KR100250187B1 - Duble focusing voltage producing apparatus for cathode-ray tube - Google Patents

Abstract

PURPOSE: A double focusing apparatus is to adjust a collector voltage obtained at a collector part of a horizontal output transistor into a low voltage level to be overlapped with a focusing grid power source generated at a flyback transformer, thereby preventing luminance difference at a center portion and a corner portion of a CRT. CONSTITUTION: An R,G,B electron gun irradiates R,G,B color beam corresponding to an R,G,B color component of a video signal. A focusing electrode condenses the R,G,B color beam. An anode electrode accelerates the R,G,B color beam. A rectifying diode(26) and a smoothing capacitor(28) are connected between a collector part of a horizontal output transistor(10) and a primary end of a flyback transformer(18) to transform a collector voltage of the horizontal output transistor into a DC level. A multi-power regulator(32) generates a sub-focusing voltage having a frequency corresponding to a horizontal scanning period of a CRT. The sub-focusing voltage also has a parabolic waveform in which electric potential at the center portion of the CRT is a minimum level. A focus voltage overlapping process portion(34) overlaps the sub-focusing voltage generated from the multi-power regulator with the focusing voltage applied from the flyback transformer to the focusing grid.

Description

DUBLE FOCUSING VOLTAGE PRODUCING APPARATUS FOR CATHODE-RAY TUBE}

The present invention relates to a dual focusing apparatus of a television. More particularly, a single focusing function is formed by forming a focusing voltage in a state in which a focusing voltage for a corner portion is superimposed on a focusing voltage for a central portion of a CRT apparatus employed in a television. The present invention relates to a double focusing apparatus for a television for focusing at the center and corner portions of a CRT apparatus.

As is well known, televisions employ a CRT apparatus for reproducing an image, and according to the principle of image reproduction in the CRT apparatus, radiation from an R / G / B electron gun is made in response to an R / G / B color signal of an image signal. When the R / G / B pixel beam reaches the corresponding R / G / B pixel fluorescent point applied on the fluorescent panel, the color image is reproduced by emitting the R / G / B pixel fluorescent point.

1 shows a schematic configuration of such a CRT apparatus, in which reference numeral 1 is arranged in an in-line form or in a Δ- form to emit R / G / B color beam component (B). Represents a representative cathode of the / G / B electron gun, 2 denotes a heater that heats the cathode 1 to about 800 ° C, and 3 denotes an electron due to a voltage difference applied to the cathode 1, that is, a bias voltage. The first grid (control grid) for controlling the brightness of the screen by controlling the amount of.

In addition, 4 represents a second grid (screen grid) that sucks the positive electrons adjusted in the control grid 3 by a positive voltage, 5 and 6 are the color beams B passing through the screen grid (4) The third and fourth grids (focus electrode and high voltage electrode) for further accelerating electrons of the? In addition, a pre-focus lens 7 for prefocusing electrons of the color beam B is provided between the screen grid 4 and the focus grid 5, and the focus grid 5 is provided. A focus lens 8 for focusing the color beam B is provided between the and the high voltage electrodes 6.

In addition, in FIG. 1, reference numeral 9 denotes a shadow mask which guides the plurality of through holes to be formed so that the electrons of the color beam B reach the R / G / B fluorescent points formed on the fluorescent panel 10. Denoted at 10 is a high voltage power supply for allowing a high voltage anode current to flow through the anode electrode of the corresponding CRT apparatus.

According to the CRT apparatus having the above-described configuration, the cathode 1 corresponding to the R / G / B color signal of the image signal processed by the image processing system while the cathode 1 is heated by the heater 2 is corresponding. ) Is applied to the cathode (1), the hot electrons of the color beam (B) is emitted, and when the voltage (approximately 200V-400V) is applied to the screen grid 4, the control grid 3 and the screen grid Depending on the bias voltage of (4), the amount of electrons passing through the control grid 3 is appropriately adjusted and accelerated toward the screen grid 4 side. The electrons of the accelerated color beam B are further accelerated toward the focus grid 5 and the high voltage electrode 6 to which a relatively high voltage is applied through the prefocus lens 7, and of the accelerated color beam B. The electrons reach the corresponding R / G / B fluorescent points on the fluorescent panel 10 through the shadow mask 9 to emit the pixels, and thus the color image is reproduced on the fluorescent panel 10.

As the electrons reaching the fluorescent panel 10 flow into the high voltage power source 10 along the direction of arrow 'A' in the drawing, the high voltage anode current is applied to the anode electrode of the corresponding CRT apparatus. do.

In addition, the high voltage of the anode electrode applied to the CRT apparatus illustrated in FIG. 1, the focusing power applied to the focus grid, and the screen power applied to the screen grid are generated in the flyback transformer mounted on the television.

Here, when focusing the R / G / B color beams in the CRT apparatus illustrated in FIG. 1, a difference in luminance is caused in the center portion and the corner portion of the screen of the CRT apparatus by a focusing action by a single focusing electrode. In order to compensate for the luminance difference, in recent years, the focusing of the CRT apparatus is doubled to install the first focusing grid for focusing at the center and the second focusing grid for focusing at the corner.

However, for the first and second focusing grids employed in the case where the focusing of the CRT device is duplicated, the first of approximately 7 KV for focusing on the center portion of the CRT device on the secondary side of the flyback transformer to apply the focusing power. A second focusing grid power supply having a low voltage level for focusing on the focusing grid power supply and the corner portion of the CRT apparatus should be generated. Typically, when the flyback transformer is mounted on a television, the flyback transformer is manufactured in a modular structure, and in the modular structure, an adjustment knob for regulating and outputting a control grid power supply and an adjustment knob for regulating and outputting a focusing grid power supply are provided. However, in order to adjust and output the redundant first and second focusing grid power supplies for focusing the center and corner portions of the CRT apparatus, additional adjustment knobs must be provided, thereby increasing the manufacturing cost of the flyback transformer. It is a situation.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and the collector voltage obtained at the collector side of the horizontal output transistor is adjusted to a low voltage level so that it is superimposed on the focusing grid power source generated by the flyback transformer so as to overlap the center and corner portions of the CRT apparatus. It is an object of the present invention to provide a double focusing apparatus of a television for enabling dual focusing.

In order to achieve the above object, according to a preferred embodiment of the present invention, the R / G / B electron gun radiating an R / G / B color beam corresponding to the R / G / B color component of the video signal, and the R / G A CRT device having a focusing electrode for focusing a / B color beam and an anode electrode for accelerating the R / G / B color beam, comprising: between a collector side of a horizontal output transistor and one end of a primary side of a flyback transformer; A rectifier diode and a smoothing capacitor connected to a DC voltage leveler of the horizontal output transistor, a zener diode for adjusting the DC leveled power supply to a low voltage level by a rating, and the flyback from the leveled power supply. It has a period corresponding to the horizontal scanning period of the CRT apparatus superimposed on the focusing voltage applied from the transformer to the focusing grid, the potential of the center portion of the CRT apparatus has a minimum level A multi-power regulator for generating a subfocusing voltage having a parabolic waveform gradually rising to the edge portion and a focusing voltage applied from the flyback transformer to the focusing grid from the sub-focusing voltage generated in the multi-power regulator; Provided is a dual focusing apparatus for a television including a focus voltage overlapping processor overlapping a voltage.

According to the dual focusing apparatus of the television according to the present invention having the above-described configuration, the collector voltage appearing on the collector side of the horizontal output transistor that is turned on / off in response to the horizontal drive signal is rated at a low voltage by means of a zener diode and then The rated low voltage is kept at the lowest potential in the focusing timing of the central part of the CRT device, while the nearer corner of the CRT device gradually increases the potential, that is, the parabola waveform subfocusing voltage, which is focused on the central part of the CRT device. Double focusing of the CRT device is performed by superimposing on the main focusing voltage from the flyback transformer for the CRT.

1 is a schematic diagram for explaining a focusing operation in a CRT apparatus employed in a conventional television;

2 is a view showing the configuration of a dual focusing apparatus of a television according to a preferred embodiment of the present invention;

3 is a view for explaining the waveform of the double focusing voltage by the double focusing device of the television according to the present invention.

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

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

18: flyback transformer, 28: smoothing capacitor,

30: zener diode, 32: multi-power regulator,

34: Focus voltage overlap processing unit.

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

2 is a view showing a power system to which the dual focusing apparatus of a television according to a preferred embodiment of the present invention is applied. In the same figure, reference numeral 10 denotes a switching ON / OFF in response to a horizontal drive signal applied from a horizontal drive circuit means (not shown), while a collector current and a collector voltage corresponding to the duty ratio of the horizontal synchronous signal are applied to the collector side. 12 and 14 denote damping diodes and capacitors for damping the collector current appearing on the collector side during switching ON / OFF of the horizontal output transistor 10, and 16 denotes the horizontal output transistors. The collector current which appears during switching ON / OFF of the transistor 10 shows a horizontal deflection coil for performing horizontal deflection with respect to the R / G / B color beam of the CRT apparatus. In FIG. 2, 18 shows that one end of the primary side is commonly connected to the collector side of the horizontal output transistor 10 so that the B + power supply intermittently flows in response to the switching ON / OFF cycle of the horizontal output transistor 10. As a result, a flyback transformer in which the image output DC power source (VDC) is obtained at the primary side and the transformer power source is induced at the secondary side is shown. The power source induced at the secondary side of the flyback transformer 18 is a high-voltage diode. Rectified at DC level at 20 to obtain a high voltage (AN) applied to the anode electrode of the CRT device, and to the focus grid of the CRT device according to the adjustment of the resistance value of the variable resistor 22 with respect to the high voltage (AN). The main focusing power supply MF applied is obtained, and the screen power supply SCREEN applied to the screen grid of the CRT apparatus is obtained by adjusting the resistance value of the variable resistor 24.

In addition, 26, 28, and 30 show a rectifying diode, a smoothing capacitor, and a zener diode for obtaining a subfocusing power source for double focusing for a CRT device to be realized in the present invention, wherein the rectifying diode 26 is the horizontal output transistor. The collector voltage shown on the collector side of (10) is actuated to DC level, and the smoothing capacitor 28 removes and smoothes the ripple component contained in the DC level power source rectified by the rectifying diode 26. The zener diode 30 serves to lower the DC power smoothed by the smoothing capacitor 28 to a rated voltage level.

In Fig. 2, reference numeral 32 denotes a multi-power regulator for generating a double focusing voltage for a CRT device to be implemented in the present invention, and the multi-power regulator 32 is shown in Fig. 3 at a timing of one horizontal scanning period. The sub-focusing voltage of the illustrated parabola waveform is generated. That is, the multi-power regulator 32 allows the lowest power level (eg, approximately 5V) to be maintained for the center portion of the CRT apparatus during one horizontal scanning period, while at the left and right edges in the horizontal direction of the CRT apparatus. Is generated at a multilevel power supply voltage such that a higher power supply level (e.g., approximately 8V) is maintained.

In addition, 34 in FIG. 2 shows a focus voltage overlapping processor for outputting a parabola waveform subfocusing voltage generated by the multi-power regulator 32 so as to overlap the main focusing voltage generated through the variable resistor 22.

Next, the operation of the double focusing device of the television according to the present invention having the above-described configuration will be described in detail.

