JPH04236577A - Protecting device for high voltage generating circuit - Google Patents

Abstract

PURPOSE:To prevent production of smoke and fire of a flyback transformer generating a high voltage. CONSTITUTION:A temperature fuse 10 provided in a case (insulating material) of a flyback transformer and a temperature protector 11 detecting the state of the temperature fuse 10 are provided in the protection device and when the temperature fuse 10 is blown, its fault detection signal is inputted to an X-ray protector terminal of a horizontal oscillation IC section 2 via an OR circuit 12 to stop the oscillation of the horizontal oscillation IC section 2 thereby stopping the production of a high voltage of the flyback transformer.

Description

[Detailed description of the invention]

0001

[Field of Industrial Application] This invention relates to a protection device for a high voltage generation circuit used in a television picture tube, and more specifically to a high voltage generation circuit for preventing smoke and ignition caused by a flyback transformer (hereinafter referred to as FBT). This invention relates to circuit protection devices.

0002

[Conventional Example] Conventionally, this type of high voltage generation circuit was constructed as shown in Fig. 3, for example.
1 is an FBT, 2 is a horizontal oscillation IC section that oscillates a drive pulse for the FBT 1, and 3 is a drive circuit for driving the FBT 1.

The drive circuit 3 is composed of a transistor 4 for amplifying the current of the oscillation pulse signal, a horizontal drive transformer 5 and a horizontal output transistor 6 for driving the FBT 1 with the amplified pulse signal.

[0004] Further, an overcurrent protector 7 is provided on the primary side of the FBT 1, and an overvoltage protector 8 is provided on the secondary side of the FBT1. It also has a function to detect overvoltage abnormalities. Furthermore, the horizontal oscillation IC section 2 is equipped with an X-ray protector for protecting X-rays such as a picture tube that utilizes the high voltage generated by the high voltage generation circuit, and includes an overcurrent protector 7 or an overvoltage protector 8.
When an abnormality detection signal is input through the OR circuit 9, pulse generation is stopped to prevent the above-mentioned overcurrent and overvoltage.

[0005]

[Problems to be Solved by the Invention] Incidentally, the FBT1 used in the above-mentioned high voltage generation circuit can be made smaller by using a ferrite for the magnetic core and molding with resin glass (case) as an insulating member. etc. may cause smoke and fire. That is, due to the internal heat generation of the FBT 1, for example, the resin gasifies and the case ruptures. Furthermore, in the worst case, a fire may occur due to the discharge of the winding layer short circuit.

However, in the above-mentioned protection device for the high voltage generating circuit, the protection operation is not performed due to a temperature rise inside the FBT 1, and there is no countermeasure against internal heat generation.

The present invention was made in view of the above problems, and its purpose is to monitor the internal temperature of the FBT so that even when the internal temperature rises, a protective operation is activated to prevent smoke and ignition. An object of the present invention is to provide a protection device for a high voltage generation circuit.

[0008]

[Means for Solving the Problems] In order to achieve the above object, the present invention detects an abnormality in a high voltage generation circuit, and transmits this abnormality detection signal to an X The protection device for the high voltage generation circuit that inputs to the wire protector terminal and stops the oscillation of the drive pulse detects the thermal fuses installed in the case of the flyback transformer and the status of these thermal fuses. The present invention further comprises a temperature protector that detects heat generation within the horizontal oscillation IC section and outputs this detection signal to the X-ray protector terminal of the horizontal oscillation IC section.

[0009]

[Operation] With the above configuration, when heat is generated in the flyback transformer (FBT) and any one of the plurality of thermal fuses is blown, the temperature protector outputs a detection signal of the heat generation, This detection signal is input to the X-ray terminal of the horizontal oscillation IC section. Then, similar to protection against overcurrent and overvoltage of the FBT, the oscillation of the horizontal oscillation IC section is stopped, that is, the output of the FBT drive pulse is stopped. Therefore, since the heat generation of the FBT is suppressed, smoke and ignition will not occur.

0010

Embodiments Hereinafter, embodiments of the present invention will be explained based on FIGS. 1 and 2. In addition, in the figure, the same parts as in FIG. 3 are given the same reference numerals, and redundant explanation will be omitted.

