JP2000350051A - High voltage discharge protection circuit - Google Patents

Abstract

(57) [Problem] To provide a high-voltage discharge protection circuit that prevents circuit breakdown, component deterioration, and high-voltage shutdown malfunction at abnormal discharge in a cathode ray tube. A high-voltage discharge protection circuit according to the present invention has a peak of an abnormal pulse at least between a point of occurrence of an abnormal pulse due to discharge in a cathode ray tube as a picture tube of a display device and a circuit component to be protected. A delay circuit for delaying the output; a reset unit for detecting the abnormal pulse between the delay circuit and the cathode-ray tube and resetting the display device; Is longer than the reset time.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a high-voltage discharge protection circuit for a display device using a picture tube, which prevents circuit breakdown, component deterioration, and high-voltage shutdown malfunction at abnormal discharge in the picture tube.

[0002]

2. Description of the Related Art A cathode ray tube (Cathode Ray Tube) is used as a picture tube for a display device. A high voltage, for example, a high voltage of several tens of kV to several tens of kV is applied to the cathode ray tube to display an image.
This high voltage has an individual usable range depending on the type of the cathode ray tube, and a designer can freely set the high voltage within the range. The cathode ray tube is composed of components such as a shadow mask, a phosphor surface, and an electron gun, and an optimal driving voltage is applied to each component. An electron beam emitted from the electron gun hits the phosphor surface due to the balance of the driving voltage, and a desired image is displayed.

A driving voltage is applied between the components of the cathode ray tube. For example, fine particles and gas are generated and exist between the components of the cathode ray tube, or the components of the cathode ray tube are The accumulation of electric charges may cause a discharge phenomenon between the components. This phenomenon is called the tube discharge phenomenon, and it is an important item in the design to protect the display device from transient phenomena when this phenomenon occurs, that is, abnormal voltage and abnormal pulse as abnormal pulse generated by tube discharge. I have.

[0004] In the above-described tube discharge phenomenon, two types of discharge pulses can be generated. One is that a discharge from a high voltage in the cathode ray tube directly discharges to an electrode in the cathode ray tube such as a focus, and the discharge phenomenon is applied to the circuit as a pulse. The other is that a relatively low-energy discharge is generated between the electrodes inside the cathode ray tube, which causes a high pressure to jump up,
In some cases, the high-voltage bounce is applied to the circuit as a pulse.

Conventionally, when the abnormal discharge occurs in the cathode ray tube, a method of detecting the abnormal voltage and performing a reset operation to prevent a malfunction of the circuit, or a method of filtering an abnormal discharge pulse by using a surge absorber or the like is known. Mainly used. For example, a high-voltage discharge protection circuit that filters an abnormal discharge pulse with a surge absorber or the like is shown in FIG.
As shown in FIG. 11, when an abnormal discharge occurs in the tube of the cathode ray tube 1, a high voltage pulse is removed by a surge absorber 21, and a small pulse is clamped by diodes 22a and 22b, a Zener diode 23, etc. to protect the circuit component 2. It is configured to be. In the high-voltage discharge protection circuit shown in FIG. 10, a pulse higher than the power supply voltage is clamped to the power supply voltage by the diode 22a, and a pulse lower than the ground is clamped to the ground by the diode 22b. Further, in the high-voltage discharge protection circuit shown in FIG. 11, the Zener diode 23 clamps a pulse of a predetermined value or more to a predetermined voltage and a pulse below ground to the ground.

According to the above-described method, an abnormal discharge pulse is removed, or a power supply reset is performed before an abnormal discharge pulse due to an in-tube discharge is applied to a circuit to cause a circuit malfunction, thereby preventing a circuit malfunction. A configuration has been realized in which an abnormal voltage is prevented from being applied to components such as transistors, and the occurrence of destruction and deterioration of components is prevented.

[0007]

However, in recent years, as cathode ray tubes have become larger in size, the high voltage used in cathode ray tubes has been increasing for the purpose of improving focus performance and increasing brightness. The voltage waveform is steeper and higher in voltage than the conventional one, and the discharge energy tends to increase.

