JPH0218839A - In-line type electron gun - Google Patents

Abstract

PURPOSE:To concurrently set three electron beams in the optimum focus state by forming the outer shape of at least one electrode of two electrodes constituting a main electron lens and facing each other narrow at the center and wide at peripheries. CONSTITUTION:Outer shapes 53 and 63 of two electrodes facing each other and constituting the main electron lens of the in-line type electron gun for a color picture tube are formed in an iron dumbbell shape. The quantity of the electric field corresponding to both outside electron beams affected by electrode short side walls is reduced, thus the distortion of the electric field is reduced, thus the diameter of the main electron lens is equivalently increased. The just focus voltage Ecs of both outside electron beams can be reduced than before and can be made equal to the just focus voltage Vcs of the center electron beam. Only either one of the outer shapes of the electrodes may be formed in the iron dumbbell shape.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an in-line electron gun for a color picture tube.

[Conventional technology]

The mainstream electron gun used in color picture tubes is the so-called unitized in-line type electron gun, in which the electrodes that make up the electron gun are formed integrally, and electron beam passage holes are arranged in-line. It has become.

Recently, in in-line color picture tubes, the eccentric distance S of the electron beams, which is the mutual spacing between the in-line array electron guns, has been reduced in order to improve the convergence characteristic of concentrating three electron beams on one point over the entire area on the phosphor screen. There is a tendency. However, if this eccentric distance is simply reduced, the spherical aberration of the main electron lens will increase, and the focusing characteristics and resolution of the electron beam will deteriorate. Therefore, in order to keep the eccentric distance S of the electron beam small and to increase the aperture of the main electron lens, the main electron lenses corresponding to each of the three electron beams in the inline array are overlapped with each other, and the diameter of the main electron lens is made to be equivalently large. Electrode structures have been proposed to obtain a main electron lens of aperture.

FIG. 3 is a cross-sectional view of an example of a conventional in-line electron gun. As shown in FIG.
Three electron beams 20a, 20b, 20c emitted from three cathodes la, lb, lc corresponding to each color of green and blue.
is G1 electrode 2. G2 electrode 3. Passing through the first 03 electrode 4, the second G.

Electrode 5. The light is focused by a superimposed large-diameter main electron lens composed of a first G4 electrode 6 and a second 04 electrode 7, passes through a shield cup 8, and reaches a phosphor screen (not shown).

FIGS. 4(a) and 4(b) are front views of the G electrode and the G4 electrode in FIG. 3.

FIG. 4(a) is a front view of the second 03 electrode 5 seen from the 04 electrode 6 side in FIG.
Three openings 9 corresponding to 0b and 20c are arranged in-line. Here, 21 is an insulating support rod for supporting and fixing the electrode.

The surfaces of the three openings 9 are located on the G4 electrode side of the second G3 electrode 5 at a position retreating from the protruding edge 51 that protrudes in a racetrack shape formed by connecting two semicircular arcs with parallel lines.

The inner diameter of the semicircular portions on both sides of the racetrack-shaped projecting edge portion 51 is R1, and the inner diameter of the opening 9 is Dl.

FIG. 4(b) is a view of the first 04 electrode 6 and the second G4 electrode 7 seen from the second 03 electrode 5 side in FIG. 3, and shows three electron beams 20a, 20b.

Three apertures 10 corresponding to 20c are arranged in-line. The surfaces of these three openings 10 are formed by an iron array-shaped protruding edge 61 that connects two semicircular arcs of the first G4 electrode protruding toward the second 03 electrode 5 side with a parallel line narrower than the diameter of the arc. It is in a retreating position.

The inner diameter of the semicircular arc on both sides of the iron array-shaped protrusion 61 is radius R2, and the inner diameter of the opening 10 is D2.

As shown in Figures 3 and 4 (a) and (b), by overlapping the main electron lenses corresponding to each of the three electron beams, a superimposed type large lens with an equivalently large aperture can be obtained. Aperture lenses can be obtained.

[Problem to be solved by the invention]

In the conventional electron gun as described above, in which a main electron lens corresponding to each of the three electron beams is superimposed on each other to obtain an equivalent large-diameter main electron lens,
There are the following problems.

Of the three in-line electron beams, the focus voltage (EC3 voltage) that makes the two electron beams on the farmer's side just focus on the screen is set to E C3s, and the center electron beam just focuses on the screen. If the focus voltage is Ec3c, E C3S > E
This is a problem with csc. The reason why this problem occurs is that the electric field of the main electron lens corresponding to both side electron beams is affected by the sidewalls on the short side, so the central electron beam is hardly affected by the sidewalls on the short side. The distortion becomes larger compared to the electric field of the main electron lens. As a result, the electric field of the main electron lens corresponding to both side electron beams is affected by the sidewall on the short side. The distortion becomes larger compared to the electric field. As a result, the main electron lens corresponding to both side electron beams has a smaller lens aperture than the main electron lens corresponding to the center electron beam. E C3S -
With #E CSC, it is not possible to bring the three electron beams into the optimum focus state at the same time, so a compromise focus state must be achieved.

