JPS58161453A - 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 a PNP 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 1. 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 Figure 1, this type of telephone circuit has adopted a system in which the dial oscillation circuit and the call circuit are switched using mechanical contacts of the push button dial. In other words, in Figure m1, 1 and 2 are the respective 1 and 1820 line terminals, 3 is a dial oscillation circuit, which includes a common contact 30 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 wr3, 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 oscillation circuit 32 is disconnected from the line terminal 1. When the push button is pressed, the common contact 30 is operated, 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 contact corresponding to the pressed button is activated. 31 operates, the oscillation circuit 32 oscillates the corresponding frequency, and the output resistor 33 connects the line terminals 1. It is output to the second gate.

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.Dial signals are interrupted for several meters due to chattering of the mechanical contacts during round switching. This had the disadvantage that the effective signal time was shortened.

Furthermore, since the pushbutton switch included in the dial oscillation circuit 3 has both a common contact 30 and a frequency contact 31, its mechanism is complicated and expensive. The present invention solves these two drawbacks. The present invention also provides a telephone circuit that sends out high-quality dial signals without chattering using a simple push-button switch.

According to the present invention, the present invention includes first and 20th line terminals, a dial oscillation circuit, first and second resistors, a communication circuit, a switch control circuit, and first and second switching elements, The first line terminal is connected to one of the first resistors.
one end of the first switching element and one end of the second switching element, and the other end of the second switching element is connected to the first resistor via the second resistor. The other end of the first switching element is connected to the positive power supply terminal of the dial oscillation circuit, the other end of the first switching element is connected to the positive power supply terminal of the communication circuit, and the second line terminal is connected to the negative power supply terminal of the dial oscillation circuit. terminal and the negative power terminal of the talking circuit,
A control output terminal of the dial oscillation circuit 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 a control output terminal of the dial oscillation circuit. A telephone circuit is obtained, characterized in that the output terminals of the 20th switching element are respectively connected to the control input terminals of the 20th switching element.

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.
are the 1st and 20th line terminals, 3 is the dial oscillation circuit, 4
is the first bias resistor to the dial oscillation circuit 3,
5Fi call circuit failure, 6 is a switch control circuit, and dial oscillation circuit 3 operates in response to each push button (
(make) frequency contact 31, an oscillation circuit 32, and an output resistor 33.

Then, the first terminal 1 is connected to the terminal 1 of the first resistor 4.
PNP as an end and the first switching element;) Emitter of the transistor and the PNP as the switching element;) Connect the PNP to the emitter of the transistor 8; The dial oscillation circuit is connected to the other end of the first resistor 4 via a resistor 9, 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 second output terminal 62 of the switch control circuit 6 is connected to the base of the PNP transistor 8.
0 base respectively.

When the pushbutton is not pressed, the frequency contact 31 is inactive, and this is detected by the oscillation circuit 32,
The 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 signal is output as a signal to turn on the switch control circuit 60, and the second switch of the switch control circuit 6 A signal for turning off the PNP transistor 8 is output from the output terminal 62. Therefore PNP)
Connected to runners 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 via the resistor 33, and a press signal is output from the control output terminal 34, which is transmitted to the control input terminal 6o of the switch control circuit 6 to control the switch. A signal to turn off the PNP transistor 7 is output from the first output terminal 61 of the circuit 6, and the communication circuit 5 is disconnected from the line terminal 1.
) A signal is output which turns on transistor 8 and connects resistor 9 in parallel to resistor 4.

Connecting this resistor 9 in parallel with the resistor 4 reduces the bias resistance value that supplies the current necessary for its operation, since the circuit current of the oscillation circuit 320 increases significantly during oscillation compared to when it does not oscillate. The oscillation circuit 32 has a minimum circuit current (usually 100 μ
When the operation of the frequency contact 31 is detected, it oscillates to send an oscillation signal to the line terminal 1.2, but the oscillation signal is ignored. Sending out with distortion requires a current many orders of magnitude higher than the current required during non-oscillation (usually several mA or more), so the bias resistor should be a large resistor during non-oscillation to reduce the load on the communication circuit 5. However, during oscillation, it is necessary to reduce the bias resistance value so that a distortion-free oscillation output is sent between the line terminals 1 and 2. Usually, the resistor 4 is selected to be IOKΩ or more, and the resistor 9 is selected to be several hundred Ω or less.

As explained above, by replacing the mechanical common contact of a push button switch with the first and second switching elements, the present invention can obtain an oscillation signal without chattering, and has a simple #II structure of the switch. There is an economic effect that makes it possible to

[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
...Mountain dial oscillation circuit, 4...Resistor, 5
...Telephone circuit, 6...Switch control circuit, 7...PNP) transistor, 8...
...PNP) transistor, 9...Resistor 30
......Common contact, 31...Frequency contact,
32...Oscillation circuit, 33...Resistor,
60... Control input terminal, 61... Control output terminal, 62... Control output terminal. Sheep! Gloss, # 2 times

Claims (1)

[Claims] *1 and M2 line terminals, a dial oscillation circuit, fourth and second resistors, a communication circuit, a switch control circuit, and first and second switching elements; A line terminal is connected to one end of the first resistor, one end of the first switching element, and one end of the second switching element, and the other end of the second switching element O is connected to the other end of the second switching element O. Connecting the other end of the first resistor to the positive power terminal of the dial oscillation circuit via a resistor, and connecting the other end of the first switching element to the positive power terminal of the communication circuit;
Said number? A line terminal of the dial oscillation circuit is connected to a negative power supply terminal of the dial oscillation circuit and a negative power supply terminal of the communication circuit, a control output terminal of the dial oscillation circuit is connected to an input terminal of the switch control circuit, and a first line terminal of the switch control circuit A telephone circuit characterized in that an 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 a control input terminal of the second switching element.