JPH08287839A - Color picture tube - Google Patents

Abstract

PURPOSE: To provide a color picture tube having excellent landing characteristics by reducing influence on an electron beam by an external magnetic field such as earth magnetism. CONSTITUTION: In a rectangular cross-sectional hollow magnetic shielding body, a depth d1 of a notch part 49a of a long edge part 44 is made deeper than a depth d2 of a notch part 49b of a short edge part 46. A projecting part 48 is arranged on the center axis 45 of the long edge part 44. Therefore, an external magnetic field in a diagonal end part 43 is prevented from being excessively guided to the long edge part 44, and the external magnetic field is guided so as to approach in parallel to an electron beam, and influence of the external magnetic field can be reduced. An external magnetic field entering from the notch part in the vicinity of the central axis of the long edge part 44 is induced to the projecting part 48, and influence of the external magnetic field can be reduced without impairing a inducing effect of the diagonal end part 43.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color picture tube, and more particularly to a color picture tube capable of reducing the influence of an external magnetic field and obtaining good landing characteristics.

[0002]

2. Description of the Related Art In a color picture tube, when an undesired magnetic field generated from the earth's magnetism or an external circuit enters the passage area of the three electron beam, the three electron beam is affected by the undesired magnetic field, and the original It deviates from the orbit, causes so-called mislanding, and causes deterioration of color purity. Therefore, in the color picture tube, the magnetic shield is usually arranged inside the funnel where the three electron beam is most susceptible to the magnetic field.

This magnetic shield has a rectangular trapezoidal hollow trapezoidal shape as a basic structure. However, since the basic structure does not sufficiently shield the external magnetic field, the magnetic shield having various shapes and structures for more appropriately shielding the external magnetic field. Is being developed. For example,
Japanese Patent Application Laid-Open No. 5-159713 discloses a magnetic shield 80 in which a long side portion 84 and a short side portion 86 of a small opening 82 are provided with notches 88 having the same depth as shown in FIG. There is.

However, none of the conventional magnetic shields sufficiently induces an undesired magnetic field, and in particular, the geomagnetism incident in the tube axis direction largely deflects the orbit of the electron beam, resulting in deterioration of color purity, which is favorable. There is a problem that images cannot be obtained.

[0005]

As described above, the structure of the conventional magnetic shield does not sufficiently induce an undesired magnetic field, and in particular, the geomagnetism incident in the tube axis direction largely deflects the trajectory of the electron beam. However, there is a problem that the color purity is deteriorated and a good image cannot be obtained.

The present invention has been made in view of the above problems, and an object of the present invention is to provide a color picture tube for displaying a good image by using a magnetic shield having a structure that favorably induces an external magnetic field such as the earth magnetism. And

[0007]

According to the present invention, a cutout portion having a predetermined cutting depth is formed at a predetermined cutting angle from a diagonal end portion of a magnetic shield on the side of a small opening to a long side portion and a short side portion. A color picture tube, comprising: a magnetic shield provided and having a depth of a cutout portion of a long side portion deeper than a depth of a cutout portion of a short side portion.

Further, it is characterized in that a magnetic shield having a convex portion is provided substantially on the central axis of the cutout portion of the long side portion or on the central axis of each of the cutout portions of the long side portion and the short side portion. It is a color picture tube.

Further, according to the present invention, the depth of the cutout portion of the long side portion is made deeper than the depth of the cutout portion of the short side portion, and the cutout portion of the long side portion is substantially on the central axis, or the long side portion and the short side portion. A color picture tube characterized by comprising magnetic shields each having a protrusion on the central axis of each of the side cutouts.

In the present invention, the relationship between the long side portion and the short side portion is the relationship between the first side portion having a small angle with the tube axis direction and the second side portion having a large angle with the tube axis direction. It is also replaced with.

[0011]

When the tube axis of the color picture tube is parallel to the direction of the external magnetic field, the external magnetic field coming from near the diagonal end of the small opening of the magnetic shield is the result of the cutting. Is guided by the protrusions formed on the. At this time, if the depth of the notch is the same, the external magnetic field coming from near the diagonal end of the small opening is more strongly induced toward the long side than at the short side, and It cannot be made parallel to the electron beam near the part. This is because the magnetic shield used in a normal color picture tube has a hollow trapezoidal shape with a rectangular cross section corresponding to the aspect ratio of the panel, so the angle formed by the long side and the tube axis is the same as the short side. This is probably because the angle is smaller than the angle formed by the tube axis and there is a difference in the magnetic flux induction force.

