DESCRIPTION
Title of Invention: ACTUATOR, OPTICALSCANNERANDIMAGEFORMING
APPARATUS
Technical Field
[OOOl]
The p r e s e n t i n v e n t i o n r e l a t e s t o an a c t u a t o r , an o p t i c a l
scanner, and an image forming apparatus.
Background A r t
[0002]
Actuators t h a t use t o r s i o n a l v i b r a t o r s a r e known ( f o r
example, see PTL 1).
For example, i n PTL 1, a l i g h t d e f l e c t o r is d i s c l o s e d
in which a movable p l a t e (movable p o r t i o n ) , a support frame
(support p o r t i o n ) , and one p a i r of e l a s t i c support p o r t i o n s
(connection p o r t i o n s ) t h a t support t h e movable p l a t e s o a s t o
be able t o r e v o l v e t o r s i o n a l l y w i t h r e s p e c t t o t h e support frame
are provided, and each e l a s t i c support portion is configured
by two p o s t s (beam members) .
The movable p l a t e , t h e support frame, and one p a i r of
the e l a s t i c support p o r t i o n s a r e i n t e g r a l l y formed by
performing a n i s o t r o p i c etching of a s i l i c o n s u b s t r a t e of which
t h e p r i n c i p a l face is configured by a plane (100) formed from
s i l i c o n .
[0003]
In a d d i t i o n , i n t h e l i g h t d e f l e c t o r according t o PTL 1,
themovable p l a t e forms an octagon i n a p l a n view. Themovable
p l a t e t h a t forms suchashapeinaplanviewdecreasestheweight
of the movable p l a t e a t a p o s i t i o n l o c a t e d f a r from t h e
revolving a x i s ( o s c i l l a t i o n a x i s ) , whereby t h e r e is an
advantage of decreasing t h e moment of i n e r t i a .
However, i n a case where t h e movable p l a t e having an
octagon shape i n a plan view is manufactured through
a n i s o t r o p i c etching as described above, t h e r e is a l a r g e
v a r i a t i o n i n the shape due t o t h e r e l a t i o n w i t h c r y s t a l p l a n e s .
C i t a t i o n L i s t
Patent L i t e r a t u r e
[0003]
PTL 1: JP-A-2010-79243
Summary of Invention
Technical Problem
[0005]
An o b j e c t of t h e i n v e n t i o n is t o provide a n a c t u a t o r ,
an o p t i c a l scanner, and an image forming apparatus capable of
decreasing t h e moment of i n e r t i a a t t h e t i m e of o s c i l l a t i n g
ofthemovable p o r t i o n b y decreasing t h e v a r i a t i o n i n t h e shape
of t h e movable p o r t i o n a t t h e t i m e of manufacturing.
Solution to Problem
[0006]
Such an object is achieved by the invention described
below.
An actuator according to the invention is characterized
by including: a movable portion that can oscillate around an
oscillation axis; a connection portion that extends from the
movable portion and is torsionally deformedin accordance with
oscillation ofthe movable portion; and a support portion that
supports the connection portion wherein the movable portion
forms a cross shape in a plan view from a thickness direction
of the movable portion.
According to such an actuator of the invention, the
variation in the shape of the movable portion can be decreased
in the manufacturing process. Therefore, the moment of
inertia at the time of oscillating of the movable portion can
be decreased.
[0007]
In the actuator of the invention, it is preferable that
an external shape of the movable portion in the plan view from
the thickness direction is mainly configuredby a segment that
is parallel to the oscillation axis and a segment that is
vertical to the oscillation axis.
Accordingly, the variation in the shape of the movable
portion in the manufacturing process can be decreased.
In the actuator of the invention, it is preferable that
the movable portion, the support portion, and the connection
portion are formed by performing anisotropic etching of a
silicon substrate.
Accordingly, the variation in the shape is decreased,
and accordingly, themovable portion, the support portion, and
one pair of the connection portions can be easily formed.
[0008]
In the actuator of the invention, it is preferable that
a plate face of the movable portion is configured by a plane
(100) of silicon.
Accordingly, by performing anisotropic etching for a
silicon substrate of which the plate face is configured by a
plane (loo), the variation in the shape can be decreased,
whereby the movable portion, the support portion, and one pair
of the connection portions can be easily formed.
[0009]
In the actuator of the invention, it is preferable that
a side face of the movable portion is mainly configured by a
plane (111) of silicon.
Accordingly, by performing anisotropic etching for a
silicon substrate of which the plate face is configured by a
plane (loo), the variation in the shape can be decreased by
using the plane (111) of silicon as an etching stopping layer.
Therefore, the movable portion, the support portion, and one
p a i r of t h e connection p o r t i o n s can be e a s i l y formed.
[OOlO]
In t h e a c t u a t o r of t h e invention, it is p r e f e r a b l e t h a t
on the s i d e face of t h e movable p o r t i o n , a groove t h a t forms
a "V" shape a t a c r o s s - s e c t i o n t h a t is perpendicular t o t h e
p l a t e face of the movable portion is formed.
A c c o r d i n g l y , t h e m o m e n t o f i n e r t i a o f t h e m o v a b l e p o r t i o n
canbedecreased. I n a d d i t i o n , f o r s u c h a g r o o v e , byperforming
a n i s o t r o p i c etching f o r a s i l i c o n s u b s t r a t e of which t h e p l a t e
face is configured by a plane (100), t h e v a r i a t i o n i n t h e shape
can be decreased by using t h e plane (111) of s i l i c o n a s an
etching stopping l a y e r . Therefore, t h e movable p o r t i o n can
be e a s i l y formed.
I n t h e a c t u a t o r of the invention, it is p r e f e r a b l e t h a t
a surface of t h e connection p o r t i o n is configured by a plane
(100) of s i l i c o n and a plane (111) of s i l i c o n .
Accordingly, by using t h e plane (111) of s i l i c o n a s an
etching stopping l a y e r , t h e v a r i a t i o n i n t h e shape i s d e c r e a s e d ,
whereby t h e connection portion can be e a s i l y formed.
[OOll]
I n t h e a c t u a t o r of t h e i n v e n t i o n , it is p r e f e r a b l e t h a t
t h e movable portion forms a shape t h a t is symmetrical with
r e s p e c t t o t h e o s c i l l a t i o n a x i s of t h e movable p o r t i o n i n t h e
plan view from t h e t h i c k n e s s d i r e c t i o n .
Accordingly, t h e g r a v i t y c e n t e r of t h e movable p o r t i o n
is located on the o s c i l l a t i o n a x i s of t h e movable p o r t i o n , and
the o s c i l l a t i o n of t h e movable p o r t i o n can be smooth.
In t h e a c t u a t o r of t h e invention, it is p r e f e r a b l e t h a t
the movable portion forms a shape t h a t is symmetrical with
respect t o a segment t h a t p a s s e s through t h e c e n t e r of t h e
movable portion i n t h e plan view from t h e t h i c k n e s s d i r e c t i o n
and is v e r t i c a l t o t h e o s c i l l a t i o n a x i s ofthemovable p o r t i o n .
Accordingly, t h e design of t h e movable p o r t i o n can be
e a s i l y performed.
[0012]
The a c t u a t o r of t h e i n v e n t i o n i s c h a r a c t e r i z e d by
including: a movable p o r t i o n t h a t can o s c i l l a t e around an
o s c i l l a t i o n a x i s ; a connection p o r t i o n t h a t extends from t h e
movable p o r t i o n a n d is t o r s i o n a l l y deformedin accordance with
o s c i l l a t i o n o f t h e m o v a b l e portion; and a support p o r t i o n t h a t
supports t h e connection portion, wherein the movable p o r t i o n
forms a shape acquired by e l i m i n a t i n g f o u r c o r n e r p o r t i o n s ,
which a r e i n rectangular shapes, of a r e c t a n g l e i n t h e plan
view from t h e t h i c k n e s s d i r e c t i o n of t h e movable p o r t i o n .
According t o such an a c t u a t o r of t h e i n v e n t i o n , t h e
v a r i a t i o n i n t h e shape of t h e movable p o r t i o n i n t h e
manufacturing process can be decreased, whereby t h e moment of
i n e r t i a a t t h e time of o s c i l l a t i n g t h e movable p o r t i o n can be
decreased.
[0013]
An o p t i c a l scanner of t h e invention is c h a r a c t e r i z e d by
including: a movable p o r t i o n t h a t i n c l u d e s a l i g h t r e f l e c t i n g
portion having l i g h t r e f l e c t i v i t y and can o s c i l l a t e around an
o s c i l l a t i o n a x i s ; a connection p o r t i o n t h a t extends from t h e
movable p o r t i o n and is t o r s i o n a l l y deformedin accordance with
o s c i l l a t i o n o f t h e movable portion; and a support p o r t i o n t h a t
supports t h e connection p o r t i o n , wherein the movable p o r t i o n
forms a c r o s s shape i n a p l a n view from a thickness d i r e c t i o n
of the movable portion.
According t o t h e o p t i c a l scanner configured as above,
t h e v a r i a t i o n i n t h e shape of t h e movable p o r t i o n can be
decreasedinthemanufacturingprocess. Therefore, themoment
of i n e r t i a a t the time of o s c i l l a t i n g of t h e movable p o r t i o n
can be decreased.
[0014]
The o p t i c a l scanner of t h e i n v e n t i o n is c h a r a c t e r i z e d
by including: a movable portion t h a t includes a l i g h t
r e f l e c t i n g p o r t i o n h a v i n g l i g h t r e f l e c t i v i t y and can o s c i l l a t e
around an o s c i l l a t i o n a x i s ; a connection portion t h a t extends
from the movable p o r t i o n and is t o r s i o n a l l y deformed i n
accordance with o s c i l l a t i o n of t h e movable p o r t i o n ; and a
support p o r t i o n t h a t supports t h e connection p o r t i o n , wherein
the movable p o r t i o n forms a shape a c q u i r e d b y e l i m i n a t i n g four
corner p o r t i o n s , which a r e i n r e c t a n g u l a r shapes, of a
r e c t a n g l e i n a plan view from a t h i c k n e s s d i r e c t i o n of t h e
movable p o r t i o n .
According t o the o p t i c a l scanner configured as above,
t h e v a r i a t i o n i n the shape of the movable portion can be
decreasedinthemanufacturingpr~cess. Therefore, themoment
of i n e r t i a a t the time of o s c i l l a t i n g of t h e movable p o r t i o n
can be decreased.
[0015]
An image forming apparatus of t h e i n v e n t i o n is
characterized by including: a l i g h t source t h a t e m i t s l i g h t ;
and an o p t i c a l scanner t h a t scans l i g h t emitted from t h e l i g h t
source, whereintheopticalscannerincludes: amovableportion
t h a t includes a l i g h t r e f l e c t i n g p o r t i o n having l i g h t
r e f l e c t i v i t y and can o s c i l l a t e around an o s c i l l a t i o n a x i s ; a
connection p o r t i o n t h a t extends from t h e movable p o r t i o n and
is t o r s i o n a l l y deformedin accordance with o s c i l l a t i o n o f t h e
movable p o r t i o n ; and a support p o r t i o n t h a t supports t h e
connection p o r t i o n , wherein t h e movable p o r t i o n forms a c r o s s
shape i n a plan view from a t h i c k n e s s d i r e c t i o n of t h e movable
p o r t i o n .
According t o the image forming a p p a r a t u s c o n f i g u r e d a s
above, t h e v a r i a t i o n i n t h e shape of t h e movable p o r t i o n can
be decreased i n t h e manufacturing p r o c e s s . Therefore, t h e
moment of i n e r t i a a t t h e t i m e of o s c i l l a t i n g of t h e movable
portion can be decreased. Accordingly, a high-quality image
can be acquired a t low c o s t .
[0016]
The image forming apparatus of t h e invention is
characterized by i n c l u d i n g : a l i g h t source t h a t emits l i g h t ;
and an o p t i c a l scanner t h a t scans l i g h t emitted from t h e l i g h t
source, whereintheopticalscannerincludes: amovableportion
t h a t includes a l i g h t r e f l e c t i n g p o r t i o n having l i g h t
r e f l e c t i v i t y and can o s c i l l a t e around an o s c i l l a t i o n a x i s ; a
connection portion t h a t extends from t h e movable p o r t i o n and
is t o r s i o n a l l y deformedin accordance with o s c i l l a t i o n o f t h e
movable portion; and a s u p p o r t portion t h a t supports t h e
connection p o r t i o n , wherein t h e movable p o r t i o n forms a shape
acquired by e l i m i n a t i n g f o u r corner p o r t i o n s , which a r e i n
rectangular shapes, of a r e c t a n g l e i n a plan view from a
t h i c k n e s s d i r e c t i o n of t h e movable p o r t i o n .
