JPS58161455A - Telephone set circuit - Google Patents

Abstract

PURPOSE:To simplify the construction of a push button switch, by replacing mechanical common contacts of the push button switch by the 1st and the 2nd 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 an NPN transistor(TR)7 is outputted from the 1st output terminal 61 of the circuit 6 to disconnect a channel circuit 5 from a line terminal 2. Further, a signal turning on a PNP TR8 is outputted from the 2nd output terminal 62 of the circuit 6 to connect a resistor 9 in parallel with a resistor 4.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a telephone circuit, and more particularly to a telephone circuit for a push-button dial telephone using a two-frequency composite signal system.

Conventionally, as shown in FIG. 1, this type of telephone circuit has adopted a system in which a mechanical contact of a push button dial is used to switch between a dial oscillation circuit and a speech circuit. That is, ll!
, in Figure 1, l and 2 are j1!1 and jI2, respectively
0 line terminal, 3 is a dial oscillation circuit, which includes a common contact 3-0 that operates in common to all push buttons, a frequency contact 31 that operates (makes) corresponding to each push button, and an oscillation circuit 32. It includes an output resistor 33, 4 is a bias resistor to the dial oscillation circuit 3, and 5 is a communication circuit. In FIG. 1, when all the push buttons are not pressed, the common contact 30 connects the communication circuit 5 to the Ii circuit end terminal and 2, and the oscillation circuit 32 is disconnected from the line terminal 1. @ When the push button is pressed, the common contact 3G is activated, the communication circuit 5 is disconnected from the line terminal 1, and the oscillation circuit M32 is
It is connected to circuit terminals 1 and 2, and when pressed, the frequency contact 31 corresponding to the reminder button operates, and the oscillation circuit 32 oscillates the corresponding frequency, which is output via the output resistor 33 between the terminals 1 and 2. be done.

In the telephone set configured in this manner, the mechanical contact 30 is used to switch between the dial oscillation circuit 3 and the call number wr5, so the dial signal may emit several m5ec due to the chattering phenomenon of the mechanical contact at the time of switching. The shortcoming is that the signal is interrupted and the effective signal time is shortened.

Furthermore, since the pushbutton switch included in the dial oscillation circuit 3 includes both a common contact 30 and a frequency contact 31, 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, first and second line terminals, a dial oscillation circuit, first and jI2 resistors, a communication circuit,
It includes a switch control circuit and first and second switching elements, and the first line terminal is connected to one end of the first resistor, one end of the second switching element, and the positive side of the communication circuit. A negative power terminal of the communication circuit is connected to one end of the first switching element, and the other end of the second switching element is connected to the first O resistor through the second resistor. the other end of the device is connected to the positive power supply terminal of the dial oscillation circuit, and the second line terminal is connected to the negative power supply terminal of the dial oscillation circuit and the other end of the first switching element. A control output terminal of the switch control circuit is connected to an input terminal of a switch control circuit, a first output terminal of the switch control circuit is connected to the control input terminal of the first switching element O, and a second output terminal of the switch control circuit is connected to the control input terminal of the first switching element O. 1! A telephone circuit is obtained, which is characterized in that it is connected to the control input terminals of the switching elements c2, respectively.

Next, one embodiment of the present invention will be described with reference to the drawings. @Figure 2 is a block circuit diagram of one embodiment of the present invention.1.
2 is the first and second ll1i path terminals, 3 is a dial oscillation circuit, 4 is a resistor for biasing JIII to the dial oscillation circuit 3, 5 is a communication circuit, and 6 is a switch control circuit I.
It is. 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 o line terminal 1 is connected to the first o line terminal 1 of the first resistor 4.
The end and the emitter of the PNP transistor 8 as the 20th switching element are connected to the positive power supply terminal of the communication circuit S, and the negative power supply terminal of the communication circuit 5 is connected to the collector of the NPN transistor 8 as the first switching element. The collector of the PNP transistor 8 is connected to the other end of the #11 resistor 4 and the positive power supply terminal of the dial oscillation circuit 3 via the 20th resistor 9, and the
0Iw path terminal 2 is connected to the negative power supply terminal of the dial oscillation circuit 3 and the input terminal of the NPN transistor, and the control output terminal 34 of the dial oscillation circuit 30 is connected to the input terminal 60 of the switch control circuit 60. The 10th output terminal 61 of the control circuit 6 is connected to the NPN transistor 0 pace, and the 20th output terminal 62 of the switch control circuit #66 is connected to the base of the PNP transistor 80.

