JP5236529B2 - ELECTRO-OPTICAL ELEMENT AND DISPLAY DEVICE - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an electro-optical element which allows high-speed response and has high luminance and high contrast characteristics. <P>SOLUTION: The elector-optical element includes: a plurality of substrates opposed to each other; a medium layer sandwiched between the plurality of substrates; electrode groups formed on the opposed surfaces of the substrates to apply an electric field to the medium layer; and a pair of polarizing plates arranged so that absorption axes may be approximately orthogonal to each other through the medium layer. Wherein, the electrode groups have interdigital portions which are arranged approximately in parallel, the medium layer includes a medium having substantially optical anisotropy with absence of an electric field and generating the optical anisotropy with application of an electric field, the electrode groups include transparent electrodes, and the optical anisotropy is applied to areas of respective electrodes in a direction normal to the substrates by combining the plurality of electrode groups. <P>COPYRIGHT: (C)2010,JPO&amp;INPIT

Description

  The present invention relates to an electro-optical element such as a liquid crystal element and a display device that control high-speed response to an applied voltage and transmission blocking of light having high light transmittance.

  Liquid crystal display elements are widely used in display units of various electronic devices such as liquid crystal televisions, personal computer monitors, mobile phones, and digital cameras, and have features such as thinness, light weight, and low power consumption.

  There are many display methods for this liquid crystal display element, but an IPS (In Plane Switching) method is known as a typical liquid crystal display method capable of achieving a wide viewing angle. In this IPS liquid crystal display element, a liquid crystal having a nematic phase is usually used, and an effective electric axis is rotated in the plane by applying an electric field to liquid crystal molecules held in a pair of substrates to rotate the alignment direction. Thus, the light transmittance of the liquid crystal is controlled to perform display.

  Various methods have been proposed for applying an electric field in the IPS method. The most common method is a method in which a comb-like pixel electrode and a common electrode are formed on the same substrate. Electric field application using a comb-teeth electrode consists of a method in which both the pixel electrode and the common electrode are in a comb-teeth shape, one of the pixel electrode and the common electrode is in a comb-teeth shape, the other electrode is in a flat plate shape, and an insulating layer There is a method of arranging through the.

  On the other hand, in contrast to the IPS liquid crystal display method, a liquid crystal display method using a substance that changes from optical isotropy to optical anisotropy by applying an electric field has been recently proposed (see, for example, Patent Document 1). In these liquid crystal display methods, a liquid crystal material having a blue phase or a liquid crystal material having cubic symmetry is used (for example, refer to Non-Patent Document 1). A parallel electric field is applied. These liquid crystal display elements can achieve response characteristics of several microseconds to several tens of microseconds, much faster than the conventional IPS method using nematic liquid crystal, and display quality when displaying moving image is greatly improved. It is expected to improve. In addition, an electrode structure in which the electrode spacing of the comb-like electrodes is smaller than the upper and lower substrate spacing (see, for example, Patent Document 2) has a weak electric field parallel to the substrate surface on the electrode, and this is applied to an optically anisotropic material. Even so, optical anisotropy cannot be imparted to the medium on the electrode.

  Patent Document 1, Patent Document 2, and Non-Patent Document 1 related to the invention of this application, and prior art documents listed in Examples described later are as follows.

Japanese Patent No. 3504159 JP 2007-086205 A JP 05-336477 A JP 2006-003840 A

Yoshiaki Hisakado etc. “Large Electro-optic Kerr Effect in Polymer-Stabilized Liquid-Crystalline Blue Phases”, Advanced Materials, Vol. 17, No. 1, 96 (2005) Hiroki Kikuchi, Advanced Materials, 17, 96-98, 2005 Hideo Takezoe et al., Journal of Japan Society of Applied Physics, 45, L282-284, 2006

  However, for example, in a liquid crystal display element that is driven by a comb-like electrode using blue phase liquid crystal as a liquid crystal material, light is not transmitted to the electrode portion even if a transparent electrode is used. This is due to the fact that the electric field strength is usually weak on the electrode and no optical anisotropy is imparted. Another reason is that there are few electric field components parallel to the substrate surface and many electric field components perpendicular to the substrate surface on the electrode.

  In the liquid crystal display element using the blue phase liquid crystal, the polarization axes of the upper and lower polarizing plates are arranged at an angle of about 45 degrees with respect to the longitudinal direction of the comb-like electrodes arranged in parallel to each other. Since the optical anisotropy is applied in the direction of the electric field, between the electrodes to which the electric field is applied substantially parallel to the substrate surface, the optical anisotropy is applied in the direction of 45 degrees from the polarization axis of the polarizing plate, and light is transmitted. To Penetrate. However, just above the electrode, the electric field strength is weak and the electric field component in the direction perpendicular to the substrate is large, so that the applied optical anisotropy is small and the direction is perpendicular to the substrate, so that the incident optical axis is rotated. Cannot transmit light.

  FIG. 18 is a schematic longitudinal sectional view showing an example of a sectional configuration of a conventional electro-optic element. FIG. 19 is a schematic plan view illustrating an example of a planar configuration when the electro-optical element illustrated in FIG. 18 is viewed from the direction of the arrow A. For example, as shown in FIGS. 18 and 19, a conventional electro-optic element encloses a medium layer 203 between a substrate 101 and a substrate 103, and forms an electrode 105 and an electrode 106 on the substrate 101. Further, deflecting plates 104 and 207 are attached to the outside of the substrate 101 and the substrate 103 so that the absorption axis is about 45 degrees with the electrode longitudinal direction. At this time, when an AC voltage is applied to the electrode 105 and the electrode 106 from an external power source (not shown), the correlation between the applied voltage and the transmittance is, for example, as shown by a curve in FIG. FIG. 20 is a schematic graph showing an example of the correlation between the applied voltage and the transmittance in the electro-optic element of the present invention and an example of the correlation between the applied voltage and the transmittance in the conventional electro-optic element. The conventional electro-optical element has a very low light transmittance and cannot be applied to an actual apparatus. As a result of observation with a microscope, no light was transmitted through the comb electrode in the conventional electro-optic element.

  Furthermore, the liquid crystal display element using blue phase liquid crystal, unlike the nematic phase liquid crystal, has a very short interaction length between liquid crystal molecules. You can't affect the top. For these reasons, no optical anisotropy is imparted to the portion immediately above the electrode, so that no light is transmitted. As a result, the transmittance corresponding to the electrode area is reduced. Therefore, it is necessary to increase the luminance of the backlight in order to obtain an appropriate luminance, and there is a problem that power consumption increases. When adopting a light anisotropic liquid crystal material for an applied electric field with high-speed response, it is an indispensable condition to increase the light transmittance of the liquid crystal in order to obtain a clear image.

  Further, in the liquid crystal display element using the blue phase liquid crystal and the comb-like electrode, the voltage giving the maximum transmittance is several V / μm, which is about 10 times or more the driving voltage of the IPS liquid crystal display element using the nematic liquid crystal. There is a problem that it is very expensive. Therefore, a low voltage drive switching element such as a thin film transistor cannot be applied.

  Further, as a result of evaluating the characteristics of the display device based on the configurations described in Patent Document 1, Patent Document 2, and Non-Patent Document 1, an electric force parallel to the substrate plane is obtained on the pixel electrode or the common electrode. Since no line is formed, the electrode hardly contributes to display.

  The present invention solves the above-described problems, and an object of the present invention is to achieve higher transmittance in an electro-optic element using a substance whose optical anisotropy changes by applying an electric field, represented by a blue phase liquid crystal. The object is to provide a technology capable of driving at a low voltage.

  Another object of the present invention is to provide a technique capable of improving the transmittance on an electrode in a display device having an electro-optic element using an isotropic liquid crystal and a comb-like electrode. It is in.

  The above and other objects and novel features of the present invention will be apparent from the description of this specification and the accompanying drawings.

  The outline of typical inventions among the inventions disclosed in the present application will be described as follows.

