JP2005055595A - Liquid crystal display, its driving method, and electronic device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid crystal display wherein display of high luminance, high contrast and a wide visual field angle is obtained in both of transmission display and reflection display without adopting a multi-gap structure, display characteristics of reflection display and transmission display is easily adjusted, and reduction of power consumption is preferably realized. <P>SOLUTION: A liquid crystal display is provided with: a sub dot SD1 for reflection display performing reflection display; and a sub dot SD2 for transmission display performing transmission display, which are obtained by two-dimensionally dividing one dot region. The sub dot SD1 for reflection display is provided with a pixel electrode 9r for reflection display, and a TFT element 30r for reflection display electrically connected to the pixel electrode 9r for reflection display, and the sub dot SD2 for transmission display is provided with a pixel electrode 9t for transmission display, and a TFT element 30t for transmission display electrically connected to the pixel electrode 9t for transmission display. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a liquid crystal display device, a driving method thereof, and an electronic apparatus.

  As a liquid crystal display device, there is a transflective liquid crystal display device that uses external light in a bright place as in a reflective liquid crystal display device, and in a dark place, the display can be visually recognized by a backlight in the same manner as a transmissive liquid crystal display device. Proposed. In such a transflective liquid crystal display device, a liquid crystal layer is sandwiched between an upper substrate and a lower substrate, and a reflective film in which a window for light transmission is formed on a metal film such as aluminum is disposed below. There is known a liquid crystal display device that is provided on the inner surface of a substrate and has the reflective film function 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 reflective film on the inner surface of the lower substrate, and passes through the liquid crystal layer again and is emitted from the upper substrate side to contribute to display. To do. On the other hand, in the transmissive mode, light from the backlight incident from the lower substrate side passes through the liquid crystal layer from the window portion of the reflective film, and then is emitted from the upper substrate side to the outside to contribute to display. Accordingly, of the reflective film formation 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 display 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 limitation that reflection 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 vertically aligned liquid crystal in Non-Patent Document 1 below. The characteristics are the following three.
(1) Employs a “VA (Vertical Alignment) mode” in which a liquid crystal having a negative dielectric anisotropy is aligned perpendicularly to a substrate, and this is defeated by applying a voltage.
(2) A “multi-gap structure” is employed in which the liquid crystal layer thickness (cell gap) is different between the transmissive display area and the reflective display area (refer to, 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 counter substrate so that the liquid crystal is tilted 360 degrees in all directions in this area. In other words, “alignment division structure” is adopted.
Japanese Patent Laid-Open No. 11-242226 JP 2002-350853 A "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)

The multi-gap structure as disclosed in Patent Document 1 is an effective means for aligning the electro-optical characteristics (transmittance-voltage characteristics and reflectivity-voltage characteristics) of the transmissive display area and the reflective display area. This is because light passes through the liquid crystal layer only once in the transmissive display region, whereas light passes through the liquid crystal layer twice in the reflective display region. The liquid crystal display devices disclosed in Patent Document 2 and Non-Patent Document 1 also employ a multi-gap structure.
However, when the multi-gap structure is employed, the following problems occur.
(1) Increase in the number of processes and cost by forming a step for changing the thickness of the liquid crystal layer on the inner surface of the substrate.
(2) Light leakage is likely to occur at step portions between regions having different liquid crystal layer thicknesses, resulting in a decrease in display contrast. In addition, this area may be hidden with a black mask, but in this case, the display becomes dark.
(3) Since the cell gap (liquid crystal layer thickness) of the reflective display area is smaller than the transmissive display area, a difference in response speed occurs between the two areas. Specifically, the response time of the transmissive display area is about four times the response time of the reflective display area.
(4) It is difficult to match the optimum voltage for transmissive display with the optimum voltage for reflective display. That is, it is difficult to adjust the display gradation while obtaining a high contrast display in both the transmissive display and the reflective display.

  The present invention has been made in view of the above-mentioned problems of the prior art, and can achieve high luminance, high contrast, and wide viewing angle display in both transmissive display and reflective display without adopting a multi-gap structure. It is another object of the present invention to provide a liquid crystal display device that can easily adjust the display characteristics of the reflective display and the transmissive display, and that can preferably reduce power consumption.

In order to solve the above-described problems, the present invention provides a liquid crystal display device in which a liquid crystal layer is sandwiched between a pair of substrates, for reflective display in which one dot region is divided in a plane to perform reflective display. A sub-dot and a sub-dot for transmissive display for performing transmissive display are provided, and a reflective display pixel electrode and a reflective display electrically connected to the reflective display pixel electrode are connected to the reflective display sub-dot A transmissive display pixel electrode and a transmissive display switching element electrically connected to the transmissive display pixel electrode. A liquid crystal display device is provided.
According to this configuration, a transflective liquid crystal display that performs reflective display and transmissive display by independently driving the reflective display subdots and the transmissive display subdots provided by dividing the dot area. An apparatus is provided. By adopting such a configuration, since different voltages can be applied to both the sub-dots, the brightness and contrast of the reflective display and the transmissive display with different lengths (retardations) that pass through the liquid crystal layer can be adjusted. Since the voltage can be adjusted by the voltage, a high-luminance and high-contrast display can be obtained in both the reflective display and the transmissive display without adopting the multi-gap structure. And by not providing the multi-gap structure, such as an increase in man-hours, an increase in leakage light due to a stepped portion for varying the liquid crystal layer thickness, and a difference in response speed between reflection display and transmission display, etc. Problems due to the multi-gap structure are eliminated.