According t o t h e image forming apparatus configured a s
above, the v a r i a t i o n i n t h e shape of t h e movable p o r t i o n can
be decreased i n t h e manufacturing process. Therefore, t h e
moment of i n e r t i a a t t h e t i m e of o s c i l l a t i n g of t h e movable
p o r t i o n can be decreased. Accordingly, a high-quality image
can be acquired a t low c o s t .
Brief Description of Drawings
[0017]
[Fig. 11 Fig. 1 i s a p l a n v i e w showing a n o p t i c a l scanner
( a c t u a t o r ) according t o a f i r s t embodiment of t h e invention.
[Fig. 21 Fig. 2 is a cross-sectional view taken along
line A - A shown in Fig. 1.
[Fig. 31 Fig. 3 is a plan view illustrating a movable
plate that is included in the optical scanner shown in Fig.
1.
[Fig. 41 Fig. 4 is a cross-sectional view taken along
line B - B shown in Fig. 1.
[Fig. 51 Fig. 5is apartially enlargedcross-sectional
view of the optical scanner shown in Fig. 4.
[Fig. 61 Fig. 6 is a cross-sectional view illustrating
a method of manufacturing the optical scanner shown in Fig.
1.
[Fig. 71 Fig. 7 is a cross-sectional view illustrating
a method of manufacturing the optical scanner shown in Fig.
1.
[Fig. 81 Fig. 8 is a cross-sectional view illustrating
a method of manufacturing the optical scanner shown in Fig.
1.
[Fig. 91 Fig. 9 is a diagram illustrating the formation
of a connection portion in an etching process shown in Fig.
8(e) (in a case where there is no mask misalignment).
[Fig. 101 Fig. 10 is a diagram illustrating the
formation of a connection portion in an etching process shown
in Fig. 8(e) (in a case where there is mask misalignment).
[Fig. 111 Fig. 11 is a plan view showing an optical
scanner according to a second embodiment of the invention.
[Fig. 121 Fig. 12 is a partially enlarged
cross-sectional view taken along line B - B shown in Fig. 11.
[Fig. 131 Fig. 13 is a plan view illustrating a movable
plate that is included in a scanner according to a third
embodiment of the invention.
[Fig. 141 Fig. 14 is a plan view illustrating a movable
plate that is included in a scanner according to a fourth
embodiment of the invention.
[Fig. 151 Fig. 15 is a schematic diagram showing an
example of the configuration of an image forming apparatus
according to the invention.
Description of Embodiments
[0018]
Hereinafter, actuators, optical scanners, and image
forming apparatuses according to preferred embodiments ofthe
inventionwillbe describedwith reference tothe accompanying
drawings. In this embodiment, a case will be described as an
example in which an actuator according to the invention is
applied to an optical scanner.

First, anopticalscanneraccordingtoa first embodiment
of the invention will be described.
Fig. 1 is a plan view showing an optical scanner
(actuator) according to a first embodiment of the invention.
Fig. 2 is a cross-sectional view taken along line A - A shown
in Fig. 1. Fig. 3 is a plan view illustrating a movable plate
that is included in the optical scanner shown in Fig. 1. Fig.
4 is a cross-sectional view taken along line B - B shown in
Fig. 1. Fig. 5 is a partially enlarged cross-sectional view
of the optical scanner shown in Fig. 4. Fig. 6 is a
cross-sectional view illustrating a method of manufacturing
the optical scanner shown in Fig. 1. Fig. 7 is a
cross-sectional view illustrating a method of manufacturing
the optical scanner shown in Fig. 1. Fig. 8 is a
cross-sectional view illustrating a method of manufacturing
the optical scanner shown in Fig. 1. Fig. 9 is a diagram
illustrating the formation of a connection portion in an
etching process shown in Fig. 8 (e) (in a case where there is
no mask misalignment). Fig. 10 is a diagram illustrating the
formation of a connection portion in an etching process shown
in Fig. 8 (e) (in a case where there is mask misalignment) .
Hereinafter, for convenience of the description, in Figs. 2,
4 to 10, the upper side is referred to as "up", and the lower
side is referred to as "low".
[0020]
As shown in Fig. 1, the optical scanner 1 includes: a
base body 2 that has a vibration system; a support body 3 that
supports the base body 2; and a driving unit 4 that vibrates
t h e v i b r a t i o n system of the base body 2.
In a d d i t i o n , t h e base body 2 includes a movable p l a t e
(movable p o r t i o n ) 21 i n which a l i g h t r e f l e c t i n g p o r t i o n 211
i s disposed, one p a i r of connection p o r t i o n s 23 and 24 t h a t
a r e connected t o t h e movable p l a t e 21, and a s u p p o r t p o r t i o n
22 t h a t supports t h e one p a i r of connection p o r t i o n s 23 and
24. The support portion 22 may be described a s supporting t h e
movable p l a t e 21 through t h e connection p o r t i o n s 23 and 24,
and t h e one p a i r of connection p o r t i o n s 23 and 24 may be
described as connecting t h e movable p l a t e 21 and t h e support
portion 22.
In t h e o p t i c a l scanner 1, depending on t h e d r i v i n g f o r c e
of the driving u n i t 4 , while t h e connection p o r t i o n s 23 and
24 a r e t o r s i o n a l l y deformed, t h e movable p l a t e 2 1 is revolved
around a predetermined a x i s along t h e connection p o r t i o n s 23
and 24. Accordingly, l i g h t r e f l e c t e d by t h e l i g h t r e f l e c t i n g
portion 211 can be scanned i n one predetermined d i r e c t i o n .
[0021]
H e r e i n a f t e r , p o r t i o n s t h a t configure t h e o p t i c a l scanner
1 w i l l be s e q u e n t i a l l y described i n d e t a i l .
[Base Body]
Thebasebody2, a s describedabove, includesthemovable
p l a t e 2 1 i n which t h e l i g h t r e f l e c t i n g p o r t i o n 2 1 1 i s disposed,
t h e support p o r t i o n 22 t h a t supports t h e movable p l a t e 21, and
t h e one p a i r o f connection p o r t i o n s 23 and 24 t h a t connect t h e
movable p l a t e 21 and t h e support portion 22.
[0022]
Thebasebody2iscomposedof s i l i c o n a s i t s m a i n m a t e r i a l ,
and the movable p l a t e 21, t h e support p o r t i o n 22, and t h e
connection p o r t i o n s 23 and 24 a r e i n t e g r a l l y formed. More
s p e c i f i c a l l y , t h e base body 2, a s described i n d e t a i l l a t e r ,
is formed by performing a n i s o t r o p i c e t c h i n g of a s i l i c o n
s u b s t r a t e o f which t h e p l a t e face is c o n f i g u r e d b y a p l a n e (100)
of s i l i c o n . By performing such a n i s o t r o p i c e t c h i n g , t h e
movable p l a t e 21, t h e support p o r t i o n 22, and t h e one p a i r of
connection p o r t i o n s 23 and 24 can be formed i n a simple manner
with high p r e c i s i o n by using t h e plane (111) of s i l i c o n a s an
etching stopping l a y e r . Here, g e n e r a l l y , as t h e s i l i c o n
s u b s t r a t e , a monocrystalline s i l i c o n s u b s t r a t e is used.
In a d d i t i o n , t h e upper f a c e and t h e lower face of t h e
base body 2 a r e r e s p e c t i v e l y configured by t h e plane (100) of
s i l i c o n . I n a d d i t i o n , t h e i n n e r p e r i p h e r a l f a c e o f t h e support
p o r t i o n 22, the s i d e face o f t h e movable p l a t e 21, a n d p o r t i o n s
of s i d e faces of t h e connection p o r t i o n s 23 and 24 t h a t a r e
p a r a l l e l t o the a x i a l l i n e X a r e r e s p e c t i v e l y configured by
a p l a n e (111) of s i l i c o n .
[0023]
Furthermore, t h e s i l i c o n is light-weight and has
r i g i d i t y t o the l e v e l of SUS. Thus, s i n c e t h e base body 2 is
composedof s i l i c o n a s i t s m a i n m a t e r i a l , t h e b a s e b o d y 2 having
e x c e l l e n t v i b r a t i o n c h a r a c t e r i s t i c s can be acquired. In
a d d i t i o n , s i l i c o n can be processed with high dimensional
p r e c i s i o n by etching a s described l a t e r . Thus, by forming t h e
base body 2 using a s i l i c o n s u b s t r a t e , t h e base body 2 having
a d e s i r e d shape ( d e s i r e d v i b r a t i o n c h a r a c t e r i s t i c s ) can be
acquired.
100241
Hereinafter, t h e base body 2 w i l l be described i n more
d e t a i l .
The support p o r t i o n 22, a s shown i n Fig. 1, has a frame
shape. More s p e c i f i c a l l y , t h e support p o r t i o n 22 forms a
square ring shape. The support p o r t i o n 2 2 supportsthemovable
p l a t e 21 through one p a i r of t h e connection p o r t i o n s 23 and
24. The shape of t h e support p o r t i o n 22 is not p a r t i c u l a r l y
l i m i t e d a s long as it can support t h e movable p l a t e 21 through
t h e one p a i r of connection p o r t i o n s 23 and 24. Thus, f o r
examplefthe supportportion22mayhavea shape t h a t is divided
i n correspondence with the connection p o r t i o n s 23 and 24.
On t h e inner s i d e of t h e support p o r t i o n 22, t h e movable
p l a t e 21 i s disposed.
[0025]
The movable p l a t e 21 forms a p l a t e shape. In t h i s
embodiment, t h e movable p l a t e 21 has a shape ( a c r o s s shape)
acquired by removing four corners from a r e c t a n g l e ( i n t h i s
embodiment, a square) i n t h e p l a n view from t h e d i r e c t i o n of
the plate thickness of the movable plate 21. Accordingly,
while the area (light reflecting area) of the light reflecting
portion 211 disposed on the upper face of the movable plate
21 is sufficiently secured, the moment of inertia at the time
of revolving of the movable plate 21 can be decreased. In
addition, as described in detail later, by performing
anisotropic etching of a silicon substrate, the movable plate
21 can be formed with high precision in a simple manner.
[0026]
More specifically, as shown in Fig. 3, the movable plate
21 is configured by a main body portion 212, one pair of
p r o t r u s i o n s 2 1 3 a n d 2 1 4 t h a t p r o t r u d e fromthemainbodyportion
212 to both sides in a direction parallel to the axial line
X, and one pair of protrusions 215 and 216 that protrude from
the main body portion 212 to both sides in a direction (a
direction parallel to a segment Y) perpendicular to the axial
line X. Accordingly, the movable plate 21 forms a cross shape
in the plan view from the plate thickness direction.
[0027]
In addition, between the protrusion 213 and the
protrusion 215 in a direction extending along the outer
periphery of the movable plate 21, a deficient portion 251 is
formed. Between the protrusion 213 and the protrusion 216 in
the direction extending along the outer periphery of the
movable plate 21, a deficient portion 252 is formed. In
addition, between t h e p r o t r u s i o n 214 and t h e p r o t r u s i o n 216
i n t h e d i r e c t i o n extending along t h e o u t e r periphery of t h e
movable p l a t e 21, a d e f i c i e n t portion 254 is formed. Between
the protrusion 214 and t h e p r o t r u s i o n 215 i n t h e d i r e c t i o n
extending along the o u t e r periphery of t h e movable p l a t e 21,
a d e f i c i e n t portion 253 i s formed.
In other words, i n t h e plan view from t h e p l a t e t h i c k n e s s
d i r e c t i o n of t h e movable p l a t e 21, along t h e o u t e r periphery
of the movable p l a t e 21, t h e d e f i c i e n t p o r t i o n 251, t h e
protrusion 213, the d e f i c i e n t p o r t i o n 252, t h e p r o t r u s i o n 216,
t h e d e f i c i e n t portion 254, t h e p r o t r u s i o n 214, t h e d e f i c i e n t
portion 252, and the p r o t r u s i o n 215 a r e disposed so as t o be
aligned i n t h i s order.
[0028]
In a d d i t i o n , t h e d e f i c i e n t p o r t i o n 2 5 1 a n d t h e d e f i c i e n t
portion 252 face each o t h e r through t h e p r o t r u s i o n 213. The
d e f i c i e n t portion 252 and t h e d e f i c i e n t p o r t i o n 254 face each
other through the p r o t r u s i o n 216. In a d d i t i o n , t h e d e f i c i e n t
portion 253 and t h e d e f i c i e n t p o r t i o n 254 face each o t h e r
through t h e p r o t r u s i o n 214. The d e f i c i e n t p o r t i o n 251 and t h e
d e f i c i e n t p o r t i o n 253 f a c e each o t h e r through t h e p r o t r u s i o n
215.
