JP2000228155A - Cathode-ray tube - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve impact resistance characteristic of a cathode-ray tube without degradation in withstand voltage characteristic, neck crack and reduction in productivity. SOLUTION: In a cathode-ray tube in which a central axis of an electron gun 27 at the side of electron beam emission end is in agreement with that of a neck 25 by support of an elastic support 34, the elastic support 34 is formed suck that spring constant of the elastic support 34 in the side of eccentric, when the side of electron beam emission end has been off-centered by external impact, is bigger than that of the support 34 when the central axis of the side of electron beam emission end is in agreement with that of the neck 25.

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 such as a color cathode ray tube, and more particularly to a cathode ray tube having an improved elastic support for supporting an electron beam emitting end of an electron gun.

[0002]

2. Description of the Related Art Generally, a color cathode ray tube has an envelope composed of a panel and a funnel-shaped funnel, and a phosphor screen composed of a three-color phosphor layer is provided on the inner surface of the panel. Then, a shadow mask is arranged on the inside. On the other hand, an electron gun that emits three electron beams is arranged in the cylindrical neck of the funnel. Then, the three electron beams emitted from the electron gun are deflected by the horizontal and vertical deflection magnetic fields generated by the deflection yoke mounted outside the funnel, and the phosphor screen is horizontally and vertically scanned through a shadow mask. , And a structure for displaying a color image.

As such a color cathode ray tube, an in-line type color cathode ray tube in which an electron gun emits three electron beams arranged in a row is widely used at present.

As shown in FIG. 6, the electron gun is provided with three cathodes K, three heaters (not shown) for heating the cathodes K, and a cathode K in the direction of the phosphor screen. A plurality of electrodes G1 to G6 (six electrodes in the illustrated example) and a shield cup C attached to the phosphor screen side end of the sixth electrode G6;
These heater, cathode K and a plurality of electrodes G1 to G
6 is formed in a structure fixed by a pair of insulating support rods 1. The electron gun has a stem pin 4 provided on a stem 3 in which the cathode K side seals the end of the neck 2.
, The electron beam emitting end side is attached to the shield cup C, and the neck 2 extends from the inner surface of the large diameter portion of the funnel.
The neck 2 is formed via the conductive film 6 applied over the inner surface.
It is supported by a plurality of elastic supports 7 that press against the inner surface. Thereby, the electron gun is connected so that the central axis of the electron gun coincides with the central axis of the neck 2 (coincident with the tube axis Z).

[0005] As shown in FIG.
At one end, a fixing portion 9 welded to the shield cup is formed by bending, and at the other end, a contact portion 10 is formed, the surface of which presses against the inner surface of the neck via a conductive film is formed as a convex surface. It is formed in a strip shape with a leaf spring portion 11 interposed between it and the contact portion 10.

[0006]

As described above, in the electron gun of the color cathode ray tube, the cathode side is supported by the stem pin provided on the stem for sealing the neck end, and the electron beam emitting end is located at the electron beam emitting end. Mounted on the side electrode (shield cup) and supported by a plurality of elastic supports pressed against the inner surface of the neck via the conductive film, whereby the center axis of the electron gun is supported so as to coincide with the center axis of the neck. ing.

The elastic support body has a fixed portion welded to an electrode on the electron beam emitting end side bent at one end, and a surface pressed against the inner surface of the neck via a conductive film at the other end portion having a convex curved surface. A contact portion is formed, and a leaf spring portion is interposed between the fixed portion and the contact portion to form a strip.

However, if the electron beam emitting end side is supported by the elastic support, after the convergence adjustment, the position of the electron gun is shifted due to an external impact applied during transportation or the like, and the convergence characteristics and landing characteristics may be deteriorated.

That is, generally, a color cathode ray tube has a 3
By adjusting the mounting angle of the deflection yoke so that the electron beam passes through a predetermined position of the deflection magnetic field generated by the deflection yoke, adjustment is performed so that optimum convergence is obtained over the entire surface of the phosphor screen. Therefore, in order to display a good image, it is necessary to immediately return to the original position even if the electron gun is displaced due to an external impact. However, the conventional elastic support has a problem in that the spring strength is not sufficient against the above-mentioned external impact, and when a large external impact is applied, the elastic support does not return to its original position, and the convergence characteristics and the landing characteristics are significantly deteriorated. .

