Four-channel reproducing system

Claim 2

A sound reproducing system for reproducing stereophonically related first and second channel signals from a two-channel signal source by means of a four-channel reproducing system, said system comprising a combination of: first means connected to receive the first and second channel signals for producing first and second composite signals by combining the first and second channel signals with such amplitude and phase relationships that the first composite signal contains a greater proportion of the first channel signal and a smaller proportion of the second channel signal, the second composite signal contains a greater proportion of the second channel signal and a smaller proportion of the first channel signal, and for producing phase differences between the first and second composite signals with respect to the first and second channel signals respectively which vary as a function of frequency of the first and second channel signals; control means connected to receive the first and second composite signals for producing control outputs the levels of which vary depending on the phase relationship between the first and second composite signals; and second means connected to receive, as first and second input signals, the first and second composite signals or the first and second channel signals for producing four-channel output signals by combining the first and second input signals, said second means being operative to produce the four-channel output siganls varying at least mixing ratios of the first and second input signals depending on the levels of the control outputs of said control means.

Claim 3

A sound reproducing system according to claim 1 wherein the phase differences between the first and second composite signals with respect to the first and second channel signals represent substantially 90* at a low frequency and substantially 180* at a high frequency, respectively.

Claim 4

A sound reproducing system according to claim 1 wherein the amplitude levels of the second and first channel signals contained in the first and second composite signals vary as a function of frequency, respectively.

Claim 5

A sound reproducing system according to claim 1 wherein said first means comprises first and second phase shifter means each including a transistor having a collector, and emitter and a base, and a resistor and a capacitor connected in series across the collector and emitter of the transistor; and a resistor means connecting the emitter of transistor in said first phase shifter means with the emitter of transistor in said second phase shifter means, the bases of transistors in said first and second phase shifter means being connected to receive the first and second channel signals, respectively, the resistor-capacitor junctions in said first and second phase shifter means being adapted to derive the first and second composite signals, respectively.

Claim 6

A sound reproducing system according to claim 1 whereIn said second means comprises a first differential amplifier having first and second output terminals deriving a pair of output signals and first and second input terminals, the first input terminal being connected to receive the first input signal; phase reversing means for reversing the phase of the second input signal; means for coupling the output of said phase reversing means to the second input terminal of said first differential amplifier; a second differential amplifier having first and second output terminals deriving another pair of output signals and first and second input terminals connected to receive the first and second input signals, respectively; and means for controlling the gains of said first and second differential amplifiers in opposite relationship in accordance with the levels of control outputs from said control means.

Claim 7

A second reproducing system according to claim 1 wherein said second means comprises means connected to receive the first and second input signals A and B for producing a first output signal substantially proportional to (1+f)A + (1-f)B where f represents a first variable matrix coefficient; means connected to receive the first and second input signals A and B for producing second output signal substantially proportional to (1+f)B + (1-f)A; means connected to receive the first and second input signals A and B for producing a third output signal substantially proportional to (1+b)A - (1-b)B where b represents a second variable matrix coefficient; means connected to receive the first and second input signals A and B for producing a fourth output signal substantially proportional to (1+b)B - (1-b)A; and means for varying the matrix coefficients f and b in opposite relationship depending on the levels of control outputs from said control means.

Claim 8

A sound reproducing system according to claim 1 wherein said control means includes a phase discriminator for detecting the phase difference between the first and second composite signals.

Claim 9

A sound reproducing system according to claim 1 wherein said control means includes a level comparator for comparing the levels of sum and difference of the first and second composite signals.

Claim 10

A sound reproducing system according to claim 1 further comprising further control means for producing control outputs in response to the first and second composite signals; and wherein said second means comprises means connected to receive the first and second input signals A and B for producing a first output signal substantially proportional to (1+f+ Square Root 2)A + (1-f + Square Root 2l)B, where f and l represent variable matrix coefficients; means connected to receive the first and second input signals A and B for producing a second output signal substantially proportional to (1+f+ Square Root 2)B + (1-f+ Square Root 2r)A, where r represent a variable matrix coefficient; means connected to receive the first and second input signals A and B for producing a third output signal substantially proportional to (1+b+ Square Root 2)A - (1-b+ Square Root 2l)B, where b represent a variable matrix coefficient; means connected to receive the first and second input signals A and B for producing a fourth output signal substantially proportional to (1+b+ Square Root 2)B - (1-b+ Square Root 2r)A; and means for varying the matrix coefficients f and b in opposite relationship depending on the levels of control outputs from said control means; and means for varying the matrix coefficients l and r in opposite relationship depending on the levels of control outputs from said further control means.

Claim 11

A sound reproducing system according to claim 9 wherein said further control means includes a phase discriminator for detecting pHase difference between sum and difference of the first and second composite signals.

Claim 12

A sound reproducing system according to claim 9 wherein said further control means includes a level comparator for comparing the levels of the first and second composite signals.

Claim 13

A sound reproducing system for reproducing stereophonically related first and second channel signals from a two-channel signal source by means of a four-channel reproducing system, said system comprising a combination of: first means connected to receive the first and second channel signals for producing first and second composite signals by combining the first and second channel signals with such amplitude and phase relationships that the first composite signal contains a greater proportion of the first channel signal and a smaller proportion of the second channel signal, the second composite signal contains a greater proportion of the second channel signal and a smaller proportion of the first channel signal, and for producing phase differences between the first and second composite signals with respect to the first and second channel signals respectively vary as a function of frequency of the first and second channel signals; first control means connected to receive the first and second composite signals for producing control outputs the levels of which vary depending on the phase relationship between the first and second composite signals; second control means connected to receive the first and second composite signals for producing control outputs the levels of which vary depending on the phase relationship between sum and difference of the first and second composite signals; second means connected to receive, as first and second input signals, the first and second composite signals or the first and second channel signals for producing four-channel output signals by combining the first and second input signals, said second means including means for varying the mixing ratios of and polarity relationship between the first and second input signals in producing the output signals depending on the levels of control outputs from said first control means; and means for varying the mixing ratios of the first and second input signals in producing the output signals depending on the levels of control outputs from said second control means.

Claim 14

A sound reproducing system for reproducing stereophonically related first and second channel signals from a two-channel signal source by means of a four-channel reproducing system, said system comprising a combination of: first means connected to receive the first and second channel signals for producing first and second composite signals by combining the first and second channel signals with such amplitude and phase relationships that the first composite signal contains a greater proportion of the first channel signal and a smaller proportion of the second channel signal, the second composite signal contains a greater proportion of the second channel signal and a smaller proportion of the first channel signal, and for producing phase differences between the first and second composite signals with respect to the first and second channel signals respectively vary as a function of frequency of the first and second channel signals; first control means connected to receive the first and second composite signals for producing control outputs the levels of which vary depending on the phase relationship between the first and second composite signals; second control means connected to receive the first and second composite signals for producing control outputs the levels of which vary depending on the phase relationship between sum and difference of the first and second composite signals; second means connected to receive, as first and second input signals, the first and second composite signals or the first and second channel signals for producing four-channel output signals by combining the first and second input signals, said second means including means for varying the mixing ratios of and polarity relationship between the first and second input signals in producing the output signals depending on the levels of control outputs from said first control means; and means for varying the mixing ratios of the first and second input signals in producing the output signals depending on the levels of control outputs from said second control means.

Claim 15

A sound reproducing system for reproducing stereophonically related first and second channel signals from a two-channel signal source by means of a four-channel reproducing system, said system comprising a combination of: first means connected to receive the first and second channel signals for producing first and second composite signals by combining the first and second channel signals with such amplitude and phase relationships that the first composite signal contains a greater proportion of the first channel signal and a smaller proportion of the second channel signal, the second composite signal contains a greater proportion of the second channel signal and a smaller proportion of the first channel signal, and for producing phase differences between the first and second composite signals with respect to the first and second channel signals respectively vary as a function of frequency of the first and second channel signals; control means connected to receive the first and second composite signals for producing control outputs the levels of which vary depending on the phase relationship between the first and second composite signals; and second means connected to receive, as first and second input signals, the first and second composite signals or the first and second channel signals for producing four-channel output signals by combining the first and second input signals, said second means including means for varying the mixing ratios of and polarity relationship between the first and second input signals in producing the output signals depending on the levels of control outputs from said control means.

Claim 16

A sound reproducing system for reproducing stereophonically related first and second channel signals from a two-channel signal source by means of a four-channel reproducing system, said system comprising a combination of: first means connected to receive the first and second channel signals for producing first and second composite signals by combining the first and second channel signals with such amplitude and phase relationships that the first composite signal contains a greater proportion of the first channel signal and a smaller proportion of the second channel signal, the second composite signal contains a greater proportion of the second channel signal and a smaller proportion of the first channel signal, and for producing phase differences between the first and second composite signals with respect to the first and second channel signals respectively vary as a function of frequency of the first and second channel signals; control means connected to receive the first and second composite signals for producing control outputs the levels of which vary depending on the phase relationship between the first and second composite signals; and second means connected to receive, as first and second input signals, the first and second composite signals or the first and second channel signals for producing four-channel output signals by combining the first and second input signals, said second means including means for varying the mixing ratios of and polarity relationship between the first and second input signals in producing the output signals depending on the levels of control outputs from said control means.