  In the liquid crystal display device of the present invention, it is preferable that the liquid crystal layer includes a liquid crystal whose initial alignment is vertical alignment. In other words, a transflective liquid crystal display that has a relatively complicated dot area structure by adopting a reflective / transmissive display method and a vertical alignment mode that enables high-quality black display regardless of the cell gap. In the apparatus, a high-quality display with a wide viewing angle and high contrast can be easily obtained.

In the liquid crystal display device having the above-described configuration, an alignment control means for controlling the alignment direction of the liquid crystal molecules when a voltage is applied is provided in the planar area of the reflective display pixel electrode and / or in the planar area of the transmissive display pixel electrode. It is preferable that
According to this configuration, it becomes possible to appropriately control the tilting direction of the vertical alignment liquid crystal when the voltage is applied by the alignment control means, and rough spots at the time of panel perspective, which is a problem in the vertical alignment mode liquid crystal display device. Display defects such as unevenness of the shape can be effectively prevented, and display with a wide viewing angle and high contrast becomes possible.

In the liquid crystal display device of the present invention, at least one of the reflective display pixel electrode and the transmissive display pixel electrode includes a plurality of island-shaped portions and a connection for electrically connecting the plurality of island-shaped portions. It can be set as the structure which has a part.
In this way, the pixel electrode is divided into a plurality of island-shaped portions, so that the orientation direction of the liquid crystal molecules in the planar region of the island-shaped portion is changed by the oblique electric field generated at the peripheral edge of the island-shaped portion when a voltage is applied. The direction toward the center of the shape portion can be taken. Thereby, liquid crystal domains having different alignment states can be formed for each island-shaped portion, and a display with a wide viewing angle can be obtained. In addition, since the boundary of the liquid crystal domain is fixed to the side edge of the island-shaped portion, a high-quality display can be obtained without causing spot-like unevenness when the panel is viewed.

  In the liquid crystal display device having the above-described configuration, it is preferable that the orientation control means is disposed at a substantially central portion of the island-like portion in plan view. According to this configuration, in the planar region of the island-shaped portion, a liquid crystal domain that exhibits a substantially radial alignment state in plan view with the alignment control means as the center can be formed, and a wide viewing angle having uniform viewing angle characteristics in all directions Can be obtained.

In the liquid crystal display device of the present invention, it is preferable that the liquid crystal capacity of the reflective display sub-dot and the liquid crystal capacity of the transmissive display sub-dot are substantially equal.
With such a configuration, it is possible to effectively prevent problems such as crosstalk between the two sub-dots.

In the liquid crystal display device of the present invention, the switching element is a two-terminal nonlinear element, and the ratio of the liquid crystal capacity of the reflective display subdot to the element capacity of the reflective display switching element is the transmission display subdot. The liquid crystal capacitance can be made substantially equal to the ratio of the capacitance of the transmissive display switching element.
With such a configuration, the effective voltage drop due to push-down during writing that occurs when a two-terminal nonlinear element is used can be made uniform for both sub-dots. A difference in brightness and contrast can be prevented.

In the liquid crystal display device of the present invention, an illuminating unit that supplies illumination light to the transmissive display sub-dots is provided, and the reflective display sub-dots and / or transmissive display units are linked to the lighting state of the illuminating unit The driving state of the subdots can be changed.
With such a configuration, it becomes possible to drive the sub-dots in an appropriate form in each of the lighting unit on / off state, that is, the reflective display state and the transmissive display state.

In the liquid crystal display device of the present invention, when the illuminating means is turned off, the transmissive display sub-dots can be in a drive stop state.
According to this configuration, in the reflective display state in which the illumination unit is turned off and the reflective display subdot is the main display area, driving of the transmissive display subdot that contributes little to the display is stopped. Power can be significantly reduced, and a liquid crystal display device suitable for use in portable electronic devices can be provided.

The liquid crystal display device of the present invention further includes image processing means for performing predetermined image processing on the input image signal and outputting the image signal to each of the sub-dots, and the image processing means includes the reflective display sub-dots. On the other hand, an image signal subjected to signal processing for enhancing the display contrast can be output.
Conventionally, in a transflective liquid crystal display device, there has been a problem that a reflective display lacks a contrast feeling and looks dark compared to a transmissive display. Therefore, in this configuration, by utilizing the fact that the reflective display sub-dots and the transmissive display sub-dots can be driven independently, image processing for enhancing contrast with respect to the image signal input to the reflective display sub-dots is performed. Like to do. As a result, a clear and bright reflective display can be obtained.

