JP2005301315A - Liquid crystal display device and optical anisotropic device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To improve viewing angle dependency characteristics, especially, a contrast ratio and viewing angle dependency of display colors. <P>SOLUTION: In a liquid crystal display element has at least two polarizers 1 and 4, a driving liquid crystal cell having liquid crystal 3e sandwiched between two substrates 3a and 3b, and optical anisotropic layers, which are characterized in that at lest one or more optical anisotropic layers differing in sign of optical anisotropy of an optical anisotropic unit are combined and arranged and angles of respective optical axes are not constant along the thickness. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an optically compensated liquid crystal display element and an optically anisotropic element for optical compensation.

  Since the liquid crystal display element has the great advantage of being thin, lightweight and low power consumption, it is not only used as a display for watches, calculators, Japanese word processors, personal computers, etc., but also a new concept that actively utilizes the advantages of liquid crystal display elements. It is also used in other products. In particular, liquid crystal display elements used in personal computers and the like have a large area and large capacity display, and a display surface of 10 inches diagonal and 640 × 480 pixels has become mainstream. The display methods used in this class of liquid crystal display elements can be roughly classified into two types. One is a simple matrix system and the other is an active matrix system.

  The simple matrix method has a simple structure in which liquid crystal is sandwiched between two glass substrates with comb-shaped transparent electrodes. Therefore, high performance is required for the liquid crystal in the simple matrix system. Before explaining the performance required for this liquid crystal, the display principle of the liquid crystal display element will be explained. In the display of the liquid crystal display element, the voltage applied to the liquid crystal is changed to change the direction of the liquid crystal molecules. In general, a large voltage difference is required to obtain a large contrast ratio. However, in order to realize a display of 640 × 480 pixels, the voltage difference between dark and light is as small as about 1V, and a large change in the state of liquid crystal molecules is required only by 1V difference. In order to achieve this, it was studied by many researchers for a long time, and in 1985, it was made by a research group of Schaefer et al. According to their research, by increasing the twist angle (twist angle) of the alignment of liquid crystal molecules, the change in alignment changes sensitively to voltage, and in order to obtain a stable alignment with a large twist angle, liquid crystal It was found that the numerator needs to have a certain inclination. Since this research report, orientation technology to realize this has been actively performed and successfully put into practical use.

  In order to realize a display having an array of 640 × 480 pixels, generally, the twist angle is required to be 180 ° or more. Since the twist angle is large as described above, this liquid crystal is called a super twist nematic (STN). However, the initial STN display had a yellow background and a green character display, and was not a monochrome display. This is because the twist angle is large, and as a means for eliminating such display coloring, a second liquid crystal cell in which the alignment of the liquid crystal layer is twisted in the opposite direction is disposed between the polarizing plate and the liquid crystal cell. It is reported in Patent Document 1 that monochrome display can be realized by the above.

  The principle of black-and-white conversion is that light transmitted through a first liquid crystal cell in which liquid crystal molecules are arranged in a twisted manner and causing optical rotation dispersion is transmitted through the first liquid crystal cell and the second liquid crystal cell of the target structure. The optical rotation dispersion has been eliminated. As a result, coloring due to optical rotatory dispersion of light is eliminated, and monochrome display can be realized. In order to perform such conversion accurately, the second liquid crystal cell, which is an optical compensator, has substantially the same retardation value as that of the first liquid crystal cell, and the twist directions are opposite to each other. It is necessary to configure so that the orientation directions of the liquid crystal molecules closest to each other are orthogonal.

  As other means, various methods using an optically anisotropic film instead of the above-described second liquid crystal cell have been proposed. This is a method of providing almost the same function as the second liquid crystal cell by laminating several optically anisotropic films on the liquid crystal cell.

  With the optical compensation described above, monochrome display is possible even on STN displays, and color display with higher added value can also be realized by combining with color filters. However, since the simple multiplex method is based on time-division driving based on the voltage averaging method, if the number of scanning lines is increased to increase the display capacity, the voltage value when light is blocked and the light is transmitted. There is an essential problem that the voltage difference during the process is remarkably reduced, and as a result, the contrast ratio becomes small and the response speed of the liquid crystal becomes slow. In addition, such a conventional technique is observed as a phenomenon in which the display image appears to be reversed depending on the azimuth and angle when viewing the liquid crystal display element, or the display image is not visible at all, or the display is colored. When a liquid crystal display element having a high level is realized, it becomes a big problem.

  On the other hand, since the active matrix system includes a switching element formed of a thin film transistor or a diode for each display pixel, an arbitrary voltage ratio can be set in the liquid crystal layer of each pixel regardless of the number of scanning lines. Therefore, special performance as in the case of the simple matrix system is not required for the liquid crystal. There is no need to increase the twist angle as in STN, and it is 90 °.

  A liquid crystal cell (TN) having a twist angle of 90 ° has a small twist angle, and therefore has no optical rotation dispersion, and an achromatic and high-contrast display can be obtained. Also, the response to voltage is faster than STN. By combining the active matrix method and TN, a liquid crystal display element having a large display capacity, a high contrast ratio, and a high response speed can be realized. Further, since there is a switching element for each pixel, an intermediate voltage can be applied, thereby enabling halftone display. Further, by combining with a color filter, full color display can be easily realized.

  However, even in the case of the active matrix method, it is not so much in the case of binary display, but when displaying a halftone, the display image may be reversed depending on the viewing direction, or the display image may not be visible at all, Alternatively, it is observed as a phenomenon that the display is colored, and it becomes a big problem when realizing a liquid crystal display element with higher display quality.

As a means for reducing the viewing angle dependency of such a display, in Patent Document 2, a liquid crystal cell and a birefringent layer having a negative optical anisotropy in the thickness direction are arranged between two polarizing plates. It is disclosed. On the other hand, Patent Document 3 discloses disposing a birefringent layer made of a liquid crystal compound (or polymer liquid crystal) exhibiting a cholesteric liquid crystal phase having a product of a helical pitch length and a refractive index of 400 nm or less on a liquid crystal cell. . These two proposals are considered only in the case of a liquid crystal cell having a vertical alignment (liquid crystal molecules aligned vertically with respect to an alignment substrate), and a liquid crystal cell having a twisted arrangement such as a TN type or STN type. In case not considered. Japanese Patent Application No. 3-121578 (Patent Document 4) proposes controlling the viewing angle of a liquid crystal display element with an optical compensation element having a twist angle of 360 ° or more and having a tilt angle. In this case, the effect of widening the viewing angle is not yet sufficient. There is also a technical report (Non-Patent Document 1) that improves the viewing angle characteristics of the TN-LCD by arranging the optical axes of negative optically anisotropic materials obliquely, but cannot compensate for all orientations. .
Japanese Patent Publication No. 63-53528 Japanese Patent Laid-Open No. Sho 62-21423 JP-A-3-67219 JP-A-4-349429 Proceedings of the 21st Liquid Crystal Symposium, p.298-301

  The basic display principle of the liquid crystal display element described above is that the direction of the liquid crystal molecules is changed by the voltage applied to the liquid crystal to cause an optical change in the liquid crystal cell.

  Therefore, when the liquid crystal display element is tilted, the orientation of the liquid crystal molecules appears to change, and particularly when a delicate halftone is displayed, the inclination of the liquid crystal molecules is changed finely, which is more remarkable.

  Due to the viewing angle dependence of the appearance of the liquid crystal molecules, it is observed as a phenomenon that the display image appears reversed or cannot be identified at all, especially when full color display is performed in combination with a color filter. As a result, the reproducibility of the display image is significantly reduced, which is a serious problem.

  The present invention solves the above inconveniences, and provides a liquid crystal display element having improved contrast ratio and viewing angle dependency of display color, and an optical anisotropic element used therefor.

  The present invention resides in a liquid crystal display element having the following characteristics.

  The present invention includes a driving liquid crystal cell in which a liquid crystal is sandwiched between two substrates between at least two polarizing plates, and at least optical anisotropic layers having different signs of optical anisotropy of optical anisotropy units. A liquid crystal display element having an optically anisotropic layer is obtained, wherein one or more layers are combined and each optical axis angle is not constant with respect to the thickness direction.

  Furthermore, the present invention provides a driving liquid crystal cell having a liquid crystal sandwiched between two substrates between at least two polarizing plates, and different optically anisotropic layers having different optical anisotropy signs. A liquid crystal display element having an optically anisotropic layer, wherein the liquid crystal display element has an optically anisotropic layer, wherein the liquid crystal display element is arranged in combination of at least one layer and has optical rotation in a direction inclined from a normal direction of the combined optically anisotropic layer To get.

  The optical axis of the optical anisotropy unit of the optical anisotropic layer whose optical anisotropy unit is positive is continuous in the optical anisotropic layer thickness direction with respect to the optical anisotropic layer thickness direction. It is preferable to have changed to.

  The optical axis of the optical anisotropy unit of the optical anisotropic layer continuously changes in the optical anisotropic layer thickness direction with respect to the optical anisotropic layer thickness direction, and the direction of the optical axis is the same direction It is preferable that they are arranged.

  A combination of an optically anisotropic layer having a negative optical anisotropy of the optically anisotropic unit and an optically anisotropic layer having an optically anisotropic unit having a positive optical anisotropy It is preferable to arrange on both sides of the cell.

  It is preferable that an optically anisotropic layer composed of the optically anisotropic unit having the negative optical anisotropy is disposed adjacent to the driving liquid crystal cell.

  The optical axis of the optical anisotropic layer in which the optical axis of the optical anisotropic unit is continuously changing with respect to the thickness direction of the optical anisotropic layer, and the surface with the smaller tilt angle of the optical axis of the optical anisotropic layer It is preferable that the liquid crystal cell is disposed adjacent to the driving liquid crystal cell.

  The optical axis orientation of the optically anisotropic layer in which the optical anisotropy unit has a positive sign, and the optical axis of the optically anisotropic layer in which the optical anisotropy unit has a negative sign. It is preferable that the azimuths are arranged perpendicular to each other.

