JPH04298198A - Adaptor for home telephone set - Google Patents

Abstract

PURPOSE:To realize the adaptor for a home telephone set by which an inexpensive system is formed on request of the user and in which crosstalk or circuit destruction is prevented. CONSTITUTION:A control circuit 103 lights a light emitting diode 110 or 111 in response to a call signal from a slave set received by a switching circuit 101 or 102 to make a photo transistor 112 or 113 conductive. A master telephone set detects it that the photo TR 112 or 113 is conductive to attain talking with the slave set. The slave set side control circuit connecting to the slave set and the master telephone set side control circuit connecting to the master telephone set are isolated electrically by a secondary circuit of a power transformer 104, the light emitting diode 110 and the photo TR 112 and the light emitting diode 111 and the photo TR 113 each forming a photocoupler.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an adapter device used in a home telephone for transmitting and receiving calls between a master telephone, a slave telephone, and an external telephone.

0002

2. Description of the Related Art Conventionally, in home telephones that transmit and receive calls between a base telephone, a handset, and an external telephone, an adapter device has been used to connect a slave such as a door phone and a base telephone. FIG. 2 shows an example of the configuration of a general home telephone system.

[0003] In FIG. 2, two door phones 201 and 202 as slave units are connected to a master telephone 204 via an adapter device 203. In addition, the external central office switch 2
05 is parallel cable K1, K2 and adapter device 20
3 to the main telephone 204. The adapter device 203 includes an interface circuit 206, a power supply circuit 207, and a transformer 208, and is connected to a commercial power source via the transformer 208. Main phone 2
04 is the base phone communication circuit 209 and the diode bridge 21
0 and a power supply circuit 211, and is connected to a commercial power supply via an AC adapter 212.

[0004] Communication between the door phone 201 or 202 and the main telephone 204 is conducted under the control of an interface circuit 206 . Further, calls between the main telephone 204 and the outside are carried out via the central office exchange 205, cables K1 and K2, and the adapter device 203. FIG. 3 is a block diagram of a conventional adapter device, and FIG. 4 is a schematic block diagram of a general base telephone. In both figures, Figure 2
The same parts are given the same symbols.

In FIG. 3, terminals L1 and L2 connected to a central office exchange 205 (see FIG. 2) are directly connected to terminals 1 and 2. Signal terminal D1 of door phone 201 (see Figure 2)
is connected to the common terminal C of the relay switch 119, and the signal terminal D2 of the door phone 202 (see FIG. 2) is connected to the common terminal C of the relay switch 120. The make terminal M of the relay switch 119 is connected to a hybrid circuit 1 that performs 2-wire to 4-wire conversion and is configured with a transformer or the like.
09 and the make terminal M of the relay switch 120. Break terminal B of relay switch 119 is connected to one input terminal of switching circuit 101. The output terminal and the other input terminal of switching circuit 101 are connected to terminals a and c of control circuit 301, respectively. Break terminal B of relay switch 120 is connected to one input terminal of switching circuit 102. The output terminal and the other input terminal of the switching circuit 102 are connected to terminals b and d of the control circuit 301, respectively. Terminals f and e of the control circuit 301 are connected to the bases of PNP transistors 304 and 305 via resistors, respectively. On the other hand, terminal 3 is connected to hybrid circuit 109 via amplifier 114 and to the collector of transistor 304 via a resistor. Further, the terminal 4 is connected to the hybrid circuit 1 via the amplifier 115.
09 and the transistor 30 via a resistor.
5 collector. Terminal 5 is connected to input terminal g of comparator 116. The output terminals h and i of the comparator 116 are connected to the relay switch 119, respectively.
It is connected to a relay coil 117 that switches and drives a relay switch 120, and a relay coil 118 that switches and drives a relay switch 120. On the other hand, a commercial power source is connected to the primary side of the transformer 208, and the secondary side is connected to a smoothing circuit 303 via a diode bridge 302. diode bridge 3
02 and the smoothing circuit 303 constitute a power supply circuit 207. A positive voltage side terminal and a reference voltage side terminal of the smoothing circuit 303 are connected to each of the above-mentioned component circuits. Further, terminal 6 is a reference voltage terminal. In addition, relay switch 119
, 120, the switching circuits 101 and 102, the control circuit 301, and the primary side circuit of the hybrid circuit 109 constitute a slave side control circuit. Further, the secondary side circuit of the hybrid circuit 109, amplifiers 114 and 115, comparator 116, relay coils 117 and 118, and transistors 304 and 305 constitute a master telephone side control circuit.

