KR19990027224U - High Voltage Rise Display Circuit of Monitor - Google Patents

Abstract

The present invention relates to a high-voltage rising display circuit of a monitor for sensitively sensing and displaying a high voltage in a monitor, and the circuit of the present invention includes: first to second divided resistors for dividing a high voltage; An amplifier for comparing the high voltage applied to the second voltage divider with a reference voltage; A transistor turned on when the amplifier outputs a high level amplified signal; And a display device that emits light while a current flows when the transistor is turned on.

Therefore, the present invention can sensitively monitor the fluctuation of the high voltage generated in the FBT and change the emission color of the light emitting diode accordingly, so that the user or the repairer of the monitor can know whether the high voltage rises and the amount of the rise, and thus the high voltage can be readjusted. As a result, the high voltage circuit and the CRT can be protected from the rise of the high voltage.

Description

A circuit for displaying of high-voltage's ascent in a monitor

The present invention relates to a high-voltage rising display circuit of the monitor for sensitively sensing and displaying the high pressure in the monitor.

In general, a cathode ray tube (CRT) focuses and accelerates hot electrons emitted from R, G, and B electron guns, and then collides with R, G, and B fluorescent surfaces through a point on a shadow mask to form pixels. Sawtooth current flows to form a two-dimensional screen. In order to operate the cathode ray tube (CRT), a heater voltage of about 6.3V is applied to the heater, and a focus grid voltage, a screen grid voltage, etc. are required for focusing the emitted hot electrons, and about the anode is accelerated. High pressure of about 25KV is applied.

By the way, when the high pressure applied to the anode in the cathode ray tube is normal, the electrons collide with the fluorescent surface and emit light in the visible range, but when the abnormally high pressure is applied to the anode, the electrons collide more strongly with the fluorescent surface. X-rays having a shorter wavelength than visible light may be generated.

Most human monitors monitor the high pressure applied to the anode when humans are exposed to such X-rays. When this high pressure is abnormally high, the X-rays stop the driving of the horizontal drive signal to prevent the high pressure from being generated. (X-RAY) protection circuit is provided.

FIG. 1 is a circuit diagram illustrating a conventional X-ray protection circuit in a monitor, which monitors a high voltage (HV) induced in a secondary winding of a high voltage generator (FBT) 130 so that a high voltage becomes abnormally high. An X-ray terminal of 140 is set high to prevent the generation of the horizontal drive signal H. drive.

Referring to FIG. 1, the voltage induced in the cubic coil of the FBT is rectified in the diode D1 and smoothed in the electrolytic capacitor C1 and then the zener diode ZD1 through the split resistors R1 and R2. Is applied to the cathode side of. The anode side of the zener diode ZD1 is connected to the X-RAY protective terminal of the oscillator 140. At this time, when the high voltage H.V of the FBT 130 is normal, a low voltage (that is, less than or equal to the rated voltage of the zener diode) is applied to the zener diode ZD1 to maintain the zener diode ZD1 in the off state.

On the other hand, when the high voltage H.V induced in the secondary winding of the FBT 130 and applied to the anode of the CRT becomes high, the voltage induced in the third winding of the FBT 130 also increases accordingly. When the tertiary side voltage increases, the voltage applied to the cathode of the zener diode ZD1 rises and rectifies and smoothes. When the rising voltage exceeds the rated voltage of the zener diode ZD1, the zener diode ZD1 conducts. The high level is applied to the X.RAY protection terminal of the oscillator 140.

When the high level is applied through the X-RAY protection terminal, the oscillator 140 blocks the horizontal drive signal (H.drive) oscillated from the internal oscillation circuit, and accordingly, the horizontal output unit 160 through the horizontal driver 150. Since there is no horizontal driving signal applied to the horizontal output transistor of the horizontal output unit 160 is kept turned off. If the horizontal output transistor is continuously turned off, the voltage is not induced in the secondary winding of the FBT 130 so that a high voltage may not be generated, thus increasing the high voltage, thereby preventing the CRT from generating X-rays. .

