JP2002082340A - Method for manufacturing flat panel display - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a method for manufacturing a flat panel display, where the distance between substrates can be kept constant by fine barrier ribs, without exerting adverse influence on the substrates. SOLUTION: The method for manufacturing the flat panel display, having a display substance 33 interposed between substrates 31 and 34 comprises; first a barrier rib member 32 performed by a laser abrasion machining is fixed onto the lower substrate 31, next the display substance 33 is injected on the barrier member 32 and the upper substrate 34 covered over the display substance 33 so as to prevent air from entering into between them.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a flat panel display such as a liquid crystal display.

[0002]

2. Description of the Related Art In recent years, flat panel displays have
Because it has been offered at a low price, it has begun to spread widely as an alternative to CRT displays of the cathode ray tube type. Examples of the flat panel display include the following. First, in a liquid crystal display, liquid crystal is injected between substrates, and the display state is controlled by changing the polarization state by changing the alignment state by applying a voltage. In addition, the plasma display (P
DP) is a method in which a gas is sealed between the substrates and discharged to excite the phosphors to emit light. Further, the organic EL display is provided with a hole transport layer, a light emitting layer, and an electron transport layer between substrates to emit light when energized.

[0003] These displays are based on the principle of operating by applying a voltage between substrates. Therefore, control of the distance between substrates is important for display fabrication technology. This is because the variation in the distance between the substrates changes the electric field strength or changes the optical characteristics, thereby causing deterioration in quality such as display unevenness, and sometimes destroys the display contents.
Therefore, when the gap between the substrates is apt to fluctuate due to the application of pressure or the like, the display quality is degraded even by a small amount of pressurization.

[0004] In order to simplify the description below, a liquid crystal display will be described as an example. The following techniques are known and frequently used as techniques for keeping the gap between substrates of a liquid crystal display constant. The technique involves spraying spherical particles of a uniform size of several microns called spacers, which are made of plastic such as silica or polystyrene, between glass substrates to keep the distance between the substrates constant. This technique is a very excellent method for keeping the distance between the substrates constant.
It is widely used for TN type liquid crystal displays such as TLCD (thin film transistor driven liquid crystal display) and STN type liquid crystal displays. However, a display using a glass substrate has a disadvantage that it has a large mass, is inconvenient to carry, and is easily broken when subjected to an impact. Therefore, a structure using a flexible substrate has been studied.

[0005] When a flexible substrate such as a plastic substrate is used, it is not easy to keep the distance between the substrates constant even when a slight pressure is applied. When an external pressure is applied, the gap between the substrates greatly fluctuates, so that a stable gap cannot be maintained, particularly in the case of a plastic substrate. Therefore, it is known that the alignment state of the liquid crystal becomes unstable, and the display content disappears, the display becomes uneven, or the color changes. In order to solve these problems, a columnar wall is formed by printing by a printing method to keep the distance between the substrates constant, or a partition is formed by a photolithography method using a photosensitive resin such as a resist, and the distance between the substrates is reduced. A method for keeping the distance constant is known. By providing such partition walls and columnar walls, the alignment state of the liquid crystal becomes extremely stable against external pressure.

In a cholesteric liquid crystal display, a planar state, which is a selective reflection state in which light of a specific wavelength is efficiently reflected, and a focal conic state, which is a transparent or scattering state, are used as display modes. Both of them have a memory property, and even if the application of the voltage is stopped, the state is maintained without power supply. The planar state is an alignment state in which the helical axis of the cholesteric liquid crystal is perpendicular to the substrate, and Bragg reflection in the visible region occurs according to the helical pitch of the cholesteric liquid crystal. Therefore, it is used as a reflective display.

On the other hand, the focal conic state is a state in which the spiral axis is inclined parallel to the substrate, and when viewed from the substrate side, the spiral multilayer structure is not visible. Therefore, light is transmitted, and a transparent state is obtained. In general, in the focal conic state, a number of structural defects are present. Therefore, when the distance between the substrates is increased, light is scattered, resulting in a cloudy mode. These states are very sensitive to the application of pressure, and even when a glass substrate is used, the conventional method of spraying spacers changes the orientation state easily with changes in the substrate spacing. Would. In such a case, forming the partition walls and the columnar walls as described above is very effective not only when a glass substrate is used but also when a flexible substrate is used.

A column forming method by a printing method is disclosed in, for example,
As disclosed in JP-A-1-109368, a resin structure is formed by mixing a spherical spacer with a thermoplastic polymer and using a screen plate or a metal mask. The resin structure is polyvinyl chloride resin, polyvinylidene chloride resin,
A polyvinyl acetate resin or the like is used. Further, a method using a photosensitive resin such as a resist is described in, for example, Japanese Patent No. 266.
As disclosed in Japanese Patent No. 9609, a photosensitive polymer material is applied to a glass substrate or a flexible substrate, and a mask pattern is irradiated with light by a lithography method and developed to form a resin dam. . As the polymer material constituting the weir, a polyamide-based, polyester-based, polyimide-based, or polyethersulfone-based material is used.

[0009]

However, the above-mentioned printing method cannot achieve a fine line width in the resin structure, the wall height is not uniform, and requires a heat step because a thermoplastic polymer is used. There is a problem that the flexible substrate must be treated at a high temperature. The flexible substrate is vulnerable to high temperatures, and when heat exceeds the glass transition point, deformation occurs, which may impair flatness. In addition, the above-described method using a photosensitive resin is troublesome because a resist is applied, a pre-bake step is performed, exposure is performed, and a post-bake step is performed after the development step. Furthermore, since the resist is removed by the developing solution during the development, the underlying alignment film and the thin film on the substrate are directly in contact with the developing solution. For this reason, there is a disadvantage that a base such as an alignment film is damaged. Also, in a normal liquid crystal display, the thickness between the substrates is as thick as about 5 μm,
It is necessary to apply the photoresist for forming the partition wall several tens of times thicker than when forming the pattern of the integrated circuit. In this case, the line width of the resist used as the partition wall is limited to about 10 μm.

Accordingly, an object of the present invention is to provide a method of manufacturing a flat panel display in which the distance between substrates can be kept constant by fine partition walls without adversely affecting the substrates.

[0011]

An object of the present invention is to provide a method of manufacturing a flat panel display in which a display substance is sandwiched between substrates, wherein a step of fixing a previously manufactured partition member on one substrate, This is achieved by a method of manufacturing a flat panel display including a step of injecting a display substance onto a member and a step of covering the other substance with the display substance. Here, the partition member is preferably manufactured by laser ablation processing. The partition member can be formed of at least one material selected from the group consisting of a dielectric material, a polymer material, and a metal thin film. Also, the partition member is triangular, square, ladder-like,
It can be manufactured to have a pattern of at least one shape selected from the group of a matrix, a honeycomb, and a stripe. This partition member can be used as a spacer for defining the distance between the substrates. Further, the substrate can be formed of a flexible material.

The method for manufacturing a liquid crystal display according to the present invention includes a step of forming an alignment film on one substrate, a step of fixing a partition member previously formed on the substrate on which the alignment film is formed, and Injecting liquid crystal on the partition member,
Covering the liquid crystal with the other substrate. In this case, it is preferable to include a step of depositing an ultraviolet curable resin on the partition member before fixing the partition member to the substrate. Cholesteric liquid crystal can be used as the liquid crystal. In this case, the liquid crystal is maintained in a planar state with respect to at least a pressure of 8 kg / cm ² applied between the substrates. With such a configuration, even if the cell uses a flexible substrate such as a plastic substrate, the distance between the substrates is kept constant with sufficient strength, and the substrate is manufactured without causing deformation of the substrate. Can be.

[0013]

DESCRIPTION OF THE PREFERRED EMBODIMENTS In the method of manufacturing a flat panel display according to the present invention, a mesh sheet is separately prepared in advance as a partition member inserted in order to keep the distance between substrates constant. Therefore, first, a method for producing the mesh sheet will be described, and then, a method for producing a flat panel display will be described.

