SPECIFICATION
Title of Invention: NEEDLE ASSEMBLY
Technical Field
[OOl]The present invention relates to a needle assembly and, more particularly, to a needle assembly including a cannula in which a puncture section is formed, a hub that holds the cannula, and a cover provided to be movable to
a first position where the cannula is exposed with
respect to the hub and a second position where a distal
end projects further than the cannula.
Background Art
[OO021
In order to prevent erroneous puncture after use,
there has been known a needle assembly including a
cannula in which a puncture section is formed, a hub that
holds the cannula, and a cover provided to be movable to
a first position where the cannula is exposed with
respect to the hub and a second position where a distal
end projects further than the cannula.
As such a needle assembly, there has been known a
needle assembly including a front cannula in which a
puncture section is formed at a distal end, a hub that
holds the front cannula, a front cover provided to be
movable to a retracted position where the front cannula
is exposed with respect to the hub and an advanced
position where a distal end projects further to the front
than the front cannula, and urging means for urging the
front cover toward the advanced position (Patent Document
1).
In such a needle assembly, an operation lever for
performing operation and an engaging protrusion for
holding the front cover in the retracted position are
exposed to the outside. A user operates the lever to
thereby locate the front cover in the advanced position.
Prior Art Document
Patent Document
[0003]
Patent Document 1: Japanese Patent Laid-Open No.
2007-151752
Summary of Invention
Problems to be Solved by the Invention
[0004]
However, for example, when the needle assembly is
used for dental treatment, since the operation lever
projects to the outside, it is likely that a patient may
be injured by the lever. It is also likely that the
front cover erroneously projects to the advanced posltion
because of erroneous operation by a user who holds the
assembly in an oral cavity.
In view of such problems, the present invention
provides a needle assembly capable of reducing projecting
objects to the outside as much as possible and preventing
a malfunction.
Means for Solving the Problems
[00051
That is, a needle assembly described in claim 1 is a
needle assembly including: a cannula in which a puncture
section is formed; a hub that holds the cannula; and a
cover provided to be movable to a first position where
the cannula is exposed with respect to the hub and a
second position where a distal end projects further than
the cannula, characterized in that
in the cover, a circumferential-direction locking
section formed in a circumferential direction and a
front-back-direction groove formed in a front-back
direction to continue to the circumferential-direction
locking section or an engaging protrusion movable along
the circumferential-direction locking section and the
front-back-direction groove are provided,
the movement of the cover in the front-back
direction is blocked in a state in which the cover is
located in the first position and the engaging protrusion
is housed in the circumferential-direction locking
section, and
when the engaging protrusion moves along the
circumferential-direction locking section and moves to
the front-back-direction groove, the engaging protrusion
becomes movable along the front-back-direction groove to
allow the movement of the cover to the second position.
Advantageous Effects of Invention
[00061
According to the invention of claim 1, in the state
in which the cover is located in the first position,
since the engaging protrusion is housed in the
circumferential-direction locking section, it is possible
to prevent injury to the patient by the operation lever
projecting to the outside described in Patent Document 1.
To move the cover to the second position, the
engaging protrusion needs to be moved along the
circumferential-direction locking section and moved to
the front-back-direction groove. Therefore, it is
possible to prevent the projection of the cover due to a
malfunction even if operation in a narrow place is
performed.
Brief Description of Drawings
[00071
[Figure 11 Figure 1 is an exterior view of a state of use
of a needle assembly according to an embodiment; (a) and
(b) respectively show figures of the needle assembly
viewed from different angles.
[Figure 21 Figure 2 is an exterior view of a state after
use of the needle assembly.
[Figure 31 Figure 3 is sectional views in a 111-III(a)
part and a 111-III(b) part in Figure 1.
[Figure 41 Figure 4 is a sectional view in a IV-IV part
of Figure 2.
[Figure 51 Figure 5 is a sectional view in a V-V part in
Figure 1.
[Figure 61 Figure 6 is a sectional view in a VI-VI part
in Figure 2.
[Figure 71 Figure 7 shows a needle assembly according to
a second embodiment; (a) shows a sectional view of a
state of use and (b) shows a figure of the needle
assembly viewed from a front cannula side in the state of
use.
[Figure 81 Figure 8 is a sectional view of a needle
assembly according to a third embodiment; (a) shows a
state of use and (b) shows a state after use.
Mode for Carrying out the Invention
[0008]
Embodiments shown in the figures are explained below.
A needle assembly (1) shown in Figures 1 and 2 is mounted
on not-shown liquid supplying means such as a syringe, in
which an anesthetic is stored, and used in dental
treatment. Figure 1 shows a state of use of the assembly
(1). Figure 2 shows a state after use of the assembly
(1).
Parts (a) and (b) of Figure 1 respectively show the
assembly (1) in the state of use viewed from different
angles. Figure 3 to Figure 6 respectively show sectional
views of sections in Figures 1 and 2. In the figures,
the right shown in the figures is referred to as front or
distal end side and the left shown in the figures is
referred to as back or rear end side.
The needle assembly (1) includes a front cannula (2)
projecting to the front, a back cannula (3) projecting
backward, a hub (4) that holds the front cannula (2) and
the back cannula (31, a front cover (5) (see Figure 2)
provided to be capable of advancing and retracting in the
front of the hub ( 4 ) , a cover guide (6) provided in the
hub (4) to cover the front cover (5), and a back cover
(7) provided to be capable of advancing and retracing in
the back of the hub (4).
