JPS6138911B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a call path monitoring method, and more particularly to a call path monitoring method for monitoring whether a call loop compatible with a telephone device having a new call function is formed. .

Conventionally, in this type of device, when the switching semiconductor element of the communication path switch circuit inserted in the communication loop is exposed to various external noises or a loud sound enters the transmitter, the DC current flowing through the switching semiconductor element is stopped. If the value falls below the required value, it will no longer remain on. For this reason, it is necessary to monitor whether the switching semiconductor element is on, that is, whether a call loop is formed, and a method of providing a monitoring circuit in series on the call loop within the main device is necessary. It is taken.

An example of a conventional system of this kind is shown in Fig. 1. In the figure, MS indicates the main device side, such as a button telephone device, and TEL is connected to the main device MS via line L. This shows the phone side that has been installed. l ₁ and l ₂ are communication lines, and l ₃ is an information transmission line. SCR ₁ and SCR ₂ are switching semiconductor elements forming a communication path switch circuit network on the main device MS side, and E is a switching semiconductor element SCR ₁ and SCR _2.
This DC current source E also serves as a call current source on the TEL side of the telephone. MC is a monitoring circuit to monitor whether a call loop is formed, and IC is an impedance circuit to balance the call loop. This impedance circuit IC is set to have the same impedance as the impedance of the monitoring circuit MC. has been done. TLD is a call loop detection circuit, SPCV is a serial/parallel conversion circuit that converts serial input of various information signals such as telephone key information sent from the telephone TEL side into parallel output and restored, and KD is a serial/parallel conversion circuit from SPCV. This is a telephone key information detection circuit that detects information, such as telephone key information, and is provided on the main device MS side.

TNW is the telephone circuit network on the telephone TEL side, S ₁ , S ₂
......Sn is a switch that turns on and off based on the telephone key information, and PSCV is a parallel/serial conversion circuit that takes the telephone key information formed by switches S ₁ to Sn as parallel input and converts it to serial output. TEL
It is located on the side.

Next, the operation of the apparatus shown in FIG. 1 will be explained. For example, when the telephone is picked up due to an incoming call from the line, and the switching semiconductor devices SCR ₁ and SCR ₂ are turned on, the main device MS
side DC current source E(+) - switching semiconductor element SCR ₁ - monitoring circuit MC - telephone line l ₁ - telephone circuit network
A communication loop is formed through the path of TNW - communication line l ₂ - impedance circuit IC - switching semiconductor element SCR ₂ - DC current source E (-), and the switching semiconductor elements SCR ₁ and SCR ₂ are held, and the telephone TEL side is supplied with communication current. Next, the ON states of the switching semiconductor elements SCR ₁ and SCR ₂ are monitored. That is, when the monitoring circuit MC, which monitors whether a call loop is formed, detects an abnormality such as disconnection of the call loop, the call loop detection circuit TLD operates to detect whether a call loop has not been formed.

On the other hand, the telephone key information on the telephone TEL side is Switch S ₁
The information output is extracted by turning on (closed) Sn, and its information output becomes serial transmission of time-division pulses via the parallel/serial conversion circuit PSCV, and serial/parallel conversion on the main device MS side via the information transmission line _L3 . It enters the circuit SPCV and becomes a parallel output, and the output is the telephone key information detection circuit
Detected by KD.

Here, the monitoring circuit MC always has some impedance, and since this impedance is inserted into the communication loop, the communication lines l ₁ , l ₂
This causes a difference in impedance. This is due to an imbalance in the cable connecting the main device MS and the telephone TEL side, and so-called common mode noise is superimposed on the call loop. In order to eliminate this problem, it has conventionally been necessary to provide an impedance circuit IC having the same impedance as the monitoring circuit MC on the communication line _l2 side of the main device MS. This point will be explained in more detail.

FIG. 2 is a diagram showing an equivalent circuit for the common mode noise in FIG. 1. In the figure, CMN
is the common mode noise source, Z _M is the impedance of the monitoring circuit MC provided in the main device MS, and Z _I is the impedance circuit with the same value as the impedance Z _M
The impedance of the IC, Z _l1 is the impedance of one cable, Z _l2 is the impedance of one cable similar to impedance Z _l1 , Z _L is the load of the telephone, Z _E1 is the impedance of one cable to ground, Z _E2 are the respective values of the impedance of one cable to the ground, similar to the impedance Z _E1 . The cable impedance values Z _l1 and Z _l2 have a relationship of Z _l1 = Z _l2 ,
Also, the impedance value Z of the cable to the ground
_E1 and Z _E2 have a relationship of Z _E1 =Z _E2 .

Therefore, if there is no impedance value Zr of the impedance circuit IC, that is, Z _I =
When the voltage is 0, the voltage generated by the common mode noise source CMN causes the load Z _L of the telephone to be
A potential difference occurs and current flows. To prevent this, the impedance Z _M must be set to Z _I . That is, an element having the same impedance as the monitoring circuit MC, for example, one of C, L, R, or a dummy impedance Z _I consisting of a plurality of elements is required. For this reason, the circuit configuration becomes complicated and there is a disadvantage that it is not economical.

In view of the above points, the present invention provides a call path monitoring system designed to solve such problems.The present invention provides a monitoring means for monitoring whether a call loop is formed on the telephone side, and monitors the call path. The monitoring output obtained by the means is transmitted to the main device side through an information transmission line other than the telephone line. Hereinafter, embodiments of the present invention will be described in detail based on the drawings.

FIG. 3 is a block diagram showing an embodiment of the communication current monitoring system according to the present invention. In Fig. 3, the same symbols as in Fig. 1 indicate corresponding parts, P _d is a light emitting element connected to the input end of the telephone circuit network TNW on the telephone TEL side, and P _t is a light emitting element connected to the input end of the telephone circuit network TNW on the telephone _TEL side. A light-receiving element that receives light forms a photocoupler PC, and this photocoupler PC constitutes means for detecting the presence or absence of a call loop. and the light emitting element P _d is connected in the forward direction between the telephone line l ₁ and the input end of the telephone network TNW on the telephone TEL side,
The collector of the light receiving element _Pt is connected to the power supply + via the resistor R.
Connected to 5V and parallel/serial conversion circuit
It is connected to PSCV and the emitter is grounded.
In addition _, one end of the switches S ₁ , S ₂ . . _{. .} . . ...Connected to the power supply +5V via Rn, and also connected to the parallel/serial conversion circuit PSCV.

Next, the operation of the embodiment shown in FIG. 3 will be explained. First, when the switching semiconductor elements SCR ₁ and SCR ₂ forming the channel switch circuit network are held in the on state, the direct current source E(+) - the switching semiconductor element
SCR ₁ - Call line l ₁ - Light emitting element P _d - Telephone circuit network
TNW - Telephone line l ₂ - Switching semiconductor device
A direct current flows from the main device MS side to the telephone TEL side through the path SCR ₂ -DC current source E(-) to form a communication loop. At the same time, the light emitting element P _d emits light due to this direct current, and this light is received by the light receiving element P _t , so that the light receiving element P _t shifts to a conductive state. When the light-receiving element _Pt becomes conductive, communication loop formation information is transmitted to the serial-to-parallel converter circuit SPCV on the main device MS side via the parallel-to-serial conversion circuit PSCV and the information transmission line _L3 , and this information is transmitted to the communication loop detection circuit. TLD detects.

Next, switching semiconductor devices SCR ₁ and SCR ₂
If any of them shifts to the OFF state due to, for example, a line being opened, the call loop is no longer formed and the DC current is cut off, so the light emitting element P _d stops emitting light and the light receiving element P _t shifts to the cut-off state. do.
When the light-receiving element _Pt is cut off, the communication loop non-formation information is transmitted to the serial-parallel converter circuit SPCV on the main device MS side via the parallel-serial converter PSCV and the information transmission line _l3 , and the communication loop is not formed. Loop detection circuit TLD
is detected.

On the other hand, as described above, electronic key information based on time allocation is generally transmitted in series using time-division pulses. In other words, the outputs of multiple telephone keys and telegrams corresponding to switches S ₁ , S ₂ ......Sn are converted into parallel/serial converters.
It is transmitted to the serial/parallel conversion circuit SPCV on the main device MS side via the PSCV and the information transmission line _L3 , and detected by the electronic key information detection circuit KD.

FIG. 4 is a diagram showing an equivalent circuit for the common mode noise of FIG. 3. In FIG. 4, the same reference numerals as in FIG. 2 indicate corresponding parts, and Zp is the impedance of the light emitting element _Pd provided in the telephone TEL and forming the photocoupler PC. and,
Cable impedance Z _l1 , Z _l2 is Z _l1 = Z _l2
It is fully expected that the impedances Z _E1 and Z _E2 of the cable with respect to the ground will be in the relationship Z _E1 =Z _E2 .

Therefore, impedance Z _l1 = Z _l2 , Z _E1
As long as = Z _E2 , there is no potential difference between points A and B, and no current flows. In other words, since the dummy impedance Z _I shown in Fig. 2 is not required, the circuit configuration on the main device MS side is simplified.
Economically effective. In addition, the communication path monitoring information is configured to be sent via the conventionally used information transmission line _L3 , and there is no need to install a special transmission line, and the parallel/serial conversion circuit PSCV can be used, making it extremely economical. It is true.

In the above embodiment, a photocoupler is used as a monitoring means to monitor whether or not a call loop is formed. However, the present invention is not limited to this, and relays, etc. It can also be composed of

As explained above, according to the present invention, a call loop can be reliably and stably formed without providing a dummy impedance _ZI as in the past and without being affected by common mode noise. This has an extremely large practical effect because it allows you to monitor what is going on. In addition, since it is possible to use some existing means without using complicated means such as providing a dummy impedance, the communication current can be monitored with a simple configuration, which is economical. is also extremely effective.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing an example of a conventional communication path monitoring system, FIG. 2 is an equivalent circuit diagram for common mode noise in FIG. 1, and FIG. 3 is an embodiment of the communication path monitoring system according to the present invention. The configuration diagram and FIG. 4 are equivalent circuit diagrams for the common mode noise in FIG. 3. MS...Main device, TEL...Telephone, E...DC current source, SCR ₁ , SCR ₂ ...Switching semiconductor element, _l1 , _l2 ...Talking line, _l3 ...Information transmission line, PC...
…Photocoupler, TNW…telephone circuit network.

Claims (1)

[Claims] 1. In a telephone device in which the main device side and the telephone side are interconnected by a communication path and an information transmission path, a switching semiconductor device is used as a communication path switch that opens and closes the communication path, and the operating state of the switching semiconductor device is The device is configured such that a direct current that maintains the current and a communication current of the telephone are supplied from a direct current source provided on the main device side, and monitors whether or not the communication path is formed based on the operation of the switching semiconductor element. A communication path monitoring system characterized in that a monitoring means is provided on the telephone side, and a monitoring output obtained by the monitoring means is transmitted to the main device side through the information transmission path.