JP3080300B2 - Liquid crystal element - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a liquid crystal device using a liquid crystal having bistability, such as a chiral smectic liquid crystal or a chiral nematic liquid crystal.

[0002]

2. Description of the Related Art Heretofore, a liquid crystal element of a type that controls transmitted light in combination with a polarizing element by utilizing the bending anisotropy of liquid crystal molecules has been proposed by Clark and Lagerwall-. U.S. Pat. No. 4,367,924). Here, the liquid crystal used in this liquid crystal element generally has a chiral smectic C phase (Sm ^* C) or an H phase (Sm ^* ) in a specific temperature range ^.
H), in this state, it takes either the first optically stable state or the second optically stable state in response to an applied electric field, and maintains that state when no electric field is applied. Bistable liquid crystals, such as chiral smectic liquid crystals and chiral nematic liquid crystals, which have a property of being stable, that is, have a quick response to a change in electric field. Therefore, this liquid crystal element is expected to be widely used as a high-speed and storage type display element.

In such a liquid crystal element, for example, a chiral smectic liquid crystal is held between a matrix electrode composed of a scanning electrode and a signal electrode, while a scanning signal is sequentially applied to the scanning electrode and synchronized with the scanning signal. Then, the alignment state of the liquid crystal in the pixel area is changed by multiplexing driving for applying an information signal to the signal electrode, that is, the liquid crystal is turned ON / OFF.

[0004]

However, in a conventional liquid crystal element which drives liquid crystal by such a driving method, the alignment state of the liquid crystal in a region outside the pixel region which is turned ON / OFF when driving the liquid crystal is, for example, as shown in FIG. As shown in (1), a white or black non-uniform state may be exhibited due to the influence of the molecular arrangement in the pixels 20a and 20b.

In FIG. 1, reference numeral 20a denotes a white writing pixel, and 20b denotes a black writing pixel.
Reference numeral 21b indicates a white domain and a black domain generated in the region 20c outside the pixel region due to the influence of the molecular arrangement in the two pixels 20a and 20b. Then, as described above, the domains 21a and 21b are located in the region 20c outside the pixel region.
There is a problem in that when images are mixed, the whole screen is rough and the image quality is low.

This is because the alignment state (mainly pretilt) in the pixels 20a and 20b and the area 20c outside the pixel area are different.
It is difficult to make a large difference with the orientation state in
Similarly to the orientation in the pixels 20a and 20b, the orientation of the region 20c outside the pixel region also exhibits a bistable state, which results in a partially non-uniform region, thereby making the entire display rough. Image quality. Here, this phenomenon similarly occurs when multiplex driving of a chiral nematic liquid crystal exhibiting bistability is performed.

On the other hand, a light-shielding layer is conventionally provided in the area 20c other than the pixel area in order to suppress such roughness on the display. However, when a metal film is used as the light-shielding layer, film formation / photolithography is required. As a result, the number of man-hours required increases the cost. It is well known that impact resistance is a weak point in reliability of a liquid crystal element using a bistable liquid crystal. This is a factor of cost increase.

Accordingly, an object of the present invention is to provide an inexpensive liquid crystal device having high display quality in view of the conventional problems.

[0009]

SUMMARY OF THE INVENTION According to the present invention, a liquid crystal is sandwiched between a pair of substrates, an electrode group for generating an electric field for driving the liquid crystal is provided on the substrate, and a desired liquid crystal arrangement is obtained. In a liquid crystal element in which an alignment film provided with uniaxial alignment by rubbing treatment is formed in a region other than a pixel region in which the liquid crystal changes an alignment state by an electric field generated in the electrode group between the pair of substrates. A three-dimensional structure formed of a resin film having a light-shielding property and an adhesive ability to adhere the pair of substrates, and having a three-dimensional structure in which fine irregularities are formed on an adhesive surface; Are characterized by different alignment states.

The present invention is characterized in that the three-dimensional structure is provided at a position corresponding to a region outside a pixel region of at least one of the substrates.

[0011]

[0012]

[0013]

Further, the present invention is characterized in that the occupied area of the three-dimensional structure is not less than 4% and not more than 90% of the area of the region outside the pixel region.

