US5343201A
Expired / Lapsed
US
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A-D converter
Assignee: Canon Inc
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Filing: 1989-03-31
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Granted: 1994-08-30
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Expires: 2009-03-31
Abstract
Abstract An A-D converter of an image signal comprises a weighing circuit for performing a different weighing for each quantization step of A/D conversion. The different weighing is performed in accordance with gamma or white compression characteristics of the image signal.
Inventors
- 👤 Tsutomu Takayama
- 👤 Kan Takaiwa
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 15:26
CPC Classifications
H; H03; H03M; H03M1/00; H03M1/12; H03M1/34; H03M1/36; H03M1/367; H04; H04N; H04N9/00; H04N9/64
Claims Analysis
Total Claims: 17
Claim 1
Independent Claim
82 words
An analog to digital converter comprising quantizing means for quantizing an image signal in quantization steps according to the level of the image signal, weighting means for selectively weighting each of the quantization steps, and a digital decoder for producing digital signals corresponding to outputs from the quantizing means, wherein said weighting means if structured and arranged to set a weight for each of the quantization steps in accordance with a gamma characteristic and a white compression characteristic of the image signal.
Claim 2
Dependent Claim
82 words
An analog to digital converter comprising quantizing means for quantizing an image signal in quantization steps according to the level of the image signal, weighting means for selectively weighting each of the quantization steps, and a digital decoder for producing digital signals corresponding to outputs from the quantizing means, wherein said weighting means if structured and arranged to set a weight for each of the quantization steps in accordance with a gamma characteristic and a white compression characteristic of the image signal.
Claim 3
Dependent Claim
29 words
An analog to digital converter according to claim 1, further including a plurality of constant current sources connected to said weighting means for adjusting the weight for quantization steps.
Claim 4
Dependent Claim
17 words
An analog to digital converter according to claim 2, wherein said constant current source comprises a resistor.
Claim 5
Dependent Claim
18 words
An analog to digital converter according to claim 1, wherein said weighting means comprises a ladder resistance circuit.
Claim 6
Dependent Claim
32 words
An analog to digital converter according to claim 1, further including gain control means for controlling gain of said analog to digital converter by changing a bias voltage of said weighting means.
Claim 7
Dependent Claim
70 words
An A/D converter comprising: (a) quantizing means for quantizing an analog input signal by predetermined quantization steps, and (b) quantization step setting means for setting up the quantization steps, wherein weighting of the quantization steps is in successively changing order, and wherein the quantization steps for which weighting is performed comprise a portion corresponding to gamma characteristics of an input image signal and a portion corresponding to white compression characteristics.
Claim 8
Dependent Claim
70 words
An A/D converter comprising: (a) quantizing means for quantizing an analog input signal by predetermined quantization steps, and (b) quantization step setting means for setting up the quantization steps, wherein weighting of the quantization steps is in successively changing order, and wherein the quantization steps for which weighting is performed comprise a portion corresponding to gamma characteristics of an input image signal and a portion corresponding to white compression characteristics.
Claim 9
Dependent Claim
22 words
An A/D converter according to claim 6, further including a plurality of constant current sources connected to said quantization step setting means.
Claim 10
Dependent Claim
15 words
An A/D converter according to claim 7, wherein said constant current source comprises a resistor.
Claim 11
Dependent Claim
18 words
An A/D converter according to claim 6, wherein said quantization step setting means comprises a ladder resistance circuit.
Claim 12
Dependent Claim
31 words
An A/D converter according to claim 6, further comprising gain control means for controlling a gain of said A/D converter by changing a bias voltage of said quantization step setting means.
Claim 13
Dependent Claim
46 words
An image signal processor comprising quantizing means for quantizing an image signal in quantization steps according to the level of the image signal and weighting means for weighting said quantization steps in accordance with a gamma characteristic and a white compression characteristic of the image signal.
Claim 14
Dependent Claim
46 words
An image signal processor comprising quantizing means for quantizing an image signal in quantization steps according to the level of the image signal and weighting means for weighting said quantization steps in accordance with a gamma characteristic and a white compression characteristic of the image signal.
Claim 15
Dependent Claim
17 words
An image signal processor according to claim 11, wherein said weighting means comprises a constant current source.
Claim 16
Dependent Claim
17 words
An image signal processor according to claim 11, wherein said weighting means comprises a ladder resistance circuit.
Claim 17
Dependent Claim
21 words
An image signal processor according to claim 11, further comprising control means for changing a bias voltage of said weighting means.
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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) | 1997-08-29 | 1998-02-28 | 1998-08-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 2001-08-29 | 2002-02-28 | 2002-08-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2005-08-29 | 2006-02-28 | 2006-08-30 | $7700.00 | Window Closed / Lapsed |