US3830972A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Sensitivity compensation for a self scanned photodiode array
Assignee: International Business Machines Corp
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Filing: 1972-11-13
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Granted: 1974-08-20
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Expires: 1992-11-13
Abstract
Abstract Light from a high frequency light source is directed onto a self-scanned photodiode array positioned to reflectively scan a document illuminated by a document light source. The differences in sensitivities of the diodes forming the photodiode array modulate the signal generated in response to the high frequency light source. The video output signal from the photodiode array includes the modulated high frequency component and the video information component varying with sensitivity. The two components are separated by high and low pass filters. The separated modulated high frequency component is demodulated to form a signal proportional to diode sensitivity. The separated video information signal varying with sensitivity is divided by the signal proportional to sensitivity to eliminate sensitivity variance from diode to diode in the video information signal.
Inventors
- 👤 M Siverling
- 👤 M Wilson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 06:30
CPC Classifications
G; G06; G06K; G06K7/00; G06K7/10; G06K7/10544; G06K7/10821; G06K7/10851; G06K11/00; G06V; G06V10/00; G06V10/10; G06V10/12; H; H04; H04M; H04M1/00; H04M1/26; H04M1/27; H04M1/274; H04M1/276; H04N; H04N1/00; H04N1/40; H04N1/401; G06K2207/00; G06K2207/1018
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
122 words
Sensitivity compensation apparatus for a serial scanned photodiode array comprising a high frequency light source positioned to uniformly illuminate said photodiode array, means for serially scanning said photodiode array at a scan rate sufficiently lower than the frequency of said high frequency light source to enable separation of the resultant serial video signal from said photodiode array into a video information signal component and a modulated photodiode sensitivity compensation component, means for separating said resultant serial video signal into a video information signal component and a modulated photodiode sensitivity compensation component, means for demodulating said modulated photodiode sensitivity compensation component, and means responsive to said video information signal component and said demodulated sensitivity compensation component for providing a compensated video information signal.
Claim 2
Dependent Claim
122 words
Sensitivity compensation apparatus for a serial scanned photodiode array comprising a high frequency light source positioned to uniformly illuminate said photodiode array, means for serially scanning said photodiode array at a scan rate sufficiently lower than the frequency of said high frequency light source to enable separation of the resultant serial video signal from said photodiode array into a video information signal component and a modulated photodiode sensitivity compensation component, means for separating said resultant serial video signal into a video information signal component and a modulated photodiode sensitivity compensation component, means for demodulating said modulated photodiode sensitivity compensation component, and means responsive to said video information signal component and said demodulated sensitivity compensation component for providing a compensated video information signal.
Claim 3
Dependent Claim
27 words
The sensitivity compensation apparatus of claim 1 wherein said high frequency light source is a light emitting diode and an oscillator for opening said light emitting diode.
Claim 4
Dependent Claim
24 words
The sensitivity coMpensation apparatus of claim 1 wherein said scan rate is an order of magnitude less than the frequency of said light source.
Claim 5
Dependent Claim
42 words
The sensitivity compensation apparatus of claim 1 wherein said means for separating said resultant serial video signal into a video information signal component and a modulated photodiode sensitivity compensation component includes a high frequency ban pass filter and a low pass filter.
Claim 6
Dependent Claim
22 words
The sensitivity compensation apparatus of claim 1 wherein said means for providing said compensated video information signal is a signal divider circuit.
Claim 7
Dependent Claim
77 words
Sensitivity compensation apparatus for a serially scanned photodiode array having a serial video information output comprising: means for generating a compensation signal modulated by photodiode sensitivity simultaneously with the generation of said serial video information output, means for demodulating said compensation signal to provide a signal proportional to photodiode sensitivity, and means responsive to said signal proportional to photodiode sensitivity and the serial video information signal from said photodiode array for providing a compensated video information signal.
Claim 8
Dependent Claim
77 words
Sensitivity compensation apparatus for a serially scanned photodiode array having a serial video information output comprising: means for generating a compensation signal modulated by photodiode sensitivity simultaneously with the generation of said serial video information output, means for demodulating said compensation signal to provide a signal proportional to photodiode sensitivity, and means responsive to said signal proportional to photodiode sensitivity and the serial video information signal from said photodiode array for providing a compensated video information signal.
Claim 9
Dependent Claim
59 words
Sensitivity compensation apparatus for a serially scanned photodiode array having a serial video information output comprising: means for generating a serial compensation signal proportional to photodiode sensitivity variances simultaneously with the generation of said serial video information output, and means responsive to said serial compensation signal and said serial video information signal for providing a compensated video information signal.
Claim 10
Dependent Claim
59 words
Sensitivity compensation apparatus for a serially scanned photodiode array having a serial video information output comprising: means for generating a serial compensation signal proportional to photodiode sensitivity variances simultaneously with the generation of said serial video information output, and means responsive to said serial compensation signal and said serial video information signal for providing a compensated video information signal.
References Cited (Backward Citations)
US2965711A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-08-19 | 1978-02-18 | 1978-08-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-08-19 | 1982-02-18 | 1982-08-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-08-19 | 1986-02-18 | 1986-08-20 | $7700.00 | Window Closed / Lapsed |