First, under the operating environment of the television, the B + power is applied to the primary side of the flyback transformer 18, while the horizontal drive signal oscillated from the horizontal drive circuit is applied to the base side of the horizontal output transistor 10. The horizontal output transistor 10 performs a switching ON / OFF function according to the duty ratio of the horizontal drive signal. The current flows intermittently to the primary side of the flyback transformer 18 according to the switching ON / OFF action of the horizontal output transistor 10, and the collector current and the collector voltage of the horizontal output transistor 10 are induced, An image output voltage VDC to be applied to an image processing system for reproducing a signal is obtained. In addition, the power source induced in the secondary side of the flyback transformer 18 is rectified by the high-voltage diode 20 and output to the high-voltage anode power source (AN) applied to the anode electrode of the CRT apparatus, the high-voltage anode power supply (AN) is obtained as the main focusing voltage MF for focusing on the center portion of the CRT apparatus by adjusting the variable resistor 22 and applied to the screen grid of the CRT apparatus by adjusting the variable resistor 24. The screen voltage is obtained.

On the other hand, the collector voltage appearing on the collector side of the horizontal output transistor 10 is rectified at the rectifying diode 26 to be DC leveled, and the DC leveled power is charged / discharged in the smoothing capacitor 28. The smoothed power supply is adjusted to a low voltage level by the rating of the zener diode 30 and applied to the multi-power regulator 32.

Accordingly, the multi-power regulator 32 generates the sub-focusing voltage SF of the parabola waveform shown in FIG. 3 corresponding to the horizontal scanning period of the CRT apparatus, that is, the sub-focusing voltage SF is the CRT. The scan interval for the center of the device is maintained at a minimum potential (e.g., 5V), while increasing as it approaches the horizontal edge of the CRT device, and set to maintain a maximum potential (e.g., 8V) at the outermost corner. .

The sub-focusing voltage SF of the parabola waveform generated by the multi-power regulator 32 is obtained from the secondary variable resistor 22 of the flyback transformer 18 through the focus voltage overlapping processor 34. Superimposed on (MF), it is applied to the focusing grid of the CRT apparatus.

Therefore, the R / G / B color beams focused by the focusing grid of the CRT apparatus are parabolic in the horizontal scanning period in the multi-power regulator 32 at the substantially constant main focusing voltage MF (approximately 7 KV) shown in FIG. The double focusing action by the sub-focusing voltage SF (generally 5V-8V) generated by the waveform is applied, so that the luminance of the horizontal edge portion and the center portion of the CRT apparatus is substantially uniform.

On the other hand, the present invention is not limited to the above-described example, if the sub-focusing power is superimposed on the main focusing power supply so that the double focusing function is performed, the present invention may be modified without departing from the technical gist and the gist of the invention. Of course it can.

As described above, according to the dual focusing apparatus of a television according to the present invention, a parabolic waveform is generally applied at the center and corner portions in the horizontal direction of the CRT apparatus at a main focusing voltage of a substantially constant potential applied to a single focusing grid employed in the CRT apparatus. By superimposing the subfocusing voltages having the potential level of, it is possible to eliminate the difference in luminance at the center and corners of the CRT apparatus by a single focusing grid, which makes it unnecessary to employ a double focusing grid in the CRT apparatus. Due to the double focusing function, deterioration of image quality can be prevented.

Claims (1)

An R / G / B electron gun radiating an R / G / B color beam corresponding to an R / G / B color component of an image signal, a focusing electrode for focusing the R / G / B color beam, and the R / G In the CRT apparatus having an anode electrode for accelerating the / B color beam, A rectifying diode 26 and a smoothing capacitor connected between the collector side of the horizontal output transistor 10 and one end of the primary side of the flyback transformer 18 to DC level the collector voltage of the horizontal output transistor 10. With 28, Zener diode 30 for adjusting the DC leveled power to a low voltage level by rating, Has a period corresponding to the horizontal scanning period of the CRT apparatus which is superimposed on the focusing voltage applied from the flyback transformer 18 to the focusing grid from the level-adjusted power supply, and the potential of the central portion of the CRT apparatus is at a minimum level. And a multi-power regulator 32 for generating a subfocusing voltage having a parabolic waveform that gradually rises in level as it approaches a corner. And a focus voltage overlapping processor (34) which superimposes the subfocusing voltage generated by the multi-power regulator (32) on the focusing voltage applied from the flyback transformer (18) to the focusing grid. Dual focusing device.

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