JPH11283524A - Color cathode ray tube - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a cathode ray tube with reduced top and bottom inner pin cushion strains, right and left inner luminescent line strains, and easily workable inner magnetic shield by forming a cut-out part, having a shape whose width is gradually extended as approaching the terminal edge of the phosphor screen side on the slanting surface on the long side of an inner magnetic shield. SOLUTION: An inner magnetic shield 7 is formed with a pair of long side slanting surfaces 11 and a pair of short side slanting surfaces. A trapezoidal cut-out part 16 having one bottom whose length is (a) in an electron gun side terminal edge 14 and a phosphor screen side bottom 15, whose length is (b) in a phosphor screen side terminal edge 17, is formed on an electron gun side opening part side on the long side slanting surface 11. Length (a) and length (b) have the relation a<b, and preferably satisfy the relation 1<b/a<=1.5. A cutting-out angle (c) formed by the electron gun side terminal edge 14 and a cutting-out side 21 is preferably equal to or larger than the minimum value of the incidence angle formed by the orbit of electron beams and the electron gun side terminal edge.

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, and more particularly to a structure of an internal magnetic shield for correcting raster distortion of a fluorescent screen.

[0002]

2. Description of the Related Art In a color cathode ray tube used as a display monitor of a personal computer, a fine display of a screen at a peripheral portion of the screen is required. In such a case, raster distortion is one of the important factors that determine the image quality of the peripheral portion of the screen. The raster distortion includes a vertical pincushion distortion p indented by a horizontal line 71 of the raster in the fluorescent screen 4 shown in FIG.
Also, there are left and right pincushion distortions in which vertical lines are dented, and reduction of these distortions is required to improve image quality.

Regarding the upper and lower pincushion distortions p, magnets are attached above and below the front end of the deflection yoke (Japanese Patent Laid-Open No. 310047/1994), for example, to apply a magnetic field from outside the cathode ray tube to the electron beam. Corrections have been made. When a magnet is used, the electron beam receives a force in a certain direction due to the magnetic field distribution formed by the magnet at the front end of the deflection yoke, and the vertical pincushion distortion p is corrected. By increasing the influence of the magnet at the front end of the deflection yoke, the upper and lower pincushion distortion p
In order to increase the amount of correction, the one described in JP-A-6-310047 is provided with a V-shaped notch on the long side inclined surface of the internal magnetic shield provided in the cathode ray tube. The method increases the correction effect.

In general, the distortion of the vertical deflection magnetic field of the deflection yoke is a strong barrel distortion from the viewpoint of self-convergence. Therefore, for example, when a cross hatch pattern (grating) is projected on the screen of a cathode ray tube, the vertical lines exhibit pincushion distortion. For this reason, the correction circuit provided on the set side of the color cathode ray tube corrects the vertical line so as to be linear.

[0005] However, as shown in FIG. 8, a vertical line 81 that forms the lateral outline of the cross hatch pattern is formed.
Is corrected to a linear shape, the vertical line 82 at a position inward toward the center of the screen may not be linear, and internal pincushion distortion may remain. This is called left and right inner xen distortion q. This is disclosed in JP-A-8-171.
As shown in FIG. 9 of Japanese Patent Publication No. 866, an excessive barrel distortion in the vertical space near the vertical axis of the vertical deflection magnetic field, which leaks near the electron gun side opening of the internal magnetic shield, is a cause. ing.

With respect to the left and right inner xen strains q caused by such a cause, for example, as shown in JP-A-8-171866, the fluorescent screen side By providing a trapezoidal or V-shaped notch that narrows as it goes to, and by providing a partition, the effect of attracting and concentrating the vertical deflection magnetic field leaking near the electron gun side opening of the internal magnetic shield Strengthen
There is a method capable of reducing the left and right inner xen strains q.

[0007]

However, a trapezoidal or V-shaped notch is formed on the long side of the inner magnetic shield, on the side of the electron gun side, where the width decreases toward the fluorescent screen. Even if only the upper and lower pincushion distortions p can be sufficiently corrected, the effect of attracting and converging the vertical deflection magnetic field leaking to the vicinity of the opening on the electron gun side of the internal magnetic shield is weak, and the left and right inner xen distortions q Magnetic field strength required to reduce the
There was a problem that the left and right inner xen strains q remained largely.

