Note: Descriptions are shown in the official language in which they were submitted.
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REPLACEABLE TRANSFER MEDIUM CASSETTE
IDE~l'l'l~'l~l) BY CODING MEANS
BACKGROUND OF THE INVENTION
The present invention relates to a method and
apparatus for making a graphic product on sheet material.
More particularly, the invention relates to the m~king of product
with enhanced graphic features through a combination of printing
and cuttiing operations, and the equipment and the processes
utilized in m~king of the product. The equipment and processes
have many uses such as m~king signs, graphic (le.~ign.~, characters
and other products with graphic images, characters and other
products with graphic images, and may be used in the field of
printing for the production of visual images from data bases.
Within the ~ignm~king field, the generation
of graphic (le.~ign~ from a stored program is known from
U.S. Patent 4,467,525 entitled AUTOMATED SIGN
GENERATOR and U.S. Patent 4,799,172 entitled APPARATUS
AND METHOD FOR AUTOMATIC LAYOUT OF A SIGN TEXT.
The apparatus utilizes a cutting tool that is guided in accordance
with a predetermined program to cut alphanumeric characters and
other graphic images from a sheet of vinyl material that is
releasably secured by a pressure-sensitive adhesive to a carrier
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or liner. The apparatus is controlled by a
microprocessor and includes a keyboard and fonts
stored in a memory to prepare sign text. Once the
text has been prepared, the apparatus cuts the
alphanumeric characters or other graphic designs from
the vinyl and the sign text or character is stripped
away from the carrier as a whole and transferred to a
sign board.
U.S. Patent 4,834,276 discloses a web
loading and feeding system in a signmaking apparatus
such as described above. The novel feeding system
described is utilized to accurately position a web of
vinyl material as it is loaded into a signmaking
apparatus and to feed the web during the generation
of the graphic images comprising the sign.
To achieve a multicolored sign or to
produce three dimensional effects with the apparatus
disclosed, it is necessary to cut multiple images in
different colored materials and then manually overlay
the graphic images cut from the colored materials.
Alternatively a multi-ply layup of sign material in
which different plies have different colors can be
formed and cut with similar effects as more
particularly described in U.S. Patent 4,512,839.
In the field of printing, it is well known
to produce single or multi-color im~ges from stored
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data bases. For example, U.S. Patent 4,618,870
discloses thermal transfer-type printer in which a
plurality of colors of thermally fusible ink are
transferred to a printing medium so as to produce
halftone and color images. Another thermal printer
for producing multi-color images is disclosed in U.S.
Patent 4,994,822 which utilizes a foil or web of
transfer dyes in multiple colors and contains a
thermal print head which is excited with pulses of
different widths to control the continuous tone color
in an image. U.S. Patent 4,899,170 reveals still
another technique for exciting the thermal print
head. A related U.S. Patent 4,804,975 discloses the
details of a transfer dye used in a thermal printer.
U.S. Patent 4,496,955 discloses another
thermal printing apparatus for printing color images
on a print medium by means of a thermally
transferable material carried on an intermediate web.
The web is provided with successive frames of
respectively different colors of the thermally
transferable material, and index marks along the edge
of the web indicate the boundaries between adjacent
color frames. A number of passes of the print medium
mounted on a rotatable platen, each pass being
carried out with a different colored frame of the
web, permits the printing of images~in the respective
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colors on the web. In one embodiment the web of
thermally transferrable matorial is contained within
a cassette which is received within the housing of
the apparatus.
S U.S. Patent 5,110,228 illustrates in detail
a cassette that may be used in a thermal printer for
supporting a web of the thermal transfer film. The
illustrated cassette has reels or spindles on which
the film is wound, and a rGtation prevention
mechanism to prevent the film from coming loose when
the cassette is removed from a thermal printer.
U.S. Patent 4,815,869 is also related to
the printing field, and discloses a method for
printing multicolor images from computer stored
lS information by means of a dot matrix printer.
The demand for signs and other sheet
material products with multicolored or enhanced
graphic images is enormous. While multicolor
printing is well known in the art and producing
multicolored or enhanced signs by cutting graphic
images in sheet material is also well known, a merger
of these arts has not been previously employed to
produce enhanced graphic images. Furthermore, the
convenience, flexibility and speed of producing signs
and other graphic images from computer data bases
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offers significant advantages and substantial
opportunity for improvement.
It is accordingly a general object of the
present invention to provide a method and apparatus
for making signs, characters, designs and other
graphic products that are enhanced through color,
halftone and other printed features.
SUMMARY OF THE INVENTION
The present invention resides in a method
and apparatus for making a graphic product such as a
sign, character, design or other graphic image on
sheet material through the use of a machine readable
data base. More particularly, the present invention
relates to a method and apparatus that prints and
cuts graphic products from a stored data base to
produce enhanced images.
The apparatus, which carries out the
method, includes a first storage means that stores
data defining the peripheral edges of a graphic image
to be generated in the product. The data stored is
machine readable data. A second storage means stores
the data that defines the printed material in po-
sitional relationship within the peripheral edges of
a graphic image in the product. The data defining
the printed material is also stored as machine
readable data.