  Furthermore, in the above liquid crystal display element, the optical axis of the optical anisotropy unit of the optical anisotropic layer in which the optical anisotropy of the optical anisotropy unit is positive is optically anisotropic with respect to the thickness direction of the optical anisotropic layer. An optically anisotropic element characterized by continuously changing in the thickness direction of the active layer is disposed.

  ADVANTAGE OF THE INVENTION According to this invention, the contrast of a liquid crystal display element and the viewing angle characteristic of a display color can be improved, and the liquid crystal display element of the high quality display which is excellent in visibility can be provided. The present invention can also be used when it is desired to change the viewing angle only in a certain direction under certain conditions, such as car navigation.

  The present invention solves the above-described problems, and simultaneously reduces the contrast ratio of the liquid crystal display element, the brightness at the time of gradation display, and the viewing angle dependency of the display color, or a specific contrast ratio of the liquid crystal display element. It is intended to control the region where the image is obtained to have a certain direction and viewing angle. The operation will be described below.

  In liquid crystal display elements such as TN and STN, the polarization state of light propagating in the liquid crystal display element differs depending on whether light is incident on the display surface of the liquid crystal display element perpendicularly or obliquely. This difference directly reflects the inversion phenomenon and coloring phenomenon of the display image. Such a phenomenon is observed when the viewing angle of the liquid crystal display element is greatly tilted from the normal to the display surface. In particular, the liquid crystal of a liquid crystal cell (hereinafter referred to as a driving cell) having means for applying a voltage to the liquid crystal layer. This is noticeable in pixels where a voltage is applied to the layer.

  FIG. 35 is a diagram showing the angle dependence of display luminance when tilting from 0 ° to 60 ° in the left-right direction from the display surface normal of the conventional TN liquid crystal display element. The levels 1 to 8 are indicated by the gradation numbers of gradation display, and the voltages applied to the liquid crystal cells are sequentially different. Level 1 is 0V and level 8 is 5V applied to the liquid crystal cell. For example, in the case of the upward orientation, the luminance gradually increases as the angle (viewing angle) tilted from the normal line of the display surface of the display increases from 0 ° (front) to 60 °. In the actual display, the display color is observed to become whitish (clear white). On the other hand, regarding the lower position, when the viewing angle is tilted from the front (0 °) to 60 °, the luminance decreases contrary to the upper direction. This phenomenon is observed in the actual display image as a dark display color (blackout). In the front, the brightest display level 1 and the lower gradation level 2 are reversed in magnitude at an upward viewing angle of 35 °, and the actual display image is reversed like a photographic film negative. Observed (inverted). Ideally, the transmittance does not change even if the viewing angle changes for any gradation level. However, as shown in FIG. 35, the actual viewing angle characteristic of TN is relatively good in the left-right direction characteristic but poor in the vertical direction characteristic.

  Such a phenomenon occurs because the viewing angle characteristic of the liquid crystal display element is caused by the polarization state being different depending on the incident angle of the light incident on the liquid crystal display element as described above. This will be explained in detail.

  FIG. 3 shows the operating principle of the TN liquid crystal display element. FIG. 3A shows the alignment state of the liquid crystal molecules LM in the TN cell when no voltage is applied to the electrodes 3c and 3d. When the voltage V is not applied, the liquid crystal molecules are arranged in a continuously twisted manner with the liquid crystal molecules parallel to the thickness direction of the liquid crystal layer (in the figure, the Z-axis direction) substantially parallel to the substrate. ing. When light Li polarized by the polarizer Pi is incident on this arrangement, the plane of polarization rotates according to the twisted arrangement of the liquid crystal molecules LM, and when exiting the liquid crystal layer, the plane of polarization enters the plane of polarization before entering the liquid crystal layer. In contrast, the liquid crystal layer rotates by the twist angle. When the transmission axis Pot of the analyzer Po is aligned with the rotated direction, the transmitted light Lo is obtained.

  FIG. 3B shows the alignment state of the liquid crystal molecules in the TN cell when a voltage is applied. By applying the voltage V, the liquid crystal molecules LM rise, and the liquid crystal molecules LMc near the center of the cell are tilted more than the liquid crystal molecules LMs near the electrode. The reason why the inclination of the liquid crystal molecules LMs in the vicinity of the electrodes 3c and 3d is small is that there is an alignment regulating force (necessary for aligning the liquid crystal) at the electrode-liquid crystal layer interface. The inclination of the liquid crystal molecules increases according to the magnitude of the voltage V, and at the same time, the twisted arrangement is distorted. When the voltage is further increased, the twist is finally released. When polarized light Li is incident in such a state, the polarization plane Lp does not rotate and proceeds through the liquid crystal layer because it is not twisted, and the polarization plane is the same as it was before entering the liquid crystal layer when exiting the liquid crystal layer. Therefore, since the transmission axis Pot of the analyzer Po is orthogonal to the polarization plane Lp, polarized light cannot be transmitted. In order to display halftones, the voltage applied to the liquid crystal layer is set smaller than this, the twisted alignment of the alignment is left slightly, and the polarization plane exiting the liquid crystal layer is rotated slightly to obtain intermediate transmitted light. Get.

  Based on the above principle, transmitted light is controlled using distortion of the twisted arrangement. Next, a phenomenon with respect to light in an oblique direction will be described.

  FIG. 4 is a diagram illustrating a state in which light is incident obliquely on the molecular arrangement state when displaying a halftone. FIG. 4A is a perspective view showing the relationship between the molecular arrangement state LMint at the time of halftone display and the directions L and U of the two incident lights, and in order to make this easier to understand, a diagram viewed from the Y-axis direction is shown. 4 (b) and 4 (c). Here, the normal direction of the substrate of the driving liquid crystal cell is represented by the Z axis, and the substrate surface is represented by the XY axis. The liquid crystal molecules LMs near the electrodes 3c and 3d on the upper and lower substrates are arranged with a slight inclination. This tilt is called a pretilt angle. In general, the pretilt indicates a tilt of liquid crystal molecules at the substrate-liquid crystal interface, and the tilt angle is referred to as a pretilt angle α0. When no voltage is applied, the upper and lower substrates 3a and 3b are inclined at the same angle. If there is a predetermined tilt (pretilt) over the region to which the voltage V is applied, the tilt direction when the voltage is applied is aligned with the pretilt direction, so that uniform display can be achieved. If there is no pretilt, the direction in which the liquid crystal molecules are tilted varies when a voltage is applied, and a defect line is generated at the boundary between regions having different tilt directions, which causes a significant deterioration in display quality. Accordingly, in order to obtain a uniform display, the pretilt is indispensable, and the angle is generally 1 ° to 6 ° in the TN mode.

  Therefore, as shown in FIGS. 4B and 4C, the alignment state of the liquid crystal molecules is asymmetric with respect to the Y axis, particularly when a halftone is displayed. With respect to the L polarized light incident obliquely in the direction from the + X axis to the + Z axis in FIG. 4B, as shown in LM-L in FIG. 5, the alignment is not tilted in the liquid crystal molecules LM (as if no voltage is applied). The polarization plane can be rotated greatly. As a result, the transmitted light becomes larger than the intensity of the outgoing light with respect to the incident light from the front (light parallel to the Z axis). On the other hand, as shown in LM-U of FIG. 5, for the polarized light U incident from the opposite direction of FIG. 4C (obliquely from the −X axis to the + Z axis), the arrangement is as follows. The liquid crystal molecules LM are in a largely inclined state (as if they were in an arrangement state where a larger voltage is applied), and the polarization plane cannot be rotated. As a result, the transmitted light becomes smaller than the intensity of the outgoing light with respect to the incident light from the front (light parallel to the Z axis). 35 corresponds to the upper direction in FIG. 35 and the lower direction in FIG. 4 corresponds to the lower direction in FIG.

  As described above, the orientation dependency of transmitted light in a halftone is due to the asymmetry of the alignment of liquid crystal molecules. This asymmetry of the arrangement causes the rotation (optical rotation) angle of the polarization plane to be different depending on the direction in which light is incident, resulting in a change in transmittance. In the TN type liquid crystal display element, it can be said that optical rotation occurs in the upper direction and optical rotation tends to decrease in the lower direction. Therefore, in order to improve this, the viewing angle dependency of the liquid crystal display element can be improved by adding an optical anisotropic element in which the optical rotation decreases in the upper direction and the optical rotation occurs in the lower position.

  First, the characteristics required for the optical anisotropic element are summarized as follows. The characteristics required for the optical anisotropic element are the upper direction and the lower direction with respect to the driving liquid crystal cell in which any viewing angle characteristic in the vertical direction is not good. This means that the rotation direction of the optical rotation is reversed.

  Furthermore, secondly, it is required to have a characteristic that improves the viewing angle characteristic with respect to other directions.

  The present invention provides an optical anisotropic element having such characteristics and a liquid crystal display element including the optical anisotropic element.

  The configuration of the optical anisotropic element according to the present invention will be described.

  The optical anisotropic element in the present invention is a film, plate, or sheet-like planar body having optical anisotropy, and has a thickness. In an element having a negative optical anisotropy, as shown in FIG. 9, the refractive index of the Z axis, that is, the optical axis perpendicular to the XY axis direction constituting the plane is small.

  A thin layer having optical anisotropy in which the optical axis is directed in a certain direction is defined as an optical anisotropy unit, and the optical anisotropic element has a configuration in which the units are stacked in multiple layers. Including those where the boundaries of each layer are not separated.

  Therefore, the representative configuration of the present invention is that at least one polarizing plate, a driving liquid crystal cell in which liquid crystal is sandwiched between two substrates, and at least one optical element in which a plurality of optical anisotropy units are continuous in the thickness direction. The optical anisotropic element has a negative optical anisotropy of the optical anisotropy unit with respect to the thickness direction, and an angle of each optical axis is in the thickness direction. On the other hand, the liquid crystal display element is arranged so as to be not constant and to have a minimum optical rotation in the thickness direction.

