JP2602254B2 - Color picture tube - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to the shape of an electrode constituting a main lens of an electron gun for a color picture tube.

FIG. 2 is a longitudinal sectional view of a color picture tube provided with an electron gun having a conventional structure. On the inner wall of the face plate portion 2 of the glass envelope 1, a phosphor screen 3 on which phosphors of three colors are alternately applied in a stripe shape is supported. The central axis of the cathodes 6, 7, 8 15,
16, 17 are G1 electrodes 9, G2 electrodes 10, focusing electrodes that constitute the main lens
11 and the shielding cup 13 are arranged substantially in parallel with each other on a common plane so as to coincide with the central axes of the openings corresponding to the respective cathodes. The central axis of the central aperture of the accelerating electrode 12, which is the other electrode constituting the main lens, coincides with the central axis 16, but the central axes 18, 19 of both outer apertures.
Are slightly displaced outward without coincidence with the corresponding central axes 15, 17. Three electron beams emitted from each cathode enter the main lens along the central axes 15, 16, and 17. A focusing voltage of about 5 to 10 KV is applied to the focusing electrode 11, an acceleration voltage of about 20 to 30 KV is applied to the accelerating electrode 12, and the shielding cup 13, the conductive film 5 provided inside the glass envelope, They are at the same potential.

Since the aperture at the center of the focusing and accelerating electrodes is coaxial, the main lens formed at the center is axisymmetric, and the central beam is focused by the main lens and then follows the trajectory along the axis. Go straight. On the other hand, since the apertures on the outside of the two electrodes are off-axis from each other, a non-axisymmetric main lens is formed on the outside. For this reason, the outer beam is included in the main lens area.
In the diverging lens area formed on the accelerating electrode side, the light passes through a portion deviated from the center axis of the lens in the central beam direction, and receives a converging force in the central beam direction simultaneously with the converging action of the main lens. In this way, the three electron beams are focused on the shadow mask 4 so as to form an image and overlap with each other. The operation of concentrating each beam in this manner is called static convergence (hereinafter abbreviated as STC). Further, each electron beam is subjected to color selection by a shadow mask, and only a component that excites and emits a phosphor of a color corresponding to each beam passes through the aperture of the shadow mask and reaches the phosphor screen. An external magnetic deflection yoke 14 is provided for scanning the electron beam on the phosphor screen.

By combining an in-line electron gun in which three electron beam paths are arranged on a horizontal plane as described above and a so-called self-convergence deflection yoke that forms a special asymmetric-magnetic field distribution, STC can be obtained at the center of the screen. If you have
It is known that convergence can be achieved over other screens. However, in general, the self-convergence deflection yoke has a problem that the deflection aberration is large due to the non-uniformity of the magnetic field, and the resolution is reduced at the peripheral portion of the screen. FIG. 3 schematically shows how the electromagnetic beam spot is deformed by deflection aberration. That is, in the peripheral portion of the screen, the high-luminance portion (core) of the electron beam indicated by oblique lines extends in the horizontal direction, and the low-luminance portion (halo) extends in the vertical direction.

Japanese Patent Laid-Open No. 61-99249 discloses one means for solving this problem. FIG. 4 shows an example of the structure of an electron gun according to this conventional example. The focusing electrode is divided into a first member 114 and a second member 115 from the cathode toward the phosphor screen. First member 114
On the end face facing the second member 115, a slit which is long in the vertical direction is provided as shown in FIG. 4 (b). On the end face of the second member 115 facing the first member, a slit-like opening long in the horizontal direction is provided as shown in FIG. 4 (c), so as to synchronize with the deflection current supplied to the deflection yoke. voltage that varies in Dainamitsuku, i.e. Dainamitsuku voltage is applied is superimposed on the focusing voltage V _f. When the amount of deflection is large, the potential difference between the first member 114 and the second member 115 increases, so that the intensity of the quadrupole lens formed by the slit increases, causing large astigmatism in the electron beam spot. If the potential of the second member 115 is higher than the potentials of the first and third members, the astigmatism generated in the electron beam has the effect of extending the core in the vertical direction and extending the halo in the horizontal direction. Can eliminate the astigmatism caused by the electron beam deflection shown in (1), and can improve the resolution at the peripheral portion of the screen. On the other hand, when the electron beam is not deflected, by eliminating the potential difference between the first member and the second member so that an asymmetric lens is not formed and the condition that astigmatism does not occur at the center of the screen can be achieved, so that the resolution is deteriorated. Does not occur.

