JPH0138347B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an electron gun structure, and more particularly to a structure of an electron gun structure that improves the uniformity of the focus of an electron beam on the screen of a color picture tube.

In an in-line color picture tube, three electron beams can be converged on the screen by a non-uniform deflection magnetic field without using a convergence coil. This deflection magnetic field consists of a pink-shaped horizontal deflection magnetic field that causes three electron beams to converge on the screen in the horizontal direction, and a barrel-shaped vertical deflection magnetic field that causes three electron beams to converge on the screen in the vertical direction. It consists of a deflection magnetic field. By the way, the pink tension-shaped horizontal deflection magnetic field and the barrel-shaped vertical deflection magnetic field cause each of the three electron beams to be focused (under-focused) behind the screen in the horizontal direction, and in front of the screen in the vertical direction. It works to bring the camera into focus (over-focus). Therefore, the difference in the focusing effect of both deflection magnetic fields on each electron beam in the horizontal and vertical directions affects the electron density distribution of the electron beam itself,
This causes coma aberration at the periphery of the screen,
Poor focus uniformity. Since the coma aberration caused by the horizontal deflection magnetic field can be suppressed to a level that does not pose a practical problem by adjusting the focus voltage applied to the electron gun assembly, it is desired to improve the coma aberration caused by the vertical deflection magnetic field.

That is, as shown in FIG. 1, the electron beam 1 emitted from the electron gun 2 has a high electron density portion 3 at the center.
and a low electron density portion 4 around it. As this electron beam approaches the screen 5, it passes through a vertical deflection magnetic field 6, and electrons located near the center 9 of the deflection magnetic field receive a stronger deflection force in the vertical direction than electrons located further away from the center. .
Then, as shown by focal point 7, the electron beam is focused (over-focused) in front of the screen. Therefore, at the periphery of the screen, the electron beam spot becomes elongated in the vertical direction and has a high electron density portion 3 and a tail-like low electron density portion 8, causing coma aberration.

The above-mentioned comatic aberration can be reduced by using a large-diameter electron lens or a compound type electron lens, but there is a limit to the size of the aperture of the electron lens installed in the narrow neck of the color picture tube. However, the reduction of coma aberration achieved thereby is not necessarily satisfactory.

Further, as another structure for reducing coma aberration, a structure in which the electron gun is made rotationally asymmetric is known. For example, British Patent No. 1,352,217 discloses an electron gun assembly in which a beam passage hole of a first electrode has a vertically elongated shape and a beam passage hole of a second electrode has a horizontally elongated rectangular shape. Further, US Pat. No. 3,497,763 also discloses an electron gun assembly in which the beam passage hole of the first electrode is elliptical and the focus part is a rotationally symmetrical lens. A similar electron gun assembly is also disclosed in US Pat. No. 3,524,094. However, all of these electron gun assemblies form an asymmetric lens in the so-called triode region and attempt to select the shape of the image by making the virtual object point asymmetric. A similar effect is produced on the entire screen area, and while the peripheral areas of the screen are improved, the central area of the screen deteriorates. In other words, since the focus portion is a rotationally symmetrical lens, it is difficult to obtain good characteristics in both the center and peripheral areas of the screen.

The present invention was developed in view of the above-mentioned problem, and it forms an asymmetrical lens in the focus section to change the focus characteristics at the periphery and center of the screen. By making the focal length larger than the focal length, vertical aberrations at the periphery of the screen are reduced, and at the same time, a non-circular electron beam passage hole with a long axis in the horizontal direction is formed in the triode region, thereby improving beam astaging at the center of the screen. The purpose of the present invention is to provide an electron gun assembly that improves the focus quality over the entire screen by compensating for.

Hereinafter, the present invention will be explained in detail with reference to the drawings.

