KR20000077245A - Liquid crystal display element, backlight unit and liquid crystal display device using them - Google Patents

Abstract

In the liquid crystal display device of the present invention, a liquid crystal layer is sandwiched and supported between a pair of substrates, the liquid crystal molecules in the liquid crystal layer are twist-oriented at 90 degrees, and the first light propagation direction conversion means and the second light propagation direction conversion. Means are provided. The first light traveling direction converting means is constituted by phase compensation plates affixed to each outer surface of the substrate, and improves the viewing angle characteristic except for the thermal visual direction, which is one specific direction when the display surface is observed from the inclined direction. . The second optical advancing direction converting means is constituted by an optical axis converting plate attached to the front phase compensating plate and converts the advancing direction of light in the column visual direction.

This realizes a liquid crystal display element having good visual characteristics without gray scale inversion.

Description

Liquid crystal display element, backlight unit and liquid crystal display device using them}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to liquid crystal display devices used for OA monitors, video cameras, and the like, and more particularly, to liquid crystal display devices and the like for improving viewing angle characteristics.

Background Art [0002] Color liquid crystal displays are conventionally used as large display panels used for OA monitors and the like, and small display panels used for video cameras. As these color liquid crystal displays, a twisted nematic (TN) type liquid crystal display device having excellent image quality is generally employed. 1 is a side cross-sectional view of a main part of a conventional liquid crystal display device.

As shown in FIG. 1, in the TN type liquid crystal display device, the liquid crystal layer 108 is sandwiched and sandwiched between a pair of substrates 107 and 109 arranged in parallel to form a rear substrate 107. The polarizing plates 105 and 105 are affixed on the outer surface and the outer surface of the front board | substrate 109, respectively. Although not shown, a thin film transistor, a pixel electrode, and an alignment film are formed inside the substrate 107, and an opposite electrode and an alignment film are formed inside the substrate 109. The liquid crystal molecules 8 in 108 are continuously twisted 90 degrees between the substrates 107 and 109. In addition, although the liquid crystal molecule 8 of FIG. 1 is drawn by three layers, it consists of a myriad of continuous layers actually.

In the state where a specific voltage is applied to the liquid crystal layer 108 between the pixel electrode and the counter electrode, the liquid crystal molecules in the middle part of the thickness direction of the liquid crystal layer 108 (hereinafter referred to as "intermediate portion"). Although 8c is in an upright position with respect to the substrates 107 and 109, the liquid crystal molecules 8a and 8a near the inner surface of the substrates 107 and 109 are relatively unmovable and are parallel to the substrates 107 and 109. It is in one posture. This is because the liquid crystal molecules 8a and 8a are anchored to the inner surfaces of the substrates 107 and 109. Therefore, the liquid crystal layer 108 to which the voltage is applied is not to be in a standing position in which the liquid crystal molecules 8 simply stand, but needs to be regarded as a total of individual liquid crystal molecules 8 in which the inclination angle continuously changes. .

In such a liquid crystal display device, when the display surface D is observed in the oblique direction, there is a problem such as gray scale inversion. For example, when the display surface D is observed in the front direction S, which is the normal direction of the display surface D, and a white square is displayed on the black ground, the display surface D When observed in the inclined direction, the brightness of the black paper becomes brighter than the brightness of the square of the displayed white, and it can be seen as if the display is negative.

Such gray level inversion occurs in a specific voltage state. This is due to the fact that the liquid crystal molecules 8 are rod-shaped and the liquid crystal molecules 8c in the middle portion are inclined downward, and as shown in FIG. Gradation inversion occurs about 20 degrees below. When the liquid crystal molecule 8c is viewed from the front, the refractive index of the liquid crystal is relatively large. However, as the viewing direction is lowered, the refractive index of the liquid crystal becomes smaller, so that the refractive index of the liquid crystal when the liquid crystal molecule 8c is observed in the long axis direction. It is because it is smallest and refractive index becomes large again below. In addition, tone inversion may occur not only in the downward direction but also in the left and right directions.

Thus, in order to compensate for the gradation inversion, a liquid crystal display element as shown in Fig. 2 is provided. 2 is a cross-sectional side view of a main part of a conventional improved liquid crystal display device. In the liquid crystal display device, phase compensation plates 106 and 106 are disposed between the rear substrate 107 and the polarizing plate 105, and between the front substrate 109 and the polarizing plate 105, respectively. .

The phase compensating plate 106 also includes a uniaxially oriented phase compensating plate and a biaxially oriented phase compensating plate. However, the phase compensating plate produced by the composition including the optical medium 6 having optically refractive index anisotropy is excellent. This optical medium 6 is a discotic liquid crystal material having negative refractive anisotropy.

Thus, when a voltage is applied to the liquid crystal layer 108, the direction of the liquid crystal molecules 8 in the liquid crystal layer 108 changes continuously in the thickness direction of the liquid crystal layer 108. Therefore, it is impossible to compensate the gradation inversion due to all liquid crystal molecules 8 in the thickness direction of the liquid crystal layer 108 only if the optical medium 6 has the same inclination angle in the thickness direction. . Thus, in order to compensate for the gray level inversion by the phase compensation plate 106, the optical medium 6 is hybrid oriented and UV cured.

Hybrid alignment means that the optical medium (the liquid crystal material of the discotic) 6 is horizontal in one surface of the phase compensation plate 106, vertically in the other surface, and inclination angle in the middle of the liquid crystal molecules 8 The inclination angle of the optical medium 6 is changed in the thickness direction such as to be perpendicular to the long axis, and the axis is continuously changed. The negative refractive anisotropy of the optical medium 6 is offset by the positive refractive anisotropy of the liquid crystal molecules 8 in the liquid crystal layer 108 by the hybrid orientation of the optical medium 6, thereby alleviating the direction dependence of the refractive index. . In this configuration, it is possible in principle to completely compensate the visual characteristics in the alignment state of a particular liquid crystal.

In addition, by inserting a uniaxially or biaxially oriented phase compensation plate, not a discotic liquid crystal material, between the substrate and the polarizing plate, the gray level inversion angle is increased (expanded outward) and the viewing angle characteristic is improved. This has been proposed in Japanese Patent Laid-Open Nos. 6-331979, 6-250166, and 6-214116. However, in a liquid crystal display device using a simple uniaxial or biaxial phase compensation plate, gray level inversion is mainly seen in the downward direction, and sometimes in the left and right directions, so that a phase compensation plate using hybrid alignment of discotic liquid crystal materials is used. Improvement in viewing angle characteristics, such as a liquid crystal display element, cannot be realized. Furthermore, a method of further improving the viewing angle characteristic is proposed in Japanese Patent Laid-Open No. 9-5520 by using a phase compensating plate obtained by solidifying the above-described discotic liquid crystal material in a hybrid alignment state. Further, Japanese Patent Application Laid-Open Nos. 7-64069 and 7-209637 propose a film in which multilayer films having different refractive indices are formed by using a specific ultraviolet curing method. It is proposed in Japanese Patent Laid-Open No. 9-281483. This is commercialized as a luminist film (brand name).

However, as shown in FIG. 2, the liquid crystal display device having the phase compensation plate 106 made of discotic liquid crystal material is completely in most cases except one direction (down direction) to which the long axis of the liquid crystal molecule 8c is directed. Although the viewing angle characteristic could be improved, the refractive index anisotropy of the liquid crystal changes rapidly in the downward direction, and gray scale inversion occurs at 40 degrees or lower downward. The phase compensation plate 106 is arranged by gradually changing the inclination so that the optical medium 6 is perpendicular to the long axis direction of the liquid crystal molecules 8, but is not offset by the sharply changing refractive index anisotropy of the liquid crystal. I think this happens.

