Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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PRINTING APPARATUS
Technical Field
The present invention relates generally to printers
and, in particular, to a compact, clam shell style
printer that is easily loaded and includes a construction
that minimizes the cabling required between a printhead,
control switches and connectors, and the associated
circuit board.
Printers of the type to which this invention
pertains have many applications and uses. They may be
used as part of a point-of-sale terminal to print
receipts, etc. Printers of this type may also be used to
generate labels on which alphanumeric characters or
symbology, i.e., barcodes are printed.
These types of printers often utilize thermal print
technology to print indicia on print medium. Thermal
printing involves a thermal printhead which uses heating
elements to produce localized heating on thermal reactive
print media to produce indicia on the print media. In
order to effect the printing process, the print medium
must be clamped between a platen and the thermal
printhead. The printhead is normally spring biased
towards the print roller in order to provide the required
clamping force.
Disclosure of Invention
The present invention provides a new and improved
printer apparatus in which the loading of print media is
greatly facilitated and, in which modular construction is
used in order to substantially reduce the number of parts
normally needed for this type of printer.
According to the invention, the printing apparatus
includes a base and an associated cover for enclosing an
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interior region of the apparatus. The cover is movable
between opened and closed positions. When the cover is
closed, the printing apparatus defines a print media path
that extends from the interior region to a discharge
opening. The platen roller is rotatably supported by the
cover, such that when the cover is moved to its opened
position, the platen roller is spaced from the print
media path. A substantially fixed printhead is supported
by the base and is engageable by the platen roller when
the cover is in its closed position. A biasing
arrangement urges the platen roller towards the printhead
when the cover is in its closed position.
According to a feature of this embodiment, a cutter
mechanism forms part of the printing apparatus~and has
one portion carried by the cover and another portion
carried by the base, such that when the cover is moved to
its opened position, the one portion of the cutter
mechanism moves to a spaced location along with the
platen roller to facilitate the loading of print media
into the printing apparatus.
According to the preferred and illustrated
embodiment of the invention, the printing apparatus also
includes a thermal printhead which together with
associated control components and electronics forms a
printhead and control module that is mounted within the
printing apparatus. The control module preferably
comprises a circuit board assembly to which the thermal
printhead is secured and is fixed relative to the base.
According to this feature of the invention, the
circuit board assembly also mounts one or more switches
which provide a cover position detector function, as well
as a print media advancement function. According to a
further feature of this aspect of the invention, the
circuit board assembly also mounts connectors by which
the printer is interfaced to other equipment.
In the preferred and illustrated embodiment, the
printer incorporates a clam shell design in which a
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pivotally mounted cover mounts a spring biased platen
roller. When the cover is opened, a print media
compartment is exposed, as well as the complete media
feed path. Print media is installed in the printer by
placing the print media supply in a compartment defined
within the printer and then pulling the lead end of the
print media so that it extends beyond an ejection point
in the printing apparatus. Closing the cover causes the
platen roller to re-engage the printhead thus clamping
the print media between itself and the printhead.
In the illustrated embodiment, the printer includes
a cutter in which a portion is carried by the cover and
another portion is mounted in the base. With this
construction, opening the cover also separates the cutter
elements so that print media need not be fed through a
cutter mechanism when the print media is loaded. In the
illustrated embodiment, the one cutter portion comprises
a fixed blade that is attached to and is movable with the
cover. The other portion of the cutter includes a
reciprocally movable blade and is located in the base
unit. In the preferred embodiment, one of the cutter
portions is resiliently biased to the other portion when
the cover is closed. This biasing urges the cutter
portions into an aligned relationship to promote uniform
blade contact in order to improve cutter performance.
The disclosed printer is compact and is easily
manufactured. Cabling normally required between the
printhead, the control switches, the connectors and the
associated circuit board, is eliminated or at least
substantially reduced. In addition, the susceptibility
of damage to the electronics of the printer due to
electrostatic discharge is substantially reduced since
the electronic control module assembly is located
entirely within the printer and except for the interface
connectors is not accessible from outside the printer.
Additional features of the invention will become
apparent and a fuller understanding obtained by reading
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the following detailed description made in connection
with the accompanying drawings.
