JPS58161454A - Telephone set circuit - Google Patents

Abstract

PURPOSE:To simplify the construction of a push button, by replacing mechanical common contacts of the push button switch by the 1st, the 2nd and the 3rd switching elements, and obtaining an oscillation signal without chattering. CONSTITUTION:When the push button is depressed, a frequency contact 31 is activated, the information is detected at an oscillation circuit 32, an oscillation signal is outputted via a resistor 33, a depression signal is outputted from a control output terminal 34 and fed to a control input terminal 60 of a switch control circuit 6. A signal turning off a PNP transistor (TR)7 is outputted from the 1st output terminal 61 of a switch control circuit 6 to disconnect a channel circuit 5 from a line terminal 1. Simultaneously, a signal turning on an NPN TR8 is outputted from the 2nd output terminal 62 of the circuit 6, both end terminals of the channel circuit 5 are short-circuited and an oscillation signal from a resistor 33 is fed to a line terminal 2. Further, a signal turning on a NPN TR9 is outputted from the 3rd output terminal 63 of the circuit 6 to connect a resistor 10 in parallel with a resistor 4.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a telephone circuit, and particularly to a telephone circuit for a two-frequency composite signal type pushbutton dial telephone. A system is adopted in which the dial oscillation circuit and the telephone call circuit are switched using the mechanical contacts of the button dial.
3 is a dial oscillation circuit, which includes a common contact 30 that operates in common to all push buttons, and a dial oscillation circuit that operates in response to each push button (
◎ In Fig. 1, all the push buttons are pressed. When not connected, the communication circuit 5 is connected to the line terminals 1 and 2 by the common contact 30, and the oscillation circuit 32 is disconnected from the line terminal 1. When the push button is pressed, the common contact 30 is activated, the communication circuit 5 is disconnected from the line terminal 1, the oscillation circuit 32 is connected to the line terminals 1 and 2, and the frequency corresponding to the pressed button is activated. When the contact 31 operates, the oscillation circuit 32 oscillates a corresponding frequency, which is outputted between the line terminals 1 and 2 via the output resistor 33.

In the telephone circuit configured in this manner, the mechanical contact 30 is used to switch between the dial oscillation circuit 3 and the telephone call circuit 5, so the dial signal may be interrupted by several m5eC due to the chattering phenomenon of the mechanical contact during switching. This had the disadvantage that the effective signal time was shortened.

Furthermore, since the pushbutton switch included in the dial oscillation circuit 3 includes both the common contact 30 and the frequency contact 310, its mechanism is complicated and expensive.

The present invention solves these two drawbacks and provides a telephone circuit that sends out high-quality dialing signals without chattering using a simple push-button switch.

According to the present invention, the first and second line terminals, the dial oscillation circuit, the first and second resistors, the communication circuit, the switch control circuit, the first . second and third switching elements, the first line terminal is connected to the positive power supply terminal of the dial oscillation circuit and one end of the N1 switching element, and the other end of the first switching element between the positive power supply terminal of the communication circuit and the first switching element of the second switching element.
and connect the second line terminal to one end of the first resistor, the negative power terminal of the communication circuit, the other end of the second switching element, and one end of the M3 switching element. and the other end of the third switching element is connected to the negative power supply terminal of the dial oscillation circuit and the other end of the first resistor via the second resistor, and the dial oscillation circuit is controlled. An output terminal is connected to an input terminal of the switch control circuit, a first output terminal of the switch control circuit is connected to a control input terminal of the first switching element, and a second output terminal of the switch control circuit is connected to the second output terminal. A telephone circuit is obtained, characterized in that the output terminal of N3 of the switch control circuit is connected to the control input terminal of the switching element of , and the output terminal of N3 of the switch control circuit is connected to the control input terminal of the third switching element.

Next, one embodiment of the present invention will be explained with reference to the drawings.0 Fig. 2 is a block circuit diagram of one embodiment of the present invention.
．． 2 is a first and second line terminal terminal, 3 is a dial oscillation circuit, 4 is a resistor for a first bias to the dial oscillation circuit 3, 5 is a communication circuit, 6 is a switch control circuit 4,
Furthermore, the dial oscillation circuit 3 includes a frequency contact 31 that operates (makes) in response to each push button, an oscillation circuit 32, and an output resistor 33.

Then, the first line terminal 1 is connected to the dial oscillation circuit 3.
positive power supply terminal and PNP as the first switching element
The collector of the PNP transistor is connected to the positive power terminal of the communication circuit 5 and the collector of the NPN transistor 8 as a second switching water element, and the second line terminal 2 is connected to the terminal of the NPN transistor 8. One end of the first resistor 4 and the negative power supply terminal of the communication circuit 5 are connected to the emitter of the NPN transistor 8 and the emitter of the NPN transistor 9 as the third switching element. ;- A receiver is connected to the negative power supply terminal of the dial oscillation circuit 3 and the other end of the first resistor 4 via the second resistor 10, and the control output terminal 34 of the dial oscillation circuit 30 is connected to the Connect the switch control circuit 60 to the input terminal 60, connect the first output terminal 6.1 of the switch control circuit 6 to the pace of the PNP'h lung staff, and connect the output terminal 62 of the bag 2 of the switch control circuit 6 to the front. eNPN) The third output terminal 63 of the switch control circuit 6 is connected to the NPN based on the run raster 80.
) Connect to each of the run raster 90 bases.