A large panel used for an OA monitor or the like is installed and used on a disc, and the display surface D is not observed from the downward direction, so there is no problem in use even if gray scale inversion occurs in the downward direction. Therefore, in the liquid crystal display device for large panels used for OA monitors and the like, alignment processing has been performed on the substrates 107 and 109 so that gray scale inversion occurs in the downward direction. However, for example, since the small display panel of the video camera is observed in various directions, there is a request to prevent gradation inversion even in the downward direction.

In addition, there are no liquid crystal display devices capable of completely eliminating the problem of gray scale inversion by various films disclosed in the above publications.

Further, the liquid crystal display device having the phase compensating plate 106 shown in FIG. 2 has the characteristics shown in the chromaticity diagram as shown in FIG. 3, and in particular, the color change in the downward direction is large.

Accordingly, an object of the present invention is to provide a liquid crystal display device capable of solving the problem of viewing angle characteristics such that grayscale inversion and color change occur.

1 is a side cross-sectional view of a main part of a conventional liquid crystal display device;

2 is a side cross-sectional view of an essential part of a conventional improved liquid crystal display device;

3 is a chromaticity diagram of a conventional improved liquid crystal display device;

4 is a side sectional view of a liquid crystal display device according to Embodiment 1 of the present invention;

5 is a side cross-sectional view of the main part of FIG. 1;

6 is a side view showing an optical axis conversion plate of Example 1-2 of the present invention;

7 is a side sectional view showing main parts of a liquid crystal display device according to an embodiment 1-3 of the present invention;

8 is a schematic side cross-sectional view of the backlight unit of embodiment 1-4 of the present invention;

9 is a schematic side sectional view showing a modification of the backlight unit of Example 1-4 of the present invention;

10 is a schematic side cross-sectional view showing another modification of the backlight unit of Example 1-4 of the present invention;

11 is a chromaticity diagram of a liquid crystal display element in Example 1 of the present invention;

12 (a) is a conceptual diagram showing the light amount distribution of the liquid crystal display device of Example 1-1 of the present invention;

12 (b) is a conceptual diagram showing the light amount distribution of the backlight unit of Example 1-4 of the present invention;

12 (c) is a conceptual diagram of light amount distribution when the liquid crystal display device of FIG. 9 (a) and the backlight unit of FIG. 9 (b) are combined;

Fig. 13 is a schematic perspective view showing an example of using the liquid crystal display element in Example 1-7 of the present invention as an OA monitor;

14 is a side sectional view of a liquid crystal display device showing a modification of Embodiment 1 of the present invention;

Fig. 15 is a side sectional view of a vertical alignment liquid crystal display device according to a second embodiment of the present invention;

Fig. 16 is a sectional side view showing the main parts of a vertical alignment liquid crystal display device according to the second embodiment of the present invention;

17 is a side sectional view of a liquid crystal display device according to a modification of the present invention.

The object is the first light traveling direction converting means for compensating the optical properties according to claim 1 and the second light traveling direction converting means for compensating optical properties that cannot be compensated by the first light traveling direction converting means. It is achieved by a liquid crystal display device having a.

With such a configuration, the optical characteristics are compensated by the two light traveling direction conversion means. Since so-called two-stage compensation is made, it is possible to efficiently compensate for the optical characteristics.

The liquid crystal display device according to claim 1, wherein the optical characteristic is a viewing angle characteristic.

As described above, in order to exhibit excellent reagent angle characteristics in both the front and the downward direction by compensation of the conventional hybrid film, it was achieved by adjusting the thickness, the refractive index, the orientation of the hybrid, and the like. Because of this strictness, the reality is very difficult. For example, even if the front contrast is excellent, there is a problem of lowering the characteristic in the downward direction (in particular, grayscale inversion occurs). On the other hand, when the viewing angle characteristic is improved by two-step compensation as in the above configuration, the front contrast is improved by the first light traveling direction converting means, and the viewing angle characteristic of the downward direction is improved by the second light traveling direction converting means. Since it can be made, the characteristic of both a front and a downward direction can be improved easily. Further, even if the performance of the hybrid film (the first light traveling direction converting means) varies due to the manufacturing process or the like, the second light traveling direction converting means can compensate for it, so that it is not necessary to use a precise hybrid film. Therefore, the range of selection of a hybrid film becomes wider, and it becomes possible to reduce the manufacturing cost of a liquid crystal display element.

The above object is a liquid crystal display device having a first optical advancing direction converting means for sandwiching a liquid crystal layer between a pair of substrates according to claim 3 and improving a viewing angle characteristic except for a thermal viewing direction in any one direction, wherein the column And a second light advancing direction converting means for converting the advancing direction of a part of the light traveling in a direction other than the visual direction to the thermal visual direction.

According to this configuration, the viewing angle characteristic other than the column visual direction is improved by the first optical advancing direction converting means, and the viewing angle characteristic in the column visual direction is improved by the second optical advancing direction converting means. Therefore, the liquid crystal display device of the present invention improves the viewing angle characteristic in all directions by combining the first light traveling direction converting means and the second light traveling direction converting means. In other words, the column visual direction is a direction in which the first optical advancing direction converting means cannot improve the viewing angle characteristic.

The liquid crystal display device according to claim 3, wherein the thermal visual direction only in the first light advancing direction converting means is the visual inversion direction.

As in this configuration, if the column visual direction is the visual inversion direction, the combination of the first light advancing direction converting means and the light advancing converting means can eliminate the visual inversion in the visual inversion direction and provide good visual characteristics. The display element can be realized.

4. The liquid crystal molecules according to claim 3, wherein the liquid crystal molecules in the liquid crystal layer are twist-oriented, and the thermal visual direction is a liquid crystal molecule located at the center of the thickness direction of the liquid crystal layer when a specific voltage is applied to the liquid crystal layer. It can be set as the liquid crystal display element characterized by the long axis direction.

By setting it as this structure, the TN type liquid crystal display element which improved the viewing angle characteristic of the long-axis direction of the liquid crystal molecule located in the center part of the thickness direction of the liquid crystal layer which is a thermal viewing direction can be implement | achieved.

The composition of claim 3, wherein the first light traveling direction converting means is a phase compensating plate affixed to at least one outside of the substrate, and the phase compensating plate comprises an optical medium having optically refractive index anisotropy. The optical medium may be inclined in the thickness direction of the phase compensation plate, and the inclination angle may be changed in the thickness direction.

According to this structure, even if the inclination angle of liquid crystal molecules in the said liquid crystal layer changes continuously, the refractive index anisotropy of each liquid crystal molecule can be canceled by the said phase compensation plate.

The first optical advancing direction converting means is a phase compensating plate affixed to the outside of at least one substrate, the phase compensating plate has a birefringence, and the birefringence is changed in the thickness direction. A liquid crystal display device can be provided.

According to this configuration, even if the inclination angle of the liquid crystal molecules in the liquid crystal layer is continuously changed, the refractive index anisotropy of each liquid crystal molecule can be canceled by the phase compensation plate having birefringence.

The liquid crystal display device according to claim 6, wherein the optical medium in the phase compensation plate has optically negative refractive anisotropy.

The liquid crystal display device according to claim 8, wherein the optical medium is formed of a composition having discotic liquid crystallinity.

The liquid crystal display device according to claim 6, wherein the optical medium in the phase compensation plate has optically positive refractive anisotropy.

The liquid crystal display device according to claim 10, wherein the optical medium is formed of a composition having liquid crystallinity.

Moreover, the said objective is a liquid crystal display element which clamped the liquid crystal layer between a pair of board | substrates, and the 2nd light advancing which converts a part of the light which progresses in the direction which brightness is not falling in the direction where the brightness is falling It is achieved by a liquid crystal display device characterized by including a direction converting means.

With this configuration, since the light traveling in the direction in which the brightness is not reduced can be converted into the direction in which the brightness is decreased by the second light traveling direction conversion means, the brightness in the direction in which the brightness is decreasing You can compensate.

The liquid crystal display device according to claim 12, wherein the liquid crystal display device is a vertical alignment type.

