JP2009162928A - Liquid crystal display device and method for manufacturing same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid crystal display device making a high-performance display. <P>SOLUTION: The liquid crystal display device 100 comprises a first substrate 200 including a reflecting layer 220r provided in a reflecting region R, and a first alignment layer 230; a second substrate 250 including a color filter layer 262 provided in both a transmission region T and the reflecting region R, and a second alignment layer 280; a liquid crystal layer 300 provided between the first alignment layer 230 and the second alignment layer 280; a first alignment maintaining layer 410 provided between the first alignment layer 230 and the liquid crystal layer 300; and a second alignment maintaining layer 420 provided between the second alignment layer 280 and the liquid crystal layer 300. A region 262r, corresponding to the reflecting region, of the color filter layer 262 includes a plurality of apertures 263. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a liquid crystal display device and a method for manufacturing the liquid crystal display device.

  The liquid crystal display device has advantages such as light weight, thinness, and low power consumption. For this reason, liquid crystal display devices are used in display units such as televisions, computers, and portable terminals. Unlike a self-luminous panel such as a cathode ray tube (CRT) or a plasma display panel (PDP), the liquid crystal panel of the liquid crystal display device itself does not emit light. For this reason, in the transmissive liquid crystal display device, a backlight is disposed on the back surface of the liquid crystal panel, and display is performed by light emitted from the backlight and passing through the liquid crystal panel. In the reflective liquid crystal display device, display is performed by light incident from the front and reflected by the liquid crystal panel.

  On the other hand, in the transflective liquid crystal display device, a transmission mode in which display is performed by light emitted from the backlight and passed through the liquid crystal panel, and a reflection mode in which display is performed by light incident from the front and reflected by the liquid crystal panel Is displayed. The transflective liquid crystal display device reduces power consumption by displaying in the reflection mode mainly in an environment where the light incident from the outside is strong, and in an environment where the light incident from the outside is weak. Displaying mainly in the transmission mode suppresses a decrease in luminance and contrast ratio. Such a transflective liquid crystal display device is suitably used for mobile devices including mobile phones, vehicle instrument panels, and the like.

  In recent years, a polymer alignment technology (hereinafter referred to as “PSA technology”) has been developed as a technology for controlling the pretilt direction of liquid crystal molecules. For example, by applying PSA technology to a VA mode liquid crystal display device that achieves a high contrast ratio, the pretilt direction of liquid crystal molecules is defined in a direction slightly tilted with respect to the normal direction of the main surface of the alignment film, The stability of the alignment of liquid crystal molecules and the response speed can be improved.

  Hereinafter, a general PSA technique will be described with reference to FIG. As shown in FIG. 5A, an active matrix substrate 600 having a pixel electrode 610 and an alignment film 620 on a transparent substrate 602, and a color having a color filter layer 660, a counter electrode 670, and an alignment film 680 on a transparent substrate 652. A liquid crystal layer 700 is formed between the filter substrate 650 and the filter substrate 650. In the liquid crystal layer 700, a small amount of a photopolymerizable composition (eg, photopolymerizable monomer) 704 is mixed in addition to the liquid crystal molecules 702. Thereafter, when a predetermined voltage is applied between the pixel electrode 610 and the counter electrode 670, the liquid crystal molecules 702 are aligned in a predetermined direction, and ultraviolet light is irradiated in such a voltage application state.

  The photopolymerizable composition 704 in the liquid crystal layer 700 is polymerized by irradiation with ultraviolet light. As a result, as shown in FIG. 5B, a polymer structure (polymer) 710 is formed between the alignment film 620 and the liquid crystal layer 700, and a polymer is formed between the alignment film 680 and the liquid crystal layer 700. A structure 720 is formed. By such polymer structures 710 and 720, the orientation state of the liquid crystal molecules 702 when the polymer structures 710 and 720 are generated is maintained (memory) even after the voltage is removed (the state where no voltage is applied). Is done. In this specification, such a polymer structure is also referred to as an orientation maintaining layer. Moreover, the process of irradiating ultraviolet light to form a polymer structure (alignment maintaining layer) is also referred to as a PSA process. By the polymer structures 710 and 720, the alignment direction of the liquid crystal molecules 702 is maintained (stored), and the pretilt direction is defined. The pretilt direction is represented by a pretilt angle and a pretilt azimuth. The pretilt angle is an angle formed between the main surface of the alignment film and the major axis of the liquid crystal molecules aligned in the vicinity of the alignment film when no voltage is applied, and the pretilt direction is the major axis of such a liquid crystal molecule. This is the azimuth angle component projected on the main surface of.

  As described above, the PSA technique has an advantage that the pretilt azimuth and pretilt angle of the liquid crystal molecules can be adjusted by controlling the electric field formed in the liquid crystal layer. In addition, the PSA technology can define the pretilt azimuth and pretilt angle of liquid crystal molecules without the need for rubbing, so it forms a vertically aligned liquid crystal layer that is difficult to control the pretilt direction by rubbing. Suitable for doing.

