JPS60218744A - Electron gun for color picture tube - Google Patents

Abstract

PURPOSE:To obtain an electron gun which causes no convergence variation by installing the first lens which deflects two electron beams located on both sides of the tube axis toward it and the second lens which forms an asymmetrical lens for the deflected electron beams. CONSTITUTION:The centers of the openings of the first grid 21 to the fourth grid 24 through which electron beams (R) and (B) pass, are on the same axes which are called first axes 27. The centers 28 of the openings 25R and 25B of the fifth grid 25 facing the fourth grid 24 are located outside the first axes 27 and the axes of the centers 28 are called second axes 28. The centers of the openings 256R and 256B of the fifth grid 25 facing the sixth grid 26 are on the same axes as the centers of the openings 26R and 26B of the sixth grid 26 and these axes are called third axes 29. The third axes 29 are closer to the tube axis than the first axes 27. Owing to the above constitution, when focusing voltage changes, variation in the amount of deflection produced by the first lens is set off by the amount of delfection produced by the second lens.

Description

DETAILED DESCRIPTION OF THE INVENTION [Technical Field of the Invention] The present invention relates to an electron gun assembly, and particularly relates to an improvement of an electron gun assembly having a plurality of electron lenses.

[Technical background of the invention and its problems]

For example, a color-picture tube electron gun assembly [phase] having an in-line integrated structure has a heater (1) as shown in FIG.
), each having an integrally formed first cathode (2);
Grid (3), 2nd grid (4), 3rd grid (
5), the fourth grid (6), and the main electron lens (7).
) is the gun axis (Zo) of the central electron gun and the gun axis (Zm) of the electron guns on both sides at the bottom of the bottomed cylinder that is mechanically integrally formed.
Opening (5m) drilled around (Zm) - (
5 o) - (5 m);
Similarly, an opening (
6G) and an opening (6m), (6m) eccentrically drilled with respect to the gun axis (Zm) - (j%) of the electron gun on both sides.
is formed between. In this case, since the central electron gun has openings (5G) and (6G) centered around the gun axis (Zo), the electron beam (8G) will proceed straight toward the screen (not shown). , in the double-sided electron gun, the electric field is asymmetrical due to eccentricity or inclination, so the electron beam passing through this electric field (sm), (sm)
is bent in the direction of the electron beam (8°), and these three electron beams (8o)'', (8m), and (8m) coincide on the screen (':1 impurity). The amount of eccentricity mentioned above is about 0.15 mm.

As mentioned above, one electron gun having the above structure is called an in-line integrated structure electron gun structure, and has eccentric openings □ to concentrate at least three electron beams on the screen. It is necessary to use it.

Of course, if there is a device other than the eccentric aperture that can correct and deflect the electron beams on both sides in a predetermined manner, other methods, such as a method of tilting the electrodes, may be used.

The integrated structure electron gun structure is preferable in terms of cost and accuracy because the structure of each electrode is mechanically simple and the relative position of each electron lens of the three electron guns can be accurately determined. On the other hand, deficiencies that need to be improved have also been pointed out. In other words, an eccentric or inclined aperture is used to concentrate the "three" electron beams onto the screen.The amount of deflection of the electron beam by this eccentric or inclined aperture is Since the amount of eccentricity or inclination is approximately proportional to the potential difference between the electrodes forming the electron lens, the intended purpose cannot be achieved unless at least the potential difference between the electrodes forming the electron lens is accurate.

That is, the deflection angle (amount) by the asymmetric electron lens is approximately given by the following equation.

19=ni-p-q ・・・・・・・・・・・・・・・・
(1) Here, θ is the deflection angle, is a constant, p is the eccentricity that normalizes the electron lens diameter, and q is the voltage ratio of the electron lens.

Therefore, if the voltage applied between the electrodes is inaccurate, the deflection angle 0 changes, resulting in a problem that the static convergence of the color picture tube shifts.

In particular, recent color picture tubes are of the preset type, in which the picture tube undergoes final adjustment before being installed in the receiver, and no adjustment is made after it is installed in the receiver. Especially when the potential difference between the electrodes forming the electron lens requires precision, if the electron gun operating conditions, especially the voltage applied to the third grid (5), are inaccurate during adjustment of the picture tube, the picture tube You will have to re-adjust it after installing it.

The adjustment of the picture tube is, for example, by adjusting the magnetic field strength of a permanent magnet attached to the outer wall of the picture tube neck, as shown in Japanese Patent Publication No. 51-45936.
Re-adjustment means to re-adjust the vIA of this permanent magnet.