As a result, in the conventional detection method, the response performance is insufficient, so that the occurrence of the circuit malfunction cannot be prevented, the parts are broken down and deteriorated, and the high voltage is further increased. .1 mR / h), and the high-voltage shutdown operating point is lowered to secure the margin, thereby increasing the occurrence rate of high-voltage shutdown malfunction.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a high-voltage discharge protection circuit which prevents circuit breakdown, component deterioration, and high-voltage shutdown malfunction at abnormal discharge in a picture tube.

[0010]

SUMMARY OF THE INVENTION A high voltage discharge protection circuit according to the present invention delays at least the peak of an abnormal pulse between the point of occurrence of the abnormal pulse due to the discharge in the picture tube and the circuit to be protected. A delay circuit for detecting the abnormal pulse between the delay circuit and the picture tube and resetting the display device, and setting a delay time of the delay circuit to a reset time of the display device. It is longer.

According to the present invention, it is possible to obtain a high-voltage discharge protection circuit that prevents circuit destruction, deterioration of components, and high-voltage shutdown malfunction during abnormal discharge in a picture tube.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The invention according to claim 1 of the present invention is directed to a method for detecting a peak of an abnormal pulse between a point of occurrence of an abnormal pulse due to a discharge in a picture tube of a display device and a circuit to be protected. A delay circuit that delays and outputs at least the delay circuit, and a reset unit that detects the abnormal pulse between the delay circuit and the picture tube and resets the display device. This is a high-voltage discharge protection circuit that is longer than the reset time of the device, and prevents the occurrence of circuit malfunction, component destruction and deterioration due to abnormal pulses when a discharge in the tube occurs in the display device where the high voltage used in the picture tube has risen more than before. it can.

According to a second aspect of the present invention, a reset circuit includes: a comparison circuit for comparing a waveform voltage of an abnormal pulse with a reference value and generating a control signal when an abnormality is detected; and a control signal from the comparison circuit. 2. A high-voltage discharge protection circuit according to claim 1, wherein said high-voltage discharge protection circuit comprises a reset circuit for resetting the display device upon receiving the pulse. Circuit malfunction, component destruction and deterioration can be prevented.

According to a third aspect of the present invention, the high voltage discharge protection circuit according to the second aspect is a high voltage discharge protection circuit provided in an X-ray detection voltage section from a flyback transformer. Erroneous operation of the high-voltage shutdown due to the jump of the X-ray detection voltage due to the above can be prevented. According to a fourth aspect of the present invention, the high-voltage discharge protection circuit according to the second aspect is a high-voltage discharge protection circuit provided in a focus voltage generating circuit. It is possible to prevent components from being deteriorated or destroyed due to superimposition of an abnormal pulse on the voltage.

According to a fifth aspect of the present invention, the high voltage discharge protection circuit according to the second aspect is a high voltage discharge protection circuit provided in at least one of a driving voltage generation circuit for a cathode, a heater, and a screen. In this case, it is possible to prevent circuit breakdown and deterioration due to an abnormal pulse and component deterioration and destruction due to superposition of the abnormal pulse on the drive voltage.

According to a sixth aspect of the present invention, a comparison circuit includes: a reference voltage generation circuit for generating a reference voltage; and a control signal when an abnormality is detected by comparing the reference voltage with a waveform voltage of an abnormal pulse. A high voltage discharge protection circuit according to claim 2, comprising a voltage comparison circuit that generates an abnormal voltage and an abnormal pulse input when a discharge in the tube that does not occur in normal operation is detected, and a control signal is output. A configuration capable of performing the above can be realized.

According to a seventh aspect of the present invention, a comparison circuit controls a storage circuit for storing a waveform of an abnormal pulse and compares and recognizes the stored waveform of the abnormal pulse with an input pulse to detect an abnormality. 3. A high voltage discharge protection circuit according to claim 2, comprising a pattern recognition circuit that generates a signal, and detects only an input of an abnormal voltage and an abnormal pulse when a discharge in the tube occurs, and outputs a control signal. A possible configuration can be realized, and a configuration for preventing a reset malfunction when a pulse is generated for some reason other than the discharge in the tube can be realized.