Brief Description of Drawin~~
Figure 1 is a perspective view of a printer
apparatus constructed in accordance with the preferred
embodiment of the invention;
Figure lA is an exploded view of the printer shown
in Figure 2, showing separation of removable covers from
a base portion of the printer;
Figure 2 is a side cross-sectional view of the
printer;
Figure 3 is another side cross-sectional view of the
printer;
Figures 4-6 show three different views of a control
module assembly forming part of the printer;
Figure 7 is a perspective view of an intermediate or
internal housing member forming part of the present
invention;
Figure 7A is a fragmentary, perspective view of the
internal housing member shown in Figure 7 showing a media
feed switch mechanism;
Figure 8 is a perspective view of a removable cover
forming part of the printer;
Figure 9 is a fragmentary, perspective view of the
printer cover shown in Figure 8;
Figure 9A is an exploded view of the printer cover
shown in Figure 9;
Figure 10 is a side view of an internal housing
member forming part of the printer;
Figure 10A is a fragmentary side view showing a
cover unlatching mechanism;
Figure 11A and i1B are fragmentary side views
showing a cover open detector switch arrangement
constructed in accordance with a preferred embodiment of
the invention;
Figure 12 is a fragmentary side view, partially in
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section showing an alternate cover latching mechanism of
the present invention;
Figure 13 is a perspective view of an alternate
printer cover;
5 Figure 14 is a perspective view of a cutter
mechanism forming part of the present invention; and,
Figure 14A schematically illustrates an alternate
embodiment of a cutter mechanism.
RP~t M2de for Carryins Out the Invention
Figure 1 illustrates the overall construction of a
printing apparatus embodying the present invention. In
the illustrated embodiment, the printing apparatus
comprises a clam shell-type printer. The printer
includes a base 10, a hinged cover 12 which, when opened,
provides access to a paper supply compartment 13 (shown
in Figure lA), and a fixed, but removable cover l4 that
encloses a printhead assembly and an optional cutter 15
(shown best in Figures 1A and 2. A feed button 16 is
actuatable by a user and is operative to advance print
media out of an ejection slot indicated generally by the
reference character 18. A cover release button 20 is
provided for releasing a latch mechanism that maintains
the cover 12 in its closed position as illustrated in
Figure 1.
Referring also to Figure 2, connectors to be
described and indicated generally by the reference
character 22 are provided by which the printer is
connected to power and a host system such as a cash
drawer of a point of sale terminal (not shown). In the
illustrated embodiment, the connectors 22 are accessible
. underneath the printer by means of a recess 24 formed in
the base 10 of the printer.
Referring also to Figure 3, the cover 12 is
rotatable between opened and closed positions about a
pivot axis 28. The opened position is shown in phantom
and is indicated by the reference character 26. In the
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preferred embodiment, the cover is separable from the
rest of the printer after it is moved to the opened
position. Referring also to Figure 8, this feature is
facilitated by a pair of J-shaped hinge members 30, which
are engageable with slots 32 formed in the base 10 (shown
in Figure 1A.
According to the invention, the cover mounts a
spring biased platen roller 40 (see Figure lA and 9A)
which is operably engageable with a thermal printhead 50
mounted at a fixed position within the base 10 of the
printer. As is conventional, print media (such as paper)
52 (Figure 2) is fed past the printhead 50 by rotation of
the platen roller 40. Heating elements forming part of
the printhead are selectively energized to produce
indicia, i.e., alphanumeric characters, symbology,
barcodes, etc, on the print media 52. Unlike prior
printers of this type, the thermal printhead 50 itself is
not moveably biased towards the platen roller 40. As is
known, in order for the thermal printing process to
perform properly, the print medium must be clamped
tightly between the platen roller 40 and the printhead
50, as the print medium moves past the printhead. In the
device of the present invention, the platen roller 40,
not the printhead 50, is spring biased in order to
produced the required clamping force.
Referring to Figures 4-6, the thermal printhead 50
forms part of a control module or circuit board assembly
54 that also mounts the control electronics and may even
include the power supply for the electronics and the
printhead. In the illustrated construction, the power
supply does not form part of the assembly 54 due to space
constraints.
