US3783192A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Decoder for use in matrix four-channel system
Assignee: Sansui Electric Co Ltd
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Filing: 1972-12-21
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Granted: 1974-01-01
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Expires: 1992-12-21
Abstract
Abstract A decoder for use in an SQ matrix four-channel system comprises first and second matrix circuits for forming a difference signal and a sum signal of the first and second channel signals respectively. The output signals from the first and second matrix circuits are supplied to third and fourth matrix circuits to produce reproduced rear signals which are supplied to two rear loudspeakers disposed to the rear of a listener. Between the first and second matrix circuits and third and fourth matrix circuits is connected at least one phase shifter which gives a phase difference of about 90* between the output signals from the first and second matrix circuits. The first and second channel signals are supplied to respective ones of two front loudspeakers disposed in the front of the listener.
Inventors
- 👤 S Takahashi
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-26 14:11
CPC Classifications
H; H04; H04S; H04S3/00; H04S3/02
Claims Analysis
Total Claims: 16
Claim 1
Independent Claim
280 words
A decoder for decoding a first channel signal normally containing one front signal and two rear signals having a phase difference of 90*, and a second channel signal normally containing another front signal and said two rear signals having a phase difference of 90* to produce reproduced four-channel signals which are to be supplied to two front loudspeakers and two rear loudspeakers which are disposed about a listener, said decoder comprising: a first matrix circuit connected to receive said first and second channel signals for forming a difference signal between said first and second channel signals; a second matrix circuit connected to receive said first and second channel signals for forming a sum signal of said first and second channel signals; a third matrix circuit connected to receive the output signals of said first and second matrix circuits for additively combining said output signal to form an output signal to be supplied to one of said rear loudspeakers; a fourth matrix circuit connected to receive the output signals from said first and second matrix circuits for subtractively combining said output signals to form an output signal to be supplied to the other of said rear loud-speakers; at least one phase shifter connected between said first and second matrix circuits and said third and fourth matrix circuits for providing a phase difference of about 90* between the outputs from said first and second matrix circuits; first and second coupling means for coupling said first and second channel signals to respective ones of said two front loudspeakers; and third and fourth coupling means for coupling the outputs from said third and fourth matrix circuits to respective ones of said two rear loudspeakers.
Claim 2
Dependent Claim
280 words
A decoder for decoding a first channel signal normally containing one front signal and two rear signals having a phase difference of 90*, and a second channel signal normally containing another front signal and said two rear signals having a phase difference of 90* to produce reproduced four-channel signals which are to be supplied to two front loudspeakers and two rear loudspeakers which are disposed about a listener, said decoder comprising: a first matrix circuit connected to receive said first and second channel signals for forming a difference signal between said first and second channel signals; a second matrix circuit connected to receive said first and second channel signals for forming a sum signal of said first and second channel signals; a third matrix circuit connected to receive the output signals of said first and second matrix circuits for additively combining said output signal to form an output signal to be supplied to one of said rear loudspeakers; a fourth matrix circuit connected to receive the output signals from said first and second matrix circuits for subtractively combining said output signals to form an output signal to be supplied to the other of said rear loud-speakers; at least one phase shifter connected between said first and second matrix circuits and said third and fourth matrix circuits for providing a phase difference of about 90* between the outputs from said first and second matrix circuits; first and second coupling means for coupling said first and second channel signals to respective ones of said two front loudspeakers; and third and fourth coupling means for coupling the outputs from said third and fourth matrix circuits to respective ones of said two rear loudspeakers.
Claim 3
Dependent Claim
100 words
The decoder according to claim 1 which further comprises a second phase shifter for coupling said first channel signal to said first matrix circuit and said first coupling means; and a third phase shifter for coupling said second channel signal to said first matrix circuit and to said second coupling means, said second and third phase shifters having the same phase shift characteristic over the entire audio frequency range and said first phase shifter having a phase shift characteristic which is different by about 90* from those of said second and third phase shifters over the entire audio frequency range.
Claim 4
Dependent Claim
79 words
The decoder according to claim 1 wherein first and second phase shifters are connected between said first and second matrix circuits and said third and fourth matrix circuits, said first phase shifter is connected to receive the output from said first matrix circuit, said second phase shifter is connected to receive the output from said second matrix circuit and said first and second phase shifters have phase shift characteristics of about 90* difference over the entire audio frequency range.
Claim 5
Dependent Claim
39 words
The decoder according to claim 1 wherein said phase shifter has a phase shift characteristic such that it provides a 90* phase difference between the input and output signals at a given frequency in the entire audio frequency range.
