US4188639A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Video synchronous detector apparatus
Assignee: Hitachi Ltd
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Filing: 1977-12-20
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Granted: 1980-02-12
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Expires: 1997-12-20
Abstract
Abstract A video synchronous detector apparatus for discriminating a video intermediate frequency signal, in which the video intermediate frequency signal is divided into two parts, one of which is applied to one terminal of a multiplier circuit, and the other of which is applied to the other terminal of the multiplier circuit through a picture-carrier intermediate frequency extraction circuit having a frequency selection circuit and a limiter circuit. The frequency selection circuit is provided with a trap circuit. The trap circuit has a center resonance frequency equal to a differential frequency between a picture-carrier intermediate frequency (f p ) and a differential frequency between a color subcarrier intermediate frequency (f c ) and a sound-carrier intermediate frequency (f s ) so that a so-called sound-cross-color disturbance caused by a beat between the intermediate frequency sound signal and the intermediate frequency picture signal may be reduced.
Inventors
- 👤 Toshio Murakami
- 👤 Masaru Noda
- 👤 Hiroaki Nabeyama
- 👤 Takeshi Murakami
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-01 09:16
CPC Classifications
H; H04; H04N; H04N9/00; H04N9/64; H04N9/66
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
130 words
A video synchronous detector apparatus comprising: a first terminal for receiving a video intermediate frequency signal; a multiplier circuit having two inputs and an output, one of said two inputs being connected to said first terminal; and a picture-carrier intermediate frequency extraction circuit connected between said first terminal and the other of said two inputs; said picture-carrier intermediate frequency extraction circuit comprising a limiter circuit and a frequency selection circuit having a trap circuit, a resonance frequency of said trap circuit being equal to a differential frequency between a picture-carrier intermediate frequency and a differential frequency between a sound-carrier intermediate frequency and a color subcarrier intermediate frequency to reduce disturbances caused by a beat between the sound-carrier intermediate frequency and a side band component of the video intermediate frequency signal.
Claim 2
Dependent Claim
130 words
A video synchronous detector apparatus comprising: a first terminal for receiving a video intermediate frequency signal; a multiplier circuit having two inputs and an output, one of said two inputs being connected to said first terminal; and a picture-carrier intermediate frequency extraction circuit connected between said first terminal and the other of said two inputs; said picture-carrier intermediate frequency extraction circuit comprising a limiter circuit and a frequency selection circuit having a trap circuit, a resonance frequency of said trap circuit being equal to a differential frequency between a picture-carrier intermediate frequency and a differential frequency between a sound-carrier intermediate frequency and a color subcarrier intermediate frequency to reduce disturbances caused by a beat between the sound-carrier intermediate frequency and a side band component of the video intermediate frequency signal.
Claim 3
Dependent Claim
67 words
A video synchronous detector apparatus according to claim 1, wherein said frequency selection circuit comprises a parallel resonance circuit of a first inductor (L o ) and a first capacitor (C o ) and said trap circuit connected across said parallel resonance circuit, said trap circuit being composed of a series resonance circuit of a second inductor (L 1 ) and a second capacitor (C 1 ).
Claim 4
Dependent Claim
59 words
A video synchronous detector apparatus according to claim 1, wherein said frequency selection circuit comprises a parallel resonance circuit of an inductor (L o ) and a first capacitor (C 1 ) and said trap circuit, said trap circuit being composed of a series resonance circuit of said inductor (L o ) and a second capacitor (C 1 ).
Claim 5
Dependent Claim
51 words
A video synchronous detector apparatus according to claim 1, wherein said frequency selection circuit comprises a parallel resonance circuit of an inductor (L o ) and a capacitor (C o ) and said trap circuit connected across said parallel resonance circuit, said trap circuit being composed of a ceramic resonator (FL).
Claim 6
Dependent Claim
22 words
A video synchronous detector apparatus according to claim 1, wherein said frequency selection circuit is composed of a surface acoustic wave filter.
References Cited (Backward Citations)
US3613032A
Cited
US3697685A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1983-02-11 | 1983-08-13 | 1984-02-12 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1987-02-11 | 1987-08-13 | 1988-02-12 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1991-02-11 | 1991-08-13 | 1992-02-12 | $7700.00 | Window Closed / Lapsed |