JPH01628A - Method for forming a phosphor screen in a fluorescent display tube - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to a method for forming a phosphor screen in a fluorescent display tube such as a fluorescent dot array tube or a barcode display tube.

(Conventional technology) As shown in FIG. 5, the fluorescent display tube 1 is made of glass.

A substrate 2 made of ceramic, resin, etc., and segment electrodes (anodes) 3 arranged on the substrate 2 in a vertical direction to the plane of the paper.
, a face glass 4 made of a transparent material such as glass that forms a vacuum closed space with the substrate 2, a phosphor screen 5 formed on each segment electrode 3, and an insulating layer on both sides of the arrangement of the phosphor screen 5. Grid electrodes 8, 8 are arranged through 6, 6 and fixed with an insulating material 7.7 such as low melting point glass.
and a tungsten wire 9 as a hot cathode.
It consists of ゜9. Thermionic electrons emitted from the tungsten wire 9 are controlled by the grid electrode 6, guided to specific segment electrodes 3, and collide with the phosphor screen, causing the phosphor screen to emit light.

A method of forming the phosphor screen 5 in a conventional fluorescent display tube will be explained based on FIGS. 6 and 7.

In the segment electrode forming step (FIG. 7(1)), a segment electrode 3 made of aluminum is formed on one surface of the substrate 2 made of a glass plate by, for example, a photoetching method. The segment electrodes 3 are strip-shaped with a width of about 50 μm, and are formed in a row in the longitudinal direction of the substrate (perpendicular to the plane of the paper) with an interval of about 35 μm between adjacent electrodes. , every other one is pulled out to the left and right side edges of the board.

In the insulating layer forming step (FIG. 7 (2)), the layer is formed so as to cover the side edges of the segment electrode 3 in the width direction of the substrate 2, in other words, to expose the center part of the segment electrode 3.
An insulating layer 6 made of thick film insulating glass, for example, lead glass and carbon and having a thickness of about 10 to 20 μl is formed on the upper surface of the substrate 2. The insulating layer 6 is formed by, for example, a screen printing method, and then fired at 500 to 600°C. In the photoresist layer forming step (FIG. 7 (3)), the insulator layer 6
．． The entire segment electrode 3 is covered with a photoresist layer 10 using a spinner or dipping method 6 Then, in the segment electrode exposure step (FIG. 7 (4)), a mask 11 is polymerized on the photoresist layer 10 to form a photoresist layer. After exposing layer 10 to light, it is developed to remove a portion of the layer and expose portion 3a of segment electrode 3. Next, in a phosphor screen forming step (FIG. 7(5)), a phosphor screen 5 is formed on the exposed portion 3a.

The phosphor screen 5 is formed by immersing the nine substrates on which the exposed portions 3a are formed in a liquid in which phosphor particles are dispersed so as to face the counter electrodes at a predetermined distance. There is an electrophoresis method in which a voltage is applied between the two dispersions and the phosphor particles in the dispersion are moved toward the segment electrode 3 by an electric field formed between the two electrodes, and the phosphor particles are deposited on the exposed portion 3a. It is formed by an appropriate method such as a sedimentation method in which a substrate is placed in a dispersed and stirred solution, and the dispersed phosphor particles settle and adhere to the exposed portion 3a.

After drying and fixing this phosphor screen 5, in a photoresist layer removal step, the photoresist layer 10 is removed by firing, for example, with oxygen plasma, leaving the phosphor screen 5 as shown in FIG. 7(6). After this, as shown in FIG. 7(7), grid electrodes 8, 8 are formed.

Incidentally, a fluorescent display tube is required to have uniform precision in dot size on the fluorescent screen 5. Conventional methods for forming phosphor screens have had the problem of not being able to obtain accurate dot sizes. The dot size of the phosphor screen 5 is determined by the formation of the exposed portion 3a in the segment electrode exposure step, as shown in FIG. 7(4). As shown in FIG. 7(3), when the photoresist layer 10 is applied and formed, a step A is created between the insulating layer 6 and the segment electrode 3.

As shown in FIG. 7(4), when the mask 11 is superposed on the photoresist layer 10, poor adhesion occurs between the two layers due to the step A. In such a state, when the photoresist layer 10 is exposed to light, the optical distance between the mask 11 and the photoresist layer 10 to be exposed increases, and the influence of the diffracted light on the mask surface on the photoresist layer 10 increases. , the desired size of the exposed portion 3a of the segment electrode cannot be obtained.

Therefore, the size of the phosphor screen 5 formed by adhering to the exposed portion 3a will be different from the desired size.

In addition, in the phosphor screen forming step shown in FIG. 7(5),
The substrate 2 is immersed in the phosphor particle dispersion, and at this time, phosphor particles adhere not only to the exposed portion 3a but also to the surface of the photoresist layer 10. These adhered particles remain on the substrate and electrodes when the photoresist layer is removed by baking, so they must be removed by polishing or other means.To prevent them from adhering to the photoresist layer, It would be sufficient if a mask exposing only 3a was polymerized onto the photoresist layer 10.

As mentioned above, since there is one step difference A, 1. The adhesion between the two is poor, and the dispersion liquid intrudes into the step indicated by the symbol A in FIG. 7(4).

(Purpose) The present invention was made to solve the above-mentioned problems of the prior art, and its purpose is to provide a method for forming a phosphor screen that can form a phosphor screen with high precision in dot size. Our goal is to provide the following.

(Structure) In order to achieve the above object, the present invention provides at least one row of strip-shaped segment electrodes made of a conductive material on a substrate in a segment electrode forming step, and in a photoresist layer forming step.

The entire surface of the segment electrode array is covered with a photoresist layer, and in the segment electrode exposure step, a mask is brought into close contact with the photoresist layer, and the photoresist layer is exposed and developed to partially cover the photoresist layer. The segment electrodes are removed to expose them in a dot shape, and in a phosphor screen forming step.

Fluorescent particles are attached to the segment electrodes exposed in a dot shape until the mask is brought into close contact with the segment electrodes to form a phosphor screen, and in a photoresist layer removal step, the mask and the photoresist layer are removed.

In the insulating layer forming step, an insulating layer that insulates the grid electrode and the segment electrode is formed along the arrangement direction of the segment electrodes.

The illustrated embodiment will be described in detail below.

FIG. 1 is a flowchart for implementing the present invention, and FIG. 2 is a sectional view showing the process of forming a phosphor screen. The steps will be explained below in order.

Segment Electrode Formation Step As shown in FIG. 2(1), a segment electrode 3 made of aluminum is formed on one surface of a substrate 2 made of, for example, a glass plate by photoetching. This process is the same as before.

Photoresist layer forming step As shown in FIG. 2(2), the segment electrodes 3 are covered with a photoresist layer 10. As the photoresist layer 10, for example, a negative type photoresist for microfabrication OMR-
85 (trade name, manufactured by Tokyo Ohka Kogyo Co., Ltd.) and a positive photoresist for microfabrication OF PR-800 (same trade name) are used. This photoresist layer 10 is formed by spinner or dipping, and then prebaked at an appropriate temperature.

Segment Electrode Exposure Step As shown in FIG. 2(3), a mask 11 is superposed on the photoresist layer 10. When a positive photoresist is used as the mask 11, as shown in FIG. 4, a mask 11 is used in which a slit 11a is formed through which light passes. The slit lla is formed extending in the arrangement direction of the segment electrodes 3, and its width determines one side of the dot on the phosphor screen. When using a negative photoresist, a mask is used in which the slit lla shown in FIG. 4 does not transmit light. In the phosphor screen formation process described below, when electrophoresis is used, a mask with line-shaped slits as shown in Figure 4 is used, and when a phosphor screen is formed using sedimentation, dot-shaped slits are used. A mask having through-holes is used.

Next, as shown in FIG. 2(4), after exposure as shown by the arrow through the mask 11, development is performed to partially remove the photoresist layer, and a portion 3a of the segment electrode 3 (
(hereinafter referred to as the "exposed part"). At this time, since the mask 11 and the photoresist layer 10 are in close contact with each other, there is no influence of diffracted light during exposure, and the exposed portion 3a becomes a highly accurate dot.

Phosphor screen forming process As shown in FIG. 2 (5), the substrate 2 with the mask 11 still attached is immersed in a phosphor particle dispersion solution, and the phosphor particles are transferred to the exposed portion 3a by electrophoresis. to form the fluorescent screen 5. When forming a phosphor screen by the sedimentation method, a mask having through holes instead of slits 11a is used, so that phosphor particles adhere only to the exposed portions 3a. After drying and fixing the fluorescent screen 5, as shown in Fig. 2 (6
), remove the mask 11. At this time, the phosphor particles attached to the mask 11 are removed.

Photoresist Layer Removal Step As shown in FIG. 2 (7), the photoresist layer 10 covering the segment electrodes 3 is removed by appropriate means such as baking. When looking at the substrate 2 after this process is completed, it can be seen that the dot-shaped fluorescent screens 5 are neatly lined up on each of the segment electrodes 3 arranged in a row.

Insulating layer forming process As shown in FIG. 2 (8), the substrate 2 of the segment electrode 3 is
Insulating layers 6, 6 made of thick film insulating glass, for example, lead glass and carbon and having a thickness of about 10 to 20 μI are formed on the upper surface of the substrate 2 so as to cover the side edges in the width direction. Insulating layer 6
, 6 are formed by, for example, a screen printing method.

If it is difficult to directly form the insulating layers 6, 6 alone on the substrate 2, they can be formed integrally on the substrate side surface of the grid electrode 8.8 in advance, as shown in FIG. This assembly may be placed on the substrate 2.
After being polymerized into a substrate 2, as shown in the figure.

It is fixed with insulating material 7,7.

Thereafter, a hot cathode 9 is placed on the substrate 2, as shown in FIG.
, 9 are stretched, and the face glass 8 is polymerized to form a closed space. Finally, when the closed space is evacuated, a fluorescent display tube 1 as shown in FIG. 5 is obtained.

(Effect of the invention) According to one aspect of the present invention, as is clear from the above description.

Since the phosphor screen is attached while the mask for exposing the segment electrodes in the form of dots remains polymerized on the photoresist layer, the desired phosphor screen dot size can be stably obtained. Furthermore, since the phosphor particles adhering to areas other than the dots are removed together with the mask, no phosphor particles remain on areas other than the regular phosphor screen, and clear phosphor screen brightness can be obtained.

[Brief explanation of the drawing]

FIG. 1 is a flowchart showing the steps of the method for forming a phosphor screen of a fluorescent display tube according to the present invention, FIG. 2 is a cross-sectional view showing the above steps, FIG. 3 is a cross-sectional view showing an example of forming an insulating layer, and FIG. FIG. 2 is a perspective view showing an example of a mask. FIG. 5 is a schematic sectional view showing an example of a fluorescent display tube, FIG. 6 is a flowchart showing a conventional phosphor screen forming process, and FIG. 7 is a sectional view showing the same process. DESCRIPTION OF SYMBOLS 1... Fluorescent display tube, 2... Substrate, 3... Segment electrode, 5... Fluorescent screen, 6... Insulating layer, 9... Grid electrode, 10... Magnetic photoresist layer , 11...
·mask. Figure 1 Figure 6 Figure 3

Claims (1)

[Claims] In the segment electrode forming step, at least one row of strip-shaped segment electrodes made of a conductive material is provided on the substrate, and in the photoresist layer forming step, the entire segment electrode row is covered with a photoresist layer, In the segment electrode exposure step, a mask is brought into close contact with the photoresist layer, and the photoresist layer is exposed and developed to partially remove the photoresist layer and expose the segment electrode in a dot shape, In the phosphor screen forming step, phosphor particles are attached to the segment electrodes exposed in dots while the mask remains in close contact to form a phosphor screen, and the mask is removed. In the photoresist layer removal step, the photoresist layer is removed. A method for forming a phosphor screen in a fluorescent display tube, comprising: removing the resist layer, and forming an insulating layer that insulates the grid electrode and the segment electrode along the arrangement direction of the segment electrodes in the insulating layer forming step.