In the liquid crystal display device of the present invention, the image signal output from the image processing means to the reflective display sub-dot is an image signal obtained by converting the input image signal into a binary gradation value. can do.
Alternatively, in the liquid crystal display device of the present invention, the image signal output from the image processing unit to the reflective display sub-dot is subjected to signal processing for increasing the gain in the intermediate gradation region of the input image signal. It can be set as the structure which is the image signal made.
According to these configurations, the contrast of the reflective display sub-dots can be enhanced, and a clear and bright reflective display can be obtained. In particular, when the reflective display is a binary gradation display, the gradation of the reflective display is crushed, but the maximum contrast is obtained in the reflective display regardless of the display content, so that the sub-dot for transmissive display is the main display area. When used, it is effective for assisting the display of transmissive display sub-dots.

In the liquid crystal display device of the present invention, when the illuminating unit is turned on, the image processing unit outputs an image signal subjected to signal processing for enhancing the contrast with respect to the reflective display sub-dot. It can be.
In the liquid crystal display device in which the illumination unit is turned on and in the transmissive display state, the transmissive display subdot is the main display area, and therefore, the gradation of the image signal is accurately reproduced for the reflective display subdot. There is no need. Therefore, in this configuration, the contrast of the transmissive display is improved by enhancing the contrast of the reflective display and assisting the display of the transmissive display sub-dots. Therefore, according to this configuration, a higher quality transmissive display can be obtained.

  Next, the present invention is the above-described method for driving a liquid crystal display device according to the present invention, wherein the transmissive display sub-dot and the reflective display sub-dot can obtain the maximum luminance with each sub-dot. A driving method of a liquid crystal display device, characterized in that driving is performed in different voltage ranges. According to this driving method, a bright and high-contrast display can be obtained in both the reflective display and the transmissive display.

  In the driving method of the liquid crystal display device of the present invention, the reflective display sub-dots can be displayed in gradation with enhanced contrast. According to this driving method, it is possible to solve the problem of the transflective liquid crystal display device in which the reflective display lacks contrast and looks dark compared to the transmissive display, and a bright and clear reflective display can be obtained. it can.

In the driving method of the liquid crystal display device of the present invention, binary gradation display can be performed in the reflective display sub-dots. In the liquid crystal display device driving method of the present invention, gradation correction for increasing the gain in the intermediate gradation region can be performed in the reflective display sub-dots.
By adopting these driving methods, it is possible to improve the contrast and brightness of the reflective display, and when the reflective display subdot is used as an auxiliary to the transmissive display subdot in the transmissive display state, There is also an effect that the contrast can be improved.

In the driving method of the liquid crystal display device of the present invention, the reflective display subdots and / or the transmissive display subdots are linked with the lighting state of the illumination means for supplying illumination light to the transmissive display subdots. The driving state can be changed.
According to this driving method, it is possible to display both the transmissive display sub-dots and the reflective display sub-dots in an appropriate drive state in each of the lighting means on / off states, and the reflective display and the transmissive display. Display quality can be further improved.

  In the driving method of the liquid crystal display device of the present invention, when the illumination unit is turned off, the driving of the transmissive display sub-dots can be stopped. According to this driving method, in the liquid crystal display device in the reflective display state, the display of the transmissive display subdots that hardly contribute to the display is stopped, so that the number of subdots to be driven can be halved. Power consumption can be significantly reduced.

  In the driving method of the liquid crystal display device of the present invention, when the illumination unit is turned on, the reflective display sub-dots can be displayed in a gradation with enhanced contrast. According to this configuration, in the liquid crystal display device in the transmissive display state, the function of assisting the transmissive display sub-dot by causing the display to emphasize the contrast for the reflective display sub-dot that does not form the main display region. Thus, the contrast of transmissive display can be improved.

  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 capable of obtaining reflective display and transmissive display with high brightness, high contrast, and wide viewing angle is provided.

  Hereinafter, embodiments of the present invention will be described 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. 2A is a plan configuration diagram showing one pixel region, and FIG. It is a section lineblock diagram which meets an AA 'line of a). The liquid crystal display device shown in these drawings is an active matrix color liquid crystal display device including a TFT (thin film transistor) 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.

As shown in FIG. 1, the liquid crystal display device 100 according to the present embodiment includes a plurality of dot regions D arranged in a matrix in plan view, a data line driving circuit 201, and a scanning line driving circuit 204. A plurality of data lines 6a... Extended from these drive circuits and scanning lines 3r. Each dot region D is divided into two subdots SD1 and SD2, and the subdot SD1 includes a TFT element 30r and a liquid crystal display element 50r connected to the drain of the TFT element 30r. Is configured to include a TFT element 30t and a liquid crystal display element 50t connected to the drain of the TFT element 30t.
The data lines 6a extending from the data line driving circuit 201 are connected to the sources of the TFT elements 30r and 30t, and the scanning lines 3r and 3t extending from the scanning line driving circuit 204 are connected to the gates of the TFT elements 30r and 30t, respectively. ing.

