JP2004206080A - Liquid crystal display and electronic apparatus - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a transflective liquid crystal display in which a bright display with high contrast and a wide viewing angle can be obtained. <P>SOLUTION: The liquid crystal display has a liquid crystal layer 50 held between a pair of substrates 10, 25 and has a transmissive display region T and a reflective display region R in one dot region D1. The liquid crystal layer 50 is made of a liquid crystal having negative dielectric anisotropy showing perpendicular alignment in the initial alignment state. The liquid crystal layer 50 sides of the pair of substrates 10, 25 are provided with electrodes 9, 31, respectively, to drive the liquid crystal. The electrodes 9, 31 are provided with openings 41, 42 and protrusions 43, 44 in the transmissive display region T and the reflective display region R, respectively. The opening area of the openings 41, 42 and possessing area of the projection parts 43, 44 in the plane direction of the substrate are larger in the reflective display region R than in the transmissive display region T. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

  The present invention relates to a liquid crystal display device and an electronic apparatus, and more particularly to a technique capable of obtaining a display with a high contrast and a wide viewing angle in a transflective liquid crystal display device that performs display in both a reflection mode and a transmission mode. .

  2. Description of the Related Art As a liquid crystal display device, a transflective liquid crystal display device having both a reflection mode and a transmission mode is known. As such a transflective liquid crystal display device, a liquid crystal layer is sandwiched between an upper substrate and a lower substrate, and a reflection film in which a light transmission window is formed in a metal film such as aluminum is disposed below. There has been proposed a device provided on the inner surface of a substrate and using this reflection film as a transflective plate. In this case, in the reflection mode, external light incident from the upper substrate side passes through the liquid crystal layer, is reflected by the reflection film on the inner surface of the lower substrate, passes through the liquid crystal layer again, and is emitted from the upper substrate side, contributing to display. I do. On the other hand, in the transmission mode, light from the backlight incident from the lower substrate side passes through the liquid crystal layer from the window of the reflection film, and then exits from the upper substrate side to contribute to display. Therefore, of the reflective film forming region, the region where the window is formed is the transmissive display region, and the other region is the reflective display region.

However, the conventional transflective liquid crystal device has a problem that the viewing angle in transmissive display is narrow. This is because a transflective plate is provided on the inner surface of the liquid crystal cell so that parallax does not occur, and there is a restriction that reflective display must be performed with only one polarizing plate provided on the viewer side. This is because the degree of freedom in design is small. In order to solve this problem, Jisaki et al. Proposed a new liquid crystal display device using a vertically aligned liquid crystal in Non-Patent Document 1 below. The features are the following three.
(1) A "VA (Vertical Alignment) mode" in which a liquid crystal having a negative dielectric anisotropy is vertically aligned with a substrate and is tilted by applying a voltage.
(2) A multi-gap structure in which the liquid crystal layer thickness (cell gap) of the transmissive display region and the reflective display region is different (for this point, see, for example, Patent Document 1).
(3) The transmissive display area is a regular octagon, and a projection is provided at the center of the transmissive display area on the opposing substrate so that the liquid crystal falls in eight directions in this area. That is, an "alignment division structure" is adopted.
JP-A-11-242226 "Development of transflective LCD for high contrast and wide viewing angle by using homeotropic alignment", M. Jisaki et al., Asia Display / IDW'01, p.133-136 (2001)

  However, in the paper by Jisaki et al., The direction in which the liquid crystal falls in the transmissive display area is controlled using projections, but there is no configuration for controlling the direction in which the liquid crystal falls in the reflective display area. Therefore, in the reflective display area, the liquid crystal falls in a random direction. In this case, a discontinuous line called disclination appears at the boundary between different liquid crystal alignment areas, which causes afterimages and the like. In addition, since the respective alignment regions of the liquid crystal have different viewing angle characteristics, there is also a problem that when the liquid crystal device is viewed from an oblique direction, the liquid crystal device appears as a rough spot-like unevenness.

  On the other hand, providing the multi-gap structure as described above in a transflective liquid crystal display device can improve the electro-optical characteristics (transmittance-voltage characteristics, reflectance-voltage characteristics) of the transmissive display region and the reflective display region. It is very effective. This is because light passes through the liquid crystal layer only once in the transmissive display area, but passes through the liquid crystal layer twice in the reflective display area.

  FIG. 12 shows the effect of the multi-gap structure on the electro-optical characteristics (transmittance-voltage characteristics, reflectance-voltage characteristics). FIG. 12A shows the electro-optical characteristics when the transmissive display area and the reflective display area have the same liquid crystal layer thickness. In the case of a liquid crystal display device that does not have such a multi-gap structure, the reflectance-voltage characteristic of the reflective display is too steep, and unless the transmissive display region and the reflective display region are driven with different voltages, the transmittance decreases. A display problem such as halftone reversal of reflection display may occur. On the other hand, FIG. 12B shows the electro-optical characteristics when the thickness of the liquid crystal layer in the transmissive display area is about twice the thickness of the liquid crystal layer in the reflective display area. With such a multi-gap structure, the reflectivity-voltage characteristics of the reflective display substantially match, so that it is possible to drive with the same voltage.

