JP2708493B2 - Color picture tube - Google Patents

Description

Description: BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color picture tube, and more particularly, to a shape of an electrode constituting a main lens of an electron gun and a method of applying a voltage to each electrode.

[Conventional technology]

FIG. 2 is a plan view of a color picture tube provided with an electron gun having a conventional structure. Face plate part 2 of glass envelope 1
A phosphor screen 3 in which phosphors of three colors are alternately applied in a stripe shape is supported on the inner wall of the phosphor. Central axis 15,1 of cathode 6,7,8
6, 17 are G1 electrode 9, G2 electrode 10, focusing electrode 1 constituting the main lens
The first and shielding cups 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 the outer apertures are respectively different. It does not coincide with the corresponding central axes 15, 17 and is slightly displaced outward. 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 acceleration electrode 12,
Shielding cup 13, conductive film 5 provided inside glass envelope
And the same potential. Since the apertures at the center of the focusing and acceleration electrodes are coaxial, the main lens formed in the center is axisymmetric, and the central beam is focused by the main lens and then travels straight along the axis. . 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
Of the main lens area, the diverging lens area formed on the accelerating electrode side, passes through a portion deviated from the lens center axis in the central beam direction, and receives a focusing action in the central beam direction at the same time as the focusing action by the main lens. . Thus, 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 undergoes color discrimination by the 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.

As described above, the STC can be removed at the center of the screen by combining the in-line electron gun, in which the three electron beam paths are arranged on a horizontal plane, and the so-called Ceralff convergence deflection yoke that forms a special asymmetric magnetic field distribution. It is known that the convergence can be achieved over the entire other screen if it is possible. 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 an electron beam spot is deformed by deflection aberration.

In the periphery 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 Application 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 115 and a second member 116 from the cathode toward the phosphor screen. 1st member
FIG. 4 (b) shows an end surface of the second member 115 facing the second member 116.
As shown in FIG. 5, a long slit is provided in the vertical direction.
The end face of the second member 116 facing the first member is provided with a horizontally long slit-shaped opening as shown in FIG. 4 (c), and is synchronized with the deflection current supplied to the deflection yoke. A dynamically fluctuating voltage, that is, a dynamic voltage is provided to be superimposed on the focused voltage _Vf . When the deflection amount is large, the potential difference between the first member and the second member becomes large, so that the quadrupole lens formed by the slits becomes strong, and large astigmatism occurs in the electron beam spot. If the potential of the second member 116 is higher than the potential of the first member 115, 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.
Astigmatism due to electron beam deflection shown in FIG. 3 can be eliminated, and the resolution at the periphery of the screen can be improved. On the other hand, when the electron beam is not deflected, the first
By eliminating the potential difference between the member and the second member, it is possible to prevent the formation of an asymmetric lens and to achieve a condition in which astigmatism does not occur at the center of the screen, so that the resolution does not deteriorate.

In a 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 conditions for focusing the electron beam 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 drawing, when the electron beam is deflected to the periphery of the screen, the potential of the second member 115 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 reduced. For this reason, the electron lens 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. That is, it is possible to realize dynamic focus simultaneously with dynamic astigmatism correction.

FIG. 5 shows another conventional example disclosed in Japanese Patent Application Laid-Open No. 61-250934. As in the conventional example shown in FIG.
Divide into 18 18 members. As shown in FIGS. 5 (b) and 5 (c), on the opposing surface of each member, flat and horizontal plate correction electrodes are arranged so as to be combined with each other to form a quadrupole lens. The second member 118 applies a dynamic voltage V _d which is superimposed on the focusing voltage V _f, to achieve dynamic astigmatism correction and dynamic focusing simultaneously.

[Problems to be solved by the invention]

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

In addition, the above-described related art has the following problems. That is, in the above-described conventional technique, in order to obtain STC, among the main lenses formed between the G3 electrode second member 116 or 118 and the G4 electrode 12, the outer main lens is formed to be non-axially symmetric. Is common in The non-axially symmetric component included in the lens electric field concentrates the outer beam on the central beam side. However, in the above-mentioned prior art, in order to achieve dynamic focus, the potential of the G3 electrode second member 116 or 118 is increased by beam deflection to weaken the strength of the main lens. The symmetry component is also weakened, which causes a problem with beam convergence that the outer beam and the center beam cannot be concentrated on the shadow mask at one point.

