JPS62290047A - Electron gun electrode structure for color cathode-ray tube - Google Patents

Abstract

PURPOSE:To obtain the excellent picture without convergence error by providing two magnetic field control elements comprising annular and tongue portions, which are opposedly arranged on the bottom of a shield magnetic pole disposed in an electron passing region which is subjected to the effect of the deflected magnetic field of an electron gun rear end portion in an electromagnetic deflection device. CONSTITUTION:A magnetic field control element 80 comprises an annular portion 81, made of high permeability magnetic material, perfectly surrounding external electron beam apertures 16R and 16 B located on the bottom of a shield magnetic pole 16 and a tongue portion 82 continously extending to the annular portion 81 on the central electron beam aperture 16G side. The annular 81 controls the horizontal and vertical deflection magnetic fields 5H and 5V on the external electron beam passage to be sided and the tongue portion 82 controls the vertical deflection magnetic field 5V to be forcused in the vicinity of the central electron beam aperture 16G. Therefore, the grasp area of the annular portion 81 in the magnetic field is made to be suitable so that the horizontal component of the scanning screens 34R and 34B formed by both electron beams is made to coincide with a scanning screen 34G and also coincide with the vertical width of the scanning screens 34R and 34B by adjusting the grasp area of the vertical field in the tongue portion 82.

Description

[Detailed Description of the Invention] & Detailed Description of the Invention The present invention is directed to a scanning screen on which a plurality of electron beams are formed on a phosphor screen without or with only a partial use of a dynamic) invergence correction device. This invention relates to a self-convergence type color cathode ray tube in-line type electron gun in which all points are concentrated at one point.

In order to facilitate understanding of the present invention, conventional examples will be explained in detail.

FIG. 1 is a longitudinal sectional view of a conventional color cathode ray tube using an in-line electron gun that does not require dynamic convergence correction. The three electron beams emitted from the in-line electron gun 1, which are aligned on a straight line and in the same plane, are deflected by an electromagnetic deflection device (hereinafter referred to as A phosphor is deflected horizontally and vertically by a deflection yoke (5), and is coated with a plurality of red, green, and blue-emitting phosphor elements on the inside of the glass envelope (1) at the front of the glass envelope (2). A scanning screen is formed on surface 3.

In this tube, adjacent to the phosphor screen 3, a color selection mechanism consisting of a perforated mask 4 is disposed, and each scanning electron beam is emitted by a main electron lens used in the cathode ray tube, as shown in FIG. This figure shows the configuration of a conventional in-line electron gun that adopts a focus configuration. A G1 electrode 12 and a G2 electrode 13 are arranged in sequence in the electron beam traveling direction, facing each other.
, G3 electrode 14. It is composed of a G4 electrode 15 and a shielding magnetic pole 16, and although each electrode except the shielding magnetic pole 16 is not shown, it is fused and fixed to an insulator support column via each electrode support part, and a predetermined electrode spacing is maintained. ing. G1 electrode 12, G
Each through hole 12 through which the electron beam of the second electrode 13 and the G3 electrode 14 passes, 12G, 12B; 13R.

13G, 13B; 14R,, 14Gl, 14BI and 1
4R1, 14Gm, and 14B are also arranged in a line with equal distances S, and the three cathodes 11R of the cathode structure 11
The distance S' between the holes in the parallel path electrode 15 for the electron beam emitted from 111G and IIB is somewhat larger than S in the above-mentioned case, and the gap between each pair of holes between the G3 electrode 14 and the G4 electrode 15 is An asymmetrical electric field is formed in the two outer parts of the main electron lens, and when there is no deflection magnetic field generated by the deflection yoke 5, the outer two electron beams are directed to the center 31 of the phosphor screen 3 as a central electron beam. It becomes electrostatically concentrated.

A static convergence device 6 is disposed on the deflection yoke 5 side of the electron gun assembly 1 sealed in the glass neck following the funnel-shaped part of the glass envelope 2, and a phosphor screen is disposed on the side of the deflection yoke 5 of the electron gun assembly 1. It is possible to correct small errors in the center. Furthermore, adjacent to the silent convergence device 6, a color line conversion device 7 is arranged to correct the three electron beams so that they correctly stimulate the phosphor elements of the corresponding colors.

However, in order to reproduce a color image without color shift over the entire surface of the phosphor screen, it is necessary to concentrate the three electron beams at all points on the scanning screen. By selecting an appropriately small value for the mutual spacing S of the three deflected electron beams, which causes strong barrel distortion in the vertical deflection magnetic field, the two outer electron beams can be formed as shown in Fig. 5. The scanning screens 33R and 33B created can be made to almost match the scanning screen 33G created by the central electron beam. This concentration error in the scanning screen is tolerably small for a cathode ray tube with a small screen of 15 inches or less with a deflection angle of 90 degrees, but can be ignored for a cathode ray tube with a larger screen. The result is an unpleasant color misalignment.