  It is known that such a PSA technique is applied to the above-described transflective liquid crystal display device (see, for example, Patent Document 1). FIG. 6 is a schematic cross-sectional view of a pixel in the liquid crystal display device 800 disclosed in Patent Document 1. The liquid crystal display device 800 is a transmissive / reflective liquid crystal display device, and the pixel has a transmissive region T and a reflective region R.

  In the liquid crystal display device 800, the color filter layer 960 is provided in both the transmissive region T and the reflective region R. In FIG. 6, in the color filter layer 960, a region corresponding to the transmission region T is indicated as a color filter region 960t, and a region corresponding to the reflection region R is indicated as a color filter region 960r. The thickness d1 of the color filter region 960t is about twice the thickness d2 of the color filter region 960r. In FIG. 6, a region corresponding to the transmission region T in the liquid crystal layer 990 is indicated as a liquid crystal region 990t, and a region corresponding to the reflection region R is indicated as a liquid crystal region 990r. In the liquid crystal display device 800, the alignment maintaining layer (not shown) is provided in the reflective region R but not in the transmissive region T.

  A PSA process is performed when the liquid crystal display device 800 is manufactured. In this PSA process, ultraviolet light is irradiated from the color filter substrate 950 side without applying a voltage between the pixel electrode 910 and the counter electrode 970. Since the color filter region 960r is relatively thin, the ultraviolet light reaches the liquid crystal region 990r and an alignment maintaining layer (ultraviolet cured product) is formed in the reflection region R, whereas the color filter region 960t is relatively thick. The ultraviolet light does not reach the liquid crystal region 990t, and the alignment maintaining layer is not formed in the transmission region T.

  In the liquid crystal display device 800, when a voltage is applied, the alignment maintaining layer maintains the liquid crystal molecules in the liquid crystal region 990r, so that the liquid crystal molecules in the liquid crystal region 990r are less inclined than the liquid crystal molecules in the liquid crystal region 990t. The refractive index anisotropy of the region is smaller than that of the liquid crystal region 990t. Thereby, the retardation of the liquid crystal region 990r is matched with the liquid crystal region 990t.

In general, light that contributes to display in the reflective region passes through the color filter region twice, whereas light that contributes to display in the transmissive region passes through the color filter region once. It is difficult to optimize the color purity of both areas T. However, in the liquid crystal display device 800, since the color filter region 960r is thinner than the color filter region 960t, even if the color filter regions 960t and 960r are formed of the same material, the color purity of both the reflective region R and the transmissive region T is improved. Can be optimized.
JP 2005-338472 A

  In the liquid crystal display device 800, it is difficult to manufacture the color filter regions 960t and 960r having different thicknesses as designed, and the display characteristics vary depending on the thickness variation of the color filter regions 960t and 960r. In addition, since the alignment maintaining layer is formed in the reflective region R while the alignment maintaining layer is not formed in the transmissive region T, the response characteristics of the liquid crystal molecules in the liquid crystal region 990t are different from those in the liquid crystal region 990r. Since the roughness occurs due to such a difference in response characteristics, the liquid crystal display device 800 cannot perform high-quality display. In practice, it is difficult to selectively form the alignment maintaining layer by changing the transmittance of ultraviolet light by changing the thicknesses of the color filter regions 960t and 960r.

  The present invention has been made in view of the above problems, and an object thereof is to provide a liquid crystal display device that performs high-quality display and a method for manufacturing the same.

  The liquid crystal display device according to the present invention is a liquid crystal display device having a plurality of pixels each including a transmission region and a reflection region, and includes a first substrate including a reflection layer provided in the reflection region and a first alignment film. And a second substrate including a color filter layer provided in both the transmission region and the reflection region, and a second alignment film, and provided between the first alignment film and the second alignment film. A liquid crystal layer, a first alignment maintaining layer provided between the first alignment film and the liquid crystal layer, and a second alignment maintaining layer provided between the second alignment film and the liquid crystal layer. A plurality of openings are provided in a region corresponding to the reflective region in the color filter layer.

  In one embodiment, a thickness of a region corresponding to the reflective region in the color filter layer is substantially equal to a thickness of a region corresponding to the transmissive region.

  In one embodiment, each of the first alignment film and the second alignment film is provided in both the transmissive region and the reflective region, and a region of the first alignment film corresponding to the transmissive region is provided. The thickness is substantially equal to the thickness of the region corresponding to the reflective region, and the thickness of the region corresponding to the transmissive region in the second alignment film is substantially equal to the thickness of the region corresponding to the reflective region.

  In one embodiment, the plurality of openings are distributed over the entire region corresponding to the reflective region of the color filter layer.

  In one embodiment, a region corresponding to the reflection region in the color filter layer has a mesh shape.

  In one embodiment, a region corresponding to the reflective region in the color filter layer has a checker pattern shape.

  In one embodiment, the plurality of openings are randomly arranged in a region corresponding to the reflective region in the color filter layer.

  In one embodiment, the distance between two adjacent openings in each of the plurality of openings is 50 μm or less.

