US3806820A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Audio apparatus
Assignee: Nippon Gakki Co Ltd
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Filing: 1972-02-24
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Granted: 1974-04-23
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Expires: 1992-02-24
Abstract
Abstract An audio apparatus includes a touch detective muting arrangement. Switch actuating knobs made of metal are electrically insulated from the circuit ground and connected to an electro-static field detector circuit detecting a touch of an operator''s finger with the knobs and producing a control signal. A muting circuit is provided in the audio signal path and connected to the detector circuit to be controlled by the control signal. When a finger touches the knob, the muting circuit is rendered operative to mute the audio signal, thus preventing undesirable click noise which might otherwise come out in accordance with changing-over manipulation of the switch.
Inventors
- 👤 Y Uchiyama
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 04:31
CPC Classifications
H; H03; H03G; H03G3/00; H03G3/20; H03G3/30; H03G3/34; H03G3/348; H03K; H03K17/00; H03K17/94; H03K17/96; H03K17/962
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
149 words
An audio apparatus with muting circuit, comprising an audio apparatus having an audio signal path, a discrete selection change-over switch generating click noise during a switching change over operation and disposed in said audio signal path, a muting arrangement comprising a switch knob coupled to said switch for the actuation thereof, said knob being made of an electrically conductive material and insulated from the ground, an electrostatic field detector circuit for detecting the electrostatic field established from the human body of an operator who manually operates said switch knob thereby providing a control signal, a muting circuit means incorporated in said audio signal path and for changing its impedance in response to said control signal supplied from said electrostatic field detector circuit and decreasing signal transmissibility during the switching change-over operation muting transmissibility of said click noise in the audio signal path during the manipulations of said switch knob.
Claim 2
Dependent Claim
149 words
An audio apparatus with muting circuit, comprising an audio apparatus having an audio signal path, a discrete selection change-over switch generating click noise during a switching change over operation and disposed in said audio signal path, a muting arrangement comprising a switch knob coupled to said switch for the actuation thereof, said knob being made of an electrically conductive material and insulated from the ground, an electrostatic field detector circuit for detecting the electrostatic field established from the human body of an operator who manually operates said switch knob thereby providing a control signal, a muting circuit means incorporated in said audio signal path and for changing its impedance in response to said control signal supplied from said electrostatic field detector circuit and decreasing signal transmissibility during the switching change-over operation muting transmissibility of said click noise in the audio signal path during the manipulations of said switch knob.
Claim 3
Dependent Claim
171 words
In an audio apparatus having an audio signal path; a muting arrangement comprising a switch knob of an electrically conductive material and insulated from the ground, an electrostatic field detector circuit for detecting the electrostatic field established from an operator''s human body who manually operates said switch knob thereby providing a control signal, a muting circuit incorporated in the audio signal path and adapted to change its impedance in response to said control signal supplied from said electrostatic field detector circuit thereby decreasing signal transmissibility in the audio signal path during the manipulationS of said switch knob, said electrostatic field detector circuit includes, an input terminal, an output terminal, an amplifier circuit comprising a first transistor having a base connected through a capacitor to said input terminal, a second transistor having a base circuit which includes a resistor and a capacitor, and a diode connected across the collector of said first transistor and the base of said second transistor, the collector of said second transistor being connected to said output terminal.
Claim 4
Dependent Claim
171 words
In an audio apparatus having an audio signal path; a muting arrangement comprising a switch knob of an electrically conductive material and insulated from the ground, an electrostatic field detector circuit for detecting the electrostatic field established from an operator''s human body who manually operates said switch knob thereby providing a control signal, a muting circuit incorporated in the audio signal path and adapted to change its impedance in response to said control signal supplied from said electrostatic field detector circuit thereby decreasing signal transmissibility in the audio signal path during the manipulationS of said switch knob, said electrostatic field detector circuit includes, an input terminal, an output terminal, an amplifier circuit comprising a first transistor having a base connected through a capacitor to said input terminal, a second transistor having a base circuit which includes a resistor and a capacitor, and a diode connected across the collector of said first transistor and the base of said second transistor, the collector of said second transistor being connected to said output terminal.
Claim 5
Dependent Claim
146 words
In an audio apparatus having an audio signal path; a muting arrangement comprising a switch knob of an electrically conductive material and insulated from the ground, an electrostatic field detector circuit for detecting the electrostatic field established from an operator''s human body who manually operates said switch knob thereby providing a control signal, a muting circuit incorporated in the audio signal path and adapted to change its impedance in response to said control signal supplied from said electrostatic field detector circuit thereby decreasing signal transmissibility in the audio signal path during the manipulations of said switch knob, said muting circuit includes a field effect transistor comprising, a gate electrode connected to an output terminal of said electrostatic field detector circuit, the impedance of said muting circuit being increased or decreased in response to the presence or absence of said control signal applied to said gate electrode.
Claim 6
Dependent Claim
146 words
In an audio apparatus having an audio signal path; a muting arrangement comprising a switch knob of an electrically conductive material and insulated from the ground, an electrostatic field detector circuit for detecting the electrostatic field established from an operator''s human body who manually operates said switch knob thereby providing a control signal, a muting circuit incorporated in the audio signal path and adapted to change its impedance in response to said control signal supplied from said electrostatic field detector circuit thereby decreasing signal transmissibility in the audio signal path during the manipulations of said switch knob, said muting circuit includes a field effect transistor comprising, a gate electrode connected to an output terminal of said electrostatic field detector circuit, the impedance of said muting circuit being increased or decreased in response to the presence or absence of said control signal applied to said gate electrode.
References Cited (Backward Citations)
US2560313A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-04-22 | 1977-10-22 | 1978-04-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-04-22 | 1981-10-22 | 1982-04-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-04-22 | 1985-10-22 | 1986-04-23 | $7700.00 | Window Closed / Lapsed |