JP2007052270A - Liquid crystal display apparatus and method for manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a transflective liquid crystal display apparatus using a MVA (multi-domain vertical aligned nematic mode) system with improved manufacture efficiency and to provide a method for manufacturing the apparatus. <P>SOLUTION: The liquid crystal display apparatus comprises an array substrate AR where a plurality of pixels PX including reflective electrodes 21 and transmissive electrodes 31 are laid in a matrix, a counter substrate CT where a counter electrode 42 laid as common corresponding to the plurality of pixels PX, a first protruding structure 32 laid corresponding to the transmissive electrodes 31, and a second protruding structure 22 laid corresponding to the reflective electrodes 21 and formed on the same plane in the same height as the first protruding structure 22, and a liquid crystal layer LQ disposed between the array substrate AR and the counter substrate CT disposed to face each other. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a liquid crystal display device and a manufacturing method thereof, and in particular, includes a reflection unit that displays an image by reflecting external light in one pixel and a transmission unit that displays an image by transmitting backlight light. The present invention relates to a transflective liquid crystal display device and a manufacturing method thereof.

  Since the liquid crystal display device has features such as light weight, thinness, and low power consumption, it is applied to various fields such as OA equipment, information terminals, watches, and televisions. In particular, a liquid crystal display device having a thin film transistor (hereinafter referred to as a TFT element) is used as a monitor for displaying a large amount of information, such as a mobile phone, a television, or a computer, because of its high responsiveness.

  In recent years, with the increase in the amount of information and the reduction in size and weight of portable terminals, display devices with high definition and a wide viewing angle are required. Of these requirements, high definition of an image is realized, for example, by miniaturizing a TFT array structure. On the other hand, with respect to a wide viewing angle, an OCB (Optically Compensated Bend) method using a nematic liquid crystal, a VAN (Vertical Aligned Nematic) mode, a HAN (Hybrid Aligned Nematic) mode, an IPS (In-Plane mode, etc.) Adoption of a display mode is being studied.

  Among these display modes, the VAN mode can obtain a faster response speed than the conventional TN (Twisted Nematic) mode and has a rubbing process (an interface in contact with the liquid crystal) that causes a failure such as electrostatic breakdown due to vertical alignment. It is not necessary to apply a polymer thin film to the surface and rub it in a certain direction with a cloth. For this reason, generation | occurrence | production of the dust in a process, defects, such as a rubbing nonuniformity, can be avoided and it is excellent in productivity. Among them, the multi-domain VAN mode (referred to as MVA mode) is particularly attracting attention because the viewing angle compensation design is relatively easy.

  Further, in recent years, since the frequency of outdoor use has increased, in addition to the conventional transmissive display method, a transflective liquid crystal method capable of partially performing reflective display has been put into practical use. This transflective liquid crystal display device includes a reflective portion having a reflective electrode and a transmissive portion having a transmissive electrode in one pixel. Such a transflective liquid crystal display device functions as a transmissive liquid crystal display device that displays an image by selectively transmitting backlight light using a transmissive portion in a pixel in a dark place. In this place, it functions as a reflective liquid crystal display device that displays an image by selectively reflecting outside light using a reflection portion in the pixel. Thereby, power consumption can be reduced significantly.

However, in the liquid crystal display device adopting the MVA mode as described above, in order to control the tilt direction of the liquid crystal molecules when a voltage is applied, is it necessary to form a hook-like projection structure on the array substrate, the counter substrate, or both? Alternatively, it is necessary to provide a slit in the common electrode on the counter substrate. Further, in the transflective liquid crystal display device as described above, in order to make the thickness of the liquid crystal layer for reflection display about half of the thickness of the liquid crystal layer for transmission, a convex structure is formed under the reflective electrode, It is necessary to control the thickness of the liquid crystal layer.
Thus, since it is necessary to form a hook-like protrusion structure or a convex structure on each of the counter substrate and the array substrate, an increase in the number of manufacturing steps (number of processes), an increase in the number of masks, or a hook-like protrusion structure or a convex structure There is a problem that causes an increase in management items such as film thickness control.
In addition, this increases the manufacturing cost and makes the manufacturing process complicated, resulting in a problem of yield reduction.
An object of the present invention is to provide a transflective liquid crystal display device using the MVA method having high manufacturing efficiency and a wide viewing angle, and a method for manufacturing the same.

According to one embodiment of the present invention, a liquid crystal display device according to the present invention includes a first substrate in which a plurality of pixels each including a reflective electrode and a transmissive electrode are arranged in a matrix on a first insulating substrate; On the insulating substrate, the counter electrode provided in common corresponding to the plurality of pixels, the first convex structure disposed corresponding to the transmissive electrode, and the reflective electrode are disposed corresponding to the reflective electrode. A second convex structure formed on the same plane as the first convex structure and having the same height, and a second substrate disposed opposite to the first substrate, and the first substrate, And a liquid crystal layer disposed between the second substrate and the second substrate.
Further, according to one embodiment of the present invention, a method for manufacturing a liquid crystal display device according to the present invention includes a first substrate in which a plurality of pixels including a reflective electrode and a transmissive electrode are arranged in a matrix on a first insulating substrate. And a second substrate provided with a counter electrode arranged in common on the second insulating substrate corresponding to the plurality of pixels, and the transmission electrode on the counter electrode of the second substrate And a first convex structure corresponding to the reflective electrode and a second convex structure corresponding to the reflective electrode are formed simultaneously, and the first substrate and the second substrate are bonded together, and the first substrate and the first substrate are bonded together. A liquid crystal layer containing liquid crystal molecules is formed between the two substrates.

  It is possible to provide a transflective liquid crystal display device using the MVA method having high manufacturing efficiency and a wide viewing angle, and a manufacturing method thereof.

  A liquid crystal display device according to an embodiment of the present invention will be described below with reference to the drawings. FIG. 1 schematically shows a configuration of a liquid crystal display device according to an embodiment of the present invention. FIG. 2 is a cross-sectional view showing a basic configuration of the liquid crystal display element shown in FIG. 3A and 3B are schematic views of the counter substrate and the array substrate shown in FIGS. 1 and 2 as viewed from the liquid crystal layer side.

  As shown in FIG. 2, the liquid crystal display device is an active matrix type transflective color liquid crystal display device and includes a liquid crystal display panel LPN. The liquid crystal display panel LPN includes an array substrate (first substrate) AR, a counter substrate (second substrate) CT disposed opposite to the array substrate AR, and the array substrate AR and the counter substrate CT. And a liquid crystal layer LQ held therebetween.

  Further, the liquid crystal display device is opposite to the first polarization control element POL1 provided on the outer surface opposite to the surface holding the liquid crystal layer LQ of the array substrate AR and the surface holding the liquid crystal layer LQ of the counter substrate CT. Is provided with a second polarization control element POL2. Further, the liquid crystal display device includes a backlight unit BL that illuminates the liquid crystal display panel LPN from the first polarization control element POL1 side.

  As shown in FIG. 1, such a liquid crystal display device includes a plurality of pixels PX arranged in a matrix of m × n in a display area DSP that displays an image. As shown in FIG. 2, each pixel PX includes a reflection part PR that displays an image by reflecting external light, and a transmission part PT that displays an image by transmitting backlight light from the backlight unit BL. ,have.

  The array substrate AR is formed using a translucent insulating substrate 10 such as a glass plate or a quartz plate. That is, the array substrate AR includes m × n pixel electrodes EP arranged for each pixel in the display region DSP, and n scanning lines Y (Y1 to Y1) respectively formed along the rows of the pixel electrodes EP. Yn), m signal lines X (X1 to Xm) formed along the columns of the pixel electrodes EP, m × x arranged for each pixel in the vicinity of the intersection position of the corresponding scanning line Y and the corresponding signal line X. Auxiliary capacitance lines formed in substantially parallel to the n scanning lines Y by capacitively coupling to the pixel electrodes EP in the corresponding rows so as to constitute the auxiliary capacitances CS in parallel with the n switching elements, ie, the thin film transistors W and the liquid crystal capacitance CLC. AY etc. An insulating layer 11 is formed between the pixel electrode EP and the auxiliary capacitor CS.

