Encoding system for forming two-channel signals from a plurality of sound signals

Claim 2

An encoding system in which at least first to fourth sound signals desired to be coupled mainly to first to fourth loudspeakers surrounding a listener are utilized in forming first and second channel signals, and first and second sound signals are coupled to the first channel in large and small proportions respectively with a reference phase shift amount, second and first sound signals are coupled to the second channel in large and small proportions respectively with the reference phase shift amount, third and fourth sound signals are coupled to the first channel in large and small proportions respectively with a phase shift amount of the reference phase shift amount plus 90*, and the fourth and third sound signals are coupled to the second channel in large and small proportions with a phase shift amount of the reference phase shift amount minus 90*, the improvement comprising means for coupling a fifth sound signal desired to have its sound image localized between said first and third loudspeakers to the first channel in a large proportion with the reference phase shift amount; means for coupling said fifth sound signal to the second channel in a small proportion with a phase shift amount having substantially 90* phase difference with respect to the reference phase shift amount; means for coupling a sixth sound signal desired to have its sound image localized between the second and fourth loudspeakers to the second channel in a large proportion with the reference phase shift amount; and means for coupling said sixth sound signal to the first channel in a small proportion with a phase shift amount having substantially 90* phase difference with respect to the reference phase shift amount.

Claim 3

An encoding system for encoding at least first to fourth sound signals desired to be coupled mainly to first to fourth loudspeakers surrounding a listener into first and second channel signals, comprising first means for mixing the first sound signal in a large proportion and the second sound signal in a small proportion; second means for mixing the second sound signal in a large proportion and the first sound signal in a small proportion; third means for mixing the third sound signal in a large proportion and a fourth sound signal in a small proportion; fourth means for mixing the fourth sound signal in a large proportion and the third sound signal in a small proportion; a first phase shifter coupled to the output of said first means; a second phase shifter coupled to the output of said second means and having substantially the same phase shifting characteristic as said first phase shifter over the entire audible frequency range; a third phase shifter coupled to the output of said third means and having a phase shifting characteristic of plus 90* difference with respect to those of said first and second phase shifters; a fourth phase shifter coupled to the output of said fourth means and having a phase shifting characteristic of minus 90* difference with respect to those of said first and second phase shifters; means for coupling a fifth sound signal desired to have its sound image localized between the first and third loudspeakers to the input of said first phase shifter in a large proportion; means for coupling said fifth sound signal to the input of said fourth phase shifter in a small proportion; means for coupling a sixth sound signal desired to have its sound image localized between the second and fourth loudspeakers to the input of said second phase shifter in a large proportion; means for coupling said sixth sound signal to the input of said third phase shifter in a small proportion; means for mixing output signals from said first and third phase shifters; and means for mixing output signals from said second and fourth phase shifters.

Claim 4

An encoding system for encoding at least first to fourth sound signals desired to be coupled mainly to first to fourth loudspeakers surrounding a listener into first and second channel signals, comprising first means for mixing the first sound signal in a large proportion and the second sound signal in a small proportion; second means for mixing the second sound signal in a large proportion and the first sound signal in a small proportion; third means for mixing the third sound signal in a large proportion and a fourth sound signal in a small proportion; fourth means for mixing the fourth sound signal in a large proportion and the third sound signal in a small proportion; a first phase shifter coupled to the output of said first means; a second phase shifter coupled to the output of said second means and having substantially the same phase shifting characteristic as said first phase shifter over the entire audible frequency range; a third phase shifter coupled to the output of said third means and having a phase shifting characteristic of plus 90* difference with respect to those of said first and second phase shifters; a fourth phase shifter coupled to the output of said fourth means and having a phase shifting characteristic of minus 90* difference with respect to those of said first and second phase shifters; means for coupling a fifth sound signal desired to have its sound image localized between the first and third loudspeakers to the input of said first phase shifter in a large proportion; means for coupling said fifth sound signal to the input of said fourth phase shifter in a small proportion; means for coupling a sixth sound signal desired to have its sound image localized between the second and fourth loudspeakers to the input of said second phase shifter in a large proportion; means for coupling said sixth sound signal to the input of said third phase shifter in a small proportion; means for mixing output signals from said first and third phase shifters; and means for mixing output signals from said second and fourth phase shifters.

Claim 5

An encoding system for coupling to the first and second channels first to fourth sound signals desired to be coupled mainly to first to fourth loudspeakers surrounding a listener comprising: means for coupling the first and second sound signal to the first channel in large and small proportions respectively with a reference phase shift amount; means for coupling the second and first sound signals to the second channel in large and small proportions respectively with the reference phase shift amount; means for coupling the third and fourth sound signals to the first channel in large and small proportions respectively with the reference phase shift amount plus 90*; means for coupling the fourth and third sound signals to the second channel in large and small proportions with the reference phase shift amount minus 90*; means for coupling a fifth sound signal desired to have its sound image localized between the first and third loudspeakers to the first channel in a large proportion with the reference phase shift amount; means for coupling the fifth sound signal to the second channel in a small proportion with a phase shift amount having substantially 90* phase difference with respect to the reference phase shift amount; means for coupling a sixth sound signal desired to have its sound image localized between the second and fourth loudspeakers to the second channel in a large proportion with the reference phase shift amount; and means for coupling the sixth sound signal to the first channel in a small proportion with a phase shift amount having substantially 90* phase difference with respect to the reference phase shift amount.

