JPS6025953B2 - Power failure monitoring circuit - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to power failure monitoring in the event of a power outage or failure in a button telephone device.

In general, button telephone devices are equipped with a power failure monitoring relay that is always active when the main source is in normal state, and when there is an incoming call from the central office line, the relay that operates on the main source The display circuit displays incoming calls.

However, if the power is cut off due to a power outage, etc., the relay is restored, and the contacts of the nuclear relay are used to activate a separately provided means of receiving calls, such as an additional bell (hereinafter referred to as the "additional bell").
A straw bag is attached to the central office line, and the ring rings to indicate an incoming call. However, in recent years, there has been a trend towards adopting circuit elements such as integrated circuits for central office line incoming call display control circuits, etc., and the power supply for the circuit elements (hereinafter referred to as "11 power supply") is a separate power supply from the operating power supply for the relay. In this case, even if a fault (for example, a short circuit fault) occurs in the circuit constituted by the circuit elements and the first power supply becomes inoperable, the general appliance will not be restored. In other words, even if a storm line call arrives, the incoming call display control circuit, which is its load, has stopped operating due to the inoperation of the 11 power supply, so the incoming call cannot be displayed, and the additional bell cannot ring because the relay has not been restored. do not have. Therefore, a problem arises in that it is not possible to display any incoming calls on the central office line. Particularly in the case of integrated circuit devices, there is a good possibility that a failure will occur due to the latch-up phenomenon specific to the device. In order to solve these problems, the present invention provides a failure monitoring circuit that detects and controls the failure when a failure occurs in the output of the -1 power supply, and restores the Hinaden appliance by controlling the failure monitoring circuit. By connecting an additional bell to the central office line, an incoming call can be displayed when a call is received from the central office line.

An embodiment of the present invention will be explained in detail below with reference to the drawings.

In Figure 1, L is the office line, M is the main device, N' is the telephone,
1 is an additional bell, 2 is a signal receiving circuit, 3 is a central office line incoming call display control circuit, 4 is a -1 power supply load circuit other than the circuit in 3, 5 is a - power supply load circuit, e■ is a power supply (■ is -1 fin source), a is the line that sends the incoming signal to telephone N. T
RI is a transistor, ZDI is a Zener diode that detects the -1 power supply state, RI is a current limiting resistor,
These monitor the failure of the -1 power supply and control the operation of relay T, which will be described later.

T is a power failure monitoring relay that monitors power failures of one power source and performs recovery control by the above-mentioned failure monitoring circuit, tl is a contact point of the relay, and D1 is a protection diode of the transistor TRI. ZD2 is a Zener diode that determines the power supply voltage of the -1 power supply, R2 is a current limiting resistor, and these constitute the -1 power supply. However, the 11 power supply circuit is
This is the simplest and most economical circuit configuration example, and other power supply circuit configurations are also effective. FI is a single power supply protection fuse. FIG. 2 shows a partially simplified circuit configuration in which RX indicates an equivalent resistance. Next, the operation will be explained. Normally, the transistor TRI is turned on in the next circuit.

When TRI is turned on, relay T operates, and its contact tl is switched to the signal receiving circuit 2 side (dotted line side).
Now, when an incoming signal arrives on the station line L', the signal receiving circuit 2
In response to the signal, the central office line incoming call display control circuit 3
is activated to display on telephone N via line a that a call is being received from the central office line. Further, when a failure occurs in the load circuit 5 of one power source, the power failure monitoring relay is restored by blowing the FI fuse. Now, as mentioned above, 11
To describe the case where a failure occurs in the load circuit 3 or 4 of the power supply, the load circuit 3 or 4 is composed of integrated circuit elements, and these elements do not cause excessive noise or noise to the input terminal during normal operation. When voltage or current such as surge is applied,
In addition, when the power supply amplitude changes suddenly, a current flows in the opposite direction to the normal input/output current at the input and output of the device, and this current triggers a latch-up, which causes the power supply terminal of the integrated circuit device to become a type of short circuit. state.

The -1 power source is supplied from one power source through a resistor R2, and its voltage is stabilized by a Jenner diode ZD2.

This is because, as shown in Figure 2, the equivalent resistance of ZD2 is the smallest among the equivalent resistances RX during normal operation.
I + RI) equivalent resistance〆ZD2〆Equivalent resistance of loads 3 and 4〆〆〆Equivalent resistance of loads 3 and 4] The voltage between -1 and ground is determined by Zener diode ZD2, but failures such as latch-up occur in load circuits 3 and 4, and the equivalent resistance decreases. When the resistance becomes sufficiently smaller than the equivalent resistance of ZD2, ZD2 cannot maintain a constant voltage supply between 1 and ground (TRI + ZDI + RI).
) The equivalent resistance of ZD2 is the ratio of the equivalent resistance of loads 3 and 4 to R2 (the ratio is smaller on the equivalent resistance side than in normal conditions). decreases and the entire load circuit stops its operation. At the same time, the transistor TRI is cut off by the detection Zener diode ZDI. Therefore, the relay T is restored and its contact tl is switched to the side of the additional bell 1 (solid line side), and thereafter the incoming signal from the office line L is applied to the added bell 1 to display an incoming call. Because of this circuit configuration, even if the power outage monitoring relay is not connected to the -1 power source, it will detect the status of the -1 power source, and the outage monitoring relay T, which is connected to the 1 power source, will detect the status of the -1 power source.
can be restored.

As explained above, according to the present invention, when there are multiple power sources due to the adoption of elements such as integrated circuits, the relay is provided in one of the power sources without providing a power failure monitoring relay for each power source, In addition, if a power failure monitoring circuit is installed, even if a fault occurs and the central office line incoming call display control circuit becomes inoperable and the central office line incoming call cannot be displayed, the monitoring circuit will restore the relay. Incoming calls can be displayed using an additional bell. That is, power failures can be monitored without having to turn on a plurality of power failure monitoring relays, and the system is put to practical use without being left unattended without displaying an incoming call, which is extremely effective.

Furthermore, there is a high possibility that failures will occur in integrated circuit devices due to latch-up phenomena, etc., and countermeasures against such failures are effective.

[Brief explanation of the drawing]

FIG. 1 is a circuit configuration diagram showing one embodiment of the present invention, and FIG. 2 is a partially simplified circuit configuration diagram. In Figure 1, L is a central office line, M is a main device, N is a telephone,
1 is an additional bell, 2 is a signal receiving circuit, 3 is a central office line incoming call display control circuit, 4 is a load circuit for -1 power supply other than 3, 5 is a load circuit for one power supply e■ is a power supply, a is a telephone N T is the relay for power failure monitoring, tl is the contact point of the vertical electric device T, TRI is the transistor, blood 1 is the line that sends the incoming signal to
The diode, RI is a current limiting resistor, ZD2 is a -1 power supply Jenner diode, R2 is a current limiting resistor, DI is a protection diode for the transistor TRI, FI is a protection fuse for one power supply, in Figure 2 RX indicates equivalent resistance. Figure 2 Figure 1

Claims (1)

[Claims] 1. In a button telephone device that can continue to display incoming calls from the central office line by restoring the power failure monitoring relay connected to the power supply during a power outage, a power source other than the operating power source of the power failure monitoring relay connected to the power supply When a fault occurs in the output circuit of the relay, a fault monitoring circuit connects a detection circuit that detects the fault by comparing it with a reference voltage to a relay drive circuit that controls the operation of the relay, and restores the relay to the station. A power failure monitoring circuit characterized in that it is capable of displaying an incoming call.