  However, when such a multi-gap structure is provided, the liquid crystal molecules in the step regions having different thicknesses of the liquid crystal layer are difficult to move, which may cause a problem that the aperture ratio is substantially reduced. In addition, the manufacturing process requires an extra photo process for obtaining a multi-gap structure, which leads to an increase in cost.

  The present invention has been made to solve the above problems, and in a transflective liquid crystal display device, display defects such as afterimages and spot-like unevenness are suppressed, and furthermore, a display with a wide viewing angle is achieved. It is an object of the present invention to provide a liquid crystal display device that is possible and that is unlikely to cause a decrease in aperture ratio due to a step when a multi-gap structure is provided. It is another object of the present invention to provide a simple and suitable method for controlling a direction in which liquid crystal falls in a region where a reflective display is performed, and to provide a liquid crystal display device having a uniform display and a wide viewing angle in both a reflective display and a transmissive display. With the goal.

  In order to achieve the above object, a liquid crystal display device of the present invention has a liquid crystal layer sandwiched between a pair of substrates, and has a transmissive display area for performing transmissive display in one dot area and a reflective display for performing reflective display. A liquid crystal display device provided with a region, wherein the liquid crystal layer is made of a liquid crystal having a negative initial dielectric alignment anisotropy and a dielectric anisotropy, and the liquid crystal layer is provided on the liquid crystal layer side of the pair of substrates. And an electrode for driving the liquid crystal in at least one of the electrodes of the pair of substrates, in each of the transmissive display area and the reflective display area, for regulating the alignment of the liquid crystal. As the alignment regulating means, a slit-shaped opening formed by opening a part of the electrode and / or a convex portion made of a dielectric formed on the electrode are provided, and an opening area of the slit-shaped opening is provided. ,as well as Or the substrate planar direction area occupied by the convex portion of the dielectric, characterized in that it is largely constituted in the reflective display region than the transmissive display region.

The liquid crystal display device of the present invention is a combination of a transflective liquid crystal display device and a liquid crystal in a vertical alignment mode. In particular, the liquid crystal display device has a preferable configuration for controlling the alignment direction when applying an electric field to the liquid crystal in the vertical alignment mode. It was found. When the vertical alignment mode is adopted, a negative type liquid crystal is generally used.However, since the liquid crystal molecules that stand perpendicular to the substrate surface in the initial alignment state are defeated by applying an electric field, there is no contrivance. Otherwise (unless a pretilt is provided), the direction in which the liquid crystal molecules fall cannot be controlled, and disorder in the alignment (disclination) occurs, causing display defects such as light leakage and deteriorating the display quality. Therefore, in adopting the vertical alignment mode, control of the alignment direction of liquid crystal molecules when an electric field is applied is an important factor.
Therefore, in the liquid crystal display device of the present invention, for each of the transmissive display area and the reflective display area, a slit-shaped opening is formed in the electrode as a liquid crystal alignment regulating means, and / or a dielectric (for example, (A resin or the like). As a result, the liquid crystal molecules exhibit vertical alignment in the initial state, and have a pretilt according to the shape of the opening and / or the convex portion. As a result, it is possible to regulate or control the direction in which the liquid crystal molecules fall down, it is difficult to cause disorder of the alignment (disclination), it is possible to avoid display defects such as light leakage, and afterimages and spot-like unevenness are caused. , And a liquid crystal display device having a wide viewing angle can be provided.
In particular, the opening area of the opening in the reflective display region and / or the area occupied by the convex portion in the plane of the substrate is made larger than the opening area of the opening in the transmissive display region and / or the area occupied by the substrate in the plane of the substrate. Since a large voltage is applied to the reflective display area, it is difficult to apply a voltage to the liquid crystal layer, and unless a high voltage is applied in the reflective display area, the liquid crystal molecules do not fall in the direction of the voltage. Therefore, it is possible to make the electro-optical characteristics of the reflective display the same as those of the transmissive display as shown in FIG. 4 without using the multi-gap structure as shown in the prior art.
In other words, according to the present invention, it is possible to obtain the wide viewing angle display based on the liquid crystal alignment control effect as described above, and to drive the liquid crystal in the reflective display region and the transmissive display region with the same voltage and the same voltage with a simple configuration, This makes it possible to provide a liquid crystal display device having excellent electro-optical characteristics.

  Here, the opening and / or the convex portion may have a configuration for regulating the direction in which the vertically aligned liquid crystal molecules fall, and in this case, the vertically aligned liquid crystal molecules may be moved in a predetermined direction. Can be made to fall regularly. As a result, disorder of the alignment of the liquid crystal molecules (disclination) hardly occurs, and display defects such as light leakage can be avoided. Thus, a liquid crystal display device having high display characteristics can be provided. In addition, as a configuration that regulates the direction in which the liquid crystal molecules fall, specifically, a configuration in which the surface of the opening and / or the convex portion is inclined by a predetermined angle with respect to the vertical alignment direction of the liquid crystal molecules. can do.

  The distance between the electrodes provided on the pair of substrates may be substantially the same in the transmissive display area and the reflective display area. Note that the inter-electrode distance in this case refers to the inter-electrode distance of each substrate in a region where an opening and / or a convex portion is not formed. In the liquid crystal display device of the present invention, even when the distance between the electrodes is substantially the same in the transmissive display region and the reflective display region, the electro-optical characteristics of each display region can be made uniform. When a reflective film is provided on any one of the substrates in order to obtain a reflective display, the effects of the present invention can be exhibited even if the thickness of the reflective film is different.