In the preferred embodiment, the printhead 50 is
attached to a circuit board 54a by solder connections
55a, 55b made between connecting pins of the thermal
printhead 50 and contacts or circuit traces made on a
circuit board 54a. A support bracket 60 is secured to
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the circuit board 54a by fasteners 62 and serves as a
mechanical support and rigidizes the mounting of the
thermal printhead 50. As seen best in Figure 4, the
circuit board is electronically coupled to, and
mechanically mounts the connectors 22, which may include
a power connector 56, a communications port in the form
of a parallel port connector 58, and a cash drawer
connector 59 by which the printer is interfaced to a host
system, such as a point of sale machine. The parallel
port 58 may be in the form of a DB25 connector. The
power connector is adapted to receive a removable jack or
plug forming part of a "power cube" which is usually
plugged into an A.C. outlet. The connector 59 may be in
the form of a RJ11 or RJ45 jack. It should be noted that
other forms of connectors are contemplated by the present
invention. For example the communications port may a
serial port or alternatively may be a more generic
communications port to which a serial or parallel module
(not shown) is attached, which determines the type of
communication that will be used by the printer.
Referring also to Figure 5, the circuit board 54a
also rigidly mounts a cover open microswitch 70 which is
mechanically actuated by an actuating protrusion (to be
described) forming part of the cover 12. The board
assembly 54 also includes a print media feed switch 72
(which activates the print media transport to advance the
print media). The feed switch 72 is mechanically
actuated by the feed button 16, shown in Figures 1, 1A,
as will be explained. The assembly also includes a LED
73 directly mounted to the board 54a and which is visible
through an opening 73a (See Figure 1) in the housing 14.
In the preferred embodiment the light from the LED 73 is
transmitted to the opening 73a by a light pipe (not
shown) that is mounted at the location indicated by the
reference character 75 in Figure lA. The mounting
arrangement eliminates cabling between the LED 73 and the
board 54a.
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The disclosed control module assembly 54
substantially reduces the manufacturing costs of the
printer, since it eliminates connectors and cabling
between the printhead 5o and the control electronics,
which are typically found in thermal printers. In
addition, cabling between external ports and connectors
are eliminated, as well as cabling between control
switches, status indicators i.e. LED 73 and the control
board. As should be apparent, the board serves as a
mounting point for bath the thermal printhead 50, as well
as the required control switches, LED's and connectors.
The platen roller 40 is rotatably supported in the
cover 12 and includes a driven gear 80 located at one
end. Referring in particular to Figure 3, when the cover
is moved to its closed position (shown in Figure 1), the
driven gear 80 engages a gear train, indicated generally
by the reference character 82 located within the base 10.
The gear train 82 is coupled to a drive motor 84 and
includes a cluster gear 85 directly driven by the motor
84 having an output gear 84a which in turn rotates a
drive gear 86 that couples with the platen gear 80 when
the cover 12 is closed. In the preferred embodiment, the
driven gear 80 of the platen roller 40 engages the drive
gear such that the engagement occurs at a tangent line
that is substantially parallel to the line of action
defined by the platen roller mounting in the cover.
The platen roller 40 is spring loaded and is
laterally movable with respect to the fixed printhead 50.
Referring in particular to Figures 2, 9, 9A and 11A, the
platen roller 40 is supported by spaced apart slots 88a,
88b (see also Figure 8) formed in the hinged cover 12.
The slots allow the platen roller 40 to move towards and
away from the printhead 50 along a line of action
indicated by the reference character 89 in Figure 2.
As seen best in Figures 9 and 9A, the platen roller
is biased towards the printhead 50 by a pair of
springs 92 which act between bushings 93 carried by the
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platen roller and ribs 95 formed in the cover. As seen
best in Figure 9A, the bushings include a narrow diameter
portion 93a which is sized to fit within an associated
' slot. An enlarged portion 93b defining a side surface
93c. The side surface 93c is engageable and rides
against a side surface of the associated slot and locates
the axial position of the platen roller with respect to
the cover 12 so that lateral movement (i.e., movement in
a direction 90 to the line of action 89 is inhibited).
Each bushing 93 also includes an extension 93d which
is sized to fit within its associated spring 91 and
serves to maintain~the position of the spring between its
associated bushing 93 and the abutment 95.
The line of action 89 defined by the slots 88a, 88b
is substantially parallel to a tangent line located at
the engagement point between the driven gear 80 and drive
gear 86. As a result, movement of the platen roller 40
towards and away from the thermal printhead 50 (when the
cover 12 is closed) to accommodate variations in
dimensional tolerances, as well as variations in print
media thickness, do not cause the driven gear 80 to
disengage the drive gear 86.
Although biasing the platen roller 40 using spring
elements directly acting between the cover and the platen
roller 40 is a preferred embodiment, the present
invention contemplates other arrangements for producing a
biasing force on the platen roller 40. Cover
constructions/mountings may be employed which indirectly
generate a biasing force on the platen roller 40, for
urging it towards operative contact with the printhead
50. In short, those skilled in the art will recognize
that the illustrated springs which act between the cover
and the platen roller 40, via the bushings 93, may be
replaced with components that indirectly bias the platen
roller 40 towards the printhead 50.
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According to a feature of the invention, the cover
open switch 70 mounted to the printhead board assembly 54
is actuated by a protrusion 90a formed on the end of a
cover latch member 90 (see Figure 8) on the cover 12
5 which is operative to actuate the switch 70 as the cover
moves to its closed position. The cover includes another
latch member 91 that does not include a similar
protrusion. As seen best in Figure 8 and 9A, the latch
members 90, 91 from at least part of the slots 88a, 88b,
10 which as described above movably supports the platen
roller 40 for movement towards and away from the
printhead 50. The latch members 90, 91, as will be
detailed below, form part of a cover latching system by
which the cover 12 is maintained in its closed position.
In the preferred embodiment, a tolerance
compensating member 94 (see Figures lA, 11A and 11B) is
located intermediate the cover open switch 70 and the
protrusion 90a, when the cover 12 is closed. In the more
preferred embodiment, the tolerance compensating member
94 is a foam element which is compressible. The foam
element is used to compensate for variations in the gap
between the actuating protrusion 90a of the cover latch
member 90 and the position of the cover open detect
switch 70. With the disclosed construction, precise
adjustments between the cover actuating protrusion 90a
and the microswitch 70 in order to effect proper
operation when the cover is closed, are not required.
The foam member located between the latch member 90 and
switch 70 compensates for variations in gap distances
between the protrusion 90a and switch 70 which normally
occur in manufacture.
As seen best in Figures. 11A and 11B, a rectangular-
shaped foam member 94 is located in an opening 98a
defined by an interior housing 98 of the printer. The
foam member is positioned such that it overlies the cover
open switch 70 mounted to the control module assembly 54.
In the illustrated embodimer , a portion 94a of the
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underside of the foam element 94 is secured to a shelf 97
as by adhesive or other suitable means. The remaining
portion 94b of the element 94 is cantilevered above the
' switch 70. When the cover 12 is closed, and as seen best
in Figure 11B, the latch member 90 including the
downwardly extending protrusion 90a contacts the
cantilevered portion 94b of the foam element. As the
cover 12 is moved to the closed position (shown in Figure
11B), the protrusion 90a pushes the foam element 94
towards the switch 70 thereby causing its actuation.
Variations in the final gap between the protrusion 90a
and the microswitch 70 are taken up by the foam.
The cover 12 is latched in its closed position by
the latch members 90, 91. The latch members 90, 91
include latching surfaces 97. The intermediate housing
98, as seen best in Figures loA and 11B, includes a pair
of latch pawls 101, 102 having a complemental latch
surfaces 99 which are engageable with the latching
surfaces 93 formed on the cover latch members 90, 91.
The engagement between the latch surface 97 and the latch
surface 99 is best shown in Figure 11B and is indicated
by the reference character 100. According to the
invention, a mechanism is provided for releasing the
latch pawls 101, 102 without requiring excessive
application force by the operator.
