JPH0756543B2 - Liquid crystal display device manufacturing method - Google Patents

Description

TECHNICAL FIELD The present invention relates to a liquid crystal display panel or an active matrix liquid crystal display panel, and a liquid crystal for thinning a display unit of a microcomputer, a word processor, a television, or the like. The present invention relates to a method for manufacturing a display device.

[Prior Art] Regarding a conventional liquid crystal display device, a transparent conductive film and an alignment film are provided inside two transparent substrates, respectively, and liquid crystal is filled between them to determine whether or not a voltage is applied between two electrodes. It controlled "on" and "off". Then, by this display, a character, a graph or a picture is displayed.

However, there is a thick gap of about 10 μ between these two transparent electrodes, and these gaps have recently become as small as 5 μ. However, such a wide interval is necessary in TN (Twiftec nematic) type liquid crystal, but it is a chiral smectics C.
If a ferroelectric liquid crystal using a phase (hereinafter referred to as FLC) is used, 3 μ or less is generally required to be 2 ± 0.5 μ.

In the past, when a known TN liquid crystal was filled into this 10 μ space by using surface tension, a spacer that controls this space was devised. That is, the spacers are generally spherical particles of organic resin, such as Micropearl SP-210 (average particle size 1
0.0 ± 0.5μ) is used. The micro pearls are divinylbenzene-based cross-linked polymers and are transparent true fine particles.

That is, FIG. 1 shows a vertical sectional view of a conventional liquid crystal display device. In the drawing, a sealing material (6) is prepared by mixing a resin and a spacer (7) around the periphery of two transparent substrates (1) and (1 ') for displaying liquid crystal so that liquid crystal does not leak to the outside.
Are stored, and the distance between the two substrates is kept constant in the peripheral portion. However, when the transparent substrate is mechanically stressed from the outside in the display part (10), that is, the region filled with the liquid crystal (5), or due to the lack of flatness of the substrate, the two transparent electrodes are shorted or close to each other. Cheap. As a result, the liquid crystal is not translucent, or a part of the liquid crystal is blackened, and defects are likely to occur. For this reason, other micropearl spacers (4) are scattered also in the liquid crystal part to keep the respective electrodes at a constant distance so as not to short-circuit.

However, the spacers were merely scattered between the alignment films and made point contacts with each other, and a large local load was applied to these contact parts. If there is an active element at this contact portion, this element may be destroyed.

“Problems to be solved by the invention” Furthermore, when actually manufacturing a liquid crystal display device using this TN liquid crystal, after sealing the two substrates with a sealing material except for a part of the periphery, The vacuum is kept and the liquid crystal is filled by utilizing the capillary phenomenon. However, the interval is 3μ
For liquid crystals such as FLC that require less than that, the spacers may move when filling by utilizing the capillary phenomenon, and the spacers themselves are more and more likely to aggregate with each other, so that they are evenly dispersed. Was impossible.

Moreover, since the spacer and the alignment film are not adhered at all,
After the sealing, when the temperature of the display device rises, the substrate tends to swell due to the thermal expansion of the liquid crystal itself, and the distance between the two electrodes cannot be kept constant. For this reason, it has been observed that the display contrast differs between the central part and the peripheral part. In particular, when the display device had a large panel shape of 20 cm x 30 cm, defects were likely to occur. Further, since the positions where the spacers are scattered are scattered, in a display in which active elements are connected, a stress may be locally applied to the elements, which easily causes a failure of the elements.

[Means for Solving the Problem] Therefore, the present invention does not use a conventionally known spacer made of a single substance, but a transparent electrode or this electrode and a filter (red, green, blue) on one substrate upper side. (Color filter) and alignment treatment or an alignment film is formed on the surface of the substrate and covered with a photosensitive organic resin such as a polyimide precursor at a predetermined height by a coating method, etc., and a transparent electrode or a filter with this is applied from the back side of the substrate. And (2) are used as effective masks for light (ultraviolet light) irradiation. Then, the light is transmitted through the gap between the transparent electrodes where the mask is not formed, and the photosensitive resin can be exposed. In this way, only the region without a mask is selectively exposed to light, and then a linear "scallop" spacer is selectively formed only in the insulating region between the electrodes in the etching process. As a result, the end portion of the pixel on which the transparent electrode is provided is made to substantially coincide with the end portion (including deviation due to over-etching or under-etching at the time of etching that slightly wraps around light) and the spacer is provided in the insulating region. You can Further, at the same time, the sealing material in the peripheral portion is formed with the same material and at the same height (thickness). Therefore, in particular, a photosensitive polyimide resin is used as the applied organic resin, and the electrode or the electrode and the filter act as an effective mask, thereby omitting the step of using a so-called photomask.

