JPS58161451A - 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. 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 TR7 is outputted from the 1st output terminal 61 of the circuit 6 to disconnect a channel circuit 5 from a line terminal 1. Simultaneously, a signal turning on a NPN TR8 is outputted from the 2nd output terminal 62 of the circuit 6, both end terminals of the circuit 5 is short-circuited, and an oscillation signal is fed to a line terminal 2. A signal turning on a PNP 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 respectively the first and second line terminals,
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 oscillation circuit 3
2 is separated from the line terminal 1. When the push button is pressed, the common contact 30 operates and the communication circuit 5 connects to 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, causing the oscillation circuit 32 to oscillate at the corresponding frequency, causing the output resistor 33 to oscillate. It is output between line terminals 1 and 2 through the line.

In the telephone circuit configured in this way, the mechanical contact 30 is used to switch between the dial oscillation circuit 3 and the telephone call circuit 5, so the dial signal is interrupted for several meters due to the chattering phenomenon of the mechanical contact at the time of switching. There was a drawback that the n1 effective signal time was shortened.

Furthermore, since the push button switch included in the dial oscillation circuit 3 includes both the common contact 3o 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, and the first, second, and third switching elements. , the first line terminal is connected to one end of the first resistor, one end of the first switching element, and the third
The other end of the first switching element is connected to the positive power terminal of the communication circuit and one end of the second switching element, and the second line terminal is connected to the dial. The negative power terminal of the oscillation circuit is connected to the negative power terminal of the communication circuit and the other end of the second switching element, and the other end of the third switching element is connected to the second switching element.
The positive power supply terminal of the dial oscillation circuit is connected to the other end of the first resistor through a resistor, the control output terminal of the dial oscillation circuit is connected to the input terminal of the switch control circuit, and the switch The first output terminal of the control circuit is connected to the control input terminal of the first switching element, the second output terminal of the switch control circuit is connected to the control input terminal of the second switching element, and the second output terminal of the switch control circuit is connected to the control input terminal of the second switching element. Third
A telephone circuit is obtained, characterized in that the output terminals of the telephone circuit are connected to the control input terminals of the third switching element.

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.1.
2 is a fil and a second line terminal, -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 furthermore, a dial oscillation circuit. The three circuits include a frequency contact 31, an oscillation circuit 32, and an output resistor 33 that operate (make) in response to each push button.

Then, the first line terminal 1 is connected to the first line terminal 1 of the first resistor 4.
PNP as the end and the first switching element) PNP as the emitter of the run cistor 9 and the third switching element) Connected to the emitter of the run sistor 9 and the
The collector of the NP) Runsystorf is connected to the positive power terminal of the talking circuit 5 and the collector of the NPN) Runsystor 8 as a second switching element, and the second line terminal 2 is connected to the negative power terminal of the dial raising circuit 3. l Connect the negative power terminal of the communication circuit 5 to the emitter of the NPN 9 transistor 8, and connect the collector of the NPN transistor 9 to the positive power terminal of the dial oscillation circuit 3 through the second resistor io. The control output terminal 34 of the dial oscillation circuit 30 is connected to the input terminal 6o of the switch control circuit 6, and the first output terminal 61 of the switch control circuit 6 is connected to the other end of the first resistor 4. PNP) at the base of the near-4 distaff, the second output terminal 6 of the switch control circuit 6
2 is connected to the base of the NPN) run raster 80, and the third output terminal 63 of the switch control circuit 6 is connected to the base of the PNP) run raster 9.

When the push button is not pressed, the frequency contact 31 is not operating, 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 [7, this output is transmitted to the control input terminal 60 of the switch control circuit 60]. A signal is output from the output external terminal 61 to turn on the Ranjistaf (PNP), and the switch control circuit 6
A signal for turning off the NPN transistor 8 is output from the second output terminal 62 of the switch control circuit 6, and a signal for turning off the PNP transistor 9 is output from the third output terminal 63 of the switch control circuit 6. Therefore, by turning on the PNP transistor, the communication circuit 5 is connected to the line terminals 1 and 2. At this time, the oscillation circuit 32 operates so that no oscillation output is produced. Further, the oscillation circuit 32 is biased only by the resistor 4.

When the push button is pressed, the frequency contact 31 is activated.
8.The information is detected by the oscillation circuit 32, and an oscillation signal is outputted through the n1 resistor 33 and the 1 control output terminal 34.
A push signal is output from the switch control circuit 6 and transmitted to the control input terminal 60 of the switch control circuit 6. A signal to turn off the PNP transistor 7 is output from the first output terminal 61 of the n1 switch control circuit 6, and the communication circuit 5 is connected to the line terminal. Separate from 1. At the same time, from the second output terminal 62 of the switch control circuit 6 to the NPN
) A signal is output to turn on the transistor 8, both ends of the communication circuit 5 are shortened, and the oscillation signal from the resistor 33 is connected to the line terminal 2. Furthermore, a signal for turning on the PNP 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 means that the circuit current of the oscillation circuit 320 is F during oscillation compared to when it is not oscillating.
i) This is because the bias resistance value that supplies the current necessary for the operation must be reduced because the current increases significantly.

The knob oscillation circuit 32 has a minimum circuit current (usually 1
It operates to detect the operation of the frequency contact 31 at a frequency of less than 00 μA), but when the operation of the frequency contact 31 is detected, it oscillates to send an oscillation signal between the line terminals 1 and 2. In order to send an oscillation signal without distortion, the circuit current (usually several mA or more) is several orders of magnitude higher than the current required during non-oscillation.
Therefore, when there is no oscillation, a large resistor is used as the bias resistor to reduce the load on the communication circuit 5. When oscillating, the bias resistor is set so that the undistorted oscillation output is sent between the line terminals 1 and 2. It is necessary to reduce the value. Normal resistor 4
is more than IOKΩ, resistor 9il! Several hundred Ω (//: selected.

As described above, the present invention can obtain an oscillation signal without chattering by replacing the mechanical common contact of the push button switch with the first, second, and third switching elements, and Economical effect of simplifying the structure of the switch.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a block circuit diagram showing an example of a conventional circuit, and FIG. 12 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) Langista, 8...
...NPN) transistor, 9...NPN) transistor, 10...resistor, 30...
Common contact, 31...Granoid number contact, 32...
...Oscillation circuit, 33...Resistor, 34...
...Control output terminal, 60...Control input terminal, 6
1... 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 an eleventh second and third switching element,
The first line terminal is connected to one end of the first resistor, one end of the first switching element, and the l end of the third switching element, and the other end of the first switching element is connected to The positive power terminal of the communication circuit is connected to one end of the second switching element, and the second line terminal is connected to the negative power terminal of the dial oscillation circuit, the negative power terminal of the communication circuit and the second switching element. the other end of the third switching element is connected to the positive power supply terminal of the dial oscillation circuit and the other end of the first resistor via the second resistor; The control output terminal of the dial oscillation circuit is the input 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 input terminal of the second switching element. a third switch of the switch control circuit;