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Printing means are connected with the
second storage means and responds to the machine
readable data to print printed material on the
surface of a sheet material in positional
relationship to the peripheral edges of the graphic
image. Preferably thereafter, cutting means con-
nected with the first storage means responds to the
stored data for cutting the sheet material along the
peripheral edges of the graphic image. The cutting
is controlled in accordance with the stored data
whereby graphic images containing the printed
material within the cut edges of the image are
prepared from the sheet material.
In one embodiment of the invention, the
printing means is a thermal printer having a printing
head and a roller platen over which the sheet
material is fed during the printing operation. The
roller platen has a cylindrical support surface and
supports the sheet material adjacent the printing
head for movement relative to the head during the
printing operation.
In order to engage and feed the sheet
material relative to the printing head, the roller
platen has a width between the axial ends that is
less than the width of the material on the platen,
whereby a marginal edge portion of the material
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overlaps each axial end of the platen. Drive means
engages the marginal edge portions of the sheet
material at each end of the platen, and feeds the
material over the platen relative to the printing
head.
Preferably the sheet material has a series-
of feed holes along the marginal edges, and the drive
means has sets of sprockets that engage the holes at
each marginal edge for positive feeding of the
lo material over the platen. The set of sprockets may
be movable relative to the roller platen in a plane
that is tangential to the cylindrical support surface
of the platen, and when the sprockets are arranged in
a circular array, they move in a cylindrical plane
lS that is tangent to the cylindrical support surface of
the roller platen but larger in diameter to provide
greater contact areas with the sheet material
supported on the platen.
The thermal printer cooperates with a donor
web bearing a printing dye or ink that is transferred
to the sheet material by the head during a printing
operation. The donor web is moved relative to the
head along with the material receiving the printed
image so that a printing ink is transferred to the
2~ material in accordance with the stored data.
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A number of controls are employed to
regulate the printing operation. For example, the
pressure applied between the printing head and sheet
material may be regulated as well as the spacing
between the head and material so that the donor web
carrying the printing ink moves with the material
during printing and is disengaged from the material
for slewing during non-printing phases of the
operation. In one embodiment the donor web is
supported in a cassette for ease of installation and
removal in the printing means. The cassette carries
a code that is read by the printer in order to
regulate various parameters of the printing operation
such as the pressure between the head and the sheet
1s material, the speed of the printing operation or the
excitation of the head of printer. Detectors for
signaling the absence of material and jams render the
printing operation more secure.
As a result of the invention, signs,
characters, designs and other graphic images can be
produced in multiple colors or halftones and with
other printing features which significantly enhance
the images.
BRIEF DESCRIPTION OF THE DRAWINGS
Fig. 1 is a schematic diagram illustrating
a system for printing and cutting s~gns and other
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graphic products in accordance with the present
invention.
Fig 2. is a three dimensional halftone
image of the letter "R" that can be produced in
accordance with the present invention.
Fig. 3 is a three dimensional image of the
letters "AR" that can be produced in accordance with
the present invention.
Fig. 4 shows one embodiment of a thermal
printer that may be utilized in the present
invention.
Fig. 5 is a side elevation view of the
thermal printer in Fig. 4 with portions broken away
to show the internal structure.
Fig. 6 is an enlarged fragmentary view of
the printer as shown in Fig. 5 and shows the drive
mechanism for moving a strip of sheet material
relative to the print head.
Fig. 7 is an enlarged fragmentary view of
the printer similar to Fig. 6 and shows the print
head, roller platen and sheet material detector.
Fig. 8 is a fragmentary front view showing
the support structure and drive mechanism for the
roller platen and drive sprockets.
Fig. 9 is another side elevation view
showing the cassette supporting the-donor web with
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the printing ink and the code reader before reading
the code for the donor web.
Fig. 10 is a fragmentary view similar to
Fig. 9 after a code reading.
Fig. 11 is a fragmentary view showing the
support structure for the supply reel in the cassette
containing the donor web.
Fig. 12 is a fragmentary view illustrating
the drive mechanism for the take-up reel in the
cassette containing the donor web.
Fig. 13 is a perspective view of the
cassette containing the donor web.
Fig. 14 is a side elevation view of the
cassette in Fig. 13.
Fig. 15 is an end view of the cassette in
Fig. 13 and shows the positioning of the label
bearing the web coding.
Fig. 16 is a cross-sectional view of the
cassette as viewed along the line 16-16 in Fig. 14.
Fig. 17 is a schematic diagram illustrating
the components that are responsible for controlling
the various functions of the thermal printer in
response to the coding on a donor web cassette.
Fig. 18 illustrates the pattern of the
coding on the cassette in one embodiment of the
invention .
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DESCRIPTION OF THE PREFERRED EMBODIMENTS
Fig. 1 illustrates a microprocessor based
system, generallyrdesignated 10, having apparatus for
making signs, characters, designs and other graphic
products with enhance-ments provided by the addition
of color, halftones and other printed features.
For example, the letter "R" shown in Fig. 2
has printed halftone characteristics which imbue the
letter with a three dimensional character. Such
printed enhancements of the letter are quite
distinctive and when such letters are cut along the
peripheral edges C from a sheet material such as a
vinyl sheet which can withstand weather, wear, abuse
and other hazards rather well, a very attractive sign
or other graphic product is generated.
Similarly, the letters "AR" shown in Fig. 3
can be prepared in two dimensional form on a single
sheet of vinyl or other material with a three
dimensional character by using different colors for
the face of the letters and the shadow or third
dimension.
