JPH02177239A - Flat CRT - Google Patents

Abstract

PURPOSE:To improve a withstand voltage of a flat CRT by disposing a spacer electrode plate which is provided with through holes corresponding to an electron beam and an insulating protrusion on at least a surface of the electrode plate between a rear plate and a face plate as sandwiched therebetween. CONSTITUTION:A through hole 2 corresponding to a picture element is provided on a metal plate 1 and also an insulating protrusion 3 on both surfaces of the metal plate 1. The through hole 2 is provided on the metal plate 1 which is an alloy plate of Ni of 42%, Cr of 6N and Fe of 52% by photo-etching. The insulating protrusion 3 is formed by printing a crystallized flit glass with a low melting point to be formed with thickness of 200mum by screen printing and baking it for 30 minutes at 450 deg.C. On a surface of a spacer electrode plate 1 thus formed, a rear plate 4 in which a surface electron source 5 is formed on a glass plate 4 is provided. While, a face plate 6 on which ZnO: Zn fluorescent material 7 is applied is provided on the other surface of the spacer electrode plate 1. The periphery of the spacer electrode plate 1 is sealed with a flit glass to exhaust air therefrom. Therefore, a withstand voltage is extremely improved. Furthermore, stray electrons are shielded to converge an electron beam so as to make the beam be incident to the fluorescent material 7 for eliminating crosstalk and displaying an image with better colour purity.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a spacer for a flat CRT using a surface electron source.

A flat plate type CRT using a conventional electron source has a high vacuum inside the tube, so atmospheric pressure is applied between the back plate of the glass container and the face plate, and the structure must be able to withstand this. Relatively small flat type CR with a screen size of about 0 inches or less
In T, the thickness of the glass container is increased.For example, in the case of a screen size of 10 inches, the thickness of the glass container is increased by 10 inches.
~I 2mm to withstand atmospheric pressure. However, flat-type CR with a larger screen size
In T, a self-supporting flat plate CRT in which a spacer or a support plate is inserted into the tube has been reported. For example, Japanese Patent Application Laid-Open No. 58-48559 discloses a technique in which a rod-shaped spacer is inserted between an X-Y matrix electrode that controls an electron beam and a face plate that applies a high voltage. The developed hybrid plasma method (SID'8G dicist, PP410-41
In 3), a lattice-shaped insulating spacer with holes corresponding to each pixel is used.

Problems to be Solved by the Invention The main conditions required for the spacer inserted between the electron beam control electrode and the face plate are (1) withstand high voltage, (2) not affect image quality, and (3) atmospheric pressure. The structure must be able to withstand In order to obtain sufficient brightness for an image display device, it is necessary to accelerate the electron beam at the highest possible voltage. However, conventional spacers have a limited withstand voltage, and if an acceleration voltage of 4 KV or more is applied, discharge occurs between the electrodes, and the practical limit is 2 to 3 KV.

The problem is that the withstand voltage between the electrodes in vacuum, especially the withstand voltage due to creeping discharge generated on the surface of the spacer, is low. It is known that the withstand voltage Vs of the spacer is determined by the following experimental formula, where d is the thickness of the spacer and m is the proportionality constant.

V s = A d ""-(+) That is, the withstand voltage Vs of the spacer is not proportional to the thickness d of the spacer but is proportional to d I t Q. Therefore, in order to double the withstand voltage Vs, it is necessary to quadruple the thickness of the spacer. Increasing the thickness of the spacer not only makes processing difficult and increases manufacturing costs, but also causes problems such as lower processing accuracy and lower image quality.

Means for Solving the Problems A planar electron source in which electron sources are arranged corresponding to each intersection of an X-Y matrix electrode, and an electrode having through holes corresponding to the electron sources between the face plate coated with a phosphor. A spacer electrode plate having a convex portion of an insulator on at least one surface of the plate is inserted.

The voltage applied to the face plate is divided and applied to the electrode plate serving as a spacer. Furthermore, when applying a high voltage to the face plate, a plurality of the spacer electrode plates are superimposed.

There is a relationship shown by equation (1) between the working spacer's withstand voltage Vs and the spacer's thickness d. Divide the thickness of the spacer into 2, 3
Division - ◆ When dividing the face plate into n parts, inserting an electrode plate between each divided spacer, and dividing the voltage applied to the face plate and sequentially applying it to each electrode plate, the withstand voltage Vs when divided into n parts is V s :=A (n * d) ”2-----(2
).

In the simplest case, n=2, that is, divide the spacer thickness into two,
If one electrode plate is inserted between them and the accelerating voltage is divided into two and applied, a withstand voltage 1.4 times higher can be obtained. In addition, as another effect, the electron beam extracted from the surface electron source generally diverges and enters the phosphor corresponding to the adjacent pixel, causing so-called crosstalk and deteriorating the image quality. li! ji′J! : When an electrode plate with a through hole corresponding to the spacer is inserted, it not only blocks stray electrons, but also creates a lens effect that focuses the electron beam by the voltage applied between the spacer electrode plate and the face plate, and the electron beam is focused on the phosphor surface. It is focused and incident.

In particular, when color display is performed by arranging color phosphor stripes, there is no reduction in color purity due to crosstalk.
Extremely effective.

Embodiments Embodiment 1 FIG. 1 shows an embodiment of a spacer electrode plate according to the present invention. Through holes 2 corresponding to pixels are provided in the metal plate 1, and the electrode plate 1
An insulator convex portion 3 is provided on both sides of the insulator. Metal plate 1 is made of 42-6 alloy with a thickness of 100μ, 42% nickel and 6% chromium.
, 52% iron alloy) plate by photo-etching technology.
A through hole 2 is provided. The insulator convex portion 3 was formed by screen printing crystalline low melting point frit glass, forming a thickness of 200 μm on both sides, and then firing at 450°C for 30 minutes.

Flat plate type C using the spacer electrode plate formed in this way
A part of the cross section of RT is shown in FIG. The spacer electrode plate is inserted in a sandwich-like manner between the back plate 4 having surface electron sources 5 formed on the surface of the glass plate 4 and the face plate 6 coated with ZnO: Zn phosphor 7, and surrounded by low melting point frit glass. The container was sealed and then evacuated under vacuum.

When a voltage V is applied between the surface electron source 5 and the phosphor (positive) of the flat CRT constructed in this way, and 1/2 of the voltage V/2 is applied to the spacer electrode plate 1, a single cell with a thickness of 400 μm is obtained. When a layer spacer was used, it was possible to apply a withstand voltage of about 1.5 times up to 6 kV, which was about 4 kV.

Example 2 FIG. 3 shows an example in which two spacer electrode plates shown in FIG. 1 are superimposed. The spacer electrode plates 8 and 9 have through holes at predetermined positions, and are formed by screen printing and firing a 200 μm thick low melting point frit glass. Therefore, the distance between the surface electron source 5 and the first spacer electrode plate 8 is 2
In country 00μ, the distance between the first spacer electrode plate 9 and the second spacer electrode plate 9 was 400 μm1, and the distance between the second spacer electrode plate 9 and the phosphor 7 was 200 μm. With this configuration, 3 kV is applied between the surface electron source 5 and the spacer electrode plate 8.
, 4 kV could be applied between the spacer electrode plates 8 and 9, and 3 tv could be applied between the spacer electrode plate 9 and the phosphor, making it possible to apply a high voltage of 10 kY in total. This withstand voltage is about twice the withstand voltage of 5 to 61 rV of a conventional spacer with a thickness of 800 microns made of only an insulator.

In the embodiment shown in FIG. 3, a voltage of 1 to 1,5 kV is applied between the surface electron source and the spacer electrode plate 8, a voltage of 4 kV is applied between the spacer electrode plates 8 and 9, and a voltage of 4 kV is applied between the spacer electrode 9 and the phosphor. 1.5-2 kVl Total 6.5-7.5kY
applied. In this way, if the electric field strength between the spacer electrode plates 8 and 9 (100 kV/cm) is made larger than the electric field strength between the surface electron source and the spacer electrode plate (50 kV/c), a strong A focusing lens occurs,
The electron beam was focused onto the phosphor surface, and crosstalk was significantly improved. Furthermore, by applying such a voltage, the influence of the electric field for accelerating the electron beam applied to the field emission cold cathode can be reduced,
This is extremely effective in preventing cold cathode malfunctions (electron emission from cold cathodes other than the cold cathode to which a signal voltage is applied).

