JP2008256963A - Liquid crystal display element and its manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid crystal display element having a satisfactory display quality and video display characteristics while a cost is suppressed. <P>SOLUTION: The liquid crystal display element is provided with counter projections 42 forming a plurality of domains D1, D2 having different tilt directions of liquid crystal molecules LC when applying a voltage between a pixel electrode 19 and a counter electrode on each pixel region AP. The respective domains D1, D2 are provided with low pretilt angle regions 47 which are smaller in the pretilt angles of the liquid crystal molecules LC than the other regions. The response characteristics of the liquid crystal molecules LC of the respective domains D1, D2 of the pixel regions AP are improved by a low pretilt angle region 47 so that the satisfactory display quality and video display characteristics are assured while the cost is suppressed. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a liquid crystal display element in which a plurality of pixel regions sandwiched between a pixel electrode and a counter electrode are formed in a liquid crystal layer, and a method for manufacturing the same.

  Since a liquid crystal display device using a liquid crystal display element has features such as light weight, thinness, and low power consumption, it is applied to various fields such as an OA device, an information terminal, a clock, and a television receiver. In particular, a liquid crystal display element using a TFT element as a switching element is used for a display monitor for data including a lot of information such as a portable television receiver and a computer because of its responsiveness.

  In recent years, with the increase in the amount of information and the increase in moving image display, high definition and high speed response have been demanded.

  High definition is supported by miniaturization of the TFT array structure, and high-speed response is achieved by, for example, an OCB method using a nematic liquid crystal, a VAN method, a HAN method, a π arrangement method, an interface using a smectic liquid crystal. A stable ferroelectric liquid crystal (SSFLC) system, an antiferroelectric liquid crystal (AFLC) system, or the like has been studied.

  In particular, the VAN type alignment mode has a rubbing alignment process step that has a higher response speed than the conventional twisted nematic type (TN) mode and that has been concerned about the occurrence of defects such as electrostatic breakdown due to the use of the vertical alignment process. Recently, it has been attracting attention because it can be deleted.

  Furthermore, in this VAN type mode, since the viewing angle compensation design is relatively easy, a wide viewing angle is realized as a multi-domain type VAN mode (hereinafter referred to as MVA mode) in which a plurality of domains are formed in each pixel region. Is possible.

  Here, in the MVA mode, as a means for dividing the alignment of liquid crystal molecules, a saddle-like structure or a missing portion (slit) of the ITO electrode is formed on one or both of the array substrate and the counter substrate. The method is known.

  In this configuration, for example, slits are formed in the pixel electrodes on the array substrate, and protrusions are formed as structures on the surface of the common electrode on the counter substrate. By using a nematic liquid crystal material exhibiting negative dielectric anisotropy, in the slit of the pixel electrode, the electric field is inclined to the outside of the slit due to the electric field discrete effect, and the liquid crystal molecules are inclined to the inside of the slit. Then, the liquid crystal molecules are inclined to the outside of the protrusion due to the shape effect of the protrusions, and therefore, it is possible to achieve good alignment division by combining both substrates so that the liquid crystal molecules are aligned in the tilt direction.

Furthermore, it is possible to divide the liquid crystal layer into a plurality of domains by providing the slit pattern and the protrusion pattern with anisotropy in a plurality of different directions. For example, the pixel electrode slit and the counter electrode In some cases, the projections are formed so as to have anisotropy in four directions that are different from each other by approximately 90 ° with respect to the edges of the substrates (see, for example, Patent Document 1).
JP 2002-229037 A

  With the recent expansion of moving picture distribution, moving picture response characteristics are particularly emphasized as a requirement for liquid crystal display elements. However, although the MVA mode has better response characteristics of the liquid crystal layer as compared with the TN mode, there is a problem that it is insufficient particularly in a halftone for viewing a moving image.

  In order to improve such a problem, for example, a liquid crystal display element for a television receiver can be considered as a measure such as overdrive driving in which a high voltage is temporarily applied in the first half of the frame. Problems such as increase and cost increase due to the drive circuit occur.

  The present invention has been made in view of these points, and an object of the present invention is to provide a liquid crystal display element that secures good display quality and moving image display characteristics while suppressing costs, and a method for manufacturing the same.

  The present invention includes a first substrate having a plurality of pixel electrodes, a second substrate having a common electrode and disposed opposite to the first substrate, and a plurality of the plurality of pixel electrodes interposed between the first substrate and the second substrate. A plurality of pixel regions sandwiched between the pixel electrode and the counter electrode. The liquid crystal layer includes a liquid crystal layer having a liquid crystal molecule and a liquid crystal composition having a negative dielectric anisotropy. A plurality of domains in which the tilt directions of the liquid crystal molecules are different from each other when a voltage is applied between the pixel electrode and the common electrode are formed in each pixel region. And a low pretilt angle region provided in each of the domains and having a pretilt angle of the liquid crystal molecules smaller than the other regions of the domain.

  Then, each of the plurality of domains formed in the pixel region is provided with a low pretilt angle region where the pretilt angle of the liquid crystal molecules is smaller than that of the other regions.

  The present invention also provides a first substrate having a plurality of pixel electrodes and a first alignment film, a second substrate having a common electrode and a second alignment film, and disposed opposite to the first substrate, and the first substrate. And a liquid crystal layer formed of a liquid crystal composition having a plurality of liquid crystal molecules and having a negative dielectric anisotropy interposed between the first alignment film and the second alignment film of the second substrate. A plurality of pixel regions sandwiched between the pixel electrode and the counter electrode are formed in the liquid crystal layer, and each pixel is applied with a voltage applied between the pixel electrode and the common electrode. A structure that divides the region into a plurality of domains in which the tilt directions of the liquid crystal molecules are different from each other; a low pretilt angle region that is provided in each of the domains and that has a smaller pretilt angle of the liquid crystal molecules than other regions of the domain; A method of manufacturing a liquid crystal display device comprising , Wherein by irradiating ultraviolet light to the first alignment film and the second alignment film and forms a low pretilt angle region.

  Then, each of the plurality of domains formed in the pixel region is irradiated with ultraviolet light to the first alignment film and the second alignment film in a low pretilt angle region in which the pretilt angle of the liquid crystal molecules is smaller than the other regions. It is provided.

  Furthermore, the present invention provides a first substrate having a plurality of pixel electrodes and a first alignment film, a second substrate having a common electrode and a second alignment film and disposed opposite to the first substrate, and the first substrate. And a liquid crystal layer formed of a liquid crystal composition having a plurality of liquid crystal molecules and having a negative dielectric anisotropy interposed between the first alignment film and the second alignment film of the second substrate. A plurality of pixel regions sandwiched between the pixel electrode and the counter electrode are formed in the liquid crystal layer, and each pixel is applied with a voltage applied between the pixel electrode and the common electrode. A structure that divides the region into a plurality of domains in which the tilt directions of the liquid crystal molecules are different from each other; a low pretilt angle region that is provided in each of the domains and that has a smaller pretilt angle of the liquid crystal molecules than other regions of the domain; For manufacturing a liquid crystal display device comprising There are, the and forms a low pretilt angle region by irradiating an ion beam with respect to the first alignment film and the second alignment layer.

  Then, each of the plurality of domains formed in the pixel region is irradiated with an ion beam to the first alignment film and the second alignment film in a low pretilt angle region in which the pretilt angle of the liquid crystal molecules is smaller than in the other regions. It is provided.

  The present invention also provides a first substrate having a plurality of pixel electrodes and a first alignment film, a second substrate having a common electrode and a second alignment film, and disposed opposite to the first substrate, and the first substrate. And a liquid crystal layer formed of a liquid crystal composition having a plurality of liquid crystal molecules and having a negative dielectric anisotropy interposed between the first alignment film and the second alignment film of the second substrate. A plurality of pixel regions sandwiched between the pixel electrode and the counter electrode are formed in the liquid crystal layer, and each pixel is applied with a voltage applied between the pixel electrode and the common electrode. A structure that divides the region into a plurality of domains in which the tilt directions of the liquid crystal molecules are different from each other; a low pretilt angle region that is provided in each of the domains and that has a smaller pretilt angle of the liquid crystal molecules than other regions of the domain; A method of manufacturing a liquid crystal display device comprising What is intended to form the low pretilt angle region by performing predetermined rubbing the first alignment film and the second alignment layer.

  Then, each of the plurality of domains formed in the pixel region is rubbed with respect to the first alignment film and the second alignment film with a low pretilt angle region in which the pretilt angle of the liquid crystal molecules is smaller than the other regions. Provide.

  According to the present invention, it is possible to improve the response characteristics of the liquid crystal molecules in each domain of the pixel area by the low pretilt angle area, and to secure good display quality and moving image display characteristics while suppressing the cost.

  Further, according to the present invention, a low pretilt angle region can be easily obtained.

  Hereinafter, the configuration of a liquid crystal display element according to an embodiment of the present invention will be described with reference to FIGS.

  In FIG. 3, reference numeral 1 denotes a liquid crystal cell as a liquid crystal display element, and this liquid crystal cell 1 is combined with a backlight (not shown) as a planar light source device that irradiates planar white light (monochromatic light). A so-called transmissive liquid crystal display device that transmits and uses light from the backlight is configured.

  The liquid crystal cell 1 is a multi-domain VAN mode (hereinafter referred to as MVA mode) active matrix TFT liquid crystal display. A liquid crystal layer 4 serving as a light modulation layer includes an array substrate 5 as a first substrate and the array. It is interposed between a substrate 5 and a counter substrate 6 as a second substrate disposed to face the substrate 5. The liquid crystal cell 1 is provided with columnar spacers 8 that are interval holding members for holding intervals between the substrates 5 and 6, and the substrate is formed by an adhesive layer 9 such as a thermosetting resin surrounding the liquid crystal layer 4. 5 and 6 are bonded to each other to form a quadrangular display region having sub-pixels P as a plurality of pixels arranged in a matrix. Further, polarizing plates 11 and 12 are attached to the outer main surfaces of the substrates 5 and 6. The liquid crystal cell 1 can display, for example, an interlaced image by a drive circuit (not shown).

  The liquid crystal layer 4 is composed of a liquid crystal composition having negative dielectric anisotropy. That is, the liquid crystal molecules LC of the liquid crystal layer 4 are substantially vertical when no voltage is applied between the substrates 5 and 6.

  As shown in FIGS. 1 to 3, the array substrate 5 includes a plurality of scanning lines 16 and a plurality of auxiliary capacitors (not shown) parallel to the scanning lines 16 on a transparent substrate 15 which is a glass substrate as an insulating substrate. Lines and a plurality of signal lines 17 are arranged in a lattice pattern, and TFTs 18 serving as switching elements are provided at intersections between the scanning lines 16 and the signal lines 17. A pixel electrode 19 that is electrically connected to the TFT 18 is provided in the vicinity of the TFT 18. Further, an insulating protective film 21 having translucency is provided to cover the TFT 18 and the pixel electrode 19, and a vertical alignment film 22 as a first alignment film is provided to cover the protective film 21.

  Each scanning line 16 is electrically connected at one end to a scanning line driving IC which is driving means (not shown).

  Each auxiliary capacitance line forms an auxiliary capacitance between the pixel electrode 19 and is alternately provided with the scanning lines 16 in the vertical direction in FIG.

  Each signal line 17 is formed so as to be substantially orthogonal to the scanning line 16, and one end thereof is electrically connected to a signal line driving IC which is driving means (not shown).

  Each TFT 18 is of a channel protection type, for example, on a gate electrode 25 extended from the scanning line 16, a predetermined gate insulating film layer 26, a semiconductor layer 27, a low resistance semiconductor layer 28 as a contact layer, and a predetermined An etching protective film 29 is laminated, and a drain electrode 31 and an island-shaped source electrode 32 that are electrically connected via the low-resistance semiconductor layer 28 are provided on the low-resistance semiconductor layer 28, respectively. The source electrode 32 is electrically connected to the pixel electrode 19. These TFTs 18 are turned on / off by a scanning signal supplied from the scanning line driving IC to the gate electrode 25 via each scanning line 16, and in synchronization with this on / off timing, the TFT 18 is passed from the signal line driving IC via the signal line 17. Then, the pixel signal supplied to the source electrode 32 is written into the pixel electrode 19 through the drain electrode 31, thereby displaying an image.

  The pixel electrode 19 is formed of, for example, a transparent member such as ITO. The pixel electrode 19 is formed in a substantially square shape for each sub-pixel P, and a corner portion where the TFT 18 is located is cut out. In addition, slits S are formed between adjacent pixel electrodes 19, respectively.

  On the other hand, the counter substrate 6 is formed with a color filter layer 37 including colored layers 37r, 37g, and 37b corresponding to the three primary colors of RGB on a transparent substrate 35 that is a glass substrate as an insulating substrate. On the color filter layer 37, spacers 8 are respectively formed at positions corresponding to the sub-pixels P by using the same material as the colored layers 37r, 37g, 37b, for example. Further, on the color filter layer 37, a common electrode, that is, a counter electrode 41, which is a transparent electrode as an electrode formed of a transparent member such as ITO, is formed at a position corresponding to each sub-pixel P. On the counter electrode 41, a bowl-shaped counter protrusion 42 as a structure is formed to protrude toward the array substrate 5 at a position corresponding to each sub-pixel P by using a light-shielding material, for example. Yes. In addition, a frame 43 which is a light shielding region surrounding the periphery of the display region is formed on the periphery of the color filter layer 37 by using, for example, the same material as the opposing protrusion 42. The three subpixels P corresponding to the colored layers 37r, 37g, and 37b of the color filter layer 37 constitute one pixel portion. Further, a vertical alignment film 45 as a second alignment film is formed on the counter electrode 41 so as to cover the counter electrode 41 and the counter protrusion 42.

  Here, the vertical alignment film 45 is for aligning the liquid crystal molecules LC together with the vertical alignment film 22 on the array substrate 5 side. The vertical alignment regulating force is strengthened by including a unit (not shown) that regulates the alignment perpendicular to the main surface of the substrate.

  The opposing protrusions 42 are linearly formed along the longitudinal direction (vertical direction in FIG. 1) in the center region in the width direction (horizontal direction in FIG. 1) of each pixel electrode 19. Therefore, in the pixel region AP sandwiched between the pixel electrode 19 corresponding to each subpixel P and the counter electrode 41, the pixel electrode 19 of the array substrate 5 and the counter electrode 41 of the counter substrate 6 are formed on both sides of the counter projection 42. A plurality of domains D1 and D2 having different inclination directions of the liquid crystal molecules LC when a voltage is applied between them (hereinafter simply referred to as a voltage application state) are formed. Further, in the central region in the width direction of each of the domains D1 and D2, that is, in the middle portion between both side portions of the pixel electrode 19 and the opposing protrusion 42, the pixel electrode 19 of the array substrate 5 and the opposing electrode 41 of the opposing substrate 6 are provided. A low pretilt angle region 47 (see FIG. 5) in which a tilt angle in a state where no voltage is applied between them (hereinafter simply referred to as no voltage application state), that is, a pretilt angle is a predetermined angle smaller than the other regions in the domains D1 and D2. 4) is formed in a band shape having a predetermined width dimension. Therefore, in each of the domains D1 and D2, normal pretilt angle regions 48 and 48 having a pretilt angle of approximately 90 ° are formed on the left and right sides of the low pretilt angle region 47 in FIG.

  The low pretilt angle region 47 reduces the units in each of the vertical alignment films 22 and 45 by, for example, irradiating the vertical alignment films 22 and 45 with ultraviolet (UV) light or irradiating a predetermined ion beam. For example, the liquid crystal molecules LC can be formed by reducing the vertical alignment regulating force or subjecting the vertical alignment films 22 and 45 to a predetermined rubbing process to bring the unit close to the substrates 5 and 6 in parallel. The predetermined pretilt angle is set to about °.

  In general, in the MVA mode, a normally black mode is used in which black display is obtained by aligning the liquid crystal molecules LC substantially vertically with respect to the respective substrates 5 and 6 in a state where no voltage is applied. If the width dimension of the low pretilt angle region 47 is too large, the liquid crystal molecules LC may approach the tilted alignment even when no voltage is applied, and light from the backlight may leak. Is preferably set to a minimum dimension that provides a desired response characteristic.

  The spacer 8 includes a first layer 51 located in the color filter layer 37, a second layer 52 located on the first layer 51, and a third layer in contact with the array substrate 5 side on the second layer 52. 53 and formed.

  Next, the operation of the above embodiment will be described.

  In the liquid crystal cell 1, an image signal transmitted from a computer or the like and converted by each driver IC is written to each pixel electrode 19 by driving the TFT 18 which is turned on by the scanning signal. The tilt of the liquid crystal molecules LC in the domains D1 and D2 changes from the vertical state to the tilted state.

  In other words, the liquid crystal molecule LC has the right side in FIG. 1 in the domain D1 due to the action of the opposing protrusion 42 and the inclination of the electric field outside the slit S due to the electric field discrete effect between the pixel electrode 19 and the opposing electrode 41. In the direction, the domain D2 is inclined in the left direction in FIG. 1, in other words, in an opposite direction between the adjacent domains D1 and D2.