  As shown in FIG. 1, the array substrate AR further includes a scanning line driver YD connected to n scanning lines Y and m signal lines X in the driving circuit area DCT around the display area DSP. It has a connected signal line driver XD. The scanning line driver YD sequentially supplies scanning signals (driving signals) to the n scanning lines Y based on control by the controller CNT. The signal line driver XD supplies video signals (drive signals) to the m signal lines X every time the thin film transistors W in each row are turned on by the scanning signal based on the control by the controller CNT. Thereby, the pixel electrodes EP in each row are set to pixel potentials corresponding to the video signals supplied via the corresponding thin film transistors W, respectively.

  As shown in FIGS. 2 and 3A, 3B, the pixel electrode EP includes a reflective electrode 21 provided corresponding to the reflective part PR and a transmissive electrode 31 provided corresponding to the transmissive part PT. Have. The reflective electrode 21 is disposed on the insulating layer 11 and is electrically connected to the thin film transistor W. The reflective electrode 21 is formed of a metal reflective film such as aluminum. The transmissive electrode 31 is disposed on the same plane as the surface on which the reflective electrode 21 is formed, that is, on the insulating layer 11 and is electrically connected to the reflective electrode 21. The transmissive electrode 31 is formed of a translucent conductive film such as indium tin oxide (ITO).

  On the other hand, the counter substrate CT is formed using a translucent insulating substrate 40 such as a glass plate or a quartz plate. That is, the counter substrate CT includes a color filter layer 41, a counter electrode 42, a first convex structure 32, and a second convex structure 22 disposed on the translucent insulating substrate 40.

  In addition, alignment films 51 and 52 are provided on the interface of the array substrate AR and the counter substrate CT that are in direct contact with the liquid crystal layer LQ to give the liquid crystal molecules alignment in a direction perpendicular to the substrate, respectively. Thereby, the liquid crystal molecules are aligned such that their long axes are oriented in a direction perpendicular to the interface of the substrate. The alignment films 51 and 52 are preferably formed to a thickness of 70 nm to 90 nm, respectively.

  The color filter layer 41 includes a black matrix (not shown) that partitions each pixel PX in the display area DSP on the translucent insulating substrate 40, and a color filter (for each pixel surrounded by the black matrix). (Not shown). The black matrix is arranged so as to face wiring portions such as the scanning lines Y and the signal lines X provided on the array substrate AR. The color filter is formed of colored resins that are colored in three different primary colors such as red, blue, and green. The red colored resin, the blue colored resin, and the green colored resin are disposed corresponding to the red pixel, the blue pixel, and the green pixel, respectively.

  The counter electrode 42 is disposed so as to face the reflective electrode 21 and the transmissive electrode 31 of all the pixels PX. The counter electrode 42 is formed of a light-transmitting conductive film such as indium tin oxide (ITO) and is electrically connected to the auxiliary capacitance line AY.

  The first convex structure 32 is disposed at a position facing the transmission electrode 31 on the array substrate AR side, and the second convex structure 22 is disposed at a position facing the reflective electrode 21 on the array substrate AR side. More specifically, as shown in FIG. 3A, the first convex structure 32 is formed in a transmission region 33 of the counter substrate CT, which is a region facing the transmission electrode 31 of the array substrate AR. The rectangular transmission region 33 has a pattern parallel to the longitudinal direction (long side 33 </ b> L), and is arranged at the approximate center on the transmission region 33. Further, as shown in FIG. 3A, the second projecting structure 22 is formed in the same size as the reflective electrode 21 formed on the array substrate AR, and faces the array substrate AR as shown in FIG. In a state where the substrate CT is disposed to be opposed, the substrate CT is disposed so as to overlap the entire surface of the reflective electrode 21. Further, the first convex structure 32 and the second convex structure 22 are formed on the counter electrode 41, that is, on the same plane, with a thickness of 1.35 μm by an insulating material, for example, a photosensitive acrylic resist, in the same process. Has been. That is, the first convex structure 32 and the second convex structure 22 are formed of the same material on the same surface and have the same height.