The liquid crystal display device according to claim 12, wherein the liquid crystal display device is an OCB type.

In the vertical alignment of the above structure and the liquid crystal display element of the optical compensation bend type (OCB type), the brightness in the direction in which the brightness is decreasing can be compensated by the second light traveling direction converting means.

The above object is a liquid crystal display device in which a liquid crystal layer is sandwiched between a pair of substrates and has a thermal visual direction in a specific direction, wherein a part of the light traveling in a direction other than the thermal visual direction is converted into the thermal visual direction. It is achieved by a liquid crystal display device characterized by including a second light traveling direction converting means.

In the liquid crystal display element of this structure, the advancing direction of a part of the light traveling outside the column visual direction can be converted to the column visual direction by the second optical advancing direction converting means, so that the viewing angle characteristic of the column visual direction is changed. Can be improved.

The liquid crystal display device according to claim 15, wherein the liquid crystal display device is a vertical alignment type, and the liquid crystal molecules in the liquid crystal layer are inclined with anisotropy by application of voltage.

As described above, in the vertical liquid crystal display device, the viewing angle characteristic of the liquid crystal molecules in the liquid crystal layer inclined in anisotropy, that is, in the inclined one direction, can be improved by the second optical advancing direction converting means.

The liquid crystal display device according to claim 3, wherein the second light traveling direction converting means is an optical axis converting plate constituted by an anisotropic scattering element.

18. The liquid crystal display device according to claim 17, wherein the optical axis conversion plate is formed by stacking materials having different refractive indices in multiple layers.

As this configuration, as the second light traveling direction converting means, an optical axis conversion plate constituted by an anisotropic scattering element, more specifically, a film in which materials having different refractive indices are laminated in multiple layers, proceeds out of the thermal viewing direction. The existing light can be scattered by the optical axis conversion plate, and the traveling direction of a part of the light can be converted into the thermal visual direction, and the viewing angle characteristic in the thermal visual direction can be improved.

The liquid crystal display device as claimed in claim 3, wherein the second light traveling direction converting means is an optical axis converting plate formed by an asymmetrical refractive element.

20. The liquid crystal display device according to claim 19, wherein the optical axis conversion plate is a sawtooth-shaped asymmetric refraction element.

With this configuration, the viewing angle characteristic in the thermal viewing direction can be improved, and only a part of the angles are not darkened locally.

20. The liquid crystal display device according to claim 19, wherein the optical axis conversion plate is an asymmetric microlens.

This configuration also improves the viewing angle characteristic in the thermal viewing direction, and can easily improve productivity.

The liquid crystal display device according to claim 17, wherein antireflection means for preventing reflection of external light is provided.

According to this configuration, the scattering behavior generated in the optical axis conversion plate constituted by the anisotropic scattering element can be prevented from adversely affecting the display by the antireflection means, and the lowering of the contrast of the liquid crystal display element can be prevented.

The liquid crystal display device according to claim 22, wherein the anti-reflection means is an anti-reflection film formed on the surface of the polarizing plate disposed outside the front substrate.

In this configuration, the antireflection film is formed by the AR process, and the antireflection film can prevent external light reflection and can not adversely affect the display.

The liquid crystal display device according to claim 22, wherein the antireflection means is an uneven portion formed on the surface of the polarizing plate disposed on the outer side of the front substrate.

By this structure, reflection of external light can be prevented by the uneven part.

23. The liquid crystal display device according to claim 22, wherein the anti-reflection means uses circular polarizers as polarizing plates on both sides of the front and rear surfaces disposed on the outside of the rear and front substrates.

According to this configuration, when reflection occurs in the optical axis conversion plate under the circular polarizing plate, since the light passes through the λ / 4 plate twice in a reciprocating direction, the wavefront rotates 90 degrees, and as a result is absorbed by the polarizing plate, external light reflection occurs. Can be prevented.

The scattering angle width of the anisotropic scattering element according to claim 17, wherein the anisotropic scattering element has a plurality of pixels and has a length of 400 µm or less in a direction in which the direction of light travel is changed by the second light traveling direction converting means of the pixels. It can be set as the liquid crystal display element which is 70 degrees or less.

The scattering angle width of the anisotropic scattering element according to claim 17, wherein the anisotropic scattering element has a plurality of pixels and has a length of a direction in which the light traveling direction of the pixel is changed by the second light traveling direction converting means. It is 40 degrees or less, and it can be set as the liquid crystal display element.

By restricting in this way, the image projected on the display surface of the liquid crystal display element can be prevented from being blurred.

The liquid crystal display device according to claim 3, wherein when the refractive index anisotropy of the liquid crystal is Δn and the thickness of the liquid crystal layer is d, the product Δnd is 0.42 or less.

The liquid crystal display device according to claim 3, wherein when the refractive index anisotropy of the liquid crystal is Δn and the thickness of the liquid crystal layer is d, the product Δnd is 0.40 or less.

According to this configuration, when Δnd is 0.42 or less, more preferably 0.40 or less, good display without gradation inversion and no phenomenon of gradation breakage is realized.

6. The liquid crystal display device according to claim 5, wherein the liquid crystal layer is twist-oriented such that the twist angle of the liquid crystal molecules is 90 degrees or more and 100 degrees or less.

Thus, by regulating the twist angle of liquid crystal molecules to 90 degrees or more and 100 degrees or less, the liquid crystal display element which shows the favorable display which a contrast does not fall is realized.

6. The liquid crystal display device according to claim 5, wherein when the display surface is viewed from the front, the rear substrate is subjected to alignment processing from the lower right to the upper left direction and the front substrate from the upper right to the lower left direction. Can be.

According to this configuration, when the display surface is viewed from the front, the long axis direction of the liquid crystal molecules can be made upward. In the liquid crystal display device of the present invention, since the viewing angle characteristic of the direction in which the gray level inversion occurs is improved by the second light advancing direction converting means, the direction of the long axis of the liquid crystal molecules, which is the direction in which the gray level inversion occurs, is upward, The viewing angle characteristic is improved from the downward direction, and therefore, the display screen can be comfortably observed when the liquid crystal display element is used as the OA monitor.

6. The liquid crystal display device according to claim 5, wherein when the display surface is viewed from the front, the rear substrate is subjected to alignment processing from the upper right to the lower left direction and the front substrate from the lower right to the upper left direction. Can be.

Also in this configuration, the direction in which grayscale inversion occurs is upward, the viewing angle characteristic in the upward direction is improved, and the display characteristic is improved.

The liquid crystal display device according to claim 3, wherein the liquid crystal molecules in the middle portion in the thickness direction of the liquid crystal layer are inclined in an upward direction with respect to the front substrate in a state in which a halftone is displayed. You can do

According to this configuration, the viewing angle characteristic in the upward direction in which the grayscale inversion occurs can be improved by the second optical advancing direction converting means.

The liquid crystal display device according to claim 3, further comprising light collecting means for collecting light in an angular region in which the amount of light is reduced by said second light traveling direction converting means.

According to this configuration, the reduced brightness can be compensated for by the condensing means even at an angle where the brightness locally decreases by the light traveling direction conversion means.

The liquid crystal display device according to claim 34, wherein the second light traveling direction converting means and the light collecting means are complementary.

In this way, since the second light traveling direction converting means and the condensing means are complementary, the light amount reduced by the second light traveling direction converting means can be supplemented by the light collecting means.

35. The liquid crystal display device according to claim 34, wherein the condensing means condenses the light into an angular region centered on the front direction in the normal direction of the display surface.

According to this structure, the brightness which declines especially in the angular area centered on a front direction can be compensated by a light converging means.

The liquid crystal display device according to claim 3, further comprising a light collecting means for collecting light in a direction other than the thermal visual direction.

The liquid crystal display device according to claim 37, further comprising means for condensing the light into an angular region centered on the front direction in the normal direction of the display surface.