As another example, as shown in Japanese Patent Application Laid-Open No. 122322/1982, a permanent magnetic material is attached inside the neck of the color picture tube, that is, around the electron gun, and this is properly magnetized from the outside. A method has been proposed in which the electron beam is accurately aligned on the screen, but with this method, it is completely impossible to readjust the image, at least during the assembly process of the receiver.

As described above, the conventional Uniquiz electron gun has the disadvantage that if the operating conditions of the electron gun are changed, even if it has been adjusted in advance, it must be readjusted.

Several proposals have been made to address the problem of such changes in the focused electric field.

For example, in Japanese Patent Application Laid-Open No. 55-53853, the openings of both the first lens and the second lens are decentered.
An example is shown in which two asymmetric lenses deflect the electron beams on both sides and align them on the screen. However, in this structure, the electron beam deflected by the first lens passes inside the second lens, that is, on the tube axis side, and is subjected to Comis aberration by the second lens.

As a result, there is a problem in that the double-sided electron beam produces a halo in the lateral direction.

Furthermore, Japanese Patent Application Laid-Open No. 55-37798 discloses an electron gun that is constructed from a first asymmetric lens and a second asymmetric lens. In this example, the electron beam deflected by the first lens obliquely enters approximately the center of the second lens, but the opening of the counter electrode forming the second lens is also decentered. Therefore, the electrode structure becomes complicated and the number of types of electrodes increases. Therefore, it is extremely difficult to assemble each electrode of the electron gun with high precision, and the resolution may deteriorate.

[Object of the invention-]

The present invention has been made in view of the drawbacks of the conventional electron gun assembly for color picture tubes, and an object of the present invention is to provide an electron gun assembly that does not require readjustment even after the picture tube is attached to a picture receiver. .

[Summary of the invention]

The present invention was made by considering lenses that act on the electron beams on both sides among a plurality of lenses arranged on the axis.The first lens near the cathode deflects the electron beams on both sides in the direction of the tube axis. It is an asymmetric lens that has the effect of This first asymmetric lens allows the double-sided electron beams to substantially coincide with the central electron beam on the screen. Next, a second lens located closer to the screen than the first lens.
lens is placed on the trajectory of the double-sided electron beam which is already deflected and tilted by the first lens.

With such a lens arrangement, the amount of deflection when the focusing voltage changes is substantially reduced by the amount of deflection caused by the first asymmetric lens and the amount of deflection caused by the lenses located on the inclined trajectory of the double-sided electron beam. It can be an electron gun that does not change on the screen.

[Embodiments of the invention]

Examples of the present invention will be described in detail below.

FIG. 9J2 is a schematic diagram showing an embodiment of the electron gun for a picture tube according to the present invention. In Figure 2, cathode (Km) -
(Ko) - (Km), 1st grid (2D, 2nd grid (2), 3rd grid (to), 4th grid (foundation), 5th grid (c) and 6th grid (c) in sequence It is located.

And each cathode has about 150cm, the first grid C! υ is grounded, the 2nd grid (2) and 4th grid (2) are held at the same potential inside the tube, and the voltage is approximately 600V, and the 3rd grid (to) and the 5th grid (c) are held at the same potential inside the tube. Been 7
8Kv for mushrooms, about 25i for gJ & 6 grid (c)
CV anode high voltages are respectively applied. Now, each grid has an opening through which the central electron beam (G) passes, and openings through which both side electron beams (R) and (B) pass. The center of the aperture through which the central electron beam (G) passes is the first grid C! From Chin to 6th grid (to)
It is on the same axis up to and substantially coincides with the tube axis. On the other hand, the centers of the apertures through which the electron beams (R) and (G) pass are on the same axis from the first grid υ to the fourth grid, and this is defined as the first axis (■).

