KR19990007143U - Image signal level control device of high pressure variable compensation method - Google Patents

Abstract

The present invention relates to a video signal level control device of a high-voltage variable compensation method, which is operated by a power supply voltage applied from a power supply system including a flyback transformer 18 to reproduce an R / G / B color ratio as an image. In a television equipped with a device (22), a high pressure detector (30) for detecting a potential of an anode power supply applied from the flyback transformer (18) to an anode electrode of the CRT device (22), and the high pressure detector (30). The digital converter 32 digitally encodes the high pressure detection value detected by the digital signal, and compares the digital transformed high voltage detection value with reference current data stored in the reference current data storage unit 36, based on the comparison result. 40 is applied to the R / G / B electron gun of the CRT apparatus under the control of the control unit 34, the control unit 34 for controlling the image level applied to the R / G / B electron gun of the CRT apparatus; R / G The image level increasing unit 40 increases the amount of current in the / B color beam and the amount of current in the R / G / B color beam applied to the R / G / B electron gun of the CRT apparatus under the control of the controller 34 is reduced. It is characterized in that it comprises a video level reduction unit 42.

Description

Image signal level control device of high pressure variable compensation method

The present invention relates to a video signal level control device of a high-voltage variable compensation method, and more particularly, to measure the beam current output from the flyback transformer to the anode electrode of the CRT, and based on the measurement result, R / G / B The present invention relates to a video signal level control apparatus of a high-voltage variable compensation method that increases / decreases the brightness / contrast level of a video signal so that a beam current reaches a reference value.

Typically, a television is provided with a CRT apparatus as a video output means for reproducing a video signal included in a TV broadcast program or for example, for reproducing an external video signal from a video tape recorder (VCR). Equipped with an R / G / B electron gun that emits an R / G / B color beam corresponding to the R / G / B color component of the R / G / B electron beam When the R / G / B color beam is reached through the shadow mask while being deflected by the vertical / horizontal deflectometer, the fluorescent panel is configured to emit light to form a color image.

1 is a diagram partially showing a power supply system of a television for applying an operating power to such a CRT apparatus, wherein reference numeral 10 denotes a horizontal output transistor to which a horizontal drive signal Hs is applied to the base, and A damping diode and a capacitor, which are connected to the collector side of the horizontal output transistor 12 and perform a damping function against a sudden change in the collector current, are shown. 16 is an R / G / B color ratio that is connected to the collector side of the horizontal output transistor 10 to determine the collector current determined by the switching action of the horizontal output transistor 10 from the R / G / B electron gun. Represents a horizontal deflection coil for performing a horizontal deflection for.

18, one end of the primary coil is connected to the collector side of the horizontal output transistor 10 to generate a power supply for the operation of the television and an operation power supply of the CRT apparatus ('22' in Fig. 1) in the secondary coil. At the other end of the primary side coil of the flyback transformer 18, an image signal power supply (DC; approximately 150V) applied to the R / G / B electron gun is obtained, while the flyback transformer 18 A variable resistor 24 for connecting the anode electrode of the CRT device 22 to the secondary coil through a high-voltage rectifier diode 20 and variably setting the focus voltage FOCUS VOLTAGE applied to the focus electrode of the CRT device 22. ) And a variable resistor 26 that variably sets the screen voltage (SCREEN VOLTAGE) applied to the screen electrode of the CRT apparatus 22.

Therefore, according to the power supply system, when the corresponding television is set to the power ON state, a horizontal drive signal having a constant duty ratio in the horizontal drive is applied to the base of the horizontal output transistor 10, and accordingly the horizontal The output transistor 10 switches according to the duty ratio of the horizontal drive signal, and the collector current corresponding to the duty ratio of the horizontal drive signal appears on the collector side. Accordingly, the collector current due to the switching action of the horizontal output transistor 10 is applied to the horizontal deflection coil 16 in a state of being damped by the damping circuits 12 and 14, so that the R / The horizontal deflection action of the color beam emitted from the G / B electron gun is performed.

In addition, an image signal power source to be applied to the R / G / B electron gun of the CRT device 22 while the current flowing through the primary coil of the flyback transformer 18 is interrupted according to the switching action of the horizontal output transistor 10. While (DC) is obtained, the secondary coil of the flyback transformer 18 obtains a high voltage applied to the anode electrode of the CRT device, and the CRT device 22 from the variable resistor 24 connected to the high voltage. The screen voltage (SCREEN) applied to the screen electrode of the CRT apparatus 22 is obtained from the focus voltage FOCUS applied to the focus electrode and the variable resistor 26.

Accordingly, the CRT apparatus emits an R / G / B color beam from the R / G / B electron gun in response to the R / G / B signal processed by the image processing means by the image signal power supply DC, and the R / G / B color beam is emitted. The G / B color beam is R / G / B fluorescent on a fluorescent panel depending on a high pressure applied to the anode electrode through a shadow mask (not shown) in a state where horizontal deflection is made by the horizontal deflection coil 16. When the point reaches the point and emits light, the color image is displayed on the CRT apparatus.

Here, the anode power source in the CRT device 22 is ideally in the form of a high voltage / low current. Generally, when the size of the CRT device is 20, the beam current by the anode power source is 1000 μA and the dimension is 25. In the case where the beam current has a dimension of 1200 µA and 29, the beam current is preferably 1500 µA.

Therefore, when the beam current caused by the anode power applied to the CRT device 22 is generally strong, the fluorescent material forming the R / G / B fluorescent point on the fluorescent panel burns and the life of the CRT device 22 is shortened. The phenomenon that the screen flows is caused, and therefore, it is necessary to appropriately adjust the beam current in the CRT apparatus.

The present invention has been made in view of the above circumstances, and the flyback transformer detects the potential applied to the anode electrode of the CRT apparatus and controls the brightness / contrast of the video signal based on the increase or decrease of the beam current with respect to the reference value. It is an object of the present invention to provide a video signal level control device of a high-voltage variable compensation method.

According to an embodiment of the present invention for achieving the above object, a television having a CRT device that is operated by a power supply voltage applied from a power supply system including a flyback transformer to reproduce an R / G / B color ratio as an image. A digital converter comprising: a high pressure detector for detecting a potential of an anode power supply applied from the flyback transformer to an anode electrode of the CRT apparatus; and a digital converter for digitally encoding the high pressure detection value detected by the high voltage detector; A control unit for comparing the high voltage detection value with reference current data stored in the reference current data storage unit and controlling the image level applied to the R / G / B electron gun of the CRT apparatus based on the comparison result; Image level to increase the amount of current in the R / G / B color beam applied to the R / G / B electron gun of the CRT apparatus under control of A video signal level control device according to the high-voltage variance compensation method comprising: a video level reduction unit for reducing the amount of current of the R / G / B color beam applied to the R / G / B electron gun of the CRT apparatus under the control of the controller. Is provided.

According to the present invention having the above-described configuration, the potential of the anode power source of the CRT applied by the flyback transformer of the power supply system is detected and digitally encoded, and the digital encoding result is compared with the reference current data, and the video signal is based on the comparison result. The luminance / contrast level of the image signal processed by the processing unit is adjusted, thereby stabilizing the R / G / B color beam emitted from the R / G / B electron gun.

1 is a view showing a part of a power system for generating a power supply voltage applied to a television CRT apparatus;

2 is a block diagram showing an apparatus for controlling a video signal level of a high voltage variation compensation method according to an embodiment of the present invention;

3 is a diagram illustrating the circuit configuration of the image level increasing unit 40 and the image level reducing unit 42 shown in FIG.

* Description of the symbols for the main parts of the drawings *

10: horizontal output transistor, 16: horizontal deflection coil,

18: flyback transformer, 22: CRT unit,

30: high pressure detection unit, 32: digital conversion unit,

34: control unit, 36: reference current data storage unit,

38: image processing unit, 40: image level increasing unit,

42: Image level reduction part.

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

FIG. 2 is a block diagram illustrating an apparatus for controlling a video signal level of a high voltage variation compensation method according to an embodiment of the present invention, in which reference numeral 18 is a switching action of a horizontal output transistor 10 (FIG. 1). An anode power supply to the primary coil and the flyback transformer generating a focus voltage and a screen voltage are applied to the CRT device 22 on the secondary side while the current flows intermittently, 30 denotes an anode power supply of the flyback transformer 18. And a high voltage detector interposed between the anode electrode and the anode electrode of the CRT apparatus 22 to measure the potential of the anode power source applied from the flyback transformer 18.

Here, the high-pressure detection unit 30 is connected to a pressure reducing transformer 30a for reducing the anode power output from the FBT 18 at a winding ratio of '250: 1' and a secondary side of the pressure reducing transformer 30a. A rectifier diode 30b for rectifying the secondary side power supply of the decompression transformer 30a and a cathode are connected to the rectifier diode 30b to output a voltage difference between the voltage output from the rectifier diode 30b and the rated voltage. A Zener diode 30c and a resistor 30d connected to the cathode of the Zener diode 30c to prevent a predetermined power output through the Zener diode 30c from being grounded are connected in series.

Here, in consideration of the anode voltage of the CRT being 25 kV to 28 kV, the zener diode 30c preferably employs a rated capacity of about 90V.

In FIG. 2, reference numeral 32 denotes a digital conversion unit for converting the high voltage detection voltage measured by the high voltage detection unit 30 into a digital code, and 34 denotes a digital conversion of the anode power source digitally converted by the digital conversion unit 32. A control unit for comparing the potential with the reference current data stored in the reference current data storage unit 36 and driving control of the image level increasing unit 40 and the image level reducing unit 42 to be described later based on the comparison result value, The reference current data stored in the reference current data storage 36 is made of an ideal current level and an allowable range corresponding to the dimensions of the CRT device 22. That is, when the size of the CRT apparatus 22 is 20, the reference current data is set in the reference current data storage 36, wherein 1000 μA is set as the reference current and the allowable range is approximately 10%. When the size of the CRT device 22 is 25, the reference current data is set in the reference current data storage unit 36 and 1200 μA is set as the reference current and the allowable range is approximately 10%. In the case where the dimension of 22 is 29, the reference current data is set in the reference current data storage section 36 while 1500 mu A is set as the reference current and the allowable range is approximately 10%.

In addition, reference numeral 38 denotes an image processor for outputting an R / G / B signal for screen output of the broadcast signal by performing an image reproduction processing operation on the broadcast signal received through an antenna, and 40 denotes a portion of the controller 34. Under the control, an image level increasing unit increases current in the R / G / B signal output from the image processing unit 38 and increases the luminance / contrast of the image signal corresponding to the R / G / B signal. Image level for reducing the luminance / contrast of the video signal corresponding to the R / G / B signal by partially bypassing the current of the R / G / B signal output from the image processor 38 under the control of the controller 34. Reduction part is shown.

As illustrated in FIG. 3, the image level increasing unit 40 includes a current-driven transistor 404 turned on / off by an enable signal EN1 applied from the controller 34, and the transistor 404. An anode is connected to the voltage divider resistors 406, 410 and 414 for distributing the voltage applied from the voltage divider and the voltage divider resistors 406, 410 and 414 to prevent the R / G / B current output from the image processor 38 from flowing backward. It consists of a backflow prevention diode (408, 412, 416) for.

In addition, the image level reducing unit 42 includes a current-driven transistor 420 turned on / off by the enable signal EN2 from the controller 34, and an R / G / of the image processing unit 38. Zener diodes 424, 428, 432 and zener diodes 424, 428, 432 for outputting only the differential voltage when an R / G / B voltage output from the R / G / B output terminal is higher than a reference voltage when the cathode is connected to the B output terminal. The resistors 426, 430, and 434 for adjusting the bias of the power supply connected to the anode end of the zener diodes 424, 428, 432 and the output of the zener diodes 424, 428, 432 are connected to the collector end of the current-driven transistor 42.

Next, the operation of the video signal level control device of the high-voltage variable compensation method according to an embodiment of the present invention of the above configuration in detail.

First, when the power of the corresponding television is controlled to the ON state, current flows intermittently through the primary coil of the flyback transformer 18 by the collector current of the horizontal output transistor by the switching action of the horizontal output transistor. Accordingly, the secondary coil of the flyback transformer 18 generates the high voltage to be applied to the anode electrode of the CRT device 22 and the focus voltage and the screen voltage to be applied to the focus electrode and the screen electrode.

The potential (voltage) of the anode power source applied from the flyback transformer 18 to the anode electrode of the CRT device 22 is applied to the anode end of the CRT and is also applied to the high pressure detector 30 to increase or decrease the high pressure. The detected high pressure is then applied to the digital conversion unit 32, and the potential of the anode power source applied to the digital conversion unit 32 is converted into a digital code and applied to the control unit 34. The control unit 34 compares the high voltage detection value with reference current data stored in the reference current data storage unit 36.

Here, when the anode voltage output from the FBT 18 is, for example, a reference voltage, that is, 24.5 kV, which is 25 kV or less, 98 V of power is output to the secondary side of the decompression transformer 30 a of the high voltage detector 30, and the output power thereof. Is applied to the zener diode 30c through the rectifying diode 30b. For this reason, the zener diode 30c outputs a power of about 8V to the digital converter 32, and the digital converter 32 converts the power into a digital signal and applies it to the control unit 34.

Subsequently, the control unit 34 determines that the potential of the anode power supply is lower than the reference current data of the reference current data storage unit 36 properly set for the dimensions of the CRT apparatus 22 and thus the image level. The enable signal is applied to the incrementer 40.

As a result, the current driving transistor 404 of the image level increasing unit 40 is turned on so that the Vcc power is output from the image processing unit 38 through the voltage distribution resistors 406, 410, 414 and diodes 408, 412, 416. It is added to the / G / B signal and reaches the R / G / B fluorescent point of the fluorescent panel in the state where the current of the R / G / B color beam is increased to emit light.

On the contrary, if the anode voltage output from the FBT 18 is, for example, a reference voltage, that is, 25.5 kV that is 25 kV or more, 102 V power is output to the secondary side of the decompression transformer 30 a of the high voltage detector 30, and the output thereof is output. Power is applied to the zener diode 30c through the rectifying diode 30b. Therefore, the zener diode 30c outputs about 12 power to the digital converter 32, and the digital converter 32 converts the power into a digital signal and applies the power to the controller 34.

Subsequently, the control unit 34 determines that the potential of the anode power source is higher than the reference current data of the reference current data storage unit 36 properly set for the dimensions of the CRT apparatus 22 to determine the image level. The enable signal is applied to the reduction unit 42.

Accordingly, the current driving transistor 420 of the image level reducing unit 42 is turned on so that the current of the R / G / B color beam output from the image processing unit 38 is transmitted to the zener diodes 424, 428, 432 and the resistance ( The predetermined power applied to the collector stage of the current-driven transistor 420 is bypassed through 426, 430, and 434, and the R / G / B of the R / G / B color beam is reduced on the fluorescent panel of the CRT. The B color beam reaches its R / G / B fluorescent point and emits light.

Therefore, when the potential of the anode power source of the CRT device 22 is increased, the CRT device is in a state in which the luminance / contrast level of the R / G / B color component of the image signal processed by the video processor 40 is reduced. (22) is applied to the R / G / B electron gun, so that the R / G / B fluorescent point of the fluorescent panel reaches and emits light while the current of the R / G / B color beam is reduced, whereas the CRT apparatus ( In the state where the potential of the anode power supply of 22) is reduced, the luminance / contrast level of the R / G / B color component of the image signal processed by the video processor 40 is increased, and the R / Since it is applied to the G / B electron gun, it eventually reaches the R / G / B fluorescent point of the fluorescent panel with the current of the R / G / B color beam increased to emit light.

As described above, according to the high-voltage variable compensation video signal level control apparatus according to an embodiment of the present invention, the potential of the anode power applied to the anode electrode of the CRT apparatus is detected from the flyback transformer and compared with the reference current data. As a result of the comparison, the luminance / contrast level of the video signal is added or subtracted to be applied to the R / G / B electron gun of the CRT apparatus, so that the beam current in the CRT apparatus can be stabilized even when the anode power source is changed.

Claims (5)

In a television equipped with a CRT apparatus 22 which is operated by a power supply voltage applied from a power supply system including a flyback transformer 18 to reproduce an R / G / B color ratio as an image, A high pressure detector 30 for detecting a potential of an anode power supply applied from the flyback transformer 18 to the anode electrode of the CRT apparatus 22; A digital conversion unit 32 for digitally encoding the high pressure detection value detected by the high pressure detection unit 30, The digitally converted high voltage detection value is compared with the reference current data stored in the reference current data storage 36 and processed by the image processor 40 based on the comparison result and applied to the R / G / B electron gun of the CRT apparatus. A control unit 34 for controlling the video level; An image level increasing unit 40 for increasing an amount of current of an R / G / B color beam applied to the R / G / B electron gun of the CRT apparatus under the control of the controller 34; Under the control of the control unit 34, the high-voltage fluctuation, characterized in that it comprises an image level reducing unit 42 for reducing the amount of current of the R / G / B color beam applied to the R / G / B electron gun of the CRT apparatus Compensation type video signal level control device. The method of claim 1, wherein the reference current data stored in the reference current data storage unit 36 comprises a reference current corresponding to the dimensions of the CRT device and an allowable range of the reference current. Image signal level control device. The image level increasing unit 40 of claim 1, wherein the image level increasing unit 40 is on / off controlled by an enable signal EN1 from the control unit 34, and the current driving transistor ( A voltage divider resistor 406, 410, 414 connected to the emitter terminal of the 404 to divide the Vcc power output from the current-driven transistor 404, and a voltage divider resistor 406, 410, 414 connected to the voltage divider resistor 406, 410, 414; High-voltage variable compensation image signal level control device, characterized in that consisting of diodes (408,412,416) to prevent the reverse current to the / G / B color beam. The image level reducing unit 42 of claim 1, further comprising: a current-driven transistor 420 on / off controlled by an enable signal EN2 from the control unit 34, and the image processing unit 38. A cathode connected to the R / G / B output terminal of the zener diodes 424, 428, 432 for outputting a zener voltage with respect to the potential of the R / G / B color beam, and anodes of the zener diodes 424, 428, 432 and the current-driven transistor ( And a bias adjustment resistor (426, 430, 434) connected between the collector stages of the (420). The high-pressure detector 30 is connected to an output terminal of the FBT 18, and a pressure reducing transformer 30a for reducing a voltage from a predetermined ratio and a rectifying die diagram 30b. A zener diode (30c) connected to the secondary side of the reduced voltage transformer (30a) and outputting a zener voltage (high voltage detection value) for the power applied through the rectifying diode (30b) to the digital converter (32). High-voltage fluctuation compensation video signal level control device comprising a.