JPS6398932A - Manufacture of fluorescent screen for fluorescent character display tube - Google Patents

Abstract

PURPOSE:To stick fluophor particles uniformly on electrode regardless of the size and the number of the electrodes by flowing dispersed liquid of fluophor in the direc tion nearly perpendicular to the arranging direction of a row of segment electrode and applying a voltage to the electrodes so as to adhere fluophor particles by electro phoresis. CONSTITUTION:A row of electrode composed of electro-conductive material is provided on a substrate 1 and on which insulating layer 3 is coated to form a row 2 of segment electrodes and further coated with photoresist layer 4, and then respective segment electrodes 2b are exposed by removing the photoresist layer 4 coated only on the respective segment electrodes. The segment electrodes and the opposed electrodes arranged to face to the segment electrodes are immersed in a dispersed liquid of fluophor particles and the liquid is flowed in the direction nearly perpendicular to the arranging direction of the segment electrodes, and a voltage is applied to electrodes so as to adhere fluophor particles on the respective exposed segment electrodes 2b by electrophoresis to form the fluorecent screen 17, and then the photoresist layer 4 is removed to form the dot array of the fluophor. Thereby an uniform fluorescent screen can be produced.

Description

DETAILED DESCRIPTION OF THE INVENTION (Technical Field) The present invention relates to a method for forming a fluorescent surface in a fluorescent display tube.

(Prior art) A fluorescent display tube has a fluorescent surface formed on a large number of segment electrodes arranged in one or more rows in one direction, and these are sealed in a vacuum container together with a hot cathode. While generating thermoelectrons, a positive voltage is selectively applied to the segment electrodes according to the information to be displayed to attract thermoelectrons to one selected segment electrode, and when the thermoelectrons collide with the fluorescent surface. Information is displayed using fluorescent light emitted from the tube, and they are already well known as bar code display tubes and fluorescent dot array tubes.

First, referring to FIG. 14, the outline of a fluorescent display tube will be explained by taking a fluorescent dot array tube as an example.

In FIG. 14, reference numeral 70 indicates glass or ceramic.

A substrate made of resin or the like is shown. A series of segment electrodes 71 are arranged on the substrate 70 in the longitudinal direction of the substrate, and each segment electrode 71 has a fluorescent surface 72.
is formed. The size of each fluorescent surface is 4
The size of the fluorescent surface is extremely small, such as 0 x 40 μm" to 50 x 50 μm", but in FIG. 14, the dimensions of the fluorescent surface are shown to be larger compared to other members.

On both sides of the array of fluorescent surfaces of the substrate 70 are insulating layers 73°7.
3 are formed along the longitudinal direction of the substrate, and on these,
Grid electrodes 74, 74 are formed, respectively. In FIG. 14, reference numeral 75 indicates a tungsten wire as a heat source stretched in the longitudinal direction of the substrate, the surface of which is coated with an electron emissive material such as Bad or SrO. Further, reference numeral 76 is a face member made of a transparent material such as glass, and is integrated with the substrate side as shown in FIG. 15. Thus, the substrate 70, the insulator layer 73.73, the grid electrode 74.74, and the face member 76 form a closed space within which the segment electrodes 71. Fluorescent surface 72 with a phosphor layer. Hot cathode 75.7
5 is trapped.

The closed space is highly evacuated.

By applying an appropriate voltage to the grid electrodes 774, 74, they are heated and emit thermoelectrons. In such a state, when a positive voltage is applied to one of the segment electrodes 71 to make it a positive potential, the thermal electrons are attracted to the electrode part of the segment electrode at a positive potential, and when they are sucked into the electrode part, they are emitted by a firefly. The energy state of the fluorescent material on the light surface 72 is excited. The excited fluorescent substance emits fluorescent light when returning to the ground state. This fluorescent light is transmitted through the face member 76 to II? be done.

