JPH08287838A - Cathode-ray tube - Google Patents

Abstract

PURPOSE: To effectively correct distortion of an image screen in the vicinity of a corner part due to a chassis effect without reducing a shielding effect to the earth magnetism or the like of a cathode-ray tube in which an internal magnetic shielding member is arranged. CONSTITUTION: An opening part 19 is arranged in the vicinity of a corner part of an internal magnetic shielding member 16. Distortion of an image screen by a chassis effect is effectively and properly corrected by a correcting member 18 such as a magnet sticking to a funnel part or the like of a tube body 2 of a cathode-ray tube.

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, and more particularly to improvement of an internal magnetic shield member for preventing deviation of an electron beam trajectory due to an external magnetic field such as earth magnetism.

[0002]

2. Description of the Related Art Conventionally, in a color cathode ray tube, an internal magnetic shield member is generally provided to prevent an electron beam scanning a color fluorescent screen from being affected by an external magnetic field such as terrestrial magnetism.

During the warm-up of such a color cathode ray tube, an electron beam is emitted on the display surface of the face plate panel.
%, A bright portion is produced in the corner portion of the color cathode ray tube when passing over the inner magnetic shield member and the funnel portion of the color cathode ray tube by excessive scanning. The brightness of this bright part increases when the mounting bracket or ground conductor is grounded and disappears within a few seconds or a few minutes after the warm-up period, but it can be seen in the corners of the color cathode ray tube during such warm-up period. A perforated inner magnetic shield 20 for eliminating bright areas is known.

The useless bright portion seen in the above-mentioned corner portion is charged by the glass of the color cathode ray tube and deflects the excessive scanning beam in the direction away from the inner surface of the side wall to surround the end portion of the shadow mask and reach the display surface of the panel. It is thought to lead.

In order to eliminate such glass charging effect, FIG.
As shown in FIG.
1, the getter material is scattered through the openings 21 to the inner surface of the side wall of the color cathode ray tube, and the opening area is selected to be 20% or less of the outer surface area of the inner magnetic shield member 20. The structure is shown in Japanese Patent Application Laid-Open No. 61-203537.

Further, as shown in FIG. 8, a frame 31 for reinforcing the periphery of the shadow mask 30 to effectively remove the influence of the external environmental magnetic field such as the earth's magnetism and to reduce the amount of mislanding has a long and high magnetic permeability. A magnetic shield member (L-shaped magnetic body) 32 made of a material is fixed, and the magnetic shield member 32 is fixed.
By extending toward the direction of the electron gun and forming a tip portion 32a having a bent portion 32b at the tip thereof to facilitate magnetization in only a specific direction due to the shape effect of the tip portion,
Japanese Patent Laid-Open No. Hei 6 (1999) -19996
No. 36700.

[0007]

The opening 2 formed in the corner portion of the internal magnetic shielding member 21 described in the above-mentioned prior art.
No. 1 is a bright part seen in the corner of the color cathode ray tube during warm-up, because the getter material is scattered on the inner surface of the side wall of the color cathode ray tube, and the getter coating quickly releases the negative charges accumulated on the inner surface of the side wall. It is provided to eliminate the problem.

On the other hand, the one shown in FIG. 8 is designed to eliminate the influence of the external environmental magnetic field in a specific direction such as the earth's magnetism in a state where it does not affect the other direction, thereby reducing the mislanding amount of the electron beam. It was made in. Even if an internal magnetic shield member having an opening is formed in the corner portion as described above, a chassis effect such as image distortion deterioration and color purity deterioration which is received when the color cathode ray tube is installed in a chassis or a cabinet is obtained. However, there is a problem in that color purity deterioration and image deterioration occur.

SUMMARY OF THE INVENTION The present invention provides a cathode ray tube which solves the above problems, and an object of the present invention is to provide a cathode ray tube capable of properly applying a predetermined correction capable of eliminating the chassis effect generated in the cathode ray tube. It was made to obtain

[0010]

The cathode-ray tube of the present invention has an internal magnetic field extending along the inner surface of the funnel portion of the cathode-ray tube body at the rear of the frame which is arranged to face the inner surface of the panel of the cathode-ray tube body. A shielding member and a correcting member such as a magnet that corrects a chassis effect such as image distortion attached near the corner of the cathode ray tube body are provided, and magnetic lines of force of the correcting member are provided near the corner of the internal magnetic shielding member. It is provided with an aperture for transmitting light.

