JPH02223999A - Sound generation driving circuit - Google Patents

Abstract

PURPOSE:To select and output the best driving signal to a sound generation body by detecting a voltage produced at the sound generation body owing to the driving signal which is generated by a driving signal generating circuit and specifying the best driving signal corresponding to the detected voltage value. CONSTITUTION:This circuit has transistors (TR) 1a-1d which turn on when '0' is inputted, a TR 2 which turns on when '1' is inputted, and an inverter circuit 3, and the driving signal generating circuit 4 is composed of them. Further, the circuit is provided with a voltage detecting means 7 which detects the voltage generated by the sound generation body 5 with the driving signal generated by the driving signal generating means 4 and a driving signal control circuit 14 which specifies the optimum driving signal among respective driving signals in accordance with the detected voltage value and generates it by the driving signal generating circuit 4. Consequently, the optimum driving signal is selected in accordance with the voltage value to generate invariably constant sound pressure and sound volume.

Description

[Detailed description of the invention] [Industrial application field 1 The present invention relates to a sound generation drive circuit.

[Prior Art] Conventionally, for example, a sound drive circuit that generates an alarm sound for a clock is designed to generate a predetermined drive output.

[Problems to be Solved] In the conventional sound generation drive circuits described above, distortion often occurs in the sound emitted from the sound generation body due to variations in the impedance of the sound generation body and the drive capacity of the output stage for driving the sound generation body. It is.

Particularly when outputting a melody, there is a problem that distortion occurs in the envelope waveform or sound due to saturation of the drive circuit depending on the magnitude of the drive capacity when performing attenuation envelope width modulation or chord synthesis.

SUMMARY OF THE INVENTION An object of the present invention is to provide a sound generation drive circuit that selects and outputs an optimal drive signal for a connected sounding body.

[Means for Solving the Problems] The present invention provides a drive signal generation circuit that selectively generates one of a plurality of types of drive signals for driving a sounding body, and a drive signal generated from the drive signal generation circuit. Voltage detection means for detecting the voltage generated in the sounding body by the signal, and a drive signal generating circuit that specifies the optimum drive signal among the drive signals according to the voltage value detected by the voltage detection means and generates it from the drive signal generation circuit. The above-mentioned problem is solved by providing a drive signal control circuit for controlling the drive signal.

〔Example〕

Hereinafter, one embodiment of the present invention will be described based on the drawings.

In Figure 1, 1a to 1d are transistors that become conductive when "0" is input, and the ratio of their output currents is 1a:1b:lc:1d-1:2:4:8. . 2 is a transistor that becomes conductive when "1" is input, and 3 is an inverter circuit. Drive signal generation circuit 4 is constituted by 1a to 1d12 and 3. 5 is a sounding body, 6 is an output transistor for driving the sounding body 5, and 7 is a voltage detection means that generates an output "1" when the voltage at the terminal E becomes less than a predetermined value. 8 is a D type. Flip-flops, 9 is a counter, 10a to 10d and 11
13 are gate circuits, and these constitute the drive signal control circuit 14.

Next, the operation will be explained with reference to the time chart shown in FIG. First, at the alarm time, due to the operation of the alarm switch (not shown), terminal A becomes O'' as shown in Fig. 2A, and a lock pulse is generated at terminal B as shown in Fig. 2B. In addition, a pulse for sound generation as shown in FIG. 2 C is supplied to the terminal C. The reset of the D-type flip-flop 8 and the counter 9 is canceled when the terminal A becomes "0". Now, since the transistor 6 is off, the output of the voltage detection means 7 is "0", and since the D input of the p-type flip-flop 8 is "O#", "1" is output from the output Q, and the terminal C '' is supplied to the counter 9 via the gate circuit 11.

First, the output terminal Q1 of the counter 9 becomes "B" due to the first pulse from the gate circuit 11, and the gate circuit 10a
The output of the transistor becomes "O", and the transistor 1a becomes conductive. At this time, since the output "1" of the terminal C' is inverted to "0" by the inverter circuit 3 and supplied to the transistor 2, the transistor 2 is in an open state. Therefore, the output current from the transistor 1a is supplied to the terminal D', thereby making the transistor 6 active. Since the voltage at the terminal E at this time is higher than the predetermined voltage V as shown in FIG. 2E, the voltage detection circuit 7 outputs O°. Therefore, the output of the gate circuit 13 remains at O".

Therefore, when the output terminal Q2 of the counter 9 becomes "1" by the next pulse from the terminal C', the transistor b becomes conductive, and a current twice as large as that in the above case flows through the terminal D'. If the voltage at the terminal E is higher than the predetermined voltage V as shown in FIG. 2E, the output of the voltage detection circuit 7 is "0" and the output of the gate circuit 13 also remains at "0".

Therefore, when the next pulse is further supplied to the counter 9, its output terminals Q and Q2 become "1", thereby transistors a and 1b become conductive, and the terminal D has the same voltage as when only the transistor a is used. Three times as much current flows.At this time, if the voltage at terminal E is lower than the predetermined voltage V as shown in FIG. 2E, the output of voltage detection circuit 7 is "
1m, and the output of the gate circuit 13 also becomes "1".

Therefore, the D input of the D type flip-flop 8 is “1”.
Then, the next pulse from terminal B causes the output Q to become "0". This closes the gate circuit 11, stops the counter 9, and keeps its output terminals Q1 and Q2 selected. Therefore, from now on, three times as much current flows through the sounding element 5 as when only the transistor a is used, and the sounding element 5 continues to be driven at the optimum voltage.

Through the above operations, automatic control is performed such that transistors a to 1d are appropriately selected depending on the sounding body to be connected, and are driven by an optimal drive signal.

[Effects] According to the present invention, the voltage applied to the sounding body is detected and the optimal drive signal is selected according to the voltage value, so even if there are variations in the output current of the drive circuit or the impedance of the sounding body, the voltage applied to the sounding body is detected. , it is possible to always generate a constant sound pressure and volume, and it is possible to eliminate the occurrence of distortion and the like.

Therefore, for example, if the sound generation drive circuit of the present invention is used in a watch with an alarm function, even if the same product is used, the circuit components of each watch will have some errors in terms of performance. It is possible to drive the sounding body with the optimal drive signal and generate an alarm sound without distortion.

[Brief explanation of the drawing]

FIG. 1 is an electric circuit diagram showing an embodiment of the present invention, and FIG. 2 is a time chart for explaining the operation of FIG. 1. 4... Drive signal generation circuit 7... Voltage detection means 14... Drive signal control circuit and above Applicant Seikosha Co., Ltd.

Claims (1)

[Claims] A drive signal generation circuit that selectively generates one of a plurality of types of drive signals for driving a sounding body; a voltage detection means for detecting voltage; a drive signal control circuit that specifies an optimal drive signal among the drive signals and causes the drive signal generation circuit to generate the optimum drive signal according to the voltage value detected by the voltage detection means; A sound generation drive circuit comprising: