KR940002727Y1 - Power supply circuit in telephone - Google Patents

Abstract

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Description

Telephone power supply circuit

1 is a conventional circuit diagram.

2 is a circuit diagram of the present article.

* Explanation of symbols for main parts of the drawings

21: bridge diode 22: hook switch

23: first power supply unit 24: line control unit

25: second power supply unit 26: zener diode

27: micom 28: call circuit

29: ringer circuit

The present invention relates to a power supply circuit of the telephone, and more particularly to a circuit capable of supplying power to the telephone when on-hook.

In general, a microcomputer is attached to a phone to store a phone number or perform additional functions other than a call. If the microcomputer is attached to the telephone as described above, the operating power of the microcomputer must always be supplied from the telephone.

FIG. 1 is a circuit diagram of a conventional telephone with a microcomputer. In the case of off-hook, operation power is supplied by using call power, and in on-hook, operation power is supplied by using a battery. have.

First, the operation process in the "on" state (off-hook) of the hook switch 12 will be described. The bridge diode 11 rectifies the call power supplied from the exchange. At this time, when the hook switch 12 is "on", the state is off-hook, and the transistor Q1 of the line control unit 13 is "on", and the transistor Q1 is turned on by turning on the transistor Q2. Is turned on. Therefore, when the transistor Q1 is turned on, the output of the bridge diode 11 is applied to the microcomputer 17 and the communication circuit 18. Then, a call loop is formed between the exchange and the call circuit 18, and the call loop is in a state capable of performing a voice call function. At this time, the output of the bridge diode 11 through the transistor Q1 is a state in which a DC signal is carried in a negative AC signal, and this signal is rectified through the coil 1 and the diode D1 and then the zener diode 16. Is converted into a constant voltage and supplied to the operating power of the microcomputer 17. At this time, the battery 15 enters the charging mode.

Secondly, the operation of the hook switch 12 in the " off " state (on-hook) will be described. When the hook switch 12 is turned off, the on-hook state is entered and the transistor Q2 is turned off. Accordingly, since the transistor Q1 is also turned off, the call loop is disconnected so that the path of the operating power supplied through the coil L1 and the diode D1 is disconnected. Then, the charging power of the battery 15 is discharged, and this power is supplied to the operating power of the microcomputer 17.

Therefore, in the conventional telephone having the above configuration, in the off-hook state, the hook switch 12 is turned on to operate the call power (4V-10V) generated through the bridge diode 11 of the microcomputer 7. Since the hook switch 12 is turned off when the on-hook is disconnected and the communication line is disconnected, the power supply 3V of the battery 15 is used as the operation power supply of the microcomputer 17. However, in the conventional telephone power supply circuit as described above, since the battery 15 is used to store the on-hook telephone number or perform an additional function, there is an inconvenience in assembling the cost.

Therefore, the purpose of this paper is to provide a circuit that can supply the operating power of the microcomputer using the telephone call power even in the on-hook state in the telephone.

Hereinafter, the present invention will be described in detail with reference to the accompanying drawings.

2 is a circuit diagram of the present invention, which includes a microcomputer 27 connected in parallel to a second line L2, a communication circuit 28 connected in parallel to the second line L2 to process a call voice signal, and telephone lines T and R. A bridge diode 21 connected between the first line L1 and applying the call power of the telephone line to the first line L1 and simultaneously applying the signal of the first line L1 to the telephone lines T and R; and the first line. A hook switch 22 connected in parallel to L1 to generate an on / off-hook signal, and connected between the first line L1 and the second line L2, and receiving an output of the hook switch 22 as a control signal. Preferred control unit 24 which connects the first line L1 and the second line L2 when off-hook occurs and forms a call loop, and disconnects the first line L1 and the second line L2 when on-hook signal is generated, and the resistor R1, R2), the first line when connected on-hook between the first line L1 and the node N1 And a first power supply unit 23 for applying the call power of the L1 to the node N1, the coil L1, and the diode D1, and are connected between the second line L2 and the node N1 to be off-hook. A second power supply unit 25 for supplying the call power of the second line L2 to the node N1 and the node N1 and the ground terminal. The power supply of the node N1 is set to the operating power level of the microcomputer 27 at a constant voltage. Zener diode 26 is applied to the telephone line and the ringer circuit 29 is connected to the telephone lines T, E to generate a ring signal when receiving a ring signal.

Therefore, in the above configuration, the first power supply unit 23 and the zener diode 26 serve as the operating power generating means during on-hook, and the second power supply unit 25 and the zener diode 26 generate the operating power during off-hook. It is a means.

This draft will be described in detail in the above-described configuration.

First, let's talk about the off-hook behavior. When the hook switch 22 is turned on, the hook switch 22 is turned off, and the transistor Q2 is turned on by the call power supplied to the first line L1 through the bridge diode 21. When the transistor Q2 is turned on, the state of the collector stage becomes a "low" level, so the transistor Q1 is also turned on. Then, the first line L1 and the second line L2 are connected to each other to form a currency loop. When the call loop is formed as described above, the bridge diode 21 polarizes and rectifies the call power (OV, -48V) supplied to the telephone line to the first line L1, and generates the voice generated by the first line L1. Apply the signal to the telephone preferences T, R. The voice signal at this time becomes an AC signal carried on a constant DC voltage. In addition, the preference controller 24 applies the voice signal carried on the call power of the first line L1 to the second line L2 and simultaneously applies the voice signal generated to the call circuit 28 to the first line L1. At this time, the voice signal generated by the communication circuit 28 has a negative signal level.

