JPS6318074Y2 - - Google Patents

Description

[Detailed explanation of the idea]

[Technical Field of the Invention] This invention relates to an envelope control device for a piezoelectric buzzer that performs envelope control by switching over time the voltage applied to the piezoelectric buzzer. [Prior art and its problems] Traditionally, small electronic devices such as electronic watches and small electronic calculators have been equipped with an alarm function that outputs an alarm sound or a musical tone function that outputs musical tones in addition to their original functions. Something is being developed. That is, the above-mentioned alarm function is used, for example, to notify the time by sounding a buzzer at a predetermined set time, and the above-mentioned musical tone function is used, for example, when operating "1" on the numeric keypad, the tone of "C" is sounded. It can also be used as a simple electronic musical instrument to confirm the operation keys by emitting a musical tone with a scale of , or a musical tone with a scale of ``d'' if you operate ``2'' (the same applies hereafter). It has been done. However, in this case, the piezoelectric buzzer has the drawback that only very monotonous sounds can be obtained at the same volume, and in particular, it cannot have a lingering sound like a natural musical instrument. [Purpose of the invention] This invention was made in view of the above circumstances, and its purpose is to perform envelope control by selectively applying multiple types of voltages with different voltage levels to both sides of a piezoelectric buzzer over time. An object of the present invention is to provide an envelope control device for a piezoelectric buzzer that provides a natural output sound. [Key points of the invention] The envelope control device for a piezoelectric buzzer according to this invention controls the voltage by switching and controlling multiple voltage sources that respectively apply voltages to the front and back sides of a sounding body in which a piezoelectric element is attached to a diaphragm. By selecting a source, the voltage level applied to each of the front and back sides of the sounding body is sequentially reduced, and an envelope is added to the sound produced by pushing and pulling the sounding body using the selected voltage source. That's what I do. [Embodiment of the invention] Hereinafter, an embodiment in which the invention is applied to a small electronic calculator will be described in detail with reference to the drawings. FIG. 1 is a circuit configuration diagram of this embodiment. In the figure, 1 is a key input section, which is equipped with various keys such as a numeric keypad and a function key.
A mode switch (not shown) is provided for switching between sound production/silence mode. This key operation signal from the key input section 1 is given to the control section 2, and the control section 2 outputs the control signal corresponding to the key operation to the ALU.
(Arithmetic circuit) 3, outputs to musical tone signal generator 4, etc.
The ALU 3 executes predetermined calculation processing according to the control signal, and also sends key input data or calculation result data to a display section (not shown). Further, the musical tone signal generating section 4 is
A basic clock from a PG (pulse generator) 5 is frequency-divided as appropriate to create musical tone signals corresponding to the operation keys, and is supplied to a buzzer drive circuit 6. In addition, the above PG
5 outputs various timing signals to drive each circuit shown in FIG. The buzzer drive circuit 6 includes a 2-bit counter 7, a decoder 8 that decodes the contents of the counter 7, and a piezoelectric buzzer 9 based on the output of the decoder 8.
(consisting of a piezoelectric element attached to a diaphragm)
It is composed of a group of switching elements that selectively apply a plurality of voltages of different levels to B ₁ and B ₂ , for example, voltages of 3V, 1.5V, and 0V. That is, the counter 7 receives a reset signal from the control section 2 to the reset input terminal R of each bit thereof, which cancels the sound generation operation of the computer.
A timing signal given from the control unit 2 from the time when the key is released from being pressed.
The contents are counted up sequentially according to 0 ₀ . From the output terminal of each bit in this counter 7, the count contents are transmitted directly and to the inverter 1.
It is applied to the decoder 8 via 0 or 11. This decoder 8 includes an AND circuit that receives a signal from the counter 7 and decodes it;
It is composed of an OR circuit that receives and outputs the content decoded by the AND circuit, and provides drive signals A to E to the switching element group according to the content of the counter 7. Table 1 shows the relationship between the contents of the counter 7 and the output of the decoder 8, that is, the drive signals A to E.

[Effect of idea]

As explained in detail above, this invention is a piezoelectric buzzer that applies voltage to both sides of a piezoelectric element to drive the piezoelectric element in a push-pull manner and outputs sounds such as musical tones or alarm sounds. By controlling the switching means to select the voltage source so that the voltage level applied to each side of the piezoelectric buzzer is sequentially lowered, and adding an envelope to the output sound, it is possible to smooth out the decaying sound, for example. , which produces a variety of excellent effects such as producing a pleasant sensation similar to that of a natural musical instrument in the listener, while being able to individually change the voltage level applied to each side of the sounding body, the number of voltage sources is It is possible to perform more detailed envelope control compared to . Furthermore, if a MOS transistor is used as the switching means, the drive circuit can be easily implemented as an LSI.

[Brief explanation of the drawing]

The drawings show an embodiment of the envelope control method for a piezoelectric buzzer according to this invention. Fig. 1 is a circuit configuration diagram when applied to a small electronic calculator, and Fig. 2 shows the operation of this embodiment. This is a timing chart for explanation. 4... Musical sound signal generation section, 6... Buzzer drive circuit, 7... Counter, 8... Decoder, 9... Piezoelectric buzzer, 10, 11... Inverter, 12a~
12h...transmission gate, 13a~
13h...Inverter, 14,16...OR circuit, 15...Inverter.

Claims (1)

[Scope of utility model registration request] A sounding body having a piezoelectric element attached to a diaphragm, a plurality of voltage sources that apply voltages to each of the front and back surfaces of the sounding body, and a switch means provided for each voltage source to control the supply of the voltage source. a voltage source selection means for controlling the switch means and selecting a voltage source applied to the sounding body from a high level to a low level over time for each of the front and back sides of the sounding body; and control means for driving the sounding body in a push-pull manner by alternately applying the respective voltage sources selected by the selection means to the front and back surfaces of the sounding body, and adding an envelope to the sound produced by the sounding body. A piezoelectric buzzer envelope control device characterized by: