JPH06187921A - Color picture tube device - Google Patents

Abstract

PURPOSE:To decrease the required dynamic voltage of a color picture tube device by starting to impress a second focusing voltage between second and fourth focusing electrodes at a value lower than a first focusing voltage impressed between first and third focusing electrodes, and then generating quadrupole lens electric-fields in the voltage impressing process. CONSTITUTION:First and second focusing voltages Vf, Vb+Vd impressed respectively between first and third focusing electrodes 4, 6, and between second and fourth focusing electrodes 5, 7 are set respectively to values satisfying an inequality of Vf>Vb. Vd stands at 0V when the deflection angle of an electron beam 13 stands at zero, then it is increased with an increase in the deflection angle, and when it stands at the zero point, first and second quadrupole electric-field lenses 10, 11 are generated between the electrodes 5, 6 and between the electrodes 6, 7 respectively. For this reason, the electron beam 13 is converged at a point on the surface 15 of a fluorescent screen in a horizontal portion (a) and a vertical portion (b) shown in a figure by the actions of convex and concave lenses 10a, 10b, concave and convex lenses 11a, 11b, and besides strong and weak convex lenses 14a, 14b. Thus an optimal focus can be obtained all over the surface 15 of the screen, and consequently the low dynamic voltage Vd can suffice for a color picture tube device so that the manufacturing cost of the device may be decreased.

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 a high resolution can be obtained over the entire surface of a phosphor screen.

[0002]

2. Description of the Related Art The resolution of a color picture tube device largely depends on the size and shape of the beam spot. That is, good resolution characteristics cannot be obtained unless the beam spot generated on the phosphor screen surface by the electron beam impingement has a small diameter and is close to a perfect circle.

In a color picture tube in which three electron beam radiating parts are arranged in a straight line in a horizontal direction, the horizontal deflection magnetic field is pincushion-shaped in order to form a self-convergence structure.
Then, the vertical deflection magnetic field is distorted in a barrel shape. For this reason, the three electron beams passing through the deflection magnetic field are subjected to a diverging action in the horizontal direction and a focusing action in the vertical direction, respectively, and have a horizontally long flat cross-sectional shape with the long axis in the horizontal direction.

Generally, as the deflection angle of the electron beam increases, the trajectory of the electron beam becomes longer and the beam spot becomes overfocused. However, since a part of the beam spot is canceled by the divergence effect, the beam spot is kept in the optimum focus state in the horizontal direction during the entire deflection period. However, since the focusing action is added in the vertical direction, the degree of overfocus increases, resulting in a long haze portion in the beam spot, resulting in a reduction in resolution.

This problem has been considerably improved by the invention described in Japanese Patent Application Laid-Open No. 3-95835 filed by the present applicant. In this case, the electron gun is the cathode 1 as shown in FIG.
a, 1b, 1c, control grid electrode 2, acceleration electrode 3, plate-shaped first focusing electrode 4, plate-shaped second focusing electrode 5, third focusing electrode 6 connected to the first focusing electrode 4, second The fourth focusing electrode 7 and the final accelerating electrode 8 connected to the focusing electrode 5 are sequentially arranged.

As shown in FIG. 6, the second focusing electrode 5 has a vertically elongated electron beam passage hole 5a on the end face on the third focusing electrode 6 side.
5b and 5c, the third focusing electrode 6 has laterally long electron beam passage holes 6a, 6b and 6c on the end face on the second focusing electrode 5 side,
The end faces on the fourth focusing electrode 7 side are provided with vertically long electron beam passage holes 6d, 6e, 6f, respectively. Also,
The fourth focusing electrode 7 has laterally long electron beam passage holes 7a, 7b, 7c on the end face on the third focusing electrode 6 side.
The final accelerating electrode 8 and the final accelerating electrode 8 have non-circular electron beam passage holes 7d, 7e, 7f and 8a, 8b, 8c for producing the main lens, respectively, on the end faces opposed to each other.

A constant first focus voltage Vf is applied to the first focusing electrode 4 and the third focusing electrode 6, and the final accelerating electrode 8
A constant high voltage Va is applied to. Then, to the second focusing electrode 5 and the fourth focusing electrode 7, a dynamic voltage is applied which starts from the focus voltage Vf and gradually increases as the deflection angle of the electron beam increases. 9 in the figure
Indicates a dynamic voltage source.