[0015]

Further, by turning on / off the liquid crystal in the pixel region by an electric field generated by an electrode group provided on the substrate holding the liquid crystal as in the present invention, by providing a three-dimensional structure in a region other than the pixel region, The alignment state of the liquid crystal in the pixel region and the region outside the pixel region are made different so as to prevent the liquid crystal molecular arrangement between the pixels from being changed by the driving of the liquid crystal in the neighboring pixels.

[0017]

A resin having a three-dimensional structure provided at a position corresponding to a region outside the pixel region of the substrate, having a light-shielding property and an adhesive ability for bonding a pair of substrates, and having fine irregularities formed on the bonding surface. By forming the film, a change in the alignment of liquid crystal molecules is prevented, and the impact resistance is improved.

[0019]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a sectional view showing a schematic structure of a liquid crystal element according to a first reference example on which the present invention is based. In the figure, 1 is a liquid crystal element, 2a and 2b are a pair of glass substrates (hereinafter referred to as substrates) sandwiching a bistable liquid crystal, for example, a chiral smectic liquid crystal (hereinafter referred to as liquid crystal) 3, and 4 is formed on one substrate 2a. Color filter, 5 is liquid crystal 3
Is a transparent electrode for generating an electric field for driving the substrate, and 6 is an alignment film that initially provides vertical alignment. The transparent electrodes 5 on the substrates 2a and 2b are formed in a matrix so as to drive the liquid crystal 3 in a multiplexing manner.

Reference numeral 7 denotes a fine pattern having a three-dimensional structure provided in a region (hereinafter, referred to as a non-pixel region) 8a other than the pixel region of the color filter 4, and the liquid crystal 3 in the non-pixel region 8a is formed by the fine pattern 7. An alignment state different from that of the pixel region 8b, for example, an asymmetric alignment state or a vertical alignment between the opposing substrates 2a and 2b is performed so as to be monostable. In this embodiment, the fine pattern 7
Are formed simultaneously with the color filter 4 using the same material as the color filter 4, thereby reducing the number of steps and the number of materials.

Since the orientation of the liquid crystal 3 is fixed by the mono-stabilization in the extra-pixel region 8a by the fine pattern 7, the driving of the liquid crystal 3 in the neighboring pixel region 8b causes the extra-pixel region 8a to be fixed. Fluctuations in the liquid crystal molecule arrangement are prevented, whereby uniform, high-quality image display without roughness can be performed.

By the way, as the fine pattern 7,
For example, as shown in FIG. 2 (a), a plurality of prismatic three-dimensional structures 71 having an area of 3 μm ² , and as shown in FIG. 2 (b), a plurality of columnar three-dimensional structures having a diameter of 3 μm. Arbitrary patterns such as those composed of the structure 72 and those composed of the striped three-dimensional structure (not shown) can be used. Here, the occupied area of the line portion or the pillar portion of the pattern is determined in consideration of the patterning accuracy, the size of the parallel alignment domain that can be opposed to the surrounding vertical alignment, and the like.
It is preferable to set the area to 4% or more and 50% or less of the entire area outside the pixel region. Note that FIG. 2A shows a case of 25%, and FIG. 2B shows a case of 39%.

Next, a method of manufacturing a liquid crystal device having such a configuration will be described.

First, one substrate 2a is spinner-coated with a product made by Tokyo Ohka Kogyo Co., Ltd. (trade name: CFPR series).
Pre-baking at 0 ° C. for 2 minutes, exposure at 200 mj, shower development with an alkaline developer for 40 seconds, and post-baking at 250 ° C. for 5 minutes to give a 1.5 μm thick color filter 4
And a fine pattern 7 is formed.

Next, after laminating the transparent electrode 5 on the color filter 4 and the fine pattern 7, a Hitachi Chemical (trade name: LQ1800) is applied and baked at 270 ° C. for 10 minutes. A film 6 is formed. After this,
A rubbing process is performed on the alignment film 6 with a strength to obtain a uniaxial orientation and a pretilt of about 20 °.