Claim 6
Dependent Claim
81 words
The decoder according to claim 4 wherein said phase shifter comprises a transistor including a base electrode, a collector electrode and an emitter electrode, and a series circuit connected across the collector and emitter electrodes of said transistor, said series circuit including a capacitor and resistor, and wherein the base electrode of said transistor is connected to receive said input signal and said output signal is taken out from the junction between said capacitor and said resistor of said series circuit.
Claim 7
Dependent Claim
204 words
The decoder according to claim 1 which further comprises a fifth matrix circuit connected to receive said first and second channel signals for forming a sum signal of said first and second channel signals; a sixth matrix circuit connected to receive said first and second channel signals for forming a difference signal of said first and second channel signals; a seventh matrix circuit connected to receive the output signals from said fifth and sixth matrix circuits for forming a signal to be supplied to said first coupling means; an eighth matrix circuit connected to receive the output signals from said fifth and sixth matrix circuits for forming a signal to be supplied to said second coupling means; a control unit for detecting the phase relationship between said first and second channel signals to form first and second control signals; a first variable gain amplifier connected to the output side of said sixth matrix circuit to vary the amplification factor thereof in response to said first control signal from said control unit; and a second variable gain amplifier connected to the output side of said second matrix circuit to vary the amplification factor thereof in response to said second control signal from said control unit.
Claim 8
Dependent Claim
121 words
The decoder according to claim 6 wherein said first variable gain amplifier includes means responsive to said first control signal from said control unit for setting the amplification factor of said first variable gain amplifier to be substantially unity when said first and second channel signals are in phase, and to be substantially zero when said first and second signals have opposite phases, and said second variable gain amplifier includes means responsive to said second control signal from saiD control unit for setting the amplification factor of said second variable gain amplifier to be substantially zero when said first and second channel signals are in phase, and to be substantially unity when said first and second channel signals have opposite phases.
Claim 9
Dependent Claim
24 words
The decoder according to claim 1 wherein one of said third and fourth matrix circuits is an adder and the other is a subtracter.
Claim 10
Dependent Claim
29 words
The decoder according to claim 8 wherein said adder includes two equally valued resistors and said subtracter includes a series connection of an inverter and two equally valued resistors.
Claim 11
Dependent Claim
22 words
The decoder according to claim 6 wherein said seventh matrix circuit is an adder, and said eighth matrix circuit is a subtracter.
Claim 12
Dependent Claim
33 words
The decoder according to claim 10 wherein said adder includes a series connection of two equally valued resistors, and said subtracter includes a series connection of an inverter and two equally valued resistors.
Claim 13
Dependent Claim
143 words
A signal converting apparatus for converting two channel signals into four channel output signals which are coupled to four loudspeakers disposed around a listener, said apparatus comprising: first means for producing a sum signal of said two channel signals; second means for producing a difference signal of said two channel signals; third means for additively combining only said sum and difference signals to produce a first output signal; fourth means for subtractively combining only said sum and difference signals to produce a second output signal; fifth means for additively combining only said sum and difference signals to produce a third output signal; sixth means for subtractively combining only said sum and difference signals to produce a fourth output signal; and seventh means for introducing a predetermined phase difference between said sum and difference signals which are supplied to said fifth and sixth means.
Claim 14
Dependent Claim
143 words
A signal converting apparatus for converting two channel signals into four channel output signals which are coupled to four loudspeakers disposed around a listener, said apparatus comprising: first means for producing a sum signal of said two channel signals; second means for producing a difference signal of said two channel signals; third means for additively combining only said sum and difference signals to produce a first output signal; fourth means for subtractively combining only said sum and difference signals to produce a second output signal; fifth means for additively combining only said sum and difference signals to produce a third output signal; sixth means for subtractively combining only said sum and difference signals to produce a fourth output signal; and seventh means for introducing a predetermined phase difference between said sum and difference signals which are supplied to said fifth and sixth means.
Claim 15
Dependent Claim
16 words
The signal converting apparatus according to claim 12 wherein said predetermined phase difference is about 90*.
Claim 16
Dependent Claim
87 words
The signal converting apparatus according to claim 12 further comprising: eighth means for detecting phase relationship between said two channel signals to produce first and second control signals; ninth means responsive to said first control signal from said eighth means for varying the level of said difference signal which is supplied to said third and fourth means; and tenth means responsive to said second control signal from said eighth means for varying the level of said sum signal which is supplied to said fifth and sixth means.
References Cited (Backward Citations)
US3632886A
Cited
US3708631A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-12-31 | 1977-07-02 | 1978-01-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-12-31 | 1981-07-02 | 1982-01-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-12-31 | 1985-07-02 | 1986-01-01 | $7700.00 | Window Closed / Lapsed |