JP2008176174A - Alignment layer, and liquid crystal display device and optical element using the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To form alignment grooves in a radial shape which is stable up to the vicinity of the center point, and to produce no significant difference of intervals between the central section and the external section in an alignment layer which is used in a liquid crystal display device etc. and with which a viewing angle is widened with the aid of the alignment grooves extending in the radial shape. <P>SOLUTION: In a liquid crystal panel 1 which is made to be uniformly viewed from any direction by making an alignment layer disposed on the confronting surface of a substrate have the alignment grooves 2 radiating with the radial shape from a center PO of each pixel A, and making an alignment layer disposed on the confronting surface of the other substrate have the alignment grooves 3 concentrically formed with respect to the center PO of each pixel A, the alignment grooves 2 radiating with the radial shape from the center PO of each pixel A are thinned out as going close to the center PO. Consequently the radial shape which is stable up to the vicinity of the center point is formed, and no significant difference of intervals between the central section and the external section is produced, and as a result a significant effect of widening the viewing angle is brought about. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an alignment layer used for a liquid crystal display device, an optical element and the like, and the liquid crystal display device and the optical element using the alignment layer.

In a liquid crystal device for display, it is a problem to increase the viewing angle, and many studies have been made from improvement of liquid crystal materials to alignment methods. Techniques that devise the alignment include a mask rubbing method in which alignment areas are divided and rubbing in the reverse direction, a rib method, a photo-alignment layer method, and the like. For example, Patent Document 1 uses a TN liquid crystal, and for each pixel, the alignment groove is concentric on one substrate side and radial on the other substrate side. It can be seen that the same condition is obtained and the viewing angle is enlarged. Even if the alignment groove is a ridge, the same effect can be obtained.
JP-A-6-324337

  In the above-described prior art, the viewing angle can be expanded by using the radial alignment grooves. However, if an appropriate groove interval is provided on the outer side of the pixel, the center (optical axis) side becomes full of grooves. If the center (optical axis) side is set to an appropriate groove interval, the groove on the outer side becomes sparse and the effect of orientation cannot be obtained.

  It is an object of the present invention to create a stable radial shape near the center of an alignment groove or ridge, and to prevent a large difference between the center side and the outer side in the interval between the alignment grooves or ridges. It is an object to provide an alignment layer capable of satisfying the requirements, a liquid crystal display device using the alignment layer, and an optical element.

  The alignment layer of the present invention is an alignment layer for contacting a birefringent layer containing a material having a uniaxial refractive index anisotropy to align the material, or an alignment groove extending radially in the plane direction of the alignment layer or The alignment groove or the protrusion is thinned out as it approaches the center of the alignment layer.

Further, the alignment layer of the present invention, in an alignment layer for aligning the material in contact with a birefringent layer containing a material having a uniaxial refractive index anisotropy, extends radially in the plane direction of the alignment layer, In addition, there are alignment grooves or protrusions that divide the region into m × 2 ⁿ (m and n are natural numbers) at equal angles, and the alignment grooves or protrusions are separated from the center of the alignment layer by a predetermined distance. When the number up to the radius point is m × 2 ⁿ every time, the number is increased to m × 2 ^{n + 1} outside the circumference of the radius.

According to the above configuration, a compound including a material having a uniaxial refractive index anisotropy, such as liquid crystal, is used for each pixel of a liquid crystal display device or an optical element used as a birefringence correction element of an optical disk in an optical pickup. An alignment layer for contacting the surface layer of the refractive layer and orienting the material in a predetermined direction extends radially from the center of the rectangular display region or the circular beam passage region to form alignment grooves or ridges. In addition, the alignment grooves or ridges are thinned out as they approach the center so that there is no significant difference between the alignment grooves or ridges between the center side and the outer side. That is, each of the alignment grooves or ridges equally divides a rectangular display region or a circular beam passage region into m × 2 ⁿ (m and n are natural numbers), and every time they are separated from the center by a predetermined distance, When the number to the radius point is m × ²ⁿ , new alignment grooves or ridges start to be formed between the alignment grooves or ridges up to the radius point, and the radial points start from the radius point. The number of alignment grooves or ridges increases to m × 2 ^{n + 1} .