  Next, a pixel configuration of the liquid crystal display device 100 of the present embodiment will be described with reference to FIG. As shown in FIG. 2, in the liquid crystal display device 100 of the present embodiment, a plane surrounded by scanning lines 30r and 30t extending in parallel with each other and data lines 6a extending so as to intersect these scanning lines. The rectangular area is a dot area D1 to D3, one color filter of the three primary colors is formed corresponding to one dot area, and the three color filters 22B, A pixel region including 22G and 22R is formed.

  The dot areas D1 to D3 are composed of two sub dots SD1 and SD2 arranged in the extending direction of the data line 6a. The subdot SD1 includes a reflective display pixel electrode 9r made of a metal thin film such as aluminum or silver, and a TFT element 30r connected to the reflective display pixel electrode 9r, the scanning line 3r, and the data line 6a. The sub-dot SD2 includes a transmissive display pixel electrode 9t having an octagonal shape in plan view made of a transparent conductive film such as ITO (indium tin oxide), a transmissive display pixel electrode 9t, The sub-dot for transmissive display includes the scanning line 3t and the TFT element 30t connected to the data line 6a. In the present embodiment, the reflective display pixel electrode 9r and the transmissive display pixel electrode 9t have substantially the same shape and size in plan view.

Here, FIG. 3 is an enlarged plan view showing the TFT element 30r provided in the sub dot SD1. As shown in the figure, the TFT element 30r includes a semiconductor layer 33, a gate electrode portion 32r provided on the lower layer side (substrate body 10A side) of the semiconductor layer 33, and an upper layer side (liquid crystal layer 50 side) of the semiconductor layer 33. ) Provided with a source electrode portion 34 and a drain electrode portion 37. A channel region 33c is formed in a region of the semiconductor layer 33 facing the gate electrode portion 32r, and a source region 33s and a drain region 33d are formed on both sides of the channel region 33c.
The gate electrode portion 32r is formed by extending a part of the scanning line 3r in the extending direction of the data line 6a, and is opposed to the channel region 33c of the semiconductor layer 33 through an insulating film (not shown) on the tip side. ing. The source electrode portion 34 is formed by extending a part of the data line 6 a in the extending direction of the scanning line 3 r and is electrically connected to the source region 33 s of the semiconductor layer 33 through the source contact hole 35. . The drain electrode 37 is electrically connected to the drain region 33d of the semiconductor layer 33 through the drain contact hole 36 on one end side, and the other end side is omitted in FIG. 3, but the reflection shown in FIG. It is electrically connected to the display pixel electrode 9r directly or through a contact hole. Then, the TFT element 30r is turned on for a predetermined period by a gate signal input via the scanning line 3r, whereby an image signal supplied via the data line 6a is supplied to the liquid crystal at a predetermined timing. To write.
Although not shown, the TFT element 30t provided in the sub-dot SD2 for transmissive display also has the same configuration as the TFT element 30r shown in FIG.

  On the other hand, when the cross-sectional structure shown in FIG. 2B is seen, the liquid crystal display device 100 includes an element substrate 10 and a counter substrate 25 disposed so as to face the element substrate 10, and the initial alignment state is between the substrates 10 and 25. A liquid crystal layer 50 having a vertical alignment, that is, a liquid crystal having negative dielectric anisotropy is sandwiched. The liquid crystal layer 50 is formed with a substantially constant layer thickness within the dot region D3 as shown in the figure, and is a “multi-gap structure” like the transflective liquid crystal display device described in Patent Documents 1 and 2 above. It is not. A backlight (illuminating means) 15 that is a light source for transmissive display is disposed on the outer surface side of the element substrate 10. As described above, the liquid crystal display device of the present embodiment is a vertical alignment mode liquid crystal display device including the vertical alignment type liquid crystal layer 50, and can perform reflection display by the subdot SD1 and transmission display by the subdot SD2. This is a transflective liquid crystal display device.

  The element substrate 10 is provided with a light-transmitting insulating film 24 on the surface of a substrate body 10A made of a light-transmitting material such as quartz or glass, and on the lower layer side (substrate body 10A side) of the insulating film 24. TFT elements 30r and 30t are formed (in FIG. 2B, only the scanning lines 3r and 3t are shown). The surface of the insulating film 24 is partially provided with a concavo-convex shape 24a, and a reflective display pixel electrode 9r is provided in the concavo-convex shape forming region. Accordingly, the reflective display pixel electrode 9r has a concavo-convex surface following the concavo-convex shape 24a, and is provided with light scattering properties so as to prevent reflection from the outside and enlarge the viewing angle. Yes. On the other hand, the transmissive display pixel electrode 9 t is formed on the flat surface of the insulating film 24.

Although not shown, a vertical alignment film such as polyimide is formed so as to cover the reflective display pixel electrode 9r and the transmissive display pixel electrode 9t, and the initial alignment control of the liquid crystal layer 50 is performed. Yes. In the case of this embodiment, the vertical alignment film does not need to be subjected to an alignment process such as a rubbing process.
In the present embodiment, the case where the reflective display pixel electrode 9r made of a metal reflective film is formed has been described. However, the reflective display pixel electrode 9r may be made of a transparent conductive film such as ITO. In this case, a metal reflective film may be formed immediately below the pixel electrode made of a transparent conductive film or on the lower layer side through an insulating film.