[Action] By doing so, the resin that acts as a spacer has its height made of the same material as the sealing material in the peripheral part and the spacer of the display part, and the coating film with the same height variation remains selectively. Since it is made of metal, it is possible to obtain a predetermined thickness of ± 0.5μ or less. In addition, since the sealing material and the material for the spacer are not used for the electrode portion, the aperture ratio can be improved. Further, when performing full-color display, for example, when displaying red, this stripe spacer can prevent green or blue of the adjacent pixel from partially transmitting due to light leakage. Furthermore, this material is in close contact with the inner surface of the other translucent substrate that opposes. For this reason, even if the two substrates initially have some non-flatness due to the wavy irregularities of the substrates themselves, at least one of the substrates has such a hardness that it can be deformed by applying semi-hard pressure. By this, the size (height) of the sealing material and spacer
Can be made constant. That is, it was formed not on the electrodes but in the electrode gap in a self-aligned manner. After forming the seal part and the space part with this polyimide resin striped “scallop”, another electrode having semi-hard translucency is placed on the upper side of the electrode in vacuum with the electrode or the filter,
The surface side on which the alignment film is formed is arranged to face each other. After that, the outside is pressurized (atmospheric pressure), the inside is vacuum (decompressed), the pressure is applied from the outside, and at the same time, heating is performed, and the respective spacers and sealing materials are brought into close contact with other surfaces by the press cure method. Then, due to the seal portion and the spacer portion which are in close contact with each other, the respective substrates are substantially in close contact with each other even if a vacuum is applied thereafter, so that the original non-flat state is not returned and the gap between the electrodes is kept constant. Therefore, in the final state, there is no problem such as a part of the panel being too wide. Further, since the substrates are closely attached by the spacer, the mechanical strength of the display panel itself is not the strength of only one sheet,
It has become possible to have a strength close to that of laminated glass, which is substantially equal to the strength of two sheets.

The present invention will be described below according to examples.

Embodiment 1 FIG. 2 is a vertical sectional view showing a manufacturing process of a liquid crystal display device of the present invention.

In FIG. 2 (A), two transparent substrates, for example, glass substrates (1) and (1 ′), one is a hard glass substrate (1 ′) (in the drawing, only shown in FIG. 2 (C)) The other Used a semi-hard glass plate or a heat-resistant translucent organic resin substrate (1) (a heat-resistant deflecting plate can also be used as this substrate) which can bend when the gap is evacuated.

A predetermined color filter (not shown in the drawing) and a liquid crystal electrode were formed on one surface of the semi-hard substrate (1) by a transparent conductive film (2) such as ITO or SnO ₂ . An insulating region (22) is provided between each electrode. A polyimide resin (3) was thinly formed on this upper surface, and an alignment treatment was performed by a known rubbing treatment. The other FIG. 2 (C)
Although not shown in the figure, the same transparent conductive film (2 ') and alignment treatment (3') were performed on the hard substrate (1 '). This substrate (1 ') has active elements provided thereon in the region (24) corresponding to each pixel.

Next, as shown in FIG. 2 (A), an ultraviolet-curable polyimide precursor solution (15) is applied to the upper surface on one side by a spinner, a roll coater, a spray method or a screen printing method.

This polyimide solution was a wholly aromatic polyimide precursor solution (15), and as an example, Photo Nice sold by Toray Industries, Inc. was used.

The thickness of this coating is reduced by 40 to 50% due to post-baking.

Next, as shown in FIG. 2 (A), this polyimide precursor solution (15) was applied and then prebaked at 80 ° C. for 60 minutes.

Next, to make a hole in the seal part to fill the liquid crystal in a later process,
Write a guide line (face) on the lower side of the substrate (1) with magic ink (black). Then, since no ultraviolet light is applied to this portion, the sealing material is not formed and the hole can be used as a liquid crystal filling hole.

After that, UV light (20) was exposed from the back side of the substrate (10 mW / c
Light with m ² intensity was applied for about 30 seconds). Then, ultraviolet light is blocked by the transparent electrode (2) or the red (R), green (G), and blue (B) filters provided on the upper side or the lower side of the transparent electrode (2). The precursor (15) is not light sensitive. Then, only the polyimide precursor in the insulating region (22) and the seal portion around the substrate can be exposed. That is, the spacer can be formed in self-alignment with the electrode gap.

