JPS58198832A - Cathode-ray tube device - Google Patents

Abstract

PURPOSE:To obtain good resolution all over a screen by a method wherein in the first part of a focusing electrode system consisting of the first - third grid electrodes, any one of them is made to be a beam pass hole of an axially asymmetrical type while the fixed focusing voltage is applied to the first and the third electrodes and the dynamic voltage is applied to the second electrode. CONSTITUTION:In an electron gun 9 consisting of three electrodes 10'-10''' arranged on a horizontal straight line, that is, a control electrode 11, an acceleration electrode system 12, the first part and the last part focusing electrode systems 13 and 14, the first focusing electrode system 13 consists of the first - the third grid electrodes 15-17 along an electron beam passage. Said first and third electrodes 15 and 17 are made to have each group of three cylindrical beam passage holes 18'-18''' and 19'-19''' while the second electrode 16 is made to have the vertically long rectangular beam passage holes 20'-20'''. Further a fixed focusing voltage Vfoc is applied to the first and the third electrodes 15 and 17 while the dynamic voltage V'foc, which changes according to a beam deflection quantity, is made to be applied to the second electrode 16.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a cathode ray tube device, which is constructed so that good resolution can be obtained over the entire area on the phosphor screen surface.

In general, the resolution of a cathode ray tube device depends on the size and shape of the beam spot (bright spot) generated on the phosphor screen surface, and in order to obtain high resolution,
It is important that the beam spot be as small as possible and without distortion. In addition, in color cathode ray tube devices, it is important from the viewpoint of resolution that the beam spot of the three electron beams be correctly concentrated at any one point on the phosphor screen surface, and for this reason, an in-line type color cathode tube is used. In this case, the horizontal deflection magnetic field distribution is distorted into a bottle cushion shape as shown in Fig. 1(a), and the vertical deflection magnetic field distribution is distorted into a barrel shape as shown in Fig. 1(b). 3 Self-focusing of electron beams 1, 2.3 (
self-convergence) sassetail.

However, when such a self-concentration method is adopted, even though the concentration of the three electron beams is good, the cross-sectional shape of the three electron beams becomes distorted as the beam deflection angle increases, causing problems especially in areas on the phosphor screen surface. The beam spot that appears on the periphery,
This tends to cause distortions as shown in FIG. That is,
The beam spot 5 that appears at the center of the phosphor screen surface 4 is a perfect circle, whereas the beam spot 3 that appears at the periphery has a high-intensity core part 7 that is long in the horizontal direction and has a vertical elliptical shape. A long low-luminance haze portion 8 accompanies the screen, making it difficult to obtain high resolution, especially in the screen circumferential portion.

The above-mentioned distortion of the beam spot shape is caused by the fact that the deflection yoke in the self-focusing method applies a non-uniform magnetic field to the three electron beams as shown in FIGS. 1(a) and (b). The electron beam within the deflection magnetic field will have its focus imparted within the electron gun weakened in the horizontal direction and strengthened in the vertical direction.

The present invention has been made to eliminate the above-mentioned drawbacks of the conventional art. Next, a cathode ray tube device of the present invention will be described with reference to embodiments shown in the drawings.

In FIG. 3, there is an electron gun 9, three cathodes 1o, 10, 10 arranged horizontally in a straight line, a control electrode 11, an accelerating electrode system 12, an iQ-stage focusing electrode system 13, and a rear-stage focusing/electrode system. 14, and the pre-focusing system 13 consists of first, second and third grid electrodes 15, 16, 17 arranged sequentially along the electron beam path. As shown in FIG. 4, the first and third grid electrodes 15.17 each have three circular electron beam passing holes 18', 18, 18; 19, 19.1.
9, and the second grid electrode 16id has vertically elongated rectangular electron beam passing holes 20, 20.20. A constant focusing voltage Vfoc is applied to the first and third grid electrodes 15, 17, and a Guinamisok voltage v/fo0 that changes depending on the amount of beam deflection is applied to the second grid electrode 16.

When the deflection current 23 is W(7) as shown by the solid line 21 or the dashed-dotted line 22 in FIG. 5, that is, when the beam spot appears at the center of the fluorescent screen surface, the voltage Vfoc takes the same value as and
As the deflection current increases or decreases, the voltage vfoo gradually decreases or increases. Therefore, when the beam spot appears in the center of the phosphor screen surface, the first . The second and third grid electrodes 15, 16, 17 are at the same potential VfOC, so that no lens electric field is generated between these grid electrodes, and the electron beam passage hole 20' of the second grid electrode 16.

Despite the fact that the electron beams 20, 20 are non-circular, no axis-asymmetric electric field acts on the electron beam, and a perfectly circular beam spot is obtained at the center of the screen surface.

On the other hand, as the amount of beam deflection increases, the voltage v/foc decreases to V
When descending or ascending from foc, a constant focusing voltage Vf
oc is applied to the first and third grid electrodes 15.
A lens electric field is generated between the grid electrode 17 and the second grid electrode 16. This lens electric field is applied to the electron beam passing holes 20', 20' of the second grid electrode 16.

