EP0062479A2
Expired / Lapsed
EP
⏱️ 0.0 years remaining
Raster scanner apparatus and method
Assignee: Xerox Corp
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Filing: 1982-03-30
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Granted: —
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Expires: 2002-03-30
Abstract
Abstract A raster scanner includes a scanning module (12) which comprises a linear scanning array, a scanning slit permitting the array to view a document image one line at a time, and document transport for transporting documents past the scanning slit. To accommodate the disparity between scanning rates and user data rates, a relatively small buffer (14) stores lines of pixels output by the array pending demand by an output device (16). Intermittent operation of the scanner in response to buffer pixel demands is effected through starting and stopping of the document transport. A control (15, 45) is provided to prevent uneven spacing of scan lines resulting from scanning stopped documents or documents in the process of being accelerated or decelerated to and from scanning speed by the document transport.
Inventors
- 👤 Matteson Ronald Grant
Bibliographic Details
Application Number
—
Jurisdiction
EP
Data Source
google_patents
Last Synchronized
2026-11-01 20:16
CPC Classifications
H; H04; H04N; H04N1/00; H04N1/32; H04N1/32358; H04N1/32443; H04N1/32448; H04N1/04; H04N1/047; H04N1/0473; H04N1/12; H04N1/19; H04N1/191; H04N1/192; H04N1/193; H04N2201/00; H04N2201/0077; H04N2201/0081; H04N2201/0082; H04N2201/0086; H04N2201/0087; H04N2201/024; H04N2201/02406; H04N2201/02439; H04N2201/04; H04N2201/047; H04N2201/04701; H04N2201/0471; H04N2201/04715; H04N2201/04724; H04N2201/04725; H04N2201/04734; H04N2201/04753; H04N2201/04756; H04N2201/04758; H04N2201/04767; H04N2201/04781; H04N2201/04786; H04N2201/04794; H04N2201/32; H04N2201/3285; H04N2201/329; H04N2201/3294
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
167 words
Raster scanner apparatus comprising: a) a platen (25) having a document scanning aperture (26) therein; b) transport means (30, 31) for moving documents to be scanned across said scanning aperture; c) at least one scanning array (38) for scanning documents (18) on said platen as said documents are moved across said scanning aperture by°said transport means, said array (38) generating a pixel line on each scan; d) clock means (70) for operating said array at a preset scan rate; e) buffer means (14) for receiving pixel lines output by said array (38), and f) means (80, 90, 92) for actuating said transport means (30) on a demand for pixel lines by said buffer means (14); the apparatus being characterised by: control means (15) for outputting pixel lines to said buffer means and discarding any duplicate pixel lines resulting from repeated scanning of the same document line by said array when the rate at which the document is scanned is less than the scan rate of said array.
Claim 2
Dependent Claim
167 words
Raster scanner apparatus comprising: a) a platen (25) having a document scanning aperture (26) therein; b) transport means (30, 31) for moving documents to be scanned across said scanning aperture; c) at least one scanning array (38) for scanning documents (18) on said platen as said documents are moved across said scanning aperture by°said transport means, said array (38) generating a pixel line on each scan; d) clock means (70) for operating said array at a preset scan rate; e) buffer means (14) for receiving pixel lines output by said array (38), and f) means (80, 90, 92) for actuating said transport means (30) on a demand for pixel lines by said buffer means (14); the apparatus being characterised by: control means (15) for outputting pixel lines to said buffer means and discarding any duplicate pixel lines resulting from repeated scanning of the same document line by said array when the rate at which the document is scanned is less than the scan rate of said array.
Claim 3
Dependent Claim
126 words
The apparatus of claim 1 wherein the transport means (30) is arranged for transporting documents to be scanned across said scanning aperture at a controlled scanning speed; the means (80, 90, 92) for actuating the transport means includes means for starting and stopping said document transport means in response to demand for pixel lines by said buffer means; and the control means includes means for discarding redundant pixel lines output by said array when said document transport means is stopped or accelerating or decelerating to or from said controlled scanning speed to thereby accommodate continued operation of said array at said preset scanning rate while said document transport means is stopped, or accelerating or decelerating while avoiding output of redundant pixel lines to said buffer means.
Claim 4
Dependent Claim
49 words
The apparatus of claim 2 in which said control means includes gate means (45) for selectively blocking output of pixel lines by said array to said buffer means, and means- (50) for actuating said gate means to a blocking condition in response to stopping of said document transport means.
Claim 5
Dependent Claim
42 words
The apparatus of claim 2 in which said control means includes: means (50) for generating a signal identifying valid pixel lines, and selector means (45) for passing pixel lines output by said array to said buffer means in response to said signal.
Claim 6
Dependent Claim
120 words
The apparatus of claim 1 in which said control means includes: a) a control gate (45) interposed between said array (38) and said buffer means (14) to control output of pixel lines from said array to said buffer means, said control gate in a first state blocking passage of pixel lines to said buffer means and in a second state permitting passage of pixel lines to said buffer means; b) means (43) for generating a control signal in synchronism with movement of said document transport means; and c) a control (50) for switching said control gate (45) to said second state in response to said control signal whereby to pass pixel lines output by said array to said buffer means.
Claim 7
Dependent Claim
42 words
The apparatus of claim 5 including a second control (57) for intervening to delay switching of said control gate to said second state until start of a pixel line whereby to prevent input of a partial pixel line to said buffer means.
Claim 8
Dependent Claim
79 words
The apparatus of claim 1 wherein the transport means (30, 31) is arranged for moving documents to be scanned in step by step fashion across said scanning aperture; the means (80, 90, 92) for actuating said transport means on a demand for pixel lines by said buffer means is arranged to step the document being scanned at least one step, and the control means is arranged for outputting one pixel line to said buffer means for each document step.
Claim 9
Dependent Claim
145 words
A raster scanning method for supplying pixel lines to a buffer from a scanning array which scans documents one line at a time through a scan slit, comprising scanning said array continuously to produce pixel lines at a predetermined rate irrespective of document movement, characterised by monitoring the supply of pixel lines in said buffer; moving the document to be scanned across said scan slit in response to a preset low supply of pixel lines in said buffer and stopping said document when the supply of pixel lines in said buffer reaches a preset high; and outputting one pixel line to said buffer for each document line scanned and discarding any redundant pixel lines resulting from repeated scanning of the same document line by said array when the rate at which documents are moved across said scan slit is less than said array scan rate.
Claim 10
Dependent Claim
145 words
A raster scanning method for supplying pixel lines to a buffer from a scanning array which scans documents one line at a time through a scan slit, comprising scanning said array continuously to produce pixel lines at a predetermined rate irrespective of document movement, characterised by monitoring the supply of pixel lines in said buffer; moving the document to be scanned across said scan slit in response to a preset low supply of pixel lines in said buffer and stopping said document when the supply of pixel lines in said buffer reaches a preset high; and outputting one pixel line to said buffer for each document line scanned and discarding any redundant pixel lines resulting from repeated scanning of the same document line by said array when the rate at which documents are moved across said scan slit is less than said array scan rate.
Claim 11
Dependent Claim
20 words
The scanning method according to claim 8 including the step of preventing output of partial pixel lines to said buffer.
Claim 12
Dependent Claim
33 words
The raster scanning method of claim 8 or claim 9 wherein the step of moving the document to be scanned comprises stepping the document one line at a time across the scan slit.
References Cited (Backward Citations)
No citation records indexed.
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