JPS61186059A - Device for preventing mis-start - Google Patents

Abstract

PURPOSE:To prevent mis-start by inserting a filter attached/detached by a relay between the 1st terminal equipment and a subscriber telephone line and inserting the said filter when the 2nd terminal equipment is started. CONSTITUTION:The filter comprised of coils 3, 4 and a capacitor is inserted between the 1st terminal equipment 11 and the subscriber telephone line L. Relays A, B are activated when the 2nd terminal equipment 21 is started from the master station via the telephone line L. When the equipment 21 is started, normally closed contacts a1, a2 of the relay A are opened and the contact (b) of the relay B is closed. Thus, the start frequency component of the equipment 11 in the data signal of the equipment 21 is blocked by the filter comprised of the coils 3, 4 and the capacitor 5.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a first terminal device such as a facsimile connected to a subscriber telephone line and a second terminal device such as for automatic meter reading connected to the same subscriber telephone line. In a system in which data transmission such as automatic meter reading is performed when a telephone or facsimile device is connected and not in use, the first terminal device may be erroneously activated by a data signal component of the second terminal device. used to prevent

Summary of the Invention The present invention provides a system having a first terminal device such as a facsimile connected to a subscriber telephone line, and a second terminal device such as for automatic medical examination connected to the same subscriber telephone line. A filter for blocking an activation signal component is provided between the first terminal device and the subscriber telephone line and is attached and detached by a relay contact, and the filter is inserted when the first terminal device is in operation. This prevents the first terminal device from being erroneously activated by the signal component of the second terminal device.

Conventional technology In recent years, subscriber telephone lines have been used to collect small amounts of data scattered over a wide area, such as to check the usage of water, gas, electricity, etc., monitor various electric power equipment, etc., and investigate the usage of vending machines. A system has been developed in which the data is collected from the main station. On the other hand, public facsimiles using subscriber telephone lines are becoming popular. Public facsimile machines automatically receive calls using a special signal from the facsimile communication network.

That is, the conventional erroneous activation prevention device prevents the facsimile terminal from being activated by any signal other than the above-mentioned special signal.

However, if an automatic medical examination terminal is connected to a subscriber telephone line to which such a facsimile terminal is connected, the facsimile terminal may be erroneously activated due to a special frequency component in the data transmission signal of the automatic medical examination terminal. Sometimes.

Problems to be Solved by the Invention The present invention is intended to prevent one terminal device from being erroneously activated by a data signal in a system in which two terminal devices are connected to the same subscriber telephone line.

Composition of the Invention The false activation prevention device of the present invention comprises: a first terminal device that is housed in an exchange and transmits data such as facsimile signals to a counterpart device connected via the exchange through a subscriber telephone line; and a second terminal device connected to the master station and activated by the master station to transmit meter reading data, etc., wherein the activation signal component blocking device is connected between the first terminal device and the subscriber telephone line. and a relay having a contact that normally puts the filter in a through state and puts it in an inserted state during operation.

When the second terminal device is activated, the relay is operated to put the filter in an inserted state, and when the second terminal device is restored, the relay is restored and the filter is put in a through state. Features.

Embodiments of the Invention Next, the present invention will be described in detail with reference to the drawings.

The figure is a block diagram showing one embodiment of the present invention. That is, the coil 3.4 is inserted in series between the first terminal device 11 and the subscriber telephone line, and the series circuit of the capacitor 5 and the operating contact of the relay B is connected to the first terminal of the coil 3.4. Connect in parallel to the terminal on the device ll side. Coil 3.4 is normally short-circuited by the normal contact al+a2 of relay A, and the operating contact of relay B is normally open. On the wood flow side, the coils 3 and 4 and the capacitor 5 constitute a filter that blocks the activation frequency component of the first terminal device 11. On the other hand, relays A and B are connected to the second terminal device δ21 through the noise removal circuit 2 and the activation line 23, and operate when the second terminal device 21 is activated from the master station through the subscriber telephone line. .

The control circuit 12 of the first terminal device 11 includes a receiving circuit that receives an activation signal of a specific frequency inputted from the subscriber telephone line through a high-wave blocking capacitor 13, and is activated by the activation signal of the specific frequency to automatically receive calls. At times, the switch 14 is closed and the response resistor 15 is connected to the subscriber telephone line for direct current termination. In addition, the power supply circuit 16 rectifies commercial power and supplies the power necessary for the operation of the first terminal device 11, which receives a signal from an off-hook detection circuit 17 that detects off-hook of the telephone 19 and performs necessary control. It is supplied to each part by a line 18.

The second terminal device 21 is directly connected to the local telephone line and is operated by a power supply of opposite polarity supplied through the local telephone line. The second terminal device 21 is activated by a DC voltage of opposite polarity and a single frequency activation signal, and transmits meter reading data etc. collected via a data line 22 to a subscriber telephone line. Also.

At startup, relays A and B of the erroneous startup prevention circuit 1 are operated through the startup line 23. Note that if the second terminal device 21 is activated by the master station and the telephone l119 goes off-hook while it is in operation, the second terminal device 21 is restored due to a drop in the voltage of the subscriber telephone line, and the telephone fi19 It is designed not to interfere with the outgoing operation of the

When the second terminal device 21 is activated, the relays A and B of the accidental activation prevention device 1 operate, and the normal contact aI of the relay A is activated.
+ a2 is open and the operating contact of relay B is closed. Therefore, the first in the data signal of the second terminal device 21
The activation frequency component of the terminal device 11 is blocked by the filter composed of the coils 3 and 4 and the capacitor 5 and is not input to the first terminal device 11.
1 will not be activated by mistake. In addition, the second terminal device 2
The voice says that the telephone 19 went off-hook while the terminal 1 was in operation.As mentioned above, the second terminal 21 recovered and stopped data transmission, and relays A and B, which were operating through the activation line 23, were also activated. Recover. When relays A and H are restored, the normal contact alva2 of relay A closes, the operating contact of relay B opens, the filter enters the through state, and the telephone 19 and first terminal device 11 are connected to the subscriber telephone line. .

Similarly, when a call is automatically made from the first terminal device 11 without using the telephone 18, the second terminal device 21 is restored and the filter enters the through state. Therefore, telephone 91
9. This does not interfere with the calling operation and communication of the first terminal device 11.

Effects of the Invention As described above, in the present invention, a filter that can be attached and detached by a relay contact is inserted between a first terminal device and a subscriber telephone line, and a second terminal device connected to the same subscriber telephone line is inserted. Since the filter is configured to be inserted when the terminal device is activated, it is possible to prevent the first terminal device from being erroneously activated due to a specific frequency component in the data signal of the second terminal device. effective. Note that when the telephone or the first terminal device makes a call while the second terminal device is in operation, the relay is also restored when the second terminal device is restored, and the filter becomes a through state. Calls and communications of the telephone or the first terminal are not interfered with by the second terminal.

[Brief explanation of the drawing]

The figure is a block diagram showing one embodiment of the present invention. In the figure, 1: false start prevention device, 2: # sound removal circuit,
3, 4: Coil, 5: Capacitor, 11: First terminal device, 12: Control circuit, 13: DC blocking capacitor, 1
4: switch, 15: response resistor, 16: 'dlt source circuit, 17: off-hook detection circuit, 18: power supply line, 19
: Telephone, 21: Second terminal device, A. B: relay, al + a2: normal contact of relay A, b: operating contact of relay B.

Claims (1)

[Scope of Claims] A first terminal device that transmits data such as facsimile signals to a counterpart device that is housed in an exchange and connected via the exchange through a subscriber telephone line, and A system comprising a second terminal device that is activated and transmits meter reading data, etc., comprising: a filter for blocking activation signal components connected between the first terminal device and the subscriber telephone line; and a relay having a contact that puts the filter in a through state and puts it in an inserted state when activated, and operates the relay to put the filter in an inserted state when the second terminal device is activated, and puts the filter in the inserted state, An accidental activation prevention device characterized in that when a terminal device is restored, the relay is restored and the filter is put into a through state.