JP2005128084A - Liquid crystal display device and electronic apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid crystal display device wherein reflection display having a wide visual field angle, high contrast and high image quality can be performed. <P>SOLUTION: In the reflection type liquid crystal display device 100 of a vertical alignment mode, a reflection electrode 31, a common electrode 9 and openings 9a to 9c are provided in a plane region of each dot D1 to D3, the reflection electrode 31 is allowed to have an irregular shape consisting of a plurality of protrusions and recesses 24a... disposed nearly irregularly in the plane region of the dot region, and the protrusions and recesses 24a... are arranged in common at each dot D1 to D3. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a liquid crystal display device and an electronic apparatus.

  As a display device suitable for a display unit of a portable electronic device or the like, a reflection type liquid crystal display device capable of displaying by reflecting external light is known, but a conventional reflection type color liquid crystal display device has a viewing angle. There was a problem of narrow and low contrast. Therefore, a reflection type liquid crystal display device employing a liquid crystal in a vertical alignment mode with a wider viewing angle has been proposed (for example, see Patent Document 1). In the vertical alignment mode, the direction in which the liquid crystal is tilted by the voltage needs to be controlled by some method. However, in Patent Document 1, a reflective electrode and a counter electrode are provided across the liquid crystal layer, and an oblique electric field generated at the end of the reflective electrode. And the orientation control window provided on the counter electrode regulate the direction in which the vertically aligned liquid crystal molecules fall.

By the way, in the reflection type liquid crystal display device, it is general to provide a light scattering means in order to prevent a decrease in display visibility due to regular reflection of external light. For example, Patent Document 1 employs a configuration in which a diffusion layer is provided on the front side of a liquid crystal panel to scatter display light. Patent Document 2 listed below discloses a liquid crystal display device using a scattering reflector having a surface provided with irregularities. The use of a scattering reflector having a surface with irregularities is superior in that a high-contrast display without blurring can be obtained as compared with those using a diffusion layer.
JP 2000-89210 A JP-A-10-123508

  Considering the case where the techniques described in Patent Documents 1 and 2 described above are combined, by applying the scattering reflector described in Patent Document 2 to the liquid crystal display device described in Patent Document 1, the viewing angle is wide and blurred. It is considered that a reflection type liquid crystal display device capable of high-contrast display without any problem is obtained. However, it has been found that when these are combined, a new problem that does not occur in the conventional vertical alignment mode reflective liquid crystal display device occurs. That is, display coloration and rough spotted unevenness occur, and these change depending on the viewing angle direction and the light irradiation direction, resulting in a significant reduction in display quality.

  The present invention has been made in view of the above-described problems of the prior art, and an object thereof is to provide a liquid crystal display device capable of a reflective display with a wide viewing angle, high contrast, and high image quality. It is another object of the present invention to provide an electronic device including a wide viewing angle and high contrast color display unit.

  According to the inventor's research, the deterioration of the display quality in the combination of the vertically aligned liquid crystal and the scattering reflector is that irregularities are irregular in order to prevent optical interference in the scattering reflector. It is derived from being arranged in The principle will be briefly described below with reference to FIGS. In FIG. 8, the octagon forming the outer shape shows the reflective electrode 110, and the octagon disposed at the center of the reflective electrode 110 is an opening 119 provided in the electrode facing the liquid crystal layer. . The reflective electrode 110 constitutes one dot or a part (subdot) of the liquid crystal display device. Reference numeral 51 schematically shows liquid crystal molecules constituting a liquid crystal layer sandwiched between the reflective electrode 110 and the opposite electrode. Further, the reflective electrode 110 is provided with an uneven shape for scattering the reflected light, and the convex portions 124a are irregularly arranged on the reflective electrode 110 as shown in FIG. 8B.

  In FIG. 8A, the liquid crystal molecules 51 are shown in a slightly tilted state when a voltage is applied. The liquid crystal molecules 51 are controlled by the alignment control action between the outer peripheral end of the reflective electrode 110 and the opening 119 disposed in the center of the reflective electrode. Oriented radially in plan view. In an actual liquid crystal display device, the tilt angle of the liquid crystal molecules 51 is different between the vicinity of the center and the outer peripheral portion.

  FIG. 9 shows the voltage reflectivity characteristics of the dots in which the liquid crystal molecules 51 are radially aligned and the concavo-convex shape is given to the reflective electrode 110 as shown in FIG. A plurality of curves indicated by solid lines or broken lines in FIG. 9 indicate the reflectance at different positions (six locations) on the reflective electrode 110, and the reflectance is parallel light incident from the 12 o'clock direction and the polar angle of 30 °. It is the ratio of the reflected light in the front direction (polar angle 0 ° direction) of the liquid crystal display device in the case of the above. Of the curves shown in the figure, two curves shown by solid lines correspond to a position where the reflectance is highest and a position where the reflectance is lowest during gradation display.

  As shown in FIG. 9, the reflectance of the dots having the configuration shown in FIG. 8 varies greatly depending on the position. In particular, when the intermediate voltage V1 is applied to perform gradation display, the maximum value within the same dot is obtained. The reflectance L2 is about three times the minimum reflectance L1. As described above, the reflectance greatly differs within one dot because of the parallel light incident on the liquid crystal display device from the 12 o'clock direction and the polar angle of 30 °, the front direction of the liquid crystal display device (polar angle of 0 ° direction; The light reflected in the direction perpendicular to the paper surface is the light reflected at one point 124b on the convex portion 124a on the reflective electrode 110, and these points 124b are irregularly arranged on the reflective electrode 110. This is also because the alignment states of the liquid crystal molecules 51 at those points are all different.

