[OOOl]
The present invention r e l a t e s t o improvement of a p r i n t e r frame
made of sheet metal for a p r i n t e r .
2. Related A r t
[0002]
Printing i s done in a s e r i a l p r i n t e r on recordingpaper delivered
from a r o l l of recording paper stored i n a recording paper storage
unit by means of a printhead mounted on a head carriage t h a t t r a v e l s
b i d i r e c t i o n a l l y on a carriage guide r a i l . This type of p r i n t e r has
a p r i n t mechanismunit configuredwithprinter components mounted on
a p r i n t e r frame made of sheet metal, and t h e p r i n t mechanism unit i s
covered by a p r i n t e r case made of p l a s t i c .
[0003]
P r i n t e r s with t h i s type of p r i n t e r frame are disclosed i n
JP-A-2010-83147 and JP-A-2004-351928. The p r i n t e r s disclosed i n
JP-A-2010-83147 and JP-A-2004-351928 have an access frame attached
t o the p r i n t e r frame, and when the access frame opens, the recording
paper storage unit t h a t holds the recording paper r o l l opens, and the
recording paper conveyance path t h a t goes from the recording paper
storage unit p a s t t h e p r i n t position of the printhead and t o the
recording paper e x i t opens.
[0004]
The p r i n t e r frame i s made from a single piece of sheet metal
throughanumber ofbending andshapingprocesses. More s p e c i f i c a l l y ,
the p r i n t e r frame has abottomportionwithleftand r i g h t side walls,
for example, t h a t are bent and shaped t o extend toward the top of the
p r i n t e r from the widthwise ends of the bottom portion. A carriage
guide r a i l spans between the l e f t and r i g h t s i d e walls i n the middle
between t h e f r o n t and back ends of the p r i n t e r . A loading u n i t for
an ink ribbon c a s s e t t e is located a t a p o s i t i o n in f r o n t of t h e
carriage guide r a i l , and t h e s t o r a g e compartment for the recording
paper r o l l is located a t a position behind the carriage guide r a i l s .
[0006]
The bottom portion and l e f t and r i g h t s i d e walls of the p r i n t e r
frame are made by bending and shaping, and a p l u r a l i t y of places f o r
i n s t a l l i n g p a r t s (such as screw holes, bent flanges f o r i n s t a l l i n g
p a r t s , and notches for mounting p a r t s ) are formed i n the bottom and
side wall panels. The o v e r a l l construction of the p r i n t e r frame i s
therefore complex, assuring the dimensional precision of each p a r t
i s not easy, and the shapes of the dies used t o stamp the p r i n t e r frame
a r e unavoidably complicated. In addition, a c t i o n s such as spreading
t h e l e f t and r i g h t side walls apart may be required when i n s t a l l i n g
various p r i n t e r componentstotheprintermain frame, making assembly
d i f f i c u l t . Formi-ng notches and holes for assembling various p r i n t e r
components c a n a l s o lower mechanical strength, i n c l u d i n g t h e f l e x u r a l
strength of t h e p r i n t e r frame and the r i g i d i t y of p a r t s of the frame.
SUMMARY
[0007]
With consideration for t h e foregoing, the present invention
provides a p r i n t e r having a p r i n t e r frame t h a t has an uncomplicated
construction, can be manufactured with good p r e c i s i o n , and enables
easy i n s t a l l a t i o n of p a r t s . Another object of the invention i s t o
provide a p r i n t e r having a p r i n t e r frame with high s t r e n g t h and
r i g i d i t y .
[0008]
A p r i n t e r according t o one aspect of the invention has a p r i n t e r
frame t o which p r i n t e r components a r e disposed. The p r i n t e r frame
includes a b a s e frame a n d a p r i n t e r m a i n f r a m e i n c l u d i n g a t l e a s t f i r s t ,
second, and t h i r d frames attached t o the base frame; a carriage guide
r a i l t h a t guides a head carriage carrying a printhead and spans the
f i r s t frame; and a recording paper storage unit t h a t holds recording
paper disposed between the second frame and the t h i r d frame.
[0009]
The p r i n t e r main frame of the p r i n t e r according t o t h i s aspect
of the invention is composed of plural frames. Increasing the
manufacturing precision of each part is therefore simple compared
with manufacturing the p r i n t e r main frame by bending and shaping a
s i n g l e m e t a l p l a t e . Complexdies are alsonotneededto stamp the frame
p l a t e s . The ease of assemblingprinter componentstotheprintermain
frame i s also improved. For example, assembling components of the
recording paper storage unit between the second and t h i r d frames can
be done without deforming the side panels or deforming the assembled
p a r t s , and is therefore extremely simple compared with assembling
components between the l e f t and r i g h t side panels of a p r i n t e r main
frame made from a single metal sheet. Furthermore, when i n s t a l l i n g
p a r t s that require i n s t a l l a t i o n with high precision, such as when
i n s t a l l i n g the carriage guide r a i l t o the p r i n t e r main frame, the
carriage guide r a i l canbe s i m p l y i n s t a l l e d t o t h e single f i r s t frame.
The f i r s t frame can be manufactured with b e t t e r precision than a
p r i n t e r main frame having a monolithic construction. The attachment
p a r t s o f t h e carriage guide r a i l canalsobe formedwithgoodprecision.
The carriage guide r a i l canthereforebe assembledtotheprintermain
frame with good precision.
[OOlO]
Preferably, the second frame and the t h i r d frame each have a
f i r s t fastening p a r t fastened t o the base frame, and a second
fastening part fastened t o the f i r s t frame.
[0011]
The second frame and t h i r d frame are r e s p e c t i v e l y fastened t o
the base frame, and are also fastened t o the f i r s t frame. As a r e s u l t ,
the strength and rigidity ofthe complete printer main frame composed
of multiple frames can be increased.
[0012]
Further preferably, a guide rail attachment part of the first
frame to which the carriage guide rail is attached has a base support
part supported by the base frame.
[0013]
If the printer is accidentally dropped, for example, a strong
impact force will be applied from the head carriage side, which
carries the heavy printhead, to the guide rail attachment part of the
first frame supporting the carriage guide rail. The force of this
impact on the guide rail attachment part of the first frame is borne
on the base frame through the base support part. The drop resistance
of the printer can therefore be improved.
[0014]
The printer main frame of the printer according to the invention
may be configured as described below.
More specifically, when the head carriagemoves widthwise tothe
printer on a transverse axis, the base frame is a frame with a
rectangular contour extending on the transverse axis and a
longitudinal axis perpendicular to the transverse axis; the first,
second, and third frames are disposed to the top of the base frame
on the vertical axis; the secondand third frames are disposedtoback
of the first frame on the longitudinal axis; the first frame includes
a first frame bottom portion extending on the transverse axis and the
longitudinal axis, a first frame left side portion bending and
extending up on the vertical axis from the left edge part of the first
frame bottom portion on the transverse axis, and a first frame right
side portion bending and extending up on the vertical axis from the
right edge part of the first frame bottom portion on the transverse
axis; the opposite axial end parts of the carriage guide rail are
respectively disposed between the first frame left side portion and
the f i r s t frame r i g h t side portion; the second frame i s a frame
extending to the back on the longitudinal axis a t a position behind
the f i r s t frame l e f t side portion on the longitudinal axis; and the
t h i r d frame is a frame extending t o the back on the longitudinal axis
a t a position behind the f i r s t frame right side portion on the
longitudinal a x i s .
[0015]
Furtherpreferably, a p r i n t e r according t o another aspect o f t h e
invention also has a recording paper conveyance path extending from
the recording paper storage unit past the p r i n t position of the
printhead; and a paper chaff prevention shield disposed between the
recording paper conveyance path and the carriage guide r a i l , and
extending in a f i r s t direction, which i s t h e d i r e c t i o n along the
carriage guide r a i l .
[0016]
Yet further preferably, the p r i n t e r has a detector t h a t detects
the current position of the head carriage; and the foreign object
shield panel is disposedbetween the recording paper conveyance path
and the detector.
[0017]
The printhead p r i n t s on recording paper near the carriage guide
r a i l i n the p r i n t e r . The recording paper conveyance path from the
recording paper storage unit t o the recording paper e x i t passes near
the carriage guide r a i l . Paper chaff and other foreign matter may f a l l
or be scattered from the recording paper being conveyed through the
recordingpaper conveyance p a t h p a s t the p r i n t position. Such foreign
matter can then s t i c k t o the carriage guide r a i l near the recording
paper conveyance path. More p a r t i c u l a r l y , because a dot impact
printhead s t r i k e s the recording paper with dot wires through an ink
ribbon, paper chaff or other foreign matter can e a s i l y f a l l or be
scattered by vibration produced when printing. I f foreign matter
s t i c k s t o the carriage guide r a i l , the foreign matter can clog the
s l i d i n g area between the carriage guide r a i l and the head c a r r i a g e ,
possiblyincreasingtheloadonthe carriagemotor t h a t move s t he head
c a r r i a g e . An o p t i c a l sensor for d e t e c t i n g the p o s i t i o n (home
p o s i t i o n ) of the head carriage i s often located near the c a r r i a g e
guide r a i l . In t h i s event, f o r e i g n m a t t e r from the conveyed recording
paper may also s t i c k t o the r e c e p t o r s u r f a c e of the sensor and
contribute t o sensor detection e r r o r s .
[ 0 0 18 ]
In t h i s aspect of the invention, the area where paper chaff and
o t h e r f o r e i g n m a t t e r is producedis separated fromthe c a r r i a g e guide
r a i l and the detector by the foreign object s h i e l d panel. Foreign
matter t h a t i s produced c a n t h e r e f o r e b e prevented or suppressed from
entering t o the s l i d i n g p a r t s of the carriage guide r a i l and head
c a r r i a g e , andthe detection surface o f t h e d e t e c t o r , andproblems such
as increasing the load on the carriage motor o r d e t e c t i o n e r r o r s by
the d e t e c t o r due t o such foreign matter s t i c k i n g can be avoided.