SUMMARY OF THE INVENTION An object of the present invention is to provide an electron gun structure capable of simultaneously realizing dynamic astigmatism correction and dynamic focus, and requiring less precision in manufacturing and assembling parts than in the past.

Another object of the present invention is to provide a color picture tube having an electron gun structure which does not cause a problem with respect to beam convergence even when a dynamic voltage is applied.

[Means for solving the problem]

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

[Action]

In the electrode structure according to the present invention as described above, the first and second member-facing surfaces opposed to each other via the plate-shaped correction electrode are provided with circular openings having the same diameter and the same diameter as each other. Therefore, unlike the embodiment shown in FIG. 4, the first and second members can be assembled with extremely high precision by using a cylindrical through-hole assembly jig usually used for assembling an electron gun. Also, as compared with the embodiment of FIG. 5, since there is no vertical plate-like correction electrode, errors in the combination of the first and second members, deterioration of component accuracy of the first member, and the like hardly occur.

〔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. An electrode plate 114 having three circular electron beam passage holes is arranged inside the first member 111. Second
The member 112 is provided with three circular electron beam passage holes on an end face facing the first member 111, and a flat plate-like correction electrode 113 extending in the first member direction is connected above and below the passage hole. The electron beam passage holes of the electrode plate 114 and the second member 112 corresponding to the respective electron beams are coaxial and have the same diameter.

A constant focusing voltage _Vf is applied to the first member 111 and the second member 112
Applying a dynamic voltage V _d is superimposed on the V _f in. When the electron beam is deflected, V _d
To rise. As _Vd increases, the first member 111 and the second
The strength of the quadrupole lens formed at the opposing portion of the member 112 is increased, 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 electric structure shown in FIG. 1, the circular beam passage hole provided in the electrode plate 114 and the circular beam passage hole on the first member 111 side of the second member 112 are coaxial and have the same diameter, so that they are usually used for electron gun assembly. By passing a cylindrical assembly jig through each hole, extremely high assembly accuracy can be obtained.

FIG. 6 shows the results obtained by analyzing the astigmatism correction characteristics of the embodiment shown in FIG. The main dimensions of the analyzed electron gun are as follows.

Focusing electrode total length: 26.33 mm 間隔 1st member 111-2nd member 112 interval: 0.5 mm Circular beam passing hole diameter on the electrode plate 114 and the electrode surface of the 2nd member 112 on the 1st member 111 side, and flat plate correction Electrode 113
The distance D between the upper and lower electrodes is 4 mm.
The interval of 114 is g, and the length of the second member 112 is lG3-2.

Astigmatism characteristics, a V _f of analysis by the following procedure and (7.4KV in this analysis) constant value, superimposes the dynamic voltage V _d to the second member 112. Changing the E _b for each V _d, obtains a voltage E _bv and E _bh electron beam diameter in the vertical and horizontal directions at the center of the screen is minimized, respectively, vertical represented by ΔE _b = E _bv -E _bh , The horizontal _Eb voltage difference is calculated. V _d
Is a positive value and E _bv becomes E
It becomes larger than _bh , and ΔE _b becomes a positive value. This is because, in order to focus the electron beam in the vertical direction, the focusing electrode second member 112 and the
The main lens strength formed between 3 and 3 must be increased, which means that at a constant E _b , the core of the electron beam spot is stretched vertically and the halo is stretched horizontally. The astigmatism caused by the electrostatic quadrupole lens has the effect of canceling out the astigmatism caused by electron beam deflection shown in FIG. Therefore, for the same V _d, the larger the value of Delta] E _b, resulting in a higher sensitivity of correction of astigmatism by the quadrupole lens. The FIG. 6, when the dynamic voltage V _d to 1 KV, various l,
The values of ΔE _b with respect to the values of g and lG3-2 are shown. Sixth
According to the figure, the astigmatism correction sensitivity is the length l of the correction electrode 113.
, And strongly depends on the distance g between the correction electrode 113 and the electrode plate 114. The electrode plate 114 has the effect of increasing the astigmatism correction sensitivity, and the smaller the value of g, the higher the sensitivity. Further, the relationship between the position of the quadrupole lens and the astigmatism correction sensitivity can be seen from FIG. Overall length l of the second member 112
As G3-2 becomes shorter, that is, as the position of the quadrupole lens approaches the position of the main lens formed between the second member 112 and the acceleration electrode 13, the astigmatism correction sensitivity becomes higher.

The embodiment shown in FIG. 1 can also solve the problem of beam convergence. As the dynamic voltage _Vd increases, the acceleration voltage E
_Since the potential difference between _d and the voltage of the second member 112 is reduced, the electric field is weakened. Therefore, the non-axisymmetric component of the electric field, which has the function of deflecting the outer beam in the direction of the center beam for beam convergence, is also weakened at the same time,
The amount of deflection of the outer beam decreases. However, in the embodiment of FIG. 1, with the rise of the dynamic voltage V _d, since the effect of increasing the amount of deflection of the outer beams at the quadrupole lens section results, compensates the reduction amount of the, V _d is varied Can always achieve convergence.

How the beam is deflected by the quadrupole lens will be described with reference to FIG. FIG. 7 schematically shows the distribution of equipotential lines in the AA section of the embodiment of FIG. The equipotential line 407 is connected to the two correction electrodes 113 as shown in the figure.
The electric potential of the first member 111 which enters inside at the intermediate portion is lower than that of the correction electrode 113, and an electric field is generated in the direction shown by the arrow 702 in FIG. The outer beam is forced in a direction opposite to this electric field and is deflected in the direction of the central beam. When the dynamic voltage _Vd is increased, this electric field becomes stronger and the amount of deflection of the outer beam increases.

FIG. 8 shows the results of analyzing the convergence fluctuation amounts for various values of l, g, and lG3-2. ΔX on the vertical axis in FIG.
Which, when the dynamic voltage V _d is increased 1 KV, representing the horizontal distance between the two outer beams at the center of the screen. Δ
If X is 0, convergence does not vary by V _d. When ΔX is positive, the beam deflection is excessive with the increase of V _d, 3 beams would be focused in front of the screen. When ΔX is a negative value, conversely, as _Vd increases, beam deflection becomes insufficient, and the beam does not concentrate even when it reaches the screen.

By appropriately selecting l, g, and lG3-2, Δx can be set to 0 and the problem of beam convergence can be solved. In particular, when l is changed, only the convergence can be independently adjusted without affecting the astigmatism correction sensitivity, and the electrode design is easy.

In the embodiment shown in FIG. 1, the electron beam passage holes provided in the electrode plate 114 are circular, but if the holes have the same horizontal and vertical diameters, such as a square as shown in FIG. For example, by using a cylindrical electrode assembly jig, the electrodes can be assembled with high accuracy, and the same effects as in the embodiment of FIG. 1 can be obtained.

FIG. 10 shows an embodiment in which the electron beam passage holes provided in the electrode plate 114 are rectangular. In this case, when the cylindrical assembly jig is used, the positional accuracy of the electrode plate 114 in the vertical direction cannot be sufficiently obtained. However, if the vertical diameter of the electron beam passage hole is sufficiently larger than the distance between the upper and lower plate-like correction electrodes, the influence of the vertical position shift is shielded by the plate-like correction electrode, and no problem occurs. In the shape of the electron beam passage hole shown in FIG. 10, the astigmatism correction sensitivity can be improved.

Even if the horizontal diameter of the electron beam passage hole is larger than the vertical shape, the problem of beam convergence can be solved,
It is not preferable because it lowers the astigmatism correction sensitivity and the electrode assembly accuracy.

In the above embodiments, the so-called Bi-Potential Focusing lens in which the electron gun main lens is composed of two electrodes, that is, only the BPF lens is targeted, but the so-called Uni-Potential Focusing lens, which is composed of three electrodes, that is, The present invention can be applied to the focusing electrode of the UPF lens, and can also be applied to a multi-stage main lens obtained by combining these lenses.

〔The invention's effect〕

According to the present invention, dynamic astigmatism correction and dynamic focus can be simultaneously realized. Also, by applying a dynamic voltage, it is possible to provide a color picture tube having an electron gun structure that does not cause a problem with beam convergence.