In FIG. 1, the protection device for this high voltage generation circuit includes a case (
A logical sum of a plurality of thermal fuses 10 provided in an insulating member (resin), a temperature protector 11 that detects abnormalities in these thermal fuses 10, and abnormality detection signals from the temperature protector 11, overcurrent protector 7, and overvoltage protector 8. and an OR circuit 12 which outputs an abnormality detection signal to the X-ray protector terminal of the horizontal oscillation IC section 2 when any abnormality occurs.

A plurality of thermal fuses 10 are arranged at predetermined locations within the case of the FBT 1, for example around the windings.

Further, as shown in FIG. 2, a plurality of thermal fuses 10 are connected in series, and the temperature protector 11 is turned on when the thermal fuses 10 are normal and turned off when abnormal. (signal of 0V) and an off signal (signal of +12V) to the horizontal oscillation IC section 2 via the OR circuit 12.

The operation of the protection device for the high voltage generating circuit having the above structure will be explained. First, it is assumed that a pulse is generated from the horizontal oscillation IC section 2, the FBT 1 is driven by this pulse, and a flight back pulse is generated.

[0015] When the inside of the case of the FBT 1 generates heat, the thermal fuse 10 closest to the location of the heat is blown by the heat. Then, the base potential of the pnp transistor 13a of the transistor circuit 13 becomes approximately 0V, and the pnp transistor 13a is turned on. The emitter of the pnp transistor 13a becomes approximately 12V, that is, the 12V becomes the abnormality detection signal from the temperature protector 11. Since this 12V abnormality detection signal is input to the X protector terminal of the horizontal oscillation IC section 2 via the OR circuit 12, the horizontal oscillation IC section 2 stops oscillating.

[0016] As a result, the FBT 1 is no longer driven by the drive circuit 3, and the heat generated within the case of the FBT 1 can be suppressed, thereby preventing heat generation and ignition.

[0017]

Effects of the Invention As explained above, according to the high voltage generation circuit protection device of the present invention, the flyback transformer (F
In addition to monitoring the thermal fuses installed at predetermined locations within the case (resin) of the BT) and the status of the thermal fuses,
FBT sends an abnormality detection signal when the thermal fuse is blown.
Since it is equipped with an electronic circuit (temperature protector) that outputs the drive pulse to the X-ray protector terminal of the horizontal oscillation IC section, the oscillation of the drive pulse can be stopped when heat is generated inside the FBT case. This has the effect of preventing heat generation and ignition.

[Brief explanation of the drawing]

[Fig. 1] A schematic circuit diagram of a protection device for a high voltage generation circuit showing an embodiment of the present invention.

[Figure 2] Specific circuit diagram of the protection device for the high voltage generation circuit shown in Figure 1

[Figure 3] Schematic circuit diagram of a conventional high voltage generation circuit protection device

[Explanation of symbols]

1 Flyback transformer (FBT) 2 Horizontal oscillation IC section 3 Drive circuit 7 Overcurrent protector 8 Overvoltage protector 10 Temperature fuse 11 Temperature protector 12 OR circuit 13 Transistor circuit 13a PNP transistor

Claims (2)

[Claims] [Claim 1] A flyback transformer driven by pulses generated by horizontal oscillation means for protecting X-rays in picture tubes, etc.
It is equipped with an overcurrent protector that detects the secondary side current and detects an abnormality in the current, and an overvoltage protector that detects the secondary side voltage of the flyback transformer and detects an abnormality in the voltage. In the protection device for the high voltage generation circuit, which stops the oscillation of the horizontal oscillation means for X-ray protection in the event of an abnormality, and prevents overcurrent or overvoltage, the thermal fuse provided in the case of the flyback transformer and its temperature and a temperature protector that detects the state of the fuse, detects an abnormality in the flyback transformer, and outputs this detection signal to the horizontal oscillation means,
A protection device for a high voltage generation circuit, characterized in that when any one of the plurality of thermal fuses becomes abnormal, oscillation of the horizontal oscillation means is stopped. 2. A plurality of the thermal fuses are arranged at predetermined locations in the case, and the thermal fuses are connected in series, and when an abnormality occurs in at least one of the thermal fuses, the horizontal oscillation means stops oscillating. 2. The high voltage generating circuit protection device according to claim 1, wherein the high voltage generating circuit is stopped.