[0019]
Further preferably i n another aspect of the invention, the head
c a r r i a g e has a s l o t extending i n the first d i r e c t i o n a t a p o s i t i o n
between the recording paper conveyance path and t h e c a r r i a g e guide
r a i l ; and the foreign object shield panel i s a panel of a s p e c i f i c
width extendingin the f i r s t d i r e c t i o n w i t h p a r t o f t h e foreign object
s h i e l d panel i n s e r t e d t o the s l o t .
[0020]
By i n s e r t i n g p a r t of the foreign o b j e c t s h i e l d panel i n the s l o t
formed i n the head c a r r i a g e , the path foreign matter must t r a v e l t o
reach the carriage guide r a i l or d e t e c t o r area from t h e s i d e where
f o r e i g n m a t t e r i s produced on the recording paper conveyance path,
f o r example, canbemade convoluted. As a r e s u l t , penetration of paper
chaff and o t h e r f o r e i g n matter t o the c a r r i a g e guide r a i l or d e t e c t o r
side can be r e l i a b l y prevented or suppressed.
[ 00211
I n another aspect of the invention, the f o r e i g n o b j e c t s h i e l d
panel is attached t o t h e f i r s t frame.
[0022]
Further preferably, the p r i n t e r a l s o has a head ground member
t h a t i s conductive, attachedtotheheadcarriage, a n d c o n t a c t i n g b o t h
a ground terminal p a r t of the printhead and t h e conductive c a r r i a g e
guide r a i l ; and a conductive guide r a i l ground member grounding t h e
c a r r i a g e guide r a i l t o the f i r s t frame.
100231
In a s e r i a l p r i n t e r , t h e printhead i s mounted on a head c a r r i a g e
and moves along a carriage guide r a i l . The moving printhead and t h e
s t a t i o n a r y c o n t r o l board are e l e c t r i c a l l y connected through a
f l e x i b l e p r i n t e d c i r c u i t . When the number of head elements i n t h e
printhead i n c r e a s e s , the number of l i n e s needed t o drive the head
elements a l s o i n c r e a s e s . In t h e case of a dot impact matrix head, f o r
example, the number of l i n e s f o r driving the many wires i n c r e a s e s .
A ground l i n e f o r grounding t h e printhead is generally included i n
t h e f l e x i b l e p r i n t e d c i r c u i t , but when the number of l i n e s f o r d r i v i n g
t h e p r i n t h e a d i n c r e a s e s , theremay not be s u f f i c i e n t space t o provide
a ground l i n e i n the f l e x i b l e p r i n t e d c i r c u i t .
[0024]
In t h e invention, t h e ground l i n e f o r grounding the printhead
t o the p r i n t e r frame i s formed using the c a r r i a g e guide r a i l .
Therefore, t h e r e i s no need t o provide a ground l i n e i n the f l e x i b l e
p r i n t e d c i r c u i t t h a t connects t h e moving printhead t o the s t a t i o n a r y
p r i n t e r control board s i d e .
[0025]
Further p r e f e r a b l y , the guide r a i l ground member has a frame
fastening p a r t fastened t o the f i r s t frame, and a guide r a i l pressure
p a r t pushing a g a i n s t one a x i a l end face of t h e c a r r i a g e guide r a i l .
100261
Bypushing against the a x i a l end o f t h e c a r r i a g e guide r a i l using
the guide r a i l groundmember disposed for grounding t h e c a r r i a g e guide
r a i l t o the f i r s t frame, c h a t t e r i n the carriage guide r a i l can be
prevented or suppressed. When the head carriage carrying the I
I
printheadmoves back and f o r t h on the carriage guide r a i l , the s l i d i n g
load of the head c a r r i a g e can c r e a t e play i n the p a r t of the c a r r i a g e
guide r a i l supported on the f i r s t frame side, such as i n t h e p r e s s - f i t
portion. When play develops i n the carriage guide r a i l , c h a t t e r can
occur i n the carriage guide r a i l i n t h e a x i a l d i r e c t i o n i n conjunction
with the s l i d i n g of the head c a r r i a g e . In the invention, the c a r r i a g e
guide r a i l is pushed i n the a x i a l d i r e c t i o n by the guide r a i l ground
I
member. As a r e s u l t , problems such as s h i f t i n g the p r i n t p o s i t i o n of I
the printhead when t h e head c a r r i a g e t r a v e l s on the outbound stroke,
and t h e p r i n t p o s i t i o n of the printhead on t h e r e t u r n stroke, due t o
t h i s c h a t t e r i n the a x i a l d i r e c t i o n of the c a r r i a g e guide r a i l can
be avoided. 1
I
[00271
A p r i n t e r according t o the invention preferably a l s o has an
e c c e n t r i c shaft p a r t disposed t o the a x i a l end p a r t of the c a r r i a g e
guide r a i l ; an adjustment member fastened t o t h e e c c e n t r i c s h a f t p a r t
and e c c e n t r i c a l l y r o t a t i n g t h e c a r r i a g e guide r a i l through a s p e c i f i c
angular range around the center of t h e e c c e n t r i c s h a f t p a r t ; and a
f i r s t fastening p a r t and a second fastening p a r t t h a t f i x the
adjustment member t o a s p e c i f i c angular p o s i t i o n around the center
of t h e eccentric s h a f t p a r t . I
[0028]
The printer, has a printhead, and a gap adjustment mechanism f o r
a d j u s t i n g the gap between the printhead and the opposing p l a t e n . An
I
example of the gap adjustment mechanism is a mechanism t h a t can a d j u s t 1
the gap by e c c e n t r i c a l l y r o t a t i n g t h e carriage guide r a i l . With t h i s
type of gap adjustment mechanism, an e c c e n t r i c s h a f t p a r t is formed
i n t e g r a l l y t o the a x i a l end of the carriage guide r a i l , and an
adjustment member extending i n a d i r e c t i o n perpendicular t o t h e
I
eccentric shaft part is attached. The adjustment member is disposed
on the outside side o f t h e side wall of the printermain frame. Because
the carriage guide r a i l turns eccentrically when the adjustment
member turns, the carriage guide r a i l can be moved toward and away
from t h e p l a t e n . The gap between the platen and the printhead carried
on the head carriage t h a t moves along the carriage guide r a i l can
thereby be increased or decreased.
[0029]
To hold the position a f t e r adjusting the gap, a l a t c h p a r t is
generallyformedtothe adjustmentmember, a n d a p l u r a l i t y of channels
t h a t the l a t c h part can engage are formed on the side panel side. More
specifically, a latch part is formed t o the adjustment member a t a
position opposing t h e s i d e panel of the p r i n t e r main frame. Multiple
channels are formed a t a s p e c i f i c angular i n t e r v a l on the surface of
the side panel t o f i x the adjustment member a t the plural angular
positions. The latch part engages one of the channels due t o the
pressure of the adjustment member, and the adjustment member is
thereby held a t a specific angular position. When the adjustment
member i s rotated in resistance t o t h i s pressure t o the channel
corresponding t o the desired angular position and engaged with the
channel, the adjustment member can be held a t that angular position.
[0030]
When a heavy printhead is used, such as when a dot impact head
with many wires i s used, the engaging force of the l a t c h p a r t and the
channel in the side panel on the frame side may not be able t o hold
the carriage guide r a i l a t the specified angular position. Because
many wires are driven when printing with the printhead, a strong
impact force is applied from the printhead through the head carriage
andcarriage guide r a i l towhere the l a t c h p a r t and the channel engage.
I f the latch p a r t disengages the channel due t o t h i s impact force,
the adjustment member turns, the carriage guide r a i l r o t a t e s
eccentrically, and the gap changes.
[0031]
When a large printhead is used such as in a dot impact printer,
a strong impact force thus acts through the carriage guide rail on
the adjustment member when printing due to the printing operation of
the heavy printhead. By rotating the adjustment member, the carriage
guide rail rotates eccentrically around the center of the eccentric
shaft part, and the gap between the printhead and the opposing platen
is adjusted. A fastening mechanism composed of a latch part and a
channel is usedto hold the adjustment member at the angular position
after adjustment. When a strong impact force is applied, holding the
adjustment member reliably so that it does not turn may be diffi-cult
with a single fastening mechanism. The invention has first and second
fastening parts, however, and can therefore prevent problems
resulting from the adjustment member turning and the gap changing.
[0032]
Further preferably, the second fastening part has a curved
channel of a specific width formed through a specific angular range
centered on the eccentric shaft part, a set screw that can slide in
the curved channel, and a screw hole into which the set screw can be
screwed; the curved channel is formed in the adjustment member; the
screw hole is formed in the first frame at a position opposing the
curved channel; and the set screw fixes the adjustment member to the
first frame by screwing into the screw hole through the curved
channel.
[0033]
By having a screw-type second fastening mechanism, the
adjustment member can be reliably held at the adjusted angular
position. Furthermore, by using a latch-type fastening mechanism as
the first fasteningpart, the adjustment member is automaticallyheld
to the adjusted angular position when the gap is adjusted, and
adjustment is simple.
COO341
Further preferably, a p r i n t e r according t o the invention a l s o
has a fourth frame attached t o the f i r s t frame; and a t r a v e l space
formedbetweenthe f i r s t frame andthe fourth frame t o enablemovement
of the head carriage along the c a r r i a g e guide r a i l ; one end of the
t r a v e l space in t h e d i r e c t i o n along the carriage guide r a i l being a
f i r s t opening, and t h e o t h e r end being a second opening; and a f i r s t
cover p l a t e t h a t covers a t l e a s t p a r t of the f i r s t opening, and a
second cover p l a t e t h a t covers a t l e a s t p a r t of the second opening,
being disposed t o the fourth frame.
