US3934158A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Switching circuit
Assignee: Victor Company of Japan Ltd
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Filing: 1974-02-27
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Granted: 1976-01-20
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Expires: 1994-02-27
Abstract
Abstract An improved switching means is provided in a loudspeaker system, which includes a power amplifier of direct coupled type having no output condensor to deliver an audio-frequency current to the loudspeaker, to eliminate undesirable effects by rapidly breaking an electrical connection between the power amplifier and the loudspeaker upon cutting off an a.c. power source. The switching means comprises circuitry having a remarkably short "time constant" compared with another circuitry provided outside the switching means but within the loudspeaker system, so that the above-mentioned rapid breaking is accomplished.
Inventors
- 👤 Masanobu Shinozaki
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 13:44
CPC Classifications
H; H04; H04R; H04R3/00
Claims Analysis
Total Claims: 7
Claim 1
Independent Claim
295 words
In combination with a power amplifier having a loudspeaker, an a-c power source connected for supplying power to said power amplifier, including a power switch, a switching circuit for breaking a connection between a power amplifier and a loudspeaker upon cutting off an a-c power source by opening said power switch, which includes: first rectifying means provided for converting a-c voltage received from said power source to a first rectified d-c voltage, first filtering means connected to said first rectifying means and deriving said first rectified voltage therefrom for smoothing ripple variations thereof, to develop a first smoothed voltage, means supplying the first smoothed voltage to said power amplifier, a relay control transistor connected to said first filtering means and supplied with a first preset potential therefrom to maintain the relay control transistor conductive when said power switch is closed, a relay connected to said relay control transistor controlled to make the connection when the relay control transistor remains conductive, the transition time being considerable for said first smoothed voltage to decrease below said first preset potential upon cutting off said a-c power source, the improvement comprising: switching means connected to said relay control transistor, said switching means including a circuit having means with a considerably short time constant in comparison with said transition time upon cutting off said a-c power source by opening of said power switch, said switching means having means controlling said first preset potential to maintain it constant while said power switch is closed and to rapidly reduce said first preset potential upon cutting off said a-c power source, which is achieved by said short time constant, including means rendering said relay control transistor non-conductive to rapidly break said connection between said amplifier and said loudspeaker by de-energizing of said relay.
Claim 2
Dependent Claim
295 words
In combination with a power amplifier having a loudspeaker, an a-c power source connected for supplying power to said power amplifier, including a power switch, a switching circuit for breaking a connection between a power amplifier and a loudspeaker upon cutting off an a-c power source by opening said power switch, which includes: first rectifying means provided for converting a-c voltage received from said power source to a first rectified d-c voltage, first filtering means connected to said first rectifying means and deriving said first rectified voltage therefrom for smoothing ripple variations thereof, to develop a first smoothed voltage, means supplying the first smoothed voltage to said power amplifier, a relay control transistor connected to said first filtering means and supplied with a first preset potential therefrom to maintain the relay control transistor conductive when said power switch is closed, a relay connected to said relay control transistor controlled to make the connection when the relay control transistor remains conductive, the transition time being considerable for said first smoothed voltage to decrease below said first preset potential upon cutting off said a-c power source, the improvement comprising: switching means connected to said relay control transistor, said switching means including a circuit having means with a considerably short time constant in comparison with said transition time upon cutting off said a-c power source by opening of said power switch, said switching means having means controlling said first preset potential to maintain it constant while said power switch is closed and to rapidly reduce said first preset potential upon cutting off said a-c power source, which is achieved by said short time constant, including means rendering said relay control transistor non-conductive to rapidly break said connection between said amplifier and said loudspeaker by de-energizing of said relay.
Claim 3
Dependent Claim
140 words
The combination claimed in claim 1, wherein said switching means further comprises: second rectifying means for converting the a-c voltage received from said power source to a second rectified d-c voltage, second filtering means connected to said second rectifying means and deriving the second rectified voltage therefrom for smoothing ripple variations thereof, said second filtering means including said circuit with said short time constant, clipping means connected to and derived from said second filtering means the second smoothed voltage for flattening it by clipping a voltage portion in excess of a present value, control means connected to said clipping means for deriving the clipped voltage, means connecting said control means to said relay control transistor and controlling said first preset potential such that said relay control transistor remains conductive only when said clipped voltage is supplied to said control means.
Claim 4
Dependent Claim
16 words
The combination claimed in claim 2, wherein said second filtering means consists of a resistor-capacitor circuit.
Claim 5
Dependent Claim
19 words
The combination claimed in claim 2, wherein said clipping means consists of a resistor and a voltage limiting element.
Claim 6
Dependent Claim
59 words
The combination claimed in claim 2, wherein said control means comprises: a first transistor and a second transistor, means connecting the base of said first transistor to said clipping means, means connecting the collector thereof to the base of said second transistor, and means connecting the collector of said second transistor to said base of said relay control transistor.
Claim 7
Dependent Claim
99 words
The combination claimed in claim 5, including a bus line and said switching means further comprises: a sensing transistor, detecting means, a diode connected between the collector of said first transistor and the base of said second transistor for preventing a current flowing from said sensing transistor to said collector of said first transistor, means connecting said sensing transistor between said diode and the bus line extending from said first filtering means and base therefore connected to said detecting means in order to derive its output, said sensing transistor being rendered conductive upon said output exceeding a predetermined potential.
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) | 1979-01-19 | 1979-07-21 | 1980-01-20 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1983-01-19 | 1983-07-21 | 1984-01-20 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1987-01-19 | 1987-07-21 | 1988-01-20 | $7700.00 | Window Closed / Lapsed |