  A method for manufacturing a liquid crystal display device according to the present invention is a method for manufacturing a liquid crystal display device having a plurality of pixels each including a transmissive region and a reflective region, wherein the reflective region is provided in each of the reflective regions of the plurality of pixels. Forming an active matrix substrate having a layer and a first alignment film, and forming a color filter substrate having a color filter layer corresponding to both the transmission region and the reflection region, and a second alignment film A step of forming a plurality of openings in a region corresponding to the reflective region of the color filter layer; and the active matrix substrate and the color so that the first alignment film and the second alignment film face each other. A filter substrate is disposed, and a liquid crystal material mixed with a photopolymerizable composition is provided between the first alignment film and the second alignment film to provide a liquid crystal panel. A step of forming an alignment maintaining layer corresponding to the transmission region by irradiating the liquid crystal panel with ultraviolet light from the active matrix substrate side, and an ultraviolet ray from the color filter substrate side to the liquid crystal panel. And irradiating light to form an alignment maintaining layer corresponding to the reflective region.

  ADVANTAGE OF THE INVENTION According to this invention, the liquid crystal display device which performs a high quality display, and its manufacturing method can be provided.

  Hereinafter, embodiments of a liquid crystal display device and a method for manufacturing the same according to the present invention will be described with reference to the drawings. In addition, this invention is not limited to the following embodiment.

(Embodiment 1)
First, the configuration of the liquid crystal display device 100 according to the first embodiment of the present invention will be described with reference to FIG. The liquid crystal display device 100 is a transflective type. The liquid crystal display device 100 is a CPA (Continuous Pinwheel Alignment) mode liquid crystal display device that realizes good viewing angle characteristics.

  FIG. 1A is a schematic cross-sectional view of the liquid crystal display device 100 of the present embodiment. The liquid crystal display device 100 is provided with a plurality of pixels in a matrix of a plurality of rows and columns. FIG. 1A shows one pixel, and the pixels are a transmissive region T and a reflective region R. have. The liquid crystal display device 100 includes a liquid crystal panel 150 and a backlight 500. The liquid crystal panel 150 includes an active matrix substrate (first substrate) 200, a color filter substrate (second substrate) 250, and a liquid crystal layer 300 provided between the active matrix substrate 200 and the color filter substrate 250. ing. Although not shown, typically, a phase difference plate and a polarizing plate are provided outside the active matrix substrate 200 and the color filter substrate 250.

  The active matrix substrate 200 includes a transparent substrate 202, a pixel electrode 210 provided on the transparent substrate 202, and a first alignment film 230 that covers the pixel electrode 210. The transparent substrate 202 is, for example, a glass substrate or a plastic substrate. The pixel electrode 210 has a plurality of sub-pixel electrodes 210a. Note that here, the pixel electrode 210 having three sub-pixel electrodes 210a is illustrated, but the number of sub-pixel electrodes 210a belonging to one pixel electrode 210 is not limited to this.

  In the liquid crystal display device 100, a part of the plurality of subpixel electrodes 210a is formed of a transparent conductive material (for example, ITO (Indium Tin Oxide)). In the following description, the subpixel electrode 210a is referred to as a transparent electrode 220t. The remaining sub-pixel electrodes 210a are made of a conductive material (for example, a metal such as aluminum) having a high light reflectance, and this functions as the reflective layer 220r. In the following description, this subpixel electrode 210a is referred to as a reflective electrode 220r. The reflective region R is defined by the reflective electrode 220r. Note that a part of the pixel electrode 210 may not have a reflection function, a transparent electrode is provided also in a region corresponding to the reflection region R, and a reflective member having no conductivity is provided on the transparent electrode. The reflective layer 220r may be used.

  Although not shown here, the active matrix substrate 200 further includes a switching element (for example, a thin film transistor (TFT)) electrically connected to the pixel electrode 210, and a scanning wiring that supplies a scanning signal to the TFT. The pixel electrode 210 is provided on an interlayer insulating film (not shown) covering these wiring groups and TFTs. Is formed.

  The color filter substrate 250 includes a transparent substrate 252, a colored layer 260, a counter electrode 270, and a second alignment film 280. The transparent substrate 252 is, for example, a glass substrate or a plastic substrate. The coloring layer 260 includes a color filter layer 262 and a light shielding layer 264. Although FIG. 1A shows one color filter layer 262, in reality, three color filter layers of red, green, and blue are provided as the color filter layer 262. While the pixel electrode 210 is disposed in each of a plurality of pixels, the counter electrode 270 is typically formed as one transparent conductive film that faces all the pixel electrodes 210.

  In the liquid crystal display device 100, the first alignment sustaining layer 410 is provided between the liquid crystal layer 300 and the first alignment film 230, and the second alignment maintaining layer 420 is provided between the liquid crystal layer 300 and the second alignment film 280. It has been. The first and second alignment maintaining layers 410 and 420 are formed by polymerization of a photopolymerizable composition. In FIG. 1A, the first and second alignment maintaining layers 410 and 420 are shown as films covering the entire surfaces of the first and second alignment films 230 and 280, but the first and second alignment maintaining layers are shown. The layers 410 and 420 may not be provided so as to cover the entire surfaces of the first and second alignment films 230 and 280 but may be provided in an island shape.