On the other hand, the counter substrate 25 has a color filter 22R (color filters 22B and 22G in the dot regions D1 and D2 respectively) and an acrylic resin on the surface of the substrate body 25A made of a translucent material such as glass or quartz. And the like, and a flat solid common electrode 31 made of a transparent conductive film such as ITO is sequentially laminated. In addition, an octagonal pyramid-shaped dielectric protrusion (orientation control means) 31r made of an insulating material is provided on the common electrode 31 at substantially the same position as the plane center of the reflective display pixel electrode 9r in plan view. An octagonal pyramidal dielectric protrusion (orientation control means) 31t made of an insulating material is provided on the common electrode 31 at substantially the same position as the plane center of the pixel electrode 9t in plan view.
As the shapes of the dielectric protrusions 31r and 31t, in addition to the polygonal pyramid shape including the octagonal pyramid shape shown in FIG. 2, shapes such as a conical shape and a hemispherical shape can be applied, and instead of the dielectric protrusions 31r and 31t, An opening in which a part of the common electrode 31 is cut out may be provided and used as orientation control means (see, for example, FIG. 6).
A vertical alignment film (not shown) is formed so as to cover the common electrode 31 and the dielectric protrusions 31r and 31. The vertical alignment film can have the same configuration as the vertical alignment film provided on the element substrate 10 described above.

The color filters 22R, 22G, and 22B are provided with opening regions 22r, 22g, and 22b that are located in the plane region of the reflective display sub-dot SD1, with the respective color filters partially cut away. In the case of the present embodiment, the opening regions 22r, 22g, and 22b are formed in a circular shape in plan view at positions concentric with the dielectric protrusions 31r of the corresponding dot regions D1 to D3. By providing these opening regions 22r, 22g, and 22b, the chromaticity of the transmissive display subdot SD2 can be harmonized, and the brightness of the reflective display subdot SD1 can be improved. It is possible to obtain a high-quality display in which luminance and chromaticity are balanced in both displays.
Further, the sizes (diameters) of the opening regions 22r, 22g, and 22b differ depending on the color types of the color filters 22R, 22G, and 22B. Specifically, the opening of the green color filter 22G having high visibility is provided. The region 22g is relatively large, and the opening region 22b of the blue color filter 22B having low visibility is formed to be relatively small.

A circularly polarizing plate is provided on the outer surface side of the lower substrate 10 by laminating a retardation plate 18 and a polarizing plate 19 from the substrate body 10A side. 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. 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. By adopting such a configuration, the transmittance in the dot region does not become non-uniform depending on the orientation direction of the liquid crystal molecules at the time of voltage application as in the case where linearly polarized light is incident on the liquid crystal layer 50. It is possible to substantially improve the aperture ratio of the dot region, thereby improving the display brightness of the liquid crystal display device.
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.

  The transflective liquid crystal display device 100 of the present embodiment having the above-described configuration is provided with a sub-dot SD1 for reflection display and a sub-dot SD2 for transmission display by dividing the dot regions D1 to D3, respectively. The sub-dots SD1 and SD2 are independently driven by the TFT elements 30r and 30t to perform reflective display and transmissive display. With such a configuration, it is possible to apply different voltages to the reflective display pixel electrode 9r and the transmissive display pixel electrode 9t, and to optimize contrast and brightness in both the reflective display and the transmissive display. Can be easily performed.

  In the case of the present embodiment, the liquid crystal layer 50 of the liquid crystal display device 100 has substantially the same layer thickness for the reflective display subdot SD1 and the transmissive display subdot SD2, so each of the subdots SD1 and SD2 The electro-optical characteristics draw different curves as shown in the graph of FIG. In the transmissive display subdot SD2, the display light is light that has been transmitted through the liquid crystal layer 50 once, whereas in the reflective display subdot SD1, light that has been transmitted through the liquid crystal layer 50 twice is used for display. Because it is. In FIG. 4, the curve indicated by the broken line is the RV characteristic (reflectance-voltage characteristic) of the reflective display subdot SD1, and the curve indicated by the solid line is the TV of the transmissive display subdot SD2. It is a characteristic (transmittance-voltage characteristic).

  In the conventional transflective liquid crystal display device, the voltage applied to the pixel electrode is uniform within the dot region. Therefore, unless a multi-gap structure is employed, the electro-optical characteristics in the reflective display region and the electrical property in the transmissive display region are The optical characteristics could not be matched. On the other hand, in the liquid crystal display device 100 of the present embodiment, for example, as shown by the “+” mark in FIG. 4, the voltage applied to the reflective display pixel electrode 9 r when the same gradation display is performed. Since the voltage applied to the transmissive display pixel electrode 9t can be made different, the display gradation in the dot region D can be easily aligned between the reflective display subdot SD1 and the transmissive display subdot SD2. Can do. In particular, since a region where gradation inversion occurs in reflective display is not used for display, an effect of lowering contrast between both sub-dots does not occur, and a high-contrast display can be obtained. In addition, a voltage value at which the maximum luminance can be obtained in each of the sub dots SD1 and SD2 can be used for display, and a high luminance display can be obtained.

