JPH07134950A - Electron beam shield - Google Patents

Abstract

PURPOSE:To narrow the invalid screen luminescent region of a color cathode-ray tube by making the cross section shape of an electron beam shield serrate and setting the free end of the electron beam shield closely to a color selecting mechanism part. CONSTITUTION:An electron beam shield 28 is installed by welding or the like through a connection part 28b of a phosphor screen side of a frame B member. In the condition of the installation, the free end of the shield 28 is set closely to a color selecting mechanism 14. The long side serrate shield part especially the surface of the free end of the shield part 28a, is preferably set at an angle in which direction the electron beam B2 hits almost perpendicularly, wherein the electron beam comes into the outermost part of the phosphor screen. In that case, since the free end of the shield part 28a in set closely to the phosphor screen, an invalid screen luminescent region can be narrowed. The electron beam B3 is not shielded by the shield 28 and is one to pass the nearest position of the shield and together with the beam B2, the electron beam B3 forms the invalid screen luminescent region. The electron beam B4 hits against the shield part 28a and is reflected at acute angle prevents conventional IBS reflection.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electron beam shield (IBS), and in particular, enhances the shield effect for an electron beam emitted from a color cathode ray tube to reduce the amount of mislanding due to geomagnetism. It is related to the electron beam shield.

[0002]

2. Description of the Related Art FIG. 4 is a schematic view of a color cathode ray tube provided with a conventional electron beam shield and is shown in a partial cross section. Further, FIG. 5 is a perspective view of a color selection mechanism including a conventional electron beam shield. The color cathode ray tube (CRT) 1 shown in FIG. 4 is provided with a deflection yoke (not shown) attached to the outside of the cathode ray tube for the electron beam 3 emitted from the electron gun 2 so as to move the electron beam 3 vertically and horizontally around the deflection center P. The image is reproduced on the fluorescent screen 5 by deflecting. But,
A magnetic shield 7 is provided to shield an external magnetic field that adversely affects the electron beam and causes color shift,
Further, in order to shield the ineffective electron beam reaching the outside of the effective screen, the electron beam shield 8 which will be described in more detail below is provided with a frame B member (second frame: second frame: It is attached to the horizontal frame 10b. In FIG. 4, 10a is a frame A member (first frame: vertical frame), 12 is a glass panel, 13 is a funnel, and 18 is a spring holder.

The color selection mechanism shown in FIG. 5 is of the trinitron type, and a color selection mechanism (aperture grill: AG) 14 in which tapes are arranged in a comb shape is provided in the frame A member 1.
The structure is such that it is welded to 0a and stretched by the frame B member 10b.

In particular, the electron beam shield 8 extends from the upper surface of the temperature drift correction piece 9 attached to the side opposite to the fluorescent surface of the frame B member 10b along the fluorescent surface, and thus along the color selecting mechanism 14 in a substantially lateral direction. It is provided so as to extend and shield the ineffective electron beam. Further, a damper wire 16 is stretched over the frame B member 10b in order to suppress vibration of the color selection mechanism 14. The damper wire 16 is fixed to a damper spring 17. A spring holder 18 is attached to the frame A member 10a and the frame B member 10b, and
(Fig. 4). In the drawings shown below, the same elements as those described above are designated by the same reference numerals. In FIG. 5, 21 is a frame B member 10 of the electron beam shield 8.
It is a connection part to b.

[0005]

As described above, the conventional electron beam shield 8 is attached to the side of the frame B member 10b opposite to the fluorescent surface along the side surface of the frame B member 10b. Therefore, when the harmful electron beam B1 is shielded by the electron beam shield 8 as shown in FIG. 6, the distance between the electron beam B2 (effective screen edge formation) incident on the outermost part of the phosphor screen and the harmful electron beam B1 is It is difficult to set the tip of the electron beam shield 8 between the D1 and D1 in a narrow range, considering that the distance between the electron beam shield 8 and the phosphor screen 5 is large and the mounting error is large. The screen emission area was large.

