JPH0644450B2 - Method for forming fluorescent screen in fluorescent display tube - Google Patents

Description

TECHNICAL FIELD The present invention relates to a method for forming a fluorescent screen in a fluorescent display tube.

(Prior Art) In a fluorescent display tube, a fluorescent surface is formed on a large number of segment electrodes arranged in one direction or in a plurality of rows in one direction, and the fluorescent surface is enclosed together with a hot cathode in a vacuum container. While generating electrons, a positive voltage is selectively applied to the segment electrodes according to the information to be displayed, attracting thermoelectrons to the selected segment electrodes, which are emitted when they collide with the phosphor screen. Information is displayed by fluorescence, which is well known as a bar code display tube or a phosphor dot array tube.

First, in FIG. 9, an outline of a fluorescent display tube will be described by taking a phosphor dot array tube as an example.

In FIG. 9, reference numeral 20 indicates a substrate made of glass, ceramic, resin or the like. On the substrate 20, a series of segment electrodes 21 are arranged in a row in the longitudinal direction of the substrate, and the segment electrodes 21 each have a fluorescent screen 26 formed thereon. The size of each phosphor screen is 40 × 40 μm ^{2 to}
Although it is extremely fine, such as 50 × 50 μm ² , in FIG. 9 the size of the phosphor screen is shown larger than that of the other members.

Insulator layers 22a and 22b are formed on both sides of the array of the phosphor screens of the substrate 20 along the substrate longitudinal direction, and grid electrodes 23a and 23b are formed thereon, respectively. In FIG. 9, reference numeral 24 indicates a tungsten wire as a hot cathode stretched in the longitudinal direction of the substrate, and BaSrO 2 is formed on the surface.
Have been coated with an electron emissive substance. Also, reference numeral 25
Is a face member formed of a transparent material such as glass, and is integrated with the substrate side as shown in FIG. Thus, the substrate 20, the insulator layers 22a and 22b, the grid electrodes 23a and 23b, and the face member 25 form a closed space, and in this space, the segment electrode 21, the fluorescent surface 26 by the fluorescent material layer, and the hot cathode 24. , 24 are trapped. The closed space is highly evacuated.

Applying an appropriate voltage to the grid electrodes 23a and 23b,
When an alternating current of several tens of milliamperes is passed through the hot cathodes 24, 24, the hot cathodes 24, 24 are heated by Joule heat and emit thermoelectrons. In this state, the segment electrode 21
When a positive voltage is applied to one of the electrodes to bring it to a positive potential, the thermoelectrons are attracted to the electrode portion of the segment electrode having a positive potential, and the energy state of the fluorescent substance on the fluorescent surface 26 is attracted to the electrode portion. To excite. The excited fluorescent substance emits fluorescence when returning to the ground state. This fluorescence is observed through the face member 25.

The phosphor dot array tube is used as a part of an optical system of an optical printer or a bar code display tube.

Conventionally, the phosphor screen is formed through the following steps.

1. In the electrode forming step, strip-shaped electrodes made of aluminum are formed on the substrate by photoetching.

2. In the insulating layer forming step, a thick film insulating glass layer is formed on the substrate by a screen printing method and is baked.
At this time, a part of the electrode is exposed.

3. In the phosphor screen forming step, a phosphor is attached to the exposed electrode portion. After that, the adhering size of the phosphor is shaped by the photo etching method.

By the way, when the adhering size of the phosphor is shaped by the photo-etching method, the deterioration of the brightness of the phosphor screen with time tends to be remarkable. Therefore, various attempts have been made to obtain a desired attachment size of the phosphor without going through the shaping process, but the current situation is that it has not been mass-produced in terms of manufacturing cost. Further, one of the methods for attaching the phosphor is an electrophoresis method. Depending on the electrodeposition conditions, it is possible to attach the electrode to a size approximately the same as the width of the strip electrode, but there is no restriction on the direction orthogonal to the electrode arrangement direction, so the entire electrode However, there is a problem in that the phosphor adheres to the surface and a phosphor screen shaping step is required.

(Purpose) An object of the present invention is to provide a phosphor screen forming method in a fluorescent display tube, which is easy to manufacture, can easily control the dot size of the phosphor screen, and can form a phosphor screen with little deterioration in its luminance over time. It is in.

(Structure) In the present invention, at least one row of strip-shaped electrodes made of a conductive material is provided on a substrate in the electrode forming step, and in the insulating layer forming step, the strip-shaped electrodes are arranged in the array direction on the substrate surface including the strip-shaped electrodes. A segment electrode row is formed by forming an insulating layer that exposes a part of the strip-shaped electrode along, and in the photoresist layer forming step, the insulating layer and the segment electrode row are covered with a photoresist layer, and then, The photoresist layer is removed in a slit shape with a desired width along the arrangement direction of the segment electrode rows to expose the segment electrode rows, and each of the exposed segment electrodes is exposed in the phosphor screen forming step. It is characterized in that phosphor particles are attached to one of them to form a phosphor screen, and in the photoresist layer removing step, the photoresist layer is removed to form a phosphor dot array.

