Patent CA1192601A successfully refreshed from Google Patents.
CA1192601A
Expired / Lapsed
CA
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Pulse width modulation greyscale system
Assignee: Xerox Corp
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Filing: 1982-06-01
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Granted: 1985-08-27
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Expires: 2002-06-01
Abstract
Abstract ABSTRACT The present invention is a one dimensional electronic halftone generating system having a source of digital data representative of pixel greyscale, a counter to store the digital data, and pulse producing logic responsive to the counter to activate a laser modulator in accordance with the digital data representative of each pixel. In particular, a six bit data word represents one of 64 greyscale states for a particular pixel. The pulse producing logic responds to the particular data word to produce a pulse of a given duration or width to drive the laser for a given time period. The duration of the pulse, representing one to 64 states for a given pixel, will produce a given discrete greyscale value for each pixel.
Inventors
- 👤 Louis D. Mailloux
- 👤 Brian L. Waldron
Bibliographic Details
Application Number
—
Jurisdiction
CA
Data Source
google_patents
Last Synchronized
2026-11-09 01:39
CPC Classifications
H; H04; H04N; H04N1/00; H04N1/40; H04N1/405; H04N1/4055; H04N1/4056; H04N1/407; H04N1/4076; H04N1/4078
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
69 words
Apparatus for the raster reproduction of halftone pictures comprising a source of digital data representative of pixel greyscale, a counter to store the digital data, a laser modulator, a clock generator to synchronize the laser modulator, a clock signal to initiate the operation of the counter, and pulse producing logic responsive to the counter to activate the laser modulator in accordance with the digital data representative of pixel greyscale.
Claim 2
Dependent Claim
69 words
Apparatus for the raster reproduction of halftone pictures comprising a source of digital data representative of pixel greyscale, a counter to store the digital data, a laser modulator, a clock generator to synchronize the laser modulator, a clock signal to initiate the operation of the counter, and pulse producing logic responsive to the counter to activate the laser modulator in accordance with the digital data representative of pixel greyscale.
Claim 3
Dependent Claim
24 words
The apparatus of Claim 1 wherein the digital data representa-tive of pixel greyscale is a data word manifesting one of several states of greyscale.
Claim 4
Dependent Claim
33 words
The apparatus of Claim 1 wherein the counter begins counting from the number representative of the greyscale and including means respon-sive to the count to provide a variable pulse to the laser modulator.
Claim 5
Dependent Claim
29 words
The apparatus of Claim 1 wherein the counter is a six bit counter and the digital data word is a six bit word manifesting one of 64 greyscale states.
Claim 6
Dependent Claim
34 words
The apparatus of Claim 1 including logic circuitry connected between the laser modulator and the counter and responsive to the counter signal, a sync signal, and a carrier signal to activate the laser modulator.
Claim 7
Dependent Claim
27 words
The apparatus of Claim 1 including a step wedge generator connected to the counter for providing a test document representative of each of the various greyscale values.
Claim 8
Dependent Claim
21 words
The apparatus of Claim 1 including a test switch for manually providing a greyscale value to the counter for test purposes.
Claim 9
Dependent Claim
122 words
In an electronic halftone screening method wherein sequentially generated pictorial signals are representative of a number of pixel positions in a plurality of scan lines to define an original image and wherein synchronously generated halftone screen signals are representative of halftone values for each pixel position in each scan line, the method of producing a halftone image including the steps of providing a digital word representative of the greyscale value for each pixel, storing the digital data word in a counter, activating the counter to produce a count representative of the value of the pixel greyscale, converting the count into a variable pulse width, and activating a modulator in response to the pulse width to provide a greyscale value for each pixel.
Claim 10
Dependent Claim
122 words
In an electronic halftone screening method wherein sequentially generated pictorial signals are representative of a number of pixel positions in a plurality of scan lines to define an original image and wherein synchronously generated halftone screen signals are representative of halftone values for each pixel position in each scan line, the method of producing a halftone image including the steps of providing a digital word representative of the greyscale value for each pixel, storing the digital data word in a counter, activating the counter to produce a count representative of the value of the pixel greyscale, converting the count into a variable pulse width, and activating a modulator in response to the pulse width to provide a greyscale value for each pixel.
Claim 11
Dependent Claim
73 words
A one dimensional method for the raster reproduction of halftone pictures having a plurality of pixels comprising the steps of providing a source of digital data representative of greyscale tone for each pixel, storing the digital data in a counter responding to the counter to reproduce a variable pulse activating a laser modulator in response to the variable pulse and producing a greyscale tone for each pixel in response to the laser modulator.
Claim 12
Dependent Claim
73 words
A one dimensional method for the raster reproduction of halftone pictures having a plurality of pixels comprising the steps of providing a source of digital data representative of greyscale tone for each pixel, storing the digital data in a counter responding to the counter to reproduce a variable pulse activating a laser modulator in response to the variable pulse and producing a greyscale tone for each pixel in response to the laser modulator.
Claim 13
Dependent Claim
20 words
The method of Claim 9 including the step of providing one of 64 states of greyscale tone for each pixel.
Claim 14
Dependent Claim
18 words
The method of Claim 9 including the step of counting from a number representative of the greyscale tone.
References Cited (Backward Citations)
No citation records indexed.
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