Further, in the state of use of the needle assembly
(1) shown in Figure 1, the assembly (1) is in a
puncturable state in which the front cover (5) is located
in a retracted position serving as a first position, the
back cover (7) is located in an advanced position serving
as the second position, and the front cannula (2) and the
back cannula (3) are exposed to the outside.
On the other hand, in the state after use of the
needle assembly (1) shown in Figure 2, the assembly (1)
is in a state in which the front cover (5) is located in
the advanced position serving as a second position, the
back cover (7) is located in the retracted position
serving as the first position, and the front cannula (2)
and the back cannula (3) are housed on the insides of the
front cover (5) and the back cover (7), and erroneous
puncture is prevented.
[0009]
The front cannula (2) and the back cannula (3) are
respectively configured by needle tubes made of stainless
steel or the like. Puncture sections (2a) and (3a) are
respectively formed at the distal end of the front
cannula (2) and the rear end of the back cannula (3).
The hub (4) is a substantially columnar member. A
through-hole (4a) piercing through the hub (4) to the
front and back is drilled on the inside of the hub (4)
(see Figure 3). The front cannula (2) and the back
cannula (3) are bonded and held in the through-hole (4a).
In the through-hole (4a), a slight gap is formed between
the rear end portion of the front cannula (2) and the
distal end portion of the back cannula (3).
The diameter of the front cannula (2) in the needle
assembly (1) for dental use is set to as small a diameter
as possible in order to reduce puncture pain. The total
length of the cannula (2) is set as long as possible such
that the assembly (1) can be punctured in any position in
an oral cavity.
Therefore, an inner passage of the cannula (2) is
small in diameter and channel resistance is large.
Therefore, the liquid supplying means has to feed the
anesthetic with a high supply pressure.
On the other hand, the back cannula (3) is provided
for the purpose of piercing through a lid section made of
resin provided at the distal end portion of the liquid
supplying means. Therefore, it is unnecessary to set the
diameter of the back cannula (3) to a small diameter.
Chanel resistance can be reduced.
[OOlO]
The configurations and the operations of the front
cover (5) and the cover guide (6) are explained below
with reference to Figure 3 and Figure 4. Figure 3 shows
a state of use in which the cover (5) is located in the
retracted position. Figure 4 shows a state after use in
which the cover (5) moves to the advanced position.
At the distal end of the hub (4), a columnar frontside
inner cylinder section (11), which holds the front
cannula (21, and a cylindrical front-side outer cylinder
section (12), which surrounds the inner cylinder section
(ll), are formed. A substantially disc-like flange (13)
is formed in the back of the inner section (11) and the
outer section (12) .
The distal ends of the inner section (11) and the
outer section (12) are formed in substantially the same
positions. A required gap is formed between the inner
section (11) and the outer section (12).
The rear end portion of a spring (14) functioning as
urging means elastically installed between the distal end
portion of the front-side inner cylinder section (11) and
the front cover (5) is elastically in contact with the
distal end of the inner section (11). As shown in Figure
3(b), key grooves (lla) are formed toward the front-back
direction in positions opposed to each other across the
front cannula (2) on the side surface of the inner
cylinder section (11).
The front-side outer cylinder section (12) is formed
smaller in diameter than the diameter of the flange (13).
On the outer circumferential surface of the outer
cylinder section (121, cover-guide holding protrusions
(12a) project outward in positions opposed to each other
across the front cannula (2).
[OOll]
The front cover (5) is formed in a substantially
cylindrical shape. When the front cover (5) is located
in the advanced position as shown in Figure 2, the distal
end of the front cover (5) projects further to the front
than the puncture section (2a) of the front cannula (2)
and covers the section (2a).
When the front cover (5) is located in the retracted
position as shown in Figure 1, the front cover (5) also
projects slightly further than the cover guide (6). The
distal end portion of the cover (5) is formed in a taper
shape. Consequently, a patient is not injured when the
needle assembly (1) is used in an oral cavity.
The distal end portion of the inner surface of the
front cover (5) is also formed in a taper shape. The
spring (14) is elastically in contact with the rear end
portion of the taper shape from the back. Consequently,
the cover (5) is always urged to the front by thespring
(14).
At the rear end portion of the front cover (5), a
pair of front-side engaging protrusions (5a) projecting
to the outer circumference side and a pair of keys (5b)
projecting to the back are respectively formed in
positions opposed to each other across the front cannula
(2). The protrusions (5a) and the keys (5b) are formed
in positions biased a predetermined angle centering on
the axial direction of the cannula (2).
The keys (5b) engage with the key grooves (lla) of
the hub (4) to configure rotation preventing means for
the front cover (5). As shown in Figure 3(b), in a state
in which the front cover (5) is located in the retracted
position, the keys (5b) fit in the grooves (lla) to
thereby prevent the rotation of the front cover (5) and
the hub (4) .
[0012]
The cover guide (6) is formed as a substantially
cylindrical member. A large diameter section (Zl), which
fits with the front-side outer cylinder section (12) of
the hub (4), an intermediate diameter section (22), which
houses the front cover ( 5 ) , and a small diameter section
(23) formed at the distal end of the guide (6) are formed
in order from the rear end of the guide (6).
