JP2008175838A - Liquid crystal display device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid crystal display device capable of efficiently inducing a splay-bend transition and having a satisfactory numerical aperture. <P>SOLUTION: In the liquid crystal display device, minute structural bodies are disposed in such positions wherein the numerical aperture is not affected and an electric field between a TFT substrate 3 and a CF substrate 4 can be applied to two minute regions, particularly to stable homogeneous regions. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an OCB (Optically Compensated Birefringence or Optically Compensated Bend) mode liquid crystal display device that realizes a wide viewing angle and high-speed response.

  In recent years, in a liquid crystal display device, a display method called an OCB mode has attracted attention (see, for example, Non-Patent Documents 1 and 2). In this OCB mode, a liquid crystal panel in which a liquid crystal layer sandwiched between a pair of substrates is in a splay alignment state and transitions to a bend alignment state when a driving voltage is applied is combined with an optical compensation film that performs optical compensation of the liquid crystal panel. In this way, wide viewing angle and high speed response are realized. However, in this OCB mode, when a normal alignment treatment is performed, it is not easy to quickly transfer the liquid crystal layer in the initial splay alignment state to the bend alignment state, and the pretilt angle on the substrate is about 10 °. Even if it is set to, a high voltage of 10V or more, for example, about 20V is required. It is very difficult to apply such a high voltage in terms of controlling the driving voltage. In addition, it is not easy to cause such a transition of the liquid crystal layer in all the pixels, and some of the pixels that remain without the transition of the liquid crystal layer will greatly deteriorate the display quality of the panel.

In order to solve such a problem, for example, in Non-Patent Document 3, a post spacer is provided on the alignment control layer (alignment film), and the rubbing process is performed three times in three directions different from each other. It is disclosed to form a twist orientation to induce a splay-bend transition.
SID 93 Digest p277, Y. Yamaguchi et al. “Wide-Viewing-Angle Display Mode for the Active-Matrix LCD Using Bend-Alignment Liquid Crystal Cell” SID 94 Digest p927, CL. Kuo et al. “Improvement of Gray-Scale performance of Optically Compensated Birefringence (OCB) Display Mode for AMLCDs” 2005 Japan Liquid Crystal Society Annual Meeting, 3A03 Kuboki, Miyashita, Ishibe, Uchida “Formation of twist disclination for spray-bend transition and its application to OCB cell”

  In order to induce the splay-bend transition, it is necessary to form two micro regions (a left twist alignment region and a right twist alignment region) having a twist structure in which the twist alignment of liquid crystal molecules is different from each other when a voltage is applied, It is necessary to have a configuration that can efficiently apply an electric field to these two minute regions. Moreover, when providing a post spacer like the said nonpatent literature 3, it is necessary to consider the influence on an aperture ratio.

  The present invention has been made in view of this point, and an object of the present invention is to provide a liquid crystal display device capable of efficiently inducing a spray-bend transition and having a sufficient aperture ratio.

  The liquid crystal display device of the present invention includes a first substrate having a pixel electrode and an alignment control layer, a second substrate having an alignment control layer and arranged to face the first substrate, and the first substrate A liquid crystal layer having a positive dielectric anisotropy sandwiched between the first and second substrates, and having at least a transmissive region in each pixel region, wherein the first and second The alignment control layer of one of the substrates has a microstructure that forms two minute regions having twist structures in which the twist arrangement of liquid crystal molecules is different from each other when a voltage is applied, and the microstructure has an aperture ratio. It is provided in the position which does not affect this.

  According to this configuration, since the microstructure disposed at an appropriate position is provided, it is possible to reliably form two minute regions for inducing the splay-bend transition by a predetermined rubbing process, and to achieve an aperture ratio. Can be prevented. As a result, it is possible to quickly shift to bend alignment over the entire screen. As a result, it is possible to provide an OCB type liquid crystal display device with no optical loss and no contrast reduction.

  In the liquid crystal display device of the present invention, it is preferable that the microstructure be provided on the second substrate. In this case, it is preferable that each pixel region has a reflective region, and the microstructure is provided in the reflective region in plan view.

