JP3109744B2 - Cathode ray tube device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION [Object of the Invention]

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cathode ray tube device for reducing a leakage magnetic field leaking outside a deflection yoke.

[0002]

2. Description of the Related Art Recently, attention has been paid to the influence of a leaked magnetic field leaking from various devices on the human body, mainly in Northern Europe, and there is a movement worldwide to regulate the leaked magnetic field. The nominal value of this leakage magnetic field is the Swedish MPR
(SSI) standards are provided. With the revision of this standard, it is necessary to take measures against leakage magnetic fields of 5Hz to 400kHz. Regarding the cathode ray tube device, of the magnetic field generated from the deflection yoke for deflecting and scanning the electron beam,
Reduction of the leakage magnetic field leaking to the outside other than the magnetic field contributing to the deflection of the electron beam is being promoted. With the new standard, it is necessary to reduce the leakage magnetic field generated from the horizontal deflection coil and the vertical deflection coil. As a countermeasure against the leakage magnetic field, there are a compensation coil method for generating a compensation magnetic field in the opposite direction to the leakage magnetic field in order to cancel the leakage magnetic field, and a method for covering the entire cathode ray tube device with a magnetic shield member.

In Japanese Patent Application Laid-Open No. 62-64024, as shown in FIG. 6, an auxiliary coil 3 having substantially the same shape as the horizontal deflection coil 1 is arranged outside a saddle-shaped horizontal deflection coil 1 with a core 2 interposed therebetween. A part of the current flowing through the horizontal deflection coil 1 flows in the opposite phase so that the magnetic flux indicated by the arrow 5 opposite to the direction of the main magnetic flux of the horizontal deflection coil indicated by the arrow 4 passes therethrough. Leakage magnetic field is reduced. However, in the method using the auxiliary coil 3, it is difficult to reduce the leakage magnetic field at a predetermined position to a predetermined level.
With the revision of the PR standard, it is necessary to newly install an auxiliary coil to compensate not only the leakage magnetic flux of the horizontal deflection magnetic field but also the leakage magnetic flux of the vertical deflection magnetic field, which leads to a problem of space for mounting the auxiliary coil and an increase in power consumption. There's a problem.

In the case of the shield system, the display unit on the front of the cathode ray tube cannot be shielded, and the effect on the leakage magnetic field on the front of the cathode ray tube is low.

Further, as another inexpensive and compact means different from the above-mentioned method, Japanese Patent Application Laid-Open No. 64-45046 discloses a method in which a magnetically permeable ring is arranged as a magnetic shunt means between a screen and a deflection yoke. Means for reducing the leakage magnetic field are shown. As shown in FIG. 7, the cathode ray tube device disclosed in Japanese Patent Application Laid-Open No. 64-45046 has a relatively high magnetic permeability adjacent to a front transition portion 6 of a saddle-shaped horizontal deflection coil 1 of a deflection yoke. , A high resistivity linear ferrite ring 7 is installed. The linear ferrite ring 7 acts as a magnetic shunt means to reduce a leakage magnetic field.

However, in the structure disclosed in Japanese Patent Application Laid-Open No. 64-45046, the size of the ring is limited because the ring is installed on the front surface of the deflection yoke. In addition, work for adjusting the position by attaching a deflection yoke to the cathode ray tube (hereinafter referred to as IT
In the case of C operation), a wedge is inserted between the cathode ray tube and the deflection yoke and fixed. Therefore, the wedge cannot be inserted in the above-described structure, and the ICT operation becomes difficult. Furthermore, in order to minimize the leakage magnetic field, the inner diameter of the ring needs to be as small as possible and close to the neck diameter of the cathode ray tube. Even with such a shape, there is a problem in ITC work. In addition, the distance between the front end of the deflection yoke and the cathode ray tube is usually 3 m.
m or less, but a thickness of at least several mm is required to minimize the leakage magnetic field. To install this, a YPB (Yo
It is necessary to change design values such as (rk Pull Back), and the display characteristics of the cathode ray tube device are impaired, and the necessity of a drastic design change of the cathode ray tube device arises.

[0007]

Conventionally, measures to reduce the leakage magnetic field from the cathode ray tube device have been mainly performed on the horizontal deflection magnetic field.
(Extremely Low Frequency) leakage magnetic field of 5Hz to 2kHz is also attracting attention.

As described above, in the method using a compensation coil as a measure against the leakage magnetic field, there is a problem that it is difficult to mount the compensation coil if the leakage magnetic field due to the vertical deflection magnetic field is to be reduced. Further, it has a structure in which a magnetically permeable ring is arranged between the front end of the deflection yoke and the cathode ray tube.
C operation becomes difficult, and furthermore, there is a problem that the display characteristics of the cathode ray tube device are largely changed, and the design of the cathode ray tube device needs to be changed.

SUMMARY OF THE INVENTION In view of the above problems, an object of the present invention is to provide a cathode ray tube device which reduces a leakage magnetic field by simpler means.

[Structure of the Invention]

[0011]

In order to solve the above-mentioned problems, the present invention provides a cathode ray tube for displaying an image on a phosphor screen by scanning an electron beam emitted from an electron gun, and a cathode ray tube mounted on the cathode ray tube. A horizontal deflection coil for generating a horizontal deflection magnetic field for horizontally deflecting the electron beam emitted from the electron gun, and a vertical deflection coil for generating a vertical deflection magnetic field for vertically deflecting the electron beam emitted from the electron gun in the vertical direction A deflection yoke in which the horizontal deflection coil includes a pair of upper and lower saddle-shaped horizontal deflection coils, and a closed yoke disposed outside the deflection yoke and on at least one side with respect to a plane of symmetry of the saddle-shaped horizontal deflection coil. A ring-shaped or rectangular magnetic body, and the front of the magnetic body on the screen side and the rear side of the electron gun on the front side of the deflection yoke. And it is located so as to cover the part and the rear flange portion.

[0012]

The front and rear flanges of a closed yoke-shaped or rectangular magnetic body on the screen side and the electron gun side are provided on at least one side of the plane of symmetry of the saddle-shaped horizontal deflection coil of the deflection yoke. By arranging so as to cover the portion, the magnetic material is magnetized by the leakage magnetic flux, and a compensation magnetic field in a direction opposite to the leakage magnetic field is generated. Basically, by arranging the magnetic material outside the front and rear flanges of the vertical deflection coil, the magnetic material is magnetized by the leakage magnetic field,
A compensating magnetic field that is opposite to the leakage magnetic field is generated. However, simply arranging the magnetic material outside the front and rear flanges of the vertical deflection coil has a strong compensation magnetic field.Therefore, connecting the front and back of the magnetic material to form a closed ring or rectangular shape increases the volume of the magnetic material, thereby compensating for it. Increase the magnetic field.

[0013]

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

FIG. 1 is a vertical sectional view of a cathode ray tube apparatus according to an embodiment of the present invention. The cathode ray tube in this apparatus has an envelope composed of a substantially rectangular panel 20 and a funnel-shaped funnel 21 joined together, and the inside of the panel 20 has three colors that emit red, green, and blue light. A phosphor screen 22 made of a phosphor layer is provided, and a shadow mask 23 having a large number of electron beam transmitting holes is mounted in close proximity to the phosphor screen 22. Also, funnel 21
An electron gun 25 that emits three electron beams is disposed in a neck 24 of the laser beam. In addition, the funnel 21 cone and neck 24
A deflection yoke 26 that generates a magnetic field that deflects the electron beam emitted from the electron gun 25 in the horizontal and vertical directions is mounted on the outer side of the boundary. A ring-shaped magnetic pair 27 is arranged above and below the deflection yoke.

FIG. 2 shows the arrangement of the ring-shaped magnetic body 27 as viewed from above. As shown in FIG. 2, the deflection yoke 26 is arranged inside the separator 28 symmetrically with respect to a horizontal axis (X axis), and generates a horizontal deflection magnetic field for horizontally deflecting the three electron beams. A deflection coil 29 and a saddle-shaped vertical deflection coil 30 are disposed outside the separator 28 symmetrically with respect to a vertical axis (Y axis) and generate a vertical deflection magnetic field for deflecting the three electron beams in the vertical direction.
The pair of horizontal deflection coils 29 have crossover portions 31a and 31b on the fluorescent screen side and the electron gun side on the opposite side, respectively.
Further, the pair of vertical deflection coils 30 also have bridging portions 32a and 32b on the fluorescent screen side and the electron gun side on the opposite side, respectively, and constitute a front french portion A and a rear flange portion B. Further, on the outer periphery of the vertical deflection coil 30, a conical cylindrical core 33 is arranged so as to surround the horizontal and vertical coils, avoiding the crossovers. further,
A pair of high-permeability, high-resistivity ring-shaped magnetic bodies 27 are arranged above and below the deflection yoke 26.
Are located near the front flange portion A and near the rear flange portion B of the deflection yoke 26, respectively.

By installing this ring-shaped magnetic body, an ELF (Extremely Low Frequent
ncy) of 5 Hz to 2 kHz can be reduced. For example, as a magnetic material, outer diameter 110 mm, inner diameter 107 mm,
By installing a ring-shaped ferrite core having a height of 8 mm, the leakage magnetic field of the ELF can be reduced from 250 nT to 150 nT or less. Further, by making the shape of the magnetic material an appropriate shape, the leakage magnetic field can be reduced to 100 nT or less.