  Therefore, a stable radial shape can be created in the alignment grooves or ridges to the vicinity of the center, and the gap between the alignment grooves or ridges is prevented from causing a large difference between the center side and the outer side as described above. be able to. As a result, it is possible to obtain a great effect on the expansion of the viewing angle in the liquid crystal display device and the birefringence correction in the optical pickup.

  Furthermore, in the alignment layer of the present invention, the alignment grooves or ridges are formed to be wider as they are separated from the center.

  According to said structure, the space | interval of the said alignment groove | channel or a protruding item | line can be made more uniform in a center side and an outward side.

  Moreover, the liquid crystal display device of the present invention has the alignment layer on the opposite surface side of one of the pair of substrates, and concentric alignment grooves or ridges on the opposite surface side of the other substrate. The alignment layer is formed, and the alignment groove or the ridge is made of nanoimprint.

  According to the above configuration, the selective rubbing takes man-hours, and the rubbing cannot be completely radial and concentric. On the other hand, by using the nanoimprint, the alignment grooves or projections that are completely radial and concentric are used. Articles can be created continuously.

  Therefore, a liquid crystal display device capable of expanding the viewing angle can be easily realized.

  Furthermore, the optical element of the present invention has the alignment layer on the opposing surface side of a pair of substrates, respectively, the birefringent layer is a liquid crystal as a material having the uniaxial refractive index anisotropy, By applying an electric field with a ring-shaped electrode, the liquid crystal axis is erected in the surface direction at the central portion and in the thickness direction toward the outer side, and solid in that state. It is fixed with the said curable resin made into.

  According to the above configuration, the liquid crystal is used as the material having the uniaxial refractive index anisotropy, and in the optical element used as the birefringence correction element of the optical disc in the optical pickup, the alignment layer is used, and the ring-shaped By applying an electric field with an electrode, preferably a solid electrode on the light emission side, and an annular side electrode on the incident side, the liquid crystal axis stands in the plane direction at the center and in the thickness direction as it goes outward. I can let you. In this state, the curable resin mixed with the material is cured to fix the birefringent layer, and the electrode is removed as necessary to complete the optical element.

  Therefore, the phase of the light beam on the outer peripheral side rather than the optical axis side advances, and the influence of the birefringence of the optical disc can be canceled, and an optical element that can improve the resolution can be realized.

  Further, the optical element of the present invention has the alignment layer on the opposing surface side of the pair of substrates, the material having the uniaxial refractive index anisotropy is a liquid crystal, and an electric field is generated by a ring-shaped electrode. By applying, the inclination of the axis of the liquid crystal is changed so as to be different between the central portion and the outer side.

  According to the above configuration, the liquid crystal is used as the material having the uniaxial refractive index anisotropy, and in the optical element used as the birefringence correction element of the optical disc in the optical pickup, the alignment layer is used, and the ring-shaped By applying an electric field using an electrode, preferably a solid electrode on the light emission side and the ring-shaped electrode on the incident side, the inclination of the axis of the liquid crystal is changed differently between the central part and the outer side, It can stand up in the thickness direction as it goes to the side.

  Therefore, the phase of the light beam on the outer peripheral side rather than the optical axis side advances, and the influence of the birefringence of the optical disc can be canceled, and an optical element that can improve the resolution can be realized. Moreover, the progress of the phase can be adjusted by changing the electric field strength.

  As described above, the alignment layer of the present invention is used for each pixel of a liquid crystal display device, an optical element used as a birefringence correction element of an optical disk in an optical pickup, and the like. In an alignment layer for contacting the surface layer of the resin layer containing the material having the material and aligning the material in a predetermined direction, the alignment layer extends radially from the center of the rectangular display area or the circular beam passage area, The alignment grooves or ridges are thinned out as they approach the center so that there is no significant difference between the alignment grooves or ridges between the center side and the outer side.