  In the liquid crystal display device of the present invention, the first substrate has an active element electrically connected to the pixel electrode, and the microstructure is at least above the wiring of the active element via an insulating film. Are preferably provided. In this case, in plan view, the pixel electrode of the first substrate and a light-shielding electrode that covers the wiring of the active element are included, and the microstructure has an insulating film and a wiring over the wiring of the active element. It is preferable that the light-shielding electrode is provided. In this case, the two minute regions are a homogeneous twist region and a spray twist region, and the microstructure is provided so that at least the homogeneous twist region is located in the light shielding electrode in a plan view. It is preferable.

  In the liquid crystal display device of the present invention, each pixel region has a reflection region, and the shortest distance between the reflection region and the microstructure is not more than three times the maximum diameter of the microstructure. It is preferable.

  According to the present invention, a first substrate having a pixel electrode and an alignment control layer, a second substrate having an alignment control layer and disposed to face the first substrate, the first and A liquid crystal layer having a positive dielectric anisotropy sandwiched between second substrates, and having at least a transmission region in each pixel region, wherein the first and second substrates The orientation control layer of one substrate has a microstructure that forms two microregions having a twisted structure in which the twisted arrangement of liquid crystal molecules is different from each other when a voltage is applied, and the microstructure affects the aperture ratio. Therefore, the splay-bend transition can be induced efficiently, and a liquid crystal display device having a sufficient aperture ratio can be realized.

  Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the drawings used in the following description, in order to make the characteristics easy to understand, the characteristic portions are enlarged as necessary.

  As shown in FIG. 1, a liquid crystal display device 1 according to the present invention includes an OCB mode liquid crystal panel 2. The liquid crystal panel 2 is a transmissive color liquid crystal panel adopting, for example, an active matrix driving method, and one unit pixel (pixel) is formed by three dots (sub-pixels) corresponding to the three primary colors of red, green, and blue. In addition, an active drive element is provided for each dot, and a color display is performed by controlling the lighting state of each pixel. Although FIG. 1 illustrates an example in which each red, green, and blue subpixel is arranged in a stripe shape, the subpixels may be arranged diagonally or in a triangle shape.

  The liquid crystal panel 2 includes a pair of substrates 3 and 4 arranged to face each other, a liquid crystal layer 5 as a light modulation layer sandwiched between the pair of substrates 3 and 4, and a rear side substrate (view side) At least one polarizing plate 7 disposed on the front side substrate (viewing side substrate: CF (color filter) substrate) 4 and a light source 6 disposed below the opposite substrate: TFT substrate) 3. The retardation plate 8, the polarizing plate 9 disposed below the lower substrate 3, at least one retardation plate 10, and the like. The pair of substrates 3 and 4 are rectangular transmissive substrates such as glass and plastic, and are mutually dispersed in the liquid crystal layer 5 by spherical spacers (not shown) that are dispersed or fixed in place. The facing distance is kept uniform, and the peripheral part is sealed and integrated with a sealing agent (not shown) made of epoxy resin or the like. Although not shown, the front substrate 4 is provided with a transparent electrode on the entire surface, and a predetermined liquid crystal alignment state is controlled on each surface of the substrates 3 and 4 facing the liquid crystal layer 5. Orientation control layers 23 and 24 (see FIG. 2) are provided.

Of the pair of substrates 3 and 4, one (back side) substrate 3 is a so-called active matrix substrate, as shown in FIGS. 2 and 3, and a switching element (on the surface facing the liquid crystal layer 5). A plurality of TFTs (Thin Film Transistors) 11 as active elements are arranged in a matrix. The TFT 11 includes an inverted staggered structure in which a gate electrode 12, a gate insulating layer 13, a semiconductor layer 14, and a source electrode 15 and a drain electrode 16 are stacked via a semiconductor layer (n ⁺ layer) 28 in this order from the substrate 3 side. Has a mold structure. That is, in this structure, an island-shaped semiconductor layer 14 is formed on the gate insulating layer 13 covering the lowermost gate electrode 12 so as to block the gate electrode 12, and is formed on one end side of the semiconductor layer 14. The source electrode 15 is formed through the semiconductor layers 14 and 28, and the drain electrode 16 is formed at the other end of the semiconductor layer 14 through the semiconductor layers 14 and 28. Note that an island-shaped insulating layer 17 is formed on the semiconductor layer 14, and this insulating layer functions as an etch stopper when forming a channel between the source electrode 15 and the drain electrode 16.