Claim 6

An encoding system for coupling to the first and second channels first to fourth sound signals desired to be coupled mainly to first to fourth loudspeakers surrounding a listener comprising: means for coupling the first and second sound signal to the first channel in large and small proportions respectively with a reference phase shift amount; means for coupling the second and first sound signals to the second channel in large and small proportions respectively with the reference phase shift amount; means for coupling the third and fourth sound signals to the first channel in large and small proportions respectively with the reference phase shift amount plus 90*; means for coupling the fourth and third sound signals to the second channel in large and small proportions with the reference phase shift amount minus 90*; means for coupling a fifth sound signal desired to have its sound image localized between the first and third loudspeakers to the first channel in a large proportion with the reference phase shift amount; means for coupling the fifth sound signal to the second channel in a small proportion with a phase shift amount having substantially 90* phase difference with respect to the reference phase shift amount; means for coupling a sixth sound signal desired to have its sound image localized between the second and fourth loudspeakers to the second channel in a large proportion with the reference phase shift amount; and means for coupling the sixth sound signal to the first channel in a small proportion with a phase shift amount having substantially 90* phase difference with respect to the reference phase shift amount.

Claim 7

An encoding system according to claim 3 wherein the small proportion of the first to fourth sound signals bears a ratio of about 0.414 to the large proportion thereof.

Claim 8

An encoding system according to claim 3 wherein the small proportion of the fifth and sixth sound signals bears a ratio of 0.01 to 0.1 to the large proportion thereof.

Claim 9

An encoding system for encoding first to fourth sound signals desired to be coupled mainly to first to fourth loudspeakers surrounding a listener into first and second channel signals comprising: first to fourth input terminals adapted to receive the first to fourth sound signals respectively; a fifth input terminal adapted to receive a fifth sound signal desired to have its sound image localized between the first and third loudspeakers; a sixth input terminal adapted to receive a sixth sound signal desired to have its sound image localized between the second and fourth loudspeakers; first and second output terminals; matrix means connected to said first to fourth input terminals so as to form first, second, third and fourth output signals, said first output signal being a sum of the first sound signal having a large amplitude and the second sound signal having a small amplitude, said second output signal being a sum of the first sound signal having a small amplitude and the second sound signal having a large amplitude, said third output signal being a sum of the third sound signal having a large amplitude and the fourth sound signal having a small amplitude, and said fourth output signal being a sum of the third sound signal having a small amplitude and the fourth sound signal having a large amplitude; a first phase shifter connected to receive said first output signal and having a reference phase shifting characteristic; a second phase shifter connected to receive said second output signal and having the reference phase shifting characteristic; a third phase shifter connected to receive said third output signal and having a phase shifting characteristic of plus 90* difference with respect to the reference phase shifting characteristic; a fourth phase shifter connected to receive said fourth output signal and having a phase shifting characteristic of minus 90* difference with respect to the reference phase shifting characteristic; means for coupling output signals from said first and third phase shifters to said first output terminal; means for coupling output signals from said second and third phase shifters to said second output terminal; means for coupling a fifth sound signal to said first phase shifter with a large amplitude; means for coupling the fifth sound signal to said third phase shifter with a small amplitude; means for coupling a sixth sound signal to said second phase shifter with a large amplitude; and means for coupling the sixth sound signal to said fourth phase shifter with a small amplitude.

Claim 10

An encoding system for encoding first to fourth sound signals desired to be coupled mainly to first to fourth loudspeakers surrounding a listener into first and second channel signals comprising: first to fourth input terminals adapted to receive the first to fourth sound signals respectively; a fifth input terminal adapted to receive a fifth sound signal desired to have its sound image localized between the first and third loudspeakers; a sixth input terminal adapted to receive a sixth sound signal desired to have its sound image localized between the second and fourth loudspeakers; first and second output terminals; matrix means connected to said first to fourth input terminals so as to form first, second, third and fourth output signals, said first output signal being a sum of the first sound signal having a large amplitude and the second sound signal having a small amplitude, said second output signal being a sum of the first sound signal having a small amplitude and the second sound signal having a large amplitude, said third output signal being a sum of the third sound signal having a large amplitude and the fourth sound signal having a small amplitude, and said fourth output signal being a sum of the third sound signal having a small amplitude and the fourth sound signal having a large amplitude; a first phase shifter connected to receive said first output signal and having a reference phase shifting characteristic; a second phase shifter connected to receive said second output signal and having the reference phase shifting characteristic; a third phase shifter connected to receive said third output signal and having a phase shifting characteristic of plus 90* difference with respect to the reference phase shifting characteristic; a fourth phase shifter connected to receive said fourth output signal and having a phase shifting characteristic of minus 90* difference with respect to the reference phase shifting characteristic; means for coupling output signals from said first and third phase shifters to said first output terminal; means for coupling output signals from said second and third phase shifters to said second output terminal; means for coupling a fifth sound signal to said first phase shifter with a large amplitude; means for coupling the fifth sound signal to said third phase shifter with a small amplitude; means for coupling a sixth sound signal to said second phase shifter with a large amplitude; and means for coupling the sixth sound signal to said fourth phase shifter with a small amplitude.