According to an eighth aspect of the present invention, the comparison circuit includes: an A / D converter for converting an input pulse from analog to digital; a storage circuit for storing a waveform of an abnormal pulse; 3. The high-voltage discharge protection circuit according to claim 2, comprising a digital data comparison circuit that generates a control signal when an abnormality is detected by comparing and recognizing a waveform and an input pulse, and a normal operating voltage at a mounting position of the comparison circuit. Irrespective of the variation of the display device, it is possible to realize a configuration in which an operation margin can always be secured at a fixed percentage, a reset malfunction caused by a reduced margin by the display device, or a large margin, and a reset operation does not occur. It is possible to eliminate the problem caused by variations such as destruction and deterioration of the circuit.

Hereinafter, the high-voltage discharge protection circuit of the present invention will be described based on specific embodiments. (Embodiment 1) A high-voltage discharge protection circuit according to Embodiment 1 of the present invention, as shown in FIG. 1, detects an abnormal pulse (abnormal voltage / abnormal pulse) due to discharge in a cathode ray tube 1 as a picture tube of a display device. A delay circuit 3 is provided between the point of occurrence and the circuit component 2 as a target circuit to be protected, the delay circuit 3 outputting at least a delay of the peak of the abnormal pulse and outputting the abnormal pulse between the delay circuit 3 and the CRT 1. And reset means for resetting the display device by detecting the delay time, and making the delay time of the delay circuit 3 longer than the reset time of the display device.

The reset means, as shown in FIG. 1, compares the waveform voltage of the abnormal pulse with a reference value and generates a control signal a when detecting an abnormality, and receives the control signal a from the comparative circuit 4. And a reset circuit 5 for resetting the display device. As the delay circuit 3, for example, a delay line as shown in FIG. 2A, an RC filter composed of a resistor (R) and a capacitor (C) as shown in FIG. As shown in (c), a coil (L), a resistor (R), and a capacitor (C)
And the like. The delay line outputs the input pulse after delaying the input pulse by time t, as shown in FIG. The RC filter is
As shown in FIG. 2 (e), at the same time as the pulse input, the pulse output whose rising gradient is made gentler from the pulse input is started, and the peak of the input pulse is output with a delay of time t. In the LRC filter, as shown in FIG. 2 (f), at the same time as the pulse input, the pulse output whose rising gradient is made gentler from the pulse input is started, and the peak of the input pulse is delayed by time t and attenuated. Output. This time t is a delay time, which is longer than the reset time of the display device. Here, it is assumed that the delay line shown in FIG.

The circuit component 2 is, for example, a component such as a transistor or an IC constituting a display device, and is a semiconductor such as a high-voltage drive IC (integrated circuit), a video drive HIC (hybrid integrated circuit), or a power supply stabilizing IC. I
There is C. Here, the first embodiment is connected to a power supply line or a ground line connecting the CRT 1 and the circuit component 2.
The operation when the high-voltage discharge protection circuit is provided will be described.

For example, when an internal discharge occurs in the CRT 1 and an abnormal voltage / pulse is output from the CRT 1, the abnormal voltage / pulse is input to the delay circuit 3. At the same time, the comparison circuit 4 compares the output from the cathode-ray tube 1 with the output during normal operation, and when it detects that the output from the cathode-ray tube 1 is an abnormal voltage generated by discharge in the tube, sends a control signal a to the reset circuit 5. Output.

When receiving the control signal a, the reset circuit 5 outputs a reset signal b to a circuit (hereinafter abbreviated as a microcomputer) 6 having a reset function such as a microcomputer and power supply. When receiving the reset signal b, the microcomputer 6 resets the operation of the display device. Since the delay time t of the delay circuit 3 is longer than the reset time of the display device, the abnormal voltage / pulse input to the delay circuit 3 reaches the circuit component 2 after the reset operation of the display device ends.

With such a configuration, the abnormal voltage and the abnormal pulse from the cathode ray tube 1 can reach the circuit component 2 after the reset operation of the display device is completed. Even if the abnormal voltage / pulse reaches the circuit component 2, the circuit does not malfunction due to the abnormal voltage / pulse or the abnormal voltage / pulse is not superimposed on the operating voltage.
It is possible to prevent a circuit malfunction due to an abnormal voltage and an abnormal pulse from the cathode-ray tube 1 and component deterioration and destruction caused by the superimposition of the abnormal voltage and the abnormal pulse on the operating voltage.