  On the surface of the substrate 3 facing the liquid crystal layer 5, a plurality of scanning lines 18, which are wirings electrically connected to the gate electrodes 12 of the respective TFTs 11, are arranged in parallel with each other in the arrow X direction (row direction) in FIG. 3. A plurality of signal lines 19 that are electrically connected to the source electrode 15 of each TFT 11 are formed side by side in the arrow Y direction (column direction) in FIG. The TFT 11 is formed in the vicinity of the intersection of the signal line 19 and the signal line 19. In addition, each rectangular area partitioned by the scanning lines 18 and the signal lines 19 forms a dot corresponding area on the substrate 3 side corresponding to each dot. By arranging a plurality of regions in a matrix, a display region of the liquid crystal panel 2 is formed as a whole. Although not shown, a scanning driver that applies a selection pulse to each scanning line 18 and a signal driver that applies a signal voltage to each signal line 19 are provided outside the display area. .

  An insulating film 20 that covers the TFT 11, the scanning line 18, and the signal line 19 is formed on the surface of the substrate 3 that faces the liquid crystal layer 5. In addition, a contact hole 21 that faces the drain electrode 16 of each TFT 11 is formed in the insulating film 20. On the insulating film 20, a plurality of pixel electrodes 22 electrically connected to the drain electrodes 16 of the respective TFTs 11 through the contact holes 21 are formed in a matrix corresponding to the respective dots. Yes. The pixel electrode 22 is made of a transparent conductive material such as ITO (Indium-Tin Oxide), and is formed in a rectangular shape so as to cover almost the entire area corresponding to each dot. On the substrate 3 on which the pixel electrode 22 is formed, an orientation control layer 23 that has been processed as described later is formed.

  On the other hand, the other surface (front side) of the substrate 4 facing the liquid crystal layer 5 is made of an alignment control layer 24 that has been processed later and a transparent conductive material such as ITO (Indium-Tin Oxide). For example, red (R), green (G), blue, which are defined by the counter electrode 27, the light-shielding black matrix layer 25 that partitions the dot corresponding area corresponding to each dot, and the black matrix layer 25. The color filter layers 26R and 26G (26B are not shown) of (B) are formed in order. Specifically, each rectangular area partitioned in a rectangular pattern by the rectangular black matrix layer 25 forms a dot corresponding area on the substrate 4 side corresponding to each dot. The black matrix layer 25 is a light shielding wall for preventing light color mixing between the color filters, and is a dot of any one of the red (R), green (G), and blue (B) colors. Is embedded. The color filter layers 26R and 26G (26B not shown) have a structure in which layers of different colors are periodically arranged in a mosaic shape such as a stripe shape, a diagonal shape, or a triangle shape. Therefore, the display color of each pixel is controlled by controlling the drive voltage applied between the pixel electrode 22 and the counter electrode 27 for each of the three dot corresponding regions corresponding to red, green, and blue of each pixel. Thus, a desired image can be displayed.

  The liquid crystal layer 5 includes a nematic liquid crystal composition having positive dielectric anisotropy enclosed between the alignment control layer 23 of one substrate 3 and the alignment control layer 24 of the counter substrate 4. Furthermore, the liquid crystal layer 5 is in a splay arrangement in which the pretilt angles of the liquid crystal molecules are opposite to each other on each of the substrates 3 and 4 in an initial state (no voltage application state or a low voltage state in which the alignment state does not change). The orientation is controlled so that

  In the liquid crystal display device of the present invention, a plurality of retardation plates, polarizing plates, etc. are provided so as to satisfy an appropriate optical compensation condition according to the liquid crystal driving voltage for a panel provided with liquid crystal molecular orientation as described later. An optical film is placed.

For example, when a display is performed in a transmissive normally black mode, a liquid crystal layer in the panel is formed with respect to a panel (a nematic liquid crystal composition having positive dielectric anisotropy sandwiched between two substrates). And a biaxial optical compensation film ( _nx > _ny > _nz , where the optical axes are set in directions orthogonal to the rubbing direction, respectively, so that the birefringence phase difference becomes zero in total X and y represent the directions in the panel surface, and z represents the thickness direction of the panel). In particular, the optical films described above are configured so that black display is performed at the lowest voltage (OFF voltage) that maintains the bend alignment state, and white display is performed at a voltage (ON voltage) at which the liquid crystal molecules sufficiently rise from the bend alignment. Conditions (mutual optical axis direction, phase difference value, etc.) are set. For example, when the panel has a phase difference of 960 nm when no voltage is applied (splay alignment state) and the ON voltage is 5.0 V, the phase difference of the biaxial optical compensation film is 50 nm and the Nz coefficient is 7.5. Then, the birefringence phase difference between the liquid crystal layer of the panel and the biaxial optical compensation film becomes zero in total. Here, the Nz coefficient is Nz = (nx−) where the refractive index in the slow axis direction, the refractive index in the fast axis direction, and the refractive index in the thickness direction are nx, ny, and nz, respectively. nz) / (nx-ny). Needless to say, in the case of so-called normally white, the above conditions for black display and white display are reversed. Further, a laminated body in which a polarizing plate and a quarter wavelength plate (1 / 4λ plate) are set so that the optical axes of both are set to about 45 ° and a circular polarizing plate is formed is placed on both sides of the above. Deploy.

On the other hand, in the case of reflection type (normally black) display, the inner surface of the substrate (on the opposite side to the observation side of the panel (a nematic liquid crystal composition having positive dielectric anisotropy sandwiched between two substrates) ( to form a reflective layer on the side of the surface) or the substrate outer surface in contact with the liquid crystal layer, the liquid crystal layer and the biaxial optical compensation film, such as its birefringence phase difference becomes zero in total in the panel (n _x> n _y > N _z , where x and y represent the panel surface, and z represents the thickness direction of the panel. For example, when the phase difference in the voltage non-application state (splay alignment state) of the panel is 480 nm and the ON voltage is 5.0 V, the phase difference of the biaxial optical compensation film is 50 nm and the Nz coefficient is 7.5. The birefringence phase difference between the liquid crystal layer of the panel and the biaxial optical compensation film becomes zero in total. Further, on the upper surface (surface close to the observation side), a polarizing plate and a quarter wavelength plate (1 / 4λ plate) are set so that both optical axes are about 45 °. The laminated body formed with is disposed. In the case of normally white, the above-described relationship between the black display and the white display is reversed as described above.

  FIG. 4 is a plan view showing a microstructure in the liquid crystal display device according to the embodiment of the present invention. FIG. 4 is a so-called film top view in which the surface on which the orientation control layer is provided is on the paper surface. A plurality of the microstructures 31 are formed on one substrate, for example, the TFT substrate 3. Using this microstructure 31, a first rubbing process is performed in the rubbing direction X, a second rubbing process is performed in the rubbing direction Y, and a third rubbing process is performed in the rubbing direction Z. By performing the rubbing process using the microstructure 31, it is possible to form two minute regions having twist structures in which the twist arrangement of liquid crystal molecules is different from each other when a voltage is applied. By forming these two minute regions, the spray-bend transition can be induced. The rubbing direction Z is the same direction as the rubbing direction in the CF substrate 4 which is the counter substrate.

  In FIG. 4, a region 32 is a rubbing shadow formed for the second rubbing process and the third rubbing process. That is, in the second rubbing process and the third rubbing process, the microstructure 31 becomes an obstacle, and the rubbing process in the rubbing direction Y and the rubbing direction Z is not performed. Accordingly, only the first rubbing process is performed on the region 32, and the alignment in the rubbing direction X is formed.

  An area 33 is a rubbing shadow formed for the third rubbing process. That is, in the third rubbing process, the micro structure 31 becomes an obstacle, and the rubbing process in the rubbing direction Z is not performed. Therefore, in the region 33, the first rubbing process and the second rubbing process are performed.