  Further, the convex portion made of the dielectric may be provided on the electrode, and may have an inclined surface inclined at a predetermined angle with respect to the electrode surface. When the convex portion has the inclined surface as described above, it is possible to regulate the direction in which the liquid crystal molecules fall in a direction along the inclined surface, which is preferable.

  Further, the distance between adjacent openings and / or convex portions among the openings and / or the convex portions formed in the reflective display region may be different from the distance between the openings and / or convex portions formed in the transmissive display region. Alternatively, the protrusions may be configured to be smaller than the distance between adjacent openings and / or protrusions. In the case of such a configuration, it is possible to preferably increase the area ratio of the opening and / or the convex portion of the reflective display region to that of the transmissive display region.

  Further, in the liquid crystal display device of the present invention, the pair of substrates includes an upper substrate and a lower substrate, and a backlight for transmissive display is provided on a side of the lower substrate opposite to the liquid crystal layer. On the liquid crystal layer side, a reflective film selectively formed only in the reflective display area may be provided. With such a configuration, a transflective liquid crystal display device can be suitably provided. Further, by providing a color filter layer on the liquid crystal layer side of the upper substrate or on the liquid crystal layer side of the reflective film, it is possible to provide a transflective liquid crystal display device capable of suitably displaying color.

  Next, an electronic apparatus according to another aspect of the invention includes the liquid crystal display device described above. According to such an electronic device, it is possible to provide an electronic device having a display portion with a wide viewing angle and excellent display characteristics, in which display defects such as afterimages and spot-like unevenness are suppressed.

[First Embodiment]
Hereinafter, a first embodiment of the present invention will be described with reference to the drawings.
The liquid crystal display device of this embodiment is an example of an active matrix liquid crystal display device using thin film transistors (hereinafter, abbreviated as TFTs) as switching elements.

  FIG. 1 is an equivalent circuit diagram of a plurality of dots arranged in a matrix forming an image display area of the liquid crystal display device of the present embodiment, and FIG. 2 is a plan view showing a structure of a plurality of adjacent dots of a TFT array substrate. FIGS. 3 and 3 are a plan view (upper row) and a cross-sectional view (lower row) showing the structure of the liquid crystal device. In the following drawings, the scale of each layer and each member is different in order to make each layer and each member have a size recognizable in the drawings.

  In the liquid crystal display device of the present embodiment, as shown in FIG. 1, a plurality of dots arranged in a matrix forming an image display area include a pixel electrode 9 and a switching element for controlling the pixel electrode 9. Are formed, and the data line 6a to which an image signal is supplied is electrically connected to the source of the TFT 30. The image signals S1, S2,..., Sn to be written to the data lines 6a are supplied line-sequentially in this order or supplied to a plurality of adjacent data lines 6a for each group. The scanning lines 3a are electrically connected to the gates of the TFTs 30, and the scanning signals G1, G2,..., Gm are applied to the plurality of scanning lines 3a in a pulsed line-sequential manner at a predetermined timing. The pixel electrode 9 is electrically connected to the drain of the TFT 30. When the TFT 30 serving as a switching element is turned on for a predetermined period, the image signals S1, S2,... Write at the timing of

  The image signals S1, S2,..., Sn of a predetermined level written in the liquid crystal through the pixel electrodes 9 are held for a certain period between the common electrodes described later. The liquid crystal modulates light by changing the orientation and order of the molecular assembly depending on the applied voltage level, thereby enabling gray scale display. Here, in order to prevent the held image signal from leaking, a storage capacitor 70 is added in parallel with the liquid crystal capacitor formed between the pixel electrode 9 and the common electrode. Note that reference numeral 3b is a capacitance line.

Next, a planar structure of a TFT array substrate included in the liquid crystal device according to the present embodiment will be described with reference to FIG.
As shown in FIG. 2, a plurality of rectangular pixel electrodes 9 (outlined by dotted lines 9A) are provided in a matrix on the TFT array substrate, and each pixel electrode 9 extends along the vertical and horizontal boundaries of the pixel electrodes 9. A data line 6a, a scanning line 3a, and a capacitance line 3b are provided. In the present embodiment, one dot region is inside a region where each pixel electrode 9 and the data line 6a, the scanning line 3a, the capacitor line 3b, and the like provided so as to surround each pixel electrode 9 are formed. The structure is such that display is possible for each dot region arranged in a matrix.

  The data line 6a is electrically connected to a source region, which will be described later, of the semiconductor layer 1a constituting the TFT 30, for example, a polysilicon film via the contact hole 5, and the pixel electrode 9 is connected to the semiconductor layer 1a. Among them, it is electrically connected to a drain region described later via a contact hole 8. In addition, the scanning line 3a is arranged to face the channel region (the diagonally shaded region ascending in the figure) of the semiconductor layer 1a, and the scanning line 3a functions as a gate electrode in a portion facing the channel region. .

  The capacitance line 3b is formed from a main line portion extending substantially linearly along the scanning line 3a (that is, a first region formed along the scanning line 3a when viewed in plan) and a portion intersecting the data line 6a. And a projection (ie, a second region extending along the data line 6a when viewed in a plan view) protruding forward (upward in the figure) along the data line 6a. In FIG. 2, a plurality of first light-shielding films 11a are provided in a region indicated by oblique lines rising to the right.

