JPH04359846A - Flat plate type image display device - Google Patents

Abstract

PURPOSE:To correct dispersion of the electron beam current reaching a screen by adjusting the transmissivity for each electron beam which has passed through a through hole provided in a drawout electrode. CONSTITUTION:An image display device concerned includes a No.1 convergence electrode divided into a plurality of segments and, outside of a vacuum vessel, a means to control the voltages to be impressed on these segments of the No.1 split electrode. Thereby generation of uneven brightness is prevented.

Description

[Detailed description of the invention]

0001

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a flat panel image display device used in color television receivers, computer terminal displays, and the like.

0002

[Prior Art] In recent years, flat panel image display devices have been actively developed, and liquid crystal displays (LCD), electroluminescent displays (EL), light emitting diode displays (LED), etc. have appeared on the market. It is inferior to color cathode ray tubes in terms of resolution and full color. Therefore, with the aim of displaying color television images on a flat device using an electron beam that can produce high-quality images comparable to that of a cathode ray tube, the screen was divided into matrix-like sections without gaps, and each There is an image display device that deflects and scans an electron beam to cause a phosphor to emit light for each category, creating a color television image as a whole, and development has progressed to the point where it rivals cathode ray tubes in terms of image quality and full color. I'm here.

An example of the above-mentioned conventional image display device will be described below with reference to the drawings.

FIG. 4 is a perspective view showing the basic structure of a conventional example, and shows a state in which the electron beam is not deflected. In FIG. 4, 1 is a back electrode, 2 is a linear hot cathode as an electron beam source, 3 is an electron beam extraction electrode, 4 is a signal electrode, 5 is a first focusing electrode, 6 is a second focusing electrode, and 7 is a horizontal The deflection electrode 8 is a vertical deflection electrode, and these components are housed in a vacuum container (not shown).

As shown in the figure, a plurality of linear hot cathodes 2 are provided in parallel at regular intervals. These linear hot cathodes 2 are composed of, for example, tungsten wires with an oxide cathode material coated on their surfaces. Further, the back electrode 1 is made of a plate-shaped conductive material, and is provided in parallel to the linear hot cathode 2 .

The extraction electrode 3 is a plate-shaped electrode that faces the back electrode 1 with the linear hot cathode 2 in between, and has a through hole for an electron beam at a location corresponding to the linear hot cathode 2.

The signal electrode 4 consists of a row of vertically elongated conductive plates installed at predetermined intervals at positions facing each of the through holes in the extraction electrode 3. A similar through hole is provided at a position opposite to the through hole of the electrode 3.

The first focusing electrode 5 is made of a conductive plate having through holes at positions opposite to the through holes of the signal electrode 4.

The second focusing electrode 6 is a conductive plate having a slit hole at a position opposite to the through hole of the first focusing electrode 5. The slit holes of the second focusing electrode 6 may be slit-shaped with respect to the electron beam, and do not necessarily need to be connected in a vertical line as shown in FIG.

The horizontal deflection electrode 7 is composed of two comb-shaped conductors that are interlocked with each other on the same plane with a space between them, and the space created between the two comb-shaped conductors is , facing the slit hole of the second focusing electrode 6.

The vertical deflection electrode 8 also has a structure in which two comb-shaped conductive plates are interlocked with each other with a space interposed therebetween on the same plane.

The intervals between the respective electrodes from the extraction electrode 3 to the vertical deflection electrode 8 are made equal.

The screen 12 is made by coating the inner surface of the glass container 10 with a phosphor 11 (not shown in FIG. 4) that emits light when irradiated with an electron beam, and adding a metal back layer (not shown) thereon. It consists of

[0014]

However, in the above structure, the amount of electron beams reaching the screen 12 differs from beam spot to beam spot due to variations in the precision of the through holes of the extraction electrode 3, which causes uneven brightness. This was a problem with image quality.

The object of the present invention is to solve the above-mentioned problems and provide a flat panel image display device free from uneven brightness.