Such a fluorescent dot array tube is used as a part of the optical system of an optical printer or as a bar code display tube.

One of the methods for forming a fluorescent surface is an electrodeposition method using electrophoresis. In this method, in the electrode formation step, a segment electrode array consisting of strip-shaped electrodes is formed on the substrate by photoetching, and in the insulating layer formation step, a part of the electrode is exposed by screen printing, and the A layer of thick film insulating glass is formed on the surface of the substrate including the electrodes, and this is fired.

Next, only a portion of the exposed electrode is exposed, and the surface of the moving plate including the electrode is covered with a resist layer. Then, in the phosphor surface forming step, the substrate is immersed in a dispersion liquid in which phosphor particles are dispersed while being stirred by a propeller or the like, facing the counter electrode at a predetermined distance, and forming a segment electrode array and a counter electrode. Apply voltage between. The fluorescent particles in the dispersion liquid move toward the segment electrode π pole by the electric field formed between the two electrodes, and adhere to the exposed electrode portion to form a fluorescent surface. After this fluorescent surface is dried and fixed, the resist layer is removed.

By the way, the above-mentioned electrodeposition method is effective when the segment electrode to which the phosphor is deposited is relatively large;
This method is not necessarily effective when the segment electrodes are small, the electrode spacing is short, or the number of segment electrodes is large. Due to the unevenness of the phosphor particles in the dispersion liquid stirred by a propeller, etc., and the uneven flow rate of the dispersion liquid due to stirring, they tend to adhere to unnecessary areas, such as the center and edges of long substrates. Problems may occur, such as the amount of adhesion on different parts being significantly different. If the liquid tank is large, there is a circulation method in addition to the propeller, but with this circulation method, the dispersion liquid is sprayed from both sides of the segment electrode row to the center part, which is applied over the entire area of the "RtJM row" mentioned above. This method has the disadvantage that it is not possible to obtain a uniform flow rate over a wide range of areas, making it difficult to achieve uniform dispersion of the phosphor particles.

(Purpose) The present invention has been made in order to overcome the disadvantage described in 1 of the prior art. ) In the phosphor surface forming step, the present invention immerses a segment electrode array and a counter electrode disposed opposite to the segment electrode array in a dispersion liquid in which phosphor particles are dispersed, and at least the segment electrode array is The injection port is provided near and along the arrangement direction of the segment electrode array, and has a rectifying means for achieving a uniform flow velocity over the entire area of the segment electrode array. While flowing the dispersion liquid in the same direction, a voltage is applied between the segment ffl rod row and the counter electrode to cause electrophoresis of the phosphor particles, so that the phosphor particles are deposited on each exposed portion of the segment electrode. It is characterized by attaching.

The present invention will be explained in detail below.

FIG. 1 shows the steps of the present invention, including an electrode forming step in which at least one row of electrodes made of a conductive material is provided on a substrate, and a step in which electrodes are formed on the surface of the substrate including the electrodes to avoid contact between the grid electrode and the electrodes. , an insulating layer forming step of forming a segment electrode array by forming an insulating layer that exposes a portion of the electrodes along the electrode arrangement direction; and after covering the insulating layer and the segment electrode array with a photoresist layer, A resist layer forming step of removing only the first and second resist layers of the individual segment electrodes constituting the segment electrode array to expose the segment electrode array, and the segment electrodes to which a voltage is applied. between the column and the counter electrode,
A phosphor surface forming step in which a phosphor particle is attached to the exposed portion to form a phosphor surface while the dispersion flows in a direction substantially perpendicular to the segment electrode array, and a stripping step in which the photoresist layer is removed. ≠It consists of a resist layer removal process.

Each step will be explained in detail below.

Electrode formation process A substrate 1 made of, for example, a glass plate, shown in FIG. 2 (1,)
An electrode made of aluminum is formed on one surface of the substrate by photoetching, as shown by reference numeral 2 in FIG. This electrode 2 has a width of about 5 mm, as shown in FIG.
0 μm strip shape, with an interval of about 35 μm between adjacent electrodes.
The lead portions 2 of each electrode are formed in a line in the longitudinal direction of the substrate.
A is drawn out to the left and right side edges of the board every other time.