Since the potential of the fourth focusing electrode 7 gradually becomes higher than the potential of the third focusing electrode 6 as the electron beam increases its deflection angle, the quadrupole lens electric field ( An axially asymmetric lens electric field) is generated. The quadrupole lens field imparts a divergent lens action to the electron beam passing therethrough in the horizontal direction and in the vertical direction. Further, since the potential of the fourth focusing electrode 7 approaches the potential of the final accelerating electrode 8, the lens action by the main lens (axial asymmetric lens electric field) generated between both electrodes 7, 8 is weakened. With these two effects, it is possible to generate a beam spot without a haze portion even in the vertical direction while maintaining the optimum focus state in the horizontal direction, and it is possible to obtain high resolution over the entire phosphor screen surface.

Moreover, as the deflection angle of the electron beam increases, the potential of the second focusing electrode 5 becomes higher than the potential of the third focusing electrode 6, so that a quadrupole lens electric field is generated between the electrodes 5 and 6. Is generated. Since the quadrupole lens electric field has a polarity opposite to that of the quadrupole lens electric field generated between the second and third electrodes 5 and 6, the lens magnifications in the horizontal direction and the vertical direction in this lens system can be made substantially equal. Therefore, it is possible to prevent the occurrence of moire due to an excessively small vertical diameter of the beam spot.

[0010]

However, a dynamic voltage is required in addition to the constant first focus voltage Vf, and the required dynamic voltage increases as the size of the color picture tube increases, so that the circuit configuration is complicated. Will lead to higher costs.

[0011]

In the present invention, an acceleration electrode, a plate-shaped first focusing electrode, a plate-shaped second focusing electrode, and a first focusing electrode are connected between a control grid electrode and a final acceleration electrode. The third focusing electrode and the fourth focusing electrode connected to the second focusing electrode are sequentially arranged. Then, a constant first focus voltage is applied to the first focusing electrode and the third focusing electrode, while the second focusing electrode and the fourth focusing electrode are lower than the first focusing voltage and the deflection angle of the electron beam By applying a second focus voltage that gradually increases with an increase, a first axially asymmetric lens electric field that is converging in the horizontal direction and diverging in the vertical direction is generated between the second focusing electrode and the third focusing electrode. To generate a second axially asymmetric lens field that is divergent in the horizontal direction and focused in the vertical direction between the third focusing electrode and the fourth focusing electrode, and strongly in the horizontal direction in the vertical direction. A third axially asymmetric lens electric field, which acts as a weak focusing lens, is generated between the fourth focusing electrode and the final accelerating electrode.

[0012]

According to this structure, the second focus voltage starts from a value lower than the first focus voltage and gradually rises as the deflection angle of the electron beam increases. Since the polar lens electric field can be generated, there is an advantage that a relatively low dynamic voltage is required.

[0013]

The present invention will be described below with reference to the illustrated embodiments. However, the electron gun in the present embodiment has the same electrode configuration as that shown in FIGS. 5 and 6, and the difference is that the second focus electrode 5 and the fourth focus electrode 7 have the second focus as shown in FIG. The point is that the voltage starts from a value lower than the first focus voltage for the first focusing electrode 4 and the third focusing electrode 6.

Now, the first focus voltage for the first and third focusing electrodes 4 and 6 is Vf, and the second and fourth focusing electrodes 5 and 7 are
Let Vb + Vd be the second focus voltage for V
Set to the relationship of f> Vb. Vd is a dynamic voltage component, which is 0 V when the deflection angle of the electron beam is 0, and gradually increases as the deflection angle of the electron beam increases. In addition, Vf = 6KV-8KV, Vf-Vb = 0.4KV-
It can be set to 2KV.

The behavior of the electron beam in the electron lens system including such a lens electric field will be described with reference to FIGS. 2 and 3. FIG. 2A shows a horizontal cross section when the deflection angle of the electron beam is 0, (B) shows a vertical cross section at the same point. At this point, the first quadrupole field lens 10 is generated between the second focusing electrode 5 and the third focusing electrode 6,
A second quadrupole lens electric field 11 is generated between the third focusing electrode 6 and the fourth focusing electrode 7.

Therefore, the electron beam 13 emitted from the crossover portion 12 is converged on one point on the phosphor screen surface 15 through the first and second quadrupole field lenses 10 and 11 and the main lens 14. First quadrupole lens 10
Is shown as a convex lens 10a in the horizontal section and as a concave lens 10b in the vertical section. Also,
The second quadrupole lens field 11 is shown as a concave lens 11a in the horizontal section and a convex lens 11b in the vertical section. The main lens 14 acts as a strong convex lens 14a in the horizontal direction, and acts as a weak convex lens 14b in the vertical direction.

As described above, Vf> Vb holds even when the deflection angle of the electron beam is 0 (Vd = 0). Therefore, both electrodes 4, 5 are caused by the potential difference between the first focusing electrode 4 and the second focusing electrode 5. The first quadrupole field lens 10 is generated between them, and the second quadrupole lens electric field 11 is generated between the third focusing electrode 6 and the fourth focusing electrode 7.
As a result of the synthetic focusing by 4 and 4, the electron beam 13 converges at a point on the phosphor screen surface 15.

FIG. 3A shows a horizontal cross section when the electron beam is considerably deflected in the horizontal direction, and FIG. 3B shows a vertical cross section at the same point. At this point, the second focus voltage (Vb + Vd) is approaching the first focus voltage (Vf), so the first and second
The convex lens 10a, the concave lens 10b, and the convex lenses 14a and 14b of the quadrupole lens electric fields 10 and 11 are weakened. This is equivalent to the occurrence of an axially asymmetric lens electric field component of relatively opposite polarity. Since the second focus voltage is close to the final acceleration electrode voltage Va, the main lens 1
4 also weakens. Then, the magnetic field lens 1 in the deflection magnetic field
6 is added as a concave lens 16a in the horizontal section and as a convex lens 16b in the vertical section, a part of which is offset by the axially asymmetric lens electric field component of the opposite polarity. Then, both quadrupole lens electric fields 10, 12,
The electron beam that has passed through the main lens 14 and the magnetic field lens 16 is converged on one point on the phosphor screen surface 15.

The case where the electron beam is deflected in the horizontal direction on the phosphor screen surface has been described above.
The same description as above applies to the case of vertical deflection.

Next, the vertical lens action by the first and second axially asymmetric lens electric fields will be described with reference to FIG. In the figure, the first focus voltage Vf is fixed at 7 KV,
FIG. 6 is a characteristic diagram in which the horizontal axis represents the second focus voltage and the vertical axis represents the amount of vertical movement of the virtual object point from the main lens (equivalent to the lens effect). The amount of movement in the conventional configuration in which the first focus voltage is fixed at 7 KV and the second focus voltage is gradually increased from 7 KV to 7.5 KV is Sa. On the other hand, the movement amount in the embodiment of the present invention in which the first focus voltage is fixed at 7 KV and the second focus voltage is gradually increased from 6.5 KV to 7 KV is Sb (Sb> Sa). In other words, it can be seen that even if the same dynamic voltage component of 0.5 KV, the dynamic voltage component necessary for obtaining the beam spot of the optimum focus can be reduced by implementing the present invention.

[0021]

As described above, according to the present invention, a beam spot of optimum focus can be generated in the peripheral portion of the screen surface by using a relatively low dynamic voltage, which is particularly applicable to a large-sized color picture tube device. Thus, it is possible to prevent the dynamic voltage generating circuit from becoming complicated and the manufacturing cost from increasing.

[Brief description of drawings]

FIG. 1 is a side sectional view showing a configuration of a color picture tube device embodying the present invention.

FIG. 2 is a diagram for explaining the behavior of an electron beam in the lens system of the same apparatus (when there is no deflection).

FIG. 3 is a diagram for explaining the behavior of an electron beam in the lens system of the same apparatus (during deflection).

FIG. 4 is a characteristic diagram for explaining a lens effect of the device.

FIG. 5 is a side sectional view showing an electrode array of an electron gun of a color picture tube device.

FIG. 6 is a plan view of a part of an electrode forming the electron gun.

[Explanation of symbols]

 2 control grid electrode 3 acceleration electrode 4 first focusing electrode 5 second focusing electrode 6 third focusing electrode 7 fourth focusing electrode 8 final accelerating electrode

Claims (2)

[Claims] 1. An acceleration electrode, a flat plate-shaped first focusing electrode, a flat plate-shaped second focusing electrode, between a control grid electrode and a final acceleration electrode,
A third focusing electrode connected to the first focusing electrode and a fourth focusing electrode connected to the second focusing electrode are sequentially arranged, and a constant first focus voltage is applied to the first focusing electrode and the third focusing electrode. On the other hand, a second focus voltage, which is lower than the first focus voltage and gradually increases with an increase in the deflection angle of the electron beam, is applied to the second focusing electrode and the fourth focusing electrode to focus in the horizontal direction. A first axially asymmetric lens field, which is divergent in the vertical direction, between the second focusing electrode and the third focusing electrode, and which is divergent in the horizontal direction and focused in the vertical direction. A second axially asymmetric lens electric field is generated between the third focusing electrode and the fourth focusing electrode, and a third axially asymmetric lens electric field that is strong in the horizontal direction and weak in the vertical direction acts as a fourth axially asymmetric lens electric field.
A color picture tube device characterized in that it is formed between a focusing electrode and a final accelerating electrode. 2. The synthetic focusing lens action by the first, second and third axially asymmetric lens electric fields is equal in a horizontal section and a vertical section when the deflection angle of the electron beam is zero. The color picture tube device according to claim 1.