[0008] When the trapezoidal cutout portion is provided with a partition portion protruding in the direction of the inner wall of the funnel, the higher the height of the partition portion, the more the left and right inner xen strains q can be reduced. Since this height is determined by the allowance with the funnel, it is difficult to further improve the reduction effect by design, and the provision of a partitioning section makes it difficult to maintain the allowance with the funnel, and has difficulty in manufacturing. I was

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems of the prior art, and includes an upper and lower pincushion distortion correcting magnets located above and below the front end of a deflection yoke, and a method for controlling the deflection yoke. The effect of a magnetic field from the outside of the cathode ray tube on the electron beam, such as deflection magnetic field and geomagnetism, is increased by providing a trapezoidal notch on the long side of the internal magnetic shield, and near the electron gun side opening. Provided is a color cathode ray tube having an internal magnetic shield that enhances the attracting and focusing effect of a leaking vertical deflection magnetic field, sufficiently reduces upper and lower inner pincushion distortion and left and right inner xensen distortion, and is easy to process in terms of manufacturing. It is an object.

[0010]

To achieve the above object, a color cathode ray tube according to the present invention comprises a panel and a funnel forming an envelope, a fluorescent screen formed on an inner surface of the panel, and a fluorescent screen formed on the inner surface of the panel. An electron gun that emits an electron beam is accommodated in the neck portion, and the fluorescent screen side terminal edge is long and the electron gun side terminal edge is short. ,And,
In a color cathode ray tube accommodating an internal magnetic shield provided with a cutout portion on the long side inclined surface inside the envelope, the cutout portion has a width as approaching the fluorescent screen side terminal edge. Are spread out (claim 1).

As described above, by providing a cutout portion in the internal magnetic shield so that the cutout region extends in the direction of the fluorescent screen, a magnetic field from outside the cathode ray tube is not interrupted by the internal magnetic shield, and the magnetic field from the inside of the internal magnetic shield is not interrupted. The magnetic field intensity required to correct the upper and lower pincushion distortion of the electron beam can be obtained, and the leakage vertical deflection magnetic field in the vertical space near the vertical axis of the electron gun side opening of the internal magnetic shield can be obtained. Barrel distortion can be reduced, and left and right inner xen distortion can be corrected.

Further, in the color cathode ray tube according to claim 1, the notch portion is a trapezoidal notch portion, and one of the long side inclined surfaces has a length a at a terminal edge on the electron gun side of the long side. A bottom having a length b at the end edge on the fluorescent screen side, wherein the lengths a and b are a
It is preferable to have a relationship of <b (claim 2).

According to this configuration, since the electron beam travels along the cutout side of the trapezoidal cutout portion, the trapezoidal cutout becomes narrower as it approaches the conventional V-shaped or fluorescent screen side terminal end. The influence of the magnetic field that corrects the left and right inner xensen distortions can be exerted over a longer range of the electron beam trajectory than in the notched portion. In addition, since it is a simple shape that can be formed by punching, it is easy to manufacture,
Material yield is improved.

In the color cathode ray tube according to claim 2, an angle formed between one side of the trapezoidal cutout portion sandwiched between the two bottoms and the electron gun side terminal edge is defined as a cutout angle. When the angle formed between the trajectory of the electron beam and the electron gun-side terminal edge is the incident angle, the notch angle is preferably equal to or greater than the minimum value of the incident angle. 3).

4. The color cathode ray tube according to claim 3, wherein one side of the trapezoidal cutout portion sandwiched between the two bottoms and a predetermined electron beam selected from the electron beams. It is preferable that the trapezoidal notch is formed so that the orbit of the trapezoid is substantially parallel (claim 4), or the notch angle is substantially equal to the incident angle of the predetermined electron beam (claim). Item 5). With such a configuration, the influence of the magnetic field for correcting left and right inner xen distortion can be uniformly and strongly exerted over a longer range of the electron beam trajectory.

Further, in the color cathode ray tube according to claim 4, the predetermined electron beam reaches a range of １ ／ of the left and right length of the fluorescent screen from both right and left ends of the fluorescent screen. It is preferably an electron beam that emits light. With this configuration, it is possible to correct an electron beam that reaches the above range where the left and right inner xen distortions are particularly large.