[Brief description of the drawings]

FIG. 1 is a vertical sectional view and a front view of a main part of an electron gun according to an embodiment of the present invention. FIG. 2 is a horizontal cross-sectional view and a front view of a main part 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 term of a color picture tube screen by a conventional electron gun. FIGS. 4 and 5 are vertical sectional views and front views of main parts of other conventional electron guns, respectively. FIG. 8 is a graph showing the analysis results of the electron gun characteristics of the embodiment of the present invention, and FIG. 7 is a schematic diagram of the vertical section and the equipotential line distribution in the inside of the embodiment of FIG. FIG. 7 is a front view of a main part of another embodiment of the present invention. Explanation of reference numerals 1 ... Glass envelope, 2 ... Face plate, 3 ...
Fluorescent screen, 4 ... 5 ... conductive film, 6,7,8 ... cathode, 9 ...
... G1 electrode, 10 ... G2 electrode, 11 ... focusing electrode, 12 ... acceleration electrode, 13 ... shield cup, 14 ... external magnetic deflection yoke,
15, 16, 17 ... initial electron beam path, 111 ... focusing electrode first member, 112 ... focusing electrode second member, 113 ... flat correction electrode, 114 ... electrode plate.

Continued on the front page (72) Inventor Seiji Yoshiyama 3681 Hayano, Mobara-shi, Chiba Hitachi Device Engineering Co., Ltd. (72) Inventor Kazunari Noguchi 33000 Hayano, Mobara-shi, Chiba Pref. References JP-A-63-32837 (JP, A) JP-A-61-99249 (JP, A) JP-A-1-137540 (JP, A)

Claims (6)

(57) [Claims] In a color picture tube provided with a phosphor screen and an electron gun, the electron gun generates a plurality of electron beams and directs these electron beams along initial paths parallel to each other on a horizontal plane. A first electrode means for directing the electron beam to the phosphor screen, and a second electrode means for constituting a main lens for focusing each of the electron beams on the phosphor screen, and an electrode constituting the main lens A focusing electrode adjacent to the accelerating electrode to which the highest voltage is applied is formed of two members, a first member and a second member, and the second member is disposed adjacent to the accelerating electrode; Two plate-shaped electrodes arranged above and below an electron beam passage hole provided on an end face of the first member facing the first member and electrically connected to the second member are connected to the second electrode of the first member. A single opening provided on the end face facing the member And extending inside the first member, disposed inside the first member, facing the flat electrode at a fixed interval, in a direction parallel to the horizontal plane, and in a direction perpendicular to the horizontal plane. An electrode plate provided with an electron beam passage hole having the same diameter is electrically connected to the first member, and the second member is configured to scan the plurality of electron beams on the phosphor screen, A color picture tube characterized by applying a voltage that fluctuates in synchronization with a deflection amount when the plurality of electron beams are deflected. 2. A color picture tube according to claim 1, wherein said electron beam passage hole formed in said electrode plate has a circular shape. 3. The color picture tube according to claim 1, wherein the electron beam passage hole formed in said electrode plate has a square shape. 4. A color picture tube provided with a phosphor screen and an electron gun, said electron gun generating a plurality of electron beams and passing these electron beams along initial paths parallel to each other on a horizontal plane. A first electrode means for directing the electron beam to the phosphor screen, and a second electrode means for constituting a main lens for focusing each of the electron beams on the phosphor screen, and an electrode constituting the main lens A focusing electrode adjacent to the accelerating electrode to which the highest voltage is applied is formed of two members, a first member and a second member, and the second member is disposed adjacent to the accelerating electrode; Two plate-shaped electrodes arranged above and below an electron beam passage hole provided on an end face of the first member facing the first member and electrically connected to the second member are connected to the second electrode of the first member. A single opening provided on the end face facing the member First, it extends to the inside of the first member, is disposed inside the first member, faces the flat electrode at a fixed interval, and has a diameter in a direction perpendicular to the horizontal plane parallel to the horizontal plane. An electrode plate provided with an electron beam passage hole larger than the diameter in the direction is electrically connected to the first member, and the second member has a plurality of electron beams for scanning on the phosphor screen, A color picture tube characterized by applying a voltage that fluctuates in synchronization with a deflection amount when the plurality of electron beams are deflected. 5. A method according to claim 1, wherein a diameter of the electron beam passage hole provided in said electrode plate in a direction perpendicular to said one horizontal plane is larger than a distance between said upper and lower plate electrodes. The color picture tube according to claim 4. 6. An electron beam passing hole provided in said electrode plate has a rectangular shape.
2. The color picture tube according to 1.