JPH0441809B2 - - Google Patents

Description

[Detailed Description of the Invention] Field of Application of the Invention The present invention relates to a liquid crystal display panel or an active matrix type liquid crystal display panel, and is used to reduce the thickness of display sections of microcomputers, word processors, televisions, etc. The present invention relates to a method for manufacturing a liquid crystal display device.

〓Conventional technology〓 Regarding a conventional liquid crystal display device, a transparent conductive film and an alignment film are provided on the inside of two transparent substrates, and liquid crystal is filled between the two transparent substrates to determine whether or not a voltage is applied between the two electrodes. ``On'' and ``Off'' were controlled. This display displays characters, graphs, or pictures.

However, there is a thick gap of about 10 microns between these two transparent electrodes, and recently this gap has increased to 5 microns. However, such wide spacing is necessary for TN (Zwiftek Nematic) type liquid crystals, but if a ferroelectric liquid crystal (hereinafter referred to as FLC) using a chiral smectic C phase is used,
2μ or less, generally 1±0.5μ is required.

In addition, when conventionally known TN liquid crystals are filled using surface tension at intervals of 10μ, a spacer was devised to control the distance between them. That is, the spacer is generally a spherical particle of organic resin,
For example, Micropearl SP-210 (average particle size 10.0±
0.5μ) is used. This micropearl is a divinylbenzene-based crosslinked polymer and is a transparent true spherical fine particle.

That is, FIG. 1 shows a vertical cross-sectional view of a conventional liquid crystal display device. In the drawing, a sealing material 6 made of a mixture of resin and a spacer 7 is collected around two transparent substrates 1 and 1' for liquid crystal display to prevent the liquid crystal from leaking to the outside. The distance is kept constant at the periphery. However, the display section 10
That is, in the region filled with the liquid crystal 5, the two transparent electrodes tend to shoot or come close to each other due to mechanical stress of the transparent substrate from the outside or the flatness of the substrate. As a result, the liquid crystal loses its translucency or becomes partially black, which tends to cause defects. For this reason, other spacers 4 are scattered around the liquid crystal section to keep the respective electrodes at a constant distance from each other so as not to shoot.

These spacers were simply scattered between the alignment films and were in point contact with each of them, and a large local load was applied to these contact areas. If there is an active element in this contact portion, this element may be destroyed.

〓Problems to be solved by the invention〓 Furthermore, when trying to actually make 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, is kept in a vacuum and filled with liquid crystal using capillary action. However, liquid crystals such as FLC, which require a spacing of 2μ or less, have a high viscosity, so the spacer may move when filled using capillary action, and the spacer itself is small. , they tended to aggregate with each other more and more, and it was impossible to disperse them uniformly.

In addition, since the spacer and alignment film are not bonded in any way, when the temperature of the display device rises after sealing, the substrate tends to swell due to thermal expansion of the liquid crystal itself, making it impossible to maintain a constant distance between the two electrodes. .
For this reason, a phenomenon has been observed in which the contrast of the display differs between the center and the periphery. Defects were particularly likely to occur when the display device became a large panel measuring 20 cm x 30 cm. Furthermore, since the spacers are scattered at different positions, in a display in which active elements are connected, point stress may be locally applied to the elements, which is likely to cause element failure.

〓Means for Solving the Problem〓 For this reason, the present invention does not use a conventionally known spacer made of a single unit, but instead sets one substrate side provided with a laminate having a masking function to a predetermined height. The substrate is covered with an organic resin film such as polyimide resin using a coating method, and then light is irradiated from the back side of the substrate to selectively form "scallop"-shaped spacers at predetermined positions without using a mask. It is. Furthermore, at the same time, the sealing material in the peripheral area is also made of the same material. For this reason, in particular, by using a positive resist on the polyimide resin to be applied, etching and removing the resist other than the upper part of the laminate, and then removing the polyimide resin, it is possible to apply a positive resist to the upper part of the laminate. Spacers could be formed in the same shape. In this way, it became possible to produce spacers and sealants without having to use new masks.

