US5115327A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Gain control circuit for use in shading compensation circuit
Assignee: Ricoh Co Ltd
•
Filing: 1990-03-02
•
Granted: 1992-05-19
•
Expires: 2010-03-02
Abstract
Abstract A gain control circuit used in a shading compensation circuit includes a signal processing circuit for an image signal successively output from each of cells of a line image sensor and a gain control signal corresponding to shading data output from an external signal system and converting the image signal into a signal with level corresponding to the gain control signal and for outputting a compensation image signal, and signal feedback circuit for inverting a reference compensation image signal and holding an inverted version of the reference compensation image signal and for feeding the inverted version of the reference compensation image signal back to a terminal of the signal processing circuit and which the image signal is input.
Inventors
- 👤 Kazumi Ishima
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 11:57
CPC Classifications
G; G11; G11C; G11C19/00; G11C19/28; G11C19/282; G11C19/285; G11C27/00; G11C27/04; H; H04; H04N; H04N1/00; H04N1/40; H04N1/401; H04N25/00; H04N25/60; H04N25/61; H04N25/70; H04N25/701; H04N25/7013; H04N25/67; H04N25/671; H04N25/673
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
229 words
A gain control circuit used in a shading compensation circuit comprising: signal processing means for inputting an image signal successively output from each of cells of a line image sensor and a gain control signal corresponding to shading data output from an external signal system and converting said image signal into a signal with a level corresponding to said gain control signal and for outputting a converted version of said signal as a compensation image signal, signal feed back means for inverting a reference compensation image signal and holding an inverted version of said reference compensation image signal and for feeding said inverted version of the reference compensation image signal back to a terminal of said signal processing means and to which said image signal is input, said reference compensation signal being obtained from said signal processing means when a reference gain control signal having a predetermined value and a reference image signal having a predetermined reference level are input to said signal processing means, the reference gain control signal being supplied from said external signal means, the reference image signal being included in a predetermined part of said image signal, and bias means for shifting a level of said image signal supplied to said terminal of said signal processing means by a predetermined level so that the reference compensation signal has a level greater than a predetermined value.
Claim 2
Dependent Claim
229 words
A gain control circuit used in a shading compensation circuit comprising: signal processing means for inputting an image signal successively output from each of cells of a line image sensor and a gain control signal corresponding to shading data output from an external signal system and converting said image signal into a signal with a level corresponding to said gain control signal and for outputting a converted version of said signal as a compensation image signal, signal feed back means for inverting a reference compensation image signal and holding an inverted version of said reference compensation image signal and for feeding said inverted version of the reference compensation image signal back to a terminal of said signal processing means and to which said image signal is input, said reference compensation signal being obtained from said signal processing means when a reference gain control signal having a predetermined value and a reference image signal having a predetermined reference level are input to said signal processing means, the reference gain control signal being supplied from said external signal means, the reference image signal being included in a predetermined part of said image signal, and bias means for shifting a level of said image signal supplied to said terminal of said signal processing means by a predetermined level so that the reference compensation signal has a level greater than a predetermined value.
Claim 3
Dependent Claim
24 words
The gain control circuit as claimed in claim 1 wherein said reference gain control signal has a value corresponding to a gain of "1".
Claim 4
Dependent Claim
23 words
The gain control circuit as claimed in claim 1 wherein the reference image signal has a level corresponding to a predetermined black tone.
Claim 5
Dependent Claim
79 words
The gain control circuit as claimed in claim 1 wherein said signal feedback means has a sampling means for sampling said reference compensation image signal and a signal holding means for inverting said reference compensation image signal sampled by said sampling means and holding a inverted version of said reference compensation image signal until a following sampling is performed by said sampling means, and said inverted version of the reference compensation image signal is fed back to said terminal.
Claim 6
Dependent Claim
27 words
The gain control circuit as claimed in claim 1 wherein said bias means has a bias change means for changing a shift level of said image signal.
Claim 7
Dependent Claim
42 words
The gain control circuit as claimed in claim 1, wherein said bias means has a bias circuit which supplies a predetermined bias voltage to said terminal of said signal processing means so that a polarity of the reference compensation signal is positive.
References Cited (Backward Citations)
US4723174A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1995-05-19 | 1995-11-18 | 1996-05-19 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1999-05-19 | 1999-11-18 | 2000-05-19 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2003-05-19 | 2003-11-18 | 2004-05-19 | $7700.00 | Window Closed / Lapsed |