  By performing the rubbing process three times as described above, the region 32 becomes a left twisted homogeneous alignment region (homogeneous-twist region), and the region 33 becomes a right twisted spray alignment region (spray-twist region). The boundary line 34 between the left twisted homogeneous alignment region and the right twist splay alignment region can be secured by a sufficient length and / or the region 32 can be secured by a sufficient width, so that the spray-bend transition can be efficiently performed. Can be induced. The shape of the microstructure 31 is not particularly limited as long as the regions 32 and 33 and the boundary line 34 are formed.

  All of these rubbing processes are performed on an alignment film (for example, a polymer alignment film such as polyvinyl alcohol, polyamide, or polyimide) that is the alignment control layer 23 of the TFT substrate 3. First, a first rubbing process is performed in the rubbing direction X. Next, a second rubbing process is performed in the rubbing direction Y. Thereafter, a third rubbing process is performed in the rubbing direction Z.

  When a voltage higher than a predetermined value is applied to the alignment state having the two minute regions 32 and 33 and the boundary line 34 formed in this way, a stable homogeneous region spreads toward the spray side at once. For this reason, the entire display screen is quickly transferred to the bend state. The reason is that the twisted homogeneous orientation is more energetically stable than the twisted splay orientation when a voltage is applied, and the energy required for the transition from spray to bend by passing through a twisted state of 90 ° or more. This is due to the smaller barrier.

  In order to efficiently induce the spray-bend transition and to have a sufficient aperture ratio, the aperture ratio is not affected, and the electric field between the TFT substrate 3 and the CF substrate 4 is 2 It is necessary to arrange the above-described microstructure at a position where it can be applied to one minute region, particularly a stable homogeneous region.

  Further, the TFT substrate 3 is more complicated in manufacturing process than the CF substrate 4 because it is necessary to make a TFT which is an active element. In addition, since the TFT substrate has a TFT, if the rubbing process is performed three times using the microstructure 31, electrostatic damage to the TFT increases. For this reason, the microstructure 31 is preferably provided on the CF substrate 4 side as shown in FIG. Thereby, it can prevent that manufacture of a TFT substrate becomes more complicated. In this case, when the pixel has a reflective region, it is preferably provided in the reflective region in plan view, that is, above the reflective electrode 35, like the microstructure 31a. In order to easily induce the spray-bend transition, it is preferable to increase the height of the microstructure by providing it in a region other than the reflection region in a plan view like the microstructure 31b.

  When the microstructure 31 is provided on the TFT substrate 3 side, it is preferable to determine the formation position in consideration of the following points. First, in order to form two micro-regions that induce the spray-bend transition with a sufficient width, it is necessary to have a size of about 5 μm square, preferably 7 μm square. Since the formation area of the microstructure 31 is an area where light leakage occurs, it needs to be covered with a metal film or a black matrix layer on the CF substrate side. From the viewpoint of not reducing the aperture ratio, the microstructure 31 is not insulated from the center of the pixel but above the TFT wiring (for example, the signal line (source electrode line) or the scanning line (gate electrode line)). It is preferable to be provided through a film.

  FIG. 6 is a diagram showing the vicinity of the TFT 11 in the pixel. 7A is a cross-sectional view taken along line VIIA-VIIA in FIG. 6, and FIG. 7B is a cross-sectional view taken along line VIIB-VIIB in FIG. In each pixel, a reflective electrode 35 made of a reflective material such as aluminum is formed, and thereby a reflective region (shaded region in FIG. 6) and a transmissive region are provided in a partitioned manner.

  In order to arrange the above-described microstructure at a position where the electric field between the TFT substrate 3 and the CF substrate 4 can be applied to the two minute regions without affecting the aperture ratio, as shown in FIG. Thus, it is preferable to provide the microstructure 31 c in the through hole 21. As shown in FIG. 7A, since the reflective electrode 35 is provided on the drain electrode 16 via the resist layer 36, the resist layer 35 is electrically connected to the reflective electrode 35 and the drain electrode 16. Excavated 36. This portion becomes the through hole 21. Since the through hole 21 does not contribute to reflection, the microstructure 31c extends from this CF substrate 4 side to this region. Accordingly, the height of the microstructure 31c can be increased, and an increase in the cell gap due to the microstructure 31c can be prevented. Further, since the through hole 21 is provided in the reflection region, the aperture ratio is not affected by providing the microstructure 31c.