With this arrangement, the light collecting means can condense the light to the angular region centered on the front direction in the normal direction of the display surface, and thus the light near the front with good visual characteristics increases, so that the whole view of the liquid crystal display element can be obtained. The characteristic is improved.

The above object is also achieved by a liquid crystal display device characterized in that a backlight unit is arranged on the back side of the liquid crystal display device according to claim 3, and the light amount angle distribution of the backlight unit has a plurality of peaks.

In addition, the above object is a backlight unit is disposed on the back side of the liquid crystal display device according to claim 3, wherein the backlight unit is a light converging means for condensing light in a region where the amount of light is reduced by the second light advancing direction converting means. It is achieved by a liquid crystal display device characterized in that is provided.

According to this configuration, since the backlight unit irradiates the light having a strong amount of light to the area where the amount of light decreases by the condensing means, there is no part where the brightness is locally lowered on the display surface, and the display surface is observed without feeling discomfort. can do.

40. The liquid crystal display device according to claim 39, wherein the backlight unit has a plurality of peaks in which the angle distribution of the light amount compensates for the light amount reduced by the second light advancing direction converting means. .

According to this configuration, since the plurality of peaks coincide with the angular region in which the amount of light is decreasing, the display surface of the liquid crystal display device has a gentle light amount distribution.

40. The liquid crystal display of claim 39, wherein the backlight unit has a light guide plate, the light guide plate includes scattering means for scattering light, and directional reflecting means for selectively emitting light in a predetermined direction. You can do it with a device.

According to this configuration, the scattering means scatters the light, and the directional reflecting means emits the light in a predetermined direction, whereby the display surface is smoothly distributed.

40. The apparatus of claim 39, wherein the backlight unit has a light guide plate having directional reflecting means for selectively emitting light in a predetermined direction, and the directional reflecting means has a plurality of concave portions formed in the light guide plate. The concave portion of the liquid crystal display can have a plurality of inclinations.

Even with this configuration, since the plurality of recesses have an inclination, light can be selectively emitted in a predetermined direction.

40. The apparatus of claim 39, wherein the backlight unit has a film having directional reflecting means for selectively emitting light in a predetermined direction, the directional reflecting means having a plurality of recesses formed in the film, The concave portion can have a liquid crystal display device characterized by having a plurality of inclinations.

According to this configuration, light can be emitted in a predetermined direction by varying the inclination of the plurality of recesses.

The above object is also provided on the rear side of the liquid crystal display device according to claim 3, and the light collecting means for condensing light is provided in a region where the amount of light is reduced by the second light advancing direction converting means. Achieved by the backlight unit.

According to this configuration, since light having a strong amount of light is collected in a region where the amount of light is reduced by the light collecting means provided in the backlight unit, the overall viewing angle characteristic of the liquid crystal display element can be improved.

<Detailed Description of the Preferred Embodiments>

Embodiments of the present invention will be described in detail.

[First Embodiment]

Embodiments 1 and 2 of the present invention will be described with reference to FIGS. 4 to 16. However, the same parts as in the prior art are denoted by the same reference symbols, and detailed description thereof will be omitted. In addition, as in the prior art, the case where the liquid crystal molecules 8c in the middle portion of the liquid crystal layer 108 are inclined downward with respect to the front substrate 109 will be described.

(Example 1)

A first embodiment of the present invention will be described with reference to FIGS. 4 and 5. 4 is a side cross-sectional view of a liquid crystal display device according to a first embodiment of the present invention, and FIG. 5 is a cross-sectional side view of the main portion of FIG. In the liquid crystal display device according to the first embodiment of the present invention, as shown in FIGS. 4 and 5, the liquid crystal layer 108 is sandwiched and supported between a pair of substrates 107 and 109 arranged in parallel, and the liquid crystal layer The liquid crystal molecules in (108) are twisted at 90 degrees by orienting the substrates (107, 109), and are provided with a first light traveling direction converting means and a second light traveling direction converting means. Doing. The first light traveling direction converting means is constituted by the phase compensation plates 106 and 106 affixed to the outer surfaces of the pair of substrates 107 and 109. The second optical traveling direction converting means is constituted by the optical axis converting plate 110 affixed to the front phase compensating plate 106. The polarizing plates 105 and 105 are attached to the back phase compensation plate 106 and the optical axis conversion plate 110, respectively. In addition, the backlight unit 104 is disposed on the rear side of the rear polarizing plate 105, and the liquid crystal display device is constituted by the backlight unit 104 and the liquid crystal display element.

The phase compensation plate 106 is a hybrid orientation of the optical medium 6, and the optical medium 6 is a discotic liquid crystal material having optically negative refractive index anisotropy. The phase compensation plate 106 can improve the viewing angle characteristic of the liquid crystal display element, but cannot improve the viewing angle characteristic in one direction like the other direction. One of these directions is referred to as the thermal visual direction (R).

In addition, the optical axis conversion plate 110 has a thermal visual direction R in a direction other than the thermal visual direction R, specifically, a direction in which a part of the normal light traveling near the front side is refracted, diffracted, or scattered. Convert to The phenomenon of gray level inversion in the thermal visual direction R is caused by a very small light quantity difference, and the gray level inversion is compensated by some light whose direction of travel is converted by the optical axis conversion plate 110.

With such a configuration, the phase compensation plate using the discotic liquid crystal oriented in the hybrid direction suppresses the direction in which the viewing angle characteristic is inferior (column visual direction R) in only one direction and the viewing angle characteristic in the one direction by the optical axis conversion plate. It is possible to improve the compensation in all directions, and by using these two methods simultaneously, the viewing angle characteristic in all directions is improved, and the distinctive effect is exerted.

11 is a chromaticity diagram of the liquid crystal display element in Example 1 of this invention. As shown in FIG. 11, the liquid crystal display element of this invention combines the two methods of the phase compensation plate 106 and the optical axis conversion plate 110, and the downward color change is also compensated. However, in order to correct the color change, it is necessary to design the phase compensation plate 106 and the optical axis conversion plate 110 to compensate for the gray level inversion, depending on the case.

In addition, although the hybrid orientation discotic film is used for a phase compensation plate, this invention is not limited to this, As described in Example 1-8 mentioned later, a phase compensation plate formed of the rod-shaped liquid crystal material. It is also possible to use. The present invention improves the viewing angle characteristic in a direction except one direction by the first optical traveling direction conversion means such as a phase compensation plate, and compensates the viewing angle characteristic in one direction according to the optical axis conversion plate which is the second optical traveling direction conversion means. It is.

In addition, the optical axis conversion plate 110 may not be disposed between the phase compensation plate and the polarizing plate, and may be disposed anywhere outside the substrate. For example, as shown in FIG. 14, the front substrate 109 and the phase compensation plate 106 may be disposed. ) Or may be disposed outside the outer polarizing plate 105. In addition, it is preferable to include an antireflection means in the optical axis conversion plate disposed outside the polarizing plate. In addition, although the downward direction is made into the visual reverse direction in this Embodiment 1, it is not limited to this, You may reverse up and down, and the visual reverse direction may be left-right direction.

As described above, the first light advancing direction converting means for improving the viewing angle characteristic except the thermal visual direction in any one direction, and the second advancing direction of the part of the light propagating out of the thermal visual direction to the thermal visual direction The liquid crystal display device having the optical advancing direction converting means improves the viewing angle characteristic in all directions.

Below, the specific example of Example 1 is illustrated and demonstrated to Example 1-1 to Example 1-8.

(Example 1-1)

In Example 1-1, Lumisty Film Y3060 (trade name, Toyo Chemical Co., Ltd.), which is an anisotropic scattering element, was used as the optical axis conversion plate 110.

The Lumisti film Y3060 is formed by stacking materials having different refractive indices in multiple layers, and has a property of scattering light in an angular region of 30 degrees to 60 degrees. In more detail, although the light upwards than the front direction S (refer FIG. 5) and the front direction S is let through as it is, the propagation direction of a part of the light of 30 degrees to 40 degrees below the front direction S as it is. It has the characteristic of refracting 20 degrees downward more than an incident angle, and isotropically scattering the light of 40 degrees to 60 degrees below. Incidentally, the angular region of 30 to 60 degrees is called a scattering angle region.

