JPS6240135A - Inline-type electron gun - Google Patents

Abstract

PURPOSE:To correct the imbalance of the diffractive force of the convergent electrode by installing walls of given height extending in the Y axis direction outside side penetrating holes formed in the first acceleration electrode and making the point on which the outer X axis components of side electron beams are diverged more apart from the main lens than the point on which the inner components are diverged. CONSTITUTION:Since the outer wall surfaces of rectangular recesses 17r and 17b surrounding penetrating holes 5r and 5b are nearer to the holes 5r and 5b than the inner wall surfaces, the outer X axis direction divergence angles of electron beam (R) and (B) are larger than their inner X axis direction divergence angles. Therefore, the cross over point of the outer components of the electron beams (R) and (B) become more apart from a cathode 3 and nearer to a main lens 12 than their inner components. As the result, the point on which the outer components are diverged by a main lens 12 becomes more apart from the point on which the inner components are diverged and as the result the imbalance of the main lens 12 is corrected. Since this correctioni effect increases as the wall surfaces of the recesses 17r and 17b are closer to the penetrating holes 5r and 5b and as the depth of the recesses 17r and 17b or the height of the wall surfaces is larger, the size of each recess is properly adjusted.

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to an in-line electron gun for a color cathode ray tube, and particularly relates to improving its convergence characteristics.

[Prior Art] Figure t52 is a vertical cross-sectional view of a conventional in-line electron gun (1), in which (2) is a heater, (3) is a cathode, (4) is a control electrode G+, and (5) is a first electrode. Accelerating electrode G2, (8),
(7) is the first electrode constituting the focusing electrode G3. The second member, (
8) and (9) are the first. The second member (10) is an attached electrode (II+?).

(1IG) and (11B) are electric field lenses (hereinafter referred to as brilenses) formed at the through holes (8r), (8g), and (8b) formed in the member (8).
, (12) is member (7).

(8) is an electric field lens (hereinafter referred to as the main lens) formed by the lens.

FIG. 3(a) is a front view of the conventional control electrode G1, and FIG. 3(b) is a front view of the conventional control electrode G1.
) is a cross-sectional view taken along line B-B, and the through holes (4r), (4g), and (4b) through which the electron beams R, G, and B pass are circular, and the electron beams passing through these holes are The cross-sectional shape is also circular, and after passing through the circular through-hole of the first accelerating electrode G2 and the pre-lenses (IIR), (IIG), and (11B), the electron beams have a circular cross-section and diverge uniformly in each direction. and enters the main lens (12).

It converges and hits the fluorescent screen. The dash-dotted line in Figure 2 is
The central paths of electron beams R, G, and B are shown, respectively. Hereinafter, the convergence effect of the main lens (12) will be described with the direction in which the electron beams R, G, and B are arranged as the X axis, the direction perpendicular to the X axis as the Y axis, and the direction in which each electron beam advances as the X axis.

Figure 4(a) shows the member (7) constituting the main lens (12).
, (8) is an enlarged cross-sectional view, and (b) is a front view of the member (7), taken along the line bb. Through hole (7r).

(7g) and (?b) are formed at equal intervals on the X axis,
An oval wall surface (7w) is formed to surround them. The other member (8) constituting the main lens (12) is also formed symmetrically with the first member (7). The broken lines in Figure 0 indicate equipotential surfaces, and this main lens (12) is aligned with the X-axis. A rotationally asymmetric electric field lens whose direction is longer than the Y-axis direction is formed.

FIG. 5 is a schematic diagram showing the configuration of the main lens (12) as an optical lens system, with (13R), (13G),
(13B) are through holes (7r), (7g), and
(14) is a rotationally asymmetric common lens formed between members (7) and (8), (15R) and (15G).

(15B) are the through holes (8r) of the member (8),
(8g).

This is a small lens formed in the part (8b).

[Problems to be Solved by the Invention] Since the common lens (14) is a rotationally asymmetric electric field lens, the focusing electrode G3 has the following refractive power imbalance.

■The refractive power in the Y-axis direction is stronger than the refractive power in the X-axis direction (astigmatism).

■The refractive power in the X-axis direction is stronger on both sides than in the center (spherical aberration).

(2) Regarding the refractive power in the X-axis direction that acts on the electron beams R and B passing through the through holes on both sides, the refractive power in the direction from the outside to the center is stronger than the refractive power in the direction from the center to the outside.

Arrows Fl, F2°F3 in Fig. 4(a) and Fig. 5 indicate the strength of the refractive power in the X-axis direction acting on each electron beam R, G, H, and For the reason, Fl>F
The relationship is 2>F3.

Figure 6 shows electron beams R, G, and B focused on the phosphor screen.
This is a diagram showing an example of the spot shape of the electron beam.Due to the above reasons, the spot shape of each electron beam is not circular.Furthermore, the electron beams R and H have different directions of refractive power F1 due to the above reason. /\Row H joins.

