US4167750A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Color-difference signal modifying apparatus
Assignee: Panasonic Holdings Corp
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Filing: 1977-09-26
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Granted: 1979-09-11
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Expires: 1997-09-26
Abstract
Abstract A color-difference signal modifying apparatus for modifying a color-difference signal in a color television receiver. The apparatus gives to a color-difference signal a non-linear characteristic which approximates a theoretical characteristic for completely eliminating both luminance and chromaticity errors of a reproduced color. The apparatus is constituted by a threshold signal producing means which is supplied with a luminance signal to produce a threshold signal proportional to the luminance signal, and a gain reduction means which is supplied with the color-difference signal to decrease the gain to remove a specific portion of the color-difference signal which exceeds the threshold signal level.
Inventors
- 👤 Tetsuo Tomimoto
- 👤 Yoshitomi Nagaoka
- 👤 Reiichi Sasaki
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-29 06:26
CPC Classifications
H; H04; H04N; H04N9/00; H04N9/77
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
107 words
A color difference signal modifying apparatus for modifying a color-difference signal in a color television receiver, the apparatus comprising a threshold signal producing means for being supplied with a luminance signal and for producing a threshold signal which is proportional to said luminance signal; a color-difference signal demodulator for producing a color-difference signal; and a gain reduction means coupled to said threshold signal producing means and to said color-difference signal demodulator for reducing the gain of the color-difference signal by at least a portion of the amount of the difference between said color-difference signal and said threshold signal only when said color-difference signal exceeds said threshold signal.
Claim 2
Dependent Claim
107 words
A color difference signal modifying apparatus for modifying a color-difference signal in a color television receiver, the apparatus comprising a threshold signal producing means for being supplied with a luminance signal and for producing a threshold signal which is proportional to said luminance signal; a color-difference signal demodulator for producing a color-difference signal; and a gain reduction means coupled to said threshold signal producing means and to said color-difference signal demodulator for reducing the gain of the color-difference signal by at least a portion of the amount of the difference between said color-difference signal and said threshold signal only when said color-difference signal exceeds said threshold signal.
Claim 3
Dependent Claim
41 words
A color difference signal modifying apparatus as claimed in claim 1 which further comprises a switch connected between said threshold signal producing means and ground for preventing the reduction of said color-difference signal when said switch is in the "OFF" state.
Claim 4
Dependent Claim
35 words
A color difference signal modifying apparatus as claimed in claim 1 wherein said threshold signal producing means comprises a threshold limiting means for eliminating a portion of said threshold signal lower than a stationary level.
Claim 5
Dependent Claim
108 words
A color-difference signal modifying apparatus as claimed in claim 1 which further comprises a DC voltage producing means for receiving the outputs of three color-difference signal sources, and for producing a reference DC voltage equal to a stationary voltage of said color-difference signal sources by adding the three outputs, and a signal reduction means for receiving at least one of the color-difference signals other than the red color-difference signal and coupled to said DC voltage producing means and receiving the reference DC voltage for attenuating said other color-difference signal by a portion of the amount of the difference between said other color-difference signal and said reference DC voltage.
Claim 6
Dependent Claim
83 words
A color-difference signal modifying apparatus as claimed in claim 1 which further comprises a reference signal producing means for being supplied with the red and blue color-difference signals and for producing a reference signal by adding said two color-difference signals, and a signal reduction means for receiving said blue color-difference signal and coupled to said reference signal producing means for attenuating said blue color-difference signal by a portion of the amount of the difference between said blue color-difference signal and said reference signal.
Claim 7
Dependent Claim
81 words
A color-difference signal modifying apparatus as claimed in claim 1 which further comprises a DC voltage producing means for producing a reference DC voltage equal to a stationary voltage of the color-difference signal sources, and a signal reduction means coupled to said DC voltage producing means for receiving at least one of the color-difference signals and for attenuating the said one color-difference signal by a portion of the amount of the difference between said color-difference signal and said reference DC voltage.
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) | 1982-09-10 | 1983-03-12 | 1983-09-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1986-09-10 | 1987-03-12 | 1987-09-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1990-09-10 | 1991-03-12 | 1991-09-11 | $7700.00 | Window Closed / Lapsed |