  The liquid crystal layer 300 is a vertical alignment type and includes liquid crystal molecules 302 having negative dielectric anisotropy. The alignment direction of the liquid crystal molecules 302 of the liquid crystal layer 300 is defined not only by the first and second alignment films 230 and 280 but also by the first and second alignment maintaining layers 410 and 420. In the liquid crystal layer 300, a liquid crystal domain is formed for each sub-pixel electrode 210a.

  The color filter substrate 250 is provided with a convex portion 290. The convex portion 290 is disposed in a region corresponding to the center of the liquid crystal domain (that is, a region corresponding to the center of each sub-pixel electrode 210a). The convex part 290 is formed from a transparent dielectric material (for example, resin). Note that the protrusions 290 are not necessarily provided, and some or all of the plurality of protrusions 290 provided in each pixel may be omitted. Further, instead of the convex portion 290, another alignment regulating structure (for example, an opening formed in the counter electrode 270) may be provided.

  In FIG. 1A, in the color filter layer 262, a region corresponding to the transmission region T is indicated as a color filter region 262t, and a region corresponding to the reflection region R is indicated as a color filter region 262r. Similarly, in the liquid crystal layer 300, a region corresponding to the transmissive region T is indicated as a liquid crystal region 300t, and a region corresponding to the reflective region R is indicated as a liquid crystal region 300r. Of the first and second alignment films 230 and 280, regions corresponding to the transmission region T are indicated as alignment regions 230t and 280t, and regions corresponding to the reflection region R are indicated as alignment regions 230r and 280r. Of the first and second alignment sustaining layers 410 and 420, regions corresponding to the transmission region T are indicated as alignment maintaining regions 410t and 420t, and regions corresponding to the reflective region R are indicated as alignment maintaining regions 410r and 420r. Yes.

  In the liquid crystal display device 100 of the present embodiment, a plurality of openings 263 are provided in the color filter region 262r. For this reason, the light transmittance of the color filter region 262r is different from the light transmittance of the color filter region 262t. For example, for the color filter region 262t, the light transmittance of the corresponding wavelength is about 80%, and the light transmittance of other wavelengths is about 0%. For the color filter region 262r, the light transmittance of the corresponding wavelength is about 90%, and the light transmittance of other wavelengths is about 50%.

  In the liquid crystal display device 100, the thickness of the liquid crystal region 300t is substantially equal to the thickness of the liquid crystal region 300r. The thickness of the liquid crystal layer 300 is, for example, 3.5 μm. The first alignment film 230 and the second alignment film 280 are each provided over the entire display area. In the first alignment film 230, the thickness of the alignment region 230t is substantially equal to the thickness of the alignment region 230r. Similarly, in the second alignment film 280, the thickness of the alignment region 280t is substantially equal to the thickness of the alignment region 280r. For example, the thickness of the first alignment film 230 and the second alignment film 280 is 600 mm.

  FIG. 1B shows a schematic plan view of the liquid crystal display device 100. The pixel electrode 210 is disposed at a position surrounded by two adjacent scanning lines G and two adjacent signal lines S. The sub-pixel electrode 210a has a substantially rectangular shape with arcuate corners. The sub-pixel electrode 210a belonging to one pixel, that is, the two transparent electrodes 220t and the one reflective electrode 220r are substantially rectangular with arcuate corners. The transparent electrode 220t and the reflective electrode 220r are electrically connected to each other. Note that the length in the x direction of the transparent electrode 220t is substantially equal to the length in the y direction. The length of the reflective electrode 220r in the x direction is substantially equal to the length of the transparent electrode 220t in the x direction, but the length of the reflective electrode 220r in the y direction is approximately half of the length of the transparent electrode 220t in the y direction. Therefore, the ratio of the sum of the areas of the transparent electrodes 220t and the area of the reflective electrodes 220r is approximately 4: 1. Here, the symmetry of the reflective electrode 220r is not as high as that of the transparent electrode 220t, but since the size of the reflective electrode 220r is relatively small, the influence on the display characteristics is small.

  FIG. 1C shows the alignment state of the liquid crystal molecules 302 when a predetermined voltage (a voltage equal to or higher than the threshold voltage) is applied between the pixel electrode 210 and the counter electrode 270. 1A is a cross-sectional view taken along the line 1A-1A ′ of FIG.

  When a predetermined voltage is applied between the pixel electrode 210 and the counter electrode 270 shown in FIG. 1A, a liquid crystal domain is formed on each sub-pixel electrode 210a as shown in FIG. 1C. The The liquid crystal molecules 302 in the liquid crystal domain are aligned in a radial gradient. A liquid crystal domain is formed for each sub-pixel electrode 210a. The sub-pixel electrode 210a has an outer edge close to an independent island, and the alignment regulating force of the oblique electric field generated at the edge of the sub-pixel electrode 210a is liquid crystal. This is because it acts on the molecule 302. The electric field generated at the edge portion of the sub-pixel electrode 210a is inclined toward the center of the sub-pixel electrode 210a, and acts to incline the liquid crystal molecules 302 radially. Further, the radial inclined orientation is stabilized by the convex portions 290 of the color filter substrate 250.

  Here, the alignment direction of the liquid crystal molecules and the PSA process will be described. By performing the PSA process, the first and second alignment maintaining layers 410 and 420 shown in FIG. 1A are formed. Therefore, the first and second alignment sustaining layers 410 and 420 are not formed before the PSA process. If no voltage is applied between the pixel electrode 210 and the counter electrode 270 before the PSA process, the liquid crystal molecules 302 in the liquid crystal layer 300 are substantially perpendicular to the surfaces of the first and second alignment films 230 and 280. Aligned and the pretilt angle of the liquid crystal molecules is approximately 90 °. The first and second alignment films 230 and 280 are also called vertical alignment films. When the first and second alignment sustaining layers 410 and 420 are formed by performing the PSA process, the pretilt angle of the liquid crystal molecules 302 becomes lower than 90 ° by the first and second alignment maintaining layers 410 and 420. Note that the pretilt angle may decrease with time.

  The PSA process is performed as follows. A photopolymerizable composition (a photopolymerizable monomer or oligomer) is preliminarily mixed in the liquid crystal material constituting the liquid crystal layer 300, and this liquid crystal material is applied between the active matrix substrate 200 and the color filter substrate 250 to obtain liquid crystal. Panel 150 is produced. When a voltage is applied between the pixel electrode 210 and the counter electrode 270, the liquid crystal molecules 302 are centered on the convex portion 290 when viewed from the normal direction of the main surface of the first alignment film 230, as shown in FIG. Oriented so as to be inclined radially. In such a voltage application state, when the liquid crystal panel 150 is irradiated with ultraviolet light, the photopolymerizable composition is polymerized, and the first and second layers are formed between the liquid crystal layer 300 and the first and second alignment films 230 and 280. Alignment maintaining layers 410 and 420 are formed. The first and second alignment sustaining layers 410 and 420 have an alignment regulating force for aligning the liquid crystal molecules 302 in the same direction as when a voltage is applied even when no voltage is applied. The first and second alignment maintaining layers 410 , 420 in the vicinity of the liquid crystal molecules 302 are pretilted in the same direction as the tilt direction at the time of voltage application. That is, the pretilt azimuth of the liquid crystal molecules 302 when no voltage is applied is defined by the first and second alignment maintaining layers 410 and 420 so as to be aligned with the radial tilt alignment during voltage application.

  As described above, the pretilt direction of the liquid crystal molecules 302 in the vicinity of the active matrix substrate 200 in the liquid crystal layer 300 is defined by the first alignment film 230 and the first alignment maintaining layer 410, and the color filter substrate 250 in the liquid crystal layer 300. The pretilt direction of the liquid crystal molecules 302 in the vicinity of is defined by the second alignment film 280 and the second alignment sustaining layer 420. The pretilt azimuth of the liquid crystal molecules 302 of the liquid crystal layer 300 is also oriented in all directions from 0 ° to 360 ° around the convex portion 290. By defining the pretilt azimuth of the liquid crystal molecules in this way, the stability of the alignment of the liquid crystal molecules and the response characteristics when a voltage is applied are improved. In addition, when the pretilt direction is controlled so that the inclination of the liquid crystal molecules with respect to the normal direction of the main surfaces of the first and second alignment films 230 and 280 in the state where no voltage is applied is about 2 to 4 °, the contrast ratio and the responsiveness. And the balance can be improved. In addition, by controlling the pretilt direction in this way, the response can be accelerated and the alignment disorder due to finger pressing or the like can be suppressed. Further, if the pixel structure is simplified, both the luminance and the contrast ratio can be improved.

  FIG. 1D shows a schematic plan view of the colored layer 260. The color filter layer 262 is substantially rectangular, and as shown in FIG. 1D, three color filter layers 262 of red (R), green (G), and blue (B) are arranged in a line. The light shielding layer 264 is disposed so as to surround the color filter layer 262. For example, the size of the color filter layer 262 is 50 × 100 μm. Further, the light shielding layer 264 is disposed so as to overlap the pixel electrode 210 by, for example, about 5 μm.

  A plurality of openings 263 are provided in the color filter region 262r of the color filter layer 262. Note that the opening 263 may be filled with a patternable acrylic resin material as a planarizing material. The plurality of openings 263 are regularly arranged over the entire surface of the color filter region 262r. In the liquid crystal display device 100 of the present embodiment, the openings 263 each have a square shape with a length of 5 × 5 μm, and the color filter region 262r provided with the plurality of openings 263 has a checker pattern shape. The distance between two adjacent openings is approximately equal to the length of the opening 263. The ratio of the area of all the openings 263 to the entire color filter region 262r is almost half.