This is because the electron beams on both sides of the inline electron beam are eccentric with respect to the center of the deflection yoke, so the size of the scanning screen to be scanned differs between the center electron beam and the electron beam on both sides. This is caused by coma distortion.

In order to correct this coma distortion, a shielding magnetic pole 16 is arranged and fixed so that the deflection magnetic field is partially at the same potential in the electron beam passing region where the rear end leakage magnetic field 51 (FIG. 1) of the deflection yoke 5 reaches. In the bottom surface, two outer through holes 16B of the through holes 16R, 16G 116B whose centers are 10 and 10G and IGBK aligned are surrounded by an annular magnetic shielding element 17 made of a magnetic material with high magnetic permeability, as shown in FIG. As shown in , the horizontal and vertical leakage magnetic fields 5H and 5V are partially bypassed to reduce the horizontal and vertical amplitudes of the scanning screen formed on the phosphor screen by the two outer electron beams. In this case, by appropriately selecting the size of the annular magnetic shielding element 17, that is, the capture area for the magnetic flux, the scanning screen 33 33B, which is drawn by both outer beams at the top and bottom of the screen, can be controlled by the center beam, as shown in FIG. Scanning screen 33G
It is possible to match. However, in the horizontal direction of the screen, the scanning screens 33R and 33B drawn by both outer beams have larger amplitudes than the scanning screen 33G drawn by the center beam, and this residual coma distortion is compensated for by scanning the inner scanning screens 33R and 33B on the outer scanning screens 33R and 33B. In order to match the screens 33G, magnetic enhancement elements 18 consisting of a pair of small disks made of high magnetic permeability material are placed on both sides of the central electron beam aperture 16G as shown in FIG.
Install it on the same plane as 7.

As shown in FIG. 4, this element expands the horizontal amplitude of the scanning screen 33G created by the central electron beam by concentrating the horizontal leakage magnetic field 5H in the vicinity of the central electron beam aperture, and increases the horizontal amplitude of the horizontal leakage magnetic field 5H near the central electron beam through-hole, and increases the horizontal amplitude of the scanning screen 33G created by the central electron beam, and the scanning screen 33R, 33B of both outer electron beams. Central electron beam scanning screen 33G
It is possible to match both the left and right sides of the screen in the horizontal direction, and thus a scanning screen without color shift can be obtained over the entire screen.

As mentioned above, in the conventional self-convergence type color cathode ray tube in-line electron gun, correction for the mismatch in the size of the scanning screen drawn by the center and both outer electron beams was performed using two different types of magnetic field control elements. . However, as is clear from FIG. 4, the annular magnetic shielding element 17
With respect to v, the magnetic flux near the central electron beam transmission hole 16G is slightly concentrated, and therefore the vertical amplitude of the scanning screen drawn by the central electron beam is slightly expanded.

This invention utilizes the effect of concentration of magnetic flux in the vicinity of the central electron beam transmission hole on the vertical deflection magnetic field of the leakage magnetic field at the rear end of the annular magnetic shielding element. In order to easily compensate for the difference in the amplitude of the scanning screen extracted by the central and outer electron beams of a cathode ray tube in-line type electron gun, the deflection magnetic field is applied to the electron beam passing region where the leakage magnetic field at the rear end of the deflection yoke extends. 6(a) and 6(b) are perspective views showing one embodiment of the present invention, and FIG. 7 is a perspective view showing an embodiment of the present invention, the purpose of which is to arrange a novel magnetic field control element for controlling The effect of the deflection yoke rear end leakage magnetic field of the magnetic field control element 70 on the horizontal and vertical deflection magnetic fields is shown.

As is clear from FIGS. 6A and 6B, the magnetic field control element 80 has an annular shape 81 made of a high magnetic permeability magnetic material that completely surrounds the outer electron beam holes 16R and 16B on the bottom surface of the shielding magnetic pole 16, and a ring shape 81 in the center. A tongue-shaped portion 82 that extends continuously from the annular portion 81 is formed on the side of the electron beam hole 16G.The tongue-shaped portion 82 extends from the center electron beam on the straight line connecting the centers of the outer electron beam holes 16R and 16B. It is located on the side of the through hole 16G and is located on both sides of the through hole.

The small hole 83 is for regulating the direction of the tongue-shaped part, and is for controlling the direction of the shielding magnetic pole 1.
6, the tip of the tongue portion 82 and the annular portion 81 can be correctly aligned
The straight line connecting the centers of the holes is perpendicular to the straight line connecting the centers of the outer electron beam holes.

