JP2009014804A - Liquid crystal device and electronic device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid crystal device which can display an image of high contrast and is suitable for compactness. <P>SOLUTION: The liquid crystal device includes a pair of substrates (10, 20) disposed opposite to each other and respectively having alignment layers (16, 22), a liquid crystal (50) interposed between the pair of substrates and composed of liquid crystal molecules (501) to which a pretilt is imparted by the alignment layers, a first optical compensation device (210) having a positive uniaxial property and having a first optical axis (211) tilted in a direction different from the direction in which the long axis of the liquid crystal molecule to which the pretilt is imparted is tilted to one plane along the pair of substrates as an optical axis and a second optical compensation device (220) having a positive uniaxial property and having a second optical axis (221) along the one plane as an optical axis. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a technical field of a liquid crystal device such as a liquid crystal light valve and an electronic apparatus such as a liquid crystal projector provided with the liquid crystal device.

  Some liquid crystal devices of this type include an optical phase difference compensation element such as a phase difference film in order to prevent the contrast from being lowered due to the phase difference (or phase shift) of light generated in the liquid crystal layer.

  With regard to such an optical phase difference compensation element, for example, Patent Document 1 discloses a technique in which an optically anisotropic element is inclined with respect to a vertical alignment type liquid crystal element according to the alignment direction of liquid crystal molecules. Yes.

JP 2006-11298 A

  However, for example, when the optically anisotropic element is tilted and disposed as in the technique disclosed in Patent Document 1, it is necessary to secure a space for placing the optically anisotropic element. For this reason, there is a technical problem that it is difficult to reduce the size of the liquid crystal device itself or a projector including the liquid crystal device, and the degree of freedom in layout is hindered.

  Furthermore, since the optically anisotropic element is tilted according to the alignment direction of the liquid crystal molecules, the mechanism for tilting the optically anisotropic element becomes complicated depending on the alignment direction, or additional adjustment is performed in the assembly process. There is a technical problem that may be necessary.

  The present invention has been made in view of, for example, the above-described problems. For example, a liquid crystal device capable of displaying a high-quality image with a relatively high contrast and suitable for downsizing, and such a liquid crystal device. It is an object to provide an electronic device provided.

  In order to solve the above problems, the liquid crystal device of the present invention is disposed opposite to each other and is sandwiched between a pair of substrates each having an alignment film and the pair of substrates, and a pretilt is caused by the alignment film. A direction in which the major axis of the liquid crystal molecule to which the pretilt is applied is inclined with respect to one plane along the pair of substrates as an optical axis and a liquid crystal composed of the applied liquid crystal molecules. A first optical compensation element having a first optical axis inclined in a different direction, and a second optical compensation element having a positive uniaxial property and having a second optical axis along the one plane as the optical axis. Prepare.

  According to the liquid crystal device of the present invention, the pair of substrates are arranged to face each other, and the liquid crystal is sandwiched between the pair of substrates. The liquid crystal is typically a vertical alignment type liquid crystal, that is, a VA (Vertical Alignment) type liquid crystal. An alignment film is provided on each of the pair of substrates. The alignment film imparts a pretilt that rises by a predetermined angle in a predetermined direction to liquid crystal molecules constituting the liquid crystal. For example, when the liquid crystal is a VA liquid crystal, the liquid crystal molecules are aligned with a pretilt angle in a predetermined direction with respect to a normal line of one plane along the pair of substrates. For example, when the liquid crystal is a TN (Twisted Nematic) type liquid crystal, the liquid crystal molecules are aligned with a pretilt angle in a predetermined direction with respect to one plane along the pair of substrates. Such an alignment film is typically an organic alignment film that is rubbed in a predetermined direction. Alternatively, the alignment film may be an inorganic alignment film. During operation of the liquid crystal device, light such as projection light is incident on the liquid crystal device, and the liquid crystal device functions as a liquid crystal light valve.

  In particular, the present invention includes first and second optical compensation elements. Each of the first and second optical compensation elements is provided on the side of the pair of substrates on which light is incident or on the side from which light is emitted. The first optical compensation element has a positive uniaxial property, and includes, for example, a positive uniaxial crystal. The first optical axis that is the optical axis (that is, the optical axis) of the first optical compensation element is different from the direction in which the long axis of the liquid crystal molecules provided with the pretilt is inclined with respect to one plane along the pair of substrates. Inclined in the direction. That is, the direction in which the first optical axis is inclined with respect to one plane along the pair of substrates, and the long axis of the liquid crystal molecules at the position in contact with the alignment film when the liquid crystal device is not operating are along the pair of substrates. The directions inclined with respect to one plane are different from each other. For example, when the liquid crystal is a VA-type liquid crystal, the first optical axis is typically along a direction symmetrical to the long axis of the liquid crystal molecules to which the pretilt is applied, on one plane along the pair of substrates. . The second optical compensation element is composed of, for example, a positive uniaxial retardation plate (that is, an A plate), and faces the pair of substrates so that the second optical axis that is the optical axis is along the pair of substrates. Be placed. The second optical axis typically intersects the first optical axis when viewed from the normal direction of one plane along the pair of substrates. For example, when the liquid crystal is a VA-type liquid crystal, the second optical axis is typically a long axis of liquid crystal molecules to which a pretilt is applied as viewed from the normal direction of one plane along the pair of substrates. Cross each other.