By making the depth of the notch on the long side of the magnetic shield deeper than the depth of the notch on the short side, an external magnetic field coming from near the diagonal end of the small opening can be applied to the long side. It can be prevented from being excessively guided to, and the strength guided to the short side portion and the long side portion can be made into an optimum balance. As a result, the external magnetic field coming from near the diagonal end is guided in the direction along the ridge, and the external magnetic field is made parallel to the electron beam near the diagonal end, and the influence of the external magnetic field can be reduced. .

Further, by providing a convex portion substantially on the central axis of the cutout portion of the long side portion of the magnetic shield, or on the central axis of each of the cutout portions of the long side portion and the short side portion, the diagonal end portions are formed. It is possible to reduce the influence of the external magnetic field on the electron beam by inducing the external magnetic field entering from the vicinity of the central axis of the cut long and short sides to the convex portion without impairing the induction effect of the external magnetic field in the vicinity.

[0014]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A color picture tube according to the present invention will now be described in detail based on embodiments with reference to the drawings. (Embodiment 1) FIG. 1 shows a 15-inch type color picture tube which is an embodiment. The aspect ratio of this picture tube panel is 3: 4,
The deflection angle is 90 °, and the glass panel 1 has a substantially rectangular shape.
And a funnel-shaped glass funnel 2 integrally joined to the panel 1, and an inner surface of the panel 1 made of a three-color phosphor layer that emits red, green, and blue light. The phosphor screen 3 is formed, and the phosphor screen 3 is formed.
And a substantially rectangular shadow mask 4 inside the
Is arranged. The shadow mask 4 has a substantially rectangular mask body 5 in which a large number of electron beam passage holes are formed.
And a cross section L attached to the periphery of the mask body 5
The mask frame 6 has a substantially rectangular shape. On the other hand, the three electron beams 8R, 8
An electron gun 9 that emits G and 8B is arranged. Further, inside the funnel 2, a magnetic shield 20 is arranged for shielding the three electron beams 8R, 8G, 8B emitted from the electron gun 9 from an external magnetic field such as geomagnetism.

In the first embodiment, the magnetic shield 2
0 is formed by molding a metal magnetic plate having a plate thickness of about 0.1 to 0.3 mm. As shown in FIG. 1, the panel 1 side has a large opening 21 and the electron gun 9 side has a small opening. The portion 22 is formed in a hollow trapezoidal shape having a rectangular cross section.

Then, as shown in FIG. 2, a long side portion 24 as a first side portion and a short side portion 26 as a second side portion.
Has trapezoidal notches 28a and 28b each having the small opening 22 side as the bottom side, the notch 28a being at an angle α with respect to the central axis 25 of the long side 24, and the notch 28b being the short side 26.
Is cut at an angle β with respect to the central axis 27 of.

Here, the height h from the large opening 21 to the diagonal end 23 of the small opening 22 along the tube axis Z is about 105 mm.
And α is about 17 ° and β is about 30 °. The depth d1 of the cutout portion 28a of the long side portion 24 cut from the diagonal end portion 23 is about 40 mm, and the cutout portion 2 of the short side portion 26.
The depth d2 of 8b is about 10 mm.

Here, the long side portion 24 and the tube axis Z form an angle γ, and the short side portion 26 and the tube axis Z form an angle δ. Normally, the angle γ is smaller than the angle δ. ing. It is to be noted that FIGS. 7B and 7C show a state in which the long side portion 24 and the short side portion 26 are inclined with respect to the tube axis Z as shown in FIG. Since it is a view projected on, the dimensions of the long side portion 24 and the short side portion 26 themselves are different.

In the magnetic shield 20, the large opening 21 is fixed to the frame 6 by a fixing means such as a clip or welding.
It is placed inside the funnel 2 by being attached to.

In general, in order to reduce the influence of the geomagnetism on the electron beam, the electromagnetic force that the electron beam receives from the geomagnetism may be reduced. As shown in FIG. 3, if the geomagnetism B intersects the electron beam I at an angle ψ, the component of the geomagnetism B that exerts an electromagnetic force on the electron beam I is the component B1 orthogonal to the electron beam I.
Therefore, in order to reduce the electromagnetic force that the electron beam I receives from the geomagnetism B, it is necessary to reduce the component B1 orthogonal to the electron beam. For that purpose, the geomagnetism B is guided so as to be parallel to the electron beam I, and the electron beam I
It is better to reduce the angle ψ that intersects with.