In the color cathode ray tube according to claim 2, the length a of the one bottom and the length b of the other bottom are provided.
Preferably satisfy the relationship of 1 <b / a ≦ 1.5 (claim 6). With this configuration, the maximum correction effect can be obtained for the electron beam reaching near the left and right ends of the fluorescent screen.

[0018]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS As shown in FIG. 3, a color cathode ray tube 1 of the present invention comprises an envelope comprising a panel 2 made of glass and a funnel 3, and a fluorescent screen 4 provided on the inner surface of the panel 2. A shadow mask 5 provided substantially parallel to the fluorescent screen 4; a frame 6 for supporting the shadow mask 5; an internal magnetic shield 7; and an electron gun (not shown) provided at the neck of the funnel 3. ).

RG emitted from an in-line type electron gun
The electron beam 8 corresponding to each of the B colors passes through a predetermined hole provided in the shadow mask 5 and reaches the phosphor on the fluorescent screen 4 corresponding to each of the RGB colors. Each phosphor irradiated with the electron beam 8 emits each color of RGB, and displays a color image on the screen of the panel 2.

When the color cathode ray tube of the present invention is used, a deflection yoke is provided at the neck of the funnel 3 (not shown), and a pair of magnets are provided above and below the front end (the fluorescent screen 4 side) of the deflection yoke. (Not shown). When viewed from the fluorescent screen 4 side, the right side of the upper magnet is the north pole and the left side is the south pole, and the right side of the lower magnet is the south pole and the left side is the north pole.

As shown in FIG.
Is formed by a pair of long side inclined surfaces 11 and a pair of short side inclined surfaces 12. On the side of the electron gun side opening portion 13 of the long side inclined surface 11, one bottom having a length a on the electron gun side terminal edge 14 is provided with a length b on the side of the fluorescent screen side terminal edge 17.
And a trapezoidal notch 16 having a bottom 15 on the fluorescent screen side.

FIG. 2 is a side view of the long side of the internal magnetic shield 7. The notch angle c of the trapezoidal notch 16 is an angle formed between the electron gun side end edge 14 and the notch side 21,
It is preferable to match the incident angle d of the electron beam for which the greatest correction effect is desired. That is, the "predetermined electron beam" referred to in claims 4 to 6 is an electron beam that reaches the upper and lower edges of the fluorescent screen, and its arrival point is greatest toward the center of the screen surface in the left-right direction. An electron beam that is intended to be moved. In other words, the arrival point on the fluorescent screen is the electron beam that moves most from the arrival point when there is no notch due to the electron beam trajectory correcting action of the trapezoidal notch.

As shown in FIG. 4, a vertical line 41 (FIG. 4) at a desired position before correction (without trapezoidal notch) is provided.
When the electron beam reaching the point A is coincident with the notch angle c and the electron beam is shifted to the point B, the curve B shown in FIG.
The size of the trapezoidal cutout portion 16 is appropriately adjusted so as to reach. At this time, the trajectories of electron beams other than the electron beam incident at a predetermined incident angle d are also corrected, but the correction amount is smaller than the predetermined electron beam.

In the case of three in-line electron beams, the incident angle of the middle electron beam is used as a reference.

As a preferred example of the internal magnetic shield used for a 46 cm (19 inch) -100 ° color cathode ray tube, the material is a mild steel plate having a thickness of 0.13 [mm], a long side inclined surface 11 and The length of the fluorescent screen side terminal edge 17 of the short side inclined surface 12 is 360 [mm] and 276 [mm], respectively, and the length of two bottoms of the trapezoidal cutout portion 16 is a = 110 [mm], b = 142 [mm], and the notch angle c of the trapezoidal notch 16 is 75 °.

Next, the effect of correcting vertical pinch distortion and left and right inner xen distortion according to the present invention will be described.