In order to dispose the above-described microstructure at a position where the electric field between the TFT substrate 3 and the CF substrate 4 can be applied to the two minute regions without affecting the aperture ratio, 19 is preferably provided on the source electrode line. That is, as shown in FIG. 7B, since the signal line 19 is provided outside the pixel region, the aperture ratio is not affected by providing the microstructure 31d above the signal line 19. In FIGS. 7A and 7B, reference numerals 37 and 38 denote insulating films made of SiNx, SiO ₂ or the like.

  As shown in FIG. 6, when the microstructure 31e is provided on the signal line 19 in the transmissive region of the pixel, since an insulating film is usually formed to prevent the signal line 19 from being short-circuited or disconnected, the signal line It is conceivable that a voltage drop occurs between the electrode 19 and the electrode of the CF substrate 4 so that an electric field is not efficiently applied to two minute regions formed using the minute structure. For this reason, as shown in FIG. 8, it is preferable that the electrode is formed directly under the microstructure 31e. This electrode may be a different electrode as long as it has the same potential as the reflective electrode. In FIG. 8, the reflective electrode 35 is formed so as to extend to the signal line of the transmission region. That is, in plan view, it has a light shielding electrode 35a that covers the pixel electrode 22 and the signal line 19 of the TFT substrate 3, and the microstructure 31e is provided above the signal 19 line via the insulating film and the light shielding electrode 35a. It has become the composition.

  When the gap 41 between the pixel electrode 22 and the signal line 19 is shielded by the black matrix layer of the CF substrate 4, the width of the black matrix layer is increased to some extent due to the overlap margin between the TFT substrate 3 and the CF substrate 4. Therefore, the aperture ratio is reduced. Although it is conceivable that the pixel electrode 22 overlaps the signal line 19, a black matrix layer is also required in this case. Since the extending portion 35 a of the reflective electrode 35 is provided so as to cover the gap 41 between the pixel electrode 22 and the signal line 19, it also functions as a light shielding electrode that prevents light leakage from the gap 41. . For this reason, it is not necessary to form the black matrix layer of the CF substrate 4. Covering the gap 41 between the pixel electrode 22 and the signal line 19 by the extending portion 35a of the reflective electrode 35 and shielding the light is advantageous from the viewpoint of the aperture ratio.

  For the induction of the spray-bend transition, two minute regions formed by rubbing using a microstructure are important, and a sufficient electric field is applied to these minute regions, particularly the homogeneous-twist region. It will be necessary. For this reason, it is preferable that the microstructure be provided so that at least the homogeneous twist region is located in the electrode in plan view. That is, as shown in FIG. 9, on the extended portion 35 a of the reflective electrode 35 that covers the gap 41 between the pixel electrode 22 and the signal line 19, the minute region, particularly the homogeneous twist region 32 is positioned. The microstructure 31e is disposed. Here, the center of the microstructure 31e is shifted to any one of the extending portions 35a. Thereby, a sufficient electric field can be applied to the minute region, particularly the homogeneous-twist region, and the spray-bend transition can be induced efficiently.

  When the microstructure 31e is provided on the signal line 19 via an insulating film in a region other than the reflection region, the shortest distance X between the reflection region and the microstructure 31e is the maximum diameter of the microstructure 31e. It is preferable to set it to 3 times or less, preferably 2 times or less. Thereby, the spray-bend transition can be induced more efficiently in the region up to the reflection region.

  In the above description, the case where at least one spray-bend transition start point is formed corresponding to each pixel is described. However, the present invention is not limited to this, and the present invention is not limited to the physical property values ( The arrangement density can be appropriately changed according to the elastic constant, dielectric anisotropy, etc.), the panel gap, the pretilt angle of the liquid crystal molecules, the alignment regulating force, and the like. For example, the number of transition start points may be one per 3 to 10 pixels. Also, by providing 2 to 4 pixels per pixel, there are relatively many starting points for bend transition, and the time to bend transition can be substantially shortened. For example, when the pretilt angle is large (4 ° or 5 ° to 15 °), the splay-bend transition is very likely to occur. Therefore, even when the arrangement density of the transition start points is 10 or more, it is effective. .