  As understood from the above description with reference to Patent Document 1, when irradiating ultraviolet light from the color filter substrate side in the PSA process, if the color filter region is not sufficiently thin, the ultraviolet light is absorbed by the color filter region. Therefore, the alignment maintaining layer cannot be formed on the liquid crystal layer corresponding to the reflective region. Even if ultraviolet light is irradiated from the active matrix substrate side in the PSA process, the ultraviolet light is reflected by the reflective electrode, and the alignment maintaining layer cannot be formed in the liquid crystal layer corresponding to the reflective region.

  However, in the liquid crystal display device 100 of the present embodiment, the plurality of openings 263 are provided in the color filter region 262r, so that the ultraviolet light irradiated from the color filter substrate 250 side reaches the liquid crystal region 300r, and the liquid crystal region Alignment maintaining regions 410r and 420r are formed between 300r and the first and second alignment films 230r and 280r. Therefore, by separately irradiating ultraviolet light from the active matrix substrate 200 side, alignment maintaining regions 410t and 420t are formed between the liquid crystal region 300t and the first and second alignment films 230 and 280, thereby transmitting the transmission region T. The alignment maintaining layers 410 and 420 can be formed over both the reflective region R and the reflective region R.

  Hereinafter, a method for manufacturing the liquid crystal display device 100 of the present embodiment will be described with reference to FIG.

  As shown in FIG. 2A, an active matrix substrate 200 provided with a pixel electrode 210 and a first alignment film 230 is formed on a transparent substrate 202. Although not shown in FIG. 2A, a TFT, a signal wiring, and the like are provided between the transparent substrate 202 and the pixel electrode 210.

  As shown in FIG. 2B, a color filter substrate 250 provided with a colored layer 260, a counter electrode 270, and a second alignment film 280 is formed on a transparent substrate 252. The color filter layer 262 in the coloring layer 260 includes color filter regions 262t and 262r, and a plurality of openings 263 are formed in the color filter region 262r. Note that the opening 263 is formed by patterning or the like by photolithography.

  As shown in FIG. 2C, the active matrix substrate 200 and the color filter substrate 250 are arranged so that the first alignment film 230 and the second alignment film 280 face each other. Thereafter, the liquid crystal material 302 mixed with the photopolymerizable monomer 304 is applied between the first alignment film 230 and the second alignment film 280. As the photopolymerizable monomer 304, for example, a diacrylate or dimethacrylate monomer having a liquid crystal skeleton is used. The photopolymerizable monomer 304 is added at a concentration of 0.3 wt% with respect to the liquid crystal material 302. In this way, the liquid crystal panel 150 is manufactured.

Thereafter, a PSA process for irradiating the liquid crystal panel 150 with ultraviolet light is performed. Here, for the PSA process, ultraviolet light using a light source having a main wavelength of 365 nm (i-line) is irradiated from each of the active matrix substrate 200 side and the color filter substrate 250 side of the liquid crystal panel 150. In each irradiation, the intensity of the ultraviolet light source is about 20 mW / cm ² , the irradiation time is about 500 seconds, and an AC voltage of about 10 V is applied during the irradiation. Note that the maximum voltage applied in the display of the liquid crystal display device 100 is 5V.

  First, as shown in FIG. 2D, the liquid crystal panel 150 is irradiated with ultraviolet light from the active matrix substrate 200 side. Since the transparent electrode 220t transmits not only visible light but also ultraviolet light, the ultraviolet light reaches the liquid crystal region 300t, and the alignment maintaining regions 410t and 420t are formed. The alignment maintaining regions 410t and 420t are formed by polymerization of a photopolymerizable monomer. On the other hand, since the reflective electrode 220r reflects not only visible light but also ultraviolet light, the ultraviolet light does not reach the liquid crystal region 300r, and the alignment maintaining regions 410r and 420r are not formed.

  Next, as shown in FIG. 2E, the liquid crystal panel 150 is irradiated with ultraviolet light from the color filter substrate 250 side. Since the color filter region 262t of the color filter layer 262 absorbs ultraviolet light, the ultraviolet light does not reach the liquid crystal region 300t. On the other hand, an opening 263 is provided in the color filter region 262r of the color filter layer 262, and the ultraviolet light passes through the opening 263 and reaches the liquid crystal region 300r, thereby forming alignment maintaining regions 410r and 420r. Similarly, the alignment maintaining regions 410r and 420r are formed by polymerization of the photopolymerizable composition.

  As described above, the alignment is maintained over both the transmissive region T and the reflective region R from the photopolymerizable composition 304 mixed in the liquid crystal material applied between the first alignment film 230 and the second alignment film 280. Layers 410, 420 are formed. Further, the photopolymerizable composition decreases from the liquid crystal layer 300, and the ratio of the liquid crystal material 302 that is the main component of the liquid crystal layer 300 increases. If necessary, after the alignment maintaining layers 410 and 420 are formed, the photopolymerizable composition in the liquid crystal layer 300 is further polymerized so that the photopolymerizable composition in the liquid crystal layer 300 is sufficiently reduced. In addition, ultraviolet light may be separately irradiated. Thereafter, the backlight 500 is arranged at a position facing the active matrix substrate 200 of the liquid crystal panel 150. The liquid crystal display device 100 is manufactured as described above.