When the film is used, the light of visual inversion of 40 degrees or more downward is scattered and weakened, and a part of normal light without the gray level inversion of 30 to 40 degrees downward is bent 20 degrees below the angle of incidence and converted into the visual inversion direction. Therefore, gradation inversion can be eliminated. In addition, the gray scale inversion was similarly eliminated for the types other than the Lumisti film Y3060. The scattering angle region and the scattering angle width can be adjusted by adjusting the structures of various kinds of lumisti films. In addition, a scattering angle width means the range of 30 degree | times, in the case of Lumist film Y3060. If the scattering angle width is large, the gradation inversion is greatly reduced, but there is a problem that the image is blurred as described later. In addition, by increasing the scattering angle region from the front direction downward, the phenomenon of gradation inversion is greatly reduced.

As described above, examples of the anisotropic scattering element that bends light at a specific incident angle due to scattering behavior include Lumaxis (trade name, manufactured by Micro Sharp) in addition to the lumisti film.

In addition, when an anisotropic scattering element exhibiting scattering behavior is used, external light is scattered by the anisotropic scattering element, and the scattered light adversely affects the display of the liquid crystal display element, and there is a problem that the contrast of the liquid crystal display element is lowered. In order to prevent such a problem from occurring, when anisotropic scattering elements are used, it is preferable to use antireflection means for the liquid crystal display elements.

The anti-reflection means may include an anti-reflection film formed on the surface of the polarizing plate 105 by anti-reflection (AR) treatment, an uneven portion formed by antiglare treatment on the surface of the polarizing plate 105, or both front and rear polarizing plates ( It can be configured by using 105 and 105 as circular polarizing plates. These antireflection means can prevent the lowering of the contrast of the liquid crystal display element.

The circular polarizing plate is a combination of a polarizing plate and a λ / 4 plate, and when reflection occurs in the optical axis conversion plate below the circular polarizing plate, the light passes through the λ / 4 plate twice in a round trip, so that the wavefront is 90 degrees. It rotates, and as a result it is absorbed by a polarizing plate, it has the characteristic that external light reflection does not occur, and especially the antireflection effect was seen.

In addition, when the anisotropic scattering element is used for the optical axis conversion plate 110, the directivity of the light is disturbed, which causes a problem that the image projected on the display surface D is blurred in the vertical direction. This problem is remarkable in the case of a high-definition pitch, and the length in the vertical direction of the pixel is 100 when the direction in which the light travels the second light advancing direction conversion means is changed, for example, the column visual direction is made downward. It is appropriate to suppress the scattering angle width to 40 degrees or less in the case of 占 퐉 or less, and it is necessary to suppress the scattering angle width to 70 degrees or less in the length of the pixel in the vertical direction.

The optical axis converting plate 110 using the anisotropic scattering element as described above has the light traveling in the front direction S in the normal direction of the display surface D of the liquid crystal display device and the light traveling upward from the front direction S as it is. It advances and only the light which goes below the front direction S is bent downward. For this reason, a dark part locally arises about 20 degrees downward from the front direction S, and an observer may feel a sense of incongruity. This solution will be described in Examples 1-3.

(Example 1-2)

In Example 1-2, a film having an asymmetrical refraction element, more specifically, a sawtooth cross-sectional shape, was used for the optical axis conversion plate 110. 6 is a side view showing an optical axis conversion plate of Example 1-2 of the present invention. As shown in FIG. 6, the optical-axis conversion plate 110 which used the asymmetric refraction element is the tooth-shaped directional film IDFII (brand name, manufactured by Toyo 3M) whose cross-sectional shape is asymmetric in a vertical direction.

In the directional film IDFII as the optical axis conversion plate 110, as shown by the thick line or the thin line in FIG. 6, the light traveling upward from the front direction S is upwardly or further upward as it is. As shown by the dashed-dotted line, the light traveling in the front direction S or the light traveling in the upper direction downward than the front direction S as shown by the dotted line is converted downward or further downward to proceed. This is characterized by the fact that the intensity of light continuously changes with respect to the angle. For this reason, as in Example 1-1, only a part of angles are not darkened locally, but the brightness of the entire display surface D is lowered. In addition, in order to solve the problem that this whole brightness falls, it is possible to improve the brightness of the whole liquid crystal display element by using the backlight unit demonstrated in Example 1-4 mentioned later.

In addition, when the cross-sectional shape of the directional film IDFII is a periodic sawtooth shape as shown in Fig. 6, the light interferes with the pitch of the liquid crystal element by this periodicity to generate a moire shape. Therefore, it is preferable to make the cross-sectional shape of the said directional film (IDFII) into the sawtooth shape without a period, and to prevent a moiré shape from generating.

In addition, although the saw tooth-shaped optical axis conversion plate was used in the present Example 1-2, it is not limited to this, What is necessary is just an asymmetric refractive element, For example, an asymmetric microlens can be used.

(Example 1-3)

In Embodiments 1-3, two optical-axis conversion plates are attached to the front and rear of the liquid crystal display element, thereby correcting a decrease in the brightness of the liquid crystal display element by the optical axis conversion plate. 7 is a side sectional view of main parts of the liquid crystal display device of Example 1-3 of the present invention. In Examples 1-1 and 1-2, the optical axis conversion plate 110, which is the Lumisti Film Y3060 or the directional film IDFII, is attached to the front of the liquid crystal display device. There was an angle of decreasing the brightness, there was a problem of feeling a sense of incongruity.

Thus, the liquid crystal display device of Embodiments 1-3 includes light converging means which compensate for each other to compensate for the reduced brightness. As shown in Fig. 7, the condensing means is constituted by the optical axis converting plate 110 'attached to the rear phase compensating plate 106. As shown in Figs. In addition, in the present exemplary embodiment 1-3, the optical axis conversion plate 110 'and the optical axis conversion plate are also used by using the Lumisty film Y3060 as the optical axis conversion plate 110 using the Lumisti film Y3060. 110 is being compensated for each other. With such a configuration, light is collected by the rear optical axis conversion plate 110 ′ at an angle at which the density of the light becomes small in the front optical axis conversion plate 110, thereby supplementing the reduced brightness. In addition, in order to collect the light irradiated from the backlight unit into a region of low density of light, for example, the light collecting film of the backlight unit may be asymmetrical or the shape of the light guide plate of the backlight unit may be asymmetrical (Example 1-4). .

In Example 1-4, the brightness of the front portion of the liquid crystal display device is reduced by adjusting the light distribution of the backlight unit.

In Example 1-3 described above, the optical axis converting plate 110 'was attached to the rear phase compensating plate 106 to improve the visual characteristics of the liquid crystal display device. The back light unit 104 was designed.

Fig. 12A is a light amount distribution in the case of combining with the liquid crystal display element of the structure of Example 1-1 using the backlight unit which has not adjusted the light amount distribution. However, the optical axis conversion plate used Y2070 of Lumisty Film. In addition, Y2070 of the Lumisti film is a film having a scattering angle width of 50 degrees and a scattering angle region of 20 degrees to 70 degrees. It can be seen from FIG. 12 (a) that there is a problem that light decreases from 20 degrees to 40 degrees below.

Thus, a backlight unit having a light amount distribution as shown in FIG. 12 (b) was prepared. In FIG. 12A, in order to compensate the amount of light in the angular region in which the luminance decreases, the backlight unit has a plurality of peaks.

The structure of the backlight unit having such a characteristic is shown in FIG. 8 is a schematic side cross-sectional view of the backlight unit of Example 1-4 of the present invention. In general, the backlight unit includes a side light 101 including a lamp and a reflector, a light guide plate 102 for converting light from the side light 101 into a planar light source, and a light collecting film disposed on the front side of the light guide plate 102. 103 and the like, and dots 111 serving as scattering means are printed on the surface of the light guide plate 102 by white scattering ink. In normal backlight, only the printing of the dot 111 of this scattering body is performed.