Since 20″ is asymmetrical, 3 passing through this
Each electron beam is subjected to an axially asymmetric focusing action.

Electron beam passing holes 20', 20'' of second grid electric grid 16
, 20'' are vertically long rectangles or vertically long ellipses as shown in FIG.
4", 24"'. The electron beam is further passed through an axially symmetrical focusing lens 25 generated by a subsequent focusing electrode system 14.
', 2♂.

25'', but the axially asymmetric lens 6 vanes 24 , 24 , 24 and the axially symmetrical focusing lens 25'
.

25.25 are combined isometrically into one of three lenses, resulting in an axially asymmetric lens that is strong in the horizontal direction and weak in the vertical direction, as typically shown in FIG. 6 as a composite lens 26. Therefore, when the electron beam 27 passes through the combining lens 26, it receives a strong focusing effect in the horizontal direction and a weak focusing effect in the vertical direction, and the vertical focus point 28 occurs at a point farther than the horizontal focus point 29. This phenomenon acts to cancel out the fact that the electron beam within the deflection magnetic field is focused weakly in the horizontal direction and strongly focused in the vertical direction as the amount of beam deflection increases, as described above.

As a result, even though the beam spot is caused by an electron beam that is largely deflected in the horizontal direction, it is possible to make it close to a perfect circle, and the resolution of the phosphor screen surface is increased, especially on both the left and right sides and in the diagonal area. . Since the distortion of the beam spot appearing near the upper middle of the phosphor screen surface is originally slight, a very clear reproduced image can be obtained over the entire area on the phosphor screen surface.

Above, an embodiment in which the present invention is applied to an in-line color cathode ray tube device has been described, but the object of the present invention is to collect electrons subjected to self-effect in an asymmetric deflection magnetic field. The purpose of this method is to correct the shape distortion of the beam spot caused by the beam, and it can be applied to cathode ray tube devices that operate with one beam or two beams in the same manner as described above.

In addition, in this example, the second focusing lens system constituting the front stage focusing lens system
The electron beam passing hole of the grid electrode in 1. was made into an axially asymmetrical shape. Only the electron beam passing hole of one of the second and third grid electrodes has an axially asymmetric shape;
Even if the electron beam passage holes of other grid electrodes are circular, the same beam spot distortion correction effect as described above can be obtained.

[Brief explanation of the drawing]

Figures 1 (a) and (b) are diagrams showing the relationship between the nonuniform deflection magnetic field distribution and three electron beams, and the 2' quotient is the phosphor screen surface of a color cathode ray tube device that uses the self-focusing method. FIG. 3 is a side sectional view of the electron gun section of an in-line color cathode ray tube device in which the present invention is implemented, and FIG. 4 is a front-stage focusing diagram of the same color cathode ray tube device. A perspective view of the electrode system, Figure 5 is a signal waveform diagram showing the relationship between the deflection current and the voltage, and Figure 6 explains the focusing state of the electron beam by a composite lens that combines the front-stage focusing lens and the rear-stage focusing lens. This is a diagram for 10', 1d", 1d"... cathode, 11...
...control electrode, 12...acceleration electrode system, 13.
...Front-stage focusing electrode system, 14... Back-stage focusing electrode system, 15... First grid electrode, 16...
...Second grid electrode, 17...Third grid electrode, 18', '18', 18''', 19', 19'', 1
d". 2d, 20", 2d//... Electron beam passing hole, Vfoc... Constant focusing voltage, Vfoc...
... Guinamisoku voltage. Name of agent: Patent attorney Masao Nakao and 1 other person No. 1
Ward ((lnotefl)) Figure 2; Figure 4, Figure 5, Figure 6, Procedural Amendment 1 Display of Case 1981 Patent Application No. 81964 2 Name of Invention Cathode Ray Tube Device 3 Person Who Makes Amendment Case and Related patent applications
Appointment Address: Bold 1006 Kadoma, Kadoma City, Osaka Prefecture
(584) Representative of Matsushita Electronic Industries Co., Ltd.
Kiyoshi Miyama -4 Agent 571 Address 1006 Oaza Kadoma, Kadoma City, Osaka [Contact phone number (Tokyo) 453-3111 Patent Branch] 6 Detailed description of the invention in the specification subject to amendment Drawing 6, Amendment Contents (1) The ``fluorescent surface'' on page 4, line 12 of the specification is 1 fluorescent substance.''
Correct and cut. (2) Amend Figure 3 of the drawing as shown in the attached sheet. 11.11

Claims (1)

[Claims] The first focusing electrode system is disposed between the accelerating electrode system and the second focusing electrode system. A constant focusing voltage is applied to the first and third grating electrodes, and the constant focusing voltage is applied to the second grating electrode as the amount of beam deflection increases. Apply a voltage that gradually decreases or increases from the first point. 2nd and 3rd
A cathode ray tube device characterized in that at least one of the grid electrodes has an axially asymmetric electron beam passage hole.