  (1) A plurality of opposing parallel substrates, a medium layer sandwiched between the plurality of substrates, and a pair of polarizing plates arranged so that absorption axes are substantially orthogonal to each other across the medium layer A plurality of electrode groups comprising a plurality of comb-like transparent electrodes provided on at least two surfaces of the plurality of substrates and arranged substantially parallel to each other, and transmitting and blocking light by an electric field applied to the electrode groups In the electro-optic element that controls the medium, the medium layer is made of a medium that has substantially optical isotropy when no electric field is applied and exhibits optical anisotropy when an electric field is applied. An electro-optic element that applies an electric field to the entire region including the region on the substrate normal line of the transparent electrode of the medium layer to provide optical anisotropy.

  (2) In the electro-optical element according to (1), the plurality of electrode groups apply an electric field at least in a direction parallel to the substrate to the medium layer.

  (3) The electro-optical element according to (2), wherein an electric field application region to the medium layer by one electrode group of the plurality of electrode groups includes a substrate normal direction region of another electrode group.

  (4) In the electro-optical element of (1), the absorption axis of the polarizing plate is disposed at an angle of 45 ° ± 10 ° with respect to the direction of electric field application to the medium layer as viewed from the normal direction of the substrate. The optical anisotropy direction imparted to the substrate normal direction region on the transparent electrode by the optical anisotropy imparting means is substantially parallel or substantially orthogonal to the electric field direction applied to the medium layer. element.

  (5) The electro-optical element according to (1), wherein the comb-tooth portions of the plurality of electrode groups are arranged so as not to overlap each other when viewed from the substrate normal direction.

  (6) In the electro-optic element of (1), the electric field components viewed from the substrate normal direction of each electric field applied to the medium layer by the plurality of electrode groups are substantially parallel to each other, and at the same time, the medium layer An electro-optic element to which an electric field is applied.

  (7) In the electro-optic element of (1), the first substrate and the second substrate facing each other, the first medium layer sandwiched between the pair of substrates, and the second substrate facing each other The third substrate, the second medium layer sandwiched between the second substrate and the third substrate, and the opposing surface side of the first substrate to the second substrate The second medium layer provided on the side of the first electrode group that applies an electric field to the first medium layer and the second substrate facing the third substrate. And a second electrode group for applying an electric field to the electro-optic element.

  (8) In the electro-optic element of (1), the first substrate and the second substrate facing each other, the first medium layer sandwiched between the pair of substrates, and the second substrate facing each other A third substrate, a second medium layer sandwiched between the second substrate and the third substrate, and a surface of the first substrate facing the second substrate. A first electrode group for applying an electric field to the first medium layer, and a second medium layer provided on a side of the third substrate facing the second substrate; An electro-optic element comprising a second electrode group for applying an electric field.

  (9) In the electro-optical element of (1), the first substrate and the second substrate facing each other, the first medium layer sandwiched between the pair of substrates, and the second substrate facing each other A third substrate, a second medium layer sandwiched between the second substrate and the third substrate, and a surface of the second substrate facing the first substrate. A first electrode group for applying an electric field to the first medium layer, and a second medium layer provided on a side of the second substrate facing the third substrate. An electro-optic element comprising a second electrode group for applying an electric field.

  (10) In the electro-optical element of (1), the first substrate and the second substrate facing each other, the medium layer sandwiched between the pair of substrates, and the second substrate of the first substrate A first electrode group for applying an electric field to the medium layer provided on a surface facing the substrate; and the medium layer provided on a surface facing the first substrate of the second substrate. And a second electrode group for applying an electric field to the electro-optic element.

  (11) In the electro-optic element according to (10), one electrode group provided on at least one of the first substrate and the second substrate includes an electrically independent common electrode and source. An electro-optic element having an electrode and the common electrode and the source electrode arranged symmetrically.

  (12) In the electro-optic element of (1), the first substrate and the second substrate facing each other, the medium layer sandwiched between the pair of substrates, and the second substrate of the first substrate An electrode group consisting of a common electrode provided on the surface facing the substrate, and an electrode group consisting of a source electrode provided on the surface facing the first substrate of the second substrate, An electro-optic element that applies a gradient electric field to the medium layer by both electrode groups.

  (13) In the electro-optic element of (12), the absorption axis of the polarizing plate is disposed at an angle of 45 ° ± 10 ° with respect to the direction of electric field application to the medium layer as viewed from the normal direction of the substrate. The optical anisotropy direction imparted to the substrate normal direction region on the transparent electrode by the optical anisotropy imparting means is substantially parallel or substantially orthogonal to the electric field direction applied to the medium layer. element.

  (14) A medium that is optically isotropic when no voltage is applied between the pair of substrates and that generates optical anisotropy when the voltage is applied is sandwiched between at least one of the pair of substrates. In the display device in which either one of the pixel electrode and the common electrode is formed in a comb-tooth shape on the surface of the other substrate facing the other substrate, the surface electrode on the surface facing the other substrate The planar electrode applies a voltage having the same potential as either the pixel electrode or the common electrode, and the thickness d of the medium and the electrode interval l between the electrodes formed in the comb shape A display device in which the relationship is d ≧ l.

  (15) The display device according to (14), wherein the planar electrode formed on the other substrate has a region where a slit is formed and an electric field is not partially generated.

  According to the present invention, in an electro-optic element that applies an electric field to a medium having optical anisotropy by a plurality of electrode groups composed of transparent electrode groups to control light transmission and blocking, the medium region on the electrode is optically anisotropic. By providing the means for imparting the property, it is possible to obtain an electro-optical element that can respond at high speed and has high luminance and high contrast and high display quality.

  In addition, according to the present invention, not only between the electrodes formed in a comb shape but also on the electrodes contributes to the transmission, so that the transmittance of the display device can be improved.

FIG. 3 is a schematic longitudinal sectional view illustrating an example of a cross-sectional configuration of a main part of the electro-optic element of Example 1 according to the present invention. 2 is a schematic plan view showing an example of a planar configuration of comb-like electrodes 105 and 106 formed on a substrate 101. FIG. 3 is a schematic plan view showing an example of a planar configuration of comb-like electrodes 201 and 202 formed on a substrate 102. FIG. FIG. 2 is a schematic plan view illustrating an example of a planar configuration when the electro-optic element of FIG. 1 is viewed from the direction of an arrow A. It is a schematic longitudinal cross-sectional view which shows an example of the preferable arrangement | positioning method of the comb-tooth electrode 105,106,201,202. FIG. 6 is a schematic plan view illustrating an example of a planar configuration when the electro-optic element of FIG. 5 is viewed from the direction of an arrow A. It is a schematic longitudinal cross-sectional view which shows an example of the cross-sectional structure of the principal part of the electro-optic element of Example 2 by this invention. It is a schematic longitudinal cross-sectional view which shows an example of the cross-sectional structure of the principal part of the electro-optic element of Example 3 by this invention. FIG. 6 is a schematic longitudinal sectional view illustrating an example of a schematic configuration of a main part of an electro-optic element according to a fourth embodiment of the present invention. FIG. 10 is a schematic diagram showing a result of electric field simulation in the configuration of the electro-optic element of Example 4. FIG. 10 is a schematic longitudinal sectional view illustrating an example of a cross-sectional configuration of a main part of an electro-optic element according to Example 5 of the present invention. 2 is a schematic plan view showing an example of a planar configuration of comb-like electrodes 105 and 106 provided on a substrate 101. FIG. 10 is a schematic diagram illustrating a result of electric field simulation in the configuration of the electro-optic element of Example 5. FIG. It is a schematic longitudinal cross-sectional view which shows an example of the cross-sectional structure of the principal part of the electro-optic element of Example 6 by this invention. 2 is a schematic plan view illustrating an example of a planar configuration of an electrode provided on a substrate. FIG. 3 is a schematic plan view illustrating an example of a planar configuration of an electrode 201 provided on a substrate 102. FIG. 10 is a schematic diagram illustrating a result of electric field simulation in the configuration of the electro-optic element of Example 6. FIG. It is a schematic longitudinal cross-sectional view which shows an example of the cross-sectional structure of the conventional electro-optical element. FIG. 19 is a schematic plan view illustrating an example of a planar configuration when the electro-optic element illustrated in FIG. 18 is viewed from the direction of arrow A. FIG. 6 is a schematic graph illustrating an example of a correlation between applied voltage and transmittance in an electro-optic element of the present invention and an example of a correlation between applied voltage and transmittance in a conventional electro-optic element. It is a schematic plan view which shows an example of the plane structure of one pixel in the liquid crystal display device of Example 7 by this invention. FIG. 22 is a schematic cross-sectional view showing an example of a cross-sectional configuration of the liquid crystal display panel taken along line A-A ′ of FIG. 21. FIG. 16 is a schematic diagram illustrating a result of electric field simulation in the pixel configuration of the liquid crystal display device of Example 7. 6 is a schematic longitudinal sectional view showing an example of a cross-sectional configuration of a liquid crystal display device of Comparative Example 2. FIG. 10 is a schematic diagram showing a result of electric field simulation in the configuration of the liquid crystal display device of Comparative Example 2. FIG. It is a schematic cross section which shows an example of the cross-sectional structure of one pixel in the liquid crystal display panel of Example 8 by this invention.