Since the points 124b on the convex portions 124a that contribute to the reflected light intensity in a specific direction are irregularly arranged on the reflective electrode 110 as described above, the distance between the plurality of reflective electrodes 110 constituting the liquid crystal display device. Therefore, the reflection characteristics are different from each other, and this causes coloring and rough spot-like unevenness when the liquid crystal display device is obliquely viewed. In addition, since the position of the point 124b varies depending on the incident angle of light and the viewing angle of the observer, it is impossible to compensate for the coloring or display unevenness with an optical element or the like. As described above, such coloring and display unevenness do not occur in a liquid crystal display device in a vertical alignment mode that is not aligned and divided, but it is a problem that occurs only when alignment within a dot is performed. is there. This is because in the conventional liquid crystal display device in which the alignment is not divided, the liquid crystal molecules on the reflective electrode are arranged in one direction, so that there is no difference in reflection characteristics depending on the emission position of the reflected light.
The present inventor has repeatedly studied to solve the problems of coloring and display unevenness in the liquid crystal display device of the vertical alignment mode which is divided in the above-described alignment, and has completed the present invention.

A liquid crystal display device according to the present invention includes a display region in which a plurality of dots constituting one display unit are arranged by sandwiching a liquid crystal layer having an initial orientation of vertical alignment between a pair of substrates arranged opposite to each other. A reflective layer and an alignment control structure for controlling an alignment state of the vertically aligned liquid crystal are provided in the planar area of each dot, and the reflective layer is substantially within the planar area of the dot. An uneven shape including a plurality of irregularly arranged uneven portions is provided, and the display region includes a plurality of dots having substantially the same reflection characteristics.
According to the liquid crystal display device of the present embodiment having the above-described configuration, a plurality of dots having substantially the same reflection characteristics are arranged in the display region, and thus display unevenness caused by the difference in reflection characteristics for each dot. Thus, a wide viewing angle and high contrast liquid crystal display device can be provided.

  In the liquid crystal display device of the present invention, it is preferable that a plurality of dot groups constituted by the dots having substantially the same reflection characteristics are included in the display area. According to this configuration, display unevenness due to a difference in reflection characteristics for each dot can be more effectively reduced. In this configuration, it is preferable that the dot group is arranged as irregularly as possible, or dots having substantially the same reflection characteristics are arranged as irregularly as possible. By adopting such a configuration, it is possible to suppress optical interference caused by periodic repetition of uneven portions between dots or dot groups.

  In the liquid crystal display device of the present invention, a color material layer is provided corresponding to each of the dots, and a pixel composed of a plurality of the dots having the color material layer of different colors is provided as a display unit. Each dot constituting one pixel can be configured to have substantially the same reflection characteristics. That is, the present invention can be preferably applied to a liquid crystal display device that performs color display using a pixel composed of a plurality of color dots as a display unit. With such a configuration, it is possible to prevent coloring due to non-uniform reflection characteristics between the dots constituting the pixel, and to obtain a high-quality display.

  In the liquid crystal display device of the present invention, the display region may include a plurality of pixels having different reflection characteristics. When the reflection characteristics of the pixels provided in the display area are the same, optical interference is likely to occur between the pixels, and this tendency becomes particularly prominent when the pixels are made finer and the pitch is narrowed. Therefore, by making display characteristics different between pixels as in this configuration, optical interference between the pixels can be prevented, and display quality can be improved. In this configuration, a plurality of pixel groups including a plurality of pixels having substantially the same reflection characteristics may be included in the display area.

  In the liquid crystal display device of the present invention, the reflective layer may also serve as an electrode for applying a voltage to the liquid crystal layer. That is, the liquid crystal display device of the present invention can be configured to include an electrode having light reflectivity as means for applying a voltage to the liquid crystal layer. With such a configuration, it is possible to realize cost reduction and manufacturing efficiency by reducing the number of members.

  In the liquid crystal display device of the present invention, each of the dots is capable of forming a plurality of liquid crystal alignment regions in which the alignment is controlled by the alignment control structure when a voltage is applied to the liquid crystal layer, in the plane region, Each liquid crystal alignment area formed in the planar area of the dots may have a different reflection characteristic. That is, in the case where display is performed by forming a plurality of liquid crystal domains when a voltage is applied in the plane area of the dots, it is preferable that the reflection characteristics are different in each liquid crystal domain. By adopting such a configuration, it is possible to prevent optical interference between liquid crystal domains from occurring in fine dots and large interference fringes from being generated.

  In the liquid crystal display device of the present invention, the dot is provided with an electrode having a plurality of island-shaped portions and a connecting portion that conductively connects the plurality of island-shaped portions, and in the plane region of each island-shaped portion. It can be set as the structure by which the said orientation control structure is provided. According to this configuration, substantially radial liquid crystal domains can be formed in the planar region of the plurality of island-shaped portions by the peripheral end portion of the island-shaped portions and the alignment control action of the alignment control structure, and uniform in all directions. A wide viewing angle liquid crystal display device capable of display can be provided.

In the liquid crystal display device of the present invention, the plurality of dots having substantially the same reflection characteristics may include the reflection layer and the alignment control structure having substantially the same configuration.
Further, in the above configuration, in the plurality of dots having substantially the same reflection characteristics, the uneven shape of the reflective layer, the shape and arrangement of the alignment control structure, and the arrangement relationship between the reflection layer and the alignment control structure Are preferably substantially the same.

  In the liquid crystal display device of the present invention, the reflective layer may be partially formed in the planar area of the dots. That is, the present invention can also be applied to a transflective liquid crystal display device. In the transflective liquid crystal display device in which the reflective display area is narrowed, the number of uneven portions formed in the reflective layer is reduced, so that color change and display unevenness due to viewing angle are likely to occur. If the configuration of the present invention is applied to such a liquid crystal display device, it is possible to obtain a remarkable effect of improving viewing angle characteristics and display quality as compared with a reflective liquid crystal display device.

  Next, an electronic apparatus according to the present invention includes the liquid crystal display device according to the present invention described above. According to this configuration, an electronic apparatus including a display unit with a wide viewing angle, high luminance, and high contrast is provided.

  Embodiments of the present invention will be described below with reference to the drawings. In each of the drawings referred to below, the scale of each member is appropriately changed and displayed in order to make the laminated film and the member recognizable on the drawing.

