JPH0136295B2 - - Google Patents

Description

[Detailed Description of the Invention] [Summary] The purpose of this invention is to reduce harmonic distortion in the sound generated by a sounder and obtain a sound suitable for a telephone ring tone. a third constant current circuit that operates at a constant current based on the output of a third transistor switch that switches based on the output of the current mirror circuit; and a first current mirror circuit that is connected to the output of the second constant current circuit. A fourth constant current circuit is provided that operates at a constant current based on the output of a fourth transistor switch that switches based on the output, and when the first current mirror circuit is inactive and the second
By operating the current mirror circuit, the first
and turn off the fourth transistor switch, the second
and turning on a third transistor switch;
By turning on the first and fourth transistor switches and turning off the second and third transistor switches, with the first current mirror circuit operating and the second current mirror circuit not operating, 1st
A capacitive sounder connected to the output of the constant current circuit and the output of the second constant current circuit is connected to both ends of the output signal of the output of the first and second constant current circuits, the polarity of which is alternately inverted. It is described that a rectangular wave is applied and the voltage waveform is controlled to be a trapezoidal or triangular wave by the capacitance inside the sounder.

[Industrial application field]

The present invention relates to a telephone calling sounder drive, and more particularly to a telephone calling sounder drive of the type using an audible alternating current signal.

[Prior art and problems to be solved by the invention]

Conventionally, in a telephone ringing circuit, an audible alternating current signal is generated using a power source obtained by rectifying a ringing signal, and in order to generate a telephone ring tone using the generated audible alternating current signal, a rectangular wave signal is converted to a piezoelectric sounder. may be applied, thereby producing a ringing tone.

However, in this case, since the signal applied to the piezoelectric sounder is a rectangular wave, the harmonics of the rectangular wave appear as sound, resulting in a distorted sound (for example, a desired sound such as "Korokoro"). There is a problem in that an unpleasant sound such as "chii" is added to the image.

An object of the present invention is to reduce distortion in the sound generated by the sounder, and to reduce distortion in the sound generated by the sounder, with respect to a ring sounder drive circuit for a telephone that uses an audible alternating current signal, based on the idea of introducing a constant current circuit into the drive circuit. It's about getting the right thing.

[Means for solving problems]

In the present invention, in a telephone calling sounder drive device that drives a capacitive sounder, first current mirror circuits 111, 112, 11 to which signals from the audible signal generation circuit 4 are input are provided.
3. A second current mirror circuit 114, 11 into which an inverted signal of the signal from the audible signal generation circuit is input.
5,116, first transistor switch 1 that performs switching operation by first current mirror circuit output
21. Second transistor switch 1 that performs switching operation based on the output of the second current mirror circuit
22. A first constant current circuit 13 that operates at a constant current based on the output of the first transistor switch; a second constant current circuit 14 that operates at a constant current based on the output of the second transistor switch; a capacitive sounder 7 connected to the output of the second constant current circuit; a third transistor switch 123 connected to the output of the first constant current circuit and switched by the output of the second current mirror circuit; a fourth transistor switch 124 that performs switching based on the output of a first current mirror circuit connected to the output of the constant current circuit; a third constant current circuit 15 that operates with a constant current based on the output of the third transistor switch; A fourth constant current circuit 16 is provided which operates at a constant current based on the output of the transistor switch 4, and when the first current mirror circuit is inoperative and the second
By operating the current mirror circuit, the first
and turn off the fourth transistor switch, the second
and turning on a third transistor switch;
By turning on the first and fourth transistor switches and turning off the second and third transistor switches, with the first current mirror circuit operating and the second current mirror circuit not operating, A rectangular wave of an output signal with the polarity of the outputs of the first and second constant current circuits alternately inverted is applied to both ends of the capacitive sounder, and the voltage waveform is changed to a trapezoidal or triangular wave depending on the capacitance inside the sounder. There is provided a telephone calling sounder driving device, characterized in that the sounder driving device is controlled so that:

〔Example〕

FIG. 1 shows a telephone calling sounder driving device as an embodiment of the present invention. The sounder drive device includes transistors 111, 112, 113, 1.
First and second current mirror circuits consisting of 14, 115 and 116 are provided.

The signal from the audible signal generation circuit is sent to the current mirror circuit through gate circuit 6 and resistors 117 and 11.
8. Transistor 111,1
16 collector circuits, first to fourth switching transistors 121, 122, 12
3,124 base circuits are connected. First and second constant current circuits 13 and 14 are connected to the emitter circuits of the transistors 121 and 122, and third and fourth constant current circuits 15 and 16 are connected to the collector circuits of the transistors 123 and 124, respectively. . In both constant current circuits, the transistor 13
1, 141, 151, 161 and a resistor 13 connected between the base and emitter of the transistor.
2,142,152,162.
Emitter of transistor 123 and transistor 1
A sounder 7 is connected between the 24 emitters.

When transistors 111, 112, and 113 are all off and transistors 114, 115, and 116 are all on, transistors 121, 1
24 are both off, transistors 122, 12
3 are all turned on, and the output terminals 171, 17
2, a voltage is applied to the sounder 7 with the side 172 as the positive electrode. On the contrary, transistor 11
When transistors 1, 112, and 113 are all on, and transistors 114, 115, and 116 are all off, transistors 121 and 124 are all on, and transistors 122 and 123 are both off, and from the output terminal, the 171 side A voltage is applied to the sounder 7 using the positive electrode as the positive electrode. Constant current circuit 1
3, 14, 15, 16, the current supplied to the piezoelectric sounder as a capacitive load is trapezoidal, reducing harmonic distortion.

