JPH0260421A - Internal power supply circuit - Google Patents

Abstract

PURPOSE:To prevent transmission of a fault signal to the outside during OFF interval by providing a contact for shortcircuiting an AND gate formed with a fault detection relay when a common contact for turning an inner power source ON/OFF is turned OFF. CONSTITUTION:Power is fed from a power source 1 through a circuitbreaker 2, a noise filter 3, DC/DC converters 6A, 6B and the like to each unit. Fault detection relays K2-K5 are arranged on respective lines such that they are opened upon detection of a fault. These contacts are connected in series in order to drive a fault signal relay K6 for transmitting a fault signal to the outside. All fault detection relays are turned OFF when a relay K1 for controlling power supply to each unit is turned OFF, and an erroneous detection signal is provided. ln order to prevent transmission of erroneously detected signal, the series connection of the relay contacts k2-k5 is shortcircuited through the normal close contact k1b of the relay K1.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a power supply circuit within an electronic device or the like.

[Conventional technology]

FIG. 3 shows a conventional example of this type of power supply circuit. In the figure, ■ is an external power input, 2 is a circuit breaker, 3 is a noise filter, 4 is a power supply for timer control unit 4A, 5 is fuse F1, fl is a contact that closes when fuse F1 is blown, 6A and 6B are D C/DC converter, 7.7A, 7B is an internal power supply that supplies power to the corresponding circuit unit in the device, 8 is a failure signal input from each part in the device, 9 is power control from timer control unit 4A A signal 10 is a failure signal of the optical device to be output to an external device.

K1 is a relay controlled by a power supply control signal 9, and the contact point 1 is a common contact point. K2~5
K6 is a failure detection relay (hereinafter simply referred to as relay), whose respective contacts are connected in series to form an AND circuit, and a failure signal output relay (hereinafter simply referred to as relay) K6 is connected to the AND circuit. is connected. K6 is the 6th output contact on the output relay.

In this configuration, external power input is supplied to a timer control unit 4 via a circuit breaker 2 and a noise filter 3. The timer control unit 4A turns on (ground) and 10FF (opens) the power control signal 9 to turn on/off the power inside the device according to its own timer function. When power control signal 9 is OFF, relay 1 is in a non-conducting state,
Contact kl is closed, and power is supplied to the internal units of the device from the corresponding power supplies 7.7A and 7B. At this time, relays 2, K3, and K4 are in a conductive state, and K
Since 5 is in a non-conducting state, 2, k3, k4, k are connected to the contacts.
5 is closed, the relay 6 is conductive, the contact 6 is open, and the fault signal 10 to the external device is in the OFF state. In this state, if a failure occurs in either of the power supplies 7.7A and 7B (for example, a failure in the DC/DC converter 6), and the corresponding relay among relays 2 to 4 becomes non-conductive, The corresponding contacts open, thereby
The relay 6 becomes non-conductive, the contact 6 closes, and a failure signal 10 is sent to the outside (failure signal ON). Even when contact f1 closes due to melting of fuse 5, or when failure signal 8 is input to each circuit unit, relay 5 becomes conductive, contact 5 opens, and as a result, contact 6 becomes conductive. Closed, a failure signal 10 is sent to the outside.

On the other hand, when the power supply control signal 9 is ON, the relay 1 becomes conductive and the contact 1 opens, supplying 7.7 A of power to the inside of the device.
, 7B to the corresponding circuit unit is cut off.

[Problem to be solved by the invention]

In this conventional configuration, when the power supply control signal 9 is turned ON, the common contact 1 is opened and the power supply from the power supplies 7.7A and 7B to the corresponding circuit units is cut off, but at the same time, the contact 2 is opened. Since 4 is also opened at ~, there is a problem in that a malfunction occurs in which a failure signal is output to the outside even though no failure has occurred.

This invention was made to solve the above problem.
It is an object of the present invention to provide a power supply circuit in a device that is more reliable than the conventional ones and does not generate fault signals by mistake.