In this example, a 42-6 alloy plate was used as the spacer metal plate. This is to match the thermal expansion coefficient of the low melting point frit glass that forms the insulator convex portion and the thermal expansion coefficient of the back glass plate and face plate glass plate, but if the thermal expansion coefficient is close to these The spacer metal plate is not limited to 42-6 alloy.

The low melting point frit glass that forms the insulator convex part is preferably a crystalline glass that has a high softening point when fired, but it is preferable to use a low melting point frit glass that does not melt or soften during the process of sealing the glass container. Any glass can be used.

Further, in this embodiment, the insulator convex portions are arranged relatively densely, but the protrusions 3 may be of any type as long as they can withstand the atmospheric pressure applied to the glass container, and for example, have an area of 200μ5×2
If the convex portion is 00μ■, it is sufficient to arrange it at a ratio of one per 2 cm square.

Although the convex portion 3 is provided between pixels so as not to affect the image quality, the image quality deteriorates due to assembly errors, slight positional deviations, etc. that occur during the manufacturing process.

To minimize such image quality deterioration, color flat plate C
In the case of RT, it is desirable to configure the convex portion 3 to be located between blue phosphor striped pixels with low visibility.

Moreover, if the protrusions 3 are arranged regularly, even if the influence of the protrusions is slight, it will be easily recognized as one pattern and will be easily noticed. In order to improve such image quality deterioration, it is most effective to align the convex portions between the pixels of the blue phosphor stripe and at the same time arrange the convex portions irregularly. Furthermore, if the screen size is large, dividing the spacer electrode plate into multiple parts along the longitudinal direction of the color phosphor stripes will prevent misalignment due to the difference in thermal expansion coefficient between the back and face plates and the spacer electrode plate. It can be prevented. In this case, it is not possible to prevent the color phosphor stripe from being misaligned in the longitudinal direction, but color mixing with adjacent phosphors of other colors does not occur, and an image with good color purity can be obtained.

Effects of the Invention According to the present invention, at least one spacer electrode plate having a convex portion of an insulator on at least one surface of the electrode plate having a through hole corresponding to a surface electron source is provided between the back plate and the face plate. By inserting it in a sandwich-like manner, the withstand voltage can be significantly improved. Furthermore, since stray electrons can be blocked and the electron beam can be focused and made incident on the phosphor, crosstalk does not occur and an image with good color purity can be displayed.

[Brief explanation of the drawing]

FIG. 1 is a perspective view of a spacer electrode plate used in a flat CRT according to an embodiment of the present invention, FIG. 2 is a cross-sectional view of a main part of a flat CRT according to the same embodiment, and FIG. It is a sectional view of an example. 1...Spacer electrode substrate, 2...Through hole, 3...
...Insulator convex part.

Claims (7)

[Claims] (1) A back plate with a two-dimensional electron source (hereinafter referred to as a surface electron source) in which electron sources are arranged corresponding to each intersection of the X-Y matrix electrodes, and a face plate coated with phosphor face each other. In the flat plate CRT, a spacer electrode plate having a convex portion of an insulator on at least one surface of an electrode plate having a through hole corresponding to the electron source is inserted in a sandwich shape between the back plate and the face plate. A flat plate CRT characterized by: (2) The flat CRT according to claim 1, characterized in that it is constructed by stacking a plurality of spacer electrode plates. (3) The flat CRT according to claim 1, wherein the spacer electrode plate is divided into a plurality of pieces along the longitudinal direction of the color phosphor stripes. (4) The flat CRT according to claim 1, wherein the convex portion of the insulator provided on the spacer electrode plate is provided at a position corresponding to the blue phosphor stripe. (5) The flat CRT according to claim 1, wherein the convex portions of the insulator provided on the spacer electrode plate are provided irregularly. (6) Claim 1 characterized in that a voltage obtained by dividing the voltage applied between the electron source and the phosphor is applied to the spacer electrode plate.
The flat type CRT described in . (7) The flat plate type C according to claim 6, wherein the electric field intensity between the surface electron source and the first spacer electrode plate is smaller than the electric field intensity between the first spacer electrode plate and the phosphor surface (anode).
RT.