FIG. 5 shows the notch depth (terminal edge 14 on the electron gun side).
This shows the relationship between the notch angle c and the upper and lower pincushion distortion p on the fluorescent screen under the condition that the distance from the fluorescent screen to the bottom 15 on the fluorescent screen side is constant. The horizontal axis shows the notch angle c, and the vertical axis shows the magnitude (%) of the upper and lower pincushion distortion p with respect to the raster size. On the vertical axis, a positive value indicates pincushion distortion, and a negative value indicates barrel distortion. When the notch angle c on the horizontal axis is 180 °, it indicates that there is no notch, and the trapezoidal notch referred to in the present invention is included in a range where the notch angle c is smaller than 90 °.
The value of the upper and lower pincushion distortion p was measured at a point on the phosphor screen where the electron beam at which the incident angle d was the same as the notch angle c of 75 ° reached.

As shown in FIG. 5, it can be seen that the smaller the notch angle c, the larger the correction amount of the upper and lower pincushion distortion p. This is because if the depth of the trapezoidal notch 16 is constant, the area of the trapezoidal notch 16 increases as the cutting angle c decreases, so that the magnetic field generated from the magnet at the front end of the deflection yoke is This is because it is easy to enter the inside of the internal magnetic shield 7 without being blocked by the magnetic shield 7, and the force in the direction of correcting the upper and lower pincushion distortion p acting on the electron beam increases.

When the notch angle c is 75 °, the barrel distortion (P = −0.1 [%]) is slightly increased, but the maximum correction effect can be obtained. At this time, the upper and lower pincushion distortion is improved by 4.6% from + 4.5% to -0.1% as compared with the case where the trapezoidal notch is not provided (c = 180 °). . This is because the maximum correction effect can be obtained when the notch angle c matches the incident angle d of the electron beam.

FIG. 6 shows the relationship between the notch angle c and the right and left inner xen distortions q (indicated by the absolute value, not the ratio to the size of the raster), similarly to FIG.
The notch angle c and the predetermined electron beam incident angle d (75
゜) approaches, and as the notch side 21 approaches the trajectory of the electron beam in parallel, the left and right inner xen strains q are reduced from 2.0 [mm] to 0.2 [mm], and 90
It can be seen that [%] is also improved.

Table 1 shows a comparison example of the correction effect between the present invention and the conventional example. In the conventional example, a partition portion is provided in a V-shaped trapezoidal cutout portion described in JP-A-8-171866.

[0032]

[Table 1]

As shown in Table 1, according to the present invention, it can be seen that a greater reduction effect can be obtained as compared with the conventional example. This is achieved by providing the trapezoidal notch 16
The effect of the attracting and focusing effect of the vertical deflection magnetic field is increased by making the notch side 21 and the trajectory of the electron beam parallel to each other, while increasing the effect of attracting and focusing the vertical deflection magnetic field around the trapezoidal cutout portion 16. Has been obtained to work over a long range of

In FIG. 2, as the distance between the trajectory of the electron beam 8 and the cutout side 21 is reduced, a stronger correction effect can be obtained.

The ratio between the lengths a and b of the two bottoms of the trapezoidal cutout portion 16 is preferably in the range of 1 <b / a ≦ 1.5. If b / a is 1 or less, the notch does not have a trapezoidal shape, and a desired distortion correction effect cannot be obtained. on the other hand,
It is difficult in design to make b / a 1.5 or more. The left and right inner xen distortions are particularly large in the range of 1/4 at both the left and right ends of the phosphor screen. To obtain a sufficient correction effect in this range, the maximum electron beam reaching near the left and right ends of the phosphor screen is required. This is because it is necessary to obtain a correction effect, and it is necessary to increase the upper base a to some extent.

As described above, the present invention has the bottom of length a at the electron gun-side terminal edge 14 of the long side inclined surface 11 of the internal magnetic shield 7 and the bottom of length b at the fluorescent screen 4 side. By providing the trapezoidal notch 16, the electron beam can receive a large force in the direction of correcting the vertical pincushion distortion by the magnetic field of the magnet of the deflection yoke. Further, by making the notch angle c of the trapezoidal notch 16 close to the incident angle d when the electron beam enters the internal magnetic shield 7, the barrel of the vertical deflection magnetic field leaking around the trapezoidal notch 16 is formed. The distortion can be reduced, and the effect of the magnetic field can be given to the electron beam in a long area.

Although the trapezoidal notch has been described in the above embodiment, similar effects can be obtained as long as the notch has a shape whose width increases as approaching the end edge on the fluorescent screen side. Therefore, the bottom 15 and the cutout side 21 on the fluorescent screen side may be curved. When the left and right inner xen strains occur asymmetrically, the shape of the notch may be asymmetrical.

