JPH0581829U - Liquid crystal display element - Google Patents

Abstract

(57) [Abstract] [Purpose] Deformation on both the inside and outside of the substrate is reliably regulated, and the substrate gap is kept constant regardless of the ambient temperature or the volume change of the liquid crystal layer due to the application of a driving electric field. (EN) Provided is a liquid crystal display device which can always obtain a high quality display. [Structure] Film-like spacers 9 made of a high-melting resin are formed on one substrate 1 in a scattered manner, and an adhesive layer 10 made of a low-melting resin is formed between the film-like spacers 9 and the other substrate 2. Glued through.

Description

[Detailed description of the device]

[0001]

[Industrial applications]

 The present invention relates to a liquid crystal display device.

[0002]

[Prior Art]

 The liquid crystal display element is configured by enclosing a liquid crystal between a pair of transparent substrates on which a display electrode and an alignment film are formed.

In this liquid crystal display element, in order to make the alignment state of the liquid crystal uniform, it is desired to make the gap (cell gap) between both substrates uniform. Therefore, in the above liquid crystal display element, A large number of spacers are scattered between a pair of substrates, and the spacers regulate the gap between the substrates.

Conventionally, as the spacers, spherical solid particles made of glass or transparent resin, or those obtained by coating the surfaces of the solid particles with an adhesive made of a thermoplastic resin are used. During assembly of the liquid crystal display element, it is dispersed on one of the substrates and sandwiched between a pair of substrates that are adhered via a frame-shaped sealing material that surrounds the liquid crystal enclosed area to control the gap between the two substrates. There is.

[0005]

[Problems to be solved by the device]

 However, in the liquid crystal display device using the above solid particles as spacers, the spacers that control the substrate gap are only sandwiched between the pair of substrates, so that the concave deformation inside the substrates can be regulated by the spacers. However, there is a problem that the bulging deformation of the substrate cannot be regulated.

This can be said also in a liquid crystal display element using a spacer in which the surface of solid particles is coated with an adhesive. In this liquid crystal display element, the spacer and the pair of substrates are bonded by the adhesive on the spacer surface. However, since the spacer is only bonded to the substrate at one point on its surface (spherical surface), the bond strength between the substrate and the spacer is weak, and therefore the liquid crystal layer is affected by the ambient temperature and the application of a driving electric field. When the volume of the liquid crystal expands, the adhesive portion between the substrate and the spacer cannot withstand the expansion force of the liquid crystal and peels off, causing the substrate to expand outward and deform.

Therefore, the conventional liquid crystal display element has a problem that the expansion of the volume of the liquid crystal layer increases the gap between the substrates to change the alignment state of the liquid crystal. This is especially a problem in a liquid crystal display device using a ferroelectric liquid crystal or an antiferroelectric liquid crystal, and in a ferroelectric or antiferroelectric liquid crystal display device, the substrate gap, that is, the layer thickness of the liquid crystal layer is Since the alignment state of the liquid crystal is greatly affected, the display quality is significantly deteriorated due to the change in the substrate gap.

The purpose of the present invention is to reliably regulate the deformation of the substrate inside or outside, and keep the substrate gap constant regardless of the ambient temperature or the volume change of the liquid crystal layer due to the application of the driving electric field. Another object of the present invention is to provide a liquid crystal display device that can always obtain a high quality display.

[0009]

[Means for Solving the Problems]

 The liquid crystal display element of the present invention is formed by interspersing film spacers made of a high melting point resin on one of the substrates, and these film spacers and the other substrate are made of a low melting point resin. It is characterized by being bonded via an adhesive layer.

[0010]

[Action]

 That is, the liquid crystal display device of the present invention is formed by combining a pair of substrates by film-like spacers formed by interspersing them on one substrate and an adhesive layer for adhering these film-like spacers to the other substrate. As described above, when a high melting point resin is used for the film spacer and a low melting point resin is used for the adhesive layer, the film spacer and the other substrate are interposed via the adhesive layer. Since the film spacer does not soften and its thickness does not change during bonding, it is possible to bond a pair of substrates with a predetermined substrate gap.

The film-shaped spacer is in close contact with one of the substrates on which the spacer is formed in the same large area as the spacer area, and also in the other substrate with the same large area as the spacer area. Since they are bonded by the bonding area, the bonding strength of the pair of substrates bonded by the film spacer and the adhesive layer is sufficient.

Therefore, according to the liquid crystal display device of the present invention, the deformation of the inside or outside of the substrate can be surely regulated, so that the substrate gap is not affected by the ambient temperature or the volume change of the liquid crystal layer due to the application of the driving electric field. Can be kept constant to always obtain a high quality display.

[0013]

【Example】

 An embodiment of the present invention will be described below with reference to FIGS. FIG. 1 is a sectional view of a liquid crystal display element, and FIG. 2 is a plan view of a part of a liquid crystal display element.