However, as shown in FIG. 8, in the backlight unit 104 of the present invention, a recess 112, which is a directional reflecting means, is formed on the rear side of the light guide plate 102, and the recess 112 is a light guide plate 102. Light may be partially reflected to selectively irradiate light in a predetermined direction. In the first embodiment 1-4, the angle of the recess 112 is adjusted to emit light propagating through the light guide plate 102 in the range of 20 degrees to 40 degrees below, as shown in Fig. 12B. Similarly, the light quantity distribution is configured to have a peak around 20 to 40 degrees. In addition, the height of the peak of the light amount can be adjusted by adjusting the density (number) of the recesses 112, and since the light amount is strong in the region near the side light 101, the density (number) of the recesses 112 is small. Doing. In combination with such a back light unit and a liquid crystal display device using a lumisti film, a liquid crystal display device having a characteristic of light intensity distribution is obtained as shown in FIG. It did not occur, and the viewing angle characteristic improved.

In addition, the backlight unit of the present invention is not limited to the above structure, and a plurality of directional reflecting means may be formed. For example, as shown in FIG. 9, the recess 112 may be used instead of the printing of the dot 111. You may form the recessed part 112 '(cutting structure) with a different inclination. FIG. 9 illustrates a recess 112 'formed at a front side of the light guide plate 102 to collect light near a main peak, that is, the front side. In such a configuration, the peak position of the light quantity distribution of the backlight unit can be controlled, and the display unit of the liquid crystal display device can have a smooth light quantity distribution by providing the backlight unit in the liquid crystal display element. The recess 112 'may be formed on the front side or the back side of the light guide plate 102, and the light quantity distribution is formed by forming two types of recesses having different inclinations on the back side of the light guide plate 102. Two peaks of can be made. In addition, the type of inclination may be two or more types.

In addition to directly cutting the light guide plate to form a concave portion, as shown in FIG. 10, a film 112b having a directional reflecting means and having a light intensity distribution in a desired direction may be attached. Background Art Conventionally, a prism sheet having one kind of inclined structure and collecting light with directivity in the front direction has been commercially available.

However, the inclination of the prism sheet forms two types, for example, triangular irregularities having a steep cross section and gentle irregularities, and the backlight unit has a plurality of backlight units. The light amount distribution having a peak is shown. By providing the backlight unit having such a configuration in the liquid crystal display element, a liquid crystal display device having the characteristics as shown in Fig. 12C can be obtained. In addition, since the backlight unit having such a characteristic merely attaches a film to the light guide plate, the desired backlight characteristic can be easily obtained.

(Example 1-5)

The present embodiment 1-5 combines a light converging means for condensing in an angular region centered on the front direction in the normal direction of the display surface of the liquid crystal display element, and a liquid crystal display element using an optical axis conversion plate. As described in Example 1-1, the wide viewing angle of the optical axis conversion plate of the present invention is a method of rotating the light by bending the light in the vicinity of the front in a direction inferior to the visual direction. At this time, the visual characteristics in the thermal visual direction are improved by rotating good light near the front side in the thermal visual direction. On the other hand, in Example 1-5, the light near the front having a good visual characteristic is increased to improve the overall visual characteristic. In addition, not only the light near the front face but also the light having good visual characteristics (light outside the thermal viewing direction) can also be improved to improve the overall visual characteristics.

In Example 1-5, in order to increase the light with a good visual characteristic, as shown to the virtual line of FIG. 4, the prism sheet 113 as a condensing means was arrange | positioned to the backlight unit 104. As shown in FIG. As the prism sheet 113, BEFII manufactured by Sumitomo 3M was used. In addition, a prism sheet including a polarization conversion element may be used.

Further, in the case of using Lumisti Film Y3565 (trade name) in Example 1-1, gray level inversion occurred slightly in the downward direction. This is because the light of the peripheral part is relatively strong, and even if the light near the front side is bent by the optical axis conversion plate and mixed with the light of the peripheral part, the light of the peripheral part whose gray level is reversed cannot be supplemented.

However, when the prism sheet (BEFII) of this embodiment 1-5 is used, since the light in the vicinity of the front with good visual characteristics can be increased by the prism sheet BEFII, sufficient visual characteristics can be obtained even with the Lumistifilm Y3565 film. It is obtained, and gradation inversion does not occur.

(Example 1-6)

In Example 1-6, Δnd of the liquid crystal material was optimized and the twist angle was optimized.

As described above, the present invention is to cover the viewing angle characteristic in the gradation inversion direction by converting light having good characteristics near the front side into the gradation inversion direction. In other words, the smaller the angular region for gray scale inversion, the better the overall characteristics.

By the way, in the TN type liquid crystal mode, it is said that the overall characteristic is optimal in the case of Δnd = 0.472 in principle. Δn is the refractive index anisotropy of the liquid crystal, and d is the thickness of the liquid crystal layer. However, in this case, gray scale inversion occurs near 30 degrees downward from the front direction S. FIG.

According to the studies of the present inventors, it is realized that the angle at which gray level inversion occurs is changed outward by decreasing Δnd further. That is, if Δnd = 0.42, the gray scale inversion angle is shifted outward from the front direction S to 40 degrees, and if Δnd = 0.4, the gray scale inversion angle changes outward from the front direction S to 45 degrees. It was. Thus, viewing angle improves by making the refractive index anisotropy of a liquid crystal and thickness of a liquid crystal layer small.

In addition, in the case of the liquid crystal display device having the optical axis conversion plate, there is no gradation inversion at Δnd = 0.42, but there is a phenomenon in which the gradation of the image is still broken. However, at DELTA nd = 0.4, good display can be achieved without causing the gray scale to be broken. As a result, Δnd is preferably 0.42 or less, and Δnd is not more than 0.4 in gradation cracking, and better visual characteristics are obtained.

This phenomenon occurs in the same manner when the twist angle is changed, and the viewing angle characteristic can be improved by making the twist angle of the liquid crystal molecules 8 larger than the normal twist angle. However, when the twist angle exceeds 100 degrees, the phenomenon of contrast decreases, so the optimum twist angle is 90 degrees or more and 100 degrees or less. In this manner, Δnd of the liquid crystal material can be optimized and the twist angle can be optimized.

(Example 1-7)

Embodiment 1-7 relates to a liquid crystal display device in which the arrangement direction of the liquid crystal display elements is optimized. Fig. 13 is a schematic perspective view showing an example of using the liquid crystal display element in Example 1-7 of the present invention as an OA monitor.

In general, when the liquid crystal display element is used as an OA monitor, since the liquid crystal display element is provided on the disk, the direction in which the gray scale inversion is generated is directed downward so that there is no problem in observing the display surface D. FIG.

However, since the liquid crystal display element of the present invention uses an optical axis conversion plate, the display characteristics in the downward direction are good, and the display characteristics in the upward direction are lower than those in the downward direction. Therefore, in arranging the liquid crystal display element, the reverse direction of the up and down direction can obtain better display characteristics.

And, in order to raise the direction in which the gray scale inversion occurs, as shown in Fig. 13, when the rubbing process is viewed from the observation direction, the rear substrate 107 faces the upper left from the lower right, and the front substrate 109 This is accomplished by performing in the direction from the upper right to the lower left. Alternatively, the rear substrate 107 is directed from the upper left to the lower left, and the front substrate 109 is also achieved by performing the rubbing treatment from the lower right to the upper left. The alignment treatment is not limited to rubbing but may be photoalignment treatment. At this time, the direction of the orientation treatment is a direction in which pretilt is generated.

