JP3262622B2 - Color picture tube equipment - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a color picture tube device constructed so that high brightness and high resolution can be obtained over the entire area of a phosphor screen.

[0002]

2. Description of the Related Art The resolution characteristics of a color picture tube apparatus largely depend on the size and shape of a beam spot. Generally, the size of the beam spot has an optimum value determined by the size of the screen and the application. If the beam spot diameter is smaller than that, moire, which is an interference fringe between the shadow mask and the scanning line, is generated. Conversely, if the beam spot diameter is larger than that, the resolution is reduced. When trying to obtain high brightness by modulating the beam current in order to modulate the screen brightness, the beam current tends to increase and the beam spot tends to increase accordingly.

On the other hand, in the peripheral portion of the phosphor screen surface, the distance from the electron gun to the phosphor screen surface becomes longer than the central portion due to the increase in the deflection angle of the electron beam. If the center of the phosphor screen is kept at the optimum focus voltage with a small diameter and a perfect circular beam spot can be obtained, the periphery of the phosphor screen will be over-focused and a small beam spot will be obtained. Absent.

Further, in an in-line type color picture tube in which three electron beam radiating portions are arranged in a horizontal straight line, the horizontal deflection magnetic field distribution is made into a pincushion shape and the vertical deflection magnetic field distribution is made into a barrel shape in order to obtain a self-convergence effect. As a result, the three electron beams passing through the deflection magnetic field distribution undergo a diverging action in the horizontal direction and a focusing action in the vertical direction, and strong astigmatism also occurs in each deflection beam. As shown in FIG. 5, the effect of astigmatism on the beam spot is such that, in the periphery of the screen surface 33, the vertical direction is overfocused, the halo 24 is generated in the vertical direction, and the lens having a horizontal section and a vertical section is formed. This causes a difference in magnification, which appears as a phenomenon 25 in which the core shape of the spot is distorted into a horizontally long ellipse. As a result, moiré fringes occur at the peripheral portion of the phosphor screen surface due to interference between the scanning lines and the arrangement of the holes of the shadow mask, and it becomes impossible to obtain a good resolution.

[0005] As a means for solving these problems of resolution degradation, the following method is used. As measures against a decrease in resolution due to a large beam spot diameter at a large beam current, JP-A-59-148242, JP-A-60-51775
There is a method described in each publication. FIG. 2 shows a beam forming section that produces a large beam spot diameter at a large beam current, and FIG. 3 shows a beam forming section described in Japanese Patent Laid-Open No. 148242/1984. 3, the second grating 18 and the third grating 19 have electron beam passage holes smaller in diameter than the conventional second grating 15 and the third grating 16 as shown in FIG. 2, respectively. The mutual interval between 18 and the third grating 19 is also smaller than in the conventional configuration. In the pre-focusing lens 20 having the above-described configuration, since the respective lens functions of the converging lens portion 20a and the diverging lens portion 20b of the pre-focusing lens 20 are both enhanced, an aberration suppression effect appears, and the beam divergence angle incident on the main lens is reduced. The beam spot on the phosphor screen can be reduced in diameter without increasing.

On the other hand, there is a method described in Japanese Patent Application Laid-Open No. 3-95835 as a means for simultaneously solving the generation of a vertical halo and the flattening of the beam spot at the peripheral portion of the phosphor screen surface. . A first focusing electrode to which a constant focus voltage is applied and a second focusing electrode to which a dynamic voltage that gradually increases with an increase in the deflection angle of the electron beam from the focus voltage are installed, and the first focusing electrode and the second focusing electrode are provided. By providing a non-axisymmetric lens electric field generating means on at least one of the surfaces facing the electrodes, the horizontal direction is divergent and the vertical direction is convergent, or the horizontal direction is convergent,
An electric field lens having a divergent horizontal direction, that is, a so-called quadrupole lens electric field can be generated.

As shown in FIG. 7, a first quadrupole lens 29 acting in the divergent form in the horizontal section (a) and in the converging form in the vertical section (b) is placed near the main lens 28 near the beam exit point 26. A second quadrupole lens 30 having a focusing function in the horizontal section (a) and a diverging function in the vertical section (b) is provided. The lens magnification is corrected by the first quadrupole lens 29 and the second quadrupole lens 30 is corrected.
As a result, the overfocus and the horizontally flattened shape of the beam spot are simultaneously corrected in the peripheral portion 31 of the phosphor screen, and no halo is generated as shown in FIG. A beam spot 32 can be obtained on the phosphor screen surface 33. In addition, the dynamic voltage is gradually increased as the deflection angle of the electron beam is increased.
A good beam spot can be obtained in all 33 areas.

[0008]

However, in the case where the above-mentioned correction means for lowering the resolution is combined, the effect of correcting the shape of the beam spot may not be obtained when the beam current is small. As shown in FIG. 4, in order to prevent the diameter of the beam spot at the time of a large beam current from increasing, the distance between the second grating 18 and the third grating 19 is shortened, and the beam forming unit in which the preliminary focusing lens 20 is strengthened. In the configuration of (1), the effective electron emission area of the electrons emitted from the hot cathode 1 at the time of the small beam current becomes small, and the crossover 5b is generated near the hot cathode 1 due to the strong focusing action of the cathode lens 4, so that the preliminary focusing is performed. Since the focusing effect of the lens 20 becomes effective, the beam divergence angle becomes too small, and this electron beam 22a,
22b crosses the center axis again before reaching the main lens,
A second crossover 23 occurs. In this case, the distance between the first quadrupole lens 7 and the second crossover 23 provided for correcting the oblong flatness of the beam spot is extremely shortened, or the second quadrupole lens 7 is moved closer to the main lens side than the first quadrupole lens 7. When the crossover 23 occurs, the operation of the first quadrupole lens 7 is not effective, and the effect of correcting the oblong flatness is lost. In that case,
Since the vertical diameter of the spot is too small, the above-described moiré is likely to occur. Further, since the virtual image 13 of the crossover, that is, the position of the object point with respect to the main lens largely moves to the phosphor screen side, the beam spot cannot be optimally focused on the phosphor screen surface.

The present invention solves the above-mentioned conventional problems. By preventing the occurrence of the second crossover at the time of a small beam current, a good resolution can be obtained over the entire phosphor screen surface in the entire beam current region. It is an object to provide a color picture tube device obtained.

[0010]

In order to achieve this object, a picture tube device according to the present invention comprises a hot cathode, a first grating which is an electron flow control electrode, and a second grating which is an electron accelerating electrode. A pre-focusing electrode is arranged adjacent to the pole portion, and a constant focus voltage is applied to a position between the pre-focusing electrode and the final accelerating electrode, the position being close to the pre-focusing electrode. A second focusing electrode to which a dynamic voltage that gradually increases with an increase in the deflection angle of the electron beam is provided, and a non-axisymmetric lens is provided on at least one of the opposing surfaces of the first focusing electrode and the second focusing electrode. A color picture tube apparatus for providing an electric field generating means for generating a lens electric field between both converging electrodes, the lens electric field being divergent in the horizontal direction and converging in the vertical direction, wherein the preliminary focusing electrode comprises a 3-1 grating, 3-2 lattice consists of three grid of 3-3 grating, substantially the same focus voltage is applied to the first 3-1 grating and 3-3 grating, the second 3-2
The grating is maintained at a lower voltage than the 3-1 and 3-3 gratings and creates a pre-focusing lens electric field between the 3-1 and 3-3 gratings.

[0011]

According to this configuration, the effect of preventing the second crossover from occurring at the time of a small beam current and suppressing the diameter of the beam spot at the time of a large beam current can be obtained. Accordingly, it is possible to prevent the focus from being deteriorated due to the movement of the position of the object point with respect to the main lens without weakening the lens effect of the first quadrupole lens with the small beam current. It also has the effect of preventing the beam spot diameter from increasing at the time of a large beam current.
In addition, good resolution can be obtained over the entire phosphor screen surface.

[0012]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments will be described below in detail with reference to the drawings. As shown in FIG. 1, a third cathode composed of a hot cathode 1 for emitting an electron beam, a first grating 2 serving as an electron flow control electrode, and a second grating 3 serving as an electron accelerating electrode is provided with a third cathode.
-1 grating 6a, 3-2 grating 6b, and 3-3 grating 6c
A preliminary focusing electrode 6 made of
Of the pre-focusing electrode between the
A first focusing electrode 7b to which a constant focus voltage is applied and a second focusing electrode 7a to which a dynamic voltage gradually increasing from the focus voltage as the deflection angle of the electron beam increases is applied to a position near the -3 grating 6c. Is installed. The first focusing electrode 7b and the second focusing electrode 7a constitute a non-axisymmetric lens electric field means. That is, the first focusing electrode 7b is provided with a horizontally long opening, and the second focusing electrode 7a is provided with a vertically long opening, and a non-axisymmetric lens electric field is generated between the two focusing electrodes 7a and 7b. It has become.

Approximately the same focus voltage is applied to the 3-1st grating 6a and the 3rd grating 6c.
b is maintained at a lower voltage than the 3-1 grating 6a and the 3-3 grating 6c, and the 3-1 grating 6a and the 3-3 grating 6c
And the preliminary focusing lens 9 is generated. By shortening the interval between the second grating 3 and the 3-1 grating 6a that generate the preliminary focusing lens 8, and reducing the hole diameter of the second grating 3 and the 3-1 grating 6a, the second grating 3 side And the divergent lens portion 8b formed on the side of the 3-1st grating 6a are brought close to each other, and a strong lens action is generated in both lens portions.

Typical values of the hole diameter, plate thickness, and applied voltage of each electrode are shown below.

[0015]

[Table 1]

In the picture tube apparatus configured as described above, the paraxial electron beams 10a and 10b emitted from the central region of the hot cathode 1 are affected by the cathode lens 4 as shown in FIG. The crossover 5a is formed at a position far from the hot cathode 1 without receiving much. Since the crossover 5a penetrates deeply into the converging lens portion 8a, it does not receive much converging action at the converging lens portion 8a, and the diverging lens portion 8b
, And is hardly affected by the preliminary focusing lens 8.

