KR950004455Y1 - In-use display circuit - Google Patents

Abstract

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Description

Telephone use state detection circuit

1 is a conventional telephone use state detection circuit diagram.

2 is a circuit diagram illustrating a state of use of a telephone according to the present invention.

* Explanation of symbols for main parts of the drawings

10: general telephone 20: relay

30: phone use state determination unit 40: central processing unit

50: audio processing unit

The present invention relates to a circuit for detecting a state of use of a telephone in a wireless telephone by connecting a general telephone in parallel on a line. A usage state detection circuit for detecting a state of use of a telephone will be described.

In general, when a regular telephone is in a call and the telephone is hooked off, the reception sensitivity of the telephone is remarkably decreased.

Therefore, the wireless telephone detects the state of use of the general telephone in order not to infringe on the telephone in the call.

In the conventional circuit for detecting the state of use of a telephone in a wireless telephone using parallel telephones connected in parallel, as shown in FIG. 1, the central processing unit 5 selects the telephone in the normal state. When the common terminal (c) and the terminal (a) are connected to each other by controlling the relay (2), the central processing unit (5) controls the relay (2) when the wireless telephone (7) is hooked off. (7) to the audio processing section (6). However, when the cordless telephone 7 is hooked off while the general telephone 1 is in use, the central processing unit 5 detects that the general telephone 1 is in use and the relay 2 is continuously connected to the common terminal c. Control to connect the terminal (a).

When the general telephone 1 or the wireless telephone 7 is hooked on, the output of the bridge rectifier circuit 3 becomes 48V. At this time, the 48V output from the bridge rectifier circuit 3 is divided by the resistors R1-R2 and applied to the base of the transistor TR1.

As a result, when the transistor TR1 is turned on and the transistor TR1 is turned on, the base of the transistor TR2 is turned low, and the transistor TR2 is turned off. When the transistor TR2 is turned off, a high signal is applied from the central processing unit 5 so that the central processing unit 5 detects that the general telephone 1 or the wireless telephone 7 is not in use. However, when the general telephone 1 or the wireless telephone 7 is hooked off, the polarity is reversed so that the output of the bridge rectifier circuit 3 becomes low.

Since the low state signal output from the bridge rectifier circuit 3 is divided by the resistors R1-R2 and applied to the base of the transistor TR1, the transistor TR1 is turned off. When the transistor TR1 is turned off, the transistor TR2 is turned to a high state at the base of the transistor TR2, and the transistor TR2 is turned on. When the transistor TR2 is turned on, a low signal is applied to the central processing unit 5 so that the central processing unit 5 detects that the general telephone 1 or the wireless telephone 7 is in use.

The audio processor 6, which is not described herein, processes the transmission / reception voice signal when forming a call of the radiotelephone 7.

In the conventional circuit as shown in FIG. 1, the power supply used in the radiotelephone and the power supply of the exchanger are not completely separated, so that noise is introduced through the line of the exchanger. (TR1, TR2) and the like may be damaged, and there is a problem that it is difficult to apply to the standards of some countries such as Europe using a minute current.

Accordingly, an object of the present invention is to provide a use state detection circuit that detects a use state of a telephone without being affected by a telephone line by separating a power supply used in a wireless telephone and a power supplied from an exchange.

The present invention for achieving the above object is a telephone use state determination means for outputting the use state determination signal of the telephone by reducing the level by synchronizing the power supplied to the telephone line with a predetermined reference pulse signal, and the telephone use state And a control means for receiving the discrimination signal outputted from the discriminating means, detecting whether the telephone is in use, generating a predetermined reference pulse signal, and outputting the predetermined reference pulse signal to the used status determining means of the telephone.

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

1 is a circuit diagram according to the present invention, and includes a general telephone 10 connected in parallel with a wireless telephone, and a relay 20 for selective switching to form a priority call when the wireless telephone or the telephone 10 is hooked off. A transformer T1 connected to one terminal L2 of the telephone line to induce a predetermined reference pulse signal (20 KHz) to the secondary side when a current loop is formed in the telephone line; and a secondary side of the transformer T1. A predetermined reference pulse signal is induced to induce a primary side signal synthesized with the power supplied from the telephone line to the secondary side to reduce the level, and a transformer having a reduced level in the transformer T2. A phone use state determination unit 30 which receives a received state determination signal and inputs a phone use state determination signal from the use state determination unit 30 to detect a use state of the phone and It is connected to two terminals L1 and L2 of the telephone line and the central processing unit 40 which controls the overall operation and generates a predetermined reference pulse signal (20 KHz) and applies it as the primary coil of the transformer T1. The audio processing unit 50 is configured to process transmission and reception voice signals during a telephone call.