Next, the operation of the ring-shaped magnetic body will be described. FIG. 3 shows the leakage magnetic field of the saddle type vertical deflection coil and the compensating action of the magnetic material. By arranging the ring-shaped magnetic body so as to cover the front and rear flanges of the deflection yoke, the front and rear of the ring-shaped magnetic body are located near the front and rear flanges of the deflection yoke, respectively. As a result, the magnetic material is magnetized to generate a compensation magnetic field in the direction opposite to the leakage magnetic field as shown by the broken line.

As described above, in order to generate a compensation magnetic field due to the magnetization of the magnetic material, it is necessary to arrange the magnetic material outside the front-rear crossover portion of the vertical coil. By adopting a ring shape, the volume of the magnetic body is increased, and the effect is improved.

When a coma correction coil is mounted in the vicinity of the rear flange portion, a leakage magnetic field is also generated by the coil, and the leakage magnetic field is reduced by installing the ring-shaped magnetic material so as to cover the coil. can do.

Further, in the above-described embodiment, the case where the ring-shaped magnetic body is arranged above and below the deflection yoke has been described. It is more effective to adopt the configuration of

Further, the leakage magnetic field can be minimized when the ring is installed at a position covering the front flange portion and the rear flange portion of the deflection yoke.

The ring according to the present invention is not limited to a ring shape, but may be a rectangular magnetic body 40 as shown in FIG.

Further, since the above-mentioned ring-shaped or rectangular magnetic substance has only an effect of reducing the leakage magnetic field of the ELF due to vertical deflection, when the magnetic field also serves to reduce the leakage magnetic field due to horizontal deflection, as shown in FIG. Alternatively, the structure may be such that the coil 41 is wound around the front part of the rectangular magnetic body 40 and also serves as a part of the compensation coil. With such a configuration, the compensation coil 41 is located near the crossing portion of the saddle-shaped horizontal deflection coil, which is effective in reducing the leakage magnetic flux of the horizontal deflection magnetic field. Further, by adjusting the angle of the rectangular magnetic body, it is possible to adjust the compensating action of the leakage magnetic flux due to the horizontal deflection magnetic field.

In the above-described embodiment, a ferrite having a high magnetic permeability and a high resistivity is used as the magnetic material. However, the case where only the leakage magnetic field of the ELF is reduced is not limited to the above-described embodiment. For, it is also possible to use lower materials.

Further, in the above-described embodiment, the saddle type coil is used as the vertical deflection coil. However, a toroidal type coil may be used.

By implementing the above-described means for reducing the leakage magnetic field, the ITC operation is facilitated, the influence on the cathode ray tube device is small, and problems such as a change in the design of the cathode ray tube device can be avoided.

[0027]

As described above, according to the present invention, the leakage magnetic field generated from the cathode ray tube device can be reduced by an easy method. Further, it does not hinder the ITC work, and can save the trouble of changing the design of the cathode ray tube device.

[Brief description of the drawings]

FIG. 1 is a vertical sectional view of a cathode ray tube device according to an embodiment of the present invention.

FIG. 2 is a diagram showing an arrangement state of ring-shaped magnetic bodies arranged above and below a deflection yoke in FIG. 1 as viewed from above.

FIG. 3 is a diagram illustrating the operation of the ring-shaped magnetic body according to the present invention.

FIG. 4 is a view showing a closed rectangular magnetic body according to another embodiment of the present invention.

FIG. 5 is a view showing another example of the present invention, which also has a compensation coil for a horizontal deflection leakage magnetic field.

FIG. 6 is a diagram showing an auxiliary coil for reducing a leakage magnetic field in a conventional cathode ray tube device.

FIG. 7 is a view showing a magnetically permeable ring for reducing a leakage magnetic field in a conventional cathode ray tube device.

[Explanation of symbols]

 22 ... phosphor screen 25 ... electron gun 26 ... deflection yoke 27 ... ring-shaped magnetic material 29 ... saddle-shaped horizontal deflection coil 30 ... saddle-shaped vertical deflection coil A ... front Flange B: Rear flange 40: Rectangular magnetic body

Claims (1)

(57) [Claims] 1. A cathode ray tube for displaying an image on a phosphor screen by scanning an electron beam emitted from an electron gun, and an electron beam mounted on the cathode ray tube and deflecting the electron beam emitted from the electron gun in a horizontal direction. A horizontal deflection coil for generating a horizontal deflection magnetic field, and a vertical deflection coil for generating a vertical deflection magnetic field for vertically deflecting the electron beam emitted from the electron gun, wherein the horizontal deflection coil is a pair of upper and lower saddle-shaped horizontal coils. A deflecting yoke comprising a deflecting coil; and a closed ring-shaped or rectangular magnetic body disposed outside the deflecting yoke and on at least one side with respect to the symmetry plane of the saddle-shaped horizontal deflection coil. The front side of the body on the screen side and the rear side of the electron gun side are located so as to cover the front flange portion and the rear flange portion of the deflection yoke. A cathode ray tube device characterized by the above-mentioned.