US3843838A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Muting circuit for video and audio playback system
Assignee: Thomas International Corp
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Filing: 1973-03-16
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Granted: 1974-10-22
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Expires: 1993-03-16
Abstract
Abstract A video tape recorder includes an electronic muting circuit for temporarily muting the audio portion of a recorded signal when the recorder is switched from the playback to the standby mode of operation, in response to a voltage level change on a line. After the lapse of a predetermined time period, during which transient signals are generated due to a change in acceleration of the video tape, an RC network disables a semiconductor muting switch to allow use of an audio amplifier by other apparatus associated with the video tape recorder.
Inventors
- 👤 P Wanek
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 13:47
CPC Classifications
H; H03; H03G; H03G3/00; H03G3/20; H03G3/30; H03G3/34; H03G3/348; G; G11; G11B; G11B5/00
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
252 words
In a television playback system having a recording medium for storing video and audio signals, signal coupling means for coupling video and audio signals to video and audio reproducer means, and switching means having a playback mode for causing said signal coupling means to couple the signals from the recording medium to the reproducer means and a different mode for effectively preventing the coupling of the signals from the recording medium to the reproducer means, the improvement comprising: control means for generating on a control line a voltage having a first magnitude when said switching means is in the playback mode and a second magnitude when the switching means is in the diffeRent mode, mute means for effectively disabling said signal coupling means including a network coupled to said control line and responsive to change in voltage from said first magnitude to said second magnitude for activating a disable means in said signal coupling means; and time delay means effective after the lapse of a predetermined time period for disabling said mute means to thereby enable said signal coupling means, said network means includes capacitor means forming a part of said time delay means, a semiconductor device forming said disable means and having a conducting or nonconducting state dependent on the charge on the capacitor means, and means for controlling the charge on the capacitor means by the magnitude of voltage on said control line, the time constant of the time delay means including said capacitor means controlling said predetermined time period.
Claim 2
Dependent Claim
252 words
In a television playback system having a recording medium for storing video and audio signals, signal coupling means for coupling video and audio signals to video and audio reproducer means, and switching means having a playback mode for causing said signal coupling means to couple the signals from the recording medium to the reproducer means and a different mode for effectively preventing the coupling of the signals from the recording medium to the reproducer means, the improvement comprising: control means for generating on a control line a voltage having a first magnitude when said switching means is in the playback mode and a second magnitude when the switching means is in the diffeRent mode, mute means for effectively disabling said signal coupling means including a network coupled to said control line and responsive to change in voltage from said first magnitude to said second magnitude for activating a disable means in said signal coupling means; and time delay means effective after the lapse of a predetermined time period for disabling said mute means to thereby enable said signal coupling means, said network means includes capacitor means forming a part of said time delay means, a semiconductor device forming said disable means and having a conducting or nonconducting state dependent on the charge on the capacitor means, and means for controlling the charge on the capacitor means by the magnitude of voltage on said control line, the time constant of the time delay means including said capacitor means controlling said predetermined time period.
Claim 3
Dependent Claim
62 words
The improvement of claim 1 wherein said capacitor means has first and second sides, means coupling said first side to said control line and to a power supply voltage with a magnitude offset from said first and second magnitudes, and means connecting said second side to said semiconductor device for biasing the same in accordance with the charge on the capacitor means.
Claim 4
Dependent Claim
230 words
In a television playback system having a recording medium for storing video and audio signals, signal coupling means for coupling video and audio signals to video and audio reproducer means, a power supply means for generating a plurality of power supply voltages for the television playback system, and switching means having a playback mode for causing said signal coupling means to couple the signals from the recording medium to the reproducer means and a different mode for effectively preventing the coupling of the signals from the recording medium to the reproducer means, said switching means includes a switch device which changes state when switching from the playback mode to the different mode in order to couple or uncouple one of said power supply voltages to a processor means for the video and audio signals from the recording medium, the improvement comprising: control means for generating a predetermined signal when said switching means is switched from the playback mode to the different mode, including a control line connected to a junction between said switch device and said processor means for causing the switched power supply voltage to form said predetermined signal mute means for effectively disabling said signal coupling means in response to said predetermined signal, including time delay means effective after the lapse of a predetermined time period for disabling said mute means to thereby enable said signal coupling means.
Claim 5
Dependent Claim
230 words
In a television playback system having a recording medium for storing video and audio signals, signal coupling means for coupling video and audio signals to video and audio reproducer means, a power supply means for generating a plurality of power supply voltages for the television playback system, and switching means having a playback mode for causing said signal coupling means to couple the signals from the recording medium to the reproducer means and a different mode for effectively preventing the coupling of the signals from the recording medium to the reproducer means, said switching means includes a switch device which changes state when switching from the playback mode to the different mode in order to couple or uncouple one of said power supply voltages to a processor means for the video and audio signals from the recording medium, the improvement comprising: control means for generating a predetermined signal when said switching means is switched from the playback mode to the different mode, including a control line connected to a junction between said switch device and said processor means for causing the switched power supply voltage to form said predetermined signal mute means for effectively disabling said signal coupling means in response to said predetermined signal, including time delay means effective after the lapse of a predetermined time period for disabling said mute means to thereby enable said signal coupling means.
References Cited (Backward Citations)
No citation records indexed.
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-10-21 | 1978-04-22 | 1978-10-22 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-10-21 | 1982-04-22 | 1982-10-22 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-10-21 | 1986-04-22 | 1986-10-22 | $7700.00 | Window Closed / Lapsed |