In FIGS. 1 and 2, reference numerals 1 and 2 denote a pair of transparent substrates made of glass or the like, and a display electrode 3 made of a transparent conductive film such as ITO is provided on one surface of each of the substrates 1 and 2. , 4 are formed, and alignment films 5 and 6 for aligning liquid crystals are formed on the electrode formation surfaces of both substrates 1 and 2. The liquid crystal display element is of a simple matrix type, for example, the electrode 3 on one substrate 1 is a scanning electrode, and the electrode 4 on the other substrate 2 is a signal electrode orthogonal to the scanning electrode 3.

The pair of substrates 1 and 2 are adhered to each other with their electrode forming surfaces facing each other through a frame-shaped sealing material 7 made of a thermosetting resin. A liquid crystal 8 is enclosed in a region surrounded by the seal material 7.

Further, among the pair of substrates 1 and 2, on one substrate 1 (on the alignment film 5), a large number of film spacers 9 made of a high melting point resin are provided over the entire liquid crystal enclosing region. It is made to exist.

The film-like spacer 9 is, for example, a circular film as shown in FIG. 2, and its diameter is the same as that of each pixel portion formed by the intersecting facing portion of the scanning electrode 3 and the signal electrode 4. The diameter is about the same as or slightly smaller than the gap (about 10 μm) (about 6 to 10 μm), and the film thickness is slightly smaller than the substrate gap (liquid crystal layer thickness) of the liquid crystal display element. It is formed with a thin film thickness.

The film spacers 9 are formed between the pixel portions (between the scanning electrodes 3 and 3 and between the signal electrodes 4 and 4) while avoiding the pixel portions, and the pair of substrates 1 and 1. Reference numeral 2 denotes a predetermined substrate by adhering each film spacer 9 formed on one substrate 1 and the other substrate 2 surface (orientation film 6 surface) via an adhesive layer 10 made of a low melting point resin. It is connected with a plate gap. FIG. 3 is a sectional view in each manufacturing step showing the method for manufacturing the above-mentioned liquid crystal display element, and this liquid crystal display element is manufactured as follows.

First, as shown in FIG. 3A, the scanning electrode 3 is formed on one of the substrates 1 by a known method, and an alignment film 5 made of polyimide or the like is further formed on the scanning electrode 3 and then the scanning electrode 3 is formed. The photosensitive high melting point resin 9a is applied on the base plate 1 (on the alignment film 5) to a predetermined film thickness by a spin coating method or the like, and the applied film is dried. The melting point resin 10a is applied to a predetermined thickness by a spin coating method or the like, and the applied film is dried. The photosensitive high melting point resin 9a is applied to a thickness such that the film thickness after drying becomes the film thickness of the film spacer 9 (a film thickness slightly smaller than the substrate gap of the liquid crystal display element). The resin 10a is applied to a thickness such that the film thickness after drying is slightly larger than the difference between the film thickness of the film spacer 9 and the substrate gap of the liquid crystal display element.

Next, as shown in FIG. 3A, exposure is performed by forming a light-shielding film 13 having an opening at a portion corresponding to the formation region of the film spacer 9 on the surface of the transparent plate 12 made of glass or the like. The photosensitive low melting point resin 10a and the photosensitive high melting point resin 9a are irradiated with light A using a mask 11, and the exposed regions of these resins 10a and 9a are polymerized by photopolymerization. Part) is removed by a developing process.

FIG. 3B shows a state after the above-mentioned development processing is performed. The high melting point resin 9a left on the substrate 1 becomes the film spacer 9, and the low melting point resin 10a is the film space. The adhesive layer 10 serves to bond the server 9 and the other substrate 2 together. The rubbing treatment of the alignment film 5 on the substrate 1 is performed after the film spacer 9 and the adhesive layer 10 are formed.

Next, the melting point of the adhesive layer 10 is formed on either one of the substrate 1 and the other substrate 2 on which the signal electrode 4 and the alignment film 6 are formed and the alignment film 6 is rubbed. A thermosetting resin that cures at a lower temperature is printed by a screen printing method to form a sealing material 7 (see FIG. 1) that surrounds the liquid crystal enclosed area.

Next, as shown in FIG. 3C, the one substrate 1 and the other substrate 2 are overlapped with each other and higher than the melting point of the adhesive layer 10 and lower than the melting point of the film spacer 9. While heating to the temperature, the substrates 1 and 2 are pressed until the gap between them reaches a predetermined value.

In this case, if the substrates 1 and 2 are pressurized while being heated to the above temperature, the film spacer 9 having a melting point higher than the heating temperature does not soften, so that the film thickness of the film spacer 9 does not change. Since the adhesive layer 10 on the film spacer 9 is melted by heating and crushed by the pressing force, the gap between the substrates 1 and 2 can be set to a predetermined value. Further, the sealing material 7 begins to cure by heating to the above temperature, but since it takes time for the sealing material 7 to cure over its entire thickness, the sealing material 7 is also crushed by the applied pressure, and The thickness depends on the gap.

