KR950005661Y1 - Electron gun - Google Patents

Abstract

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Description

Electron gun for cathode ray tube

1 is a schematic diagram of an inline cathode ray tube.

2 is a perspective view of a configuration of an electron gun of a conventional inline cathode ray tube.

3 is a perspective view of the configuration of the electron gun of the present invention.

4 is a cross-sectional view of the main lens of the electron gun of the present invention.

5 is a screen beam state diagram of a conventional electron gun.

6 is a state diagram of the screen beam by the electron gun of the present invention.

* Explanation of symbols for main parts of the drawings

1: electron gun 4: shadow mask

5: fluorescent surface 6: electron beam

7, 8, 9: cathode 10: G1 electrode

11: G2 electrode 12, 12 ': G3 electrode

13, 13 ': G4 electrode 12a, 12'a, 12c, 12'c: outer hole

12b, 12'b, 13b, 13'b: center hole 13a, 13'a, 13c, 13'c: outer hole

The present invention relates to an electron gun for a cathode ray tube, and more particularly to an electrode constituting the main lens.

1 shows a typical CRT.

The three electron beams emitted by the electron gun 1 are imaged on the shadow mask 4 and subjected to color selection by the shadow mask 4, and only the component which excites and emits phosphors of a color corresponding to each beam is a shadow mask. Passing through the opening in (4), it reaches the fluorescent surface 5 to which red, green, and blue three-color phosphors were applied.

2 shows a conventional electron gun.

The three electron beams of red, green, and blue emitted to the cathodes (7) (8) (9) pass through the G1 electrode (10) and the acceleration electrode (G2) electrode (11), which constitute the main lens. ) And the electron beam through holes 12a, 12b, 12c and 13a, 13b, and 13c of the G4 electrode 13 are focused on the fluorescent surface 5 to form a pixel.

The electron beam passing holes 12a, 12b and 12c of the G3 electrode 12 of the conventional electron gun are formed in a circle having the same radius (R1 = R2 = R3), and the electron beam passing through the G4 electrode 12. The balls 13a, 13b and 13c are formed in a circular shape in which the radius R4 = R6 of the through holes 13a and 13c on both outer sides is larger than the radius R5 of the center passage hole 13b.

As shown in FIG. 5 by the main lens of this shape, the degree of distortion becomes larger as the electron beam goes toward the periphery of the fluorescent surface 5 by the focusing action by the main lens.

As a factor that greatly influences the focus characteristic of the columnar correlator, there are lens magnification and aberration of the main lens, and these are highly dependent on the intensity of focusing of the lens.

In the picture tube, determining the scanning area and the maximum deflection angle of the electron beam determines the distance from the main lens to the image plane. Under a condition where the distance of the image plane branch is constant, weakening the lens focusing action causes a reduction in the lens magnification, and furthermore, it suppresses the spread of the beam in the main lens to a constant value in order to prevent an increase in deflection aberration. Adding a condition lowers the beam incidence angle to the main lens.

If the beam incidence angle is αi, the minimum confusion circle diameter δ due to the spherical aberration most predominant among the aberrations of the main lens is It is expressed by, and spherical aberration can be reduced by decreasing the beam incident angle. Where M is the lens magnification and C is the spherical aberration coefficient.

As described above, in the receiving tube, if the lens focusing action of the main lens is weakened, the lens magnification and spherical aberration are reduced, and the focus characteristic is improved.

One way to weaken the focusing action is to enlarge the diameters of the openings (beam through holes) of the G3 and G4 electrodes forming the main lens.

However, in the in-line residual gun, the main lenses corresponding to each of the three colors of red, green, and blue are arranged in the same plane, so that the opening diameter is 1/3 of the inner diameter of the neck portion accommodating the electron gun. It should be

Therefore, when the inner diameter of the neck portion is enlarged, the deflection power increases, and in general, when the diameter of the aperture portion is enlarged, the eccentric distance of the aperture portion becomes large, and a problem that the convergence characteristic of the beam deteriorates. For this reason, it is difficult to enlarge the diameter of a perforation part more than a certain degree.

The present invention can effectively increase the diameters of the electron beam passing holes of the G3 electrode and the G4 electrode even when the external shape of the electron gun is restricted by the inner diameter of the neck portion, and thus the cathode ray can improve the focus characteristic. To provide a conventional gun.

In order to achieve the above object, the present invention forms a non-circular electron beam through hole of the G3 electrode and G4 electrode, the through hole in the center by connecting the shortcomings of the two arcs in two parallel straight lines than the diameter in the horizontal direction The length of the vertical direction is increased, and the beam passing holes on both sides have an outer arc and an inner straight line, respectively. In the semicircle connected to two horizontal lines below, the effect of substantially increasing the diameter of the beam passing hole is generated, and the lens focusing action is weakened, thereby improving the focus characteristic.

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

3 shows the electron gun of the present invention, wherein the hot electrons emitted from the cathodes 7, 8, 9 are controlled by the G1 electrode 10 and accelerated by the G2 electrode 11 to form the main lens. The fluorescent surface 5 is focused by the G3 electrode 12 'and the G4 electrode 13'.

A hole 12'b through which the central beam passes and a hole 12'a and 12'c through which the outer beam passes are formed in the G3 electrode 12 ', and the G4 electrode 13' has a hole in the center beam 12'b. The opening 13'b passing through and the opening 13'a, 13'c through which the outer beam passes are formed.

In this embodiment, the shape and the dimensions of the openings corresponding to each other of the G3 electrode 12 'and the G4 electrode 13' are the same.

The central opening 12'b of the G3 electrode 12 'and the central opening 13'b of the G4 electrode 13' have a shape in which the shortcomings of two circular arcs are connected by two parallel lines. The longitudinal length 14 is also longer than the horizontal length 15.

The outer opening 12'a (12'c) of the G3 electrode 12 'and the outer opening 13'a (13'c) of the G4 electrode 13' are respectively formed in the center opening 12'b. It is a shape which connected the straight line which opposes each of the two straight lines of 13'b, and the circular arc which has a curvature radius larger than the said circular arc.

By the shape of the openings, the diameters of the electron beam passing holes of the G3 electrode 12 'and the G4 electrode 13' can be substantially enlarged with respect to the inner diameter of the same neck portion.

Therefore, the focusing function of the main lens is weakened, thereby improving the focus characteristic.

On the other hand, the center beam through hole 12'b (13'b) of the G3 electrode and the G4 electrode of the present invention has a longitudinal shape longer than the horizontal length, and both outer holes 12'a (12'c). Since the horizontal lengths of (13'a) and (13'c) are formed more than the center opening 12'b (13'b), as shown in FIG. Since a beam close to a circle is formed at, a good image quality can be obtained.

Claims (1)

In an electron gun for a cathode ray tube having a triode tube part for generating an electron beam and a main lens for focusing the electron beam, the electrode forming the main lens is a species in which a central beam passes and two vertical lines and two circular arcs are connected in a horizontal direction. An electron gun for a cathode ray tube, characterized in that it has a long central opening and a semicircular outer opening formed on both sides by connecting two horizontal straight lines and an outer side and an inner vertical line by an arc.