JPS62154530A - Phosphor screen formation in fluorescent character display tube - Google Patents

Abstract

PURPOSE:To make dot size control ever so easy as well as to reduce secular deterioration in the brightness, by removing a photoresist layer alone after covering an insulating layer and a segment electrode train with the photoresist layer, while letting a dispersion solition of phosphor particles drip and stick to each of them. CONSTITUTION:A substrate 1 inclusive of a strip-form electrode 2 is covered with an insulating layer 3. An electrode part 'an exposing part 2b' to be situated in a central part in a cross direction of this substrate 1 and an edge of a lead part 2a both are exposed, forming a segment electrode train hereat. Next, all of them are covered with a photoresist layer 4 to the full, and this photoresist layer 4 on the exposing part 2b of each segment electrode is removed in dotted form as shown in 4a, whereby the segment electrode train (the central part of the exposing part 2b) is reexposed. This electrode train is exposed in a way of spot scanning by a laser beam. Then, phosphor particles are stucked to each of them with a dripping device by means of an ink jet process, thus a phosphor screen 15 is formed up. A phosphor screen former 10 consists of a tank 12 storing a dispersion solution 11 in which these phosphor particles are dispersed and a dripping head 13. And, the photoresist layer 4 is removed after being burned with oxygen plasma.

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 is made by forming a fluorescent surface on a large number of segment electrodes arranged in one or more rows in one direction, and enclosing this together with a hot cathode in a vacuum container. While generating thermoelectrons from Information is displayed by the fluorescent light emitted when the fluorescent light collides with the fluorescent light, and is already well known as a bar code display tube or a fluorescent dot array tube.

First, referring to FIG. 8, the outline of a fluorescent display tube will be explained by taking a fluorescent dot array tube as an example.

In FIG. 8, reference numeral 20 indicates a substrate made of glass, ceramic, resin, or the like. A series of segment electrodes 21 are arranged on the substrate 20 in the longitudinal direction of the substrate, and a fluorescent surface 26 is formed on each of the segment electrodes 21. The size of each fluorescent surface is 40
Although it is extremely fine, such as 40μ7rLm to 50×50μm', the size of the fluorescent surface in FIG. 9 is larger than that of the other members.

An insulator layer 22a1 is provided on both sides of the fluorescent surface arrangement of the substrate 20.
22b are formed along the longitudinal direction of the substrate, and grid electrodes 23a and 23b are formed on these, respectively. In FIG. 8, reference numeral 24 indicates a tungsten wire as a hot cathode stretched in the longitudinal direction of the substrate, the surface of which is coated with an electron emissive substance such as Ba5rO. Further, reference numeral 25 denotes a face member made 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, 22b, the grid electrodes 23a,
23b, the phase member 25 forms a closed space,
Within this space, a segment 21, a fluorescent surface 26 formed by a phosphor layer, and a heat shade +1ffi 24 are confined. The closed space is highly evacuated.

When an appropriate voltage is applied to the grid electricity fM 23a, 23b and an alternating current of several tens of milliamps is passed through the hot cathode 24.24, the hot cathode 24.24 is heated by Zeel heat and emits thermionic electrons. . In this state, when a positive voltage is applied to one of the segment electrodes 21 to make it a positive potential, the thermionic electrons are attracted to the electrode portion of the segment electrode having a positive potential, and when absorbed into the electrode portion, the fluorescent surface The energy states of 26 fluorescent substances are excited. The excited fluorescent substance emits fluorescent light when returning to the ground state. This fluorescent light is observed through the face member 25.

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.

Conventionally, the fluorescent surface 26 is formed through the following steps.

(2) In the electrode forming step, a strip-shaped electrode made of sia aluminum is 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 screen printing and fired.

At this time, a portion of the electrode is exposed.

3. In the phosphor surface forming step, a phosphor is attached to the exposed electrode portion. Thereafter, the adhered size of the phosphor is adjusted by photo-etching.

By the way, when the size of the adhered phosphor is adjusted by photoetching, the brightness of the phosphor surface tends to deteriorate significantly over time. Therefore, various attempts have been made to obtain the desired phosphor adhesion size without going through the shaping process, but the current situation is that mass production has not been possible due to manufacturing costs. Further, one of the methods for attaching a phosphor is electrophoresis. Depending on the electrodeposition conditions, it is possible to deposit the electrode to a size that is approximately the same as the width of the strip electrode, but since there is no restriction in the direction perpendicular to the electrode arrangement direction, the entire electrode There is a problem in that the phosphor adheres to the phosphor, and a phosphor surface shaping process is required.