The large diameter section (21) fits with the outer
cylinder section (12) to be capable of rotating in the
circumferential direction. A plurality of protrusions
(2la) for operation to be held by a user in treatment are
formed on the outer circumferential surface of the large
diameter section (21) (see Figure 1 and Figure 2).
In the large diameter section (211, cover-guide
holding grooves (21b), which engage with the cover-guide
holding protrusions (12a) formed in the hub (4), are
formed toward the circumferential direction of the
section (21).
When the cover-guide holding protrusions (12a) are
housed in the cover-guide holding grooves (2lb), the
movement in the front-back direction of the cover guide
(6) with respect to the hub (4) is blocked and, on the
other hand, the rotation of the guide (6) in the
circumferential direction is allowed.
Specifically, in the state of use shown in Figure 1,
as shown in Figure l(a), the protrusions (12a) are
located on the lower side shown in the figure of the
grooves (21b). It is possible to rotate the cover guide
(6) clockwise from this state.
Very small protrusions (21c) are formed in the
cover-guide holding grooves (21b). When the user rotates
the cover guide (6), the user moves the cover-guide
holding protrusions (12a) to move over the protrusions
(21c) .
[00131
On the inner surface of the cover guide (6), frontside
front-back-direction grooves (24) formed toward the
front-back direction and front-side circumferentialdirection
locking sections (25) formed continuously in
the circumferential direction from the rear end portions
of the grooves (24) are formed. Front-cover-retraction
blocking sections (26) for blocking retraction of the
front cover (5) are provided in the front of the grooves
(24). Pairs of the grooves (24), the locking sections
(25), and the blocking sections (26) are respectively
provided across the front cannula (2).
The front-side front-back-direction grooves (24) are
formed at depth for enabling the front-side engaging
protrusions (5a) of the front cover (5) to pass through
the grooves (24). The grooves (24) are formed not to
pierce through the cover guide (6) to the outer surface.
By forming the grooves (24) not to pierce through
the cover guide (6) to the outer surface, when the guide
(6) is led into the oral cavity of the patient, the
patient is prevented from being injured by protrusions or
edges formed by the grooves that pierce through the guide
(6).
The front-side circumferential-direction locking
sections (25) are configured by a step formed in the
boundary between the large diameter section (21) and the
intermediate diameter section (22) of the cover guide (6).
As shown in Figure 3(b), the locking sections (25) are
formed to continue to the rear end portions of the frontside
front-back-direction grooves (24).
Gaps in a degree in which the front-side engaging
protrusions (5a) can be located are formed between the
locking sections (25) and the front-side outer cylinder
section (12) of the hub (4) .
[0014]
The inner diameter of the small diameter section
(23) is set to a diameter for disabling the front-side
engaging protrusions (5a) of the front cover (5) to pass
through the section (23). When the front cover (5) is
located in the advanced position as shown in Figure 4,
the front-side engaging protrusions (5a) come into
contact with a surface in the back of the small diameter
section (23) and block further advance of the front cover
(5).
The outer surface of the section (23) is formed in a
taper shape. The taper-shaped portion of the front cover
(5) projects slightly further to the front than the small
diameter section (23) in the retracted position. An
integral taper shape is formed by the section (23) and
the distal end portion of the cover (5) to prevent the
patient from being injured.
[00151
The front-cover-retraction blocking sections (26)
are located between the small diameter section (23) and
the front-side front-back-direction grooves (24) and
configured from through-holes (26a) formed in a
substantially rectangular shape and retraction blocking
protrusions (26b) projecting to the insides of the holes
(26a).
The surfaces in the front in the holes (26a)
configure the surface at the rear end of the small
diameter section (23). As explained above, the frontside
engaging protrusions (5a) of the front cover (5)
come into contact with the surface from the back and
block the advance of the cover (5).
The retraction blocking protrusions (26b) are formed
to project toward the front from the surfaces in the back
of the holes (26a). As shown in Figure 4, the engaging
protrusions (5a) are housed between the distal end
portions of the blocking protrusions (26b) and the
surfaces in the front of the holes (26a).
The retraction blocking protrusions (26b) are
elastically deformed starting from a base section on the
rear end side of the retraction blocking protrusions
(26b). Inclined surfaces (26c) inclining from the back
toward the front are formed on the inner surfaces of the
retraction blocking protrusions (26b)
The front-side engaging protrusions (5a) come into
contact with the inclined surfaces (26c). While the
engaging protrusions (5a) pass, the blocking protrusions
(26b) move outward.
On the other hand, the outer surface side of the
blocking protrusions (26b) is located flush with the
outer surface of the cover guide (6) or further on the
inner surface side than the outer surface to prevent the
patient from being injured when the needle assembly (1)
is operated in the oral cavity.
[00161
Concerning the configuration explained above, an
operation in locating the front cover (5) in the advanced
position from the retracted position is explained below.
First, in the state of use, when the front cover (5)
is located in the retracted position, as shown in Figure
3, the front-side engaging protrusions (5a) formed at the
rear end portion of the cover (5) are in contact with,
from the back, the front-side circumferential-direction
locking sections (25) formed in the cover guide (6). The
advance of the front cover (5) is blocked irrespective of
an urging force of the spring (14).
In this state, when the cover guide (6) is rotated
clockwise from the state of Figure 1, the engaging
protrusions (5a) relatively move along the locking
sections (25).