[00351
The dot impact head becomes hot i n a d o t impact p r i n t e r , f o r
example. I f the operator a c c i d e n t a l l y touche s t hehot dot impact head,
the operator couldbe burned. However, because f i r s t and second cover
p l a t e s a r e disposed t o the ends of the fourth frame disposed t o the
f i r s t frame i n t h i s aspect of the invention, t h e o p e r a t o r ' s f i n g e r s
can be r e l i a b l y prevented from touching the dot impact head.
[0036]
Preferably, a loading u n i t f o r an ink ribbon c a s s e t t e s t o r i n g
an ink ribbon from which ink i s t r a n s f e r r e d t o recording paper by the
printhead is disposed between the p a r t s of the f i r s t frame spanned
by the carriage g u i d e r a i l ; andthe f i r s t andsecondcover p l a t e s guide
the ink ribbon c a s s e t t e being i n s t a l l e d t o the loading u n i t i n t o t h e
loading u n i t , and support the ink ribbon delivery s i d e portion and
t h e i n k ribbon recovery side portion of the ink ribbon c a s s e t t e
i n s t a l l e d t o the loading u n i t
[00371
In a dot impact p r i n t e r , dots a r e p r i n t e d by s t r i k i n g the
recordingpaper with the wires o f t h e printhead through an ink ribbon.
The ink ribbon i s held i n an ink ribbon c a s s e t t e , and i s removably
i n s t a l l e d t o a c a s s e t t e loading u n i t disposed t o t h e p r i n t e r . The
c a s s e t t e loading u n i t of the p r i n t e r main frame i s l o c a t e d between
the l e f t and r i g h t side panels of t h e p r i n t e r main frame. The ink
ribbon cassette installed to the cassette loading unit has an ink
ribbon storage unit, a delivery-side arm protruding from one end of
the storage unit, and a recovery-side arm extending parallel to the
delivery-side arm from the other end of the storage unit. A delivery
opening is formed in the delivery-side arm, and a recovery opening
is formed in the recovery-side arm. The ink ribbon is pulled from the
deliveryopening, travels between the distal endofthe delivery-side
arm and the recovery-side arm, and is recovered from the recovery
opening into the storage unit. The portion of the ink ribbon between
the two arms is disposed parallel to the carriage guide rail between
the printhead and the platen.
[0038]
The cassette loading unit of a printer according to the related
art has opposing arm surfaces on the arm parts of the ink ribbon
cassette that face each other from the inside. One opposing arm
surface is defined by an engaging lever. A protrusion that can engage
the engaging lever is formedon one armpart ofthe ink ribbon cassette.
When installing the ink ribbon cassette to the cassette loading unit,
the arm on the side where the protrusion is formed is pushed in to
the cassette loading unit until the protrusion engages the engaging
lever fromthe opposite side as the installationdirection. The other
armpart is thenpushedin along the opposing armsurface. As a result,
the ink ribbon cassette is installed so that it does not separate from
the cassette loading unit.
[0039]
However, with the installation mechanism of this ink ribbon
cassette, one arm part of the ink ribbon cassette is installed to the
cassette loading unit, and then the other arm part is installed to
the cassette loading unit. This requires a two stage installation
operation of installing the ink ribbon cassette to the cassette
loading unit with the ink ribbon cassette tilted so that one arm part
is lower and the other armpart is higher, andthenpushingthe higher
arm part into the cassette loading unit. The operation of installing
one arm with the ink ribbon cassette tilted and then installing the
other arm part is thus complicated and installation is difficult.
[0040]
The ease of installing the ink ribbon cassette also decreases
with the installation mechanism of the related art when trying to
reduce device size and increase the size of the dot impact head. For
example, if the size of the ink ribbon cassette is increased without
increasing the size of the printer, the clearance between the left
and right arm parts of the ink ribbon cassette being installed and
the cassette loading unit and the left and right side panels of the
printer main frame becomes narrow on both sides, and the ease of
installing the ink ribbon cassette is impaired.
[0041]
The.re is also not enough space for an engaging lever that
prevents the ink ribbon cassette from separating from the cassette
loading unit, and the ink ribbon cassette installation mechanism
according to the related art cannot be used.
[0042]
The printer preferably also has a loading unit for an ink ribbon
cassette storing an ink ribbon from which ink is transferred to
recording paper by the printhead disposed between the parts of the
first frame spanned by the carriage guide rail; and the first and
second cover plates guide the ink ribbon cassette being installed to
the loading unit into the loading unit, and support the ink ribbon
delivery side portion and the ink ribbon recovery side portion ofthe
ink ribbon cassette installed to the loading unit.
[0043]
Because the ink ribbon cassette is guided into the cassette
loading unit and the arm parts of the installed ink ribbon cassette
are supported using the first and second cover plates disposed on the
ends of the fourth frame, less installation space is required, and
the ink ribbon c a s s e t t e can be guided and supported using few p a r t s .
[0044]
To prevent increasing the p a r t s count and complicating
construction, the f i r s t and secondcover p l a t e s are p r e f e r a b l y formed
bybendingthe opposite ends o f t h e f o u r t h frame i n t h e d i r e c t i o n a l o n g
the c a r r i a g e guide r a i d .
[0045]
F u r t h e r p r e f e r a b l y , t o improve t h e ease of i n s t a l l i n g t h e ink
ribbon c a s s e t t e , the p r i n t e r preferably a l s o has a loading u n i t f o r
an ink ribbon c a s s e t t e s t o r i n g an ink ribbon disposed between the
p a r t s of the f i r s t frame spanned by t h e carriage guide r a i l ; f i r s t
and second c a s s e t t e guides disposed t o the opposite ends of the
loadingunitinadirectionalongthe c a r r i a g e guide r a i l , and guiding
the ink ribbon c a s s e t t e t o the loading u n i t ; and f i r s t and second
engaging p a r t s disposed t o the opposite ends of t h e loading u n i t i n
a d i r e c t i o n a l o n g t h e c a r r i a g e guide r a i l , andengaging the ink ribbon
c a s s e t t e t h a t is guided by the f i r s t and second c a s s e t t e guides and
i n s t a l l e d t o t h e loading u n i t ; and the f i r s t and secondengagingparts,
and f i r s t and second c a s s e t t e - s i d e engaging p a r t s formed on t h e ink
ribbon c a s s e t t e t o engage the f i r s t and second engaging p a r t s , a r e
a snap f i t construction.
[0046]
T h e p r i n t e r t h u s comprisedaccordingtotheinventioncanbeused
i n a dot impact p r i n t e r having a dot impact p r i n t h e a d .
BRIEF DESCRIPTION OF THE DRAWINGS
[0047]
FIG. 1 i s an e x t e r n a l oblique view showing a p r i n t e r according
t o the invention.
FIG. 2 i s an e x t e r n a l oblique view showing t h e p r i n t e r i n FIG.
1 when an access cover i s open.
FIG. 3 i s a p a r t i a l section view showing the c o n f i g u r a t i o n of
the recording paper conveyance path of t h e p r i n t e r i n FIG. 1.
FIG. 4 is an oblique view of t h e p r i n t mechanism u n i t i n s i d e t h e
p r i n t e r i n FIG. 1.
FIG. 5 i s an exploded oblique view of the p r i n t mechanism u n i t
shown i n FIG. 4 with t h e i n k ribbon c a s s e t t e removed.
FIG. 6 i s an oblique view of the p r i n t mechanism u n i t i n FIG.
5 with some p a r t s removed.
FIG. 7 i s an oblique view of the p r i n t e r frame of t h e p r i n t
mechanism u n i t shown i n FIG. 4 .
FIG. 8 i s an oblique view and a s e c t i o n view of p a r t of t h e gap
adjustment mechanism of t h e p r i n t e r i n FIG. 1.
FIG. 9 is an o b l i q u e v i e w a n d a s i d e v i e w i l l u s t r a t i n g t h e ground
path of the printhead of t h e p r i n t e r i n FIG. 1.
DESCRIPTION OF EMBODIMENTS
[0048]
A p r e f e r r e d embodiment of a p r i n t e r according t o t h e p r e s e n t
invention is described below with reference t o the accompanying
f i g u r e s .
[0049]
General c o n f i g u r a t i o n of t h e p r i n t e r
FIG. 1 i s an e x t e r n a l oblique view showing a p r i n t e r according
t o a p r e f e r r e d embodiment of t h e invention, FIG. 2 i s an e x t e r n a l
oblique view showing t h e p r i n t e r with an access cover open, and FIG.
3 is a p a r t i a l s e c t i o n view i l l u s t r a t i n g t h e recording paper
conveyance path of the p r i n t e r .
Note t h a t i n t h e f i g u r e s andbelow t h e d i r e c t i o n across t h e width
of the p r i n t e r is r e f e r r e d t o a s t h e t r a n s v e r s e a x i s X, t h e d i r e c t i o n
through t h e f r o n t and back as t h e l o n g i t u d i n a l a x i s Y, and t h e
d i r e c t i o n through the top and bottom as t h e v e r t i c a l a x i s Z . The l e f t
and r i g h t s i d e s of t h e p r i n t e r mean the l e f t and r i g h t s i d e s on t h e
t r a n s v e r s e a x i s X when looking a t the p r i n t e r from t h e f r o n t .
