EP0035875A2
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EP
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Pixel magnification/demagnification apparatus and method
Assignee: Xerox Corp
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Filing: 1981-03-05
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Granted: —
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Expires: 2001-03-05
Abstract
Abstract Pixel magnification/demagnification apparatus and method are disclosed for controlling the size of reproducible image, the image being represented by video image signals or pixels generated by a raster scanner (12). A binary rate multiplier (102) is used for image size control along the X-axis, the multiplier being programmed to the size image desired to vary the frequency of the pixel clock signals output by the multiplier. A control flip-flop (45) astride the image pixel stream is driven by the multiplier clock signals to speed up or reduce the rate at which image pixels are output with consequent change in image size along the X-axis. …<??>For image size control along the Y-axis, a phase lock loop (86) control with programmable frequency generator (82) is provided for the scanning carriage drive motor (39). The frequency output of the generator is settable to the image size desired, changes in image size along the Y-axis being achieved either by increasing or decreasing the rate at which the scanning carriage (32) is moved.
Inventors
- 👤 Peter A. Crean
- 👤 Martin A. Agulnek
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-04 20:33
CPC Classifications
G; G03; G03G; G03G15/00; G03G15/04; G03G15/041; G06; G06T; G06T3/00; G06T3/40; H; H04; H04N; H04N1/00; H04N1/387; H04N1/393; H04N1/3935
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
178 words
Pixel magnification/demagnification apparatus for controlling the size of the image producible by pixels derived by raster scanning image bearing documents, characterized by: a pixel control gate (45) through which said pixels pass; clock means (42) for generating pixel clock pulses at a maximum frequency representing maximum image size along a first axis, said pixel clock pulses being output to said control gate to control enablement of said control gate; a fractional multiplier (102) for selectively reducing the frequency of said pixel clock pulses from said maximum to a minimum frequency representing minimum image size along said first axis; first control means (101) for varying the multiplication ratio of said multiplier between said maximum and minimum frequencies to thereby vary the frequency of the pixel clock signals to said control gate and accordingly the rate at which pixels pass through said control gate; and second control means (82) for varying the speed at which documents are raster scanned to thereby vary the rate at which pixels are produced and accordingly the size of the image along a second axis.
Claim 2
Dependent Claim
178 words
Pixel magnification/demagnification apparatus for controlling the size of the image producible by pixels derived by raster scanning image bearing documents, characterized by: a pixel control gate (45) through which said pixels pass; clock means (42) for generating pixel clock pulses at a maximum frequency representing maximum image size along a first axis, said pixel clock pulses being output to said control gate to control enablement of said control gate; a fractional multiplier (102) for selectively reducing the frequency of said pixel clock pulses from said maximum to a minimum frequency representing minimum image size along said first axis; first control means (101) for varying the multiplication ratio of said multiplier between said maximum and minimum frequencies to thereby vary the frequency of the pixel clock signals to said control gate and accordingly the rate at which pixels pass through said control gate; and second control means (82) for varying the speed at which documents are raster scanned to thereby vary the rate at which pixels are produced and accordingly the size of the image along a second axis.
Claim 3
Dependent Claim
43 words
Apparatus according to Claim 1 in which the maximum frequency of said pixel clock pulses output by said clock means is at least twice the frequency at which said pixels are produced to double the size of the image along said first axis.
Claim 4
Dependent Claim
116 words
Apparatus according to Claim 1 including: a movable scan carriage (32), at least one scanning array (40) on said carriage for scanning said original image, and drive means (37, 39) for driving said scan carriage to enable said array to scan said original image; said second control means including: a frequency generator (82) adjustable between a frequency representing maximum image size and frequency representing minimum image size along said second axis; and phase lock loop means (86) for controlling the speed of said drive means in response to the frequency output of said generator whereby to drive said scan carriage at a scanning speed corresponding to the size of the image desired along said second axis.
Claim 5
Dependent Claim
118 words
A pixel magnification/demagnification method to control the size of the image producible by image pixels, characterized by the steps of: controlling the speed at which an image bearing document is scanned to produce image pixels at a rate which provides an image of selected size along a first axis; clocking the image pixels with a pixel clock; generating new pixel clock pulses at a maximum frequency corresponding to the maximum image size along a second axis; selectively reducing the frequency of the new pixel clock pulses to thereby reduce the size of the image producible by the image pixels along said second axis to a selected size; and clocking the image pixels with said new pixel clock pulses.
Claim 6
Dependent Claim
118 words
A pixel magnification/demagnification method to control the size of the image producible by image pixels, characterized by the steps of: controlling the speed at which an image bearing document is scanned to produce image pixels at a rate which provides an image of selected size along a first axis; clocking the image pixels with a pixel clock; generating new pixel clock pulses at a maximum frequency corresponding to the maximum image size along a second axis; selectively reducing the frequency of the new pixel clock pulses to thereby reduce the size of the image producible by the image pixels along said second axis to a selected size; and clocking the image pixels with said new pixel clock pulses.
Claim 7
Dependent Claim
72 words
A method according to Claim 4 further characterised by the steps of: controlling the operating speed of a scanning drive motor in response to signal frequency to control the speed at which a document is scanned and therefore the size of the image along said first axis; and generating various frequencies for use in controlling the operating speed of said motor and therefore the size of the image along said first axis.
References Cited (Backward Citations)
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