JP3628941B2 - Liquid crystal element and electronic device - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a liquid crystal element using a flexible substrate such as a polymer film, and further relates to an electronic device equipped with the liquid crystal element.
[0002]
[Prior art]
In recent years, liquid crystal elements using a flexible substrate such as a polymer film (hereinafter referred to as PFP) are light, thin, and do not break, so that they are superior to liquid crystal elements using a glass substrate, such as pagers and mobile phones. It is attracting attention as a display element for portable information terminals, and demand is expanding. FIG. 7 shows an example of a cross-sectional view of the PFP. Reference numerals 1 and 2 are flexible substrates having a thickness of about 100 μm, and generally have a structure in which a gas barrier layer, a surface treatment layer, and the like are laminated based on PET, PC, PES or the like. A transparent electrode 3 such as indium tin oxide (ITO) is formed on the opposite surface. An alignment film 4 made of soluble polyimide or the like is formed on the transparent electrode 3, and the surface is subjected to an alignment process for aligning liquid crystals. The upper and lower substrates 1 and 2 are polymerized and bonded with a sealant 6 made of an epoxy adhesive or the like through a gap holding member 5, and a nematic liquid crystal 7 is enclosed to constitute a liquid crystal cell 8. The liquid crystal cell has a structure sandwiched between polarizing elements 9 and 10 which are bonded via 11 and 12 adhesive layers. The liquid crystal element may be of a reflective / semi-transmissive type in which a reflector or a semi-transmissive reflector is bonded to either outside of 9, 10 via an adhesive layer. The liquid crystal element may be an FTN type in which an optical compensator is bonded to at least one of 9 and 11 or 10 and 12 via an adhesive layer.
[0003]
[Problems to be solved by the invention]
However, PFP has not yet achieved a display quality equivalent to that of a glass cell due to restrictions on materials and the like.
[0004]
In the present invention, the problem of display unevenness and the deformation of the liquid crystal element, which is a factor that deteriorates the display quality, was analyzed from various angles, and the following facts were found.
[0005]
That is, display unevenness, which is a factor that deteriorates display quality, is caused by unevenness in the thickness of the liquid crystal cell, and is caused by low flatness of optical elements and reflectors attached to the liquid crystal cell. That is, in the case of PFP, unlike a liquid crystal cell using a glass substrate, it has flexibility, so that the liquid crystal cell is unevenly pressed by the unevenness of the applied substance, resulting in distortion of the substrate. Uneven display is accumulated in the liquid crystal cell. This problem is most problematic when the components are attached to the liquid crystal cell, and uneven stress due to adhesion is applied to the liquid crystal cell, and the substrate is distorted and accumulated in the liquid crystal cell.
[0006]
In addition, since the rigidity of a flexible substrate is lower than the rigidity of an optical element or the like, it is significantly distorted when pressed with an object having irregularities during bonding, and is distorted by being firmly fixed to a highly rigid body. Another problem is that it cannot be opened.
[0007]
In addition, the same problem is considered for the pressure-sensitive adhesive layer used for adhesion, and unevenness occurs on the contact surface with the liquid crystal cell if the flatness of the pressure-sensitive adhesive layer is low even when a polarizing element having high smoothness is used. At the time of bonding, the liquid crystal cell is non-uniformly pressurized and fixed to a highly rigid polarizing element or the like, so that distortion is accumulated and uneven display of the liquid crystal element occurs.
[0008]
On the other hand, the deformation is caused by the difference in deformation rate between the optical elements and the like attached to the liquid crystal cell and the liquid crystal cell, and particularly becomes a problem when external environmental factors (temperature, humidity, etc.) are changed.
[0009]
That is, when external environmental factors change, the liquid crystal cell and the material attached to the liquid crystal cell have a difference in expansion and contraction, which causes distortion and causes deformation of the liquid crystal element.
[0010]
Further, since the rigidity of the flexible substrate is lower than the rigidity of the components such as the polarizing element, the liquid crystal cell is deformed by strong stress when the polarizing element or the like is deformed. These phenomena become prominent when substances having remarkably different stretch rates such as reflectors are used. In addition, it is considered that the pressure-sensitive adhesive layer undergoes significant expansion and contraction due to changes in external environmental factors (temperature, humidity, etc.), thus causing distortion between the liquid crystal cell and the substance adhered to cause deformation of the liquid crystal element. This deformation in the liquid crystal element causes a significant deterioration in display quality, and when the amount of deformation is large, the liquid crystal element is destroyed. Therefore, in order to improve the display quality of the liquid crystal display element, it is important not to always cause deformation regardless of changes in external environmental factors (temperature, humidity, etc.).