  The array substrate AR and the counter substrate CT having the above-described configuration are arranged to face each other in a state where a predetermined gap, for example, a gap of 3.65 μm is formed by a columnar spacer (not shown) arranged in the effective display portion DSP. The peripheral portions are bonded together by, for example, a sealing material. Thus, a cell for injecting liquid crystal molecules is formed, and a liquid crystal layer LQ is formed by injecting and sealing a liquid crystal material (Nn liquid crystal material) exhibiting negative dielectric anisotropy into the cell. That is, the liquid crystal layer LQ is held between the alignment film 51 on the array substrate AR side and the alignment film 52 on the counter substrate CT side. Accordingly, a vertical alignment mode in which the liquid crystal molecules included in the liquid crystal layer LQ are vertically aligned by the alignment control by the alignment films 51 and 52 can be configured.

  With this configuration, division of the liquid crystal alignment is induced in the step portion of the first convex structure 32, and the alignment of the liquid crystal molecules has an arrangement in which the major axis is inclined at a specific angle from the direction perpendicular to the glass substrate. . The liquid crystal molecules positioned in the vicinity of the first convex structure 32 serve to regulate the tilt direction of other liquid crystal molecules. That is, a region in which the liquid crystal molecules are aligned in a predetermined direction (region in which the alignment directions of the liquid crystal molecules are aligned) is referred to as a domain, but a plurality of liquid crystal molecules are aligned in different directions on both sides of the first convex structure 32. A domain can be formed. For this reason, by forming the first convex structure 32 having a predetermined pattern, the inside of the transmission part PT can be divided into a plurality of domains. Further, by forming a plurality of these domains in one pixel region, an effect of compensating for anisotropy of liquid crystal molecules occurs, and a wide viewing angle can be realized.

  In addition, by providing the second convex structure 221 in the reflective portion PR, the actual voltage applied between the reflective electrode 21 and the counter electrode 42 is made lower than the actual voltage applied between the transmissive electrode 31 and the counter electrode 42. The polarization state can be changed. Thereby, the orientation of the liquid crystal molecules between the transmissive electrode 31 and the first convex structure 32 and the orientation of the liquid crystal molecules between the reflective electrode 21 and the second convex structure 22 can be made different.

  The first polarization control element POL1 and the second polarization control element POL2 described above control the polarization state of light passing through them, and form elliptically polarized light that enters the liquid crystal layer LQ. That is, the first polarization control element POL1 controls the polarization state of the backlight light incident on the first polarization control element POL1, and the polarization state of the light that has passed through the first polarization control element POL1, ie, the light immediately before entering the liquid crystal layer LQ, is elliptically polarized. Convert to The second polarization control element POL2 controls the polarization state of the external light incident thereon, and the polarization state of the light that has passed through the second polarization control element POL2, that is, the light immediately before entering the liquid crystal layer LQ, becomes elliptically polarized light. Convert.

  In the present embodiment, the first polarization control element POL1 includes a first polarizing plate 61 and a first retardation plate 62, and the second polarization control element POL2 includes a second polarizing plate 71 and a second retardation plate 72. Contains. The first retardation plate 62 and the second retardation plate 72 constituting the first polarization control element POL1 and the second polarization control element POL2 are, for example, between an ordinary ray and an extraordinary ray with respect to light of a predetermined wavelength. This is a so-called quarter-wave plate that gives a quarter-wave phase difference. Further, the first polarizing plate 61 and the second polarizing plate 71 applied here have an absorption axis and a transmission axis orthogonal to each other in a plane orthogonal to the traveling direction of light. Such a polarizing plate extracts light having a vibrating surface in one direction parallel to the transmission axis, that is, light having a linearly polarized light state, from light having a vibrating surface in a random direction.