  In the above description, the arrangement position of the microstructure 31 is set on the TFT substrate 3, but in the liquid crystal display device of the present invention, the CF corresponding to the position provided on the TFT substrate 3 described above is described. The microstructure 31 may be provided at the position of the substrate 4.

Next, examples performed for clarifying the effects of the present invention will be described.
(Example 1)
A general CF substrate with red, green, and blue filters formed on subpixels is fabricated, and a fine structure (column spacer) with dimensions of 10 μm × 10 μm and a height of 4 μm is used for each subpixel. 19 was formed in a region corresponding to 19 (region corresponding to the microstructure 31e in FIG. 6). In addition, the shortest distance X between the microstructure 31e and the reflective region was 10 μm.

This column spacer is exposed to transparent negative resist CL-016S (manufactured by TOK) at 100 mJ / cm ² , developed with a 0.5% aqueous solution of N-A3K (trade name) for 60 seconds, and then post-treated at 300 mJ / cm ² . It formed by exposing and performing a post-baking at 220 degreeC for 1 hour.

  As shown in FIG. 4, the CF substrate was subjected to the first rubbing process in the rubbing direction X, the second rubbing process in the rubbing direction Y, and the third rubbing process in the rubbing direction Z. . The rubbing strength was 100 cm (pushing amount 0.2 mm) for all three rubbing treatments. The angle θ formed between the rubbing direction X and the rubbing direction Y was 120 °.

  Next, a TFT substrate on which a source electrode, a gate electrode, a pixel electrode, a TFT element and the like were formed was produced by a normal method. The TFT substrate was rubbed in the rubbing direction Z shown in FIG. 4 with a rubbing strength of 300 cm (pushing amount 0.6 mm). As shown in FIG. 8, the TFT substrate 3 is formed with a reflective electrode 35 having an extended portion 35a that covers the signal line 19 with an insulating film interposed therebetween, and a reflective region and a transmissive region are provided for each pixel.

  Next, the CF substrate and the TFT substrate were overlapped using the column spacer formed on the CF substrate as a gap material between the substrates. Next, after the stacked substrates were cut into panel units, a liquid crystal material (manufactured by Chisso Corp.) was injected between both substrates by a vacuum injection method to produce the OCB liquid crystal panel of Example 1. This OCB liquid crystal panel had a panel gap in the transmissive area of 4 μm and a panel gap in the reflective area of 2 μm.

  The OCB liquid crystal panel thus obtained was examined by an optical microscope to determine whether the spray-bend transition was induced by applying a voltage of 5 V to the pixel electrode and source electrode lines. As a result, in the OCB liquid crystal panel, immediately after the voltage is applied, a spray-bend transition occurs from a location where the post spacer formation region of the CF substrate intersects with the pixel electrode space, and all the pixels of the panel change to bend alignment in about 0.5 seconds. And metastasized.

  Further, the aperture ratio of the OCB liquid crystal panel of Example 1 using the reflective electrode 35 having the extending portion 35a was 44%, which was higher than the aperture ratio of 39% when the black matrix layer was used.

(Example 2)
An OCB liquid crystal panel of Example 2 was manufactured in the same manner as described above except that the microstructure was provided at the position of the microstructure 31e shown in FIG. With respect to this OCB liquid crystal panel, it was examined with an optical microscope whether or not a spray-bend transition was induced by applying a voltage of 5 V to the pixel electrode and source electrode lines. As a result, in the OCB liquid crystal panel, immediately after the voltage is applied, a splay-bend transition occurs from the point where the post spacer formation region of the CF substrate intersects with the pixel electrode space, and all the pixels of the panel transition to bend alignment in about 1 second. did. Moreover, the aperture ratio of the OCB liquid crystal panel of Example 2 was 44%.

(Example 3)
An OCB liquid crystal panel of Example 3 was fabricated in the same manner as described above except that the shortest distance X between the microstructure 31e and the reflective region was set to 30 μm. With respect to this OCB liquid crystal panel, it was examined with an optical microscope whether or not a spray-bend transition was induced by applying a voltage of 5 V to the pixel electrode and source electrode lines. As a result, in the OCB liquid crystal panel, immediately after the voltage is applied, a splay-bend transition occurs from the point where the post spacer formation region of the CF substrate intersects with the pixel electrode space, and all the pixels of the panel transition to bend alignment in about 3 seconds. did. Further, the aperture ratio of the OCB liquid crystal panel of Example 2 was 39%.

