KR20000021579A - Method for discharging residual voltage of cathode ray tube when power supply is off - Google Patents

Abstract

PURPOSE: A method for discharging residual voltage of a CRT(Cathode Ray Tube) is provided to rapidly down the residual operating voltage in a Braun tube, when power supply is off. CONSTITUTION: A TV set receives an R.G.B signal amplified imaginally by a control of an image processor, and emits an electron according to the R.G.B signal. The TV set provides high voltage over the certain value on an aluminum plate of the fluorescent side, to collide an electron gun for scanning an electron beam with the electron beam on the fluorescent side, and has a CRT(Cathod Ray Tube) for being composed of an anode terminal for discharging high voltage when power supply is off. A method for discharging residual voltage of the CRT comprises the steps of: providing an arbitrary R.G.B signal while residual voltage of operating voltage exists, supplied to the image processor when power supply is off; forming the electron beam according to the R.G.B signal; and scanning to inside of the CRT.

Description

Method for remainder voltage discharge of CRT at powor OFF

The present invention relates to a method for discharging a high voltage remaining inside a cathode ray tube when a power supply is turned off in a television receiver. In particular, the microcomputer scans an electron beam according to an arbitrary RGB color signal by a driving voltage remaining at the time of power-off operation. The present invention relates to a method for discharging a cathode ray tube residual voltage when a power supply is turned off to rapidly lower a voltage remaining therein.

In general, a TV for receiving and watching a broadcast signal transmitted from a broadcasting station is briefly described with reference to FIG. 1, when a power cord is inserted into an outlet (not shown), a standby power (eg, 5V) is applied to the microcomputer 200. In addition, the operation of the TV by the operation of the key input unit 220 and the power supply unit 700 for applying the main power source AC110 / 220V to the FBT 800 by the power “key” operation of the key input unit 220 are performed. A broadcast signal of a channel selected by the microcomputer 200 to be controlled by the microcomputer 200, the memory 240 storing data to be processed by the microcomputer 200, and the preset voltage output from the microcomputer 200. A tuner 100 received from the image processor, an image processor 300 for processing an image signal of a broadcast signal received by the tuner 100, and an image amplifier for amplifying the image signal output from the image processor 300. 320 and the image processor 300 The vertical / horizontal synchronization processor 340 for deflecting the vertical synchronization signal and the horizontal synchronization signal of the image signal displayed on the screen of the CRT 400 by the vertical / horizontal synchronization signal, and the image signal output from the image amplifier 320. to the CRT 400 and, the power supply section 700, the CRT must generate a high-voltage pulse required by the 400 and the addition the video processor 300 by the main power supplied from the input received on the screen B ⁺ FBT 800 for supplying driving power, a voice processor 500 for processing a voice signal of a broadcast signal received by the tuner 100, and a voice signal processed by the voice processor 500 is amplified to a predetermined level. The speech amplifier 520 and the speaker 600 and 620 that receive and output the voice signal output from the voice amplifier 520 are largely configured.

At this time, the function of the FBT 800 in the above-described configuration in more detail, the time to return to the next dice according to the horizontal synchronization of the television scan is called flyback (Flyback), the power required is a flyback high-voltage power supply It is called. Therefore, a transformer for generating a flyback high voltage power is called a flyback transformer (FBT).

Therefore, referring to FIG. 2 attached to the conventional FBT configuration, the power supply ACV supplied to the horizontal deflection coil DY is changed at the flyback time, that is, the pulse voltage is converted using the high frequency transformer TL. After the step-up, the high-voltage rectifier 10 is used to convert the voltage to about 25 kV to 30 kV and use it as a horizontal deflection output of the television receiver. In addition, a relatively low voltage is induced through a portion of the high frequency transformer TL to obtain a voltage of 400 V to 600 V using the rectifier 20 to be used as a high voltage source of the anode of the water pipe.

However, if the power supply is cut off due to a sudden power off or power outage during the normal operation of displaying the received broadcast signal on the screen, the power supply to the horizontal deflection coil DY is cut off. In this case, the high frequency transformer TL acts as if it is a voltage change caused by a flyback time.

Therefore, a high voltage output through the rectifier 20 is applied to the water pipe anode so that a portion of the screen is exposed for a predetermined time (for example, 2 to 3 seconds), that is, during a time when the high voltage applied to the water pipe anode is naturally discharged. Afterimages occur after concentration.

However, this phenomenon is increased as the use of the product increases, causing a problem of shortening the life of the product.

An object of the present invention for solving the above problems is to rapidly reduce the voltage remaining inside the CRT by scanning the electron beam according to the arbitrary RGB color signal by the driving voltage remaining at the time of power off operation. It is to provide a cathode ray tube residual voltage discharge method when the power is off.

1 is a schematic configuration example of a general television receiver

2 is a schematic configuration example of a flyback transformer

3 is a configuration example of a cathode ray tube

4 is an exemplary operation diagram illustrating a cathode ray tube residual voltage discharge method at power off according to the present invention;

<Explanation of symbols for main parts of the drawings>

200: Microcomputer 800: FBT

700: power supply unit 220: key input unit

240: memory ANT: antenna

100: tuner 300: image processor

320: image amplifier 400: CRT

340: vertical / horizontal synchronization processor 500: voice processor

520: voice amplifier 600, 620: speaker

A feature of the present invention for achieving the above object is, by the control of the image processor is scanned by the electron gun and the electron gun that receives the R, G, B signal amplified by the image processor and emits electrons to form an electron beam A method for discharging residual high voltage in a television receiver comprising a cathode ray tube composed of an anode terminal for supplying a high voltage of a predetermined value or more to an aluminum film of a fluorescent surface to impinge an electron beam onto a fluorescent surface and discharging the high voltage when the power is turned off. The first step of providing an arbitrary RGB signal while the residual voltage of the driving voltage supplied to the image processor at the time of off, and forming an electron beam according to the RGB signal provided in the first step to scan inside the cathode ray tube It includes the second step.

First, referring to the accompanying drawings briefly described the technical spirit to be applied in the present invention, Figure 3 is a schematic diagram showing the internal structure of the CRT (400), generates heat by receiving the image amplified R, G, B signals The heater 410 to increase the temperature of the cathode 420, the cathode 420 to emit electrons when a negative voltage is supplied from the heater 410, and the amount of electrons emitted from the cathode 420. The control grid 430 modulates luminance (change in brightness) and a constant voltage (for example, +110 V to 400 V) so that electrons emitted from the cathode 420 can reach the fluorescent surface 492 of the glass tube 490. By supplying electrons with charges to accelerate them in the axial direction, and by supplying a constant voltage (for example, +10 mA or more) to electrons accelerated primarily in the acceleration grid 440 The medium acceleration grid 450 and the cathode 420 are accelerated by the glass tube 4 The focusing grid 460 and the cathode 420 are discharged from the accelerating grid to form a thin electron beam by axially concentrating electrons moving toward the fluorescent surface 492 of the 90 to be diffused by the repulsive force between the electrons. A high acceleration grid that supplies a constant voltage (eg, +10 Hz or more) to the electrons accelerated twice through the medium acceleration grid 450 and accelerates in the third order to collide with the fluorescent surface 492 of the glass tube 490. 470 and an anode terminal 480 for supplying a high voltage of a constant voltage (for example, +10 mA) or more to the aluminum film of the fluorescent tube 492 of the glass tube 490 and discharging the high voltage when the power is "off".

At this time, the high voltage discharged through the anode terminal 480 as in the above-described problems of the prior art has a discharge time of about 2 to 3 seconds, the cause of which is supplied to the aluminum film of the fluorescent surface 492 of the glass tube 490 While the power supply drops from 400V to 600V at a voltage of about + 10㎸ or more, there is no current flow from the electron gun, and according to Ohm's law, the resistance component inside the cathode ray tube increases almost infinitely.

Therefore, since the time that the voltage of about 400V to 600V is discharged through the anode terminal 480 is delayed with the increase of the resistance due to the increase of the internal resistance component, the light concentrates and the afterimage occurs as described above. Will be.

Therefore, in the present invention, even if the power is turned off, by using the driving voltage (B +) remaining in the microcomputer 200 to scan the RGB color signal for a certain duration so that the internal resistance component does not increase the residual inside the cathode ray tube This is to allow the voltage being discharged to discharge quickly.

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

4 is an exemplary view illustrating operation of the cathode ray tube residual voltage discharge method when the power is turned off according to the present invention.

While performing a normal television operation in step S101, if it is determined that there is a power off request in step S102 due to a user's request or a factor such as a power failure, the flow proceeds to step S103 to cut off the power supply of peripheral devices that have been supplied with driving power. Done.

At this time, the microcomputer 200 controls the peripheral image processing processor and the like by the residual voltage B + provided from the fly back transformer 800 and accordingly emits another electron beam to the RGB color signal.

Provided to the cathode ray tube residual voltage discharge method when the power off according to the present invention operating as described above is supplied to the aluminum film of the glass tube fluorescent surface of the conventional cathode ray tube as the current flows by the electron beam for a predetermined time even when the power is off Although the power supply falls from 400V to 600V at a voltage of about +10 + or more, there is no current flow from the electron gun, so the Ohm's law increases the resistance in the cathode ray tube almost infinitely and thus remains. Since the time that the voltage is discharged through the anode terminal is delayed with the increase of the resistance, the problem that the afterimage occurs due to the concentration of light as described above is solved.

Claims (1)

In order to collide with the fluorescent surface, the electron gun scanning the electron gun scanned from the electron gun to receive the R, G, B signals amplified by the control of the image processor, and emit electrons corresponding to the fluorescent surface. A method for discharging a residual high voltage in a television receiver having a cathode ray tube made of an anode terminal which is supplied to an aluminum film and discharges a high voltage when the power is turned off. A first step of providing an arbitrary RGB signal while there is a residual voltage of a driving voltage supplied to said image processor at power off; And a second step of forming an electron beam according to the RGB signal provided in the first step and scanning the electron beam inside the cathode ray tube.