By rubbing the substrates 107 and 109 in this manner, the liquid crystal molecules 8c in the intermediate portion are inclined upward in the direction perpendicular to the substrate in the halftone display state. This upward direction is a direction in which gray scale inversion has occurred conventionally, but the visual characteristic is improved by the optical axis conversion plate of the present invention, and the visual characteristic in the upward direction is improved. In addition, when the liquid crystal display device is used as a small display panel of a video camera, it is also possible to arrange the direction in which the gray level inversion occurs in the left and right directions, and convert the second light traveling direction in the direction in which the gray level inversion occurs. By converting light by the optical axis conversion plate which is a means, the viewing angle characteristic of the left-right direction can be improved.

(Example 1-8)

In Example 1, a phase compensation plate formed of a discotic liquid crystal material of hybrid orientation was used. In Example 1-8, instead of a discotic liquid crystal material, phase compensation formed of a rod-shaped liquid crystal material of hybrid orientation was used. Plates were used. The phase compensation plate is formed by solidifying a rod-shaped liquid crystal oriented in a hybrid manner, has a birefringence, and the birefringence is changed in the thickness direction.

Since the birefringence changes in the thickness direction of the phase compensation plate formed by the rod-shaped liquid crystal material, the phase difference varies depending on the angle of incident light, and the effect of visual compensation is large. In addition, since the phase compensating plate has a smaller compensating effect in the uniaxial direction than the phase compensating plate formed by the discotic liquid crystal material, the visual characteristics of the thermal visual direction R become worse. There is an advantage that it can produce with low cost than the formed phase compensation plate. Thus, by using the phase compensation plate formed from the rod-shaped liquid crystal oriented hybridly, a part of the light traveling in the direction other than the thermal visual direction is converted to the thermal visual direction, and the viewing angle characteristic of the entire liquid crystal display element is improved.

(Example 2)

In the present embodiment, a vertical alignment liquid crystal display device is used.

(Example 2-1)

In Example 2-1, a vertical alignment liquid crystal display device having a second light traveling direction converting means for converting a part of the light traveling in a direction in which the brightness is not reduced to a direction in which the brightness is decreasing. Explain.

Fig. 15 is a side sectional view of a vertical alignment liquid crystal display device in Example 2-1 of the present invention. As shown in Fig. 15, in the vertical alignment liquid crystal display device, the liquid crystal layer 115 is sandwiched and supported between the pair of substrates 107 and 109, and the second light advancing direction described later on the front substrate 109 is shown. An optical axis conversion plate 110 that is a conversion means is provided. In addition, polarizing plates 105 and 105 are attached to the rear substrate 107 and the optical axis conversion plate 110. In addition, the liquid crystal layer 115 is vertically aligned by vertically treating the substrates 107 and 109. In addition, the liquid crystal display element of this embodiment is not provided with the phase compensation plate serving as the first light traveling direction converting means.

In the liquid crystal display device, when voltage is not applied, the liquid crystal molecules in the liquid crystal layer 115 are vertically aligned with respect to the substrates 107 and 109. When voltage is applied, the liquid crystal molecules are arranged horizontally with respect to the substrates 107 and 109. To change. At this time, the inclined direction of the liquid crystal molecules is changed by applying irregularities to the pixel electrodes (not shown) formed on the substrate 109 or forming slits. Fig. 16 is a sectional side view of the main portion of a vertical alignment liquid crystal display device in Example 2-1 of the present invention. In the above-described example, in order to improve the visual characteristics also in the vertical alignment liquid crystal display device, as shown in Fig. 16, the orientation orientation of the liquid crystal molecules 8 in the liquid crystal layer 115 by a method such as rubbing or electric field inclination. It's called a multidomain with anisotropy. This multi-domain liquid crystal display device is characterized in that one pixel is divided into two or more parts, and each part has a different characteristic inclined direction, so that the visual characteristics are uniform. Such a vertical alignment type liquid crystal display element does not generate gray scale inversion as in a TN type liquid crystal display element, but has a problem in that brightness is greatly reduced when viewed in the left and right directions.

For example, when a photographer photographs by a video camera, since the video camera is generally held to the right, the display panel constituted by the liquid crystal display element is often observed in the left direction. Therefore, when the liquid crystal display element is used as a display panel of a video camera, it is necessary to improve the brightness in the left direction.

Therefore, in the liquid crystal display device according to the present embodiment 2-1, the optical axis conversion plate 110 serving as the second optical advancing direction conversion means for converting the traveling direction of part of the light traveling in the front direction S to the left direction. ) Is attached to the front substrate 109 so as to compensate for the decrease in brightness in the left direction. In this way, by converting a part of the light traveling in the direction in which the brightness is not reduced by the optical axis conversion plate 110 in the direction in which the brightness is decreasing, the brightness in the decreasing direction can be compensated. In addition, by stacking the optical axis conversion plate 110 for converting the traveling direction of the light to the left direction and the optical axis conversion plate 110 for converting the right direction, it is also possible to be configured to improve the brightness of both the left and right. In addition, when a part of the light traveling in the front direction S is converted to the left direction by using the optical axis conversion plate 110, the brightness of the front part is lowered. However, as described in Example 1-4, the backlight unit By adjusting the light quantity distribution, the reduced brightness can be compensated for.

(Example 2-2)

In Example 2-1, the liquid crystal display element of the vertical alignment type is provided with a second light traveling direction converting means for converting a part of the light traveling in the direction in which the brightness is not reduced to the direction in which the brightness is decreasing. Although described, the process cost is required to divide the pixels. Thus, in order to inexpensively manufacture the vertical liquid crystal display device of the present Example 2-2, the liquid crystal molecules in the liquid crystal layer have anisotropy in the inclined direction in which the liquid crystal molecules are inclined in one direction. Since the vertical liquid crystal display device of Example 2-2 is anisotropic in the inclination direction of the liquid crystal molecules, gray level inversion occurs in the direction in which the liquid crystal molecules are inclined. Therefore, when the viewing angle characteristic decreases due to the gray scale inversion, the optical axis converting plate is provided in the same manner as in the first embodiment, and the liquid crystal molecules convert light in the inclined direction to improve the visual characteristics. In this way, even in the case of having the thermal visual direction in any particular direction, a part of the light traveling in a direction other than the thermal visual direction can be converted into the thermal visual direction by the optical axis conversion plate which is the second optical advancing direction converting means. The viewing angle characteristic of the liquid crystal display device is improved.

(Other matters)

(1) Although the liquid crystal display of the vertical alignment type has been described in the second embodiment, the optically compensated bend (OCB) type liquid crystal display has a problem of viewing angle characteristic deteriorating to the same brightness. In the OCB type liquid crystal display device, a bend-aligned liquid crystal layer is sandwiched and supported on a pair of substrates, and a retardation plate and a polarizing plate are laminated on the outside of the two substrates. Also in this OCB type liquid crystal display element, it is possible to improve the viewing angle characteristic by providing the optical axis conversion plate which is the second optical advancing direction converting means.

(2) In the present embodiment, the optical axis conversion plate 110 is used as an anisotropic scattering element, Lumisti film Y2070 (trade name), but is not limited to this, and may be an asymmetric refractive element having a sawtooth cross-sectional shape. .

(3) In the present embodiment, the viewing angle characteristic of the liquid crystal display element has been described. However, the present invention is not limited to this, and it is also possible to improve only the contrast in the front direction. For example, as shown in FIG. 17, the optical axis advancing plate 110 'shown in FIG. 7 is disposed, and the optical axis advancing plate 110' is disposed in place of the optical axis converting plate 110, so that the light proceeds upward. May be changed in the front direction, and the density of light in the front direction may be improved. As a result, it is possible to easily correspond to a device that requires an incognito mode such as a mobile phone.

According to the present invention as described above, the optical characteristics are compensated by the two light traveling direction conversion means. Since so-called two-stage compensation is made, it is possible to efficiently compensate for the optical characteristics.

