JPS6248836B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method of driving a sounding body (piezoelectric buzzer, dynamic speaker, etc.).

In digital circuits, especially LSI circuits, etc., in order to obtain a synthesized sound of two frequencies, a mixing circuit using an analog circuit is required before the sounding element drive circuit.

The present invention has been made with the object of obtaining a drive system that does not require the mixing circuit described above, and achieves the above object by providing a structure in which the sounding body itself has the function of the mixing circuit. That is, the sounding body driving method of the present invention applies two waveforms with different frequencies to both ends of the sounding body, and performs amplitude modulation within the sounding body, thereby generating a synthesized sound of the sounds of the two frequencies. It is characterized by the following.

Examples will be described below.

FIG. 1 is a block diagram showing the structure of an embodiment of the present invention.

In the figure, A and B are independent oscillators, and the waveforms of their outputs a and b are as shown in the signal waveform diagram in Figure 2 (the one shown in Figure 2 is just an example). frequency is variable). Connect one of the A and B output terminals to GND. When piezoelectric buzzer (sounding body) C is connected as shown in the figure, C
The waveform of the voltage c (voltage seen from C ₂ to C ₁ ) applied to is as shown in FIG. This is a
The piezoelectric buzzer C generates a synthesized sound of a and b.

FIG. 3 is a block diagram showing the structure of another embodiment of the present invention.

As shown in the figure, when driving a dynamic speaker (sounding body) D, power a and b are amplified by transistors Tr1 and Tr2, respectively.
Similar to the piezoelectric buzzer C in Fig. 1 above, the sounding body itself D
A synthesized sound can be obtained by mixing.

Figure 4 shows A (or B) configured with LSI hardware.
The specific configuration is shown below. CG is a clock generator. DV is a frequency divider consisting of T-type flip-flops TF ₁ to _{TF 8} with reset, MD is data D1
A coincidence detection circuit detects coincidence between ~D8 and the output of the frequency divider DV, and RC is a reset circuit that latches one bit of the coincidence output from the coincidence detection circuit MD and resets the frequency divider DV. The reset circuit RC includes
A T-type flip-flop TF ₉ is included which provides a 1:1 square numbering of the reset pulses. LA is a latch circuit that temporarily stores data from the CPU (not shown).

When the currently required frequency division ratio (8 bits) is given from the data bus, the output from the frequency divider DV is
A comparison is made in the coincidence detection circuit MD, and when the contents match the contents of the latch circuit LA, a 1-bit reset pulse is generated at h of the reset circuit RC. The frequency divider DV is reset by this reset pulse and counted up until it again matches the data in the latch circuit LA. Output a has the waveform h received by T-type flip-flop _TF9 , that is, a latch circuit.
A square wave (duty 1:1) with the period of the LA data is obtained.

According to the sounding element driving method of the present invention described above, in order to generate a synthesized sound of sounds of two frequencies, there is no need for two sounding bodies or a mixing circuit, which reduces the number of parts and costs. can be measured. In particular, it is very effective when the piezoelectric sounding element is directly driven by the LSI, since the number of parts is small.

The present invention can be implemented in a melody alarm clock, a melody calculator, or the like.

[Brief explanation of the drawing]

1 and 3 are configuration diagrams showing the configuration of an embodiment of the present invention, FIG. 2 is a signal waveform diagram for explaining FIGS. 1 and 3, and FIG. 4 is a diagram similar to that shown in FIGS. 1 and 3. FIG. 2 is a block diagram showing a specific configuration of the oscillator shown in FIG. Code, A, B: Oscillator, C: Piezoelectric buzzer, D:
Dynamic speaker, Tr1, Tr2: transistor, CG: clock generator, DV: frequency divider, MD: coincidence detection circuit, RC: reset circuit,
LA: latch circuit, TF ₁ ,..., TF ₈ , TF ₉ : T-type flip-flop.

Claims (1)

[Claims] 1. A sounding body drive characterized in that two waveforms with different frequencies are applied to both ends of the sounding body and amplitude modulation is performed within the sounding body to generate a synthesized sound of the two frequencies. method.