  By simply irradiating ultraviolet light from the active matrix substrate 200 side, the ultraviolet light is reflected by the reflective electrode 220r, so the ultraviolet light does not reach the liquid crystal region 300r, and the alignment maintaining regions 410r and 420r are not formed. However, since the opening 263 is provided in the color filter region 262r of the color filter layer 262, when the ultraviolet light is irradiated from the color filter substrate 250 side, the ultraviolet light reaches the liquid crystal region 300r, and the alignment maintaining region 410r, 420r is formed. Accordingly, the pretilt azimuth of the liquid crystal molecules can be defined not only in the liquid crystal region 300t but also in the liquid crystal region 300r, and the response characteristics of the liquid crystal regions 300t and 300r can be improved and the occurrence of flicker can be suppressed.

  In general, light that contributes to display in the reflective region passes through the color filter region twice, whereas light that contributes to display in the transmissive region passes through the color filter region once. It is difficult to optimize the color purity of both. However, in the liquid crystal display device 100, the color filter region 262r is provided with the opening 263, which suppresses a decrease in luminance of the reflective region R and easily optimizes the color purity of the transmissive region T and the reflective region R. be able to.

  In the above description, the ultraviolet light is irradiated from the color filter substrate 250 side after the ultraviolet light is irradiated from the active matrix substrate 200 side, but the present invention is not limited to this. After the ultraviolet light is irradiated from the color filter substrate 250 side, the ultraviolet light may be irradiated from the active matrix substrate 200 side.

  In the above description, the irradiation condition when irradiating from the active matrix substrate 200 side is the same as the irradiation condition when irradiating from the color filter substrate 250 side, but the present invention is not limited to this. The two irradiation conditions may be different. For example, when the size of the opening 263 and the ratio of the area of the opening 263 occupying the entire color filter region 262r are small, the irradiation amount when irradiating from the color filter substrate 250 side is irradiated from the active matrix substrate 200 side. It may be larger than the amount of irradiation.

  In the above description, as shown in FIG. 1D, the opening 263 has a substantially rectangular shape, and the color filter region 262r has a checker pattern shape. However, the present invention is not limited to this. .

  As shown in FIG. 3, the opening 263 may be substantially circular. In this case, the size of the opening 263 is, for example, 5 μm to 20 μm, and preferably 10 μm. Further, the sizes of the openings 263 need not be equal. In addition, the openings 263 are basically randomly arranged, but the distance between two adjacent openings 263 is at least 50 μm or less in order to prevent the alignment direction of the liquid crystal molecules from becoming non-uniform in the reflection region. Thus, the opening 263 is arranged. For example, when the width of the pixel in the row direction is 60 μm, two or more patterns can be formed in the row direction if the distance between two adjacent openings 263 is 15 μm or less.

  The ratio of the area of the opening 263 to the entire color filter region 262r is 10% to 50%, and the distribution density of the openings 263 is substantially uniform over the entire color filter region 262r. The degree of distribution can be determined by the roughness of the display in the halftone.

  Alternatively, as shown in FIG. 4, the color filter region 262r of the color filter layer 262 may have a mesh structure in which the size of the opening 263 and the distance between two adjacent openings 263 are different from each other. Considering the resolution of photolithography, for example, the size of the opening 263 is 1 μm or more, and the distance between two adjacent openings 263 is 1 μm or more.

  In the above description, the sub-pixel electrode has a substantially rectangular shape with arc-shaped corners, but the present invention is not limited to this. Other shapes may be used. However, the shape of the subpixel electrode is preferably a shape having high rotational symmetry (substantially square, substantially rectangular, substantially circular, etc.).

  In the above description, the liquid crystal layer 300 is a vertical alignment type, but the present invention is not limited to this. The liquid crystal layer 300 may be other alignment types.

  In the above description, the liquid crystal display device is in the CPA mode, but the present invention is not limited to this. The liquid crystal display device may be in another mode. For example, the liquid crystal display device may be in an MVA (Multidomain Electrical Alignment) mode.

  In the above description, the alignment film is a vertical alignment film that vertically aligns liquid crystal molecules when no voltage is applied, and the pretilt azimuth is defined by the alignment maintaining layer, but the present invention is not limited to this. Before forming the alignment maintaining layer, the pretilt azimuth may be defined only by the alignment film, and such an alignment film may be formed by photo-alignment treatment.