  As described above, in the liquid crystal display device of the present invention, since the microstructure is disposed at an appropriate position, two minute regions that induce a spray-bend transition by a predetermined rubbing process, that is, left twisting. The homogeneous region and the right twisted spray region can be reliably formed, and the aperture ratio can be prevented from being lowered. Accordingly, it is possible to provide an OCB type liquid crystal display device that can be quickly transferred to bend alignment over the entire screen and has no optical loss and no contrast reduction.

  The present invention is not limited to the embodiment described above, and can be implemented with various modifications. For example, the numerical values and materials described in the above embodiments, the configuration of the liquid crystal display device, and the like are not particularly limited. Other modifications may be made as appropriate without departing from the scope of the object of the present invention.

1 is an exploded perspective view showing a schematic configuration of a liquid crystal display device according to an embodiment of the present invention. It is sectional drawing of the liquid crystal display device shown in FIG. FIG. 2 is an enlarged view showing an active matrix substrate of the liquid crystal display device shown in FIG. 1. It is a figure for demonstrating the microstructure of the liquid crystal display device which concerns on embodiment of this invention. It is a figure for demonstrating the arrangement position of the microstructure of the liquid crystal display device which concerns on embodiment of this invention. It is a top view for demonstrating the arrangement position of the microstructure of the liquid crystal display device which concerns on embodiment of this invention. (A) is sectional drawing which follows the VIIA-VIIA line of FIG. 6, (b) is sectional drawing which follows the VIIB-VIIB line of FIG. It is a top view for demonstrating the arrangement position of the microstructure of the liquid crystal display device which concerns on embodiment of this invention. It is an enlarged view for demonstrating the arrangement position of the microstructure of the liquid crystal display device which concerns on embodiment of this invention.

Explanation of symbols

3,4 substrate 5 liquid crystal layer 11 TFT
DESCRIPTION OF SYMBOLS 12 Gate electrode 13 Gate insulating film 14 Semiconductor layer 15 Source electrode 16 Drain electrode 17 Insulating layer 18 Scan line 19 Signal line 22 Pixel electrode 23, 24 Orientation control layer 25 Black matrix layer 26R, 26G Color filter layer 27 Counter electrode 31, 31c , 31d, 31e Microstructure 32, 33 Region 34 Boundary line 35 Reflective electrode 36 Resist layer 37, 38 Insulating film 41 Gap

Claims (7)

  A first substrate having a pixel electrode and an alignment control layer, a second substrate having an alignment control layer and arranged to face the first substrate, and between the first and second substrates A liquid crystal layer having a positive dielectric anisotropy sandwiched therebetween, and having at least a transmission region in each pixel region, the orientation control of one of the first and second substrates The layer has a microstructure that forms two minute regions having twist structures in which the twist arrangement of liquid crystal molecules is different from each other when a voltage is applied, and the microstructure is provided at a position that does not affect the aperture ratio. A liquid crystal display device characterized by that.   The liquid crystal display device according to claim 1, wherein the microstructure is provided on the second substrate.   3. The liquid crystal display device according to claim 2, wherein each pixel region has a reflection region, and the microstructure is provided in the reflection region in plan view.   The first substrate includes an active element electrically connected to a pixel electrode, and the microstructure is provided above the wiring of the active element through at least an insulating film. The liquid crystal display device according to claim 1.   In plan view, it has a light-shielding electrode that covers the pixel electrode of the first substrate and the wiring of the active element, and the microstructure has an insulating film and the light-shielding electrode above the wiring of the active element. The liquid crystal display device according to claim 4, wherein the liquid crystal display device is provided.   The two minute regions are a homogeneous twist region and a spray twist region, and the microstructure is provided so that at least the homogeneous twist region is located in the light shielding electrode in a plan view. The liquid crystal display device according to claim 5.   Each pixel region has a reflective region, and the shortest distance between the reflective region and the microstructure is not more than three times the maximum diameter of the microstructure. The liquid crystal display device according to claim 6.

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