The present invention is particularly effective when a magnet is used.
A similar effect is exerted on any external magnetic field according to the strength of the magnetic field.

[0039]

As described above, the present invention provides a deflection yoke by providing a notch having such a shape that its width increases as it approaches the fluorescent screen side terminal edge on the long side inclined surface of the internal magnetic shield. Increasing the effect of the external magnetic field on the electron beam, such as the upper and lower pincushion distortion correction magnets arranged above and below the front end, and further increasing the attracting and focusing effect of the vertical deflection magnetic field leaking near the electron gun side opening,
It is possible to sufficiently reduce the upper and lower inner pincushion distortion and the left and right inner xen distortion, thereby providing a high quality color cathode ray tube. Further, the shape of the cutout portion of the internal magnetic shield is a simple shape that can be formed by punching, so that it is easy to manufacture and the yield of materials can be improved.

[Brief description of the drawings]

FIG. 1 is a perspective view of an internal magnetic shield used in a color cathode ray tube of the present invention.

FIG. 2 is a side view of the internal magnetic shield.

FIG. 3 is a partially cutaway side view of the color cathode ray tube of the present invention.

FIG. 4 is a diagram for explaining correction of left and right inner pin cushion distortions;

FIG. 5 is a diagram showing a relationship between a notch angle of a trapezoidal notch portion of an internal magnetic shield and upper and lower pincushion distortions.

FIG. 6 is a diagram showing a relationship between a notch angle and left and right inner xen strains.

FIG. 7 is a diagram for explaining vertical pincushion distortion.

FIG. 8 is a diagram for explaining left and right inner xen distortions;

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Color cathode ray tube 2 Panel 3 Funnel 4 Fluorescent screen 5 Shadow mask 7 Internal magnetic shield 8 Electron beam 11 Long side inclined surface 12 Short side inclined surface 13 Electron gun side opening 14 Electron gun side terminal edge 15 On fluorescent screen side Bottom 16 Trapezoidal cutout 17 Fluorescent screen side terminal edge 21 Notch side

Claims (7)

[Claims] 1. A panel and a funnel constitute an envelope, a fluorescent screen is formed on an inner surface of the panel, and an electron gun for emitting an electron beam is accommodated in a neck portion of the funnel. An internal magnet having a pair of long side slopes and a pair of short side slopes having a long side terminal edge and a short electron gun side terminal edge, and a cutout provided in the long side slope. A color cathode ray tube accommodating a shield inside the envelope, wherein the notch has a shape such that its width increases as approaching the phosphor screen side terminal edge. 2. The notch is a trapezoidal notch,
The long side inclined surface has one bottom having a length a at the electron gun side terminal edge and the other end having a length b at the fluorescent screen side terminal edge, and has the length a. And b
The color cathode ray tube according to claim 1, wherein a has a relationship of a <b. 3. An angle formed between a side of the trapezoidal cutout portion sandwiched between the two bottoms and an end edge on the electron gun side is defined as a cutout angle, and the trajectory of the electron beam and the electron gun side are formed. 3. The color cathode ray tube according to claim 2, wherein the notch angle is equal to or greater than a minimum value of the incident angle, where an angle formed by the terminal edge is an incident angle. 4. The method according to claim 1, wherein one side sandwiched between the two bottoms of the trapezoidal cutout portion is substantially parallel to a trajectory of a predetermined electron beam selected from the electron beams. The color cathode ray tube according to claim 3, wherein a trapezoidal cutout portion is formed. 5. The color cathode ray tube according to claim 3, wherein the notch angle is substantially equal to an incident angle of the predetermined electron beam. 6. The electron beam as claimed in claim 3, wherein the predetermined electron beam is an electron beam that reaches from the left and right ends of the fluorescent screen to a range of １ ／ of the left and right length of the fluorescent screen. Or a color cathode ray tube according to 4. 7. The length a of the one bottom of the trapezoidal cutout portion and the length b of the other bottom are 1 <b / a ≦ 1.5.
3. The color cathode ray tube according to claim 2, wherein the following relationship is satisfied.