JPS61245438A - Formation of fluorescent screen of fluorescent character display tube - Google Patents

Abstract

PURPOSE:To enable a high quality fluorescent screen to be formed treating a substrate on which segment electrodes are arranged in line and an opposing electrode in a liquid which includes diffused phosphor particles, while surrounding said substrate and the opposing electrode with a screen which has tiny holes of diameters nearly equal to the mean diameter of the phosphor particles. CONSTITUTION:Phosphor particles are deposited on each of many segment electrodes SP which are arranged in one or more lines in one direction on a substrate 1 to form a fluorescent screen of a fluorescent character display tube. The substrate 1 and an opposing electrode TP are surrounded by a screen 4, whose structure includes tiny holes of diameters nearly equal to the mean diameter of phosphor particles, and are dipped in a liquid 2 which includes diffused phosphor particles. A voltage is applied across the electrode 1 and TP to cause electrophoresis of the phosphor particles and make them deposit on the electrodes SP. Thus high quality fluorescent screen with no dispersion of performance can be obtained by preventing phosphor particles of relatively large diameters from depositing.

Description

[Detailed description of the invention] (Technical field) The present invention relates to a method for forming a fluorescent surface of a fluorescent display tube.

(Prior art) A fluorescent display tube has a fluorescent surface formed on a large number of segment electrodes arranged in a single row or multiple rows in one direction, and is sealed in a vacuum container together with a hot cathode. While generating electrons, a positive voltage is selectively applied to the segment electrodes according to the information to be displayed, and the thermoelectrons are attracted to the selected segment electrodes, and the attracted thermoelectrons collide with the fluorescent surface. This is a display element that displays information using the fluorescent light emitted when the display is performed, and is known as a bar code display tube or a fluorescent dot array tube.

The specific structure of the fluorescent display tube is disclosed in Japanese Patent Application No. 60-45, for example.
No. 169.

In such a fluorescent tube, a so-called electrodeposition technique using electrophoresis is disclosed as a method of forming a fluorescent surface on the segment electrodes, for example, in Japanese Utility Model Publication No. 57-55728. The outline of this method is to put a dispersion liquid in which a phosphor is dispersed in a liquid bath, place a counter electrode and a substrate having segment electrodes to which the phosphor is attached into the dispersion liquid, and apply a voltage. This is a method in which a fluorescent substance is migrated onto and attached to segment electrodes.

Here, as a dispersion liquid, for example, phosphor particles (ZnO, Zn has a particle size of 5 μm) and a trace amount of aluminum nitrate (A ml (NO3)a・9H,
0) is used.

Aluminum nitrate dissociates into AQ"+ and NO; in the dispersion, and the AQ ions adhere to the phosphor particles, thereby serving to positively charge the phosphor particles.

As shown in FIGS. 4 and 5, a substrate 1 having segment electrodes SP and a counter electrode TP are immersed in the dispersion liquid 2,
They are arranged opposite to each other in the dispersion liquid 2.

A power source 3 is connected between the segment electrode SP and the counter electrode TP so that the segment electrode SP side is negative. Further, a stirring means rotated by a motor M is provided in the dispersion liquid 2.

However, even if a fluorescent surface is formed on the segment electrode SP with such a configuration, it is difficult to uniformly adhere the fluorescent material to a minute area if the fluorescent material particle diameters are uneven.

In general, the phosphor particle size usually has a certain distribution, and those with an average particle size of 7 to 10 μm are often used, but the phosphor surface to be attached is minute (for example, 50
(approximately 50 .mu.m@2), if relatively large particles are mixed in with the phosphor particles, they will adhere and electrodeposit in a way that protrudes from the phosphor surface.

When such electrodeposition is performed, the unevenness of the light emitting area causes a disadvantage that the light emitting power of each segment varies.

(Objective) Therefore, an object of the present invention is to provide an improved method for forming a fluorescent surface that can form a high-quality fluorescent surface on each segment electrode without causing variations in the electrodeposited area. be.

(Structure) In order to achieve the above-mentioned object, the present invention surrounds the phosphor with a screen having a pore structure having at least the same diameter as the average particle size of the phosphor, and then performs electrophoresis to form a phosphor surface. It is characterized by this.

Hereinafter, a detailed explanation will be given based on one embodiment of the present invention.

Example 1 (see Figure 1).

As shown in the figure, a box-shaped screen 4 having a pore structure (mesh-like surface) approximately equal to the average particle diameter of the phosphor is placed in a liquid bath containing a dispersion 2. A substrate 1 having segment electrodes SP and a counter electrode TP are placed therein, and an electrodeposition method is performed.

Example 2 (see Figure 2).

This example is basically the same as Example 1 above.

The difference is that only the substrate 1 is left inside the screen 4 and the counter electrode TP is placed outside the screen 4.

Example 3 (see Figure 3).

In this example, the screen 40' is made of a conductive material and has the function of a counter electrode, so that the positive voltage of the power source 3 is applied to the screen 40'.

In this example, since the counter electrode and the screen are used both, there is an advantage that the configuration is simple.

In Examples 1 to 3 above, since the segment electrodes are surrounded by the screen, only the phosphor particles with a specified particle size or less corresponding to the pores of the screen adhere to the segment electrode surface, resulting in uniform fluorescing. surface.

In other words, it is possible to form a phosphor surface with a constant area and less protrusion of the phosphor from the electrode.

(Effects) According to the present invention, since the particle diameters of the phosphors constituting the phosphor surface are uniform, it is possible to form a minute phosphor surface evenly and with high precision, and the dispersion of the light emitting power of each segment can be reduced. can be resolved.

[Brief explanation of drawings]

1 to 3 are diagrams showing the relationship between electrodes and a screen, each illustrating an embodiment of the present invention, FIG. 4 is a diagram illustrating the electrodeposition method according to the prior art, and FIG. 5 is a perspective view of the electrodes. It is. 2...Dispersion liquid, 4.40'...Screen, SP・
...Segment electrode.

Claims (1)

[Claims] In a fluorescent display tube, a substrate on which a large number of segment electrodes are arranged in one or more rows in one direction, and a counter electrode are immersed in a dispersion liquid in which fluorescent particles are dispersed. and arranging the segment electrode row and the counter electrode with an appropriate spacing between them, applying a voltage between the segment electrode row and the counter electrode,
A method in which fluorescent particles are electrophoresed and adhered to individual segment electrodes to form a fluorescent surface, the method comprising forming at least an array of segment electrodes approximately the same size as the average particle size of the fluorescent particles in the dispersion. 1. A method for forming a fluorescent surface of a fluorescent display tube, comprising performing the electrophoresis while surrounding the screen with a screen having a pore structure of the same diameter.