JP3191970B2 - Color cathode ray tube - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color cathode ray tube in which the luminance distribution of a displayed image is uniform over the entire screen.

[0002]

2. Description of the Related Art In a shadow mask type color cathode ray tube, as is well known, a fluorescent surface in which dots or vertical stripes of three primary color phosphors are repeatedly arranged in a predetermined order is provided on the back surface of a face plate portion of a panel. A shadow mask having an opening for passing an electron beam is provided on the electron gun side of the fluorescent screen so as to face the fluorescent screen, and an electron beam dedicated to each of the three primary colors is emitted into the same horizontal plane. A gun is provided, and the electron beam for a specific primary color that has passed through a specific opening of the shadow mask intersects the shadow mask surface at an angle different from the electron beam for the other primary colors. Tracing a different trajectory from the electron beam to the dots or stripes of the specific primary color phosphor on the phosphor screen to emit light.

It should be noted that three electron guns (strictly indicating an electron beam emitting portion, and a focusing electron lens and the like having a large diameter with respect to the three electron beams) are dedicated to each primary color of a shadow mask type color cathode ray tube. The in-line method, which is arranged in a horizontal plane including the tube axis, is mainly used except for the very beginning. This is because so-called self-convergence can be expected.

[0004] As described above, the arrangement method of the electron guns is unified, whereas the method for the phosphor screen and the shadow mask is different. The fluorescent surface includes a three-primary-color phosphor repeatedly arranged in a predetermined order and a vertically-continuous three-primary-color phosphor stripe repeatedly arranged in a predetermined order. The shadow mask also has an electron beam passing opening in a circular shape corresponding to whether the phosphor on the phosphor surface is in a dot or stripe shape, and a vertically elongated opening at multiple locations in the vertical direction. The one provided with a lateral connection part for reinforcement, and the one in which the vertical grid elements are arranged in parallel and arranged in the horizontal direction have been put to practical use.

When the brightness of the display image is maximized, that is, when the beam current value is maximized, the diameter of the electron beam is large enough to cover a plurality of electron beam passing openings of the shadow mask. This means that the electron beam flies through the equipotential space in the funnel after leaving the electron gun,
It is unavoidable that repulsion between electrons acts during this flight. However, in such a situation,
The smaller the area ratio of the electron beam passing openings of the shadow mask, the lower the brightness of the entire displayed image. Black lines that do not emit light appear between phosphor element bodies (dots or stripes) of different primary colors that are adjacent in the horizontal direction, as in any type of shadow mask, but pixels using phosphor dots are used. In the method, black lines also appear between pixels adjacent in the vertical direction, and the brightness of the entire display image is relatively low. From the viewpoint of increasing the brightness of the entire display image, a shadow mask in which vertical grid elements are arranged in parallel in the horizontal direction is most preferable. Incidentally, as a shadow mask in which such grid element bodies are arranged in parallel, for example, Japanese Patent Publication No. 46-23941, U.S. Pat. No. 3,638,063 and the like can be mentioned.

[0006]

However, in a conventional shadow mask in which vertical grid elements are juxtaposed in the horizontal direction, the horizontal width of a specific vertical grid element is as follows.
The width of the electron beam passage opening between the grid elements was the same everywhere in the vertical direction. On the other hand, as described above, the diameter of the electron beam increases as the flight distance increases, and the current density in the electron beam decreases. Therefore, the brightness tends to be high in the central portion of the screen where the electron beam reaches the phosphor screen only by flying a relatively short distance, and the brightness tends to be low in the peripheral portion of the image where the electron beam travels a long distance.

The present invention solves the above-mentioned conventional problems and provides a color cathode ray tube in which the brightness of the entire display screen is high and the brightness distribution is uniform over the entire display image including the vertical direction. The purpose is to:

[0008]

In order to achieve the above object, according to the present invention, a fluorescent surface in which vertical stripes of three primary color phosphors are repeatedly arranged in a predetermined order in the horizontal direction is formed on the back surface of the panel. In a color cathode-ray tube having a shadow mask structure in which a large number of vertical grid elements are arranged in parallel in the horizontal direction in opposition to the phosphor screen, each grid element has a barrel shape, and electrons sandwiched between the grid elements are formed. The shape of the beam passage opening was made wide at both ends in the vertical direction and narrow at the center. At the same time, the grid elements in the vertical direction of the shadow mask structure are arranged in parallel at a variable pitch such that the horizontal distance between their center lines is relatively short at the center in the horizontal direction and relatively long as approaching both ends in the horizontal direction. I decided to let it.

