JPS6086737A - In-line type electron gun structure - Google Patents

Abstract

PURPOSE:To remove asymmetric aberration due to coma of scanned picture formed by the central and both side electron beams by shortening the length of cylinder side portion of a cylindrical concentrated magnetic pole with bottom and made non-magnetic material. CONSTITUTION:In a concentrated magnetic pole 20, a pair of magnetism reinforced elements 15, 16 oppositely arranged in such a way as interposing therebetween a central electron beam penetrating opening 22 drilled on the bottom 21 on the vertical axis Y-Y, and annular magnetism screening elements 17, 18 surrounding both outside electron beam penetrating openings 23, 24 drilled on the horizontal axis X-X are arranged. The height h of the cylinder side portion 29 is set to 6.0mm. or less. Then, eddy current loss in horizontal deflection magnetic field can be prevented and convergence error in right and left ends of the picture of both the outside electron beams and the central electron beam can be minimized to prevent deterioration of picture quality due to color slip.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a two-star cathode ray tube in which a central and a pair of outer electron beams emitted from an in-line electron gun form a two-star cathode ray tube on a fluorescent surface by a common deflection magnetic field. The present invention relates to a self-convergence-type in-2-in type electron gun that can have the same size regardless of the horizontal deflection frequency.

The IT diagram is a longitudinal cross-sectional view of a color cathode ray tube using a conventionally used in-line electron gun of a dynamic convergence method (which does not require a so-called self-convergence method).

A central electron beam Bl emitted from an in-two-in electron gun l and located in the same plane, and a pair of outer electron beams B2.
B3 is deflected horizontally and vertically by a deflection device 5 disposed in the funnel-shaped part of the evacuated glass envelope 2, and is located on the top surface of the glass envelope 2, and has a plurality of lights emitting light in three colors inside. A scanning screen is formed on a phosphor surface 4 on which phosphor pixels are deposited through a shadow mask 3 placed opposite thereto. In order to make this color cathode ray tube a self-writing convergence method that does not require dynamic convergence correction, the horizontal deflection magnetic field of the deflection device i5 is made to have a strong pincushion distortion, and the vertical deflection magnetic field is made to have a strong barrel distortion, as shown in Figure 2. As shown, these deflection magnetic fields cause a pair of outer electron beams B2. The comatic aberration of B3 is eliminated to form a matching scanning screen 6 on the fluorescent surface 4. In this case, the scanning screen 7 of the central electron beam B1 generally has both horizontal and vertical outer electron beams B2. It is smaller than the scanning screen 6 formed by B3.

This misalignment of the scanning screen is due to the coma aberration of the deflection device 50. In order to eliminate the coma aberration and make each scanning screen consistent, the deflection device 50 is attached to the tip of the electron gun l, which is exposed to the leakage magnetic field at the rear of the deflection device 5. A magnetic field control element made of a magnetic material with high magnetic permeability is disposed on the bottom surface 11 of the concentrated magnetic pole lO, which is formed in the shape of a cylinder with a bottom and made of a non-magnetic material. FIG. 83 shows an example of a magnetic field control element, in which the central electron beam transmission aperture 12 formed in the bottom surface 11 of the concentrated magnetic pole 10 is aligned with the vertical axis Y, which is the short axis of the fluorescent surface 4.
A pair of disc-shaped magnetic enhancement elements 15 and 16 placed opposite each other on -Y, and both outer electron beam transmission apertures 13 bored on the horizontal axis XX, which is the long axis of the fluorescent surface 4. , 14 are arranged to surround the annular magnetic shielding elements 17, 18. The magnetic enhancement elements 15, 16 increase the deflection sensitivity of the horizontal deflection magnetic field FH of the deflection device 5 with respect to the central electron beam B1 on both outer electron beams B2. B3, the annular magnetic shielding elements 17 and 18 are arranged on both outer sides of the electron beam AB2. For B3.

It has the function of lowering the deflection sensitivity of the horizontal and vertical deflection magnetic fields FH and FV of the deflection device 5 relative to the center electron beam Bl, and increasing the deflection sensitivity of the vertical deflection magnetic field FV relative to the center electron beam Bl relative to both outer electron beams. .

Therefore, by the magnetic field control elements 15.16 and 17.18, the scanning screen 7 of the central electron beam Bl is enlarged both horizontally and vertically, and conversely, the scanning screen 6 of the outer electron beams B2 and B3 is enlarged.
is reduced, comatic aberration due to the deflection magnetic field is eliminated, and it becomes possible to perfectly match the scanning planes 6.7.

On the other hand, recently, so-called display color cathode ray tubes, which are color cathode ray tubes with high resolution characteristics, have been used to display various types of information.
Kanji, charts, etc. are displayed in high density.