In the first embodiment, the delay circuit is a delay line. However, even if an RC filter is used, the same effect as described above is obtained. The pulse can be attenuated. (Embodiment 2) As shown in FIG. 3, a high-voltage discharge protection circuit according to a second embodiment of the present invention is different from the high-voltage discharge protection circuit according to the first embodiment in that a flyback transformer (hereinafter, referred to as an FBT).
Abbreviated. ) Is provided at an X-ray detection terminal 7a as an X-ray detection voltage section from 7.

When an in-tube discharge occurs in the CRT 1, a high-voltage output (Extremely High
gh Tension: Abbreviated as EHT. ) A phenomenon occurs in which the high voltage output from 7b jumps. At this time, a jump also occurs in the X-ray detection voltage. The comparison circuit 4 is shown in FIG.
As shown in FIG. 3, the jump of the X-ray detection voltage at the X-ray detection terminal 7a is detected. Here, it is assumed that the RC filter shown in FIG. 2 is used for the delay circuit 3.

The X-ray protection circuit 8 detects an X-ray detection voltage as shown in FIG. 4 so that the high-voltage generation circuit such as the FBT 7 does not generate X-rays. As described above, the high-voltage shutdown for stopping the operation of the FBT 7 by controlling the drive pulse circuit for operating the FBT 7 is performed. In the FBT 7, 7c, 7f
Is a capacitor, 7d is a diode, and 7e is a resistor.

Here, the operation of the high voltage discharge protection circuit will be described. For example, when a jump in the X-ray detection voltage occurs due to the generation of discharge in the cathode ray tube 1, the jump in the X-ray detection voltage is input to the delay circuit 3. At the same time, the comparison circuit 4 detects the jump of the X-ray detection voltage and outputs a control signal a to the reset circuit 5. When receiving the control signal a, the reset circuit 5 outputs a reset signal b to a circuit (hereinafter abbreviated as a microcomputer) 6 having a reset function such as a microcomputer and a power supply. When receiving the reset signal b, the microcomputer 6 resets the operation of the display device.

The delay time t of the delay circuit 3 is longer than the reset time of the display device.
Before reaching the line protection circuit 8, the operation of the FBT 7 is initialized to stop the high voltage jump. Specifically, the X-ray detection voltage waveform shown by a solid line in FIG. 4 input to the comparison circuit 4 is such that a discharge in the tube occurs at the point P1 and the jump is detected by the comparison circuit 4 between the points P1 and P2. Assuming that the reset operation is completed at the point P3, the high voltage jump stops after the point P3. An X-ray detection voltage waveform delayed by the time t by the delay circuit 3 shown by a two-dot chain line in FIG. 4 is input to the X-ray protection circuit 8, and this X-ray detection voltage is a voltage for executing a high-voltage shutdown operation. , The X-ray protection circuit 8 does not execute the high-voltage shutdown operation due to the jump.
The dashed line in FIG. 4 is a conventional X-ray detection voltage waveform having a jump, and a high-pressure shutdown operation due to the jump occurs at a point P4.

With this configuration, in the conventional example, X
Since only a zener diode is provided in series between the line protection circuit 8 and the X-ray detection terminal 7a, the occurrence rate of the high-voltage shutdown malfunction has increased due to the jump of the X-ray detection voltage. In FIG. 2, before the jump of the X-ray detection voltage reaches the X-ray protection circuit 8, F
The operation of the BT 7 can be initialized to stop the high voltage jump, and the X-ray protection circuit 8 can only reach the X-ray detection voltage jump that does not cause the high voltage shutdown at worst. A high voltage shutdown malfunction due to a voltage jump can be prevented.

In the second embodiment, delay circuit 3 is connected to RC
Although the filter is used, when the LRC filter is used, the jump of the X-ray detection voltage to the X-ray protection circuit 8 can be further attenuated. Of the X-ray detection voltage is not output. (Embodiment 3) As shown in FIG. 5, a high-voltage discharge protection circuit according to a third embodiment of the present invention has the above-described high-voltage discharge protection circuit according to the first embodiment provided in a focus voltage generation circuit. .