To this end, the long side portions 2 from the four diagonal end portions 23 of the small opening 22 on the electron gun side of the magnetic shield 20.
4, and the cut angles and cut depths of the cutouts 28a and 28b of the short side portion 26 are optimally set so that the geomagnetism is provided in each diagonal end 23 of the small opening 22 so as to be parallel to the electron beam. The guidance can reduce the influence of the geomagnetism on the electron beam.

Inside the magnetic shield 20, the tube axis Z
Directional geomagnetism (hereinafter referred to as N / S geomagnetism) is extremely large, and horizontal geomagnetism (hereinafter referred to as E / W geomagnetism) at right angles to the tube axis Z direction has no significant effect on the amount of landing movement. Therefore, it is necessary to reduce the landing movement amount due to the influence of N / S geomagnetism. Therefore, the relationship between the landing movement amount due to the influence of N / S geomagnetism and the depth of the notch will be described.

4 (a), (b) and (c) show the depth of the notch 28a formed in the long side portion 24 and the notch 28b formed in the short side portion 26 of the magnetic shield 20, respectively. , A screen horizontal axis (hereinafter referred to as X axis) end portion 30 shown in FIG.
6 is a graph showing a relationship between an electron beam landing movement amount at a screen vertical axis (hereinafter referred to as Y axis) end portion 31 and a screen diagonal axis (hereinafter referred to as D axis) end portion 32. That is, in FIG. 9A, the short side portion 26 is not cut and the long side portion 24 is not cut.
The depth of the cutout portion 28a of the long side portion 24 is changed in the state in which the short side portion 26 is cut by 10 mm, and the depth of the cutout portion 28a of the long side portion 24 is changed. (C) in the drawing shows the state in which the short side portion 26 is cut by 20 mm and the depth of the cutout portion 28a of the long side portion 24 is changed.

From the figure, by making the depth of the cutout portion 28a of the long side portion 24 deeper than the depth of the cutout portion 28b of the short side portion 26, the landing movement amount at the D axis end portion 32 and the X axis end portion. It can be seen that the landing movement amount at 30 is decreasing.

Here, it is needless to say that the total sum of the landing movement amounts is reduced, and in addition to that, in addition to that, each shaft end portion 3
It is necessary to take care so that 0, 31, and 32 do not partially project to show a large landing movement amount.
For example, in FIG. 2B, the cutout portion 28 of the short side portion 26
When the depth of b is 10 mm and the depth of the cutout portion 28b of the long side portion 24 is 10 mm, the landing movement amount of the Y-axis end portion is about 8 μ.
m is a good value, but the X-axis end 30 and the D-axis end 3
2 are about 20 μm and about 18 μm, respectively, which are extremely worse than the Y-axis end portion 31. In this respect, it is not preferable that the difference between the shaft end portion having the largest landing movement amount and the shaft end portion having the smallest landing movement amount is about 10 μm or more. Further, since the D-axis end portion 32 has the largest deflection angle and the long reach distance of the beam, it needs to be considered more important than the other axis end portions. After considering these, each shaft end 30, 31,
It is preferable that the amount of landing movement of 32 is suppressed to within about 15 μm.

Taking these into consideration, when the long side portion 24 is cut to a depth of about 40 mm and the short side portion 26 is cut to a depth of about 10 mm, relatively good landing characteristics are obtained at each shaft end portion 30, 31, 32. You can see that

As described above, by forming the long side portion 24 and the short side portion 26 into the shapes as in this embodiment, the landing movement amount particularly at the D-axis end portion 32 and the X-axis end portion 30 can be reduced. You can

(Second Embodiment) Next, a second embodiment will be described. As shown in FIG. 5, in the magnetic shield 40 of the second embodiment, a semicircular convex portion 48 is provided on the central axis 45 of the cutout portion 49a of the long side portion 44. Except that the depth d3 from the diagonal end portion 43 to the apex of the semi-circular convex portion 48 is about 20 mm, other configurations, dimensions and the like are the same as those in the first embodiment.

2B and 2C show a state in which the long side portion 44 and the short side portion 46 are inclined with respect to the tube axis Z at angles γ and δ, as in FIG. Since it is a projected view, the dimensions of the long side portion 44 and the short side portion 46 themselves are different.

As shown in FIG. 4, as the depth d1 of the cutout portion 49a of the long side portion 44 is increased, the landing movement amount of the Y-axis end portion 31 increases, and the cutout portion of the short side portion 46 increases. 49
It can be seen that the landing movement amount of the X-axis end portion 30 increases as the depth d2 of b is increased.

Therefore, by providing a convex portion 48 having a depth d3 of about 20 mm to the apex on the central axis 45 of the long side portion 44 of the magnetic shield 40 having the above-mentioned cutout portions 49a and 49b, the long side portion Y-axis end 3 increased due to the cut in part 44
A landing movement amount of 1 can be compensated. By providing this convex portion 48, an external magnetic field coming from near the central axis 45 of the long side portion 44 of the small opening is effectively guided at a position closer to the electron gun, and is brought closer to the orbit of the electron beam.
Y without impairing the landing characteristics at the D-axis end 32
The amount of landing movement at the shaft end 31 can be reduced. At this time, it is desirable not to make the convex portion 48 too large so as not to affect the external magnetic field induction characteristic of the diagonal end portion 48.

(Embodiment 3) Furthermore, as a third embodiment,
As shown in FIG. 6, the convex portion 68 is provided on the central axis 65 of the cutout portion 69a of the long side portion 64, and the convex portion 70 is also provided on the central axis 67 of the cutout portion 69b of the short side portion 66. It can also be a structure.

In addition to the effects of the second embodiment, the structure of this embodiment can improve the landing characteristics at the X-axis end portion 30. However, the cutout portion 69b of the short side portion 66
Is shorter than the cutout portion 69a of the long side portion 64, and the convex portion 70 may impair the effect of inducing an external magnetic field at the diagonal end portion 63. Therefore, it is necessary to consider the size and height of the convex portion 70. is there. In this embodiment, the height of the apex of the convex portion 70 is the diagonal end portion 6
I made it almost the same as 3.

The present invention is not limited to a color picture tube having an aspect ratio of 3: 4, but may be a color picture tube having, for example, 9:16, and the deflection angle is not limited to 90 °. Further, the shadow mask 4 may be something like an aperture grill. Further, the shape of the notch may be a gentle curved shape. As described above, it goes without saying that many modifications and changes can be made to the embodiments within the scope of the present invention.

[0035]

As described above, according to the present invention,
It is possible to effectively induce an external magnetic field such as terrestrial magnetism, particularly an external magnetic field in the tube axis direction, to eliminate disturbance of the orbit of the electron beam, and to obtain a color picture tube with a small landing movement amount.

[Brief description of drawings]

FIG. 1 is a diagram showing a composition of a color picture tube in an embodiment of the present invention.

2A and 2B are views showing the shape of a magnetic shield in the first embodiment of the present invention, FIG. 2A is a perspective view of the whole, and FIG. 2B is a perspective view of a long side projected on a plane parallel to the tube axis. Projection view, (c) is a projection view in which the short side portion is projected on a plane parallel to the tube axis.

FIG. 3 is an explanatory diagram of an angle formed by a magnetic field and an electron beam.

4 (a), (b) and (c) are graphs showing the relationship between the depths of the cutout portions of the long side portion and the short side portion and the landing movement amount at each axial end portion of the screen, (d). [Fig. 3] is a schematic diagram showing each axial end of the screen.

5A and 5B are diagrams showing the shape of a magnetic shield in a second embodiment of the present invention, FIG. 5A is a perspective view of the whole, and FIG. 5B is a perspective view of a long side projected on a plane parallel to the tube axis. Projection view, (c) is a projection view in which the short side portion is projected on a plane parallel to the tube axis.

6A and 6B are views showing the shape of a magnetic shield in a third embodiment of the present invention, FIG. 6A is a perspective view of the whole, and FIG. 6B is a perspective view of a long side projected on a plane parallel to the tube axis. Projection view, (c) is a projection view in which the short side portion is projected on a plane parallel to the tube axis.

FIG. 7 is a view showing a shape of a conventional magnetic shield,
(A) is a perspective view of the whole, (b) is a projection view in which a long side is projected on a plane parallel to the tube axis, and (c) is a projection view in which a short side is projected on a plane parallel to the tube axis. .