Each one of t h e p r o t r u s i o n s 213 t o 216 and t h e d e f i c i e n t
portions 251 t o 254 forms a r e c t a n g l e i n t h e plan view from
t h e p l a t e thickness d i r e c t i o n o f t h e m o v a b l e p l a t e 21. In Figs.
l a n d 3, a s t a t e is i l l u s t r a t e d as an example inwhich the shape
i n the plan view of each one of t h e d e f i c i e n t p o r t i o n s 251 t o
254 forms a square. In each corner of t h e e x t e r n a l c r o s s shape
ofthemovable p l a t e 21, n o t o n l y a p r e d e t e r m i n e d c r y s t a l plane
but a l s o a p l u r a l i t y of c r y s t a l p l a n e s a p p e a r . Accordingly,
each corner portion does not p r e c i s e l y form a r i g h t angle, and
each one of t h e d e f i c i e n t p o r t i o n s 251 t o 254 is not a p r e c i s e
r e c t a n g l e . However, i n t h i s embodiment, it is assumed t h a t
each one of t h e d e f i c i e n t p o r t i o n s 251 t o 254 is a r e c t a n g l e
t h a t includes t h e above-described s t a t e .
[0029]
The e x t e r n a l shape of t h e movable p l a t e 21 i n t h e plan
view from t h e p l a t e t h i c k n e s s d i r e c t i o n is mainly configured
by a segment t h a t is p a r a l l e l t o t h e revolving c e n t e r a x i s ( t h e
a x i a l l i n e X) of t h e movable p l a t e 21 and a segment (segment
Y ) thatisperpendiculartotherevolvingcenteraxis ( t h e a x i a l
l i n e X) of t h e movable p l a t e 21. Accordingly, as described
l a t e r , b y p e r f o r m i n g a n i s o t r o p i c e t c h i n g o f a s i l i c o n s u b s t r a t e ,
t h e movable p l a t e 21 can be formed with high p r e c i s i o n i n an
easy manner. In a d d i t i o n , on t h e corner of t h e e x t e r n a l c r o s s
shape ofthemovable p l a t e 21, notonlyapredeterminedcrystal
p l a n e b u t a l s o a p l u r a l i t y of c r y s t a l planes appear.
Accordingly, t h e e x t e r n a l shape of t h e corner p o r t i o n i n t h e
plan view from t h e p l a t e t h i c k n e s s d i r e c t i o n of t h e movable
p l a t e 21 is n o t n e c e s s a r i l y a segment t h a t i s p a r a l l e l t o t h e
a x i a l l i n e X or t h e segment Y. In other words, t h e e x t e r n a l
shape of t h e movable p l a t e 21 i n t h e plan view from t h e p l a t e
thickness d i r e c t i o n is configuredby a segment p a r a l l e l t o t h e
a x i a l l i n e X and a segment p a r a l l e l t o t h e segment Y except
f o r a t l e a s t t h e corners of t h e movable p l a t e 21.
I n a d d i t i o n , the movable p l a t e 21 forms a shape t h a t i s
symmetrical with respect t o t h e revolving c e n t e r a x i s ( t h e
a x i a l l i n e X) of the movable p l a t e 21 i n t h e plan view.
Accordingly, t h e g r a v i t y c e n t e r of t h e movable p l a t e 21 is
e a s i l y positioned on t h e revolving c e n t e r a x i s of t h e movable
p l a t e 21, whereby t h e revolving of t h e movable p l a t e 21 can
be smooth.
[00301
Furthermore, themovable p l a t e 21has a shape t h a t passes
through t h e c e n t e r P of t h e movable p l a t e 21 i n t h e plan view
and is symmetrical with r e s p e c t t o t h e segment Y t h a t is
perpendicular t o t h e revolving c e n t e r a x i s ( t h e a x i a l l i n e X)
o f t h e m o v a b l e p l a t e 2 1 . Accordingly, t h e d e s i g n o f t h e m o v a b l e
p l a t e can be performed i n an easy manner.
In a d d i t i o n , the p l a t e face of t h e movable p l a t e 21 is
configured by t h e plane (100) of s i l i c o n . Accordingly, as
d e s c r i b e d l a t e r , byperforminganisotropicetchingofasilicon
s u b s t r a t e of which t h e p l a t e face is c o n f i g u r e d b y a p l a n e (100),
t h e movable p l a t e 21, t h e support p o r t i o n 22, and t h e one p a i r
of connection p o r t i o n s 23 and 24 can be formed w i t h h i g h
precision in a simple manner.
[0031]
Furthermore, the side face of the movable plate 21 is
mainly configuredbytheplane (111) of silicon. Accordingly,
as described later, by performing anisotropic etching of a
silicon substrate of which the plate face is configured by a
plane (100) , the movable plate 21, the support portion 22, and
one pair of the connection portions 23 and 24 can be formed
with high precision in a simple manner by using the plane (111)
of silicon as an etching stopping layer. In addition, on the
corners of the external shape in the plan view from the plate
thickness direction of the movable plate 21, the side face of
the movable plate 21 includes a crystal plane other than the
plane (111). Accordingly, the side face of the movable plate
21 is configured by the plane (111) of silicon except for at
least the side face on the corner.
[0032]
In addition, on the side face of the movable plate 21,
a groove 217 of which the horizontal cross-section forms a 'V"
shape is formed. Accordingly, the moment of inertia of the
movable plate 21 can be decreased. In addition, by performing
anisotropic etching of a silicon substrate of which the plate
face is configured by a plane (loo), the groove can be formed
with high precision in a simple manner by using the plane (111)
of silicon as an etching stopping layer.
[0033]
In addition, when the length of the movable plate 21 in
a direction (hereinafter, also referred to as a "segment Y
direction") vertical to the revolving center axis (axial line
X) in the plan view from the direction of the plate thickness
is A, the length of the movable plate 21 in a direction
(hereinafter, also referred to as an "axial line X direction")
parallel to the revolving center axis (the axial line X) is
B, the length of each one of the deficient portions 251 to 254
in the segment Y direction is a, and the length of each one
of the deficient portions 251 to 254 in the axial line X
direction is b, the following Expressions (A) and (B) are
satisfied.
[0034]
[Mathematical 11
[0035]
By satisfying Expressions (A) and (B) described above,
while the area of the light reflecting portion 211 of the
movable plate 21, which is necessary for light reflection, is
secured, the moment of i n e r t i a a t the t i m e of revolving t h e
movable p l a t e 21 can be e f f i c i e n t l y decreased.
In c o n t r a s t t o t h i s , i n a case where t h e lengths a and
b are l e s s than t h e above-described lower l i m i t s , t h e e f f e c t
of decreasing the moment of i n e r t i a a t t h e time of revolving
t h e m o v a b l e p l a t e 2 1 t e n d s t o b e small. Accordingly, depending
pn t h e thickness of t h e movable p l a t e 21, t h e movement bending
o f t h e m o v a b l e p l a t e 2 1 i n c r e a s e s , whereby t h e r e is a casewhere
the o p t i c a l c h a r a c t e r i s t i c s of t h e o p t i c a l scanner 1
d e t e r i o r a t e .
[0036]
On t h e other hand, i n a case where t h e lengths a and b
exceed t h e above-described upper l i m i t s , t h e area of t h e l i g h t
r e f l e c t i n g portion 211 of t h e movable p l a t e 21 can not be
e f f i c i e n t l y used, and t h e i n t e n s i t y of l i g h t r e f l e c t e d from
t h e l i g h t r e f l e c t i n g p o r t i o n 211 tends t o be low.
In a d d i t i o n , i n Fig. 3, i n a case where Expressions (A)
and (B) described above a r e s a t i s f i e d , a movable p l a t e 21A of
a case where the lengths a and b a r e r e s p e c t i v e l y maximums,
and a movable p l a t e 21B of a case where t h e l e n g t h s a and b
a r e r e s p e c t i v e l y minimums a r e denoted by d o t t e d l i n e s .
[0037]
H e r e i n a f t e r , Expressions (A) and (B) w i l l be b r i e f l y
described.
As shown i n Fig. 3, i n a case where a spot of l i g h t L
having a c i r c u l a r shape or an oval shape is i n s c r i b e d i n t h e
movable p l a t e 21 i n t h e plan view, t h e area of each one of t h e
d e f i c i e n t p o r t i o n s 251 t o 254 is t h e maximum outside t h e spot
of l i g h t L when a = ( 1 - 1 / 4 2 ) ~a nd b = ( 1 - 1 / 4 2 ) ~ .
In a d d i t i o n , i n such a case, the length a is the maximum,
and the length b is the minimum i n a range i n which t h e e f f e c t
of t h e formation of the d e f i c i e n t p o r t i o n s 251 t o 254 i s
acquired when t h e corner P3 of each one of t h e d e f i c i e n t
p o r t i o n s 2 5 1 t o 2 5 4 i s l o c a t e d a t a n i n t e r s e c t i o n P 2 ofasegment
t i l t i n g with r e s p e c t t o t h e a x i a l l i n e X by 30 degrees and t h e
outer circumference of t h e spot of l i g h t L.
[0038]
In a d d i t i o n , i n such a case, t h e length a is t h e minimum,
and the l e n g t h b is themaximumin t h e range i n which t h e e f f e c t
of t h e formation of t h e d e f i c i e n t p o r t i o n s 251 t o 254 is
acquired when t h e corner P3 of each one of t h e d e f i c i e n t
p o r t i o n s 2 5 1 t o 2 5 4 i s l o c a t e d a t a n i n t e r s e c t i o n P 1 o f a s e g m e n t
t i l t i n g with r e s p e c t t o t h e a x i a l l i n e X by 60 degrees and t h e
o u t e r circumference of t h e spot of l i g h t L.
[0039]
Furthermore, g e n e r a l l y , t h e e f f e c t i v e range o f t h e
diameter o f t h e spot of a l a s e r beam t h a t is commonly used as
l i g h t L is regarded as a range i n which t h e diameter is equal
t o or l a r g e r than l / e 2 of t h e peak luminance. Accordingly, i n
a case where t h e e f f e c t i v e range is i n s i d e t h e l i g h t r e f l e c t i n g
portion 211, ideal light reflection can be performed.
However, even in a case where the diameter of the spot
of an actual laser beam is outside the above-described
effective range, a small quantity of light is present therein.
Thus, even in a case where the lengths a and b are a little
bit larger or smaller than the above-described values, the
laser beam can be allowed for practical use without problems.
More specifically, the allowed values of the lengths a
and b acquired as described above can be set to be -20% or more
and +200% or less.
[0040]
As above, Expressions (A) and (B) described above can
be acquired.
On the upper face of the movable plate 21, the light
reflecting portion 211having light reflectivity is disposed.
On the other hand, on the lower face of the movable plate 21,
a permanent magnet 41 of the driving unit 4 to be described
later is disposed. In addition, the permanent magnet 41 will
be described in detail in the description of the driving unit
4 to be described later.
Each of the connection portions 23 and 24 forms a
rectangular shapeandis configuredtobeelasticallydeformed.
In addition, the connection portion 23 and the connection
portion 24 face each other through the movable plate 21. The
connection portions 23 and 24 connect the movable plate 21 and
the support portion 22 such t h a t t h e movable p l a t e 21 can
revolve around the support p o r t i o n 22. One p a i r of t h e
connection portions 23 and 24 is disposed so a s t o have t h e
same a x i s extending along the a x i a l l i n e X, and t h e movable
p l a t e 2 1 r e v o l v e s w i t h respect t o t h e support p o r t i o n 22 around
the a x i a l l i n e X as i t s revolving center a x i s .
[0041]
In t h i s embodiment, as shown i n Fig. 1, t h e connection
portion 23 is configured by one p a i r of beam members 231 and
232. Similarly, t h e connection p o r t i o n 24 is configured by
one p a i r of beam members 241 and 242. H e r e i n a f t e r , t h e
connection portion 23 w i l l be r e p r e s e n t a t i v e l y described.
Since t h e connection portion 24 is s i m i l a r t o t h e connection
portion 23, the d e s c r i p t i o n t h e r e o f w i l l be omitted.
Thebeammembers 231and232 a r e d i s p o s e d a l o n g t h e a x i a l
l i n e X a n d f a c e e a c h o t h e r t h r o u g h t h e a x i a l l i n e X . I n a d d i t i o n ,
t h e shape of t h e h o r i z o n t a l c r o s s - s e c t i o n of each one of t h e
beam members 231 and 232 forms a p a r a l l e l o g r a m .