At this point, since the keys (5b) of the cover (5)
located in the retracted position engage with the key
grooves (1la) of the hub (4), the rotation of the cover
(5) is blocked. The engaging protrusions (5a) of the
cover (5) move relatively to the locking sections (25).
[0017]
A rotation amount of the cover guide (6) is
specified by the length in the circumferential direction
of the cover-guide holding grooves (21b) formed in the
guide (6), that is, a movement amount of the cover-guide
holding protrusions (12a) formed in the hub (4).
When the holding protrusions (12a) move from the
state shown in Figure 1 to the other end portions in the
holding grooves (21b), the front-side front-backdirection
grooves (24) of the cover guide (6) move to
positions overlapping the front-side engaging protrusions
(5a).
When the grooves (24) move to the positions of the
engaging protrusions (5a) in this way, the protrusions
(5a) are capable of advancing along the grooves (24).
The front cover (5) advances to the advanced position
with the urging force of the spring (14).
[0018]
When the front cover (5) advances with the urging
force of the spring (14), the front-side engaging
protrusions (5a) advance along the front-side front-backdirection
grooves (24) and come into contact with, from
the back, the inclined surface (26c) formed on the inner
surfaces of the retraction blocking protrusions (26b) in
the front-cover-retraction blocking sections (26).
Then, the blocking protrusions (26b) are pressed
outward by the engaging protrusions (5a). Consequently,
the base sections on the rear end portion side of the
blocking protrusions (26b) are elastically deformed to
move outward and allow passage of the engaging
protrusions (5a) .
The engaging protrusions (5a) come into contact with
the surfaces in the front of the through-holes (26a),
which have passed the blocking protrusions (26b), and are
located in the advanced position shown in Figure 4.
Consequently, further advance of the front cover (5) is
blocked.
On the other hand, when the engaging protrusions
(5a) pass the blocking protrusions (26b), the blocking
protrusions (26b) return from the elastic deformation and
move inward again. The distal end portions of the
blocking protrusions (26b) become capable of comlng into
contact with the passed engaging protrusions (5a) from
the back. Therefore, the retraction of the front cover
(5) is blocked.
[00191
The configuration and the operation of the back
cover (7) are explained with reference to Figure 4 and
Figure 6.
In the back of the flange (13) in the hub (4), a
back-cannula holding section (31) formed in a
substantially cross shape in section, which holds the
back cannula (3), a columnar back-side inner cylinder
section (32) projecting to the back from the holding
section (31), and a cylindrical back-side outer cylinder
section (33) that surrounds the inner section (32) are
formed.
The through-hole (4a) is formed in the center of the
holding section (31) and the inner section (32). The
rear end portions of the inner section (32) and the outer
section (33) are formed in substantially the same
positions. A required gap is formed between the inner
section (32) and the outer section (33).
In the back-side outer cylinder section (33), a pair
of back-side engaging protrusions (33a) is provided in
positions opposed to each other across the back cannula
(3). The pair of engaging protrusions (33a) is formed to
project to the outer circumference side of the outer
cylinder section (33).
The back-side engaging protrusions (33a) are
provided further at rear end portions of an arm section
projecting to the back from the rear end portion of the
back-cannula holding section (31). When the arm section
is elastically deformed, the engaging protrusions (33a)
move to the inner circumference side.
[0020]
The back cover (7) is formed as a cylindrical member.
The cover (7) slides in the front-back direction along
the back-cannula holding section (31) and the back-side
outer cylinder section (33) of the hub (4) and is capable
of rotating in the circumferential direction. When the
cover (7) is located in the retracted position as shown
in Figure 2, the rear end of the cover (7) projects
further to the back than the puncture section (3a) of the
back cannula (3) and covers the section (3a).
At the rear end portion of the back cover (7), a
coupling section (41) coupled to a coupled section
provided in the not-shown liquid supplying means is
formed. The coupling section (41) is configured from a
female screw section (41a) formed on the inner surface
and a lock section (41b) formed on the outer surface. On
the other hand, in the coupled section of the not-shown
liquid supplying means, a male screw section, which
screws in the female screw section (41a), and a lock
section, which engages with the lock section (41b), are
provided.
In order to couple the coupled section of the liquid
supplying means to the coupling section (41), the liquid
supplying means is rotated. Consequently, the male screw
section screws with the female screw section (41a). The
lock section (41b) engages with the lock section.
On the other hand, to separate the coupled section
of the liquid supplying means from the coupling section
(41) in order to separate the liquid supplying means from
the needle assembly (I), the liquid supplying means only
has to be rotated in the opposite direction to separate
the male screw section from the female screw section
(41a) of the back cover (7).
Note that such a coupling section (41) is publicly
known in the past. The section (41) in this embodiment
may be coupling sections corresponding to liquid
supplying means including coupled sections having other
shapes.
[0021]
In the back cover (7), back-side front-backdirection
grooves (42) formed toward the front-back
direction, back-side circumferential-direction locking
sections (43) formed continuously to the rear end
portions of the grooves (42), and back-cover-advance
blocking sections (44) provided in the front of the
grooves (42) are provided. Pairs of the grooves (42),
the locking sections (43), and the blocking sections (44)
are respectively provided in positions across the back
cannula (3).
