JPS58161450A - Telephone set circuit - Google Patents

Abstract

PURPOSE:To obtain an oscillation signal without chattering, by replacing mechanical common contacts of a push button switch by the 1st, the 2nd and the 3rd switching elements, in a push button dial telephone set of the two-frequency synthesis signal system. CONSTITUTION:When a push button is depressed, a frequency contact 31 is activated, the information is detected at an oscillation circuit 32, the oscillation signal is outputted via a resistor 33, a depression signal is outputted from a control output terminal 34, fed to a control input terminal 60 of a switch control circuit 6, and a signal turning off an NPN transistor (TR)8 is outputted from the 2nd output terminal 62 of the circuit 6, and a channel circuit 5 is disconnected from a line terminal 2. Simultaneously, a signal turning on a PNP TR7 is outputted from the 1st output terminal 61 of the circuit 6, both end terminals of the circuit 5 are short-circuited and the oscillation signal from a resistor 33 is fed to the line terminal 1. A signal turning on an NPN TR9 is outputted from the 3rd output terminal 63 of the circuit 6 and a resistor 10 is connected 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, in FIG. 1, 1 and 2 are the first and second line terminals, respectively;
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 (
It includes a frequency contact 31 for making (make), an oscillation circuit 32, and 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 communication circuit 5 is connected to the line terminals 1 and 2 by the common contact 30, and the oscillator circuit 32 is disconnected from the line terminal 1.

When the push button is pressed, the common contact 30 operates, and the communication circuit 5
is disconnected from the line terminal 1, the n1 oscillation circuit 32 is connected to the line terminals 1 and 2, and the frequency contact 31 corresponding to the pressed button operates to oscillate the frequency corresponding to the oscillation circuit 32U, and the output resistance Line terminal 1.2 via the device 33
It is output in between.

In the telephone circuit configured in this way, the mechanical contact 30 is used to switch between the dial illumination circuit 3 and the call circuit 5, so when switching, the dial signal may be distorted due to chattering of the mechanical contact. There was a drawback that the n1 effective signal time was shortened by intermittent several m5ec.

Furthermore, the pushbutton switch included in the dial oscillation circuit 3 has both a common contact 30 and a same wave number contact 31, so 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, and the first, second, and third switching elements are connected. The first line terminal is connected to the positive power terminal of the dial oscillation circuit, one end of the first switching element, and the positive power terminal of the communication circuit, and the other end of the first switching element is connected to the positive power terminal of the dial oscillation circuit. The negative power terminal of the communication circuit is connected to one end of the second switching element, and the second line terminal is connected to one end of the first resistor, the other end of the second switching element, and the other end of the second switching element. The other end of the second switching element is connected to one end of the third switching element, and the other end of the second switching element is connected to the negative power terminal of the dial oscillation circuit and the other end of the first resistor through the second 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 a control input terminal of the first switching element. A second output terminal 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 third switching element.
A telephone circuit is obtained which is characterized in that it has two connections.

Next, one embodiment of the present invention will be described with reference to the drawings. FIG. 2 is a block circuit diagram of one embodiment of the present invention.
．． 2 are first and second line terminals, 3 is a dial oscillation circuit, 4 is a resistor for the first bias to the dial oscillation circuit 3, 5 is a communication circuit, 6 is a switch control circuit, and 3 is a dial oscillation circuit. The 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 emitter of the Runsistor 8 is connected to the collector of the 8, and the second line terminal 2 is connected to one end of the first resistor 4 and the NPN.) The emitter of the Runsistor 8 is connected to the NPN as the third switching element.) The emitter of the Runsistor 8 is connected to the collector of the 8. The collector of the NPN) run transistor 9 is connected to the negative power terminal of the dial oscillation circuit 3 and the other end of the first resistor 4 via a second resistor 10, and the collector of the NPN The control output terminal 34 of the circuit 3 is connected to the input terminal 60 of the bang switch control circuit 60, and the first output terminal 61 of the switch control circuit 6 is connected to the input terminal 60 of the switch control circuit 6.
The second output terminal 62 of the circuit is connected to the base of the NPN transistor 8, and the output terminal 6 of the switch control circuit is connected to the base of the NPN transistor 8.
3 is connected to the pace of the NPN) run sister 9.

