JPS6258103B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to an improvement in an in-line type color picture tube electron gun, and more specifically, in a so-called integrated electron gun in which at least the main lens portion is integrated (unitized), a color The focusing voltage of the electron guns corresponding to the three colors of red, green, and blue phosphors coated on the inner surface of the picture tube panel is the same, and the slightly different electron beam spot shapes seen in the integrated electron gun are created. This improves the apparent misconvergence when the current density is high in the center of the screen, and also improves the appearance of astigmatism (commonly known as smearing) caused by deflection aberration when the electron beam is deflected to the periphery of the screen. The purpose is to remove the top.

As is well known, the electron gun of a cathode ray tube (not shown) generally has two basic parts: an electron beam source (including an object point forming part) and an electron beam emitted from the electron beam source onto the fluorescent surface of the cathode ray tube. It consists of a focusing lens section that focuses the electron beam, and the former is called the triode section and the latter is called the main lens section.

As shown in Fig. 1, recent in-line type electron guns for color picture tubes have a main lens part 1 integrated into a cylindrical conductor with openings 2B, 2G, and 2R at positions corresponding to the central electron beam and both side electron beams. A first focusing electrode 3 with holes formed therein, and a second focusing electrode opposite thereto with openings 5B, 5G, and 5R formed in the same cylindrical conductor at positions corresponding to the central electron beam and both side electron beams. 4, the so-called unitized type main lens is mainstream, and the so-called bipotential type main lens is the majority.

This is because in-line color picture tube devices themselves have become self-concentrating, and it has become necessary to improve the assembly precision of the color picture tube and deflection yoke as well as the electron gun itself.

The unitizing electron gun shown in FIG. 1 has apertures 2B and 2R corresponding to both side electron beams of the first focusing electrode 3 in order to statically concentrate the central electron beam and the side electron beams at the center of the screen. The openings 5B and 5R of the second focusing electrode 4 are slightly eccentric, and the facing surface 6 of the second focusing electrode 4 is usually slightly concave.

Therefore, unlike the conventional independent three-electron gun type, this lens system can be said to produce astigmatism in principle, at least with respect to both side electron beams.

Here, 7 is a second electrode, 8 is a first electrode, 9 is a cathode, and 10 is a heater, and these electrodes are supported at predetermined intervals through insulating support rods (not shown).

As is well known, the suitable magnetic field of the deflection yoke used in a self-concentrating color picture tube incorporating an electron gun having the above-described structure is a pincussion type for the horizontal magnetic field and a barrel type non-uniform magnetic field for the vertical magnetic field.

Such a self-concentrating in-line color picture tube device has the following drawbacks.

First, in the case of a unitized electron gun, as mentioned above, it basically contains an astigmatism component, and the optimum focusing voltage of the central electron beam and both side electron beams are slightly different. The electron beam 13G is slightly horizontally elongated, with both side electron beams 13
In B and 13R, the electron beam spot becomes slightly elongated. In other words, the optimum focusing conditions of the electron beam in the horizontal and vertical directions are different for each beam, and the difference in the shape of the spot causes the apparent difference in the shape of the spot, especially when the current density is high. It looks like the upper misconvergence remains.

Second, when deflection is applied in a very non-uniform magnetic field, astigmatism (commonly known as smearing) caused by so-called deflection aberration occurs at the periphery of the screen, as shown in Figure 2. ) is likely to occur, resulting in astigmatism 11 shown with diagonal lines at the periphery of the actual electron beam spot 12, especially when correction is performed using a purity magnet etc. that corrects and absorbs assembly errors of color picture tubes. The electron beam flux emitted from the electron beam generation source is slightly eccentric or tilted from the central axis of the electron gun, which tends to cause astigmatism and coma aberration, which has the disadvantage of further deteriorating blurring at the periphery of the screen. ing.

Therefore, it is preferable that the central electron beam and both side electron beams have the same diameter and are slightly elongated vertically, and that when the electron beams are focused in the horizontal direction, they are slightly underfocused in the vertical direction.

It is well known that the above problem can be improved in principle by using a rotationally asymmetric electron gun.