FIG. 4 is a schematic block diagram of a typical base telephone used with the adapter device of FIG. Terminals 1 to 6 correspond to terminals 1 to 6 in FIG. In FIG. 4, a receiver section R and a microphone section M of a handset 401 are connected to a call switching matrix switch 406 via amplifiers 404 and 405, respectively. Terminals 1 and 2 are connected via a diode bridge 415 to a hybrid circuit 414 that performs 2-wire to 4-wire conversion. Terminals 3 and 4 are connected to a matrix switch 406 via amplifiers 402 and 403, and are also connected to first and second input terminals of a control circuit 416. Terminal 5 is connected to the output terminal of control circuit 416. The control circuit 416 has a numeric keypad 418 and a hook switch 417 connected to third and fourth input terminals. A
The C adapter 212 (see Figure 2) connects the diode bridge 4
It is connected to a smoothing circuit 419 via 20. The diode bridge 420 and the smoothing circuit 419 are the power supply circuit 2
It consists of 11. A positive voltage side terminal and a reference voltage side terminal of the smoothing circuit 419 are connected to each of the component circuits. Further, terminal 6 is a reference voltage terminal.

The operation of the adapter device configured as described above will be explained below with reference to FIGS. 2, 3, and 4. It is assumed that the contacts of the relay switches 119 and 120 are in the state shown in FIG. 3 as an initial state. When a calling signal is issued from the door phone 201, this signal is outputted to the terminal a of the control circuit 301 via the terminal D1, the common terminal C of the relay switch 119, the break terminal B, and the switching circuit 101. Control circuit 301 responds to this signal to output terminal c.
A call confirmation signal is output from the switching circuit 101 to the switching circuit 101. This call confirmation signal is sent to the doorphone 1 via the break terminal B, common terminal C, and terminal D1 of the relay switch 119.
sent to. At the same time, from the terminal f of the control circuit 301,
A low level signal is output. This low level signal is applied to the base of transistor 304 via a resistor, the output signal of transistor 304 becomes high level, and terminal 3 also becomes high level. The control circuit 416 receives this high level signal and drives the ringing bell of the main phone (not shown) to notify the main phone that the door phone 1 has called the main phone. Next, when the handset 401 of the main telephone is disconnected and the hook switch 417 is switched to the talking state, the control circuit 416 detects this and changes the potential of the terminal 5 from the low level to the potential V1. The comparator 116 has a terminal 5 at a potential V1.
is detected, and the relay coil 117 is driven. This operates the relay switch 119, and the common terminal C of the relay switch 119 is connected to the make terminal M.

[0008] Through the above-described operation, the transmitted sound from the base telephone is transmitted to the microphone section M of the handset 401, the amplifier 405, the matrix switch 406, the amplifier 402, the terminal 3, the amplifier 114, the hybrid circuit 109, and the relay switch 1.
It is transmitted to the door phone 201 via the make terminal M, the common terminal C, and the terminal D1 of No. 19. On the other hand, the voice received from the door phone 201 includes the door phone 201, terminal D1, common terminal C of the relay switch 119, make terminal M, hybrid circuit 109, amplifier 115, terminal 4, amplifier 403,
The signal is output from the receiver section R of the handset 401 via the matrix switch 406 and the amplifier 404.

[0009] To end the call, put down the handset and return the hook switch 417 to its initial state. Control circuit 416 detects this and outputs a low level signal to terminal 5. Comparator 116 detects that terminal 5 has become low level and stops driving relay coil 117. As a result, the common terminal C of the relay switch 119 is connected to the break terminal B.
is connected and returns to the initial state.