When the gap between the substrates 1 and 2 reaches a predetermined value, the heating temperature is lower than the melting point of the adhesive layer 10 and the curing temperature of the sealing material 7 while maintaining the applied pressure at this time. The adhesive layer 10 is re-cured by lowering it to a higher temperature, the film spacers 9 on one substrate 1 and the other substrate 2 are bonded to each other via the adhesive layer 10, and the seal material is also used. 7 is cured over its entire thickness, and both substrates 1 and 2 are adhered by this sealing material 7.

After that, a liquid crystal 8 is injected by a vacuum injection method between the substrates 1 and 2 from a liquid crystal injection port (not shown) provided in a part of the sealing material 7 when the sealing material 7 is formed, and then The liquid crystal display element is completed by sealing the liquid crystal injection port with an ultraviolet curable resin.

That is, in the liquid crystal display element, the film-like spacers 9 formed by interposing the pair of substrates 1 and 2 on one substrate 1 and the film-like spacers 9 and the other substrate 2 are provided. When the high-melting point resin is used for the film-shaped spacer 9 and the low-melting point resin is used for the adhesive layer 10, as described above, the high-melting-point resin 9 is bonded to the film-shaped spacer 9. When the other substrate 2 is adhered via the adhesive layer 10, the film spacer 9 does not soften and its thickness does not change. Can be combined.

The film-shaped spacer 9 is in close contact with one of the substrates 1 on which the spacer 9 is formed in the same large area as the spacer area, and the other substrate 2 also has the spacer area. Since they are bonded with the same large bonding area as described above, the bonding strength of the pair of substrates 1 and 2 bonded by the film spacer 9 and the adhesive layer 10 is sufficient.

Therefore, according to the liquid crystal display element, the deformation of the substrates 1 and 2 on either the inside or outside can be surely regulated, so that the volume change of the liquid crystal layer due to the ambient temperature or the application of the driving electric field can be prevented. Instead, the gap between the substrates 1 and 2 can be kept constant, and high-quality display can always be obtained.

Further, in the conventional liquid crystal display element, since the spacers are arranged by being scattered, the spacers are also present in the pixel portion, so that the alignment state of the liquid crystal in the pixel portion is disturbed around the spacer. Although the display quality is deteriorated, in the liquid crystal display element of the above-mentioned embodiment, since the film spacer 9 is formed between the pixel portions while avoiding the pixel portion, the alignment state of the liquid crystal in the pixel portion is changed. Since no disturbance occurs, the display quality can be improved as compared with the conventional liquid crystal display element. The present invention can be applied to a liquid crystal display device using a ferroelectric liquid crystal or an antiferroelectric liquid crystal, as well as a liquid crystal display device using a nematic liquid crystal or the like.

Further, in the above-mentioned embodiment, the rubbing treatment is applied to the alignment films 5 and 6 of the substrates 1 and 2, respectively. However, as the liquid crystal 8, a ferroelectric liquid crystal or an antiferroelectric liquid crystal is used. Alternatively, in the case of an anti-ferroelectric liquid crystal display element, the alignment film on either one of the substrates (for example, the substrate 1 on which the film spacer 9 is formed) may be a non-rubbed film, or one of the substrates may have an alignment film. An insulating film that covers the display electrode may be formed without forming the film.

[0032]

[Effect of the device]

 According to the liquid crystal display element of the present invention, film spacers made of a high melting point resin are formed on one substrate in a scattered manner, and these film spacers are bonded to the other substrate by a low melting point resin. Since it is adhered via the adhesive layer, it is possible to reliably control the deformation of the inside or outside of the substrate, and therefore, the gap between the substrates can be reduced regardless of the ambient temperature or the volume change of the liquid crystal layer due to the application of the driving electric field. Can be kept constant to always obtain high quality display.

[Brief description of drawings]

FIG. 1 is a sectional view of a liquid crystal display device showing an embodiment of the present invention.

FIG. 2 is a plan view of a part of the liquid crystal display element.

FIG. 3 is a sectional view in each manufacturing step showing the method of manufacturing the liquid crystal display element.

[Explanation of symbols]

1, 2 ... Substrate, 3, 4 ... Electrode, 5, 6 ... Alignment film, 7 ... Sealing material, 8 ... Liquid crystal, 9 ... Membrane spacer (high melting point resin),
10 ... Adhesive layer (low melting point resin).

Claims (1)

[Scope of utility model registration request] 1. In a liquid crystal display device in which liquid crystal is sealed between a pair of substrates, film spacers made of a high melting point resin are formed on one substrate in a scattered manner, and the film spacers and the other substrate are formed. And a liquid crystal display element, which are adhered to each other through an adhesive layer made of a low melting point resin.