  For example, as one example, a hybrid in which the optical axis is substantially parallel to one surface from one surface of the element to the other surface, and gradually changes in inclination to the other surface and is substantially perpendicular to the other surface. An optically anisotropic element having a structure can be raised.

  In order to further improve the viewing angle dependency, the present invention provides an optical anisotropic element combination in which at least one optical anisotropic layer having different optical anisotropy signs of optical anisotropy units is combined. is there. These anisotropic elements are characterized in that the optical rotatory power in the direction inclined from the normal direction of the combined optically anisotropic layer is larger than the optical rotatory power in the normal direction, for example, positive and negative optical Used as a pair of anisotropic bodies. For example, these are arranged on both sides of the driving liquid crystal cell.

  First, the characteristics required for the optical anisotropic element are summarized as follows. The characteristic required for the optical anisotropic element is that the rotation direction of the optical rotation is reversed between the upper direction and the lower direction.

  FIG. 6 is a view showing the arrangement of the optical axes of the optical anisotropic element of the present invention. FIG. 6A is a cross-sectional view of the optical anisotropic element of the present invention. An optical anisotropy unit LD constituting an anisotropic element is shown, and an elliptical short axis normal corresponds to the optical axis OL. The unit may be a single molecule or may be composed of a plurality of molecules formed by stacking.

  The inclination of the major axis continuously changes from the lower substrate 2d to the upper substrate 2a, and is substantially perpendicular to the substrate surface in the vicinity of the lower substrate 2d and substantially parallel in the vicinity of the upper substrate 2a (hybrid orientation). . An example of this arrangement as seen from above is shown in FIG. The arrow in the figure indicates the direction of the optical axis. FIG. 6C is an arrangement diagram when observed obliquely from the Z axis. The tilt direction is indicated by XYZ axes in the figure. A view seen from the opposite oblique direction is shown in FIG. As can be seen from FIGS. 6 (c) and 6 (d), when the array of FIG. 6 (a) is observed obliquely from the Z-axis, in FIG. ) Is twisted to the right of the opposite. By the optically anisotropic elements arranged obliquely in this way, the above-mentioned characteristic that “the rotation direction of the optical rotation is opposite between the upper direction and the lower direction” can be realized.

  The optical anisotropic element as the optical anisotropic element of the present invention can be regarded as a structure in which optically anisotropic material layer units are optically laminated in the thickness direction. Each layer unit has an optical axis, and the inclination of these optical axes changes continuously or stepwise.

  Furthermore, the optical axis arrangement having the minimum optical rotation in the thickness direction is taken.

  Next, how such an optically anisotropic element is combined with a drive cell to obtain a good compensation effect will be described.

  FIG. 7A is a diagram showing the drive cell shown in FIGS. 3, 4 and 5 with an arrow added as in FIG. 6, where the symbol Lip is the polarization axis of the incident light and the symbol Lop is the polarization of the emitted light. Represents an axis. FIG. 7A shows an optical anisotropic element, and FIG. 7B shows a drive cell (TN) to which a voltage corresponding to a halftone is applied, as viewed from the Z axis. (C) is a diagram showing the molecular arrangement of each optical anisotropic material layer constituting the optical anisotropic element when viewed from the Z-axis to the + X-axis side, in which linearly polarized light is incident. The optical rotation state was shown. In this direction, the optical anisotropic element has the property of rotating the polarization plane of incident light in the left direction (left rotation ability). (D) shows the arrangement state of the driving cells when viewed from the same direction as (c). The liquid crystal molecules are inclined obliquely because a voltage equivalent to halftone (a voltage slightly higher than the critical voltage (threshold voltage) at which the liquid crystal operates) is applied, and the major axis of the liquid crystal molecules is viewed from this direction. An orientation portion is produced in which the length in the direction and the length in the minor axis direction are substantially the same. Therefore, the incident polarized light is transmitted without rotating much, and the direction of the polarization axis Lop of the emitted light is almost the same as the polarization axis Lip of the incident light. This is a cause of display abnormality called “blackout” that darkens the display. In this case, if the polarization is rotated counterclockwise (the optical rotation is increased), this can be improved. For this purpose, the optical anisotropic element shown in FIG. The optically anisotropic element shown in FIG. 2C has a left optical rotation ability, and compensates for the optical rotation that is insufficient with the drive cell.

  On the other hand, the reverse orientation will be described with reference to FIGS. (E) and (f) show the arrangement of the optical axes when the optical anisotropic element in FIG. (A) is observed from the -X axis from the Z-axis direction. Has the property of turning right (right rotation). FIG. (F) is a state in which a halftone voltage is applied, as in FIG. (D). From this direction, although the liquid crystal molecules are actually inclined, it does not appear to be inclined, As a result, a large optical rotation is achieved. This causes a display abnormality called “white spot” in which the display becomes brighter than necessary. If right rotation that suppresses counterclockwise rotation is applied, excess rotation can be eliminated and “white spot” is improved. The optically anisotropic element shown in FIG. 4E has a right-handed rotation ability, and the characteristics of the element can be improved by combining it with a drive cell.

  As described above, the principle of field expansion is explained by taking as an example an optically anisotropic element having a hybrid orientation in which the optical rotation in the direction inclined with respect to the normal to the surface of the optical anisotropic element is larger than the optical rotation in the direction of the normal. However, optical anisotropic elements that are twisted and aligned in a hybrid orientation and optical anisotropic elements that are tilt-aligned uniformly between the upper and lower substrates can obtain characteristics similar to those of hybrid anisotropic optical elements. It can be selected according to the specifications. Further, although TN has been described as an example, since the same principle can be applied to STN, it can be used as means for improving the viewing angle of STN.

  The optically anisotropic body exhibiting negative optical anisotropy has the characteristic that the optical rotation in the oblique direction of the element is larger than the front direction (Z axis) by the hybrid arrangement as described above. ”And“ white spot ”display abnormalities are greatly improved. Further, in the above description, the case where the optical anisotropy of the optical anisotropy unit constituting the optical anisotropic element is a negative sign is shown, but the case where the optical rotation property in the oblique direction is larger than that in the front direction. It goes without saying that the same effect is exhibited even when the optical anisotropy is positive.

  In the above description, the hybrid arrangement is shown. However, it is not only such an arrangement that the optical rotation in the oblique direction is larger than that in the front direction, but optical anisotropy when viewed from the element normal direction. Even if the optical axis of the optical anisotropy unit constituting the element is twisted in the direction of the element surface, the direction of the optical axis at the both end faces of the optical anisotropic element is the same, and the internal arrangement is continuously or stepwise changed For example, the same effect can be obtained with a bend array or a spray array in which two hybrid arrays are stacked. Further, the retardation value of the optical anisotropic element is preferably smaller than the retardation value of the driving liquid crystal cell, and is a value near the retardation value of the driving liquid crystal cell when a voltage indicating halftone is applied. Is more desirable. However, this value depends on product specifications and mass productivity, and is not necessarily limited to this. Further, the arrangement and arrangement of the optical anisotropic elements vary depending on the product specifications, mass productivity, cost, and the like depending on the optical anisotropic elements used in combination and the number of the optical anisotropic elements.

  In addition, when combining viewing angle characteristics with product specifications, optical anisotropic elements with biaxial optical axes, such as those used in STN, and optical anisotropics with positive optical anisotropy in the optical anisotropy unit. Even when used in combination with an optical anisotropic element in which the body is arranged in various ways, or an optical anisotropic element in which the optical anisotropy in which the optical anisotropy of the optical anisotropic material is biaxial is arranged in various ways, etc. Needless to say, an advantageous effect can be obtained.

  Substances exhibiting negative optical anisotropy include C18H6 (OCOC7H15) 6 with an ester bond on the triphenylene nucleus and C6 (OCOCmH2m + 1) 6 with a benzene nucleus, and these are called discotic liquid crystals. These may be used in a crystal phase so that a desired arrangement is formed in a temperature region showing a liquid crystal phase and the arrangement does not change. Further, if the optical anisotropic element is manufactured so that the temperature range showing the liquid crystal phase is set to the operating temperature range of the liquid crystal module and the arrangement can be controlled by an electric field or the like, the viewing angle characteristics can be voltage controlled.

  In the present invention, since the optically anisotropic substance constituting the optically anisotropic element is a negative sign having a different optical anisotropy optical axis inclination, a better viewing angle improving effect is exhibited. Next, the principle of improving the viewing angle characteristics when using a liquid crystal having a negative optical anisotropy will be described.

  A state where a voltage higher than the threshold voltage is applied to the driving liquid crystal cell is represented by a three-dimensional refractive index ellipsoid as shown in FIG. The Z axis is the thickness direction of the liquid crystal cell, and the XY plane corresponds to the substrate surface of the liquid crystal cell. The birefringence phenomenon is a method on the center point of the index ellipsoid RA of the line connecting the observation point when the center point of the index ellipsoid RA is viewed from a certain direction and the center point of the index ellipsoid RA. The line surface is indicated by the shape of an elliptical cut surface formed when the refractive index ellipsoid RA is cut (herein referred to as a refractive index body in a two-dimensional plane). If the difference between the major axis and minor axis length of the refractive index body in the two-dimensional plane corresponds to the phase difference between ordinary light and extraordinary light, and the transmission axes of the polarizing plates sandwiching the liquid crystal cell are orthogonal to each other, When the phase difference is zero, the transmitted light of the liquid crystal cell is blocked, and when the phase difference is not zero, transmitted light corresponding to the phase difference and the wavelength of the incident light is generated.

  When light is incident perpendicularly to the substrate surface of the liquid crystal cell (when the liquid crystal cell is viewed from the front), the refractive index body RA4 in the two-dimensional plane is a circle, and the phase difference between ordinary light and extraordinary light is zero. However, when light is incident from a direction RA1 tilted from the substrate surface of the liquid crystal cell, the refractive index ellipsoid RA5 becomes an ellipse, causing a phase difference between ordinary light and extraordinary light. The polarization states of are different.