The characteristics of the abnormal voltage and the abnormal pulse when the discharge in the tube occurs in the focus block are the magnitude of the energy and the steepness of the pulse. When the abnormal voltage / pulse is applied to the circuit component 2, component destruction / deterioration occurs. Here, the operation of the high voltage discharge protection circuit will be described. For example, when an in-tube discharge occurs in the focus block, the abnormal voltage / pulse is input to the delay circuit 3. At the same time, the comparison circuit 4 compares the abnormal voltage and the abnormal pulse due to the discharge in the tube in the focus block with the output during the normal operation, and outputs a control signal a to the reset circuit 5 when it detects that the voltage is abnormal.

When receiving the control signal a, the reset circuit 5 outputs a reset signal b to a circuit (hereinafter abbreviated as a microcomputer) 6 having a reset function such as a microcomputer and power supply. When receiving the reset signal b, the microcomputer 6 resets the operation of the display device. Since the delay time of the delay circuit 3 is longer than the reset time of the display device, after the reset operation of the display device is completed, the abnormal voltage / pulse input to the delay circuit 3 is applied to the circuit component 2.
To reach.

With such a configuration, in the conventional protection circuit system, a gap such as the surge absorber 24 is provided on the circuit, and when a voltage higher than a predetermined voltage is applied, discharge occurs in the gap and the voltage is reduced. The circuit component 2 was protected by lowering it and further providing a voltage limiting element such as a Zener diode in front of the circuit component 2. However, in a display device in which the high voltage is increasing, the discharge energy is proportional to the high voltage. In contrast, in recent display devices in which high-density mounting is indispensable because a more compact design is required, the protective element cannot sufficiently limit the voltage. There is a problem that an abnormal pulse is applied to the circuit component 2 to increase the rate of occurrence of destruction / deterioration. The abnormal voltage / pulse due to the internal discharge can reach the circuit component 2 after the reset operation of the display device is completed, and the abnormal voltage / abnormal pulse reaches the circuit component 2 after the reset operation of the display device is completed. Also, abnormal voltage and abnormal pulse due to abnormal voltage and abnormal pulse and abnormal voltage and abnormal pulse are not superimposed on the drive voltage. It is possible to prevent the withstand voltage of the circuit component 2 from being superimposed due to the superposition, and prevent the component from being deteriorated or destroyed.

In the third embodiment, as shown in FIG. 5, two focus outputs A and B are used. However, one or more focus outputs may be used. (Embodiment 4) A high-voltage discharge protection circuit according to a fourth embodiment of the present invention is different from the high-voltage discharge protection circuit according to the third embodiment in that a driving voltage generation circuit for a cathode, a heater, and a screen, which are components of the CRT 1, is provided. Provided in an electrode drive circuit such as a cathode, a heater, and a screen.

The electrode is an electrode driven at a lower voltage than the focus block, and is provided at a position farther than the anode to which a high voltage is applied, as compared with the focus electrode. As a result, FIG. 6B, which is different from the abnormal voltage / abnormal pulse in the focus block shown in FIG. Thus, FIG.
The abnormal voltage / abnormal pulse shown in FIG. 6B has a smaller energy and a smaller pulse steepness than the abnormal voltage / abnormal pulse in the focus block shown in FIG. If the determination method is the same as that described above, a circuit malfunction may occur.

Therefore, in the fourth embodiment, the delay circuit 3 and the comparison circuit 4 are configured by selecting components that can correspond to the pulse shown in FIG. 6B. In the high-voltage discharge protection circuit according to the fourth embodiment, an abnormal voltage and an abnormal pulse due to a discharge in a tube generated at electrodes such as a cathode, a heater, and a screen are delayed by a delay circuit 3, and simultaneously, a cathode and a heater are compared by a comparison circuit 4. The control signal a is output to the reset circuit 5 by detecting an abnormal voltage and an abnormal pulse due to a discharge inside the tube at an electrode such as a screen.
The reset circuit 5 receives the control signal a and outputs a reset signal b to the microcomputer 6 to reset the operation of the display device. The reset operation stops the circuit operation before an abnormal voltage / abnormal pulse due to discharge in the tube reaches the circuit component 2 which is an electrode drive circuit such as a cathode, a heater, a screen, and the like.