Next, when a call is made from the door phone 202, a call signal is supplied to the terminal D2. This signal is
The signal is output to terminal b of the control circuit 301 via the terminal D2, the common terminal C of the relay switch 120, the break terminal B, and the switching circuit 102. Control circuit 301 outputs a call confirmation signal from terminal d to switching circuit 102 in response to this signal. This call confirmation signal is transmitted to the break terminal B, common terminal C, and terminal D of the relay switch 120.
is transmitted to the doorphone 202 via the . At the same time, a low level signal is output from the terminal e of the control circuit 301. This low level signal is applied to the base of transistor 305 through a resistor, and the output signal of transistor 305 becomes high level, and terminal 4 also becomes high level. The control circuit 416 receives this high-level signal and drives the ringing bell of the main phone (not shown) to notify the main phone that the door phone 202 has called the main phone. Next, the handset 4 of the main phone
01 and switches the hook switch 417 to the talking state side, the control circuit 416 detects this and changes the potential of the terminal 5 from the low level to the potential V2. Comparator 116 detects that terminal 5 has reached potential V2, and drives relay coil 118. This operates the relay switch 120, and the common terminal C of the relay switch 120 is connected to the make terminal M.

[0011] Through the above operations, the transmitted sound from the base telephone is transmitted to the microphone section M of the handset 401, the amplifier 405, the matrix switch 406, the amplifier 402, the terminal 3, the amplifier 114, the hybrid circuit 109, and the relay switch 1.
The signal is transmitted to the door phone 202 via the make terminal M, common terminal C, and terminal D2 of No. 20. On the other hand, the voice received from the door phone 202 includes the door phone 202, terminal D2, common terminal C of the relay switch 120, make terminal M, hybrid circuit 109, amplifier 115, terminal 4, amplifier 403,
The signal is output from the receiver R of the handset 401 via the matrix switch 406 and the amplifier 404.

When ending the call, the hook switch 417 is returned to its initial state. Control circuit 416 detects this and outputs terminal 5.
Outputs a low level signal to the The comparator 116 is
When it is detected that the terminal 5 has become low level, the driving of the relay coil 118 is stopped. This connects the common terminal C of the relay switch 120 to the break terminal B,
Return to initial state.

[0013] For communication between the main phone and the outside, terminal L1
, L2, terminals 1 and 2, diode bridge 415, hybrid circuit 414, amplifiers 409 and 410, matrix switch 406, and amplifiers 404 and 405. Further, transmission to a wireless slave device (not shown) is performed via a microphone section M, an amplifier 405, a matrix switch 406, an amplifier 408, a transmitter 412, a mixer 413, and an antenna. The antenna, mixer 413, and receiving circuit 41
1, the amplifier 407, the matrix switch 406, the amplifier 404, and the receiver section R.

[0014]

[Problem to be Solved by the Invention] By using the adapter device configured as described above, it is possible to connect the main phone and various handsets to configure home telephone systems in various ways. . However, in the above-mentioned adapter device, the control circuit on the main phone side and the control circuit on the handset side are electrically connected by the reference potential line and the connection cable between the control circuit 301 and the transistors 304 and 305. Various problems arise when connecting a video door intercom system that uses a power source of this type. This will be explained using FIG. 5.