Next, the substrate 2a and a counter substrate 2b formed in the same manner as described above except for the formation of the color filter 4 and the rubbing direction giving a cross angle of -8 ° are interposed via a spacer (not shown). The liquid crystal 3 is injected between the substrates 2a and 2b, and the liquid crystal element 1 is manufactured.

By the way, in the liquid crystal element 1 manufactured as described above, the uniform alignment having a desired pretilt is realized in the pixel region 8b, and the vertical alignment and the horizontal alignment are hybridized in the out-of-pixel region 8a. In the region 8a, the liquid crystal alignment was fixed, and a high-quality image display without roughness was obtained.

Next, a liquid crystal device according to a second reference example on which the present invention is based will be described.

As shown in FIG. 3, the liquid crystal element of this embodiment has a color filter 4 and a fine pattern 7 formed on one substrate 2a and on the other substrate 2b. In addition,
The thickness of the color filter 4 is 0.75 μm, and the color filter 4 is formed at a position facing each other so that the same color is overlapped on both substrates 2a and 2b.

By the way, in such a liquid crystal element 1 ', after forming the color filter 4 and the fine pattern 7 on the respective substrates 2a and 2b, the same electrode / alignment film forming / forming as in the first embodiment described above is performed. It is manufactured by performing a rubbing process and a cell forming process.

Here, in the liquid crystal element 1 'manufactured in this manner, uniform alignment having a desired pretilt is realized in the pixel region 8b, while vertical alignment is achieved in the out-of-pixel region 8a, and high quality without roughness is achieved. An image display was obtained. Further, in the liquid crystal element 1 'having this configuration, effects such as improvement of the durability of the drive margin with time and suppression of the cell gap change due to the movement of the liquid crystal were obtained.

Next, a liquid crystal device according to a third reference example on which the present invention is based will be described with reference to FIG.

The liquid crystal element of this embodiment uses a chiral nematic liquid crystal as the liquid crystal 3 and is manufactured as follows.

First, two substrates 2a and 2b are formed in the same manner as in the first embodiment up to the color filter 4, the fine pattern 7, and the transparent electrode 5 in the extra-pixel region 8a. Next, a polyimide alignment film (SE-314 manufactured by Nissan Chemical Industries, Ltd.)
0) After forming 6, rubbing treatment is performed. Next, the substrates 2a and 2b are bonded together via spacer beads such that the rubbing directions are antiparallel and the distance between the rubbings is 2.0 μm.

Finally, a nematic liquid crystal composition (KN-40 manufactured by Chisso Corporation) is provided in the gap between the substrates 2a and 2b.
2. Helical H pitch obtained by adding an optically active agent to 0)
The chiral nematic liquid crystal 3 of 4 μm is injected to manufacture the liquid crystal element 1.

Here, when the liquid crystal element 1 was multiplex-driven, the liquid crystal orientation in the extra-pixel region 8a was fixed, and almost no roughness was observed.

Next, a first embodiment of the present invention will be described.

FIG. 4 is a sectional view showing a schematic structure of the liquid crystal element according to the present embodiment. In FIG. 1, reference numeral 1A denotes a liquid crystal element, 2a and 2b denote a pair of glass substrates (hereinafter referred to as substrates) sandwiching a liquid crystal 3, 4 denotes a color filter formed on one substrate 2a, 5 denotes an electrode pattern, and 6 denotes an initial pattern. This is an alignment film that gives vertical alignment to.

A light-shielding layer (resin film) 9 made of a resin having a light-shielding property and an adhesive property is provided on the extra-pixel region 8a.
On the bonding surface of the light shielding layer 9, an uneven portion 10 having fine unevenness is formed as shown in FIG. Here, the uneven portion 10 serves as a barrier to the rubbing process to reduce the effect of the rubbing process.

By providing the light-shielding layer 9 having such uneven portions 10 in the out-of-pixel region 8a, the liquid crystal 3 in the out-of-pixel region 8a becomes an asymmetric or vertical alignment between the opposing substrates 2a and 2b. And become monostable,
The driving of the liquid crystal 3 in the neighboring pixels 8b can prevent the liquid crystal molecule arrangement in the non-pixel region 8a from being changed.

