Quaternary stereophonic sound reproduction apparatus

Claim 2

A quadraphonic sound reproduction apparatus for use in quadraphonic sound recording and reproducing systems comprising in combination, reproducing decoder means for restoring encoded signals to four signals, four audio channels coupled to said reproducing decoder means, a plurality of means, each coupled to a pair of said audio channels corresponding to oppositely located speakers for comparing the amplitude of said restored signal of the signal in one of said pair of audio channels with the amplitude of a cross talk component thereof in the respective other audio channel, each of said means producing a balancing signal from said restored signal the magnitude of which is dependent upon the ratio of the amplitudes of the restored signal and the cross talk component of the respective signal, and attenuating means coupled between each of said comparing means and the other two audio channels for applying said balancing signal from said comparing means to the remaining two channels to attenuate cross talk components of the signal developed therein by applying a signal opposite in phase to sAid cross talk, whereby the acoustic separation between the audio channels is increased.

Claim 3

A quadraphonic sound reproduction apparatus as claimed in claim 1 wherein said means for attenuating the cross talk component of the signal includes a phase inverter circuit for inverting the phase of the balancing signal, and a mixer circuit connected to said phase inverter circuit to add said balancing signal to the cross talk component of the signal in phase inverted relationship, thereby eliminating the cross talk component.

Claim 4

A quadraphonic sound reproduction apparatus as claimed in claim 1 wherein said comparing means includes means for generating the balancing signal which comprises a detection circuit for producing a control signal in accordance with the ratio of the amplitude of said restored signal and said cross talk component of the signal in the selected audio channel, and a gain control circuit coupled to the detection circuit and responsive to the applied control signal to produce the balancing signal for eliminating the cross talk component of the signal.

Claim 5

A quadraphonic sound reproduction apparatus for use in quadraphonic sound recording and reproducing systems comprising in combination, reproducing decoder means for restoring encoded signals to four signals, four audio channels coupled to said reproducing decoder means each channel receiving one signal therefrom, a plurality of combined comparison and detection circuit means each coupled to respective pairs of said audio channels, one of each of said pairs being a reference channel and the other being an associated audio channel said two channels being connected to diagonally opposite speakers, for comparing said restored signal in each of the respective reference audio channels with a cross talk component of the signal developed in the associated channel in terms of the amplitude of the signal and the cross talk component, and for detecting the ratio of the amplitude of said restored signal to said cross talk component, a plurality of balancing signal generation circuit means each coupled to one of said combined comparison and detection circuit means and to said respective reference audio channel for generating a balancing signal from said restored signal in said respective reference audio channel in accordance with said ratio, and a plurality of attenuating circuit means each coupled to one of said balancing signal generation circuit means and to audio channels corresponding to speakers flanking said reference channel speaker for applying the balancing signal to each of the flanking audio channels to attenuate the cross talk component of the signal resulting from the restored signal in each of the audio channels by applying a signal opposite in phase to said cross talk, whereby the cross talk component is eliminated for increasing the acoustic separation between the audio channels.

Claim 6

A quadraphonic sound reproduction apparatus for use in quadraphonic sound recording and reproducing systems comprising in combination, reproducing decoder means for restoring encoded signals to four signals, four audio channels coupled to said reproducing decoder means each channel receiving one signal therefrom, a plurality of combined comparison and detection circuit means each coupled to respective pairs of said audio channels, one of each of said pairs being a reference channel and the other being an associated audio channel said two channels being connected to diagonally opposite speakers, for comparing said restored signal in each of the respective reference audio channels with a cross talk component of the signal developed in the associated channel in terms of the amplitude of the signal and the cross talk component, and for detecting the ratio of the amplitude of said restored signal to said cross talk component, a plurality of balancing signal generation circuit means each coupled to one of said combined comparison and detection circuit means and to said respective reference audio channel for generating a balancing signal from said restored signal in said respective reference audio channel in accordance with said ratio, and a plurality of attenuating circuit means each coupled to one of said balancing signal generation circuit means and to audio channels corresponding to speakers flanking said reference channel speaker for applying the balancing signal to each of the flanking audio channels to attenuate the cross talk component of the signal resulting from the restored signal in each of the audio channels by applying a signal opposite in phase to said cross talk, whereby the cross talk component is eliminated for increasing the acoustic separation between the audio channels.

Claim 7

A quadrophonic sound reproduction apparatus as claimed in claim 4 wherein said attenuating circuit means includes a phase inverter circuit for phase inverting the balancing signal and a mixer circuit connected to said phase inverter circuit to add the phase inverted balancing signal, to the cross talk component of the signal developed in the respective audio channels corresponding to flanking speakers, thereby eliminating said cross talk.

Claim 8

A quadraphonic sound reproduction apparatus as claimed in claim 4, wherein said associated audio channel in a pair of audio channels is that audio channel into which said restored component of the signal from the reference channel does not ideally leak.