FIG. 2 shows a shadow mask-shaped color picture tube to which the electron gun structure of the present invention is applied, and the glass envelope 11 includes a panel 13, a funnel section 15 extending from the panel, and a network extending from the funnel section 15. It is composed of a section 17. Panel 13
A phosphor screen 19 with phosphor stripes 21, 23 and 25 emitting red, green and blue light is formed on its inner surface. A shadow mask 27, which is a color selection electrode, is disposed inside the panel 13 and close to the phosphor screen 19, and this shadow mask 27 receives three electron beams emitted from an electron gun 37 provided in the network portion 17. 31,
A large number of through holes 29 are provided for selecting holes 33 and 35. The electron beam is deflected by the deflection magnetic field and the through hole 29.
After passing through, it collides with a phosphor screen, causing a predetermined phosphor to emit light. Furthermore, a deflection coil 39 is attached to the outside of the funnel section 15 and the neck section 17 for forming a deflection magnetic field for deflecting the electron beam in the horizontal axis X direction and the vertical axis Y direction.

Further, the electron gun 37 consists of three electron gun units 41, 43, and 45 arranged in the X direction.
Details of each unit are shown in FIG. Each electron gun unit includes a cathode 47, a first electrode 49, and a second electrode 5 arranged along the electron beam path.
1, third electrode 53, fourth electrode 55, fifth electrode 57
and a sixth electrode 59, the cathode 47 and the first
The second electrodes 49 and 51 constitute a three-pole section, and the third to sixth electrodes 53-59 constitute a focus section. The first electrode 49 and the second electrode 51 are plate-shaped, and the third electrode 53 to the sixth electrode 59 are cylindrical. The second electrode 51 and the fourth electrode 55 are connected within the tube, and the third electrode 53 and the fifth electrode 57 are similarly connected within the tube. During operation, the sixth
The electrode 59 has an anode voltage of about 25 KV, and the third electrode 53 and the fifth electrode 57 have a focus voltage of about 7 KV.
However, 500V is applied to the second electrode 51 and the fourth electrode 55.
is applied. As shown in FIG. 5, the focus section of this electron gun assembly includes a bipotential main electrostatic lens 61 formed between the fifth electrode 57 and the sixth electrode 59, and a main electrostatic lens 61 formed between the third electrode 53 and the fifth electrode. Electrode 5
7 and a unipotential type auxiliary electrostatic lens 63.

In an electron gun assembly equipped with a focus section consisting of such a composite electron lens system, the electron beam emitted from the cathode 47 is first focused to some extent by the auxiliary lens 63 to narrow the beam diameter, and then the spherical surface of the main lens 61 is used. Deterioration of the focus of the electron beam on the screen due to aberration can be improved.

As shown in Figures 3 and 4, the first
Electrode 49 includes an elliptical non-circular electron beam passage aperture 67 having a major axis 69 substantially parallel to the horizontal axis X of the screen and a minor axis 68 substantially parallel to the vertical axis Y of the screen. . The sixth electrode 59 of the focus section has, on the side opposite to the fifth electrode 57, a long axis 72 that is substantially parallel to the horizontal axis It has an elliptical non-circular beam passage hole 71 having short axes 73 that are parallel to each other.
For example, the non-circular beam passing hole 67 in the triode section has a major axis of 0.65 to 0.7 mm and the minor axis of 0.6 mm, and the non-circular beam passing hole 71 in the focus section has a major axis of 5.55 to 5.6 mm. The short axis is formed to a size of 5.5 mm. Note that the beam passage holes of all other electrodes are formed in a circular shape.

According to the electron gun structure having the above-described configuration, the electron beam passage hole of the electrode 59 in the region that mainly gives a divergent effect to the electron beam in the focus section has an elliptical shape with a long axis in the horizontal direction, so that the main lens 61 does not rotate. It is symmetrical. Therefore, the vertical divergence effect of the electron beam becomes relatively stronger than the horizontal divergence effect, and as a result, the vertical convergence angle of the electron beam becomes smaller than the horizontal convergence angle.
In other words, the vertical focal length can be made longer than the horizontal focal length.

As mentioned above, since a barrel-shaped vertical deflection magnetic field is used in the color picture tube to which the present invention is applied, the electron beam passing through such a magnetic field is overlapping in the vertical direction, as shown in FIG.・
It receives a deflection force that causes it to focus, and focuses in front of the screen as shown by focal point 7. Comatic aberration occurs due to the low electron density portion. In contrast, in the electron gun assembly of the present invention, the focal length in the vertical direction is made longer than that in the horizontal direction in the focus section, and compensation is made to bring the focal point 7 closer to the screen 5. In other words, in the present invention, the position of the focal point is controlled so that the electron beam is focused on the screen. As a result, the peripheral area of the screen is such that coma aberration can be reduced at the four corners.