In order to achieve high-density display, color cathode ray tubes must have high resolution and uniform focus characteristics, the video circuit must have a wide frequency band to increase the horizontal resolution layer of the display screen, and the vertical direction of the display screen must be In order to increase the resolution, it is necessary to have a large number of scanning lines.

Normally, in order to increase the number of scanning lines as a means of high-density display, the horizontal deflection frequency fh is increased to more than 15.734 KHz of the current standard color TV system. In this case, horizontal deflection frequency fh = 15.73
A scanning screen 6' formed by the inner, outer and central electron beams due to the horizontal deflection magnetic field, which had no problems at around 4KHz;
7' coma aberration occurs, and as shown in FIG. 4, the scanning screen 6 of both outer electron beams is
' is slightly enlarged in the horizontal direction, and the rate of enlargement is different on the left and right sides of the fluorescent surface 4, and the enlarged dimension d1 on the left side is larger than the enlarged dimension d2 on the right side (this creates an asymmetry. The deviation causes a convergence error that depends on the horizontal deflection frequency, which significantly deteriorates the quality of the image received on the fluorescent surface.For example, in a 20-inch 90-degree deflection force 2-cathode ray tube, the horizontal deflection frequency fh = 15, 73 KHz. 2 times f h -31,5)G(z, then the above 9d1
+'2 is near the outermost periphery of the effective fluorescent surface, dl=Q, 7gu,
d2=9.3 questions. The reason why a shift due to coma aberration occurs in the horizontal direction in the scanning screen s/, 71 formed by both outer electron beams and the central electron beam as the horizontal deflection frequency fh increases is as follows.

First of all, the screen vertical axis Y of the bottomed cylindrical concentrated magnetic pole 10
- The magnetic flux of the horizontal deflection magnetic field penetrating the side part 19 in the Y direction generates an eddy current in the magnetic flux passing surface, which generates a magnetic flux that obstructs the change in the magnetic flux of the horizontal deflection magnetic field, attenuates the magnetic flux, and and both outer electron beams B1. B2. Reducing the deflection sensitivity of B3 and reducing its horizontal deflection amplitude, the reduction in magnetic flux reduces the magnetic shielding effect of the annular magnetic shield 17,18. The loss of magnetic flux due to this eddy current was completely negligible at the conventional horizontal deflection frequency fh=ts, about 7aKHz, but as the frequency increases, the loss of magnetic flux due to the eddy current becomes impossible to ignore, as shown in Figure 4. The scanning screen 6' of both outer electron beams is the scanning screen 7 of the central electron beam.
′, it will spread in the left and right direction.

On the other hand, the current waveform applied to the horizontal deflection coil of the deflection device 5 to perform horizontal scanning is a sawtooth wave shown in FIG. The time t2 from point b to point C is the horizontal retrace time, and t2 is usually set to about 115 of tl. Point a or point 0 corresponds to the left end of the horizontal scanning screen, and point b corresponds to the right end position. That is, the left end position of the horizontal scanning screen corresponds to the end of the horizontal retrace time t2, the right end corresponds to the end of the horizontal retrace time t1, and during the horizontal retrace time t2, the horizontal retrace time tl
A magnetic field is generated by the current that changes about five times faster than the inside.
Therefore, due to the reduction in magnetic flux due to eddy current loss due to the harmonic component magnetic field, the magnetic shielding effect loss of the annular magnetic shielding elements 17 and 18 is greater on the left side of the phosphor screen than on the right side, as shown in Figure 4. The horizontal expansion width of both outer electron beam scanning screens 6' with respect to the central electron beam scanning screen 7' is dl on the left side.
is larger than d2 on the right side, an asymmetry occurs in the comatic aberration in the horizontal direction. Conventional standard color TV system (NTS
At fh=15.734KHz used in C method), t1==st ~53μsec, t2=l
O~l 21' rainbow, the eddy current loss caused by this can be completely ignored, and the above-mentioned coma aberration and its asymmetry were not found substantially, but as fh increases, the difference between tl and tl, and even more effective In order to increase the scanning time t1, the retrace time t2 is set to be as small as possible, and the asymmetry of the horizontal deflection magnetic flux reduction based on eddy current loss becomes a non-negligible amount, and the above phenomenon becomes noticeable. It's coming.

The present invention has been made in view of the above-mentioned drawbacks.The present invention has been made in view of the above-mentioned drawbacks.The present invention has been made in view of the increase in the horizontal deflection frequency of a cathode ray tube using a self-convergence type in-line electron gun. This is to prevent deviations due to aberrations.

That is, the lateral length of a bottomed cylindrical concentrated magnetic pole made of a non-magnetic material attached to the tip of the electron beam exit side of an in-line electron gun is limited to a short length.

With this configuration, it is possible to prevent eddy current loss in the horizontal deflection magnetic field penetrating the side part of the concentrated magnetic pole tube, and it is possible to prevent eddy current loss due to the scanning screen formed by the central and both outer electron beams, regardless of the increase in the horizontal deflection frequency. The asymmetric shift can be eliminated, and the in-2-in type electron gun can be made into an electron gun assembly capable of displaying high-density video information.