The system disclosed in Fig. 1 enables a
graphic product to be created and produced with
enhancements from a data base on which both the
printed and cut features of the product are commonly
based. To produce a graphic product with
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enhancements, the system 10 includes a digitizer 12
or other data input device which supplies a
microprocessor based or other computer 14 with
machine readable data defining at least the
peripheral edges of the graphic product and possibly
internal edges as well. The computer 14 displays the
machine readable data defining the edges as an image
on the screen 15. Then printed enhancements from the
special enhancement programs in memory 16 printing
designs are added within the edges of the displayed
image with the aid of the computer as the operator or
composer desires. All the edge and enhancement
features are then referenced to one another in a
common data base. For example, the enhancement
features may include special programs that allow
halftone images such as the halftone features shown
in Fig. 2 to be added within the peripheral edges of
the pattern P.
Alternatively, the memory 16 may include an
entire font of halftone or otherwise enhanced
characters including the edge data, in which case the
data input to the computer 14 for the purposes of
preparing a final product may be selected entirely
from the memory. Still further, the digitizer may
serve as the sole input device and may provide the
critical data points defining the peripheral edges to
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be cu~ as well as the edges of the printing as in the
enhanced letters "AR" shown in Fig. 3. Still other
data sources may b~e utilized to supply the computer
14 with an infinite variety of graphic images with
S enhancements that can be produced by the system 10.
From the data defining the enhanced graphic
product, the computer 14 generates at least one
printing program for operating a printer 20 that
prepares one portion of the enhanced graphic product,
and a cutting program that operates a cutter 22 and
prepares the remaining portion of the product. Addi-
tional printing programs may also be generated, for
example, to prepare additional printed material in
different colors. Each program is stored in a memory
24, and when the product is to be produced, a
controller 26 reads the programs and operates the
printer 20 and cutter 22 respectively.
For example, to create the graphic image of
the letters "AR" in Fig. 3, the outline of the
letters and the shadow of the third dimension are
printed by the printer 20 on a sheet material, such
as a vinyl secured by a pressure sensitive adhesive
on a releasable backing material. One such vinyl is
sold by the Assignee of this application under the
trademark SCOTCHCAL of 3M Company. The printer
prints the outline of the letters and third dimension
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in black or another color contrasting with the basic
color or colors of the vinyl material. The printed
sheet of vinyl on the releasable backing material is
then mounted in the cutter 22 and the controller 26
cuts the vinyl only along the peripheral edges C of
the image and any internal edges in accordance with
the cutting program in the memory 24.
By utilizing a printing program and cutting
program which have a common data base for defining
both the peripheral edges to be cut as well as the
printed material, the printing and cutting operations
on the sheet of vinyl material are coordinated.
After weeding to remove unwanted vinyl material
within or around the image, the vinyl forming the
enhanced graphic image is lifted from the underlying
backing material and is attached to a sign board,
window or other object.
It is generally preferable, but not
essential, to carry out the printing operation in the
printer 20 before the sheet material is cut by the
cutter 22. With a separate printer and cutter it is
also essential that the graphic image that is printed
on the vinyl be registered in the cutter with the
printing program origin and the cutting program
origin coincident. In this manner the lines of cut
and the printed portion of the image maintain the
14
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correspondence established by the common data base.
This registration can be accomplished by printing an
origin point on t~e vinyl along with the printed
portion of the image and then optically aligning the
origin point with a reference position for the
material in the cutter 22. If the printing and
cutting operations are carried out by a single
machine or a machine having a common drive mechanism
for positioning the vinyl relative to a printing head
and a cutting head, then the origin point or other
reference can be eliminated.
A unique printing apparatus for carrying
out the printing operation is described in further
detail below. A suitable cutting apparatus for
carrying out the cutting operation on sheets of vinyl
or other material is described in the above-
referenced U.S. Patents 4,467,525; 4,799,172 and
4,834,276, all owned by the Assignee of the present
application.
One embodiment of a printer for
accomplishing the printing operation disclosed in
Fig. l is illustrated in Fig. 4. The printer 40
utilizes a set of sprockets to engage corresponding
feed holes extending along each longitudinal edge of
a strip S of the sheet material from which the
graphic product is prepared, and correspondingly the
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cutter 22 has a set of sprockets to engage the same
series of feed holes during the cutting operation.
In this manner th~ registration of the cut edges of
the graphic with the printed image is insured in the
longitudinal direction. Since the graphic image is
absolutely fixed both transversely and longitudinally
on the strip S relative to the feed holes, the feed
holes become a proper reference for the image in both
the printing and cutting operations.
Alternatively, the printer can prepare a
positional reference track T on the print-receiving
surface of the sheet material to establish a known
positional relationship between the printed image on
the strip S and the strip itself. The cutting
operation is then carried out by the cutter after the
printing operation, and the cutter reads the
positional reference track on the sheet material in
order to coordinate the position of the material and
the cutting tool with the printed material.
As shown in Fig. 4 the strip S is supplied
in a roll which is supported on a platform 42 at the
back side of the printer and is fed over a guide
roller 44 before it enters the housing 46 of the
printer. After the strip passes through the printer
where the printing operation takes place, it is dis-
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charged freely at the front side of the machine or
may be retrieved on a take-up reel if desired.
Although the printer 40 is connected for
controlling the printing operation to the controller
26 in Fig. 1, the printer includes a control panel 48
on the housing 46 to stop and start printing
operations. Additionally the control panel 48
includes controls for slewing the strip S
independently of the printing operation and other
controls for operating the printer as will become
more apparent hereafter.
The upper portion of the printer 40 has a
cover 50 with a handle 52 that can be opened and
closed in order to expose the internal structure of
the printer as shown more particularly in Figs. 5-10.
Within the printer 40, the strip S passes
over a roller platen 58 relative to a thermal print
head 60 which is pressed downwardly onto the strip of
material and generally establishes a linear zone of
contact between the material and the platen. In one
embodiment the strip of vinyl sheet material is 15"
wide and a hard rubber sleeve on the roller platen as
well as the print head are approximately 12" wide.
Thus a marginal edge portion of the strip overlaps
the rubber sleeve 59 of the roller platen at each end
as indicated in Fig. 8. A drive sprocket 62, having
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a set of sprocket pins engages a series of feed holes
along the one marginal edge of the strip S, and a
similar drive spr$cket 64 having sprocket pins
engages a series of feed holes along the opposite
marginal edge of the strip. For a more complete
description of the series of feed holes and drive
sprockets reference may be had to U.S. Patent
4,834,276 mentioned above.
As shown in Figs. 6 and 8, the drive
sprockets 62,64 are fixedly mounted to a drive shaft
66. The drive shaft is rotatably mounted within the
housing 46 of the printer and is driven from a step
motor 70 by a series of drive gears 72,74, toothed
drive pulleys 76,78 and a toothed drive belt 80. In
addition the roller platen 58 which is also rotatably
mounted within the housing 46 is driven from the
drive shaft 66 by means of drive pulleys 82,84 and an
O-ring drive belt 86 at one end of the platen and
drive pulleys 88,90 and an 0-ring drive belt 92 at
the opposite end of the platen. The gears, pulleys
and toothed drive belt 80 ensure that the strip S of
sheet material is precisely positioned on the roller
platen and control the speed at which the strip S
moves through the printer. The drive pulleys 82,84,
88,90 are selected to establish a peripheral speed of
the roller platen 58 that is slightly higher than the
18
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peripheral speed of the drive sprocket 62 and 64 to
augment the feeding of the strip S past the print
head 60. Since th,e drive sprockets positively engage
the strip and control the speed of the strip, the O-
ring drive belts 86,92 must allow limited slip.
As shown most clearly in Fig. 6 a pair of
curved, sheet metal plates 94,96 guide the strip S of
sheet material circumaxially onto and off of the
roller platen 58 and the cylindrical surfaces of the
sprockets 62,64 in a U-shaped feed path. The
cylindrical surfaces of the sprockets lie in a
cylindrical plane which is much larger in diameter
than the cylindrical, strip-engaging surface of the
roller platen 58 and is tangential to the cylindrical
surface. Preferably the cylindrical surface of the
platen is formed by a hard rubber sleeve which
improves the frictional engagement of the platen with
the releasable backing material of the strip.
To keep the strip S fully engaged with
approximately 180~ of the sprockets 62,64, a pair of
holddown bails 98 straddle the pins of each sprocket.
The bails are pivotally suspended from the housing 46
on pins 100 as indicated in Fig. 9 so that the bails
can be lifted away from the sprockets and allow a
strip of sheet material to be mounted on and removed
from the sprockets and roller platen 58. Over-center
19
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springs 102 assist in holding the bails downwardly on
the strip and also permit lifting the bails away from
the sprockets dur~ng installation or removal of a
strip. In addition a pair of holddown rollers
104,106 in Fig. 6 extend between the bails 98 at the
supply and discharge points from the roller platen.
Thus, the series of feed holes along each edge of the
strip S are threaded onto the sprockets 62 and 64 by
lifting the bails, and are held firmly engaged with
the sprockets and the roller platen by lowering the
bails.
The thermal print head 60 is mounted in an
upper support frame 110 that is pivotally mounted on
an axle 112 at the back side of the housing 46 as
shown in Figs. 5, 6 and 9. In Fig. 9 the support
frame is shown in phantom at a partially elevated po-
sition. The actual suspension of the thermal print
head 60 from the support frame 110 is illustrated in
detail in Fig. 7. A suspension plate 114 is
connected with the frame 110 by means of a series of
bolts 116 which are secured to the plate 114 and
slideably received within the frame 110 so that the
plate 114 together with the print head 60 can move
vertically in Fig. 7 relative to the support frame.
Sur-rounding each of the sliding bolts 116 and
interposed between the frame 110 and plate 114 is a
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coil spring 117 which applies pressure downwardly to
the plate I14 and presses the print head 60 against
the strip S of sh$et material and the roller platen
58 along a line of contact. The print head 60 has a
plurality of heating elements distributed evenly
along the head from one end of the roller platen 58
to the other, and the heating elements are densely
packed along the line of contact preferably with a
density of 300 elements per inch. One such a head is
made by Kyocera Industrial Ceramics, Inc. of
Kyoto, Japan.