(Objective) The object of the present invention is to provide a fluorescent surface in a fluorescent display tube that is easy to manufacture, easy to control the dot size of the fluorescent surface, and can form a fluorescent surface whose brightness is less likely to deteriorate over time. The objective is to provide a forming method.

(Structure) The present invention provides at least one row of strip-shaped electrodes made of a conductive material on a substrate in the electrode formation step, and an arrangement of the strip-shaped electrodes on the substrate surface including the strip-shaped electrodes in the insulating layer formation step. An insulating layer exposing a part of the strip-shaped electrodes along the direction was formed to form a segment electrode array, and in a photoresist A, step 5 forming step, the insulating layer and the segment electrode array were covered with a photoresist layer. Afterwards, only the photoresist layer on the segment electrode array is removed in dots to expose the segment electrode array, and in a fluorescent surface forming step, each of the exposed segment electrodes is exposed to fluorescent light. A phosphor dot array is formed by dropping a dispersion of body particles to form a phosphor surface, and in a photoresist layer removal step, the photoresist layer is removed to form a phosphor dot array.

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 strip-shaped electrodes made of a conductive material is provided on a substrate, and in order to avoid contact between the grid electrode and the strip-shaped electrodes, forming an insulating layer that exposes a portion of the strip electrodes along the arrangement direction of the strip electrodes on the surface of the substrate including the strip electrodes to form a segment electrode array; and forming a resist layer in which the segment electrode row is covered with a photoresist layer, and then only the photoresist layer on each segment electrode constituting the segment electrode row is removed in dots to expose the segment electrode row. a fluorescent surface forming step in which a dispersion of fluorescent particles is dropped onto each of the exposed segment electrodes to form a fluorescent surface; and a photoresist layer in which the photoresist layer is removed. It consists of a resist layer removal step.

Each step will be explained in detail below.

Electrode Formation Step An electrode made of aluminum is formed on one surface of the substrate 1 made of, for example, a glass plate, as shown in FIG.

As shown in FIG. 3, this electrode 2 has a width of about 50 μm.
The electrodes are shaped like strips, and are formed in a line in the longitudinal direction of the substrate with an interval of about 35 μm between adjacent electrodes, and lead portions 2a of each electrode are drawn out to the left and right edges of the substrate every other time.

Insulating layer forming process As shown in FIG. 2 (3), the substrate 1 including the strip-shaped electrodes 2 is made of, for example, lead glass and carbon and has a thickness of 10 to 5.
Cover with an insulating layer 3 of about 20 μm. This insulating layer 3 is
It is formed by a screen printing method and then fired at 500 to 600°C, and as shown in FIG. (hereinafter referred to as "exposed part 2bJ")
The end portion of the lead portion 2a is exposed. Exposed part 2b
are arranged in rows in the longitudinal direction of the substrate, meaning that segment electrode rows are formed here.

Photoresist layer forming step As shown in FIG. 2(4), the insulating layers 3, 3, segment electrode array 2, and substrate 1 are entirely covered with a photoresist layer 4. As the photoresist layer 4, for example, negative-type photoresist 0F for microfabrication, OMR-85 (trade name manufactured by Tokyo Ohka Kogyo Co., Ltd.), or positive photoresist 0F for microfabrication.
"PR-80Or same high quality product 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, it is removed in dots to expose the segment electrode array (center portion of the exposed portion 2b) again. dot 4
The a6D@ is controlled to 40-50 .mu.m, and the method for forming such dots will be explained with reference to FIGS. 4 and 5 as an example.

In FIG. 4, a laser beam generated by a laser beam generator 5 is guided to a scanning optical system 7 via a polarizer 6, and the photoresist layer 4 is polarized by this laser beam in a direction perpendicular to the arrangement direction of the segment electrodes. , exposure is performed by spot scanning at the electrode arrangement pitch. Thereafter, this layer is developed and rinsed to remove the layer in dots to form recessed dots 4a.

In this case, a positive type photoresist is used as the photoresist layer 4, and the portions hit by the laser beam are removed to expose the dot-shaped segment electrode arrays. 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;
After polymerizing the mask 8 in which a dot array pattern 8a having the same pitch as the arrangement pitch of the electrodes 2 is formed, the photoresist layer is removed in dots by dimming light from a light source 9 having an emission wavelength such as ultraviolet rays. The method 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 layer 4a. When the photoresist layer 4 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. In any case, the tonneau 4a is recessed.

Fluorescent surface forming step As shown in FIG. 2 (5), the substrate 1 coated with the photoresist layer 4 and with the exposed portion 2b of the electrode 2 exposed is exposed to a droplet ray using the inkjet method shown in FIG. The fluorescent surface 15 is formed as shown in FIG. 2(6) by adhesion. In FIG. 10, a fluorescent surface forming device 1° includes a tank 12 that stores a dispersion liquid 11 in which fluorescent particles are dispersed, and a droplet head that ejects the dispersion liquid 11 in droplets using, for example, a piezoelectric element. It has 13 points.

The dispersion liquid 11 contains zinc oxide phosphor (
Zno: Zn) and aluminum nitrate (AI (NO3)3.9H20) as a control agent are dispersed therein. The dispersion liquid 11 is transferred to the tank 12 and the Shivive 1.
4 into the droplet head 13, and is ejected from the nozzle 13a of the droplet head 13 by the vibration of the piezoelectric element. It goes without saying that the number of droplets deposited is controlled. After the fluorescent surface is formed, the substrate 1 is moved by the transport means 115. The fluorescent surface forming apparatus is not limited to the above-mentioned inkjet method, but may be of a method in which the dispersion liquid is dropped upward while moving the substrate horizontally. In this case, the amount of phosphor deposited can be controlled by the number of droplets. Furthermore, by including AI3+ in the dispersion, the conductivity of the phosphor adhesion layer may be increased to prevent deterioration of the light emitting characteristics due to so-called charge-up.

Photoresist Layer Removal Step As shown in FIGS. 2(6) and 6, the substrate 1 on which the fluorescent surface 15 is formed is fired with, for example, oxygen plasma to remove the photoresist layer 4, as shown in FIG. (7) As shown in FIG. 7, the insulating layers 3, 3, electrodes 2, 2°, .

That is, a fluorescent surface 15 having the same size as the dot 4a is formed on the electrode 2.

When this is observed with respect to the substrate 1, it can be seen that the fluorescent surfaces 15 are arranged in an orderly array in the form of dots.

(Effects) As described above, according to the present invention, a uniform fluorescent surface can be formed because a dispersion containing fluorescent particles is formed into droplets and the droplets are attached to the segment electrodes.

Furthermore, since no fluorescent particles are attached to the segment electrodes other than the dots 4a, fluorescent display with clear edges can be performed.

[Brief explanation of drawings]

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 above in a cross-sectional view, Fig. 3 is a partial plan view illustrating the photoresist layer forming process, and Fig. 4 is a block diagram showing an example of means for removing the photoresist layer. 5 is a schematic sectional view showing another example of means for removing a photoresist layer, FIG. 6 is a partial plan view showing a state where a fluorescent surface is formed and the photoresist layer is not removed, and FIG. 8 is an exploded perspective view showing a fluorescent dot array tube as an example of a fluorescent display tube, FIG. 9 is a sectional view of the same, and FIG. The figure is a schematic side view showing an example of an apparatus for implementing the fluorescent surface forming method. 1... Substrate, 2... Strip-shaped electrode, 3... Insulation/,
7,.1...-Photoresist i, ila...dot, 15...fluorescent surface. Surprise β □□□ U/ Hisashi

Claims (1)

[Claims] In the fluorescent display tube, in the electrode forming step, at least one row of strip-shaped electrodes made of a conductive material is provided on the substrate, and in the insulating layer forming step, the substrate surface including the strip-shaped electrodes is provided with:
forming an insulating layer that exposes a portion of the strip-shaped electrodes along the arrangement direction of the strip-shaped electrodes to form a segment electrode array; After covering the segment electrodes with a dotted layer, only the photoresist layer on each segment electrode constituting the segment electrode row is removed in dots to expose the segment electrode row. Droplets of a dispersion of fluorescent particles are applied to each of the segment electrodes to form a fluorescent surface, and in a photoresist layer removal step, the photoresist layer is removed. A method for forming a fluorescent surface, comprising forming a fluorescent dot array.