JP2002176654A - Degaussing method for color cathode-ray tube, and the color cathode-ray tube adopting the degaussing method - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a degaussing method for a color cathode-ray tube with which degaussing effect is improved to reduce mislandings of electron beams, the degaussing time is decreased with a simplified operating circuit, and the mounting work of a degaussing coil is facilitated. SOLUTION: The degaussing coil 1 consists of a front-face ring coil 1a, a 1st lateral face ring coil 1b and a 2nd lateral face ring coil 1c, that are branched from the front-face ring coil 1a. The front-face ring coil 1a is placed around a panel 8 of a face of a mask 5, the 1st lateral face ring coil 1b is placed at an upper part of the color cathode-ray tube and the 2nd lateral face ring coil 1c is placed at a lower part of the color cathode-ray tube. The 1st lateral face ring coil 1b intersects a font-face ring coil 2, and the 2nd lateral face ring coil 1c is folded back and branched from the front face ring coil 1a so as not to intersect the font face ring coil 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for degaussing a color cathode ray tube used for a television or a personal computer monitor, and a color cathode ray tube employing the degaussing method.

[0002]

2. Description of the Related Art FIG. 4 shows a basic structure of a general color cathode ray tube used for a television or a personal computer monitor. The color cathode ray tube deflects the electron beam 3 emitted from the electron gun 2 in the vertical and horizontal directions by a deflection yoke 4 and scans the entire screen to reproduce an image. At this time, when an external magnetic field such as terrestrial magnetism acts on the color cathode ray tube, the mask 5, the frame 6, and the internal magnetic shield 7 made of a magnetic material in the tube are magnetized. Due to the magnetic field generated by the magnetization, the electron beam 3 has a Lorentz force f = q (v × B) (f: Lorentz force, q: charge amount of electron, v: velocity vector of electron, B: magnetic flux density ). The distortion of the electron beam 3 causes a mislanding where the electron beam 3 does not reach a predetermined position with respect to the phosphor 9 on the panel 8. As a countermeasure against the mislanding, a degaussing coil is usually arranged around the color cathode ray tube to perform degaussing for removing the magnetization of the magnetic member.

As a degaussing method using a degaussing coil, a method shown in FIG. 5 is generally used.

[0004] The degaussing coil 101 comprises a pair of ring-shaped coils. These ring-shaped coils are placed above and below the color cathode ray tube from the panel 8 on the mask 5 side so that the degaussing magnetic field generated when an alternating degaussing current flows is in the same direction between the two ring-shaped coils. It is arranged over 10 parts. As described above, when the ring-shaped coil is disposed substantially above and below the color cathode ray tube, the magnetic field (demagnetizing magnetic field) generated mainly in the vertical direction (Y-axis direction in the figure) causes
Demagnetization is performed.

Another demagnetizing method is disclosed in Japanese Patent Laid-Open No.
Japanese Patent No. 84435 discloses a degaussing operation in which a current for generating a degaussing magnetic field is applied to a first ring-shaped coil 102 disposed in front of a color cathode ray tube, as shown in FIG. Alternatively, a current that generates a demagnetizing magnetic field in the same direction is applied to a pair of second ring-shaped coils 103 arranged on the left and right (here, an example arranged vertically) to perform a demagnetizing operation. A method is disclosed in which the first ring-shaped coil 102 and the second ring-shaped coil 103 are operated in different time zones to demagnetize.

[0006]

However, in the general degaussing method shown in FIG. 5, the degaussing magnetic field in the tube axis direction (Z-axis direction in the figure) is weak, and the degaussing ability is insufficient. In particular, when geomagnetism is applied in the pipe axis direction (Z axis direction),
Magnetic fields act from the opening on the deflection yoke 4 side and the opening on the mask 5 side of the internal magnetic shield 7, and the vicinity of the mask 5 is not sufficiently demagnetized. As a result, the electron beam 3 was distorted and mislanding occurred.

On the other hand, Japanese Patent Laid-Open No. 6-284 shown in FIG.
In the case of the degaussing method disclosed in Japanese Patent Publication No. 435/435, a degaussing magnetic field in the tube axis direction (Z-axis direction) can be applied to the color cathode ray tube, but two degaussing coils (the first ring-shaped coil 1).
02 and the second ring-shaped coil 103) operate in different time zones, resulting in a longer demagnetization time, and a problem of operating the two demagnetizing coils separately to complicate the operation circuit. I was Further, since the degaussing coil is divided into two, there is a problem in the mounting operation that the number of steps for mounting the color cathode ray tube increases.

The present invention has been made to solve these problems, and improves the demagnetizing effect over the entire color cathode ray tube to reduce mislanding caused by distortion of an electron beam due to a residual magnetic field. An object of the present invention is to provide a degaussing method capable of shortening the degaussing time and simplifying the operation circuit and improving the workability of attaching the degaussing coil, and a color cathode ray tube using the degaussing method.

[0009]

In order to achieve the above object, a method of degaussing a color cathode ray tube according to the present invention comprises: a degaussing method for a color cathode ray tube using a degaussing coil; A side coil, wherein the front coil is disposed in a ring shape on a front surface of the color cathode ray tube, and the side coil is branched from the front coil. A pair of first side coils and second side coils arranged in a ring on at least one of the upper, lower, left and right sides, the first side coils intersect and branch from the front coils, The two side coils are arranged so as not to cross from the front coil and are arranged so as not to intersect. By passing a current through such a degaussing coil, the magnetic members of the color cathode ray tube are magnetized. It is characterized in that except Ri.

According to this method, it is possible to degauss mainly the vicinity of the front surface of the color cathode ray tube by the front coil and demagnetize mainly the inside of the color cathode ray tube by the first side coil and the second side coil. Furthermore, by arranging as described above, the demagnetizing magnetic fields generated from the first side coil and the second side coil are increased in the same direction, so that the inside of the color cathode ray tube can be more reliably demagnetized.

As a result, the degaussing effect is improved over the entire color cathode ray tube, the mislanding caused by the distortion of the electron beam due to the residual magnetic field is reduced, the degaussing time is shortened, and the operation circuit is simplified.
The workability of mounting the degaussing coil can be improved.

[0012] In this specification, the phrase "the degaussing coil has a loop shape" means that the front coil and the side coils constituting the degaussing coil are continuous.

Further, the color cathode ray tube of the present invention is a color cathode ray tube provided with a degaussing coil for removing magnetization of a magnetic member of the color cathode ray tube, wherein the degaussing coil is a loop composed of a front coil and a side coil. Wherein the front coil is disposed in a ring shape on the front surface of the color cathode ray tube, and the side coil is at least one of the upper, lower, left and right sides of the color cathode ray tube branched from the front coil. A first side coil and a second side coil arranged in a ring shape, the first side coil intersects and branches from the front coil, and the second side coil is connected to the front coil. It is characterized by being arranged in a branched manner without intersecting from.

With this configuration, it is possible to provide a color cathode ray tube capable of realizing the function and effect of the above-described degaussing method of the color cathode ray tube of the present invention.

[0015]

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

FIG. 1 shows a structure of a color cathode ray tube using a degaussing method according to an embodiment of the present invention.
The basic structure of the color cathode ray tube and the principle of image reproduction in the present embodiment are the same as those of the general color cathode ray tube shown in FIG. Therefore, also in the color cathode ray tube of the present embodiment, the mask 5 made of the magnetic material in the tube,
The electron beam 3 is distorted by Lorentz force due to the magnetic field generated by the magnetization of the frame 6 and the internal magnetic shield 7, causing a landing deviation.

The misalignment of the landing of the electron beam 3 (mislanding) is caused by the horizontal direction of the electron beam 3 (X in the figure).
Generated by Lorentz force f _x receiving the axial direction). The Lorentz force f _x is the magnetic flux in the vertical direction (Y-axis direction) and the tube axis direction (Z axis direction) exerted on the electron beams _{3, f x = q (B} z v y -B y v z) (f : Lorentz force,
q: charge amount of electrons, v: velocity vector of electrons, B: magnetic flux density). Therefore, the color cathode ray tube according to the present embodiment is provided with a degaussing coil 1 which is a feature of the present invention as a configuration for solving the problem of mislanding.

The degaussing coil 1 includes a front ring coil (front coil) 1a, a first side ring coil (first side coil) 1b branched from the front ring coil 1a, and a second side ring coil (second coil). 1c), and each of the coils 1a, 1b, 1c is formed in a continuous loop. The front ring coil 1a is arranged in a substantially ring shape around the panel 8 on the mask 5 side of the color cathode ray tube. The first side ring coil 1b and the second side ring coil 1c are arranged in a ring shape from the mask 5 to the funnel 10 above and below the color cathode ray tube. The first side ring coil 1b crosses and branches from the front ring coil 1a. On the other hand, the second side ring coil 1c is branched in a folded state so as not to cross from the front ring coil 1a.

The degaussing coil 1 is connected to a power supply section 11 so that when an alternating degaussing current flows, it flows in the direction of the arrow in the figure. The degaussing coil 1 is mainly degaussed in the vicinity of the mask 5 by the front ring coil 1a.
b and the second side ring coil 1c mainly degauss the inside of the internal magnetic shield 7. Here, the directions of the currents of the first side ring coil 1b and the second side ring coil 1c are the same on the mask 5 side and the funnel 10
It is the same direction on the side. For this reason, the demagnetizing magnetic fields in the vertical direction generated from the first side ring coil 1b and the second side ring coil 1c are in the same direction and are increased. Due to the increased vertical demagnetizing magnetic field, mainly the internal magnetic shield 7
Inside is demagnetized.