Of course, if the organic resin film for the spacer, such as polyimide resin, has positive photosensitivity, the positive photosensitive polyimide resin is coated by a coating method without using a positive resist, and then ultraviolet light is irradiated using the laminate as a mask. A spacer can be created by removing the polyimide resin which has a masking effect and is not located above the laminate without using any mask.

Effect: By doing so, it became possible to create a spacer on a previously provided laminate having a mask effect without using a new mask. In addition, the laminate having this masking effect is, for example,
Nonlinear elements are generally made of a laminate of a non-single crystal semiconductor having an NIN structure and a pair of electrodes above and below the semiconductor, or a laminate having an MIM (metal-insulator-metal) structure.

In this way, the height of the organic resin that acts as a spacer can be achieved by using the same material as the sealing material in the peripheral area and the spacer in the display area, and the same coating film can be selectively left even with variations in height. Because of this, we were able to obtain an accuracy of less than ±0.2μ.
In addition, this sealing material and a spacer are used to bring the substrate into close contact with the inner surface of another opposing light-transmitting substrate.
Therefore, even if the two substrates initially have some degree of non-flatness due to the undulation-like unevenness of the substrates themselves, it can be made constant by the size (height) of the sealing material and the spacer. That is, after forming the seal portion and the spacer portion in the shape of a “scallop” using polyimide resin, another substrate having semi-hard translucent properties is placed above it in a vacuum, and heated to bring them into close contact. Then, due to the sealing part and the spacer part being in close contact with each other, even if the vacuum is removed afterwards, the respective substrates are substantially in close contact with each other, so they do not return to their original non-flat state and the gap between the electrodes remains constant. Therefore, in the final state, problems such as part of the panel being too wide do not occur. In addition, because the substrates are brought into close contact with each other using spacers, the mechanical strength of the display panel itself is not as strong as that of only one panel, but is similar to that of laminated glass, making it possible to have a mechanical strength that is essentially equivalent to the strength of two panels. It became.

The present invention will be described below with reference to Examples.

Embodiment 1 FIG. 2 shows a vertical cross-sectional view showing the liquid crystal display device of the present invention and its manufacturing process.

In FIG. 2A, two transparent substrates, for example glass substrates 1 and 1', one is a solid glass substrate 1,
On the other hand, a semi-hard glass plate or a translucent organic resin substrate 1' was used that could be bent when the gap was evacuated.

One side of this hard substrate 1 is connected to the lower lead 1.
1. It has a stacked body 50 consisting of a non-linear element 12 made of a non-single crystal semiconductor having an NIN junction and an upper chromium electrode 13. A transparent interlayer insulator 8 is provided around the laminate 50. A transparent conductive film 2 and an alignment film 3 are provided on the laminate of the lower substrate 1, and the transparent conductive film 2 and the upper electrode 13 of the laminate 50 are electrically connected in series.

Although only shown in FIG. 2C, a similar transparent conductive film 2' and alignment treatment 3' were also performed on a semi-hard substrate 1'.

Next, as shown in FIG. 3A, a polyimide solution 15, e.g.
Apply PIQ.

Further, a positive photoresist (not shown in the drawing) is applied thereon.

Next, these are exposed to ultraviolet light from the bottom side of the substrate through the substrate (approximately 60 mW/cm ² of light is applied).
seconds) did. Then, since this laminate 50 has a light-shielding property, only the resist above it can be left and the other parts can be removed. Use this resist as a mask to
Removed PIQ. Thereafter, the positive resist was removed to obtain the image shown in FIG. 2B.

At the same time, a "scallop" as a sealing material 6 was provided at the periphery of the substrate with a width of 3 mm to surround the inside of the other parts except for the liquid crystal filling part. That is, it becomes possible to arrange the spacers in a scattered manner with substantially a predetermined interval between the spacers. Furthermore, by creating a "scallop" using this mask method, in the case of an active type liquid crystal panel, localized mechanical stress is applied to nonlinear elements or switching elements, causing leads to break or the elements to become inoperable. You can avoid the possibility of

Furthermore, in order to further complete the method of the present invention, a second
As shown in Figure C, a semi-hard facing transparent substrate 1' with a transparent electrode 2' and an alignment film 3' provided inside
The gap was vacuumed at the same time as the press. In this state, post-baking was performed at 200 to 300°C. Then, the scallops 6 and 14 came into close contact with the polyimide alignment film of the opposing glass, making it possible to glue the two glasses together.

