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US 5,327,524 AGranted
Electrophotographic recording with multiple-bit grey level LED printhead with enhanced addressability
AssigneeEastman Kodak Company
InventorYee S. Ng
Life of this patent
Estimating the term…
Abstract
A recording apparatus and method wherein a plurality of LEDs record pixel information on an electrophotographic recording medium. The LEDs are driven by a grey level driver to control the size of each pixel. The location of a pixel is controlled during a main line recording period to shift the pixel's centroid or center. Where a pixel is located at an edge or border of a text-like structure and its centroid is shifted to reduce edge raggedness, an exposure duration of the LED is increased to compensate for overlap with pixels that are within the text-like structure.
Claims22
A non-impact printer apparatus comprising:
- an electrophotoconductive recording medium;
- means including a plurality of recording elements for cooperating with said medium to produce a modulated electrostatic charge on said medium representing an image to be recorded;
- driving means, responsive to an enablement signal, for driving the recording elements for recording the image;
- control means for controlling enablement times of the driving means for driving the recording elements during a main line pixel recording period for recording a line of pixels by said plural recording elements, said control means including:
- (a) register means associated with each recording element for storing a respective first multibit data signal representing a recording duration for recording a pixel by a respective recording element during one of plural sub-line recording periods comprising said main line period,
- (b) counter means for generating during each sub-line period a series of signals representing a time-changing count during a count cycle, the count recycling to establish plural pixel recording periods during said main line recording period, and
- (c) comparator means for comparing a second multibit signal with a signal representing a particular sub-line period and for comparing the first multibit data signal with said count to enable the driving means during the particular sub-line period for a time related to said first multibit data signal;
- and wherein the counter means during each sub-line period is in a count-down mode and count-up mode.
5 more elements
A method for recording which comprises:
- selectively energizing a plurality of recording elements arranged relative to a recording medium to produce on said medium an image to be recorded;
- controlling enablement times of the recording elements during a main line pixel recording period for recording a line of pixels by said plural recording elements, the step of controlling including the steps of:
- (a) storing a respective first multibit data signal representing a recording duration for recording a pixel by a respective recording element during one of plural sub-line recording periods comprising said main line period,
- (b) generating during each sub-line period a series of exposure clock signals representing a time-changing count during a count cycle, the count recycling to establish plural pixel recording periods during said main line recording period, each count cycle including a count-down mode and a count-up mode, and
- (c) comparing a second multibit signal with a signal representing a particular sub-line period and comparing the first multibit data signal with said count to enable a recording element during the particular sub-line period for a time related to said first multibit data signal.
2 more elements
The method of claim 8 and wherein the centroid is shifted for a pixel bordering an edge of a text-like structure.
A non-impact printer apparatus comprising:
- a recording medium;
- means including a plurality of selectively activatable recording elements for recording an image;
- driving means, responsive to an enablement signal, for driving the recording elements for recording the image;
- control means for controlling enablement times of the driving means for driving the recording elements during a main line pixel recording period for recording a line of pixels by said plural recording elements, said control means including:
- (a) register means associated with each recording element for storing a respective first multibit data signal representing a recording duration for recording a pixel by a respective recording element during one of plural sub-line recording periods comprising said main line period,
- (b) counter means for generating during each sub-line period a series of signals representing a time-changing count during a count cycle, the count recycling to establish plural pixel recording periods during said main line recording period, and
- (c) comparator means for comparing a second multibit signal with a signal representing a particular sub-line period and for comparing the first multibit data signal with said count to enable the driving means during the particular sub-line period for a time related to said first multibit data signal;
- and wherein the counter means during each sub-line period is in a count-down and count-up mode.
5 more elements
Dependencies are inferred from the claim text.