By forming the light-shielding layer 9 from a resin, the cost can be reduced as compared with a metal film. Further, since the shock resistance is improved, the liquid crystal 3 can be injected while having the shock resistance. The occupied area of the concavo-convex portion 10 is, as described above, 4% or more of the area of the non-pixel region 8a in consideration of the patterning accuracy, the size of the parallel alignment domain that can be opposed to the surrounding vertical alignment, and the like.
% Is preferable. In this embodiment, the occupied area is 39% by a photomask shown in FIG. 6 described later.

Next, a method of manufacturing the liquid crystal element 1A having such a configuration will be described.

First, one substrate 2a is spinner-coated with a product made by Tokyo Ohka Kogyo Co., Ltd. (trade name: CFPR series).
After prebaking at 0 ° C. for 2 minutes, 200 mj of light, shower development with an alkali developing solution for 40 seconds, and postbaking at 250 ° C. for 5 minutes, a color filter 4 having a thickness of 1.5 μm is formed.

Next, after forming color filters 4 of three colors in the same manner, manufactured by Tokyo Ohka Kogyo (trade name: TP-AR)
A pre-bake is performed after applying an acrylic coating carbon dispersed in a photosensitive adhesive resin. After this,
As shown in FIG. 6, the back surface is exposed using a photomask 10 in which a plurality of circular openings 10a having a diameter of 3 μm are formed. Form. The thickness of the projections of the uneven portion 10 is finally set to 2.1 μm.

Further, after forming the transparent electrode 5, Hitachi Chemical (trade name: LQ1800) is applied as an alignment film 6,
After baking at 0 ° C. for 10 minutes, a film thickness of 200 ° was obtained. A rubbing treatment is performed on the resultant structure so as to obtain uniaxial orientation and a pretilt of about 20 °.

Thereafter, the substrate 2a and the opposing substrate 2b formed in the same manner as described above except for the rubbing direction for forming a color filter and providing a cross angle of -8 ° are bonded via a spacer. The pressure-curing condition of the sealing material is 1 kg / cm ² and 160 ° C. for 30 minutes. And
Finally, the liquid crystal 3 is injected between the substrates 2a and 2b to manufacture the liquid crystal element 1A.

By the way, in the liquid crystal element 1A thus prepared, uniform alignment having a desired pretilt is realized in the pixel region 8b, and hybrid alignment of vertical alignment and horizontal alignment is realized in the non-pixel region 8a. The liquid crystal orientation in the region 8a was fixed, and a high-quality image display without roughness was obtained.

Next, a liquid crystal device according to a second embodiment of the present invention will be described.

As shown in FIG. 7, the liquid crystal element 1A 'of this embodiment has a light-shielding layer 9 and a color filter 4 formed on one substrate 2a and on the other substrate 2b. Here, the liquid crystal element 1A 'forms the color filter 4 in the same manner as in the first embodiment, but has a thickness of 0.75 μm.
m, and are formed at positions facing each of the substrates 2a and 2b so that the same color overlaps.

On the other hand, the light-shielding layer 9 is similarly
The light shielding layer 9 is formed at the position opposite to the pixels a and 2b so that the respective light shielding layers 9 are adhered to each other in the pixel outside region 8a as shown in FIG. The thickness of the projection of the light shielding layer 9 is 1.35 μm.

The liquid crystal element 1A 'is manufactured by the same electrode, alignment film forming, rubbing, and cell forming steps as in the first embodiment. As a result, a uniform alignment having a desired pretilt is realized in the pixel region 8b, and a high-quality image display with high contrast and high contrast is obtained in the non-pixel region 8a by the effect of the vertical alignment with the light shielding film 9. In addition, the effects of improving the durability over time of the drive margin while maintaining the intended impact resistance and suppressing the change in the cell gap due to the movement of the liquid crystal 3 were also obtained.

Finally, the driving configuration of the liquid crystal element in the information transmission device having such a liquid crystal element 1 will be described with reference to FIG.
This will be briefly described with reference to FIG.

In an information transmission device such as a printer or a color display provided with the liquid crystal element 1 according to the present invention,
As shown in FIG.
2 and the information signal applying circuit 403 are connected to each other.
3, a drive control circuit 404 and a graphic controller 405 are connected in order. Then, the data and the scanning method signal are sent from the graphic controller 405,
The data is transmitted to the scanning signal control circuit 406 and the information signal control circuit 407 via the drive control circuit 404.