  Therefore, for example, when the liquid crystal device functioning as a liquid crystal light valve is operated, the phase difference of the light generated when the incident light passes through the liquid crystal composed of the liquid crystal molecules inclined with respect to the pair of substrates is expressed as the first phase difference. And it can compensate by the 2nd optical compensation element. In other words, the first and second optical compensation elements can reduce the anisotropy of the overall refractive index of the liquid crystal sandwiched between the pair of substrates and the first and second optical compensation elements. That is, the refractive index ellipsoid showing the anisotropy of the entire refractive index of the liquid crystal and the first and second optical compensation elements can be made close to a sphere. By performing such compensation, it is possible to prevent the light that has passed through the liquid crystal from entering the output-side polarizing plate in a state of being out of phase. Therefore, for example, in the polarizing plate on the emission side, the possibility of leakage of light that should not be transmitted is reduced, and it is possible to prevent a decrease in contrast and a reduction in viewing angle.

  Furthermore, the first and second optical compensation elements can compensate for the phase difference of the light generated in the liquid crystal without being inclined with respect to the pair of substrates. Therefore, it can be suitable for downsizing the liquid crystal device and the like.

  Each of the first and second optical compensation elements may be provided on the side where light enters the pair of substrates (in other words, the side where light enters the liquid crystal), or the pair of substrates. May be provided on the side from which light is emitted.

  Not only the VA liquid crystal but also the TN liquid crystal and OCB (Optically Compensated Birefringence) liquid crystal can be effectively compensated by appropriately setting the relationship between the first and second optical axes. Can do.

  As described above, according to the liquid crystal device of the present invention, the first and second optical compensation elements can compensate for the phase difference generated in the liquid crystal. Therefore, a high-definition image having a relatively high contrast can be displayed and can be suitable for downsizing.

  In one aspect of the liquid crystal device of the present invention, the first and second optical axes intersect each other when viewed from the normal direction of the one plane.

  According to this aspect, the first optical axis and the second optical axis are sandwiched between the pair of substrates as compared to the case where they are parallel to each other when viewed from the normal direction of one plane along the pair of substrates. Further, the anisotropy of the refractive index of the entire liquid crystal and the first and second optical compensation elements can be reduced.

  In the aspect in which the first and second optical axes intersect with each other, the first and second optical axes may be configured to be orthogonal to each other when viewed from the normal direction of the one plane.

  In this case, the anisotropy of the entire refractive index of the liquid crystal sandwiched between the pair of substrates and the first and second optical compensation elements can be further reduced.

  In another aspect of the liquid crystal device of the present invention, the liquid crystal is a vertical alignment type liquid crystal.

  According to this aspect, the liquid crystal molecules are vertically aligned, and the pretilt imparted to the liquid crystal molecules by both of the alignment films provided on each of the pair of substrates is the same. Therefore, the phase difference of the light generated due to the long axis of the liquid crystal molecules provided with the pretilt by the two alignment films being inclined with respect to the normal line of the one plane is expressed by the first and second optical components. The compensation element can effectively compensate.

  In the aspect in which the liquid crystal is a vertical alignment type liquid crystal, the angle formed by the first optical axis with respect to the normal line of the one plane is such that the major axis of the liquid crystal molecules provided with the pretilt is the one plane. You may comprise so that it may be equal to the pretilt angle which is an angle made with respect to the normal line.

  In this case, the angle at which the first optical axis is inclined with respect to the normal of one plane along the pair of substrates (that is, the angle formed by the first optical axis and the normal) is Since it is equal to the pretilt angle, it is possible to effectively compensate for the phase difference of the light caused by the long axis of the liquid crystal molecules being inclined with respect to the normal of the one plane. Here, “equal to the pretilt angle” means that the phase difference of the light caused by the tilt of the major axis of the liquid crystal molecules is within a range sufficient to compensate to the extent allowed by the product specifications. This means that it should be close to the pretilt angle, that is, includes the case where it is substantially equal to the pretilt angle in addition to the case where it is literally equal to the pretilt angle.

  In another aspect of the liquid crystal device of the present invention, the first optical compensation element includes a positive uniaxial crystal and is formed by polishing so that the optical axis is inclined with respect to one surface. It consists of a plate.

  According to this aspect, the first optical compensation element can be configured as a crystal plate having an optical axis inclined with respect to one plane along the pair of substrates, relatively easily. Therefore, it is not necessary to dispose the first optical compensation element with respect to the one plane, and the liquid crystal device can be downsized. Here, “one surface” according to the present invention means one main surface in a flat crystal plate having two main surfaces. In the case of using quartz as the positive uniaxial crystal, for example, it is cheaper than the case of using sapphire or the like, and the processing of the crystal plate is easy. Thus, cost reduction can be achieved.

  A crystal plate whose optical axis is inclined with respect to one surface is formed by, for example, cutting a crystal by tilting it at a predetermined angle with respect to the optical axis of the crystal and polishing it to a predetermined thickness. Good. The surface opposite to the one surface is preferably polished so as to be parallel to the one surface.

  In another aspect of the liquid crystal device of the present invention, the liquid crystal device further includes a third optical compensation element having a negative uniaxial property and having a third optical axis along the normal direction of the one plane as the optical axis.

  According to this aspect, the third optical compensation element is composed of, for example, a negative uniaxial retardation plate (that is, a C plate), and the third optical axis that is the optical axis is a single one along the pair of substrates. The pair of substrates are opposed to each other so as to be along the normal direction of the plane. Therefore, the phase difference of light generated by passing through the liquid crystal can be more reliably compensated. In other words, the liquid crystal sandwiched between the pair of substrates by the first, second, and third optical compensation elements, and the refractive index anisotropy of the entire first, second, and third optical compensation elements are further increased. It can be made even smaller. That is, the refractive index ellipsoid showing the anisotropy of the entire refractive index of the liquid crystal and the first, second, and third optical compensation elements can be made closer to a sphere. Accordingly, it is possible to more reliably prevent a decrease in contrast and a reduction in viewing angle.

  In the aspect including the third optical compensation element described above, the third optical compensation element may be made of an inorganic material.

