JPH0286247A - Sound source circuit - Google Patents

Abstract

PURPOSE:To eliminate the need for an exclusive IC and to form an entire device inexpensively by using a microprocessor as a sound source circuit. CONSTITUTION:The microprocessor 11 is provided with a frequency signal output Os outputting a signal in a prescribed frequency being a sound source, and 1st and 2nd control output ports O1, O2 whose output levels are varied in two kinds. Then the levels of the signals outputted from the 1st and 2nd control output ports O1, O2 are combined as a desired value to change the state of power supply to an output amplifier 13, thereby outputting a continuous tone or a sound with envelope. Thus, no special IC is required and the cost is reduced.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a sound source circuit for a ring tone used in a telephone set, for example, and particularly to a sound source circuit with an envelope.

[Conventional technology]

For example, telephones often output not only intermittent tones that are a continuous tone of constant intensity interrupted at a predetermined period, but also enveloped tones in which the output sound level changes over time. Conventionally, a dedicated LSI (Large Scale Integrated Circuit) has been used as a sound source circuit for creating such various sounds, and this has been controlled according to the aspects of the various sounds.

[Problem to be solved by the invention]

For this reason, the LSIs used in these sound source circuits are special ICs whose uses are limited, resulting in an increase in cost.

SUMMARY OF THE INVENTION An object of the present invention is to provide a sound source circuit that can output enveloped sound using a general-purpose IC.

[Means to solve the problem]

In the present invention, (1) a frequency signal output terminal that outputs a signal of a predetermined frequency, and a first terminal that changes the voltage level in two values.
and a second control output terminal;
) a series circuit consisting of a resistor and a capacitor connected between the first and second control output terminals, and (ii
i) A diode whose cathode side is connected to the connection point between one end of this resistor and the capacitor, and whose anode side is grounded or connected to the other end of this resistance, and (1V) a buffer amplifier whose input side is connected to this connection point. and (V) an output amplifier that receives a signal from the frequency signal output terminal described above and is supplied with power by the buffer amplifier described above.

By combining the levels of the signals output from the first and second control output terminals to a desired value, the state of power supply to the output amplifier is changed, and continuous sound or enveloped sound is output. be able to do so.

〔Example〕

The present invention will be described in detail with reference to Examples below.

FIG. 1 shows the circuit configuration of a tone generator circuit in one embodiment of the present invention.

This sound source circuit is equipped with a one-chip microprocessor 11 for performing various controls. This microprocessor 11 has a frequency signal output port 0. and the first one that changes the output level into two logic levels: I (high) and L (low).
and a second control output port ○4.02.

The frequency signal output capacitor (Os) is connected to the base of a transistor 13 via a base resistor 12. This transistor 13 has a role as an output amplifier, and its emitter is grounded, and the collector outputs a sound source output 14. The collector of the transistor 13 is also connected via a load resistor 15 to the output side of an operational amplifier 16 serving as a buffer amplifier.

On the other hand, the first control output port O1 is connected to the (2) input terminal of the operational amplifier 16 via a series circuit consisting of an output port protection resistor 18 and a capacitor 19. The e input terminal of this operational amplifier 16 is connected to its output terminal. The second control output port 02 is connected to the O input terminal of the operational amplifier 16 via a resistor 21, and the cathode side of a diode 22 whose anode side is grounded is connected to this connection point.

In order to output an envelope sound with such a groove-bottom sound source circuit, an audible frequency signal 25 of a predetermined frequency is output from the frequency signal output port OS.

In this state, the second control output port 02 outputs an L level signal as the second control signal 26, and the first control output port ○ changes from the L level to the H level as the first control signal 27. Outputs a signal to Then, a differential waveform with a time constant determined by the capacitor 19 and the resistor 21 is generated, and as a result, power is supplied from the output side of the operational amplifier 16 to the transistor 13 with a voltage varying over time. As a result, an enveloped sound signal is output as the sound source output 14. The length of the envelope sound can be freely set by adjusting the values of the capacitor 19 and resistor 21 described above.

On the other hand, when creating a continuous sound of a constant frequency, the first control signal 2 is output while the audible frequency signal 25 is being output.
7 and the second control signal 26 may both be maintained at H level. The first control signal 27 may be set to L level, and the second control signal 26 may be set to H level.

[Modified example]

FIG. 2 shows a modification of the invention.

Components that are the same as those in FIG. 1 are designated by the same reference numerals, and their description will be omitted as appropriate.

Now, in this modification of the sound source circuit, a first relay 31 consisting of an excitation coil and a contact is disposed between the first control output port 01 and the capacitor 19. Further, the anode of the diode 22 is connected to one end of the resistor 21 without being grounded. Then, this connection point and the second control output capo)02
A second relay 32 consisting of an excitation coil and contacts is arranged between the two.

That is, in this modification, two output boats O, 02
By arranging the relays 31 and 32 on the side, the current driving ability of the buffer amplifier 16 placed on the contact side thereof is increased.

〔Effect of the invention〕

As described above, according to the present invention, since a microprocessor is used as the sound source circuit, a dedicated IC is not required, and a general-purpose microprocessor used for controlling electronic equipment can also be used as the sound source circuit. Therefore, the entire device can be manufactured at low cost.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram of a sound source circuit in an embodiment of the present invention,
FIG. 2 is a circuit diagram of a sound source circuit in a modification of the present invention. 11...Microprocessor, 13...
Transistor, 16... Buffer amplifier, 19... Capacitor, 21... Resistor, 22... Diode,
0 + 02 ... Control output port, frequency signal output port. Applicant NEC Co., Ltd.

Claims (1)

[Claims] A frequency signal output terminal that outputs a signal at a predetermined frequency;
an integrated circuit having first and second control output terminals that change the output level in binary values; a series circuit comprising a resistor and a capacitor connected between the first and second control output terminals; a diode whose cathode side is connected to the connection point between one end of the resistor and the capacitor, and whose anode side is grounded or connected to the other end of the resistor; a buffer amplifier whose input side is connected to the connection point; and the frequency signal output. A sound source circuit comprising: an output amplifier that receives a signal from a terminal and is supplied with power by the buffer amplifier.