JPH0139187B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement of an electron gun device for a cathode ray tube, particularly a shadow mask type color cathode ray tube.

In general, an electron gun device for a color cathode ray tube consists of three electron guns each made up of a plurality of grid electrodes.The electron lenses formed by the electron guns focus the electron beam, and the electron beam is projected onto a screen. It is something that makes you

Normally, as a means to make three parallel electron beams emitted from a cathode almost coincident on a screen, for example, as shown in Japanese Patent Publication No. 52-32714, the bottom of a cylindrical electrode is used at the final stage of an electron gun device. A method has been adopted in which an electron lens is formed by arranging the two electron beams facing each other, and the central axis of the side electron beam passage hole is slightly eccentric to deflect the electron beam.

However, with the electron gun device having the above configuration, the electron beam focusing spot on the screen becomes elliptical, the bright spot on the fluorescent surface becomes large, and the resolution deteriorates significantly. The above-mentioned drawbacks were improved by configuring a cylindrical electrode (hereinafter referred to as a counter electrode) arranged on the screen side with a curved bottom.

However, the electron gun device with the above configuration,
Since the distance L between the electron beam passing holes of the opposing electrode is as short as D/2 or less relative to the diameter D of the electron beam passing hole, the main electron lens formed between the opposing electrodes is distorted by the electric field of the adjacent aperture. As the electron beams on both sides pass through the most distorted part of the main electron lens, the electron beams on both sides will be subjected to large distortions, and the bright spot on the phosphor surface will become larger, resulting in lower resolution. It was not possible to reliably prevent deterioration.

Therefore, an object of the present invention has been made in order to improve the above-mentioned drawbacks, and it is an object of the present invention to provide a shielding electrode inside the opposing electrode to prevent distortion of the electric field due to adjacent apertures, and to configure an opposing main focusing lens. By making the above-mentioned shielding electrode slightly eccentric in the direction of the center axis of the electron gun device than the center axis of the counter electrode, the three electron beams can be The object of the present invention is to provide a cathode ray tube in which the beam is concentrated on almost one point on the screen. Embodiments of the cathode ray tube according to the present invention will be described in detail below with reference to the drawings.

FIGS. 1 and 2 are a sectional view of a main part and a side view of an example of a cathode ray tube, particularly an electron gun device, according to the present invention. In the same figure, 1a, 1b,
1c are cathodes arranged at equal intervals on the same plane, and a heater (not shown) is housed inside. 2 and 3 are a first grid and a second grid, and holes 2a, 2b, 2c and 3a, 3b,
3c is provided. Further, on the opposing surface of the second grid 3, a third electrode is formed by joining two deep dish-shaped cylindrical electrodes, an upper electrode 4A and a lower electrode 4B.
A grid 4 is arranged. In this case, the hole 3 is located on the second grid 3 side of the lower electrode 4B.
Holes 4a, 4b, 4c corresponding to holes 4a, 3b, 3c are formed, and at the bottom of the upper electrode 4A, a side electron beam passage hole 4d for forming a main lens, a central electron beam passage hole 4e, and a side electron beam passage hole 4e are formed at the bottom of the upper electrode 4A. Beam passage hole 4
f (hereinafter referred to as holes 4d, 4e, 4f) are formed,
The holes 4d and 4f on both sides are provided with their central axes S eccentrically outward from the central axes T of the holes 4a and 4c on both sides of the lower electrode 4B. Further, in this upper electrode 4A, holes 4a and 4 of the lower electrode 4B are provided.
A first shielding electrode 5 having a side electron beam passage hole 5a, a central electron beam passage hole 5b, and a side electron beam passage hole 5c (hereinafter referred to as holes 5a, 5b, and 5c), whose central axis T coincides with b and 4c. is placed inscribed. In this case, the hole 5 of the first shielding electrode 5
The inner diameters of a, 5b, and 5c are the same as the hole 4 of the upper electrode 4A.
d, 4e, and 4f. Further, on the opposing surface of the third grid 4 (upper electrode 4A), a side electron beam passage hole 6a, a center electron beam passage hole 6b, and a side electron beam passage hole 6c (hereinafter referred to as holes 6a, 6b, and 6c) are provided at the bottom. A fourth grid 6 is arranged. In this case, this hole 6a,
6b, 6c are holes 4d, 4e, 4f of the upper electrode 4A
is provided on the same central axis S as the holes 4d, 4.
A main lens is formed between the gaps e and 4f and the holes 6a, 6b, and 6c. Moreover, inside this fourth grid 6, this fourth grid 6
A second shielding electrode 7 having holes 7a, 7b, 7c having the same inner diameter and whose central axis S coincides with the holes 6a, 6b, 6c of the fourth grid 6 is disposed inscribed therein. It is formed in a structure that substantially extends the electrical length of 6c.