The data among them is converted into scanning line address data and display data by the scanning signal control circuit 406 and the information signal control circuit 407, and the other scanning method signal is directly used by the scanning signal applying circuit 402 and the information signal. The signal is sent to the signal application circuit 403.

Further, the scanning signal applying circuit 402 applies a scanning signal having a waveform determined by the scanning method signal to the scanning electrode determined by the scanning line address data, and the information signal applying circuit 403 outputs white or black sent by the display data. And an information signal having a waveform determined by the two display contents and the scanning method signal.

[0057]

As described above, according to the present invention, by providing a three-dimensional structure outside the pixel region to mono-stabilize the alignment state outside the pixel region, it is possible to suppress display roughness and to improve display quality. Can be increased. In addition, when vertical alignment is performed outside the pixel region, effects such as improvement of durability over time of a drive margin and suppression of cell gap change due to movement of liquid crystal can be obtained, thereby improving quality and reliability of a liquid crystal element. It can greatly contribute.

Further, by providing a light-shielding layer as a three-dimensional structure outside the pixel area to shield the light while stabilizing the alignment state outside the pixel area, it is possible to improve the contrast while suppressing the roughness of the display and to improve the contrast. Is formed of a resin having an adhesive ability, an inexpensive liquid crystal element can be provided.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating a schematic configuration of a liquid crystal element according to a first reference example on which the present invention is based.

FIG. 2 is a diagram showing an example of a fine pattern provided outside a pixel region of the liquid crystal element.

FIG. 3 is a cross-sectional view illustrating a schematic configuration of a liquid crystal element according to a second reference example on which the present invention is based.

FIG. 4 is a sectional view showing a schematic configuration of a liquid crystal element according to the first embodiment of the present invention.

FIG. 5 is a schematic cross-sectional view of an adhesive light-shielding layer provided outside a pixel region of the liquid crystal element.

FIG. 6 is a view showing a photomask pattern for forming a fine pattern of the adhesive light shielding layer.

FIG. 7 is an essential part cross-sectional view showing a schematic configuration of a liquid crystal element according to a second embodiment of the present invention.

FIG. 8 is a diagram illustrating a driving configuration of a liquid crystal element in an information transmission device including the liquid crystal element.

FIG. 9 is a schematic diagram showing a state where black and white domains are mixed in a conventional liquid crystal element.

[Explanation of symbols]

 1, 1a, 1A, 1A 'Liquid crystal element 2a, 2b Glass substrate 3 Liquid crystal 4 Color filter 7 Fine pattern 71, 72 Three-dimensional structure 8a Non-pixel region 8b Pixel region 9 Light shielding layer 10 Uneven portion

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-3-192329 (JP, A) JP-A-4-225325 (JP, A) JP-A-58-172622 (JP, A) JP-A-7- 318950 (JP, A) JP-A-4-93942 (JP, A) JP-A-6-331970 (JP, A) (58) Fields investigated (Int. Cl. ⁷ , DB name) G02F 1 / 1337-1 / 1339 500

Claims (3)

(57) [Claims] A liquid crystal is sandwiched between a pair of substrates,
A liquid crystal element in which an electrode group for generating an electric field for driving the liquid crystal and an alignment film provided with uniaxial alignment by a rubbing process to obtain a desired liquid crystal alignment is formed on the substrate. In a region other than a pixel region in which the liquid crystal changes its alignment state by an electric field generated by the electrode group between the substrates , the light shielding property and the bonding ability for bonding the pair of substrates are improved.
It is formed by a resin film that has
A liquid crystal element having a three-dimensional structure in which unevenness is formed , wherein the liquid crystal has different alignment states in the pixel region and a region outside the pixel region. 2. The liquid crystal device according to claim 1, wherein the three-dimensional structure is provided at a position corresponding to a region outside a pixel region of at least one of the substrates. Footprint of claim 3 wherein said three-dimensional structure, the liquid crystal device according to claim 1 or 2, wherein the 90% or less than 4% of the area of the pixel region outside the region.