JP2612859B2 - Method of forming phosphor screen in fluorescent display tube - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to a method for forming a fluorescent screen in a fluorescent display tube such as a fluorescent dot array tube and a bar code display tube.

(Prior Art) As shown in FIG. 5, a fluorescent display tube 1 is composed of a substrate 2 made of glass, ceramic, resin or the like, and segment electrodes (anodes) 3 arranged on the substrate 2 in a vertical direction on a paper surface. When,
A face glass 4 made of a transparent material such as glass which forms a vacuum closed space with the substrate 2, fluorescent screens 5 formed on the individual segment electrodes 3, insulating layers 6 on both sides of the arrangement of the fluorescent screens 5, A grid electrode 8,8 is provided with an insulating material 7,7 such as low-melting glass or the like, and is provided with a tungsten wire 9,9 as a hot cathode (cathode). Thermions emitted from the tungsten wire 9 are controlled by the grid electrode 6 so that the specific segment electrode 3
And cause the phosphor screen to emit light by colliding with the phosphor screen.

The method of forming the fluorescent screen 5 in the conventional fluorescent display tube is described in the sixth.
Explanation will be made based on FIG. 7 and FIG.

In the segment electrode forming step (FIG. 7 (1)),
A segment electrode 3 made of aluminum is formed on one surface of a substrate 2 made of a glass plate by, for example, a photoetching method. The segment electrodes 3 are in the form of strips having a width of about 50 μm, and are formed in a line in the longitudinal direction of the substrate (perpendicular to the plane of the paper) at an interval of about 35 μm between adjacent electrodes. Every other is drawn to the left and right side edges of the substrate.

In the insulating layer forming step (FIG. 7 (2)), the thick electrode is formed so that the side edge of the segment electrode 3 in the width direction of the substrate 2 covers the waist, in other words, the central part of the segment electrode 3 is exposed. An insulating layer 6 made of insulating glass such as lead glass and carbon and having a thickness of about 10 to 20 μm is formed on the upper surface of the substrate 2. The insulating layer 6 is formed, for example, by a screen printing method, and then fired at 500 to 600 ° C. In a photoresist layer forming step (FIG. 7 (3)), the insulator layer 6 and the segment electrodes 3 are entirely covered with a photoresist layer 10 by a spinner or a dipping method. Then, in the step of exposing the segment electrode (FIG. 7 (4)), the photoresist layer 10 is exposed by exposing the mask 11 to the photoresist layer 10 and then developed to remove a part of the layer. Then, a part 3a of the segment electrode 3 is exposed. 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 substrate on which the exposed portions 3a are formed in a liquid in which phosphor particles are dispersed, facing the counter electrode at a predetermined interval, and arranging the row of the segment electrodes 3 and the counter electrode. A voltage is applied between them, the phosphor particles in the dispersion are moved toward the segment electrode 3 by the electric field formed between the two electrodes, and the electrophoresis method of attaching the phosphor particles to the exposed portion 3a, The substrate is placed in a liquid that has been dispersed and stirred, and the dispersed phosphor particles are formed by an appropriate method such as a sedimentation method in which the phosphor particles settle and adhere to the exposed portion 3a. After the fluorescent screen 5 is dried and fixed, in a photoresist layer removing step, the photoresist layer 10 is removed by baking with, for example, oxygen plasma, as shown in FIG. 7 (6).
The phosphor screen 5 is left. Thereafter, as shown in FIG. 7 (7), grid electrodes 8, 8 are formed.

By the way, the fluorescent display tube is required to have uniform accuracy of the dot size of the fluorescent screen 5. The conventional phosphor screen forming method has a problem that an accurate dot size cannot be obtained. The dot size of the phosphor screen 5 is determined by
As shown in FIG. 7 (4), this is the formation of the exposed portion 3a in the segment electrode exposing step. As shown in FIG. 7 (3), when the photoresist layer 10 is formed by coating, since the insulating layer 6 is formed first, only the thickness of the insulating layer 6 is required.
A step occurs between the segment electrode 3 and the step, and the step A results in the step A in the photoresist layer 10. Then, as shown in FIG. 7 (4), when the mask 11 is superimposed on the photoresist layer 10, poor adhesion due to the step A occurs between the two. When the photoresist layer 10 is exposed in such a state, the optical distance between the mask 11 and the photoresist layer 10 to be exposed increases, and the effect of diffracted light on the mask surface on the photoresist layer 10 increases. However, the size of the desired exposed portion 3a of the segment electrode cannot be obtained.
Therefore, the size of the phosphor screen 5 formed on the exposed portion 3a is different from the desired size.

Further, in the phosphor screen forming step shown in FIG. 7 (5), the substrate 2 is immersed in the phosphor particle dispersion liquid. At this time, not only the exposed portion 3a but also the photoresist layer 10 is formed. Phosphor particles also adhere to the surface. When the photoresist layer is removed by baking, the adhered particles remain on the substrate or the electrode, and must be removed by means such as polishing. As a measure for preventing adhesion to the photoresist layer, a mask exposing only the exposed portion 3a may be polymerized on the photoresist layer 10. However, as described above, since the mask is present at the step A, both of them can be used. The adhesiveness is poor, and the dispersion liquid infiltrates the step indicated by reference symbol A in FIG. 7 (4).

(Purpose) The present invention has been made to solve the above-mentioned problems of the prior art, and an object of the present invention is to form a phosphor screen capable of forming a phosphor screen with an accurate dot size. It is to provide a method.

(Structure) In order to achieve the above object, according to the present invention, in a segment electrode forming step, at least one row of strip-shaped segment electrodes made of a conductive material is provided on a substrate, and in the photoresist layer forming step, the segment electrode is formed. The entire column is covered with a photoresist layer, and in a segment electrode exposure step, a mask is adhered to the photoresist layer, and the photoresist layer is exposed and developed to partially remove the photoresist layer. Exposing the segment electrodes in the form of dots, and forming a phosphor screen by attaching phosphor particles to the segment electrodes that are exposed in the form of dots while keeping the mask in close contact in the phosphor screen forming step. In the layer removing step, the mask and the photoresist layer are removed. Along the poles of the arrangement direction, an insulating layer for insulating the grid electrode and the segment electrode, and performing this insulating layer formation step to the final step.

 Hereinafter, the illustrated embodiment will be described in detail.

FIG. 1 is a flowchart for carrying out the present invention.
FIG. 2 is a sectional view showing each step of forming a phosphor screen. Hereinafter, description will be made in the order of steps.

Segment Electrode Forming Step As shown in FIG. 2A, a segment electrode 3 made of aluminum is formed on one surface of a substrate 2 made of, for example, a glass plate by a photoetching method. This step is the same as the conventional one.

Photoresist Layer Forming Step As shown in FIG. 2 (2), the segment electrode 3 is covered with a photoresist layer 10. As the photoresist layer 10, for example, a negative working photoresist OMR-85 for fine processing is used.
(Trade name, manufactured by Tokyo Ohka Kogyo Co., Ltd.) or a positive type photoresist OFPR-800 (trade name) for fine processing. The photoresist layer 10 is prebaked at an appropriate temperature after being formed by spinner or dipping.

Segment electrode exposure step As shown in FIG. 2 (3), a mask 11 is polymerized on the photoresist layer 10. When a positive photoresist is used as the mask 11, as shown in FIG. 4, a mask having a slit 11a through which light passes is used. Slit 1
1a is formed so as to extend in the arrangement direction of the segment electrodes 3, and the width thereof determines one side of the dot on the phosphor screen. The mask when using a negative photoresist is
A type in which the slit 11a shown in FIG. 4 does not transmit light is used. In the phosphor screen forming step described below,
When an electrophoresis method is used, a mask having a linear slit as shown in FIG. 4 is used, and when a phosphor screen is formed by a sedimentation method, a mask having a dot-like through hole is used. Can be

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

Phosphor Screen Forming Step As shown in FIG. 2 (5), the substrate 2 with the mask 11 adhered thereto is immersed in a phosphor particle dispersion solution, and the phosphor particles are exposed to the exposed portions 3a by electrophoresis. To form a phosphor screen 5. When the phosphor screen is formed by the sedimentation method, a mask having a through hole is used instead of the slit 11a, so that the phosphor particles adhere only to the exposed portion 3a. After the fluorescent screen 5 is dried and fixed, the mask 11 is removed as shown in FIG. 2 (6). At this time, the phosphor particles adhering to the mask 11 are removed.