When the pushbutton is not pressed, the frequency contact 31 is inactive, and this is detected by the oscillation circuit 32,
No oscillation output is sent to the resistor 33, and a signal indicating no press is output to the control output terminal 34. This output signal is transmitted to the control input terminal 60 of the switch control circuit 60, and the w! of the switch control circuit 6 is output. l A signal to turn on the NPN transistor is output from the output terminal 61, and a signal to turn off the PNP transistor 8 is output from the *2O output terminal 62 of the switch control circuit 6.A Therefore, the NPN transistor is turned on. As a result, the communication circuit 5 is connected to the line terminals 1 and 2. Also, at this time, the oscillation circuit 32 is biased only by the resistor 4.

When the push button is pressed, the frequency contact 31 operates,
The information is detected by the oscillation circuit 32, and an oscillation signal is output through the resistor 33, and at the same time, a press signal is output from the control output terminal 34 and transmitted to the switch control circuit 60 control input terminal 60, and the switch control circuit A signal is output from the first output terminal 61 of the switch control circuit 6 to turn off the NPN transistor 7, and the communication port wI5 is disconnected from the line terminal 2. A signal is output to turn on resistor 9 and connect resistor 4 in parallel.

Connecting this resistor 9 in parallel with the resistor 4 is necessary because the circuit current of the oscillation port I@32 increases greatly during oscillation compared to when there is no oscillation, so a bias resistor is used to supply the current necessary for the operation. This is because it is necessary to reduce the value. Tsut
The oscillator circuit 32 uses the minimum required circuit current (usually 100
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 the oscillation signal is transmitted without distortion. In order to send out a current with no oscillation, a circuit current several orders of magnitude higher than the current required during no oscillation (usually several mA or more) is required, so the bias resistance should be a large resistor during no oscillation.
It is necessary to reduce the load on the communication circuit 5 and to reduce the bias resistance value so that an undistorted oscillation output is sent between the Ifs1111 terminals 1 and 2 during oscillation. Usually resistor 4 is lQk
g or more, and resistor 9 is selected to be several hundred ohms or less @ As explained above, the present invention replaces the mechanical common contact of the push button switch with the first and second switching elements, thereby achieving chattering-free oscillation. There is an economical effect in that it is possible to obtain signals and to simplify the structure of the switch.

[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 circuit 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...NPN) Langista, 8...
...PNP) transistor, 9...Resistor 3
0... Common contact, 31... Frequency contact, 32-... Oscillation circuit, 33... Resistor, 60... Control input terminal , 61... Control output terminal, 62... Control output terminal. Hand l Figure 7 End 2 Figure

Claims (1)

[Claims] #11 and #! 20 line terminals, a dial oscillation circuit, first and second resistors, a communication circuit, a switch control circuit, and first and second switching elements, and the first line terminal is connected to the One end of the first resistor, one end of the second switching element, and the positive power supply terminal of the communication circuit are connected, and the negative power source terminal of the communication circuit is connected to the *1
#I is connected to one end of the O switching element, and the other end of the second switching element is connected to the #I through the second resistor.
The second line terminal is connected to the negative power supply terminal of the dial oscillation circuit and the other end of the switching element j11, and the second line terminal is connected to the negative power supply terminal of the dial oscillation circuit and the other end of the switching element j11. A control output terminal of the dial oscillation circuit is connected to an input terminal of a 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 control output terminal of the switch control circuit. A telephone circuit characterized in that the terminals are respectively connected to control input terminals of the second switching element.