JPH0158827B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION This invention enables multiple electron beams to be focused at one point at all points on the scanning screen formed on the phosphor screen without using a dynamic convergence correction device or using only a part of the dynamic convergence correction device. This invention relates to a self-convergence color cathode ray tube in-line electron gun.

In order to facilitate understanding of the present invention, conventional examples will be described 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. Three electron beams emitted from the in-line electron gun 1, aligned in a straight line and in the same plane, are deflected by an electromagnetic deflection device (hereinafter referred to as deflection) arranged in a funnel-shaped part of the evacuated glass envelope 2. (called a yoke) 5 horizontally and vertically, and on the front part of the glass envelope 2, on the inside thereof is a phosphor screen 3 covered with a plurality of red, green and blue emitting phosphor elements. to form a scanning screen. Inside this tube, a perforated mask 4 is placed adjacent to the phosphor screen 3.
A color selection mechanism is arranged such that each scanning electron beam stimulates only the phosphor elements of the color corresponding to the respective electron beam.

FIG. 2 shows, as an example, the configuration of a conventional in-line electron gun in which the main electron lens used in the cathode ray tube has a bipotential focus configuration, and the electrode configuration is insulated from each other. , three cathode assemblies 11 arranged in a line with equal distances S, and a G1 electrode 12 and a G2 electrode 1 facing them and arranged sequentially in the electron beam traveling direction.
3. G3 electrode 14, G4 electrode 15, and shielding magnetic pole 1
Although each electrode except the shielding magnetic pole 16 is not shown, it is fused and fixed to an insulator support rod via each electrode support part, and a predetermined electrode spacing is maintained. G1 electrode 12, G2 electrode 13, G3 electrode 14
Each through hole 12R, 12G, through which the electron beam passes through
12B; 13R, 13G, 13B; 14R ₁ , 1
4G ₁ , 14B ₁ and 14R ₂ , 14G ₂ , 14B ₂ are also aligned in a line with equal distances S, and the electron beams radiated from the three cathodes 11R, 11G, 11B of the cathode assembly 11 have a parallel path 10R. ,10
It is accelerated to move above G, 10B. The distance S' between the through holes of the G4 electrode 15 is somewhat larger than the above-mentioned S, and the two outer parts of the main electron lens formed in each corresponding through hole gap between the G3 electrode 14 and the G4 electrode 15 are forms an asymmetric electric field, and when there is no deflection magnetic field generated by the deflection yoke 5, the outer two electron beams are electrostatically concentrated at the center 31 of the phosphor screen 3 into a central electron beam. .

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,
A static compurge device 6 is arranged so as to be able to correct small errors in the center of the phosphor screen due to assembly errors of the electron gun assembly 1 and the like. Further, adjacent to the static convergence device 6, a color dulling 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. In addition to the strong pincushion distortion, the vertical deflection magnetic field has a strong barrel distortion in the coil winding distribution of the deflection yoke, and the astigmatism of the magnetic field within the deflection coil is appropriately harmonized. Furthermore, the three electron beams aligned in a straight line are By selecting the mutual spacing S to a suitably small value, the scanning screens 33R and 33B formed by the two outer electron beams are made to coincide with each other, as shown in FIG. 5, and this and the scanning screen 33G formed by the central electron beam
can be almost matched. This concentration error in the scanning screen is small enough to be tolerated in a cathode ray tube with a small screen of 15 inches or less with a deflection angle of 90 degrees, but cannot be ignored in a cathode ray tube with a screen larger than 15 inches, and cannot be ignored in reproduced color images. The result is an unpleasant color shift.