The back-side engaging protrusions (33a) formed in
the hub (4) move to the back-side front-back-direction
grooves (42). Unlike the front-side front-back-direction
grooves (24) formed in the cover guide (6), the back-side
front-back-direction grooves (42) may pierce through the
back cover (7) from the inner surface to the outer
surface.
As shown in Figure l ( b ) , the back-side
circumferential-direction locking sections (43) are
formed continuously in the circumferential direction from
the rear end portions of the grooves (42) and formed in a
groove shape to match the width of the engaging
protrusions (33a).
In Figure l(b), the locking sections (43) are formed
upward shown in the figure from the rear end portions of
the grooves (42). When the back cover (7) is rotated
counterclockwise, the engaging protrusions (33a)
relatively move along the locking sections (43).
Further, in the locking sections (431, protrusions
(43a) are formed in positions adjacent to the back-side
engaging protrusions (33a). The back cover (7) is
prevented from unintentionally rotating.
[0022]
The back-cover-advance blocking sections (44) are
configured from through-holes (44a) formed in positions
spaced apart from the grooves (42) to the front by a
predetermined distance and piercing through the back
cover (7) and advance blocking sections (44b) formed
between the through-holes and the grooves (42).
The through-holes (44a) are formed in a shape for
allowing the back-side engaging protrusions (33a) to fit
in the holes (44a) substantially without a gap. The
engaging protrusions (33a) come into contact with the
surfaces in the front of the holes (44a) from the back to
block further retraction of the back cover (7).
With the through-holes (44a), since the engaging
protrusions (33a) are housed in the holes (44a), the
protrusions (33a) can be visually recognized from the
outside (see Figure 2).
The advance blocking sections (44b) configure the
surfaces in the back of the holes (44a). The engaging
protrusions (33a) come into contact with the advance
blocking sections (44b) from the front to block the
advance of the back cover (7).
Further, on the inner surfaces of the advance
blocking sections (44b), inclined surfaces (44c)
projecting to the inner surface side are formed from the
back to the front. The engaging protrusions (33a) of the
hub (4) come into contact with the inclined surfaces
(4412) when the back cover (7) retracts.
[0023]
Concerning the configuration explained above, an
operation in locating the back cover (7) from the
advanced position to the retracted position is explained.
In the state of use shown in Figure 1, in a state in
which the back cover (7) is located in the advanced
position, as shown in Figure 5, the back-side engaging
protrusions (33a) are housed in the back-side
circumferential-direction locking sections (43). The
retraction of the cover (7) is blocked.
1; a state in which engaging protrusions (33a) are
housed in the locking sections (43) in this way, when the
cover (7) is rotated counterclockwise from the state
shown in Figure 1, the engaging protrusions (33a)
relatively move to the rear end portions of the grooves
(42) along the locking sections (43).
[0024]
When the user retracts the back cover (7) from that
state, the engaging protrusions (33a) advance relatively
to the grooves (42). The protrusions (33a) come into
contact with the inclined surface (44c) of the blocking
sections (44) from the back.
Then, the engaging protrusions (33a) are elastically
deformed from the base sections on the distal end side
thereof, move inward toward the inner cylinder section
(32), and pass the inclined surfaces (44c). After
passing the surfaces (44c), the protrusions (33a) move
outward again and are housed in the through-holes (44a).
When the engaging protrusions (33a) are housed in
the through-holes (44a), further retraction of the back
cover (7) is blocked by the surfaces in the front of the
holes (44a). The cover (7) is located in the retracted
position. Repeated advance of the cover (7) is blocked
by the advance blocking sections (44b).
[GO251
A method of usirlg the needle assembly (1) having the
configuration explained above is explained below.
First, the needle assembly (1) is conveyed in a
state in which the assembly (1) is housed on the inside
of a not-shown casing. The casing is configured from a
front side casing that covers the cover guide (6) and the
front cannula (2) and a back side casing that covers the
back cover (7) and the back cannula (3).
The user removes the back side casing of the casing
and exposes the back cover (7) and the back cannula (3).
In this case, the needle assembly (1) is in the state of
use shown in Figure 1. The cover (7) is held in the
advanced position.
In this state, the user couples the coupled section
of the liquid supplying means to the coupling section
(41) formed in the cover (7). Consequently, the back
cannula (3) pierces through the lid section of the liquid
supplying means. The anesthetic can be supplied from the
liquid supplying means to the cannula (3).
[GO261
Subsequently, the user removes the front side casing
of the casing and exposes the cover guide (6) and the
front cannula (2) . At this point, the front cover (5) is
held in the retracted position.
The user grips the flange (13) of the hub (4) and
the protrusions (21a) for operation of the cover guide
(6), punctures the front cannula (2) into the oral cavity
of the patient, and operates the liquid supplying means
to administer the anesthetic.
In that case, since protrusions are not formed as
much as possible on a portion led into the oral cavity of
the patient, that is, the outer circumferential surface
of the cover guide ( 6 ) , it is possible to prevent the
patient from being injured by the protr~sions.
The front-side engaging protrusions (5a) of the
front cover (5) are not exposed to the outside.
Therefore, the user gripping the needle assembly (1) is
prevented from erroneously touching the engaging
protrusions (5a) to cause the front cover (5) to
malfunction.
[00271
When the user finishes the administration of the
anesthetic to the patient, the user rotates the cover
guide (6) clockwise with respect to the hub (4).
Consequently, the front cover (5) moves from the
retracted position to the advanced position and changes
from the state of use to the state after use.