Photoresist layer removing step As shown in FIG. 2 (7), the photoresist layer 10 covering the segment electrodes 3 is removed by an appropriate means such as baking. When the substrate 2 is viewed at the end of this step, it is observed that the dot-shaped fluorescent screens 5 are arranged in order on each of the segment electrodes 3 arranged in a line.

Insulating Layer Forming Step As shown in FIG. 2 (8), the thickness of the insulating film for a thick film, for example, lead glass and carbon having a thickness of 10 to 10 so that the side edge of the segment electrode 3 in the width direction of the substrate 2 covers the rim. An insulating layer 6 of about 20 μm is formed on the upper surface of the substrate 2. The insulating layers 6, 6
For example, it is formed by a screen printing method. When it is difficult to directly form the insulating layers 6 and 6 directly on the substrate 2, as shown in FIG. 3, the insulating layers 6 and 6 are previously formed integrally with the grid electrodes 8 and 8 on the substrate side. In advance, this assembly may be mounted on the substrate 2. As shown in FIG. 5, the assembly is superposed on the substrate 2 and then fixed with insulating materials 7,7.

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

(Effects of the Invention) As is clear from the above description, according to the present invention, the phosphor screen is attached while the mask for exposing the segment electrodes in a dot shape is superimposed on the photoresist layer, so that the intended effect is achieved. The phosphor screen dot size can be obtained stably. In addition, since the phosphor particles attached to portions other than the dots are removed together with the mask, no phosphor particles remain on portions other than the regular phosphor screen, and a clear phosphor screen luminance can be obtained.

Furthermore, since the insulating layer forming step of forming an insulating layer for ensuring insulation with the grid electrode formed in the shape of a strip-shaped segment electrode is performed in the final step of the phosphor screen forming method,
By disposing the insulating layer before the photoresist forming step, the occurrence of the step which has occurred is eliminated. Therefore, it is possible to form the phosphor screen with a desired dot size and uniformity on the exposed portion of the segment electrode where the phosphor screen dots are to be formed, while ensuring the adhesion between the photoresist layer and the mask.

[Brief description of the drawings]

FIG. 1 is a flowchart showing steps of a method for forming a fluorescent screen of a fluorescent display tube according to the present invention, FIG. 2 is a sectional view showing the above steps, FIG. 3 is a sectional view showing an example of forming an insulating layer, and FIG. FIG. 5 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. . DESCRIPTION OF SYMBOLS 1 ... Fluorescent display tube, 2 ... Substrate, 3 ... Segment electrode, 5 ... Phosphor screen, 6 ... Insulating layer, 9 ... Grid electrode, 10 ... Magnetic photoresist layer, 11 ... Mask.

Claims (1)

(57) [Claims] In a step of forming a segment electrode, at least one row of strip-shaped segment electrodes made of a conductive material is provided on a substrate. In the step of forming a photoresist layer, the entirety of the segment electrode row is covered with a photoresist layer; In the step of exposing the segment electrode, a mask is adhered to the photoresist layer, and the photoresist layer is exposed and developed to partially remove the photoresist layer to expose the segment electrode, thereby forming a phosphor screen. In the step, while keeping the mask in close contact, phosphor particles are attached to the segment electrodes exposed in a dot shape to form a phosphor screen and the mask is removed, and in the photoresist layer removing step, the photoresist layer is removed. In the insulating layer forming step, the grid is arranged along the arrangement direction of the segment electrodes. A phosphor screen forming method of a fluorescent display tube to form an insulating layer for insulating the electrode and the segment electrode, and performing this insulating layer formation step to the final step.