[0011]

The correction of the chassis effect countermeasure can be properly performed by selecting the kind of the correction member such as the magnet according to the amount of change due to the chassis effect at the position facing the vicinity of the corner of the internal magnetic shielding member.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A color cathode ray tube using an aperture grill with one gun and three beams as a cathode ray tube of the present invention will be described below with reference to FIGS.

FIG. 1 is an overall configuration diagram of the cathode ray tube of the present invention,
2 is an explanatory view of magnetic force lines of the present invention, FIG. 3 is an explanatory view of magnetic force lines of the correction member of the present invention, and FIG. 4 is a perspective view of a magnetic shielding member used in the cathode ray tube of the present invention.

In FIG. 1, the color cathode ray tube is composed of a face plate panel 1, a cathode ray tube tube body 2 including a funnel portion, and a glass member of a neck portion 2a having an electron gun 3, and an inner surface of the face plate panel 1 is colored. The phosphor 4 is applied and is composed of a color selecting means 5 and an internal magnetic shield member 16 facing the color phosphor 4. The color selecting means 5 has a frame 9 including a frame side 7 and an arm portion 8, a card grill 10 and an aperture grill 11.

The internal magnetic shielding member 16 is formed in a pyramidal pyramid shape along the funnel portion, and the size of the rectangular bottom opening portion 16a at the bottom side is the size of the frame side 7 and the arm portion 8 constituting the frame 9. It has the same size as a rectangle, and the pair of long side wall 12 and short side wall 13 is substantially trapezoidal, and the short side wall portion of the mounting opening portion 16b formed in the mounting head is V-shaped. The short side notch 17 is formed by the notch. The V-shaped notch formed on the short side wall 13 causes the magnetic flux generated by the degaussing coil to pass through the aperture grille 11 of the color selecting means 5.
In particular, the demagnetization efficiency is improved in the X-axis direction of the electron beam so as to flow more.

Further, in the example of FIG. 1, as will be described later in detail, an opening portion 19 is formed near the corner of the long side wall 12. A correction member 18 for correcting the chassis effect such as a magnet attached to the funnel portion of the cathode ray tube body 2 is disposed opposite to the opening 19.

The internal magnetic shielding member 16 incorporated in the color cathode ray tube as described above has an effect of shielding the external magnetic field such as the earth magnetism and reducing the mislanding amount of the electron beam. However, since the internal magnetic shielding member 16 is disposed in the cathode ray tube body 2, such a color cathode ray tube is inserted into a casing having a chassis shape, a cabinet or the like having different sizes, and attached at a predetermined position. At this time, a chassis effect such as color purity deterioration or image distortion deterioration occurs at a preset color purity or proper image position due to the magnetic shielding effect of the internal magnetic shielding member 16 described above.

In order to eliminate such a chassis effect, a correction member 18 made of a magnet, a ferrite piece, an iron piece, etc., in a predetermined shape is attached to the funnel portion of the cathode ray tube body to distort the image distortion and color of the electron beam. The internal magnetic shielding member 16 causes a problem that these corrections cannot be performed sufficiently when the correction of the purity or the like is performed. Therefore, in this example, the opening 19 is formed in the internal magnetic shield member 16.

FIG. 4 shows a perspective view of the above-mentioned internal magnetic shielding member 16 as seen from the back side, and the formation position, shape, etc. of the opening 19 will be described with reference to this perspective view.

The internal magnetic shield member 16 has a thickness of 0.1 m.
The opening 19 is made of a magnetic thin film of about m to 0.4 mm, and the opening 19 to be formed is used for color purity correction or image distortion correction on the color fluorescent screen 4 of the face plate panel 1 at the four corners when viewed from the front. Since the correction is made to concentrate on the above, it can be considered that the correction by the chassis effect is converged on these four corners.

Therefore, the opening area of the opening 19 can be selected from 1 cm ² to 50 cm ^{2 in} order to enhance the effect of eliminating the chassis effect without reducing the shielding effect, for example, the effect of correcting color purity and image distortion. To do.

That is, when the opening area is selected as described above, the magnetic field lines φ _E of the external magnetic field such as the earth magnetism passing through the opening 19 formed in the internal magnetic shielding member 16 as shown in FIG. Lines of magnetic force φ _E absorbed near the opening
Has substantially the same size as the internal magnetic field lines of the internal magnetic shield member 16, and the decrease in the magnetic shield effect caused by the presence of the opening 19 is small.