[0042]
More s p e c i f i c a l l y , t h e e x t e r n a l shape of t h e h o r i z o n t a l
c r o s s - s e c t i o n of each one of t h e beammembers 231 and 232 forms
a p a r a l l e l o g r a m t h a t i s configuredbyonepairofsidesdisposed
along (100) of s i l i c o n and one p a i r of s i d e s disposed along
the plane (111) of s i l i c o n . In o t h e r words, i n thebeammember
231, t h e upper face 2311 and t h e lower face 2312 a r e configured
by the planes ( 1 0 0 ) of s i l i c o n , and one p a i r of s i d e f a c e s 2313
and 2314 a r e configured by t h e planes (111) of s i l i c o n .
Similarly, i n the beam member 232, t h e upper face 2321 and t h e
lower face 2322 are configured by t h e planes (100) of s i l i c o n ,
and one p a i r of side f a c e s 2323 and 2324 a r e configured by t h e
planes (111) of s i l i c o n . Here, s i n c e t h e s i d e f a c e s 2313, 2324,
2323, and 2324 are configured by t h e planes (111) of s i l i c o n ,
the tilt angle 0 with r e s p e c t t o t h e upper face or t h e lower
face ( t h a t is, the plane (100) of s i l i c o n ) of t h e base body
2 is 54.73 degrees. Each one of t h e beam members 231 and 232
t h a t configures 'the shape of t h e h o r i z o n t a l c r o s s - s e c t i o n can
be r e l i a b l y f o r m e d i n a simplemannerbyperforminganisotropic
etching o f a s i l i c o n s u b s t r a t e of which t h e p l a t e f a c e is
configured by the plane (100) of s i l i c o n .
In a case where t h e outer s u r f a c e of t h e connection
portion 23 is configured by t h e plane (100) of s i l i c o n and t h e
plane (111) of s i l i c o n , t h e connection portion 23 can be formed
with high p r e c i s i o n i n a simple manner by using t h e plane (111)
of s i l i c o n a s a n e t c h i n g stopping l a y e r , w h i c h w i l l b e d e s c r i b e d
l a t e r .
[0043]
In a d d i t i o n , t h e beam members 231 and 232, when viewed
from a d i r e c t i o n p a r a l l e l t o t h e a x i a l l i n e X ( i n o t h e r words,
viewedat thecross-section shownin Fig. 5 ) , r e s p e c t i v e l y h a v e
a shape symmetrical t o a segment t h a t v e r t i c a l l y extends and
passes through the a x i a l l i n e X.
In addition, i n the cross-section shown i n Fig. 5, the
e n t i r e width (a distance between the s i d e face 2313 of the beam
member 231 and the side face 2323 of the beam member 232) of
the connection portion 23 is increased from the lower side
toward the upper s i d e . I n t h e cross-section shown i n Fig. 5,
a distance (the width of a gap) between the beam member 231
and the beammember 232 is increased fromthe lower s i d e toward
the upper s i d e .
[0044]
In other words, the distancebetweenone p a i r ofthebeam
members 231 and 232, when viewed from a d i r e c t i o n p a r a l l e l t o
the revolving center axis ofthemovable p l a t e 21, is gradually
increased from one face s i d e of .the movable p l a t e 21 toward
t h e o t h e r face side ( i n t h i s embodiment, from the lower s i d e
toward the upper s i d e ) .
When a distance between lower-side ends of the one p a i r
of beam members 231 and 232 i s W1, and the thickness t of one
p a i r o f t h e beammembers 231 and 232 i n t h e thickness d i r e c t i o n
of the movable p l a t e 21 is t, the following Expression (1) is
s a t i s f i e d .
[0045]
[Mathematical 21
[0046]
As d e s c r i b e d i n d e t a i l l a t e r , s i n c e a n i s o t r o p i c e t c h i n g
is performed f o r a s i l i c o n s u b s t r a t e of which t h e p l a t e face
i s c o n f i g u r e d b y t h e p l a n e (100) of s i l i c o n fromboth face s i d e s
t h e r e o f , t h e r e is a case where formation p o s i t i o n s of masks
formed on b o t h f a c e s of t h e s i l i c o n s u b s t r a t e a r e misaligned
when the movable p l a t e 21, t h e support p o r t i o n 22, and one p a i r
of the connection p o r t i o n s 23 and 24 a r e formed. When t h e
formation p o s i t i o n s of masks on both f a c e s of t h e s i l i c o n
s u b s t r a t e a r e misaligned, l e v e l d i f f e r e n c e s a r e generated on
one p a i r of t h e side faces 2313 and 2314 or 2323 and 2324 of
each one of t h e beam members 231 and 232 t o be configured by
t h e planes (111) of s i l i c o n . By s a t i s f y i n g Expression (1)
described above, in a case where t h e formation p o s i t i o n s of
t h e masks formed on both f a c e s of t h e s i l i c o n s u b s t r a t e a r e
misaligned, a l e v e l d i f f e r e n c e formed on one s i d e face and a
l e v e l d i f f e r e n c e formed on t h e o t h e r s i d e face can be s h i f t e d
i n t h e t h i c k n e s s d i r e c t i o n of t h e s i l i c o n s u b s t r a t e (see Fig.
0 Accordingly, t h e c o n c e n t r a t i o n of s t r e s s generated i n
thebeammembers231and232atthetimeofrevolvingthemovable
p l a t e 21 can be a l l e v i a t e d .
As above, the o p t i c a l scanner 1 can prevent damage due
to the stress concentration at the time of driving in a
relatively simple manner.
In addition, when a distance between upper-side ends of
the one pair of beam members 231 and 232 is WZr the following
Expression (2) is satisfied.
[0047]
[Mathematical 31
[0048]
Accordingly, by performing anisotropic etching of a
silicon substrate of which the plate face is configured by the
plane (100) of silicon from both face sides thereof, the
connection portion 23 that is configured by the one pair of
beam members 231 and 232 can be reliably formed in a simple
manner.
[0049]
[Support Body]
The support body 3 has a function of supporting the
above-described base body 2. In addition, the support body
3 has a function of supporting a coil 42 of the driving unit
4 to be described later.
This support body 3 forms a box shape having a concave
portion 31 that is open on the upper side. In other words,
the support body 3 is configured by a plate shape portion 32
forming aplate shape anda frame shape portion 33, which forms
a frame shape, disposed along the outer periphery portion of
the upper face of the plate shape portion 32.
[0050]
To a portion of the upper face of the support body 3 that
is located outside the concave portion 31, that is, the upper
face ofthe frame s h a p e p o r t i o n 3 3 , t h e l o w e r f a c e o f t h e support
portion 22 of the base body 2 is bonded. Accordingly, between
the movable plate 21 of the base body 2 and one pair of the
connection portions 23 and 24 and the support body 3, a space
used for allowing the movable plate 21 to revolve is formed.
The material configuring the support body 3 is not
particularly limited. As examples of the above-described
m a t e r i a l , t h e r e a r e a g l a s s m a t e r i a l s u c h a s q u a r t z g l a s s , Pyrex
glass ("Pyrex" is a registered trademark), or Tempax glass,
a silicon material such as monocrystalline silicon or
polysilicon, LTCC (Low Temperature Co-fired Ceramic), and the
like.
The method of bonding the base body 2 and the support
body 3 to each other may be appropriately determined in
accordance with the composition material, the shape, and the
like of the support body 3 and is not particularly limited.
As examples of the bonding method, there are a method using
an adhesive, an anodic bonding method, and a direct bonding
method, and the l i k e .
[0051]
[Driving Unit]
The driving u n i t 4 includes t h e permanent magnet 4 1 and
a c o i l 42 and drives t h e movable p l a t e 21 of t h e base body 2
t o revolve by using a n electromagnetic driving system (more
p a r t i c u l a r l y , an electromagnetic d r i v i n g system of a moving
magnet t y p e ) . The electromagnetic d r i v i n g s y s t e m c a n g e n e r a t e
a l a r g e driving f o r c e . Thus, according t o t h e d r i v i n g u n i t
4 t h a t employs t h e electromagnetic driving system, t h e
d e f l e c t i o n angle ofthemovable p l a t e 21 can be i n c r e a s e d w h i l e
a low driving voltage is achieved.
[0052]
The permanent magnet 4 1 i s f i x e d t o t h e lower face of
t h e movable p l a t e 21, f o r example, through an adhesive. In
a d d i t i o n , t h e permanent magnet 4 1 forms a r e c t a n g u l a r shape
and is disposed so a s t o extend i n a d i r e c t i o n p e r p e n d i c u l a r
t o t h e a x i a l l i n e X i n t h e plan view. The permanent magnet
4 1 is magnetized i n t h e l o n g i t u d i n a l d i r e c t i o n , and one s i d e
thereof i n t h e l o n g i t u d i n a l d i r e c t i o n is t h e south pole, and
t h e other s i d e t h e r e o f is t h e north pole. By disposing t h e
permanentmagnet41so as t o e x t e n d i n a d i r e c t i o n p e r p e n d i c u l a r
t o t h e a x i a l l i n e XI both end p o r t i o n s of t h e permanent magnet
4 1 c a n b e l o c a t e d f a r fromthe a x i a l l i n e x . Accordingly, based
on t h e a c t i o n of a magnetic f i e l d generated by t h e c o i l 42,
a l a r g e torque can be given by t h e movable p l a t e 21.
[0053]
Such a permanent magnet 4 1 is not p a r t i c u l a r l y l i m i t e d .
Thus, f o r example, a hard magnet such as a neodymium magnet,
a f e r r i t e magnet, a samarium-cobalt magnet, an a l n i c o magnet,
or a bond magnet t h a t is magnetized can be a p p r o p r i a t e l y used.
The c o i l 42 is disposed so a s t o face t h e movable p l a t e
2 1 o n t h e b o t t o m f a c e 3 1 1 o f t h e c o n c a v e p o r t i o n 3 1 o f t h e s u p p o r t
body 3. Accordingly, a magnetic f i e l d generated by t h e c o i l
42 canbe e f f e c t i v e l y a p p l i e d t o t h e permanentmagnet 4 1 . This
c o i l 42 is e l e c t r i c a l l y connected t o a power source not shown
i n t h e f i g u r e , and a p e r i o d i c a l l y a l t e r n a t i n g v o l t a g e (an AC
voltage, an i n t e r m i t t e n t d i r e c t c u r r e n t , or t h e l i k e ) i s
applied t o the c o i l 42 from t h e power source.
[0054]
The movable p l a t e 21 revolves as follows due t o t h e
driving u n i t 4 .
F i r s t , f o r example, an AC v o l t a g e is a p p l i e d t o t h e c o i l
42 by t h e power source not shown i n t h e f i g u r e . Accordingly,
a f i r s t magnetic f i e l d i n which t h e upper s i d e ( t h e movable
p l a t e 21 s i d e ) of t h e c o i l 42 is t h e north pole, and t h e lower
s i d e thereof is t h e south pole and a second magnetic f i e l d i n
which t h e upper s i d e of t h e c o i l 42 is t h e south pole, and t h e
lower s i d e thereof is t h e n o r t h p o l e a r e g e n e r a t e d a l t e r n a t e l y
and p e r i o d i c a l l y .
In t h e f i r s t e l e c t r i c f i e l d , t h e movable p l a t e 21
revolves around the a x i a l l i n e X counterclockwise i n Fig. 2
such t h a t t h e north pole side of t h e permanent magnet 4 1 i s
a t t r a c t e d t o t h e c o i l 4 2 , a n d t h e s o u t h p o l e s i d e is drawn a p a r t
from t h e c o i l 42 ( f i r s t s t a t e ) . In c o n t r a s t , i n t h e second
e l e c t r i c f i e l d , the movable p l a t e 21 revolves around t h e a x i a l
l i n e X clockwise i n Fig. 2 such t h a t t h e south pole s i d e of
the permanent magnet 4 1 i s a t t r a c t e d t o t h e c o i l 42, and t h e
north pole s i d e is drawn a p a r t from t h e c o i l 42 (second s t a t e ) .
By a l t e r n a t e l y repeating t h e f i r s t s t a t e and t h e second s t a t e ,
the movable p l a t e 21 revolves around t h e a x i a l l i n e X.
[0055 1
(Method of Manufacturing Actuator)
The above-described o p t i c a l scanner 1 can be
manufactured, f o r example, as follows. H e r e i n a f t e r , a s an
example of the method of manufacturing an a c t u a t o r according
t o t h e invention, amethodofmanufacturingthe o p t i c a l scanner
1 w i l l be described with reference t o Figs. 6 t o 10. Figs.
6 t o 8 show c r o s s - s e c t i o n s corresponding t o Fig. 2, and Figs.