(First embodiment)
FIG. 1 is a circuit configuration diagram of a liquid crystal display device according to a first embodiment of the present invention, FIG. 2 is a configuration diagram showing a schematic planar structure of the electrode, and FIG. 3 is a diagram showing one pixel region. It is. The liquid crystal display device shown in these figures is an active matrix color liquid crystal display device using a TFD (Thin film diode) element (two-terminal nonlinear element) as a switching element. Further, the liquid crystal display device according to the present embodiment includes a liquid crystal layer made of a liquid crystal having a negative dielectric anisotropy in which the initial alignment is vertical alignment.

The liquid crystal display device of this embodiment includes a scanning line driving circuit 110 and a data line driving circuit 120 as shown in FIG. The liquid crystal display device 100 is provided with signal lines, that is, a plurality of scanning lines 13 and a plurality of data lines 9 intersecting with these scanning lines 13. The scanning lines 13 are scanned by the scanning line driving circuit 110. Are driven by the data line driving circuit 120. In each pixel region 150, the TFD element 40 and the liquid crystal display element 160 (liquid crystal layer) are connected in series between the scanning line 13 and the data line 9.
In FIG. 1, the TFD element 40 is connected to the scanning line 13 side and the liquid crystal display element 160 is connected to the data line 9 side. On the contrary, the TFD element 40 is connected to the data line 9 side and the liquid crystal display element 160 is connected to the data line 9 side. The display element 160 may be provided on the scanning line 13 side.

  Next, the planar structure of the electrodes provided in the liquid crystal display device of the present embodiment will be described with reference to FIG. As shown in FIG. 2, in the liquid crystal display device of the present embodiment, pixel electrodes 31 (see FIG. 3 for the detailed planar shape) connected to the scanning lines 13 via the TFD elements 40 are arranged in a matrix. The common electrodes 9 are arranged in a substantially strip shape (stripe shape) in plan view so as to face the pixel electrodes 31 in the direction perpendicular to the paper surface. The common electrode 9 forms a data line shown in FIG. 1 and has a stripe shape that intersects the scanning line 13. In the present embodiment, each region in which each pixel electrode 31 is formed forms one dot and has a structure capable of displaying for each dot arranged in a matrix.

  Here, the TFD element 40 is a switching element that connects the scanning line 13 and the pixel electrode 31. For example, the TFD element 40 is formed on the surface of the first conductive film mainly composed of tantalum, the first conductive film, the insulating film mainly composed of tantalum oxide, and formed on the surface of the insulating film. An MIM structure including a second conductive film as a main component is provided. The first conductive film of the TFD element 40 is connected to the scanning line 13, and the second conductive film is connected to the pixel electrode 31.

  Next, the pixel configuration of the liquid crystal display device 100 of the present embodiment will be described with reference to FIG. 3A is a plan configuration diagram illustrating one pixel region of the liquid crystal display device 100, and FIG. 3B is a cross-sectional configuration diagram along line A-A 'of FIG. As shown in FIG. 2, the liquid crystal display device 100 of the present embodiment has a reflection made of a metal thin film having light reflectivity such as aluminum or silver inside the area surrounded by the data lines 9 and the scanning lines 13. It has dots D1 to D3 provided with electrodes 31. In these dots, as shown in FIG. 3A, a color filter of one of the three primary colors is formed corresponding to one dot, and three dots (D1, D2, D3) are 3 Pixels including color filters 22B, 22G, and 22R are formed.

  As shown in FIG. 3A, the reflective electrode 31 includes three island portions 31a to 31c and connecting portions 31d and 31e that electrically connect the adjacent island portions. Yes. More specifically, island portions 31a to 31c having an octagonal shape in plan view and having substantially the same plane area are arranged in the dot extending direction (the left-right direction in the drawing), The connecting portions 31d and 31e extending substantially parallel to the arrangement direction of the island-shaped portions 31a to 31c are provided between the shaped portions 31a and 31b and between the island-shaped portions 31b and 31c, respectively. In addition, scanning lines 13 extending in the horizontal direction in the figure are provided in the boundary region of each dot, and are connected to the island-shaped portion 31 a via the TFD element 40. The members indicated by reference numerals 9a to 9c arranged in the central portions of the planar regions of the island-shaped portions 31a to 31c are openings (orientations) provided by partially cutting the common electrode 9 facing the pixel electrode 31. Control means).

  A plurality of concavo-convex portions 24a are formed in the planar region of each of the island-shaped portions 31a to 31c, and the light scattering function is imparted to the reflective electrode 31 by the concavo-convex shape formed by these concavo-convex portions 24a. The concavo-convex portions 24a are arranged as irregularly as possible in the plane regions of the island portions 31a to 31c, and are arranged at different positions so as to exhibit different reflection characteristics between the island portions 31a to 31c. Yes. On the other hand, in the three reflective electrodes 31 arranged in the vertical direction in the figure, the concavo-convex portions 24a... Have the same concavo-convex shape. That is, in the liquid crystal display device of the present embodiment, the island-shaped portions 31a to 31c have different reflection characteristics, while the dots D1 to D3 have substantially the same reflection characteristics.

  Next, looking at the cross-sectional structure shown in FIG. 3B, the liquid crystal display device 100 of the present embodiment includes a lower substrate (element substrate) 10 and an upper substrate (counter substrate) 25 disposed opposite thereto. A structure in which a liquid crystal layer 50 made of a liquid crystal material in which an initial alignment state is vertically aligned, that is, a liquid crystal material having a negative dielectric anisotropy, is sandwiched. That is, the liquid crystal display device of the present embodiment is a vertical alignment type liquid crystal display device including the vertical alignment type liquid crystal layer 50, and is a reflection type liquid crystal display device that performs display by reflecting external light.

The lower substrate 10 includes a resin layer 24 made of a resin material such as an acrylic resin and a reflective film made of a highly reflective metal film such as aluminum or silver on the surface of a substrate body 10A made of a translucent material such as quartz or glass. The electrode 31 is stacked. A TFD element 40 and a scanning line 13 are provided corresponding to the reflective electrode 31.
In the resin layer 24 formed on the substrate body 10A, a plurality of uneven portions 24a are formed in a plane region corresponding to the island-like portions 31a to 31c on the surface, and formed by these uneven portions 24a. The surface of the reflective electrode 31 has an uneven shape following the uneven shape. Since the reflected light is scattered by such unevenness, reflection from the outside is prevented and good visibility can be obtained.