Continuing from the shaped part 81, a screen shaped part 72 is formed which is bent perpendicularly to the surface thereof. The screen-shaped portion 72 has a magnetic field control element 80 installed on the bottom surface of the shielding magnetic pole 16 so as to be perpendicular to the straight line connecting the centers of the outer electron beam holes 16R and 16B. As shown in FIG. 7, the annular portion 81 bypasses the horizontal and vertical deflection magnetic fields 5H and 5V on the two outer electron beam paths, while the tongue portion 82 With respect to the vertical deflection magnetic field 5V, the magnetic field is concentrated near the central electron beam hole 16G.Therefore, like the annular portion 81, the horizontal scanning screen of the scanning screens 34R and 34B drawn by the electron beams on both sides is This is made to match the scanning screen 34G drawn by the central electron beam. In this case, the bypass effect on the horizontal and vertical magnetic fields of the magnetic field control element 80 is larger due to the presence of the tongue 82, and the amplitude adjustment function in the horizontal direction is larger than in the vertical direction. is clear.

Next, adjust the area of the vertical magnetic field trapping part of the tongue part 82,
The scanning screen 34 drawn by the central electron beam is increased by increasing the concentration effect on the vertical deflection magnetic field 5V on the central beam path.
The vertical amplitude of G is expanded to match the vertical width of the scanning screens 34R and 34B drawn by both outer electron beams.

In this way, it is possible to match the scanned images of the central and outer electron beams over the entire screen, and the resulting color image is of excellent quality with no color shift.

Note that if the sizes of the annular portion 81 and the tongue portion 82 of the magnetic field control element 80 are appropriately selected, the scanning screen formed by both outer electron beams of the in-line electron beam caused by coma distortion of the deflection yoke and the central electron beam can be adjusted. It is possible to match any discrepancies.

As described above, by using the magnetic field control element according to the present invention, it is possible to eliminate the need for the conventional two sets of annular magnetic shielding elements and magnetic enhancement elements, and only use one set of magnetic field control elements, thereby eliminating the need for a dynamic convergence correction device. , it is possible to realize a self-convergence type color cathode ray tube in which three electron beams emitted from an in-line electron gun are concentrated at one point at all points on the moving screen to be formed on the phosphor screen.

Note that the magnetic field control element according to the present invention is not limited to the above-mentioned shape, and it goes without saying that various shapes are possible without changing the gist of the present invention.

[Brief explanation of the drawing]

Fig. 1 is a vertical cross-sectional plan view of a color cathode ray tube that does not require or only partially uses a conventional dynamic convergence correction device, and Fig. 2 is a plan view of a conventional 3-bim in-line color cathode ray tube used in the above color cathode ray tube. Figure 3 is a perspective view showing the shielding magnetic pole used in the above electron gun;
The figure is a plan view showing the operating state of the conventionally used magnetic enhancement element and annular magnetic shielding element in response to the horizontal and vertical deflection magnetic fields of the rear end leakage magnetic field of the deflection yoke. Figure 5 shows the deflection when only the annular magnetic shielding element is used. A scanning screen formed by both outer electron beams and a central electron beam on a phosphor screen by a yoke. FIG. 6(a) is a perspective view showing a magnetic field control element according to the present invention, and FIG. 7 is a diagram showing the above magnetic field control element. A plan view showing the operating state of the deflection yoke rear end leakage magnetic field with respect to the horizontal and vertical deflection magnetic fields,
FIG. 8 is a plan view showing a scanning screen in which both outer electron beams and a central electron beam are formed on the fluorescent screen by the deflection yoke by the operation of the annular portion of the magnetic field control element. In the figure, 1...3-beam in-line electron gun, 11... cathode, 12...G
1 electrode, 13...G2 electrode, 14...
G3 electrode, 15...G4 electrode, 16...
- Shielding magnetic pole, 17... Annular magnetic shielding element, 1 day... Magnetic enhancement element, 2...--Cathode ray tube glass envelope, 3... Fluorescence surface, 4... color selection mechanism, 5... deflection yoke, 51...
・Deflection yoke rear end leakage magnetic field, 6... Silent convergence device, 7... Color line converting device, 33R, 3
3G, 33B; 34R134G. 34B...Scanning screen formed by three electron beams on the phosphor screen, 80...Magnetic field control element based on the present invention. Agent Patent Attorney Original Sound Procedural Amendment (Method) Showa Year Month Day

Claims (1)

[Claims] A color cathode ray tube device comprising an in-line electron gun that emits a central electron beam and two outer electron beams aligned in a straight line, and an electromagnetic deflection device that deflects the aligned electron beams horizontally and vertically. Two magnetic field control elements arranged opposite to each other on the bottom surface of the shielding magnetic pole arranged in the electron passage region where the deflection magnetic field extends at the rear end of the deflection device on the electron gun side control the two outer electron beams. A collar characterized by having an annular portion made of a magnetic material that completely surrounds the through hole, and tongue-like portions that are located on the central electron beam through hole side in the direction of the three in-line array lines and extend to both sides sandwiching it. Cathode ray tube electron gun electrode structure.