Hereinafter, the present invention will be described in detail.

FIG. 1 shows the steps of the present invention. In order to avoid contact between the grid electrode and the strip-shaped electrode, an electrode forming step in which at least one strip-shaped electrode made of a conductive material is provided in a row on the substrate, An insulating layer forming step of forming a segment electrode row by forming an insulating layer that exposes a part of the strip-shaped electrodes along the array direction of the strip-shaped electrodes on the surface of the substrate including the strip-shaped electrodes; After coating the segment electrode array with a photoresist layer, the photoresist layer is removed in a slit shape with a desired width along the arrangement direction of the segment electrode array to form a resist layer forming step of exposing the segment electrode array. A phosphor screen forming step of forming phosphor screen by attaching phosphor particles to each of the exposed segment electrodes, and a photoresist layer for removing the photoresist layer It is made up of the removed by the process.

Hereinafter, each step will be described in detail.

Electrode forming step As shown by reference numeral 2 in FIG. 2B, an electrode made of aluminum is formed on one surface of the substrate 1 made of, for example, a glass plate shown in FIG. 2A by photoetching. As shown in FIG. 3, the electrodes 2 are strips each having a width of about 50 μm, and are formed in a line in the longitudinal direction of the substrate with a gap between adjacent electrodes of about 35 μm. Every other, it is pulled out to the left and right side edges of the substrate.

Insulating Layer Forming Step As shown in FIG. 2 (3), the substrate 1 including the strip-shaped electrode 2 is formed to have a thickness of 10 to 20 made of lead glass and carbon, for example.
It is covered with an insulating layer 3 having a thickness of about μm. The insulating layer 3 is formed by a screen printing method and then fired at 500 to 600 ° C.,
As shown in FIG. 7, an electrode portion (hereinafter referred to as an “exposed portion 2b”) that extends along the arrangement direction of the strip-shaped electrodes 2 and is located at the central portion in the width direction of the substrate 1, The ends of the lead portions 2a are exposed. The exposed portions 2b are arranged in a row in the longitudinal direction of the substrate, and a segment electrode row is formed here.

Photoresist Layer Forming Step As shown in FIG. 2 (4), the insulating layers 3 and 3, the segment electrode array 2, and the substrate 1 are entirely covered with a photoresist layer 4. As the photoresist layer 4, for example, a negative photoresist OMR-85 for fine processing "trade name of Tokyo Ohka Kogyo Co., Ltd." or a positive photoresist OFPR- for fine processing is used.
The 800 "same product name" is used. Photoresist layer 4
Is prebaked at 85 ° C to 95 ° C.

Next, as shown in FIGS. 2 (5) and 3, a part of the photoresist layer 4 is removed in a slit shape in the longitudinal direction of the substrate 1 as indicated by reference numeral 4a, and the segment electrode array (exposed The central portion of the portion 2b) is exposed again. The width of the slit 4a is controlled to 40 to 50 μm. An example of the method of forming the slit will be described with reference to FIGS. 4 and 8.

In FIG. 4, the laser light generated by the laser light generator 5 is guided to the scanning optical system 7 via the polarizer 6, and the laser light causes the photoresist layer 4 to move in the direction orthogonal to the arrangement direction of the segment electrodes. Line scan to expose the layer in slits. After that, this is developed and rinsed to remove the layer in a slit shape to form a slit 4a. In this case, a positive photoresist is used as the photoresist layer 4, and the portion exposed to the laser beam is removed in a slit shape to expose the segment electrode array. In FIG. 4, a method of sliding a mirror or the like may be adopted without using the polarizer 6. Furthermore,
In FIG. 4, adjusting means for adjusting the beam power may be provided between the laser light generator 5 and the polarizer 6.

FIG. 8 shows a substrate coated with a photoresist layer 4,
There is shown a method in which the mask 8 having the slit pattern 8a formed thereon is polymerized and then the light from a light source 9 having an emission wavelength such as ultraviolet rays is applied to remove the photoresist layer in a slit shape. When the photoresist layer 4 is a positive photoresist, a positive mask is used and the exposed portion is removed by development and rinsing to obtain the slit 4a. When the photoresist layer 4 is a negative photoresist, a negative mask is used to remove the unexposed portion by developing and rinsing to obtain the slit 4a.