Hereinafter, the present invention will be described in detail together with embodiments (examples) with reference to the drawings.
In all the drawings for explaining the embodiments, parts having the same function are given the same reference numerals and their repeated explanation is omitted.

1 to 6 are schematic diagrams for explaining the schematic configuration and operation of the main part of the electro-optic element according to the first embodiment of the present invention.
FIG. 1 is a schematic longitudinal sectional view showing an example of a cross-sectional configuration of a main part of the electro-optic element of Example 1 according to the present invention. FIG. 2 is a schematic plan view illustrating an example of a planar configuration of the comb-like electrodes 105 and 106 formed on the substrate 101. FIG. 3 is a schematic plan view illustrating an example of a planar configuration of the comb-like electrodes 201 and 202 formed on the substrate 102. FIG. 4 is a schematic plan view showing an example of a planar configuration when the electro-optic element of FIG. 1 is viewed from the direction of arrow A. FIG. 5 is a schematic longitudinal sectional view showing an example of a preferable arrangement method of the comb-like electrodes 105, 106, 201, 202. FIG. 6 is a schematic plan view illustrating an example of a planar configuration when the electro-optic element of FIG. 5 is viewed from the direction of the arrow A.

(Structure of electro-optic element)
For example, as shown in FIG. 1, the electro-optical element of the first embodiment includes three substrates 101, 102, and 103 arranged at a predetermined interval, and a medium layer 203 arranged in a gap between these substrates. , 204. The substrate 101 is provided with a group of electrodes including electrodes 105 and 106, and imparts an optical anisotropy 108 to the medium layer 203. Similarly, the substrate 102 is provided with a group of electrodes including electrodes 201 and 202, and imparts an optical anisotropy 206 to the medium layer 204.

  At this time, the electrode 105 and the electrode 106 provided on the substrate 101 have, for example, a comb shape as shown in FIG. 2 and are arranged so that the comb portions are substantially parallel. Similarly, the electrode 201 and the electrode 202 provided on the substrate 102 have, for example, a comb shape, and are arranged so that the comb portions are substantially parallel. In the electro-optic element of Example 1, as materials for the electrodes 105, 106, 201, and 202, ITO (indium tin oxide), ZnO (zinc oxide), and IZO (indium) having excellent transparency and conductivity are used. Zinc oxide).

  At this time, as shown in FIG. 4, for example, as shown in FIG. 4, the comb-tooth portions of the comb-like electrodes 105, 106, 201, and 202 formed on the respective substrates are Combined so that they do not overlap when viewed. In the electro-optic element of Example 1, the electrode gap L1 at the comb-tooth portion between the electrodes 105 and 106 on the substrate 101 and the electrodes 201 and 202 on the substrate 102 or the electrode width L2 at the comb-tooth portion is as small as possible. Better. When the electrode interval L1 is as small as possible, the electrodes 105, 106, 201, and 202 are arranged as shown in FIGS. 5 and 6, for example.

  In the portion of the electrode gap L1, as shown in FIG. 1, the optical anisotropy 108 imparted to the medium layer 203 and the optical anisotropy 206 imparted to the medium layer 204 overlap. The degree of optical anisotropy becomes greater than the directionality, and the permeability of the medium layer becomes non-uniform, leading to a reduction in image quality. On the other hand, if the comb-tooth portion of the electrode overlaps, no optical anisotropy is imparted to the overlap portion, so that no light is transmitted. Therefore, in the electro-optic element of Example 1, it is desirable to make the electrode gap L1 as small as possible, or make the electrode width L2 as small as possible. If the electrode width L2 is processed as small as possible and the area between the electrodes is increased, the effect on the image quality of the difference between the optical anisotropy on the electrodes and the optical anisotropy between the electrodes is reduced. Since the optical anisotropy imparted by the medium layers 203 and 204 overlaps, apparently low voltage driving is possible.

  Further, in the electro-optic element of Example 1, as the medium layers 203 and 204, a medium that has substantially optical isotropy when no electric field is applied and develops optical anisotropy with the application of the electric field is used. Examples thereof include a blue phase liquid crystal material and a medium having cubic symmetry.

  The blue phase liquid crystal material is a material in which the temperature range of the blue phase is expanded by polymerizing a monomer containing a nematic liquid crystal composition containing a chiral agent in the blue phase. For nematic liquid crystals, organic compounds having a ring structure and a long chain structure substituted with polar groups, which are generally used in liquid crystal displays, are used. As the chiral agent, an organic compound having an asymmetric carbon in the molecule is used. Typical polymerizable monomers include acrylic monomers, and in the case of photopolymerization, a polymerization initiator such as an acetophenone derivative is used in combination. In the electro-optical element having the configuration as in the first embodiment, high-speed response to an applied voltage can be obtained by using the blue phase liquid crystal material as described above as the medium layers 203 and 204.

  When different potentials are applied to the electrodes 105 and 106 of the electro-optic element configured in this manner from an external power source (not shown), an electric field is applied to the medium layer 203 mainly in the direction of the arrow 107 in FIG. As a result, the optical anisotropy 108 in the same direction as the electric field direction 107 is imparted to the medium layer 203 between the electrodes 105 and 106. Furthermore, when different potentials are applied between the electrode 201 and the electrode 202, an electric field is applied to the medium layer 204 mainly in the direction of the arrow 205 in FIG. As a result, an optical anisotropy 206 in substantially the same direction as the electric field direction 205 is imparted to the medium layer 204 between the electrodes 201 and 202. That is, in the configuration of the first embodiment, the electric field directions 107 and 205 of the electric field applied to the medium layers 203 and 204 are substantially parallel, and the optical anisotropy 108 and 206 generated in the medium layers 203 and 204 when the electric field is applied are also included. It becomes almost parallel.

  The optical anisotropy is refractive index anisotropy, and indicates a difference in refractive index in the in-plane direction of the substrate applied by an electric field, that is, anisotropy. The arrows of the optical anisotropy 108 and 206 shown in FIG. 1 indicate directions in which a refractive index greater than the orthogonal direction is given.

  Furthermore, it is desirable that the optical anisotropy 108 imparted to the medium layer 203 and the optical anisotropy 206 imparted to the medium layer 204 are imparted substantially simultaneously, so that a potential difference is applied to the electrodes 105 and 106. It is more desirable that the timing and the timing at which the potential difference is applied to the electrode 201 and the electrode 202 are substantially the same. Therefore, in the electro-optical element of Example 1, for example, the electrode 105 and the electrode 201 and the electrode 106 and the electrode 202 may be connected.

  In the configuration of the first embodiment, the optical anisotropy 206 imparted to the medium layer 204 is imparted to the region directly above the comb-tooth portion of the electrodes 105 and 106 on the substrate 101 in the substrate normal direction. When observed from the direction A, optical anisotropy is imparted to the comb-tooth portions of the electrodes 105 and 106 on the substrate 101.

  Furthermore, in the electro-optical element of Example 1, the first polarizing plate 104 and the second polarizing plate 207 are disposed outside the substrate 101 and the substrate 103. The first polarizing plate 104 and the second polarizing plate 207 contain an iodine dye, and iodine is oriented by forming a multimer in the polarizing plate. Due to the dichroism, the polarizing plate converts incident natural light into linearly polarized light having a sufficiently high degree of polarization. The orientation direction of the iodine dye multimer is the absorption axis, and the absorption axes 301 and 302 of this polarizing plate are arranged at an angle of 45 ° ± 10 ° with the electric field directions 107 and 205 applied to the medium layer. ing.