  More specifically, the first light-shielding film 11a is provided at a position covering the TFT 30 including the channel region of the semiconductor layer 1a as viewed from the TFT array substrate side, and further, is opposed to the main line of the capacitor line 3b. A main line portion extending linearly along the scanning line 3a, and a protruding portion protruding from a location intersecting the data line 6a toward a subsequent stage (that is, downward in the drawing) adjacent to the data line 6a. The tip of the downward projection in each stage (pixel row) of the first light-shielding film 11a overlaps the tip of the upward projection of the capacitor line 3b in the next stage below the data line 6a. A contact hole 13 for electrically connecting the first light-shielding film 11a and the capacitance line 3b to each other is provided in the overlapping portion. That is, in the present embodiment, the first light-shielding film 11 a is electrically connected to the preceding or subsequent capacitive line 3 b by the contact hole 13.

  As shown in FIG. 2, a reflective film 20 is formed at the center of one dot region, and the region where the reflective film 20 is formed becomes a reflective display region R, and the reflective film 20 is formed. An area that is not present, that is, the inside of the opening 21 of the reflective film 20 is a transmissive display area T.

  Next, the structure of the liquid crystal display device of the present embodiment will be described with reference to FIG. FIG. 3A is a schematic plan view illustrating a planar structure of a color filter layer provided in the liquid crystal display device of the present embodiment, and FIG. 3B is a plan view of FIG. It is a cross section of a portion corresponding to a layer.

  The liquid crystal display device according to the present embodiment has a dot region including the pixel electrode 9 inside a region surrounded by the data line 6a, the scanning line 3a, the capacitor line 3b, and the like as shown in FIG. ing. In this dot area, as shown in FIG. 3A, one coloring layer of the three primary colors is provided corresponding to one dot area (one of D1, D2, D3). Pixels including the colored layers 22B (blue), 22G (green), and 22R (red) are formed by the dot regions D1, D2, and D3.

  On the other hand, as shown in FIG. 3B, the liquid crystal display device of the present embodiment has a liquid crystal in which the initial alignment state is vertical between the TFT array substrate 10 and the opposing substrate 25 disposed opposite thereto. That is, the liquid crystal layer 50 made of a liquid crystal material having a negative dielectric anisotropy is sandwiched. In the TFT array substrate 10, a reflective film 20 made of a metal film having a high reflectivity such as aluminum or silver is partially formed on a surface of a substrate main body 10A made of a translucent material such as quartz or glass via an insulating film 24. The configuration has been made. As described above, the region where the reflective film 20 is formed becomes the reflective display region R, and the region where the reflective film 20 is not formed, that is, the inside of the opening (light transmitting portion) 21 of the reflective film 20 becomes the transmissive display region T. As described above, the liquid crystal display device of the present embodiment is a vertical alignment type liquid crystal display device including a vertical alignment type liquid crystal layer, and is a transflective liquid crystal display device capable of performing reflective display and transmissive display. . The surface of the insulating layer 24 has an uneven shape, and the surface of the reflective film 20 has an uneven portion following the uneven shape. Since the reflected light is scattered by such unevenness, reflection from the outside is prevented, and a display with a wide viewing angle can be obtained. Further, the transmissive display area does not necessarily need to be an area in which the reflective film 20 is opened, and may be designed to be an area provided with a translucent means such as, for example, partially reducing the thickness of the reflective film 20. .

  On the surface of the insulating film 24 including the surface of the reflective film 20, a pixel electrode 9 made of a transparent conductive film such as indium tin oxide (hereinafter abbreviated as ITO), an alignment film made of polyimide or the like (illustrated) (Abbreviation). In the present embodiment, the reflection film 20 and the pixel electrode 9 are separately provided and laminated. However, in the reflection display region R, a reflection film made of a metal film can be used as the pixel electrode.

  On the other hand, on the counter substrate 25 side, a color filter 22 (a red coloring layer 22R in FIG. 3B) is provided on a substrate main body 25A (a liquid crystal layer side of the substrate main body 25A) made of a translucent material such as glass or quartz. Is provided. The periphery of the colored layer 22R is surrounded by a black matrix BM, and the black matrix BM forms boundaries between the dot regions D1, D2, and D3. Further, on the liquid crystal layer side of the color filter layer 22, a common electrode 31 made of a transparent conductive film such as ITO, and an alignment film (not shown) made of polyimide or the like are formed.

  Note that both the alignment films of the TFT array substrate 10 and the counter substrate 25 are subjected to vertical alignment processing. Further, a retardation plate 18 and a polarizing plate 19 are formed on the outer surface side of the TFT array substrate 10, and a retardation plate 16 and a polarizing plate 17 are formed on the outer surface side of the counter substrate 25. It is configured to be able to enter. As the configuration of the polarizing plate 17 (19) and the phase difference plate 16 (18), a circular polarizing plate combining a polarizing plate and a λ / 4 phase difference plate, or a polarizing plate, a λ / 2 phase difference plate and a λ / 4 A viewing angle compensator comprising a broadband circularly polarizing plate combining a retardation plate, or a polarizing plate, a λ / 2 retardation plate, a λ / 4 retardation plate, and a negative C plate (a retardation plate having an optical axis in the film thickness direction). Can be adopted. A backlight 15 as a light source for transmissive display is provided outside the polarizing plate 19 formed on the TFT array substrate 10.