Although not shown, a vertical alignment film made of polyimide or the like is formed so as to cover the reflective electrode 31. This vertical alignment film is an alignment film that aligns liquid crystal molecules perpendicularly to the film surface. In this embodiment, a film that is not subjected to an alignment treatment such as rubbing is preferably used.
In this embodiment, the reflective electrode 31 made of a metal thin film is provided. However, an electrode for applying a voltage to the liquid crystal layer 50 is formed of, for example, ITO (indium tin oxide), and the ITO electrode is formed under the ITO electrode. Of course, a reflective layer made of aluminum, silver, or the like may be separately formed on the side (substrate body 10A side).

  On the other hand, the upper substrate 25 has, on the upper substrate 25 side, a red color filter (coloring material layer) 22R and a translucent material on the liquid crystal layer 50 side of the substrate body 25A made of a translucent material such as glass or quartz. 3 and a common electrode 9 made of a transparent conductive material such as ITO and having a planar shape shown in FIG. 3A are formed in order. Openings 9a to 9c having a predetermined shape with notches formed therein are formed, and these openings 9a to 9c are provided corresponding to the respective central portions of the island-shaped portions 31a to 31c. Although not shown, a vertical alignment film made of polyimide or the like is provided so as to cover the common electrode 9.

  On the outer surface side of the upper substrate 25, a circularly polarizing plate is provided in which the retardation plate 16 and the polarizing plate 17 are laminated from the substrate body 25A side. That is, in the liquid crystal display device 100 according to the present embodiment, display is performed by making circularly polarized light incident on the liquid crystal layer 50. When linearly polarized light is incident on the liquid crystal layer 50, the reflectance may be non-uniform in the dots depending on the orientation direction of the liquid crystal molecules when a voltage is applied. A uniform reflectance can be obtained regardless of the orientation direction, and the display luminance of the liquid crystal display device can be improved.

  As the configuration of the circular polarizing plate, a circular polarizing plate combining a polarizing plate and a λ / 4 retardation plate, a broadband circular polarizing plate combining a polarizing plate, a λ / 2 retardation plate, and a λ / 4 retardation plate, Alternatively, a circularly polarizing plate having a viewing angle compensation function by combining a polarizing plate, a λ / 2 retardation plate, a λ / 4 retardation plate, and a negative C plate can be employed. The “C plate” is a retardation plate having an optical axis in the film thickness direction.

  In the liquid crystal display device of the present embodiment having the above-described configuration, the reflective electrode 31 is configured such that the regular octagonal island-shaped portions 31a to 31c are electrically connected by the connecting portions 31d and 31e, and the island-shaped portion 31a. Since the openings 9a to 9c are provided in the common electrode 9 corresponding to each of .about.31c, the tilt direction of the liquid crystal molecules at the time of electric field application is appropriately controlled, and the reflection having excellent viewing angle characteristics. The display can be performed. This orientation control action will be described below.

First, in a state where no electric field is applied between the common electrode 9 and the reflective electrode 31 (when no voltage is applied), the liquid crystal molecules of the liquid crystal layer 50 are aligned perpendicular to the substrate surface. When a voltage is applied to the electrodes 9 and 31, the liquid crystal molecules arranged in the planar region of the island-shaped portion 31a are perpendicular to the side edges of the island-shaped portion 31a in the plane direction due to the oblique electric field generated at the side edge portions. The liquid crystal molecules around it fall in the same direction so as to be aligned with the alignment state at the side edge of the island 31a. As a result, the liquid crystal molecules arranged in the planar region of the island-shaped part 31a are oriented toward the center of the regular octagonal island-shaped part 31a when an electric field is applied.
Further, in the case of the present embodiment, since the planar circular opening 9a is provided at substantially the center of the planar region of the island-shaped part 31a, the edge of the island-shaped part 31a is also provided at the periphery of the opening. An alignment control action similar to that of the portion occurs, and the liquid crystal molecules are aligned radially in plan view with the opening 9a as the center.

As described above, in the liquid crystal display device 100 of the present embodiment, when a voltage is applied, a flat electric field is generated in the plane region of the island portion 31a by the oblique electric field generated at the peripheral end portion of the island portion 31a and the peripheral end portion of the opening 9a. A liquid crystal domain in which liquid crystal molecules are aligned radially is formed. Also in the planar regions of the island-shaped portions 31b and 31c, a planar liquid crystal domain is generated due to the alignment control action similar to that of the island-shaped portion 31a.
With the above operation, the liquid crystal display device 100 according to the present embodiment has a structure in which liquid crystal domains having a radial alignment state in a plan view are arranged in the dots D1 to D3 when a voltage is applied. And uniform viewing angle characteristics can be obtained.

  Further, in the liquid crystal display device of the present embodiment, each island shape is formed by the side edges of the island portions 31a to 31c and the openings 9a to 9c of the common electrode 9 provided corresponding to the island portions 31a to 31c. Since the alignment state of the liquid crystal in the part formation region is controlled, the alignment state of the liquid crystal can be controlled well even when the plane area of the island portions 31a to 31c formed in the dot region is increased. Be able to. Specifically, according to the configuration of the present embodiment, even if relatively large island portions 31a to 31c of about 40 to 50 μmφ are formed, the orientation can be stabilized.

  Further, according to the reflective color liquid crystal display device of the present embodiment, in addition to the effect of obtaining a display with a wide viewing angle and high contrast, (1) the occurrence of interference colors is small even when irradiated with parallel light. (2) viewing angle It is possible to obtain the effect that there is little coloration and display unevenness due to (3), and (3) a clear display without blur is obtained. Hereinafter, these functions and effects will be described.