  That is, as shown in FIG. 4, the absorption axes 301 and 302 of the polarizing plate are 45 ° ± 10 ° clockwise and counterclockwise with respect to the longitudinal direction of the comb teeth of the electrodes 105, 106, 201, and 202, respectively. It is arranged at an angle of. The angle of ± 10 degrees is set as a range that absorbs electrode manufacturing errors and the like. Further, the polarizing plates 104 and 207 may be disposed on the inner side of the substrate, that is, on the medium layer side, or may be formed of a water-soluble lyotropic liquid crystal dye material or a polymer liquid crystal material containing a dichroic dye. In addition, when the polarizing plates 104 and 207 are arranged on the inner side of the substrate, the configuration is not limited to the above configuration. For example, a wire grid polarizer in which thin conductor wires are arranged at intervals shorter than the wavelength of light as a built-in polarizing layer. It can also be adopted.

  When the polarizing plates 104 and 207 are arranged in this way, the light incident on the electro-optic element from the direction of the substrate 101 is converted into linearly polarized light by the first polarizing plate 104, and the medium layers 203 and 204 are optical when no voltage is applied. In order to show isotropic properties, the light is blocked by the second polarizing plate 207 when the light is emitted from the substrate 103. That is, black is displayed when no voltage is applied. In addition, the polarized light incident from the direction of the substrate 101 and passing between the electrodes 105 and 106 when an electric field is applied becomes elliptically polarized light whose optical axis is rotated 90 degrees by the optical anisotropy 108 imparted to the medium layer 203. , And passes through the substrate 102, the electrode 201, the medium layer 204, the substrate 103, and the second polarizing plate 207. At this time, since birefringence (optical anisotropy) is not imparted on the electrode 201, the optical axis of polarized light does not rotate in the region immediately above the electrode 201.

  In addition, polarized light that is incident from the direction of the substrate 101 and passes through the comb-shaped electrode portion of the electrode 105 or the electrode 106 when an electric field is applied has no optical anisotropy applied to the medium layer 203 on the electrode 105 or the electrode 106. Although the optical axis is not rotated in the layer 203, the optical axis is rotated 90 degrees by the optical anisotropy 206 imparted to the medium layer 204, and passes through the substrate 103 and the second polarizing plate 207. Is emitted. That is, when a voltage is applied, white display is performed, and light is transmitted through the comb teeth of the transparent electrodes 105, 106, 201, 202. Therefore, compared to the case where no optical anisotropy is imparted on the electrodes 105 and 106, that is, the case where the medium layer 204 and the substrate 102 are not present, light is transmitted through the electrode portion, so that a higher transmittance can be obtained. it can.

(Method for manufacturing electro-optical element)
The electro-optic element of Example 1 was manufactured according to the following outline process. First, ITO is vapor-deposited on a glass substrate by a sputtering method, a photoresist is applied, an exposure process, an etching process, and the like are performed. Then, a substrate 101 having comb-like electrodes 105 and 106 as shown in FIG. A substrate 102 having comb-like electrodes 201 and 202 as shown in FIG. The film thickness of ITO was 100 nm, the electrode width L2 of the comb tooth portion was 10 microns, and the electrode interval was 15 microns. Next, the substrate 101 and the substrate 102 on which the comb-like electrodes are formed are made such that the electrode forming surface of the substrate 101 and the back surface of the surface on which the electrode of the substrate 102 is formed are opposed to each other, and a spacer (not shown) Were attached so that the substrate interval was 15 microns. Further, a glass substrate (substrate 103) was bonded in the same manner so that the distance from the substrate 102 was 15 microns. Next, a blue phase liquid crystal mixture was injected as medium layers 203 and 204 between the substrate 101 and the substrate 102 and between the substrate 102 and the substrate 103.

  For the blue phase liquid crystal mixture, a mixture of an acrylic monomer, a liquid crystal material, a chiral agent, and a photopolymerization initiator described in Non-Patent Document 1 is used. The blue phase was stabilized by irradiating ultraviolet light and polymerizing the acrylic monomer.

  Next, the electrode 105 of the substrate 101 and the electrode 201 of the substrate 102 were connected at the end of the substrate, and the electrode 106 of the substrate 101 and the electrode 202 of the substrate 102 were connected at the end of the substrate. Further, as shown in FIG. 4, the polarizing plates 104 and 207 are formed on the substrate so that the respective absorption axes 301 and 302 are about 45 degrees with the longitudinal direction of the comb teeth of the electrodes 105, 106, 201, and 202. 101 and the substrate 103 were attached to the outside.

  In the electro-optic element of Example 1 manufactured by the above procedure, when an AC voltage is applied from the external power source to the electrode 106 and the electrode 202 connected to the connected electrode 105 and the electrode 201, the correlation between the applied voltage and the transmittance is obtained. The relationship is like the curve of (a) shown in FIG. The produced electro-optic element had a higher transmittance than the conventional element shown in Comparative Example 1 described later. As a result of observation with a microscope, in the electro-optic element of Example 1, light was transmitted also on the comb-like electrodes 105, 106, 201, 202, and the effect of the present invention was confirmed.

  FIG. 7 is a schematic longitudinal sectional view illustrating an example of a cross-sectional configuration of a main part of the electro-optic element according to the second embodiment of the present invention.

  The electro-optic element of Example 2 is different from Example 1 in that, for example, electrodes 201 and 202 for applying an electric field to the medium layer 204 are formed on the substrate 103 as shown in FIG. is there. The planar configuration of the electrodes 105, 106, 201, and 202, and the relationship between the longitudinal direction of the comb teeth of each electrode and the absorption axes 301 and 302 of the polarizing plates 104 and 207 are shown in FIGS. 2 and 4, respectively. The configuration is the same. Therefore, a detailed description of the configuration of the electro-optical element of Example 2 is omitted. At this time, in the electro-optical element of Example 2, when different potentials are applied to the electrode 201 and the electrode 202 as in Example 1, an electric field is applied to the medium layer 204 to impart optical anisotropy. As a result, in the electro-optical element of Example 2, light was transmitted through the transparent electrodes 105 and 106 when a voltage was applied as in Example 1, and high transmittance was obtained.

  The electro-optical element of Example 2 was manufactured according to the following outline process. First, as in Example 1, the substrate 101 having the comb-like electrodes 105 and 106 and the substrate 103 having the comb-like electrodes 201 and 202 were formed. Next, the substrate 101 on which the electrodes 105 and 106 are formed and the substrate 102 on which no electrode is formed are bonded together, and the substrate 103 on which the electrodes 201 and 202 are further formed is placed so that the electrode formation surface faces the substrate 102. Pasted together. Next, as in Example 1, a blue phase liquid crystal mixture was injected between the substrates as the medium layers 203 and 204, and the monomer was polymerized by light irradiation.

  Next, as in Example 1, the electrode 105 of the substrate 101 and the electrode 201 of the substrate 102 were connected at the substrate end, and the electrode 106 of the substrate 101 and the electrode 202 of the substrate 102 were connected at the substrate end. Further, as shown in FIG. 4, the polarizing plates 104 and 207 are formed on the substrate so that the respective absorption axes 301 and 302 are about 45 degrees with the longitudinal direction of the comb teeth of the electrodes 105, 106, 201, and 202. 101 and the substrate 103 were attached to the outside.

  In the electro-optic element of Example 2 manufactured by the above procedure, when an AC voltage is applied from the external power source to the electrode 106 and the electrode 202 connected to the connected electrode 105 and the electrode 201, the correlation between the applied voltage and the transmittance is obtained. The relationship is almost the same as the curve (a) shown in FIG. 20, and a higher transmittance was obtained compared to the conventional example having the relationship like the curve (b) shown in FIG. .

  FIG. 8 is a schematic longitudinal sectional view illustrating an example of a cross-sectional configuration of a main part of the electro-optic element according to the third embodiment of the present invention.