When the push button is not pressed, frequency contact 3it:
i is not operating, and the oscillation circuit 32 detects that the oscillation output is not sent to the resistor 33, and a signal indicating no press is output to the control output terminal 34, and this output is output to the switch 1.
It is transmitted to the control input terminal 60 of the switch control circuit 60, outputs from the output terminal 61 of the switch control circuit 60 stripe 1 a signal for turning on the Langstaff (f'NP), and outputs a signal to turn on the Langstaff, and the signal is transmitted from the 20th output terminal 62 of the switch control circuit 60 to the 20th output terminal 62 of the pure circuit 6. A signal that turns off the N P N transistor 8 is output, and a signal that turns off the N P N transistor 9 is output from the third output terminal 63 of the switch flii control circuit 6. Therefore, P.N.
P) The communication circuit is connected to the line terminals 1 and 2 by turning on the Langistaph. At this time, the oscillation output of the oscillation circuit 320 operates as if it were not used. Further, the oscillation circuit 32 is biased by the resistor 4 (6).

When the square button is pressed, the frequency contact 31 operates,
The information is detected by the oscillation circuit 32, and an oscillation signal is outputted via the resistor 33, and at the same time, a press signal is outputted from the control output terminal 34 and transmitted to the control input terminal 60 of the switch-j control circuit 6. A signal is output from the first output terminal 61 of the switch control circuit 6 to disconnect the PNPN transistor 8, disconnecting the communication circuit 5 from the line terminal l. A signal to turn on is output, short-circuiting the communication circuit 50 and connecting the oscillation signal from the resistor 33 to the line terminal 2. Furthermore, a signal is output from the third output terminal 63 of both switch 'ftrlj circuits 6 to turn on the NPN) transistor 9, and the resistor 10 is connected in parallel to the resistor 4.

By connecting this resistor 1Otl and resistor 4 in parallel, the oscillation circuit 320 circuit current increases to a large arc during oscillation compared to when it does not oscillate, so the bias resistance value that supplies the current necessary for its operation is reduced. This is because there is a breathtaking view. The tab oscillator circuit 32 operates to detect the operation of the frequency contact 31 with a circuit current of the required III/J- limit (normally 100 μA or less) so as not to become a load on the communication circuit 5 when it is not oscillating. , when the operation of the frequency contact 31 is detected, it oscillates to send an oscillation signal between the line terminals 1 and 2, but in order to send the oscillation signal without distortion, a circuit that requires several orders of magnitude more current than is required when no oscillation is required. Since a current (usually more than a few meters) is required, when there is no oscillation, the bias resistor should be a large resistor to lighten the load on the communication circuit 5, and when oscillation, undistorted oscillation output is sent between the line terminals 1 and 2. It is necessary to reduce the bias resistance value so that Usually, the resistor 4 is selected to be 10 kg or more, and the resistor 9 is selected to be several thousand.

As explained above, the present invention makes it possible to obtain a chattering-free oscillation signal by replacing the mechanical common contacts of a push button switch with first, second, and third switching elements, and to switch It has an economical effect of simplifying the structure.

[Brief explanation of the drawing]

FIG. 1 is a block circuit diagram showing an example of a conventional circuit, and FIG. 2 is a block diagram showing an embodiment of the present invention. 1...Line terminal, 2...Line terminal, 3
......Dial oscillation circuit, 4--Resistor, 5-
...Telephone circuit, 6...Switch control circuit, 7...PNP) transistor, 8...
NPN) transistor, 9--N P N transistor, 10...-resistor, 30... common contact, 3
1...Frequency contact, 32...Oscillation circuit, 33...-Resistor, 34...Control output terminal, 60...Control input terminal, 61...- Control output terminal, 62... Control output terminal, 63...
...Control output terminal.

Claims (1)

[Claims] first and second line terminals, a dial oscillation circuit, and a first
and a second resistor, a communication circuit, a switch control circuit, and a first. The second and jI3 switch elements are connected to one end of the second switching element, and the second line terminal is connected to one end of the first resistor, the negative power terminal of the communication circuit, and I
The other end of the switching element jI2 is connected to one end of the third switching element, and the other end of the third switching element is connected to the negative power supply terminal of the dial oscillation circuit through the second p resistor. A control output terminal of the dial oscillation circuit is connected to an input terminal of the switch control circuit, and a first output terminal of the switch control circuit is connected to the other end of the first switching element. A second output terminal of the switch control circuit is connected to a control input terminal of the second switching element, and a third output terminal of the switch control circuit is connected to a control input terminal of the jI3 switching element. Telephone circuit characterized by connecting @