JPH0427655B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION Field of the Invention The present invention relates to an in-line electron gun for a color picture tube.

Conventional Structure and Problems Generally, in a color picture tube equipped with an in-line electron gun in which three electron beam emission ports are arranged in a straight line, a center beam 1a and both side beams are used as shown in FIG. 1b and 1c pass through the respective main lenses 2a, 2b and 2c, where they are subjected to a focusing action. And both side beams 1
b, 1c are concentrated at a central point 3 on the phosphor screen surface together with the center beam 1a.
Both side beams 1b, 1c and center beam 1a
A beam concentration angle θ is given between . In addition, the deflection magnetic field is a self-convergence magnetic field,
center beam 1a and both side beams 1b,
1c is constructed so that the beam is concentrated at a single point even in areas other than the central point 3 on the phosphor screen surface, and the set beam concentration angle θ is such that the beam is concentrated in the entire area on the phosphor screen surface. Affect properties.

To set the beam concentration angle θ, there is a method of arranging three electron guns at an angle, but this method causes variations in the beam concentration angle θ due to assembly errors when integrating three independent electron guns. tends to occur.
Therefore, an integrally formed electron gun as shown in FIG. 2 is usually employed. The integrated type electron gun is made by Tokukosho.
52-4905, etc., both side beam holes 5 of the beam holes 5a, 5b, 5c on the end surface of the focusing electrode 4 on the final acceleration electrode side.
b, 5c, and beam holes 8a, 8 at the end surface of the final acceleration electrode 7 on the focusing electrode side.
By making the center axes 9b, 9c of both side beam holes 8b, 8c of the two side beam holes 8b, 8c eccentric, respectively, and obtaining the axis-asymmetric main lenses 10b, 10c, both sides are Deflect the beam electrostatically.

Incidentally, in such an integrated type electron gun, the eccentricity for giving the beam concentration angle θ is determined by the eccentricity between the two side beam holes 5b and 5c of the focusing electrode 4 and the both side beam holes 8b and 8c of the final accelerating electrode 7. Therefore, very strict machining accuracy is required for both electrodes 4 and 7.

OBJECTS OF THE INVENTION It is an object of the present invention to provide an integrated in-line electron gun that does not require eccentricity of the central axis as described above between both side beam holes of the focusing electrode and both side beam holes of the final acceleration electrode. There is a particular thing.

Structure of the Invention According to the present invention, a protruding region protruding toward the accelerating electrode is provided at the center of the end surface of the focusing electrode on the accelerating electrode side, a center beam hole is provided in the protruding region, and a center beam hole is formed in the protruding region, and a center beam hole is provided on both sides avoiding the protruding region. A side beam hole is provided respectively, and the prefocus lens electric field on both sides is made axially asymmetrical by the wall electric field of the protrusion region, and a central axis common to each side beam hole at the mutually opposing end surfaces of the focusing electrode and the final acceleration electrode is formed. , the side beam holes of the control electrode and the acceleration electrode are eccentrically centered toward the tube axis with respect to the common central axis of each side beam hole, and this will be described in detail below with reference to embodiments shown in the drawings.

DESCRIPTION OF EMBODIMENTS In FIG. 3, three
cathodes 11a, 11b, 11c. control electrode 12,
The accelerating electrode 13, the focusing electrode 14, and the final accelerating electrode 15 constitute an integrated in-line electron gun, and the center beam hole 16a of the control electrode 12
The side beam holes 16b, 16c have central axes 18a, 18b, 18c common to the center beam hole 17a and both side beam holes 17b, 17c of the accelerating electrode 13, respectively, and are common to both the center beam holes 16a, 17a. The central axis 18a of is on the tube axis 19.

Further, at the center of the acceleration electrode side end surface of the focusing electrode 14, a protruding length h and a width W protruding toward the accelerating electrode 13 side are provided.
A circular or rectangular protruding area 14a is formed, and a center beam hole 20a is formed in the protruding area 14a.
However, both side beam holes 20a and 20c are provided on both sides avoiding the protruding region 14a, respectively. Moreover, these beam holes 20a, 20b,
Each central axis of 20c is connected to the aforementioned common central axis 18.
a, 18b, and 18c, respectively.

On the other hand, the center beam hole 22a and side beam holes 22a, 22c on the final acceleration electrode side end surface of the focusing electrode 14 are common to the center beam hole 23a and side beam holes 23b, 23c on the focusing electrode side end surface of the final acceleration electrode 15, respectively. It has central axes 24a, 24b, 24c,
The central axis 24a common to both center beam holes 22a, 23a is on the tube axis 19, but the central axis 24b, 24c common to the side beam holes 22b, 22c, 23b, 23c, respectively, is on the common central axis 18b. , 18c toward the tube axis side.