  Therefore, it is possible to create a stable radial shape near the center of the alignment groove or ridge, and to prevent a large difference between the alignment groove or the ridge between the center side and the outer side as described above. can do. As a result, it is possible to obtain a great effect on the expansion of the viewing angle in the liquid crystal display device and the birefringence correction in the optical pickup.

  Furthermore, in the alignment layer of the present invention, as described above, the alignment groove or the ridge is formed wider as the distance from the center increases.

  Therefore, the spacing between the alignment grooves or the protrusions can be made more uniform on the center side and the outer side.

  Further, as described above, the liquid crystal display device of the present invention has the alignment layer on the opposite surface side of one of the pair of substrates, and concentric alignment on the opposite surface side of the other substrate. An alignment layer having grooves or ridges is formed, and the alignment grooves or ridges are formed by nanoimprinting.

  Therefore, selective rubbing takes man-hours, and rubbing cannot be made completely radial and concentric, whereas using nanoimprint, continuous radial and concentric alignment grooves or ridges can be continued. Thus, a liquid crystal display device that can be manufactured and that can widen the viewing angle can be easily realized.

  Furthermore, as described above, the optical element of the present invention uses liquid crystal as the material having the uniaxial refractive index anisotropy, and in the optical element used as a birefringence correction element of an optical disk in an optical pickup, And using a ring-shaped electrode, preferably a solid electrode on the light exit side, and applying an electric field with the ring-shaped electrode on the incident side, the liquid crystal axis in the plane direction at the center and outward It can stand up in the thickness direction as it goes to the side, the curable resin mixed in that state is cured to fix the birefringent layer, the electrode is removed if necessary, etc. Complete the device.

  Therefore, the phase of the light beam on the outer peripheral side rather than the optical axis side advances, the influence of the birefringence of the optical disc can be canceled, and an optical element that can improve the resolution can be realized.

  Further, as described above, the optical element of the present invention uses liquid crystal as the material having the uniaxial refractive index anisotropy, and the optical element used as a birefringence correction element of an optical disk in an optical pickup, And using a ring-shaped electrode, preferably a solid electrode on the light emitting side and an incident side as the ring-shaped electrode, the inclination of the axis of the liquid crystal is different between the central portion and the outer side. Thus, it can be raised in the thickness direction as it goes outward.

  Therefore, the phase of the light beam on the outer peripheral side rather than the optical axis side advances, the influence of the birefringence of the optical disc can be canceled, and an optical element that can improve the resolution can be realized. Moreover, the progress of the phase can be adjusted by changing the electric field strength.

[Embodiment 1]
FIG. 1 is an enlarged front view showing a part of a liquid crystal panel 1 that realizes a liquid crystal display device according to an embodiment of the present invention. In the liquid crystal panel 1, the alignment film, which is an alignment layer provided on the opposite surface side of one of the pair of glass substrates, has an alignment extending radially from the center P 0 of each pixel A, as in the above-mentioned Patent Document 1. The alignment film provided with the grooves or ridges 2 on the opposite surface side of the other substrate has the alignment grooves or ridges 3 formed concentrically with respect to the center P0 of each pixel A.

  The alignment grooves or ridges 2 and 3 may be formed by electron beam drawing or the like on a resin sheet serving as an alignment film, and may be used as the alignment film as it is transferred by etching, or the electron beam drawing or the like on a mold material. What is formed by and transferred by etching may be used as a mold such as nanoimprint, and what is transferred to the resin sheet may be used as the alignment film. Moreover, you may form by photolithography by exposure and an etching as another preparation method. However, nanoimprinting is preferable for forming each of a large number of pixels A. When the alignment layer composed of the alignment grooves or the ridges 2 and 3 is directly engraved on a glass substrate which is a base material, the above-described separate film is unnecessary.

  Then, the alignment film is affixed to the opposite surface side of the substrate on which the electrode is formed, liquid crystal is filled between them, spacers are provided as appropriate, and the outer periphery is hermetically sealed so that the liquid crystal Panel 1 is completed. Thereafter, a driving circuit or a printed circuit board connected to the peripheral edge of the panel is connected.