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

Figure 6 shows the above-mentioned horizontal coma aberration of the center and both outer electron beams at the left end of the screen of a 20-inch 90-degree deflection cathode ray, with the horizontal axis representing the side length of the concentrated magnetic pole tube and the horizontal deflection frequency fh as a parameter. It is a figure showing quantity d1. As is clear from Fig. 6, when h=8 and Qmm is exceeded, fh=3
For 1.5 to 64 KHz C vs. 1° dl, Q becomes 1 mm or more and increases rapidly. h=s,.

When mm, fh = 31.5KHz, d1 = Q, Q
9mm.

fh=64KHz, dl=0.18mm, h=
At 6.0 mm, f h = 31.5 KHz, dl
=0.05mm, d1 at fh=64 KHz
=O, l mm.

Generally, if the convergence error is 0.2 mm or more, it becomes noticeable and deteriorates the image quality, but if it is 0.1 mm or less, the color shift is not a problem.

On the other hand, a plurality of bulbous bases are attached to the side of the conventional concentrated magnetic pole, which fixes the electron gun assembly within the cathode ray tube microscope section, and connects the internal waveguide film applied from the funnel-shaped part of the cathode ray tube to the inner wall of the neck. Because it has the function of supplying a higher voltage to the electron gun structure, or is equipped with a getter support with a getter container necessary to maintain a high vacuum inside the cathode ray tube, the side length of the normal part is sufficiently large, approximately 15 to 25 mm. Selected.

In the present invention, in order to maintain the occurrence of the convergence error at the side part of the concentrated magnetic pole tube at a level that does not deteriorate the image quality by increasing the horizontal deflection frequency, the length of the side part is set to 5. FIG. 7 shows a perspective view of the concentrated magnetic pole 20. The concentrated riIi pole 20 includes a pair of magnetic enhancement elements 15 that are arranged opposite to each other so as to sandwich the central electron beam transmission aperture 22 formed in the bottom surface 21 on the vertical axis YY, which is the short axis of the fluorescent surface, as in the conventional case. .16, and an annular magnetic shielding element 17 surrounding the inner and outer electron beam transmission apertures 23 and 24't formed on the horizontal axis XX, which is the long axis of the fluorescent surface.
゜18 is arranged. However, the height h of the side part 29
is 5. Although it is set below Q m m, it is possible to fix a plurality of valve spacers or funnel getter supports (not shown) to the side portion 29 as in the conventional case.

As described above, according to the embodiment of the present invention, even if the horizontal deflection frequency fh is increased from 15.75 KHz to 64 KH1, the convergence error 'irO, tmm or less, and by reducing the amount of error, the asymmetry can be ignored, and even if the horizontal deflection frequency of the color cathode ray tube is increased and high-density display is performed, image quality due to color shift will not deteriorate. will disappear. Furthermore, since the dependence of the convergence error on the horizontal deflection frequency is eliminated, the same magnetic field control element can be used without having to change the magnetic field control element installed in the concentrated magnetic pole to one optimized for each horizontal deflection frequency used. It also has the advantage of simplifying the cathode ray tube manufacturing process, and its industrial practical value can be said to be extremely high.

[Brief explanation of drawings]

Figure m1 is a vertical cross-sectional view of a color cathode ray tube using a conventional self-convergence type in-line electron gun, and Figure 2 shows electrons from the center and both outer electron guns on the fluorescent surface of this color cathode ray tube. The scanning screen formed by the beam is
Figure 3 shows the magnetic field control element that corrects the coma aberration of the scanning screen and its effect on the horizontal and vertical deflection magnetic fields. Figure 5 shows the waveform of the current flowing through the horizontal deflection coil, and Figure 6 shows the deviation of the convergence error between the side length of the concentrated magnetic pole tube and the horizontal deflection frequency as a parameter. FIG. 7 shows a perspective view of a concentrated magnetic pole according to an embodiment of the present invention. l... In-line electron gun, 2... Glass envelope. 4... Fluorescent surface, 5... Deflection device, 6.
6'...Scanning screen formed by both outer electron beams, 7.7'...Scanning screen formed by central electron beam, 10.20...Concentrated magnetic pole, 12 .22・
...Central electron beam transmission aperture. 13.14, 23.24...Both outer electron beam transmission apertures. 19.29... side part, 15.16...
・Magnetic enhancement element. 17.18...Annular magnetic shielding element. T)4(2) Taku 5th Ward

Claims (1)

[Claims] 5. The side length of the bottomed cylindrical concentrated magnetic pole made of a non-magnetic metal material attached to the tip of the electron beam exit side of the electron gun. Qm
An in-line electron gun structure characterized by being limited to less than m.