Further, as described above, since the liquid crystal display device 100 of the present embodiment is configured not to include the multi-gap structure, the problems caused by the adoption of the multi-gap structure described above (man-hours due to formation of multi-gap steps) Of course, it is possible to eliminate an increase in light, light leakage at a stepped portion, and a response speed difference between reflection display and transmission display.
In particular, since the liquid crystal display device of this embodiment uses vertically aligned liquid crystal for the liquid crystal layer 50, the liquid crystal display device is always black when no voltage is applied regardless of the subdots SD1 and SD2 and regardless of the cell gap (liquid crystal layer thickness). Can be displayed. This has an advantage that a high-contrast display can be obtained in both the transmissive display and the reflective display very easily as compared with liquid crystal display devices in other liquid crystal display modes (for example, TN mode).

In addition, the liquid crystal display device 100 according to the present embodiment can appropriately control the alignment state of the vertical alignment mode liquid crystal layer 50 when a voltage is applied to obtain a wide viewing angle and high contrast display. This is because the pixel electrodes 9r and 9t have an octagonal shape in plan view and the dielectric protrusions 31r and 31t are provided to face the pixel electrodes 9r and 9t.
When no electric field is applied between the pixel electrodes 9r and 9t and the common 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 between the pixel electrodes 9r and 9t and the common electrode 31, the liquid crystal molecules arranged in the planar region of the pixel electrodes 9r and 9t are at the side edges of the pixel electrodes 9r and 9t. As a result of the oblique electric field generated in this manner, the liquid crystal molecules fall in a direction perpendicular to the side edges and the surface direction, and the liquid crystal molecules around them also fall in the same direction so as to be aligned with the tilt direction. As a result, the liquid crystal molecules fall from the peripheral ends of the pixel electrodes 9r and 9t toward the center of the electrodes. In addition, on the dielectric protrusions 31r and 31t provided at the same position as the plan view of the center of the pixel electrodes 9r and 9t, when no voltage is applied, the vertical alignment film provided on the surfaces of the dielectric protrusions 31r and 31t Liquid crystal molecules are aligned perpendicular to the surface of the body protrusions, that is, inclined with respect to the substrate surface. When a voltage is applied, the liquid crystal molecules on the dielectric protrusions fall in the tilt direction, so the surrounding liquid crystal molecules also fall in the same direction. As a result, the liquid crystal molecules are aligned substantially radially in plan view with the dielectric protrusions 31r and 31t as the center.
In this manner, liquid crystal domains having a substantially radial alignment state in plan view around the dielectric protrusions 31r and 31t are formed in the respective planar regions of the pixel electrodes 9r and 9t when a voltage is applied. Each liquid crystal domain can obtain uniform viewing angle characteristics in all directions, and the boundary between the liquid crystal domains is fixed at the boundary between the pixel electrodes 9r and 9t. A high-quality display can be obtained without causing rough and uneven spots even when viewed obliquely.

  In the case of the present embodiment, the orientation state of the liquid crystal when a voltage is applied is determined by both the octagonal pixel electrodes 9r and 9t in plan view and the dielectric protrusions 31r and 31t provided corresponding to the pixel electrodes 9r and 9t. Since the control is performed, the alignment of the liquid crystal can be appropriately controlled even when the plane areas of the pixel electrodes 9r and 9t are relatively large. Specifically, even if the pixel electrodes 9r and 9t having a size of about 40 to 50 μmφ are formed, there is an advantage that the alignment can be stabilized and a bright display can be obtained by maintaining a high aperture ratio.

  Furthermore, in this embodiment, since the liquid crystal capacities of the reflective display subdot SD1 and the transmissive display subdot SD2 are substantially equal, problems such as crosstalk between the subdots SD1 and SD2 may occur. Absent. In particular, when a TFD (Thin Film Diode) element is used as the switching element instead of the TFT element used as the switching element of the subdots SD1 and SD2 in this embodiment, the capacitance between the element and the liquid crystal at the time of writing Since pushdown (a phenomenon in which a substantial writing voltage is attenuated by capacitive coupling) occurs depending on the ratio, it is effective to align the liquid crystal capacitances of the subdots SD1 and SD2.

In the present embodiment, the planar shape of the pixel electrodes 9r and 9t is an octagonal shape, but is not limited to this shape, and any of a circular shape, an elliptical shape, a polygonal shape, and the like can be applied. That is, as the pixel electrodes 9r and 9t, any shape can be suitably used as long as it can form a liquid crystal domain that takes a substantially radial alignment state when a voltage is applied in the planar region.
Furthermore, in the present embodiment, the liquid crystal alignment state at the time of electric field application is controlled by an oblique electric field generated at the side edges of the pixel electrodes 9r and 9t. However, the alignment control means such as dielectric protrusions and electrode openings is used. When the orientation state of the liquid crystal in the dot region is controlled, the planar shape of the pixel electrodes 9r and 9t does not necessarily have to be the above-mentioned shape.