With such a configuration, the reset operation causes an abnormal voltage / abnormal pulse due to discharge in the tube to reach the circuit component 2 which is an electrode drive circuit such as a cathode, a heater, a screen, etc., and destroys / degrades the circuit component 2 By stopping the circuit operation before the operation, the circuit breakdown / deterioration due to the malfunction due to the abnormal voltage / abnormal pulse and the abnormal voltage / abnormal pulse superimposed on the driving voltage may exceed the withstand voltage of the circuit component 2. Therefore, it is possible to prevent the parts from being deteriorated or broken.

(Embodiment 5) The high-voltage discharge protection circuit according to Embodiment 5 of the present invention is the same as the comparison circuit 4 of each of the above-described embodiments.
As shown in FIG. 7, in order to detect an abnormal voltage and an abnormal pulse when a discharge in the tube occurs, a reference voltage generating circuit 9 for generating a reference voltage is compared with the reference voltage and a waveform voltage of the abnormal pulse. It comprises a voltage comparison circuit 10 that generates a control signal a when an abnormality is detected.

The abnormal voltage and the abnormal pulse due to the discharge in the tube are as follows.
Since a voltage higher than the normal operation voltage is generated, the characteristic is used. When a voltage higher than the reference voltage generated by the reference voltage generation circuit 9 is input to the voltage comparison circuit 10, a control signal a as a detection signal is output. I do. The reference voltage can be freely set by a designer. With such a configuration, it is possible to realize a configuration capable of detecting an input of an abnormal voltage and an abnormal pulse at the time of occurrence of an in-tube discharge which does not occur in a normal operation and outputting the control signal a.

(Embodiment 6) The high voltage discharge protection circuit according to Embodiment 6 of the present invention is the same as the comparison circuit 4 of each of the above embodiments.
As shown in FIG. 8, in order to detect an abnormal voltage and an abnormal pulse at the time of occurrence of discharge in the tube, a storage circuit 11 for storing a waveform of the abnormal pulse is compared with a stored waveform of the abnormal pulse and an input pulse. It comprises a pattern recognition circuit 12 which generates a control signal a upon recognition and detection of an abnormality.

The abnormal voltage / abnormal pulse waveform due to the discharge inside the tube is stored in the storage circuit 11 by utilizing the characteristic that the waveform of the abnormal voltage / pulse due to the discharge inside the tube is different from the waveform during normal operation.
When the input signal has the same behavior as an abnormal voltage and an abnormal pulse due to the discharge in the tube in the pattern recognition circuit 12, it is recognized that the discharge in the tube has occurred, and a control signal a as a detection signal is output.

With such a configuration, it is possible to realize a configuration capable of detecting only the input of an abnormal voltage and an abnormal pulse when an in-tube discharge occurs and outputting the control signal a. It is possible to realize a configuration that prevents a reset malfunction in the event of occurrence. (Embodiment 7) The high-voltage discharge protection circuit according to Embodiment 7 of the present invention uses the comparison circuit 4 of each of the above-described embodiments to detect an abnormal voltage and an abnormal pulse at the time of occurrence of an in-tube discharge, as shown in FIG. A to convert input pulse from analog to digital to detect
A D / D converter 13, a storage circuit 14 for storing the waveform of the abnormal pulse, a digital data comparing circuit 15 for comparing and recognizing the stored waveform of the abnormal pulse with the input pulse, and generating a control signal a when detecting an abnormality. It consists of.

First, the input voltage during normal operation is converted into digital data by the A / D converter 13. A value obtained by multiplying the digital data by a predetermined operating voltage margin is stored in the storage circuit 14. The digital data comparison circuit 15 receives the reference voltage data including the margin from the storage circuit 14, compares the value with the output from the A / D converter 13, and outputs the data from the A / D converter 13. If the data is larger, it recognizes that an in-tube discharge has occurred, and outputs a control signal a as a detection signal.

