Note: Descriptions are shown in the official language in which they were submitted.
CA 02836062 2013-12-09
THERMAL PRINTER WITH SINGLE LATCH, ADJUSTABLE MEDIA
STORAGE AND CENTERING ASSEMBLIES, AND PRINT ASSEMBLY
BACKGROUND
Technical Field
[0002] The present disclosure relates generally to printers, and in
particular, to a direct
thermal printer with a single latch assembly, an adjustable media storage
assembly guide, a
media centering assembly, a print assembly, and a temperature sensing member.
Description of Related Art
[0003] Direct thermal printers are used to produce a printed image by
selectively heating
specially coated media as it passes over the printer's thermal printhead. An
image is produced
where the media's coating turns black in the areas where it is heated.
Traditional thermal
printers include a thermal printhead, which generates heat and effectively
prints on the media, a
platen, or roller (typically rubber), that feeds the media through the
printer, a spring or similar
mechanism that urges the thermal printhead toward the media to establish
physical contact
between the printhead and the media to facilitate thermal printing, and a
controller that controls
the printer.
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SUMMARY
[0004] An example embodiment of the present disclosure includes a printer,
such as a direct
thermal printer, that comprises a housing including a cover and a base
connected together with a
hinge, a latch assembly disposed in the cover, a media storage assembly
disposed in the base, a
media centering assembly disposed in the base, a print assembly disposed in
the housing, and a
temperature sensing member disposed in the base.
[0005] The latch assembly includes a latch lever disposed at least in part
on the exterior of
the cover in mechanical communication with latch tabs also disposed in the
cover such that
actuation of the latch lever will simultaneously actuate the first and second
latch tabs. Openings
in the base of the printer are adapted to receive the latch tabs. Once
inserted into the openings,
actuation of the latch tabs will move the latch tabs between a locked position
and an unlocked
position allowing the cover to be selectively engaged and disengaged from the
base.
[0006] The media storage assembly includes media guides each having tab
slots for receiving
removable and repositionable tabs. The media guides also include securing tabs
for securing the
removable and repositionable tabs in the tab slots. The removable and
repositionable tabs
include a male feature disposed on the face of each tab. In a first position
in the tab slot, the
removable and repositionable tab's male feature is in a position to hold media
of a certain size.
When the removable and repositionable tab is repositioned to a second position
in the tab slot,
the removable and repositionable tab's male feature is in a position to hold
media of another
inside diameter (ID) core size.
[0007] The media centering assembly includes mounting plates disposed on
the media guides
and pulley assembly disposed in the base. Each pulley assembly includes a belt
that is attached
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at one end to one media guide and at the other end to the other media guide.
An extension spring
disposed in the base is secured to the base at a first end and to one of the
mounting plates at its
other end. The extension spring provides a force to bias the first media guide
towards the second
media guide.
[0008] The print assembly includes a printhead disposed in the cover and
retained by an
inner cover frame and positioned by compliant members that apply a force
against a platen
disposed in the base retained by a bearing and having a cam disposed at both
ends of the platen.
The compliant members of the printhead provide limited radial movement of the
printhead along
the printhead's axis. The platen's bearing provides radial movement of the
platen along the
platen's axis. The print assembly further includes a set screw disposed in the
base and a leaf
spring disposed on the platen's bearing and also in contact with the set
screw. Rotation of the set
screw rotates platen's cams and this rotation causes contact of the first and
second cams with the
printhead which positions the printhead forward along the axis of the paper
motion.
[0009] The printer optionally includes a temperature sensing member
disposed in the base to
sense the temperature of certain components.
[0010] In another aspect, the present disclosure is directed to a media
centering assembly.
The media centering assembly includes a first media guide and a second media
guide disposed in
slidable opposition to one another and configured to support a roll of media
therebetween. The
media centering assembly includes a first pulley assembly having a first
pulley and a first belt.
The first belt is in communication with the first pulley and is operably
coupled to the first media
guide at a first end of the first belt, and the first belt is operably coupled
to the second media
guide at a second end of the first belt. The media centering assembly includes
a second pulley
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I
assembly having a second pulley and a second belt, wherein the second belt is
in communication
with the second pulley and is operably coupled to the second media guide at a
first end of the
second belt, and the second belt is operably coupled to the first media guide
at a second end of
the second belt. An extension spring is operably coupled, at a first end of
thereof, to an anchor,
and the extension spring operably coupled to the first media guide at a second
end of the
extension spring. The extension spring is configured to bias the first media
guide toward the
second media guide.