As is clear from the frequency spectrum, the level of harmonic components is lower than that of the rectangular wave, harmonic distortion is reduced, and a pleasant ring tone can be generated. As an example, according to the device shown in Figure 1, 1200Hz
The degree of distortion expressed by the ratio of the signal level of 2400Hz to the level of the 2400Hz harmonic signal is approximately 10dB.
Improved.

The sounder drive device of FIG. 1 is used, for example, as a sounder drive device in the telephone calling circuit shown in FIG. The telephone calling circuit shown in FIG. 2 is connected in parallel with the subscriber telephone at the point of connection of the subscriber line to the telephone by means of its input terminals P ₁ and P ₂ . Input terminal P ₁ ,
Rectifier 221, 2 via capacitor 21 to P ₂
Full wave rectifier circuit 22 consisting of 22, 223, 224
is connected. One terminal of the rectangular wave signal generating circuit 3 is connected to one of the output terminals of the full wave rectifier circuit 22, and the other terminal of the rectangular wave signal generating circuit 3 is connected to a capacitor 91, a zener diode 92, and an audible signal. One terminal of the generation circuit 4 and the timing circuit 5 are connected to each other. One terminal of the sounder drive circuit 1 is connected to the other terminals of the Zener diode 92, the audible signal generation circuit 4, and the timing circuit 5, and the other terminal of the sounder drive circuit 1 is connected to the output terminal of the full-wave rectifier circuit 22. connected to the other. The control output of the rectangular wave signal generation circuit 3 controls the timing circuit 5. The control output S _c of the audible signal generation circuit 4 and the timing circuit 5 passes through a gate 6 and becomes a control input to the sounder drive circuit 1 . The sounder drive circuit 1 drives a speaker as a sounder or a piezoelectric sounder 8 (Patent application filed by the present applicant in 1983).
74923 (Japanese Unexamined Patent Publication No. 57-190448) "Paging circuit for telephone").

In the device of FIG. 1, the voltage waveform appearing at terminal 171 is shown in FIG. 3A, and the voltage waveform appearing at terminal 172 is shown in FIG. 3B. Originally,
Due to the presence of the constant current circuit, the voltage waveform that should appear as a rectangular wave indicated by a broken line changes to a waveform that has slopes at the rising and falling edges. A, B
Output terminal 171,1 as the sum of both waveforms
The voltage waveform appearing between 72 and 72 becomes a trapezoidal or triangular wave as shown in FIG. 4, and harmonic distortion is reduced compared to the conventional one.

〔Effect of the invention〕

According to the present invention, in operation of a telephone ringing sounder, a constant current rectangular wave is supplied to a capacitive sounder, and the voltage waveform becomes a trapezoidal or triangular wave due to the internal capacitance of the capacitive sounder, thereby causing harmonic distortion. The distortion in the sound generated by the sounder is reduced and a suitable telephone ring tone is obtained.

[Brief explanation of drawings]

FIG. 1 is a circuit diagram showing a telephone calling sounder driving device as an embodiment of the present invention, and FIG.
A circuit diagram showing a telephone calling circuit to which the sounder drive device shown in the figure is applied, and FIGS. 3 and 4 are waveform diagrams for explaining the operation of the sounder drive device shown in FIG. 1. 1... Sounder drive circuit, 21... Capacitor, 22... Full wave rectifier circuit, 221, 222, 2
23, 224... Rectifier, 3... Rectangular wave signal generation circuit, 4... Audible signal generation circuit, 5... Timing circuit, 6... Gate circuit, 7... Sounder, 9
1... Capacitor, 92... Zener diode,
_P1 , _P2 ...Input terminals.

Claims (1)

[Claims] 1. In a telephone calling sounder drive device that drives a capacitive sounder, first current mirror circuits 111, 112, 11 to which signals from the audible signal generation circuit 4 are input.
3. A second current mirror circuit 114, 11 into which an inverted signal of the signal from the audible signal generation circuit is input.
5,116, first transistor switch 1 that performs switching operation by first current mirror circuit output
21. Second transistor switch 1 that performs switching operation based on the output of the second current mirror circuit
22. A first constant current circuit 13 that operates at a constant current based on the output of the first transistor switch; a second constant current circuit 14 that operates at a constant current based on the output of the second transistor switch; a capacitive sounder 7 connected to the output of the second constant current circuit; a third transistor switch 123 connected to the output of the first constant current circuit and switched by the output of the second current mirror circuit; a fourth transistor switch 124 that performs switching based on the output of a first current mirror circuit connected to the output of the constant current circuit; a third constant current circuit 15 that operates with a constant current based on the output of the third transistor switch; A fourth constant current circuit 16 is provided which operates at a constant current based on the output of the transistor switch 4, and when the first current mirror circuit is inoperative and the second
By operating the current mirror circuit, the first
and turn off the fourth transistor switch, the second
and turning on a third transistor switch;
By turning on the first and fourth transistor switches and turning off the second and third transistor switches, with the first current mirror circuit operating and the second current mirror circuit not operating, A rectangular wave of an output signal obtained by alternately inverting the polarity of the output of the first and second constant current circuits is applied to both ends of the capacitive sounder, and the voltage waveform is changed to a trapezoidal or triangular wave depending on the capacitance inside the sounder. A sounder drive device for telephone calling characterized by being controlled so that: