KR940007249B1 - Dynamic focus electron gun for c-crt - Google Patents

Abstract

The dynamic focus electron gun includes a cathode, a control electrode, a screen electrode, and other electrodes for forming first and second unipotential static lenses, wherein a positive dynamic focus voltage is applied to the central electrode of the first unipotential static lens in synchronization with a deflection signal, and a negative dynamic focus voltage is applied to the central electrode of the second unipotential static lens in synchronization with the deflection signal, thereby correcting the distortion of the electron beams.

Description

Dynamic Focus Gun for Color Cathode Ray Tubes

1 is a cross-sectional view of a dynamic focus electron gun for a color cathode ray tube according to the present invention, showing a voltage application state.

2 is a diagram illustrating a voltage waveform of a dynamic focus voltage applied to the second focus electrode and the fourth focus electrode of the electron gun.

* Explanation of symbols for the main parts of the drawings

2: cathode 3: control electrode

4 screen electrode 5 first focus electrode

6: second focus electrode 7: third focus electrode

8: fourth focus electrode 9: fifth focus electrode

8H: electron beam through hole 11: final acceleration electrode

Vf: Focus voltage Vs: Constant voltage

Vd ₁ : first dynamic focus voltage Vd ₂ : second dynamic focus voltage

The present invention relates to an electron gun for a color cathode ray tube, and more particularly, to a dynamic focus electron gun capable of uniformly forming a cross section of an electron beam landing on a fluorescent film to improve astigmatism and focus characteristics.

Typically, the electron gun provided in the neck portion of the cathode ray tube is of various kinds depending on the method of applying the potential to each electrode constituting the cathode, in particular, at least one electrode constituting the electron gun in synchronization with the signal of the deflection yoke The dynamic focus electron gun, which applies a focus voltage to improve focus characteristics, has a high voltage driving method for applying a dynamic focus voltage to one electrode in which the focus electrode is divided, and a dynamic focus to an electrode to which the electrostatic lens of the electron gun is multi-stage and low voltage is applied. The high voltage dynamic focus electron gun has a very good dynamic focus characteristic and astigmatism correction effect, but has the following problems.

First: A separate voltage higher than the voltage applied to the focus electrode for connecting and accelerating the electron beam is required.

Second: It is difficult to apply the dynamic focus voltage superimposed on the ground voltage applied to the dynamic focus electrode.

Third: Since the intensity of the main lens is weakened according to the dynamic focus voltage, the convergence characteristic of the main lens, in particular, the decentralization characteristic at the periphery of the screen is deteriorated, resulting in poor convergence of the three electron beams.

Fourth: As the screen becomes larger and the angle of deflection becomes larger, the distortion of the electron beam spot due to the self-convergence deflection magnetic field appears severely and the incident angle of the electron beam on the screen is small. Will be lowered.

The low-voltage driving dynamic focus electron gun has advantages in that it is easier to implement circuits and has better withstand voltage characteristics than the high-voltage driving electron gun described above. Will.

The present invention was created to solve the above problems, and uniformly spreads the electron beam spots landing on the fluorescent film in the entire region of the fluorescent film, thereby improving focus characteristics and astigmatism and improving screen resolution. The purpose is to provide a focus electron gun.

In order to achieve the above object, according to the present invention, a cathode, a control electrode, and a screen electrode constituting the pre-triode tube portion, a plurality of electrodes constituting the first universal electrostatic lens and a plurality of electrodes constituting the second universal potential lens are sequentially In a dynamic focus electron gun for color cathode ray tubes arranged in a manner, a dynamic focus voltage having positive polarity is applied to an electrode located in the center of the electrodes forming the first universal electrostatic lens in synchronization with a deflection signal, and the second A dynamic focusing voltage having a negative polarity is applied to an electrode positioned at the center of the electrodes of the unipotential electrostatic lens in synchronization with a deflection signal.

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

The electron gun for the color cathode ray tube according to the present invention is installed so as to be adjacent to the cathode (2), the control electrode (3) and the screen electrode (4), and the screen electrode (4) forming the pre-triode tube portion as shown in FIG. The first focusing electrostatic lens is disposed adjacent to the second focusing electrodes 5, 6 and the third focusing electrode 7 to form the second focusing electrostatic lens. In addition to the fifth focusing electrode 9 and the fourth focusing electrode 8, a final acceleration electrode 11 forming a bipotential type electrostatic lens is provided. Herein, the electron beam through hole 6H of the second focus electrode 6 has a horizontal shape, and the electron beam through hole 8H of the fourth focus electrode 8 has a longitudinal shape. Preferably, the two focus electrodes 6 are divided into a plurality of electrodes. A predetermined potential is applied to each of the electrodes, and a predetermined focus voltage Vf is applied to the first, third and fifth focus electrodes 5, 7, and 9, and to the screen electrode 4. The constant voltage Vs lower than the focus voltage Vf is applied. As shown in FIG. 2, the second focus electrode 6 includes a first dynamic focus voltage higher than the constant voltage Vs, lower than the focus voltage Vf, synchronous with a deflection signal, and having positive polarity (+). Vd ₁ ) is applied to the fourth focusing electrode 8, and a second dynamic focus voltage Vd ₂ having a potential lower than the constant voltage Vs is synchronized with the deflection synchronization signal and has a negative polarity (−). An anode voltage Ve higher than the focus voltage Vf is applied to the final acceleration electrode 11.