  In the liquid crystal display device of the present embodiment, at least one of the pair of electrodes that controls the alignment of the liquid crystal layer 50 has a part of the electrode opened in each of the transmissive display region T and the reflective display region R. Slit-shaped openings 41 and 42 or convex portions 43 and 44 made of a dielectric material formed on the electrodes. Specifically, a slit-shaped opening 41 is formed in the transmissive display region T in the pixel electrode 9, and a slit-shaped opening 42 is formed in the reflective display region R. The projection 43 is provided in the reflection display region R.

  The openings 41 and 42 and the convex portions 43 and 44 thus formed on the sandwiching surface of the liquid crystal layer 50 regulate the direction in which the liquid crystal molecules are vertically aligned in the initial state based on the electric field change. That is, by forming the openings 41 and 42 in the electrodes (in this case, the pixel electrodes 9), the direction of the electric field between the electrodes is inclined from the direction perpendicular to the substrate, and the direction in which the liquid crystal molecules fall along the inclination is directed. On the other hand, by forming the convex portions 43 and 44 on the electrode (in this case, the common electrode 31), the liquid crystal molecules are vertically aligned on the inclined surface provided by the convex portions, so that the direction in which the liquid crystal molecules fall is directed. It will be. Here, the convex portions 43 and 44 have, for example, a predetermined inclined surface and a convex stripe shape extending in the longitudinal direction, but are not limited thereto, and regulate the direction in which the liquid crystal molecules fall. It is only necessary to have a surface.

  Therefore, in both the transmissive display region T and the reflective display region R, it is possible to regulate the orientation of the liquid crystal molecules, particularly the direction in which the liquid crystal molecules vertically aligned in the initial state fall. As a result, a very wide viewing angle characteristic can be obtained. Specifically, in a reflective display, a contrast of 1:10 or more was obtained with a 120 ° cone, and in a transmissive display, a contrast of 1:10 or more was obtained with a 160 ° cone.

  In the liquid crystal display device of the present embodiment, the thickness of the liquid crystal layer in the transmissive display region T and the thickness of the liquid crystal layer in the reflective display region R are substantially the same. The thickness of the liquid crystal layer in the transmissive display region T is large. As shown in the plan view of FIG. 3A, the opening width (opening area) of the opening 42 formed in the reflective display region R is changed for the openings 41 and 42 formed in the pixel electrode 9. It is configured to be larger than the opening width (opening area) of the opening 41 formed in the display region T. Further, regarding the resin convex portions 43 and 44 provided on the common electrode 31, as shown in the plan view of FIG. 3A, the width of the convex portions 44 formed in the reflective display region R is The width is larger than the width of the convex portion 43 formed in the transmissive display region T.

  Specifically, the opening width of the opening 42 formed in the reflective display region R is about 8 μm and the width of the convex portion 44 is about 12 μm, while the opening width of the opening 41 formed in the transmissive display region T is set. The width is about 5 μm, and the width of the convex portion 43 is about 6 μm. The area occupied by each of the openings and the convex portions, that is, the area occupied in the substrate surface is about 35% in the reflective display area R and about 19% in the transmissive display area T.

  In the regions where the openings 41 and 42 and the convex portions 43 and 44 are formed, it is difficult to apply a voltage to the liquid crystal layer 50, and unless a high voltage is applied, the liquid crystal molecules will not fall down due to the voltage change. . In the present embodiment, the area occupied by the openings and the convex portions in the reflective display region R is made larger than that in the transmissive display region T, so that the liquid crystal molecules in the reflective display region R must be relatively operated. High voltage is required.

  Here, as shown in the prior art, in the transflective liquid crystal display device, there is a problem that the reflectance-voltage characteristic of the reflective display is too steep unless the multi-gap structure is adopted (see FIG. )reference). However, even when the transflective liquid crystal display device does not have the multi-gap structure as in the present embodiment, the area occupied by the openings and / or the convex portions that regulate the alignment of the liquid crystal molecules is reflected. By making the display region R relatively large, the voltage for operating the liquid crystal molecules in the reflective display region R becomes relatively large as described above, and as shown in FIG. I was able to make them almost match.

  Therefore, according to the liquid crystal display device of the present embodiment, in both the transmissive display region T and the reflective display region R, it is possible to regulate the orientation of the liquid crystal molecules, particularly the direction in which the vertically aligned liquid crystal molecules fall in the initial state. Thus, a very wide viewing angle characteristic can be obtained in each region. Furthermore, by using the means (opening and / or convex part) for regulating the alignment of the liquid crystal molecules, the in-plane occupied area was varied in each region, and the electro-optical characteristics of each region were substantially matched. The reflective display and the transmissive display can be driven by the same voltage.

  The widths (occupied areas in a plane) of the convex portions 43 and 44 may be further increased. However, if the widths (opening areas) of the openings 41 and 42 are too large, no matter how much the voltage is increased. In some cases, liquid crystal molecules near the center of the opening do not operate, causing problems such as dark display.

