JPH0253987B2 - - Google Patents

Description

[Detailed Description of the Invention] [Summary] This invention relates to a power supply circuit for a telephone that supplies DC voltage for driving a bell and DC voltage for telephone calls via a constant current switching circuit, which can supply a predetermined current without depending on the line length. For the purpose of supplying power through regulation, the AC signal is voltage doubled and rectified to generate a direct current voltage for telephone calls and a direct current voltage for driving a bell that is a predetermined times higher than the voltage, and is applied to the first signal appearing at the call control input. A DC voltage generation circuit that outputs a DC voltage for driving a bell in response to a second signal and a DC voltage for communication in response to a second signal, a power supply output, and a power supply output connected between the output of the DC voltage generation circuit and the power supply output. , a constant current circuit that causes the output of the DC voltage generating circuit to output a constant current on/off or a constant current output to the power supply output in response to a signal applied to the switching control input; A switching control signal generating circuit is provided for generating an on/off control signal of the bell signal frequency in response to the signal and generating an on control signal in response to the second signal.

[Industrial application field]

The present invention relates to a power supply circuit for a telephone that supplies a bell drive DC voltage and a telephone call DC voltage via a constant current switching circuit.

[Conventional technology]

Due to the nature of the power supply circuit for conventional wireless telephones,
There is a power supply section for driving the bell and a power supply section for telephone calls, and both of these power supply sections are sometimes provided at a position separated from the power-supplied circuit section of the telephone. The manner in which power is supplied to the telephone is as follows. In other words, the bell drive power supply part boosts the 16Hz signal from the bell signal generation circuit to 150V _P - _P with a transformer and supplies power to the bell drive circuit of the telephone as a bell signal, and also responds to this call. A switching regulator having a voltage boosting function is used in a power supply section that supplies power for a telephone call to a telephone circuit section of the telephone after a telephone call path is formed. An adjustment resistor is used to limit the direct current that varies depending on the length of the line from the power supply circuit to the telephone as described above.

[Problem to be solved by the invention]

Due to the structure of such a conventional power supply circuit, a large transformer must be provided in the power supply section for driving the bell, and in addition, the above-mentioned adjustment resistor must be adjusted, which is complicated.

The present invention was created in view of the drawbacks of the conventional circuits as described above, and its object is to provide a power supply circuit for a telephone that can supply a predetermined current without depending on the line length and without adjustment. purpose.

[Means to solve the problem]

FIG. 1 shows a block diagram of the principle of the present invention. As shown in this figure, the circuit of the present invention rectifies an AC signal by a predetermined voltage doubler to generate a DC voltage for telephone calls and a DC voltage for driving a bell that is a predetermined times higher than the voltage, a DC voltage generating circuit 1 that outputs a DC voltage for driving a bell in response to the first signal and a DC voltage for talking in response to a second signal; It is connected between the output of the DC voltage generation circuit 1 and the power supply output 36, and controls the output of the DC voltage generation circuit 1 to the power supply output 36 at a constant current on/off in response to a signal applied to the switching control input. a constant current circuit 19 that outputs a constant current or a constant current output, and is connected to the call control input 35;
a switching control signal generator for generating an on/off control signal at a bell signal frequency in response to a first signal present at the ring control input 35; and generating an on control signal in response to a second signal present at the ring control input 35; circuit 25
It is composed of:

[Effect]

When the first signal is input to the ring control input 35, the bell driving DC voltage generated in the DC voltage generation circuit 1 is output from there, and the switching control signal generation circuit 25 turns on/off the bell signal frequency. A control signal is supplied to constant current circuit 19. This causes constant current on/off power supply for the bell driving DC voltage from the constant current circuit 19 to the telephone bell driving circuit.

When the second input is input to the call control input 35, the DC voltage for communication is output from the DC voltage generation circuit 1, and the ON control signal is output from the switching control signal generation circuit 25 to the constant current circuit 19. As a result, a constant current supply of the direct current voltage for communication from the constant current circuit 19 to the telephone communication circuit section is generated.

Since both of these power feeds can supply the required power without depending on the power feed length to the telephone, there is no need to use an adjustment resistor corresponding to the power feed length as in the past.

