Abstract: An electroacoustic transducer includes a first fixed electrode, a second fixed electrode, and a vibration body. The first and second fixed electrodes face each other across a space. The first fixed electrode includes first protrusions that are provided on a first electrode surface of the first fixed electrode and that protrude toward the second fixed electrode. The first protrusions are arranged at a first arrangement density that varies depending on a position of the first protrusions on the first electrode surface. The second fixed electrode includes second protrusions that are provided on a second electrode surface of the second fixed electrode and that protrude toward the first fixed electrode. The second protrusions are arranged at a second arrangement density that varies depending on a position of the second protrusions on the second electrode surface. The vibration body is sandwiched between the first protrusions and the second protrusions.

Abstract: A speaker comprising includes an acoustic generation unit, a tube, and a pressure transmission member. The acoustic generation unit is arranged in a housing and includes a rear surface that faces an inside of the housing. The tube extends from the rear surface to an outside of the housing in a winding manner. The pressure transmission member is arranged at a side wall of the tube. The pressure transmission member is shared by portions of the tube at a plurality of positions that are located at different distances from the rear surface.

Abstract: A speaker controller includes a switch that is inserted on a speaker wiring for supplying a sound signal to a speaker. A switch control circuit can extract and hold an ON/OFF control signal for instructing ON/OFF of the switch from an alternating-current signal supplied via the speaker wiring. A switch control circuit controls ON/OFF of the switch based on the ON/OFF control signal. A power supply circuit can generate a power supply voltage for operating the switch control circuit from the alternating-current signal supplied via the speaker wiring.

Abstract: Provided is an acoustic device with which it is possible to make reproduced sound able to be heard across a wide frequency range, from the front and from the rear. This acoustic device is provided with a flat speaker 3 configured to emit sound, from a front and a rear thereof, in a low frequency sound range. Also, provided therein are a first speaker 5F configured to emit sound, in a direction facing the front of the flat speaker, in a mid-to-high frequency sound range, and a second speaker 5R configured to emit sound, in a direction facing the rear of the flat speaker, in the mid-to-high frequency sound range.

Abstract: A sensor output device includes a sensor and an output circuit. The sensor includes a piezoelectric element and an output terminal. The piezoelectric element includes porous resin. The output circuit is connected to the output terminal of the sensor and includes a thermistor.

Abstract: Provided is a driving control apparatus that can control relaxation of force in an actuator. The driving control apparatus is provided with: a driving control unit configured to control driving of the actuator according to a driving control signal; and a pressure control unit configured to control, according to a pressure control signal, involvement of the driving control signal in control of pressure to be generated by the actuator.

Abstract: A class D amplifier includes a self-oscillating class D amplification circuit that is driven by an output current signal; and a voltage-current converting circuit that outputs an output current signal in response to an input signal voltage and an output signal voltage from a feedback signal voltage.

Abstract: A sensor output device includes a sensor and an output circuit. The sensor includes a piezoelectric element and an output terminal. The piezoelectric element includes porous resin. The output circuit is connected to the output terminal of the sensor and includes a thermistor.

Abstract: An electroacoustic transducer includes: a diaphragm having two pairs of longitudinal split tubular surfaces; a converter that performs conversion between vibration of the diaphragm and an electric signal; and a supporter supporting the diaphragm. The two pairs of longitudinal split tubular surfaces form valleys and ridge portions. In each pair of the two pairs of longitudinal split tubular surfaces, one-side portions of the respective longitudinal split tubular surfaces form a valley. Another-side portion of the split tubular surface of each one of the two pairs and an other-side portion of the split tubular surface of the other of the two pairs form a ridge portion. The two pairs of longitudinal split tubular surfaces are arranged in at least one of a state in which the valleys are orthogonal to each other and a state in which the ridge portions are orthogonal to each other.

Abstract: A self-oscillating class D amplifier includes an integration circuit configured to integrate an input signal and output a result of the integration as an integrated signal, a comparator configured to receive the integrated signal at an inverting input terminal and output a pulse width modulation signal by comparing voltages of a non-inverting input terminal being grounded and the inverting input terminal, a switching circuit configured to power-amplify the pulse width modulation signal output from the comparator, a low-pass filter configured to extract an amplified output signal from the power-amplified pulse width modulation signal, a first feedback circuit configured to feed back the output signal of the low-pass filter to the inverting input terminal of the comparator, and a second feedback circuit configured to feed back the output signal of the low-pass filter to the integration circuit.