Also, in the color picture tube, the distance from the main lens to the periphery of the screen is longer than the distance to the center of the screen, so the electron beam focusing conditions differ between the center and the periphery.
When the electron beam is focused at the central portion, there is a problem that the resolution is deteriorated because the electron beam is not focused at the peripheral portion. But the fourth
In the conventional example shown in the figure, when the electron beam is deflected to the periphery of the screen, the potential of the second member 114 is increased, so that the voltage difference from the acceleration voltage of the acceleration electrode 12 is reduced, and the lens strength of the main lens is weakened. For this reason, the electron beam focusing point is extended in the screen direction, and the electron beam can be focused on the screen even at the peripheral portion of the screen, so that the degradation of the peripheral portion resolution can be prevented at this point. That is, dynamic astigmatism correction,
Dynamic focus can be realized at the same time.

FIG. 5 shows another embodiment disclosed in JP-A-61-250934. As in the embodiment shown in FIG.
Divide into two parts. As shown in FIGS. 5 (b) and (c), the plate-like correction electrodes in the vertical direction and the horizontal direction are arranged on the opposing surfaces of each member so as to be combined with each other to form a quadrupole lens. The second member 117 applies a Dainamitsuku voltage V _d which is superimposed on the focusing voltage V _f, to realize the astigmatism correction and Dyna honey click Fuo dregs of Dainamitsuku simultaneously.

[Problems to be solved by the invention]

The above prior art has a problem that extremely high precision is required for the production of electron gun parts and the assembly of electron guns.
That is, in the conventional examples shown in FIGS. 4 and 5, when the vertical and horizontal slits or the vertical and horizontal plate-like correction electrodes are combined with each other, even if they slightly deviate from desired positions, the electron beam is not corrected when astigmatism is corrected. An uneven force acts on the screen, distorting spots on the screen.

SUMMARY OF THE INVENTION It is an object of the present invention to provide an electron gun structure that can simultaneously achieve dynamic astigmatism correction and dynamic focus, and does not require as high precision as before in component manufacturing and assembly.

[Means for solving the problem]

In the prior art, parts and assembling accuracy have to be increased because of the necessity of accurately combining two kinds of electrodes having different structures. Thus, the first member of the G3 electrode only has a single large opening on the surface facing the second member, and the structure for forming the quadrupole lens is the second member.
Only the plate-shaped correction electrode is disposed above and below the electron beam passage hole on the surface of the member facing the first member, and extends into the first member through the opening.

[Action]

In the above-described electrode structure according to the present invention, the electrode structure is arranged near the first and second member facing surfaces and close to the electron beam. There is no electrode portion belonging to the first member. Therefore,
1. When assembling the second members, high positional accuracy is not required with respect to each other.

〔Example〕

FIG. 1 shows an embodiment of the present invention. The focusing electrode is divided into a first member 111 and a second member 112, and the first member is provided with a single horizontally long opening. The second member 112 is provided with three circular electron beam passage holes on the end surface facing the first member, and a flat correction electrode 11 extending in the first member direction above and below the passage holes.
Connect 3.

A constant focusing voltage _Vf is applied to the first member 111 and the second member 112
Applying a Dainamitsuku voltage V _d is superimposed on the V _f in. When the electron beam is deflected, V
raise _d . As _Vd increases, the strength of the quadrupole lens formed at the opposing portion of the first member 111 and the second member 112 increases, and astigmatism due to electron beam deflection can be corrected. At the same time, the reduction of the voltage difference between the accelerating voltage _Eb of the accelerating electrode 12 and the voltage applied to the second member 112 reduces the strength of the main lens and increases the distance between the main lens and the electron beam focusing point. Therefore, the electron beam can be focused even at the peripheral portion of the screen.

That is, dynamic astigmatism correction and dynamic focus can be performed simultaneously.

In the electrode structure shown in FIG. 1, the first member 111 is not close to the electron beam path near the quadrupole lens portion, that is, in the vicinity of the portion facing the second member 112. Therefore, even if the desired position of the first member with respect to the second member is slightly shifted from the second member, the characteristics of the quadrupole lens are not significantly affected, so that high precision is not required for electrode assembly.

FIG. 6 shows the results obtained by analyzing the astigmatism correction and the dynamic focus characteristics of the embodiment of FIG. The analysis conditions are as follows.

Acceleration voltage _Eb : 25 KV Focusing voltage _Vf : 6 KV Distance between main lens and center of screen: 340 mm Extension amount of flat correction electrode 113 in the direction of first member 111: 2.0, 3.0 m
m astigmatism correction characteristic represents a value of the astigmatism voltage [Delta] V _f, shown in solid lines in Figure 6. ΔV _f is a value obtained by subtracting the value of the focusing voltage capable of eliminating the horizontal halo from the value of the focusing voltage capable of eliminating the vertical halo of the electron beam spot at the center of the picture tube of the picture tube. When Dainamitsuku voltage V _d is 0, quadrupole lens is not formed, the [Delta] V _f because the screen center astigmatism does not occur 0
Becomes Quadrupole lens strength increases astigmatism with increasing V _d is increased. If ΔV _f is a positive value, astigmatism occurs such that the core of the electron beam is elongated in the longitudinal direction, and thus cancels out the astigmatism due to deflection shown in FIG. When the Dainamitsuku voltage 1KV is applied, when l is 3.0 mm, the astigmatism of about -3KV value of [Delta] V _f is the [Delta] V _f to correct astigmatism -1.9KV when l is 2.0mm Can be.