In order to reduce the invalid screen light emitting area,
It is necessary to reduce the distance between the fluorescent screen 5 and the electron beam shield 8. However, if the electron beam shield 8 is simply brought close to the electron beam shield (IBS) 8 as shown in FIG. 7A, so-called IBS reflection that reflects on the effective screen is generated, or as shown in FIG. 7B. The IBS 8 may interfere with the spring holder 18 and may be difficult to dispose.

Further, the electron beam shield 8 is symmetrically attached in use, and has the best design when the vertical magnetic field is zero. However, in Japan, due to vertical geomagnetism, the electron beam has a circular orbit as shown in FIG. 8, the electron beam shield 8 is short on the left (-X) and halation (IBS reflection) is likely to occur, and the electron on the right (+ X) is likely to occur. Beam shield 8 becomes longer and IBS
Shadows are more likely to occur.

In view of the above problems, it is an object of the present invention to provide an electron beam shield capable of reducing the ineffective screen light emitting area of a color cathode ray tube.

[0009]

In order to solve the above problems, an electron beam shield according to a first aspect of the present invention is an electron beam shield which is attached to face a frame of a color selection mechanism of a color cathode ray tube. The cross-sectional shape of the electron beam shield is serrated, and the free end of the electron beam shield is disposed so as to be close to the color selection mechanism portion of the color selection mechanism.

The electron beam shield according to a second aspect of the present invention is arranged such that the shield surface at the free end of the electron beam shield is substantially perpendicular to the electron beam incident on the outermost portion of the color cathode ray tube. It is characterized by

According to a third aspect of the present invention, in the electron beam shield attached to the frame of the color selecting mechanism of the color cathode ray tube so as to face the frame,
The electron beam shields provided opposite to each other are asymmetrically arranged.

[0012]

According to the electron beam shield of the first aspect of the present invention, the cross section of the electron beam shield 28 has a sawtooth shape, and the free end of the electron beam shield is the color selecting mechanism portion 14 of the color selecting mechanism. The IBS shadow due to the mounting error of the electron beam can be prevented because it is arranged close to the electron beam, and the free end of the electron beam shield can be brought closer to the electron beam locus forming the effective screen edge, thus reducing the invalid screen emission area. Can be made.

According to the electron beam shield of claim 2 of the present invention, the shield surface at the free end of the electron beam shield 28 of claim 1 is substantially aligned with the electron beam incident on the outermost portion of the color cathode ray tube. Since they are arranged vertically, the electron beam that strikes the shield part is reflected so as to pass through or near the original trajectory, and so-called IBS reflection that causes halation does not occur.

Furthermore, according to the electron beam shield of the third aspect of the present invention, since the electron beam shields 29 attached to face each other are arranged asymmetrically, the electron beam shield according to the vertical earth magnetic field is aligned. Can shield.

[0015]

Embodiments of the present invention will now be described in detail with reference to the drawings.

FIG. 1 is a perspective view showing a first embodiment of an electron beam shield according to the present invention. The electron beam shield 28 of the present invention shown in FIG. 1 comprises a shield portion 28a bent in a sawtooth shape for shielding an electron beam and a connecting portion 28b to a frame, and is made of a rectangular steel plate.

FIG. 2 shows a schematic cross-sectional view in which the saw-toothed electron beam shield 28 is thus attached to the frame B member 10b.

Although the conventional electron beam shield is mounted on the side of the frame B member opposite to the fluorescent surface, the electron beam shield of this embodiment is welded to the frame B member on the fluorescent surface side via the connecting portion 28b. It is installed in. In the attached state, the free end of the electron beam shield 28 is arranged in the vicinity of the color selection mechanism 14.

