JP3134316B2 - CRT - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cathode ray tube provided with a correction means for correcting the convergence state of an electron beam, and more particularly to an improved technique of the correction means.

[0002]

2. Description of the Related Art The deflection magnetic field distribution of a deflection yoke of a cathode ray tube is not a uniform magnetic field but is intentionally distorted for reasons such as reduction of graphic distortion. In particular, in a color cathode ray tube, a larger distortion is often formed in order to correct the occurrence of a concentration error due to the distortion of the deflection magnetic field.

However, the distortion of the deflecting magnetic field has a great influence on the focusing state of the electron beam. For example, in the case of CFD (convergence free DY), astigmatism occurs in which the focus is just focused at the center of the screen surface, but becomes front-focused (over-focus) in the vertical direction at the corner.

Conventionally, in order to solve this problem, a dynamic focus correcting means and a dynamic quadrupole correcting means are provided at the position of the electron gun, and both means are dynamically driven so that the entire screen surface is only horizontal. It is configured to converge in the vertical direction as well.

[0005]

However, since the position of the dynamic quadrupole correcting means and the position of the deflection yoke are different, even if the electron beam is converged, the image magnification in the horizontal and vertical directions is increased. Are different. For this reason, the spot of the electron beam is not a circle but a horizontally elongated one, which is a cause of deteriorating the image quality. Here, it is conceivable to move the position of the dynamic quadrupole correction means in the vicinity of the deflection yoke, for example in the case of a color cathode ray tube is practically difficult because of interference or the like to the current in the state.

Accordingly, an object of the present invention is to provide a cathode ray tube in which an electron beam converges on a screen surface with the same image magnification in the horizontal and vertical directions.

[0007]

A CRT according to the present invention for solving the above-mentioned problems is an electron gun for emitting an electron beam toward a screen surface.
Between the three electron beams between the screen and the screen
An electron gun that emits an electron beam, a deflection yoke that forms a deflection magnetic field in a space through which the electron beam passes, and a dynamic focus correction unit that corrects the convergence state of the electron beam by applying a voltage in synchronization with scanning of the electron beam. And a dynamic quadrupole corrector, wherein the dynamic quadrupole corrector is provided divided into a plurality of positions, and the virtual dynamics obtained by synthesizing the correction contents of the plurality of dynamic quadrupole correctors. The quadrupole correcting means is configured to be at the position of the deflection yoke.

[0008]

The electron beam emitted from the electron gun is subjected to a predetermined deflecting action by the deflection yoke, and the horizontal and vertical deflection states are corrected by the dynamic focus correction means and the dynamic quadrupole correction means. And the dynamic quadrupole corrector is divided into a plurality of locations, and the virtual dynamic quadrupole corrector obtained by correcting and combining the positions is at the position of the deflection yoke. The image magnification in the direction becomes the same.

[0009]

Embodiments of the present invention will be described below with reference to the drawings. 1 to 3 show an embodiment of the present invention. FIG. 1 is a diagram for explaining the concept of the present invention by replacing the operation of each means with a lens. In FIG. 1, an electron gun 1 and a screen surface 2
And the deflection yoke 3 is replaced by a lens. When the deflection yoke 3 is replaced with a lens, the deflection yoke 3 has a convex lens portion 3a in the vertical direction.
The horizontal direction acts as the concave lens portion 3b.

A dynamic focus correction means 5 and dynamic quadrupole correction means 6, 7 are provided inside the electron gun 1 together with the main lens 4, and these means 5, 6, 7 are synchronized with electron beam scanning. Voltage is applied. When replaced by a lens, the dynamic focus correction means 5 functions as a concave lens portion 5a in both the vertical and horizontal directions. The dynamic quadrupole correctors 6 and 7 are divided into two parts and arranged. When one dynamic quadrupole corrector 6 is replaced with a lens, the vertical direction is a concave lens portion 6a and the horizontal direction is a convex lens portion 6b. Is driven so that the vertical direction becomes the convex lens portion 7a and the horizontal direction becomes the concave lens portion 7b. Then, as shown in FIG. 2, a single virtual dynamic quadrupole corrector 8 obtained by synthesizing the correction contents of the two dynamic quadrupole correctors 6 and 7 is equivalently replaced with the position of the deflection yoke 3. The strength is controlled so that