When rotating the cover guide (6), the user has to
cause, with the cover-guide holding protrusions (12a),
the guide (6) to move over the protrusions (21c) formed
in the cover-guide holding grooves (21b). The guide (6)
is prevented from unintentionally rotating to cause the
front cover (5) to malfunction before the guide (6) moves
over the protrusions (2lc).
Since the front cover (5) changes to the state after
use, the distal end of the cover (5) projects further to
the front than the puncture section (2a) of the front
cannula (2). Therefore, erroneous puncture by the
cannula (2) is prevented.
When the front cover (5) is located in the advanced
position, the front-side engaging protrusions (5a) are
housed in the front-cover-retraction blocking sections
(26) provided in the front of the front-side front-backdirection
grooves (24). The cover (5) is located in the
advanced position and repeated retraction is blocked.
[0028]
When the front cover (5) is located in the advanced
position in this way, subsequently, in a state in which
the liquid supplying means is kept connected, the user
retracts the back cover (7) from the advanced position to
the retracted position and changes the cover (7) from the
state of use to the state after use.
Specifically, the user rotates the cover (7)
counterclockwise from the state shown in Figure 1 and,
when the back-side engaglng protrusions (33a) are located
at the rear end portions of the back-side front-backdirection
grooves (42), moves the cover (7) to the back.
When rotating the back cover (71, the user has to
cause, with the engaging protrusions (33a), the cover (7)
to move over the protrusions (2lc) formed in the backside
circumferential-direction locking sections (43). The
cover (7) is prevented from unintentionally rotating to
retract before the cover (7) moves over the protrusions
(21c).
When the cover (7) is located in the retracted
position, the engaging protrusions (33a) are housed in
the through-holes (44a). By visually recognizing the
engaging protrusions (33a) from the outside, the user can
confirm that the back cover (7) is surely located in the
retracted position.
[00291
When the back cover (7) is located in the retracted
position in this way, the user rotates the liquid
supplying means coupled to the coupling section (41) of
the cover (7) counterclockwise. Consequently, the user
can separate the lock section and the male screw section
of the coupled section from the lock section (41b) and
the female screw section (4la) of the coupling section
(41).
When the liquid supplying means is separated in thls
way, since the cover (7) is already located in the
retracted position and is in the state after use shown in
Figure 2, the back cannula (3) is housed in the cover (7)
It is possible to prevent subsequent erroneous puncture
by the cannula (3).
Thereafter, the needle assembly (1) in this
embodiment is discarded. However, since the front cover
(5) is maintained in the advanced position and the back
cover (7) is maintained in the retracted position as
explained above, it is also possible to prevent an
accident in which the front cannula (2) and the back
cannula (3) are exposed from the discarded assembly (1).
[0030]
Figure 7 shows a partial sectional view (a) on the
front cover (5) side of the needle assembly (1) according
to the second embodiment and a view (b) of the assembly
(1) viewed from the distal end side. Specifically,
Figure 7 is a figure for explaining another embodiment
concerning rotation preventing means for blocking the
rotation of the hub (4) and the cover (5). In this
embodiment, explanation is omitted concerning elements
common to the elements in the first embodiment and the
same reference numerals and signs are used for the
elements.
As the cover guide (6) in this embodiment, a cover
guide same as the cover guide (6) in the first embodiment
can be used. The front-side front-back-direction grooves
(24) and the front-side circumferential-direction locking
sections (25) are formed in the guide (6).
The rotation preventing means of the front cover (5)
in this embodiment is configured from engaging concave
sections (5c) formed at the rear end portion of the cover
(5) and formed in positions adjacent to the front-side
engaging protrusions (5a) and engaging convex sections
(12b) formed at the distal end portion of the front-side
outer cylinder section (12) of the hub (4) and engaging
with the engaging concave sections (5c).
[0031]
Concerning the needle assembly (1) having the
configuration explained above, an operation in locating
the front cover (5) in the advanced position from the
retracted position is explained below.
As in the first embodiment, in a state in which the
cover (5) is located in the retracted position, the
front-side engaging protrusions (5a) formed at the rear
end portion of the cover (5) come into contact with, from
the back, the front-side circumferential-direction
locking sections (25) formed in the cover guide (6) and
block the advance of the cover (5) resisting the urging
force of the spring (14).
In this state, when the guide (6) is rotated
counterclockwise from a state shown in Figure 7(b) with
respect to the hub, the cover (5) located on the inside
of the guide (6) is also about to rotate with friction or
the like.
However, the engaging protrusions (5a) are in
contact with the engaging convex sections (12b) of the
hub (4) located in the engaging concave sections (5c).
Consequently, the rotation of the cover (5) is prevented.
As a result, the cover guide (6) and the front cover
(5) relatively rotate. The front-side engaging
protrusions (ha) relatively move along the front-side
circumferential-direction locking sections (25) and move
to positions overlapping the front-side front-backdirection
grooves (24).
When the grooves (24) move to the positions of the
engaging protrusions (5a), the protrusions (5a) are
capable of advancing along the grooves (24). The front
cover (5) advances to the advanced position with the
urging force of the spring (14).
When the front cover (5) is located in the advanced
position, as in the first embodiment, the engaging
protrusions (5a) are located in the front-coverretraction
blocking sections (26) formed on the distal
end side of the grooves (24). The advance and the
retraction of the cover (5) are blocked.