- Since the spot shape of each electron beam is not circular in this way, there are problems in that resolution decreases, contrast decreases, and color shift occurs.

The present invention was made to solve these problems, and aims to provide an electron gun that corrects the imbalance described in (2) above.

[Means for Solving the Problems] In the in-line electron gun according to the present invention, the three electron beams are formed in the first accelerating electrode, and the holes on both sides of the throughhole through which the electron beams pass are formed on the outside of the throughhole through which the electron beams pass. Wall bodies extending in the Y-axis direction are provided on the surfaces facing the focusing electrodes.

[Function] The walls provided on the outside of the through holes on both sides make the divergence angle of the outside component of the X-axis of the electron beam smaller than the divergence angle of the inside component, and the farther away from the cathode than that of the component (closer to the main lens)
, acts to move the convergence point (image point) of the outer component by the main lens farther from the main lens than the convergence point of the inner component.

As a result, the above imbalance of the main lens (12) can be corrected.

[Embodiments of the Invention] FIG. 1(a) is a front view of an embodiment of the first accelerating electrode G2 constituting the main part of the present invention, and FIG. 1(b) is a sectional view taken along the line bb. In a certain 0 diagram, (17r), (1?b
) are rectangular recesses formed on the surface facing the focusing electrode G3 following the through holes (5r) and (5b), respectively, and are provided at eccentric positions toward the center. (17g) is a rectangular recess formed following the through hole (5g), and is coaxial with the second through hole (5g).Next, the function of this recess will be explained.

The recess (17g) provided in the center hole (5g) is
5g), the wall surface on the X axis and the wall surface on the Y axis are located at the same distance from each other, so that there is no imbalance in the divergence angle of the electron beam G. However, the through holes (5r) on both sides, (
5b), the rectangular recess (17r), (1?b)
), the outside is close to the through holes (5r) and (5b) and the inside is far away, so the divergence angle of the electron beams R and B in the X-axis direction is small on the outside and large on the inside. This is because the crossover point of the outer components of the electron beams R, B is farther from the cathode (3) than that of the inner component, that is, closer to the main lens (12). Since the convergence point of the outer component is farther away from the main lens than the convergence point of the inner component, there is an effect of correcting the above-mentioned imbalance of the main lens (I2).

This effect increases as the wall surfaces of the recesses (17r), (17b) approach the through holes, and the wall surfaces of the recesses (17r), (17b)
17b) depth.

That is, the higher the height of the wall surface, the stronger it becomes, so by appropriately setting the size of each recess, it is possible to obtain an electron gun that corrects the imbalance described in (2) above.

In the above embodiment, the rectangular recess (1?r) is used.

(17g) and (+7b) are shown, but each recess (17r), (
17g), (17b) in the X-axis direction and Y-axis direction, the through holes (5r), (5
In this case, a wall extending in the Y-axis direction is formed on the outside of b), and it is clear that the same functions and effects as in the above embodiment can be obtained in this case as well.

[Effects of the Invention] As explained above, this invention has a predetermined height on the outside of the through holes on both sides of the through holes formed in the first accelerating electrode facing the focusing electrode. A wall body extending in the Y-axis direction is provided so that the convergence point of the X-axis outer component of the electron beam on both sides is made to be farther from the main lens than the convergence point of the inner component. This has the effect of providing an electron gun that corrects the force imbalance.

[Brief explanation of the drawing]

FIG. 1(a) shows the first accelerating electrode G, which is the main part of this invention.
2, FIG. 3(b) is a sectional view taken along the line bb arrow, FIG. 2 is a longitudinal sectional view of the in-line electron gun, and FIG. 3(a) is a front view of the conventional control electrode G1. 4(b) is an enlarged sectional view of the main lens portion of the electron gun, and FIG. 4(b) is a sectional view taken along line bb. A front view, FIG. 5 is a schematic diagram showing the main lens as an optical lens, and FIG. 6 is a diagram showing the shape of each electron beam spot on the phosphor screen. (1)... In-line type 111 subgun, (5)... First accelerating electrode G 2 , (5r), (5g),
(5b)=through hole, (Ill), (7)...
Focusing electrode G3, (8), (9)...second accelerating electrode, (12)--main lens, (+4)
・・Common lens, (+7r). (17g), (17b)...square recess. In addition, in each figure, the same reference numerals indicate the same or corresponding parts.

Claims (2)

[Claims] (1) The X-axis direction in which electron beams R, G, and B are lined up is Y
In an in-line electron gun having a focusing electrode that forms a rotationally asymmetric electric field lens that is longer than the axial direction, the outer side of the through-holes on both sides of the three through-holes formed in the first accelerating electrode through which the electron beam passes. An in-line electron gun characterized by comprising walls extending in the Y-axis direction, each of which is provided on a surface facing the focusing electrode. (2) Claim 1, wherein the wall is a peripheral wall surface of a rectangular recess formed eccentrically toward the center and formed on the surface of the first accelerating electrode communicating with the through hole. The in-line electron gun described.