Appeal No. 1999-2851
Application No. 09/127,347
BACKGROUND
The appellant's invention relates to an apparatus for printing graphic images on
sheet material having an ink web cassette with constant web tension. An understanding of
the invention can be derived from a reading of exemplary claim 1, which is reproduced
below.
1. A cassette for a thermal-transfer printing apparatus having a strip of
sheet material for receiving the graphic images, wherein the sheet material
defines a plurality of feed holes spaced relative to each other in opposed
marginal portions thereof; a platen mounted adjacent to the sheet material
for supporting the sheet material; a print head movable into engagement with
an ink web of the cassette and sheet material along a line of contact
extending in a lateral direction of the sheet for transferring printing ink from
the ink web onto the sheet and printing the graphic images on the sheet; a
take-up motor for driving the ink web of the cassette; a substantially
constant-torque clutch drivingly connected to the take-up motor for
generating a substantially constant motor torque; two sprockets rotatably
mounted on opposite ends of the platen relative to each other, and engaging
the feed holes of the sheet material upon passage between the platen and
print head; a drive motor drivingly connected to at least one of the platen and
sprockets for rotatably driving at least one of the platen and sprockets and
moving the sheet material engaged by the platen and sprockets; and a
controller electrically coupled to the drive motor and print head, wherein the
controller tracks the rotational position of at least one sprocket to register the
print head with the sheet material, and actuates the print head based on the
rotational position of the at least one sprocket for printing the graphic
images on the sheet material; wherein the cassette comprises:
a predetermined length of ink web; a supply spool mounted within the
cassette and carrying the ink web, wherein the supply spool is releasably
connectable to the thermal-transfer printing apparatus with the ink web
interposed between the sheet material and print head for transferring printing
ink from the ink web onto the sheet and printing the graphic images on the
sheet; a take-up spool mounted within the cassette and connected to the ink
2
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