[0011]
Accordingly, an object of the present invention is to provide a liquid crystal element excellent in reliability while ensuring uniformity of display.
[0012]
Another object of the present invention is to provide an electronic apparatus with improved reliability by mounting the liquid crystal element.
[0013]
[Means for Solving the Problems]
The liquid crystal element of the present invention includes a liquid crystal cell in which a transparent electrode is provided between a pair of flexible substrates and a liquid crystal layer is sandwiched between the pair of substrates. In a liquid crystal element in which a pair of optical elements are arranged,
On the surface of the optical element, a plurality of dot-like gap holding members having a predetermined height formed by printing and baking an adhesive in a dot shape are formed, and the plurality of dot-like gap holding members are formed. The optical element is arranged in the liquid crystal cell with the surface facing the liquid crystal cell, so that the liquid crystal cell and the optical element are held in the gaps of the predetermined height of the plurality of point-like gap holding members. It is characterized by being.
[0020]
As a result, in the conventional liquid crystal element, the cell thickness becomes non-uniform due to the distortion stress due to the uneven thickness of the optical element and the color unevenness occurs, but in the liquid crystal cell of this embodiment, the occurrence of the defect due to the significant color unevenness I was not able to admit. In addition, when a weather resistance test was performed at a high temperature, the conventional liquid crystal element was deformed and the deterioration of the element was observed, but the liquid crystal element of this example was not deformed and no deterioration was observed.
[0021]
[Example 2]
FIG. 2 is a cross-sectional view showing the configuration of the liquid crystal element, in which the liquid crystal cell 8 and the sealing agent 13 are formed by the same method as in the first embodiment. Then, after spraying Sekisui Fine Chemical Co., Ltd. micropearls having a particle diameter of 6 μm as the gap holding member 14, the polarizing elements 9 and 10 were fixed so as to hold a predetermined gap. In this example, Sekisui Fine Chemical Co., Ltd. micropearl was used as the gap retaining member, but the present invention is not limited to this, and can be applied to general granular materials such as inorganic compounds, organic compounds, or mixtures thereof. A liquid crystal cell or one that can be fixed on an optical element is preferable. Further, the particle diameter is not limited to 6 μm used in the present embodiment, and it is possible to carry out with an arbitrary value from 1 μm to 1 mm, but it is particularly preferable to be able to hold a gap of 1 μm to 10 μm. Also, the arrangement method of the gap holding member is not limited to the spraying method, and a printing method, a transfer method, or the like can be selected, and the arrangement location is not only on the liquid crystal cell but also on the optical element. Can do.
[0022]
As a result, in the conventional liquid crystal element, the cell thickness became non-uniform due to the distortion stress due to the uneven thickness of the optical element and the like, and the color unevenness defect occurred. I was not able to admit. In addition, when a weather resistance test was performed at a high temperature, the conventional liquid crystal element was deformed and the deterioration of the element was observed, but the liquid crystal element of this example was not deformed and no deterioration was observed.
[0023]
[Example 3]
FIG. 3 is a cross-sectional view showing the configuration of the liquid crystal element. The liquid crystal cell 8 and the sealing agent 13 are formed by the same method as in the first embodiment. Then, an epoxy adhesive is printed on the 9 and 10 polarizing elements in the form of dots at intervals of 5 mm and baked to form a gap holding member 15 having a height of 6 μm. The liquid crystal cell and the 9 and 10 polarizing elements were fixed so as to maintain a predetermined gap to obtain a liquid crystal element. In this embodiment, an epoxy adhesive or the like is used as the gap holding member, but the adhesive is not limited to an epoxy adhesive, for example, an adhesive such as phenol, vinyl or synthetic rubber, acrylic, polyester, etc. System, polythiol and epoxy photo-curing adhesives can be used, and inorganic materials such as SiOx can also be used. Further, the method for forming the columnar gap holding member is not limited to printing, and means such as a dispenser, a transfer method, a spray method, and a sputtering method can be selected, and the height is not limited to 6 μm used in this embodiment. Although it is possible to carry out with any value from 1 μm to 1 mm, it is particularly preferable to maintain a gap of 1 μm to 10 μm. In this embodiment, the gap holding member is formed on the optical element side, but the arrangement location can be arranged not only on the optical element but also on the liquid crystal cell.