In the above configuration, the electron beam emitted from the electron gun 1 undergoes a predetermined deflection by the deflection yoke 3 and is moved in the horizontal and vertical directions by the dynamic focus correction means 5 and the two dynamic quadrupole correction means 6 and 7. Are corrected, and the electron beam is converged at one point on the screen surface 2 in both the horizontal and vertical directions.

The virtual dynamic quadrupole corrector 8 obtained by correcting and combining the two dynamic quadrupole correctors 6 and 7 becomes the position of the deflection yoke 3, and the position where astigmatism occurs and the position where the astigmatism occurs are determined. Since the positions to be corrected match, a beam spot having the same image magnification in the horizontal and vertical directions is obtained.

FIG. 3 shows a specific example in which the dynamic quadrupole correcting means 6 and 7 are electrostatically constituted by a trinitron method. In the case of the trinitron method, the position where dynamic quadrupole correction can be performed is (1) near G2 where three beams are completely separated, and (2) the main lens center (3) where three beams are completely matched. 3) Three places near the convergence plate where the three beams are completely separated. The position (2) is a position where the dynamic quadrupole correction means 7 is conventionally provided, and if it is newly added, it is the position (1) or (3). In the position (3), electrostatic correction is performed under a high voltage potential.
Power supply and circuit are difficult. Therefore, the position of (1), that is, for example, the vicinity of G2 is, for example, a prefocus system. As shown in FIG. 3, another dynamic quadrupole corrector 6 is disposed at this position. Then, the dynamic voltage to be supplied can be shared as shown in the figure. or,
One or both of the two dynamic quadrupole correction means 6 and 7 may be constituted by magnetic means using an electromagnetic coil.

[0014]

As described above, according to the present invention, the electronic
An electron gun that fires a beam toward the screen
Between the electron gun and the screen surface.
An electron gun that fires an electron beam where the beams intersect,
Deflection yoke for forming a deflection magnetic field in the beam passage space
Voltage is applied in synchronization with the scanning of the electron beam,
Dynamic focus compensation to correct beam focusing
Bra with positive means and dynamic quadrupole correction means
The dynamic quadrupole corrector is divided into a plurality of positions, and a single virtual dynamic quadrupole corrector obtained by correcting and combining the plurality of dynamic quadrupole correctors is provided at the position of the deflection yoke. As a result, the position at which astigmatism occurs and the position at which the astigmatism is corrected coincide with each other, so that the electron beam converges to one point with the same horizontal and vertical image magnification.

[Brief description of the drawings]

FIG. 1 illustrates a concept of the present invention.

FIG. 2 is a diagram showing a virtual dynamic quadrupole corrector obtained by correction synthesis of two dynamic quadrupole correctors.

FIG. 3 is a diagram showing a specific configuration in the case of a trinitron method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Electron gun 2 ... Screen surface 3 ... Deflection yoke 5 ... Dynamic focus correction means 6, 7 ... Dynamic quadrupole correction means 8 ... Virtual dynamic quadrupole correction means

Claims (1)

(57) [Claims] 1. An electron gun for emitting an electron beam toward a screen surface, comprising: the electron gun and the screen.
Launches an electron beam where three electron beams intersect
An electron gun , a deflection yoke for forming a deflection magnetic field in a passage space of the electron beam, a dynamic focus correction means for applying a voltage in synchronization with the scanning of the electron beam to correct the convergence state of the electron beam, and a dynamic quadruple. A dynamic dynamic quadrupole correction obtained by synthesizing correction contents of the plurality of dynamic quadrupole correction means, wherein the dynamic quadrupole correction means is provided at a plurality of positions. A cathode ray tube, wherein the means is arranged at the position of the deflection yoke.