[0050]
As described below with reference t o the accompanying f i g u r e s ,
t h e p r i n t e r 1 has a p r i n t e r case 2 including a b a s i c a l l y rectangular
main case 3 covering the f r o n t , back, l e f t , and r i g h t s i d e s ; a f r o n t
access cover case 4 covering the f r o n t p a r t of the top of t h e p r i n t e r ;
and a back access cover case 5 covering the back p a r t of the top of
t h e p r i n t e r . The p r i n t mechanism u n i t 30 comprising p r i n t e r
components disposed t o a p r i n t e r frame made of sheet metal as
described f u r t h e r below i s covered by the p r i n t e r case 2.
A recording paper e x i t 6 of a s p e c i f i c width extending on the
transverse a x i s X is formed between the f r o n t access cover case 4 and
t h e back access cover case 5.
A power switch 7 is disposed t o the p r i n t e r case 2 a t the f r o n t
of the p r i n t e r . The power switch 7 i s located i n the r i g h t corner area
on t h e t r a n s v e r s e axis X. A recess t h a t i s s e t back toward the back
of the p r i n t e r i s formed a t t h e f r o n t of the p r i n t e r i n the middle
on t h e t r a n s v e r s e a x i s XI and the bottom of t h i s recess i s a f l a t
operating panel 8 t h a t faces up.
[0051]
The operating panel 8 is formed by a panel sheet, and a round
display u n i t s 8a, 8b, 8c, which are the e m i t t i n g s u r f a c e s of LEDs,
and a panel switch 8d are disposed t o the panel sheet. Display u n i t
8a is an on/off i n d i c a t o r t h a t l i g h t s steady when the power switch
7 i s on, display u n i t 8b is an e r r o r i n d i c a t o r t h a t l i g h t s steady when
an e r r o r occurs, and display u n i t 8c i s a no-paper i n d i c a t o r t h a t
l i g h t s steady when there is no recording paper.
Display u n i t 8a l i g h t s blue, and display u n i t s 8b and 8c l i g h t
orange, for example. While combinations of green and red i n d i c a t o r s
a r e common i n t h e r e l a t e d a r t , u s i n g t h e combinationofblue andorange
as i n t h i s embodiment of the invention enables people with a color
v i s i o n deficiency, which makes d i s t i n g u i s h i n g c e r t a i n colors
( t y p i c a l l y redandgreen) d i f f i c u l t , t o clearlydetermine whether the
i n d i c a t o r s are on or o f f .
The panel switch 8d is a paper feed switch, and protrudes
slightlyupwardwith a curved convex a r c shape or a c i r c u l a r truncated
cone shape, for example. Because the outside surface p a r t of the
protruding panel switch 8d d i f f u s e s l i g h t from an i n t e r n a l LED, the
switch can be seen from d i f f e r e n t d i r e c t i o n s .
The operating panel 8 i s t h e r e f o r e a u s e r - f r i e n d l y operating
panel from a universal design perspective.
[0052]
A s l i d e r button 9 for opening the back access cover case 5 i s
d i s p o s e d t o t h e p r i n t e r case 2 on t h e r i g h t side o f t h e recordingpaper
e x i t 6. Operating t h e s l i d e r button 9 releases a l o c k n o t shown, and
enables opening the back access cover case 5 as shown i n FIG. 2. When
the back access cover case 5 opens, the recording paper storage u n i t
11, which i s a storage unit f o r t h e recording paper r o l l 10, opens
t o the top and the recording paper r o l l 10 can be replaced, f o r
example.
When the f r o n t access cover case 4 opens, t h e c a s s e t t e loading
u n i t 13 ( s e e FIG. 3) where an ink ribbon c a s s e t t e 12 t h a t contains
an ink ribbon is removably i n s t a l l e d opens t o t h e top, and the ink
ribbon c a s s e t t e 12 can be replaced, for example.
[0053]
The i n t e r n a l configuration of t h e p r i n t e r 1 is d e s c r i b e d n e x t .
As shown i n FIG. 3, the recording paper storage u n i t 11 i s located
i n t h e r e a r portion o f t h e inside o f t h e p r i n t e r l . The recordingpaper
storage u n i t 11 has a curved bottom portion 1 4 t h a t opens t o the top
when seen from the s i d e of the p r i n t e r , and the recording paper r o l l
10 i s loaded sideways so t h a t it can r o l l on the t r a n s v e r s e axis X.
The recording paper 10a pulled from the recording paper r o l l 10 and
guided over a guide r o l l e r 15 disposed a t the f r o n t p a r t of the
recording paper storage u n i t 11 through the recording paper
conveyance path 16.
The recording paper conveyance path 1 6 has a conveyance path
portion 16a t h a t slopes s l i g h t l y upward toward the f r o n t on the
l o n g i t u d i n a l axis Y, a conveyance p a t h p o r t i o n 16b t h a t extends
curving up through a large angle from t h e f r o n t end of conveyance path
portion 16a, and a conveyance path portion 16c t h a t continues from
the top end of c o n v e y a n c e p a t h p o r t i o n 1 6 b t o t h e recordingpaper e x i t
6. In FIG. 3, the recording paper conveyance path 16 and the recording
paper 10a a r e both indicated by a s i n g l e dot-dash l i n e .
[0054]
The conveyance path portion 16a i s defined by a top conveyance
guide 17 and abottomconveyance guide 18. The conveyance path portion
1 6 b i s d e f i n e d b y a p l a t e n l g formedcontinuouslytothetop conveyance
guide 17, and the head surface 20a of a dot impact printhead 20 facing
the platen 19, and a p o s i t i o n between the platen 19 and the head
surface 20a i s the p r i n t i n g position of t h e recording paper 10a. The
printhead 20 i s disposed with the head surface 20a facing the back
and i n c l i n e d s l i g h t l y upward.
The printhead 20 i s mounted on a head carriage 21, and the head
carriage 21 c a n t r a v e l b i d i r e c t i o n a l l y on the transverse axis X along
a carriage guide r a i l 22.
[0055]
The c a s s e t t e loading u n i t 1 3 is l o c a t e d i n t h e top o f t h e p r i n t e r
above the head carriage 21. The ink ribbon (not shown i n t h e f i g u r e )
i n t h e i n k ribbon c a s s e t t e 12 loaded i n t h e c a s s e t t e loading u n i t 13
I i s s e t p a r a l l e l t o and between the head surface 20a of the printhead
I 20 and the platen 19 along the t r a n s v e r s e a x i s X. I
I
1
[0056]
A paper feed r o l l e r 23 and a pressure r o l l e r 24 t h a t i s pressed
I t o the paper feed r o l l e r 23 with the recording paper 10a therebetween I
1
is disposed t o the conveyance path portion 16c t h a t connects the ,
I
conveyance path portion 16b t o the recording paper e x i t 6. The
recording paper 10a is conveyed by the paper feed r o l l e r 23 through
the recording paper conveyance path 16.
[0057]
A scissor-type automatic c u t t e r u n i t 25 for c u t t i n g the
recording paper 10a widthwise is disposed t o the conveyance path
p o r t i o n 1 6 c n e a r t h e recordingpaper e x i t 6. The automatic c u t t e r u n i t
25 has a fixed knife and a movable knife on opposite s i d e s of the
conveyancepathportion16b, for example, a n d c u t s t h e recordingpaper
10a a t t h e p o s i t i o n between the knives. A c u t t e r 27 f o r manually
c u t t i n g the recording paper 10a i s also disposed t o the recording
paper e x i t 6 on t h e s i d e toward the f r o n t of the p r i n t e r .
[0058]
P r i n t e r frame
FIG. 4 is an oblique view of the p r i n t mechanism u n i t 30 t h a t
.is covered by the p r i n t e r case 2, FIG. 5 i s an oblique view of the
p r i n t mechanism u n i t 30 with the ink ribbon c a s s e t t e 12 removed, and
FIG. 6 i s an oblique view of t h e p r i n t mechanism u n i t 30 i n FIG. 5
without some p a r t s of the c a s s e t t e loading u n i t 13. FIG. 7 i s an
oblique view showing the p r i n t e r frame of t h e p r i n t mechanism u n i t .
[0059]
The p r i n t mechanism u n i t 30 i s composed of p r i n t e r components
assembled t o a p r i n t e r frame 31 made of sheet metal as shown i n FIG.
7. The configuration of the p r i n t e r frame 31 i s described primariLy
with reference t o FIG. 7.
The p r i n t e r frame 31includes a b a s e frame 32, and a p r i n t e r m a i n
frame 33 attached t o the base frame 32. The p r i n t e r main frame 33
comprises three frames, a f i r s t frame 34, a second frame 35, and a
t h i r d frame 36, t h a t are fastened together by screws or other
f a s t e n e r s .
[0060]
Thebase frame 3 2 i s a framewitha rectangular contour extending
on the transverse axis X and t h e l o n g i t u d i n a l a x i s Y, and includes
a rectangular base p l a t e 32a long on the l o n g i t u d i n a l axis Y, a f r o n t
panel 32b and a back panel 32c.that bend and extend down from the front
and back edges of the base plate '32a, and a l e f t panel 32d and a r i g h t
panel 32e that bend and extend down from the l e f t and r i g h t edges of
the base plate 32a.
[0061]
Theprintermain frame 33 comprisingthe f i r s t , second, and t h i r d
frames 34, 35, 36 i s attached t o the top of the base p l a t e 32a of the
base frame 32. The f i r s t frame 34 i s located a t the front on the
longitudinal axis Y. The carriage guide r a i l 22 (FIG. 4 t o FIG. 6 )
spansthe f i r s t frame 34 onthe transverse axisX. The cassette loading
unit 13 (FIG. 4 t o FIG. 6) i s disposed t o the f i r s t frame 34. The second
and t h i r d frames 35, 36 are disposed behind the f i r s t frame 34 on the
longitudinal axis Y . The recording paper storage u n i t 11 (FIG. 4 t o
FIG. 6) i s disposed between the second and t h i r d frames 35, 36. The
back end of the back access cover frame 5a (FIG. 4 t o FIG. 6 ) i s
attached to pivot v e r t i c a l l y a t the back end part of the second and
t h i r d frames 35, 36. The back access cover case 5 is attached t o the
back access cover frame 5a, thereby embodying the back access cover
(see FIG. 2 ) .