[0011] In some embodiments, the media centering assembly includes a
first mounting plate
disposed on the first media guide, and a second mounting plate disposed on the
second media
guide. In some embodiments, the first belt is fixed to the first mounting
plate at a first end of the
first belt, and is fixed to the second mounting plate at a second end of the
first belt. The second
belt is fixed to the second mounting plate at a first end of the second belt,
and is fixed to the first
mounting plate at a second end of the second belt.
[0012] In some embodiments, the first media guide and the second
media guide each include
a male protrusion configured for insertion into a support tube of a media
roll. In some
embodiments, the male protrusion is disposed on a reversible member having a
first position
wherein the male protrusion is configured for insertion into a support tube of
a media roll having
a first diameter, and a second, reversed position, wherein the male protrusion
is configured for
insertion into a support tube of a media roll having a second diameter
different from the first
diameter. In some embodiments, the first media guide and the second media
guide include a tab
slot defined therein, and the reversible member includes a tab configured to
selectively engage
the tab slot of the corresponding first or second media guide.
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a
[0013] In another aspect, the present disclosure is directed to a
printer that includes a housing
having a cover and a base connected together with a hinge. A latch assembly is
disposed in the
cover. The latch assembly includes a latch lever disposed at least in part on
the exterior of the
cover in mechanical communication with a first latch tab and a second latch
tab, such that
actuation of the latch lever simultaneously actuates the first and second
latch tabs. The base
includes first and second openings defined therein that are adapted to receive
the first and second
latch tabs respectively, wherein the actuation of the first and second latch
tabs once inserted into
the first and second openings will move the latch tabs from a locked position
to an unlocked
position allowing the cover to be disengaged from the base. The printer
includes a print
assembly disposed in the housing having a bearing disposed in the base, and an
elongate
cylindrical platen disposed in the base and rotatable about its longitudinal
axis. The platen is
retained by the bearing and the bearing facilitates rotation of the platen
along the platen's
longitudinal axis. The print assembly includes a first cam disposed on a first
end of the platen,
and, a temperature sensor disposed in the base.
[0014] In some embodiments, the printer includes a second cam
disposed on a second end of
the platen, a set screw disposed in the base, and, a leaf spring disposed on
the second bearing and
in contact with the set screw. Rotation of the set screw rotates the first and
second cams and, in
turn, rotation of the first and second cams causes contact of the first and
second cams with a
printhead. In some embodiments, an anchor slot is defined in the base that is
configured to
receive a portion of the leaf spring. In some embodiments, the leaf spring is
configured for
deflection in a transverse direction away from the platen to enable the leaf
spring to move out of
the anchor slot.
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[0015] In some embodiments, the bearing is configured for selective removal
from the platen
by rotating the bearing relative to the platen by a predetermined amount. In
some embodiments,
the predetermined amount of rotation is about 43 degrees.
[0016] In some embodiments, the printer includes a motor operably coupled
to the platen. In
some embodiments, the printer includes a temperature sensor configured to
sense the
temperature of the motor. In some embodiments, the temperature sensor provides
closed loop
temperature control of the motor.
[0017] In yet another aspect, the present disclosure is directed to a
printer that includes a
housing having a cover and a base connected together with a hinge. The printer
includes a latch
assembly disposed in the cover. The latch assembly includes a latch lever
disposed at least in
part on the exterior of the cover in mechanical communication with a first
latch tab and a second
latch tab. Actuation of the latch lever simultaneously actuates the first and
second latch tabs.
The base includes first and second openings defined therein to receive the
first and second latch
tabs respectively. Actuation of the first and second latch tabs, once inserted
into the first and
second openings, move the latch tabs from a locked position to an unlocked
position thus
allowing the cover to be disengaged from the base. The printer includes a
media centering
assembly disposed in the base. The media centering assembly includes a first
media guide and a
second media guide disposed in slidable opposition to one another and
configured to support a
roll of media therebetween. The media centering assembly includes a first
pulley assembly
having a first pulley and a first belt. The first belt is in communication
with the first pulley and
is operably coupled to the first media guide at a first end of the first belt,
and is operably coupled
to the second media guide at a second end of the first belt. The media
centering assembly
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includes a second pulley assembly that includes a second pulley and a second
belt. The second
belt is in communication with the second pulley and is operably coupled to the
second media
guide at a first end of the second belt, and operably coupled to the first
media guide at a second
end of the second belt. The media centering assembly includes an extension
spring operably
coupled to an anchor at a first end of the extension spring, and is operably
coupled to the first
media guide at a second end of the extension spring and configured to bias the
first media guide
toward the second media guide.