8-layer forming process As shown in FIG. 2 (3), the substrate 1 including the strip-shaped electrodes 2 is made of, for example, button glass and carbon and has a thickness of 10
Cover with an insulating layer 3 of about 20 μm.

The second insulating layer 3 is formed by screen printing and then
As shown in FIG. 7, the electrode part (hereinafter referred to as "exposed" The end portions of the lead portions 2a (referred to as portions 2bJ) are exposed.The exposed portions 2b are arranged in rows in the longitudinal direction of the substrate, and segment electrode rows are formed here.

Photoresist layer forming step As shown in FIG. 2(4), the insulating layers 3, the segment electrode array 2, and the substrate 1 are entirely coated with a photoresist layer 4. As the photoresist layer 4, for example, a negative type resist for fine processing OMR-85 is used.
r manufactured by Tokyo Ohkagaku Kogyo Co., Ltd. or a positive photoresist for microfabrication 0FPR-800 (trade name) is used. The photoresist layer 4 is prebaked at 85°C to 95°C for about 30 minutes.

Next, as shown in FIGS. 2(5) and 3, the photoresist layer 4 on the exposed portion 2b of each segment electrode is
As shown in a, remove in dots to form segment electrodes!
The pole row (center portion of exposed portion 2b) is exposed again. The width of the dot 4a is controlled to 40 to 50 μm,
As an example of a method for forming such dots, a fourth laser beam is guided to the scanning optical system 7 via a polarizer 6, and the photoresist layer 4 is oriented perpendicularly to the arrangement direction of the segments ff1l by this laser beam to form electrodes. Spots are scanned and exposed at an array pitch. Thereafter, this layer is developed and rinsed to remove the layer in dots to form dots 4a. In this case, photoresist Pf! A positive type photoresist is used as J4, and the portion hit by the laser beam is removed to expose a dot-shaped segment electrode array. In addition, in FIG. 4, a method of sliding a mirror or the like may be adopted without using the polarizer 6. Furthermore, in FIG. 4, an adjusting means for adjusting the beam power may be provided between the laser beam generator 5 and the polarizer 6. The shape of the dot 4a is not limited to the exact square shown in the figure, but may be circular or oval.

FIG. 5 shows a substrate 1 coated with a photoresist layer 4;
There is a method in which a mask 8 on which a dot array pattern 8a having the same pitch as the electrode 2 is formed is polymerized, and then the photoresist layer is removed in the form of dots by applying light from a light source 9 having an emission wavelength such as ultraviolet rays. It is shown. When the photoresist layer 4 is a positive type photoresist, a positive mask is used and the exposed portion is removed by development and rinsing to obtain the dots 4a. Photoresist layer 4
If it is a negative type photoresist, a negative mask is used and the unexposed portions are removed by development and rinsing to obtain the dots 4a. Note that the photoresist layer 4 was not removed in a driver-like manner.

The width of the exposed portion may be regulated by removing the layer in the form of a slit in the same direction as the arrangement direction of the segment electrodes to expose the exposed portion of the segment electrode array.

Fluorescent surface formation process A fluorescent surface forming apparatus is shown in FIGS. 8 and 9.

In these figures, the reference numeral 10 indicates the bottom.

This bottom punch 10 has two gear combinations G1. A recess 10a and a lob are formed to respectively accommodate G2, and grooves 11a and 11b are connected to these recesses 10a and 10b.
, 12a, 12b are formed. A lid 13 is attached to the top of the bottom opening 10, and the lid 13 has grooves 11b and 12b.
Square holes 13a and 13b are bored through which the two communicate with each other. Block 14.1 so as to close the square holes 13a and 13b
5 are erected on the lid 13, and these blocks 14.1
A pipe 16 is supported on 5.

