Signal converting systems for use in stereo reproducing systems

Claim 2

A signal converting system for reproducing stereophonically related first and second channel signals from a two-channel signal source by means of a four-channel stereo reproducing system, said system comprising a combination of: first signal converting 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; a control unit responsive to the phase relationship between the first and second composite signals for producing first and second control outputs, the levels of which vary in opposite relationship; and second signal converting means connected to receive the first and second channel signaLs for producing four-channel output signals by combining the first and second channel signals, said second signal converting means including means for controlling at least a relative amplitude ratio between the first and second channel signals contained in each of a pair of output signals in accordance with the level of said first control output and means for controlling at least a relative amplitude ratio between the first and second channel signals contained in each of another pair of output signals in accordance with the level of said second control output.

Claim 3

A signal converting system according to claim 1 wherein the first composite signal is a sum signal of the first and second channel signals which contains the first channel signal at a larger amplitude level and the second channel signal at a smaller amplitude level, and the second composite signal is a sum signal of the first and second channel signals which contains the first channel signal at a smaller amplitude level and the second channel signal at a larger amplitude level.

Claim 4

A signal converting system according to claim 1 wherein the first composite signal is a difference signal of the first and second channel signals which contains the first channel signal at a larger amplitude level and the second channel signal at a smaller amplitude level, and the second composite signal is a difference signal of the first and second channel signals which contains the first channel signal at a smaller amplitude level and the second channel signal at a larger amplitude level.

Claim 5

A signal converting system according to claim 1 wherein said second signal converting means comprises: a first differential amplifier having first and second output terminals deriving a pair of output signals and first and second input terminals, said first input terminal being connected to receive the first channel signal; phase reversing means for reversing the phase of the second channel signal; means for coupling the output of said phase reversing means to said second input terminal of said first differential amplifier; means for controlling the gain of said first differential amplifier in accordance with the level of said first control output; 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 said first and second channel signals respectively; and means for controlling the gain of said second differential amplifier in accordance with the level of said control output.

Claim 6

A signal converting system according to claim 1 wherein said second signal converting means comprises: means connected to receive the first and second channel signals L and R for producing a first output signal substantially proportional to (1+f)L+(1-f)R where f represents a first variable matrix coefficient; means connected to receive the first and second channel signals L and R for producing a second output signal substantially proportional to (1+f)R+ (1-f)L; means connected to receive the first and second channel signals L and R for producing a third output signal substantially proportional to (1+b)L-(1-b) R where b represents a second variable matrix coefficient; means connected to receive the first and second channel signals L and R for producing a third output signal substantially proportional to (1+b)R- (1-b)L; means for varying the first variable matrix coefficient f in accordance with the level of said first control output; and means for varying the second variable matrix coefficient b in accordance with the level of said second control output.

Claim 7

A signal converting system according to claim 1 which further comprises a further control unit for producing third and fourth control outputs, the levels of whicH vary in opposite relationship in response to the first and second composite signals, and wherein said second signal converting means comprises: means connected to receive the first and second channel signals L and R for producing a first output signal substantially proportional to (1+f+ Square Root 2)L+ (1-f+ Square Root 2l )L; where f and l represent variable matrix coefficients; means connected to receive the first and second channel signals L and R for producing a second output signal substantially proportional to (1+f+ Square Root 2)R+ (1-f+ Square Root 2r)L, where r represents a variable matrix coefficient; means connected to receive the first and second chaanel signals L and R for producing a third output signal substantially proportional to (1+b+ Square Root 2)L- (1-b+ Square Root 2l)R, where b represents a variable matrix coefficient; means connected to receive the first and second channel signals L and R for producing a fourth output signal substantially proportional to (1+b+ Square Root 2)R-(1-b+ Square Root 2rL; means for varying the coefficient f in accordance with the level of said first control output means for varying the coefficient b in accordance with the level of said second control output; means for varying the coefficient l in accordance with the level of said third control output; and means for varying the coefficient r in accordance with the level of said fourth control output.

Claim 8

A signal converting system according to claim 1 wherein said control unit comprises a phase discriminator for detecting the phase difference between the first and second composite signals.

Claim 9

A signal converting system according to claim 1 wherein said control unit comprises a level comparator for comparing levels of the sum and difference signals of the first and second composite signals.

Claim 10

A signal converting system according to claim 6 wherein said further control unit comprises a phase discriminator for detecting phase difference between the sum and difference signals of the first and second composite signals.

Claim 11

A signal converting system according to claim 6 wherein said further control unit comprises a level comparator for comparing the levels of the first and second composite signals.

Claim 12

A signal converting system for reproducing stereophonically related first and second channel signals from a two-channel signal source by means of a four-channel stereo reproducing system, said system comprising a combination of: first signal converting 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; a control unit responsive to the phase relationship between the first and second composite signals for producing first and second control outputs, the levels of which vary in opposite relationship; and second signal converting means connected to receive the first and second composite signals for producing four-channel output signals by combining the first and second composite signals, said second signal converting means including means for controlling at least a relative amplitude ratio between the first and second composite signals contained in each of a pair of output signals in accordance with the level of said first control output and means for controlling at least a relative amplitude ratio between the first and second composite signals contained in each of another pair of output signals in accordance with the level of said second control output.