In addition, when the viewing angle characteristic is improved by the two-step compensation, the front contrast can be improved by the first light traveling direction converting means, and the viewing angle characteristic of the downward direction can be improved by the second light traveling direction converting means. Both the characteristics of the and downward direction can be easily improved. Further, even if the performance of the hybrid film (the first light traveling direction converting means) varies due to the manufacturing process or the like, the second light traveling direction converting means can compensate for it, so that it is not necessary to use a precise hybrid film. Therefore, the range of selection of a hybrid film becomes wider, and it becomes possible to reduce the manufacturing cost of a liquid crystal display element.

According to the present invention, the viewing angle characteristic other than the column visual direction is improved by the first optical advancing direction converting means, and the viewing angle characteristic in the thermal visual direction is improved by the second optical advancing direction converting means. Therefore, the liquid crystal display device of the present invention improves the viewing angle characteristic in all directions by combining the first light traveling direction converting means and the second light traveling direction converting means.

Claims (45)

First light traveling direction converting means for compensating optical characteristics; Second light traveling direction conversion means for compensating optical characteristics that cannot be compensated by the first light traveling direction conversion means; Liquid crystal display device having a. The method of claim 1, And the optical characteristic is a viewing angle characteristic. A liquid crystal display device having a first optical advancing direction converting means for sandwiching a liquid crystal layer between a pair of substrates and improving a viewing angle characteristic except for a thermal viewing direction in any one direction. And a second light advancing direction converting means for converting a traveling direction of a part of the light traveling outside the column visual direction to the thermal visual direction. The method of claim 3, And the column visual direction in the first light advancing direction conversion means is the visual inversion direction. The method of claim 3, The liquid crystal molecules in the liquid crystal layer are twisted, and the thermal visual direction is in the long axis direction of the liquid crystal molecules located in the center of the thickness direction of the liquid crystal layer when a specific voltage is applied to the liquid crystal layer. Display element. The method of claim 3, The first light traveling direction converting means is a phase compensating plate affixed to the outside of at least one substrate, the phase compensating plate is made of a composition comprising an optical medium having optically refractive index anisotropy, the optical medium is The liquid crystal display device inclined in the thickness direction of the phase compensation plate, and the inclination angle thereof is changed in the thickness direction. The method of claim 3, And said first light advancing direction converting means is a phase compensating plate affixed on at least one outside of said substrate, said phase compensating plate has a birefringence, and said birefringence is changing in the thickness direction. The method of claim 6, And the optical medium in the phase compensation plate has optically negative refractive index anisotropy. The method of claim 8, And the optical medium is formed of a composition having discotic liquid crystallinity. The method of claim 6, And the optical medium in the phase compensation plate has optically positive refractive index anisotropy. The method of claim 10, And the optical medium is formed of a composition having liquid crystallinity. A liquid crystal display device comprising a liquid crystal layer sandwiched between a pair of substrates, And a second light traveling direction converting means for converting a part of the light traveling in the direction in which the brightness is not reduced to the direction in which the brightness is decreasing. The method of claim 12, And the liquid crystal display element is a vertical alignment type. The method of claim 12, And said liquid crystal display element is of type OCB. A liquid crystal display device having a liquid crystal layer sandwiched between a pair of substrates and having a thermal viewing direction in a specific direction, And a second light advancing direction converting means for converting a part of the light traveling in the column visual direction other than the column visual direction. The method of claim 15, And said liquid crystal display element is of a vertical alignment type, and that liquid crystal molecules in said liquid crystal layer are inclined with anisotropy by application of voltage. The method of claim 3, And said second light traveling direction converting means is an optical axis converting plate constituted by an anisotropic scattering element. The method of claim 17, The optical axis conversion plate is a liquid crystal display device, characterized in that the material having a different refractive index is laminated in multiple layers. The method of claim 3, And said second light traveling direction converting means is an optical axis converting plate constituted by an asymmetrical refractive element. The method of claim 19, The optical axis conversion plate is a liquid crystal display device, characterized in that the cross-section is a sawtooth asymmetric refractive element. The method of claim 19, And the optical axis conversion plate is an asymmetric microlens. The method of claim 17, A liquid crystal display device characterized by comprising anti-reflection means for preventing reflection of external light. The method of claim 22, And the anti-reflection means is an anti-reflection film formed on the surface of the polarizing plate disposed outside the front substrate. The method of claim 22, And the anti-reflection means is an uneven portion formed on the surface of the polarizing plate disposed outside the front substrate. The method of claim 22, The anti-reflection means is a liquid crystal display device characterized in that the polarizing plate on both sides of the front and back disposed on the outside of the substrate of the back and front as a circular polarizer. The method of claim 17, The scattering angle width of the anisotropic scattering element is 70 degrees or less when the length of the direction in which the traveling direction of the light is changed by the second light traveling direction conversion means of the pixel is 400 μm or less. Liquid crystal display device. The method of claim 17, The scattering angle width of the anisotropic scattering element is 40 degrees or less when the length of the direction in which the traveling direction of the light is converted by the second light traveling direction converting means of the pixel is 100 m or less. Liquid crystal display device. The method of claim 3, When the refractive index anisotropy of the liquid crystal is Δn and the thickness of the liquid crystal layer is d, the product Δnd is 0.42 or less. The method of claim 3, When the refractive index anisotropy of the liquid crystal is Δn and the thickness of the liquid crystal layer is d, the product Δnd is 0.40 or less. The method of claim 5, The liquid crystal display device is a liquid crystal display device, characterized in that the twist angle of the liquid crystal molecules are twist-oriented at 90 to 100 degrees. The method of claim 5, When the display surface is viewed from the front, the liquid crystal display device is subjected to alignment processing in the rear substrate from the lower right to the upper left and in the front substrate from the upper right to the lower left. The method of claim 5, When the display surface is seen from the front side, the liquid crystal display element is subjected to the alignment process in the lower left direction from the upper right side to the rear substrate and the upper right direction from the lower right side to the front substrate. The method of claim 3, The liquid crystal molecules of the middle part of the thickness direction of a liquid crystal layer become a posture inclined upward with respect to the front board | substrate in the state which shows halftone. The method of claim 3, And a light collecting means for collecting light in an angular region in which the amount of light is reduced by the second light advancing direction converting means. The method of claim 34, wherein And the second light traveling direction converting means and the light collecting means are complementary. The method of claim 34, wherein And said condensing means condenses to an angular region centered on a front direction which is a normal direction of a display surface. The method of claim 3, And a light converging means for collecting light in a direction other than the column visual direction. The method of claim 37, And means for condensing the light into an angular region centered on the front direction in the normal direction of the display surface. A liquid crystal display device comprising: a backlight unit disposed on the rear side of the liquid crystal display device according to claim 3, wherein the light angle angle distribution of the backlight unit has a plurality of peaks. The backlight unit is disposed on the back side of the liquid crystal display device according to claim 3, and the backlight unit includes a light converging means for condensing light in a region where the light quantity is reduced by the second light advancing direction converting means. A liquid crystal display device. The method of claim 39, And wherein the backlight unit has a plurality of peaks having an angular distribution of light amount to compensate for the light amount reduced by the second light advancing direction converting means. The method of claim 39, The backlight unit has a light guide plate, the light guide plate includes scattering means for scattering light, and directional reflecting means for selectively emitting light in a predetermined direction. The method of claim 39, The backlight unit has a light guide plate having directional reflecting means for selectively emitting light in a predetermined direction, the directional reflecting means has a plurality of recesses formed in the light guide plate, and the plurality of recesses have a plurality of inclinations. Liquid crystal display device characterized in that. The method of claim 39, The backlight unit has a film having a directional reflecting means for selectively emitting light in a predetermined direction, the directional reflecting means has a plurality of recesses formed in the film, the plurality of recesses have a plurality of inclinations A liquid crystal display device. A backlight unit, arranged on the back side of the liquid crystal display device according to claim 3, for condensing light in a region in which the amount of light is reduced by said second light advancing direction converting means.