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 ... Panel 2 ... Funnel 3 ... Phosphor screen 4 ... Shadow mask 7 ... Neck 8R, 8G, 8B ... Electron beam 9 ... Electron gun 20, 40, 60 ... Magnetic shield 22 ... Small opening 23, 43, 63 ... Diagonal end portions 24, 44, 64 ... Long side portions 25, 45, 65 ... Long side portion central axes 26, 46, 66 ... Short side portions 27, 47, 67 ... Short side portion central axes 28a, 49a, 69a ... Notches on long sides 28b, 49b, 69b ... Notches on short sides 48, 68, 70 ... Projections Z ... Pipe axis

Claims (10)

[Claims] 1. A rectangular panel having a phosphor screen formed on an inner surface thereof, a funnel-shaped funnel joined to the panel, an electron gun disposed at a neck portion of the funnel, and emitting an electron beam, A shadow mask, which is arranged inside the panel so as to face the phosphor screen and has a plurality of electron beam passage holes, and two long side portions which are arranged inside the funnel and face each other 2 A hollow trapezoidal magnetic shield having two short sides and a small opening on the electron gun side in the tube axis direction, wherein the long side and the short side extend from a diagonal end of the small opening. Each of the portions is provided with a notch having a predetermined notch depth at a predetermined notch angle, and the depth of the notch of the long side is deeper than the notch of the short side, and a magnetic shield. Color picture tube characterized by 2. A rectangular panel having a phosphor screen formed on an inner surface thereof, a funnel-shaped funnel joined to the panel, an electron gun arranged at a neck portion of the funnel and emitting an electron beam, A shadow mask, which is arranged inside the panel so as to face the phosphor screen and has a plurality of electron beam passage holes, and two long side portions which are arranged inside the funnel and face each other 2 A hollow trapezoidal magnetic shield having two short sides and a small opening on the electron gun side in the tube axis direction, wherein the long side and the short side extend from a diagonal end of the small opening. And a magnetic shield having a projection on the central axis of at least the cutout portion of the long side, the cutout portion having a predetermined cut angle and a predetermined cut depth. A color picture tube. 3. The color picture tube according to claim 2, further comprising magnetic shields each having a convex portion on a central axis of each of the cutout portions of the long side portion and the short side portion. tube. 4. The color picture tube according to claim 1, further comprising a magnetic shield having a projection on at least a central axis of the cutout portion of the long side portion. 5. The color picture tube according to claim 1, further comprising magnetic shields each having a convex portion on a central axis of each of the cutout portions of the long side portion and the short side portion. tube. 6. A rectangular panel having a phosphor screen formed on an inner surface thereof, a funnel-shaped funnel joined to the panel, an electron gun arranged at a neck portion of the funnel, and emitting an electron beam, A shadow mask that is arranged inside the panel facing the phosphor screen and has a plurality of electron beam passage holes, and two first side portions that are arranged inside the funnel and face each other. Has a hollow trapezoidal shape having two small sides on the electron gun side in the tube axis direction, and the angle between the first side and the tube axis is the second side. A magnetic shield smaller than the angle formed by the tube axis and the diagonal axis of the small opening from the first side portion to the second side portion at a predetermined cutting angle at a predetermined cutting depth. Is provided with a notch portion, and the first side portion Color picture tube depth of the notch is characterized by comprising a magnetic shield deeper than the depth of the notch of the second side portion. 7. A rectangular panel having a phosphor screen formed on an inner surface thereof, a funnel-shaped funnel joined to the panel, an electron gun disposed at a neck portion of the funnel, and emitting an electron beam, A shadow mask that is arranged inside the panel facing the phosphor screen and has a plurality of electron beam passage holes, and two first side portions that are arranged inside the funnel and face each other. Has a hollow trapezoidal shape having two small sides on the electron gun side in the tube axis direction, and the angle between the first side and the tube axis is the second side. A magnetic shield smaller than the angle formed by the tube axis and the diagonal axis of the small opening from the first side portion to the second side portion at a predetermined cutting angle at a predetermined cutting depth. Is provided with a notch, and at least the above Color picture tube characterized by comprising a magnetic shield having a convex portion on the center axis of the cutout portion of one side portion. 8. The color picture tube according to claim 7, further comprising magnetic shields each having a convex portion on a central axis of each of the cutout portions of the first side portion and the second side portion. And a color picture tube. 9. The color picture tube according to claim 6, further comprising a magnetic shield having a convex portion on at least a central axis of the cutout portion of the first side portion. 10. The color picture tube according to claim 6, further comprising magnetic shields each having a protrusion on a central axis of each of the cutout portions of the first side portion and the second side portion. And a color picture tube.