Patent US3869698A successfully refreshed from Google Patents.
US3869698A
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US
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Optical character recognition video amplifier and digitizer
Assignee: DECISION DATA Inc A CORP OF
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Filing: 1973-11-29
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Granted: 1975-03-04
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Expires: 1993-11-29
Abstract
Abstract A video amplifier and digitizer for use in combination with an array of photoconductive diodes for optical sensing in optical character recognition equipment. The video amplifier includes a noise filter and provides high gain for the signals from the diode array. The digitizer includes circuits for storing the peak ''''black'''' and ''''white'''' levels of the analog video signal and a comparison circuit for comparing the analog video signal with a threshold between the stored black and white levels to produce a digitized video output signal.
Inventors
- 👤 Edward Trost
- 👤 Clifford E Martin
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-22 22:15
CPC Classifications
H; H04; H04N; H04N1/00; H04N1/40; H04N1/403; G; G06; G06V; G06V30/00; G06V30/10; G06V30/16; G06V30/162
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
245 words
In optical character recognition apparatus including an array of photoconductive diodes for optically scanning the characters to be recognized, a source of start signals for starting the scanning of the diode array, and a source of clock signals for sequencing the scanning of the diode array; a video amplifier and digitizer comprising: an amplifier connected to said diode array for receiving and amplifying the video signal from said diode array; first and second storage means connected to said amplifier for storing the positive and negative peak values, respectively, of said video signal, one of said peak values corresponding to the light background of the characters to be recognized and the other peak value corresponding to the dark portions of the characters to be recognized; means connected to said first and second storage means for deriving a threshold level between said positive peak value and said negative value; comparison means responsive to said amplified video signal and said threshold level for producing a digitized output signal having a first level when said amplified video signal is more positive than said threshold level and a second level when said amplified video signal is more negative than said threshold level; and negative feedback means connected between the storage means storing said one peak value corresponding to the light background and said amplifier for stabilizing said one peak value of the amplified video signal, despite variations in the reflectivity of the light background of the characters to be recognized.
Claim 2
Dependent Claim
245 words
In optical character recognition apparatus including an array of photoconductive diodes for optically scanning the characters to be recognized, a source of start signals for starting the scanning of the diode array, and a source of clock signals for sequencing the scanning of the diode array; a video amplifier and digitizer comprising: an amplifier connected to said diode array for receiving and amplifying the video signal from said diode array; first and second storage means connected to said amplifier for storing the positive and negative peak values, respectively, of said video signal, one of said peak values corresponding to the light background of the characters to be recognized and the other peak value corresponding to the dark portions of the characters to be recognized; means connected to said first and second storage means for deriving a threshold level between said positive peak value and said negative value; comparison means responsive to said amplified video signal and said threshold level for producing a digitized output signal having a first level when said amplified video signal is more positive than said threshold level and a second level when said amplified video signal is more negative than said threshold level; and negative feedback means connected between the storage means storing said one peak value corresponding to the light background and said amplifier for stabilizing said one peak value of the amplified video signal, despite variations in the reflectivity of the light background of the characters to be recognized.
Claim 3
Dependent Claim
25 words
The optical character recognition apparatus of claim 1 wherein said threshold level is substantially midway between said positive peak level and said negative peak level.
Claim 4
Dependent Claim
34 words
The optical character recognition apparatus of claim 1 further comprising: a compensating network connected between said start and clock signal sources and said amplifier for compensating said video signal to optimize low frequency ripple.
Claim 5
Dependent Claim
51 words
The optical character recognition apparatus of claim 1 further comprising: means for periodically discharging said second storage means by incremental amounts so as to cause the voltage stored in said second storage means to change slowly in the positive direction in the absence of negative peaks of said amplified video signal.
Claim 6
Dependent Claim
22 words
The optical character recognition apparatus of claim 4, further comprising: means for limiting said threshold level to less than a predetermined voltage.
Claim 7
Dependent Claim
24 words
The optical character recognition apparatus of claim 1 wherein said amplifier means includes a low-pass filter for cutting off noise above a predetermined frequency.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-03-03 | 1978-09-02 | 1979-03-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-03-03 | 1982-09-02 | 1983-03-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-03-03 | 1986-09-02 | 1987-03-04 | $7700.00 | Window Closed / Lapsed |