FIG. 1 is a view showing the structure of an apparatus for producing a mesh sheet by laser processing. As shown, on the movable stage 11, a fibrous body 12 is interposed.
Polyimide film 1 for a mesh sheet to be processed
Three are placed. The polyimide film 13 is irradiated with laser light 10 from an excimer laser oscillator 14 via a mask 15, a reduction optical lens 16, and a mirror 17. An assist gas is injected from the assist gas injection device 18 to the laser light irradiation surface of the polyimide film 13 during processing. In this example, a KrF laser was used as the excimer laser oscillation device 14, and the partition walls of the mesh sheet were formed by using a laser ablation technique. The maximum output of the KrF laser is 400 mJ,
In this example, the processing operation was performed by oscillating at 100 Hz with one pulse of 200 mJ.

The polyimide film 13 having a thickness of 7 μm is
It is fixed to the movable stage 11 by a vacuum chuck via a fibrous body 12 (for example, dust-free paper) as a cushioning material. This fibrous body 12, after laser ablation processing,
This is suitable for facilitating removal of the thin polyimide film 13 from the movable stage 11. As the mask 15 for laser irradiation, a mask for laser light shielding having a net-like pattern can be used. This reticulated mask is manufactured using a dielectric multilayer film, and unnecessary laser beams are reflected almost 100% by the dielectric multilayer film, and a desired pattern can be projected. The spacing corresponding to the mesh is 400 μm. The width of the partition on the mask is 20 μm.
In this embodiment, a reflecting mirror made of a dielectric multilayer film is used, but a less expensive metal mask can be used as a mask.

The exposure pattern by the mask is further reduced to 1/4 by the reduction optical lens 16 and irradiated onto the polyimide film 13. When processing the polyimide film 13, an assist gas injection device 18
, An assist gas (oxygen) is sprayed from the gas to promote stable gasification of plasma emitted by ablation. Further, the material transport is promoted by wind force generated by the assist gas, so that contamination of the polyimide film 13 can be prevented. The laser irradiation time for one area is 0.7 seconds.
That is, the polyimide film 13 is vaporized by the laser irradiation of 70 shots, and the partition can be formed.

FIGS. 2A and 2B are plan views of a mesh sheet as a partition member. For example, as shown in FIG.
Partitions having a square pattern with a line width of 5 μm are formed at intervals of μm. In addition, the partition pattern may be formed in a ladder shape as shown in FIG.

FIGS. 3A to 3C are process diagrams showing a method for manufacturing a flat panel display according to the present invention. The substrate may be flexible, for example, having a thickness of 125
A micron polycarbonate (PC) substrate is used.
The lower substrate 31 is formed as follows. First, P
ITO (indium-tin-oxide) on C substrate
The film is deposited by sputtering. Thereafter, a stripe-shaped matrix electrode is formed on the PC substrate through a photolithography process. Subsequently, an anti-reflection film (for example, H80 manufactured by Nissan Chemical Co., Ltd.) for preventing reflection from the ITO film
00) is provided on the electrode, and a PI (poly)
The lower substrate 31 is formed by applying an orientation film based on an imide).

On the other hand, a separately formed net-like sheet 32 is passed through an atmosphere of an ultraviolet-curing resin, and an ultraviolet-curing resin is deposited for about 500 ° to form a lower substrate 31 as shown in FIG.
Place on top. Alternatively, the alignment film forming surface of the lower substrate 31 may be overlaid on the mesh sheet 32. FIG. 4 is a perspective view showing this state. Thereafter, the net sheet 32 is fixed to the lower substrate 31 by irradiating ultraviolet rays and using an ultraviolet curing resin. Next, as shown in FIG. 2B, a cholesteric liquid crystal (chiral nematic liquid crystal) 3 is placed on the mesh sheet 32.
3 is added dropwise. Then, the upper substrate 34 on the opposite side is covered on the liquid crystal 33 as shown in FIG. At this time, the liquid crystal 33 is held in the partition wall of the mesh sheet 32 while taking care not to mix air, unnecessary liquid crystal is removed, and then the periphery of both substrates 31, 34 is sealed to produce a liquid crystal cell. I do. FIG. 5 is a partial sectional view showing this state. When a voltage was applied to the liquid crystal cell thus manufactured to form a planar state, green selectively reflected light was observed. At this time, it was confirmed that the planar state was not changed even when a pressure of 8 kg / cm ² or more was applied.