Note that, as the rotation preventing means for
preventing the rotation of the hub (4) and the front
cover (5) described in the first and second embodiments,
besides, it is also possible to couple and fix the hub
(4) and the cover (5) with the spring (14) and prevent
the rotation of the hub (4) and the cover (5) with the
spring (14). Further, it is also conceivable to
integrally form the hub (41, the cover (51, and the
spring (14) with resin.
[0032]
Figure 8 shows the needle assembly (1) according to
a third embodiment and (a) shows a state in which the
front cover (5) is located in the retracted position and
(b) shows a state in which the cover (5) is located in
the advanced position.
The needle assembly (1) in this embodiment has a
configuration in which the cover (5) is located on the
outer circumference side and the cover guide (6) is
housed on the inside of the cover (5).
The rear end portion of the cover guide (6) is
inserted between the front-side inner cylinder section
(11) and the front-side outer cylinder section (12) of
the hub (4) and is coupled and fixed not to be capable of
rotating with respect to the hub (4).
The spring (14) is housed on the inside of the cover
guide (6). A distal end portion opening of the cover
guide (6) is set to a diameter same as the diameter of
the spring (14) . Consequently, the spring (14) projects
further to the front than the opening section.
[0033]
In this embodiment, on the outer circumferential
surface of the cover guide (6), as shown in (b), the
front-side front-back-direction grooves (24), the frontside
circumferential-direction locking sections (25), and
the front-cover-retraction blocking sections (26) are
formed.
Specifically, the grooves (24) are formed on the
outer circumferential surface of the cover guide (6)
toward the front-back direction and configured to house
the front-side engaging protrusions (5a) formed on the
inner circumferential surface of the front cover (5).
The locking sections (25) are grooves formed
continuously in the circumferential direction from the
rear end portions of the grooves (24). Protrusions (25a)
for blocking the movement of the engaging protrusions
(5a) are formed halfway in the locking sections (25).
The blocking sections (26) include retraction
blocking protrusions (26b) formed near the distal end
portions of the grooves (24). When the engaging
protrusions (5a) are located at the distal ends of the
grooves (24), the blocking sections (26) engage with the
engaging protrusions (5a) from the back to block the
retraction of the cover (5) .
Further, grooves (24a) for assembly branching from
the front-side front-back-direction grooves (24) are
formed in positions adjacent to the back of the blocking
sections (26) in this embodiment.
The grooves (24a) for assembly are formed to the
distal end of the guide (6). When the needle assembly
(1) is assembled, the engaging protrusions (5a) of the
front cover (5) are intruded into the grooves (24a) for
assembly. The engaging protrusions (5a) are led into the
locking sections (25) via the front-side front-backdirection
grooves (24).
[a0341
The front cover (5) is formed to have a cylindrical
shape and surround the cover guide (6) and the front-side
outer cylinder section (12) of the hub (4) and provided
to be capable of rotating relatively to the hub (4) and
the cover guide (6).
The distal end portion of the front cover (5) is
located further in the front than the distal end portion
of the guide (6). The opening section of the cover (5)
is formed smaller in diameter than the distal end opening
section of the guide (6).
The spring (14) is elastically in contact with, from
the back, the rear side of the distal end opening section
of the front cover (5) and always urges the cover (5)
toward the advanced position.
On the inner circumferential surface of the front
cover (5), the front-side engaging protrusions (5a),
which engage with the front-side front-back-direction
grooves (24) and the front-side circumferential-direction
locking sections (25) formed on the outer circumference
of the cover guide (61, are provided.
In a state in which the front-side engaging
protrusions (5a) are housed in the locking sections (25),
the front cover (5) is regulated from moving to the front
and held in the retracted position. In a range in which
the protrusions (5a) move within a range in which the
locking sections 25 are formed, the cover (5) and the
guide (6) are capable of relatively rotating.
[00351
Concerning the needle assembly (1) having the
configuration explained above, an operation in locating
the front cover (5) in the advanced position from the
retracted position is explained.
When the front cover (5) is located in the retracted
position, the front-side engaging protrusions (5a) formed
on the inner circumferential surface of the cover (5) are
housed in the front-side circumferential-direction
locking sections (25) formed on the outer circumferential
surface of the cover guide (6) and block the advance of
the cover (5) resisting the urging force of the spring
(14).
When the front cover (5) is rotated with respect to
the hub (4) and the cover guide (6) from this state, the
engaging protrusions (5a) relatively move along the
locking sections (25) and move to positions overlapping
the front-side front-back-direction grooves (24) of the
guide (6).
When the grooves (24) move to the positions of the
engaging protrusions (5a), the protrusions (5a) are
capable of advancing along the grooves (24). The cover
(5) advances to the advanced position with the urging
force of the spring (14).
When the front cover (5) is located in the advanced
position, the engaging protrusions (5a) are located in
the blocking sections (26) formed on the distal end side
of the grooves (24). The advance and the retraction of
the cover (5) are blocked.
[00361
Note that, in the embodiments explained above, the
front cover (5) is urged by the spring (14) functioning
as urging means. However, it is also possible to adopt
other components as the urging means.
For example, it is also possible that a member
having a bellows shape is adopted as the urging means,
when the cover (5) is located in the retracted position,
the bellows-shaped member maintains a contracted state
and, thereafter, when the cover (5) is located in the
advanced position, the cover (5) is advanced using an
urging force of the bellows-shaped member returning to an
original expanded state.