  When the angle of viewing the refractive index ellipsoid RA in FIG. 8, ie, the viewing angle RA3 is increased, the refractive index body RA5 in the two-dimensional plane of the visual axis RA1 increases in the length direction of nRA1, and from the direction of the visual axis RA1. Larger transmitted light is observed when viewed. Ideally, it is desirable that the shape of the refractive index body in the two-dimensional plane does not change when the viewing angle is changed in any orientation.

  In such optical compensation, a disk-shaped refractive index ellipsoid RB as shown in FIG. 9 is arranged on the Z axis of the refractive index ellipsoid RA in FIG. 8 (that is, adjacent to the upper or lower portion of the liquid crystal cell). Can be realized. With such a configuration, when the viewing angle RA3 is increased, the refractive index body RA in the two-dimensional plane of the refractive index ellipsoid RA increases in the length direction of nRA1, whereas the refractive index ellipsoid. The refractive index of RB in the length direction of nRA2 increases, and as a result, the combined refractive index body in the two-dimensional plane becomes a circle, and the refractive index ellipsoid RA can be optically compensated, and the viewing angle characteristics Will improve.

  In an actual liquid crystal display element, the refractive index ellipsoid of the driving liquid crystal cell has a long axis of the ellipse that is not perpendicular to the display surface but slightly tilted as shown in FIG. Therefore, the refractive index ellipsoid RB of the optical anisotropic element shown in FIG. 9 that compensates for this is preferably such that the minor axis of the disk shape is inclined accordingly.

  Actually, the refractive index ellipsoid as shown in FIG. 9 is an optically anisotropic element composed of an optically anisotropic material layer in which the optical axis is continuously twisted, or a refractive index in the in-plane direction rather than the thickness direction. This can be realized by using a smaller material.

  Hereinafter, a method for realizing an optically anisotropic element having a negative optical anisotropy with an optically anisotropic element composed of an optically anisotropic material layer having an optical axis continuously twisted will be described.

  In general, a driving liquid crystal cell performs display by actively changing the polarization direction of light in a visible wavelength region (generally, a region from 380 nm to 750 nm) according to a voltage applied to the liquid crystal cell.

  On the other hand, in the case of the optically anisotropic element for optical compensation of the present invention, the optical axis of the optically anisotropic material layer is continuously twisted, so that optical rotation may occur depending on the optical conditions of the optically anisotropic element. . Here, the optical rotation indicates the property that the vibration direction of the light turns to the left or right around the traveling direction as the light travels in the medium. When the retardation value of an optically anisotropic element whose optical axis is continuously twisted is constant, and the twist pitch of the optical axis is long, the light rotates its polarization plane according to the twist of the optical axis. When the pitch is short, the light cannot follow the twist of the optical axis, and the optical rotation phenomenon does not occur. If the optical rotatory power of the optical anisotropic element is large, the polarization plane of the light transmitted through the element is changed, resulting in a decrease in the contrast ratio, and in some cases the polarization plane changes variously depending on the wavelength of the light, There arises a problem that light transmitted through the optical anisotropic element is colored.

  Therefore, at least the optical rotatory power with respect to visible light of the optically anisotropic element needs to be smaller than the optical rotatory power with respect to visible light of the driving liquid crystal cell. The optical rotation depends largely on the wavelength of light transmitted through the medium and the medium through which the light is transmitted. The magnitude of the optical rotation is represented by the degree of change in the retardation value of the medium with respect to the change in the optical axis.

Therefore, the optical rotation of the liquid crystal cell for driving is determined by the difference between the refractive index no for the ordinary light and the refractive index ne for the extraordinary light of the liquid crystal of the driving liquid crystal cell by Δn1 (= ne−no: refractive index anisotropy), If the thickness of the liquid crystal layer is d1 and the twisted angle (twist angle) of the liquid crystal layer is T1, Δn1 · d1 / T1 = R1 / T1 [1.1] where R1 = Δn1 · d1 (retardation value)
It can be expressed as

  Similarly, the optical rotatory power of the compensating optical anisotropic element is determined by the refractive index anisotropy of the optical anisotropic material layer of the compensating optical anisotropic element Δn2 and the thickness of the laminated optical anisotropic material layer. If the total twist angle of the optical axis of the optically anisotropic material layer is T2, Δn 2 · d 2 / T 2 = R 2 / T 2 [1.2] where R 2 = Δn 2 · d 2.

  Therefore, the magnitude relationship between the optical rotatory power of the compensating optical anisotropic element and the optical rotatory power of the driving liquid crystal cell is (R1 / T1)> (R2 / T2) [1.3] from the equations [1.1] and [1.2].

  The propagation of light in an optical anisotropic element in which the optical axis of the optically anisotropic material layer is continuously twisted can be expressed by a parameter represented by the following equation (C. Z. Van Doorn, Physics Letters 42A, 7 (1973)).

f = λ / (p × Δn) [1.4] where λ is the wavelength of light in the vacuum (visible wavelength range)
p is the twist pitch length of the optical axis (p = d / T)
In the case of f << 1, the polarization plane of the light in the optical anisotropic element changes according to the twist angle of the optical axis and has optical rotation. As described above, it is desirable that the optical anisotropic element has a small optical rotation, and the optical anisotropic element needs to satisfy the condition of f >> 1. Therefore, the optical anisotropy needs to satisfy p × Δn <λ [1.5] from the equation [1.4].

  By the way, a liquid crystal having a very large twist angle, that is, a liquid crystal having a short helical pitch is generally referred to as a cholesteric liquid crystal. The product of the length p of the helical pitch of the liquid crystal and the average refractive index n of the cholesteric liquid crystal is n × p. When the value is in the visible wavelength range (depending on conditions, the short wavelength end is 360 nm to 400 nm and the long wavelength end is 760 nm to 830 nm), selective scattering occurs (JL Fergason; Molecular Crystals. 1. 293 (1966) ). Such a phenomenon is not only observed in the cholesteric liquid crystal cell, but can also occur in an optical anisotropic element in which the optical axis of the optical anisotropic body is continuously twisted. When selective scattering occurs, a coloring phenomenon of the optical anisotropic element occurs and the display color changes. Therefore, the coloring phenomenon can be prevented if the product n × p of the average refractive index n of the optically anisotropic material layer forming the optical anisotropic element and the twist pitch p of the optical axis is out of the visible wavelength range.

  Optical anisotropic elements are made by laminating retardation films with optical anisotropy produced by stretching polymer films, twisted liquid crystal cells, and twisted polymer liquid crystals. It can be realized by the thin film. In this case, for example, since it is obtained by applying this polymer layer to at least one of the substrates of the driving liquid crystal cell, it is easy to manufacture and a more desirable liquid crystal display element can be obtained. For example, a polymer copolymer having polysiloxane as the main chain and biphenylbenzoate and cholesteryl groups in an appropriate ratio in the side chain can be used.

  Even if these optical anisotropic elements are produced not only between the polarizing plate and the substrate but also in a cell inside the substrate, the same effect can be obtained. For example, polymer liquid crystal may be applied to the inside of the substrate, and an alignment film may be formed thereon.

  However, if one of the same or the same type is used to achieve the characteristics required for an optically anisotropic element, “the direction of rotation of the optical rotation is reversed between the upper and lower positions”, the thickness increases and the retardation value increases. There is a drawback that the display color changes too much. This is because the light transmitted through the optical anisotropic element has a birefringence effect along with the optical rotation, the linearly polarized light becomes elliptically polarized light, and the ellipticity varies depending on the wavelength of the light. Is born.

  Therefore, in order to eliminate the desired optical rotation and coloring, an optical anisotropic element composed of optical anisotropy units having different signs of optical anisotropy is replaced with a positive and negative sign. It has been found that both required performances can be obtained by combining elements.

  Next, a positive optical anisotropic element combined with a negative optical anisotropic element will be described.

  As in the case of the negative optical anisotropic element, a case will be described in which a characteristic in which the rotation direction of the optical rotation is opposite between the upper direction and the lower direction is obtained.

  FIG. 24 is a diagram showing an arrangement state of optical axes of the optical anisotropic element of the present invention, and FIG. 24A is a cross-sectional view of the optical anisotropic element of the embodiment of the present invention, which is indicated by an ellipse. Indicates an optically anisotropic body LD constituting an optically anisotropic element, and the major axis of the ellipse corresponds to the optical axis OL. The inclination of the major axis continuously changes from the electrode on the lower substrate 2b to the electrode on the upper substrate 2a, and is substantially parallel to the substrate surface in the vicinity of the lower substrate electrode and substantially vertical in the vicinity of the upper substrate electrode. Yes (hybrid orientation). An example of this arrangement as seen from above is shown in FIG. The arrow in the ellipse in the figure indicates the direction of the optical axis. The directions of the optical axes in the layer are on the same plane, that is, they are aligned on a single axis. FIG. 24C is an arrangement diagram when observed obliquely from the Z axis. The tilt direction is indicated by XYZ axes in the figure. A view seen from the opposite oblique direction is shown in FIG. As can be seen from FIGS. 24C and 24D, when the array of FIG. 24A is observed obliquely from the Z-axis, in FIG. ) Is arranged with the reverse right twist. By the optically anisotropic elements arranged obliquely in this way, the above-described property that “the rotation direction of the optical rotation is opposite between the upper direction and the lower direction” can be realized.

  Next, how such an optical anisotropic element is combined with a driving liquid crystal cell to obtain a good compensation effect will be described next.