According to such a configuration, the upper electrode 4A and the first
The holes 4d and 5a and 4f and 5c on both sides of the shielding electrode 5 are eccentric, and the holes 6a and 7a and 6c and 7c on both sides of the fourth grid 6 and the second shielding electrode 7 are eccentric.
Since the holes 4d and 6a and 4f and 6c on both sides of the upper electrode 4A and the fourth grid 6 are arranged on the same central axis S, decentered lenses with extremely small aberrations are formed between the upper electrode 4A and the holes 4f and 6c on both sides of the fourth grid 6, and light passing through these portions is formed. The electron beams are deflected toward the central electron beam, allowing three beams to be focused on one point on the screen. In this case, the deflection angles for the electron beams on both sides can be adjusted by appropriately setting the lengths and eccentricities of the holes 5a, 5c of the first shielding electrode 5 and the holes 4d, 4f of the upper electrode 4A.

In addition, in the above embodiment, the third grid 4
The first shielding electrode 5 housed in the upper electrode 4
A, the case where the fourth grid 6 and the second shielding electrode 7 are eccentric to the same central axis has been described, but the present invention is not limited to this.
The first shield electrode 5, upper electrode 4A, and fourth grid 6 housed in the third grid 4 are arranged on the same central axis, and the second shield electrode 7 housed in the fourth grid 6 is eccentrically arranged. Of course, the same effect as described above can be obtained even if the above-described method is used.

In the above embodiment, the inner diameter of the holes 5a, 5b, 5c of the first shielding electrode 5 housed in the upper electrode 4A of the third grid 4 is the same as that of the hole 4 of the upper electrode 4A.
By configuring the holes to be smaller than d, 4e, and 4f, the electric field due to the adjacent apertures that is applied to the electron beam passing through the holes in the center and on both sides is suppressed to a small amount and uniformly, and the influence of the electric field due to the adjacent apertures is reduced as much as possible. ing. In addition, the holes 5a, 5b, 5 of the shielding electrode 5
By making the inner diameter of the holes 4d to 4f smaller than those of the holes 4d to 4f, the gaps between the holes 5a, 5b, and 5c can be widened, and the openings 4d, 4e, and 4e constituting the main lens can be made wider.
Since the diameters of the holes 4f, 6a, 6b, and 6c can be made larger than the distance between the apertures, a large-diameter lens can be obtained. Therefore, highly accurate focusing can be obtained.

Further, in the above embodiment, a bipotential focus type electron gun device has been described, but the present invention is not limited to this, and the same effects as described above can be obtained with an electron gun device having other structures. Of course, it can be done.

As explained above, according to the cathode ray tube according to the present invention, at least one of the opposing electrodes is provided with a shielding electrode having an electron beam passing hole, and the side electron beam passing hole of the shielding electrode is connected to the side electron beam passing hole of the at least one of the opposing electrodes. Since it is eccentric to the beam passage hole, it is possible to block the distortion of the electric field caused by adjacent apertures and concentrate the electron beam at a single point on the screen, which is an extremely excellent feature that reliably prevents resolution deterioration. Effects can be obtained.

[Brief explanation of drawings]

1 and 2 are a sectional view and a side view of essential parts showing an example of a cathode ray tube electron gun device according to the present invention. 1a, 1b, 1c... cathode, 2... first grid, 2a, 2b, 2c... hole, 3... second grid, 3a, 3b, 3c... hole, 4... third grid, 4A... ...Top electrode, 4B...Bottom electrode,
4a, 4b, 4c, 4d, 4e, 4f... hole, 5
...first shielding electrode, 5a, 5b, 5c...hole,
6...4th grid, 6a, 6b, 6c...hole,
7... Second shield electrode, 7a, 7b, 7c...
Hole.

Claims (1)

[Scope of Claims] 1. A cylindrical electrode having a central electron beam passage hole and a side electron beam passage hole disposed on both sides of the central electron beam passage hole at the bottom thereof is installed in the final stage of an electron gun device, and the bottom portion is disposed on both sides of the central electron beam passage hole. In a cathode ray tube arranged so that the electron beam passing holes facing each other are coaxial, a shielding electrode having electron beam passing holes corresponding to the electron beam passing holes in at least one of the cylindrical electrodes. A cathode ray tube characterized in that a side electron beam passage hole of the shielding electrode is eccentric with respect to a side electron beam passage hole of the one cylindrical electrode. 2. The cathode ray according to claim 1, wherein the inner diameter of the eccentric side electron beam passage hole of the shielding electrode is smaller than the inner diameter of the side electron beam passage hole of the one cylindrical electrode. tube. 3. The cathode ray tube according to claim 1 or 2, wherein the shielding electrode having the eccentric electron beam passage hole is provided in one of the cylindrical electrodes disposed on the cathode side.