That is, the first method is to make the electrode openings constituting the triode part of the electron gun non-circular, for example, in an elliptical shape having a major axis along the vertical axis of the color picture tube (Y direction in FIG. 2). In such a structure, by adjusting the diameter of the aperture corresponding to the central electron beam and the side electron beams, the electron beams are formed on a fluorescent surface made of phosphors that emit light in three colors: red, green, and blue. Although it is possible to match the diameter and shape, it is not possible to fine-tune the horizontal and vertical focusing conditions of each electron beam due to the slight difference in focusing conditions mentioned above, and as a result, astigmatism at the periphery of the screen occurs. It is not very effective against an increase in electron beam diameter (bleeding).

The second method is to make the main lens aperture of the electron gun non-circular, but in this case, the effect of this aperture shape is very strong, so for example, in an electron gun with an aperture diameter of 5.5 mm, It is known that it is sufficient to make the opening diameter only about 50 microns, that is, about 1/100 of the diameter. Although this is possible in terms of design, the manufacturing error of electron gun parts is ±1/100 mm and the assembly error is ±3/1.
Considering 00 mm, there are many problems from a practical standpoint. In particular, it is nearly impossible to match the diameters of the center electron beam and both side electron beams to the extent of ellipses.

Therefore, when making the main lens portion rotationally asymmetric, it is ideal if the sensitivity to so-called ellipticity (deviation from a perfect circle) becomes less sensitive.

The present invention relates to an in-line color picture tube electron gun developed in view of the above drawbacks.

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

FIG. 3 is a diagram schematically showing an embodiment of an in-line color picture tube electron gun according to the present invention.
1 is a cathode, 15 is a first electrode, and 16 is a second electrode, which constitutes a so-called three-pole portion of an ordinary electron gun. The aperture may be either circular or non-circular. 17 is a first focusing electrode, 18 is a second focusing electrode, and the aperture corresponding to the center electron beam and the aperture on both sides for the electron beam The holes are all approximately elliptical, and as shown in FIG. 4, for example, the longitudinal direction of these holes is approximately perpendicular to the line connecting the centers of these holes, and the central electron beam hole is Part 21G
The length in the longitudinal direction is relatively longer than the length in the longitudinal direction of the electron beam openings 21R and 21B on both sides. 19 is a third focusing electrode, 20 is a fourth focusing electrode, and the openings thereof are usually preferably circular; and the first focusing electrode 17 and the third focusing electrode 19, and the second electrode 16 and the second focusing electrode 18 are In other words, the first focusing electrode of the well-known bipotential electron gun shown in FIG. In this configuration, the electrode (voltage applied) is divided into two parts, and an auxiliary electrode in which at least one of the openings is non-circular is inserted in the middle.

The second focusing electrode 18 is normally connected to a voltage of several hundred volts.
A voltage of about 2 K.V. is applied, and, for example, the second electrode 16 is connected within the tube as described above.

With the electron gun configuration described above, the shape of the electron beam on the fluorescent surface can be easily formed into a non-circular beam by the shape of the aperture of the second focusing electrode 18 and the effect of the non-rotationally symmetrical component as the auxiliary electrode. It also has the advantage that the degree of ellipse of the electron beams on both sides can be easily controlled.

The effects and advantages of the present invention will be explained in detail below.

First, the thickness of the second focusing electrode 18 is made relatively thin, and the apertures corresponding to the center beam and side beams are formed in the vertical axis direction of the color picture tube (Y direction in FIG. 2).
The ellipticity of the aperture corresponding to the central electron beam is always greater than the ellipticity of the aperture corresponding to both side electron beams by forming the aperture into a substantially elliptical shape having a major axis along the central electron beam. The electron beams of three colors red, green, and blue on the fluorescent surface can be made to fit into the same desired longitudinal shape under the same focusing conditions.