[Second embodiment]
Hereinafter, a second embodiment of the present invention will be described with reference to the drawings.
FIG. 5 shows a plan view and a sectional view of the liquid crystal display device of the second embodiment, and is a schematic diagram corresponding to FIG. 3 of the first embodiment. The basic configuration of the liquid crystal display device of the present embodiment is the same as that of the first embodiment. Openings 41 and 42 are provided in the reflective display region R and the transmissive display region T of the pixel electrode 9, and the reflective display of the common electrode 31 is performed. The convex portions 43 and 44 are provided in the region R and the transmissive display region T. However, in the second embodiment, the point that the insulating film 24 made of resin is not formed in the transmissive display region T, that is, the insulating film 24 having the uneven surface for scattering selectively in the reflective display region R is used. The point formed is different from the first embodiment.

  According to such a configuration, the liquid crystal layer thickness in the transmissive display area is larger than the liquid crystal layer thickness in the reflective display area by 0.7 μm, which is the sum of the thickness of the reflective film 20 of 0.2 μm and the average thickness of the insulating layer 24 of 0.5 μm. Also increases. In order to make the reflectance-voltage characteristics of the reflective display and the transmittance-voltage characteristics of the transmissive display uniform, a difference in the thickness of the liquid crystal layer of about 2 μm is necessary, and about 0.7 μm is insufficient. As in the first embodiment, it is possible to compensate for the insufficiency by increasing the area ratio of the configuration of the opening and / or the convex portion in the reflective display region.

  In the second embodiment, the width of the opening 42 formed in the reflective display region R is about 6 μm, the width of the convex portion 44 is about 10 μm, and the width of the opening 41 formed in the transmissive display region T is about 10 μm. The opening width is about 5 μm, and the width of the convex portion 44 is about 6 μm. In this case, the ratio of the in-plane occupation area of the opening and the convex portion of the reflective display region R is approximately 28%, and the ratio of the in-plane occupation area of the opening and the convex portion of the transmissive display region T is approximately 19%.

  As described above, in the case of the second embodiment, since the difference in the thickness of the liquid crystal layer between the reflective display region R and the transmissive display region T is 0.7 μm, the difference in the area ratio in each region is set to the first embodiment. Even when it is smaller, the electro-optical characteristics of the reflective display region R and the transmissive display region T can be made uniform. Further, a bright transmissive display could be obtained as much as the insulating layer 24 was not present in the transmissive display region T.

[Third Embodiment]
Hereinafter, a third embodiment of the present invention will be described with reference to FIG.
FIG. 6 is a schematic diagram corresponding to FIG. 3 of the first embodiment, showing a plan view and a cross-sectional view of the liquid crystal display device of the third embodiment. In the liquid crystal display device of the present embodiment, the convex portions are not formed in the common electrode (counter electrode) 31 on the counter substrate 25 side, and the openings 45 and 46 are formed in the reflective display region R and the transmissive display region T, respectively. This is different from the first embodiment, and the other configuration is substantially the same as that of the first embodiment. Therefore, in FIG. 6, the same reference numerals are given to the same components as those in FIG. Description is omitted.

  In the present embodiment, the opening width of the opening formed in the pixel electrode 9 is about 7 μm in the reflective display area R and about 5 μm in the transmissive display area T. The opening width is about 7 μm in the reflective display area R and about 5 μm in the transmissive display area T. The opening area ratio of the opening in the reflective display region R is about 25%, and the opening area ratio of the opening in the transmissive display region T is about 18%.

  Also in the liquid crystal display device having the above configuration, the electro-optical characteristics of the reflective display region R and the transmissive display region T can be made uniform. In addition, the liquid crystal display device adopting a simple matrix system in which electrode patterning is required for both the pixel electrode 9 and the common electrode (opposite electrode) 31 and an active matrix system using a TFD (thin film diode) are described in the second embodiment. In the case where the configuration of the second embodiment is adopted, the number of photo steps in the manufacturing process is reduced by one compared with the case where the first embodiment is adopted, so that simple and low cost can be realized. Become.

  Note that the combination of the opening and the convex portion formed in the electrode may be a configuration in which an opening is formed in the common electrode (upper substrate), the convex portion is formed in the pixel electrode (lower substrate), or a combination of the common electrode (upper substrate) and the common electrode (upper substrate). A configuration in which a convex portion is formed on both the pixel electrode (lower substrate), a configuration in which an opening is formed only in the common electrode (upper substrate) or the pixel electrode (lower substrate), a configuration in which the common electrode (upper substrate) or the lower electrode is formed Any of the configurations in which the convex portion is formed only on the substrate) can be adopted.

[Fourth Embodiment]
Hereinafter, a fourth embodiment of the present invention will be described with reference to FIG.
FIG. 7 shows a plan view and a sectional view of the liquid crystal display device of the fourth embodiment, and is a schematic diagram corresponding to FIG. 3 of the first embodiment. In the liquid crystal display device according to the present embodiment, the distance between the adjacent openings and / or convex portions among the openings and / or convex portions formed in the reflective display region R is set to be equal to the size of the opening formed in the transmissive display region R. The distance between adjacent openings and / or convex portions among the portions and / or convex portions was configured to be smaller. That is, the pitch between the openings and the pitch between the convex portions are different between the reflective display region R and the transmissive display region T, and the width of the opening and the width of the convex portion are the same in each region. Since other configurations are substantially the same as those of the first embodiment, the same reference numerals are given to the same components in FIG. 7 as those in FIG. 3 and the detailed description is omitted.