Referring to Figure 1A, a cover unlatching mechanism
comprising a pair of spaced apart lever arms 110, 112 is
located and pivotally supported in the internal housing
98. The lever arms 110, 112 are interconnected by a
shaft 118, so that they rotate in unison about an axis
121 (see Figure l0A) defined by the shaft 118. Referring
also to Figures 10 and 10A, the latch arm 110 defines a
first actuating lever portion 110a, which receives forces
from the cover open button 20 via tab 20a. The
application of force to the first lever portion 110a
rotates the lever 110 and hence the lever 112 (see Figure
lA) in a counterclockwise direction as viewed in Figure
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10A. Each lever arm 110, 112 includes a second lever
portion 120 located on the other side of the pivot axis
121. Downward movement in the first lever portion 110a
causes the second lever portions 120 to move upwardly.
The second lever portions each include a vertically
extending pin-like portion 120a and a laterally extending
finger portion l2ob.
Referring to Figure 10A, the pin-like portion 120a
is operative to engage a Gaming surface 130 on its
associated latch pawl causing the latch pawl to move or
bend leftwardly (as viewed in Figure l0A). This movement
tends to disengage the latch pawl surface 99 from the
latch surface 97 located on its associated cover mounted
latch member. Concurrently, with moving the latch pawls
101, 102 towards the left, the laterally extending f roger
120b of each lever 110, 112 tends to exert upward forces
on an abutment surface 123 formed on the cover mounted
latch members 90, 91 thereby effecting opening of the
cover 12. The combination action provided by the lever
arrangement reduces the effort needed to open the cover
by depressing the cover open button 20.
Figures 12 and 13 illustrate an alternate embodiment
for the cover latching mechanism. In this embodiment, a
spring arrangement is used to pop open a cover 12' when
the cover open button 20 is pressed. As seen best in
Figure 12, a latch arm 110' is rotated about a pivot 121
whenever the button 20 is depressed. The forces from the
button 20 are applied to a first lever portion 110a' via
tab 20a. A second lever portion 120' operates like the
lever portion 120 in Figure 10a to move the latch paw 101
leftwardly in order to disengage the cover 12'. Once
disengagement occurs, a pair of spring members indicated
generally by the reference character 160 operate to raise
the cover 12' upwardly so the operator can grasp and lift
the cover to its opened position.
Referring also to Figures 7 and 13, the spring
members comprise compression springs 162 which act
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between the cover 12' and a cup 164. The assemblage is
maintained by a screw 165 and washer 166 which holds the
cup 164 to a stanchion 168 formed in the cover 12'. The
spring forces act between the cover 12' and side plates
172 forming part of the internal housing member 98 (see
Figure 7).
The print media feed switch 72 located on the
control module assembly is, in the preferred embodiment,
directly actuated by the feed button 16 shown in Figure
1. Referring also to Figures 6 and 7A, the button 16
includes a finger receiving portion 16a and an elongate
arcuate segment 16b. The button 16 is slidably held
within a channel 140 defined in a locating rib 142 molded
into the internal housing 98. The arcuate segment is
rectangular in cross-section and is therefore inhibited
from rotating with respect to the rectangular shaped
channel 140. The coaction between the channel 140 and
the segment 16b operates to transfer the finger forces
applied to the button 16a in one direction to a switch
closing force exerted by the distal end 16c of the button
16 in another direction which is substantially 70
different from the direction of the finger applied force.
With the disclosed construction, a remotely mounted print
media advancing switch is avoided eliminating the need
for cabling and other componentry to connect an actuating
button to the switch and, in turn, connect the switch to
the control electronics. In addition, by internally
mounting the feed switch 72 and actuating it using the
elongate feed button 16, susceptibility to electrostatic
discharge damage to the circuit board and/or switch is
reduced since, in the preferred embodiment, the feed
button 16 is molded from a non-conducting, plastic
material.
Although the switch has been described as one that
produces advancement of print media when actuated, the
switch 72 may be used for other functions, such as
triggering a self test mode when the printer is first
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turned on or used as means to initiate a printer
configuration mode. The switch 72 should not be limited
to a print media advancing function.
Returning to Figures lA and 2, the disclosed printer
may be outfitted with the cutter 15. In the preferred
embodiment, the cutter 15 includes a fixed blade 15a
mounted to the cover 12. A moving blade assembly 15b is
mounted in the base 10 and is enclosed by the removable
cover 14. The moving cutter assembly includes a
to reciprocating blade 150 which moves towards and away from
the fixed blade 15a. A drive motor 152 forming part of
the cutter assembly effects the required reciprocating
movement in the blade 150. As seen best in Figure 2,
when the blade moves through its cutting cycle towards
and away from the fixed blade 148, a print media portion
52a extending through the slot 12 is severed from the
remainder of the print media 52.