When a filter is provided on the glass surface as a mask for this ultraviolet light, and a transparent electrode is further formed on the glass surface, a method of applying weak light for a long time, for example, 2 to 3 minutes in order to prevent the filter from fading due to exposure to ultraviolet light. Is preferred. On the other hand, when a transparent conductive film is formed in close contact with the glass surface and a filter is formed on it, the ultraviolet light has an optical energy band width of 4 eV or more (wavelength of 310 nm or less, for example, 254 nm).
The transparent conductive film acts as a mask. In this case, the filter is not exposed to ultraviolet light, so it is possible to prevent fading.
A 30 second exposure is sufficient.

For this reason, one spacer of the liquid crystal connected in series to the active element is 400 μ ^□ , and the spacer is the insulating region (electrode interval) 20
If it is μ, it is not necessarily formed on the active element and the transparent electrode, and the spacer (1
It was possible to make a “scallop” as 4) with its end roughly corresponding to the end of the pixel (filter or electrode). At the same time, in the peripheral portion of the substrate, a liquid crystal filling hole having a width of about 5 mm was removed, and a scallop as a sealing material (6) was provided so as to surround pixels inside the other portion. That is, it is possible to disperse the spacers with a predetermined interval in a scattered manner. Furthermore, by making a "scallop" by this maskless self-aligning method, in the case of an active type liquid crystal panel, this element is also non-translucent even in the region where wiring, non-linear elements or switching elements exist. Therefore, similarly, the organic resin above it is not exposed to light, and as a result, it is possible to intentionally avoid the presence of the spacer in the region where the element exists. That is, it is possible to avoid the possibility that the lead will be disconnected or the element will not operate due to mechanical stress or the like in the subsequent use by the spacer.

After that, the development is carried out by an ultrasonic development method at 25 ° C. for 25 minutes for a predetermined DV.
Performed using -140. Furthermore, ultra-long-wave rinse was performed with isopalonol at 25 ° C for 15 seconds.

Thus, as shown in FIG. 2B, the filter and the translucent conductive film (2) on the translucent substrate (1) and the polyimide alignment film (3) on the filter and the translucent conductive film (3) are in close contact with each other to form the outer periphery. The sealing material (6) and the spacer (14) of (3) could be arranged in the electrode gap and the peripheral portion.

Next, as shown in FIG. 2 (C), the upper side of FIG. 2 (B) is arranged upside down (to be the lower side), and another substrate (1 ′) on which active elements have been formed in advance is placed on top of it. The transparent substrate (1 ') having the transparent electrode (2') and the alignment film (3 ') provided on the upper surface thereof was opposed to each other and combined. Further, vacuuming of all of them was performed at the same time as this combining step. After maintaining this vacuum state, atmospheric pressure or reduced pressure (100 to 400
As a torr), the substrates were pressed against each other from the outside, and additionally post-baked at 200 to 400 ° C., for example, 180 ° C. for 30 minutes + 300 ° C. for 30 minutes + 400 ° C. for 30 minutes. We also invented the so-called "press cure system". Then, the scallops (6) and (14) are brought into close contact with the opposing substrate or the polyimide scallops or the alignment film on this (inner surface), so that the two glasses can be attached to each other.

After this post bake, its height is 3μ or less,
In this case, the interval was set to 2.2 μ ± 0.5 μ, which was a preferable interval for FLC.

In this case, if at least one of the opposing glasses has a semi-hard hardness, the other glass is aligned according to the distortion that the glass itself has, and the spacers fix each other, so the glass substrate itself is distorted. Even if it has (smooth uneven waviness), it is possible to substantially bond the opposing substrates to each other with the electrode gap kept constant irrespective thereof.

In the example of the present invention, thereafter, the ferroelectric liquid crystal (5) was filled in the gap held by the spacer by a known method.

FIG. 3 shows a plan view (A) and a vertical sectional view (B) of a part of the liquid crystal display panel corresponding to FIG.

FIG. 2 (C) is a vertical sectional view taken along the line AA ′ in FIG. 3 (A). A vertical cross-sectional view of BB 'is shown in FIG.
Shown in.

In the drawing, a linear transparent electrode (the electrode (2) in contact with the upper substrate in FIG. 2 (C)) is formed in the X direction, and the FLC is filled from the lower side with surface tension in the drawing (A). Further, FIG. 3 (B) is a vertical sectional view taken along the line BB ′ in FIG. 3 (A).

FIG. 3 (B) is abbreviated.