  FIG. 25A is a diagram showing the driving liquid crystal cell shown in FIGS. 3, 4 and 5 with an arrow added as in FIG. 24. Reference symbol Lip is the polarization axis of incident light, and reference symbol Lop is outgoing light. Represents the polarization axis. FIG. 25A shows an optical anisotropic element, and FIG. 25B shows a driving liquid crystal cell (TN) to which a voltage corresponding to a halftone is applied as viewed from the Z axis. (C) is the figure which showed the arrangement | sequence of the optical axis of an optical anisotropic element when it sees from the Z-axis to the + X side, and showed the optical rotation state when linearly polarized light injects into the figure. In this direction, the optical anisotropic element has the property of rotating the polarization plane of incident light in the left direction (left rotation ability). (D) shows the arrangement of the driving liquid crystal cells when viewed from the same direction as (c). The liquid crystal molecules are tilted obliquely because a voltage equivalent to halftone (a voltage slightly higher than the critical voltage (threshold voltage) at which the liquid crystal operates) is applied, and when viewed from this direction, the long axis of the liquid crystal molecules An orientation portion is produced in which the length in the direction and the length in the minor axis direction are substantially the same. Therefore, the incident polarized light is transmitted without rotating much, and the direction of the polarization axis Lop of the emitted light is almost the same as the polarization axis Lip of the incident light. This is the cause of the display abnormality called “blackout” that darkens the display. In this case, if the polarized light is rotated counterclockwise (increases the optical rotation ability), this is improved. For this purpose, the optically anisotropic element shown in FIG. The optical anisotropic element shown in FIG. 3C has a left optical rotation ability, and the driving liquid crystal cell compensates for the insufficient optical rotation.

  On the other hand, the opposite direction will be described with reference to FIGS. (E) and (f) show the arrangement of the optical axes when the optical anisotropic element in FIG. (A) is observed from the -X axis from the Z-axis direction. It has the property of turning to the right (right rotation ability). FIG. (F) shows a state in which a halftone voltage is applied as in FIG. (D). From this direction, although the liquid crystal molecules are actually inclined, it does not appear to be inclined. There is a great optical rotation. This causes a display anomaly called “white spot” that makes the display brighter than necessary, and if the right rotation that suppresses counterclockwise rotation is applied, the extra rotation can be eliminated and “white spot” is improved. . The optically anisotropic element shown in FIG. 4E has a right-handed rotation ability, and characteristics can be improved by combining this with a driving liquid crystal cell.

  As described above, the principle of the viewing angle expansion is exemplified by the optical orientation element of the hybrid orientation in which the optical rotation in the direction inclined with respect to the normal of the surface of the optical anisotropic element is larger than the optical rotation in the direction of the normal. Although explained, an optical anisotropic element that is twist-aligned by hybrid alignment and an optical anisotropic element that is tilt-aligned uniformly between the upper and lower substrates can obtain characteristics similar to those of the hybrid alignment optical anisotropic element. Can be selected according to the design specifications. Further, although TN has been described as an example, the same principle can be applied to STN or hybrid aligned (Hybrid Aligned Nematic), and therefore, it can be used as means for improving the viewing angle of STN.

  From the above, the optically anisotropic unit exhibiting negative optical anisotropy has a characteristic that the optical rotation in the oblique direction of the element is larger than that in the front direction by the hybrid arrangement as described above. There is a big improvement effect on the display abnormality of “white spot”, but the optical rotation in the oblique direction shows a characteristic larger than that in the front direction, even if the optical anisotropy of the optically anisotropic substance is a positive sign. Demonstrate.

  The present invention improves the viewing angle dependency of the driving liquid crystal cell in all directions by combining at least one optically anisotropic layer or element having positive and negative optical anisotropies. It can be done.

  In the above description, each optical anisotropic element is shown in the case where the optical anisotropy unit is in a hybrid arrangement. However, the optical rotation in the oblique direction shows a characteristic larger than that in the front direction. Even if the optical axis of the optical anisotropic material layer constituting the optical anisotropic element is twisted in the element surface direction when viewed from the normal direction of the element as well as the arrangement, the optical axes at both end faces of the optical anisotropic element The same effect can be obtained even if the orientations of the two are the same and the internal sequence is changed continuously or stepwise.

  In order to realize the above optically anisotropic element, for example, an ultraviolet curable liquid crystal in which a polymerizable functional group such as an acryloyloxy group is added to the liquid crystal may be used.

  Embodiments of the liquid crystal display element of the invention will be described in detail.

  (Embodiment 1) FIGS. 1 and 2 are sectional views of a liquid crystal display element according to this embodiment. The liquid crystal display element 10 includes two polarizing plates 1 and 4 (LLC2-92-18 manufactured by SANRITZ), a liquid crystal cell 2 which is an optical anisotropic element for viewing angle compensation, and a driving liquid crystal cell 3 between them. It has the structure which pinches | interposes. The polarizing plate 1 has a polarizing film 1a sandwiched inside a transparent substrate 1b, and the polarizing plate 4 is similarly formed by attaching a polarizing film 4a to a transparent substrate 4b.

  A viewing angle compensating liquid crystal cell 2 as an optically anisotropic element is disposed between the polarizing plates 1 and 4 and has a cell structure in which an optically anisotropic material layer 2c is interposed between the transparent substrates 2a and 2b. The substrates 2a and 2b are obliquely vapor-deposited on the surface at different angles, and a discotic liquid crystal with negative optical anisotropy (C18H6 (OCOC7 H15) 6 with an ester bond in the triphenylene nucleus and an alkyl chain)) Is introduced as an optically anisotropic material layer, and the pretilt angle is 30 ° closer to the driving liquid crystal cell 3 and 60 ° farther away. Δnd of the optically anisotropic material layer used in the viewing angle compensation liquid crystal cell 2 is −570 nm.

  The driving liquid crystal cell 3 is disposed between the viewing angle compensation liquid crystal cell 2 and the polarizing plate 4. The two upper substrates 3a and the lower substrate 3b form transparent electrodes 3c and 3d, respectively, and are connected to the drive power supply 3f. A chiral agent S811 (trade name, manufactured by E. Merck Co. Ltd.) is applied to a twisted nematic liquid crystal (ZLI-4287, manufactured by E. Merck Co. Ltd.) having positive dielectric anisotropy between the substrates 3a, 3b. The mixed material is introduced at a twist angle of 90 °, and the state changes according to the applied voltage from the drive power supply 3f. The torsional arrangement is maintained when no voltage is applied.

  The Δn of the liquid crystal used in the driving liquid crystal cell 3 is 0.093, and the thickness of the liquid crystal layer is 5.5 μm. The liquid crystal molecules of the driving liquid crystal cell 3 are twisted counterclockwise (left twist) from the lower substrate 3b to the upper substrate 3a. This cell 3 operates as a TN cell having a 90 ° twist angle, and performs light control by an optical rotation action.

  FIG. 2A is an exploded perspective view showing the configuration of the liquid crystal display element in the present embodiment. (1.1) and (4.1) are the transmission axes of the two polarizing plates 1 and 4, which are orthogonal to each other, and (1.1) is the + Z direction which is the normal direction of the substrate with respect to the Y axis It is arranged at 135 ° counterclockwise when viewed from the side. (3.1) and (3.2) are the rubbing axes of the upper substrate 3a and the lower substrate 3b of the driving liquid crystal cell 3, that is, the alignment treatment direction, which are orthogonal to each other and are rubbed with respect to the Y axis (3. The angle formed with 1) is 45 ° counterclockwise when viewed from the + Z direction.

  (2.1) and (2.2) of the viewing angle compensation liquid crystal cell 2 which is an optically anisotropic element are the rubbing axes of the upper and lower substrates 2a and 2b, respectively, and the viewing angle compensation liquid crystal cell 2 is a rubbing axis ( 2.2) is arranged so as to be parallel to the rubbing axis (3.1) of the driving liquid crystal cell 3. In other words, the optical axis OL (FIG. 6) of the liquid crystal molecules LM is arranged along these rubbing axes, and becomes the optical axis of the liquid crystal layer on the side where the liquid crystal layer is in contact with the rubbed surface of the substrate.

  The polarizing plate 1 was disposed so that the transmission axis (1.1) was orthogonal to the rubbing axis (2.1) of the viewing angle compensation liquid crystal cell 2.

  The liquid crystal display element of this configuration was measured for electro-optical characteristics in the coordinate system of FIG. The voltage value at the time of measurement (the voltage applied between the driving voltage 3f and the electrodes 3c-3d of the driving liquid crystal cell 3) was changed from 1V to 5V. The results are shown in FIG. FIG. 10 shows applied voltage-transmittance characteristics in four directions, up, down, left, and right, and shows the transmittance when the viewing angle is changed by 30 ° from the front to 60 °. The ideal is that any angle is identical to the transmittance curve of the front (viewing angle θ = 0 °). In the front direction, when a certain voltage is exceeded, the transmittance decreases as the voltage increases.

  FIG. 11 is a graph showing applied voltage-transmittance characteristics of the TN-LCD according to Comparative Example 1 of the prior art. In the lower characteristics, the transmittance decreases as the viewing angle increases. This corresponds to the occurrence of “blackout” when the gradation is actually displayed. Further, the re-increase of the transmittance near 3 V at a viewing angle of 60 ° corresponds to “inversion” in actual display. Looking at the upper direction, the transmittance increases as the viewing angle increases from 0 ° to 60 ° at a voltage of 3V. This corresponds to “white spots” in actual display.

  In the case of this embodiment, when looking at FIG. 10, the characteristics of the lower position are hardly changed, the right direction and the upper direction are deteriorated, and the “reversal” at the viewing angle of 60 ° is decreased only for the left direction and is improved. Is seen.

  Such characteristics can be used when it is desired to improve the viewing angle only in a specific direction, such as car navigation or personal information terminals.

  (Comparative Example 1) In the first embodiment, the voltage-transmittance characteristics when the viewing angle compensating liquid crystal cell 2 is not provided were measured. The measurement results are shown in FIG. In this comparative example, depending on the angle, there was a phenomenon that the display turned white in the upper direction and the display turned black or the gradation was inverted in the lower position.