[0062]
The f i r s t frame 34 has a rectangular f i r s t frame bottom panel
34a. A f i r s t frame l e f t side panel 34b and a f i r s t frame r i g h t side
panel 34c are formed bending and extending perpendicularly up on the
v e r t i c a l axis Z from the l e f t and r i g h t edges of the transverse axis
X from the f i r s t frame bottompanel 34a. Rail holes 34d, 34e are formed
passing onthe transverse axis Xthroughthebackendpartofthe f i r s t
frame l e f t side panel 34b and f i r s t frame right side panel 34c. The
carriage guide r a i l 22 (FIG. 4 t o FIG. 6) passes between these r a i l
holes 34d, 34e. The f i r s t frame bottom panel 34a is disposed a t an
angle with the front end thereof r e s t i n g on the top of the base p l a t e
32a, and the back end r i s i n g from the base p l a t e 32a t o a s p e c i f i c
height.
[0063]
A l e f t leg panel 34f and a r i g h t l e g panel 34g are formed
extending down from the bottom edge part of the f i r s t frame l e f t side
panel34b andthe f i r s t frame rightsidepanel34cdirectlybelowwhere
the r a i l h o l e s 34d, 34e are formed s o t h a t the f i r s t framebottompanel
34a slopes. The bottom ends of the l e f t leg panel 34f and r i g h t leg
panel 34g are a l e f t fastening tab 34h and a r i g h t f a s t e n i n g tab 34i
that bend a t a right angle t o the inside on t h e t r a n s v e r s e axis X.
A screw hole i s formed i n the l e f t fastening tab 34h and the r i g h t
fasteningtab34i, andthe f i r s t frame 34 istherebyfastenedbyscrews
not shown t o the base p l a t e 32a. Note t h a t the f i r s t frame 34 can also
be fastened t o the base p l a t e 32a by screws a t places other than the
l e f t fastening tab 34h and right fastening tab 34i.
[00641
The second frame 35 i s located a t the back of the f i r s t frame
l e f t side panel 34b, and extends on the longitudinal axis Y upright
on the v e r t i c a l axis Z. Fastening tabs (not shown in the figure)
bending and extending perpendicularly t o the outside on the
transverse axis X are formed a t plural locations on the bottom end
of the second frame 35, and screw holes are formed i n these fastening
tabs. A fastening tab 35a i s formed bending and extending
perpendicularly to t h e i n s i d e on the transverse axis X from the front
end of the second frame 35, and plural screw holes, such as two in
t h i s example, are formed therein. A fastening tab 34j formed a t the
backend o f t h e f i r s t f r a m e l e f t s i d e p a n e l 3 4 b contacts the fastening
tab 35a from the back on the longitudinal axis Y. A screw hole i s also
formed in the fastening tab 34j. The f i r s t frame l e f t side panel 34b
and the second frame 35 are fastened together by fastening the
fastening tabs 35a, 34j with screws not shown. The fastening tab 35a
i s a second fastening u n i t t h a t i s fastened t o the f i r s t frame 34.
[0065]
The t h i r d frame 36 is located a t the back side of the f i r s t frame
right side panel 34c a specific distance inside of the first frame
right side panel 34c on the transverse axis X, and extending on the
longitudinal axis Ystandinguprightonthe vertical axis Z. Fastening
tabs 36a (first fasteningparts) that bend and extendperpendicularly
to the outside on the transverse axis X are formed at plural locations
along the bottom end of the third frame 36, and a screw hole is formed
in each fastening tab 36a. The fastening tabs 36a are fastened to the
base plate 32a using screws not shown. Another fastening tab 36b that
bends and extends perpendicularly to the outside on the transverse
axis X is also formed at the front bottom end part of the third frame
36. A screw hole (not shown in the figure) is formed in the distal
end part of the fastening tab 36b, and the fastening tab 36b is
fastened to the first frame right side panel 34c by a screw not shown.
[0066]
The printer main frame 33 is thus composed of plural frames 34
to 36. Increasing the manufacturing precision of each of the frames
34 to 36 is therefore simple compared with manufacturing the printer
main frame 33 by bending and shaping a single metal sheet. Complex
dies are also not needed to stamp the frame plates. The ease of
assembling printer components to the printer main frame 33 is also
improved.
[0067]
For example, installing the bottom portion 14, which is a
component of the recording paper storage unit 11, between the second
and third frames 35, 36 can be done without deforming the side panels
or deforming the assembled parts, and is therefore extremely simple
compared with installing the bottom portion 14 between the left and
right side panels of a printer main frame 33 made from a single metal
sheet.
100681
Furthermore, when installing the carriage guide rail 22, which
requires installation with high precision, to the printer main frame
33, the carriage guide rail 22 can simply be installed between the
first frame left side panel 34b and the first frame right side panel
34c of the single first frame 34. The first frame 34 can be
manufactured with better precision than a printer main frame 33 made
from a single piece. The rail holes 34d, 34e for installing the
carriage guide rail 22 can also be formed with good precision in the
first frame 34. The carriage guide rail 22 can therefore be assembled
to the printer main frame 33 with good precision.
[0069]
The first to third frames 34 to 36 are each fastened to the base
frame 32. The first frame 34 and the second frame 35 are also fastened
together, and the first frame 34 and the third frame 36 are fastened
together. The second frame 35 and the third frame 36 thus each have
first fastening parts that are fastened to the base frame 32, and
second fastening parts that are fastened to the first frame 34. The
overall strength and rigidity of a printer main frame 33 assembled
. from plural frames can therefore be increased.
[0070]
The first frame left side panel 34b and first frame right side
panel 34c of the first frame 34 are also fastened to the base frame
32 at a position directly below the rail holes 34d, 34e that are the
guide rail attachment parts, andare thusbase supportparts supported
by the base frame 32. As a result, if the printer 1 is accidentally
dropped, for example, a strong impact force will be applied from the
head carriage 21 side, which carries the heavy printhead 20, to the
part where the rail holes 34d, 34e are formed in the first frame 34
that supports the carriage guide rail 22. The impact force is borne
on the base frame 32 side through the first frame 34. The drop
resistance of the printer 1 can therefore be improved.
[0071]
Cassette loading unit
The cassette loading unit 13 in which the ink ribbon cassette
12 i s removably i n s t a l l e d and which is disposed t o the f i r s t frame
34 of the p r i n t e r frame 31 is described next with reference t o FIG.
3 t o FIG. 6.
[0072]
The head carriage 21 t h a t c a r r i e s the printhead 20 t r a v e l s
bidirectionallyonthetransverse a x i s x a l o n g t h e carriage guide r a i l
22. The space through which the printhead 20 and the head c a r r i a g e
2 1 move is enclosed by the f i r s t frame bottom panel 34a located below
t h e c a r r i a g e guide r a i l 22, and a ribbon frame 37, which i s a fourth
frame, above the carriage guide r a i l 22. As shown i n FIG. 4 and FIG.
5, the ribbon frame 37 includes a rectangular c e i l i n g panel 37a
extending on the transverse axis X, a rectangular f r o n t panel 37b
bending and extending perpendicularly down fromthe f r o n t edge o f t h e
c e i l i n g panel 37a, and a rectangular back panel 37c extending down
t o the back a t an angle l e s s than 90 degrees from the back edge of
the c e i l i n g panel 37a. Rectangular openings are also formed a t a
s p e c i f i c i n t e r v a l i n the ribbon frame 37.
[0073]
As shown i n FIG. 4 and FIG. 5, i d e n t i c a l l y shaped side members
37d are a l s o formed bending and extending perpendicularly down from
the l e f t and r i g h t ends of t h e c e i l i n g panel 37a. The side members
37d also have a side extension 37f t h a t extends f u r t h e r down from a
p o s i t i o n towards the back of the p r i n t e r .
[0074]
As w i l l be understood from FIG. 5, a loading u n i t base 38 i s
disposed extending on the transverse axis X between the f i r s t frame
l e f t side panel 34b and the f i r s t frame r i g h t side panel 34c of the
f i r s t frame 34 a t a p o s i t i o n i n f r o n t o f t h e ribbon frame 37. Thebottom
of the c a s s e t t e loading u n i t 13 i s defined by the loading u n i t base
38. As shown i n FIG. 6, the loading u n i t base 38 covers and hides the
components o f t h e ink ribbon conveyancemechanism, which i s i n s t a l l e d
t o the f i r s t frame bottom panel 34a of t h e f i r s t frame 34 below the
loading u n i t base 38.
[0075]
As showninFIG. 5, t h e i n k r i b b o n c a s s e t t e 1 2 has a r e c t a n g u l a r l y
shaped, f l a t ink ribbon storage u n i t 12a, a l e f t arm 12b, and a r i g h t
a r m 12c. An ink ribbon 12A i s housed i n the ink ribbon storage u n i t
12a. The l e f t arm 12b'and the r i g h t arm 12c extend the same d i s t a n c e
i n the d i r e c t i o n of t h e s h o r t sides from the opposite ends of the long
s i d e of t h e i n k ribbon storage u n i t 12a. The ink ribbon 12A is
recovered i n t o the ink ribbon storage u n i t 12a from the take-up
entrance 12d formed a t the base of the r i g h t arm 12c, and is pulled
out from the supply opening 12i formed a t the d i s t a l end p a r t of the
l e f t arm 12b. The portion of the ink ribbon 12A t h a t i s pulled out
is wound between the d i s t a l end of the l e f t arm 12b and the d i s t a l
end of the r i g h t arm 12c as indicated by the imaginary l i n e i n FIG.