With this configuration, it is possible to set a margin corresponding to the variation in input voltage between display devices. That is, the input voltage during normal operation is a value that fluctuates due to variations in component constants of each display device. In the method described in the fifth embodiment, the reference voltage is fixed, and thus the input voltage until the control signal a is generated. There is a possibility that a variation in the operation margin may occur and a reset malfunction may occur. However, according to the seventh embodiment, if the operation margin is specified as a percentage of the input voltage, a control signal is required for each display device. It is possible to adjust the input voltage at which a is output, thereby realizing a configuration in which the operation margin can always be secured at a constant percentage regardless of the variation of the normal operation voltage in the mounting portion of the comparison circuit 4. Reset operation that occurs due to a reduced margin due to the display device, or a large margin, reset operation does not occur, and the circuit breaks · It is possible to solve the problems caused by variations such as to deteriorate.

The circuit diagrams and structure diagrams used in the description of each of the above-described embodiments are merely examples. For example, there is no limitation on the internal structure of the FBT 7 or the number of output terminals and the like. The high voltage discharge protection circuit of the present invention can be applied to any high voltage generation circuit. It is also possible to insert some circuit or component before the input to the delay circuit 3 or the comparison circuit 4.
The comparison circuit 4 can be adjusted so that a desired effect can be obtained regardless of where it is provided between the circuit component 2 to be protected from an abnormal voltage and an abnormal pulse when an in-tube discharge occurs and an abnormal voltage and abnormal pulse generating point. It is possible.

The comparison circuit 4 includes an operational amplifier and a power supply I.
It can be easily realized with C, a regulator, a comparator, and the like.

[0048]

As described above, according to the high-voltage discharge protection circuit of the present invention, the circuit between the point of occurrence of the abnormal pulse due to the discharge in the picture tube of the display device and the circuit to be protected is provided.
A delay circuit that delays and outputs the peak of the abnormal pulse at least; a reset unit that detects the abnormal pulse between the delay circuit and the picture tube to reset the display device; Time,
By making the reset time longer than the reset time of the display device, it is possible to prevent the malfunction of the circuit, the destruction and deterioration of parts due to the abnormal voltage when the discharge in the tube occurs in the display device in which the high voltage used in the picture tube is higher than before.

When this high-voltage discharge protection circuit is specifically provided in an X-ray detection voltage section from a flyback transformer, a focus voltage generation circuit, or a drive voltage generation circuit such as a cathode, a heater, or a screen, the discharge in the tube is prevented. Erroneous operation of the high voltage shutdown caused by the jump of the X-ray detection voltage caused by the abnormal voltage can be prevented, and the deterioration and the destruction of the parts due to the abnormal pulse superimposed on the drive voltage can be prevented. be able to.

The comparison circuit of the high-voltage discharge protection circuit includes a reference voltage generation circuit for generating a reference voltage, a voltage comparison circuit for comparing the reference voltage with a waveform voltage of an abnormal pulse and generating a control signal when an abnormality is detected. In the case of the configuration described above, it is possible to realize a configuration capable of detecting the input of an abnormal voltage / abnormal pulse at the time of occurrence of an in-tube discharge that does not occur in normal operation and outputting a control signal.

The comparison circuit comprises a storage circuit for storing the waveform of the abnormal pulse, and a pattern recognition circuit for comparing and recognizing the stored waveform of the abnormal pulse with the input pulse and generating a control signal when an abnormality is detected. In such a case, it is possible to realize a configuration that can detect only the input of abnormal voltage and abnormal pulse at the time of occurrence of discharge in the tube and output a control signal. It is possible to realize a configuration for preventing such a situation.

The comparison circuit includes an A / D converter for converting an input pulse from analog to digital, a storage circuit for storing a waveform of an abnormal pulse, and comparing and recognizing the stored waveform of the abnormal pulse with an input pulse to determine an abnormality. When configured with a digital data comparison circuit that generates a control signal when detected,
Irrespective of the variation of the normal operating voltage in the mounting location of the comparison circuit, it is possible to realize a configuration in which the operation margin can always be secured at a constant percentage, and the reset device malfunction due to the reduced margin by the display device or the margin is reduced. In many cases, a reset operation does not occur, and it is possible to eliminate a problem caused by variations such as destruction and deterioration of a circuit.