[0018] In
some embodiments, the printer includes a first mounting plate disposed on the
first
media guide, and a second mounting plate disposed on the second media guide.
In some
embodiments, the first belt is fixed to the first mounting plate at a first
end of the first belt, and is
fixed to the second mounting plate at a second end of the first belt. The
second belt is fixed to
the second mounting plate at a first end of the second belt, and is fixed to
the first mounting plate
at a second end of the second belt. In some embodiments, the first media guide
and the second
media guide each include a male protrusion configured for insertion into a
support tube of a
media roll. In some embodiments, the male protrusion is disposed on a
reversible member
having a first position wherein the male protrusion is configured for
insertion into a support tube
of a media roll having a first diameter, and a second, reversed position
wherein the male
protrusion is configured for insertion into a support tube of a media roll
having a second
diameter different from the first diameter.
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BRIEF DESCRIPTION OF THE DRAWINGS
[0019] The present subject matter may take form in various components
and arrangements of
components, and in various steps and arrangements of steps. The appended
drawings are only
for purposes of illustrating particular embodiments and are not to be
construed as limiting the
subject matter.
[0020] Fig. 1 is a front perspective view of an assembled thermal
printer constructed in
accordance with an example embodiment of the present disclosure;
[0021] Fig. 2 is a front perspective view of an assembled thermal
printer shown with its
cover open and constructed in accordance with an example embodiment of the
present
disclosure;
[0022] Fig. 3A is a perspective view of the media storage assembly in
accordance with an
example embodiment of the present disclosure;
[0023] Fig. 3B is a perspective view of exemplary media that may be
used in an example
embodiment of the present disclosure;
[0024] Fig. 4 is a top perspective view of the media centering
assembly in accordance with
an example embodiment of the present disclosure;
[0025] Fig. 5 is a perspective view of the portion of the print
assembly including a portion of
the platen and the cam located at one end of the platen constructed in
accordance with an
example embodiment of the present disclosure;
[0026] Fig. 6 is a side perspective view of the portion of the print
assembly including a
portion of the platen and the cam located at one end of the platen, the drive
train, and a
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temperature sensing member constructed in accordance with an example
embodiment of the
present disclosure; and
[0027] Fig. 7 is a circuit drawing of the temperature sensing member
constructed in
accordance with an example embodiment of the present disclosure.
DETAILED DESCRIPTION
[0028] Particular embodiments of the present disclosure are described
hereinbelow with
reference to the accompanying drawings; however, it is to be understood that
the disclosed
embodiments are merely examples of the disclosure, which may be embodied in
various forms.
Well-known and/or repetitive functions and constructions are not described in
detail to avoid
obscuring the present disclosure in unnecessary or redundant detail.
Therefore, specific
structural and functional details disclosed herein are not to be interpreted
as limiting, but merely
as a basis for the claims and as a representative basis for teaching one
skilled in the art to
variously employ the present disclosure in virtually any appropriately
detailed structure. In
addition, as used herein in the description and in the claims, terms
referencing orientation, e.g.,
"top", "bottom", "upper", "lower", "left", "right", and the like, are used
with reference to the
figures and features shown and described herein. It is to be understood that
embodiments in
accordance with the present disclosure may be practiced in any orientation
without limitation. In
this description, as well as in the drawings, like-referenced numbers
represent elements which
may perform the same, similar, or equivalent functions.
[0029] Turning first to Figs. 1 and 2, according to aspects of the present
disclosure, direct
thermal printer 100 includes base 110 and cover 120. Cover 120 is configured
for selective
engagement with a top portion of base 110 and includes top frame 180, latch
lever 140, and latch
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tabs 220. In the present embodiment, top frame 180 includes an enlarged
section of a top surface
121 of cover 120, and is generally configured to allow cover 120 to couple
with base 110 without
contacting or interfering with the supply of print media 150 disposed within
printer 100.
Additionally, cover 120 may be hingedly attached to a rear portion of the base
at hinge 130.
Various structures known in the art to hingedly attach cover 120 to base 110
are also
contemplated, for example and without limitation, a conventional hinge-pin
arrangement, a
living hinge, and so forth. During use, cover 120 may be pivoted or rotated
about hinge 130 to
enable a user to selectively access the components in base 110, to load and
unload media, and the
like. A view of printer 100 with cover 120 open and media inserted is shown in
Fig. 2.