  In the present embodiment, the opening width of the opening formed in the pixel electrode 9 is about 5 μm in both the reflective display region R and the transmissive display region T, and the width of the convex portion formed in the common electrode (opposite electrode) 31 is , The reflective display area R and the transmissive display area T are both about 6 μm. The distance (pitch) between the convex portion 44a formed in the reflective display region R and the adjacent convex portion 44b is about 17 μm, and the convex portion 43a formed in the transmissive display region T is adjacent to the convex portion 43a. The distance (pitch) between the light emitting device and the light emitting device 43b is about 34 μm. The area ratio of the opening and the projection in the reflective display region R is about 38%, and the area ratio of the opening and the projection in the transmission display region T is about 19%.

  Also in the liquid crystal display device having the above configuration, the electro-optical characteristics of the reflective display region R and the transmissive display region T can be made uniform. Further, as in the present embodiment, when the width of the opening or the convex portion is constant, the photo step in the manufacturing process can be simplified.

[Fifth Embodiment]
Hereinafter, a fifth embodiment of the present invention will be described with reference to FIG.
FIG. 8 shows a plan view of the liquid crystal display device of the fifth embodiment, and is a schematic diagram corresponding to FIG. 7A of the fourth embodiment. In the seventh embodiment, the direction in which the liquid crystal molecules fall between the reflective display region R and the transmissive display region T is different. This can cause asymmetry of the viewing angle characteristics. Therefore, in the liquid crystal display device of the present embodiment, as shown in FIG. 8, the shape of the opening and / or the convex portion of each of the display regions R and T in the pixel is made symmetrical, so that the The falling direction could be made substantially the same in each of the display regions R and T. That is, the reflective display region R and the transmissive display region T are divided in the direction in which the opening and / or the convex portion extend in the pixel, and at least the reflective display region R and the transmissive display region T are provided in the extending direction. As a result, the direction in which the liquid crystal molecules fall can be made substantially symmetrical in the left-right direction.

  Here, in this embodiment, only the opening is formed for each of the pixel electrode and the common electrode. That is, in FIG. 8, the opening A is an opening formed on the common electrode side, and the opening B is an opening formed on the pixel electrode side. Further, the pitch of the openings is made different between the transmissive display basin T and the reflective display region R as in the fourth embodiment. As described above, in the case of forming an opening that is likely to cause a problem when the width is increased, it is preferable to adjust the pitch to adjust the area ratio. Since the other configuration is substantially the same as that of the fourth embodiment, the same reference numerals in FIG. 8 denote the same components as in FIG. 7, and a detailed description thereof will be omitted.

  In the present embodiment, the opening width of the opening formed in the pixel electrode 9 is about 5 μm for both the reflective display region R and the transmissive display region T, and the opening width of the opening formed in the common electrode (opposite electrode) 31. The width is about 5 μm for both the reflective display region R and the transmissive display region T. The distance (pitch) between one opening formed in the reflective display region R and the adjacent opening is approximately 17 μm, and the distance (pitch) between the openings formed in the transmissive display region T is approximately 34 μm. is there. The area ratio of the opening in the reflective display region R is about 36%, and the area ratio of the opening in the transmissive display region T is about 18%.

  Also in the liquid crystal display device having the above configuration, the electro-optical characteristics of the reflective display region R and the transmissive display region T can be made uniform. Further, in both the reflective display region R and the transmissive display region T, the viewing angle characteristics symmetrical in the vertical and horizontal directions could be obtained.

[Sixth Embodiment]
Hereinafter, a sixth embodiment of the present invention will be described with reference to FIG.
FIG. 9 shows a plan view and a sectional view of the liquid crystal display device of the sixth embodiment, and is a schematic diagram corresponding to FIG. 3 of the first embodiment. In the liquid crystal display device of the present embodiment, the transmissive display region T is located at the center of the dot (D1, D2, D3), and a resin convex portion 47 is formed at the center, so that the reflective display region R around the dot is formed. A slit-shaped opening 48 was formed in the substrate. Here, the pixel electrode provided in the transmissive display region T and the pixel electrode provided in the reflective display region R are connected by two bridges. Since other configurations are substantially the same as those of the first embodiment, in FIG. 9, the same reference numerals are given to the same components as those in FIG. 3, and the detailed description will be omitted.

  In the present embodiment, the area ratio of the opening 48 in the reflective display region R is about 19%, and the area ratio of the convex portion 47 in the transmissive display region T is about 6%. Also in the liquid crystal display device having the above configuration, the electro-optical characteristics of the reflective display region R and the transmissive display region T can be made uniform. Further, in the case of the present embodiment, the opening 48 is provided in the boundary region between the transmissive display region T and the reflective display region R, which originally have some steps and the alignment is easily disturbed, so that the direction in which the liquid crystal molecules fall can be easily controlled. It also has the advantage of becoming Note that, as shown in FIG. 10, the same effect as that of the present embodiment can also be obtained when the convex portion 57 is formed on the pixel electrode 9 side and the opening 58 is formed on the common electrode 31 side. In FIGS. 9 and 10, the convex portions 47 and 57 have a quadrangular pyramid shape, but may have a predetermined inclined surface such as a conical shape.