[0016]

[Means for Solving the Problems] In order to achieve the above object, the flat panel image display device of the present invention includes a first focusing electrode divided into a plurality of parts, and a divided part of the first focusing electrode outside the vacuum container. The configuration includes means for controlling the voltage applied to each individual.

[0017]

[Operation] According to the above configuration, the transmittance of the electron beam at the second focusing electrode changes substantially linearly with respect to the potential of the first focusing electrode, so that By manipulating the applied potential, the amount of electron beams reaching the screen can be easily corrected.

[0018]

Embodiments An embodiment of the present invention will be described below with reference to FIGS. 1 and 2. FIG. 1 is a sectional view showing the internal structure of an embodiment of the flat panel image display device of the present invention, and shows a state in which the electron beam is not deflected. In the electrode structure, elements having the same functions as those in the conventional example are given the same numbers. In FIG. 1, reference numeral 5 denotes a first focusing electrode, which is made of a conductive plate having through holes at positions opposite to the through holes of the signal electrode 4, and is divided into thin strips for each row of openings through which the electron beam passes. ing. Note that 9 is an electron beam.

FIG. 2 is a perspective view showing only the first focusing electrode 5 in FIG.
This shows the connection status. The first focusing electrode 5 is 5
It is divided into multiple parts such as a, 5b, and so on. Further, a voltage control circuit 13 is connected to each of the first focusing electrodes 5a, 5b, . . . so that a voltage can be applied to each divided individual first focusing electrode 5. The voltage control circuit 13 can apply individual voltages to the first focusing electrodes 5a, 5b, . . . based on correction data input from the outside. Further, the voltage control circuit 13 may be one that stores correction data internally.

The operation of the flat panel image display device configured as described above will be explained. First, in FIG. 1, the linear hot cathode 2 is A sheet-like electron beam 9 can be generated from scratch. However, only a part of the electron beam trajectory is shown in the figure.

The sheet-like electron beam 9 is then horizontally divided into a plurality of pieces by the through-hole of the extraction electrode 3 and reaches the through-hole of the signal electrode 4. By controlling the voltage over time, the amount of electron beam passing is adjusted individually for each electron beam according to the video signal for displaying the picture element.

The electron beam 9 that has passed through the signal electrode 4 then reaches the vicinity of the first focusing electrode 5 and the second focusing electrode 6, and crosses over in the horizontal direction due to the potential applied thereto. In this embodiment, the cross-over occurs in the horizontal direction before the first focusing electrode 5. Therefore, the trajectory of the electron beam widens horizontally before reaching the second focusing electrode 6, and a portion of the electron beam collides with the second focusing electrode 6 and does not reach the screen 12. For the electron beam that was able to pass through those through holes and slit holes, the first focusing electrode 5,
After being focused and shaped by the second focusing electrode 6, it is electrostatically deflected horizontally and vertically as required by the potential difference (deflection voltage) applied between the conductors of the horizontal deflection electrode 7 and between the conductors of the vertical deflection electrode 8. be done.

Further, a high voltage of, for example, 10 kV is applied to the metal back layer of the screen 12, and the electron beam 9 is accelerated and collides with the metal back, causing the phosphor to emit light. However, in this state, the amount of electron beams reaching the screen 12 differs from beam spot to beam spot due to variations in the precision of the through holes of the extraction electrode 3.

If the voltage applied to the first focusing electrode 5 is changed, the extent to which the electron beam spreads after crossover changes, and the transmittance of the electron beam at the second focusing electrode 6 changes. The relationship will be explained using FIG. 3.

FIG. 3 shows an example of the results of an experimental study on the relationship between the potential applied to the first focusing electrode 5 and the electron beam transmittance at the second focusing electrode 6. The slope and intercept of the figure change somewhat depending on the voltage applied to other electrodes, the shape of the hole, etc. The transmittance here is the value obtained by dividing the amount of current of the electron beam passing through the slit hole of the second focusing electrode 6 by the amount of current of the electron beam passing through the through hole of the extraction electrode 3. As shown in FIG. 3, the transmittance of the electron beam at the second focusing electrode 6 changes substantially linearly with the potential of the first focusing electrode 5. Further, as shown in FIG. 2, the voltage control circuit 13 controls the first focusing electrodes 5a, 5b, and the like based on correction data input from the outside.
The configuration is such that an appropriate voltage can be applied to...

Therefore, by adjusting the transmittance of each electron beam passing through the through hole of the extraction electrode 3 based on the relationship shown in FIG. 3, variations in the electron beam current reaching the screen 12 can be corrected. be able to. Moreover, in this embodiment, the transmittance changes substantially linearly with respect to the potential of the first focusing electrode 5, so that the voltage can be easily controlled.

For example, if the average electron beam current in this embodiment is set to 4.6 μA per spot, when the potential of the first focusing electrode 5 is 55 V, the beam current at a certain spot is 4.2 μA. In this case, the transmittance at that time is 52.5% from FIG. 3. Therefore, by setting the potential of the first focusing electrode 5 to 65V, the transmittance becomes 57.5%, which is 4.2÷52.5×57.5=4.
Beam current can be corrected to 6μA.

Note that if we focus only on the electron beam current, similar transmittance control is possible with the voltage applied to the signal electrode 4, but the electron beam transmittance at the second focusing electrode 6 relative to the potential of the signal electrode 4 is It has been found that the change is non-linear and the diameter of the electron beam spot on the screen 12 is significantly enlarged, making it impractical.

[0029]

[Effects of the Invention] According to the present invention, the first focusing electrode is divided into a plurality of parts, and a means for controlling the voltage applied to each of the divided first focusing electrodes is provided outside the vacuum container. By this, it is possible to obtain a flat panel image display device with sufficiently less unevenness in brightness.

[Brief explanation of drawings]

FIG. 1 is a sectional view of essential parts showing the configuration of an embodiment of a flat panel image display device of the present invention.

[Fig. 2] Explanatory diagram of the first focusing electrode of the same embodiment device

[Figure 3]
Relationship diagram between the potential applied to the first focusing electrode and the electron beam transmittance at the second focusing electrode in the same example device

FIG. 4 is a perspective view showing the configuration of a conventional flat panel image display device.

[Explanation of symbols]

1　Back electrode 2 Linear hot cathode 3 Extraction electrode 4 Signal electrode 5 First focusing electrode 6 Second focusing electrode 7 Horizontal deflection electrode 8 Vertical deflection electrode 9　Electron beam 10 Glass container 11. Phosphor 12 Screen 13 Voltage control circuit

Claims (6)

[Claims] 1. A vacuum container includes an electron source, an electron beam control electrode group for extracting and controlling a beam from the electron source, and a screen that emits light when the electron beam hits the electron beam, the electron beam control electrode group comprising: A horizontal deflection electrode and a vertical deflection, at least a part of which is composed of a first focusing electrode divided into a plurality of parts, a second focusing electrode having a plurality of slit-like through holes, and a plurality of conductive plates located on the same plane. What is claimed is: 1. A flat panel image display device, comprising a voltage control means for applying a voltage to each divided individual of said first focusing electrode outside said vacuum container. 2. The flat panel image display device according to claim 1, wherein the voltage control means includes means for externally inputting correction data for the amount of electron beam. 3. The flat panel image display device according to claim 1, wherein the voltage control means includes storage means for storing therein correction data for the amount of electron beam. 4. The voltage control means has a function of controlling the voltage based on at least the relationship between the voltage applied to the first focusing electrode and the rate at which the electron beam passes through the through hole of the second focusing electrode. 4. The flat panel image display device according to claim 1, further comprising: a flat panel image display device; 5. Claim 4, wherein the voltage applied to the first focusing electrode and the rate at which the electron beam passes through the through hole of the second focusing electrode vary substantially linearly. The flat panel image display device described above. 6. The electron beam crosses over in a direction perpendicular to the slit direction of the through hole of the second focusing electrode before passing through the through hole of the first focusing electrode. 5. The flat panel image display device according to any one of 5.