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Patent US4998172A successfully refreshed from Google Patents.
US4998172A
Expired / Lapsed
US
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Secondary beat signal cancel circuit
Assignee: Sony Corp
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Filing: 1987-06-16
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Granted: 1991-03-05
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Expires: 2007-06-16
Abstract
Abstract A magnetic reproducing apparatus is provided with an improved secondary beat signal cancel circuit for reducing a secondary beat signal of a low-frequency converted chroma signal leaked into a reproduced luminance signal without deteriorating vertical resolution at the edge of an oblique check signal. The secondary beat signal cancel operation is interrupted during a period in which no vertical correlation exists between the edge portions of two succeeding horizontal lines of the oblique check signal.
Inventors
- 👤 Toshihiko Kitazawa
- 👤 Ichitaro Sato
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-07 21:35
CPC Classifications
H; H04; H04N; H04N9/00; H04N9/79; H04N9/7908; H04N9/7912
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
179 words
A circuit for reducing a secondary beat signal of a low-frequency converted chrominance signal leaked into a reproduced luminance signal, said secondary beat signal being produced because of the transmission of said luminance and chrominance signals through a non-linear transmission medium; said circuit comprising: means for deriving a non-correlation signal having a leakage chrominance signal component superimposed thereon and an edge signal indicating a difference between luminance signal levels of corresponding points of succeeding horizontal scan lines; means for detecting an amplitude of said chrominance signal; level control means responsive to said detected amplitude of said chrominance signal for controlling an amplitude of said non-correlation signal in response to said detected amplitude of said chrominance signal to produce a signal of controlled amplitude such that said chrominance signal and said leakage chrominance signal component have equal amplitudes; means responsive to said signal of controlled amplitude and said reproduced luminance signal for subtracting said signal of controlled amplitude from said reproduced luminance signal; and gate means for inhibiting output from said level control means in response to said edge signal.
Claim 2
Dependent Claim
179 words
A circuit for reducing a secondary beat signal of a low-frequency converted chrominance signal leaked into a reproduced luminance signal, said secondary beat signal being produced because of the transmission of said luminance and chrominance signals through a non-linear transmission medium; said circuit comprising: means for deriving a non-correlation signal having a leakage chrominance signal component superimposed thereon and an edge signal indicating a difference between luminance signal levels of corresponding points of succeeding horizontal scan lines; means for detecting an amplitude of said chrominance signal; level control means responsive to said detected amplitude of said chrominance signal for controlling an amplitude of said non-correlation signal in response to said detected amplitude of said chrominance signal to produce a signal of controlled amplitude such that said chrominance signal and said leakage chrominance signal component have equal amplitudes; means responsive to said signal of controlled amplitude and said reproduced luminance signal for subtracting said signal of controlled amplitude from said reproduced luminance signal; and gate means for inhibiting output from said level control means in response to said edge signal.
Claim 3
Dependent Claim
88 words
The circuit according to claim 1, in which said deriving means includes a separating circuit having two circuit paths, one of said two circuit paths deriving said non-correlation signal and having a band pass filter and a limiting amplifier circuit serially coupled to said level control means and the other of said two circuit paths deriving said edge signal and having an amplifier, a band-eliminating filter and a full-wave rectifier serially coupled to said gate means, whereby the edge signal supplied to said gate means is full-wave rectified.
Claim 4
Dependent Claim
57 words
The circuit according to claim 2, in which said gate means includes two input terminals to which said full-wave rectified edge signal and said detected amplitude signal are respectively supplied so that said detected amplitude signal is inhibited from being applied to said level control means during a period in which said full-wave rectified edge signal occurs.
Claim 5
Dependent Claim
43 words
The circuit according to claim 3 further comprising delay line means connected between an input terminal of said luminance signal and said subtracting means, said delay line means having a time delay substantially equal to a time delay caused by said deriving 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) | 1994-03-04 | 1994-09-03 | 1995-03-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1998-03-04 | 1998-09-03 | 1999-03-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2002-03-04 | 2002-09-03 | 2003-03-05 | $7700.00 | Window Closed / Lapsed |