5.
[0076]
Agrip12e extendingin the d i r e c t i o n o f t h e short side protrudes
v e r t i c a l l y from the top of the ink ribbon storage u n i t 12a a t the
middle of the long side. A knob 12f f o r rewinding the ink ribbon 12A
is disposed near the r i g h t end of the long side of the ink ribbon
storage u n i t 12a.
[0077]
A guide channel 12g and a snap f i t engaging p a r t 12h a r e formed
on the s h o r t s i d e s o f t h e l e f t and r i g h t ends o f t h e ink ribbon storage
u n i t 12a. The guide channel 12g i s formed i n t h e s i d e of the l e f t and
r i g h t short s i d e s of t h e i n k ribbon s t o r a g e u n i t 12a beside the
respective l e f t arm 12b and r i g h t arm 12c, and is a guide channel
extending with a s p e c i f i c width i n the thickness d i r e c t i o n of the ink
ribbon storage u n i t 12a. The snap f i t engaging p a r t 12h i s an
e l a s t i c a l l y deformable p a r t disposed i n the l e f t and r i g h t s i d e s of
t h e ink ribbon storage u n i t 12a beside the guide channel 12g.
[0078]
As will be understood from F I G . 5, the loading unit base 38 that
defines the bottom of the cassette loading unit 13 has identically
shaped side members 38b formedbending and extending perpendicularly
up from the opposite ends of the transverse axis X (only the side
member 38b on the left side is shown in F I G . 5). A guide tab 38c and
a snap fit engaging tab 38d are formed on each side member 38b. The
top ends of the guide tabs 38c slope and widen to the outside on the
transverse axis X. The snap fit engaging tabs 38d are protrusions of
a constant width that protrude slightly to the inside on the
transverse axis X.
[0079]
The size of the loading unit base 38 that defines the bottom of
the cassette loading unit13 is large enoughto install the ink ribbon
storage unit 12a of the ink ribbon cassette 12. A space enabling
inserting the left arm 12b of the ink ribbon cassette 12 from above
is formed between the first frame left side panel 34b of the first
frame 34 and the side member 37d on the left side of the ribbon frame
37 opposing the first frame left side panel 34b from the inside. A
space enabling inserting the right arm 12c of the ink ribbon cassette
12 from above is likewise formed between the first frame right side
panel 34c of the first frame 34 and the side member 37d on the right
side of the ribbon frame 37.
[0080]
As shown in F I G . 5, the ink ribbon cassette 12 can be installed
to the cassette loading unit 13 from above the cassette loading unit
13. To install, the left arm 12b and right arm 12c of the ink ribbon
cassette 12 are pushed in along the outside surfaces of the side
members 37d of the ribbon frame 37, and the ink ribbon storage unit
12a of the ink ribbon cassette 12 is then positioned so that the guide
tabs 38c on the opposite sides of the loading unit base 38 enter the
matching guide channels 12g of the ink ribbon cassette 12 and pushed
toward the loading unit base 38.
[0081]
The ink ribbon cassette 12 is guided in the installation
directionby the sidemembers 37dofthe ribbon frame 37 on the printer
1 side and the guide tabs 38c on the opposite sides of the loading
unit base 38, and installed to the cassette loading unit 13. When the
ink ribbon cassette 12 is pushed into the installation position, the
snap fit engaging parts 12h on the opposite sides of the ink ribbon
storage unit 12a engage the snap fit engaging tabs 38d on the loading
unit base 38 side. As a result, as shown in FIG. 4, the ink ribbon
cassette 12 is installed to the cassette loading unit 13.
[0082]
The ink ribbon cassette 12 is held installed to the cassette
loading unit13 bya specific engaging force. To remove the ink ribbon
cassette 12 from the cassette loading unit 13, the user holds the grip
12e and lifts the ink ribbon cassette 12 up. As a result, the snap
fit engaging parts 12h disengage the snap fit engaging tabs 38d on
the cassette loading unit 13 side, and the ink ribbon cassette 12 can
be removed from the cassette loading unit 13.
[0083]
The ink ribbon cassette 12 can be installed to the cassette
loading unit13 bypushingtheinkribbon cassette 12 into the cassette
loading unit 13, and can be removed from the cassette loading unit
13bypullingitoutinthe oppositedirection. The ink ribbon cassette
12 can therefore be easily installed and removed.
[0084]
As will also be understood from FIG. 4, when the ink ribbon
cassette 12 is installed to the cassette loading unit 13, the side
extensions 37f of the side members 37d on the opposite sides of the
ribbon frame 37 contact the left arm 12b and right arm 12c of the ink
ribbon cassette 12 from the inside. The left arm 12b and right arm
12c are supported by the side extensions 37f. Because the left and
right arms 12b, 12c are thus supported by the side extensions 37f,
- 29 -
the arms w i l l not be damaged even i f excess force i s applied thereto
when i n s t a l l i n g or removing the ink ribbon cassette 1 2 .
[00851
A side member 37d i s also disposed t o both sides of the ribbon
frame 37 in t h i s example. As shown in FIG. 4, the side members 37d
of the ribbon frame 37 t h a t covers the t r a v e l space of the head
carriage 21 carrying the printhead 20, and the l e f t arm 12b and r i g h t
arm 12c of the i n s t a l l e d ink ribbon cassette 12, cover and hide the
openings on both sides of t h i s t r a v e l space on the transverse axis
X. More s p e c i f i c a l l y , the side members 37d function a s guides of the
ink ribbon cassette 12 and supports f o r t h e l e f t and right arms 12br
12cr and function as shields closing the side openings of the t r a v e l
space.
[0086]
The printhead 20, which is a dot impact head in t h i s p r i n t e r 1,
gets hot during the printing operation. The operator could therefore
get burned by accidentally touching the hot printhead 20. Such
accidents can be r e l i a b l y prevented, however, because the ribbon
frame 37 encloses the printhead 20 so t h a t the printhead 20 cannot
be touched by the user.
100871
Foreign object shield panel
The foreign object shield panel attached t o the f i r s t frame 34
i s described next with reference t o FIG. 3 and FIG. 6. As shown i n
FIG. 3 and FIG. 6, a foreign object shield panel 39 extends between
the f i r s t frame l e f t side panel 34b and the f i r s t frame right side
panel 34c of the f i r s t frame 34. This foreign object shield panel 39
i s basically rectangular, and extends on the transverse axis X along
the carriage guide rail22betweenthe recordingpaper conveyancepath
1 6 and t h e c a r r i a g e guide r a i l 22.
LO0881
The foreign object s h i e l d p a n e l 3 9 i s disposedneartheback edge
of the first frame bottom panel 34a of the first frame 34, and extends
on the transverse axisX standinguprightperpendicularlytothe first
frame bottom panel 34a. As will be understood from FIG. 3, the width
of the foreign object shield panel 39 covers the distance from a
position at an elevation below the carriage guide rail 22 on the
vertical axis Z to a position at an elevation near the print position
of the printhead 20.
[0089]
A slot 21a of a specific width extending on the transverse axis
X is formed in the head carriage 21 at a position on the recording
paper conveyance path 16 side. The slot 21a in the head carriage 21
is openat both ends on the transverse axisxandis open tothe bottom.
The top part 39a of the foreign object shield panel 39 is inserted
from below to the slot 21a. The head carriage 21 travels
bidirectionally along the carriage guide rail 22 with the top part
39a of the foreign object shield panel 39 inserted to the slot 21a.
[0090]
Paper chaff and other foreign matter falling or dispersed from
the recording paper 10a conveyed toward the print position through
the recording paper conveyance path 16 is prevented by the foreign
object shield panel 39 from entering to the carriage guide rail 22
side. A detector 40 for detecting the current position of the head
carriage 21 is also disposed near the carriage guide rail 22. As shown
in FIG. 6, the detector 40 is a home position sensor that detects if
the head carriage 21 is at the home position set at the left end on
the transverse axis X in this example. The detector 40 is a
transmissive photosensor, for example. Paper chaff or other foreign
matter can also be prevented by the foreign object shield panel 39
from penetrating to the detector 40 side and sticking to the detector
40.
[0091]
If foreign matter sticks to the carriage guide rail 22, the
foreignmattermay accumulatebetween the s l i d i n g p a r t o f t h e carriage
guide r a i l 22 and the head carriage 21, and increase the load of the
carriage motor (not shown i n the figure) t h a t moves the head carriage
21. If foreignmatter s t i c k s t o t h e d e t e c t o r 40 near the carriage guide
r a i l 22, detection errors may a l s o r e s u l t . In t h i s embodiment of the
invention, the recording paper conveyance path 16, which i s where
paper chaff and such foreign matter can occur, i s separated from the
carriage guide r a i l 2 2 andthe detector 4Obythe foreign object shield
panel 39. The resulting foreign matter can therefore be prevented or
suppressed f r o m p e n e t r a t i n g t o t h e sliding part o f t h e carriage guide
r a i l 22 and the head carriage 2 1 or the detection surface of the
detector 40, and problems such as an increased load on t h e c a r r i a g e
motorordete'ctionerrorsbythe detector 40 due t o such foreignmatter
can be avoided.
[0092]
In t h i s example the top p a r t of the foreign object shield panel
39 i s inserted t o the s l o t 21a formed in the head carriage 21. This
creates a convoluted path t h a t foreign matter originating from the
recording paper conveyance path 16 side must t r a v e l t o reach the area
of the carriage guide r a i l 22 or detector 40. Paper chaff o r o t h e r
foreign matter can thus be r e l i a b l y prevented or suppressed from
passing t o the carriage guide r a i l 22 or detector 40 side.