  The light emitted from the transmissive part PT is light emitted from the backlight BL and passed through the liquid crystal layer LQ, but the light emitted from the reflective part PR travels back and forth through the liquid crystal layer LQ from the counter substrate CT side. Released. For this reason, in the conventional transflective liquid crystal display device, the thickness of the liquid crystal layer of the reflective portion is made half the thickness of the liquid crystal layer of the transmissive portion, so that the light emitted from the transmissive portion is polarized by the liquid crystal layer. The state and the polarization state of the light emitted from the reflecting portion by the liquid crystal layer can be controlled substantially the same.

  In the present embodiment, the gap between the transmissive part PT and the reflective part PR is substantially uniform, and the second convex structure 22 is formed at a predetermined position on the counter substrate CT side corresponding to the reflective electrode 21, thereby reflecting the gap. The actual voltage applied between the electrode 21 and the counter electrode 42 is made lower than the actual voltage applied between the transmissive electrode 31 and the counter electrode 42 to change the polarization state. Thereby, the thickness of the liquid crystal display device can be reduced.

  In the liquid crystal display device according to the present embodiment, it is preferable that the luminance of the image displayed as a result is in the same range when the transmissive part PT or the reflective part PR is used. If the difference between the voltage applied between the transmissive electrode 31 and the counter electrode 42 (second voltage) and the voltage applied between the transmissive electrode 31 and the counter electrode 42 (first voltage) is within 100 mV, the transmissive portion The applied voltage-luminance characteristics in the PT and the reflection part PR can be made equal.

  In the present embodiment, the maximum difference between the first voltage and the second voltage is 98 mV. As a result, the color reproducibility of the image displayed as a result can be matched with high precision in both the display by the transmission part PT and the display by the reflection part PR.

Next, an example of a method for manufacturing a liquid crystal display element having the basic configuration described above will be described.
First, wirings such as signal lines X and scanning lines Y, thin film transistors W, auxiliary capacitors CS, and insulating layers 11 are formed on the translucent insulating substrate 10 by a known method. Thereafter, the reflective electrode 21 is formed at a predetermined position on the insulating layer 11 and is simultaneously conducted to the thin film transistor W through a through hole (not shown) formed in the insulating layer 11, for example. Then, a transmissive electrode 31 is formed adjacent to the reflective electrode 21 and is conducted to the reflective electrode 21.

  Subsequently, a vertical alignment polyimide film having a thickness of 80 nm is formed as the alignment film 51 on the entire surface of the translucent insulating substrate 10 on which the reflective electrode 21 and the transmissive electrode 31 are formed. Thus, the array substrate AR is configured. Further, on the alignment film 51 of the array substrate AR, a spacer having a height of 3.65 μm is formed using, for example, an acrylic photosensitive resin on the wiring that is out of the pixel region.

  On the other hand, a color filter layer 41 and a common electrode 42 made of ITO are formed on the translucent insulating substrate 40 of the counter substrate CT. Then, a photosensitive resist material (for example, a photosensitive acrylic resist) is formed on the common electrode 42.

  Subsequently, a photosensitive acrylic resist film using a mask (not shown) for forming the first and second convex structures 32 and 22 corresponding to the reflective electrode 21 and the transmissive electrode 31, for example, by a parallel exposure apparatus. Then, development processing and etching processing are performed, followed by patterning. Thereby, the 1st, 2nd convex structures 32 and 22 of a shape as shown to Fig.3 (a) can be formed simultaneously.

Thereafter, a vertical alignment polyimide film having a thickness of 80 nm is formed on the entire surface as the alignment film 52. Thereby, the counter substrate CT is configured.
Subsequently, an epoxy-based thermosetting resin is applied as a sealant to the seal region around the counter substrate CT by a dispenser. Then, the array substrate AR and the counter substrate CT are bonded via a sealing material so that the alignment films 51 and 52 face each other, and heat treatment is performed while applying a predetermined load, whereby the sealing material is thermally cured. Thereby, a cell (not shown) for injecting liquid crystal molecules is formed. Thereafter, a liquid crystal material exhibiting negative dielectric anisotropy is injected into the cell and sealed. Thereby, the liquid crystal layer LQ is formed.