It is preferable that the surface of the saw-toothed long-side shield part, particularly the shield part 28a at the free end, is arranged at an angle at which the electron beam B2 (forming the effective screen end) incident on the outermost part of the phosphor screen strikes substantially vertically. . In this embodiment, the shield portion 28a
Since the free end of is disposed near the phosphor screen, the invalid screen light emitting area can be reduced. Although the electron beam B3 is not shielded by the electron beam shield 28, it is an electron beam that passes through the closest position, and forms an invalid screen light emitting region with the electron beam B2. The electron beam B4 hits the shield portion 28a of the electron beam shield 28 and is reflected at an acute angle to prevent conventional IBS reflection (halation). When the electron beam shield 28 of this embodiment is used,
The space between the frame A member 10a and the frame B member 10b is also shielded, and the amount of mislanding due to geomagnetism is also reduced.

FIG. 3 is a perspective view showing a second embodiment of the electron beam shield according to the present invention. The electron beam shield shown in FIG. 3 considers the circular orbit due to the vertical geomagnetism described in FIG. 8 of the prior art. And are provided asymmetrically.

Particularly, in this embodiment, the frame B member 10 is adjusted so as to match the vertical geomagnetism of the use area, that is, the orbit shifted rightward like the electron beam orbit at the vertical geomagnetism 0.
An electron beam shield 29a having a long shield portion is provided on the left side on the temperature drift correction piece 9 of b, while an electron beam shield 29b having a short shield portion is provided on the right side.
As a matter of course, the electron beam shields 29a and 29b are arranged to face each other. Thus, the electron beam shield can be arranged asymmetrically to prevent halation.

Here, the deflection center and the electron beam shield 29
Letting L and R be the distances to the free ends of a and 29b, for example, in the case of vertical geomagnetism 35 μT, R−L = 5.5.
It is about mm. The electron beam shields 29a and 29b are arranged so that RL becomes larger as the geomagnetism becomes larger.

[0023]

As described above, according to the present invention,
It is possible to prevent halation such as IBS reflection in the color cathode ray tube, reduce the ineffective screen light emitting area, and obtain a good image without color misregistration.

[Brief description of drawings]

FIG. 1 is a perspective view of a first embodiment of an electron beam shield according to the present invention.

FIG. 2 is a schematic cross-sectional view for explaining the shield action by attaching the electron beam shield shown in FIG. 1 to a color cathode ray tube.

FIG. 3 is a schematic diagram for explaining a second embodiment of the electron beam shield according to the present invention.

FIG. 4 is a schematic diagram of the configuration of a color cathode ray tube including a conventional electron beam shield.

FIG. 5 is a perspective view of a color selection mechanism including a conventional electron beam shield.

FIG. 6 is a schematic cross-sectional view for explaining the action of a conventional electron beam shield.

FIG. 7 is a schematic diagram of a main part for explaining a problem of the conventional technique.

FIG. 8 is a schematic diagram of a main part for explaining a problem of the conventional technique.

[Explanation of symbols]

 1 Color Cathode Ray Tube 2 Electron Gun 3 Electron Beam 5 Fluorescent Surface 7 Magnetic Shield 8 Electron Beam Shield 9 Temperature Drift Correction Piece 10 Frame 10a Frame A Member 10b Frame B Member 12 Glass Panel 13 Funnel 14 Color Selection Mechanism (Aperture Grill) 16 Damper Wire 17 damper spring 18 spring holder 21 connection part 28 electron beam shield 28a shield part 28b connection part 29a, 29b electron beam shield

Claims (3)

[Claims] 1. An electron beam shield provided opposite to a frame of a color selection mechanism of a color cathode ray tube, wherein the electron beam shield has a saw-tooth cross section and the free end of the electron beam shield is the color selection. An electron beam shield, which is arranged so as to be close to a color selection mechanism portion of a mechanism body. 2. The electron according to claim 1, wherein a shield surface at a free end of the electron beam shield is arranged so as to be substantially perpendicular to an electron beam incident on an outermost portion of the color cathode ray tube. Beam shield. 3. An electron beam shield provided opposite to a frame of a color selection mechanism of a color cathode ray tube, wherein the electron beam shields provided opposite to each other are asymmetrically arranged. shield.