A passage 47 is bored in the block 14, 15 to communicate the square holes 13a, 13b with the hollow part of the pipe 6. The pipe 16 has a slit 18 as shown in FIG.
is opened along the longitudinal direction to form an injection port.

The length of the slit 18 is 1.1 to 1.2 of the length of the segment electrode row so that the dispersion liquid flows uniformly to all electrodes (2b).
The width is increased toward the center, forming a diamond shape as a whole, and the direction is diagonal e, as will be described later, and along the placed substrate. Recess 10 in bottom plate 10
(Gear combinations G1 and G2 are accommodated in 1 and 10b to constitute two sets of gear pumps, and the drive gears 19 and 20 of these gear pumps are connected to the gears 21 and 21 on i13, respectively.
22 through an unillustrated shaft, and the gear 21
．． 22 is driven by an intermediate gear 23.

Intermediate gear 23 is driven by motor 24 . The substrate loading stage 25 is mounted close to the pipe 16 on the lid I3. 11 substrates 1 are held on a substrate mounting table 25,
Opposing electrodes 19 are arranged facing the exposed portions 2b of the segment electrode rows at a predetermined interval. The counter electrode 19 is made of an elongated rectangular aluminum plate.
It is erected in a direction almost perpendicular to l. A device configured as described above is submerged in a liquid tank 21 in which a dispersion liquid 20 is stored.

When voltage is applied to the motor 24 and the intermediate gear 23 fixed to the motor rotates, two sets of gear pumps (G1 and G2) are operated via the gears 21 and 22.
The dispersion liquid 20 is sucked through the grooves 11a and 12a and discharged into the grooves 11b and 12b, and further into the square holes 13a and 12b, respectively.
13b, passes through blocks 14 and 15, enters the pipe 16, and is ejected from the slit 18. The dispersion liquid ejected from the slit 18 flows along the substrate 1 and in a direction substantially perpendicular to the arrangement direction of the segment electrode array (2b). In order to easily form a phosphor according to the surface of the segment electrodes, regardless of the size of the segment electrodes or the length of the electrode interval, the width of the slit 18, the motor rotation speed, etc. are appropriately set to achieve the desired jet flow velocity and The injection flow rate is adjusted per unit time. Furthermore, as shown in FIG. 11, the slits 18 may be formed by arranging a large number of small holes 27 in parallel at equal intervals in the longitudinal direction of the pipe 26. In this case, the diameter of the small hole 27 is changed little by little so that it is maximum at the center and minimum at both ends. Further, as shown in FIG. 12, a large number of small holes 37 having the same diameter may be arranged in parallel in the longitudinal direction of the pipe 36 such that the distance increases from the center toward both ends. Furthermore, the 13th
As shown in the figure, a mesh perforated film, sheet, etc. may be provided in the center of the slit 47 of the pipe 46. In short, it is important that the pipe has a rectifying means that substantially continuously changes the shape, size, spacing, etc. of the injection ports to provide a uniform flow velocity over the entire area of the deposited electrode array. The term "substantially continuous" means that in addition to the linear variation as mentioned above, it includes an additional variation or a curved variation, as long as a substantially uniform flow can be obtained. It is. In addition,
The number of pipes is not limited to one, but two pipes may be arranged in parallel so that the injected dispersion liquid is supplied from both sides of the segment electrode array toward the center.

The substrate to which the fluorescent surface formed in the above-described steps is attached is subjected to the next step after the fluorescent surface is dried and the liquid component is removed.

Photoresist Layer Removal Step As shown in FIGS. 2(6) and 6, the substrate 1 on which the fluorescent surface 17 is formed is fired with, for example, oxygen plasma to peel and remove the photoresist layer. Photoresist layer 4
As shown in Fig. 2 (7) and Fig. 7, when .
Insulating layer 3, 3, which was previously covered with a photoresist layer
, the segment electrode array 2 is exposed. At this time, the phosphor particles adhering to the photoresist layer 4 are also removed as the layer is peeled off. Therefore, on each segment electrode 2, a fluorescent surface 17 having the same size as the dot 4a is formed. When this is observed with respect to the substrate 1, it can be seen that the fluorescent surfaces 17 are arranged in an orderly dot shape.

(Effects) According to the present invention, by arbitrarily adjusting the supply of the dispersion liquid to the segment electrode array, it is possible to form a fluorescent surface under optimal electrophoresis conditions. In the case where the electrode spacing is short or the number of electrodes is large, it is highly effective in forming a fluorescent surface on the substrate. In addition, compared to the conventional propeller agitation method, it is possible to form a fluorescent surface with approximately 1/3 the amount of dispersion liquid, and it can be provided at low cost. Moreover, since the dispersion liquid injection port is provided with a rectifying means, a uniform flow velocity can be obtained over the entire area of the segment electrode array, and uniform fluorescent surface formation can be achieved.

[Brief explanation of the drawing]

FIG. 1 is a process diagram showing the steps of the fluorescent surface forming method of the present invention;
FIG. 2 is a process diagram showing a specific example of the same as the above in a cross-sectional view, FIG. 3 is a partial plan view for explaining the photoresist layer forming process, and FIGS. 4 and 5 show means for removing the photoresist layer. Block diagrams showing different examples, FIG. 6 is a partial plan view showing a state in which a fluorescent surface is formed and the photoresist layer is not removed, and FIG. 7 is a partial plan view showing a state in which the photoresist layer is removed. , FIGS. 8 and 9 are a partially exploded perspective view and a partially sectional view showing an example of an apparatus for carrying out the fluorescent surface forming method of the present invention, and FIG. 10 is a partially exploded perspective view and a partially sectional view showing a pipe used in the apparatus. 11 to 13 are partial side views showing modified examples of the pipe, FIG. 14 is an exploded perspective view showing a fluorescent dot array tube as an example of a fluorescent display tube, and FIG. 15 is a sectional view of the same as above. DESCRIPTION OF SYMBOLS 1... Substrate, 2... Segment electrode, 3... Insulating layer, 4... Photoresist layer, 4a... Dot, 1
0... Bottom plate, 13... Lid, 16... Pipe, 18
... Slit, 19 ... Counter electrode, 20 ... Dispersion liquid, G, , G2 ... Gear combination (gear pump).

Claims (1)

[Scope of Claims] In a fluorescent display tube, in the electrode forming step, at least one row of electrodes made of a conductive material is provided on the substrate, and in the insulating layer forming step, the surface of the substrate including the electrodes is coated in the direction in which the electrodes are arranged. An insulating layer exposing a part of the electrodes is formed along the line to form a segment electrode row, and in a photoresist layer forming step, the insulating layer and the segment electrode row are covered with a photoresist layer, and then the segment electrode row is formed. Only the photoresist layer on each segment electrode constituting the segment electrode was removed to expose the segment electrode row, and in the fluorescent surface forming step, the segment electrode row and the segment electrode row were arranged opposite to each other. A counter electrode is immersed in a dispersion liquid in which phosphor particles are dispersed, and is provided at least in the vicinity of the segment electrode array and along the arrangement direction of the segment electrode array, and uniformly over the entire area of the segment electrode array. In order to obtain a flow velocity, the dispersion liquid is caused to flow in a direction substantially perpendicular to the arrangement direction of the segment electrode array from an injection port having a rectifying means, and a voltage is applied between the segment electrode array and the opposing electrode. The fluorescent particles are adhered to each of the exposed segment electrodes by electrophoresis to form a fluorescent surface, and the photoresist layer is removed in a photoresist layer removal step. A method for forming a fluorescent surface, comprising: forming a fluorescent dot array.