In addition to supporting the thermal print
head 60, the mounting plate 114 also serves as a heat
sink for the heat generated in the print head and
supports a pair of dancer rolls 118,120 which guide a
web or foil W over the head. The web bears a heat
sensitive printing ink or printing dye in black,
white or other colors on the surface of the web
facing the strip S of sheet material.
The web W bearing the printing ink is
interposed between the print head 60 and the strip S
of sheet material, and when the heating elements of
the head 60 are selectively energized, the portion of
the ink immediately under a heating element is
released from the web and transferred to the sheet
material. With high density heating elements,
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graphic images of high resolution are thus created on
the strip of sheet material. The excitation of the
heating elements ~s, of course, controlled in
accordance with the program of printed material that
is read by the controller 26 from memory 24 in Fig.
1.
The web W of printing ink has a width
substantially equal to that of the print head and is
moved synchronously with the strip of sheet material
relative to the head by virtue of the pressure
applied between the print head and the roller platen
58. As the web W moves, a pair of static suppression
brushes 122,124 mounted in the plate 114 wipe the
side of the web opposite from the printing ink. With
lS the drive sprockets 62 and 64 having a larger
diameter than the roller platen 58, the roller platen
defines a relatively thin line of contact with the
strip S of sheet material and yet the sprockets can
engage an inverted U-shaped segment of the strip
which is substantially larger than the segment
contacting the hard rubber sleeve of the roller
platen. This allows a narrow linear zone of high
pressure contact to be made by the strip with the
printing head while a dispersed area of contact with
the strip is provided for driving the strip.
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In order to regulate the amount of pressure
applied to the web W and strip S by the head and the
roller platen, th~e projecting or cantilevered end of
the support frame 110 is moved up and down relative
to the platen 58 by a pressure regulating mechanism
that is adjusted by the controller 26. The pressure
regulating mechanism includes one or more cams 130
shown in Fig. 5 which are rotatably mounted in the
housing 46 on a shaft 132. The cam 130 includes a
spiral cam slot 134 that is engaged by a cam follower
136 connected to the projecting end of the support
frame 110. As the cam 130 is rotated by means of the
pressure regulating step motor 138, the cam follower
together with the support frame 110 move up and down
and the pressure applied to the web W and strip S of
sheet material between the print head 60 and roller
platen 58 is adjusted through the coil springs 117
(Fig. 7). By controlling the rotation of the cam 130
with the step motor 138, a precise pressure setting
can be obtained since the displacement of the support
frame is directly proportional to the pressure.
The spiral cam slot 134 includes an exit
point 140 at the periphery of the cam 130 so that the
cam follower and correspondingly the support frame
110 can be lifted completely free of the cam when the
cam has rotated to the upright position. The
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controller 26 may thus regulate the position of the
cam to permit or prevent the lifting of the support
frame 110 and prinrt head 60 at appropriate times in a
printing operation.
The pressure regulating mechanism can also
be utilized to lift the pressure head out of contact
with the strip S and roller platen since the spiral
cam slot 134 is comprised by a groove that can both
push and pull the cantilevered end of the support
frame 110 up and down. Thus, for example, at the end
of a printing operation the regulating motor 138 can
drive the cam 130 to a position at which there is
zero pressure between the print head and the roller
platen or the print head can actually be lifted away
from the roller platen so that the strip S of sheet
material can be slewed back and forth relative to the
print head without making contact with the web W of
printing ink.
The lifting feature of the pressure
regulating mechanism is desirable when, for example,
multiple colors are printed on the strip S of sheet
material in multiple passes of the material over the
roller platen relative to the head. Between each
pass the web W must be changed or indexed so that
printing inks of different colors can be transferred
from different webs or different portions of one web
24
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onto the same segments of the strip S in overlapping,
side-by-side or spaced relationship. The ability to
overlap the colors is particularly useful when
subtractive inks or color process dyes are employed
to mix the colors and obtain still further colors.
The pressure regulating step motor 138 may
also be adjusted by the controller 26 of Fig. 1 in
accordance with other printing parameters of the
operation. For example, the texture or character of
the printing-receiving surface on the strip S of
sheet material may require setting the pressure at a
preferred level for ideal transfer of the ink between
the web W and the strip S. Other parameters that may
effect the desired pressure level include the speed
at which the printing operation is carried out, the
character or color of the printing ink that is
transferred from the web W and the intensity or tone
of the printed material desired on the strip. The
adjustment of the pressure level can occur prior to
or throughout the printing operation in accordance
with print characteristics that are stored in the
print program or are measured during the printing
operation.
Since the strip S of sheet material may be
slewed back and forth between opposite sides of the
roller platen 58 and operation of the head without
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material on the platen can cause serious damage to
the head or platen, it is desirable to be able to
detect the absence of the strip at each side. For
example, if the trailing end of the strip S passed
S over the roller platen in the course of a printing
operation, the web of printing ink would be caused to
make direct contact with the roller platen and the
ink together with the heat from the printing head may
actually cause damage to the head. Correspondingly,
if the strip S is slewed backwards to begin a second
printing operation on the same segment of the strip
with, for example, an ink of a different color, the
leading end of the strip may pass beyond the roller
platen and again the web W and printing head may be
pressed directly against the cylindrical surface of
the roller platen. Accordingly a strip detector 150
shown in Figs. 6 and 7 is provided at both the input
and discharge sides of the roller platen to detect
the absence of the strip at each location.
The detector 150 includes a first detector
arm 152 that is pivotally mounted on a plate 154 at
the input side the roller platen, and a second
detector arm 156 pivotally mounted to the plate at
the discharge side of the roller platen. The upper
ends of the arms project into the feed path of the
strip S through slots in the guide plates 94 and 96
26
CA 022402S4 1998-08-11
respectively. Thus when the web is present at the
input side the detector arm 152 is depressed and
assumes the solid~line position illustrated in Fig.
7, and when the web is present at the discharge side
S the detector arm lS6 is depressed and assumes the
solid line position. In the solid line positions of
the arms 152 and 156, the depending ends of the arms
are drawn out of contact with an actuating switch 160
which may be a microswitch. However, when the strip
S is not present at the input side, the detecting arm
152 is rotated inwardly at the bottom by the
retracting spring 162 to the phantom position, and
the switch 160 is actuated to signal the absence or
an error in the positioning of the strip S.
lS Correspondingly when the web is not present at the
discharge side of the roller platen 58, the
retracting spring 164 draws the arm 156 inwardly to
the phantom position, and correspondingly actuates
the switch 160. Thus it is possible to detect the
absence of the web at either side of the roller
platen and send a warning signal to the controller 26
of Fig. 1 through the single switch 160.
As mentioned above the web W bearing the
printing ink that is transferred by the printing head
60 is moved with the strip S relative to the printing
head during a printing operation and the ink is
CA 022402~4 1998-08-11
transferred from the web onto the sheet material. As
a consequence the web is a donor web that is expended
normally after a single use and therefore must be
periodically replaced. Furthermore, the webs
generally include a transfer ink of a single color,
and in order to print graphic images in multiple
colors, it is necessary to run the printing operation
one or more times with different webs and printing
inks. For this reason the preferred embodiment of
the invention incorporates a web that is supported in
a replaceable cassette 170 shown in the installed
position in Figs. 5, 6, 9 and 10. The cassette 170
is held in an operative position within the support
frame 110 by means of a pair of oppositely disposed
mounting pins 172 (only one visible) and by blocks
174,176 which establish a reference plane within the
frame 110. The cassette is easily installed and
removed from the frame when the frame is lifted to a
fully open position.
The cassette 170 by itself is shown more
clearly in Figs. 13-16 and includes two molded side
rails 180,182 and two end shells 184,186. This
construction provides the cassette with a generally
rectangular configuration and the central portion of
the rectangle between the side rails 180 and 182 de-
fines an opening through which the printing head 60
28
CA 022402S4 1998-08-11
and support plate 114 may pass in order to press a
donor web mounted in the cassette onto the roller
platen as shown, ,for example, in Fig. 9. One end of
the donor web W is mounted on a spool 190 enclosed
within the end shell 184 and the other end is mounted
on a spool 192 enclosed by the end shell 186.
At each axial end the spool 190 is
supported loosely within a pair of aligned holes at
one side of the side rails 180 and 182 respectively,
and correspondingly the spool 192 is loosely
supported at its axial ends within another pair of
aligned holes at the other end of the side rails
180,182. The loose mounting of the spools in the
side rails allows each of the spools limited freedom
of movement in the radial direction relative to the
common axis that connects the aligned holes in the
side rails. Additionally, as shown most clearly in
Fig. 16 each spool 190,192 includes at least one
axial end a set of teeth projecting radially outward
while the side rail at the same end of the spool
includes another set of teeth projecting radially
inward. The limited movement of the spools in the
radial direction allows the teeth on the spool and
the side rails to become engaged which thereby
inhibits spool rotation and prevents the web of
material from unraveling when the cassette 170 is
CA 022402~4 1998-08-11
removed from the thermal printer. When the cassette
170 is mounted in the printer, each of the spools is
held in alignmentrwith the common axis and with the
teeth disengaged as explained further below. Thus
the spools are permitted to rotate freely under the
control of the printer.
When the cassette is mounted in the support
frame 110 as shown in Fig. 11, one axial end of the
spool 190, which is the supply spool, is mounted on a
rotatable axle 194, which centers the spool within
the mounting hole in the cassette and is coupled to
the axle by means of a cross pin 196 that is received
within slots 198 of the spool. The end of the axle
opposite from the cross pin 196 is coupled to a slip
clutch or drag brake 200 to impose frictional
restraint on the supply spool as the donor web W is
pulled off of the spool. The opposite end of the
spool 190 is captured on a non-rotatable axle 202 to
center the spool within the mounting hole of the
cassette. The axle 202 is also movable axially of
itself and is biased into engagement with the spool
190 by means of a compression spring 204. Thus by
depressing a release lever 203 and retracting the
axle 202, the spool 190 is released from the mounting
frame 110.
CA 022402~4 1998-08-11
The spool 192 is considered the take-up
spool and takes up the consumed portion of a donor
web in the course,of a printing operation. As shown
in Fig. 12, the one end of the take-up spool 192 is
mounted on a rotatable axle 210 which centers the
spool and is drivingly engaged with the axle by means
of the cross pin 212. The axle 210 is connected
through a set of gears 214,216 and a slip clutch 218
to a drive motor 220. Thus, when the drive motor is
engaged it applies a torque which is limited by the
slip clutch 218 to the take-up spool 192 and thus
produces a uniform tension force on the donor web W.