However, the X-ray protection circuit operates only when the high voltage output from the FBT rises above 4 to 5 KV above the normal size, and cannot detect when the high voltage rises within 4 to 5 KV. Due to this, the high voltage circuit and the CRT, which is a color display device, are damaged and shorten their lifespan.

Therefore, the present invention has been devised to solve the problems of the prior art, and if the high voltage is raised in the range where the X-ray protection circuit does not operate, it detects and displays the high voltage of the monitor so that it is within the rated range. It is an object of the present invention to provide a high-voltage rising display circuit of a monitor.

In order to achieve the above object, the circuit of the present invention, in the monitor that the high voltage is generated in the secondary winding of the FBT by switching the B + voltage applied to the primary winding of the FBT according to the horizontal drive signal, the high voltage First to second voltage divider resistors for dividing the pressure; An amplifier for comparing the high voltage applied to the second voltage divider with a reference voltage; A transistor turned on when the amplifier outputs a high level amplified signal; And a display device that emits light while a current flows when the transistor is turned on.

1 is a circuit diagram showing a conventional X-ray protection circuit in the monitor,

2 is a circuit diagram illustrating an X-ray protection circuit to which a high voltage rising display circuit according to the present invention is applied to a monitor.

* Explanation of symbols for the main parts of the drawings

110: power supply 120: DC-DC converter

130: high pressure generator (FBT) 140: oscillation unit

150: horizontal drive unit 160: horizontal output unit

170: x-ray protection unit 200: high pressure rising display unit

Hereinafter, an embodiment of the present invention will be described in detail with reference to the accompanying drawings.

Bar diagram showing a monitor to which the high-voltage rising display circuit and the X-ray protection circuit according to the present invention are applied, which is a power supply 110, a DC-DC converter 120, an FBT 130, a horizontal oscillator 140, and a horizontal When the high voltage rises above a predetermined voltage by sensing the high voltage HV provided to the CRT using the voltage output from the driving unit 150, the horizontal output unit 160, and the third winding of the FBT 130, the horizontal driving signal It is composed of an X-ray protection unit 170 to block the (H.drive) to prevent the FBT 130 is driven, and a high-voltage rising display unit 200 to sense the high voltage rise even if the high voltage rises even slightly.

The high voltage rising display unit 200 includes a first divided resistor R21 to a second divided resistor R22 for dividing the high voltage HV, and a high voltage applied to the second divided resistor R22. An amplifier 210 for inputting a positive input terminal through the input terminal and a reference voltage as a negative input terminal through the resistor R24 and the zener diode ZD21 and comparing the two voltages, and amplifying a high level in the amplifier 210. When the signal is output, the transistor Q21 is applied to the base terminal through the resistor R25 and turned on, and when the transistor Q21 is turned on, the display element and the resistor R26 that emit light while current flows, and the amplifier Negative feedback is composed of a feedback resistor (R27). In this case, the display device may be implemented as a light emitting diode 220 whose color changes according to the amount of current.

The operation of the present invention configured as described above is as follows.

The power supply 110 receives the AC power AC and outputs predetermined DC voltages to each part of the monitor. The DC-DC converter 120 is a boost-up converter or a buck type converter and receives a DC voltage and applies a predetermined B + voltage to the primary winding of the FBT 130.

The FBT 130 includes a primary winding to which a B + voltage is applied, a secondary winding to which a high voltage is induced, and a tertiary winding to induce a low voltage induced voltage. The FBT used in the embodiment of the present invention is a laminated type, and the laminated type FBT has an advantage of reducing reliability of the layer short of the secondary winding.

The high voltage HV induced by the secondary winding of the FBT 130 is applied to the anode of the CRT, and the focus voltage and the screen voltage divided by the resistor are applied to the focus grid and the screen grid of the CRT, respectively. do. In addition, an ABL circuit is connected to one end of the secondary winding to decrease the contrast of the video preamplifier, not shown, when the anode current increases.

The oscillator 140 receives the synchronization signals H.sync and V.sync and generates a horizontal drive signal H.drive locked thereto, and the horizontal driver 150 outputs the horizontal drive signal output from the oscillator 140. After fully amplifying (H.drive) and outputs to the horizontal output unit (160). In the horizontal output unit 160, a sawtooth wave current flows in the horizontal deflection coil H.DY by turning on / off an internal horizontal output transistor according to a horizontal driving signal input through the horizontal driver 150.

On the other hand, when the high voltage (HV) induced in the secondary winding of the FBT (130) in the monitor rises, the high-voltage rise display unit 200 is operated to light up the light emitting diode 220, the user of the monitor can recognize this. Make sure That is, the high voltage HV output from the FBT 130 is properly branched by the first voltage divider R21 and the second voltage divider R22, and the positive input terminal of the amplifier 210 is provided through the resistor R23. Is applied. At this time, a reference voltage is applied to the negative input terminal of the amplifier 210 by the zener diode ZD21.

When the high voltage H.V maintains the normal voltage, the amplifier 210 outputs a low level amplified signal because the high voltage H.V applied to the positive input terminal is lower than the reference voltage applied to the negative input terminal. However, when the high voltage rises, since the high voltage applied to the positive input terminal is higher than the reference voltage applied to the negative input terminal, the amplifier 210 amplifies and outputs the difference voltage between the high voltage and the reference voltage, and the high voltage is higher than the reference voltage. As it increases, the amplified signal output from the amplifier 210 increases.

The amplified signal is applied to the base terminal of the transistor Q21 to turn on the transistor Q21. If the potential of the amplified signal applied to the base terminal of the transistor Q21 is high, the collector and emitter terminals of the transistor Q21 are high. Through a large amount of current flows, if the potential of the amplified signal is low, a small amount of current flows. In addition, the current flowing to the transistor Q21 passes through the light emitting diode 220. When the amount of current passing through the light emitting diode 220 is large, the light emitting diode 220 emits red light, and the light emitting diode 220 As the amount of current passing through the LED decreases, the light emitting diode 220 emits orange light and then emits blue light.

That is, although the X-ray protection unit 170 is not enough to operate, when the high voltage output from the FBT 130 rises, the LED 220 emits light and displays that the high voltage is higher than the normal high voltage. Can be readjusted with voltage. In addition, since the degree of increase of the high voltage can be known through the light emitting color of the light emitting diode 220, the readjustment amount of the high voltage can be accurately known.

On the other hand, if the high voltage (HV) induced by the secondary winding of the FBT 130 in the monitor is excessively higher than the normal voltage, there is a possibility that the X-ray (X-RAY) in the CRT, X-ray protection unit 170 Is driven to suppress the generation of X-rays.

That is, when the voltage induced in the secondary winding of the FBT 130 is increased, the voltage induced in the secondary winding is also increased. The voltage induced in the tertiary winding is rectified in the diode D1, smoothed in the electrolytic capacitor C1, divided by the division resistors R1 and R2, and then applied to the zener diode ZD1. When the high voltage HV output from the secondary winding of the 130 is increased and the voltage applied to the zener diode ZD1 becomes higher than the zener voltage, the zener diode ZD1 is turned on, so that the X-ray terminal X. RAY) is applied to the high level.

At this time, the oscillator 140 does not output the horizontal drive signal (H.drive), which causes the driving of the horizontal drive unit 150 and the horizontal output unit 160 to stop the B + voltage applied to the FBT 130 The switching operation of is not made. That is, when the high voltage rises above a certain voltage, the output of the high voltage through the FBT is temporarily stopped to stabilize the high voltage.

As described above, the high-voltage rising display circuit according to the present invention sensitively monitors the fluctuation of the high voltage generated in the FBT, and the light emitting color of the light emitting diode changes accordingly, so that the user or repairman of the monitor knows whether the high voltage is rising and the amount of the rising. As a result, it is possible to readjust the high voltage, thereby protecting the high voltage circuit and the CRT from rising of the high voltage.

Claims (1)

In the monitor in which the high voltage is generated in the secondary winding of the FBT by switching the B + voltage applied to the primary winding of the FBT according to the horizontal drive signal, First to second voltage divider resistors for dividing the high voltage; An amplifier for comparing the high voltage applied to the second voltage divider with a reference voltage; A transistor turned on when the amplifier outputs a high level amplified signal; And The display device of claim 1, wherein the transistor comprises a display element which emits light when current is turned on.