This is because both outer electron beams 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 depending on the central electron beam and both outer electron beams.
This is caused by so-called coma distortion. In order to correct this coma distortion, a small magnetic element that partially controls the deflection magnetic field is installed at the G4 electrode of the electron gun assembly 1 in the electron beam passing region where the rear end leakage magnetic field 51 (FIG. 1) of the deflection yoke 5 reaches. It is arranged in the electron beam exit hole portion of No. 15. That is, the centers of the shielding magnetic poles 10R, 10G,
Through holes 16R, 16G, 16B aligned with 10B
The two outer through holes 16R and 16B are surrounded by an annular magnetic shielding element 17 made of a magnetic material with high magnetic permeability, and as shown in FIG. 4, horizontal and vertical leakage magnetic fields 5H and 5V are generated.
is 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, the annular magnetic shielding element 17
By appropriately selecting the size of the magnetic flux, that is, the trapping area for the magnetic flux, the scanning screens 33R and 33B drawn by both outer beams at the top and bottom of the screen are made to match the scanning screen 33G drawn by the center beam, as shown in FIG. Is possible. 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 central beam, and this residual coma distortion is compensated for by the outer scanning screens 33R and 33B.
In order to match the inner scanning screen 33G to
As shown in FIG. 3, a set of high magnetic permeability materials is placed on both sides of the central electron beam hole 16G in a direction perpendicular to this arrangement, which is not adjacent to the two outer electron beam holes 16R and 16B. A magnetic enhancement element 18 consisting of a small disk is mounted in the same plane as the magnetic shielding element 17. As shown in FIG. 4, this element concentrates the horizontal leakage magnetic field 5H near the central electron beam hole, expands the horizontal amplitude of the scanning screen 33G created by the central electron beam, and expands the horizontal amplitude of the scanning screen 33G of both outer electron beams.
3R, 33B and central electron beam scanning screen 33G
It is possible to match both the left and right sides of the screen horizontally. In this way, a scanned screen without color shift can be obtained over the entire screen.

Conventional self-convergence color cathode ray tube in-line electron guns use two different types of magnetic field control elements to compensate for the discrepancy in the size of the scanning screen drawn by the central and outer electron beams, as described above. . However, as is clear from FIG. 4, the annular magnetic shielding element 17 concentrates the magnetic flux in the vicinity of the central electron beam transmission hole 16G against the vertical deflection magnetic field of 5 V, albeit slightly, and therefore The vertical amplitude of the scanning screen is slightly expanded.

This invention utilizes the effect of concentrating magnetic flux near the central electron beam transmission hole on the vertical deflection magnetic field of the leakage magnetic field at the rear end of the deflection yoke of the annular magnetic shielding element, and enables color cathode ray tube in-line processing without using a conventional magnetic enhancement element. In order to easily compensate for the difference in the amplitude of the scanning screen drawn by the central and outer electron beams of the type electron gun, a new method is used to control the deflection magnetic field in the electron beam passage area where the leakage magnetic field at the rear end of the deflection yoke extends. The purpose is to provide a magnetic field control element with a magnetic field control element.

6a and 6b are perspective views showing one embodiment of the present invention, and FIG. 7 is a magnetic field control element 8 based on the present invention.
The effect of the leakage magnetic field at the rear end of the deflection yoke at zero on the horizontal and vertical deflection magnetic fields is shown.

As is clear from FIGS. 6a and 6b, the magnetic field control element 80 includes an annular portion 81 made of a high magnetic permeability magnetic material that completely surrounds the outer electron beam holes 16R and 16B at the bottom of the shielding magnetic pole 16, and a central electron beam. Through hole 16
A tongue-shaped portion 8 that extends continuously from the annular portion 81 on the G side.
2 is formed. The tongue-shaped portion 82 is fixed to the bottom surface of the shielding magnetic pole 16 so as to be located on the side of the central electron beam hole 16G on a straight line connecting the centers of the outer electron beam holes 16R and 16B, and to face both sides of the hole. ing.

The small hole 83 is for regulating the direction of the tongue-like part, and by aligning it with the small hole previously drilled at the corresponding position on the bottom surface of the shielding magnetic pole 16, the tongue-like part 8 can be correctly aligned.
2 and the center of the annular portion 81 is provided so that the straight line connecting the center of the outer electron beam hole coincides with the straight line connecting the center of the outer electron beam hole.

The state in which the shielding magnetic pole 16 on which the magnetic field control element 80 is installed is placed within the leakage magnetic field at the rear end of the deflection yoke is referred to as the seventh
As shown in the figure. As can be seen from the figure, the annular portion 81 bypasses the magnetic fields on the two outer electron beam paths of the horizontal and vertical deflection magnetic fields 5H and 5V as in the prior art, while the tongue portion 82 bypasses the magnetic fields on the two outer electron beam paths for the vertical deflection magnetic field 5V. Hole 1
The magnetic field is concentrated near 6G. Therefore,
By optimizing the trapping area of the annular portion 81 in the magnetic field, the bypass effect on the magnetic field is increased.
As shown in FIG. 8, the scanning screens in the horizontal direction of the scanning screens 34R and 34B drawn by both side electron beams are made to coincide with 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. it is obvious. Next, the area of the vertical deflection magnetic field trapping part of the tongue 82 is adjusted to increase the concentration effect on the vertical deflection magnetic field 5V on the central electron beam path, thereby expanding the vertical amplitude of the scanning screen 34G drawn by the central electron beam. The vertical widths of the scanning screens 34R and 34B drawn by both outer electron beams are matched.

In this way, the scanning screen drawn by the center and both outer electron beams can be matched over the entire screen,
Its color screen provides excellent images 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 deviations.

As described above, if the magnetic field control element according to the present invention is used, only one set of magnetic field control element is used instead of the conventional two sets of annular magnetic shielding element and magnetic enhancement element, and there is no need for a dynamic convergence correction device. This makes it possible to realize a self-convergence 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 scanning screen that forms them 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 drawings]

Figure 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 Figure 2 is a plan view of a conventional three-beam in-line type electron beam used in the color cathode ray tube. Longitudinal cross-sectional view of the gun body including the three electron beam axes,
FIG. 3 is a perspective view showing a shielding magnetic pole used in the above electron gun, and FIG. 4 is a conventionally used magnetic enhancement element, the operating state of the annular magnetic shielding element with respect to the horizontal and vertical deflection magnetic fields of the leakage magnetic field at the rear end of the deflection yoke. FIG. 5 is a scanning screen in which both outer electron beams and a central electron beam are formed on the phosphor screen by the deflection yoke when only the annular magnetic shielding element is used, and FIG. 6 a and b are based on the present invention. FIG. 7 is a perspective view showing the magnetic field control element; FIG. 7 is a plan view showing the operating state of the magnetic field control element in response to the horizontal and vertical deflection magnetic fields of the rear end leakage magnetic field of the deflection yoke; FIG. 8 is the operation of the annular portion of the magnetic field control element. FIG. 3 is a plan view showing a scanning screen in which both outer electron beams and a central electron beam are formed on a phosphor screen by a deflection yoke. In the figure, 1... 3-beam inline electron gun, 11... cathode, 12... G1 electrode, 1
3... G2 electrode, 14... G3 electrode, 15... G4 electrode, 16... Shielding magnetic pole, 17... Annular magnetic shielding element, 18... Magnetic enhancement element, 2... Cathode ray tube glass envelope, 3 ... Fluorescent screen, 4 ... Color sorting mechanism, 5
... Deflection yoke, 51 ... Deflection yoke rear end leakage magnetic field, 6 ... Static convergence device, 7 ... Color purification device, 33R, 33G, 33B; 34R, 34
G, 34B...Scanning screen formed by three electron beams on a fluorescent screen, 80...Magnetic field control element based on the present invention.

Claims (1)

[Claims] 1. An in-line electron gun that emits a central electron beam and two outer electron beams aligned in a straight line, an electromagnetic deflection device that deflects the aligned electron beam horizontally and vertically, and an electromagnetic deflection device that deflects the aligned electron beam horizontally and vertically. The rear end of the device on the electron gun side has an annular portion made of a magnetic material that completely surrounds each of two outer electron beam through holes formed on the bottom surface of the shielding magnetic pole in the electron beam passing region where the deflection magnetic field extends. In the color cathode ray tube electron gun electrode assembly including two magnetic field control elements, each of the two magnetic field control elements has a tongue-shaped portion extending to the side sandwiching the central electron beam hole. Color cathode ray tube electron gun electrode structure.