Piezoelectric acoustic multiple tone generator

• US 3,912,952 A
• Filed: 02/22/1974
• Issued: 10/14/1975
• Est. Priority Date: 12/27/1971
• Status: Expired due to Term

• Current Assignee: Nobuyuki Saito, Osamu Kumon
• Original Assignee: Nobuyuki Saito, Osamu Kumon
• Inventors: Saito, Nobuyuki, Kumon, Osamu
• Primary Examiner(s): Budd, Mark O.
• Application Number:
  US05/445,040
• Time in Patent Office: 599 Days
• Field of Search: 310/8.1,8.2 179/11A,138 340/388,384E,393,384R 84/1.24
• US Class Current: 310/317
• CPC Class Codes: B06B 1/0223 for generating signals continuous in time
• CPC Class Codes: B06B 2201/55 Piezoelectric transducer
• CPC Class Codes: B60Q 5/00 Arrangement or adaptation of acoustic signal devices
• CPC Class Codes: B60R 2022/4816 for sensing locking of buckle
• CPC Class Codes: B60R 22/48 Control systems, alarms, or interlock systems, for the correct application of the belt or harness
• CPC Class Codes: G08B 3/10 using electric transmission; using electromagnetic transmission

Abstract

This invention provides an acoustic device including one sound generator for generating sound waves with a plurality of distinguishable tone colors. For this purpose, the sound generator is composed of a composite member, which consists of a piezoelectric element and a diaphragm adhered thereon, and an electric circuit connected thereto so that sound waves are generated according to the bending vibration of the composite member, that is, so-called piezoelectric sound generator, and the tone color of the generated sound wave is varied by means of making a change in the electric circuit. As ways for making a change in the electric circuit, the electric circuit is composed of an oscillator and a switching circuit and then the time constant or the switching frequency of the switching circuit is varied.

Claims

1. A piezoelectric acoustic system comprising:

a. a single composite electroacoustical member including a piezoelectric element and a diaphragm adhered to each other;

b. phase-shift oscillator means electrically coupled to said member for applying electrical oscillation signals thereto, thereby inducing bending vibration iN said member to generate a sound wave;

c. cross-coupled multivibrator circuit means comprising a resistance-capacitance time constant circuit which determines the switching frequency of said multivibrator means;

d. means for electrically coupling the output of said multivibrator circuit means to said oscillator means to intermittently interrupt said oscillation signals and thereby said sound wave; and

e. means for varying the resistance of said time constant circuit to vary the switching frequency of said multivibrator means, and thereby the frequency at which said oscillation signals are intermittently interrupted so as to produce a plurality of distinguishable tone colors from said single composite member;

said multivibrator circuit further comprising first and second cross-coupled transistors of the same conductivity type;

the collector of said first transistor being directly connected to the base of said second transistor to form a first cross-coupling path;

said resistance-capacitance time constant circuit being connected between the collector of said second transistor and the base of said first transistor to form a second cross-coupling path;

the emitters of said transistors being connected to a common point;

a resistor connected directly between the bases of said transistors;

individual resistors connecting the collectors of said transistors to a common power input terminal;

first, second and third additional power input terminals connected respectively to said emitter common point, to the juncture of the resistance and capacitor in said time constant circuit, and directly to said oscillator means;

whereby a D.C. power source selectively connected between said common power input terminal and individual ones of said first, second and third power input terminals produces, respectively, said plurality of distinguishable tone colors.