KR19990012682A - Cathode ray tube with geomagnetic shielding means - Google Patents

Abstract

The present invention discloses a cathode-ray tube provided with a geomagnetic shielding means. The cathode ray tube according to the present invention is provided with a permalloy inside the holder between the electron gun and the deflection yoke as a means having a geomagnetic shielding function.

Therefore, it is possible to minimize the misconvergence by minimizing the change of the horizontal magnetic component of the image display apparatus using the cathode ray tube, for example, the change of the CPM due to the change of the position of the screen portion or the change of the horizontal frequency. To improve the picture quality. This makes it possible to provide better image information to the end user who uses the image display apparatus.

Description

Cathode ray tube with geomagnetic shielding means

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cathode-ray tube having a CPM (Convergence Purity Magnet) having a magnetic shielding function. In particular, the present invention relates to a means for preventing a decrease in convergence caused by a change in a horizontal magnetic field. It relates to a CPM having a.

1 shows a cathode ray tube that is currently widely used. Referring to FIG. 1, the cathode ray tube forms an image on the panel 6 using hot electrons generated by the electron gun 1. Specifically, the electron beam generated by the electron gun 1 is focused and accelerated by a plurality of electrodes and is deflected to a predetermined position on the panel by the deflection yoke 3. The electron beam is color screened through a shadow mask 5 before reaching the panel 6. Inside the funnel 4 of the cathode ray tube, an inner shielder 7 is provided to minimize the influence of the electron beam by the geomagnetic field.

In a television set, a computer monitor, or other image display apparatus using a cathode ray tube having the above-described configuration, the image quality is determined by the deflection yoke 3 and the CPM 2. The image display apparatus is placed in a different place or direction depending on the user. Accordingly, a change in the direction or the horizontal frequency of the screen portion of the image display device is generated, and the change may cause a change in the horizontal magnetic field component of the electron gun in the cathode ray tube. As a result, the convergence of the electron beam reaching the panel surface changes. That is, in the cathode ray tube, the electron beam is emitted from the electron gun and passes through the electron lens part of the electron gun and the magnetic lens part of the CPM, so that the focus of the electron beam is precisely formed on the panel surface. As it affects the magnetic field component of and changes the angle of incidence of the electron beam incident on the CPM, as a result, the electron beam may not be landed correctly or abnormally formed on the panel. Therefore, the color purity may deteriorate and image quality may be faded or modulated. .

Here, the form according to the prior art of the CPM to determine the focus of the electron beam which is widely used now. Referring to FIG. 2, the CPM has a function of concentrating an electron beam incident from an electron gun, and is typically provided with two-pole, four-pole, and six-pole magnets 50, 60, and 70. Such a CPM is provided outside of a normal body.

Typically, there is a circular holder 30 that holds the body of the electron gun in addition to the CPM, and the holder 30 is wrapped by the band 20 so that it can be properly tightened by the bolt 40. In addition, the locker 10 is provided in the ordinary body so as to hold a plurality of magnets constituting the CPM. The rocker 10 is provided with four rocker handles 45.

Some of the CPMs shown in FIG. 2 represent the handles of the dipole, quadrupole, and six pole (50, 60, 70) magnets constituting the CPM.

In this type of CPM, the 4-pole and 6-pole magnets 60, 70 move the blue or red beams of the passing electron beams in the opposite direction or rotate them in the same direction in the same direction, or The three electron beams are concentrated in the center of the panel by overlapping the green electron beams.

The incident angle of the electron beam incident on the CPM is determined by the horizontal and vertical magnetic fields of the electron gun. Therefore, if the horizontal magnetic field of the electron gun varies depending on the installation location or installation direction of the monitor according to the user, the incident angle incident on the CPM is changed, which leads to a poor convergence, resulting in a problem of deterioration in the quality of the cathode ray tube.

Accordingly, an object of the present invention is to provide a Cathode-Ray Tube provided with a magnetic field shielding means to solve the problems of the prior art described above so that a user can obtain better image information.

1 is a cross-sectional view of a cathode ray tube.

2 is a cross-sectional view of a structure including a holder and a CPM provided between an electron gun and a deflection yoke according to the prior art.

3 is a cross-sectional view of a structure including a holder and a CPM provided between the electron gun and the deflection yoke according to the embodiment of the present invention.

4 is an enlarged view of a portion A of FIG. 3.

5 is a cross-sectional view taken along the line BB ′ of FIG. 3.

FIG. 6 is a table for comparing the change in convergence in a cathode ray tube using a structure including a holder and a CPM provided between an electron gun and a deflection yoke according to embodiments of the present invention.

〈Code Description of Main Parts〉

10: locker

20: band

30a: holder

40: bolt

50, 60, and 70: 2, 4, and 6 pole magnets

80: means with magnetic shield

In order to achieve the above object, a cathode ray tube (Cathode-Ray Tube) having a geomagnetic shielding means according to the present invention is a cathode ray tube having a CPM and a holder in the ordinary body provided between the electron gun portion and the deflection yoke portion,

Means for suppressing the change of the horizontal magnetic field component of the CPM due to the geomagnetic field is provided inside the holder.

The means is provided between the ordinary body and the holder, characterized in that it is fitted in the groove having a predetermined depth inside the holder.