FIG. 5 is an equivalent circuit diagram equivalently representing the block diagram of FIG. 2 focusing on impedance, and the same parts as in FIG. 2 are given the same reference numerals. However, the door phone 201 in FIG. 2 is replaced with a camera built-in door phone 502, and a monitor unit 501 is connected between the adapter device 203 and the camera built in door phone 502. In FIG. 5, the central office exchange 205 connects the main telephone 20 to the main telephone 20 via parallel cables K1 and K2.
4 to the adapter device 203. The adapter device 203 is connected to a series circuit of a monitor unit 501 and a camera built-in door phone 502, and the door phone 202, respectively. The parallel cables K1 and K2 are each
It has an earth impedance Z1. Main phone 20
4. The adapter device 203, the door phone 202, the monitor unit 501, and the door phone with built-in camera 502 are each:
They have ground impedances Z2, Z3, Z4, Z5, and Z6, and their reference potential sides are commonly connected to each other. Furthermore, the master telephone 204 is grounded via a power supply circuit 211 and an AC adapter 212, and the adapter device 203
is grounded via a power supply circuit 207 and a transformer 208. On the other hand, the monitor unit 501 and the camera built-in door phone 502 are grounded via a switching power supply 503. The switching power supply 503 includes a switching circuit 504 and a series circuit of smoothing capacitors C1 and C2.

As described above, when a switching power supply is used, the ground impedance of cable K1 is Z
1, but since the series capacitance of capacitors C1 and C2 are connected in parallel to Z1, the ground impedance of cable K2 is

[0017]

[Math 1]

[0018] Therefore, cables K1, K2
There is a problem in that the impedances between the two cables and the ground are different, and the balance between the two cables is lost, resulting in crosstalk. In addition, if a lightning strike occurs on the cable K1 or K2, the diode bridge 415, the reference potential, the capacitor C1, the capacitor C2,
A large current flows through the earth path, causing the diode bridge 415
There was a problem that the diodes constituting the diodes were destroyed.

[0019] As a method of solving the above problem, it is also possible to provide an insulating circuit between the cables K1 and K2 within the main telephone set 204. However, this method has the problem that the base phone becomes expensive, which is disadvantageous to users who do not need to configure the above-mentioned system. The present invention was made in view of the above problems,
It is an object of the present invention to provide an adapter device that can prevent crosstalk and circuit destruction, and can configure an inexpensive system in accordance with user requirements.

[0020]

[Means for Solving the Problems] The present invention provides a home telephone adapter device which is disposed between a base telephone and a handset and includes a master telephone side control circuit and a slave side control circuit. The present invention is characterized in that it includes an insulating circuit that electrically insulates between the side control circuit and the handset side control circuit.

[0021]

[Operation] The insulating circuit within the adapter device electrically insulates the main phone and handset, and disturbances on the main phone are not transmitted to the handset.

[0022]

Embodiment FIG. 1 is a block diagram showing an embodiment of the present invention. In FIG. 1, the same parts as in FIG. 3 are given the same reference numerals. The operations of the parts that are different from those in FIG. 3 will be explained below. The terminals f and e of the control circuit 103 have
Light emitting diodes 110 and 111 are connected to each. Phototransistors 112 and 113 are connected to terminals 3 and 4 via resistors, respectively. light emitting diode 1
10, phototransistor 112, and light emitting diode 11
1 and phototransistor 113 each constitute a photocoupler. A commercial power source is connected to the primary side of a transformer 104 having two secondary windings. transformer 10
4 is connected to a smoothing circuit 106 via a diode bridge 105. Smoothing circuit 10
The positive voltage side terminal and the reference voltage side terminal 6 are connected only to the constituent circuits of the slave side control circuit. On the other hand, transformer 1
The other secondary winding of 04 is a diode bridge 107
It is connected to the smoothing circuit 108 via. Smoothing circuit 1
The positive voltage side terminal and the reference voltage side terminal of 08 are connected only to the constituent circuits of the master telephone side control circuit. The two photocouplers and the transformer 104 constitute an insulating circuit, and the handset-side control circuit and the master phone-side control circuit are electrically insulated from each other.

