Patent US3904972A successfully refreshed from Google Patents.
US3904972A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Acoustic amplifier
Assignee: Hitachi Ltd
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Filing: 1973-04-27
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Granted: 1975-09-09
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Expires: 1993-04-27
Abstract
Abstract An acoustic amplifier comprises a starter circuit which sets the output potential of an output amplifier circuit at ground potential upon the connection of the power supply and then gradually raises the output potential up to the operating voltage of the output amplifier circuit, whereby the load of the acoustic amplifier is made operative without ''''pop'''' noise.
Inventors
- 👤 Kunio Seki
- 👤 Yoshio Sakamoto
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-10 02:23
CPC Classifications
H; H03; H03F; H03F1/00; H03F1/30; H03F1/305; H03F1/307; H03F3/00; H03F3/181; H03F3/183; H03F3/30; H03F3/3069; H03F3/3076; H03F3/3077; H03F3/3083; H03F3/3086; H03F3/3091
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
187 words
An acoustic amplifier comprising: a first amplifier circuit; a second amplifier circuit having an input coupled to an output of said first amplifier circuit; a power source terminal to which a source of power for said amplifier circuits is applied; a power switch, one terminal of which is connected to said power source terminal; a feedback means connected between an output of said second amplifier circuit and an input of said first amplifier circuit; a capacitor connected between said input of said first amplifier circuit and ground potential; first means, having a first terminal connected to another terminal of said power switch and a second terminal connected to said input of said second amplifier circuit, respectively, for setting the potential of the output of said second amplifier circuit at ground potential during a certain period of time starting from the instant of time when said power switch is closed; and second means, having a first terminal connected to said another terminal of the power switch and a second terminal connected to said capacitor, respectively, for supplying a charging current to said capacitor during said period of time.
Claim 2
Dependent Claim
187 words
An acoustic amplifier comprising: a first amplifier circuit; a second amplifier circuit having an input coupled to an output of said first amplifier circuit; a power source terminal to which a source of power for said amplifier circuits is applied; a power switch, one terminal of which is connected to said power source terminal; a feedback means connected between an output of said second amplifier circuit and an input of said first amplifier circuit; a capacitor connected between said input of said first amplifier circuit and ground potential; first means, having a first terminal connected to another terminal of said power switch and a second terminal connected to said input of said second amplifier circuit, respectively, for setting the potential of the output of said second amplifier circuit at ground potential during a certain period of time starting from the instant of time when said power switch is closed; and second means, having a first terminal connected to said another terminal of the power switch and a second terminal connected to said capacitor, respectively, for supplying a charging current to said capacitor during said period of time.
Claim 3
Dependent Claim
17 words
An acoustic amplifier according to claim 1, wherein said first amplifier circuit comprises a differential amplifier circuit.
Claim 4
Dependent Claim
99 words
An acoustic amplifier according to claim 2, further including voltage divider circuits and wherein said first and second means are comprised of a transistor circuit having a reference potential input, a control input and a pair of outputs, said reference potential input and said control input being connected between said voltage divider circuits, said voltage divider circuits supplying a voltage produced by dividing a supply voltage to each of said inputs, and said power switch, and said pair of outputs being connected to an input of said differential amplifier circuit and the input of said second amplifier circuit, respectively.
Claim 5
Dependent Claim
95 words
An acoustic amplifier according to claim 2, further including a voltage divider circuit, and wherein said first and second means are comprised of a transistor circuit having a reference potential input, a control input and an output, said reference potential input being connected to One side of said differential amplifier circuit, said control input being connected between said voltage divider circuit, said voltage divider circuit supplying a voltage produced by dividing a supply voltage to said control input, and said power switch and the output being connected to an input of said differential amplifier circuit.
Claim 6
Dependent Claim
75 words
An acoustic amplifier according to claim 2, wherein said second means comprises a first diode connected between a first reference point on a voltage divider circuit directly connected to said power switch and an input of said diffential amplifier circuit, and said first means comprises a transistor circuit including a transistor and a diode connected thereto, coupled between a second reference point on said voltage divider circuit and the input of said second amplifier circuit.
Claim 7
Dependent Claim
17 words
An acoustic amplifier according to claim 2, wherein said second amplifier circuit comprises a push-pull amplifier circuit.
Claim 8
Dependent Claim
42 words
An acoustic amplifier according to claim 6, wherein said second amplifier circuit further includes a driver circuit connected to said push-pull amplifier circuit, and further comprising a level shift circuit coupling the output of said differential amplifier circuit to said driver circuit.
Claim 9
Dependent Claim
44 words
An acoustic amplifier according to claim 6, further including a ripple filter circuit connected to said power switch, and wherein said feedback path comprises a resistor-capacitor network connected between the output of said push-pull amplifier circuit and an input of said differential amplifier circuit.
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) | 1978-09-08 | 1979-03-10 | 1979-09-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-09-08 | 1983-03-10 | 1983-09-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-09-08 | 1987-03-10 | 1987-09-09 | $7700.00 | Window Closed / Lapsed |