In general, the absence of the lens action means that the spherical aberration of the lens included in the lens is also suppressed, and the virtual image point 13 of the crossover of the electron beam emitted from the preliminary focusing lens 8 has the beam current value To the change. If the position of the object point is stable like this,
The diameter of the electron beam spot formed on the phosphor screen focused by the main lens can be reduced due to less aberration.

On the other hand, the electron beams 12a and 12b emitted from the peripheral region of the hot cathode 1 are greatly affected by the spherical aberration of the cathode lens 4, and form a crossover 5b near the hot cathode 1. Since the light is incident on the converging lens portion 8a at a relatively large divergence angle, it passes through a position distant from the central axis of the converging lens portion 8a and receives strong aberration of the converging lens portion 8a. In this case, the points 14a, 14 at which the electron beams 12a, 12b intersect the slightly more paraxial beams 11a, 11b.
b occurs. Further, when the plate thickness of the second grating 3 is reduced and the positions of the crossovers 5a and 5b of each electron beam and the position of the preliminary focusing lens 8 are brought close to each other, the focusing action of the electron beam as a whole is weakened, and 2 grid 6b and 3rd
The light is further focused by the second pre-focusing lens 9 formed by the grating 6c, and enters the main lens.
The divergence angle of the beam is reduced to the same beam divergence angle as in the prior art as shown in FIG. Therefore, the electron beam incident on the main lens can have an appropriate diameter, and the spherical aberration received by the main lens can be reduced. By these effects, the beam spot on the phosphor screen surface at the time of a large beam current can be reduced in diameter, and the current density distribution can be sharp. When the thickness of the second grating is reduced and the position of the crossover of each electron beam and the position of the preliminary focusing lens are made close to each other, the distance between the position of the crossover and the preliminary focusing lens does not increase, Since the focusing action of the pre-focusing lens does not become too large, no second crossover occurs at small beam currents.

[0019]

As described above, according to the present invention,
It is possible to prevent the occurrence of the second crossover which occurs when the preliminary focusing lens is used for the purpose of preventing the beam spot diameter from increasing at a large beam current, and to provide a good resolution over the entire phosphor screen surface in the entire beam current range. Can be provided.

[Brief description of the drawings]

FIG. 1 is a diagram showing a beam forming unit in a picture tube device according to an embodiment of the present invention.

FIG. 2 is a diagram showing a conventional beam forming unit at the time of a large beam current.

FIG. 3 is a diagram showing another conventional beam forming unit having improved characteristics at the time of a large beam current.

FIG. 4 is a diagram showing the occurrence of a second crossover at the time of a small beam current in a conventional example.

FIG. 5 is a diagram showing the shape of a beam spot in a conventional example.

FIG. 6 is a diagram showing a shape of a beam spot on a phosphor screen surface when two pairs of quadrupole lenses are operated.

FIG. 7 is a diagram showing a lens configuration of a quadrupole lens.

[Explanation of symbols]

1 ... hot cathode, 2 ... first grid, 3 ... second grid,
4 ... Cathode lens, 6 ... Pre-focusing electrode, 6a ...
3-1st lattice, 6b ... 3rd lattice, 6c ... 3rd
3 gratings, 7 ... first quadrupole lens, 7a ... second focusing electrode, 7b ... first focusing electrode, 8 ... first preliminary focusing lens, 8a ... focusing lens portion, 8b ... divergent lens portion, 9 ... second preliminary focusing lens.

────────────────────────────────────────────────── ─── Continuation of front page (56) References JP-A-3-116636 (JP, A) JP-A-4-262344 (JP, A) JP-A-6-187921 (JP, A) (58) Field (Int.Cl. ⁷ , DB name) H01J 29/48 H01J 29/50 H01J 29/56

Claims (1)

(57) [Claims] 1. A preliminary focusing electrode is disposed adjacent to a triode comprising a hot cathode, a first lattice as an electron flow control electrode, and a second lattice as an electron accelerating electrode. A first focusing electrode in which a constant focus voltage is applied to a position between the electrode and the preliminary focusing electrode, and a second dynamic voltage in which a gradually increasing dynamic voltage is applied from the focus voltage as the deflection angle of the electron beam increases. A focusing electrode is provided, and a non-axisymmetric lens electric field generating means is provided on at least one of the opposing surfaces of the first focusing electrode and the second focusing electrode, so that the diverging type is provided in the horizontal direction and the focusing type is provided in the vertical direction. A color picture tube device for generating a lens electric field between both focusing electrodes, wherein said preliminary focusing electrode comprises three gratings of a 3-1st grating, a 3-2nd grating, and a 3rd grating, 3-1 rank And the 3-3 grating substantially the same focus voltage is applied, the first 3-2 grating claim 3-1 grating and a 3-
A color picture tube device, which is maintained at a voltage lower than the three gratings and generates a preliminary focusing lens electric field between the 3-1st grating and the 3rd grating.