In order to prevent such deterioration of the characteristics, it is only necessary to increase the spring strength of the elastic support to increase the support strength of the electron gun. When the electron gun is inserted into the neck and sealed, the conductive film on the inner surface of the neck is scraped by friction with the contact portion of the elastic support, and the scraps of the cut conductive film adhere to the electron gun or its vicinity. As a result, a discharge in the tube, a leak between the electrodes, etc. occur to deteriorate not only the withstand voltage characteristic but also damage the inner surface of the neck and cause a neck crack.

As means for solving such a problem, there is a method of attaching a large number (6 to 8 or more) of elastic supports having relatively low spring strength. According to this means,
A support effect equivalent to that of using the elastic support having high spring strength is obtained. In addition, it is possible to prevent the conductive film from being scraped, thereby preventing deterioration of withstand voltage characteristics such as discharge in a tube and leakage between electrodes, and neck cracks caused by damage to the inner surface of the neck. However, such means has a problem in that the number of parts increases, the mounting time increases, and the productivity decreases.

The present invention has been made to solve the above problems, and an object of the present invention is to improve the impact resistance of a cathode ray tube without deteriorating withstand voltage characteristics, neck cracks, and lowering productivity. Aim.

[0013]

(1) An electron gun having a plurality of electrodes is arranged in a neck of a funnel, and the electron beam emitting end of the electron gun is fixed to the electrode on the electron beam emitting end. The center axis of the electron gun and the center axis of the neck at the electron beam emitting end side are supported by a plurality of elastic supports that are in pressure contact with the inner surface of the neck via a conductive film formed on the inner surface of the neck. When the electron beam emitting end side is eccentric due to external impact in the cathode ray tube in which the electron beam emitting end side is eccentric due to an external impact, the center axis of the electron beam emitting end side is the center axis of the neck. It was formed to have a structure in which the spring constant of the elastic support at the time of coincidence was higher.

(2) In the cathode ray tube of (1), the elastic support is provided between the fixed portion fixed to the electrode on the electron beam emitting end side and the contact portion pressed against the inner surface of the neck via the conductive film. A projection is provided which protrudes in the direction of the electrode on the electron beam emitting end side and comes into contact with the electrode on the electron beam emitting end side when the electron beam emitting end side is eccentric.

(3) In the cathode ray tube of (1), the elastic support is provided between the fixed portion fixed to the electrode on the electron beam emitting end side and the contact portion pressed against the inner surface of the neck via the conductive film. At least a portion is curved in a convex shape in the direction of the electrode on the electron beam emitting end side, and when the electron beam emitting end side is decentered, the convexly curved portion comes into contact with the electrode on the electron beam emitting end side.

[0016]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 shows a color cathode ray tube which is one embodiment of the present invention. This color cathode ray tube has an envelope composed of a panel 20 and a funnel 21 having a funnel shape.
A phosphor screen 22 made of a three-color phosphor layer that emits blue, green, and red light is provided on the inner surface of 0, and a shadow mask 23 is disposed inside the phosphor screen 22 so as to face the phosphor screen 22. On the other hand, in a cylindrical neck 25 of the funnel 21, three electron beams 2 arranged in a line passing on the same horizontal plane
An electron gun 27 for emitting 6B, 26G, 26R is connected. The three electron beams 26B, 26G, and 26R emitted from the electron gun 27 are deflected by horizontal and vertical deflection magnetic fields generated by a deflection yoke 29 mounted outside the funnel 21, and the phosphors are passed through a shadow mask 23. The screen 22 is formed to display a color image by scanning the screen 22 horizontally and vertically.

The electron gun 27 has three cathodes K arranged in a row in the horizontal direction, three heaters (not shown) for heating these cathodes K, and a plurality of cathodes K arranged in the direction of the phosphor screen in order from the cathode K. The plurality of electrodes G1 to
G6 (six in the illustrated example) and a shield cup C attached to the end of the sixth electrode G6 on the phosphor screen side, the heater, the cathode K and the plurality of electrodes G1.
G6 are formed in a structure fixed by a pair of insulating support rods 1.

In the electron gun 27, the cathode K side is supported by a stem pin 32 provided on a stem 31 for sealing the end of the neck 25, the electron beam emission end side is attached to the side surface of the shield cup C, and the funnel It is supported by a plurality of elastic supports 34 which press against the inner surface of the neck 25 via a conductive film 33 formed by coating from the inner surface of the large diameter portion to the inner surface of the neck 25. Thereby the electron gun 27
Are arranged so that the central axis of the central axis (5) coincides with the central axis of the neck 25 (coincident with the tube axis Z).