On the lower transparent electrode substrate (1 ') side, the active element (2
5), transparent electrode (2 '), alignment film or alignment treatment (3')
Is provided. The active element is the lower electrode (21),
It is composed of a non-linear element (22) and an upper electrode (23). This element (25) is mechanically protected, and an insulating material (24) is provided in the periphery to flatten the electrode (2 '). There is. The electrode (21) of this active element is the lead (31) in the Y direction.
The electrode (23) is in close contact with the transparent electrode (3 ') corresponding to each pixel. Therefore, in FIG. 2C which is a vertical sectional view taken along the line AA ′ in FIG. 3A, the insulator (24) around the substrate (1 ′) is shown, and the transparent electrode is formed on these. (2 '), an alignment film or alignment treatment (3') is provided. The color filter is provided on either side (here, the side (2)) of the transparent electrode (2) or (2 '). FLC (5) is filled between the transparent electrodes or between the alignment films.

Thus, as shown in FIG. 3 (A), the spacer (14)
And the sealing material (6) could be provided without using any photomask.

Of course, in FIG. 2C, it is also possible to form a simple matrix structure by using a stripe in the Y direction without using any active element on the lower substrate and combining it with a stripe in the X direction of the upper substrate. It is valid.

In addition, the spacer sealing material is formed on the side where the active element is not formed in this embodiment. However, conversely, it may be formed on the active element side or on both sides.

[Effect] As described above, in the present invention, in order to make the gap between the two electrodes facing each other constant, the polyimide resin film is selectively left to have a constant height. Further, the spacer and the sealing material and the polyimide-based alignment film made of the same material are closely adhered to each other by a press cure method. As a result, 2
The distance between the two alignment films could be kept constant within a predetermined thickness ± 0.5μ. In particular, in a liquid crystal panel with a large area of 20 cm × 30 cm that has an active matrix structure and the number of dots is 400 × 1920, the central part swells more than necessary,
It was also possible to prevent the two electrodes from approaching each other.

For this reason, in the past, when a liquid crystal was made using a large-area substrate, the inner surface of each substrate had to be polished extremely accurately, and the sealing material and the spacer were completely different materials, different materials. It was made by the process. In addition, the spacer did not adhere to the inner surfaces of the upper and lower substrates. Moreover, the position of the spacer could not be estimated. However, in the present invention, the price of such a glass substrate is
It has another feature that there is no polishing process which is 5 times expensive and the process of sealing with a sealing material and the process of scattering spacers can be simplified as one process.

In addition, since one spacer is provided between the electrodes, that is, at an interval of about 400 μ, it has become possible to handle the liquid crystal panel as an extremely strong substrate like a so-called laminated glass.

The shape of the spacer could be a surface contact or a line contact with the substrate surface instead of a point contact, and the spacer could be made into a black matrix (prevent light leakage of an adjacent color).

In the present invention, the alignment film may be left on or removed from the glass substrate in the sealing material portion around the glass substrate.

In the present invention, when ultraviolet light uses only a transparent electrode as a mask, the optical energy bandwidth of the electrode is ~ 3.
Since it has 5 eV, it is effective to use light of 4 eV or more (310 nm or less). Also, if you have color filters (R, G, B) at the same time, this filter easily fades, so weak ultraviolet light (generally 3 to 5 mW / cm ² of wavelength of 300 to 400 nm)
Is effective.

In the present invention, the same main component material was used for the “scallop” and the alignment films above and below it. This is because the adhesiveness is improved by making all of them polyimide-based. However, other materials may be used as long as this adhesion is guaranteed.

[Brief description of drawings]

FIG. 1 is a vertical sectional view of a conventionally known liquid crystal display device. FIG. 2 shows a vertical cross-sectional view of the manufacturing process of the liquid crystal display device of the present invention. FIG. 3 shows a plan view and a vertical sectional view of the liquid crystal display device of the present invention.

Claims (2)

[Claims] 1. A step of forming a film of a photosensitive organic material capable of forming a spacer on a substrate having wiring, a region where a non-linear element or a switching element exists and a transparent electrode, and a step of forming a photosensitive organic material from the back surface side of the substrate. Using the region and the transparent electrode as a mask for the coating film, irradiating light blocked by the transparent electrode to expose the organic material in an insulating region between the transparent electrodes other than the mask, and the organic material A method for manufacturing a liquid crystal display device, which comprises removing an unexposed organic material by etching. 2. A transparent electrode and a region in which a light-shielding line or surface is formed on the back surface side of the transparent substrate, and the transparent electrode is provided on the substrate including a pixel and an insulating region between the pixels. Forming a photosensitive organic material in the form of a film, and irradiating the material with light blocked by the transparent electrode from the back side of the substrate using the transparent electrode and the light-shielding line or surface as a mask, A method of manufacturing a liquid crystal display device, comprising: exposing an organic material other than a mask, which is irradiated with light, to light; and removing an unexposed organic material from the organic material by etching.