The operation of the dynamic focus electron gun for a cathode ray tube according to the present invention configured as described above is as follows.

When a predetermined potential is applied to each electrode constituting the dynamic focus electron gun, a prefocus electrostatic lens is formed between the screen electrode 4 and the first focus electrode 5, and the second and fourth focus electrodes are formed. (6) First, second and third focus electrodes (5) with or without dynamic focus voltage (Vd ₁ ) (Vd ₂ ) applied to (8) (6) (7) and third, fourth and fifth focus electrodes (7) Between the (8) and (9), a first universal electrostatic lens and a second universal electrostatic lens are formed, respectively.

As described above, the action on the electron beam emitted from the cathode 2 of the dynamic focus electron gun in which the electrostatic lens is formed is divided into the time of scanning the center of the fluorescent film and the peripheral part of the fluorescent film.

First, when the electron beam emitted from the cathode 2 of the electron gun is scanned to the center portion of the fluorescent film, the second focusing electrode 6 and the fourth focusing electrode 8 have first and second dynamic focus voltages synchronized with a deflection signal. Since (Vd _l ) (Vd ₂ ) is not applied, the first and second potential type electrostatic lenses are strongly formed. Therefore, the electron beam emitted from the cathode 2 is prefocused and accelerated at the prefocus electrode formed between the screen electrode 4 and the first focus electrode 5, and the The electron beam passing holes 6H of the second focus electrode 6 are formed in a horizontal shape and the electron beam passing holes 8H of the fourth focus electrode 8 are formed in an elongated shape. The electron beam passing through the unpotential type electrostatic lens is strongly focused in the vertical direction, and the electron beam passing through the second potential type electrostatic lens is strongly focused in the horizontal direction, and then between the fifth focus electrode 9 and the final acceleration electrode 11. After incident on the capacitive lens formed at the final focusing and acceleration, it lands at the best state in the center of the fluorescent film.

When the electron beam emitted from the cathode 2 is scanned to the periphery of the fluorescent film, the second focusing electrode 6 and the fourth focusing electrode 8 of the electrodes forming the first and second universal electrostatic lenses are formed. Since the first positive dynamic focus voltage Vd _l and the negative second dynamic focus voltage Vd ₂ are synchronized with the deflection synchronization signal, the first and second potential electrostatic lenses are respectively applied. The strength of is relatively weak. Therefore, the electron beam emitted from the cathode 2 passes through the first universal electrostatic lens after being pre-focused and accelerated in the prefocus lens, and the electron beam that passes through this becomes longer in focal length in the vertical direction of the electron beam and is deflected. The distortion caused by the deflection aberration of the yoke is corrected, and the electron beam passing through the second potential electrostatic lens and passing through the second potential electrostatic lens is shortened in the horizontal focusing distance incident to the main lens. This prevents horizontal distortion due to aberration and horizontalization of the electron beam due to curvature of the screen surface.

As described above, the dynamic focus electron gun for a color cathode ray tube according to the present invention is a low voltage electron gun, which is synchronized with a deflection signal to a second focus electrode and a fourth focus electrode among the electrodes forming the first and second universal type electrostatic lenses. Since the 1,2 dynamic focus voltage is applied, the screen resolution is improved by correcting the distortion of the electron beam according to the deflection aberration and the curvature of the screen surface.

Claims (4)

A cathode for a color cathode ray tube in which a cathode, a control electrode, and a screen electrode constituting the pre-triode tube part, a plurality of electrodes constituting the first universal electrostatic lens and a plurality of electrodes constituting the second universal potential lens are sequentially arranged. In the focus electron gun, a dynamic focus voltage Vd ₁ having a positive polarity in synchronization with a deflection signal is applied to an electrode positioned at the center of the electrodes forming the first universal electrostatic lens, and the second potential is applied. A dynamic focus electron gun for color cathode ray tubes, characterized by applying a dynamic focus voltage (Vd ₂ ) having a negative polarity in synchronism with a deflection signal to an electrode located at the center of electrodes forming a type electrostatic lens. 2. The electron beam through hole of the electrode according to claim 1, wherein the electron beam through hole 6H of the electrode to which the positive dynamic focus voltage Vd ₁ is applied is formed in a horizontal shape and the electrode of the electrode to which the negative dynamic focus voltage Vd ₂ is applied is formed. A dynamic focus electron gun for a color cathode ray tube, wherein (8) is formed in an elongated shape. The color cathode ray tube of claim 1, wherein the positive dynamic focus voltage Vd ₁ is higher than the constant voltage and the negative dynamic focus voltage Vd ₂ is lower than the constant voltage. Dynamic focus gun The dynamic focus electron gun for color cathode ray tube according to claim 1, wherein a plurality of electrodes located at the center of the electrodes forming the first universal type electrostatic lens are separated and formed.