ELECTROSTATIC ULTRASONIC TRANSDUCER, ULTRASONIC SPEAKER, METHOD, DEVICE AND PROGRAM FOR DESIGNING TRANSDUCER, METHOD FOR REPRODUCING SOUND SIGNAL, METHOD FOR MANUFACTURING, SUPER-DIRECTIVITY SOUND SYSTEM AND DISPLAY DEVICE

摘要

PROBLEM TO BE SOLVED: To provide a push/pull type electrostatic ultrasonic transducer where low voltage (low power) operation is obtained by obtaining a height of projecting parts of fixed electrodes quantitatively so as to generate the same sound pressure with smaller energy, an ultrasonic speaker using the transducer, a method, a device and a program for designing the transducer, a method for reproducing a sound signal, method for manufacturing, a super-directivity sound system, and a projector. SOLUTION: In the push/pull type electrostatic ultrasonic transducer 1, a formula for optimally setting the height (t) of the projecting parts of the fixed electrodes 10A and 10B when a desired sound pressure and a driving frequency are given is formalized. The formula is obtained by a=(1/πf)√ä(IO×10P/10)/2ρOc} when it is assumed that the desired sound pressure is P(dB), the driving frequency is f(Hz) and a value of one side amplitude of a film oscillation 12 is a(m). Wherein, Io denotes the reference acoustic intensity being 0.96×10-12(W/m2),ρo is the density of the air being 1.2(kg/m3) and (c) denotes the sound speed in the air being around 340(m/S). A value exceeding and closest to the one side amplitude value "a" obtained by the formula (at least in a range where an oscillation film never contacts with an electrode due to the film oscillation) is set to be the height (t) of the projecting parts of the fixed electrodes. COPYRIGHT: (C)2007,JPO&INPIT