It should be noted that in the present embodiment, in the alignment film for aligning the liquid crystal material in contact with the liquid crystal layer, which is a birefringent layer including a material having uniaxial refractive index anisotropy, the pixel A That is, the alignment grooves or ridges 2 extending radially from the center P0 are thinned out as they approach the center P0. That is, every time the alignment groove or the ridge 2 that divides the region of the pixel A into m × 2 ⁿ (m and n are natural numbers) at an equal angle is separated from the center P0 by a predetermined distance, and a predetermined interval is opened. When the number up to the radius point is m × ²ⁿ , a new orientation groove or ridge starts to form in the middle between the orientation groove or ridge up to the radius point. The orientation grooves or ridges increase from the radius point to m × 2 ^{n + 1} . In the example of FIG. 1, m = 2 and n = 3, and there are 16 alignment grooves or protrusions 2a extending from the center P0, and alignment grooves or protrusions formed between the alignment grooves or protrusions 2a from the middle. Article 2b also becomes 16 in 12 × ^{2 3,} the alignment grooves or ridges 2a, alignment grooves or ridges 2c are formed between the 2b will become 32 in 2 × ^{2 4,} the number of divisions 64 It becomes.

  For example, if m = 2, the initial value of n is 1 and the maximum value is 4, as shown in FIG. 2, there are 4 alignment grooves or ridges 2a and 4 alignment grooves or ridges 2b. Eight alignment grooves or ridges 2c formed between the alignment grooves or ridges 2a and 2b, and eight alignment grooves or ridges 2d formed between the alignment grooves or ridges 2a, 2b and 2c. 16 and the number of divisions is 32. Furthermore, for example, if m = 3, the initial value of n is 1 and the maximum value is 3, as shown in FIG. 3, there are 6 alignment grooves or protrusions 2a and 6 alignment grooves or protrusions 2b. 12 alignment grooves or ridges 2c formed between the alignment grooves or ridges 2a and 2b, and 12 alignment grooves or ridges 2d formed between the alignment grooves or ridges 2a, 2b and 2c. There will be 24 and the number of divisions will be 48.

  By configuring in this way, a stable radial shape can be created in the alignment groove or ridge 2a up to the vicinity of the center point, and the distance between the alignment grooves or ridges 2a, 2b and 2c as described above It is possible to prevent a large difference from occurring on the outer side. Thereby, it is possible to obtain a great effect on the expansion of the viewing angle in the liquid crystal display device.

  In addition, selective rubbing (mask rubbing method) such as Patent Document 1 and Japanese Patent Application Laid-Open No. 2005-332435 requires man-hours and costs in mass production, and the rubbing cannot be made completely radial or concentric. On the other hand, the rib method requires a step of adding ribs, whereas the nanoimprint is used as described above to continuously form the complete radial grooves and the concentric alignment grooves or ridges 2 and 3. Can be created easily. Therefore, a liquid crystal display device capable of expanding the viewing angle can be easily realized.

  In addition, as shown in FIG. 4, the alignment grooves or ridges 2a passing through the center P0 may be strictly cut off in the vicinity of the center P0, and the alignment grooves or ridges 2a, 2b, 2c to be formed are formed. The longest of these.

[Embodiment 2]
FIG. 5 is an enlarged front view showing a part of a liquid crystal panel 1 ′ that realizes a liquid crystal display device according to another embodiment of the present invention. The liquid crystal panel 1 ′ is similar to the liquid crystal panel 1 shown in FIG. 1, and corresponding portions are denoted by the same reference numerals and description thereof is omitted. It should be noted that in this liquid crystal panel 1 ′, the alignment grooves or ridges 2 ′ (2a ′, 2b ′, 2c ′) extending radially from the center P0 of each pixel A ′ become wider as the distance from the center P0 increases. Is formed.

  Therefore, the distance between the alignment grooves or the protrusions 2 'can be made more uniform on the center P0 side and the outer side.

[Embodiment 3]
6 and 7 are schematic cross-sectional views for explaining the manufacturing process of the optical element 10 according to still another embodiment of the present invention. The optical element 10 is similar to the liquid crystal panels 1 and 1 ′ shown in FIGS. 1 and 5 described above, and corresponding portions are denoted by the same reference numerals and description thereof is omitted. The optical element 10 is mounted on an optical pickup that records and reproduces data on an optical disk, and is used as a birefringence correction element for the optical disk.