[Electronics]
Next, a specific example of an electronic apparatus including the liquid crystal display device according to the above embodiment of the present invention will be described.
FIG. 11 is a perspective view showing an example of a mobile phone. In FIG. 11, reference numeral 1000 denotes a mobile phone main body, and reference numeral 1001 denotes a display unit using the liquid crystal display device. When the liquid crystal display device of the above embodiment is used for a display portion of an electronic device such as a mobile phone, an electronic device including a liquid crystal display portion having a bright, high contrast, and a wide viewing angle regardless of a use environment. Equipment can be realized.

  The technical scope of the present invention is not limited to the above-described embodiment, and various changes can be made without departing from the spirit of the present invention. For example, in the above embodiment, an example in which the present invention is applied to an active matrix type liquid crystal display device using a TFT as a switching element has been described. However, an active matrix type liquid crystal display device using a thin film diode (TFD) switching element, The present invention can also be applied to a passive matrix type liquid crystal display device or the like. In addition, specific descriptions regarding materials, dimensions, shapes, and the like of various components can be appropriately changed.

FIG. 2 is an equivalent circuit diagram of the liquid crystal display device according to the first embodiment of the present invention. FIG. 2 is a plan view showing a structure of a dot of the liquid crystal display device. FIGS. 3A and 3B are a schematic plan view and a schematic cross-sectional view illustrating a main part of the liquid crystal display device. 7 is a graph showing the electro-optical characteristics of the liquid crystal display device. FIGS. 4A and 4B are a schematic plan view and a schematic cross-sectional view illustrating a main part of a liquid crystal display device according to a second embodiment. FIGS. FIGS. 9A and 9B are a schematic plan view and a schematic sectional view illustrating a main part of a liquid crystal display device according to a third embodiment. FIGS. 9A and 9B are a schematic plan view and a schematic cross-sectional view illustrating a main part of a liquid crystal display device according to a fourth embodiment. FIG. 15 is a schematic plan view illustrating a main part of a liquid crystal display device according to a fifth embodiment. 22A and 22B are a schematic plan view and a schematic cross-sectional view illustrating a main part of a liquid crystal display device according to a sixth embodiment. FIG. 10 is a schematic sectional view illustrating a modification of the liquid crystal display device of FIG. 9. FIG. 13 is a perspective view illustrating an example of an electronic apparatus of the invention. 7 is a graph showing electro-optical characteristics of a conventional liquid crystal display device.

Explanation of reference numerals

  Reference numeral 9: pixel electrode, 10: TFT array substrate, 20: reflective film, 22: color filter layer, 25: counter substrate, 31: common electrode, 41, 42: opening, 43, 44: convex portion, 50: liquid crystal Layer, R: reflective display area, T: transmissive display area

Claims (8)

A liquid crystal display device in which a liquid crystal layer is sandwiched between a pair of substrates, and a transmissive display area for performing transmissive display and a reflective display area for performing reflective display are provided in one dot area,
The liquid crystal layer is composed of a liquid crystal having a negative dielectric anisotropy in which an initial alignment state exhibits vertical alignment, and an electrode for driving the liquid crystal is provided on the liquid crystal layer side of the pair of substrates, respectively.
At least one of the electrodes of the pair of substrates has, in each of the transmissive display region and the reflective display region, a part of the electrode opened as an alignment control unit for controlling the alignment of the liquid crystal. A slit-shaped opening formed by forming, and / or a convex portion made of a dielectric formed on the electrode,
Liquid crystal characterized in that an opening area of the slit-shaped opening and / or an area occupied by a dielectric convex in the substrate plane direction is larger in the reflective display area than in the transmissive display area. Display device.   2. The liquid crystal display device according to claim 1, wherein the distance between the electrodes provided on the pair of substrates is substantially the same in the transmissive display area and the reflective display area.   3. The method according to claim 1, wherein the convex portion made of the dielectric is provided on the electrode, and has a slope inclined at a predetermined angle with respect to the electrode surface. 4. Liquid crystal display.   The distance between the adjacent openings and / or the convex portions of the openings and / or the convex portions formed in the reflective display region is the same as the distance between the openings and / or the convex portions formed in the transmissive display region. The liquid crystal display device according to claim 1, wherein the liquid crystal display device is configured to be smaller than a distance between adjacent openings and / or convex portions among the convex portions.   5. The liquid crystal display device according to claim 1, wherein the opening and / or the protrusion have a configuration that regulates a direction in which the vertically aligned liquid crystal molecules fall down based on an electric field change. 6. The liquid crystal display device according to the above.   An upper substrate and a lower substrate are included as the pair of substrates, and a backlight for transmissive display is provided on a side of the lower substrate opposite to the liquid crystal layer, and only the reflective display area is provided on the liquid crystal layer side of the lower substrate. 6. The liquid crystal display device according to claim 1, further comprising a reflection film selectively formed on the liquid crystal display.   7. The liquid crystal display device according to claim 6, wherein a color filter layer is provided on the liquid crystal layer side of the upper substrate or on the liquid crystal layer side of the reflection film.   An electronic apparatus comprising the liquid crystal display device according to claim 1.

Images