In the in-line electron gun configured in this manner, a curved lens electric field 25 as a whole is generated between the accelerating electrode 13 and the focusing electrode 14, as shown in FIG. That is, while a strong axially symmetrical prefocus lens electric field 25a is generated between the center beam hole 17a of the accelerating electrode 13 and the center beam hole 20a of the focusing electrode 14, the accelerating electrode 1
3 side beam holes 17b, 17c and focusing electrode 1
Prefocus lens electric fields 25b and 25c, which are axially asymmetrical, are generated between the side beam holes 20b and 20c of No. 4 due to the wall electric field of the protrusion region 14a.

Therefore, three cathodes 11a, 11b, 11c
and the center beam hole 16a and side beam holes 16b, 16c of the control electrode 12.
The three electron beams that have passed through are pre-focused by the pre-focus lens electric field 25, but the pre-focus lens electric fields 25 on both sides
b and 25c are axially asymmetrical, so both side beams are slightly deflected toward the tube axis.

In FIG. 5, three prefocus lens parts are shown as equivalent electron sources 26a, 26b, and 26c, and the equivalent electron sources 26b and 26c on both sides are as follows.
They are each offset by Δx from the aforementioned common central axes 24b and 24c. The center beam 27a travels straight on the tube axis 19 and enters the axially symmetrical center main lens 28a on the tube axis 19, while the side beams 27b and 27c advance at an angle of α. Side main lens 28b, 2
Inject into 8c.

Center beam 27a and both side beams 2
7b, 27c are main lenses 28a, 28b,
28c, and when no deflection magnetic field acts, both side beams 27b, 2
7c is on the phosphor screen surface 29, and the center axis 24
From b and 24c, deviate by Δx·M. however,
Here, M indicates lens magnification.

Therefore, the eccentricity Δx is set so that the eccentricity (Δx・M) is equal to the distance S between the central axes 24b, 24c and the tube axis 19 (Δx・M=S). The center beam 27a and both side beams 27b, 27c are connected to the phosphor screen surface 2.
It can be concentrated at one point in the center on 9.

Pre-focus lens electric field 25b on both sides,
25c and both side beams 27b, 27c are each axially asymmetric, but by appropriately setting the protruding length h and width W of the protruding region 14a, an appropriate inclination angle α can be achieved.
By giving this, the beam spot (bright spot) on the phosphor screen surface 29 can be made close to a perfect circle. Furthermore, the amount of eccentricity created between the accelerating electrode and the focusing electrode to which a relatively low voltage is applied is smaller than the amount of eccentricity created between the high voltage electrodes in the conventional case. All lenses are axially symmetrical. Furthermore, since there is no need to eccentricize the beam hole center axis between the opposing end surfaces of the focusing electrode 14 and the final accelerating electrode 15, the final accelerating electrode side half of the focusing electrode 14 and the final accelerating electrode 15 are pressed together in the same press. It becomes possible to form with a mold, and it is possible to reduce convergence defects caused by variations in the shapes of both electrodes 14 and 15. moreover,
Even if the roundness of the beam hole cannot be obtained satisfactorily due to the peculiarities of the press mold, both electrodes 14,1
By combining the mutually opposing end surfaces of No. 5 in an upside-down relationship, at least the left-right symmetry of beam focusing can be made good, and a good beam spot can be obtained.

In another electron gun according to the present invention shown in FIG. 6, protrusions 30a and 30b protruding toward the focusing electrode 14 are provided on both sides of the accelerating electrode 13. With this configuration, the necessary prefocus lens electric field 25 can be obtained without increasing the protrusion length h of the protrusion region 14a too much.

Effects of the Invention Since the in-line electron gun of the present invention is constructed as described above, it is easy to manufacture, manage, and assemble the focusing electrode and the final accelerating electrode, which are relatively complicated, and a good beam spot shape can be achieved. Resolution characteristics can be obtained.

[Brief explanation of drawings]

Fig. 1 is a diagram for explaining the concentration of three electron beams by a conventional in-line electron gun, Fig. 2 is a side sectional view showing the electrode configuration of a part of the electron gun, and Fig.
The figure is a side sectional view of an in-line electron gun embodying the present invention, Figure 4 is a diagram for explaining the prefocus lens electric field of the electron gun, and Figure 5 is a diagram showing the concentration of three electron beams by the electron gun. Diagram for explanation, No. 6
The figure is a side sectional view of a main part of another embodiment of the present invention. 12...control electrode, 13...acceleration electrode, 14...
...Focusing electrode, 14a...Protrusion region, 15...Final acceleration electrode, 16b, 16c, 17b, 17c, 2
0b, 20c, 22b, 22c, 23b, 23c
...Side beam hole.

Claims (1)

[Claims] 1. A protruding region protruding toward the accelerating electrode is provided in the center of the end surface of the focusing electrode on the accelerating electrode side, a center beam hole is provided in the protruding region, and side beam holes are provided on both sides avoiding the protruding region,
The prefocus lens electric field on both sides is made axially asymmetrical by the wall electric field of the protruding region, and the central axis common to each side beam hole on the mutually opposing end surfaces of the focusing electrode and the final acceleration electrode is set to the control electrode and the acceleration electrode. An in-line electron gun characterized by being eccentric to the tube axis side from a common central axis of each side beam hole.