  In this case, the third optical compensation element is formed of an inorganic material using, for example, a vapor deposition method. Therefore, the third optical compensation element undergoes little or no deterioration due to ultraviolet rays or the like. Accordingly, the light resistance or durability of the third optical compensation element can be improved, and deterioration of quality over time in the display image can be reduced or prevented.

  In the aspect including the third optical compensation element described above, the optical system further includes a microlens array disposed on a light incident side with respect to the pair of substrates, and the third optical compensation element is disposed on the pair of substrates. It may be provided on the light emitting side.

  In this case, since the third optical compensation element can be arranged on the side from which the light is emitted with respect to the microlens array, the third phase difference generated when the light bent by the microlens array passes through the liquid crystal. Compensation can be ensured by the optical compensation element. In other words, the adverse effect on the phase shift of light by the microlens array can be almost or completely eliminated.

  In another aspect of the liquid crystal device of the present invention, the first and second optical compensation elements are provided on the light emitting side with respect to the pair of substrates.

  According to this aspect, since the first and second optical compensation elements can be arranged on the side where light is emitted with respect to the microlens array, for example, the light bent by the microlens array passes through the liquid crystal. The generated phase difference can be reliably compensated by the first and second optical compensation elements. In other words, the adverse effect on the phase shift of light by the microlens array can be almost or completely eliminated.

  In order to solve the above problems, an electronic apparatus according to the present invention includes the above-described liquid crystal device according to the present invention (including various aspects thereof).

  According to the electronic apparatus of the present invention, since the above-described liquid crystal device of the present invention is provided, the phase difference generated in the light passing through the liquid crystal layer can be compensated, and high contrast can be realized. . As a result, a projection display device, television, mobile phone, electronic notebook, word processor, viewfinder type or monitor direct view type video tape recorder, workstation, video phone, Various electronic devices such as a POS terminal and a touch panel can be realized.

  The operation and other advantages of the present invention will become apparent from the best mode for carrying out the invention described below.

Hereinafter, embodiments of the present invention will be described with reference to the drawings. In the following embodiments, a TFT active matrix driving type liquid crystal device with a built-in driving circuit, which is an example of the liquid crystal device of the present invention, is taken as an example.
<First Embodiment>
First, a liquid crystal panel constituting the liquid crystal device according to the first embodiment will be described with reference to FIGS. The liquid crystal device according to the present embodiment is a liquid crystal device used for a light valve of a projection display device such as a liquid crystal projector. FIG. 1 is a plan view showing the configuration of the liquid crystal panel according to this embodiment, and FIG. 2 is a cross-sectional view taken along the line HH ′ of FIG. In FIG. 1 and FIG. 2, only the liquid crystal panel is shown without the optical compensation element described later in detail.

  1 and 2, in a liquid crystal panel 100 constituting the liquid crystal device according to the present embodiment, a TFT array substrate 10 and an opposing substrate 20 as an example of “a pair of substrates” according to the present invention are arranged to face each other. . A liquid crystal layer 50 is sealed between the TFT array substrate 10 and the counter substrate 20, and the TFT array substrate 10 and the counter substrate 20 are provided with a sealing material 52 provided in a seal region positioned around the image display region 10a. Are bonded to each other.

  In FIG. 1, a light-shielding frame light-shielding film 53 that defines the frame area of the image display region 10a is provided on the counter substrate 20 side in parallel with the inside of the seal region where the sealing material 52 is disposed. A data line driving circuit 101 and an external circuit connection terminal 102 are provided along one side of the TFT array substrate 10 in a region located outside the sealing region in which the sealing material 52 is disposed in the peripheral region. The sampling circuit 7 is provided so as to be covered with the frame light shielding film 53 on the inner side of the seal region along the one side. The scanning line driving circuit 104 is provided so as to be covered with the frame light-shielding film 53 inside the seal region along two sides adjacent to the one side. On the TFT array substrate 10, vertical conduction terminals 106 for connecting the two substrates with the vertical conduction material 107 are arranged in regions facing the four corner portions of the counter substrate 20. Thus, electrical conduction can be established between the TFT array substrate 10 and the counter substrate 20.

  On the TFT array substrate 10, a lead wiring 90 is formed for electrically connecting the external circuit connection terminal 102 to the data line driving circuit 101, the scanning line driving circuit 104, the vertical conduction terminal 106, and the like. .

  In FIG. 2, on the TFT array substrate 10, a laminated structure in which wirings such as pixel switching TFTs (Thin Film Transistors), scanning lines, and data lines are formed. In the image display area 10a, pixel electrodes 9a are provided in a matrix on the upper layer of wiring such as pixel switching TFTs, scanning lines, and data lines. An alignment film 16 is formed on the pixel electrode 9a. On the other hand, a light shielding film 23 is formed on the surface of the counter substrate 20 facing the TFT array substrate 10. The light shielding film 23 is formed of, for example, a light shielding metal film or the like, and is patterned, for example, in a lattice shape in the image display region 10a on the counter substrate 20. On the light shielding film 23, a counter electrode 21 made of a transparent material such as ITO (Indium Tin Oxide) is formed in a solid shape so as to face the plurality of pixel electrodes 9a. An alignment film 22 is formed on the counter electrode 21. The liquid crystal layer 50 includes liquid crystal molecules having negative dielectric anisotropy. Therefore, the liquid crystal device according to this embodiment is a liquid crystal device in which the alignment of liquid crystal molecules is controlled in the vertical alignment (VA) mode. The liquid crystal device according to the present invention is not limited to a liquid crystal device having liquid crystal molecules having a negative dielectric anisotropy, and includes, for example, a liquid crystal in which one or several types of nematic liquid crystals are mixed. It may be a liquid crystal device that takes a predetermined alignment state between the pair of alignment films 16 and 22.