After this post-bake its height should be 2μ or less in this case 1.2μ±0.2μ.
This was the preferred spacing for FLC.

In this case, if the opposing glass or translucent organic resin is made semi-hard, the other translucent substrate 1' is aligned with the distortion of the glass 1 itself, and the spacers are used to secure them together. Therefore, even if the glass substrate itself has distortion (smooth unevenness), the electrode gap can be kept constant and the opposing glasses can be substantially bonded to each other regardless of the distortion.

In the embodiment of the present invention, the gap held by the spacer was then filled with ferroelectric liquid crystal 5 by a known method.

<Effects> As described above, the present invention selectively leaves one polyimide resin film and uses the same upper and lower polyimide alignment films as a spacer and sealing material in order to maintain a constant gap between two opposing electrodes. and are placed in close contact with each other. The manufacturing process was carried out without using any new masks. As a result, the distance between the two alignment films is
The thickness could be kept constant within the range of ±0.5μ within a predetermined thickness of 2μ or less. In particular, it has an active matrix structure,
In a liquid crystal panel with a large area of 20 cm x 30 cm, which has 400 x 1920 dots, it was possible to prevent the central part from swelling more than necessary or the two electrodes from coming close to each other.

For this reason, in the past, when attempting to manufacture a liquid crystal display device using large-area substrates, each substrate had to be polished extremely precisely, and the sealant and spacer were made of completely different materials. Ta. In addition, the spacers were not in close contact with the inner surfaces of the upper and lower substrates. Furthermore, the position of the spacer could not be estimated. However, the present invention has other features such as not requiring an expensive polishing process that is 2 to 5 times the price of the glass substrate, and simplifying the process of sealing with a sealing material and the process of dispersing spacers into one. have

In addition, since one to several spacers (one spacer in the example) are provided at a distance of approximately 400 μm, the liquid crystal panel can now be handled as an extremely strong substrate similar to so-called laminated glass.

The shape of the spacer can be made into surface contact rather than point contact with the substrate surface, and its area can also be freely controlled.

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

In the present invention, a polyimide solution was used. However, the spacer and sealing material may be formed using a selective etching method using an ultraviolet curable polyimide (positive) resin. However, such positive-type polyimide resins are not commercially available and are still in the experimental stage, so at present the resist coating step can be omitted, but it is expensive.

In the present invention, the same main component material is used for the "scallop" and the alignment films above and below it. This is because all the materials are made of polyimide to improve their adhesion to each other. However, other materials may be used if this adhesiveness is guaranteed.

[Brief explanation of drawings]

FIG. 1 shows a longitudinal sectional view of a conventionally known liquid crystal display device. FIG. 2 shows a longitudinal sectional view showing the manufacturing process of the liquid crystal display device of the present invention.

Claims (1)

[Claims] 1. A step of forming a laminate having a masking effect and a transparent electrode on a transparent substrate, a step of forming a transparent organic resin film on these, and a step of forming a transparent electrode on the resin film. a step of forming a photoresist film for use, a step of irradiating light from the back side of the substrate and selectively forming the resist into a predetermined shape using the laminate having a masking effect as a mask; forming the organic resin film into a predetermined shape using the resist as a mask, and forming the remaining organic resin film as a spacer. 2. A step of forming a laminate having a masking effect and a transparent electrode on a transparent substrate, a step of forming a positive photosensitive organic resin film on these, and irradiating light from the back side of the substrate, A method for manufacturing a liquid crystal display device, characterized in that the remaining organic resin film is formed as a spacer by selectively forming the organic resin film into a predetermined shape using the laminate having a masking effect as a mask. 3. The method of manufacturing a liquid crystal display device according to claim 1 or 2, wherein the film having a masking effect is an active element connected to each pixel of a liquid crystal display panel using an active matrix method.