US3560751A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Optical mark sensing device
Assignee: International Business Machines Corp
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Filing: 1969-02-07
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Granted: 1971-02-02
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Expires: 1989-02-07
Abstract
Abstract The invention pertains to an optical mark reading device which uses collinated light directed toward a document path with light reflected to and intercepted by a phototransistor array to yield signal currents. The current signal is converted to a voltage in the amplifier which is sensed by a comparator circuit that stores a voltage level representative of background illumination and emits the signal upon the occurrence of a proportional reduction of light level indicative of a mark in the sensing area.
Inventors
- 👤 Donald L Buettner
- 👤 John R Burchfiel Jr
- 👤 Norman D Kline
- 👤 Michael J Sheehan
- 👤 Kenneth L Thompson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 11:55
CPC Classifications
G; G06; G06K; G06K7/00; G06K7/10; G06K7/10544; G06K7/10821; G06K7/10851
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
231 words
A device for sensing marks on continuously feeding records which have marked positions located along the intersections of rows and columns extending over the document surface with a sensing station forming a portion of the document guide path extending transversely across such guide path comprising; a plurality of light collimating means for directing beams of collimated light toward a document at said sensing station which intercept such document at respective sensing locations corresponding respectively to each document row in which a mark to be sensed may occur; separate photosensing means respectively associated with each such row and mounted to receive reflected light from a document surface originating from one of said collimated light beams; amplifier means associated with each of said photosensing means including first and second variable threshold switching means for respectively generating second and third output signals upon respectively sensing first and second proportional reductions in the level of reflected light sensed by said photosensing means; said second proportional reduction being indicative of a value of sensed light intensity intermediate the initial value and that indicated by said first proportional reduction; whereby the coincidence of said second and third output signals indicates that data has been sensed, the absence of both second and third output signals indicates the absence of data and the occurrence of said third output in the absence of said second output indicates a detected error.
Claim 2
Independent Claim
231 words
A device for sensing marks on continuously feeding records which have marked positions located along the intersections of rows and columns extending over the document surface with a sensing station forming a portion of the document guide path extending transversely across such guide path comprising; a plurality of light collimating means for directing beams of collimated light toward a document at said sensing station which intercept such document at respective sensing locations corresponding respectively to each document row in which a mark to be sensed may occur; separate photosensing means respectively associated with each such row and mounted to receive reflected light from a document surface originating from one of said collimated light beams; amplifier means associated with each of said photosensing means including first and second variable threshold switching means for respectively generating second and third output signals upon respectively sensing first and second proportional reductions in the level of reflected light sensed by said photosensing means; said second proportional reduction being indicative of a value of sensed light intensity intermediate the initial value and that indicated by said first proportional reduction; whereby the coincidence of said second and third output signals indicates that data has been sensed, the absence of both second and third output signals indicates the absence of data and the occurrence of said third output in the absence of said second output indicates a detected error.
Claim 3
Dependent Claim
38 words
The device of claim 1 wherein said document path is positioned to present a document passing said sensing station in a substantially horizontal attitude and said light source and said photosensing means are disposed below said document path.
Claim 4
Dependent Claim
90 words
The device of claim 1 wherein each said variable threshold switching means comprises: a capacitor which is charged in accordance with the level of light intensity sensed from the document background; means for restraining decay of the charge of said capacitor when the output of the associated photosensing means changes indicating a drop in the intensity of reflected light sensed; and pluraL impedance means interconnected with each said capacitor and with relative values to initiate said second output signal upon sensing a predetermined proportional drop in said sensed light level.
Claim 5
Dependent Claim
33 words
The device of claim 1 wherein each of said plurality of light collimating means receives light from a single incandescent source and communicates therewith at a location transversely offset from the filament thereof.
Claim 6
Independent Claim
172 words
A device for sensing marks on a document feeding past a sensing station comprising: a source of collimated light; photo sensing means including preamplifier means for intercepting reflected light from said document at said sensing station and operative to generate a first electrical output proportional to the intensity of light sensed; first comparator means connected to said photo sensing means to receive said first electrical output, said first comparator means being operative to store a signal indicative of the value of said first electrical output and generate a second output signal upon a first predetermined proportional reduction of said first electrical output; and second comparator means connected to said photo sensing means to receive said first electrical output, said second comparator means being operative to store a signal indicative of the value of said first electrical output and generate a third output signal upon a second predetermined proportional reduction of said first electrical output, said second predetermined proportional reduction being a value intermediate said first signal and said first predetermined proportional reduction.
Claim 7
Independent Claim
172 words
A device for sensing marks on a document feeding past a sensing station comprising: a source of collimated light; photo sensing means including preamplifier means for intercepting reflected light from said document at said sensing station and operative to generate a first electrical output proportional to the intensity of light sensed; first comparator means connected to said photo sensing means to receive said first electrical output, said first comparator means being operative to store a signal indicative of the value of said first electrical output and generate a second output signal upon a first predetermined proportional reduction of said first electrical output; and second comparator means connected to said photo sensing means to receive said first electrical output, said second comparator means being operative to store a signal indicative of the value of said first electrical output and generate a third output signal upon a second predetermined proportional reduction of said first electrical output, said second predetermined proportional reduction being a value intermediate said first signal and said first predetermined proportional reduction.
Claim 8
Dependent Claim
48 words
The device of claim 5 wherein said source of collimated light comprises a shrouded tubular light confining passageway having a terminal collimating portion of substantially constant cross section, said passageway originating adjacent an incandescent light source offset from the axis thereof and terminating closely adjacent said sensing station.
Claim 9
Dependent Claim
48 words
The device of claim 6 wherein said collimating light is directed substantially normal to a document being fed past said sensing station and said photosensing means is positioned along an axis having an angle of inclination not exceeding 45* with respect to the path of said collimated light.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-02-01 | 1974-08-03 | 1975-02-02 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-02-01 | 1978-08-03 | 1979-02-02 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-02-01 | 1982-08-03 | 1983-02-02 | $7700.00 | Window Closed / Lapsed |