  Although not shown here, a surface of the counter substrate 20 opposite to the side facing the liquid crystal layer 50 (that is, the surface on which incident light is incident) is provided on a microlens array described later with reference to FIG. 400 is provided.

  Although not shown here, in addition to the data line driving circuit 101, the scanning line driving circuit 104, etc., on the TFT array substrate 10, in order to inspect the quality, defects, etc. of the liquid crystal device during manufacturing or at the time of shipment. An inspection circuit, an inspection pattern, or the like may be formed.

  Next, the first and second optical compensation elements included in the liquid crystal device according to the present embodiment will be described with reference to FIGS.

  First, the arrangement positions of the first and second optical compensation elements will be described with reference to FIG. FIG. 3 is a cross-sectional view of the liquid crystal device according to this embodiment, showing the configuration of the liquid crystal device according to this embodiment and the incident direction of incident light. In the following drawings, detailed members of the liquid crystal panel 100 shown in FIGS. 1 and 2 are omitted as appropriate, and only directly related members are shown. 3 shows the TFT array substrate 10 and the counter substrate 20 shown in FIG. 2 upside down for convenience of explanation.

  3, the liquid crystal device according to the present embodiment includes a liquid crystal panel 100, a microlens array 400, a first optical compensation element 210, and a second optical compensation element 220, and is sandwiched between polarizing plates 300a and 300b. Is arranged.

  The microlens array 400 is a microlens array plate in which a microlens corresponding to each pixel of the liquid crystal panel 100 is formed, and is provided between the polarizing plate 300 a on the incident side and the liquid crystal panel 100. With the microlens array 400, incident light can be collected in units of pixels, and the substantial aperture ratio of the liquid crystal panel 100 can be improved. That is, the microlens array 400 can improve light use efficiency, brightness, and color purity in the liquid crystal panel 100.

  The first optical compensation element 210 and the second optical compensation element 220 are provided between the output-side polarizing plate 300 b and the liquid crystal panel 100. The first optical compensation element 210 and the second optical compensation element 220 are attached to the TFT array substrate 10 in this order. Each of the first optical compensation element 210 and the second optical compensation element 220 may be configured integrally with the support body by providing a support body separately from the TFT array substrate 10.

  Next, the configuration of the first and second optical compensation elements will be described with reference to FIGS. FIG. 4 is a perspective view of the first and second optical compensation elements according to the present embodiment, and FIG. 5 is a conceptual diagram showing a method for forming the first optical compensation element according to the present embodiment. In addition, in addition to the first and second optical compensation elements, FIG. 4 conceptually shows the state of the liquid crystal molecules in the liquid crystal panel 100 when no voltage is applied. Further, in FIG. 4, for convenience of explanation, the angle α and the angle θ1 are illustrated to be larger than actual.

  In FIG. 4, the liquid crystal molecules 501 in the liquid crystal layer 50 have a predetermined orientation (see FIG. 2) in the plane of the counter substrate 20 (or the TFT array substrate 10) by the alignment films 22 and 16 (see FIG. 2) in a state where no voltage is applied. 4, a pretilt that rises by a predetermined angle from the in-plane in the tilt direction 20r of the liquid crystal in the vicinity of the alignment film 22 (that is, the direction along the tilt direction 10r of the liquid crystal in the vicinity of the alignment film 16) is the azimuth along the X direction The orientation is inclined by a pretilt angle α with respect to the normal line of the counter substrate 20 (or the TFT array substrate 10).

  The first optical compensation element 210 is made of a crystal plate formed of a positive uniaxial crystal such as quartz. The optical axis 211 of the first optical compensation element 210 is in a direction different from the direction in which the major axis of the liquid crystal molecules 501 is inclined with respect to the surface of the first optical compensation element 210 facing the liquid crystal panel 100 (ie, the XY plane). Inclined. That is, for example, when viewed in one plane orthogonal to the TFT array substrate 10 along the tilt direction 10r, the optical axis 211 is a liquid crystal molecule 501 with respect to the normal line (that is, the Z axis) of the TFT array substrate 10. The major axis is inclined by an angle θ1 in a direction different from the direction in which the major axis is inclined. Therefore, the assumed refractive index ellipsoid 212 is also inclined by an angle θ1 with respect to the normal line of the TFT array substrate 10 in a direction different from the direction in which the major axis of the liquid crystal molecules 501 is inclined. The slow axis 213 of the first optical compensation element 210 is along the tilt direction 10r of the liquid crystal near the alignment film 16 (that is, the tilt direction 20r of the liquid crystal near the alignment film 22 or the X direction). More specifically, the first optical axis 211 is symmetric with respect to the major axis of the liquid crystal molecules 501 to which the pretilt is applied with respect to the surface of the first optical compensation element 210 facing the liquid crystal panel 100 (that is, the XY plane). The angle θ1 is set to be almost equal to the pretilt angle α or completely in practice.

  As shown in FIG. 5 (a), in the present embodiment, the positive uniaxial crystal 2b is moved by an angle θ2 with respect to the optical axis L (here, the angle θ2 is a difference between 90 degrees and the angle θ1). The first optical compensation element 210 as shown in FIG. 5B is formed by cutting along the inclined cutting lines q1 and q2 and polishing to have a predetermined thickness d. According to such a forming method, for example, when the angle θ2 is set to 85 degrees, the first optical compensation element 210 having an angle θ1 of 5 degrees (that is, an angle almost equal to the pretilt angle α) can be easily formed. . As the polishing, for example, various polishing techniques such as CMP (Chemical Mechanical Polishing) can be applied.

  In FIG. 4 again, the second optical compensation element 220 is made of, for example, a film-like organic compound that functions as a positive uniaxial retardation plate (ie, an A plate). The optical axis 221 of the second optical compensation element 220 is along the surface (that is, the XY plane) facing the liquid crystal panel 100 of the first optical compensation element 210, and the normal direction of the facing surface (that is, the Z direction). ) Intersect with the optical axis 211 of the first optical compensation element 210 at an angle of, for example, 80 to 90 degrees. In other words, the optical axis 221 of the second optical compensation element 220 is along the XY plane and forms an angle of, for example, 80 degrees to 90 degrees with the major axis of the liquid crystal molecules 510 to which the pretilt is applied as viewed from the Z direction. Cross each other. Accordingly, the assumed refractive index ellipsoid 222 is also along the XY plane, and the slow axis 223 of the second optical compensation element 220 is, for example, 80 degrees with the slow axis 213 of the first optical compensation element 210 when viewed from the Z direction. From each other at an angle of 90 degrees.

  Next, the operation of the liquid crystal device including the first and second optical compensation elements configured as described above will be described with reference to FIG. 6 in addition to FIG. 3 and FIG. FIG. 6 is a conceptual diagram conceptually showing an assumed refractive index ellipsoid obtained by synthesizing the assumed refractive index ellipsoid of the liquid crystal layer and the assumed refractive index ellipsoid of the first optical compensation element.

  In FIG. 3, when the liquid crystal device according to this embodiment operates, incident light first enters the polarizing plate 300a on the incident side. In the polarizing plate 300a, only light that ideally vibrates in an angular direction of 45 ° with respect to a predetermined direction (in this embodiment, the tilt direction 20r of the liquid crystal in the vicinity of the alignment film 22 included in the counter substrate 20, that is, the X direction). Can pass. That is, incident light becomes linearly polarized light by passing through the polarizing plate 300a. Incident light that has passed through the polarizing plate 300 a passes through the microlens array 400 and the counter substrate 20 and enters the liquid crystal layer 50.

  In FIG. 4, the liquid crystal molecules 501 in the liquid crystal layer 50 are in one direction (that is, X direction) along the tilt direction 10 r with respect to the normal direction (that is, the Z direction) of the TFT array substrate 10 when no voltage is applied. It is oriented with a pretilt angle α inclined in the positive direction of the axis. Therefore, as shown in FIG. 6, the assumed refractive index ellipsoid 501e indicating the anisotropy of the refractive index of the entire liquid crystal layer 50 also has a tilt direction 10r with respect to the normal direction (that is, the Z direction) of the TFT array substrate 10. Is tilted by a pretilt angle α in one direction along the axis (that is, the positive direction of the X axis). Therefore, if no measures are taken, the light incident on the liquid crystal layer 50 causes a phase difference due to the assumed refractive index ellipsoid 501e of the liquid crystal layer 50 being inclined by the pretilt angle α. The light that has passed through the liquid crystal layer 50 enters the output-side polarizing plate 300b in a state of being out of phase. Note that the polarizing plate 300b can pass only light that vibrates in a direction perpendicular to the polarization direction of the polarizing plate 300a.

  However, in FIGS. 4 and 6, the liquid crystal device according to the present embodiment includes the first optical compensation element 210 and the second optical compensation element 220, so that the assumed refractive index in which the incident light is tilted by the pretilt angle α. A phase difference of light generated by passing through the liquid crystal layer 50 having the ellipsoid 501e can be compensated. In other words, the first optical compensation element 210 and the second optical compensation element 220 can reduce the total refractive index anisotropy of the liquid crystal layer 50, the first optical compensation element 210, and the second optical compensation element 220. . That is, the refractive index ellipsoid showing the anisotropy of the entire refractive index of the liquid crystal layer 50, the first optical compensation element 210, and the second optical compensation element 220 can be made close to a sphere.

  That is, the first optical element having the assumed refractive index ellipsoid 212 inclined to the opposite side of the assumed refractive index ellipsoid 501e by the angle θ1 with respect to the liquid crystal layer 50 having the assumed refractive index ellipsoid 501e inclined by the pretilt angle α. By arranging the compensation element 210, the assumed refractive index ellipsoid 292 of the entire liquid crystal layer 50 and the first optical compensation element 210 is approximated to a biaxial refractive index ellipsoid. For this reason, the first optical compensation element 210 can compensate, for example, a phase difference caused when light incident along the tilt direction 10r (or 20r) passes through the liquid crystal layer 50.

  Furthermore, a second optical compensation element 220 having an assumed refractive index ellipsoid 222 that intersects with the assumed refractive indices ellipsoids 501e and 212 when viewed from the Z direction is disposed with respect to the liquid crystal layer 50 and the first optical compensation element 210. Thus, the assumed refractive index ellipsoid of the entire liquid crystal layer 50, the first optical compensation element 210, and the second optical compensation element 220 is approximated to a spherical refractive index ellipsoid. Therefore, the phase difference generated in the liquid crystal layer 50 can be compensated by the first optical compensation element 210 and the second optical compensation element 220.

  By performing such compensation, it is possible to prevent the light that has passed through the liquid crystal layer 50 from entering the output-side polarizing plate 300b in a state of being out of phase. Accordingly, for example, in the polarizing plate 300b on the emission side, the possibility that light that should not be allowed to leak is reduced, and it is possible to prevent a decrease in contrast and a reduction in viewing angle.

  Furthermore, the first optical compensation element 210 and the second optical compensation element 220 compensate for the phase difference of light generated in the liquid crystal layer 50 without being inclined with respect to the TFT array substrate 10 and the counter substrate 20. Can do. Therefore, it can be suitable for downsizing the liquid crystal device and the like.