As described above, according to the present invention, a laser ablation method is used in producing a mesh sheet as a partition member. Therefore, this method will be described below in detail. ArF, Xe for laser ablation
An excimer laser using a gas such as Cl or KrF is mainly used. Excimer lasers have a short wavelength and are ultraviolet light, and therefore have high photon energy. When irradiated on a substance, the molecular bonds of the constituent molecules are broken and the molecules are decomposed, so that a plasma state is realized.

The plasma state is a gas state of atoms ionized positively and negatively, and easily scatters. In addition, this plasma state is unstable as it is, that is, it is chemically active, and may damage the surroundings. However, by oxidizing with an assist gas such as oxygen to promote stable gasification, the surroundings can be prevented. The effect can be greatly reduced. In this step, unlike the melting, the influence of heat can be suppressed because the molecular bond is instantaneously broken and decomposed. Therefore, even a thin film does not undergo thermal deformation and is suitable for fine processing.

In the case of polymer materials, C—C, CＣC, and C—H
In many cases, these polymer bonds are formed by molecular irradiation such as excimer laser, and these polymer bonds are selectively cut by a multiphoton process, thereby realizing a plasma state by molecules and atoms. In the example using the polyimide film, the plasma-converted polyimide combines with the assist gas and oxygen present in the air and scatters as carbon dioxide gas and water vapor. Fine processing that faithfully reflects the mask pattern can be performed without undergoing any substantial deformation.

Regarding the contamination of the processing part and the surroundings by the laser ablation processing, the gasification of the plasma-processed work is promoted by using an assist gas by oxygen, so that the generation of contamination and particles is sufficiently suppressed. You can also. Also, in the removed part,
Scum that seems to be the rest of the polymer may be seen,
This is thinly deposited and adhered on a fibrous body (for example, dust-free paper) for fixing the polyimide film. Furthermore, since a laser beam is applied to a workpiece such as a resin through a reduction optical system using a lens system, a pattern in which the actual mask dimensions are accurately reduced and reflected can be formed with high precision.

In the present invention, by processing the polymer film using this laser ablation method, the shape of the mesh sheet can be changed to a triangle, a square, a ladder, a matrix, or the like.
It can be manufactured in a variety of forms such as a honeycomb shape or a stripe shape, and is bonded and arranged on a flexible substrate to form a partition. That is, the present invention is to irradiate the film member with laser light by laser ablation method,
By forming a mesh sheet having fine partition walls, which cannot be obtained by the conventional technique, and sandwiching the mesh sheet between substrates, a cell that is stable against pressure application is manufactured.

A partition forming method using a laser ablation method is disclosed in, for example, Japanese Patent Application Laid-Open No. 9-90327. In this technique, a polymer material is coated on a glass substrate in advance, and a laser is applied from above the glass substrate. Irradiation of light removes unnecessary portions of the polymer material to form partition walls. However, in this method, there is a possibility that the alignment film, the insulating film, the transparent electrode, or the like applied on the upper portion of the glass substrate may be damaged by laser ablation.
When a flexible substrate is used, the flexible substrate itself may be damaged by laser ablation. In order to avoid this kind of damage, high precision is required for laser light output control. For this reason, implementation in this manner would be practically difficult. Even when a glass substrate is used, the polymer material scattered by laser ablation does not exist in the partition walls, but remains as scum in the removed portion, and the removal is not easy. In the present invention, since the mesh sheet made of a polymer material is separately prepared by laser ablation, and the mesh partition is sandwiched between the substrates, the above-described problem does not occur.

Next, the accuracy of the partition walls will be described. In the present invention, the distance between the partition walls is 10 μm and the width of the partition walls is 5 μm.
m network pattern can be formed by laser ablation processing. Since such extremely fine partition walls can be formed, a high-definition net-like sheet can be obtained, and a flat panel display with a high aperture ratio can be manufactured. If the demand for finer partition walls is not high, this kind of net-like sheet can also be produced by thermal processing using a carbon dioxide gas laser.