Phosphor screen forming step As shown in FIG. 2 (5), the substrate 1 covered with the photoresist layer 4 and having the exposed portions 2b of the electrodes 2 exposed is attached to the phosphor screen forming apparatus 10 shown in FIG. Fluorescent screen forming device
Reference numeral 10 includes a tank 12 that stores a dispersion liquid 11 in which phosphor particles are dispersed, a DC power supply 13, and a counter electrode 14 that is connected to the positive electrode of this power supply and that is disposed in the dispersion liquid. . As the dispersion liquid 11, isopropyl alcohol ((CH ₃ ) ₂ .CHOH) as a solvent, a zinc oxide phosphor (ZnO: Zn), and aluminum nitrate (Al (NO ₃ ) ₃ .9H ₂ O as a control agent) ) Is used. Then, the substrate 1 is immersed in the dispersion liquid, and the exposed portion 2b of the electrode is opposed to one end of the counter electrode 14 at a predetermined interval. The counter electrode is not limited to the one shown in the figure, and may have an appropriate shape. In addition,
In FIG. 5, the insulating layer 3 and the photoresist layer 4 are not shown. Each electrode 2 is connected to the negative electrode of the power supply 13. The tank 12 is provided with a stirring device (not shown) so as to stir the dispersion liquid 11.

Then, the switch S is closed and the electrode 2 and the counter electrode 14 are closed.
When a voltage is applied between the two, an electric field is formed between the two, and the phosphor particles in the dispersion liquid 11 are electrophoresed and move to the electrode 2 side. As shown in FIGS. 2 (6) and 6, the phosphor particles that have electrophoretically moved to the electrode 2 side adhere to the exposed portion 2b of the electrode in a layered manner, so that the phosphor screen 15 is formed. Form. At this time, the phosphor particles adhere to the surface of the photoresist layer 4 along the covered electrode 2, although slightly.

As a matter of course, other methods may be adopted as the fluorescent screen forming device.

Photoresist Layer Removal Step As shown in FIGS. 2 (6) and 6, when the substrate 1 on which the phosphor screen 15 is formed is baked by, for example, oxygen plasma to remove the photoresist layer 4, FIG. As shown in 7) and FIG. 7, the insulating layers 3 and 3 and the segment electrode array 2 which have been covered with the photoresist layer until now are exposed.

That is, the phosphor screen 15 having the same side as the width of the electrode 2 and the same side as the width of the slit 4a is formed on each segment electrode 2. When this is observed with respect to the substrate 1, the phosphor screens 15 are regularly arranged in a dot shape.

(Effect) As described above, according to the present invention, since the photoresist layer is formed and the shape size of the phosphor screen is controlled by the slit as a pre-process of the process of attaching the phosphor particles, the phosphor screen This eliminates the need for a shaping step after the formation of the phosphor screen, which causes deterioration of luminance over time, which is advantageous for deterioration over time. Also,
Since it is sufficient to control the size of the phosphor screen in the direction orthogonal to the segment electrode array, the manufacturing becomes relatively easy.

[Brief description of drawings]

FIG. 1 is a process drawing showing the steps of the phosphor screen forming method of the present invention,
FIG. 2 is a process diagram showing a sectional view of a concrete example of the same, FIG. 3 is a partial plan view for explaining a photoresist layer forming process, and FIG. 4 is a block showing an example of a means for removing the photoresist layer. 5 and 5 are schematic cross-sectional views showing an example of means for forming a phosphor screen, FIG. 6 is a partial plan view showing a state where the phosphor layer is formed and the photoresist layer is not removed, and FIG. 7 is a photoresist. A partial plan view showing the state in which the layers have been removed,
FIG. 8 is a block diagram showing another example of means for removing the photoresist layer, FIG. 9 is an exploded perspective view showing a phosphor dot array tube as an example of a fluorescent display tube, and FIG. 10 is a sectional view of the same. Is. 1 ... Substrate, 2 ... Strip-shaped electrode, 3 ... Insulating layer, 4 ...
Photoresist layer, 4a ... slit, 15 ... phosphor screen.

Claims (1)

[Claims] 1. In a fluorescent display tube, at least one row of strip-shaped electrodes made of a conductive material is provided on a substrate in an electrode forming step, and a substrate surface including the strip-shaped electrodes is formed in an insulating layer forming step.
A segment electrode row is formed by forming an insulating layer that exposes a part of the strip electrode along the arrangement direction of the strip electrodes, and the insulating layer and the segment electrode row are formed into a photoresist layer in a photoresist layer forming step. Then, the photoresist layer is removed in a slit shape with a desired width along the arrangement direction of the segment electrode rows to expose the segment electrode rows, and in the phosphor screen forming step, the exposed Phosphors characterized in that phosphor particles are attached to each of the segment electrodes to form a phosphor screen, and the photoresist layer is removed in a photoresist layer removing step to form a phosphor dot array. Surface forming method.