(Second Embodiment)
Next, a liquid crystal display device according to a second embodiment will be described with reference to the drawings. FIG. 5 is a circuit configuration diagram of the liquid crystal display device 200 of the present embodiment. FIG. 6A is a plan configuration diagram showing one pixel region, and FIG. 6B is a diagram shown in FIG. It is a section lineblock diagram which meets a BB 'line. The liquid crystal display device 200 is an active matrix color liquid crystal display device using a TFD element (two-terminal nonlinear element) as a switching element. In the following, in FIG. 5 and FIG. 6, the constituent elements to which the same reference numerals as those in FIG. 1 to FIG.

As shown in FIG. 5, the liquid crystal display device 200 including the scanning line driving circuit 110 and the data line driving circuit 120 includes signal lines, that is, a plurality of scanning lines 13 and a plurality of data lines intersecting with the scanning lines 13. 19r and 19t are provided, the scanning line 13 is driven by the scanning line driving circuit 110, and the data lines 19r and 19t are driven by the data line driving circuit 120. In each dot region D, the TFD element 40r and the liquid crystal display element 160r (liquid crystal layer) are connected in series between the scanning line 13 and the data line 19r, and between the scanning line 13 and the data line 19t, The TFD element 40t and the liquid crystal display element 160t are connected in series. That is, each dot region D includes a sub dot SD1 having a TFD element 40r and a liquid crystal display element 160r, and a sub dot SD2 having a TFD element 40t and a liquid crystal display element 160t.
In FIG. 5, the TFD elements 40r and 40t are connected to the scanning line 13 side, and the liquid crystal display elements 160r and 160t are connected to the data lines 19r and 19t, but conversely, the TFD elements 40r and 40t are connected. May be provided on the data lines 19r and 19t side, and the liquid crystal display elements 160r and 160t may be provided on the scanning line 13 side.
In FIG. 5, the data lines 19r and 19t are both taken out upward and connected to the same data line driving circuit, but the data line 19r group is taken out upward and the data line 19t group is taken out downward and separated. It is more convenient to apply different voltages to the data line driving circuits.

  Next, the pixel configuration will be described with reference to FIG. As shown in FIG. 6A, in the liquid crystal display device 200 of the present embodiment, the plane area of each of the data lines 19r and 19t partitioned by the scanning lines 13 extending in the horizontal direction in the figure is a dot area. D1 to D3, and one color filter of the three primary colors is formed corresponding to one dot area, and the three dot areas D1 to D3 include three color filters 22R, 22G, and 22B. An area is formed.

As shown in FIG. 5, each dot area D of the liquid crystal display device 200 is divided into two subdots SD1 and SD2. In the dot areas D1 to D3 shown in FIG. 19r and 19t extend, and in each dot area, a sub-dot SD1 is provided in the formation area of the data line 19r, and a sub-dot SD2 is provided in the formation area of the other data line 19t. The sub-dot SD1 is provided with a reflective display pixel electrode 131r connected to the scanning line 13 via the TFD element 40r and a reflective film 20. The sub dot SD2 is provided with a transmissive display pixel electrode 131t connected to the scanning line 13 via the TFD element 40t. Accordingly, in the liquid crystal display device 200, the sub dot SD1 is a reflective display sub dot, and the sub dot SD2 is a transmissive display sub dot.
Here, the TFD elements 40r and 40t are switching elements that connect the scanning line 13 and the pixel electrodes 131r and 131t. For example, the TFD elements 40r and 40t are formed on the surface of the first conductive film mainly composed of Ta, the first conductive film, the insulating film mainly composed of Ta ₂ O ₃ , and the surface of the insulating film. And an MIM structure including a second conductive film containing Cr as a main component. The first conductive films of the TFD elements 40r and 40t are connected to the scanning line 13, and the second conductive film is connected to the pixel electrodes 131r and 131t, respectively.

  The reflective display pixel electrode 131r provided in the reflective display sub-dot SD1 has a regular octagonal shape in plan view. The transmissive display pixel electrode 131t provided in the transmissive display subdot SD2 includes two island-like portions 131a and 131b having a regular octagonal shape in plan view arranged in the extending direction of the scanning line 13, and these island-like portions. In order to electrically connect 131a and 131b, a connecting portion 131c extending from both island portions 131a and 131b is provided, and the island portion 131a and the TFD element 40t are connected. The reflective display pixel electrode 131r and the island portions 131a and 131b have substantially the same shape and size in plan view, and the transmissive display subdot SD2 The planar area is approximately twice that of the dot SD1.