Further, the position of the opening 19 in this example is the length of each side from the end of each of the long side L ₁ and the short side L ₂ of the frame 9 supporting the bottom side opening 16a of the internal magnetic shield member 16. It is within 1/6 of that. That is, bored openings 19 of the L _2/6 within the size described above in of the short side L ₂ in the corner portion from the corner portion in the long side L ₁ L _1/6 within.

Further, the opening position in the vertical direction formed from the corner portion of the frame 9 along the ridgeline of the mounting pyramid, that is, in the direction away from the face plate panel surface 1, is the length L ₁ of the long side of the frame 9. It is selected to 1/6 within the (L _1/6).

The magnetic shield member is present in the through hole portion by forming the opening portion 19 made of the through hole or the like having a size determined by a predetermined image distortion or the like at the above-mentioned position near the corner of the internal magnetic shield member 16. Therefore, the magnetic shielding effect is reduced only in this portion.

The cathode ray tube body 2 is provided with respect to the above-mentioned opening 19.
When the correction member 18 is added to the funnel portion of the disk, which corresponds to the amount of change due to the chassis effect such as image distortion and color purity deterioration, the type and size (magnet strength) of the correction member 18 are selected to correct the chassis effect. It is decided according to the quantity. The magnetic field lines φ _C from the correction member 18 thus attached to the funnel portion reach the inside of the internal magnetic shielding member 16 without being disturbed by the internal magnetic shielding member 16 as shown in FIG.
It is possible to effectively correct the landing deviation of the electron beam or the like.

In the above-described embodiment, the opening 19 formed in the internal magnetic shield member 16 has a through hole formed as a long side wall 12 and a short side wall 1.
3 one has been addressed formed in the opening 19 as shown in FIG. 5 within L _1/6 and / or L _2/6 of each side of the frame 9, the height round hole 19a within L _1/6 , Square hole 19b, elliptical hole 1
The corner hole 19d and the like are formed so as to extend over the ridge line 9c or the corner portion, and the shape and the number of holes to be formed can be appropriately selected.

The structure shown in FIG. 6 is not a through hole, but a kerf 19 whose size and position satisfy the conditions described above.
e or a corner cut groove 19f is formed.

According to the structure of the internal magnetic shield member 16 of the cathode ray tube according to each of the above-described embodiments, the magnetic field lines of the correction member arranged near the corner portion of the internal magnetic shield member 16 pass through the opening and the panel of the cathode ray tube body. Since it can affect the electron beam emitted in the direction, the mislanding variation due to the chassis effect can be effectively corrected without reducing the shielding effect such as geomagnetism.

[0030]

According to the cathode ray tube of the present invention, it is possible to properly and effectively correct color purity deterioration and image distortion due to the chassis effect.

[Brief description of drawings]

FIG. 1 is an overall configuration diagram of a cathode ray tube according to the present invention.

FIG. 2 is an explanatory diagram of magnetic lines of force of the cathode ray tube of the present invention.

FIG. 3 is an explanatory diagram of magnetic lines of force of a correction member of the cathode ray tube of the present invention.

FIG. 4 is a perspective view of an internal magnetic shield member of the cathode ray tube of the present invention.

FIG. 5 is a perspective view showing another configuration of the internal magnetic shielding member of the cathode ray tube of the present invention.

FIG. 6 is a perspective view of a magnetic shielding member showing still another configuration of the cathode ray tube of the present invention.

FIG. 7 is a perspective view of a conventional magnetic shield member.

FIG. 8 is a perspective view of a conventional mislanding prevention member.

[Explanation of symbols]

 2 cathode ray tube tube body 9 frame 16 internal magnetic shielding member 18 correction member 19 opening

Claims (3)

[Claims] 1. An internal magnetic shield member extending along the inner surface of a funnel portion of the cathode ray tube body at the rear of a frame arranged so as to face the inner surface of the panel of the cathode ray tube body, and the cathode ray tube body. A correction member such as a magnet that corrects a chassis effect such as image distortion attached near a corner is provided, and an opening is formed in the vicinity of the corner of the internal magnetic shielding member to transmit the magnetic force lines of the correction member. Characteristic cathode ray tube. 2. The cathode ray tube according to claim 1, wherein the opening area of the inner magnetic shield member near the corner is 1 cm ² to 50 cm ² . 3. The center position of the opening of the internal magnetic shielding member is within 1/6 of the length of each side from the end of each side of the frame, and the position in the direction perpendicular to each side of the frame is the frame. The cathode ray tube according to claim 1 or 2, wherein the length is within 1/6 of the length of the long side.