[0093]
Fastening mechanism for the platen gap adjustment mechanism
FIG. 8 ( a ) i s an oblique view of part of the fastening mechanism
f o r securing the platen gap adjustment mechanism of the p r i n t e r 1 in
the adjustment position, and FIG. 8 (b) i s a p a r t i a l section view
thereof.
[0094] .
The p r i n t e r 1 has a gap adjustment mechanism f o r adjusting the
gap (see FIG. 3) between the head surface 20a of the printhead 20 and
t h e opposing platen 19. The gap adjustment mechanism in t h i s
embodiment of the invention can move the printhead 20 c a r r i e d by the
head c a r r i a g e 21 s l i d a b l y attached t o the c a r r i a g e guide r a i l 22 i n
the d i r e c t i o n toward and the d i r e c t i o n away from the p l a t e n 19, and
thereby a d j u s t t h e gap therebetween, by e c c e n t r i c a l l y r o t a t i n g t h e
c a r r i a g e guide r a i l 22. Because the l e f t and r i g h t gap adjustment
mechanisms are i d e n t i c a l l y configured, the gap adjustment mechanism
on t h e r i g h t side i s described below and d e s c r i p t i o n of t h e other is
omitted.
[0095]
As shown i n FIG. 8, the gap adjustment mechanism 50 has an
e c c e n t r i c s h a f t p a r t 5 1 t h a t i s round i n section formedwith a s p e c i f i c
e c c e n t r i c i t y on the end of the c a r r i a g e guide r a i l 22. The e c c e n t r i c
s h a f t p a r t 51 passes through t o the outside on t h e t r a n s v e r s e a x i s
X from t h e r a i l hole 34e i n the f i r s t frame r i g h t s i d e panel 34c of
the f i r s t frame 34. The portion of the e c c e n t r i c s h a f t p a r t 51
protruding t o the o u t s i d e from t h e r a i l hole 34e i s press f i t i n a
bearing hole 52a of an adjustment r o l l e r 52, which i s the adjustment
member f o r gap adjustment.
[0096]
An arm52bis formedextending r a d i a l l y t o t h e adjustment r o l l e r
52. A l a t c h p a r t 52c i s formed t o t h e d i s t a l end p a r t of the arm 52b.
Multiple l a t c h channels 53 are formed i n the o u t s i d e surface of the
f i r s t frame r i g h t s i d e panel 34c a t a s p e c i f i c angular i n t e r v a l
through a s p e c i f i c angular range along the movement path of the l a t c h
p a r t 52c. The l a t c h p a r t 52c of t h e arm 52b of t h e adjustment r o l l e r
52 i s f i t with a s p e c i f i c pressure i n t o one of t h e l a t c h channels 53.
The adjustment r o l l e r . 52 is held a t a s p e c i f i c angular p o s i t i o n by
a f i r s t f a s t e n i n g p a r t i n c l u d i n g t h e l a t c h p a r t 5 2 ~a n d l a t c h channels
53.
[0097]
A second fastening p a r t f o r holding the adjustment r o l l e r 52 a t
a s p e c i f i c angular p o s i t i o n is a l s o d i s p o s e d t o t h e adjustment r o l l e r
52. The second fastening part includes a curved channel 54 of a
specific width formed through a specific angular range centered on
the eccentric shaft part 51, a set screw 55 that can slide along the
curved channel 54, and a screw hole 56 into which the set screw 55
can be screwed.
[0098]
The curved channel 54 is formed in an extension plate 52d
integrally formed to the outside circumference of the adjustment
roller 52 a position not interfering with the arm 52b. The screw hole
56 is formed in the first frame right side panel 34c at a position
opposite the curved channel 54. The set screw 55 screws into the screw
hole 56throughthe curvedchannel54 and thereby fixesthe adjustment
roller 52 to the first frame right side panel 34c.
[0099]
The gap can be adjusted with the gap adjustment mechanism thus
comprised by compelling the adjustment roller 52 to turn with the set
screw 55 loosened. When the desired gap is set, the latch part 52c
of the adjustment roller 52 fits into the latch channel 53, and the
adjustment roller 52 is held at the adjusted angular position. By
tightening the set screw 55 after the gap is adjusted, the adjustment
roller 52 is reliably held at the adjusted angular position.
[OlOO]
When the printhead 20 is heavy, such as when a dot impact head
with many wires is used, the engaging force of the latch part 52c and
the latch channels 53 alone may not be able to hold the carriage guide
rail 22 at the set angular position. Because many wires are driven
when printing with the printhead 20, a strong impact force is applied
from the printhead 20 through the head carriage 21 and the carriage
I
guide rail 22 to where the latch part 52c and the latch channels 53
are engaged. If the latch part 52c leaves the latch channels 53 due
to this impact force, the adjustment roller 52 may turn, the carriage
guide rail 22 rotate eccentrically, and the gap change.
[ OlOl]
This embodiment of the invention uses a first fastening part
comprising the latch part 52c and the latch channels 53, and a second
fastening part using the set screw 55, as the mechanism for fixing
the position of the adjustment roller 52. Problems such as the
adjustment roller 52 turning and the gap changing can therefore be
reliably prevented. The gap can also be easily adjusted when the set
screw 55 is loosened because the adjustment roller 52 is then held
only by the latch-type first fastening part.
[0102]
Printhead grounding path
FIG. 9 (a) is an oblique view showing the area around the ground
path of the printhead 20, and FIG. 9 (b) is a side view of the same.
The printhead 20 is mounted on a head carriage 21 and travels
bidirectionally along the carriage guide rail 22 in a serial printer
1. Themovingprinthead 20 andthe stationary controlboard (not shown
in the figure) that carries circuits including the printhead driver
that controls driving the printhead 20 are electrically connected
through a flexible printed circuit (not shown in the figure).
[0103]
When the number of wires, which are head elements of the
printhead 20, increases, the number of lines needed to drive the many
wires also increases. A ground line for grounding the printhead 20
is usually included in the flexible printed circuit. When the number
of lines for driving the printhead increases, there may not be
sufficient space to provide a ground line in the flexible printed
circuit. In this example, the printhead 20 is grounded to the printer
frame 31 using the carriage guide rail 22, which is electrically
conductive, in the ground line.
[0104]
As shown in FIG. 6 and FIG. 9 (a), a ground terminal plate 41
made from a conductive material is disposed to the head carriage 21.
The ground terminal p l a t e 4 1 contacts the conductive head case 20br
which i s the ground terminal part of the printhead 20. The ground
terminal plate 4 1 i s pressed against the outside surface of the
carriage guide r a i l 2 2 , s l i d e s along the outside o f t h e carriage guide
r a i l 22 i n conjunction with movement of the head carriage 21, and
e l e c t r i c a l contact is continuously maintained.
[0105]
As shown i n FIG. 9 ( b ) , a conductive guide r a i l ground p l a t e 42
t h a t e l e c t r i c a l l y connects t h e c a r r i a g e guide r a i l 22 t o the f i r s t
frame 34 i s disposed t o the f i r s t frame right side panel 34c of the
f i r s t frame 34 of the p r i n t e r frame 31. The guide r a i l ground p l a t e
42 includes a frame attachment part 42a, and a guide r a i l contact part
42bthatbends perpendicularly fromthe frame attachment part 42a and
then again bends perpendicularly and extends p a r a l l e l t o the frame
attachment part 42a.
[0106]
The frame attachment part 42a of the guide r a i l ground p l a t e 42
i s fastened by a s e t screw 43 t o the outside of the f i r s t frame right
s i d e p a n e l 3 4 c . A ~d escribedabove, the r i g h t a x i a l e n d o f t h e carriage
guide r a i l 22 i s t h e e c c e n t r i c shaft part 51, and the eccentric shaft
part 51 protrudes a s p e c i f i c amount t o the outside from the r a i l hole
34e i n the f i r s t frame r i g h t s i d e panel 34c. The adjustment r o l l e r
52 for gap adjustment i s press f i t t o the eccentric shaft part 51.
The eccentric shaft p a r t 51protrudes a specific amount t o t h e outside
from the bearing hole 52a in the center of the adjustment r o l l e r 52,
and the d i s t a l end surface of the guide r a i l contact part 42b of the
guide r a i l groundplate 42 c o n t a c t s t h e a x i a l end 51a o f t h e eccentric
shaft p a r t 51 with a specific pressure.
[0107]
The ground l i n e for grounding the printhead 20 t o the p r i n t e r
frame 31 i s thus formed by the ground terminal p l a t e 41, the carriage
guide r a i l 22, and the guide r a i l ground plate 42. There i s therefore
no need t o provide a ground l i n e i n the f l e x i b l e p r i n t e d c i r c u i t (not
shown i n t h e figure) t h a t connects t h e moving printhead 20 t o the
s t a t i o n a r y p r i n t e r c o n t r o l board (not shown i n the f i g u r e ) .
[0108]
The guide r a i l ground p l a t e 42 a l s o pushes with a s p e c i f i c
pressure a g a i n s t t h e c a r r i a g e guide r a i l 22 i n the a x i a l d i r e c t i o n .
Play i n t h e a x i a l d i r e c t i o n o f t h e c a r r i a g e guide r a i l 2 2 is prevented
or suppressed by t h i s pressure from t h e guide r a i l ground p l a t e 42.