9 t o 10 show c r o s s - s e c t i o n s corresponding t o Fig. 5.
The method of manufacturing t h e o p t i c a l scanner 1
includes a process of forming t h e base body 2.
The process of forming t h e base body 2 includes: [A] a
process of forming t h e concave p o r t i o n 218; and [B] a process
of forming the movable p l a t e 21, t h e support p o r t i o n 22, and
one pair of the connection portions 23 and 24.
[0056]
Hereinafter, the processes will be sequentially
described in detail.
[A] Process of Forming Concave Portion 218
-Al-
First, as shown in Fig. 6(a), a silicon substrate 102
is prepared.
This silicon substrate 102 is formed as a base body 2
through etching to be described later.
More specifically, the principal face of the silicon
substrate 102 is configured by a plane (100) of silicon.
LO0571
-A2 -
Next, as shown in Fig. 6 (b) , a nitride film 51 is formed
ontheupper face ofthe silicon substrate102, and on the lower
face of the silicon substrate 102, a nitride film 52 is formed.
These nitride films 51 and 52 are, for example, composed
of SiN.
Here, the method of forming the nitride films 51 and 52
is not particularly limited. Thus, as the above-described
method, for example, a vapor-phase deposition method such as
a plasma CVD method may be used.
In addition, the thickness of the nitride films 51 and
52 is not particularly limited and is at a level that is equal
to or larger than 0.01 p and equal to or smaller than 0.2 pm.
Furthermore, instead of the nitride films 51 and 52,
oxide films composedof SiOmaybe formed, for example, by using
a thermal oxidation method.
100581
-A3-
Next, as shown in Fig. 6 (c) , a resist film 61 is formed
on the nitride film 51, and as shown in Fig. 6(d), a resist
film 62 is formed on the nitride film 52.
These resist films 61 and 62 are configured by resist
materials of a positive type or a negative type.
-A4-
Next, by exposing and developing the resist film 62, a
portion of the resist film 62 that corresponds to an area in
which the concave portion 218 is to be formed is removed.
Accordingly, as shown in Fig. 6 (e) , a resist film 62A that has
an opening 621 is acquired.
[0059 1
-A5-
Next, a part of the nitride film 52 is removed through
etching by using the resist film 62A as a mask. Accordingly,
as shown in Fig. 6 (f) , a nitride film 52A that has an opening
521 is acquired.
The above-described etching (the method of forming the
opening 521) is not particularly limited. For example,
36
r e a c t i v e ion e t c h i n g ( R I E ) o r a d r y e t c h i n g using CF4 may be
used.
[0060]
-A6-
Next, t h e resist f i l m s 61 and 62A a r e removed.
Accordingly, a s shown i n Fig. 6 ( g ) , t h e s i l i c o n s u b s t r a t e 102
i s i n a s t a t e inwhich t h e upper f a c e is c o v e r e d w i t h t h e n i t r i d e
f i l m 51, and t h e lower f a c e is covered with t h e n i t r i d e f i l m
52A.
A method of removing t h e resist f i l m s 61 and 62 is not
p a r t i c u l a r l y l i m i t e d . Thus, f o r example, c l e a n i n g u s i n g
s u l f u r i c a c i d , O2 ashing, o r t h e l i k e may be used.
[0061]
-A7 -
Next, t h e s i l i c o n s u b s t r a t e 102 is e t c h e d by using t h e
n i t r i d e f i l m 5 2 A a s amask. Accordingly, a s s h o w n i n F i g . 7 ( a ) ,
a s i l i c o n s u b s t r a t e 102A having t h e concave p o r t i o n 218 is
a c q u i r e d .
The above-described e t c h i n g (a method of forming t h e
concave p o r t i o n 218) is not p a r t i c u l a r l y l i m i t e d . S i m i l a r l y
t o e t c h i n g t h a t is performed f o r forming t h e movable p l a t e 21,
t h e support p o r t i o n 22, and t h e l i k e t o be described l a t e r ,
a n i s o t r o p i c e t c h i n g is a p p r o p r i a t e l y used.
The a n i s o t r o p i c e t c h i n g is not p a r t i c u l a r l y l i m i t e d .
Thus, f o r example, wet e t c h i n g using a KOH aqueous s o l u t i o n
or the like may be performed.
[0062]
-A8-
Next, the nitride films 51 and 52A are removed.
Accordingly, as shown in Fig. 7 (b) , a state is formed in which
the upper face and the lower face ofthe silicon substrate 102A
are exposed.
A method of removing the nitride films 51 and 52A is not
particularly limited. Thus, similarly to the process A5, for
example, reactive ion etching (RIE), dry etching using CF4,
or the like may be used.
[0063]
[B] Process of Forming Movable Plate 21, Support Portion
22, and The Like
-B1-
Next, as shown in Fig. 7 (c), a nitride film 71 is formed
on the upper face of the silicon substrate 102A, and a nitride
film 72 is formed on the lower face of the silicon substrate
102A.
These nitride films 71 and 72, for example, are composed
of SiN.
[0064]
Here, the method of forming the nitride films 71 and 72
is not particularly limited. Thus, similarly to the
above-described process A2, for example, a vapor-phase
deposition method such as a plasma CVD method may be used.
In a d d i t i o n , t h e thickness of t h e n i t r i d e f i l m s 71 and
72 i s not p a r t i c u l a r l y l i m i t e d and is a t a l e v e l t h a t is equal
t o or l a r g e r than 0.01 pm and equal t o or smaller than 0.3 p.m.
Furthermore, i n s t e a d of t h e n i t r i d e f i l m s 7 1 and 72,
oxide f i l m s composedof SiOmaybe formed, f o r example, byusing
a thermal oxidation method.
COO651
-B2-
Next, as shown i n Fig. 7 (d) , a r e s i s t f i l m 81 i s formed
on t h e n i t r i d e f i l m 71.
This r e s i s t f i l m 81 is configured by a resist m a t e r i a l
of a p o s i t i v e type or a negative type.
-B3-
Next, by exposing and developing t h e resist f i l m 81, a
p a r t of t h e r e s i s t f i l m 81 i s removed such t h a t p o r t i o n s of
t h e r e s i s t f i l m 81 t h a t correspond t o areas, i n which t h e
movable p l a t e 21, t h e support p o r t i o n 22, and one p a i r of t h e
connection p o r t i o n s 23 and 24 a r e formed, remain. Accordingly,
as shown i n F i g . 7 ( e ) , a r e s i s t f i l m 81A t h a t has an opening
8 1 1 i s acquired. Althoughnotshownin Fig. 7 ( e ) , i n t h e r e s i s t
f i l m 81A, an opening formed i n accordance with a gap betw-een
upper ends of one p a i r ofthebeammembers 231and 232 is formed
as well.
[0066]
-B4-
Next, a part of the nitride film 71 is removed through
etching by using the resist film 81A as a mask. Accordingly,
as shown in Fig. 7 (f) , a nitride film 71A that has an opening
711 is acquired. Although not shown in Fig. 7 ( 5 ) , in the
nitride film 71A, an opening formed in accordance with a gap
between upper ends of one pair of the beam members 231 and 232
is formed as well.
The above-described etching (a method of forming the
opening 711) is not particularly limited. Similarly to the
above-describedprocess AS, for example, reactive ion etching
( R I E ) or a dry etching using CF4 may be used.
[0067]
-B5-
Next, the resist film 81A is removed. Accordingly, as
shown in Fig. 7 (g), the silicon substrate 102A is in a state
in which the upper face is covered with the nitride film 71A,
and the lower face is covered with the nitride film 72.
A method of removing the resist film 81A is not
particularly limited. Thus, for example, cleaning using
sulfuric acid, O2 ashing, or the like may be used.
-B6-
Next, as shown in Fig. 8(a), a resist film 82 is formed
on the nitride film 72.
This resist film 82 is configured by a resist material
of a p o s i t i v e type or a n e g a t i v e t y p e .
-B7 -
Next, by exposing and developing t h e resist f i l m 82, a
p a r t of the resist f i l m 82 i s removed such t h a t p o r t i o n s of
the r e s i s t f i l m 82 t h a t correspond t o a r e a s , i n which t h e
movable p l a t e 21, t h e support portion 22, and one p a i r of t h e
connectionportions 23 and24 a r e formed, remain. Accordingly,
as shown i n Fig. 8 ( b ) , a resist film 82A t h a t has an opening
8 2 1 i s acquired. AlthoughnotshowninFig. 8 ( b ) , i n t h e r e s i s t
film 82A, an opening formed i n accordance with a gap between
lower ends of one p a i r ofthebeammembers 231and232 is formed
as well.
[0069]
-B8-
Next, a p a r t of t h e n i t r i d e f i l m 72 is removed through
etching by using t h e resist film 82A as a mask. Accordingly,
as shown i n Fig. 8 (c), a n i t r i d e film 72A t h a t has an opening
721 is acquired. Although not shown i n Fig. 8 ( c ) , i n t h e
n i t r i d e f i l m 72A, an opening formed i n accordance with a gap
between t h e lower ends of one p a i r of t h e beam members 231 and
232 is formed as w e l l .
The above-described etching (a method of forming t h e
opening 721) is not p a r t i c u l a r l y l i m i t e d . S i m i l a r l y t o t h e
above-describedprocess A5, f o r example, r e a c t i v e ion etching
(RIE) or a dry e t c h i n g using CF4 may be used.
[0070]
-B9-
Next, t h e resist film 82A is removed. Accordingly, a s
shown i n Fig. 8 ( d ) , t h e s i l i c o n s u b s t r a t e 102A is i n a s t a t e
i n which t h e upper f a c e i s covered w i t h t h e n i t r i d e f i l m 71A,
and t h e lower f a c e is covered with the n i t r i d e f i l m 72A.
A method of removing t h e r e s i s t f i l m 82A is not
p a r t i c u l a r l y l i m i t e d . Thus, f o r example, c l e a n i n g using
s u l f u r i c a c i d , O2 ashing, o r t h e l i k e may be used.
[0071]
-B10-
Next, a n i s o t r o p i c e t c h i n g i s performed f o r t h e s i l i c o n
s u b s t r a t e 1 0 2 A b y u s i n g t h e n i t r i d e f i l m s 71A and 72Aasmasks.
Accordingly, a s shown i n Fig. 8 (e) , a base body 2 is a c q u i r e d .
In o t h e r words, i n t h e a n i s o t r o p i c e t c h i n g i n t h i s p r o c e s s ,
byperforminganisotropicetching o f t h e s i l i c o n s u b s t r a t e 1 0 2 A
through t h e n i t r i d e f i l m 72A a s a f i r s t mask and t h e n i t r i d e
f i l m 71A a s a second mask from both f a c e s i d e s t h e r e o f , t h e
movable p l a t e 21, t h e support p o r t i o n 22, and t h e one p a i r of
connection p o r t i o n s 23 and 24 a r e formed.
The a n i s o t r o p i c e t c h i n g (a method of forming t h e base
body 2) i s not p a r t i c u l a r l y l i m i t e d . Thus, f o r example, w e t
e t c h i n g u s i n g a KOH aqueous s o l u t i o n o r t h e l i k e may be
performed.
[0072]
Here, the formation of t h e connection p o r t i o n 23 through
the a n i s o t r o p i c e t c h i n g w i l l be described i n d e t a i l . Since
the formation of t h e connection portion 24 is s i m i l a r t o t h a t
of t h e connection p o r t i o n 23, t h e d e s c r i p t i o n t h e r e o f w i l l be
omitted.
As shown i n Fig. 9, t h e n i t r i d e film 71A used a s t h e mask
(second mask) includes a portion 712 of the connection p o r t i o n
23 t h a t is formed i n correspondence with an a r e a i n which t h e
upper face of the beam member 231 is formed and a p o r t i o n 713
of t h e connection p o r t i o n 23 t h a t i s formed i n correspondence
with an area i n which t h e upper face of t h e beam member 232
is formed. In a d d i t i o n , between t h e portion 712 and t h e p o r t i o n
713, an opening 714 (second opening) is formed. This opening
714 is formed i n correspondence with a gap between upper ends
of one p a i r of t h e beam members 231 and 232.
I n a d d i t i o n , t h e n i t r i d e f i l m 7 2 A u s e d a s t h e m a s k ( f i r s t
mask) includes a p o r t i o n 722 of t h e connection p o r t i o n 23 t h a t
is formed i n correspondence with an area i n which t h e lower
face of the beam member 231 i s formed and a p o r t i o n 723 of t h e
connection p o r t i o n 23 t h a t is formed i n correspondence with
a n a r e a i n w h i c h t h e lower face ofthebeammember232 is formed.