100301 Latch lever 140 can be mechanically connected to latch tabs
220 which can be
disposed on opposing sides of cover 120. Latch tabs 220 can be normally biased
for engaging
slots 230 located in base 110. Actuation of latch lever 140 can simultaneously
actuate latch tabs
220 , which overcomes the bias such that latch tabs 220 do not engage slots
230 in base 110 and
cover 120 can be pivoted about hinge 130 or separated from base 110.
Conversely, the normal
bias of latch tabs 220 urges latch tabs 220 to engage a portion of slots 230
thereby securing cover
120 to base 110.
100311 Front plate 160 of base 110 provides an exit surface over
which media 150 passes as
it exits printer 100. Front plate 160 may be pulled away from base 110 to
provide space for the
attachment of optional accessories, such as a label peeler and/or a cutter, to
base 110.
[0032] Printer 100 can be supplied with power from an electrical
source (not shown). The
electrical source of energy can be AC or DC depending on the desired
configuration of printer
100. Switches or buttons 170 can be positioned on the top face of cover 120
and can be in
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electrical communication with a control circuit (not shown) that is disposed
within printer 100.
The control circuit can be a printed circuit board or any control circuit
known in the art sized to
fit in printer 100. Buttons 170 can control operation of printer 100 such as
pause, resume, and
feed.
[0033] Media storage assembly 300, which can be seen only partially
in Fig. 2, is shown in
further detail in Figs. 3A and 4. Media storage assembly 300 includes spaced
apart media guides
310 each having tab slots 320 for receiving removable tabs 330 which may be
selectively
positioned within tab slots 320. Media guides 310 can also include securing
tabs 340 for
securing removable tabs 330 in tab slots 320. Removable tabs 330 can include
disc-shaped male
features 350 disposed on the face of removable tabs 330. Male features 350 are
adapted for
engaging a portion of the inside diameter of media supply roll 152. Various
types of media 150
may have an inside diameter of varying sizes. For example, as illustrated in
Fig. 3B, media
supply roll 152a has an inside diameter 360a of diameter da, while media
supply roll 152b has an
inside diameter 360b of diameter db that is greater than diameter da.
[0034] Media supply roll 152, media supply roll 152a, and/or media
supply roll 152b may
include a support tube 151, support tube 151a, and/or support tube 151b,
respectively, that
engages male feature 350 such that media supply roll 152 is rotatable on male
features 350,
thereby allowing media 150 to be fed from media supply roll 152 toward
printhead 510. Media
guides 310 can be repositioned within tab slots 320 to allow for media supply
rolls 152 of
different inside diameters to fit in printer 100. In a first position in tab
slot 340, which is
indicated by 330a, removable tab's 330 male feature 350 is in a position to
hold media rolls of a
certain size, for example, a media supply roll having a width of 1.5 inches.
When removable tab
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,
330 is removed, rotated 180 degrees, and reinserted in a second position,
which is indicated by
330b, in the tab slot, removable tab's 330 male feature 350 is placed in a
position suitable to hold
media of another size, for example, 1.0 inches wide.
[0035] Turning now to Fig. 4, media centering assembly 400 is shown
in further detail.
Media centering assembly 400 may include mounting rails (not shown) disposed
in base 110,
first and second mounting plates 410 disposed on first and second media guides
310, and pulley
assemblies 415a and 415b disposed in base 110. Pulley assembly 415a includes
pulley 420a and
belt 430a. As shown in Fig. 4, belt 430a can be attached to a first mounting
plate 410 with
fastener 440a and to a second mounting plate 410 with fastener 440b. Pulley
assembly 415b
includes pulley 420b, belt 430b, and extension spring 450. As shown in Fig. 4,
belt 430b is
joined to one of mounting plates 410 with fastener 440c and to the other media
of mounting
plates 410 with another fastener (not shown). Although fasteners are
illustrated here, any
attaching mechanisms known in the art are contemplated by the present
disclosure, including
without limitation, threaded fasteners, rivets, clips, adhesive, integral
forming, overmolding,
intermolding, and so forth. Mounting plates 410 are slidably mounted to the
mounting rails (not
shown) such that movement of mounting plates 410 and guides 310 is directed in
a transverse
linear path. Extension spring 450 is disposed between one of mounting plates
410 and an anchor
451 situated on a portion of base 110 that is opposite mounting plate 410,
such as the platen
bracket (not shown), an interior wall of base 110, or any other suitable
position. Extension
spring 450 is biased for pulling media guides 310a, 310b towards each other.