  Subsequently, the first polarization control element POL1 is adhered to the outer surface of the array substrate AR, that is, the outer surface of the translucent insulating substrate 10 via, for example, an adhesive (not shown), and the outer surface of the counter substrate CT, that is, the transparent insulating material. The second polarization control element POL2 is bonded to the outer surface of the substrate 40 through, for example, an adhesive (not shown). A liquid crystal display panel is completed through the above steps.

  As described above, in the liquid crystal display device according to the present embodiment, the tilt of the liquid crystal molecules in the liquid crystal layer LQ in a state where power is supplied to the reflective electrode 21 and the transmissive electrode 31 via the signal line X and the scanning line Y. The first and second convex structures 32 and 22 that are means for controlling the angle can be formed simultaneously. Thereby, since a manufacturing process can be simplified, manufacturing cost and manufacturing labor can be reduced, and productivity can be improved.

  Conventionally, the reflective display portion of the transflective liquid crystal display device has controlled the thickness of the liquid crystal layer by a convex structure formed under the electrode for applying a voltage to the liquid crystal layer of the array substrate or the counter substrate. However, in this method, the alignment control convex structure unique to the MVA mode is formed on the counter substrate side, and the liquid crystal layer thickness control convex structure for reflection display is formed under the reflective electrode of the array substrate. The number of management items such as the increase in the number, the number of masks, or the film thickness control may increase, and the yield may decrease.

  On the other hand, as described above, since the liquid crystal display device according to the present embodiment can form the first and second convex structures 32 and 22 at the same time, the number of processes and the number of masks can be reduced. Manufacturing efficiency can be improved.

  The gap between the array substrate AR and the counter substrate CT is allowed in the range of 3.65 ± 0.3 μm. The thickness of the photosensitive acrylic resist film for forming the first convex structure 32 and the second convex structure 22 is allowed in the range of 1.35 μm ± 0.2 μm.

  Further, as described above, the second convex structure 22 can be formed of a photosensitive resist material that can be processed by a conventional array process, but the present invention is not limited to this. For example, a material such as an acrylic resin, an epoxy resin, or a novolac resin that is used for orientation control for MVA is preferable.

  Furthermore, if the dielectric constant of this dielectric is lower than the dielectric constant of the liquid crystal material, a region having a weaker magnetic field is formed above the first and second convex structures 32 and 22 formed of these dielectrics. be able to. An example in which the actual voltage between the reflective electrode 21 and the counter electrode 42 is changed and the orientation is improved by adjusting the dielectric constant of the second convex structure 22 will be described below.

(Second Embodiment)
A liquid crystal display device according to the second embodiment will be described with reference to FIGS.

  4A and 4B are schematic views illustrating an example of a liquid crystal display device according to the second embodiment.

  As shown in FIGS. 4A and 4B, the reflective electrode 21 and the transmissive electrode 31 are formed on the array substrate AR, and the first convex structure 32 and the second convex structure 221 are formed on the counter substrate CT. Is formed. Among these, the constituent elements having the same numbers as those described above have the same configurations and functions as those described above, and thus detailed description thereof will be omitted.

  The second convex structure 221 is formed by the same process as the first convex structure 32 in the same manner as the second convex structure 22 described above, and has a predetermined pattern as shown in FIG. It has an uneven shape. In the present embodiment, the second convex structures 221 are provided substantially in parallel with each other at a substantially constant period in a quarter reflective region obtained by dividing the reflective region 221A corresponding to the rectangular reflective electrode 21 into four. Includes a plurality of convex portions arranged substantially parallel to the diagonal line of the reflection region 221A. Therefore, four domains having different tilt directions of liquid crystal molecules can be formed in the reflection region 221A of each pixel PX. Thereby, the inclination direction (polar angle) and in-plane direction (azimuth angle) of the liquid crystal molecules can be controlled. In addition, the orientation is improved, the effect of compensating the anisotropy of the liquid crystal molecules occurs, and a wide viewing angle can be realized.

  In the present embodiment, the plurality of convex portions are formed at intervals of 6 μm to 15 μm. Thereby, alignment uniformity can be improved. However, the present invention is not limited to this, and the balance of transmittance, image quality, and the like can be improved even if the pattern is in a range other than the period as described above.