The center (c) of the openings (25R) and (25B) facing the fourth grid (c) of the fifth grid (c) is eccentric to the outside of the axis (c) of gate 1. axis (
c). Next, the 6th grid (c) of the 5th grid (c)
opening (256R), (256B) facing
The center is the opening (26R) of the 6th grid (a),
It is on the same axis as the center of (26B), and this is defined as the third axis 4. The third axis (c) is located closer to the tube axis than the first axis (5). In an electron gun with such a configuration, between the fourth grid (2) and the fifth grid (c),
An asymmetric lens having the function of deflecting the electron beam in the direction of the tube axis is obtained by the tenth axis gradient and the eccentricity of the second axis (end). The angle deflected by this asymmetric lens is (
1) It can be determined from Eq. The first asymmetric lens is configured so that the deflected electron beams on both sides substantially coincide with the central electron beam at the center of the screen. Next, the lens formed between the fifth grid (c) and the sixth grid (c), that is, the third axis of the main lens, allows the electron beams on both sides deflected by the first lens to move toward the first axis (2). ) is shifted toward the tube axis by an amount that is further away from the tube. That is, the electron beams on both sides pass through the center of the main lens obliquely. This condition is when the focusing voltage is centered at the set value. Next, the effects of the lens and electron beam on fluctuations in focusing voltage will be explained with reference to FIG. In Fig. 3, from the left end, the first axis (5), the second axis (2), the third axis, and the central electron beam axis (G), that is, the tube axis and the center part of the screen (0) towards the right end. It is shown. The first asymmetric lens (
L,) is formed. In addition, a second lens (L, ), which is a main lens, is located closer to the screen than the first lens (L, ).
) is formed. Now, at a certain focusing voltage vt, the electron beams (R) on both sides are moved by θ1 by the first lens (L, ).
The light beam is deflected by a distance of 1.5 mm, and is incident obliquely into the center of the second lens (Lt) at a distance corresponding to the length of the fifth grid in the tube axis direction. In this state, the electron beams on both sides pass through the center of the second lens, go straight, reach the center (0) of the screen, and match the center electron beam.

Next, when the focusing voltage is lowered by (vl - ΔvI) and Δvf, the first lens
Therefore, the deflection angle θ becomes smaller by (θ, −Δθ1) and Δθ. Therefore, the electron beam (R) travels along the trajectory (R) and is incident on the upper point (A) in FIG. 3 with respect to the center of the second lens. If the electron beam continues straight without being affected by the second lens, it will reach point (A) on the plane. However, since the electron beam is incident on the upper side of the second lens when viewed from the center of the lens, it is inevitably deflected toward the center of the screen (0), resulting in a converged state. becomes.

When the focusing voltage increases by (vr + Δ■,) and Δ■-, the electron beam is incident on the lower side of the second lens in the figure, contrary to the above, and is similarly deflected to the center of the Al1-on (0). be influenced to do so. Here, the opposing openings constituting the second lens are not decentered, that is, they are on the same axis parallel to the tube axis, and the lens itself is considered to be a symmetrical lens.

However, since the electron beam is incident on this second lens at an angle, the second lens viewed from the electron beam is regarded as an inclined asymmetric lens unless it passes through its center. ' □ As is clear from the above explanation, in this embodiment, when the focusing voltages applied to the third and fifth grids vary from the center setting value, the deflection amount by the first lens increases or decreases. The angle of incidence of the electron beams on both sides entering the second lens and the amount of deflection caused by the change in the position of incidence act so as to cancel each other out in opposite directions. Therefore, even if the focusing voltage varies, the convergence on the screen remains substantially unchanged.

In addition, the third axis, that is, the opposing openings of the electrodes constituting the second lens are not eccentric, but are on the same axis parallel to the tube axis, and both electrons deflected by the first lens The beam is set to pass through the center of the second lens. Therefore, the coma aberration caused by the second lens for both electron beams is extremely small, and substantially no distortion occurs on the screen. Furthermore, since the third shaft is not eccentric, the structure is relatively simple, allowing for highly accurate assembly and suitable for mass production.

Next, a specific design example will be described in which the electron gun of the embodiment shown in FIGS. 2 and 3 is applied to a four-inch color picture tube with a neck diameter of 29.1111 mm. 4th grid of 3rd grid
The diameter of the opening from the opening between the grids to the sixth grid is approximately 5.5 mm. The distance between the first axis and the tube axis is approximately 6.831 Tx, and the diameter of the opening between the pair of grids is approximately 5.5 mm. The amount of eccentricity with respect to the axis of 1 is approximately 0.11+s+.

Further, the voltages applied to the fourth grid and the fifth grid are 600 volts and 7 kV, respectively. In this state, the angle at which both electron beams are deflected by the first asymmetric lens is (1
) formula, it is approximately 1.04 degrees. The length of the fifth grid, or L, is approximately 12. Os+m, and the distance between the axis of 's3 and the tube axis is approximately (5.5 mrx).

FIG. 4 shows the relationship between the focusing voltage and static convergence of such an electron gun. In FIG. 4, the horizontal axis shows the variation of the focusing voltage, the vertical axis shows the deviation amount of the state-coupled vergence, and the zero point on the vertical axis shows the case where three electron beams coincide. Characteristic (a) is the convergence characteristic of the conventional electron gun shown in Fig. 1, and characteristic (b) is
1 and 2 respectively show the convergence characteristics of the electron gun according to the embodiment of the present invention. As is clear from FIG. 4, in the conventional electron gun, the convergence changes by about 0.4 per 500 V in the focusing voltage, whereas in the electron gun according to the embodiment of the present invention, the convergence changes by about 0.4 volts per 500 V change in the focusing voltage. 500v
The amount of change in convergence with respect to the change in convergence is only about 0.1, which is a substantially negligible amount of deviation considering that the actual variation in focusing voltage is much smaller than this. In general, the allowable value for the deviation amount of static convergence is Q, 3 mm or less, and it can be said that the electron gun to which the present invention is applied has no practical problems at all, and there is no need for readjustment even in response to fluctuations in the focusing voltage. .