Abstract: A Bridge-Tied Load output self-oscillating class D amplifier includes a comparator receives an input signal from a signal input circuit at a second input terminal and outputs a positive-phase pulse width modulation signal and a reverse-phase pulse width modulation signal by comparing voltages of the two input terminal, first and second switching circuits power-amplifies the reverse-phase pulse width modulation signal and the positive-phase pulse width modulation signal, a first low-pass filter extracts a first output signal from the reverse-phase pulse width modulation signal, a second low-pass filter extracts a second output signal from the positive-phase pulse width modulation signal, a subtractor calculates a difference between the first and second output signals and output a difference signal, and a first feedback circuit feeds back the difference signal to the second input terminal of the comparator.

Abstract: A self-oscillating class D amplifier includes an integration circuit configured to integrate an input signal and output a result of the integration as an integrated signal, a comparator configured to receive the integrated signal at an inverting input terminal and output a pulse width modulation signal by comparing voltages of a non-inverting input terminal being grounded and the inverting input terminal, a switching circuit configured to power-amplify the pulse width modulation signal output from the comparator, a low-pass filter configured to extract an amplified output signal from the power-amplified pulse width modulation signal, a first feedback circuit configured to feed back the output signal of the low-pass filter to the inverting input terminal of the comparator, and a second feedback circuit configured to feed back the output signal of the low-pass filter to the integration circuit.

Abstract: An electroacoustic transducer includes: a diaphragm having two pairs of longitudinal split tubular surfaces; a converter that performs conversion between vibration of the diaphragm and an electric signal; and a supporter supporting the diaphragm. The two pairs of longitudinal split tubular surfaces form valleys and ridge portions. In each pair of the two pairs of longitudinal split tubular surfaces, one-side portions of the respective longitudinal split tubular surfaces form a valley. Another-side portion of the split tubular surface of each one of the two pairs and an other-side portion of the split tubular surface of the other of the two pairs form a ridge portion. The two pairs of longitudinal split tubular surfaces are arranged in at least one of a state in which the valleys are orthogonal to each other and a state in which the ridge portions are orthogonal to each other.

Abstract: A power amplifier includes a class-D amplifier and an input signal supplier. The class-D amplifier includes an input portion and a switching device. The switching device is switched according to an input signal that is input to the input portion so that a current is supplied to a load from a power source via the switching device. The input signal supplier supplies the input signal to the input portion of the class-D amplifier, calculates a virtual output voltage to be output from a virtual power source having a prescribed internal impedance characteristic when a current to flow through the load is output from the virtual power source, and adjust an amplitude of the input signal according to the virtual output voltage.

Abstract: A power amplifier includes a class D amplification section and a load current feedback circuit. The class D amplification section includes an input section and a switching section serving as an output stage and switched depending on a signal input to the input section, and outputs current from a power source to a load via the switching section. The load current feedback circuit negatively feeds back the current flowing in the load to the input section of the class D amplification section.

Abstract: An electroacoustic transducer includes: a diaphragm including a cone portion having a conical shape such as a circular conical surface shape or an oval conical surface shape, and a wing-pair portion having a pair of longitudinal split tubular surfaces arranged next to each other, a valley being formed between a side portion of one of the longitudinal split tubular surfaces and a side portion of the other of the longitudinal split tubular surfaces; a converter that performs conversion between vibration of the diaphragm along an axis of the cone portion and an electric signal corresponding to the vibration; and a supporter that supports the diaphragm such that the diaphragm is movable in an axial direction of the cone portion. The small-diameter-side end portion of the cone portion, and a bottom portion of a valley of the wing-pair portion are secured to the converter.

Abstract: A power amplifier includes a class D amplification section and a load current feedback circuit. The class D amplification section includes an input section and a switching section serving as an output stage and switched depending on a signal input to the input section, and outputs current from a power source to a load via the switching section. The load current feedback circuit negatively feeds back the current flowing in the load to the input section of the class D amplification section.

Abstract: An electroacoustic transducer includes a diaphragm including: a wing-pair portion; and a cone portion. The wing-pair portion includes a pair of convex surfaces having respectively convex surfaces of a pair of longitudinal split tubular members. A valley is formed between one side portions of the pair of convex surfaces. The cone portion surrounds an outer peripheral portion of the wing-pair portion and extends in a conical shape. The electroacoustic transducer further includes: a converter configured to convert between a vibration of the diaphragm in a depth direction of the valley and an electric signal corresponding to the vibration; and a supporter supporting an outer peripheral portion of the cone portion to allow the diaphragm to vibrate in a direction of the vibration.