[Means to solve the problem]

In order to achieve the above object, the present invention has the following objectives:
This configuration includes a contact that shorts the AND circuit that is sometimes formed by the contacts of the failure detection relay, and a capacitor that is connected in parallel to the failure signal output relay.

[Effect]

In this invention, when the power control signal is turned ON, the relay K
l becomes conductive, the common contact opens, and each contact of the fault detection relay also opens, but the short circuit contact closes, so the state of the fault signal output relay does not change, and a fault signal is erroneously created and sent to the outside. It will not be sent out.

〔Example〕

An embodiment of the present invention will be described below with reference to the drawings.

In FIG. 1, kla and klb are 1 contacts in the relay, and contact klb is turned OFF when contact 1 is ON, and is connected in parallel to an AND circuit formed by contacts 2 to 5. 11 is a capacitor, which is connected in parallel to the relay 6. The other configurations are the same as those in FIG.

In this configuration, when the power supply control signal 9 is OFF, that is, when the relay 1 is in a non-conducting state, the contact klA is closed, the contact IB is open, and the conventional operation is performed.

When power control signal 9 turns ON, relay 1 becomes conductive, contact kla opens, and contacts 2 to 4 also open, but contact klb closes, so relay 6 maintains conduction. , the failure signal 10 is never sent to the outside.

When the power supply control signal 9 turns OFF, the contact klb opens, but the contact kla closes, so the contacts 2 to 4 close. At this time, the timing at which contacts 2 to 4 close is slightly delayed from the timing at which contact kla closes, so
In order to prevent the relay 6 from instantaneously becoming non-conductive and closing the contacts 6, a capacitor 11 is provided to delay the operation of the relay 6.

FIG. 2 shows another embodiment of the invention. In the figure, 12 is connected to a relay 7 in parallel with 1, and its contacts 7 are connected in parallel to a series circuit of 2 to 5 contacts. The other configurations are the same as those shown in FIG.

Relays 1 and 7 have the same operating speed, and the return time of relay Kl is sufficiently faster than the return time of relay 7. In addition, the operation time of Relays 2 to K4 is selected to be sufficiently faster than that of Relay 1 and Kl. That is, (Kl return time) + (3 to K2.
K4 operating time) Kuni7 return time...
(Each relay is selected so that the following relationship holds true.

Therefore, when the power supply control signal 9 changes from ON to OFF, there is no difference between the time for the contact 7 to transition from closed to open and the time for the contact 2 to 4 to transition from open to closed. Therefore, the relay 6 will not become non-conductive (and erroneous generation of a fault signal will be prevented).

〔Effect of the invention〕

As explained above, this invention turns on/off the internal power supply.
By providing a contact that shorts the AND circuit formed by the contact of the failure detection relay when the common contact is OFF,
A failure signal is not erroneously sent to the outside during the OFF state, and reliability can be improved compared to the conventional case.

[Brief explanation of the drawing]

FIG. 1 is a circuit diagram showing an embodiment of the present invention, FIG. 2 is a circuit diagram showing another embodiment of the invention, and FIG. 3 is a circuit diagram showing a conventional example of a power supply circuit in the device. In the figure, 1 - external power input, 4 - timer control section, 7
．． 7A, 713-internal power supply, kl, kla common contact, K
2 to 5-fault detection relay, K6 fault signal output relay,
klb, k7 - short-circuit contact. In addition, in the figures, the same reference numerals indicate the same or corresponding parts.

Claims (1)

[Claims] (1) An internal power supply that supplies power to each circuit unit in the device using power introduced from an external power supply through a common contact, a failure detection relay that detects the OFF state of the common contact or a failure of each internal power supply, and a failure An AND circuit created by the contacts of the detection relay, and a fault signal output relay connected to an external power source through the AND circuit, and the common switch is opened and closed by an ON/OFF power supply control signal, and the common switch is turned off when the common contact is turned OFF. A power supply circuit in a device, characterized in that it has a short-circuiting contact that sometimes shorts the AND circuit.