Figure 7 illustrates the overall construction of the
internal housing 98. The housing is preferably a molded
product and includes latches 103 by which it is removably
held within the base 10. The internal housing 98
defines, at least partially, the paper supply compartment
13 in which a roll of print media is placed. In the
disclosed construction, when the print media 52 needs to
be replenished, the cover 12 is opened and a roll of
print media is placed within the compartment 12. The
leading end of the print media is passed over the
printhead and laid atop the cover 14. The cover 12 is
then rotated to its closed position at which time the
platen roller 40 re-engages the printhead and clamps the
print media between itself and the printhead. The end of
the print media then extends through the slot 18 which is
defined between the rotatable cover 12 and the cover 14.
With the disclosed construction, the paper does not have
to be fed between paper paths components, i.e., rollers
or between components of the cutter (since the fixed
blade 15a moves out of the paper path when the cover 12
......_.._..~ ._.~._....._ . .~.....r...=.. ..,.........t.. ~ . ..
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is opened). In the disclosed construction, the fixed
blade of the cutter is attached and moves with the cover
12, whereas the reciprocating blade portion of the cutter
remains with the base 10.
5 Figure 14 illustrates, in detail, the preferred
cutter mechanism 15. As indicated above, the mechanism
includes a fixed blade 15a which is mounted to the cover
12. A reciprocating blade 250 is carried by the moving
blade assembly 15b which is mounted to the base 10 of the
10 printing apparatus. As viewed in Figure 14, when the
cover 12 is opened, the fixed blade 15a moves upwardly
with respect to the reciprocating blade 150.
To promote uniform contact between the fixed blade
15a and the reciprocating blade 150, when the cover is
15 closed, a self-alignment mechanism is provided. In the
disclosed embodiment, the blade 150 includes a pair of
spaced apart laterally extending ears 180 which contact
the underside of the fixed blade 15a whenever the cover
is closed. The blade 150 itself is at least partially
held to a cutter mounting plate 184 by a compression
spring and fastener 190, 192 respectively. The spring
190 exerts an upward force on the blade 150 so that
contact with the fixed blade 15a is maintained while
allowing the blade to move (and even rotate slightly) in
order to align itself with the blade 15a, even if there
are slight misalignments between the cover 12 and the
base 10. As a consequence, reliable cutting of the print
media which passes between a cutting edge 196 of the
fixed blade 15a and a V-shaped cutting edge 198 of the
blade 150 is improved.
As is conventional, when cutting is desired, the
motor 152 is energized to move the blade 150 towards and
away from the fixed blade 15a. A slot 200 formed in the
blade 150 allows relative movement between the blade and
the fastener 192. In the preferred embodiment, the
alignment ears 180 remain in sliding contact with the
underside of the blade 15a throughout the cutting cycle.
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It should be noted that this aspect of the invention also
contemplates a spring loaded fixed blade 15a to provide
the self-alignment function.
Figure 14A illustrates an alternate arrangement for
biasing the blades towards uniform cutting contact. In
the alternate arrangement, a fixed blade 15a' is biased
towards a reciprocating blade 150' by a spring 190' that
acts between the fixed blade 15a' and a cover portion
12a " . The fixed blade 15a' is urged into contact with
the reciprocating blade 150' whenever the cover 12 " is
closed.
The disclosed invention provides a very compact and
cost effective printer that is easily loaded. Costly and
complex cabling between a printhead, control components
and interfacing connectors is eliminated or substantially
reduced. The disclosed construction also facilitates
servicing and component replacement in the printer. In
addition, the internal mounting of all of the electronic
components including control switches reduces the risk of
damage to electronic components due to electrical
discharges, etc.
Although the invention has been described with a
certain degree of particularity, it should be understood
that those skilled in the art can make various changes,
alterations and substitutions to the embodiments
described herein without departing from the spirit or
scope of the invention which is defined by the following
claims.
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