Dyna Mitsu click Fuo Kas characteristics, represented by the value of Dyna honey click Fuo Kas voltage V _df indicated by the dashed line in Figure 6. Since V _df is increased almost in proportion to the dynamic voltage V _d , it can be seen that dynamic focus can be performed simultaneously with astigmatism correction.

7 and 8 show another embodiment of the present invention. A problem with the embodiment shown in FIG.
Since the dipole lens gives different effects, the electron beam spot on the screen is distorted, and the convergence is also adversely affected. This is because the influence of the side wall of the first member 111 on the side of the electrode side wall of the outer electron beam is strongly affected, while the influence on the side of the center beam is weak.

Therefore, in order to solve the above problem, the correction electrode
The shape of 113 may be changed to shield the influence of the side wall of the first member 111. In the embodiment of FIG. 7, both ends of the correction electrode 113 'are bent to reduce the influence of the side wall of the first member 111. In the embodiment shown in FIG. 8, the parts arranged above and below the electron beam passage hole of the correction electrode 113 "are connected to form an integral part, and the connection part is curved into a concave shape as shown in FIG. As in the embodiment of FIG. 7, the influence of the side wall of the first member 111 is reduced.

In the above embodiment, the electron gun main lens is composed of two electrodes. It targets only the so-called Bi-Potential Focusing (Bi-Potential Focusing) lens, that is, the BPF lens, but it is composed of three electrodes.
The present invention can be applied to a focusing electrode of an ial focusing (UPF) lens, and can also be applied to a multistage main lens obtained by combining these lenses.

〔The invention's effect〕

According to the present invention, in a color picture tube, correction of astigmatism caused by electron beam deflection and dynamic focus can be realized at the same time, so that the resolution at the peripheral portion of the screen is greatly improved. At this time, since high accuracy required for an electron gun for performing astigmatism correction for a conventional electron gun assembly is not required, an increase in manufacturing cost can be prevented.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view of an electron gun according to one embodiment of the present invention,
FIG. 2 is a longitudinal sectional view of a color picture tube provided with a conventional electron gun, FIG. 3 is a schematic view of an electron beam spot shape of each part of a color picture tube screen by a conventional electron gun, FIG. 5 and 5 are a longitudinal sectional view and a plan view of main parts of a conventional electron gun, FIG. 6 is a graph showing the analysis results of the electron gun characteristics of the embodiment of the present invention, and FIG. 7 is another graph of the present invention. FIG. 8 is a plan view and a side view of a main part of an electron gun according to another embodiment of the present invention. 1 ... glass envelope, 2 ... face plate, 3 ...
Fluorescent screen, 4 ... shadow mask, 5 ... conductive film, 6, 7, 8
… Cathode, 9… G1 electrode, 10… G2 electrode, 11… Focusing electrode, 12… Acceleration electrode, 13… Shielding cup, 14… External magnetic deflection yoke, 15, 16, 17… Electron Beam initial passage, 111
... Focusing electrode first member, 112 ... Focusing electrode second member, 11
3,113 ', 113 "... plate-shaped correction electrode.

 ──────────────────────────────────────────────────続 き Continuation of the front page (72) Inventor Masaaki Yamauchi 3681 Hayano Mobara-shi, Chiba Hitachi Device Engineering Co., Ltd. (56) References JP-A-61-250933 (JP, A)

Claims (3)

(57) [Claims] A first electrode means for generating a plurality of electron beams and directing these electron beams to a phosphor screen along initial paths parallel to each other on a horizontal plane; An electron gun having second electrode means constituting a main lens for focusing and third electrode means constituting an accelerating electrode, and a deflection yoke for deflecting each electron beam to scan on a phosphor screen. In the provided color picture tube, the second electrode means is composed of two members, a first member and a second member, and the first member is disposed adjacent to the third electrode means, and the first member has a first member. On the side opposite to the electrode means of No. 3, above and below the electron beam passage hole provided on the end face facing the second member, through a single opening provided on the end face of the second member facing the first member, The plate-like electrode extended to the inside of the second member is connected to the first member. Color picture tube, characterized in that was placed in electrical contact. 2. The apparatus according to claim 1, wherein a distance between said plate electrodes above and below said electron beam passage hole is shorter at an end portion than at a center portion of said plate electrode. A color picture tube as described. 3. The plate-shaped electrodes above and below the electron beam passage hole are connected at both ends, and the amount of extension of the connecting portion in the direction of the first member is large near the plate-shaped electrode and small at an intermediate portion thereof. Claim 1 characterized by the following:
Item 7. A color picture tube according to the above.