(1) The generation of interference colors is small even when irradiated with parallel light.
In the reflective display device, coloring due to optical interference due to the arrangement of the concavo-convex portions 24a provided to give the reflective electrode 31 a concavo-convex shape may be a problem. The following three patterns can be considered as the uneven interference. Hereinafter, these patterns [1] to [3] will be described with reference to FIGS. 4 to 7 are explanatory views showing a schematic plane configuration of dots or pixels (groups) provided in the liquid crystal display device.

[1-1] Due to Regularity of Irregularities in Dots The dots 110a and 110b shown in FIG. 4 are mainly composed of the reflective electrode 111, and are composed of a plurality of irregularities 112 in the planar area of the reflective electrode 111. The uneven shape is given. In the dots 110a shown in FIG. 4A, the concavo-convex portions 112 are arranged at regular intervals in a square lattice shape, and in the dots 110b shown in FIG. 4B, the concavo-convex portions 112 are randomly arranged in the region. Yes.
As shown in FIG. 4A, when the concavo-convex portions 112 are arranged at equal intervals on the top, bottom, left, and right in the figure, a direction in which light is strengthened and a direction in which light is weakened are generated periodically by interference according to the pitch P1. The direction in which light intensifies (becomes weakening) depends on the wavelength of the light, so it looks like a rainbow. In general, the smaller the pitch, the stronger (weakening) direction occurs at a larger angular pitch, so it is necessary to suppress regularity as much as possible, especially within the dots. As shown in FIG. 112 are preferably arranged at random.

However, even if the random arrangement shown in FIG. 4B is employed, interference according to the distance between any two points remains. That is, when the uneven portions 112 are arranged in the same manner in other dots, interference may occur due to the uneven portions 112 of different dots. That is, in the liquid crystal display device provided with the dots 110b shown in FIG. 5A, interference due to the pitches P2 and P3 between the two points is strengthened.
However, in the case of the liquid crystal display device according to the present invention, such interference between dots is difficult to be visually recognized. Hereinafter, the operation will be described with reference to FIG. FIG. 5B is a diagram showing a dot 110c having a configuration according to the present invention. The dot 110c is provided with a reflective electrode 111 and uneven portions 112a to 112c formed on the reflective electrode 111. ing.

  In the conventional liquid crystal display device in which the alignment is not divided, as shown in FIG. 5A, the brightness in each of the concavo-convex portions 112 is almost the same, but in the liquid crystal display device of this embodiment, the island shown in FIG. Due to the alignment control action between the side edges of the shaped portions 31a to 31c and the openings 9a to 9c arranged at the center thereof, the liquid crystal during voltage application can be seen in a plan view within the region of the island shaped portions 31a to 31c. Radial liquid crystal domains are formed. Thereby, as conceptually shown in FIG. 5B, the image is displayed with different brightness depending on the position in the dot. In other words, the display is bright at the position of the uneven portion 112a indicated by the white circle, but is slightly darker at the position of the uneven portion 112b with the upward-sloping diagonal line in the drawing, and the unevenness with the downward-sloping diagonal line in the drawing. It becomes darker at the position of the portion 112c.

In general, the interference light intensity I _{max in the} direction in which light is intensified in the interference of light of intensity I ₁ and light of intensity I ₂ is I _max = I ₁ + I ₂ + 2 × (I ₁ + I ₂ ) ^1/2 The interference light intensity I _{min in the} direction in which light is weakened is given by I _min = I ₁ + I ₂ −2 × (I ₁ + I ₂ ) ^1/2 . _Therefore, when I 1 = _{I 2,} although I max _{/ I min} is the denominator becomes infinite becomes zero, for example, when the intensity of _{I 1} is half of _{I 2 (I 1 = I 2} /2) is _{, I max / I min = 34} , the more when the intensity of _{I 1} is 1/3 of _{I 2 (I 1 = I 2} /3) _{becomes I max /} I min = 14. That is, interference between lights having different intensities is difficult to see due to a decrease in contrast. Therefore, in a liquid crystal display device in which liquid crystal is oriented and divided when a voltage is applied as in this embodiment, interference due to regularity in dots is difficult to see. There is an effect.

[1-2] Due to Regularity of RGB Dots in Pixel Pixel 135 shown in FIG. 6 includes R, G, and B dots 110R, 110G, and 110B, and each dot includes blue, green, A red color filter is provided. Each dot 110 </ b> R, 110 </ b> G, 110 </ b> B includes a reflective electrode 111 and a plurality of concavo-convex portions 112 provided to give the reflective electrode 111 a concavo-convex shape.
As shown in FIG. 6, in the pixel 135 composed of three dots 110R, 110G, and 110B, when the same uneven arrangement is made for each color dot of R, G, and B, the same pitch (P4) in the dot arrangement direction. Thus, interference occurs due to the regularity in which the uneven portions 112 are arranged. However, since there are few common wavelength components in the reflected light in each dot of R, G, and B, interference is weak originally.
Furthermore, in the case of the present invention, the viewing angle characteristics are different because the alignment of the liquid crystal in each uneven portion is different. Therefore, when interference by all the uneven portions is integrated, the specific direction is not brightened, and the interference does not occur. Even if it occurs, it is not noticeable. Accordingly, it is possible to appropriately select whether the concavo-convex portions 112 are arranged in the same or different arrangement for each of R, G, and B dots. In the liquid crystal display device 100 described above, the concave / convex arrangement is common to the dots D1 to D3, and only one type of concave / convex pattern of the resin layer 24 for imparting the concave / convex shape to the reflective electrode 31 is required. There is an advantage that manufacturing can be performed efficiently.

[1-3] Due to Regularity Between Pixels FIG. 7 shows four pixels 135 including three dots 110R, 110G, and 110B. Each dot 110 </ b> R, 110 </ b> G, 110 </ b> B includes a reflective electrode 111 and a plurality of uneven portions 112.
As shown in FIG. 7, when the same unevenness is arranged in each pixel 135, the unevenness 112 is arranged at the same pitch (P 5) across the plurality of pixels 135, resulting in interference. However, this interference is not conspicuous because the repetitive pitch of the concavo-convex portions 112 is considerably longer than the interference based on the regularity in the dots, and the angular pitch in the strengthening (weakening) direction becomes smaller. Even so, when the pitch of the pixels is increased and the pitch is reduced, interference may be conspicuous. Therefore, it is preferable to devise an irregular uneven arrangement between the pixels.