  (Embodiment 2) FIG. 12 is an exploded perspective view showing a configuration of a liquid crystal display element in this embodiment. In the first embodiment, the viewing angle compensation liquid crystal cell 2 which is an optically anisotropic element is coated with polyimide AL-1051 (manufactured by Nippon Synthetic Rubber) on the side of the lower substrate 2b in contact with the liquid crystal and subjected to rubbing treatment on the surface. Has been. The pretilt angle is 1 °. On the other hand, a vertical alignment process is performed on the side of the upper substrate 2a in contact with the liquid crystal. The viewing angle compensation liquid crystal cell thus produced has a Δnd of −570 nm. The optical axis of the liquid crystal molecules, that is, the optical axis of the optical anisotropic element is parallel to the cell on the driving liquid crystal cell side and continuously changes in the layer thickness direction, and is normal to the cell substrate on the side away from the liquid crystal cell 3. Almost along. The twist angle is 0 °.

  (1.1) and (4.1) are transmission axes of the polarizing plates 1 and 4, which are orthogonal to each other, and (1.1) is 135 ° counterclockwise with respect to the Y axis as viewed from the + Z direction. Be placed. (3.1) and (3.2) are the rubbing axes of the upper and lower substrates 3a and 3b of the driving liquid crystal cell 3, which are orthogonal to each other and the rubbing axis (3.1) and the Y axis. Is arranged at 45 ° counterclockwise when viewed from the + Z direction.

  The optical axis (2.2) of the viewing angle compensation liquid crystal cell 2 is the rubbing axis of the lower substrate 2b, and is orthogonal to the rubbing axis (3.1) of the upper substrate of the driving liquid crystal cell 3, and the rubbing of the lower substrate. Arranged parallel to the axis (3.1) (hybrid arrangement).

  The transmission axis (1.1) of the polarizing plate 1 is arranged so as to be parallel to the rubbing axis (3.1) of the upper substrate of the driving liquid crystal cell 3.

  The liquid crystal display element of this configuration was measured for electro-optical characteristics in the coordinate system of FIG. The voltage value at the time of measurement (voltage applied between the driving power supply 3f and the electrodes 3c-3d of the driving liquid crystal cell 3) was changed from 1V to 5V. The results are shown in FIG. As can be seen from comparison with the characteristic diagram 11 of the conventional example, the viewing angles of the upper direction and the right direction are deteriorated, but the “inversion” of the lower side is almost eliminated, and the contrast at the viewing angle of 60 ° in the left direction is improved.

  (Embodiment 3) In Embodiment 2, the liquid crystal layer of the viewing angle compensating liquid crystal cell 2 is arranged in a twisted arrangement with a twist angle of 10 °. The twist direction is twisted counterclockwise from the lower substrate 2b to the upper substrate 2a (left twist). The other conditions are exactly the same as in the second embodiment. The voltage-transmittance characteristics are shown in FIG. Although the twist angle is 10 °, there is not much difference from the second embodiment. However, the twist of the viewing angle compensation liquid crystal cell 2 increases the reversal of the horizontal direction and improves the lower contrast. It was.

  (Embodiment 4) FIG. 15 is an exploded perspective view showing a configuration of a liquid crystal display element in this embodiment. The viewing angle compensation liquid crystal cell 2 which is the first optical anisotropic element is the same as the viewing angle compensation liquid crystal cell 2 in the second embodiment.

  The viewing angle compensation liquid crystal cell 5 which is the second optical anisotropic element has the structure of the viewing angle compensation liquid crystal cell 2 turned upside down. Polyimide AL-1051 (manufactured by Nippon Synthetic Rubber) is applied to the surface of the lower substrate 2b of the viewing angle compensation liquid crystal cell 2 and the upper substrate 5a of the viewing angle compensation liquid crystal cell 5 in contact with the liquid crystal, and the surface thereof is rubbed. Is given. The pretilt angle is 1 °. On the other hand, a vertical alignment process is performed on the side of the upper substrate 2a of the viewing angle compensation liquid crystal cell 2 and the lower substrate 5b of the viewing angle compensation liquid crystal cell 5 in contact with the liquid crystal. The Δnd of the viewing angle compensation cell is −570 nm in both cells. The optical axis of the liquid crystal molecules, that is, the optical axis of the optical anisotropic element, is parallel to the cell substrate surface on the side close to the driving liquid crystal cell of the viewing angle compensation liquid crystal cell 2 and continuously changes in the layer thickness direction. It is substantially along the normal direction of the cell substrate on the side away from the cell 4, and the cell 5 is the opposite.

  The twist angle is 0 ° for both cells.

  (1.1) and (4.1) are transmission axes of the polarizing plates 1 and 4, which are orthogonal to each other, and (1.1) is 135 ° counterclockwise with respect to the Y axis as viewed from the + Z direction. Be placed. (3.1) and (3.2) are the rubbing axes of the upper and lower substrates 3a and 3b of the driving liquid crystal cell 3, which are orthogonal to each other and the rubbing axis (3.1) and the Y axis. Is arranged at 45 ° counterclockwise when viewed from the + Z direction.

  The optical axis (2.2) of the viewing angle compensation liquid crystal cell 2 is the rubbing axis of the lower substrate 2b, and is orthogonal to the rubbing axis (3.1) of the upper substrate of the driving liquid crystal cell 3, and the rubbing of the lower substrate. Arranged to be parallel to the axis (3.2).

  The optical axis (5.1) of the viewing angle compensation liquid crystal cell 5 is the rubbing axis of the upper substrate 5a, parallel to the rubbing axis (3.1) of the upper substrate of the driving liquid crystal cell 3, and the rubbing axis of the lower substrate. Arranged so as to be orthogonal to (3.2).

  The transmission axis (1.1) of the polarizing plate 1 was arranged so as to be parallel to the rubbing axis (3.1) of the upper substrate of the driving liquid crystal cell 3.

  The liquid crystal display element of this configuration was measured for electro-optical characteristics in the coordinate system of FIG. The voltage value at the time of measurement (voltage applied between the driving power supply 3f and the electrodes 3c-3d of the driving liquid crystal cell 3) was changed from 1V to 5V. The results are shown in FIG. Compared with the characteristic diagram 11 of the conventional example, the left azimuth and lower directional characteristics were deteriorated, but the “inversion” of the right azimuth disappeared and the “white spot” of the upper azimuth was also improved.

  (Embodiment 5) FIG. 17 is an exploded perspective view showing a configuration of a liquid crystal display element in this embodiment. The viewing angle compensation liquid crystal cell 2 which is the first optical anisotropic element has a structure similar to the viewing angle compensation liquid crystal cell 2 in the second embodiment. However, SiO2 is obliquely deposited on one side substrate, and the pretilt angle of the lower side substrate is 60 °. A vertical alignment process is performed on the side of the upper substrate 2a in contact with the liquid crystal.

  The viewing angle compensation liquid crystal cell 5 which is the second optical anisotropic element has the structure of the viewing angle compensation liquid crystal cell 2 turned upside down. The Δnd of the viewing angle compensation cell is −180 nm in both cells. The twist angle is 0 ° for both cells.

  (1.1) and (4.1) are transmission axes of the polarizing plates 1 and 4, which are orthogonal to each other, and (1.1) is 135 ° counterclockwise with respect to the Y axis as viewed from the + Z direction. It is arranged with. (3.1) and (3.2) are the rubbing axes of the upper and lower substrates 3a and 3b of the driving liquid crystal cell 3, which are orthogonal to each other and the rubbing axis (3.1) and the Y axis. Is arranged at 45 ° counterclockwise when viewed from the + Z direction.

  The optical axis (2.2) of the viewing angle compensation liquid crystal cell 2 is the orientation direction of the lower substrate 2b and is orthogonal to the rubbing axis (3.3) of the upper substrate of the driving liquid crystal cell 3, and the rubbing of the lower substrate. Arranged to be parallel to the axis (3.2).

  The optical axis (5.1) of the viewing angle compensation liquid crystal cell 5 is the alignment direction of the upper substrate 5a, parallel to the rubbing axis (3.1) of the upper substrate of the driving liquid crystal cell 3, and the rubbing axis of the lower substrate. Arranged so as to be orthogonal to (3.2).

  The transmission axis (1.1) of the polarizing plate 1 was arranged so as to be parallel to the rubbing axis (3.1) of the upper substrate of the driving liquid crystal cell 3.

  The liquid crystal display element of this configuration is measured for electro-optical characteristics in the coordinate system of FIG. The voltage value at the time of measurement (voltage applied between the driving power source 3f and the electrodes 3c and 3d of the driving liquid crystal cell 3) was changed from 1V to 5V. The results are shown in FIG. Compared with the characteristic diagram 11 of the conventional example (Comparative Example 1), the lower “inversion” is worse, but the “inversion” in the horizontal direction is eliminated, and the “outline” in the upper direction is greatly improved.

  (Embodiment 6) FIG. 19 is an exploded perspective view showing a configuration of a liquid crystal display element in this embodiment. The viewing angle compensation liquid crystal cell 20 which is an optically anisotropic element in the present embodiment is composed of two optical anisotropic layers, and the viewing angle compensation cells 2 and 5 in the fourth embodiment overlap each other. Δnd was −380 nm.

  FIG. 20 is a cross-sectional view of the viewing angle compensation liquid crystal cell 2 as viewed from the + X-axis direction. The optical axis direction when viewed from the + Z-axis direction with the substrate 2d subjected to the vertical alignment treatment on both sides as the boundary is between the upper 2a and 2d, the rubbing axis (2.1) direction in the cell 2 of FIG. 19, and the lower 2d -The distance between 2b is different from the (2.2) direction. When the rubbing axes (2.1) and (2.2) are in the same direction, the optical axis is on a single axis, and when the rubbing axes are in different directions, there are two axes as shown in the present embodiment. Further, the optical axis is continuously changed by twisting the liquid crystal layer.

  The liquid crystal display element of this configuration was measured for electro-optical characteristics in the coordinate system of FIG. The voltage value at the time of measurement (voltage applied between the driving power supply 3f and the electrodes 3c-3d of the driving liquid crystal cell 3) was changed from 1V to 5V. Compared with FIG. 11 showing the characteristics of the conventional example, lower “inversion” and “blackout” are improved, and there is not much change in other directions.

