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US4157533A
Expired / Lapsed
US
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Independent channel automatic gain control for self-scanning photocell array
Assignee: Bell and Howell Co
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Filing: 1977-11-25
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Granted: 1979-06-05
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Expires: 1997-11-25
Abstract
Abstract A scanned photocell array has the gain for each photocell channel automatically controlled by establishing a scale range based upon the media being scanned. The apparent gain of each cell is varied by modulating the reference input of an analog to digital converter at the photocell scan rate.
Inventors
- 👤 Dale R. Duvall
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 10:30
CPC Classifications
G; G06; G06V; G06V30/00; G06V30/10; G06V30/16; G06V30/162; B; B41; B41J; B41J2/00; B41J2/435; B41J2/447; B41J2/45; B41J2002/453
Claims Analysis
Total Claims: 14
Claim 1
Independent Claim
68 words
A control circuit for automatically independently controlling the effective gain of each photocell in a scanned array of photocells comprising; means for storing a digital reference gain value for each photocell each time the photocell is scanned, said value based upon the output of a photocell of a previous scan and means for independently varying the apparent gain of each photocell based upon the stored reference gain value.
Claim 2
Dependent Claim
68 words
A control circuit for automatically independently controlling the effective gain of each photocell in a scanned array of photocells comprising; means for storing a digital reference gain value for each photocell each time the photocell is scanned, said value based upon the output of a photocell of a previous scan and means for independently varying the apparent gain of each photocell based upon the stored reference gain value.
Claim 3
Dependent Claim
23 words
The circuits according to claim 1 wherein the means for varying the apparent gain of each photocell includes an analog to digital converter.
Claim 4
Dependent Claim
27 words
The circuit according to claim 2 wherein the analog to digital converter has a reference input and the reference input is modulated at the photocell scan rate.
Claim 5
Dependent Claim
115 words
An automatic gain control circuit for varying the gain from one scan to another of each photocell in a scanned array of photocells comprising; means for sequentially comparing with a reference value, the video output of each photocell as it is scanned, means for storing the results of the comparison and generating a new reference value each time the photocell is scanned, means for delaying the reference value for at least one scan and means for adjusting the apparent gain of each photocell after said delay in accordance with the new reference value when the video output of a photocell is less than or exceeds the reference value for a predetermined number of successive scans.
Claim 6
Dependent Claim
115 words
An automatic gain control circuit for varying the gain from one scan to another of each photocell in a scanned array of photocells comprising; means for sequentially comparing with a reference value, the video output of each photocell as it is scanned, means for storing the results of the comparison and generating a new reference value each time the photocell is scanned, means for delaying the reference value for at least one scan and means for adjusting the apparent gain of each photocell after said delay in accordance with the new reference value when the video output of a photocell is less than or exceeds the reference value for a predetermined number of successive scans.
Claim 7
Dependent Claim
45 words
The control circuit according to claim 4 including means for storing the reference value in digital form and converting it to analog form when it is compared with the photocell video signal, and when it is used to adjust the apparent gain of each photocell.
Claim 8
Dependent Claim
28 words
The control circuit according to claim 4 including means for applying the reference value to means for adjusting the apparent gain at the scan rate of the array.
Claim 9
Dependent Claim
102 words
A control circuit for compensating gain difference in individual photocells in an array of scanned photocells and for adjusting apparent photocell gain to compensate for differences in reflectance of the media being scanned by the photocell array comprising; means for detecting a change in reflectance of the media being scanned for each scan of each photocell in said array, means for delaying gain compensation of each photocell for a predetermined period after detection in a change in reflectance, and means operable after said delay to increase or decrease gain to establish a gain compensation for each photocell corresponding to said reflectance change.
Claim 10
Dependent Claim
102 words
A control circuit for compensating gain difference in individual photocells in an array of scanned photocells and for adjusting apparent photocell gain to compensate for differences in reflectance of the media being scanned by the photocell array comprising; means for detecting a change in reflectance of the media being scanned for each scan of each photocell in said array, means for delaying gain compensation of each photocell for a predetermined period after detection in a change in reflectance, and means operable after said delay to increase or decrease gain to establish a gain compensation for each photocell corresponding to said reflectance change.
Claim 11
Independent Claim
127 words
An apparatus for providing automatic gain control for each photocell in a multicell self-scanning array comprising; means for generating a sequential analog video signal representative of the output of each of the photocells, an automatic gain control circuit for generating a digital reference signal for each photocell, a digital to analog converter for changing each digital reference signal to an analog value, means for storing each of said reference signals, means for comparing the analog reference signals with the sequential analog signal on a cell by cell basis each time the photocell is scanned, and means for generating a digital value representative of each cell output signal independent of the other cell output signals adjusted in gain based upon the reference signal against which it is compared.
Claim 12
Independent Claim
127 words
An apparatus for providing automatic gain control for each photocell in a multicell self-scanning array comprising; means for generating a sequential analog video signal representative of the output of each of the photocells, an automatic gain control circuit for generating a digital reference signal for each photocell, a digital to analog converter for changing each digital reference signal to an analog value, means for storing each of said reference signals, means for comparing the analog reference signals with the sequential analog signal on a cell by cell basis each time the photocell is scanned, and means for generating a digital value representative of each cell output signal independent of the other cell output signals adjusted in gain based upon the reference signal against which it is compared.
Claim 13
Independent Claim
120 words
A method for individually compensating the gain of each photocell in an array of scanned photocells for reflectance changes in the media scanned by the photocells comprising the steps of; generating a reference signal for each photocell, comparing the video output of each photocell with the reference signal for that photocell, delaying the reference value for at least one scan, generating a new signal based on the comparison of the video signal and the delayed reference signal, storing the new signal, generating a new reference signal based on the new signal and adjusting the apparent gain of each photocell by using the new reference signal as a reference to modify the current output of the video signal of each photocell.
Claim 14
Independent Claim
120 words
A method for individually compensating the gain of each photocell in an array of scanned photocells for reflectance changes in the media scanned by the photocells comprising the steps of; generating a reference signal for each photocell, comparing the video output of each photocell with the reference signal for that photocell, delaying the reference value for at least one scan, generating a new signal based on the comparison of the video signal and the delayed reference signal, storing the new signal, generating a new reference signal based on the new signal and adjusting the apparent gain of each photocell by using the new reference signal as a reference to modify the current output of the video signal of each photocell.
References Cited (Backward Citations)
US3568151A
Cited
US3962681A
Cited
US3800078A
Cited
US3918049A
Cited
US3872434A
Cited
US4064484A
Cited
US4128830A
Cited
US4129853A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1982-06-04 | 1982-12-04 | 1983-06-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1986-06-04 | 1986-12-04 | 1987-06-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1990-06-04 | 1990-12-04 | 1991-06-05 | $7700.00 | Window Closed / Lapsed |