  In general, in an optical system of an optical disk, linearly polarized light emitted from a light source passes through a beam splitter, passes through a quarter-wave plate, becomes circularly polarized light, and then is collected by a condenser lens. Irradiated onto the optical disk, the reflected light traces the incident optical path in the reverse direction, passes through the quarter-wave plate, becomes linearly polarized light rotated 90 degrees from the incident light, and is reflected in a direction different from the incident optical path by the polarizing beam splitter The light is received by the light receiver.

  In that system, incident light enters the optical disk as condensed light, and the incident angle increases toward the outer side away from the optical axis. If the optical disk has unnecessary birefringence anisotropy, the birefringence increases toward the outer side. Thus, the light incident as circularly polarized light becomes elliptically polarized light after reflection. This not only reduces the amount of light but also increases the size of the spot light, thereby reducing the resolution. Therefore, a birefringence correction element in which the phase of light advances toward the outside so as to cancel such birefringence anisotropy is interposed between the quarter-wave plate and the optical disk. The structure and function of such an optical pickup is described in detail in Japanese Patent Laid-Open No. 2005-332435.

  It should be noted that in this optical element 10, alignment films 14 and 15 having radial alignment grooves or ridges 2 and 2 ′ shown in FIG. 1 and FIG. 5 are provided on the opposing surfaces of the paired substrates 11 and 12. Each of them is filled with a photo-curing resin 16 containing liquid crystal and a spacer (not shown) as appropriate, and after the outer periphery is hermetically sealed by a sealing member 17, the photo-curing resin 16 is described below. It is to be cured as shown.

  That is, as shown in FIG. 6, dummy substrates 20 and 21 on which electrodes 18 and 19 are formed are laminated on the outer surface side of the substrates 11 and 12 (the side opposite to the alignment films 14 and 15), respectively. A voltage is applied from the power source 22 between the electrodes 18 and 19, and the photo-curing resin 16 is fixed by being irradiated with ultraviolet rays while an electric field is generated between the electrodes 18 and 19. At least one of the dummy substrate 20 and the electrode 18 and the dummy substrate 21 and the electrode 19 is transparent to the ultraviolet rays, and the ultraviolet irradiation is performed from the transparent substrate side. Further, the substrates 11 and 12 are transparent to the irradiation light to the optical disc.

  One of the electrodes 18 and 19 (18 in FIGS. 3 and 4) is a ring-shaped electrode formed facing the outer peripheral edge of the substrates 11 and 12, and the other of the electrodes 18 and 19 (FIGS. 3 and 4). Then 19) is a solid electrode. The power source 22 applies alternating current for a predetermined period to activate the liquid crystal, and then applies direct current for a predetermined time during the photocuring and before the photocuring. By applying a voltage between the electrodes 18 and 19 having the above-described shape, an electric field as indicated by reference numeral 30 in FIG. 8 is generated. The electric field is strong on the peripheral edge side of the optical element 10 facing the electrodes 18 and 19 and weak on the central area side. Therefore, as shown in FIGS. 8 and 9, in the photocurable resin 16, the liquid crystal molecules 16a are tilted in the plane direction near the center of the optical element 10, and the inclination is changed at a position corresponding to the radius. It stands up in the thickness direction near the periphery.

  In this state, direct current is applied to stop the movement of the liquid crystal molecules 16a, and after being cured by irradiating the ultraviolet rays, the dummy substrates 20, 21 are removed together with the electrodes 18, 19 as shown in FIGS. The optical element 10 is completed. In such an optical element 10, the substrate 11 side on which the ring-shaped electrode 18 is formed is used as the light incident side on the light source side, and the substrate 11 side on which the solid electrode 19 is formed is used as the light emitting side on the optical disc side. As a result, the phase of the light beam on the outer peripheral side rather than the optical axis side advances, the influence of the birefringence of the optical disc can be canceled, and the resolution can be improved.

  The optical element 10 does not necessarily have to be solidified, and as shown by the optical element 31 in FIG. 10, a configuration in which electrodes 18 and 19 and a power source 32 are provided for constantly applying an alternating electric field. If so, the same birefringence correction effect can be obtained without solidification. In this case, by adjusting the electric field strength, the progress of the phase can be adjusted. Further, the electrode 19 is not necessarily a solid electrode, and may be ring-shaped like the electrode 18. In this case, an electric field is generated between a portion where the electrodes 18 and 19 are formed and a portion where the electrodes 18 and 19 are not formed. Since the change becomes steep, the change in the alignment direction of the liquid crystal molecules 16a becomes steep.

It is a front view which expands and shows a part of liquid crystal panel which implement | achieves the liquid crystal display device which concerns on one Embodiment of this invention. It is a front view which expands and shows a part in other example of the said liquid crystal panel. It is a front view which expands and shows a part in other example of the said liquid crystal panel. It is a front view which expands and shows a part in other example of the said liquid crystal panel. It is a front view which expands and shows a part of liquid crystal panel which implement | achieves the liquid crystal display device which concerns on other embodiment of this invention. It is typical sectional drawing for demonstrating the manufacturing process of the optical element which concerns on the further another form of implementation of this invention. It is typical sectional drawing for demonstrating the manufacturing process of the optical element which concerns on the further another form of implementation of this invention. It is typical sectional drawing for demonstrating the orientation direction of the liquid crystal molecule in the optical element shown in FIG. 6 and FIG. It is typical sectional drawing for demonstrating the orientation direction of the liquid crystal molecule in the optical element shown in FIG. 6 and FIG. It is typical sectional drawing of the optical element which concerns on the further another form of implementation of this invention.

Explanation of symbols

1, 1 'liquid crystal panels 2, 2'; 2a, 2a ', 2b, 2b', 2c, 2c '; 3 alignment grooves or ridges 10, 31 Optical elements 11, 12 Substrate 14, 15 Alignment film 16 Photo-curing resin 17 Seal member 18, 19 Electrode 20, 21 Dummy substrate 22, 32 Power supply 16a Liquid crystal molecule

Claims (6)

In an orientation layer for orienting the material in contact with a birefringent layer comprising a material having uniaxial refractive index anisotropy,
An alignment layer comprising alignment grooves or ridges extending radially in a plane direction of the alignment layer, wherein the alignment grooves or ridges are thinned out toward the center of the alignment layer. In an orientation layer for orienting the material in contact with a birefringent layer comprising a material having uniaxial refractive index anisotropy,
The alignment groove or protrusion extends radially in the plane direction of the alignment layer and divides the region into m × 2 ⁿ (m and n are natural numbers) at an equal angle. Every time the distance from the center of the alignment layer is a predetermined distance, when the number to the radius point is m × 2 ⁿ , it is increased to m × 2 ^{n + 1 on the} outer circumference of the radius. Feature alignment layer.   The alignment layer according to claim 1, wherein the alignment groove or the ridge is formed wider as it gets away from the center.   The alignment layer according to any one of claims 1 to 3 is provided on the opposing surface side of one of the paired substrates, and concentric alignment grooves or protrusions are provided on the opposing surface side of the other substrate. A liquid crystal display device comprising: an alignment layer having a stripe formed thereon, wherein the alignment groove or the protrusion is made of nanoimprint.   Liquid crystal as a material having the alignment layer according to any one of claims 1 to 3 on the opposing surface side of a pair of substrates, wherein the birefringent layer has the uniaxial refractive index anisotropy. And a curable resin, and by applying an electric field with a ring-shaped electrode, the axis of the liquid crystal is erected in the thickness direction as it goes outward in the plane direction and in the center portion, and the state An optical element characterized by being fixed by the curable resin solidified in step (b).   Each of the alignment layers according to any one of claims 1 to 3 is provided on a facing surface side of a pair of substrates, the material having the uniaxial refractive index anisotropy is a liquid crystal, and a ring-shaped electrode The optical element is characterized in that the inclination of the axis of the liquid crystal is changed so as to be different between the central portion and the outer side by applying an electric field at.

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