  At this time, immediately after the voltage application, the response of the liquid crystal molecules LC is started at the opposing protrusions 42 and the side edges of the pixel electrode 19, and propagates toward the intermediate part between the opposing protrusions 42 and the side edges of the pixel electrode 19. Go.

  For this reason, in the normal pretilt angle regions 48 and 48 of the domains D1 and D2, the liquid crystal molecules LC are inclined according to the magnitude of the voltage from a substantially vertical state, and in the low pretilt angle region 47, a predetermined pretilt angle is obtained. From the tilted state, the tilted state is set according to the magnitude of the voltage.

  As a result, according to the embodiment, in the MVA mode liquid crystal cell 1, the response characteristics of the liquid crystal molecules LC in the domains D1 and D2 of the pixel region AP corresponding to the subpixel P are obtained by the low pretilt angle region 47. The display quality can be improved, and bright and good display quality and good moving image display can be obtained.

  In addition, the opposing protrusion 42 is provided in the center of each of the domains D1 and D2, and the low pretilt angle region 47 is provided in an intermediate portion between the opposite side edges of the pixel electrode 19, so that the opposite protrusion 42 and the opposite side edges of the pixel electrode 19 are provided. The response characteristics of the liquid crystal molecules LC in the intermediate portion where the response is slowest because it propagates toward the intermediate portion between the opposite protrusion 42 and the both side edges of the pixel electrode 19 can be improved. A display is obtained.

  Furthermore, by setting the width dimension of the low pretilt angle region 47 so that the liquid crystal molecules LC in a state where no voltage is applied is not too close to the tilt alignment, light leakage in the low pretilt angle region 47 is prevented, and Contrast can be obtained.

  In the conventional case, for example, in which the response characteristic of the liquid crystal layer is improved by overdrive driving, there are problems such as an increase in power consumption and an increase in cost due to the driving circuit. There is no need to increase power or to provide a separate drive circuit, and costs can be reduced.

  In addition, the low pretilt angle region 47 can be easily formed by irradiating with ultraviolet light or an ion beam or performing a predetermined rubbing process, and the manufacturing cost does not increase more than necessary.

  In addition, it cannot be overemphasized that said one Embodiment does not limit this invention and can be used in various changes within the range of the summary of this invention.

  Next, for Examples 1 to 3 of the liquid crystal display device and Comparative Examples 1 and 2, the contrast ratio, the response speed of the liquid crystal layer 4 and the display quality were evaluated.

  Example 1 has the structure shown in the above embodiment, and the TFT 18 and the liquid crystal cell 1 were formed by repeating film formation and patterning using a general process.

  That is, the array substrate 5 is formed by sputtering molybdenum (Mo) with a film thickness of, for example, 0.3 μm, patterning the scanning lines 16, the gate electrodes 25, and the auxiliary capacitance lines into a predetermined shape by photolithography, In addition, a gate insulating film layer 26 made of, for example, a silicon oxide film having a thickness of 0.15 μm is formed, the semiconductor layer 27 is made of, for example, amorphous silicon (a-Si), and the etching protection film 29 is made of, for example, silicon nitride. did.

  Then, for example, ITO is formed into a film with a thickness of about 0.1 μm by sputtering, the pixel electrode 19 is formed in a predetermined pattern by photolithography, and further, aluminum (Al) is formed by sputtering with a film thickness of 0.3 μm. Then, the signal line 17, the drain electrode 31 extending from the signal line 17 onto the low-resistance semiconductor layer 28, and the island-like source electrode 32 were simultaneously formed by photolithography to form the TFT 18. Further, the upper protective film 21 was formed of, for example, silicon nitride.

  On the other hand, the counter substrate 6 is coated with a photosensitive resist in which a red pigment is dispersed, and by photolithography, a red colored layer 37r and a first layer 51 of the spacer 8 which is a projection having a size of 33 × 33 μm, for example, Formed simultaneously.

  Similarly, the green colored layer 37g and the second layer 52 of the spacer 8 which is a projection having a size of 26 × 26 μm, for example, are simultaneously formed, and the blue colored layer 37b and a projection having a size of, for example, 22 × 22 μm are formed. The third layer 53 of the spacer 8 is formed at the same time, and the color filter layer 37 having a thickness of about 1.5 μm and the spacer 8 are formed.