(2) No coloration or display unevenness due to viewing angle.
In the liquid crystal display device 100 of this embodiment, as shown in FIG. 3, since the liquid crystal is divided in the dots D1 to D3, the amount of reflected light at the positions of the concave and convex portions 24a is all different. However, since the concavo-convex arrangement is the same among the pixel electrodes 31 provided in the three color dots, there is no difference in reflection characteristics and viewing angle characteristics depending on colors. Thereby, coloration of the display and color change due to the viewing angle direction or the light irradiation direction are effectively prevented, and a colorful display can be obtained. In addition, since the uneven arrangement in all the pixels is the same, an effect that rough and uneven display unevenness hardly occurs can be obtained.

  In the present embodiment, the uneven portions 24a are arranged as irregularly as possible between the island-shaped portions 31a to 31c in the dot, so that the viewing angle is set in each region (liquid crystal domain) of the island-shaped portions 31a to 31c. The characteristics are different. In such a configuration, display unevenness may occur within the dots. However, since the dots D1 to D3 are sufficiently small and only the average brightness can be recognized by the human eye, they are visually recognized as display unevenness. It will never be done.

(3) Clear display with wide viewing angle and high contrast.
As described above, the liquid crystal display device 100 according to the present embodiment includes the liquid crystal layer 50 in the vertical alignment mode, and the liquid crystal is aligned and divided in each of the dots D1 to D3. Can be obtained. Of course, since the reflective electrode 31 provided with the light scattering function is provided on the inner surface of the panel, a clear display with no blur can be obtained.

(Second Embodiment)
Next, a liquid crystal display device according to a second embodiment will be described with reference to the drawings. FIG. 10 is a diagram showing a planar structure of the image display area in the liquid crystal display device of the present embodiment. The liquid crystal display device 200 according to the present embodiment has the same basic configuration as the liquid crystal display device 100 according to the first embodiment, and the feature thereof is that the concave and convex portions 24 a provided on the reflective electrode 31. In placement. Therefore, the following description will be made with reference to FIG. 3 as necessary.

  FIG. 10 shows a display area in which pixels 135 composed of three color dots D1 to D3 are arranged in four rows and four columns. In the display area, the color filters 22R, 22G, and 22B are arranged in a stripe pattern in the vertical direction in the figure. In the figure, reference signs a to j shown in each dot indicate a pattern of uneven arrangement in the reflective electrode 31 provided in each dot. In the liquid crystal display device 200, the three dots D1 to D3 constituting one pixel have a common uneven pattern, and the uneven pattern is arranged as randomly as possible between the pixels 135 arranged in a plane. ing.

  Specifically, with reference to FIG. 3, in the liquid crystal display device 200 of the present embodiment, the arrangement of the concavo-convex portions 24 a... Is different. In the planar area of each island-shaped part 31a-31c, the uneven | corrugated | grooved part 24a ... is arrange | positioned irregularly as much as possible, and is uneven | corrugated arrangement | positioning which is different also between island-like parts 31a-31c.

  The configuration of the liquid crystal display device 200 of the present embodiment is a configuration suitable for use in a high-definition liquid crystal display device with a small dot pitch. In the liquid crystal display device 100 according to the first embodiment, the uneven portions 24a... Are irregularly arranged in each dot, but the dot pitch is reduced because of the common uneven arrangement between the dots and the pixels. In such a case, there is a possibility that interference due to the periodic arrangement of the concavo-convex portions 24a across the pixels as described with reference to FIG. 7 occurs. On the other hand, in the liquid crystal display device 200 of this embodiment, the uneven patterns a to j are irregularly arranged with respect to the arrangement of the pixels 135 as shown in FIG. It can be prevented. On the other hand, since the reflection characteristics of the pixels 135 are relatively non-uniform, it has been predicted that rough and uneven display unevenness is likely to be seen. However, the present inventors have confirmed that this display unevenness is a dot pitch. When it was small, it was not noticeable. Furthermore, it became invisible when the flat area of the uneven portions 24a.

(Third embodiment)
Next, a liquid crystal display device according to a third embodiment will be described with reference to the drawings. 11A is a plan configuration diagram illustrating one pixel region of the liquid crystal display device 300, and FIG. 11B is a cross-sectional configuration diagram taken along line BB ′ of FIG. It is drawing equivalent to FIG. 3 of embodiment.
The liquid crystal display device 300 of this embodiment is a transflective vertical alignment mode liquid crystal display device. In addition, in FIG. 11, about the thing to which the code | symbol same as the code | symbol shown in FIG. 3 was attached | subjected, description is abbreviate | omitted as a similar structural member.

  As shown in FIG. 11, the liquid crystal display device 300 according to the present embodiment includes a plurality of dots D1 to D3 each including a pixel electrode 331 inside a region surrounded by the data lines 9, the scanning lines 13, and the like. ing. In these dots, as shown in FIG. 11A, a color filter of one of the three primary colors is formed corresponding to one dot, and three dots (D1, D2, D3) have three colors. Pixels including the color filters 22R, 22G, and 22B are formed.

The pixel electrode 331 is a transparent electrode formed of a transparent conductive material such as ITO, and includes octagonal island-shaped portions 331a to 331c in plan view and connecting portions 331d and 331e that conductively connect them. The pixel electrode 331 and the TFD element 40 are electrically connected via an island-shaped portion 331a.
The island portions 331a are arranged in the formation region of the reflective film (reflective layer) 20 partially provided in each dot region, and the remaining island portions 331b and 331c are formed in the non-formation region of the reflective film 20. Has been placed. Under this configuration, the planar area of the island-shaped portion 331a (and a part of the connecting portion 331d) disposed in the region where the reflective film 20 is formed serves as a reflective display region for each dot, and the island-shaped portions 331b, 331c, A part of the connecting portion 331d and a planar area of the connecting portion 331e are a transmissive display region.