An object of the present invention is to provide an in-line electron gun that can bring three electron beams into optimal focus at the same time.

[Means to solve the problem]

The present invention has three in-line arrays of apertures in each of two mutually opposing electrodes constituting the main electron lens,
In an in-line electron gun in which the opening is in a recessed part recessed from the protruding edge of each of the two electrodes that are closest to each other, the two electrodes that form the main electron lens face each other. The outer shape of at least one of the two electrodes is narrow at the center and wide at the periphery.

〔Example〕

Next, embodiments of the present invention will be described with reference to the drawings.

FIGS. 1(a) and 1(b) are a front view of the 03 electrode and the G4 electrode of one embodiment of the present invention.

FIG. 1(a) is a front view of the G3 electrode viewed from the G4 electrode side, and three apertures 9 corresponding to the three electron beams 20a, 20b and 20c are arranged in-line. The surfaces of the three openings 9 are located a certain distance back from the protruding edge 52 that protrudes in a racetrack shape toward the 04 electrode of the G3 electrode. The electrode outer shape 53 of the projecting edge portion 52 has an iron array shape in which approximately semicircular arcs are inserted by parallel lines narrower than the diameters of the semicircular arcs.

FIG. 1(b) is a front view of the 04 electrode viewed from the G electrode side, and shows three electron beams 20a, 20b, 20c.
Three apertures 10 corresponding to the above are arranged in-line. The surfaces of the three openings 10 are located a certain distance back from the protruding edge 62 that protrudes in an iron array shape toward the 63rd electrode of the G4 electrode. The electrode outer shape 63 of the projecting edge portion 62 has an iron array shape in which approximately semicircular arcs are inserted by parallel lines narrower than the diameters of the semicircular arcs.

The in-line electron gun for a color picture tube of this embodiment is similar to the conventional superimposed electron gun shown in FIG. It is the same as a large-caliber electron gun.

By making the outer shape of the electrodes constituting the main electron lens of this example into an iron array shape, the electric field corresponding to both side electron beams is less influenced by the short side walls of the electrodes, and therefore the distortion of the electric field is reduced. , so the main electron lens aperture becomes equivalently larger. Due to this, the just focus voltage E C3S of the electron beams on both sides can be lowered than in the conventional case, and eventually E C3S = E C,C.

In this embodiment, the outer shapes of the two electrodes constituting the main electron lens are both iron array shapes, but the same effect can be obtained even if only one of them is iron array shapes.

FIGS. 2(a) and 2(b) are front views of 63 electrodes and G4 electrodes of other embodiments of the present invention.

The shapes of the electrodes 53 and 63 are shown in FIG. 1(a).

Similar to the embodiment shown in (l), approximately semicircular arcs are connected in an iron array shape by parallel lines narrower than the diameter of the semicircular arc, and furthermore, both the ridge portion 52 and the ridge portion 62 have an iron array shape. It becomes.

In the embodiment described above, the apertures 9 and 1 through which the electron beam passes
Although 0 is a circular shape, the present invention is not limited to a circular shape; for example, an elliptical shape or an assembled shape of a circle and an ellipse can also be applied.

〔Effect of the invention〕

As explained above, the present invention provides a superimposed large-diameter electron gun in which the external shape of at least one of the two mutually opposing electrodes constituting the main electron lens is narrow at the center and wide at the periphery. By doing so, the amount by which the electric field corresponding to the electron beams on both sides is influenced by the short side walls of the electrode is reduced, so that the distortion of the electric field is reduced, and a main electron lens having an equivalently large diameter can be obtained. Therefore, the just focus voltage EC3S of both side electron beams is the just focus voltage E of the center electron beam. 3c, it is possible to bring the three electron beams into optimum focus at the same time without having to use a compromise focus level as in the conventional case.

[Brief explanation of the drawing]

FIGS. 1(a) and (b) are front views of the 03 electrode and G4 electrode of one embodiment of the present invention, and FIGS. 2(a) and (b) are G3 electrodes of another embodiment of the present invention. A front view of the electrode and a front view of the G4 electrode, FIG. 3 is a cross-sectional view of an example of a conventional in-line electron gun, and FIGS. 4(a) and (b) are front views of the G3 electrode and G4 electrode in FIG. It is a diagram. 1 a, 1 b, 1 c---cathode, 2 ・G
, electrode, 3...G2 electrode, 4...first 03 electrode,
5... Second G3 electrode, 6... First G4 electrode, 7
...Second G4 electrode, 8...Shield cup, 0...Opening hole, 20a. Edge support rod, Ob, 20c...electron beam, 21...absolute 51.5
2, 61.62... Projection edge, 53° 3... Electrode outer shape.

Claims (1)

[Claims] Each of the two mutually opposing electrodes constituting the main electron lens has three in-line apertures, and the apertures are located in the respective electrodes to which the two electrodes constituting the main electron lens are closest. In an in-line electron gun located in a recessed part receding from a projecting edge of the main electron lens, the outer shape of at least one of the two electrodes facing each other constituting the main electron lens is narrow in the center and wide in the periphery. An in-line electron gun characterized by: