JPH0518219B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Field of Industrial Application] The present invention relates to a shadow mask type color cathode ray tube device.

[Conventional technology]

Generally, in this type of device, as shown in FIG. 8, a shadow mask type color cathode ray tube 1 includes a panel 2 which is a glass front plate, a funnel 3 connected to the panel 2 and having a substantially conical shape, and a cylindrical glass tube. It is composed of a vacuum container consisting of a neck portion 4, which is a tube, and the like.

On the inner surface of the panel 2, a phosphor screen 5 consisting of a collection of phosphor dots or stripes called a phosphor mosaic element is provided. A shadow mask 6 having a large number of holes 6a arranged in a pattern is arranged.

A plurality of electron guns 7 are built into the network part 4, and electron beams 10 are emitted from the electron guns 7.
0 (only one of the plurality of wires is shown in the figure) is bent by the magnetic field of the deflection yoke 30 attached to the outside near the connection between the funnel 3 and the neck portion 4, and then passes through the hole 6a of the shadow mask 6. fluorescent screen 5
to shoot at. For example, it passes through one of the holes 6a and hits a phosphor dot 5a whose correspondence with the hole 6a is predetermined, causing it to emit light.

Now, if the electron beam 100 passing through the hole 6a of the shadow mask 6 correctly strikes the corresponding phosphor dot 5a, light of the correct color will be obtained, and this is said to be a state of good purity. However, in actual color cathode ray tubes 1, this relationship is impaired due to various causes, resulting in poor integrity. The cause of this is the influence of an unnecessary magnetic field (hereinafter simply referred to as terrestrial magnetism) that exists globally at the location where the color cathode ray tube 1 is operated, such as the earth's magnetism, so as to cover the entire color cathode ray tube. In other words, with this magnetic field, the electron beam 1
00 does not follow the originally planned trajectory and is undesirably bent. As a result, even if the electron beam 100 passes through the hole 6a of the shadow mask 6, it does not strike the predetermined phosphor dot 5a accurately, but instead strikes other phosphor dots, making it impossible to emit light of the correct color. . This is called the deterioration of the purity characteristic.

In order to improve such symptoms, in conventional shadow mask type color cathode ray tube devices, an external magnetic shield 8a surrounding the outer periphery of the funnel 3 or an internal magnetic shield 8b inside the funnel 3 is generally disposed. ing. All of these are formed into a conical shape substantially similar to the funnel 3 using a metal plate with high magnetic permeability such as an iron plate, and are attached to the outside or inside of the funnel 3, or both, by an appropriate method. With such a configuration, the electron beam traveling in the space surrounded by the shields 8a and 8b is prevented from being unnecessarily bent by the earth's magnetism, and therefore the earth's magnetic field having the above-mentioned piyury property characteristic is suppressed. The deterioration caused by

[Problem that the invention seeks to solve]

However, even if the above-mentioned method of shielding the funnel 3 is used, it is difficult to completely eliminate the influence of the earth's magnetism, which is not initially planned, on the privacy characteristics. Therefore, the current situation is that there is a demand for further improvement in the above-mentioned pulley properties. The inventors discovered that the component of an undesirable magnetic field such as earth's magnetism is composed of a component parallel to the tube axis of the color cathode ray tube 1 (the center axis of the network portion 4) and a component perpendicular to this, and that the latter component has a pyurity characteristic. They found a way to reduce the impact on the environment and completed this invention.

That is, an object of the present invention is to provide a color cathode ray tube device that can effectively avoid the influence of earth's magnetism on the image quality characteristics.

[Means for solving problems]

A color cathode ray tube device according to the present invention is located on the rear side of a deflection yoke attached near a connecting portion between a funnel and a neck portion of a color cathode ray tube, and is arranged outside the neck portion and perpendicular to the axis of the neck portion. A magnetic material with high magnetic permeability (hereinafter referred to as a concentrator) is provided to collect unnecessary magnetism such as earth's magnetism, which has a source other than the deflection yoke existing in the direction, and concentrate it in the above-mentioned network portion.

[Effect]

In this invention, the concentrator placed outside the neck collects the magnetic flux of the component perpendicular to the tube axis of the earth's magnetic field, increases the magnetic flux crossing the tube axis in this part, and the electron beam passes through the neck. The effect of the component of the geomagnetic flux perpendicular to the tube axis on the tube axis is increased compared to the case without the concentrator. The influence of the component of earth's magnetism perpendicular to the tube axis on the integrity characteristics is opposite between the front side (funnel side) and the rear side (neck side) of the deflection yoke.