[0024]
As a result, in the conventional liquid crystal element, the cell thickness became non-uniform due to the distortion stress due to the uneven thickness of the optical element and the like, and the color unevenness defect occurred. I was not able to admit. In addition, when a weather resistance test was performed at a high temperature, the conventional liquid crystal element was deformed and the deterioration of the element was observed, but the liquid crystal element of this example was not deformed and no deterioration was observed.
[0025]
[Example 4]
FIG. 4 is a cross-sectional view showing the configuration of the liquid crystal element, in which the liquid crystal cell 8 and the sealing agent 13 are formed by the same method as in the first embodiment. Silicon oil as filler 16 was sealed inside the sealing agent 13 with the polarizing elements 9 and 10 while taking care not to leave bubbles, and the gap between the liquid crystal cell and the polarizing element was 6 μm. In this embodiment, silicon oil is used as an example of a fluid liquid or a gel-like substance. However, the present invention is not limited to silicon oil, and can be applied to inorganic and organic flame retardant liquids such as distilled water and paraffin oil. It is possible. In addition, it is possible to use a substance that exhibits a gel state at room temperature, such as glycerin and petrolatum, and handling at the time of encapsulation is easier than liquid. In this embodiment, the filler is sealed so that the gap between the liquid crystal cell and the optical element is 6 μm. However, the gap is not limited to 6 μm, and can be implemented with any value from 1 μm to 1 mm. In particular, it is preferable to maintain a gap of 1 μm to 10 μm.
[0026]
As a result, in the conventional liquid crystal element, the cell thickness becomes non-uniform due to the distortion stress due to the uneven thickness of the optical element and the like, and the color unevenness defect occurs. I was not able to admit. In addition, when a weather resistance test was performed at a high temperature, the conventional liquid crystal element was deformed and the deterioration of the element was observed, but the liquid crystal element of this example was not deformed and no deterioration was observed.
[0027]
[Example 5]
FIG. 5 is a cross-sectional view showing the configuration of the liquid crystal element, in which the liquid crystal cell 8 and the sealing agent 13 are formed by the same method as in the first embodiment. A glass plate 17 was disposed below the liquid crystal cell, and the polarizing elements 9 and 10 were bonded via an adhesive layer to form a liquid crystal element so as to maintain a gap of 6 μm from the liquid crystal cell. In this embodiment, a glass plate is used. However, the glass plate is not limited to glass, and can be used for a substrate having higher rigidity than a liquid crystal cell. Is also applicable. Further, when a predetermined gap is maintained when using the casing of the liquid crystal device or the like, the sealing agent 13 can be omitted. In the present embodiment, the gap between the liquid crystal cell and the optical element is designed to be 6 μm, but the gap is not limited to 6 μm, and can be implemented with any value from 1 μm to 1 mm. In particular, it is preferable to maintain a gap of 1 μm to 10 μm.
[0028]
As a result, in the conventional liquid crystal element, the cell thickness becomes non-uniform due to the distortion stress due to the uneven thickness of the optical element and the like, and the color unevenness defect occurs. I was not able to admit. In addition, when a weather resistance test was performed at a high temperature, the conventional liquid crystal element was deformed and the deterioration of the element was observed, but the liquid crystal element of this example was not deformed and no deterioration was observed.
[0029]
[Example 6]
FIG. 6 is a cross-sectional view showing the configuration of the liquid crystal element, in which the liquid crystal cell 8 and the sealing agent 13 are formed by the same method as in the first embodiment. A glass plate 17 was disposed above the liquid crystal cell, and the polarizing elements 9 and 10 were bonded via an adhesive layer to form a liquid crystal element so as to maintain a gap of 6 μm from the liquid crystal cell. In this embodiment, a glass plate is used, but the glass plate is not limited to glass, and a transparent substrate of an inorganic substance typified by glass or the like or an organic substance typified by acrylic or the like can be used. The present invention can also be applied to a plate or a casing of a liquid crystal device. Further, if necessary, the appearance color can be easily changed by coloring the transparent substrate to such an extent that the visibility is not impaired. Further, when a predetermined gap is maintained when using the casing of the liquid crystal device or the like, the sealing agent 13 can be omitted. In the present embodiment, the gap between the liquid crystal cell and the optical element is designed to be 6 μm, but the gap is not limited to 6 μm, and can be implemented with any value from 1 μm to 1 mm. In particular, it is preferable to maintain a gap of 1 μm to 1 Oμm.