As shown in FIG. 3, the elastic support 34 has a fixed portion 36 which is bent at one end and which is welded to the side surface of the shield cup, and is pressed against the inner surface of the neck via the conductive film at the other end. The contact portion 37 whose surface to be formed is a convex curved surface is formed, and the leaf spring portion 3 is provided between the fixing portion 36 and the contact portion 37.
8 is formed in the shape of a strip interposed.

Further, in this embodiment, projections 39 projecting toward the shield cup when the fixing portion 36 is welded to the side surface of the shield cup are provided on both sides of the leaf spring portion 38. When the projection 39 is normally sealed in the neck so that the center axis of the electron gun coincides with the center axis of the neck, the projection 39 does not contact the side surface of the shield cup and contacts the side surface of the shield cup as much as possible. It is formed in a size to approach.

When such an elastic deformation portion 38 is attached to the electron beam emitting end side electrode of the electron gun 27 to support the electron gun 27, when the electron gun 27 is sealed, the conductive film 33 is not cut off and the neck is removed. 25 can be inserted into the neck 25 without damaging the inner surface. Therefore, it is possible to prevent deterioration of withstand voltage characteristics such as discharge in a tube and leakage between electrodes.
In addition, even if the electron gun is displaced due to an external impact, the color CRT can be immediately returned to the original position and the convergence characteristics and the landing characteristics are not deteriorated.

That is, the spring constant k of a leaf spring is generally
The length of the leaf spring is 1, the width is b, the thickness is h, and the longitudinal elastic modulus is E.
Then, k = b × h ³ × E / 4 × l ³ . Therefore, when the length 1 is shortened, the spring constant of the leaf spring increases, and the leaf spring becomes a spring having relatively high spring strength. Conversely, when the length 1 is increased, the spring constant k decreases, and the spring has a relatively low spring strength.

Therefore, when the elastic support 34 is constructed as in this embodiment, as shown in FIG. 3A, a contact portion is formed from a boundary 41 between the fixed portion 36 acting as a leaf spring and the leaf spring portion 38. The length l1 of the 37 to the contact point 42 with the conductive film 33 can be made sufficiently long to reduce the spring strength. When the electron gun 27 is sealed, the conductive film 33 is not cut off and the neck 25 is removed. Neck 2 without damaging the inner surface
5 can be inserted. Therefore, it is possible to prevent deterioration of withstand voltage characteristics such as discharge in a tube and leakage between electrodes caused by the scraps of the conductive film shaved off and attached to the electron gun 27 or its vicinity.

Further, when the electron beam emitting end side of the electron gun 27 is eccentric due to an external impact, as shown in FIG. 3B, the electron gun 27 is provided on the leaf spring portion 38 of the elastic support 34 attached in the eccentric direction. The protrusion 39 contacts the side surface of the shield cup C. In this case, the portion acting as a leaf spring has a length l2 from the contact point 43 of the projection 39 with the shield cup C to the contact point 42 of the contact portion 37 with the conductive film 33, and the spring strength is increased. Moreover, the difference in spring strength between the elastic support 34 attached in the eccentric direction and the elastic support 34 on the opposite side increases. Therefore, due to the high spring strength and the difference in spring strength between the elastic support 34 on the opposite side, the eccentric electron beam emitting end side can be promptly returned to the original position.

Next, an elastic support according to a different embodiment will be described.

The elastic support 34 shown in FIG. 4 is a leaf spring between a fixed portion 36 welded to the side surface of the shield cup and a contact portion 37 having a convex curved surface which presses against the inner surface of the neck via the conductive film. The portion 38 is curved so as to be convex in the direction of the shield cup.

Even if the elastic support 34 is formed in such a shape, the elastic support having the same effect as the elastic support 34 shown in FIG. 2 can be obtained.

That is, as shown in FIG. 5 (a), the length l1 from the boundary 41 between the fixing portion 36 and the leaf spring portion 38 to the contact point 42 of the contact portion 37 with the conductive film 33 is made sufficiently long. When the electron gun 27 is sealed, the conductive film 33 can be inserted into the neck 25 without shaving the conductive film 33 and without damaging the inner surface of the neck 25. Deterioration of withstand voltage characteristics such as discharge in a tube and leakage between electrodes caused by the attachment of dust to or near the electron gun 27 can be prevented.