The drive motor 220 is engaged only during a printing
operation and the force applied to the donor web is
so limited by the slip clutch 218 that the actual
movement of the web is controlled by the movement of
the rotatable platen 58. Thus the web W and the
strip S of sheet material which are pressed between
the print head 60 and the roller platen 58 move
synchronously relative to the printing head during a
printing operation. When the pressure between the
print head and roller platen is released, for
example, during slewing of the strip S, the drive
motor 220 is de-energized and the web W does not move
and is not consumed.
CA 022402~4 1998-08-11
The end of the take-up spool 192 opposite
from the drive motor 220 is mounted and centered on a
non-rotatable andraxially retractable axle 224 with a
release lever 223 in the same manner as the spool
190. The axle 224 is pressed into engagement with
the spool by the compression spring 226.
It should be understood that with the
spools 190 and 192 positioned loosely within the
cassette 170, and the frame or casing of the cassette
held in the printer by means of the registration pins
172 and reference blocks 174,176 as shown in Fig. 9,
the positioning of the spools and correspondingly the
donor web W is controlled within the printer by axles
194,202,
210 and 224 while the position of the casing is con-
trolled independently by the registration pins 172
and the reference blocks 174,176. However, when the
casing and the spools are mounted, the spools are
free to rotate within the enlarged holes of the
cassette without interference from the locking teeth.
As shown in Fig. 11, an optical encoding
disk 230 is coupled to the rotatable axle 194 that
engages the supply spool 190. An optical reader 232
is mounted on the support frame 110 immediately
adjacent the encoding disk 230 so that the rotation
of the axle as well as the supply spool can be
CA 022402~4 1998-08-11
detected during a printing operation. The reader 232
produces a signal indicating that the donor web W is
in motion as it spould be during the operation. If
the signal indicates no movement when there should be
S movement, such a signal means that the supply spool
190 is empty or that the donor web W alone or
together with the strip S of sheet material is jammed
and not moving properly past the print head 60. In
either event the lack of movement indicates a fault
of the printing operation and the controller 26 which
receives the signal from the reader 232 stops the
printer and issues a fault signal.
As indicated above, a printing operation
may be carried out to produce printed material in
various colors, and generally the entire printing and
cutting operation for making a sign or other graphic
product is pre-programmed, not only with respect to
the design and arrangement of the printed matter
within the peripheries of the graphic product, but
also the colors of the print and the sheet material
on which the print is placed. Accordingly, in order
to carry out a printing operation properly, the
operator of the printer must install both the strip
of sheet material and a cassette that is called for
by the program.
33
CA 022402~4 1998-08-11
Additionally, the materials on which the
printing takes place as well as the donor webs used
in the printing p~ocess may have different printing
characteristics beyond just color which render the
materials incompatible or the resulting product
inferior unless the printer is controlled and
adjusted properly to compensate for the different
characteristics. For example, the pressure applied
between the donor web and strip of sheet material may
need to be adjusted up or down in accordance with the
donor web that is being used in a printing operation.
Also the speed at which the printing operation is
carried out may affect the pressure and vice versa.
Furthermore, the excitation of elements in the
printing head may need to be modified in accordance
with the thermal characteristics of the ink or the
speed and the pressure with which the printing oper-
ation is carried out. In sum there are a number of
variables that require adjustment either prior to or
during the printing operation in order to produce a
satisfactory graphic product.
For the reasons given above, the controller
26 of Fig. l shown in greater detail in Fig. 17 has a
microprocessor 250 which regulates the operation of
the printer 40 to set and adjust various of the
operating parameters in a printing operation. The
34
CA 022402~4 l998-08-ll
microprocessor responds to a number of inputs in-
cluding the keyboard 252, the printing and cutting
program derived f~om the memory 24 and a code reader
254 which detects printing characteristics of the web
S W and printing ink in the cassette 170. From these
various inputs, the microprocessor regulates the
pressure applied between the printing head 60 and
roller platen 58 through the pressure control means
256 including the drive motor 138 and controlling cam
130 of Fig. 5, the speed of printing through the feed
driver 258 which regulates the step motor 70 for the
roller platen 58 in Fig. 6 and the image intensity
through a print head drive 260 which controls the
excitation of the heating elements in the print head
15 60. The setting of the various parameters and
regulation during a printing operation is
accomplished in conjunction with the display 262. In
the event of a fault of the system, any error or
detected fault is identified through the display 262
on the printer and if the fault is serious, the
microprocessor immediately stops or inhibits printer
operation.
Since the donor web W is a significant
variable in a printing operation and may be installed
and replaced from time to time throughout a given
operation in order to change the colors or other
CA 022402~4 1998 - 08 -11
printing characteristics, a code label 270 bearing an
identifying code is secured to the end shell 186 of
the 45 cassette 170 adjacent the take-up reel 192 as
shown in Figs. 9, 10 and 13. The code label bears a
code that identifies the color, thermal transfer and
other distinctive printing characteristics of the
donor web within the cassette. The printer includes
the code reader or sensor 254 shown in Figs. 9 and 10
for reading the code from the label 270 as the
support frame 110 and the cassette 170 are moved by
the pressure regulating means downwardly into an
operative position in which the web and sheet
material are pressed against the roller platen 58.
