Onkyo Corporation

Joji Kasai

Kazumasa Takemura

Tetsuro Nakatake

Koichi Sadaie

Kenichiro Toyofuku

Kazuhiro Hida

Mamoru Sekiya

Sadatoshi Hisamoto

Koji Takatori

Yoshitaka Handa

Tadashi Yamamoto

Sou Fujioka

Hiroyuki Hirano

An audio signal processing circuit for an audio reproduction apparatus at least having sound source located substantially at left and right sides to a listener, is provided. The audio signal processing circuit includes a phase difference control portion. The phase difference control portion receives a left channel signal for the left sound source and a right channel signal for the right sound source, controls a phase difference between the left and right channel signals so as to produce a relative phase difference in the range of 140 degrees to 160 degrees, and outputs the phase difference controlled left and right channel signals for the left and right sound source, respectively.

Audio signal processing circuit

A switching power supply circuit of the present invention includes: a transformer including a main winding and an auxiliary winding, which are magnetically coupled together on a primary winding side; a switching element for intermittently supplying a direct-current voltage to the main winding; and a controller for turning ON/OFF the switching element using a voltage induced across the auxiliary winding by the intermittent supply of the direct-current voltage. The switching power supply circuit includes a startup circuit, the startup circuit including: a startup switch connected to the main winding; and a driving pulse generator for outputting a driving pulse to the startup switch for turning ON the startup switch.

Switching power supply circuit

A switching amplifier including a PWM circuit, a driver, a switching output circuitand an LPFis provided with a fluctuation detection circuitfor detecting fluctuations in the power supply voltage. The fluctuation detection circuitincludes detection resistorsandconnected in series between a positive power supplyand a negative power supply. A fluctuating signal RPL occurring at a fluctuation detection terminalis supplied to the inverted input terminal of a differential amplifierof a non-inverted amplifier circuit. The non-inverted amplifier circuitinverts the fluctuating signal RPL, mixes the inverted fluctuating signal into the input signal e, amplifies the mixed signal, and supplying the amplified signal to the PWM circuit

Switching amplifier

Surround-effect, providing no unnatural feeling to the listeners who sit next to each other under side-by-side basis through virtual sound sources, is realized. A surround left channel signal SL and a surround right channel signal SR are mixed with an adderand are in monaural. A first monophonic signal and a second monophonic signal thus resulted are supplied to a virtual localization processor. A first virtual localization output of the processoris supplied to a front left speaker SPL and a front right speaker SPR and a second virtual localization output thereof is supplied to a front center speaker SPC. In this way, virtual sound sources can be created at the right and the left to the listener. Similarly, virtual sound sources can also be created at the right and the left to the listener. Sound fields from the virtual surround sources are in reverse to the listenerand the listener. However, no substantial drawbacks caused by the reversal are observed because monophonic signals are reproduced as the surround signals in this embodiment. In this way, surround-effect with natural feeling can be achieved.

Surround-sound processing system

In a switching power supply of the present invention, when a voltage output from start-up means is greater than a driving voltage produced by output means, the voltage from the start-up means is provided to control means, whereby the switching power supply can be started up reliably. Furthermore, when the voltage output from the start-up means is less than the driving voltage produced by the output means, the current path is blocked in the start-up means so that no voltage is provided to the control means from the start-up means, whereby it is possible to reduce the power consumption during the steady operation.

Switching power supply

The present invention includes producing a first processed signal which localizes sound image at a first localization position and a second processed signal which localizes sound image at a second localization position; multiplying one of the first and the second processed signals by a coefficient k which varies in the range of 0 to 1; multiplying the other signal by a coefficient 1&minus;k; and adding the processed signal multiplied by the coefficient k and the processed signal multiplied by the coefficient 1&minus;k. When the predetermined position is located away at an angle &thgr; in a circumferential direction from the front of the listener, the first localization position is in the vicinity of the predetermined position and located away at an angle &thgr; in a circumferential direction from the front of the listener wherein &thgr; <&thgr;, and the second localization position is in the vicinity of the predetermined position and located away at an angle &thgr; in a circumferential direction from the front of the listener wherein &thgr; >&thgr;.

Apparatus and method for localizing sound image

It is an object of the present invention to provide an apparatus for localizing a sound image capable of achieving so called 'surround-effect' sufficiently with a simple structure while maintaining a sufficient width of a frontal sound field. Both surround left and surround right signals SL, SR are supplied to a sideward localizer 12 for localizing the sound image reproduced by the signals to positions of sideward of a listener. Also, front left and front right signals FL, FR are supplied to the sideward localizer 12. In this way, the sound image reproduced by the signals is localized at positions between speakers arranged in front side and sidewards of the listener, so that a sufficient width of frontal sound field can be maintained eventually.

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Neyagawa, Japan

Joji Kasai