  However, the present invention is not limited to this pattern, and may be a predetermined pattern that takes into account the balance of transmittance, image quality, and the like. Further, in order to control the viewing angle characteristics of the liquid crystal display device in detail, a pattern that forms the alignment direction (polar angle) or in-plane direction (azimuth angle) of predetermined liquid crystal molecules may be used.

  As described above, in the liquid crystal display device according to the present embodiment, the tilt of the liquid crystal molecules in the liquid crystal layer LQ in a state where power is supplied to the reflective electrode 21 and the transmissive electrode 31 via the signal line X and the scanning line Y. The first and second convex structures 32 and 221 that are means for controlling the angle can be formed simultaneously. Thereby, since a manufacturing process can be simplified, manufacturing cost and manufacturing labor can be reduced, and productivity can be improved.

  In addition, by providing the second convex structure 221 in the reflective part PR, as described above, the actual voltage applied between the reflective electrode 21 and the counter electrode 42 is made higher than the actual voltage applied between the transmissive electrode 31 and the counter electrode 42. And the polarization state can be changed. Thereby, the orientation of the liquid crystal molecules between the transmissive electrode 31 and the first convex structure 32 and the orientation of the liquid crystal molecules between the reflective electrode 21 and the second convex structure 221 can be made different. Further, the thickness of the liquid crystal layer LQ in the transmission part PT and the reflection part PR can be made equal.

  Furthermore, the dielectric constant of the 2nd convex structure 221 can be changed by forming such an uneven | corrugated shape. Thereby, the actual voltage value applied between the reflective electrode 21 and the counter electrode 42 can be adjusted. Therefore, the alignment of the liquid crystal molecules between the transmissive electrode 31 and the first convex structure 32 and the alignment of the liquid crystal molecules between the reflective electrode 21 and the second convex structure 221 can be made different. Further, the orientation is improved and a wide viewing angle can be realized. For this reason, the parameters for controlling the thickness of the liquid crystal layer of the liquid crystal display device are increased, the design margin is increased, and the yield is improved.

  In this manner, the liquid crystal display device according to the present embodiment forms the second convex structure 221 having a concave and convex shape with a predetermined pattern at a predetermined position on the counter substrate CT side corresponding to the reflective electrode 21. Thus, the dielectric constant of the second convex structure 221 can be adjusted. Furthermore, as described above, the polarization state can be changed by making the actual voltage applied between the reflective electrode 21 and the counter electrode 42 lower than the actual voltage applied between the transmissive electrode 31 and the counter electrode 42.

  Thereby, the luminance characteristics in the transmission part PT and the reflection part PR can be made equal, and a wide viewing angle can be realized.

  In the liquid crystal display device according to the present embodiment, the luminance of the image displayed as a result is preferably in the same range even when the transmissive part PT or the reflective part PR is used. If the difference between the voltage applied between the electrode 21 and the counter electrode 42 (second voltage) and the voltage applied between the transmissive electrode 31 and the counter electrode 42 (first voltage) is within 100 mV, The luminance characteristics in the transmissive part PT and the reflective part PR can be made equal.

  In the present embodiment, the maximum difference between the first voltage and the second voltage is 98 mV. As a result, the color reproducibility of the image displayed as a result can be matched with high precision in both the display by the transmission part PT and the display by the reflection part PR.

  Note that the present invention is not limited to the above-described embodiment as it is, and can be embodied by modifying the components without departing from the scope of the invention in the implementation stage. In addition, various inventions can be formed by appropriately combining a plurality of constituent elements disclosed in the embodiment. For example, some components may be deleted from all the components shown in the embodiment. Furthermore, constituent elements over different embodiments may be appropriately combined.

  For example, the first polarization control element POL1 has, as the first retardation plate 62, a ½ wavelength between an ordinary ray and an extraordinary ray with respect to light of a predetermined wavelength in addition to the ¼ wavelength plate described above. A so-called half-wave plate that provides a phase difference may be included. Similarly, the second polarization control element POL2 may include a ½ wavelength plate as the second retardation plate 72 in addition to the ¼ wavelength plate described above. Thereby, the change of the light transmittance by a wavelength can be suppressed. Furthermore, in the case of a design that widens the viewing angle, an optical element having a negative phase difference may be added.