  It is desirable that the retardation (Δn · d) of the first optical compensation element 210 in the Z direction is almost or completely equal to the retardation of the liquid crystal layer 50 in the Z direction. In this case, the effect of compensating for the phase difference generated in the liquid crystal layer 50 can be further enhanced. However, even if the retardation of the first optical compensation element 210 in the Z direction is almost or completely equal to the retardation of the liquid crystal layer 50 in the Z direction, the retardation of the first optical compensation element 210 in the Z direction and the Z of the liquid crystal layer 50 are the same. The effect of compensating for the phase difference generated in the liquid crystal layer 50 can be increased correspondingly according to the difference from the retardation with respect to the direction. That is, for example, when the retardation of the liquid crystal layer 50 with respect to the Z direction is 250 nm, the retardation of the first optical compensation element 210 is desirably 250 nm, but if the retardation is within the range of 150 nm to 300 m, for example, The effect of compensating for the phase difference generated in the layer 50 can be reliably increased.

  In FIG. 4, in this embodiment, in particular, the optical axis 211 of the first optical compensation element 210 and the optical axis 221 of the second optical compensation element 220 are viewed from the normal direction (that is, the Z direction) of the TFT array substrate 10. For example, they intersect each other at an angle of 80 to 90 degrees. Therefore, if the optical axis 211 and the optical axis 221 are parallel to each other when viewed from the Z direction, the entire refraction of the liquid crystal layer 50, the first optical compensation element 210, and the second optical compensation element 220 is considered. The rate anisotropy can be reduced. Note that the optical axis 211 and the optical axis 221 are desirably orthogonal to each other when viewed from the Z direction. In this case, the anisotropy of the entire refractive index of the liquid crystal layer 50, the first optical compensation element 210, and the second optical compensation element 220 can be further reduced.

  Furthermore, in this embodiment, in particular, the angle θ1 formed by the optical axis 211 of the first optical compensation element 210 with respect to the normal line (ie, the Z axis) of the TFT array substrate 10 is the length of the liquid crystal molecules 501 to which the pretilt is applied. The axis is almost or practically equal to the pretilt angle α formed with respect to the normal of the TFT array substrate 10. Therefore, it is possible to effectively compensate for the phase difference of light caused by the long axis of the liquid crystal molecules 501 being inclined by the pretilt angle α with respect to the normal line of the TFT array substrate 10.

  In addition, in the present embodiment, in particular, the first optical compensation element 210 and the second optical compensation element 220 are provided on the side from which light is emitted with respect to the liquid crystal panel 100. That is, the first optical compensation element 210 and the second optical compensation element 220 are disposed on the side from which light is emitted with respect to the microlens array 400. Accordingly, the first optical compensation element 210 and the second optical compensation element 220 can reliably compensate for the phase difference generated when the light bent by the microlens array 400 passes through the liquid crystal layer 50. In other words, the adverse effect on the phase difference of light by the microlens array 400 can be almost or completely eliminated. The first optical compensation element 210 and the second optical compensation element 220 may be provided on the side where light enters the liquid crystal panel 100 (in other words, the side where light enters the liquid crystal layer 50). . Also in this case, an effect of compensating for the phase difference of light can be obtained.

As described above, according to the liquid crystal device according to the present embodiment, the first optical compensation element 210 and the second optical compensation element 220 can compensate for the phase difference generated in the liquid crystal layer 50. Therefore, a high-definition image having a relatively high contrast can be displayed and can be suitable for downsizing.
Second Embodiment
A liquid crystal device according to a second embodiment will be described with reference to FIGS. FIG. 7 is a sectional view having the same concept as in FIG. 3 in the second embodiment. FIG. 8 is a perspective view having the same concept as in FIG. 4 in the second embodiment. 7 and 8, the same reference numerals are given to the same components as the components according to the first embodiment shown in FIGS. 1 to 6, and the description thereof will be omitted as appropriate.

  In FIG. 7, the liquid crystal device according to the second embodiment is different from the liquid crystal device according to the first embodiment described above in that it further includes a third optical compensation element 230. Other points are the same as those in the first embodiment described above. The configuration is almost the same as that of the liquid crystal device according to the embodiment.

  In FIG. 7, the liquid crystal device according to the second embodiment includes a liquid crystal panel 100, a microlens array 400, a first optical compensation element 210, a second optical compensation element 220, and a third optical compensation element 230, and a polarizing plate. It arrange | positions so that it may be inserted | pinched between 300a and 300b.

  The third optical compensation element 230 is provided between the output-side polarizing plate 300b and the liquid crystal panel 100 (more specifically, between the first optical compensation element 210 and the second optical compensation element 220). . The first optical compensation element 210, the second optical compensation element 220, and the third optical compensation element 230 are arranged on the TFT array substrate 10 in the order of the first optical compensation element 210, the third optical compensation element 230, and the second optical compensation element 220. It is pasted. Note that the first optical compensation element 210, the second optical compensation element 220, and the third optical compensation element 230 are in the other order (for example, the first optical compensation element 210, the second optical compensation element 220, and the third optical compensation element 230). In this order) may be attached to the TFT array substrate 10. Further, the first optical compensation element 210, the second optical compensation element 220, and the third optical compensation element 230 may be configured integrally with a support provided separately from the TFT array substrate 10.

  In FIG. 8, the third optical compensation element 230 is composed of a negative uniaxial retardation plate (ie, C plate). The optical axis 231 of the third optical compensation element 230 has a normal direction (that is, the XY plane or the substrate surface of the TFT array substrate 10) facing the first optical compensation element 210 of the third optical compensation element 230 (that is, the substrate surface of the TFT array substrate 10). Z direction). Therefore, the assumed refractive index ellipsoid 232 is also along the normal direction (that is, the Z direction).