  Thereafter, for example, ITO is sputtered to a film thickness of about 0.1 μm to form the counter electrode 41, and further, a black resin resist is used to form a hook-shaped counter projection 42 and a frame 43 in parallel with the long side of the sub-pixel P. At the same time, a pattern was formed.

Then, after the vertical alignment film 22 and the vertical alignment film 45 are applied to the array substrate 5 and the counter substrate 6 formed in this way with a thickness of, for example, 70 nm, the counter protrusions 42 are formed using a photomask. The pretilt angle of the liquid crystal molecules LC was lowered by irradiating 5 J / m ² of ultraviolet light in parallel with the opposing protrusions 42 with a width of 5 μm, for example, at an intermediate portion with the side edge of the pixel electrode 19. Separately, when the pretilt angle was measured with a liquid crystal cell that was simply created under the same conditions, the pretilt angle in the untreated state corresponding to the normal pretilt angle region 48 was 90 °, whereas the low pretilt angle was It was confirmed that the pretilt angle in the post-processing state corresponding to the region 47 was reduced to 22 °.

  Furthermore, for example, an adhesive layer 9 is used to bond the array substrate 5 and the counter substrate 6 at a predetermined position using an adhesive made of an epoxy thermosetting resin, and a liquid crystal composition having a negative dielectric anisotropy is formed vertically. After filling the alignment films 22 and 45 to form the liquid crystal cell 1, the liquid crystal composition inlet was sealed with, for example, an ultraviolet curable resin. The size of the sub-pixel P is set to 40 μm × 120 μm, for example, and the width dimension of the opposing protrusion 42 and the width dimension of the slit S between the pixel electrodes 19 between the adjacent sub-pixels P and P are each designed to be 10 μm, for example.

  Further, in the second embodiment, in the first embodiment, the pretilt angle of the liquid crystal molecules LC is lowered by irradiating the vertical alignment films 22 and 45 with an ion beam instead of the ultraviolet light, thereby reducing the low pretilt angle region 47. Formed. At this time, when the pretilt angle was measured with a liquid crystal cell simply and separately prepared under the same conditions, the pretilt angle in the untreated state corresponding to the normal pretilt angle region 48 was 90 °, whereas it was low pretilt. It was confirmed that the pretilt angle in the post-process state corresponding to the corner region 47 was reduced to 20 °. Except for this point, Example 2 was created with the same design and process as Example 1.

  Further, in Example 3, the low pretilt angle region 47 is formed by lowering the pretilt angle of the liquid crystal molecules LC by subjecting the vertical alignment films 22 and 45 to rubbing treatment instead of ultraviolet light in the above Example 1. Formed. At this time, when the pretilt angle was measured with a liquid crystal cell simply and separately prepared under the same conditions, the pretilt angle in the untreated state corresponding to the normal pretilt angle region 48 was 90 °, whereas it was low pretilt. It was confirmed that the pretilt angle in the post-process state corresponding to the corner region 47 was reduced to 18 °. Except for this point, Example 3 was created with the same design and process as Example 1.

  On the other hand, Comparative Example 1 was prepared by the same design and process as Example 1 except that ultraviolet light was not irradiated.

  Further, Comparative Example 2 was created by the same design and process as Example 1 except that the width dimension of the low pretilt angle region 47 was set to 10 μm.

  Then, comparing Examples 1 to 3 with Comparative Examples 1 and 2, in Example 1, as shown in FIG. 5, the response speed of the liquid crystal layer 4 from the transmittance of 10% to the transmittance of 90% is 8 ms. In Example 2, it was 10 ms, and in Example 3, it was 9 ms, which was improved with respect to 22 ms in Comparative Example 1, and good moving image display could be obtained.

  Further, when the contrast ratio was calculated by measuring the luminance in a state where voltages of 0 V and 5 V were applied between the substrates 5 and 6, it was 490 in Example 1, 500 in Example 2, and 480 in Example 3. A contrast ratio equivalent to 500 of Comparative Example 1 was obtained, and good display quality was obtained. In Comparative Example 2, the contrast ratio was greatly reduced to 260. As a result of observing each subpixel P in detail, in Comparative Example 2, light leakage was observed in the low pretilt angle region 47, whereas in Examples 1 to 3, a good alignment state was obtained. It could be confirmed.

