Appeal No. 2001-1420
Application No. 08/988,453
BACKGROUND
The invention is directed to method and apparatus that enables an optical write
device to write multi-tone images on a photosensitive member, such as photographic
paper. According to appellants, the relatively low-bit (e.g., six-bit) driver ICs, which set
the tone level of each pixel, that are used in the pertinent art cannot normally reproduce
high quality multi-tone images which require a larger number of bits for encoding tone
level. Appellants’ invention includes providing additional levels of tone level control by
modulating the pulse width or the pulse intensity of the signal produced by the driver IC.
Nine-bit data for the tone level of a particular pixel may be converted into three sets of
six-bit data, allowing six-bit driver ICs to be used. Representative claims 1 and 12 are
reproduced below.
1. A method for driving an [sic] write device which writes an image based on
image data, the method comprising the step of:
dividing a time for formation of a pixel into a plurality of periods and
performing multi-tone level control based on the image data in each of the
periods, said multi-tone level including at least three levels.
12. The method for driving an [sic] write device, the method comprising the
steps of:
a first step of converting an n-bit image data for one pixel into a plurality of
sets of m-bit data, wherein m is larger than 1 but smaller than n;
a second step of modulating a write element based on a first set of data of
the plurality of sets; and
a third step of modulating the write element based on a second set of data
of the plurality of sets.
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