FIG. 2 schematically shows each axis of the color cathode ray tube viewed from the panel 8 side (the front side of the mask 5). Fig. 3 shows the horizontal magnetic field (X-axis direction) and the tube axis magnetic field (Z-axis direction).
5 shows a comparison result between the beam shift amount by the degaussing method of this embodiment and the beam shift amount by the conventional degaussing method shown in FIG.

As shown in FIG. 3, when the degaussing method of the present embodiment is used, the beam shift amount with respect to the tube axis magnetic field (Z-axis direction) is reduced as compared with the conventional degaussing method. . This is because, in the degaussing method of the present embodiment, the masked 5 vicinity demagnetization decreases the magnetic flux density B _y and B _z is the front ring coil 1a, the Lorentz force f _x of the electron beam 3 receives the residual magnetic field is reduced It is.

As described above, by using the degaussing method for the color cathode ray tube in the present embodiment, the degaussing effect over the entire color cathode ray tube can be improved, and the mislanding of the electron beam 3 due to the residual magnetic field can be suppressed. .
Further, the degaussing method for the color cathode ray tube according to the present embodiment is as follows.
Since the degaussing magnetic field is generated by the two degaussing coils 1, the degaussing time is not lengthened, no complicated operation circuit is required, and no complicated work is required for mounting the degaussing coil.

In this embodiment, the case where the first side ring coil 1b and the second side ring coil 1c are arranged above and below the color cathode ray tube has been described. , Mask 5
A similar effect can be obtained by demagnetizing the vicinity. Further, the same applies to a case where the first side ring coil 1b and the second side ring coil 1c are arranged on both the upper and lower sides and the left and right sides of the color cathode ray tube.

[0024]

As described above, according to the method for degaussing a color cathode ray tube of the present invention and the color cathode ray tube employing the degaussing method, the degaussing effect is improved over the entire color cathode ray tube, and the electron by the residual magnetic field is improved. The effects of reducing mislanding caused by beam distortion, shortening the degaussing time, simplifying the operation circuit, and improving the workability of attaching the degaussing coil can be achieved.

[Brief description of the drawings]

FIG. 1 is a perspective view schematically showing the structure of a color cathode ray tube using a degaussing method according to an embodiment of the present invention.

FIG. 2 is a schematic diagram showing each axis of the color cathode ray tube as viewed from a panel side (mask front side).

FIG. 3 is a comparison diagram of a beam shift amount when the degaussing method of the present embodiment is used and a beam shift amount when a conventional degaussing method is used.

FIG. 4 is a sectional view schematically showing the structure of a general color cathode ray tube.

FIG. 5 is a perspective view schematically showing the structure of a color cathode ray tube using a conventional degaussing method.

FIG. 6 is a perspective view schematically showing the structure of a color cathode ray tube using another conventional degaussing method.

[Explanation of symbols]

 Reference Signs List 1 Demagnetizing coil 1a Front ring coil (front coil) 1b First side ring coil (first side coil) 1c Second side ring coil (second side coil)

 ──────────────────────────────────────────────────の Continued on the front page (72) Inventor Shinichiro Hatta 1006 Kadoma Kadoma, Osaka Prefecture Inside Matsushita Electric Industrial Co., Ltd. (72) Inventor Takayuki Yonezawa 1006 Kazuma Kadoma, Kadoma City, Osaka Prefecture Matsushita Electric Industrial Co., Ltd. F term (reference) 5C060 CM04 CN04

Claims (2)

[Claims] 1. A degaussing method for a color cathode ray tube using a degaussing coil, wherein the degaussing coil is a loop-shaped coil including a front coil and a side coil, wherein the front coil is the color cathode ray tube. A set of first side coils that are arranged in a ring on at least one of the upper, lower, left, and right sides of the color cathode ray tube, the side coils being branched from the front coil; A second side coil, wherein the first side coil crosses and branches from the front coil, and a second side coil branches without crossing from the front coil, and is disposed. Demagnetizing the color cathode ray tube by removing the magnetization of the magnetic member of the color cathode ray tube by applying a current to the color cathode ray tube. 2. A color cathode ray tube including a degaussing coil for removing magnetization of a magnetic member of the color cathode ray tube, wherein the degaussing coil is a loop-shaped coil including a front coil and a side coil. The front coil is arranged in a ring shape on the front surface of the color cathode ray tube. The side coil is branched from the front coil and arranged in a ring shape on at least one of the upper, lower, left and right sides of the color cathode ray tube. A first side coil and a second side coil, wherein the first side coil crosses and branches from the front coil, and the second side coil branches without crossing from the front coil. A color cathode ray tube characterized by being arranged.