[0009]

According to the present invention, by using a barrel-shaped grid element, it is possible to make the luminance distribution at the center in the vertical direction and both ends in the vertical direction of the displayed image uniform, and to make the vertical grid element horizontal. By juxtaposing the display images at a variable pitch in the direction, the luminance distribution at the center in the horizontal direction and the both ends in the horizontal direction of the display image can be made uniform, and a uniform luminance distribution can be obtained over the entire display screen.

[0010]

FIG. 2 is a schematic sectional view of a shadow mask type color cathode ray tube according to the present invention, in which 1 is a neck tube, 2 is a funnel, 3 is a panel, 4 is a valve, 5 is a face plate portion of the panel, Reference numeral 6 denotes a fluorescent screen, 7 denotes a shadow mask structure, 8 denotes an electron gun, and 9 denotes an electron beam. The fluorescent screen 6 is 3
The primary color phosphor has a complicated and fine structure in which stripes are sequentially and repeatedly arranged in a predetermined order, and the relative position between a specific stripe of the phosphor and a specific electron beam passing opening of the shadow mask structure is In general, it is necessary that the phosphor surface is held very accurately, so that the fluorescent surface is opposed to a photosensitive film containing a specific color phosphor applied to the entire back surface of the face plate portion of the panel. It is formed by a photolithography technique in which after exposing with light passing through the shadow mask opening to solidify a required portion and fixing it to the glass surface of the panel, an unnecessary portion is peeled off. To this end, panel 3 must be separated from funnel 2 until all the phosphor stripes of each phosphor on the phosphor screen are formed as desired. The panel 3 includes a face plate portion 5 facing the image observer and a panel skirt portion bent substantially at right angles around the face plate portion. A fluorescent surface is formed on at least the entire back surface of the panel as described above. Thereafter, the end face of the panel skirt portion and the end face of the funnel 2 are welded with low-melting glass to complete the bulb 4.
The electron beams 9 are emitted from three electron guns dedicated to a specific color arranged on a horizontal plane passing through the tube axis corresponding to each primary color. In this way, 3
The electron beam dedicated to the specific color emitted from the book specific color electron gun crosses the shadow mask at different angles when passing through the specific electron beam passing opening of the shadow mask. Therefore, even if the three electron beams pass through the specific opening for passing the electron beam of the shadow mask together, they pass through the opening and are narrowed there by being narrowed.
The electron beams fly in different orbits,
Light is emitted by striking the phosphor stripes of different specific colors forming the phosphor screen.

FIG. 1A is a perspective view showing a shadow mask structure used in a color cathode ray tube according to an embodiment of the present invention.
FIG. 1B is an enlarged plan view in the A circle shown in FIG. The color cathode ray tube of the present embodiment is a 20-inch, 90-degree-deflection color high-definition display tube for VDT.