  The electro-optic element of Example 3 is different from Example 1 in that, for example, electrodes 105 and 106 for applying an electric field to the medium layer 203 are formed on the substrate 102 as shown in FIG. is there. The planar configuration of the electrodes 105, 106, 201, and 202, and the relationship between the longitudinal direction of the comb teeth of each electrode and the absorption axes 301 and 302 of the polarizing plates 104 and 207 are shown in FIGS. 2 and 4, respectively. The configuration is the same. Therefore, a detailed description of the configuration of the electro-optical element of Example 3 is omitted. At this time, in the electro-optical element of Example 3, when different potentials are applied to the electrode 105 and the electrode 106 as in Example 1, an electric field is applied to the medium layer 203 to impart optical anisotropy. As a result, in the electro-optical element of Example 3, light was transmitted through the transparent electrodes 105 and 106 when a voltage was applied, as in Example 1, and high transmittance was obtained.

  FIG. 9 is a schematic longitudinal sectional view illustrating an example of a schematic configuration of a main part of the electro-optic element according to the fourth embodiment of the present invention.

  Unlike the first to third embodiments, the electro-optical element of the fourth embodiment has a single medium layer (only the medium layer 203) as shown in FIG. 9, for example. At this time, the transparent electrodes 201 and 202 are provided on the side of the substrate 102 facing the substrate 101. The planar configuration of the electrodes 105, 106, 201, and 202, and the relationship between the longitudinal direction of the comb teeth of each electrode and the absorption axes 301 and 302 of the polarizing plates 104 and 207 are shown in FIGS. 2 and 4, respectively. The configuration is the same. Therefore, a detailed description of the configuration of the electro-optical element of Example 4 is omitted.

  In the electro-optic element of Example 4, when different potentials are applied to the electrode 105 and the electrode 106, the optical anisotropy 108 is imparted to the medium layer 203 between the electrode 105 and the electrode 106. Further, when different potentials are applied to the electrode 201 and the electrode 202, an optical anisotropy 206 is imparted to the medium layer 203 between the electrode 201 and the electrode 202. At this time, different potentials are applied to the electrode 105 and the electrode 202, and different potentials are applied to the electrode 106 and the electrode 201, whereby the medium layer 203 between the electrode 105 and the electrode 202 and between the electrode 106 and the electrode 201 is provided. Also, the optical anisotropy 206 can be imparted. The optical anisotropy 206 imparted by the electrode 201 and the electrode 202 on the substrate 102 is imparted immediately above the electrode 105 and the electrode 106 on the substrate 101 as viewed from the substrate normal direction. As a result, similarly to the electro-optic element of Example 1, the electro-optic element of Example 4 allows light to pass through the transparent electrodes 105 and 106 when a voltage is applied, and high transmittance is obtained.

  FIG. 10 is a schematic diagram illustrating a result of electric field simulation in the configuration of the electro-optical element of Example 4.

  In the electro-optic element of Example 4, when the electrode 106 and the electrode 202 are set to the same potential and the electrode 105 and the electrode 201 are set to the same potential, the equipotential line (equipotential surface) of the electric field applied to the medium layer 203 is For example, the distribution is as shown in FIG. 10, between the electrode 105 and the electrode 106, between the electrode 105 and the electrode 202, between the electrode 201 and the electrode 202, and between the electrode 106 and the electrode 201. It can be seen that an electric field is applied. That is, as shown in FIG. 9, the electro-optic element of Example 4 is between these electrodes 105, 106, between electrode 105 and electrode 202, between electrode 106 and electrode 201, by these electric fields, In addition, optical anisotropy 108 and 206 is imparted to the medium layer 203 between the electrode 201 and the electrode 202. As a result, in the electro-optical element of Example 4, light was transmitted through the transparent electrodes 105 and 106 when a voltage was applied as in Example 1, and high transmittance was obtained.

FIGS. 11 and 12 are schematic diagrams for explaining a schematic configuration of a main part of the electro-optic element according to the fifth embodiment of the present invention.
FIG. 11 is a schematic longitudinal sectional view showing an example of a cross-sectional configuration of the main part of the electro-optic element according to the fifth embodiment of the present invention. FIG. 12 is a schematic plan view illustrating an example of a planar configuration of the comb-like electrodes 105 and 106 provided on the substrate 101.

  The electro-optic element of the fifth embodiment has a single medium layer (only the medium layer 203) as in the fourth embodiment. The electro-optic element of Example 5 differs from Example 4 in that, for example, as shown in FIGS. 11 and 12, the planar shapes of the electrodes 105 and 106 provided on the substrate 101 are different. Other points, for example, the relationship between the longitudinal direction of the comb-tooth portion of each electrode and the absorption axes 301 and 302 of the polarizing plates 104 and 207 are the same as those of the electro-optic element of the fourth embodiment. Therefore, a detailed description of the configuration of the electro-optic element of Example 5 is omitted.

  In the electro-optic element of Example 5, when different potentials are applied to the electrode 105 and the electrode 106, the optical anisotropy 108 is imparted to the medium layer 203 between the electrode 105 and the electrode 106. Further, when different potentials are applied to the electrode 201 and the electrode 202, an optical anisotropy 206 is imparted to the medium layer 203 between the electrode 201 and the electrode 202. At this time, different potentials are applied to the electrode 105 and the electrode 202, and different potentials are applied to the electrode 106 and the electrode 201, whereby the medium layer 203 between the electrode 105 and the electrode 202 and between the electrode 106 and the electrode 201 is provided. Also, the optical anisotropy 206 can be imparted. The optical anisotropy 206 imparted by the electrode 201 and the electrode 202 on the substrate 102 is imparted immediately above the electrode 105 and the electrode 106 on the substrate 101 as viewed from the substrate normal direction. As a result, similarly to the electro-optic element of Example 1, the electro-optic element of Example 5 allows light to pass through the transparent electrodes 105 and 106 when a voltage is applied, and high transmittance is obtained.

  FIG. 13 is a schematic diagram illustrating a result of electric field simulation in the configuration of the electro-optic element of Example 5.

  In the electro-optic element of Example 5, when the electrode 106 and the electrode 202 are set to the same potential and the electrode 105 and the electrode 201 are set to the same potential, the equipotential line (equipotential surface) of the electric field applied to the medium layer 203 is For example, the distribution is as shown in FIG. 13, between the electrode 105 and the electrode 106, between the electrode 105 and the electrode 202, between the electrode 201 and the electrode 202, and between the electrode 106 and the electrode 201. It can be seen that an electric field is applied. That is, as shown in FIG. 11, the electro-optic element of Example 5 is between these electrodes 105 and 106, between electrode 105 and electrode 202, between electrode 106 and electrode 201, by these electric fields, In addition, optical anisotropy 108 and 206 is imparted to the medium layer 203 between the electrode 201 and the electrode 202. As a result, in the electro-optic element of Example 5, light was transmitted through the transparent electrodes 105 and 106 when a voltage was applied, as in Example 1, and high transmittance was obtained.

14 to 16 are schematic views for explaining a schematic configuration of a main part of the electro-optic element of Example 6 according to the present invention.
FIG. 14 is a schematic longitudinal sectional view showing an example of a cross-sectional configuration of the main part of the electro-optic element of Example 6 according to the present invention. FIG. 15 is a schematic plan view illustrating an example of a planar configuration of the electrode 106 provided on the substrate 101. FIG. 16 is a schematic plan view illustrating an example of a planar configuration of the electrode 201 provided on the substrate 102.

  The electro-optic element of Example 6 has a single medium layer (medium layer 203 only), as in Example 4. The electro-optic element of Example 6 differs from Example 4 in that, for example, as shown in FIGS. 14 to 16, only the electrode 106 is provided on the substrate 101 and only the electrode 201 is provided on the substrate 102. It is. Other points, for example, the relationship between the longitudinal direction of the comb-tooth portion of each electrode and the absorption axes 301 and 302 of the polarizing plates 104 and 207 are the same as those of the electro-optic element of the fourth embodiment. Therefore, the detailed description regarding the configuration of the electro-optic element of Example 6 is omitted.

  In the electro-optical element of Example 6, when different potentials are applied to the electrode 106 and the electrode 201, the optical anisotropy 206 is imparted to the medium layer 203 between the electrode 106 and the electrode 201. Since the optical anisotropy 206 is given in an oblique direction with respect to the substrate normal direction, the optical anisotropy is also directly above the electrode 106 on the substrate 101 and the electrode 201 on the substrate 102 as viewed from the substrate normal direction. Is granted. As a result, the electro-optic element of Example 6 allows light to pass through the transparent electrodes 106 and 201 when a voltage is applied, and high transmittance can be obtained.

  FIG. 17 is a schematic diagram illustrating a result of electric field simulation in the configuration of the electro-optic element of Example 6.

  In the electro-optic element of Example 6, when different potentials are applied to the electrode 106 and the electrode 201, the equipotential lines (equipotential surface) of the electric field applied to the medium layer 203 are, for example, as shown in FIG. It can be seen that an electric field is applied between the electrode 106 and the electrode 201. Further, it can be seen that the electric field between the electrode 106 and the electrode 201 is also generated on the respective electrodes 106 and 201. That is, in the electro-optic element of Example 6, as shown in FIG. 14, the optical anisotropy 206 is imparted to the medium layer 203 between the electrode 106 and the electrode 201 by this electric field. As a result, in the electro-optical element of Example 6, light was transmitted through the transparent electrodes 106 and 201 when a voltage was applied as in Example 1, and high transmittance was obtained.

  By the way, the electro-optic element of the present invention has one of the basic configurations shown in FIGS. 1, 5, 7, 8, 9, 11, and 14 arranged in a matrix as one pixel, By connecting each electrode and further including a backlight, it can be used as a liquid crystal display device.

  In this case, a plurality of data signal lines and a plurality of scanning signal lines intersecting each other and a common signal line are provided, and one of the comb-like electrodes of the first electrode group and the second electrode group is supplied to the scanning signal line. An active element that is controlled to be turned on and off by the active signal, a pixel electrode connected to the data signal line through the active element, and the other as a common electrode connected to the common signal line. It can also be set as a liquid crystal display device. The active element may be provided separately for the first electrode group and the second electrode group, or may be provided only for one of the pixel electrodes of the first electrode group and the pixel electrode of the second electrode group. May be electrically connected. In addition, the comb-like electrodes corresponding to the common electrode of the first electrode group and the second electrode group may be given different potentials, or both may be electrically connected. In addition, such a liquid crystal display device can be a color liquid crystal display device by providing a color filter on any substrate.

  Furthermore, in the case of this liquid crystal display device, in order to improve the viewing angle dependency of display characteristics, a plurality of directions in which optical anisotropy occurs may be provided in one pixel. In this case, the comb electrodes may be arranged so that the direction of optical anisotropy is orthogonal in the plane. In this liquid crystal display device, high transmittance can be obtained as an effect of the present invention, so that light from the backlight can be emitted efficiently, and a liquid crystal display device with low power consumption and high white luminance can be obtained. .

  Note that the electro-optical element of the present invention is not limited to the configuration shown in the drawings referred to in the description of the first to sixth embodiments, and may be modified without departing from the spirit of the present invention. Can be combined. For example, a plurality of regions having different optical anisotropy directions may be formed in one element.

21 and 22 are schematic diagrams for explaining an example of a schematic configuration of the main part of the liquid crystal display device according to the seventh embodiment of the present invention.
FIG. 21 is a schematic plan view illustrating an example of a planar configuration of one pixel in the liquid crystal display device according to the seventh embodiment of the present invention. FIG. 22 is a schematic cross-sectional view showing an example of a cross-sectional configuration of the liquid crystal display panel taken along line AA ′ of FIG.

  The configuration of the electro-optic element of the present invention is such that, for example, an isotropic liquid crystal layer is formed by generating an electric field between a pixel electrode and a common electrode disposed on a substrate sandwiching an isotropic liquid crystal and changing the electric field strength. The present invention can be applied to a liquid crystal display panel (liquid crystal display device) that controls optical characteristics. An isotropic liquid crystal is optically isotropic when no voltage is applied, and induces birefringence (optical anisotropy) in the direction of voltage application when a voltage is applied. As prior art documents concerning such a device using an isotropic liquid crystal, there are, for example, Patent Document 3 and Patent Document 4. In order to control the transmittance of the isotropic liquid crystal due to the properties of the isotropic liquid crystal, the polarizing plates 104 and 207 are arranged in crossed Nicols, and the electric field in the in-plane direction (lateral direction) of the liquid crystal display panel. Must be applied. Therefore, it can be said that an IPS electrode structure is basically suitable for a liquid crystal display panel using an isotropic liquid crystal. However, in the conventional IPS electrode structure, an electric field in the in-panel direction is not generated on the electrode, and thus does not contribute to transmission on the electrode. For this reason, in order to perform good display using isotropic liquid crystals, it is usually necessary to improve the IPS electrode structure to form an element that generates more electric field parallel to the panel surface.

  From this point of view, Example 7 describes an example of an electrode structure suitable for an IPS liquid crystal display panel using an isotropic liquid crystal.

  In the liquid crystal display device of Example 7, the configuration of one pixel in the liquid crystal display panel is configured as shown in FIGS. 21 and 22, for example. The video signal of the video signal line DL is supplied to the pixel electrode PX connected to the source electrode of the thin film transistor TFT via the thin film transistor TFT controlled by the scanning signal line GL. At this time, in the liquid crystal display device of Example 7, an electric field is formed between the pixel electrode PX and the common electrode CT (sometimes referred to as a common electrode), and between the pixel electrode PX and an electrode CT2 described later, etc. Display is performed by driving the isotropic liquid crystal layer LC. The pixel electrode PX and the common electrode CT correspond to the electrode 105 and the electrode 106 in the first to fifth embodiments, respectively. The isotropic liquid crystal layer LC corresponds to the medium layer 203 in the fourth to sixth embodiments, and is made of, for example, the aforementioned blue phase liquid crystal mixture. Further, the drain electrode and the source electrode of the thin film transistor TFT vary depending on the bias relationship, that is, the relationship between the potential of the video signal line DL and the potential of the pixel electrode PX when the thin film transistor TFT is turned on. The one connected to the pixel electrode PX is called a source electrode.

  A black matrix BM is disposed on the upper substrate SUB2 having the color filter CF to block unnecessary light leakage. The substrate SUB2 corresponds to the substrate 102 in the fourth and fifth embodiments. In addition, the color filters CFG, CFR, and CFB have different colors between adjacent pixels in the horizontal direction, and therefore have different colors. Further, an overcoat film OC for planarization is applied on the color filters CFG, CFR, CFB and the black matrix BM, and an electrode CT2 is further formed thereon.

  On the other hand, the lower substrate SUB1 includes a common electrode CT and a pixel electrode PX formed in a comb shape in each pixel. The substrate SUB1 corresponds to the substrate 101 in the fourth and fifth embodiments. An insulating film GI is provided on the common electrode CT, and a video signal line DL is provided so as to correspond to the common electrode CT for each pixel. Further, a protective film PAS is provided on the video signal line DL, and the pixel electrode PX is disposed thereon. The common electrode CT and the pixel electrode PX are formed of a transparent conductive film such as ITO, for example. Each of the pair of substrates SUB1 and SUB2 includes polarizing plates PL1 and PL2, and the absorption axis PT1 of the polarizing plate PL1 and the absorption axis PT2 of the polarizing plate PL2 are crossed Nicols (sometimes referred to as crossed Nicols). It is arranged to be.

  In the pixel having such a configuration, the electrode CT2 is driven to have the same potential as either the common electrode CT or the pixel electrode PX. Hereinafter, the electrode CT2 will be described as being at the same potential as the common electrode CT unless otherwise specified. However, the electrode CT2 may be driven at the same potential as the pixel electrode PX unless there is a restriction on the circuit configuration or process.

  With this configuration, when no voltage is applied, the isotropic liquid crystal layer LC is isotropic, so black display is obtained. Further, at the time of voltage application, birefringence in the voltage application direction is induced between the common electrode CT and the pixel electrode PX and on the common electrode CT in parallel with the panel surface, so that white display is performed. In addition, since electric lines of force parallel to the panel surface are formed on either the common electrode CT or the pixel electrode PX having the same potential as the electrode CT2, birefringence is generated. This contributes to transmission during white display. Thus, in the pixel of the liquid crystal display device of Example 7, the transmittance of the display device can be improved because it contributes to transmission not only between the electrodes but also on the electrodes.

  In the liquid crystal display device of Example 7, the structure of the electrode formed on the substrate SUB1 is characterized in that either one of the pixel electrode PX and the common electrode CT is comb-like, and isotropic. The electrode far from the liquid crystal layer LC may be formed in a flat plate shape.

  The liquid crystal display device of Example 7 was manufactured, for example, according to the following process. In addition, what is necessary is just to select what was applied with the conventional manufacturing method about the material and formation method to be used. Therefore, the specific description regarding the manufacturing method of the liquid crystal display device of Example 7 is omitted.

  First, for example, a thin film transistor TFT and a scanning signal line GL are formed on one substrate SUB1. Next, a common electrode CT was formed in a comb-like shape as a transparent conductive layer made of ITO on the upper layer of the substrate SUB1, and an insulating film GI made of silicon nitride or organic matter was further formed on the upper layer. In Example 7, the thicknesses of the comb-like common electrode CT and the insulating film GI made of ITO were 77 nm and 500 nm, respectively.

  Next, after forming the video signal line DL and the protective film PAS on the insulating film GI, the pixel electrode PX was formed in a comb shape as a transparent conductive layer made of ITO having a film thickness of 77 nm. At this time, the pixel electrode PX was formed so that the distance from the common electrode CT was 10.0 μm.

  On the other substrate SUB2, after forming a black matrix BM, a color filter CFG, and the like, an overcoat film OC was applied and baked, and then an electrode CT2 was formed as a transparent electrode layer made of ITO having a film thickness of 77 nm. .

  Next, the substrate SUB1 on which the pixel electrode PX and the common electrode CT were formed and the substrate SUB2 on which the electrode CT2 was formed were bonded together with a spacer and a peripheral sealant interposed therebetween to assemble a cell.

  In addition, an optically isotropic medium, which will be described later, is sealed in this cell in a vacuum to provide an isotropic liquid crystal layer LC, which is then sealed with a sealant made of an ultraviolet curable resin to produce a panel. did.

  At this time, the thickness (gap) of the isotropic liquid crystal layer LC made of an optically isotropic medium is such that the relationship between the gap d and the distance l between the pixel electrode PX and the common electrode CT satisfies d ≧ l. The spacer was adjusted so as to be 13.0 μm in an enclosed state.

  Next, this panel is sandwiched between two polarizing plates PL1 and PL2 (for example, SEG1224DU manufactured by Nitto Denko Corporation), and the polarizing transmission axis of one polarizing plate PL1 is orthogonal to the polarizing transmission axis of the other polarizing plate PL2. Arranged. At this time, the polarizing plates PL1 and PL2 are arranged so that the directions of the absorption axes PT1 and PT2 form 45 degrees with respect to the angle in the in-plane direction of the electric force lines EFL.

  Next, a drive circuit is connected so that an AC drive voltage is applied to the comb-shaped common electrode CT, pixel electrode PX, and electrode CT2, and then a backlight is connected to form a module so that the liquid crystal display device is Obtained.

  As the isotropic liquid crystal layer LC (medium exhibiting optical isotropy) sandwiched between the substrate SUB1 and the substrate SUB2, for example, liquid crystal material JC1041XX manufactured by Chisso Corporation described in Non-Patent Document 2, Aldrich Corporation A liquid crystal material that exhibits an optically isotropic blue phase was used, such as a liquid crystal composition comprising 4-cyano-4'-pentylbiphenyl (5CB) manufactured by Merck and a chiral agent ZLI-4572 manufactured by Merck. In addition to the material, any medium that has optical isotropic characteristics when no voltage is applied and exhibits optical anisotropy when a voltage is applied may be used in the same manner. That is, the isotropic liquid crystal layer LC may be, for example, a layer in which bent-core shaped molecules described in Non-Patent Document 3 are aligned by a vertical alignment film. In this case, it is necessary to form an alignment film between the isotropic liquid crystal layer LC and the substrates SUB1 and SUB2. However, in the present invention, the type of alignment film and the method of alignment treatment are not specified at all. Absent.

  As a result of driving the liquid crystal display device obtained by the above procedure, high transmittance could be obtained. Further, as a result of observing the pixels of the liquid crystal display device being driven, light is transmitted between the pixel electrode PX and the common electrode CT, and part of the common electrode CT, which is why the transmittance is high. It has been confirmed that this is because the common electrode CT also contributes to the display.

  FIG. 23 is a schematic diagram illustrating a result of electric field simulation in the pixel configuration of the liquid crystal display device of Example 7.

  When the electric field simulation was performed by schematically expressing the electrode configuration in the liquid crystal display device of Example 7, the equipotential lines (equipotential surface) generated between the pixel electrode PX and the common electrode CT and the electrode CT2 are For example, the distribution is as shown in FIG. At this time, electric lines of force EFL that perpendicularly cross the equipotential lines are formed in the isotropic liquid crystal layer LC. According to this, it was found that an electric force line EFL substantially parallel to the substrate SUB1 is generated between the pixel electrode PX and the common electrode CT. Since the optically isotropic medium used in Example 7 generates birefringence in the direction in which the electric lines of force are generated, light is transmitted only at the locations where the birefringence generated along the electric lines of force is generated. It will be transparent. Accordingly, the transmitted light intensity varies between the pixel electrode PX and the common electrode CT in accordance with the magnitude of the birefringence generated, and thus can be used as a display device. In the simulation results shown in FIG. 23, almost no electric lines of force are generated on the pixel electrode PX substantially parallel to the surface of the substrate SUB1, but no parallel electric lines of force are generated on the common electrode CT. Has occurred. From this, the transmittance of each pixel can be improved by using a transparent electrode made of ITO for the common electrode CT as in the configuration of the seventh embodiment.

(Comparative Example 1)
In order to investigate the effect of the liquid crystal display device of Example 7, the inventors of the present application have compared the distance l between the pixel electrode PX and the common electrode CT in the configuration shown in FIG. 21 and FIG. A liquid crystal display device in which l = 10.0 μm and d = 4 μm was manufactured as a relationship in which d <l with respect to the cell gap d.

  As a result of driving the liquid crystal display device of Comparative Example 1, the transmittance was lower than that of the liquid crystal display device of Example 7.

(Comparative Example 2)
FIG. 24 is a schematic longitudinal cross-sectional view showing an example of a cross-sectional configuration of the liquid crystal display device of Comparative Example 2.

  In addition, in order to investigate the effect of the liquid crystal display device of Example 7, the inventors of the present application manufactured a liquid crystal display device in which the electrode CT2 is not formed on the substrate SUB2 as shown in FIG. did.

  As a result of driving the liquid crystal display device of Comparative Example 2, the transmittance was lower than that of the liquid crystal display device of Example 7.

  FIG. 25 is a schematic diagram showing a result of electric field simulation in the configuration of the liquid crystal display device of Comparative Example 2.

  When the electric field simulation was performed by schematically expressing the electrode configuration in the liquid crystal display device of Comparative Example 2, an equipotential line (equipotential surface) between the pixel electrode PX and the common electrode CT is shown in FIG. The distribution was as shown. That is, in the liquid crystal display device of Comparative Example 2, although electric lines of force EFL substantially parallel to the substrate SUB1 are generated between the pixel electrode PX and the common electrode CT, the substrate is formed on the pixel electrode PX and the common electrode CT. It became clear that almost no electric lines of force were generated substantially parallel to the surface of SUB1.

FIG. 26 is a schematic cross-sectional view showing an example of a cross-sectional configuration of one pixel in the liquid crystal display panel of Example 8 according to the present invention.
FIG. 26 shows an example of a cross-sectional configuration of the liquid crystal display panel at a position corresponding to the line AA ′ in FIG.

  The basic configuration of the pixels in the liquid crystal display panel of the eighth embodiment is the same as that of the seventh embodiment. The configuration of the pixel of the eighth embodiment differs from that of the seventh embodiment in that, for example, as shown in FIG. 26, when the electrode CT2 made of ITO is formed, a portion located immediately above the pixel electrode PX is dry-etched. It is the point which removed and provided the slit. At this time, the width of the slit of the electrode CT2 was the same as that of the pixel electrode PX. Since the pixel electrode PX has a bent structure as shown in FIG. 21, the slit structure of the electrode CT2 is formed to be bent similarly. In addition, a liquid crystal display device was manufactured under the same manufacturing conditions and pixel configuration as in Example 7 except that this slit was formed in the electrode CT2.

  As a result of driving a liquid crystal display device having a liquid crystal display panel configured as in Example 8, a good display was shown. Further, as a result of observing the pixels of the liquid crystal display device being driven, light is transmitted between the pixel electrode PX and the common electrode CT, and part of the common electrode CT, which is why the transmittance is high. It has been confirmed that this is because the common electrode CT also contributes to the display.

  The present invention has been specifically described above based on the above-described embodiments. However, the present invention is not limited to the above-described embodiments, and various modifications can be made without departing from the scope of the present invention. is there.

  For example, in the seventh and eighth embodiments, a pixel in which the longitudinal direction of the comb-tooth portions of the pixel electrode PX and the common electrode CT is the extending direction (y direction) of the video signal line DL and the pixel is bent is taken as an example. Listed. However, it goes without saying that the comb-tooth portions of the pixel electrode PX and the common electrode CT may have, for example, the longitudinal direction extending straight in the extending direction (y direction) of the video signal line DL. Of course, the pixel electrode PX and the common electrode CT may have a structure in which, for example, a pixel electrode PX having a plurality of slits extending in a predetermined direction and a plate-like common electrode CT are stacked. Furthermore, it goes without saying that the pixel electrode PX and the common electrode CT may be formed on the same surface of the insulating layer GI.

101, 102, 103, SUB1, SUB2 Substrate 104, 207, PL1, PL2 Polarizing plate 105, 106, 201, 202 Electrode 107, 205 Electric field direction 108, 206 Optical anisotropy (direction)
203, 204 Medium layer 301, 302, PT1, PT2 (Polarizing plate) Absorption axis DL Video signal line GL Scanning signal line TFT Thin film transistor PX Pixel electrode CT Common electrode LC Isotropic liquid crystal layer BM Black matrix CFG, CFR, CFB Color Filter OC Overcoat film CT2 Electrode GI Insulating film PAS Protective film EFL Electric field lines

Claims (9)

A plurality of opposing parallel substrates, a medium layer sandwiched between the plurality of substrates, a pair of polarizing plates disposed so that absorption axes are substantially orthogonal to each other across the medium layer, and the plurality of the plurality of substrates An electric group comprising a plurality of comb-shaped transparent electrodes provided on at least two surfaces of the substrate and arranged substantially parallel to each other, and controls transmission and blocking of light by an electric field applied to the electrode group In the optical element,
The medium layer is made of a medium having substantially optical isotropy when no electric field is applied, and exhibiting optical anisotropy when the electric field is applied, and applying an electric field by the at least two electrode groups, An optical anisotropy is imparted to the medium layer including a region on the substrate normal;
The tooth portions of the plurality of electrode group, be arranged so as not to overlap each other when viewed from the substrate normal direction,
The plurality of electrode groups apply an electric field at least in a direction parallel to the substrate to the medium layer.
An electro-optical element. A plurality of opposing parallel substrates, a medium layer sandwiched between the plurality of substrates, a pair of polarizing plates disposed so that absorption axes are substantially orthogonal to each other across the medium layer, and the plurality of the plurality of substrates An electric group comprising a plurality of comb-shaped transparent electrodes provided on at least two surfaces of the substrate and arranged substantially parallel to each other, and controls transmission and blocking of light by an electric field applied to the electrode group In the optical element,
The medium layer is made of a medium having substantially optical isotropy when no electric field is applied, and exhibiting optical anisotropy when the electric field is applied, and applying an electric field by the at least two electrode groups, An optical anisotropy is imparted to the medium layer including a region on the substrate normal;
The comb tooth portions of the plurality of electrode groups are arranged so as not to overlap each other when viewed from the substrate normal direction,
Electric field applied to said medium layer by one of the electrode groups of the plurality of electrode groups, in the region of the substrate normal line of the other of the at least one electrode group, that having a component parallel to the substrate,
You wherein electric optical element that. The absorption axis of the polarizing plate is disposed at an angle of 45 ° ± 10 ° with respect to the direction of electric field application to the medium layer as viewed from the normal direction of the substrate, direction of the optical anisotropy to be imparted to the substrate normal direction area on the electrode, according to claim 1 or claim 2, characterized in that said a medium layer substantially parallel or substantially perpendicular to the direction of the electric field to be applied Electro-optic element. The electric field components viewed from the substrate normal direction of each electric field applied to the medium layer by the plurality of electrode groups are substantially parallel to each other, and the electric field is applied to the medium layer substantially simultaneously. The electro-optical element according to claim 1 . A plurality of opposing parallel substrates, a medium layer sandwiched between the plurality of substrates, a pair of polarizing plates disposed so that absorption axes are substantially orthogonal to each other across the medium layer, and the plurality of the plurality of substrates An electric group comprising a plurality of comb-shaped transparent electrodes provided on at least two surfaces of the substrate and arranged substantially parallel to each other, and controls transmission and blocking of light by an electric field applied to the electrode group In the optical element,
The medium layer is made of a medium having substantially optical isotropy when no electric field is applied, and exhibiting optical anisotropy when the electric field is applied, and applying an electric field by the at least two electrode groups, An optical anisotropy is imparted to the medium layer including a region on the substrate normal;
First and second substrates facing each other, a first medium layer sandwiched between the pair of substrates, a third substrate facing the second substrate, the second substrate, and the second substrate An electric field is applied to the first medium layer provided on the side of the second medium layer sandwiched between the third substrate and the second substrate facing the second substrate. A first electrode group, and a second electrode group that is provided on a surface of the second substrate facing the third substrate and applies an electric field to the second medium layer. An electro-optical element characterized. A plurality of opposing parallel substrates, a medium layer sandwiched between the plurality of substrates, a pair of polarizing plates disposed so that absorption axes are substantially orthogonal to each other across the medium layer, and the plurality of the plurality of substrates An electric group comprising a plurality of comb-shaped transparent electrodes provided on at least two surfaces of the substrate and arranged substantially parallel to each other, and controls transmission and blocking of light by an electric field applied to the electrode group In the optical element,
The medium layer is made of a medium having substantially optical isotropy when no electric field is applied, and exhibiting optical anisotropy when the electric field is applied, and applying an electric field by the at least two electrode groups, An optical anisotropy is imparted to the medium layer including a region on the substrate normal;
First and second substrates facing each other, a first medium layer sandwiched between the pair of substrates, a third substrate facing the second substrate, the second substrate, and the second substrate An electric field is applied to the first medium layer provided on the side of the second medium layer sandwiched between the third substrate and the second substrate facing the second substrate. A first electrode group, and a second electrode group that is provided on the surface of the third substrate facing the second substrate and applies an electric field to the second medium layer. An electro-optical element characterized. A plurality of opposing parallel substrates, a medium layer sandwiched between the plurality of substrates, a pair of polarizing plates disposed so that absorption axes are substantially orthogonal to each other across the medium layer, and the plurality of the plurality of substrates An electric group comprising a plurality of comb-shaped transparent electrodes provided on at least two surfaces of the substrate and arranged substantially parallel to each other, and controls transmission and blocking of light by an electric field applied to the electrode group In the optical element,
The medium layer is made of a medium having substantially optical isotropy when no electric field is applied, and exhibiting optical anisotropy when the electric field is applied, and applying an electric field by the at least two electrode groups, An optical anisotropy is imparted to the medium layer including a region on the substrate normal;
First and second substrates facing each other, a first medium layer sandwiched between the pair of substrates, a third substrate facing the second substrate, the second substrate, and the second substrate An electric field is applied to the first medium layer provided on the side of the second medium layer sandwiched between the third substrate and the second substrate facing the first substrate. A first electrode group, and a second electrode group that is provided on a surface of the second substrate facing the third substrate and applies an electric field to the second medium layer. An electro-optical element characterized. The first and second substrates facing each other, the medium layer sandwiched between the pair of substrates, and the medium layer provided on the surface of the first substrate facing the second substrate A first electrode group for applying an electric field to the first substrate, and a second electrode group for applying an electric field to the medium layer provided on the surface of the second substrate facing the first substrate. The electro-optic element according to claim 1 or 2 . One electrode group provided on at least one of the first substrate and the second substrate has an electrically independent common electrode and pixel electrode, and the common electrode and the 9. The electro-optical element according to claim 8 , wherein the pixel electrodes are arranged so as to be line-symmetric with respect to a symmetry axis in a direction in which the comb-shaped comb-tooth portion extends.

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