The operation of the adapter device configured as above will be explained below. In addition, relay switches 119, 12
It is assumed that the contact point 0 is in the state shown in FIG. 1 as an initial state. When a calling signal is issued from the door phone 201, this signal is outputted to the terminal a of the control circuit 103 via the terminal D1, the common terminal C of the relay switch 119, the break terminal B, and the switching circuit 101. Control circuit 103
is the switching circuit 1 from terminal c in response to this signal.
Outputs a call confirmation signal to 01. This call confirmation signal is
Break terminal B and common terminal C of relay switch 119
, is transmitted to the door phone 201 via the terminal D1. At the same time, a high level signal is output from the terminal f of the control circuit 103. This high level signal causes the light emitting diode 110 to
emits light. This light is received by the phototransistor 112, and the phototransistor 112 becomes conductive. This causes terminal 3 to go high. The master telephone in FIG. 4 performs the above-described operation in response to the high level signal at terminal 3, and outputs a signal at potential V1 to terminal 5. Comparator 116 detects that terminal 5 has reached potential V1, and drives relay coil 117. This operates the relay switch 119, and the common terminal C of the relay switch 119 is connected to the make terminal M.

Thereafter, as described above, the door phone 201
A call is made between the parent phone and the parent phone. Next, doorbell 2
When a calling signal is issued from 02, this signal is sent to terminal D.
2. Control circuit 103 via common terminal C of relay switch 120, break terminal B, and switching circuit 102
is output to terminal b. Control circuit 103 outputs a call confirmation signal from terminal d to switching circuit 102 in response to this signal. This call confirmation signal is transmitted to the door phone 202 via the break terminal B, common terminal C, and terminal D1 of the relay switch 120. At the same time, control circuit 1
A high level signal is output from terminal e of 03. This high level signal causes the light emitting diode 111 to emit light. This light is received by the phototransistor 113, and the phototransistor 113 becomes conductive. This causes terminal 4 to go high. The master telephone in FIG. 4 performs the above-described operation in response to the high level signal at terminal 4, and
2 signal is output to terminal 5. The comparator 116 is
It is detected that the terminal 5 has reached the potential V2, and the relay coil 118 is driven. This allows relay switch 120
operates, and the common terminal C of the relay switch 120 is connected to the make terminal M. Thereafter, a call is made between the door phone 202 and the main phone as described above.

According to this embodiment, a photocoupler and two
Since the transformer 104 having two secondary windings is used to electrically insulate the control circuit on the main phone side and the control circuit on the handset side, crosstalk can be prevented and cables K1 and K2 can be struck by lightning. Even if this occurs, circuits such as diodes can be prevented from being destroyed. Furthermore, it is also possible to prevent the generation of noise caused by interference from power lines and the like. Furthermore, it becomes possible to configure an inexpensive system according to the user's request.

[0026]

According to the present invention, since an insulating circuit is provided to electrically insulate between the control circuit on the main phone side and the control circuit on the handset side, the adapter device of the present invention can be used to create a home telephone system. If constructed, crosstalk can be prevented in various systems, and circuits such as diodes can be prevented from being destroyed even if the cables K1 and K2 are struck by lightning. Furthermore, it is also possible to prevent the generation of noise caused by interference from power lines and the like. Furthermore, it becomes possible to configure an inexpensive system according to the user's request.

[Brief explanation of the drawing]

[Fig. 1] Block diagram showing one embodiment of the present invention

[Figure 2]
Block diagram representing a typical home telephone system

[Figure 3] Block diagram of a conventional adapter device

[Figure 4] Block diagram of a typical base phone

[Figure 5] Equivalent circuit diagram of a typical home telephone system

[Explanation of symbols]

101, 102...Switching circuit 103 forming a control circuit on the handset side...Control circuit 104 forming a control circuit on the handset side
...Power transformer 109 forming an isolation circuit...Hybrid circuits 110, 111 forming an insulation circuit...
- Light emitting diodes 112, 113 forming an insulating circuit...Phototransistors 114, 115 forming an insulating circuit...Amplifier 116 forming a main phone side control circuit...Comparator 117 forming a main phone side control circuit , 118... Relay coils 119, 120 forming the control circuit on the main phone side, and relay switches forming the control circuit on the handset side.

Claims (1)

[Claims] 1. A home telephone adapter device disposed between a base phone and a handset and comprising a base phone side control circuit and a handset side control circuit, wherein the base phone side control circuit and the handset side control circuit are provided. A home telephone adapter device characterized by comprising an insulating circuit that electrically insulates between it and a control circuit.