In the present invention, the net-like sheet produced in this way is adhered on a lower substrate, liquid crystal is dropped on this net-like sheet, and the upper substrate is adhered on it in such a manner that air does not enter. . Thereafter, the liquid crystal protruding from the periphery is removed to complete the liquid crystal cell. When formed in this manner, there is an advantage that the orientation film on the substrate and other functional films on the substrate that are strongly affected by the normal resist process are not affected in principle by the partition wall forming process.

When the beam diameter of the excimer laser is limited to a radius of about several tens of millimeters,
When fabricating a net-like sheet for a liquid crystal display of about inches, not all the partition walls can be formed by a single laser irradiation. In that case, it is possible to cope by moving the irradiation position and irradiating the beam in a plurality of times. In the present embodiment, a method for manufacturing a liquid crystal display has been described as an example. However, the present invention is not limited to this and can be applied to other methods for manufacturing a flat panel display.

[0029]

According to the present invention, it is possible to manufacture a flat panel display having high manufacturing efficiency and stable against pressure application. Further, since extremely fine partition walls can be formed without adversely affecting the substrate, a flat panel display with a high aperture ratio can be manufactured.

[Brief description of the drawings]

FIG. 1 is a diagram showing an apparatus configuration for producing a mesh sheet by laser processing.

FIGS. 2A and 2B are plan views of a mesh sheet.

FIGS. 3A to 3C are process diagrams showing a method for manufacturing a flat panel display according to the present invention.

FIG. 4 is a perspective view showing a mesh sheet fixed on a lower substrate.

FIG. 5 is a partial cross-sectional view showing a step of covering an upper substrate on a display material (liquid crystal).

[Explanation of symbols]

 31 lower substrate 32 net-like sheet 33 display substance (liquid crystal) 34 upper substrate

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Toshihide Tanaka 2274 Hongo, Ebina-shi, Kanagawa Prefecture Fuji Xerox Co., Ltd. (72) Inventor Taketo Hikiji 2274 Hongo, Ebina-shi, Kanagawa Prefecture Fuji Xerox Co., Ltd. 2H089 HA15 LA09 LA10 LA19 LA20 NA07 NA13 NA17 NA22 NA35 NA58 QA12 QA14 RA16 TA04 2H090 JA03 JB03 KA09 LA02 5C094 AA03 AA10 AA43 EC03 EC04 GB10 5G435 AA03 AA07 AA17 BB12 CC09 KK05

Claims (10)

[Claims] 1. A method for manufacturing a flat panel display in which a display substance is sandwiched between substrates, wherein a step of fixing a partition member prepared in advance on one substrate and injecting the display substance onto the partition member. A method of manufacturing a flat panel display, comprising: a step of covering the display substance with another substrate. 2. The method for manufacturing a flat panel display according to claim 1, wherein the partition member is manufactured by laser ablation processing. 3. The flat panel display according to claim 1, wherein the partition member is made of at least one material selected from the group consisting of a dielectric material, a polymer material, and a metal thin film. Method. 4. The partition member according to claim 1, wherein the partition member has at least one pattern selected from the group consisting of a triangle, a square, a ladder, a matrix, a honeycomb, and a stripe. A method for producing a flat panel display according to the above item. 5. The method according to claim 1, wherein the partition member is used as a spacer for defining a distance between the substrates.
5. The method for manufacturing a flat panel display according to any one of items 4 to 4. 6. The method according to claim 1, wherein the substrate is made of a flexible material. 7. A method for manufacturing a liquid crystal display in which a liquid crystal is sandwiched between substrates, comprising a step of forming an alignment film on one substrate, and a step of forming a partition member previously formed on the substrate on which the alignment film is formed. A method for manufacturing a liquid crystal display, comprising: a step of fixing; a step of injecting a liquid crystal onto the partition member; and a step of covering the liquid crystal with another substrate. 8. The method of manufacturing a liquid crystal display according to claim 7, further comprising a step of depositing an ultraviolet curable resin on the partition member before fixing the partition member to the substrate. 9. The method according to claim 7, wherein the liquid crystal is a cholesteric liquid crystal. 10. At least 8 kg applied between the substrates
/ Relative pressure of cm ^2, a method for manufacturing a liquid crystal display according to claim 9, wherein said liquid crystal is characterized in that in order to maintain the planar state.