  In the above description, the thickness (cell gap) of the liquid crystal region 300t is substantially equal to that of the liquid crystal region 300r, but the present invention is not limited to this. In order to reduce the difference in optical path length between light used for transmission mode display (passes the liquid crystal layer 300 only once) and light used for reflection mode display (passes the liquid crystal layer 300 twice), The thickness of the liquid crystal region 300r may be smaller than the thickness of the liquid crystal region 300t. For example, the thickness of the liquid crystal region 300r may be half the thickness of the liquid crystal region 300r. In order to realize such a multi-gap structure, a layer (liquid crystal layer thickness adjusting layer) for adjusting the thickness of the liquid crystal layer 300 in a region corresponding to the reflective region R of the active matrix substrate 200 or the color filter substrate 250. ) May be formed. The liquid crystal layer thickness adjusting layer is formed from, for example, a transparent resin material.

  ADVANTAGE OF THE INVENTION According to this invention, the transflective liquid crystal display device which performs a high quality display can be provided. The liquid crystal display device according to the present invention is suitably used for mobile devices such as cellular phones and vehicle instrument panels.

(A) is a schematic plan view of an embodiment of the liquid crystal display device according to the present invention, (b) is a schematic plan view of the liquid crystal display device of the present embodiment, and (c) is a voltage diagram. It is a typical top view which shows the orientation state of the liquid crystal molecule at the time of application, (d) is a typical top view of a colored layer. (A)-(e) is a schematic diagram for demonstrating the manufacturing method of the liquid crystal display device of this embodiment, respectively. It is a typical top view of the colored layer in the modification of the liquid crystal display device of this embodiment. It is a typical top view of the colored layer in another modification of the liquid crystal display device of this embodiment. (A) is a schematic diagram explaining the irradiation of the ultraviolet light in a general PSA technique, (b) is a schematic diagram which shows the orientation maintenance layer produced | generated by the irradiation of the ultraviolet light. It is typical sectional drawing of the conventional liquid crystal display device.

Explanation of symbols

DESCRIPTION OF SYMBOLS 100 Liquid crystal display device 150 Liquid crystal panel 200 Active matrix substrate 202 Transparent substrate 210 Pixel electrode 210a Subpixel electrode 220t Transparent electrode 220r Reflective electrode 230 1st alignment film 250 Color filter substrate 252 Transparent substrate 260 Colored layer 262 Color filter layer 263 Opening 264 Light shielding layer 270 Counter electrode 280 Second alignment film 290 Convex part 300 Liquid crystal layer 410 First alignment sustaining layer 420 Second alignment sustaining layer 500 Backlight

Claims (9)

A liquid crystal display device having a plurality of pixels each including a transmissive region and a reflective region,
A first substrate including a reflective layer provided in the reflective region and a first alignment film;
A second substrate including a color filter layer provided in both the transmission region and the reflection region, and a second alignment film;
A liquid crystal layer provided between the first alignment film and the second alignment film;
A first alignment sustaining layer provided between the first alignment film and the liquid crystal layer;
A second alignment sustaining layer provided between the second alignment film and the liquid crystal layer,
A liquid crystal display device, wherein a plurality of openings are provided in a region corresponding to the reflective region in the color filter layer.   The liquid crystal display device according to claim 1, wherein a thickness of a region corresponding to the reflective region in the color filter layer is substantially equal to a thickness of a region corresponding to the transmissive region. Each of the first alignment film and the second alignment film is provided in both the transmission region and the reflection region,
The thickness of the region corresponding to the transmissive region in the first alignment film is substantially equal to the thickness of the region corresponding to the reflective region,
3. The liquid crystal display device according to claim 1, wherein a thickness of a region corresponding to the transmission region in the second alignment film is substantially equal to a thickness of a region corresponding to the reflection region.   4. The liquid crystal display device according to claim 1, wherein the plurality of openings are distributed over an entire region of the color filter layer corresponding to the reflection region. 5.   The liquid crystal display device according to claim 4, wherein a region corresponding to the reflective region in the color filter layer has a mesh shape.   The liquid crystal display device according to claim 4, wherein an area corresponding to the reflective area in the color filter layer has a checker pattern shape.   The liquid crystal display device according to claim 4, wherein the plurality of openings are randomly arranged in a region corresponding to the reflection region in the color filter layer.   The liquid crystal display device according to claim 4, wherein a distance between two adjacent openings in each of the plurality of openings is 50 μm or less. A method of manufacturing a liquid crystal display device having a plurality of pixels each including a transmissive region and a reflective region,
Forming an active matrix substrate having a reflective layer provided in the reflective region of each of the plurality of pixels and a first alignment film;
Forming a color filter substrate having a color filter layer corresponding to both the transmissive region and the reflective region and a second alignment film, wherein a plurality of regions in the color filter layer corresponding to the reflective region are formed. Forming an opening of
The active matrix substrate and the color filter substrate are disposed so that the first alignment film and the second alignment film face each other, and a photopolymerizable composition is disposed between the first alignment film and the second alignment film. Providing a mixed liquid crystal material to produce a liquid crystal panel;
Irradiating the liquid crystal panel with ultraviolet light from the active matrix substrate side to form an alignment maintaining layer corresponding to the transmission region;
Irradiating the liquid crystal panel with ultraviolet light from the color filter substrate side to form an alignment maintaining layer corresponding to the reflective region.

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