  The third optical compensation element 230 configured as described above can more reliably compensate for the phase difference of light generated by passing through the liquid crystal layer 50. In other words, the liquid crystal layer 50, the first optical compensation element 210, the second optical compensation element 220, and the third optical compensation element 230 are formed by the first optical compensation element 210, the second optical compensation element 220, and the third optical compensation element 230. The anisotropy of the overall refractive index can be further reduced. That is, the refractive index ellipsoid showing the anisotropy of the entire refractive index of the liquid crystal layer 50, the first optical compensation element 210, the second optical compensation element 220, and the third optical compensation element 230 can be made closer to a sphere. it can. Accordingly, it is possible to more reliably prevent a decrease in contrast and a reduction in viewing angle.

  Particularly in the present embodiment, the third optical compensation element 230 is formed of an inorganic material using, for example, a vapor deposition method. Therefore, the third optical compensation element 230 undergoes little or no deterioration due to ultraviolet rays or the like. Therefore, the light resistance or durability of the third optical compensation element 230 can be improved, and deterioration of quality over time in the display image can be reduced or prevented.

  Next, an example of the measurement result of the contrast (that is, the contrast ratio) of the display image displayed by the liquid crystal device according to the first and second embodiments will be described with reference to FIG. FIG. 9 is an example of the measurement result of the contrast of the display image by the liquid crystal device according to the first and second embodiments. In FIG. 9, an example of the measurement result of the contrast of the display image by the liquid crystal device according to the first and second embodiments is shown together with an example of the measurement result of the contrast of the display image by the liquid crystal device according to the comparative example. In this measurement, the first optical compensation element 210 is formed of quartz as a positive uniaxial crystal.

  In FIG. 9, the data D0a is a liquid crystal device configured by a single liquid crystal panel 100 (that is, any of the first optical compensation element 210, the second optical compensation element 220, and the third optical compensation element 230 with respect to the liquid crystal panel 100). The contrast of the display image by the liquid crystal device which is not provided is shown. The data D0b indicates the contrast of a display image by a liquid crystal device in which the first optical compensation element 210 is provided for the liquid crystal panel 100 and neither the second optical compensation element 220 nor the third optical compensation element 230 is provided. Show. In this measurement, the thickness d of the first optical compensation element 210 is changed as a parameter to 25, 30 and 35 um. The data D1a is the contrast of the display image by the liquid crystal device in which the second optical compensation element 220 is provided for the liquid crystal panel 100 and neither the first optical compensation element 210 nor the third optical compensation element 230 is provided. Show. The data D1b is a liquid crystal device in which the first optical compensation element 210 and the second optical compensation element 220 are provided for the liquid crystal panel 100 and the third optical compensation element 230 is not provided, that is, the first embodiment described above. The contrast of the display image by the liquid crystal device which concerns on a form is shown. The data D2a indicates the contrast of the display image by the liquid crystal device in which the second optical compensation element 220 and the third optical compensation element 230 are provided for the liquid crystal panel 100, and the first optical compensation element 210 is not provided. Yes. The data D2b is a display image of the liquid crystal device in which the first optical compensation element 210, the second optical compensation element 220, and the third optical compensation element 230 are provided on the liquid crystal panel 100, that is, the liquid crystal device according to the second embodiment. Contrast is shown.

  In FIG. 9, when only the first optical compensation element 210 is provided for the liquid crystal panel 100 indicated by the data D0b, the contrast is low as compared with the case of the liquid crystal panel 100 alone indicated by the data D0a. However, when the first optical compensation element 210 and the second optical compensation element 220 are provided for the liquid crystal panel 100 indicated by the data D1b, that is, in the case of the liquid crystal device according to the first embodiment, the liquid crystal indicated by the data D0a. Compared with the panel 100 alone, the contrast is high. Furthermore, in the case of the liquid crystal device according to the first embodiment indicated by the data D1b, the contrast is higher than when only the second optical compensation element 220 is provided for the liquid crystal panel 100 indicated by the data D1a. Therefore, by providing not only the first optical compensation element 210 but also both the first optical compensation element 210 and the second optical compensation element for the liquid crystal panel 100, the contrast can be effectively increased. That is, as shown in the data D1b, the liquid crystal device according to the first embodiment can display a high-quality image with high contrast.

In addition, in FIG. 9, when the second optical compensation element 220 and the third optical compensation element 230 are provided for the liquid crystal panel 100 indicated by the data D2a, the second optical compensation element is provided for the liquid crystal panel 100 indicated by the data D1a. Compared with the case where the compensation element 220 is provided, the contrast is almost the same. That is, the contrast can hardly be increased by providing the third optical compensation element 230 for the liquid crystal device provided with the second optical compensation element 220 for the liquid crystal panel 100. However, when the first optical compensation element 210, the second optical compensation element 220, and the third optical compensation element 230 are provided for the liquid crystal panel 100 shown in the data D2b, that is, in the case of the liquid crystal device according to the second embodiment. Is higher in contrast than the case where the second optical compensation element 220 is provided for the liquid crystal panel 100 shown in the data D1a. Therefore, not only the second optical compensation element 220 and the third optical compensation element 230 but also the three optical compensation elements of the first optical compensation element 210, the second optical compensation element 220, and the third optical compensation element 230 with respect to the liquid crystal panel 100. By providing this, it is possible to increase the contrast more effectively. That is, as shown in the data D2b, the liquid crystal device according to the second embodiment can display a high-quality image with high contrast.
<Electronic equipment>
Next, an example of an electronic device using the liquid crystal device described above will be described with reference to FIGS. The electronic apparatus according to the present embodiment is a projector that uses the liquid crystal device described above as a light valve.