When the above call loop is formed, the call power is supplied to the second line L2, and the call power is rectified by the coil L1 and the diode D1 and applied to the node N1. The control diode 26 then supplies the power applied to the node N1 to the operating power (4V-10V) of the microcomputer 27. Therefore, in the off-hook state, the microcomputer 27 may be powered by the call power and perform phone number memory and other additional functions. At this time, the operating power of the microcomputer 27 must satisfy the retention current of the internal memory RAM. The retention current of the memory RAM is about 16 μA.

Second, we look at the behavior in the on-hook state. In this case, since the hook switch 22 is in an off state, the hook switch 22 is in an on-hook state and thus the call power of the first line L1 is not applied to the transistor Q2. Therefore, the transistor Q1 is also turned off so that the first line L1 and the second line L2 are disconnected. Therefore, the second power supply unit 25 connected to the second line L2 cannot supply the call power to the node N1. At this time, the first power supply unit 23 connected in parallel to the first line L1 applies the call power supplied to the first line L1 to the node N1. Then, the power applied to the node N1 is converted to a constant voltage by the zener diode 26 and applied to the power terminal of the microcomputer 27.

The first power supply unit 23 is composed of resistors R1 and R2 connected in parallel to the first line L1, wherein resistance values of the resistors R1 and R2 are retained in the internal memory of the microcomputer 27. The current value must be satisfied. At this time, the insulation resistance at the time of on-hook is prescribed | regulated to 1 MΩ or more in the specification of the said telephone. Therefore, the resistors R1 and R2 should be set to 1 MΩ or more.

If the resistors R1 and R2 are set to 4.7 MΩ, the current applied to the node N1 is Since it becomes about 20.4μA, the retention current value of the memory can be satisfied. Therefore, the first power supply unit 24 satisfies the on-hook insulation resistance value of the telephone standard, and can supply the operating power having a current value equal to or higher than the retention current value of the memory to the microcomputer 27.

Therefore, even when on-hook, the microcomputer 27 can be supplied with the operating power by the call power supplied from the exchanger, and thus it is not necessary to provide a separate battery.

When the 20HZ ring signal generated at the AC60-80V level is applied on the telephone line TR in the on-hook state, the ringer circuit 29 separates the DC signal from the received ring signal and extracts only the AC signal to generate a ring tone. . At this time, since the bridge diode 21 cuts off the ring signal of the AC type, the supply of the ring signal is cut off to the first line L1.

As described above, even when the phone is in the on-hook state, the microcomputer uses the call power to supply the operating power so that additional functions such as a phone number can be performed, thereby reducing the cost and simplifying the assembly process. .

Claims (8)

A telephone circuit comprising: a microcomputer connected in parallel to a second line, having a memory therein, which performs an additional function of a telephone by an operating power received by a power supply node, and is connected between a telephone line and a first line, A bridge diode which applies a call voice signal of the telephone line to the first line and a call voice signal of a first line to the telephone line, and is connected in parallel with the first line and generates an on / off-hook signal A hook switch to be connected between the first line and the second line, and inputs the output of the hook switch as a control signal to connect the first line and the second line when an off-hook signal is generated, and an on-hook signal A line control unit which disconnects the first line and the second line when it occurs, and is connected between the first line and the power supply node, and when on-hook, the call power of the first line is connected to the power supply node. A second power supply unit connected between the first power supply unit, the second line and the power supply node to rectify the call power of the second line and apply the power supply node to the power supply node when off-hook; And a constant voltage unit connected between the ground terminal and the ground terminal, and configured to normalize the power of the power supply node to the operating power level of the microcomputer. The power supply circuit according to claim 1, wherein a resistance value is set so that the first power supply unit satisfies the retention current for the memory inside the microcomputer as an insulation resistance of the telephone when on-hook. 3. A power supply circuit for a telephone according to claim 2, wherein first and second insulating resistors having the same insulating resistance in said first line are connected in parallel. 4. The power supply circuit of claim 3, wherein the first and second insulation resistances are 4.7 MΩ. A power supply circuit for a telephone according to claim 1, wherein the constant voltage portion is a zener diode. A telephone circuit comprising: a microcomputer connected in parallel to a second line, having a memory therein, which performs an additional function of a telephone by an operating power received by a power supply node, and is connected between a telephone line and a first line, A bridge diode which applies a call voice signal of the telephone line to the first line and a call voice signal of a first line to the telephone line, and is connected in parallel with the first line and generates an on / off-hook signal A hook switch to be connected between the first line and the second line, and inputs the output of the hook switch as a control signal to connect the first line and the second line when an off-hook signal is generated, and an on-hook signal A line control unit for disconnecting the first line and the second line at the time of occurrence, and connected in parallel with the first line, and converts the call power of the first line into a DC voltage of a predetermined level when on-hook. On-hook power supply means for supplying to the operating power of the com, and connected in parallel to the first line, when the off-hook, the power supply of the microcomputer by converting the call power of the second line to a certain level of DC voltage A power supply circuit for a telephone, comprising: an off-hook power supply means for supplying. 7. The apparatus of claim 6, wherein an on-hook power supply means is connected in parallel to the first line, and is set to satisfy an insulation standard at the time of on-hook and to satisfy a retention current value for the memory of the microcomputer. And a control diode connected between the insulation resistance and the ground terminal to normalize the call power for outputting the insulation resistance to the operating power level of the microcomputer. Power supply circuit. 8. The apparatus of claim 7, wherein an off-hook power supply means is connected in parallel to the second line, and is connected between the rectifying unit and a ground terminal to rectify the communication power of the second line when off-hook. And a zener diode to normalize the output power of the microcomputer to an operating power level.