JPS60102694A - Driving circuit for piezo-electric buzzer sound emitting body - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Field of Industrial Application) The present invention relates to a drive circuit for a two-terminal separately excited piezoelectric buzzer sounding element in a sounding device such as an alarm, and to a driving method for improving sound pressure. be.

(Structure of Conventional Example and Problems thereof) Conventionally, this type of drive system uses a switching drive system between the ground potential and the power supply voltage, as shown in FIG. Separately excited sounding bodies have the advantage of being able to freely change the oscillation frequency from the outside, but they are often driven at a frequency that is outside the resonance point of the sounding body, which has the disadvantage of lowering the sound pressure.

Transformer 2 stars Q1, Q2, capacitor CI+C2
, resistors R,, R2, and collector resistors R3r and R4.
A switching circuit SC consisting of an input resistor R5 and an output resistor R6 is connected, and a separately excited piezoelectric buzzer sounding element BZ is connected between the output end of the switching circuit SC and ground. Therefore, the power supply voltage is directly applied to the separately excited piezoelectric buzzer sounding body BZ. Therefore, when a situation arises in which the sound pressure decreases due to the above-mentioned causes, there is a drawback that the sound pressure becomes too low.

(Objective of the Invention) The object of the present invention is to eliminate the conventional drawbacks, and utilize the property that the phase of the collector voltage of the Professional King oscillation circuit of the drive circuit of the piezoelectric buzzer sounding element is different by 180 degrees, and the collector output of each The idea is to directly apply the voltage to the piezoelectric buzzer sounding body and drive it with a voltage that is equivalently twice the power supply voltage, thereby improving the sound pressure.

(Structure of the Invention) The drive circuit of the voltage buzzer sounding element of the present invention takes out a signal directly from the transformer disk in the blocking oscillation circuit of the drive circuit, and the collector of the two transformers alternately performs the switching operation. The outputs have a phase difference of 180 degrees from each other, and by applying this signal to each of the positive and negative electrodes of the piezoelectric buzzer sounding element, it is possible to drive the piezoelectric buzzer with a voltage twice the power supply voltage equimetrically. It is something.

(Explanation of actual q examples) An embodiment of the present invention will be described based on FIG. 2.

In the figure, in the blocking oscillation circuit, when the l-run source Q+ is turned on, the collector 't' level rapidly drops. At the same time, the base potential of the transformer Q2 decreases via the capacitor CI, but due to the time constant of the resistor R and the capacitor CI, the capacitor C is charged, and the base potential of the transformer Q2 gradually increases. It rises and soon Tosinnosta Q2 turns on. At the same time, the collector potential of the transistor Q2 decreases, and the base potential of the transistor Q+ decreases via the capacitor C2, turning off the switching operation of the transistor Q1. At the same time, with the time constant of condenser 02 and resistor R2, trannostar Q
The base potential of 1 increases. The oscillation continues as described above. In order to perform this continuous operation, the collectors of the blocking oscillation circuit each have a phase of
Different signals are obtained. By directly applying this signal to the positive and negative electrodes of the piezoelectric buzzer sounding body BZ, it is possible to drive the piezoelectric buzzer with a voltage twice the power supply voltage. Therefore, the sound pressure increases.

(Effects of the Invention) According to the present invention, a piezoelectric buzzer sounding element drive circuit professional;
By driving a contact pressure type buzzer using a King oscillation circuit, high sound pressure can be obtained at low cost, and the applications are expanded and the practicality is increased.

[Brief explanation of the drawing]

Figure 1 is a drive circuit diagram of a conventional separately excited electric buzzer sounding element.
Figure 2 shows separately excited piezoelectric buzzers R1, R2 according to the present invention.
・Resistance, CI, C2... Capacitor, Ql, Q2 ・
・Transistor 2 star, R3, R4...Collector resistance, BZ
...Separately excited piezoelectric buzzer sounding body. Figure 1 r Figure 2

Claims (1)

[Claims] In a drive circuit for a two-terminal separately excited piezoelectric buzzer sounding element, a voltage with opposite positive and negative phases is directly outputted from the Pro-King oscillation circuit to generate a positive voltage of the piezoelectric buzzer sounding element. '° A drive circuit for a two-terminal separately excited piezoelectric buzzer sounding element characterized by applying voltage to the negative electrode.