Pioneer Electronic Corporation

Tohoku Pioneer Electric Corporation

Yoshio Sasaki

Akio Tokumo

Yoshiro Kunugi

Makoto Odaka

Takeshi Sato

Toshikazu Yoshimi

Shinjiro Kato

Masayuki Kato

Mamoru Saitoh

Shuuichi Mori

Toyohiko Terada

A driving apparatus according to the invention turns on a capacitive light emitting device having a first electrode and a second electrode in accordance with a light-on instruction. The apparatus has: a voltage accumulating unit, for example, a capacitor for holding a voltage energy corresponding to the contents of the light-on instruction; a circuit for applying the voltage energy held in the voltage accumulating unit to a portion across electrodes (A and B) in one direction in response to a first control signal and for applying the voltage energy held in the voltage accumulating unit to the portion across the electrodes in the other direction in response to a second control signal; and a circuit for alternately generating the first and second control signals. The invention can cope with a deterioration due to an aging change or the like, prevent a reduction of a light emission intensity due to the deterioration or the like, and contribute to a simplification of the construction and a decrease in costs.

Driver for capacitive light-emitting device with degradation compensated

A main ladder attenuator has a series of resistors and switches for connecting corresponding resistors to an output. The controller has an auxiliary ladder attenuator connected to the main ladder attenuator in series and having a series of resistors and switches. Each of the resistors of the auxiliary ladder attenuator is provided for interpolating between the adjacent resistors of the main ladder attenuator.

Electronic volume controller

A stabilized power supply is provided for supplying a constant voltage to an audio amplifier. There are provided two comparators, a first comparator of which compares an output voltage of the stabilized power supply with a reference value to provide a first comparator signal when the output voltage coincides with the reference value. A second comparator is provided for comparing an output bias voltage of the amplifier with the output voltage of the stabilized power supply and for producing a second comparator signal when the output bias voltage coincides with the output voltage. A NAND gate is provided to be operated by the first and second comparator signals and a mute release signal so as to stop muting operation of the circuit.

Circuit for muting noises for an audio amplifier

An isolator circuit for an audio system has an operational amplifier provided between a signal source and an amplifier. A capacitor and a resistor connected in series are connected between each input of the operational amplifier and the signal source. A buffer amplifier is provided between the capacitor and the resistor of each input line of the operational amplifier.

Isolator circuit for an audio system

A sound field correcting system for correcting for mulitpath frequency-characteristic distortion in an acoustic reproducing system. In one embodiment, the level and delay of an original signal are adjusted and superposed on the original signal so as to obtain a signal which, when reproduced by a loudspeaker, yields a sound pattern at a listening point having a flat frequency characteristic. The delay adjustment is effected in accordance with a difference between the travel distances of direct and reflected sound waves to the listening point.

Sound field correction system

An adjusting apparatus for adjusting sound volume or sound quality of a signal reproduced from a music source in which an electronic volume section has a group of analog switches. The apparatus includes a signal generating means which generates a signal for switching the group of analog switches at the approximately zero-cross point of the reproduced signal of the music source.

Adjusting apparatus for adjusting sound volume or sound quality

A sound field correcting system for correcting for multipath frequency-characteristic distortion in an acoustic reproducing system. In one embodiment, the level and delay of an original signal are adjusted and superposed on the original signal so as to obtain a signal which, when reproduced by a loudspeaker, yields a sound pattern at a listening point having a flat frequency characteristic. The delay adjustment is effected in accordance with a difference between the travel distances of direct and reflected sound waves to the listening point.

An amplification gain adjusting circuit in which the gain of an AC amplifier is controlled by a voltage dividing series connection of two resistors. One of the resistors is selectively shorted by a switching transistor. The DC bias of the switching transistor is set to prevent current flow through the base of the switching transistor at high AC levels.

Amplification gain adjusting circuit

An automatic sound volume device which adjusts the volume of an audio signal in a vehicle to compensate for vehicle noise. A time constant circuit smooths the level output of a microphone to smooth the volume variations. However, the time constant is long for increases in noise but short for decreases in noise.

Automatic sound volume controlling device for use in automotive vehicle

A sound field correcting device for use in a stereophonic system intended for vehicular use. Speakers are installed on opposite sides of both the front and rear seats of the vehicle. The number of persons seated in the vehicle is determined and applied to a correcting unit. When plural persons are seated in the vehicle, the sound pressure levels in the high-frequency range of loudspeakers is increased. Also, the sound pressure levels of the speakers can be corrected in accordance with the positions at which persons are seated in the vehicle.

Mobile sound field correcting device

An automatic gain control unit particularly adapted for vehicular use is disclosed. The ambient noise level inside the vehicle is detected, as is the level of the audio signal. A difference is formed between detection signals thus produced, and a frequency characteristic of a gain varying device, inserted in an audio signal path of the audio device, is varied according to this difference.

Automatic gain and frequency characteristic control unit in audio device

A mobile sound field correcting system for correcting an acoustic characteristic in a vehicle sound field formed by direct waves radiated from loudspeakers and reflected waves thereof providing satisfactory acoustic characteristics for different vehicles and different listening points within a vehicle. A first correcting means corrects a power spectrum of each loudspeaker in a frequency range above a frequency at which a decrease of starts of the power spectrum in a high-frequency range of each loudspeaker. Second correcting means corrects for irregularities in the frequency characteristic of each loudspeaker caused by interference of the direct waves with the reflected waves in a frequency lower than the drop-off frequency of this power spectrum.

Growing community of inventors

Saitama, Japan

Yoshio Sasaki