In this case, if the thickness of the second focusing electrode is set relatively thin, the first focusing electrode 17 and the second focusing electrode 1
8. The effect of the local unipotential lens formed in the space of the third focusing electrode 19 becomes weaker, so the effect on the ellipticity mentioned above also becomes weaker. For example, in the case of a lens diameter of 5.5 mm, the ellipse becomes approximately 0.1 to 0.3 mm. In this case, since the effectiveness is only equivalent to that of the conventional method at 50 microns, the drawbacks of the conventional method, such as the sensitivity problem of the listening method and the problem of parts and assembly precision, can be solved.

Second, it has the advantage that the focusing conditions of the electron beam in two directions, horizontal and vertical, can be easily adjusted by selecting the ellipticity.

As described above, the present invention provides a new electron gun that can completely solve the sensitivity problem of the conventional method.

Next, other embodiments of the present invention will be described.

In the above embodiment, except for the triode part, the second
Although it has been explained that it is preferable that only the aperture of the focusing electrode 18 (auxiliary electrode) is non-circular, in this example, the second
The same effect can be obtained even if the opening of the focusing electrode 18 is a perfect circle and the side of the opposing first focusing electrode 17 or third focusing electrode 19 that is closer to the second focusing electrode 18 is made non-circular. The two embodiments may be combined, but also in this case the fourth one of the third focusing electrode 19
The portion facing the focusing electrode 20 is preferably circular.

In the present invention, a voltage lower than that of the first focusing electrode 17 and the third focusing electrode 19 is applied to the second focusing electrode 18 inserted as an auxiliary electrode to form a local unipotential lens. A similar effect can be obtained when the electrode 18 is connected and a fluorescent surface voltage is applied.

Furthermore, for special purposes, the electron gun of the present invention may be used in the case of an electron gun in which part of the aperture of the first electrode 15 and/or the second electrode is made non-circular in order to form a non-circular electron beam on a fluorescent surface. If used, the shape of the electron beam spot can be easily controlled.

As described above, the practical application of the present invention is extremely effective from an industrial standpoint.

In the above invention, the first focusing electrode 17 to the fourth focusing electrode 20 are all referred to as a focusing electrode, but it goes without saying that this includes both an accelerating electrode and a focusing electrode.

In addition, although each electrode, especially all integrated electrodes, is shown as a single press-formed piece,
It goes without saying that these techniques can be applied as they are even when each electrode is constructed from a plurality of plate-shaped and/or shallow cap-shaped collective electrodes.

[Brief explanation of the drawing]

FIG. 1 is an explanatory cross-sectional view showing an example of an electron gun having a general integrated structure, and FIG. 2 is a plan view showing the shape of a beam spot on a fluorescent surface when the electron gun of FIG. 1 is used. FIG. 3 is a sectional view schematically showing an embodiment of an in-line color picture tube electron gun of the present invention, and FIG. 4 is a plan view showing an opening of the second focusing electrode in FIG. 3. 9,14...Cathode, 8,15...First electrode, 7,1
6...Second electrode, 3,17...Second focusing electrode, 4,1
8... Second focusing electrode, 19... Third focusing electrode, 20...
Fourth focusing electrode.

Claims (1)

[Scope of Claims] 1. An electron beam generating section consisting of at least a cathode, a first electrode, and a second electrode, and a main lens section that mainly focuses the central and both side electron beams emitted from the electron beam generating section. In the in-line color picture tube electron gun, the main lens portion is made up of at least four spatially arranged electrodes: a first focusing electrode, a second focusing electrode, a third focusing electrode, and a fourth focusing electrode, and Approximately the same potential voltage of several KV is applied to the first focusing electrode and the third focusing electrode, and the opening portion through which the electron beams at the center and both sides of the second focusing electrode pass is It has an elongated elliptical shape in the direction perpendicular to the line connecting the centers of the beam apertures, and the longitudinal length of the central electron beam aperture is relatively longer than the longitudinal length of the side apertures. An in-line type color picture tube electron gun characterized in that the electron gun is long and has a different voltage applied to the first focusing electrode or the third focusing electrode. 2. Claim 1, characterized in that the potential of the second focusing electrode is approximately the same potential as the potential of the second electrode.
In-line type color picture tube electron gun as described in . 3. The in-line color picture tube electron gun according to claim 1, wherein the potential of the second focusing electrode is substantially the same as the potential of the fourth focusing electrode.