In the case of ordinary color cathode ray tubes, the former almost entirely determines the influence on the image quality characteristics rather than the latter. Therefore, by increasing the latter, it is possible to cancel the influence of the former and reduce the influence of the pieurity characteristic of the component perpendicular to the tube axis of the earth's magnetic field.

[Embodiments of the invention]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic top view showing an example of a color cathode ray tube device according to the present invention. In the figure, 20
is a concentrator. The concentrator 20 is made of a plate-shaped material having high magnetic permeability such as permalloy or ferrite, and is located on the rear side of the deflection yoke 30 in a plane perpendicular to the central axis of the neck portion 4. This concentrator 20
As shown in Figure 2, the top and bottom are one set,
Each has a substantially trapezoidal shape, and the short side portion 21 of the trapezoid is disposed in contact with or close to the outer periphery of the neck portion 4.

By arranging such a concentrator 20, it is possible to prevent the deterioration of the magnetic field due to the component of earth's magnetism perpendicular to the plane of the paper. The effects of this will be explained in detail below.

FIG. 3 is a diagram for explaining the influence of the component of earth's magnetism perpendicular (to the plane of the paper) on the pieurity characteristics. First, among the electron beams when there is no vertical component of the earth's magnetism, the one that passes through the hole 6a of a specific shadow mask 6 is defined as 100a, and this electron beam 10
The point where 0a hits the fluorescent screen 5 is 5a. The electron beam 100a from the electron gun 7 is deflected by the deflection yoke 30, passes through the hole 6a of the shadow mask 6, and reaches a predetermined injection point 5a on the inner surface of the panel (electron gun 7
generally emits multiple electron beams, but in order to consider the phenomenon we are currently considering, it is necessary to
It is enough to think about books.)

Next, it is assumed that a magnetic flux of a component of earth's magnetism perpendicular to the plane of the paper exists from the back to the front of the paper, and that such magnetic flux is distributed only between the deflection yoke 30 and the fluorescent screen 5. Then, the electron beam travels along the same trajectory as described above until it reaches the inside of the deflection yoke 30, but after passing through the deflection yoke 30, it is bent to the left in the direction of travel by the problematic component of the earth's magnetism.
The trajectory shown by the dotted line 100b in the figure passes through the hole 6a of the shadow mask 6 and hits the inner surface of the panel at a point 5b. This point 5b is deviated from the correct injection point 5a, which results in undesirable deterioration of the pilotage characteristics.

Next, it is assumed that the magnetic flux of the component of earth's magnetism perpendicular to the plane of the paper exists from the back to the front of the paper, and that such magnetic flux is distributed only between the electron gun 7 and the deflection yoke 30. By the time the electron beam reaches the deflection yoke 30, it has already been bent to the left in the direction of travel, but after passing through the area of the deflection yoke 30, it is assumed that there is no extra bending due to the earth's magnetic field, so the electron beam is curved to the left by the dashed line 100c in the figure. The object having the trajectory shown passes through the hole 6a of the shadow mask 6 and hits the inner surface of the panel at a point 5c. This point is different from the correct injection point 5a, and therefore undesirable deterioration of the pilotage characteristics occurs.

By the way, as is clear from Figure 3, the firing point 5
b and 5c are in opposite directions with respect to the correct firing point 5a. That is, the influence of the component of the earth's magnetism on the injection point is opposite to the influence of the magnetic flux until the electron beam 100 reaches the deflection yoke 30 and the influence of the magnetic flux received after passing through the deflection yoke 30. In a normal color cathode ray tube device, the influence of this magnetic flux usually affects the entire trajectory of the electron beam, but it is much larger before and after the deflection yoke 30, so it passes through the hole 6a of the shadow mask 6. The injection point of the ivy electron beam is 5b
It can only shift in the following directions. Therefore, if the influence of the earth's magnetism that the electron beam receives before reaching the deflection yoke 30 can be increased, the effects before and after the deflection yoke 30 can cancel each other out, and the deterioration of the integrity characteristics can be suppressed ( So far, we have only considered the phenomenon at a specific point on panel 2, but this phenomenon occurs over the entire surface of panel 2 and is of approximately the same order of magnitude, so there are no countermeasures. However, a certain amount of correction is effective for improving the entire surface of the panel 2, although there may be some excess or deficiency.)