  11B, the liquid crystal display device 300 includes a liquid crystal layer 50 sandwiched between a lower substrate (element substrate) 310 and an upper substrate (counter substrate) 325 that are arranged to face each other. A panel and a backlight (illuminating device) 15 disposed on the back side (the lower side in the figure) of the liquid crystal panel are provided.

The lower substrate 10 is mainly composed of a substrate body 10A made of a translucent material such as quartz or glass. A reflective film 20 made of a highly reflective metal film such as aluminum or silver is partially formed on the surface of the substrate body 10A via a resin layer 24, and a region where the reflective film 20 is formed is the previous reflective film. Corresponds to the display area. The resin layer 24 formed on the substrate body 10 </ b> A is provided with a concavo-convex shape including a plurality of concavo-convex portions 24 a on the surface, and the reflective film 20 has a concavo-convex shape that follows the concavo-convex shape of the resin layer 24.
In the present embodiment, the concavo-convex portions 24a are irregularly arranged in the planar region of each island-shaped portion 31a, but the island-shaped portions 31a of all the dots provided in the liquid crystal display device, It has a common uneven arrangement.

  A red color filter 22R is provided across the reflective display area and the transmissive display area on the reflective film 20 and the substrate body 10A in the planar area of the dots. In plan view, as shown in FIG. 11A, three color filters 22R (red), 22G (green), and 22B (blue) are arranged, and are planar with the boundary region of adjacent color filters. The scanning line 13 extends to overlap the.

  An insulating film 26 is selectively formed on the color filter 22 </ b> R so as to be positioned above the reflective film 20. As described above, the insulating film 26 partially formed in the dots makes the thickness of the liquid crystal layer 50 different between the reflective display area and the transmissive display area. The insulating film 26 is made of an organic material film such as an acrylic resin having a film thickness of about 0.5 to 2.5 μm, for example, and its film thickness continuously changes in the vicinity of the boundary between the reflective display area and the transmissive display area. The boundary level | step-difference area | region N which consists of an inclined surface which comprises is comprised. The layer thickness of the liquid crystal layer 50 in the transmissive display region is about 2 to 7 μm, and the liquid crystal layer thickness in the reflective display region is about half of the liquid crystal layer thickness in the transmissive display region.

  As described above, the insulating film 26 functions as a liquid crystal layer thickness adjusting layer that varies the thickness of the liquid crystal layer 50 between the reflective display region and the transmissive display region depending on the film thickness of the insulating film 26. In the case of the present embodiment, the edge of the flat surface on the upper side of the insulating film 26 and the edge of the island-shaped portion 331 a constituting the pixel electrode 331 on the upper substrate 325 side substantially coincide with each other and are formed by the insulating film 26. The boundary step region N is disposed at a position overlapping the connecting portion 331d between the island-shaped portions 331a and 331b in plan view.

  A common electrode 9 made of a transparent conductive material such as ITO is formed on the surface of the lower substrate 310 including the surface of the insulating film 26. The common electrode 9 is formed in a stripe shape in plan view extending in the direction perpendicular to the paper surface, and functions as a common electrode with a plurality of dots arranged in parallel in the direction perpendicular to the paper surface. A vertical alignment film is formed on the lower substrate 310 so as to cover the common electrode 9.

  The common electrode 9 is formed with substantially conical dielectric protrusions (orientation control means) 19a to 19c made of a dielectric material such as resin corresponding to each dot. As shown in FIG. 11A, the dielectric protrusions 19a to 19c are provided corresponding to the island-shaped portions 331a to 331c of the pixel electrode 331, respectively, and are substantially in the plane region of each of the island-shaped portions 331a to 331c. Located in the center.

  Next, on the upper substrate 325 side, a pixel electrode 331 having a planar shape shown in FIG. 11A is formed on the liquid crystal layer 50 side of the substrate body 25A made of a light-transmitting material such as glass or quartz. A TFD element 40 and a scanning line 13 are provided corresponding to the pixel electrode 331. Although not shown, a vertical alignment film made of polyimide or the like is provided so as to cover the pixel electrode 331.

  On the outer surface side of the lower substrate 310, a circularly polarizing plate is provided by laminating the retardation plate 28 and the polarizing plate 29 from the substrate body 10A side, and the outer surface side of the upper substrate 25 is positioned from the substrate body 25A side. A circularly polarizing plate in which the phase difference plate 16 and the polarizing plate 17 are laminated is provided. As the retardation plate 28 and the polarizing plate 29, those having the same configuration as the retardation plate 16 and the polarizing plate 17, respectively, are used.

In the transflective liquid crystal display device, since the reflective display area and the transmissive display area are provided by dividing a plane area of one dot, the reflective display area is narrower than that of the first embodiment, and the reflective film There are also few uneven | corrugated | grooved parts provided to. For this reason, the color change due to the viewing angle in the reflective display and rough spotted unevenness are likely to occur.
On the other hand, in the liquid crystal display device 300 of the present embodiment having the above-described configuration, the uneven portions 24a formed in the reflective display area are irregularly arranged in the dot plane area, and the uneven arrangement pattern is provided for each uneven pattern. By adopting a common configuration for the dots, non-uniform reflection characteristics due to viewing angles are eliminated, and reflective display with a wide viewing angle, high brightness, and high contrast is possible. As described above, when the configuration according to the present invention is applied to the transflective liquid crystal display device, a remarkable effect can be obtained as compared with the reflective type.

  Further, in the liquid crystal display device 300 of the present embodiment, the insulating film 26 provided in the reflective display region can reduce the thickness of the liquid crystal layer 50 in the reflective display region to about half of the liquid crystal layer thickness in the transmissive display region. The retardation of the liquid crystal layer in the reflective display region and the retardation of the liquid crystal layer in the transmissive display region can be made substantially equal. As a result, the electro-optical characteristics in both the regions can be made uniform, and the display contrast can be improved.