It is a top view which shows the principal part of the liquid crystal display element of one embodiment of this invention. It is AA sectional drawing of FIG. 1 of a liquid crystal display element same as the above. It is a longitudinal cross-sectional view which shows a part of liquid crystal display element same as the above. It is explanatory sectional drawing which shows each domain of a liquid crystal display element same as the above. It is a table | surface which shows the comparison with Example 1 thru | or 3 of the liquid crystal display element same as the above, and the comparative examples 1 and 2. FIG.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Liquid crystal cell as a liquid crystal display element 4 Liquid crystal layer 5 Array substrate as 1st substrate 6 Opposite substrate as 2nd substrate
19 Pixel electrode
22 Vertical alignment film as the first alignment film
41 Counter electrode as common electrode
42 Opposite protrusions as structures
45 Vertical alignment film as second alignment film
47 Low pretilt angle region
AP pixel area
D1, D2 domain
LC liquid crystal molecules

Claims (5)

A first substrate having a plurality of pixel electrodes; a second substrate having a common electrode and disposed opposite to the first substrate; and a plurality of liquid crystal molecules interposed between the first substrate and the second substrate. And a liquid crystal layer formed of a liquid crystal composition having negative dielectric anisotropy, and a plurality of pixel regions sandwiched between the pixel electrode and the counter electrode are formed in the liquid crystal layer A liquid crystal display element,
A structure that forms a plurality of domains in each pixel region in which the tilt directions of the liquid crystal molecules are different from each other in a state where a voltage is applied between the pixel electrode and the common electrode;
A liquid crystal display element comprising: a low pretilt angle region provided in each of the domains, wherein the pretilt angle of the liquid crystal molecules is smaller than that of other regions of the domain. The structure is provided in a central portion of each pixel region,
The liquid crystal display element according to claim 1, wherein the low pretilt angle region is located in an intermediate portion between the structure and an edge of the pixel electrode. A first substrate having a plurality of pixel electrodes and a first alignment film; a second substrate having a common electrode and a second alignment film and disposed opposite to the first substrate; and a first alignment film of these first substrates; A liquid crystal layer interposed between the second alignment film of the second substrate and having a plurality of liquid crystal molecules and having a negative dielectric anisotropy. A plurality of pixel regions sandwiched between the pixel electrode and the counter electrode are formed, and each pixel region is formed of the liquid crystal molecule in a state where a voltage is applied between the pixel electrode and the common electrode. A liquid crystal display device comprising: a structure that is divided into a plurality of domains having different tilt directions; and a low pretilt angle region that is provided in each domain and has a smaller pretilt angle of the liquid crystal molecules than other regions of the domain A manufacturing method of
The method of manufacturing a liquid crystal display element, wherein the low pretilt angle region is formed by irradiating the first alignment film and the second alignment film with ultraviolet light. A first substrate having a plurality of pixel electrodes and a first alignment film; a second substrate having a common electrode and a second alignment film and disposed opposite to the first substrate; and a first alignment film of these first substrates; A liquid crystal layer interposed between the second alignment film of the second substrate and having a plurality of liquid crystal molecules and having a negative dielectric anisotropy. A plurality of pixel regions sandwiched between the pixel electrode and the counter electrode are formed, and each pixel region is formed of the liquid crystal molecule in a state where a voltage is applied between the pixel electrode and the common electrode. A liquid crystal display device comprising: a structure that is divided into a plurality of domains having different tilt directions; and a low pretilt angle region that is provided in each domain and has a smaller pretilt angle of the liquid crystal molecules than other regions of the domain A manufacturing method of
The method of manufacturing a liquid crystal display element, wherein the low pretilt angle region is formed by irradiating the first alignment film and the second alignment film with an ion beam. A first substrate having a plurality of pixel electrodes and a first alignment film; a second substrate having a common electrode and a second alignment film and disposed opposite to the first substrate; and a first alignment film of these first substrates; A liquid crystal layer interposed between the second alignment film of the second substrate and having a plurality of liquid crystal molecules and having a negative dielectric anisotropy. A plurality of pixel regions sandwiched between the pixel electrode and the counter electrode are formed, and each pixel region is formed of the liquid crystal molecule in a state where a voltage is applied between the pixel electrode and the common electrode. A liquid crystal display device comprising: a structure that is divided into a plurality of domains having different tilt directions; and a low pretilt angle region that is provided in each domain and has a smaller pretilt angle of the liquid crystal molecules than other regions of the domain A manufacturing method of
A method of manufacturing a liquid crystal display element, wherein the low pretilt angle region is formed by performing predetermined rubbing on the first alignment film and the second alignment film.

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