Buzzer driving circuit

Abstract

PURPOSE: To vary the sound volume of a piezoelectric buzzer with a single power source by driving the piezoelectric buzzer with the output obtained by gating a pulse signal selected among plural pulse signals which have frequencies higher than a frequency nearly equal to the resonance frequency of the piezoelectric buzzer and differ in duty by using a pulse signal of frequency nearly equal to the resonance frequency. CONSTITUTION: Pulse generating circuits 23-25 generate the pulse signals PA, PB, and PC which have frequencies higher than the resonance frequency of the piezoelectric buzzer 31 and differ in duty according to a basic clock and a pulse selecting circuit 26 selects the pulse signals PA, PB, and PC according to a control signal from a microcomputer 27. Then the selected pulse signal P is gated by an AND circuit 28 with the pulse signal P outputted by a pulse generating circuit. Consequently, the amplitude of a component having a frequency close to the resonance frequency can be varied with the duty of the pulse signal, to the sound volume of the piezoelectric buzzer can be varied with the single power source. COPYRIGHT: (C)1990,JPO&Japio

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Patent Citations (3)

    Publication numberPublication dateAssigneeTitle
    JP-S5619476-AFebruary 24, 1981Seiko Epson CorpAlarm unit
    JP-S57210395-ADecember 23, 1982Ricoh KkPiezo-electric buzzer driving system
    JP-S5860292-UApril 23, 1983

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    JP-2015032852-AFebruary 16, 2015セイコーインスツル株式会社, Seiko Instruments Inc電子機器、および電子機器の制御方法
    JP-2015074283-AApril 20, 2015株式会社デンソー, Denso CorpVehicular alarm apparatus
    JP-2016075780-AMay 12, 2016マツダ株式会社, Mazda Motor Corp発音装置
    JP-H0530897-UApril 23, 1993日興電機工業株式会社圧電ブザー装置
    JP-H056499-UJanuary 29, 1993日興電機工業株式会社圧電ブザー回路