〔Example〕

FIG. 2 shows an embodiment of the invention. In this figure, reference numeral 1 denotes a DC voltage generation circuit that generates a telephone call voltage and a bell drive voltage. This circuit 1 passes through a charging/discharging circuit 3 which is turned on/off by a signal of a desired frequency, for example 16KHz, from an oscillation circuit 2, and supplies a voltage (+V) of a current power supply (not shown), for example 12 volts, to a transformer 5 through a capacitor 4. The voltage supplied to the primary winding and induced in the secondary winding is rectified by the triple voltage rectifier circuit 6 to generate a telephone call voltage and a bell drive voltage, and the signal appearing at the call control input 35 (the ``Means for solving the problem'' and ``effects''
Either one of the two voltages is outputted via a voltage selection circuit 15 that responds to the first or second signal (described in section 1). The charging/discharging circuit 3
A unidirectional current flows through the primary winding of the transformer 5 while charging the capacitor 4 in a charging circuit 7 consisting of a PNP transistor Q1 and an NPN transistor Q2.
While discharging the capacitor 4 in a discharge circuit 8 consisting of a PNP transistor Q4, the transformer 5
The current is configured to flow in the primary winding in a direction opposite to the one direction described above. The triple voltage rectifier circuit 6 has diodes 9, 10, 11 and a capacitor 12 connected in series between the secondary windings of the transformer 5, and an anode of the diode 9 and a diode 10.
The capacitor 13 is connected between the cathode of the diode 11, that is, the anode of the diode 11, and the cathode of the diode 9, that is, the anode of the diode 10, and the anode of the diode 9 are connected. A capacitor 14 is connected between the ground terminal and the ground terminal. The voltage selection circuit 15 consists of a relay 17 and its switching contacts 18.

The call control input 35 is, for example, a detection circuit 16 which detects when a telephone powered by the power supply circuit of the present invention is being called wirelessly and generates an output signal during that call. The output of the detection circuit 16 is connected to a relay 17.

Reference numeral 19 denotes a constant current circuit that is turned on and off by a switching control signal, and its output is connected to a telephone (not shown) via a line 20. This constant current circuit consists of a PNP transistor 24 whose emitter is connected to the above-mentioned switching contact 18 via a resistor 21, and whose base is connected to the switching contact 18 via series-connected diodes 22 and 23 whose cathodes are connected to this. The collector of the transistor 24 is connected to the line 20 mentioned above.

A switching control signal generation circuit that supplies a switching control signal to the constant current circuit 19 is designated by reference number 2.
5. This circuit 25 has a predetermined frequency,
For example, an oscillation circuit 26 that generates a signal at a bell drive frequency of 16 Hz, and a gate circuit 27 whose one input is connected to the output of the oscillation circuit 26 and whose other input is connected to the output of the detection circuit 16 described above. , an inverter 28 connected to the output of the gate circuit 27
and an NPN type transistor 30 whose base is connected to the output of the inverter 28 via a resistor 29 and whose emitter is grounded, and whose base is connected to the output of the gate circuit 27 via a resistor 31 and whose emitter is grounded. The collector of transistor 30 is connected to the base of transistor 24 via a resistor 33, and the collector of transistor 32 is connected to the collector of transistor 24, ie to line 20 via a telephone power supply output 36.
connected to.

Next, the operation of the circuit of the present invention will be explained.

When the circuit of the invention is put into use, the oscillator circuit 2, 26 begins to generate its output.

A charging/discharging circuit 3 receiving a high frequency signal from an oscillation circuit 2 alternately supplies direct current from a direct current power supply (+V) to a primary winding of a transformer 5 via a capacitor 4. That is, during the negative half cycle period of the oscillation signal, the charging circuit 7 and the transformer 5 pass through the capacitor 4.
A current is applied in one direction to energize the transformer 5, and a current in the opposite direction to the above one direction is applied to the transformer 5 through the discharge circuit 8 and the capacitor 4 within the positive half cycle period of the oscillation signal. The transformer 5 is energized. This alternating energization generates an alternating voltage on the secondary side of the transformer 5, and this voltage
A predetermined voltage, for example 150 volts, is applied between the capacitor 12 terminals of the voltage doubler rectifier circuit 6, and the capacitor 1
A predetermined voltage, for example 50 volts, is generated between the terminals of 4.

When a telephone in such a state is called by radio, the detection circuit 16 catches the call and generates a signal at its output, which operates the relay 17 and switches the relay contact 18. As a result, the voltage generated between the terminals of the capacitor 12 is supplied to the constant current circuit 19 via the relay contact 18.

On the other hand, the switching control signal generation circuit 25 receives the signal from the detection circuit 16 and supplies the 16 Hz signal from the oscillation circuit 26 to the bases of the transistors 30 and 32. When transistor 30 is on, transistor 32 is off, and when transistor 30 is off, transistor 32 is off.
2 is in a relationship where it is turned on.