The non-rotationally symmetrical main lens 61 makes the electron beam elongated as a result, so that the beam spot is slightly elongated and non-circular at the center of the screen. Therefore, in the present invention, the first electrode 49 of the triode part
The electron beam passage hole 67 is shaped like an ellipse, and its long axis 69 is substantially aligned with the horizontal direction, so that the shape of the electron beam entering the focus section is horizontally elongated. This non-circular beam passage hole 67 functions to compensate for the non-circularity of the beam spot at the center of the screen caused by the non-circular beam passage hole 71.

In the embodiment described above, the first electrode 49 of the triode section and the sixth electrode 59 of the focus section are provided with non-circular electron beam passage holes, but the other electrodes of the triode section and the focus section are provided with non-circular electron beam passage holes. A non-circular electron beam passage hole can also be applied. That is, the non-circular electron beam passage hole provided in the focus section is provided in the electrode corresponding to the region where the electron beam mainly receives the divergent effect, that is, the electrode on the side to which a higher voltage is applied of the two opposing electrodes. It's fine if you can. For example, in the electron gun assembly shown in FIG.
9 and the electron beam passage hole on the side facing the fourth electrode 55 of the fifth electrode 57 is made non-circular, or the first electrode 49
and the electron beam passage hole on the side of the third electrode 53 facing the fourth electrode 55 may be made non-circular. Note that the electrodes provided with the non-circular electron beam passage hole are not limited to a combination of two electrodes, and may be three or more, such as the first electrode, second electrode, and sixth electrode. Of course. Further, the shape of the non-circular electron beam passage hole is not limited to an ellipse, but may be a teardrop shape or a rectangle.

Furthermore, in the above-mentioned embodiments, a uni-bipotential type of composite electron gun structure was described, but as is clear from the above description, the electron gun structure of the present invention has a structure in which one of the electrodes forming the triode part is If at least one electron beam passage aperture of at least one electrode and at least one electrode of the lens system of the focus section which mainly gives a diverging effect to the electron beam is formed into an elongated non-circular shape along the horizontal axis of the screen, Therefore, the present invention can be applied to uni-potential type, bi-potential type, tri-potential type,
It can also be applied to other electron gun structures such as periodic potential type.

As described above, according to the electron gun structure of the present invention, coma aberration around the screen caused by the vertical deflection magnetic field can be removed, and blurring of the electron beam spot around the screen can be reduced. It is effective and its industrial value is extremely large.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing the shape of an electron beam generated by a conventional electron gun assembly, and FIG. 2 is a partially cutaway perspective view of a color picture tube equipped with an embodiment of the electron gun assembly of the present invention. 3 is a perspective view showing the relative position of the non-circular electron beam passing hole in this embodiment, FIG. 4 is a plan view showing the non-circular electron beam passing hole,
FIG. 5 is a sectional view of the electron gun assembly of this embodiment. 2, 37...electron gun, 19...phosphor screen, 47...cathode, 49...first electrode, 51
...Second electrode, 53...Third electrode, 55...Fourth electrode
Electrode, 57...5th electrode, 59...6th electrode.

Claims (1)

[Claims] 1. A triode section disposed opposite to a screen defined by a horizontal axis and a vertical axis and having at least a cathode, a first electrode, and a second electrode; In an electron gun assembly comprising a focus section that focuses an electron beam on the screen,
An electrode to which a higher voltage is applied among at least a pair of electrodes that face each other and to which different voltages are applied, forming the electron beam passage hole part and the focus part of at least one electrode of the three-electrode part excluding the cathode. An electron gun assembly characterized in that each of the electron beam passage holes is formed in a non-circular shape having a major axis or a long side along the horizontal axis. 2. The electron gun assembly according to claim 1, wherein the non-circular shape is an ellipse, a teardrop shape, or a rectangle.