| 摘要 |
<p><P>PROBLEM TO BE SOLVED: To provide a miniaturized and inexpensive ultrasonic parametric speaker. <P>SOLUTION: Each of two speakers SP1 and SP2 is composed of a semiconductor wafer 10, a heat insulating layer 11 provided on a surface of the semiconductor wafer 10, and a membrane-like heating element 12 which is provided on a surface of the heat insulating layer 11 on the opposite side of the semiconductor wafer 10 and generates heat in accordance with an inputted electric signal, and is provided with an ultrasonic generator 1 for expanding and shrinking a medium by generating heat from the heating element 12 to generate ultrasonic waves. The ultrasonic generator 1 of one speaker SP1 is driven by a fixed frequency output means 3 and generates ultrasonic waves of a fixed reference frequency. The ultrasonic generator 1 of the other speaker SP2 is driven by a modulation frequency output means 6 and outputs ultrasonic waves of a frequency composed of the reference frequency and a frequency of an audible sound, thereby generating the audible sound from a differential sound of ultrasonic waves outputted from the speakers SP1 and SP2. <P>COPYRIGHT: (C)2004,JPO</p> |