The use state determination unit 30, the central processing unit 40, and the audio processing unit 50 in the above configuration are incorporated in the radio telephone.

Based on the above-described configuration, an embodiment of the present invention will be described in detail with reference to FIG.

Power supply 48V supplied from the subscriber line of the exchange is applied to the two terminals L1 and L2 of the telephone line through the trunk line. At this time, when the general telephone 10 and the wireless telephone connected in parallel to the two terminals L1 and L2 of the telephone line are hooked on, the two terminals L1 and L2 of the telephone line are open-loaded, and the current is in the telephone line. Will not flow. At this time, the central processing unit 40 generates a predetermined reference pulse signal (20 KHz), and the predetermined reference pulse signal (20 KHz) generated from the central processing unit 40 is the primary coil (T1) of the transformer (T1). N1) and resistor R16 flow to ground. However, since no current flows through the secondary coil N2 of the transformer T1, the predetermined reference pulse signal 20KHz applied to the primary side of the transformer T1 is not induced to the secondary coil N2. . When there is no voltage induced by the secondary coil of the transformer T1, since there is no current flowing to the primary coil N3 of the transformer T2, the voltage induced by the secondary coil N4 of the transformer T2 is There will be no. This causes the transistor Q1 to be turned off. When the transistor Q1 is turned off, a high voltage is applied to the base of the transistor Q2 so that the transistor Q2 is turned on. When the transistor Q2 is turned on, a low signal is applied to the central processing unit 40 so that the central processing unit 40 detects that the general telephone 10 or the wireless telephone is not in use. In this case, the transformer T1 may prevent the noise introduced into the telephone line from being applied to the wireless telephone 60.

However, when the general telephone 10 or the wireless telephone is hooked off, current flows in the telephone line. As a result, the transformer T1 induces the predetermined reference pulse signal 20 KHz generated from the central processing unit 40 applied to the primary coil N1 to the secondary coil N2. The primary coil N3 is applied with a signal similar to that in FIG. Therefore, the transformer T2 induces the signal applied to the primary side coil N3 to the secondary side coil N4 and outputs it through the line a. The signal induced to the secondary side coil N4 is reduced in level. do. The 20KHz reference pulse signal output through the line a is coupled through the capacitor C1 and applied to the base of the transistor Q1. As a result, the transistor Q1 outputs a 20 KHz pulse inverted to the collector.

The 20KHz reference pulse signal inverted and output to the collector of the transistor Q1 is applied to the base of the transistor Q2 through the capacitor C3 and the resistor R14.

As a result, the transistor Q2 inverts the inverted 20KHz reference pulse signal again and outputs the original 20KHz reference pulse signal to the collector through line a to be applied to the CPU 40. At this time, the central processing unit 40 detects a 20KHz reference pulse signal to detect that the general telephone 10 or the wireless telephone is in use. Since the relay 20, which is not described herein, is the same as the operation of FIG. 1, detailed operation description thereof will be omitted.

As described above, in order to avoid invasion of the telephone in the call, the cordless telephone used by connecting ordinary telephones in parallel on the telephone line is separated from the power supplied from the subscriber line of the exchanger and the supply power used from the cordless telephone. By detecting the state of use of the telephone connected to the device, it is possible to prevent the parts of the cordless telephone from being damaged by the noise introduced into the telephone line, and also has the advantage that it can be applied to the standard of some European countries that use minute electric current. .

Claims (1)

In a wireless telephone using a regular telephone connected to both terminals (L1 and L2) of a telephone line in parallel, a relay for selective switching to establish a priority call when the wireless telephone or the telephone is hooked off. A transformer T1 connected to one terminal L2 of the telephone line and configured to induce a predetermined reference pulse signal to the secondary side when a current loop is formed in the telephone line; and two of the transformer T1. A transformer T2 for reducing a level by inducing a primary reference signal synthesized with a power source supplied from the telephone line to a secondary side to reduce a level, and a signal having a reduced level in the transformer T2. Telephone usage state determination unit 30 for receiving a state of use and outputs a signal for determining the use of the telephone by inputting a telephone usage state determination signal from the usage state determination unit 30 And a central processing unit 40 which detects the state, controls the overall operation of the wireless telephone, and generates a predetermined reference pulse signal (20 KHz) to apply to the primary coil of the transformer T1. Use state detection circuit.