Fig. 9 illustrates the relative positioning of the
code label 270 and the code reader 254 immediately
prior to a code reading operation, and Fig. 10
illustrates the relative positioning of the label 270
and reader 254 immediately after the reading
operation. It is clear from the change in the
relative positions that the code label 270 is swept
past the reader 254 to read the identifying code on
the label.
The mechanism that allows the identifying
code to be swept includes the pressure regulating
mechanism that pulls the support frame 110 and
cassette 170 downwardly into the operative position
36
CA 022402~4 1998-08-ll
and a slide plate 274 that is bolted to the pro-
jecting end of the support frame 110 for sliding
movement on the fr~ame relative to the code label 270.
The slide plate 274 positions the code reader 254
within a slot 276 in the end of the frame 110
directly opposite the code label 270 and includes an
operating tang 278 which butts against an adjustable
seat 280 on the housing 46 as the movable support
frame 110 is lowered. A tension spring 282 connected
at its upper end to the slide plate 274 and at its
lower end to the frame 110 normally biases the plate
274 downwardly to the position illustrated in Fig. 9.
However, when the tang abuts the seat 280 as shown in
Fig. 10 and the support frame 110 continues its down-
ward movement, the slide plate 274 moves upward
relative to the frame 110 in opposition to the spring
tension. During sliding movement of the plate the
code reader 254 scans the code on the label 270 and
transmits the read code back to the microprocessor
250 in Fig. 17.
The code reader 2~4 may be a magnetic,
mechanical or other type of sensor but in the
preferred embodiment the sensor is an optical sensor
and the code on the label 270 iS a compatible
optically read code. One such code which is
particularly suitable for the printer application is
CA 022402~4 1998-08-11
disclosed in Fig. 18 and includes a series of
rectangular marks or bars that are located in at
least one data tra~ck and one clocking track extending
in the reading direction indicated by the arrow A.
The outer tracks 290,292 in the illustrated
embodiment are data tracks which are each divided
into a series of data blocks, six blocks being
illustrated in this embodiment. Each block repre-
sents a data bit and may be light or dark
representing a "0" or a "1". Thus, for example, the
data track 290 read in the direction of the arrow A
would represent the binary number 100111.
Correspondingly, the data track 292 would represent
the binary number 001000. Both numbers may be
components of a single number, and therefore, a total
of 212 or 4096 different codes can be derived from
the two data tracks in combination.
The track 294 is a clocking track which
controls the reading of the data tracks. The
clocking track consists of a series of clocking marks
which are read in the direction of the arrow A
simultaneously with the two data tracks by a three
head optical reader. The clocking track synchronizes
the optical reading of the data blocks with the
positioning of those blocks in front of an optical
head within the reader 254. It will be noted, for
CA 022402~4 1998-08-11
example, that the clocking marks have the same di-
mensions as the data blocks but are offset from the
data blocks by a ~alf cycle in the reading direction.
In reading the c~ocking marks, the transitions
between light and dark values occur at the midpoint
of the data blocks and by triggering the optical
heads for the data blocks at the transitions, a clear
and unambiguous reading of the data is taken.
It should be understood that the use of the
clocking track in the code label renders the code
reading process independent of any time clock within
the microprocessor and independent of the speed with
which the support frame 110 is moved downwardly into
the operative position.
Additionally, the two data tracks 290,292
are located on opposite sides of the clocking track
294 to minimize any errors '_hat may arise due to the
mounting of the bar code label 270 at a slight angle
to the direction of reading the code. Thus, the bar
code illustrated in Fig. 18 is particularly useful
for identifying donor webs bearing a transferrable
printing ink that is used in thermal printers.
While the present invention has been
described in a preferred embodiment, it should be
understood that numerous modifications and
substitutions can be had without departing from the
39
CA 022402~4 1998-08-11
spirit of the invention. For example, it is clear
that the novel printing and cutting apparatus may be
carried out by a number of different printing and
cutting machines. The use of the common sprocket
drive means in the printer and cutter ensures
coordination between the printed and cut subject
matter; however, other indicia including a timing
track printed on the strip of sheet material to be
printed upon may also be used for the same
coordination. While a separate printer and cutter
have been disclosed, it is contemplated that a single
machine having interchangeable heads or both printing
and cutting heads might be used to carry out the two
functions. Wipers for cleaning the strip of sheet
material before printing can also be provided. The
thermal printer disclosed has a stationary printing
head that extends parallel to the width of the strip
of material on which the printing takes place;
however, other types of printers including those with
movable heads can also be employed. The control
means disclosed regulates a number of the printing
operations including the pressure applied by the
printing head to the donor web and strip of sheet
material resting on the printing platen. A number of
the controls may be eliminated by selecting nominal
values for the regulated parameters although the
CA 022402~4 1998-08-11
number of printing tasks that can be accomplished
without such controls may be more limited. The
coding employed tQ identify the type and
characteristics of the donor web is advantageously
applied to a cassette containing the web for scanning
as the web moves into its operative position. Such
coding, however, may take other forms and may be
scanned by other techniques to accomplish the same or
other control functions. Accordingly, the present
invention has been described in several preferred
embodiments by way of illustration rather than
limitation.
41