  The optically anisotropic element used in the present embodiment can be obtained by combining several optical anisotropic elements of the present invention as shown in the fourth embodiment. Further, an optical anisotropic element composed of one optical anisotropic layer can be produced by arranging a liquid crystal having a negative optical anisotropy in a bend alignment / bend twist alignment.

  (Embodiment 7) The configuration of this embodiment is shown in FIG. In the second embodiment, biaxiality is used to compensate for the optical anisotropy of the unstable discotic alignment between the viewing angle compensation liquid crystal cell 2 and the driving liquid crystal cell 3 which are the first optical anisotropic elements. A retardation film 50 was disposed. Although there was no significant improvement in characteristics, display irregularities due to poor alignment could be alleviated.

  (Embodiment 8) When the viewing angle compensation liquid crystal cell 2 in Embodiment 2 was made of a polysiloxane main chain and a polymer copolymer having biphenylbenzoate and cholesteryl groups in an appropriate ratio in the side chain, Characteristics similar to those of Form 2 were obtained. Furthermore, a thinner liquid crystal display element is realized by producing an optically anisotropic element with a polymer copolymer.

  (Embodiment 9) FIG. 22 is a cross-sectional view of a liquid crystal display element according to this embodiment, and FIG. The liquid crystal display element is driven by two polarizing plates (LLC2-92-18: manufactured by SANRITZ) 1, 4 and liquid crystal cells 2, 5, 6, 7 that are optical anisotropic elements for viewing angle compensation between them. The liquid crystal cell 3 is sandwiched.

  The viewing angle compensating liquid crystal cell used as the optical anisotropic elements 2 and 5 is disposed between the polarizing plate 1 and the driving liquid crystal cell 3. The optical anisotropic element 2 has a positive optical anisotropy.

  It has a liquid crystal cell structure in which a liquid crystal 2c is interposed between the transparent substrates 2a and 2b. The substrates 2a and 2b are subjected to different alignment processes, 2a is a vertical alignment, 2b is a horizontal alignment, and as the horizontal alignment process of 2b, a tilt alignment of about 2 ° is obtained by rubbing the alignment film. . As the liquid crystal 2c, nematic liquid crystal (ZLI-4287, manufactured by E. Merck Co. Ltd.) having a positive optical anisotropy is used, and has a thickness of 1.9 μm and retardation (optical anisotropy of liquid crystal and liquid crystal The product of the layer thickness is 180 nm. The optically anisotropic element 7 (substrates 7a and 7b) is an element having the same optical anisotropy as that of the optical anisotropy element 2, and is disposed upside down.

  The optical anisotropic element 5 is composed of a viewing angle compensation cell which is a negative sign of optical anisotropy, and has a liquid crystal cell structure in which a liquid crystal 5c is interposed between transparent substrates 5a and 5b.

  On the transparent substrate 3b, SiO2 is obliquely deposited on the surface at an angle, and a discotic liquid crystal (C18H6 (OCOC7 H15) 6 having an ester bond on a triphenylene nucleus and an alkyl chain) is optically anisotropic. The pretilt angle is 60 ° closer to the driving liquid crystal cell 4 and 90 ° farther from the driving liquid crystal cell 4. The retardation is -220 nm. The optically anisotropic element 6 (substrates 6a and 6b) is composed of a viewing angle compensation cell having the same optical anisotropy as that of the optically anisotropic element 5, and is disposed upside down.

  The optical anisotropic elements 2 and 5 and the optical anisotropic elements 6 and 7 make a pair, and an element having a negative optical anisotropy faces the driving liquid crystal cell 3. That is, the driving liquid crystal cell 3 is disposed between the optical anisotropic element 5 having a negative optical anisotropy and the optical anisotropic element 6 having a negative sign.

  The upper substrate 3a of the driving liquid crystal cell 3 has a liquid crystal 3c sandwiched between a substrate 3a on which a transparent electrode 3a1 is formed on a color filter and a substrate 3b on which a thin film transistor and a pixel electrode 3b1 are formed on each picture element. Sometimes forms a 90 ° twist orientation. Liquid crystal 3c is a nematic liquid crystal (ZLI-4287, manufactured by E. Merck Co. Ltd) mixed with a chiral agent S811 (trade name, manufactured by E. Merck Co. Ltd) with a twist angle of 90 °. The state changes according to the applied voltage from the drive power supply 4E which is a voltage applying means. The torsional arrangement is maintained when no voltage is applied.

  The Δn of the liquid crystal used for the driving liquid crystal cell 3 is 0.093, and the thickness of the liquid crystal layer is 5.0 μm. The liquid crystal molecules of the driving liquid crystal cell 3 are twisted counterclockwise (left twist) from the lower substrate 3b to the upper substrate 3a. This cell 3 operates as a TN cell having a 90 ° twist angle, and performs light control by an optical rotation action.

  FIG. 26 is an exploded explanatory view showing the configuration of the liquid crystal display element in the present embodiment, wherein (a) is a perspective view, (b) is a top view, and (c) is a side view. (1.1) and (4.1) are the absorption axes of the two polarizing plates 1 and 7, which are orthogonal to each other, and (1.1) is the + Z direction which is the normal direction of the substrate with respect to the X axis. It is arranged at 45 ° counterclockwise when viewed from the side.

  (3.1) and (3.2) are the rubbing axes of the upper substrate 3a and the lower substrate 3b of the driving liquid crystal cell, that is, the alignment treatment direction, which are orthogonal to each other and are rubbed with respect to the X axis (3.1). ) Is arranged at 135 ° counterclockwise when viewed from the + Z direction.

  The positive optical anisotropic element 2 has its optical anisotropy unit optical axis 20U aligned in the same direction, and has a tilt orientation of about 2 ° on the lower substrate as seen in the side view of FIG. The upper substrate is arranged at an angle of approximately 90 ° while being continuously inclined (hybrid arrangement). The average of the optical axes of these optical anisotropy units, that is, the average optical axis 2OA is arranged at 225 ° counterclockwise when viewed from the + Z direction with respect to the X axis.

  The positive optical anisotropic element 7 disposed on the other surface side of the liquid crystal cell 3 has the same configuration as that of the optical anisotropic element 2, and the arrangement is such that the optical anisotropic element 2 is reversed upside down as viewed from the + Z axis. The average optical axis 60A is 135 ° from the + Z axis to the X axis.

  On the other hand, the negative optical anisotropic element 5 has an optical axis 5OU of optical anisotropy unit (the direction with the smallest refractive index is defined as the optical axis) on the upper substrate as shown in FIG. The tilt angle is continuously changing during the tilt of 60 ° on the lower substrate. Therefore, the average optical axis 5OA is inclined with respect to the element surface, and the direction thereof is arranged at −45 ° from the X axis when viewed from the + Z axis.

  The negative optical anisotropic element 5 has the same configuration as that of the optical anisotropic element 3, and the optical anisotropic element 2 is turned upside down when viewed from the + Z axis, and the average optical axis 60A changes the average optical axis 20A from the + Z axis to X. Arranged at 45 ° to the axis.

  The liquid crystal display element of this configuration was measured for electro-optical characteristics by changing the observation point angle, azimuth angle φ, and viewing angle θ in the coordinate system of FIG. The transmissivity of the liquid crystal panel was measured by changing the voltage value at the time of measurement (the voltage applied from the driving voltage 3f to the liquid crystal layer 4C of the driving liquid crystal cell 3 from 0 V to 5 V. The result is shown in FIG. 27. 4 shows the applied voltage-transmittance characteristics in four directions, top, bottom, left, and right (excluding the decrease in transmittance due to the color filter), and the transmittance when the viewing angle is changed by 30 ° from the front to 60 °. The ideal characteristic is that the angle is the same as the transmittance curve of the front (viewing angle θ = 0 °) at any angle.

  FIG. 28 is a graph showing applied voltage-transmittance characteristics when a conventional optical anisotropic element is not used. In the characteristic of the downward direction, the transmittance decreases as the viewing angle increases. This corresponds to the occurrence of “blackout” when the gradation is actually displayed. Further, the re-increase of the transmittance near 3 V at a viewing angle of 60 ° corresponds to “inversion” in actual display. Looking at the upper direction, the transmittance increases as the viewing angle increases from 0 ° to 60 ° at a voltage of 3V. This corresponds to “white spots” in actual display.

  In the case of the present embodiment, in FIG. 27, the characteristics of all the azimuths are improved. In particular, the transmittance at 60 ° obliquely at 0V shows a high value except the upper azimuth, and a bright display is obtained even in the oblique direction. realizable.

  When the actual liquid crystal display element was observed with 64 gradations, good display was obtained even when the angle was increased.

  (Comparative Example 2) In the ninth embodiment, voltage-transmittance characteristics were measured when only the negative optical anisotropic elements 3 and 5 and no positive optical anisotropic elements 2 and 6 were present. The measurement results are shown in FIG. In this comparative example, the lower-order characteristics are somewhat improved, but the transmittance at 5 V on the left and right is high and the contrast ratio is low.

  (Comparative Example 3) The voltage-transmittance characteristics in the case where the negative optical anisotropic elements 5 and 6 are not provided with only the positive optical anisotropic elements 2 and 7 in the ninth embodiment shown in FIG. The measurement results are shown in FIG. In this comparative example, the transmissivity in the upper right and left directions is kept low even at 5 V, but the abrupt decrease in transmissivity in the lower position is significant, and inversion and blackout occur.

  (Embodiment 10) In Embodiment 9, the optical anisotropy of unstable discotic alignment is compensated between the viewing angle compensation liquid crystal cell 2 and the driving liquid crystal cell 3 which are the first optical anisotropic elements. A biaxial retardation film was arranged for the purpose. Although there was no significant improvement in characteristics, display unevenness due to poor alignment could be alleviated.