Reference Signs List
to0371
1 needle assembly
2 front cannula
3 back cannula
4 hub
5 front cover
5a front-side engaging protrusion
6 cover guide
7 back cover
24 front-side front-back-direction groove
25 front-side circumferential-direction locking section
33a back-side engaging protrusion
41 coupling section
42 back-side front-back-direction groove
43 back-side circumferential-direction locking section

Claims
[Claim 11
A needle assembly comprising:
a cannula in which a puncture section is formed;
a hub that holds the cannula; and
a cover provided to be movable to a first position
where the cannula is exposed with respect to the hub and
a second position where a distal end projects further
than the cannula, characterized in that
in the cover, a circumferential-direction locking
section formed in a circumferential direction and a
front-back-direction groove formed in a front-back
direction to continue to the circumferential-direction
locking section or an engaging protrusion movable along
the circumferential-direction locking section and the
front-back-direction groove are provided,
the movement of the cover in the front-back
direction is blocked in a state in which the cover is
located in the first position and the engaging protrusion
is housed in the circumferential-direction locking
section, and
when the engaging protrusion moves along the
circumferential-direction locking section and moves to
the front-back-direction groove, the engaging protrusion
becomes movable along the front-back-direction groove to
allow the movement of the cover to the second position.
[Claim 21
The needle assembly according to claim 1,
characterized in that
the cannula is a front cannula, at a distal end of
which the puncture section is formed, and the cover is a
front cover provided to be movable to a retracted
position serving as the first position where the cannula
is exposed with respfct to the hub and an advanced
position serving as the second position where the distal
end projects further to a front than the cannula,
urging means for urging the front cover toward the
advanced position and a cover guide that houses at least
a part of the urging means and the front cover are
provided to be capable of rotating in the circumferential
direction with respect to the hub and the front cover,
the engaging protrusion is provided in one of the
cover guide and the front cover, and the circumferentialdirection
locking section and the front-back-direction
groove are provided in the other,
in a state in which the front cover is located in
the retracted position, the engaging protrusion engages
with the circumferential-direction locking section and
blocks advance of the front cover resisting an urging
force of the urging means, and
when the front cover is rotated with respect to the
cover guide, the engaging protrusion moves from the
circumferential-direction locking section to the frontback-
direction groove, and the front cover moves to the
advanced position with the urging force of the urging
means.
[Claim 31
The needle assembly according to claim 2,
characterized in that rotation preventing means is
provided, the rotation preventing means preventing the
front cover and the hub from relatively rotating when the
front cover is located in the retracted position, even if
the cover guide rotates relatively to the front cover and
the hub.
[Claim 41
The needle assembly according to claim 1,
characterized in that
the cannula is a front cannula, at a distal end of
which the puncture section is formed, and the cover is a
front cover provided to be movable to a retracted
position serving as the first position where the front
cannula is exposed with respect to the hub and an
advanced position serving as the second position where
the distal end projects further to a front than the front
cannula,
Urging means for urging the front cover toward the
advanced position is provided, a cylindrical cover quid
coupled to the hub is provided on an inside of the front
cover, and the front cover is provided to be capable of
rotating in the circumferential direction with respect to
the hub and the cover guide,
the engaging protrusion is provided in one of the
cover guide and the front cover, and the circumferentialdirection
locking section and the front-back-direction
groove are provided in the other,
in a state in which the front cover is located in
the retracted position, the engaging protrusion engages
with the circumferential-direction locking section and
blocks advance of the front cover resisting an urging
force of the urging means, and
when the front cover is rotated with respect to the
cover guide, the engaging protrusion moves from the
circumferential-direction locking section to the frontback-
direction groove, and the front cover moves to the
advanced position with the urging force of the urging
means.
[Claim 51
The needle assembly according to claim 1,
characterized in that
the cannula is a back cannula in which a puncture
section punctured into a lid section of liquid supplying
means is formed at a rear end, and liquid is supplied
from the liquid supplying means to the back cannula by
piercing the puncture section of the back cannula through
the lid section of the liquid supplying means,
the cover is a back cover movable to an advanced
position serving as the first position and a retracted
position serving as the second position and including a
coupling section coupled to a coupled section of the
liquid supplying means,
in a state in which the back cover is located in the
advanced position, the coupled section of the liquid
supplying means is coupled to the coupling section, and
the puncture section of the back cannula pierces through
the lid section of the liquid supplying means, and
in a state in which the back cover is located in the
retracted position, a rear end portion of the back cover
projects further to a back than the puncture section of
the back cannula and covers the puncture section.
[Claim 63
The needle assembly according to claim 5,
characterized in that the back cover has a cylindrical
shape and surrounds an outer circumference of the hub.
[Claim 71
The needle assembly according to claim 5 or 6,
characterized in that the front-back-direction groove and
the circumferential-direction locking section are formed
in the back cover, and the engaging protrusion is formed
on an outer surface of the hub.
[Claim 81
The needle assembly according to claim 7,
characterized in that a housing section that houses the
engaging protrusion is formed in a front of the frontback-
direction groove and the housing section is formed
to pierce through the back cover from an inside to an
outside to enable the engaging protrusion to be visually
recognized from an outside when the engaging protrusion
is housed in the housing section.