[0030]
As a result, in the conventional liquid crystal element, the cell thickness becomes non-uniform due to the distortion stress due to the uneven thickness of the optical element and the like, and the color unevenness defect occurs. I was not able to admit. In addition, when a weather resistance test was performed at a high temperature, the conventional liquid crystal element was deformed and the deterioration of the element was observed, but the liquid crystal element of this example was not deformed and no deterioration was observed.
[0031]
[Example 7]
When the liquid crystal element was mounted as a display device for a pager, a pager that was thinner and lighter than a liquid crystal element formed of a glass substrate and was excellent in impact resistance was obtained. That is, even if it is accidentally dropped, it does not break like a glass cell. Therefore, there is no display defect due to breakage, which has been a problem in the past. Further, even when used in a high temperature environment, the margin of the deformation of the liquid crystal element, which is a problem peculiar to PFP, is increased as compared with the conventional product, and a pager with excellent reliability and display quality can be provided.
[0032]
In this embodiment, a pager has been described as an example. However, the present invention is not limited to this embodiment, and an excellent electronic apparatus can be provided by being mounted on an electronic apparatus as a display device such as a personal digital assistant (PDA) or a personal computer.
[0033]
【The invention's effect】
The liquid crystal element of the present invention has a structure that does not transmit unevenness to the liquid crystal cell, such as a liquid crystal element component such as a polarizing element, an optical compensator, a reflector, and a semi-transparent reflector, while significantly improving display quality. Even when external environmental factors (temperature, humidity, etc.) change, the distortion stress caused by the liquid crystal element components etc. is not transmitted to the liquid crystal cell, so the liquid crystal element does not deform, high image quality, high quality, A highly durable liquid crystal element can be provided. In addition, since the adhesive layer is not used, there is an effect that the adhesive layer is not deformed or deteriorated and can be highly durable. Furthermore, the liquid crystal element of the present invention using a protector for protecting the liquid crystal element can suppress the adhesion of dust etc. to the liquid crystal element and the generation of scratches on the display surface, etc. A highly durable liquid crystal element can be provided.
[0034]
The electronic apparatus according to the present invention has excellent characteristics such as excellent reliability and display characteristics, and being thin and lightweight by mounting the liquid crystal element.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view of a liquid crystal element of the present invention.
2 is a cross-sectional view of a liquid crystal element of Example 2. FIG.
3 is a cross-sectional view of a liquid crystal element of Example 3. FIG.
4 is a cross-sectional view of a liquid crystal element of Example 4. FIG.
5 is a cross-sectional view of a liquid crystal element of Example 5. FIG.
6 is a cross-sectional view of a liquid crystal element of Example 6. FIG.
FIG. 7 is a cross-sectional view of a conventional liquid crystal element.
[Explanation of symbols]
1. Substrate 2. Substrate 3. Transparent electrode4. 4. Alignment film 5. Gap holding member 6. Sealing material Liquid crystal 8. Liquid crystal cell 9. Polarizing element 10. Polarizing element 11. Adhesive layer 12. Adhesive layer 13. Sealant 14. Granular gap retaining member 15. Columnar gap retaining member 16. Filler 17. Glass

Claims (1)

A transparent electrode is provided between a pair of flexible substrates, and a liquid crystal cell is configured in which a liquid crystal layer is sandwiched between the pair of substrates, and at least a pair of optical elements are disposed outside the liquid crystal cell. In the liquid crystal element
On the surface of the optical element, a plurality of dot-like gap holding members having a predetermined height formed by printing and baking an adhesive in a dot shape are formed, and the plurality of dot-like gap holding members are formed. The optical element is arranged in the liquid crystal cell with the surface facing the liquid crystal cell, so that the liquid crystal cell and the optical element are held in the gaps of the predetermined height of the plurality of point-like gap holding members. A liquid crystal element characterized by being made.

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