[Brief description of the drawings]

FIG. 1 is a block diagram illustrating a configuration of a high-voltage discharge protection circuit according to a first embodiment of the present invention.

FIG. 2 is a block diagram showing a configuration of a delay circuit according to the first embodiment;

FIG. 3 is a block diagram showing a configuration of a high-voltage discharge protection circuit according to a second embodiment of the present invention.

FIG. 4 is a waveform chart showing a transition of an X-ray detection voltage when a discharge in the tube occurs in the second embodiment.

FIG. 5 is a block diagram showing a configuration of a high-voltage discharge protection circuit according to a third embodiment of the present invention.

FIG. 6 is a waveform diagram showing a pulse waveform in an electrode drive circuit such as a focus block and a cathode.

FIG. 7 is a block diagram showing a configuration of a comparison circuit according to a fifth embodiment of the present invention.

FIG. 8 is a block diagram showing a configuration of a comparison circuit according to a sixth embodiment of the present invention.

FIG. 9 is a block diagram showing a configuration of a comparison circuit according to a seventh embodiment of the present invention.

FIG. 10 is a block diagram showing a configuration of a conventional high-voltage discharge protection circuit.

FIG. 11 is a block diagram showing a configuration of a conventional high-voltage discharge protection circuit.

[Explanation of symbols]

 REFERENCE SIGNS LIST 3 delay circuit 4 comparison circuit 5 reset circuit 6 microcomputer 9 reference voltage generation circuit 10 voltage comparison circuit 11 storage circuit 12 pattern recognition circuit 13 A / D converter 14 storage circuit 15 digital data comparison circuit

 ────────────────────────────────────────────────── ─── Continued on the front page F term (reference) 5C068 AA16 AA20 GA01 GA02 GA03 GA12 5G013 AA01 AA04 AA09 BA02 CB04 DA03 DA09 DA11 5G043 AA05 AC02 BA06 BB01 BC03 5G053 AA10 BA04 CA01 DA01 EA03 EC06 FA06

Claims (8)

[Claims] A delay circuit that delays and outputs a peak of the abnormal pulse at least between a point of occurrence of the abnormal pulse due to discharge in the picture tube of the display device and a target circuit to be protected; A high-voltage discharge protection circuit, comprising: reset means for detecting the abnormal pulse between a circuit and a picture tube to reset the display device, wherein a delay time of the delay circuit is longer than a reset time of the display device. 2. A reset circuit comprising: a reset circuit for comparing a waveform voltage of an abnormal pulse with a reference value and generating a control signal when an abnormality is detected; and a reset circuit for resetting a display device upon receiving a control signal from the comparison circuit. 2. The high-voltage discharge protection circuit according to claim 1, comprising: 3. A high-voltage discharge protection circuit comprising the high-voltage discharge protection circuit according to claim 2 provided in an X-ray detection voltage section from a flyback transformer. 4. A high voltage discharge protection circuit comprising the high voltage discharge protection circuit according to claim 2 provided in a focus voltage generation circuit. 5. A high-voltage discharge protection circuit according to claim 2, wherein the high-voltage discharge protection circuit is provided in at least one of a driving voltage generation circuit for a cathode, a heater, and a screen. 6. A comparison circuit comprising: a reference voltage generation circuit for generating a reference voltage; and a voltage comparison circuit for comparing the reference voltage with a waveform voltage of an abnormal pulse and generating a control signal when an abnormality is detected. Item 3. A high-voltage discharge protection circuit according to item 2. 7. A comparison circuit comprising: a storage circuit for storing a waveform of an abnormal pulse; and a pattern recognition circuit for comparing and recognizing the stored waveform of the abnormal pulse with an input pulse and generating a control signal when detecting an abnormality. 3. The high-voltage discharge protection circuit according to claim 2, wherein 8. A comparison circuit comprising: an A / D converter for converting an input pulse from analog to digital; a storage circuit for storing a waveform of an abnormal pulse; 3. The high-voltage discharge protection circuit according to claim 2, comprising a digital data comparison circuit that generates a control signal when the signal is detected.