US3798562A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Expanding circuit in a compression and expansion system
Assignee: Victor Company of Japan Ltd
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Filing: 1972-10-02
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Granted: 1974-03-19
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Expires: 1992-10-02
Abstract
Abstract An expanding circuit is provided for a compression and expansion system. It operates to expand signals compressed in the compression system responsive to a control system of two loops, with respect to the medium-frequency component and the highfrequency component of the signals transmitted to the expanding circuit. The expanding circuit has a control system of only a single loop for varying the gain an input signal by means of control signals obtained in accordance with the levels of the medium-frequency band and the high-frequency band. An attenuation circuit imparts to signals of gains thus varied, characteristics whereby the level of the high-frequency band is attenuated more than that of the medium-frequency band.
Inventors
- 👤 H Sekiguchi
- 👤 N Ohsaki
- 👤 Y Okabe
- 👤 N Takahashi
- 👤 M Kasuga
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 16:02
CPC Classifications
H; H04; H04B; H04B1/00; H04B1/62; H04B1/64; H03; H03G; H03G7/00; H03G7/06; H03G7/08; H03G9/00; H03G9/02; H03G9/025
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
248 words
A single loop expandor circuit for use in a compression and expansion system, said expandor circuit comprising: an input terminal to which is applied a signal produced in the compression system by compressing the medium frequency range component of a sound signal, said compressing system comprising means responsive to a control signal derived through a control loop in accordance with the level of the medium frequency range component for compressing the medium frequency range, and means for compressing the high frequency range component of the sound signal responsive to another control signal derived through another control loop in accordance with the level of the high frequency range component; said single loop comprising feedback filter means for filtering and extracting medium and high frequency range signal components from the signal applied to said input terminal; means for amplifying the signal applied to said input terminal; control signal forming means for rectifying the signal extracted by said filter means and forming a control signal voltage; variable gain means responsive to said formed control signal for controlling the gain of said amplifying means to selectively expand the medium and high frequency range signal components included in the signal applied to said input terminal; an attenuation circuit means responsive to the output signal of said amplifying means for attenuating the high frequency range signal component more than the medium frequency range signal component by a predetermined decibel level; and an output terminal for providing an output signal responsive to said attenuation circuit.
Claim 2
Dependent Claim
248 words
A single loop expandor circuit for use in a compression and expansion system, said expandor circuit comprising: an input terminal to which is applied a signal produced in the compression system by compressing the medium frequency range component of a sound signal, said compressing system comprising means responsive to a control signal derived through a control loop in accordance with the level of the medium frequency range component for compressing the medium frequency range, and means for compressing the high frequency range component of the sound signal responsive to another control signal derived through another control loop in accordance with the level of the high frequency range component; said single loop comprising feedback filter means for filtering and extracting medium and high frequency range signal components from the signal applied to said input terminal; means for amplifying the signal applied to said input terminal; control signal forming means for rectifying the signal extracted by said filter means and forming a control signal voltage; variable gain means responsive to said formed control signal for controlling the gain of said amplifying means to selectively expand the medium and high frequency range signal components included in the signal applied to said input terminal; an attenuation circuit means responsive to the output signal of said amplifying means for attenuating the high frequency range signal component more than the medium frequency range signal component by a predetermined decibel level; and an output terminal for providing an output signal responsive to said attenuation circuit.
Claim 3
Dependent Claim
107 words
An expandor circuit according to claim 1 in which said amplifying means comprises an amplifying transistor connected for amplifying the signal applied to said input terminal, said variable gain means having a semiconductor element connected by way of an impedance element to the emitter circuit of said amplifying transistor and having an internal resistance value varied in accordance with said control signal voltage, said filter means being connected to filter a signal derived from the emitter circuit of said amplifying transistor, and said control signal forming means being connected to rectify and smooth the signal filtered by said filter means thereby to form the control signal voltage.
Claim 4
Dependent Claim
153 words
An expandor circuit according to claim 1 in which said amplifying means comprises an amplifying transistor connected for amplifying the signal applied to said input terminal, said variable gain means including a control transistor having a collector connected by way of an impedance element to the emitter of said amplifying transistor and a base to which said control signal voltage is applied whereby the resistance across the collector and emitter thereof is made variable as a function of said control signal voltage, and circuit means for applying the collector voltage of said amplifying transistor to the base of said control transistor, said collector voltage of the amplifying transistor being of opposite phase relative to the collector voltage of said control transistor and functioning to cancel variation of the resistance value of said control transistor with respect to the variation of the collector potential thereof and to reduce the distortion of the control transistor.
Claim 5
Dependent Claim
52 words
An expandor circuit according to claim 1 and means whereby said expandor has an overall frequency characteristic wherein the level of the high frequency band component of a signal has a alrger attenuation of approximately from 2 dB to 7 dB as compared to the attenuation of the medium frequency band component.
Claim 6
Dependent Claim
71 words
An expandor circuit according to claim 1 and means whereby said expandor has an overall frequency characteristic wherein the gain characteristics of the low and medium frequency bands are substantially flat when the levels of the medium and high frequency band components of the input signal are very low, and means for attenuating only the high frequency band by approximately 2 dB to 7 dB more than said medium frequency band.
Claim 7
Dependent Claim
68 words
An expandor circuit according to claim 1 which further comprises a first amplifying transistor means for amplifying signals applied to said input terminal and a second amplifying transistor means for amplifying signals from said first amplifying transistor means, and said filtering means comprises a capacitor connected to the collector of said second amplifying transistor for providing a low-cutoff filter for cutting off only the low frequency band component.
Claim 8
Dependent Claim
82 words
An expandor circuit according to claim 1 which further comprises an amplifying transistor means for amplifying the signals applied to said input terminal, said transistor having an emitter, and said variable gain means comprises a control field-effect transistor having a gate, drain, and source connected by way of an impedance element to the emitter of said amplifying transistor, the resistance value measured across said source and drain being varied responsive to an application of said control signal voltage to the gate thereof.
Claim 9
Dependent Claim
45 words
An expandor circuit according to claim 7 which further comprises an AC feedback circuit comprising a resistor and a capacitor connected across the source and gate of said field-effect transistor, said capacitor functioning as a filter to improve the operational linearity of said field-effect transistor.
Claim 10
Dependent Claim
49 words
An expandor circuit according to claim 1 wherein said variable gain means comprises means responsive to a decrease in the control signal voltage for controlling the gain of said amplifying means to attenuate the medium and high frequency signal components included in the signal applied to said input terminal.
Claim 11
Dependent Claim
20 words
An expandor circuit according to claim 1 wherein said predetermined decibel level is between substantially 2 dB and 7 dB.
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) | 1977-03-18 | 1977-09-17 | 1978-03-19 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-03-18 | 1981-09-17 | 1982-03-19 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-03-18 | 1985-09-17 | 1986-03-19 | $7700.00 | Window Closed / Lapsed |