Claim 13

A signal converting system for reproducing stereophonically related first and second channel signals from a two-channel signal source by means of a four-channel stereo reproducing system, said system comprising a combination of: first signal converting 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; a control unit responsive to the phase relationship between the first and second composite signals for producing first and second control outputs, the levels of which vary in opposite relationship; and second signal converting means connected to receive the first and second composite signals for producing four-channel output signals by combining the first and second composite signals, said second signal converting means including means for controlling at least a relative amplitude ratio between the first and second composite signals contained in each of a pair of output signals in accordance with the level of said first control output and means for controlling at least a relative amplitude ratio between the first and second composite signals contained in each of another pair of output signals in accordance with the level of said second control output.

Claim 14

A signal converting system according to claim 11 wherein the first composite signal is a sum signal of the first and second channel signals which contains the first channel signal at a larger amplitude level and the second channel signal at a smaller amplitude level, and the second composite signal is a sum signal of the first and second channel signals which contains the first channel signal at a smaller amplitude level and the second channel signal at a larger amplitude level.

Claim 15

A signal converting system according to claim 11 wherein the first composite signal is a difference signal of the first and second channel signals which contains the first channel signal at a larger amplitude level and the second channel signal at a smaller amplitude level, and the second composite signal is a difference signal of the first and second channel signals which contains the first channel signal at a smaller amplitude level and the second channel signal at a larger amplitude level.

Claim 16

A signal converting system according to claim 11 wherein said second signal converting means comprises: a first differential amplifier having first and second output terminals deriving a pair of output signals and first and second input terminals, said first input terminal being connected to receive the first composite signal; phase reversing means for reversing the phase of the second composite signal; means for coupling the output of said phase reversing means to said second input terminal of said first differential amplifier; means for controlling the gain of said first differential amplifier in accordance with the level of said first control output; 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 said first and second composite signals respectively; and means for controlling the gain of said second differential amplifier in accordance with the level of said second control output.

Claim 17

A signal converting system according to claim 11 wherein said second signal converting means comprises: means connected to receive the first and second composite signals L'' and R'' for producing a first output signal substantially proportional to (1+f)L+ + (1-f)R'' where f represents a first variable matrix coefficient; means connected to receive the first and second composite signals L'' and R'' for producing a second output signal substantially proportional to (1+f)R'' +(1-f)L''; means connected to receive the first and second composite signals L'' and R'' for producing a third output signal substantially proportional to (1+b)L'' -(1-b)R'' where b represents a second variable matrix coefficient; means connected to receive the first and second composite signals L'' and R'' for producing a third output signal substantially proportional to (1+b)R''-(1-b)L'' ; means for varying the first variable matrix coefficient f in accordance with the level of said first control output; and means for varying the second variable matrix coefficient b in accordance with the level of said second control output.

Claim 18

A signal converting system according to claim 11 which further comprises a further control unit for producing third and fourth control outputs, the levels of which vary in opposite relationship in response to the first and second composite signals, and wherein said second signal converting means comprises: means connected to receive the first and second composite signals L'' and R'' for producing a first output signal substantially proportional to (1+f+ Square Root 2)L''+(1-f+ Square Root 2l)R'', where f and l represent variable matrix coefficients; means connected to receive the first and second composite signals L'' and R'' for producing a second output signal substantially proportional to (1+f+ Square Root 2)R'' +(1-f+ Square Root 2r)L'', where r represents A variable matrix coefficient; means connected to receive the first and second composite signals L'' and R'' for producing a third output signal substantially proportional to (1+b+ Square Root 2)L''-(1-b+ Square Root 2l)R'', where b represents a variable matrix coefficient; means connected to receive the first and second composite signals L'' and R'' for producing a fourth output signal substantially proportional to (1+b+ Square Root 2)R'' -(1-b+ Square Root 2r)L''; means for varying the coefficient f in accordance with the level of said first control output; means for varying the coefficient b in accordance with the level of said second control output; means for varying the coefficient l in accordance with the level of said third control output; and means for varying the coefficient r in accordance with the level of said fourth control output.

Claim 19

A signal converting system according to claim 11 wherein said control unit comprises a phase discriminator for detecting the phase difference between the first and second composite signals.

Claim 20

A signal converting system according to claim 11 wherein said control unit comprises a level comparator for comparing levels of the sum and difference signals of the first and second composite signals.

Claim 21

A signal converting system according to claim 16 wherein said further control unit comprises a phase discriminator for detecting phase difference between the sum and difference signals of the first and second composite signals.

Claim 22

A signal converting system according to claim 16 wherein said further control unit comprises a level comparator for comparing the levels of the first and second composite signals.