[0109]
More s p e c i f i c a l l y , when the head c a r r i a g e 21 carrying t h e
printhead 20 moves back and f o r t h along t h e carriage guide r a i l 22,
a small amount of play may be produced i n the a x i a l d i r e c t i o n a t the
p a r t s of t h e carriage guide r a i l 22 supported by the f i r s t frame 34,
which i n t h i s embodiment of the invention are the adjustment r o l l e r s
52 press f i t t o each end, by the s l i d i n g load of the head c a r r i a g e
21. When play develops i n the carriage guide r a i l 22 i n the a x i a l
d i r e c t i o n , c h a t t e r can a l s o occur i n the a x i a l d i r e c t i o n i n the
carriage guide r a i l 22 i n conjunction with the head c a r r i a g e 21
s l i d i n g . Due t o t h i s c h a t t e r i n the a x i a l d i r e c t i o n of t h e c a r r i a g e
guide r a i l 22, s h i f t i n g may occur i n t h e p r i n t p o s i t i o n of t h e
printhead 20 whenthe head c a r r i a g e 2 1 t r a v e l s on the outbound s t r o k e ,
and the p r i n t position of t h e printhead 20 on t h e r e t u r n s t r o k e . Such
problems can be avoided i n t h i s example using the p r e s s u r e a p p l i e d
by the guide r a i l ground p l a t e 42.
[0110]
Other embodiments
The p r i n t e r 1 i n t h i s example has a dot impact head as the
printhead 20. The invention i s not so l i m i t e d , however, and can a l s o
be applied t o p r i n t e r s u s i n g a thermal head or an i n k j e t head, f o r
example, a s the printhead 20.
Althoughthe present invention has been d e s c r i b e d i n connection
with the p r e f e r r e d embodiments thereof with reference t o the
accompanying drawings, it is t o be noted t h a t various changes and
modifkcations w i l l be apparent t o t h o s e . s k i l l e d i n the a r t . Such
changes andmodifications are t o b e understood as i n c l u d e d w i t h i n t h e
scope of the present invention as defined'by t h e appended claims,
unless they depart therefrom.

WE CLAIMS:-
1. A printer comprising:
a printer frame to which printer components are disposed;
wherein the printer frame includes a base frame and a printer
main frame attached to the base frame;
theprinter main frame includes at least first, second, and third
frames;
a carriage guide rail that guides a head carriage carrying a
printhead spans the first frame; and
a recording paper storage unit that holds recording paper is
disposed between the second frame and the third frame.
2. The printer described in claim 1, wherein:
the second frame and the third frame each have a first fastening
part fastened to the base frame, and a second fastening part fastened
to the first frame.
8 .
3. The printer described in claim 1, wherein:
a guide rail attachment part of the first frame to which the
carriage guide rail is attached has a base support part supported by
the base frame.
4. The printer described in claim 1, wherein:
when the head carriage moves widthwise to the printer on a
transverse axis, the base frame is a frame with a rectangular contour
extending on the transverse axis and a longitudinal axis
perpendicular to the transverse axis;
the first, second, and third frames are disposed to the top of
the base frame on the vertical axis;
the second and third frames are disposed to back of the first
frame on the longitudinal axis;
the first frame includes a first frame bottom portion extending
on the transverse axis and the longitudinal axis, a f i r s t frame l e f t
side portion bending and extending up on the v e r t i c a l axis from the
l e f t edge p a r t . o f the f i r s t frame bottom portion on the transverse
a x i s , and a f i r s t frame r i g h t side portion bending and extending up ,
on t h e v e r t i c a l axis fromthe r i g h t edge p a r t o f t h e f i r s t framebottom
portion on the t r a n s v e r s e a x i s ;
the opposite a x i a l end p a r t s of the carriage guide r a i l are
r e s p e c t i v e l y disposed between the f i r s t frame l e f t side portion and
the f i r s t frame r i g h t side portion;
t h e second frame is a frame extending t o the back on the
l o n g i t u d i n a l axis a t a position behind the f i r s t frame l e f t side
portion on t h e l o n g i t u d i n a l a x i s ; and
t h e t h i r d frame i s a frame extending t o the back on the
l o n g i t u d i n a l axis a t a position behind the f i r s t frame r i g h t side
portion on t h e l o n g i t u d i n a l a x i s .
5. The p r i n t e r described i n claim 1, f u r t h e r comprising:
a recording paper conveyance path extending f r o m t h e recording
paper storage u n i t p a s t the p r i n t p o s i t i o n of the printhead; and
a foreign object s h i e l d panel disposed between the recording
paper conveyance path and t h e c a r r i a g e guide r a i l , and extending i n
a f i r s t d i r e c t i o n , which i s the d i r e c t i o n along t h e c a r r i a g e guide
r a i l .
6. The p r i n t e r described i n claim 5, f u r t h e r comprising:
a detector t h a t d e t e c t s the c u r r e n t p o s i t i o n of the head
c a r r i a g e ;
t h e foreign o b j e c t s h i e l d panel being disposed between the
recording paper conveyance path and the d e t e c t o r .
7. The p r i n t e r described i n claim 5, wherein:
the head c a r r i a g e has a s l o t extending i n the f i r s t d i r e c t i o n
a t a p o s i t i o n between the recording paper conveyance path and the
carriage guide r a i l ; and
the foreign object s h i e l d p a n e l being a p a n e l o f a s p e c i f i c width
extending i n the f i r s t d i r e c t i o n with p a r t of the f o r e i g n o b j e c t
shield panel i n s e r t e d t o the s l o t .
8. The p r i n t e r described i n claim 5, wherein:
the foreign object s h i e l d panel is attached t o the f i r s t frame.
9. The p r i n t e r described i n claim 1, f u r t h e r comprising:
a conductive head ground member attached t o the head carriage
and contacting both a ground terminal p a r t of the printhead and the
conductive carriage guide r a i l ; and
a conductive guide r a i l ground member grounding the c a r r i a g e
guide r a i l t o the f i r s t frame.
1 0 . The p r i n t e r described i n claim 9, wherein:
the guide r a i l groundmember has a frame fastening p a r t fastened
t o the f i r s t frame, and a guide r a i l pressure p a r t pushing against
one a x i a l end face of the carriage guide r a i l .
11. The p r i n t e r described i n claim 1, f u r t h e r comprising:
an e c c e n t r i c s h a f t p a r t disposed t o the a x i a l end p a r t of the
carriage guide r a i l ;
an adjustment member fastened t o t h e e c c e n t r i c s h a f t p a r t and
e c c e n t r i c a l l y r o t a t i n g the carriage guide r a i l through a s p e c i f i c
angular range around t h e center of the e c c e n t r i c s h a f t p a r t ; and
a f i r s t fastening p a r t and a second fastening p a r t t h a t f i x the
adjustment member t o a s p e c i f i c angular p o s i t i o n around t h e c e n t e r
of t h e e c c e n t r i c s h a f t p a r t .
1 2 . The p r i n t e r described i n claim 11, wherein:
the second fastening p a r t has a curved channel of a s p e c i f i c
width formed through a s p e c i f i c angular range centered on the
e c c e n t r i c s h a f t p a r t , a s e t screw t h a t can s l i d e through the curved
channel, and a screw hole i n t o which the s e t screw can be screwed;
the curved channel i s formed i n the adjustment member;
the screwhole i s formedinthe f i r s t frame a t a p o s i t i o n o p p o s i n g
t h e curved channel; and
the s e t screw f i x e s t h e adjustment member t o the f i r s t frame by
screwing i n t o t h e screw hole through the curved channel.
13. The p r i n t e r described i n claim 1, fur'cher comprising:
a fourth frame attached t o the f i r s t frame;
a t r a v e l space formed between the f i r s t frame and t h e f o u r t h
frame t o enablemovement o f t h e headcarriage along the c a r r i a g e guide
r a i l ;
one end of the t r a v e l space i n the d i r e c t i o n along the c a r r i a g e
guide r a i l being a f i r s t opening, and the other end being a second
opening; and
a f i r s t cover p l a t e t h a t covers a t l e a s t p a r t o f t h e f i r s t opening,
and a second cover p l a t e t h a t covers a t l e a s t p a r t of the second
opening, being disposed t o t h e . f o u r t h frame.
1 4 . The p r i n t e r described i n claim 13, f u r t h e r comprising:
a c a s s e t t e loading u n i t t o which is i n s t a l l e d an ink ribbon
c a s s e t t e s t o r i n g an ink ribbon from which ink i s t r a n s f e r r e d t o
recording paper by the printhead i s disposedbetweenthe p a r t s o f t h e
f i r s t frame spanned by the c a r r i a g e , g u i d e r a i l ; and
the f i r s t and secondcover p l a t e s g u i d i n g t h e i n k r i b b o n c a s s e t t e
being i n s t a l l e d t o t h e c a s s e t t e loading u n i t t o the c a s s e t t e loading
u n i t , and supporting the ink ribbon delivery side portion and the ink
ribbon recovery side portion of the ink ribbon c a s s e t t e i n s t a l l e d t o
t h e c a s s e t t e loading u n i t .
15. The printer described in claim 13, wherein:
the first and second cover plates are formed by bending the
opposite ends of the fourth frame in the direction along the carriage
guide rail.
16. The printer described in claim 1, further comprising:
a cassette' loading unit to which an ink ribbon cassette storing
an inkribbonis installedbetween theparts ofthe first frame spanned
by the carriage guide rail;
first and second cassette guides disposed to the opposite ends
of the cassette loading unit in a direction along the carriage guide
rail, and guiding the ink ribbon cassette to the cassette loading
unit; and
first and second engaging parts disposed to the opposite ends
of the cassette loading unit in a direction along the carriage guide
rail, and engaging the ink ribbon cassette guided by the first and
second cassette guides and installed to the cassette loading unit;
the first and second engaging parts, and first and second
cassette-side engaging parts formed on the ink ribbon cassette to
engage the first and second engaging parts, being a snap fit engaging
construction.
17. The printer described in claim 1, wherein:
the printhead is a dot impact printhead.