The concentrator 20 shown in FIG. 1 is provided so that the amount of bending of the electron beam before it enters the deflection yoke 30 by the vertical component of the earth's magnetism is increased. As a result, the vertical component Φ of the earth's magnetic field concentrates as shown in FIG.
The magnetic flux density inside the electron beam becomes higher than normal, and the influence of the geomagnetic component on the electron beam 100 after passing through the deflection yoke 30 is canceled out.

The concentrator 20 has a trapezoidal shape as is usually adopted in this type of magnetic flux concentrator, but
Generally speaking, the width Wa of the side 21 which is made of a high magnetic permeability material and which is close to the neck 4 is in the relationship Wd with respect to the diameter d of the neck 4, and the side farthest from the neck 4 is Either the width Wb of 22 or the length H between one side 21 and the other side 22 is approximately 4, which is larger than the diameter d of the neck portion 4.
The side-shaped member may be arranged in a plane perpendicular to the axis of the neck portion 4. Generally speaking, the area of one concentrator 20 needs to be at least larger than the cross-sectional area of the neck portion 4.

Therefore, for example, as shown in FIG. 5, a rectangular metal plate of constant width and length H is connected to the concentrator 2.
May be used as 0. Furthermore, as shown in FIG. 6, it is also possible to use as the concentrator 20 an L-shaped concentrator whose tip end is bent backward in the tube axis direction so that the amount of lateral protrusion is reduced and the magnetic flux is collected as much as possible. be.

Furthermore, it is not necessary that there be a pair of concentrators 20 on the neck portion 4, one above the other, and in some cases, a certain effect can be expected even with only one concentrator 20. Typically,
As is clear from FIG. 3, in order for the electron beam incident on the deflection yoke 30 to be bent and, as a result, the point of impact of the electron beam on the panel 2 to be shifted from the point 5a as shown in 5c, the electron beam must be It is necessary to curve the beam so that it distances itself from the original electron beam (which is not affected by magnetism) near the center of the beam. Therefore, the concentrator 20
It is necessary that the installation position be a certain distance from the deflection yoke 30 so that it can work efficiently.

The concentrator 20 is effective in reducing the deterioration of the power characteristics due to changes in the geomagnetic component in one direction perpendicular to the tube axis. If necessary for the geomagnetic component in the other direction perpendicular to the tube axis, another concentrator 200 oriented perpendicular to the first direction may be installed as shown in FIG. . At this time, in order to efficiently concentrate the magnetic flux collected by the concentrators 20 and 200 in the network part 4, the concentrators 20 and 200 are connected to each other in the network part 4.
It is best to position it offset in the axial direction.

It goes without saying that the concentrators 20, 200 may be used in conjunction with conventional magnetic shielding devices.

〔Effect of the invention〕

As described above, according to the present invention, by arranging a high magnetic permeability concentrator at the neck part at a location slightly away from the deflection yoke, the earth's magnetic field, etc. The magnetic flux of the components can be collected and concentrated within the network. In particular, the influence of unnecessary magnetic flux components perpendicular to the tube axis on the integrity characteristics is much greater on the front side of the deflection yoke than on the rear side, and the influence is opposite before and after the deflection yoke. In view of this, by increasing the concentration of unnecessary magnetic flux components on the rear side, the effects on the power characteristics before and after the deflection yoke can be mutually canceled out, thereby effectively reducing the negative effects on the power characteristics due to unnecessary magnetic flux such as the earth's magnetism. can be reduced to Moreover, without using any coils or current sources,
The simple and inexpensive configuration of simply installing a high permeability concentrator has the effect of significantly improving the pieurity characteristics.

[Brief explanation of the drawing]

FIG. 1 is a schematic top view showing an example of a color cathode ray tube device according to the present invention, FIG. 2 is a front view of a concentrator in the same device, and FIG. 4 is an explanatory diagram showing how the concentrator according to the present invention collects magnetic flux of the earth's magnetic field; FIGS. 5 and 6 are diagrams showing modified examples of the concentrator; FIG. FIG. 7 is a perspective view of essential parts showing another embodiment of the present invention, and FIG. 8 is a partially cutaway side view showing the operation of a conventional color cathode ray tube device. 1...Color cathode ray tube, 3...Funnel,
4...Network section, 20,200...Concentrator, 30...Deflection yoke. Note that the same reference numerals in the figures indicate the same or corresponding parts.

Claims (1)

[Claims] 1 A deflection yoke attached near the connection between the funnel and the neck in a color CRT; A color cathode ray tube device comprising, in addition to a deflection yoke, a magnetic body with high magnetic permeability that collects unnecessary magnetism such as earth's magnetism from a source and concentrates it in the network portion.