Abstract: A speaker driving apparatus includes a speaker enclosure whose inside is tightly closed, at least two speakers that are provided to the speaker enclosure so as to have a common rear space, and a signal supplying unit that supplies a stereo left channel signal to the speaker in a first group and supplies a stereo right channel signal to the speaker in a second group. The at least two speakers being divided into two groups as the first group and the second group.

Abstract: Power amplifies are provided to correspond with a plurality of speaker units constituting a speaker array. Driving signals from the power amplifies are supplied to one terminals of the speaker units, and other terminals are connected a common line. Inverters are provided at preceding stages of the power amplifies such that the driving signals supplied to the speaker units being arranged adjacently have an opposite phase respectively. Since a correlation between the driving signals of the adjacent speaker units is high, a current flowing through the common line can be very reduced. An LED display panel can be driven by the similar method.

Abstract: A vehicle of the present invention includes: a vehicle body; an electric motor; wheels that are provided between the vehicle body and a road surface and that are rotated by transmitted motive power, to thus drive the vehicle body; a power transmission section that transmits motive power generated by the electric motor to the wheels; a detection section that detects a driving speed of the vehicle body; a speaker unit that outputs a sound based on a supplied audio signal downwardly from an undersurface of the vehicle body so as to reflect on the road surface, thereby to output the reflected sound to surroundings of the vehicle body; and a supply section that acquires an audio signal and supplies the audio signal to the speaker unit when a driving speed of the vehicle body detected by the detection section is less than a preset speed.

Abstract: An amplification system of the invention can decrease power consumption in a power amplification section if the power amplification section need not be used. The power consumption in the power amplification section can be decreased by shutting off power feed into a voltage amplification stage by a power control section, and the power feed state into a power amplification stage from a power supply section is not changed. Thus, power feed into the voltage amplification stage of the circuit wherein a large current does not flow needs only to be controlled using limiter means also used for a different application, so that the power consumption of the power amplification section can be decreased without the need for enlarging the circuit scale, with saved space, and simply.

Abstract: A speaker system, includes a speaker enclosure that has a surface, a speaker that is mounted in the speaker enclosure, a vibration portion that has one end fixed on the surface of the speaker enclosure so as to be allowed to vibrate elastically, an opening portion that is provided in the surface where the vibration portion is provided, and disposed in a position corresponding to a vibration region of the vibration portion and a sealing member that covers a gap formed between the vibration portion and a rim portion of the opening portion while enabling vibration of the vibration portion so as to keep the speaker enclosure airtight.

Abstract: The speaker apparatus according to the invention is arranged in a manner that when the magnitude of an audio signal Sin increases temporarily and so a consumption power increases, a DC-DC converter reduces an output voltage Vout to thereby increase an output current Iout and further discharges a capacitor to thereby increase a current supplied to an amplifier. Thus, a power of 2.5 W or more supplied from a USB connection terminal can be temporarily supplied to the amplifier.

Abstract: A protection circuit of a digital amplifier includes a DC voltage detection circuit for detecting a DC voltage occurring in a loudspeaker output terminal; a control circuit for performing protection operation when the DC voltage detection circuit outputs a detection signal; and a midpoint potential detection circuit for detecting midpoint potential shift between a positive power supply voltage and a negative power supply voltage. Output of the midpoint potential detection circuit is connected to input of the DC voltage detection circuit and when the midpoint potential shift is detected, the DC voltage detection circuit outputs a detection signal.

Abstract: A loudspeaker system includes a loudspeaker enclosure having an inside space, a loudspeaker provided on the loudspeaker enclosure, a first diaphragm which has one of ends fixed to a surface of the loudspeaker enclosure and the other end, a second diaphragm which has one of ends fixed to the surface of the loudspeaker enclosure and the other end, a coupling portion having an elasticity, and coupling the other end of the first diaphragm to the other end of the second diaphragm, an opening structure provided in the surface of the loudspeaker enclosure, and a sealing member provided to a portion among the first and second diaphragms, the coupling portion and an edge part of the opening structure, and closing the inside space to hold an airtightness of the loudspeaker enclosure in a state that the first and second diaphragms can be vibrated.

Abstract: A vibration source driving device that realizes various vibration functions on portable telephones. The vibration source driving device includes a sound source for generating musical tone signals in response to music data. A vibration source to generate vibration, a driver to drive the vibration and a control circuit are further included such that the vibration source may be driven in synchronization with the rhythm signal within the music data.

Abstract: A switching regulator raises power from a USB terminal to 100 V, and performs the charging of an electrolytic capacitor. After the charging has been completed, a switching regulator drops the voltage to 5 V, and supplies the power to an amplifier. When the power consumed by the amplifier exceeds the maximum power to be supplied in accordance with the USB standard, the charge accumulated in the electrolytic capacitor is discharged, and for use, the switching regulator drops the power to 5 V. Thus, when the power consumed exceeds the maximum power to be supplied by the USB terminal, the amplifier can be driven without any problem.