  (Embodiment 11) FIGS. 31 and 32 show a liquid crystal display element in this embodiment. The liquid crystal display element 10 includes two polarizing plates 1 and 4 (LLC-92-18: manufactured by SANRITZ), and a liquid crystal cell 2 and a driving liquid crystal cell 3 which are optical anisotropic elements for viewing angle compensation between them. It has the structure which pinches | interposes. The polarizing plate 1 is formed by sandwiching a polarizing film on a transparent substrate, and the polarizing plate 4 is similarly formed by attaching a polarizing film to a transparent substrate.

  A viewing angle compensating liquid crystal cell 2 as an optically anisotropic element is disposed between the polarizing plates 1 and 4 and has a cell structure in which an optically anisotropic material layer 2c is interposed between the transparent substrates 2a and 2b. Substrates 2a and 2b are formed by obliquely depositing SiO2 on the surface at different angles, with a negative optical anisotropy between them (a C18H6 (OCOC7 H15) 6 with an ester bond on a triphenylene nucleus and an alkyl chain)) Is introduced as an optically anisotropic material layer, and the pretilt angle (inclination of the optical axis 20U with respect to the substrate surface) is 30 ° closer to the driving liquid crystal cell 3 and about 90 ° farther (see FIG. 33). ). The effective Δnd of the optically anisotropic material layer used in the viewing angle compensation liquid crystal cell 2 is −60 nm.

  The driving liquid crystal cell 3 is disposed between the viewing angle compensation liquid crystal cell 2 and the polarizing plate 4. The two upper substrates 3a and the lower substrate 3b form transparent electrodes 3a1 and 3b1, respectively, and are connected to the drive power supply 3E. Nematic liquid crystal (ZLI-4287, manufactured by E. Merck Co. Ltd.) having positive dielectric anisotropy is filled between the substrates 3a and 3b, and the state changes according to the applied voltage from the drive power supply 3E. The hybrid arrangement is maintained when no voltage is applied.

  The Δnd of the liquid crystal molecules in the driving liquid crystal cell 3 is 0.093, and the thickness of the liquid crystal layer is 5.0 μm. The liquid crystal molecules of the driving liquid crystal cell 3 are arranged with the tilt angle changing from substantially vertical to horizontal from the lower substrate 3b to the upper substrate 3a (hybrid arrangement).

  FIG. 32 is an exploded perspective view showing the configuration of the liquid crystal display element in the present embodiment.

  (1.1) and (4.1) are the transmission axes of the two polarizing plates 1 and 4, which are orthogonal to each other, and (1.1) is the + Z direction that is the normal direction of the substrate with respect to the Y axis It is arranged at 45 ° counterclockwise when viewed from the side. (3.1) is the rubbing axis of the upper substrate 3a of the driving liquid crystal cell 3, that is, the alignment processing direction, and the angle formed by the rubbing axis (3.1) with respect to the Y axis is 180 counterclockwise when viewed from the + Z direction. Arranged at °. (3.2) is the orientation direction of the lower substrate 3b, and substantially coincides with the -Z direction.

  (2.1) and (2.2) of the viewing angle compensation liquid crystal cell 2 which is an optically anisotropic element are the orientation treatment directions of the upper and lower substrates 2a and 2b, respectively, and the viewing angle compensation liquid crystal cell 2 is oriented. The processing direction (2.2) is arranged so as to be parallel to the rubbing axis (3.1) of the driving liquid crystal cell 3.

  The polarizing plate 1 was arranged such that the transmission axis (1.1) formed an angle of 45 ° with the rubbing axis (2.1) of the viewing angle compensation liquid crystal cell 2.

  The liquid crystal display element of this configuration was measured for electro-optical characteristics in the coordinate system of FIG. The voltage value at the time of measurement (the voltage applied between the driving voltage 3E and the electrodes 3a1, 3b1 of the driving liquid crystal cell 3) was changed from 0V to 5V. The results are shown in FIG. FIG. 34 shows the viewing angle-luminance characteristics for each of the upper, lower, left, and right gradations, and each gradation luminance when the viewing angle is changed every 10 degrees from the front to 60 degrees. The ideal is that any angle is identical to the transmittance curve of the front (viewing angle θ = 0 °).

  In the case of the present embodiment, when FIG. 34 is viewed, “inversion” is reduced in any of the top, bottom, left, and right directions as compared with TN, and the black transmittance is difficult to increase. Is obtained.

  Although the present invention has been described with reference to a TN type liquid crystal display element using TFT, it goes without saying that an excellent effect can be obtained even when applied to an active matrix using MIM or the like and a simple matrix liquid crystal display element such as STN. .

Sectional drawing which shows the structure of Embodiment 1 of this invention BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagram illustrating a first embodiment of the present invention, in which (a) is an exploded perspective view illustrating a configuration, and (b) is a diagram illustrating a coordinate system for measuring electro-optical characteristics. The figure explaining the principle of operation of a TN type liquid crystal display element. The figure explaining the generation | occurrence | production principle of the viewing angle characteristic of a TN type | mold liquid crystal display element. The figure explaining the generation | occurrence | production principle of the viewing angle characteristic of a TN type | mold liquid crystal display element. The figure which shows the arrangement | sequence state of the optical anisotropic element of this invention. The figure explaining the optical compensation principle at the time of using the optically anisotropic element of this invention. The figure which shows the refractive index ellipsoid of the drive cell at the time of a voltage application. The figure which showed the refractive index ellipsoid of the optically anisotropic element whose refractive index anisotropy is a negative sign in the thickness direction. 2 is an electro-optical characteristic of the liquid crystal display element of Embodiment 1. Electro-optical characteristics of conventional liquid crystal display elements. FIG. 9 illustrates a configuration of a second embodiment. FIG. 6 is a diagram illustrating an effect of the second embodiment. FIG. 10 is a diagram for explaining the effect of the third embodiment. FIG. 6 illustrates a configuration of a fourth embodiment. FIG. 10 is a diagram illustrating an effect of the fourth embodiment. FIG. 6 illustrates a configuration of a fifth embodiment. FIG. 6 illustrates a configuration of a fifth embodiment. FIG. 10 illustrates a configuration of a sixth embodiment. FIG. 10 is a diagram illustrating the operation of a sixth embodiment. FIG. 9 illustrates a configuration of a seventh embodiment. FIG. 10 illustrates a configuration of a ninth embodiment. FIG. 10 is a diagram illustrating an effect of the ninth embodiment. The figure which shows the arrangement | sequence state of the positive optical anisotropic element concerning this invention. The figure explaining the optical compensation principle at the time of using the positive optical anisotropic element concerning this invention. FIG. 10 is a configuration diagram of a liquid crystal display element of Embodiment 9. FIG. 10 is a curve diagram showing electro-optical characteristics of the liquid crystal display element of Embodiment 9. FIG. 6 is a curve diagram showing electro-optical characteristics of a liquid crystal display element of a conventional example. FIG. 6 is a curve diagram showing electro-optical characteristics of Comparative Example 2. FIG. 9 is a curve diagram showing electro-optical characteristics of Comparative Example 3. Sectional drawing of the liquid crystal display element of Embodiment 11. FIG. FIG. 16 is a configuration diagram of a liquid crystal display element of Embodiment 11. FIG. 20 is a schematic diagram of a liquid crystal display element according to an eleventh embodiment. FIG. 25 is a curve diagram showing electro-optical characteristics of the liquid crystal display element of Embodiment 11. The curve figure which shows the viewing angle dependence of the brightness | luminance of the conventional TN type | mold liquid crystal display element.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 4 ... Polarizing plate 2, 5 ... Optically anisotropic layer 2c ... Optically anisotropic material layer 3 ... Drive liquid crystal cell

Claims (8)

  A liquid crystal cell for driving in which a liquid crystal is sandwiched between two substrates between at least two polarizing plates and at least one optical anisotropic layer having different optical anisotropy signs from each other. A liquid crystal display element having an optically anisotropic layer, wherein the liquid crystal display elements are arranged in combination, and an angle of each optical axis is not constant with respect to the thickness direction.   A liquid crystal cell for driving in which a liquid crystal is sandwiched between two substrates between at least two polarizing plates and at least one optical anisotropic layer having different optical anisotropy signs from each other. A liquid crystal display element having an optically anisotropic layer, characterized in that it is arranged in combination and has optical rotation in a direction inclined from the normal direction of the combined optically anisotropic layer.   The optical axis of the optical anisotropy unit of the optical anisotropy layer whose optical anisotropy unit is positive is continuous in the optical anisotropic layer thickness direction with respect to the optical anisotropic layer thickness direction. The liquid crystal display element according to claim 2, wherein the liquid crystal display element is changed.   The optical axis of the optical anisotropy unit of the optical anisotropic layer continuously changes in the optical anisotropic layer thickness direction with respect to the optical anisotropic layer thickness direction, and the orientation of the optical axis is the same direction. 3. The liquid crystal display element according to claim 1, wherein the liquid crystal display element is arranged.   A liquid crystal cell for driving a combination of an optically anisotropic layer having a negative optical anisotropy unit and an optically anisotropic layer having a positive optical anisotropy unit. The liquid crystal display element according to claim 1, wherein the liquid crystal display element is disposed on both sides of the liquid crystal display element.   6. An optically anisotropic layer comprising an optically anisotropic unit having negative optical anisotropy is disposed adjacent to a driving liquid crystal cell, according to any one of claims 1, 2, 4, and 5. Liquid crystal display element.   The optical axis of the optical anisotropy layer is continuously changing with respect to the thickness direction of the optical anisotropic layer. The liquid crystal display element according to claim 1, wherein the liquid crystal display element is disposed adjacent to the liquid crystal cell for use.   Optical axis orientation of an optically anisotropic layer whose optical anisotropy unit is positive, and optical axis orientation of an optically anisotropic layer whose optical anisotropy unit is negative And the liquid crystal display element according to claim 1, wherein the liquid crystal display elements are arranged orthogonal to each other.

Images