JPH04105559A - Abnormal voltage protecting circuit - Google Patents

Abstract

PURPOSE:To prevent the fear of a fire by the abnormal heat occurrence in a faulty element or the fear of electric shock by leakage by detecting output voltage abnormality, and shorting the input power source on reception of its abnormality signal, and letting overcurrent flow to a protective fuse so as to focedly blow the fuse. CONSTITUTION:An abnormal voltage detection circuit 9 issues an abnormality signal 13 when the output of main power source circuit deviates greatly from the voltage set value and abnormality occurs in output voltage. An abnormality signal transmission means 11 transmits the abnormality signal 13 to a short circuit means 1. The short circuit 13, which has received the abnormality signal 13, shorts input voltage 2 so as to let an overcurrent flow to a fuse 4 and focedly blows a fuse. Therefore, even if the cause of its abnormal voltage is the fault of an element, at the point of time when abnormality occurs in the output voltage, it cuts the input voltage source of a power source circuit off the root, so the current is not applied to the power source circuit beyond it, and the dangers such as a fire, an electric shock, etc., can be avoided surely.

Description

[Detailed description of the invention] [Industrial application field] The present invention relates to an abnormal voltage protection circuit.

[Conventional technology]

Conventionally, when this type of protection circuit detects abnormal voltage on the exit side, it transmits the signal to the control circuit, and the control circuit either limits the detection power to prevent the voltage from rising any further, or stops the power supply by stopping transmission, etc. By stopping the operation, protection has been provided against fires, electric shocks, etc. when an abnormality occurs in the power supply circuit.

[Problem to be solved by the invention]

In the conventional abnormal voltage protection circuit described above, the control circuit limits the output, stops operation, etc., so abnormal voltage is not output to the output terminal, but the power supply circuit is continuously energized by the input voltage source. Therefore, if a malfunction occurs in a certain element and an abnormality occurs in the output voltage, voltage continues to be applied to the malfunctioning element, and there remains a risk of fire due to abnormal heat generation in that element or electric shock due to electrical leakage. There are drawbacks.

[Means to solve the problem]

The abnormal voltage protection circuit of the present invention includes: an abnormal voltage detection circuit that detects when an output voltage is abnormal and outputs an abnormal signal; an abnormal signal transmission means that transmits the abnormal signal to a short circuit means; The fuse is configured to include short-circuiting means for forcibly blowing out the fuse by short-circuiting the input power source and causing an excessive current to flow through the protective fuse.

〔Example〕

Next, the present invention will be explained with reference to the drawings.

FIG. 1 is a block diagram of one embodiment of the present invention.

The abnormal voltage detection circuit 9 generates an abnormality signal 13 when the output voltage of the power supply circuit deviates significantly from the voltage setting value and an abnormality occurs in the output voltage.

The abnormality signal transmission means 11 transmits the abnormality signal 13 to the shorting means 1. Upon receiving the abnormal signal 13, the short-circuiting means 1 short-circuits the input voltage 2 so that an excessive current flows through the fuse 4, forcibly blows the fuse, cuts off the input voltage of the power supply circuit, protects the key circuit, and prevents fire, electric shock, etc. Avoid danger.

〔Effect of the invention〕

As explained above, the present invention forcibly blows out the fuse when an abnormality is detected in the output voltage. Since the input voltage source of the power supply circuit is disconnected from the source, the power supply circuit is no longer energized and the danger of fire, electric shock, etc. can be reliably avoided.

[Brief explanation of the drawing]

FIG. 1 is a block diagram showing one embodiment of the present invention. DESCRIPTION OF SYMBOLS 1... Short-circuiting means, 2... Input AC power supply, 3... Power switch, 4... Fuse, 5... Noise filter, 6... Rectifier Gollidge, 7... Control circuit, 8・・・
・Error amplifier, 9... Abnormal voltage detection circuit, 10.
... Control signal transmission means, 11... Abnormal signal transmission means,
12... Control signal, 13... Abnormal signal.

Claims (1)

[Claims] an abnormal voltage detection circuit that detects when an output voltage is abnormal and outputs an abnormal signal; an abnormal signal transmitting means that transmits the abnormal signal to a shorting means; and a protective fuse that short-circuits the input power supply upon receiving the abnormal signal. 1. An abnormal voltage protection circuit comprising short-circuiting means for forcibly blowing a fuse by flowing an excessive current.