Further, when the electron beam emitting end side of the electron gun 27 is eccentric due to an external impact, as shown in FIG. 5B, the fixing portion of the leaf spring portion 38 of the elastic support 34 attached in the eccentric direction. The side 36 contacts the side surface of the shield cup C, and the portion acting as a leaf spring is from the contact point 43 with the shield cup C to the contact point 4 with the conductive film 33 of the contact portion 37.
The length is up to 2 and the spring strength is increased. Moreover, the difference in spring strength between the elastic support 34 attached in the eccentric direction and the elastic support 34 on the opposite side increases. Therefore, the high spring strength and the elastic support 34 on the opposite side
The eccentric electron beam emitting end side can be promptly and correctly returned to the original position due to the difference in spring strength from the above.

Although the above embodiment has been described with reference to a color cathode ray tube, the present invention can be applied to a cathode ray tube other than a color cathode ray tube.

[0032]

As described above, when the elastic support for supporting the electron beam emitting end side of the electron gun is formed, when the electron gun is sealed, the conductive film on the inner surface of the neck is not cut off and the inner surface of the neck is removed. It can be inserted into the neck without damaging it and can prevent deterioration of withstand voltage characteristics such as discharge in a tube and leakage between electrodes. Moreover, even if the electron gun is displaced due to external impact,
The cathode ray tube can be immediately returned to the original position immediately and the convergence characteristics and the landing characteristics do not deteriorate.

[Brief description of the drawings]

FIG. 1A is a diagram showing a configuration of a color CRT according to an embodiment of the present invention, and FIG. 1B is a diagram showing an arrangement of an electron gun in a neck.

FIG. 2 is a view showing a configuration of an elastic support for supporting an electron beam emitting end side of the electron gun.

FIGS. 3A and 3B are diagrams for explaining the operation of the elastic support. FIG.

FIG. 4 is a diagram showing a configuration of an elastic support different from the elastic support shown in FIG. 2;

5 (a) and 5 (b) are diagrams for explaining the operation of the elastic support shown in FIG. 4;

FIG. 6 is a diagram showing an arrangement of a conventional color cathode ray tube in a neck of an electron gun.

FIG. 7 is a view showing a configuration of an elastic support for supporting the electron beam emitting end side of the conventional electron gun.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 21 ... Funnel 25 ... Neck 27 ... Electron gun 33 ... Conductive film 34 ... Elastic support 36 ... Fixed part 37 ... Contact part 38 ... Leaf spring part 39 ... Projection part C ... Shield cup

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Tsutomu Takekawa 7-1, Nisshincho, Kawasaki-ku, Kawasaki-shi, Kanagawa Prefecture Inside Toshiba Electronics Engineering Co., Ltd. (72) Inventor Hirofumi Ueno 7-1, Nisshincho, Kawasaki-ku, Kawasaki-shi, Kanagawa Prefecture F-term in Toshiba Electronics Engineering Corporation (reference) 5C041 AA03 AB15

Claims (3)

[Claims] An electron gun having a plurality of electrodes is disposed in a neck of a funnel, and an electron beam emitting end side of the electron gun is fixed to the electrode on the electron beam emitting end side and formed on an inner surface of the neck. It is supported by a plurality of elastic supports that are in pressure contact with the inner surface of the neck via a conductive film, and the central axis of the electron gun at the electron beam emitting end side coincides with the central axis of the neck due to the support of the elastic supports. In the cathode ray tube, when the electron beam emission end side of the elastic support is eccentric due to an external impact, the spring constant of the elastic support on the eccentric side matches the center axis of the electron beam emission end with the center axis of the neck. A cathode ray tube characterized in that the cathode ray tube is formed to have a structure that is higher than a spring constant of the elastic support member. 2. An elastic support member is provided between a fixed portion fixed to an electrode on the electron beam emitting end side and a contact portion pressed against the inner surface of the neck via a conductive film in the direction of the electrode on the electron beam emitting end side. 2. The cathode ray tube according to claim 1, wherein a projection is provided which projects and comes into contact with the electrode on the electron beam emitting end side when the electron beam emitting end side is eccentric. 3. The elastic support has at least a portion between a fixed portion fixed to an electrode on the electron beam emitting end side and a contact portion pressed against the inner surface of the neck via a conductive film on the electron beam emitting end side. 2. The cathode ray according to claim 1, wherein the convex portion is curved in a direction of the electrode, and the convexly curved portion contacts the electrode on the electron beam emitting end when the electron beam emitting end is eccentric. tube.