  FIG. 10 is a plan view showing a configuration example of the projector. As shown in FIG. 10, a projector 1100 includes a lamp unit 1102 made of a white light source such as a halogen lamp. The projection light emitted from the lamp unit 1102 is separated into three primary colors of RGB by four mirrors 1106 and two dichroic mirrors 1108 arranged in the light guide 1104, and serves as a light valve corresponding to each primary color. The light enters the liquid crystal panels 1110R, 1110B, and 1110G.

  The configurations of the liquid crystal panels 1110R, 1110B, and 1110G have the same configuration as that of the above-described liquid crystal device, and are driven by R, G, and B primary color signals supplied from the image signal processing circuit, respectively. The light modulated by these liquid crystal panels enters the dichroic prism 1112 from three directions. In this dichroic prism 1112, R and B light is refracted at 90 degrees, while G light travels straight. Accordingly, as a result of the synthesis of the images of the respective colors, a color image is projected onto the screen or the like via the projection lens 1114.

  Here, paying attention to the display images by the liquid crystal panels 1110R, 1110B, and 1110G, the display images by the liquid crystal panels 1110R and 1110B need to be horizontally reversed with respect to the display images by the liquid crystal panel 1110G.

  Since light corresponding to the primary colors R, G, and B is incident on the liquid crystal panels 1110R, 1110B, and 1110G by the dichroic mirror 1108, it is not necessary to provide a color filter.

  Since such a projector includes the above-described liquid crystal device, the phase difference generated in the light passing through the liquid crystal layer is compensated, a high-contrast image can be displayed, and the size can be further reduced.

  In addition to the electronic apparatus described with reference to FIG. 10, a mobile personal computer, a mobile phone, a liquid crystal television, a viewfinder type or a monitor direct view type video tape recorder, a car navigation device, a pager, and an electronic notebook , Calculators, word processors, workstations, videophones, POS terminals, devices with touch panels, and the like. Needless to say, the present invention can be applied to these various electronic devices.

  The present invention is not limited to the above-described embodiments, and can be appropriately changed without departing from the gist or concept of the invention that can be read from the claims and the entire specification. An electronic device including the liquid crystal device is also included in the technical scope of the present invention.

It is a top view of the liquid crystal panel which concerns on 1st Embodiment. It is HH 'sectional drawing of FIG. 1 is a cross-sectional view of a liquid crystal device according to a first embodiment. It is a perspective view of the 1st and 2nd optical compensation element concerning a 1st embodiment. It is a conceptual diagram which shows the formation method of the 1st optical compensation element which concerns on 1st Embodiment. It is a conceptual diagram which shows notionally the assumed refractive index ellipsoid by which the assumed refractive index ellipsoid of a liquid crystal layer and the assumed refractive index ellipsoid of a 1st optical compensation element are synthesize | combined. It is sectional drawing with the same meaning as FIG. 3 in 2nd Embodiment. It is a perspective view of the same meaning as FIG. 4 in 2nd Embodiment. It is an example of the measurement result of the contrast of the display image by the liquid crystal device which concerns on 1st and 2nd embodiment. It is a top view which shows the structure of the projector which is an example of the electronic device of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 10 ... TFT array substrate, 10r ... Tilt direction, 16 ... Alignment film, 20 ... Counter substrate, 20r ... Tilt direction, 22 ... Alignment film, 50 ... Liquid crystal layer, 100 ... Liquid crystal panel, 210 ... First optical compensation element, 220 ... 2nd optical compensation element, 230 ... 3rd optical compensation element, 211, 221, 231 ... Optical axis, 212, 222, 232 ... Expected refractive index ellipsoid, 213, 223 ... Slow axis, 300a, 300b ... Polarizing plate , 400 ... micro lens array

Claims (11)

A pair of substrates disposed opposite to each other and each having an alignment film;
A liquid crystal composed of liquid crystal molecules sandwiched between the pair of substrates and provided with a pretilt by the alignment film;
A first optical axis that has positive uniaxiality and is inclined in a direction different from the direction in which the major axis of the liquid crystal molecules provided with the pretilt is inclined with respect to one plane along the pair of substrates. A first optical compensation element having
A liquid crystal device comprising: a second optical compensation element having positive uniaxiality and having, as an optical axis, a second optical axis along the one plane.   2. The liquid crystal device according to claim 1, wherein the first and second optical axes intersect each other when viewed from a normal direction of the one plane.   The liquid crystal device according to claim 2, wherein the first and second optical axes are orthogonal to each other when viewed from a normal direction of the one plane.   The liquid crystal device according to claim 1, wherein the liquid crystal is a vertical alignment type liquid crystal.   The angle formed by the first optical axis with respect to the normal line of the one plane is equal to the pretilt angle that is the angle formed by the long axis of the liquid crystal molecules provided with the pretilt with respect to the normal line of the one plane. The liquid crystal device according to claim 4.   2. The first optical compensation element includes a crystal plate that includes a positive uniaxial crystal and is polished so that an optical axis is inclined with respect to one surface. 6. The liquid crystal device according to any one of items 1 to 5.   7. The third optical compensation element according to claim 1, further comprising a third optical compensation element having negative uniaxiality and having a third optical axis along the normal of the one plane as an optical axis. The liquid crystal device described.   The liquid crystal device according to claim 7, wherein the third optical compensation element is made of an inorganic material. A microlens array disposed on the light incident side of the pair of substrates;
The liquid crystal device according to claim 7, wherein the third optical compensation element is provided on a side from which light is emitted with respect to the pair of substrates.   10. The liquid crystal device according to claim 1, wherein the first and second optical compensation elements are provided on a light emitting side with respect to the pair of substrates.   An electronic apparatus comprising the liquid crystal device according to any one of claims 1 to 10.

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