The shadow mask of this embodiment has a thickness of 0.0
Made of 25 mm mild steel plate, the opening is about 1 mm in the horizontal direction.
There are 200 of them. A large number of barrel-shaped vertical grid elements 11a as shown in FIG. 1 (b) are arranged side by side at a variable pitch in the horizontal direction, and they are connected at both ends in the vertical direction to form a shadow mask 11. Barrel-shaped grid element 1 of shadow mask 11 of the present embodiment
1a is a horizontal width b at the center in the vertical direction at the center of the shadow mask.
= 0.225 mm, width a at both ends in the vertical direction
Is 0.96 times smaller than this. The width of the electron beam passing opening at the center of the shadow mask is 0.07.
5 mm. That is, at the center of the shadow mask,
The grid element bodies 11a are arranged at a pitch of 0.30 mm. The grid element 11a has a variable pitch P _H =
It is arranged at ^{_{0.30 + 1.23 × 10 ~ 6 x}} 2 mm. Here, x is a numerical value representing the horizontal distance from the center of the shadow mask to the position in mm. At the horizontal end of the shadow mask, the actual value of the pitch is 0.
Extends to 34 mm. Since the shadow mask is generally formed with an electron beam opening by an etching method, the material having a small thickness can be manufactured in a short time and the shape of the opening can be accurately formed. The thickness of the shadow mask material was made as thin as 0.025 mm. Unlike a shadow mask in which an electron beam passage opening is formed in a circular shape, such a shadow mask can apply a sufficiently high tension in the vertical direction. The opening may be deformed. Since the shadow mask used in the present invention has a large number of vertical grid elements arranged in parallel in the horizontal direction, the shadow mask structure 7
The shadow mask is fixed to the mask frame while tension is applied only in the vertical direction. As shown in FIG. 1A, the mask frame 10 includes a pair of horizontal frame sides 10.
a and 10b, and vertical arm portions 10c and 10d for holding these facing each other. In order for the shadow mask to function sufficiently with a margin as a color selection electrode, as described above, the horizontal width of the vertical grid element is considerably larger than the horizontal width of the electron beam passing opening. It is getting bigger. For this reason, a considerable portion of the electrons in the electron beam cannot pass through the opening, and collides with the grid element to prevent the movement. The kinetic energy is given to the colliding point, and the temperature is increased. Therefore, when the shadow mask is fixed to the mask frame by applying tension to the mask frame, it is necessary to ensure that sufficient tension is still applied even if the temperature of the shadow mask rises during use and thermally expands as described above. No. Therefore, the attachment work of the shadow mask 11 to the mask frame 10 is first performed by externally attaching the shadow mask 11 to the mask frame 10 such that the vertical distance between the horizontal frame sides 10a and 10b is reduced by a predetermined amount due to the elastic deformation of the vertical arms 10c and 10d. After the upper and lower peripheral portions of the shadow mask 11 are seam-welded to the horizontal frame sides 10a and 10b of the mask frame in a state where pressure is applied, the pressure is removed and the shadow mask 11 is elastically restored to the shadow mask 11 by the elastic restoring force of the mask frame 10. Tension is applied vertically. In addition, when the vertical grid element body 11a is attached to the mask frame 10 by applying tension in the vertical direction only, when actually used,
When a shock or vibration is applied from the outside of the cathode ray tube, continuous vibration may occur in the grid element and color mixing or color shift may appear on the display screen. To absorb the energy of vibration,
2. Description of the Related Art A damper wire using a thin tungsten wire or the like is stretched on a shadow mask by applying tension.

[0013]

As described above, according to the present invention, the current density when the electron beam reaches the phosphor screen is considerably different between the central portion and the peripheral portion of the image because the flight distance of the electron beam is different. In spite of the difference, the width of the electron beam passing opening of the shadow mask is set differently in the vertical direction and the horizontal direction of the screen depending on the position of the electron beam current density depending on the position reaching the phosphor screen. Since the compensation is performed, the luminance distribution of the display image can be made uniform over the entire screen.

[Brief description of the drawings]

FIG. 1 (a) is a perspective view showing a shadow mask structure used in a color cathode ray tube according to an embodiment of the present invention, and FIG. 1 (b) is within an A circle shown in FIG. 1 (a). FIG.

FIG. 2 is a schematic sectional view of a shadow mask type color cathode ray tube according to the present invention.

[Explanation of symbols]

1: Neck tube, 2: Funnel, 3: Panel, 4
... Valve 5 Panel faceplate 6
Phosphor screen, 7: shadow mask structure, 8: electron gun,
9: electron beam, 10: mask frame, 10a,
10b: horizontal frame side; 10c, 10d: vertical arm; 11: shadow mask; 11a: grid element.

──────────────────────────────────────────────────の Continuing on the front page (72) Inventor Hideo Tanabe 3300 Hayano Mobara-shi, Chiba Inside Mobara Plant, Hitachi, Ltd. (72) Inventor Masaki Shinoda 3300 Hayano Mobara-shi, Chiba Mobara Plant, Hitachi (72) Inventor Hiroshi Kawasaki 3681 Hayano, Mobara City, Chiba Prefecture Hitachi Device Engineering Co., Ltd. (56) References JP-B-46-32306 (JP, B1) JP-B-48-12548 (JP, B1) (58) ) Surveyed field (Int.Cl. ⁷ , DB name) H01J 29/07

Claims (2)

(57) [Claims] 1. A phosphor screen in which vertical stripes of three primary color phosphors are repeatedly arranged in a horizontal direction in a predetermined order is formed on the back surface of a panel, and a large number of vertical grid elements are opposed to the phosphor screen. In a color cathode ray tube in which a shadow mask structure arranged in a horizontal direction is arranged, each grid element of the shadow mask structure is formed into a barrel shape, and the shape of an electron beam passing opening sandwiched between the grid elements is set at both ends in a vertical direction. A color cathode ray tube characterized in that it is wide and narrow at the center. 2. The vertical grid elements of the shadow mask structure are arranged in parallel such that the horizontal distance between their center lines is relatively short at the center in the horizontal direction and relatively longer as approaching both ends in the horizontal direction. 2. The method according to claim 1, wherein
The color cathode ray tube as described.