FIG. 5 shows another embodiment in which the present invention is applied to a pi-potential type electron gun, and parts corresponding to those in FIG. 2 are designated by the same numbers.

In this embodiment, the first asymmetric lens has an aperture whose central axis is not decentered, and is formed by tilting the opposing surfaces. That is, the inclination of the opposing surface, the oblique angle α, corresponds to the amount of eccentricity in the embodiment of FIG. 2, and by optimally designing this inclination angle, the same effects as in the embodiment of FIG. 2 can be obtained.

〔Effect of the invention〕

As described above, according to the present invention, even if the focusing voltage fluctuates, convergence fluctuations on the screen can be substantially ignored, and the voltage applied to the electrodes forming the electron lens can have a large margin. Since it is possible to do this, there is no need for readjustment, and high-precision assembly can be performed relatively easily, so its industrial value is great.

[Brief explanation of the drawing]

FIG. 1 is a schematic configuration diagram showing an example of a conventional electron gun, FIG. 2 is a schematic configuration diagram showing an embodiment of an electron gun to which the present invention is applied, and FIG. 3 is an electron beam of the electron gun of FIG. 2. FIG. 4 is a characteristic diagram showing the amount of convergence shift with respect to fluctuations in the focusing voltage, and FIG. 5 is a schematic diagram showing another embodiment of the present invention. Q... 1st grid (2)... 2nd grid (c)... 3rd grid @... 4th grid (c)
...5th Grid (c)...6th Grid (Foundation)...
...First axis (c)...Second axis...Third axis Agent Patent attorney Noriyuki Chika (and 1 other person) Figure 1 Figure 8

Claims (1)

[Scope of Claims] 1) Consisting of at least a cathode and a plurality of electrodes, each of the plurality of electrodes having an electron beam passage hole in one row through which three electron beams pass; In an electron gun for a color picture tube, the electron gun has a central electron beam that substantially coincides with the tube axis, and an electron lens that focuses both side electron beams onto a target, wherein the electron lens includes a plurality of electron lenses arranged from the cathode side toward the target. The plurality of electron lenses include a first lens that is an asymmetric lens having the function of deflecting the double-sided electron beams toward the tube axis, and a first lens that is located on the trajectory of the deflected double-sided electron beams. 1. An electron gun for a color picture tube, comprising at least a second lens forming an asymmetric lens group for a deflected electron beam on both sides. 2) The second lens is an asymmetric lens that causes the electron beams on both sides deflected by the first lens to act in a converging direction when they are under-concentrated with respect to the central electron beam, and in a diverging direction when they are over-concentrated. An electron gun for a color picture tube according to claim 1, characterized in that: 3) The plurality of electrodes consist of a first grid to a sixth grid, and the electron beam passing hole corresponding to the center electron beam of the first grid to the sixth grid,
The axis is substantially coaxial with the tube axis, and the axis of the electron beam passage hole corresponding to the two-sided electron beam ζ2 is a first axis coaxial with the first grid to the fourth grid. , a second axis that is an axis of the electron beam passage hole of the fifth grid facing the fourth grid and eccentric in a direction away from the tube axis with respect to the first axis; An axis consisting of electronic vinyl passing holes in each of the fifth grid facing the fifth grid and the sixth grid facing the fifth grid, parallel to the tube axis and on the tube axis side with respect to the first axis. 3. An electron gun for a color picture tube according to claim 2, characterized in that the third glaze is eccentric. 4) The second grid and the jl! The fourth grid is connected within the tube and a low potential is applied to it, the third grid and the fifth grid are connected within the tube and a medium potential of a focused voltage higher than the low potential is applied, and the sixth grid is connected to the 4. The electron gun for a color picture tube according to claim 3, wherein a high potential with an accelerating voltage higher than a medium potential is applied. 5) The first lens is formed so that planes corresponding to the electron beams on both sides and including opposing electron beam passage holes of the fourth grid and the fifth grid are inclined with respect to a plane perpendicular to the tube axis. - An electron gun for a color picture tube according to claim 4, characterized in that: - an electron gun for a color picture tube;