In addition, the means are formed to face each other from the inside of the holder and extends a predetermined length along the surface of the body in the direction of the deflection yoke.

The means is permalloy.

The present invention is provided with a geomagnetic shielding means inside the holder to minimize the influence of the geomagnetic field of the CPM can reduce the landing error of the electron beam can improve the image quality of the cathode ray tube.

Hereinafter, a cathode-ray tube provided with a magnetic shielding means according to an embodiment of the present invention will be described in detail with reference to the accompanying drawings. First, FIG. 3 is a cross-sectional view of a structure including a holder and a CPM provided between the electron gun and the deflection yoke according to the embodiment of the present invention.

Referring to FIG. 3, the CPMs 50, 60, and 70 are made of two-pole 50, four-pole 60, and six-pole 70 magnets as in the conventional CPM shown in FIG. 2. The same is true. The same applies to the rocker 10 for tightening the CMPs 50, 60, 70, the rocker handle 45, and the band 20 for holding the holder 30a. However, the holder 30a is different from the holder according to the prior art (30 in FIG. 2). Specifically, inside the holder 30a according to the embodiment of the present invention, the geomagnetic field shielding means 80 is the CPM 50, 60, 70, the holder 30a, the band 20, the locker 10, or the like. It is provided along the surface in parallel with the normal body (not shown) provided in this exterior. The means 80 is provided between the holder 30a and the normal body and fitted into a groove having a predetermined depth inside the holder 30a. In addition, the means 80 extends by a predetermined length in the direction of the deflection yoke along the surface of the body, rather than remaining only inside the holder 30a. The means 80 is a permalloy, an alloy material containing nickel (Ni) and iron (Fe) as main components. The means 80 are provided in two places inside the holder 30a, and are provided in parallel to face each other. The size of the means 80 may vary depending on the size of the cathode ray tube required. In the present invention, the size of the means 80 is enlarged in the portion A in which the means 80 are included in FIG. 4 is shown. Referring to Fig. 4, one example of the specification of the means 80 is thickness, height and length (length in the direction entering the ground) are 0.21 mm, 7 mm and 27 mm, respectively. The planar form of the means 80 is shown in FIG. 5. Referring to FIG. 5, it can be seen that the means 80 are inserted side by side parallel to each other in a groove of a constant depth inside the holder 30. In FIG. 5, reference numeral 20 denotes a holder 30 provided with the means 80. Reference numerals 50a, 60a and 70a denote two-pole, four-pole and six-pole magnets of CPM, respectively. Reference numeral 10a denotes a locker.

It is possible to minimize the change in the horizontal magnetic field due to the geomagnetic field in the CPM (50, 60, 70) by the means 80 in the holder 30.

6 is a table showing a change in the CPM according to the prior art and the embodiment of the present invention due to the change of the position of the screen portion of the cathode ray tube or the change of the horizontal magnetic component, specifically, according to the change of the position of the screen portion and the change of the horizontal frequency The change in the center and peripheral convergence is measured. Referring to FIG. 6, when the CPM according to the embodiment of the present invention is used, the convergence is improved in both the center and the periphery when the position change of the screen unit changes from east to west, east to south, and east to north. In particular, the improvement effect is large when it changes to north in the east. Specifically, the convergence (Cg) is improved by 0.11mm at the center of the screen. That is, the miss convergence is reduced by 0.11 mm compared with the prior art.

In addition, when the horizontal frequency changes from 64K at 82KHz, 48KHz at 82KHz and 31KHz at 82KHz, there is an improvement in convergence at the center and periphery, but especially when the change from 82KHz to 31KHz occurs. Specifically, when using the CPM according to the embodiment of the present invention, the convergence was improved by 0.07 mm at the center. That is, the miss convergence is reduced by that compared with the prior art.

As described above, the cathode ray tube having the geomagnetic shielding means according to the embodiment of the present invention is provided with a permalloy inside the holder as the geomagnetic shielding means.

Therefore, it is possible to minimize the miss convergence by suppressing the change of the horizontal magnetic component due to the geomagnetic field of the image display device using the cathode ray tube, for example, the change of the horizontal magnetic component of the CPM due to the change of the position of the screen or the change of the horizontal frequency. The focus of the electron beam can be accurately formed on the panel, thereby improving image quality. This makes it possible to provide better image information to the end user who uses the image display apparatus.

The present invention is not limited to the above embodiments, and it is apparent that many modifications can be made by those skilled in the art within the technical spirit of the present invention.

Claims (4)

In the cathode ray tube having a CPM and a holder in a normal body provided between the electron gun section and the deflection yoke section, A cathode-ray tube provided with a geomagnetic shielding means characterized in that a means for suppressing a change in the horizontal magnetic component of the CPM due to a geomagnetic field is provided inside the holder. The cathode ray tube provided with a geomagnetic shielding means according to claim 1, wherein said means is provided between said ordinary body and said holder and is fitted in a groove having a predetermined depth inside said holder. Tube). 3. The cathode according to claim 2, wherein the means is formed to face each other from the inside of the holder and extends by a predetermined length in the direction of the deflection yoke along the surface of the ordinary body. Cathode-Ray Tube. 4. Cathode-ray tube according to any one of the preceding claims, characterized in that the means is a permalloy.