Therefore, the constant current circuit 19
Line 20 with a voltage of 150 volts when 4 is turned on
and ground line 20 when transistor 24 is off. This alternating operation occurs at 16 Hz, and the bell drive voltage of 150 volts at 16 Hz is applied to and drives the telephone. In this power supply, due to the characteristics of the constant current circuit 19, even if the distance to the telephone is long or short, there is no need to adjust the adjustment resistor as in the conventional art, which limits the power supply DC current.

When the user disconnects the handset of the telephone that is called by the bell drive voltage and answers the call, the above-described wireless call is terminated by a conventionally known method, so that there is no output signal from the detection circuit 16. , the relay contact 18 is switched and the 50 volt communication voltage generated between the terminals of the capacitor 14 is supplied to the constant current circuit 19. Further, since the signal from the oscillation circuit 26 is no longer supplied, the transistor 30 is on and the transistor 32 is off. Therefore, the 50 volt voltage supplied to constant current circuit 19 is transmitted through transistor 24, which is turned on, to line 20 to power the telephone. In this case as well, the constant current characteristics of the constant current circuit 19 are utilized for power supply to the telephone, and there is no need to adjust the power supply DC current depending on the length of the distance to the telephone.

As described above, both the bell drive voltage and the telephone call voltage are supplied from one power supply system, so there is no need to provide separate components, and they can be used in common. In addition, the DC voltage is converted to an alternating voltage using a high frequency (16KHz) oscillation circuit, which is then boosted and rectified by a transformer, allowing for a more compact circuit.

Other modifications are also included in the present invention as long as they do not deviate from the technical concept of generating the voltage necessary to drive the telephone and supplying power to the telephone through a constant current circuit that turns this voltage on and off as explained in the above embodiment. .

〔Effect of the invention〕

As is clear from the above description, according to the present invention, a predetermined current can be supplied regardless of the length of the distance to the telephone, so there is no need for adjustment as in the conventional case. There is no need to provide separate generation circuits for each power supply voltage, and components can be shared, making it possible to downsize the circuit.

[Brief explanation of drawings]

FIG. 1 is a block diagram of the principle of the present invention, and FIG. 2 is a diagram showing an embodiment of the present invention. 1 and 2, 1 is a DC voltage generation circuit (oscillation circuit 2, charge/discharge circuit 3, triple voltage rectifier circuit 6, relay 17, switching contact 18), 19 is a constant current circuit (PNP type transistor 24) , resistance 21,
diodes 22, 23) and 25 are switching control signal generation circuits (oscillation circuit 26, gate circuit 2
7, inverter 28, resistors 29, 31, NPN type transistors 30, 32), 35 is a call control input (detection circuit 16), and 36 is a power supply output to the telephone set.

Claims (1)

[Scope of Claims] 1. A DC voltage for communication is generated at a DC voltage output terminal for communication by rectifying an AC signal by a predetermined voltage, and a DC voltage for driving a bell that is a predetermined times higher than the voltage is applied to the DC voltage output terminal for driving a bell. DC voltage generation circuit 1
and a current circuit 1 having a switching control input terminal.
9, a power supply terminal 36 for the telephone connected to the output terminal of the current circuit 19, and one of the voltages generated at the two output terminals of the DC voltage generation circuit 1 in response to the switching signal. a voltage selection circuit 15 that outputs to the input terminal of the current circuit 19; and a voltage selection circuit 15 that switches the current circuit 19 by either an on/off control signal synchronized with the bell signal frequency or an on control signal in response to the switching signal. A switching control signal generation circuit 25 is provided to apply the switching control signal to the control input terminal, and when a call is made to the telephone, in response to the switching signal, the voltage selection circuit 15 converts the voltage generated at the call DC voltage output terminal into the current. In response to the switching signal, the switching control signal generating circuit 25 supplies an on/off control signal to the switching control input terminal of the current circuit 19 to turn the current circuit 19 on and off. When making a call to the telephone, the voltage selection circuit 15 outputs the voltage generated at the call DC voltage output terminal to the input terminal of the current circuit 19 in response to the switching signal. At the same time, the switching control signal generation circuit 25 responsive to the switching signal:
A power supply circuit for a telephone set, characterized in that an ON control signal is supplied to a switching control input terminal of the current circuit 19 to drive the current circuit 19 at a constant current.