Electrostatic transducer, ultrasonic speaker, driving circuit of capacitive load

Abstract

Provided are an electrostatic transducer capable of reducing a loss in a damping resistor and realizing a flat frequency characteristic in a driving frequency band in the case of using a class-D power amplifier and an LC filter, a method of setting a circuit constant of the electrostatic transducer, an ultrasonic speaker, a display device, and a directional sound system and a driving circuit of a capacitive load . An electrostatic transducer includes: a class-D power amplifier that amplifies an input signal; and a low pass filter that has a plurality of pairs of inductors and capacitors, is connected to an output side of the class-D power amplifier, and serves to eliminate switching carrier components included in an output of the class-D power amplifier. An electrostatic load capacitor of the electrostatic transducer serving as a driving load is disposed at a capacitor, which is closest to the output side of the class-D power amplifier, of circuit elements forming the low pass filter, an electrostatic coupling capacitor and an output transformer are interposed between the electrostatic load capacitor of the electrostatic transducer and an inductor closest to the output side of the class-D power amplifier of the low pass filter, and a damping resistor is connected in series to a primary coil of the output transformer.

Description

technical field [0001] The present invention relates to an electrostatic transducer, in particular to an electrostatic transducer having a drive circuit, a method for setting circuit constants of the electrostatic transducer, an ultrasonic speaker, a display device having the ultrasonic speaker, and directivity An acoustic system, wherein the drive circuit is suitable for an electrostatic transducer that outputs a modulated wave obtained by modulating a carrier wave in an ultrasonic frequency band by an acoustic signal in an audible frequency band, thereby reproducing a modulated wave having a high The directional sound also involves the drive circuit of the capacitive load. Background technique [0002] The ultrasonic speaker can reproduce sound with high directivity by outputting a modulated wave obtained by modulating a carrier wave in the ultrasonic frequency band with an acoustic signal in the audible frequency band. As a transducer (transmitter) of an ultrasonic speak...

AI Technical Summary

Problems solved by technology

In the example shown in FIG. 17, the ultrasonic speaker cannot be stably driven under such characteristics because the characteristics around the driving frequency band of the ultrasonic speaker fluctuate greatly.

Images