Abstract: A threshold value adjustment circuit for adjusting a predetermined threshold value is provided in a stage followed by a protection circuit which starts protection operation when a load current flowing into an MOSFET exceeds the threshold value. A voltage proportional to a drain current and generated between the opposite ends of a current detection resistor Rd inserted between the high-side MOSFET and a positive power supply +V, and an output of an output voltage detection circuit for detecting the voltage amplitude of an analog signal from a low pass filter for modulating an output of a class D amplifier stage are inputted to the threshold value adjustment circuit. The threshold value adjustment circuit adjusts the threshold value in such a manner that a limit current of the MOSFET is set as the threshold value when the output voltage is large, and protection operation is started in response to a lower current than the limit current when the output voltage is small.

Abstract: A vibration source driving device that realizes various vibration functions on portable telephones. The vibration source driving device includes a sound source for generating musical tone signals in response to music data. A vibration source to generate vibration, a driver to drive the vibration and a control circuit are further included such that the vibration source may be driven in synchronization with the rhythm signal within the music data.

Abstract: A speaker driving apparatus includes a speaker enclosure whose inside is tightly closed, at least two speakers that are provided to the speaker enclosure so as to have a common rear space, and a signal supplying unit that supplies a stereo left channel signal to the speaker in a first group and supplies a stereo right channel signal to the speaker in a second group. The at least two speakers being divided into two groups as the first group and the second group.

Abstract: There is provided a power supply circuit having a simple configuration which is capable of eliminating an adverse effect due to pumping operation. The capacitor-input positive and negative power supply circuit is comprised of diodes, switching circuits connected in parallel with the diodes, and control circuits that control the switching circuits such that the switching circuits conduct during a time period over which the diodes conduct.

Abstract: A protection circuit of a digital amplifier includes a DC voltage detection circuit for detecting a DC voltage occurring in a loudspeaker output terminal; a control circuit for performing protection operation when the DC voltage detection circuit outputs a detection signal; and a midpoint potential detection circuit for detecting midpoint potential shift between a positive power supply voltage and a negative power supply voltage. Output of the midpoint potential detection circuit is connected to input of the DC voltage detection circuit and when the midpoint potential shift is detected, the DC voltage detection circuit outputs a detection signal.

Abstract: A speaker system, includes a speaker enclosure that has a surface, a speaker that is mounted in the speaker enclosure, a vibration portion that has one end fixed on the surface of the speaker enclosure so as to be allowed to vibrate elastically, an opening portion that is provided in the surface where the vibration portion is provided, and disposed in a position corresponding to a vibration region of the vibration portion and a sealing member that covers a gap formed between the vibration portion and a rim portion of the opening portion while enabling vibration of the vibration portion so as to keep the speaker enclosure airtight.

Abstract: An array speaker system is constituted by a plurality of speaker units, which are equipped with weighting means respectively and to which weight coefficients based on a Bessel function are imparted. An input signal is transmitted through an all-pass filter whose phase rotates by 180° in high-frequency ranges and is then supplied to those of the speaker units whose weight coefficients have negative values. Thus, a signal of an inverse phase is output with respect to low-frequency ranges; hence, it is possible to avoid the deterioration of audio emission characteristics, and it is possible to avoid the occurrence of beams and comb shapes in audio emission characteristics with respect to signals of high-frequency ranges.

Abstract: A switching power device uses a non-capacitor flyback converter circuit not provided with a smoothing input capacitor having a large capacity. Therefore, a power harmonic can be suppressed and a rush current preventing element is not required. A fluctuation in an output current to be supplied to a load is fed back to the non-capacitor flyback converter circuit by a feedback circuit at a lower speed than an input AC frequency. Therefore, it is possible to improve a power factor by causing an input AC current to be proportional to an input AC voltage. A voltage control circuit controls an output voltage so as to have a constant voltage, and the output voltage is dropped in proportion to an output current when the output current exceeds a threshold. Therefore, it is possible to have the same output characteristic as a power device comprising a low frequency power transformer.

Abstract: A lateral PNP transistor PB and a lateral NPN transistor NB are serially connected between an input terminal and a reference potential (ground potential). In the transistor PB, a diode D1 is formed. In the transistor NB, a diode D3 is formed. When an ESD of +2000 V is input, the transistor NB turns on, whereas when an ESD of ?2000 V is input, the transistor PB turns on. The level of a positive signal capable of being input is limited by the inverse breakdown voltage (e.g., 18 to 50 V) of the diode D3, whereas the level of a negative signal capable of being input is limited by the inverse breakdown voltage (e.g., 13 to 15 V) of the diode D1.

Abstract: A threshold value adjustment circuit for adjusting a predetermined threshold value is provided in a stage followed by a protection circuit which starts protection operation when a load current flowing into an MOSFET exceeds the threshold value. A voltage proportional to a drain current and generated between the opposite ends of a current detection resistor Rd inserted between the high-side MOSFET and a positive power supply +V, and an output of an output voltage detection circuit for detecting the voltage amplitude of an analog signal from a low pass filter for modulating an output of a class D amplifier stage are inputted to the threshold value adjustment circuit. The threshold value adjustment circuit adjusts the threshold value in such a manner that a limit current of the MOSFET is set as the threshold value when the output voltage is large, and protection operation is started in response to a lower current than the limit current when the output voltage is small.