[0036] During use, in order to insert a media roll 152 on male
features 350, a user pushes
apart media guides 310 thus extending extension spring 450 to overcome the
bias thereof. After
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media roll 152 is positioned on media guides 310, e.g., male features 350 are
inserted into
support tube 151 of media roll 15, the user releases media guides 310, which,
in turn, causes
extension spring 450 to contract, thus allowing the media guides 310 to pull
towards each other
and thereby hold media roll 152 in place. Advantageously, the interaction of
belt 430a and
pulley 420a with left media guide 310a and right media guide 310b, the
interaction of belt 430b
and pulley 420b with left media guide 310a and right media guide 310b,
together with the inward
bias of extension spring 450, enables media guides 310 to move in a reciprocal
manner about the
centerline A-A (Fig. 2) of printer 100, which, in turn, enables media guides
310 to retain media
roll 152 in a centered position relative to printhead 510. In this manner,
centering of the print
media roll 152 may be achieved without the bulk and friction typically
encountered with
conventional rack and pinion arrangements.
[0037] Print assembly 500, which is shown partially in Fig. 2, is disposed
within base 110
and/or within cover 120. A portion of print assembly 500 that may be disposed
in cover 120
includes inner cover 562, compliant members (such as compression springs - not
shown) and
printhead 510. Inner cover 562 and compliant members can retain printhead 510
providing
limited radial movement of printhead 510 along printhead 510's axis.
[0038] The portion of print assembly 500 is shown in further detail in Fig.
5. Bearing 550
retains platen 520 and facilitates axial rotation of platen 520 along a
longitudinal axis thereof. A
cam 530 is disposed at each end of platen 520. An adjustment set screw 560 is
disposed in base
110. Leaf spring 540 is disposed at a first end 541 on the bearing 550 and at
a second end 542 in
slot 545. When positioned in slot 545, leaf spring 540 contacts a set screw
560. Rotation of set
screw 560 engages leaf spring 540, which, in turn, rotates cam 530. As cam 530
rotates,
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printhead 510 is translated in a longitudinal direction (e.g., along axis A-
A). In this manner, the
position of printhead 510 may be adjusted to achieve optimal printing. Set
screw 560 includes a
tool engaging feature 561, such as a slot, Phillips head, Pozidrive head, hex
head, Torx head, and
the like to facilitate the adjustment thereof with a screwdriver or other
suitable tool. In some
embodiments, set screw 560 may be knurled to enable adjustment using only the
fingers. Leaf
spring 540 is biased inward, e.g., toward platen 520, to retain platen 520 in
association with
bearing 550. During use, leaf spring 540 may be deflected in a transverse
direction away from
platen 540 (e.g., orthogonal to axis A-A) to allow leaf spring 540 to move out
of its anchor
position in base 110. Once bearing 550 is rotated a predetermined amount, for
example, about
43 degrees, bearing 550 may be removed from the platen bracket (not shown) to
facilitate the
removal and replacement of platen 520, bearing 550, leaf spring 540 and/or set
screw 560.
[0039] Printer 100 also includes motor 605 as shown in Fig. 6. Motor 605,
which may be a
stepper motor, a DC motor, an AC motor, or any suitable motor now or in the
future known, is
operatively coupled to platen roller 520 via drive train 620 such that a full
step of motor 605
corresponds to a predetermined length of media 150 movement. Temperature
sensor 610, which
may include a thermistor, and drive train 620, are shown in Fig. 6.
Temperature sensor 610 is
disposed in base 110 and is configured to sense and/or monitor the temperature
of motor 605,
providing closed loop temperature control of motor 605 which, in turn, allows
printer 100 to run
at higher duty cycles and protect the printer 100 and/or motor 605 from
overheating.
[0040] Fig. 7 shows a stepper motor interface 700 which illustrates the
electrical connections
of the temperature sensor 610 to an analog-to-digital converter (ADC) input
612 of the printer
controller (not shown), which is used to determine motor temperature. In the
illustrated
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_
embodiment, motor 605 employs a four-wire arrangement in which the relative
timing of the
phase A 614 and phase B 616 motor drive signals, as provided by the
controller, determines the
rotational output of motor 605 and thus, the advancement of media 150.
[0041]
The described embodiments of the present disclosure are intended to be
illustrative
rather than restrictive, and are not intended to represent every embodiment of
the present
disclosure. Further variations of the above-disclosed embodiments and other
features and
functions, or alternatives thereof, may be made or desirably combined into
many other different
systems or applications without departing from the spirit or scope of the
disclosure as set forth in
the following claims both literally and in equivalents recognized in law.