FIG. 1 schematically shows a configuration of a liquid crystal display device according to an embodiment of the present invention. FIG. 2 is a cross-sectional view showing a basic configuration of the liquid crystal display element shown in FIG. FIG. 3 is a schematic view of the counter substrate and the array substrate applicable to the liquid crystal display device shown in FIGS. FIG. 4 is a schematic view of the counter substrate and the array substrate applicable to the liquid crystal display device shown in FIGS.

Explanation of symbols

  LPN ... liquid crystal display panel, AR ... array substrate, CT ... counter substrate, LQ ... liquid crystal layer, PT ... transmission part, PR ... reflection part, POL1 ... first polarization control element, POL2 ... second polarization control element, 21 ... reflection Electrode, 31 ... Transparent electrode, 22 ... First convex structure, 32 ... Second convex structure, 61 ... First polarizing plate, 62 ... First retardation plate, 71 ... Second polarizing plate, 72 ... Second place Phase difference plate, BL: Backlight unit, PX: Pixel.

Claims (11)

A first substrate in which a plurality of pixels each including a reflective electrode and a transmissive electrode are arranged in a matrix on a first insulating substrate;
On the second insulating substrate, a counter electrode provided in common corresponding to the plurality of pixels, a first convex structure disposed corresponding to the transmissive electrode, and disposed corresponding to the reflective electrode A second convex structure that is formed on the same plane as the first convex structure and has the same height, and is disposed opposite to the first substrate,
A liquid crystal display device comprising: a liquid crystal layer disposed between the first substrate and the second substrate.   The liquid crystal display device according to claim 1, wherein the first convex structure and the second convex structure are made of the same material.   The liquid crystal display device according to claim 2, wherein the first convex structure and the second convex structure are made of a photosensitive acrylic resin.   4. The liquid crystal display device according to claim 1, wherein the second convex structure has the same size as the opposing reflective electrode and is formed to have a uniform thickness. 5.   4. The liquid crystal display device according to claim 1, wherein the second convex structure has the same size as the opposing reflective electrode and has an uneven shape. 5.   The difference between the first voltage applied between the transmissive electrode and the counter electrode and the second voltage applied between the reflective electrode and the counter electrode at the same luminance is within 100 mV. The liquid crystal display device according to any one of 5. A first polarization control element provided on an outer surface opposite to a surface holding the liquid crystal layer of the first substrate;
7. The liquid crystal display device according to claim 1, further comprising: a second polarization control element provided on an outer surface opposite to a surface holding the liquid crystal layer of the second substrate. A first alignment film provided on a surface of the first substrate that holds the liquid crystal layer, and having a property of aligning liquid crystal molecules of the liquid crystal layer substantially perpendicularly to the first substrate;
And a second alignment film provided on a surface of the second substrate for holding the liquid crystal layer and having alignment characteristics for aligning liquid crystal molecules of the liquid crystal layer substantially perpendicularly to the second substrate. 8. A liquid crystal display device according to any one of 1 to 7. A plurality of pixels including a reflective electrode and a transmissive electrode are arranged in a matrix on a first insulating substrate, and a plurality of pixels are arranged in common on the second insulating substrate corresponding to the plurality of pixels. A second substrate provided with a counter electrode,
A first convex structure corresponding to the transmissive electrode and a second convex structure corresponding to the reflective electrode are simultaneously formed on the counter electrode of the second substrate,
Bonding the first substrate and the second substrate,
A method for manufacturing a liquid crystal display device, wherein a liquid crystal layer containing liquid crystal molecules is formed between the first substrate and the second substrate. When forming the first convex structure and the second convex structure,
Forming a photosensitive resist film on the counter electrode,
The method for manufacturing a liquid crystal display device according to claim 9, wherein the photosensitive resist is exposed and developed using a mask for forming the first convex structure and the second convex structure.   The method for manufacturing a liquid crystal display device according to claim 10, wherein the photosensitive resist is made of a material containing an acrylic resin.

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