  Further, by adopting the multi-gap structure, the boundary step region N generated in the dot extends to a region between the island-shaped portion 331a of the reflective display region and the island-shaped portion 331b of the transmissive display region. Since it is arranged so as to overlap with the connecting portion 331d in a plan view, it is possible to effectively suppress a deterioration in display quality caused by the boundary step region N. That is, when the electrode is formed in the boundary step region N, the liquid crystal molecules are inclined and aligned with respect to the substrate surface, so that a weak alignment regulating force acts on the liquid crystal molecules when a voltage is applied. If the pixel structure is designed ignoring this weak alignment regulating force, the liquid crystal alignment may be disturbed. In the liquid crystal display device according to the present embodiment, an electrode disposed on the boundary step region N is removed as much as possible to remove this weak alignment regulating force, and conversely, an oblique electric field generated at the edges of the island portions 331a and 331b. By making the strong orientation regulating force due to the above, dominant display can be obtained in both the reflective display area and the transmissive display area.

  The technical scope of the present invention is not limited to the above-described embodiments, and can be appropriately changed. For example, in each of the above embodiments, the planar shape of the island-shaped portions 31a to 31c and 331a to 331c constituting the pixel electrode is a regular octagonal shape, but the planar shape of these island-shaped portions is limited to the shape. For example, any of a circular shape, an oval shape, a polygonal shape, and the like can be applied. That is, the island-shaped portions 31a to 31c and 331a to 331c can be applied without any problem as long as they can form liquid crystal domains that take a substantially radial alignment state when a voltage is applied in the planar region. Further, the number of island portions provided in each dot is not limited to three, and may be an appropriate number according to the dot pitch.

(Electronics)
FIG. 12 is a perspective view showing an example of an electronic apparatus according to the present invention. A cellular phone 1300 shown in this figure includes the display device of the present invention as a small-sized display portion 1301 and includes a plurality of operation buttons 1302, an earpiece 1303, and a mouthpiece 1304.
The display device of each of the above embodiments is not limited to the mobile phone, but is an electronic book, a personal computer, a digital still camera, a liquid crystal television, a viewfinder type or a monitor direct view type video tape recorder, a car navigation device, a pager, and an electronic notebook. , Calculators, word processors, workstations, videophones, POS terminals, devices equipped with touch panels, etc., and can be suitably used as image display means. In any electronic device, it is bright, has high contrast, and has a wide viewing angle. In addition, high-quality reflection display or transflective display without color unevenness and display unevenness is possible.

The circuit block diagram of the liquid crystal display device of 1st Embodiment. The figure which shows an electrode structure planarly. FIG. 2 is an enlarged plan view (a) and a cross-sectional view (b) showing an enlarged pixel. Explanatory drawing which showed the schematic plane structure of the dot. Explanatory drawing which showed the schematic plane structure of the dot. Explanatory drawing which showed the schematic plane structure of the pixel. Explanatory drawing which showed the schematic plane structure of the some pixel. Explanatory drawing which showed the schematic planar structure of the reflective electrode. The graph which shows the reflectance in the several position on the reflective electrode shown in FIG. The plane block diagram of the liquid crystal display device of 2nd Embodiment. The pixel plane | planar block diagram (a) in 3rd Embodiment, and a cross-sectional block diagram (b). FIG. 11 is a perspective configuration diagram illustrating an example of an electronic apparatus according to the invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 100,200,300 ... Liquid crystal display device, 9 ... Common electrode (data line), 13 ... Scanning line, 20 ... Reflective film, 24 ... Resin layer, 24a ... Uneven part, 26 ... Insulating film (liquid crystal layer thickness adjustment layer) 31 ... Pixel electrode, 50 ... Liquid crystal layer, 31a to 31c, 331a to 331c ... Island-like portion, 9a to 9c ... Opening (alignment control means), 19a to 19c ... Dielectric protrusion (alignment control means)

Claims (11)

A liquid crystal display device comprising a display region in which a plurality of dots constituting one display unit are arranged, with a liquid crystal layer having an initial orientation of vertical orientation sandwiched between a pair of opposed substrates.
In the plane region of each dot, a reflective layer and an alignment control structure for controlling the alignment state of the vertically aligned liquid crystal are provided,
The reflective layer is provided with a concavo-convex shape consisting of a plurality of concavo-convex portions arranged almost irregularly in the planar region of the dots,
A liquid crystal display device, wherein the display area includes a plurality of the dots having substantially the same reflection characteristics.   The liquid crystal display device according to claim 1, wherein a plurality of dot groups including the dots having substantially the same reflection characteristics are included in the display area. A color material layer is provided corresponding to each of the dots, and a pixel constituted by a plurality of the dots having the color material layer of different colors is provided as a display unit.
The liquid crystal display device according to claim 1, wherein each dot constituting one pixel has substantially the same reflection characteristic.   The liquid crystal display device according to claim 3, wherein the display region includes a plurality of the pixels having different reflection characteristics.   The liquid crystal display device according to claim 1, wherein the reflective layer also serves as an electrode for applying a voltage to the liquid crystal layer. Each of the dots is capable of forming a plurality of liquid crystal alignment regions that are controlled in alignment by the alignment control structure when a voltage is applied to the liquid crystal layer in the plane region,
6. The liquid crystal display device according to claim 1, wherein the liquid crystal alignment regions formed in the planar region of the dots have different reflection characteristics.   The dot is provided with an electrode having a plurality of island-shaped portions and a connecting portion that conductively connects the plurality of island-shaped portions, and the orientation control structure is provided in a planar region of each island-shaped portion. The liquid crystal display device according to claim 6, wherein the liquid crystal display device is provided.   The liquid crystal display device according to claim 1, wherein the plurality of dots having substantially the same reflection characteristics include the reflection layer and the alignment control structure having substantially the same configuration. .   In the plurality of dots having substantially the same reflection characteristics, the uneven shape of the reflection layer, the shape and arrangement of the alignment control structure, and the arrangement relationship between the reflection layer and the alignment control structure are substantially the same. The liquid crystal display device according to claim 1, wherein the liquid crystal display device is a liquid crystal display device.   The liquid crystal display device according to claim 1, wherein the reflective layer is partially formed in a planar area of the dots.   An electronic apparatus comprising the liquid crystal display device according to claim 1.

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