When the push button is not pressed, the frequency contact 31 is not operating, and this is detected by the oscillation circuit 32.
An oscillation output is not sent to the resistor 33, and a signal indicating that the button is not pressed is output to the control output terminal 34. This output is transmitted to the control input terminal 60 of the switch control circuit 6, and the first A signal is output from the output terminal 61 to turn off the Ranjistaf (PNP), and the miswitch control circuit 6
A signal that turns on the NPN transistor 8 is output from the second output terminal 62 of the switch control circuit 6, and a signal that turns off the NPN transistor 9 is output from the third output terminal 63 of the switch control circuit 6. Therefore, when the NPN transistor 8 is turned on, the communication circuit 5 is connected to the line terminals 1 and 2. At this time, the oscillation/circuit 320 operates so that no oscillation output is produced. Also, the bias to the oscillation circuit 32 is provided by the resistor 4.
It is biased only by f.

When the push button is pressed '':5f', the frequency contact 31 operates [7, that information is detected by the oscillation circuit 32, and an oscillation signal is output via the resistor 33, and at the same time, from the control output terminal 34. Outputs a push signal and switches control circuit 60
A signal is transmitted to the control input terminal 60, and a signal for turning off the NPN transistor 8 is output from the second output terminal 62 of the switch control circuit 6, thereby disconnecting the communication circuit 5 from the line terminal 2. At the same time, the first output terminal 61 of the switch control circuit 6 outputs a signal to turn on the PNP) gingistough, short-circuiting both ends of the communication circuit 5 and connecting the oscillation signal from the resistor 33 to the line terminal IK. Furthermore, a signal for turning on the NPN transistor 9 is output from the third output terminal 63 of the switch control circuit 6, and the resistor 10 is connected in parallel to the resistor 4.

Connecting this resistor 10 in parallel with the resistor 4 is important because the circuit current of the oscillation circuit 320 increases significantly during oscillation compared to when there is no oscillation, so the bias resistance value that supplies the current necessary for its operation is adjusted. This is because it needs to be made smaller. In other words, the oscillation circuit 32 uses the minimum necessary circuit current (usually 10
It operates to detect the operation of the frequency contact 31 when the frequency contact 31 is detected (lower than 0 voice A), but when the operation of the frequency contact 31 is detected,
The oscillation signal is sent between line terminals 1 and 2.
Since the KFi transmits the oscillation signal without distortion, it requires a circuit current that is several orders of magnitude higher than the current required when there is no oscillation (usually several mA or more), so when there is no oscillation, a resistor with a large bias resistance is used, and the communication circuit 5 It is necessary to reduce the load on the line and to reduce the bias resistance value so that an undistorted oscillation output is sent between the line terminals 1 and 2 during oscillation. Usually, the resistor 4 is selected to have a resistance of 10 ohms or more, and the resistor 9 is selected to have a resistance of several 100 ohms.

As explained above, the present invention provides a mechanical common contact point of a pushbutton switch as a first contact point. By switching the second and third switching element traps, an oscillation signal without chattering can be obtained, and the structure of the switch can be simplified, which is an economical effect.

[Brief explanation of the drawing]

FIG. 1 is a block circuit diagram showing a conventional circuit, and FIG. 2 is a block circuit diagram showing an embodiment of the present invention. l...Line terminal, 2...Line terminal, 3-
...-Dial oscillation circuit, 4...-Resistor, 5--
-----Telephone circuit, 6...Switch control circuit,
7...-PNP) transistor, 8...NPN
) Ransistor, 9...-NPN) Ransistor, lO... Resistor, 30... Common contact, 31...-1ira number 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 first, second, and third switching elements, and the first line terminal is connected to the positive power supply terminal of the dial oscillation circuit and the first line terminal. one end of the switching element is connected to the positive power supply terminal of the communication circuit, the other end of the first switching element is connected to the negative power supply terminal of the communication circuit and the l terminal of the second switching element, A second line terminal is connected to one end of the first resistor, the other end of the second switching element, and one end of the third switching element, and the other end of the third switching element is connected to the other end of the third switching element. The negative power supply terminal of the dial oscillation circuit and the other end of the first resistor are connected through a resistor No. 2, and the control output terminal of the dial oscillation circuit is connected to the input terminal of the control circuit No. 3. a first output terminal of the switch control circuit is connected to a control input terminal of the first switching element Ktm; a second output terminal of the switch control circuit is connected to a control input terminal of the second switching element; A telephone product circuit characterized in that a third output terminal of the control circuit is connected to a control input terminal of the third switching element.