In a d d i t i o n , between t h e p o r t i o n 722 and t h e p o r t i o n 723, an
opening 724 ( f i r s t opening) is formed. This opening 724 is
formed in correspondence with a gap between lower ends of one
pair of the beam members 231 and 232.
Here, when the width of the opening 724 is Wml, and the
thickness of the silicon substrate 102A is T, the relation of
the following Expression (3) is satisfied.
[0074]
[Mathematical 41
1
wm, < m m m
tan 54.73"
(3)
100751
By satisfying this relation, even in a case where the
positional relationship between the nitride film 72A as the
first mask and the nitride film 71A as the second mask is
misaligned, and wherefore, there is a level difference in one
pair of side faces of the beam members 231 and 232 to be
configured by the planes (111) of silicon, a level difference
formed on one side face and a level difference formed on the
other side face can be shifted in the thickness direction of
the siliconsubstrate. Accordingly, intheacquiredactuator,
the concentration of stress that occurs in the beam members
231 and 232 at the time of revolving the movable plate 21 can
be alleviated.
When the width of the opening 714 is Wm2, the following
Expression (4) is satisfied.
[Mathematical 53
tan 54.73"
T < ( 1 + wm2 ) . . . (4)
2
[0077]
' Accordingly, by performing a n i s o t r o p i c etching of t h e
s i l i c o n s u b s t r a t e 10% of which t h e p l a t e face is configured
by the plane (100) of s i l i c o n from b o t h f a c e s i d e s t h e r e o f ,
the connection portion 23 t h a t is configured by one p a i r of
the beam members 231 and 232 can be r e l i a b l y formed i n a simple
manner.
[0078]
H e r e i n a f t e r , t h e generation of a l e v e l d i f f e r e n c e i n t h e
a n i s o t r o p i c etching of t h i s process w i l l be described i n
d e t a i l .
Whentheanisotropicetchingisperformedinthisprocess,
i n a case where the formation p o s i t i o n s of t h e n i t r i d e f i l m s
71A and 72A used as masks a r e n o t m i s a l i g n e d , as shown i n Figs.
9 ( a ) t o 9 (d) , the upper face of t h e s i l i c o n s u b s t r a t e 102A i s
etched through the openings 711 and 714, and t h e lower f a c e
of t h e s i l i c o n s u b s t r a t e 102A i s etched through t h e openings
721 and 724, whereby one p a i r of t h e beam members 231 and 232
a r e formed.
In such a case, t h e c e n t e r p o s i t i o n s of t h e openings 714
and 724 i n t h e widthwise d i r e c t i o n match each o t h e r i n t h e
widthwise d i r e c t i o n . Accordingly, as shown i n Fig. 9 (d) , t h e
side faces of t h e beam members 231 and 232 are f i x e d i n c l i n e d
faces t h a t have no l e v e l d i f f e r e n c e and a r e configured by t h e
planes (111) of s i l i c o n .
[0079]
On t h e other hand, when t h e a n i s o t r o p i c etching is
performed i n t h i s process, in a case where t h e formation
positions of t h e n i t r i d e f i l m s 71A and 72A used a s masks a r e
misaligned, a s shown i n Figs. 1 0 ( a ) t o 10 ( d ) , t h e upper face
of the s i l i c o n s u b s t r a t e 102A is etched through t h e openings
711 and 714, and the lower face of t h e s i l i c o n s u b s t r a t e 102A
is etched through the openings 721 and 724, whereby one p a i r
of the beam members 231 and 232 a r e formed.
[0080]
In such a case, t h e c e n t e r p o s i t i o n s of t h e openings 714
a n d 7 2 4 i n t h e w i d t h w i s e d i r e c t i o n a r e d i f f e r e n t f r o m e a c h o t h e r
i n the widthwise d i r e c t i o n . Accordingly, as shown i n Fig.
1 0 ( d ) , a l e v e l d i f f e r e n c e 2315 is formed on one s i d e face of
the beam member 231, and a l e v e l d i f f e r e n c e 2316 is formed on
the other s i d e face of t h e beam member 231. In a d d i t i o n ,
s i m i l a r l y , a l e v e l d i f f e r e n c e 2325 is formed on one s i d e f a c e
of the beam member 232, and a l e v e l d i f f e r e n c e 2326 is formed
on t h e o t h e r s i d e face of t h e beam member 232.
[0081]
Since t h e width of t h e opening 724 of t h e n i t r i d e f i l m
72A used as a mask is formed so as t o s a t i s f y Expression (3)
described above, the l e v e l d i f f e r e n c e 2316 is formed on t h e
n i t r i d e film 72A side ( t h e lower s i d e ) from t h e c e n t e r of t h e
s i l i c o n s u b s t r a t e 102A i n t h e thickness d i r e c t i o n .
In c o n t r a s t t o t h i s , s i n c e the widths of t h e opening 711
of the n i t r i d e f i l m 71A and t h e opening 721 of t h e n i t r i d e f i l m
72A are excessively l a r g e r than t h e t h i c k n e s s of t h e s i l i c o n
s u b s t r a t e 102A, the l e v e l d i f f e r e n c e 2315 i s formed on t h e
c e n t e r of t h e s i l i c o n s u b s t r a t e 102A i n t h e t h i c k n e s s
d i r e c t i o n .
[0082]
Accordingly, the p o s i t i o n s of t h e l e v e l d i f f e r e n c e 2315
and the l e v e l d i f f e r e n c e 2316 i n t h e t h i c k n e s s d i r e c t i o n of
t h e s i l i c o n s u b s t r a t e 102A a r e d i f f e r e n t from each o t h e r .
Similarly, t h e p o s i t i o n s of t h e l e v e l d i f f e r e n c e 2325 and t h e
l e v e l d i f f e r e n c e 2 3 2 6 i n t h e t h i c k n e s s d i r e c t i o n o f t h e s i l i c o n
s u b s t r a t e 102A a r e d i f f e r e n t from each o t h e r .
As above, since t h e p o s i t i o n s of t h e l e v e l d i f f e r e n c e s
2315 and 2316 i n t h e t h i c k n e s s d i r e c t i o n of t h e s i l i c o n
s u b s t r a t e 1 0 2 A a r e d i f f e r e n t f r o m e a c h o t h e r , t h e c o n c e n t r a t i o n
of s t r e s s on t h e center p o r t i o n of t h e beam member 231 i n t h e
thickness d i r e c t i o n a t t h e time of revolving t h e movable p l a t e
21 can be prevented or suppressed. S i m i l a r l y , . t h e
c o n c e n t r a t i o n o f s t r e s s o n t h e c e n t e r p o r t i o n o f t h e b e a m m e m b e r
232 i n the thickness d i r e c t i o n a t the time of revolving t h e
movable p l a t e 21 can be prevented or suppressed. As a r e s u l t ,
t h e d a m a g e o f t h e c o n n e c t i o n p o r t i o n 2 3 d u e t o t h e c o n c e n t r a t i o n
of s t r e s s a t the time of driving can be prevented. S i m i l a r l y ,
t h e d a m a g e o f t h e c o n n e c t i o n p o r t i o n 2 4 due t o t h e concentration
of s t r e s s a t t h e time of d r i v i n g can be prevented.
[0083]
In a case where the width of t h e opening 724 does not
s a t i s f y Expression (3) described above, a l l t h e l e v e l
d i f f e r e n c e s 2315, 2316, 2325 and 2326 a r e formed a t t h e c e n t e r
p o s i t i o n s of t h e s i l i c o n s u b s t r a t e 102A i n t h e t h i c k n e s s
d i r e c t i o n . I n other words, t h e p o s i t i o n s of t h e l e v e l
d i f f e r e n c e s 2315, 2316, 2325 and 2326 i n t h e t h i c k n e s s
d i r e c t i o n of t h e s i l i c o n s u b s t r a t e 102A a r e t h e same.
Accordingly, t h e r e i s a concern t h a t damage occurs due t o t h e
concentration of s t r e s s a t t h e time of d r i v i n g .
[0084]
-B11-
Next, t h e n i t r i d e f i l m s 71A and 72A a r e removed.
Accordingly, a s shown i n Fig. 8 (f) , a s t a t e is formed i n which
t h e upper f a c e a n d t h e lower f a c e o f t h e b a s e b o d y 2 areexposed.
A method of removing t h e n i t r i d e f i l m s 71A and 72A is
not p a r t i c u l a r l y l i m i t e d . Thus, s i m i l a r l y t o t h e process A5,
f o r example, r e a c t i v e ion etching (RIE), d r y e t c h i n g u s i n g C F 4 ,
a wet process using thermal phosphoric a c i d , or t h e l i k e may
be used.
[0085]
I n a d d i t i o n , a process of rounding each corner p o r t i o n
of t h e base body 2 i s performed a s necessary.
Such a process (rounding process) is not p a r t i c u l a r l y
l i m i t e d . Thus, f o r example, i s o t r o p i c e t c h i n g using
h y d r o f l u o r i c a c i d , n i t r i c acidand a c e t i c ( o r w a t e r ) , a t h e r m a l
process (under decompression, about 1000 t o 120OoC, and under
an atmosphere of A r i n which H2 is i n t r o d u c e d ) .
[0086]
Next, as shown i n Fig. 8 (g) , t h e permanent magnet 4 1 is
f i x e d t o t h e lower face of t h e movable p l a t e 21 through an
adhesive. A l t e r n a t i v e l y , i t m a y b e c o n f i g u r e d s u c h t h a t a h a r d
m a g n e t i s f i x e d t o t h e l o w e r f a c e o f t h e m o v a b l e p l a t e 2 1 t h r o u g h
an adhesive, and t h e r e a f t e r t h e permanent magnet 4 1 is formed
by magnetizing t h e hard magnet.
In a d d i t i o n , on t h e upper f a c e of t h e movable p l a t e 21,
a metal film i s formed, and a l i g h t r e f l e c t i n g p o r t i o n 211 is
formed. Amethodof formingthemetal f i l m i s not p a r t i c u l a r l y
l i m i t e d . Thus, adryplatingmethodsuchasvacuumdeposition,
s p u t t e r i n g (low-temperature s p u t t e r i n g ) , o r i o n p l a t i n g , awet
p l a t i n g method such as e l e c t r o l y t i c p l a t i n g , e l e c t r o l e s s
p l a t i n g , or t h e l i k e , a spraying method, a metal f o i l bonding,
or t h e l i k e may be used.
In a d d i t i o n , although not shown i n t h e f i g u r e , t h e c o i l
42 is disposed on the support body 3, and the support body 3
and the base body 2 are bonded together.
The optical scanner 1 can be acquired through the
above-described process.
[0087]
Accordingtotheabove-describedmethodofmanufacturing
the optical scanner 1, Expression (3) described above is
satisfied. Thus, inthe acquiredopticalscanner 1 (actuator),
the concentration of stress that is generated in each one of
the beam members 231, 232, 241 and 242 at the time of revolving
the movable plate 21 can be alleviated.
According to the above-described optical scanner 1
(actuator) of the first embodiment, the movable plate 21 forms
a cross shape in the plan view. Accordingly, while the light
reflecting area of the movable plate 21 is secured, the moment
of inertia at the time of revolving the movable plate 21 can
be decreased.
In addition, the movable plate 21 having such a shape
in the plan view can be formed with high precision in an easy
manner by performing anisotropic etching of a silicon
substrate.
[0088]

Next, a second embodiment of the invention will be
described.
Fig. 11 is a plan view showing an optical scanner
according to the second embodiment of the invention, and Fig.
12 is a partially enlarged cross-sectional view taken along
line B - B shown in Fig. 11.
Hereinafter, in the optical scanner according to the
second embodiment, differences from the optical scanner
according to the above-described embodiment will be focused
upon in the description, and the description of similar
configurations will be omitted.
to0891
The optical scanner according to the second embodiment
is almost the same as the optical scanner 1 according to the
first embodiment except for the shape of the horizontal
cross-section of a connection portion. The same reference
numeral is assigned to the same configuration as that of the
above-described embodiment.
The optical scanner 1A of this embodiment, as shown in
Fig. 11, includes a base body 2A that has a vibration system.
In addition, the base body 2A includes a movable plate 21, a
support portion 22, and one pair of connection portions 23A
and24Athatconnectthemovableplate 21tothe support portion
22 so as to revolve.
[0090]
Hereinafter, the connection portion 23 will be
representatively described. Since the connection portion 24
is similar to the connection portion 23, the description
thereof will be omitted.
The connection portion 23A is disposed along the axial
line X. In addition, the horizontal cross-sectional shape of
the connection portion 23A forms a trapezoid.
More specifically, the connection portion 23A, when
viewed from a direction parallel to the axial line X (in other
words, viewed at the cross-section shown in Fig. 12), has a
shape symmetrical (horizontally symmetrical in Fig. 12) to a
segment that vertically extends and passes through the axial
line X.
[0091]
In addition, in the cross-section shown in Fig. 12, the
entire width of the connection portion 23A is increased from
the lower side toward the upper side.
In addition, the external shape of the horizontal
cross-section ofthe connection portion 23A forms a trapezoid
that is configured by one pair of sides extending along (100)
of siliconandonepair of sides extending alongthe plane (111)
of silicon. In other words, in the connection portion 23A,
the upper face 233 and the lower face 234 are configured by
the planes (100) of silicon, and one pair of side faces 235
and 236 are configured by the planes (111) of silicon. Here,
the side faces 235 and 236 have a tilt angle 8 of 54.73 degrees
with respect to the upper face 233 or the lower face 234. The
connection portion 23A that forms such a horizontal
cross-section shape, similarly to the connection portion 23
of the above-described first embodiment, can be formed with
high precision in a simple manner by performing anisotropic
etching of a silicon substrate of which the plate face is
configured by the plane (100) of silicon.
Also, according to the above-described optical scanner
1A of the second embodiment, while the light reflecting area
is secured, the moment of inertia at the time of revolving the
movable plate is decreased, and a superior dimensional
precision of the movable plate can be achieved in a simple
manner.
[0092]

Next, a third embodiment of the invention will be
described.
Fig. 13 is a plan view illustrating a movable plate that
is included in a scanner according to the third embodiment of
the invention.
Hereinafter, in the optical scanner according to the
third embodiment, differences from the optical scanner
according to the above-described embodiment will be focused
upon in the description, and the description of similar
configurations will be omitted.
[0093]
The optical scanner according to the third embodiment
is almost the same as the optical scanner 1 according to the
first embodiment except for the shape of a movable plate in
the plan view. The same reference numeral is assigned to the
same configuration as that of the above-described embodiment.
The movable plate 21C that is included in the optical
scanner of this embodiment, as shown in Fig. 13, includes: a
main body portion 212C; one pair of protrusions 213C and 214C
that protrude from the main body portion 212C to both sides
in the axial line X direction; and one pair of protrusions 215C
and 216C that protrude from the main body portion 212 to both
sides in the segment Y direction. Accordingly, the movable
plate 21C forms a cross shape in the plan view.
[0094]
In addition, between the protrusion 213C and the
protrusion 215C in a direction extending along the outer
periphery of the movable plate 21C, a deficient portion 251C
is formed. B e t w e e n t h e p r o t r u s i o n 2 1 3 C a n d t h e p r o t r u s i o n 2 1 6 C
in the direction extending along the outer periphery of the
movable plate 21C, a deficient portion 252C is formed. In
addition, between the protrusion 214C and the protrusion 216C
in the direction extending along the outer periphery of the
movable plate 21C, adeficientportion254Cis formed. Between
the protrusion 214C and the protrusion 215C in the direction
extending along the outer periphery of the movable plate 21C,
a d e f i c i e n t portion 253C is formed.
[0095]
In t h i s embodiment, the movable p l a t e 21C is formed so
as t o be symmetrical with respect t o t h e a x i a l l i n e X i n t h e
plan view from t h e p l a t e t h i c k n e s s d i r e c t i o n and be
asymmetrical with r e s p e c t t o t h e segment Y i n t h e plan view.
H e r e i n a f t e r , the d e f i c i e n t p o r t i o n s 251C and 253C w i l l be
r e p r e s e n t a t i v e l y described. However, the same a p p l i e s t o t h e
d e f i c i e n t portions 252C and 254C.
More s p e c i f i c a l l y , when t h e length of t h e d e f i c i e n t
portion 251 along t h e segment Y d i r e c t i o n is a l , and t h e l e n g t h
of t h e d e f i c i e n t p o r t i o n 251C along t h e a x i a l l i n e X d i r e c t i o n
is b l , t h e r e l a t i o n of a1 < b l is s a t i s f i e d . In o t h e r words,
t h e d e f i c i e n t p o r t i o n 2 5 1 C f o r m s arectangleinwhichthelength
along t h e a x i a l l i n e X d i r e c t i o n i s longerthanthelengthalong
the segment Y d i r e c t i o n . Accordingly, t h e mass of t h e end
portion of the movable p l a t e 21C t h a t is l o c a t e d f a r from t h e
a x i a l l i n e x c a n b e e f f i c i e n t l y r e d u c e d . Therefore, themoment
of i n e r t i a of t h e movable p l a t e 21C a t t h e t i m e of revolving
can be e f f i c i e n t l y suppressed.
[0096]
Similarly, when t h e length of t h e d e f i c i e n t p o r t i o n 253C
along t h e segment Y d i r e c t i o n is a3, and t h e length of t h e
d e f i c i e n t portion 253C along t h e a x i a l l i n e X d i r e c t i o n is b3,
the r e l a t i o n of a3 < b3 is s a t i s f i e d . I n o t h e r words, t h e
d e f i c i e n t portion 253C forms a r e c t a n g l e i n which t h e l e n g t h
alongthe a x i a l l i n e X d i r e c t i o n i s l o n g e r t h a n t h e l e n g t h a l o n g
the segment Y d i r e c t i o n . Accordingly, t h e mass of t h e end
portion of t h e movable p l a t e 21C t h a t is located f a r from t h e
a x i a l l i n e X c a n b e e f f i c i e n t l y r e d u c e d . Therefore, themoment
of i n e r t i a of the movable p l a t e 21C a t t h e time of revolving
can be e f f i c i e n t l y suppressed.
[0097]
In a d d i t i o n , t h e r e l a t i o n s of a1 > a3 and b l > b3 a r e
s a t i s f i e d . Accordingly, i n a case where l i g h t is i n c i d e n t on
the l i g h t r e f l e c t i n g portion 211 with t i l t e d with r e s p e c t t o
the a x i a l l i n e X a x i s , t h e l i g h t r e f l e c t i n g area can be
e f f i c i e n t l y secured.
In a d d i t i o n , a l s o i n t h i s movable p l a t e 21C, when t h e
length of t h e movable p l a t e 21C i n t h e segment Y d i r e c t i o n i n
the plan view is A, t h e length of t h e movable p l a t e 21C i n t h e
a x i a l l i n e X d i r e c t i o n is B, t h e l e n g t h of each one of t h e
d e f i c i e n t p o r t i o n s 251C t o 254C i n t h e segment Y d i r e c t i o n is
a, and t h e length of each one of t h e d e f i c i e n t p o r t i o n s 251C
t o 254C i n t h e a x i a l l i n e X d i r e c t i o n is b, Expressions (A)
and (B) described above a r e s a t i s f i e d .
Also according t o t h e above-described o p t i c a l scanner
of the t h i r d embodiment, while t h e l i g h t r e f l e c t i n g a r e a i s
secured, t h e moment of i n e r t i a a t t h e time of revolving t h e
movable p l a t e is decreased, and a s u p e r i o r dimensional
precision of the movable plate can be achieved in a simple
manner.

Next, a fourth embodiment of the invention will be
described.
Fig. 14 is a plan view illustrating a movable plate that
is included in a scanner according to the fourth embodiment
of the invention.
Hereinafter, in the optical scanner according to the
fourth embodiment, differences from the optical scanner
according to the above-described embodiment will be focused
upon in the description, and the description of similar
configurations will be omitted.
[0099]
The optical scanner according to the fourth embodiment
is almost the same as the optical scanner 1 according to the
first embodiment except for the shape of a movable plate in
the plan view. The same reference numeral is assigned to the
same configuration as that ofthe above-described embodiment.
The movable plate 21D that is included in the optical
scanner of this embodiment, as shown in Fig. 14, includes: a
main body portion 212D; one pair of protrusions 213D and 214D
that protrude from the main body portion 212D to both sides
in the axial line Xdirection; and one pair of protrusions 215D
and 216D that protrude from the main body portion 212 to both
sides in the segment Y direction. Accordingly, the movable
plate 21D forms a cross shape in the plan view.
[OlOO]
In addition, between the protrusion 213D and the
protrusion 215D in a direction extending along the outer
periphery of the movable plate 21D, a deficient portion 251D
is formed. B e t w e e n t h e p r o t r u s i o n 2 1 3 D a n d t h e p r o t r u s i o n 2 1 6 D
in the direction extending along the outer periphery of the
movable plate 21D, a deficient portion 252D is formed. In
addition, between the protrusion 214D and the protrusion 21 6D
in the direction extending along the outer periphery of the
movable plate 21D, a deficient portion 254Dis formed. Between
the protrusion 214D and the protrusion 215D in the direction
extending along the outer periphery of the movable plate 21D,
a deficient portion 253D is formed.
[OlOl]
In this embodiment, the movable plate 21D is formed so
as to be asymmetrical with respect to the axial line X in the
plan view and be symmetrical with respect to the segment Y in
the plan view. Hereinafter, the deficient portions 251D and
252D will be representatively described. However, the same
applies to the deficient portions 253D and 254D.
More specifically, when the length of the deficient
portion251Dalongthe segmentydirectionis all and the length
of the d e f i c i e n t portion 251D along t h e a x i a l l i n e X d i r e c t i o n
i s b l , the r e l a t i o n of a1 < b l is s a t i s f i e d . In other words,
t h e d e f i c i e n t p o r t i o n 2 5 1 D f o r m s a r e c t a n g l e i n w h i c h t h e length
along the a x i a l l i n e X d i r e c t i o n i s l o n g e r t h a n t h e length along
the segment Y d i r e c t i o n . Accordingly, the mass of t h e end
portion of the movable p l a t e 21D t h a t is l o c a t e d f a r from t h e
a x i a l l i n e x c a n b e e f f i c i e n t l y r e d u c e d . Therefore, themoment
of i n e r t i a of the movable p l a t e 21D a t the time of revolving
can be e f f i c i e n t l y suppressed.
[0102]
On t h e other hand, when t h e length of t h e d e f i c i e n t
portion252Dalongthe segment Y d i r e c t i o n i s a2, a n d t h e length
of t h e d e f i c i e n t portion 252D along t h e a x i a l l i n e X d i r e c t i o n
i s b2, the r e l a t i o n of a2 > b2 is s a t i s f i e d . Accordingly, even
i n a case where t h e area of t h e d e f i c i e n t p o r t i o n 252D i n t h e
plan view is l a r g e r than t h e area of t h e d e f i c i e n t p o r t i o n 251D
i n t h e plan view, t h e g r a v i t y c e n t e r of t h e movable p l a t e 21D
is prevented or suppressed from b e i n g d e v i a t e d from t h e a x i a l
l i n e X. Therefore, the revolving of t h e movable p l a t e 21D can
be smooth. In a d d i t i o n , i n t h i s embodiment, t h e r e l a t i o n of
a l x b l < a2xb2 is s a t i s f i e d .
In a d d i t i o n , a l s o i n t h i s movable p l a t e 21D, when t h e
length of t h e movable p l a t e 21D i n t h e segment Y d i r e c t i o n i n
t h e plan view is A, t h e length of t h e movable p l a t e 21D i n t h e
a x i a l l i n e X d i r e c t i o n is B, t h e length of each one of t h e
deficient portions 251D to 254D in the segment Y direction is
a, and the length of each one of the deficient portions 251D
to 254D in the axial line X direction is b, Expressions (A)
and (B) described above are satisfied.
[0103]
Also according to the above-described optical scanner
of the fourth embodiment, while the light reflecting area is
secured, the moment of inertia at the time of revolving the
movable plate is decreased, and a superior dimensional
precision of the movable plate can be achieved in a simple
manner.
The optical scanner as describedabove canbe preferably
applied to an image forming apparatus such as a projector, a
laser printer, a display for imaging, a barcode reader, or a
scanning-type confocal microscope. As a result, an image
forming apparatus having superior drawing characteristics can
be provided.
[0104]
(Image Forming Apparatus)
Here, anexample of an image forming apparatus according
to the invention will be described with reference to Fig. 15.
Fig. 15 is a schematic diagram showing an example of the
configuration ofthe image forming apparatus according to the
invention. Hereinafter, for convenience of the description,
the longitudinal direction of the screen SC is referred to as
a " h o r i z o n t a l d i r e c t i o n " , and a d i r e c t i o n perpendicular t o t h e
l o n g i t u d i n a l d i r e c t i o n is r e f e r r e d t o as a " v e r t i c a l
d i r e c t i o n " .
[0105]
A p r o j e c t o r 9 includes: a l i g h t source device 91 t h a t
emits l i g h t such as a l a s e r beam; a c r o s s d i c h r o i c prism 92;
one p a i r of o p t i c a l scanners 93 and 94 ( f o r example, o p t i c a l
scanners having the same configuration as t h a t of t h e o p t i c a l
scanner 1) according t o the invention; and a f i x e d mirror 95.
The l i g h t source device 91 includes a red l i g h t source
device 911 t h a t emits red l i g h t , a blue l i g h t s o u r c e d e v i c e
912 t h a t e m i t s b l u e l i g h t , and a green l i g h t source device 913
t h a t emits green l i g h t .
[0106]
The cross d i c h r o i c p r i s m 9 2 i s configuredbybonding four
right-angleprismsand is a n o p t i c a l device t h a t compose s l i g h t
emitted from t h e red l i g h t source device 911, t h e blue l i g h t
source device 912, and t h e green l i g h t source device 913.
The p r o j e c t o r 9 is configured such t h a t l i g h t emitted
from t h e red l i g h t source device 911, l i g h t emitted from t h e
blue l i g h t source device 912, and l i g h t emitted from t h e green
l i g h t source device 913 basedon image information t r a n s m i t t e d
from a host computer not shown i n t h e f i g u r e a r e composed by
the c r o s s d i c h r o i c prism 92, and t h e composed l i g h t i s scanned
by the o p t i c a l scanners 93 and 94 and is r e f l e c t e d by t h e f i x e d
mirror 95, whereby a c o l o r image is formed on a screen SC.
[0107]
Here, o p t i c a l scanning of t h e o p t i c a l scanners 93 and
94 w i l l be described more s p e c i f i c a l l y .
F i r s t , the l i g h t composed by t h e cross d i c h r o i c prism
9 2 i s scannedinthehorizontaldirectionbythe o p t i c a l scanner
93 (main scanning). Then, t h e l i g h t scanned i n t h e h o r i z o n t a l
d i r e c t i o n i s f u r t h e r scanned i n t h e v e r t i c a l d i r e c t i o n by t h e
o p t i c a l scanner 94 (sub s c a n n i n g ) . Accordingly, a
two-dimensional color image can be formed on t h e screen SC.
By using t h e o p t i c a l scanners according t o t h e i n v e n t i o n a s
t h e o p t i c a l scanners 93 and 94, extremely e x c e l l e n t drawing
c h a r a c t e r i s t i c s can be acquired.
[0108]
However, t h e p r o j e c t o r 9 is not l i m i t e d t h e r e t o , as long
as it is configured so a s t o form an image on a t a r g e t o b j e c t
by scanning l i g h t by using an o p t i c a l scanner. Thus, f o r
example, t h e f i x e d m i r r o r 95 may be omitted.
According t o t h e p r o j e c t o r 9 configured a s above, t h e
o p t i c a l scanners 93 and 94 having t h e same c o n f i g u r a t i o n a s
t h a t of t h e above-described o p t i c a l scanner 1 a r e included,
a n d t h e r e f o r e , ahigh-qualityimage c a n b e a c q u i r e d a t l o w c o s t .
[0109]
As above, t h e a c t u a t o r , t h e o p t i c a l scanner, and t h e
image forming apparatus according t h e invention have been
described with reference t o t h e accompanying drawings.
However, t h e invention is not l i m i t e d t h e r e t o . For example,
in the a c t u a t o r , the o p t i c a l scanner, and t h e image forming
a p p a r a t u s a c c o r d i n g t o t h e i n v e n t i o n , t h e c o n f i g u r a t i o n o f each
portion can be replaced by a p o r t i o n having an a r b i t r a r y
configuration t h a t implements t h e same function, and an
a r b i t r a r y configuration may be added t h e r e t o .
[OllO]
In a d d i t i o n , i n t h e above-described embodiments, a case
has been d e s c r i b e d i n which t h e movable p l a t e forms a symmetric
shape with r e s p e c t t o a t l e a s t one of t h e revolving c e n t e r a x i s
in the plan view and t h e segment v e r t i c a l t h e r e t o . However,
the invention is not l i m i t e d t h e r e t o , and t h e movable p l a t e
may form a shape t h a t is asymmetrical with r e s p e c t t o e i t h e r
oneoftherevolvingcenteraxisintheplanviewandthesegment
v e r t i c a l t h e r e t o .
Furthermore, i n t h e above-described embodiments, an
example has been described i n which t h e a c t u a t o r according t o
t h e invention is applied t o t h e o p t i c a l scanner. However, t h e
a c t u a t o r according t o t h e invention is not l i m i t e d t h e r e t o and
can be applied t o o t h e r o p t i c a l devices such as a l i g h t switch,
or an o p t i c a l a t t e n u a t o r .
In a d d i t i o n , i n t h e above-described embodiments, an
example has been described i n which t h e d r i v i n g u n i t revolving
the movable p l a t e has a c o n f i g u r a t i o n employing a moving
magnet-type electromagnetic d r i v i n g system. However, such a
driving u n i t maybe amoving c o i l - t y p e e l e c t r o m a g n e t i c d r i v i n g
system or may employ a d r i v i n g system o t h e r than t h e
electromagnetic driving system such as an e l e c t r o s t a t i c
driving system or a p i e z o e l e c t r i c d r i v i n g system.
Reference Signs L i s t
[0111]
1 , l A : o p t i c a l scanner, 2,2A: base body, 3: support body,
4 : driving u n i t , 9: p r o j e c t o r , 21, 21A, 21B, 21C, 21D: movable
p l a t e , 22: support portion, 23,23A: c o n n e c t i n g p o r t i o n , 24,24A
connecting p o r t i o n , 31: concave p o r t i o n , 32: p l a t e shape
portion, 33: frame shape p o r t i o n , 4 1 : permanent magnet, 42:
c o i l , 51: n i t r i d e film, 52: n i t r i d e f i l m , 52A: n i t r i d e f i l m ,
61: r e s i s t f i l m , 62: resist f i l m , 62A: resist film, 71: n i t r i d e
f i l m , 71A: n i t r i d e film, 72: n i t r i d e film, 72A: n i t r i d e film,
81: r e s i s t f i l m , 81A: r e s i s t f i l m , 82: resist f i l m , 82A: r e s i s t
f i l m , 91: l i g h t source device, 92: c r o s s d i c h r o i c prism, 93:
o p t i c a l scanner, 94: o p t i c a l scanner, 95: f i x e d m i r r o r , 102:
s i l i c o n s u b s t r a t e , 102A: s i l i c o n s u b s t r a t e , 211: l i g h t
r e f l e c t i n g p o r t i o n , 212,212C, 212D: body p o r t i o n , 213 t o 216,
213C t o 216C, 213D t o 216D: p r o t r u s i o n , 217: groove, 218:
concave p o r t i o n , 231: beammember, 232: beammember, 233: upper
face, 234: lower face, 235,236: s i d e f a c e , 241: beam member,
242: beam member, 251 t o 254, 251C t o 254 C, 251D t o 254D:
d e f i c i e n t p o r t i o n , 311: bottom f a c e , 521: opening, 621: opening,
711: opening, 712: p o r t i o n , 713: p o r t i o n , 714: opening, 721:
opening, 722: p o r t i o n , 723: p o r t i o n , 724: opening, 811: opening,
821: opening, 911: r e d l i g h t s o u r c e d e v i c e : 912: b l u e l i g h t
s o u r c e d e v i c e , 913: green l i g h t s o u r c e d e v i c e , 2311: upper f a c e ,
2312: lower f a c e , 2313,2314: s i d e f a c e , 2 3 1 5 : l e ~ e l d i f f e r e n c e ~
2316: l e v e l d i f f e r e n c e , 2321: upper f a c e , 2322: lower f a c e ,
2323,2324: s i d e f a c e , 2325: l e v e l d i f f e r e n c e , 2326: l e v e l
d i f f e r e n c e

CLAIMS
[Claim 11
An actuator comprising:
a movable portion that can oscillate around an
oscillation axis;
a connection portion that extends from the movable
portion and is torsionally deformed in accordance with
oscillation of the movable portion; and
a support portion that supports the connection portion,
wherein the movable portion forms a cross shape in a plan
view from a thickness direction of the movable portion.
[Claim 21
The actuator according to Claim 1, wherein an external
shape ofthemovable portion in the planview fromthethickness
direction is mainly configured by a segment that is parallel
to the oscillation axis and a segment that is vertical to the
oscillation axis.
[Claim 31
The actuator according to Claim 1, wherein the movable
portion, the support portion, and the connection portion are
formed by performing anisotropic etching of a silicon
substrate.
[Claim 41
The actuator according to Claim 3, wherein a plate face
of the movable portion is configured by a plane (100) of
silicon.
[Claim 51
The actuator according to Claim 3, wherein a side face
of the movable portion is mainly configured by a plane (111)
of silicon.
[Claim 61
The actuator according to Claim 5, wherein, on the side
face of the movable portion, a groove that forms a 'V" shape'
at a cross-section that is perpendicular to the plate face of
the movable portion is formed.
[Claim 71
The actuator according to Claim 3, wherein a surface of
theconnectionportionis configuredbyaplane (100) of silicon
and a plane (111) of silicon.
[Claim 81
The actuator according to Claim 1, wherein the movable
portion forms a shape that is symmetrical with respect to the
oscillation axis of the movable portion in the plan view from
the thickness direction.
[Claim 91
The actuator according to Claim 1, wherein the movable
portion forms a shape that is symmetrical with respect to a
segment that passes through the center of the movable portion
in the plan view from the thickness direction and is vertical
to the oscillation axis of the movable portion.
[Claim 101
I An actuator comprising:
1 a movable portion that can oscillate around an
oscillation axis;
a connection portion that extends from the movable
portion and is torsionally deformed in accordance with
oscillation of the movable portion; and
a support portion that supports the connection portion;
wherein the movable portion forms a shape acquired by
eliminating four corner portions, which are in rectangular
shapes, of a rectangleinaplanview froma thickness direction
of the movable portion.
[Claim 111
An optical scanner comprising:
a movable portion that includes a light reflecting
portion having light reflectivity and can oscillate around an
oscillation axis;
a connection portion that extends from the movable
portion and is torsionally deformed in accordance with
oscillation of the movable portion; and
a support portion that supports the connection portion,
wherein themovable portion forms a cross shape in aplan
view from a thickness direction of the movable portion.
[Claim 121
An o p t i c a l scanner comprising:
a movable portion t h a t includes a l i g h t r e f l e c t i n g
portion having l i g h t r e f l e c t i v i t y and can o s c i l l a t e around an
o s c i l l a t i o n a x i s ;
a connection p o r t i o n t h a t extends from t h e movable
portion and is t o r s i o n a l l y deformed i n accordance with
o s c i l l a t i o n of the movable portion; and
a support portion t h a t supports t h e connection p o r t i o n ,
wherein the movable p o r t i o n forms a shape acquired by
e l i m i n a t i n g f o u r corner p o r t i o n s , which a r e i n r e c t a n g u l a r
shapes, of a r e c t a n g l e i n a p l a n v i e w froma thickness d i r e c t i o n
of the movable portion.
[Claim 131
An image forming apparatus comprising:
a l i g h t source t h a t e m i t s l i g h t ; and
an o p t i c a l scanner t h a t scans l i g h t emitted from t h e
l i g h t source,
wherein the o p t i c a l scanner i n c l u d e s :
a m o v a b l e p o r t i o n t h a t includes a l i g h t r e f l e c t i n g
portion having l i g h t r e f l e c t i v i t y and can o s c i l l a t e around an
o s c i l l a t i o n a x i s ;
a connection p o r t i o n t h a t extends fromthemovable
portion and is t o r s i o n a l l y deformed i n accordance with
o s c i l l a t i o n of t h e movable portion; and
a support p o r t i o n t h a t supports t h e connection
portion, and
wherein themovable portion forms a cross shape i n a plan
view from a thickness d i r e c t i o n of the movable portion.
[Claim 141
An image forming apparatus comprising:
a l i g h t source t h a t emits l i g h t ; and
an o p t i c a l scanner t h a t scans l i g h t emitted from the
l i g h t source,
wherein the o p t i c a l scanner includes:
amovableportionthat includes a l i g h t r e f l e c t i n g
portion having l i g h t r e f l e c t i v i t y and can o s c i l l a t e around an
o s c i l l a t i o n axis;
a connection portion t h a t extends fromthemovable
portion and is t o r s i o n a l l y deformed i n accordance with
o-~cI-Tlation of the movable portion; and
a support portion t h a t supports the connection
portion, and
wherein the movable portion forms a shape acquired by
eliminating four corner portions, which a r e i n rectangular
shapes, ofarectangleinaplanviewfromathicknessdirection
of the movable portion.