On the other hand, when viewing the cross-sectional structure shown in FIG. 6B, the liquid crystal display device 200 has a configuration in which a liquid crystal layer 50 is sandwiched between an upper substrate 225 and a lower substrate 210 disposed opposite thereto. On the outer side (back side) of the lower substrate 210, a backlight (illuminating means) that constitutes a light source for transmissive display is disposed. Also in this embodiment, the liquid crystal layer 50 is formed with a substantially constant layer thickness within the dot region D3 as shown in the figure, and is similar to the transflective liquid crystal display device described in the above-mentioned Patent Documents 1 and 2. It is not a “multi-gap structure”.
As described above, the liquid crystal display device 200 of the present embodiment is a vertical alignment mode liquid crystal display device including the vertical alignment type liquid crystal layer 50, and includes a reflective display by the subdot SD1 and a transmissive display by the subdot SD2. This is a transflective liquid crystal display device that can be used.

On the lower substrate 210, a reflective film 20 made of a highly reflective metal film such as aluminum or silver is partially formed through an insulating film 24 on the surface of a substrate body 10 A made of a light-transmitting material such as quartz or glass. Has been. A reflective display sub-dot SD1 is provided in a region where the reflective film 20 is formed.
The insulating film 24 formed on the substrate main body 10A is provided with a concavo-convex shape in a partial region of its surface, and the surface of the reflective film 20 has a concavo-convex portion following the concavo-convex shape. Since the reflected light is scattered by such unevenness, reflection from the outside is prevented and good visibility can be obtained.

A rectangular red color filter 22R straddling the reflective display subdot SD1 and the transmissive display subdot SD2 is provided on the reflective film 20 and the insulating film 24 in the dot region. In plan view, as shown in FIG. 6A, 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 formed on the color filter 22R, and the insulating film 26 flattens the uneven shape due to the reflective film 20 and the color filter 22R.
On the surface of the insulating film 26, data lines 19r and 19t made of a transparent conductive material such as ITO are formed in a stripe shape in plan view extending in the direction perpendicular to the paper surface, and are arranged in parallel in the direction perpendicular to the paper surface. It functions as a common electrode for each of the subdots SD1 and SD2 of the plurality of dot regions D1 to D3. Further, the data line 19r is formed with an opening 19ra having an octagonal shape in plan view with a part cut away corresponding to each dot region, and the data line 19t corresponding to each dot region. Openings 19ta and 19tb having an octagonal shape in plan view with a part thereof cut away are formed. As shown in FIG. 6A, the openings 19ra, 19ta, and 19tb are provided corresponding to the island-shaped portions 131a and 131b of the reflective display pixel electrode 131r and the transmissive display pixel electrode 131t, respectively. The electrode 131r and the island-shaped portions 131a and 131b are disposed at substantially the center of the planar area.

Although not shown, a vertical alignment film made of polyimide or the like is formed so as to cover the data lines 19r and 19t. This vertical alignment film is an alignment film that aligns liquid crystal molecules perpendicularly to the film surface. In this embodiment, it is preferable to use a film that has not been subjected to alignment treatment such as rubbing.
Further, in the present embodiment, the reflective film 20 and the data line 19r that constitutes the electrode of the reflective display subdot SD1 are separately provided and laminated. However, by forming the data line 19r from a metal material, It can also be set as the electrode which has the function of a reflecting film.

  Next, on the upper substrate 225 side, the liquid crystal layer 50 side of the substrate body 25A made of a translucent material such as glass or quartz is made of a transparent conductive material such as ITO, and the planar shape shown in FIG. The pixel electrodes 131r and 131t are formed, and the TFD elements 40r and 40t provided corresponding to the pixel electrodes 131r and 131t, respectively, and the scanning line 13 are provided. Although not shown, a vertical alignment film made of polyimide or the like is provided so as to cover the pixel electrodes 131r and 131t.

The liquid crystal display device 200 of the present embodiment having the above-described configuration is provided with a reflective display subdot SD1 and a transmissive display subdot SD2 by dividing the dot regions D1 to D3, respectively. Is independently driven by the TFD elements 40r and 40t to perform reflective display and transmissive display, so that contrast and luminance can be easily optimized in both reflective display and transmissive display.
In addition, as described above, the liquid crystal display device 200 of the present embodiment is also configured not to have a multi-gap structure, and thus has problems that arise with the adoption of the multi-gap structure described above (man-hours due to the formation of multi-gap steps). Of course, it is possible to eliminate an increase in light, light leakage at a stepped portion, and a response speed difference between reflection display and transmission display.

  In the present embodiment, the cell gaps of the reflective display subdot SD1 and the transmissive display subdot SD2 are substantially equal, and the electrode area of the transmissive display subdot SD2 is twice as large. The capacity is twice that of the reflective display sub-dot SD1. As described above, when the TFD element is used as the switching element, if the liquid crystal capacity of the dots is different, the substantial write voltage varies depending on the push-down that occurs at the time of writing depending on the ratio of the TFD element and the liquid crystal capacity. End up. In the liquid crystal display device 200 of the present embodiment, when the TFD elements 40r and 40t are equal, the substantial voltage applied to the transmissive display pixel electrode 131t is higher. Therefore, as in the present embodiment, when a dot configuration that prioritizes transmissive display is used, a method of driving by applying equal voltages to the TFD elements 40r and 40t and applying a high voltage to the TFD elements 40r is employed. Alternatively, the TFD elements 40r and 40t may be manufactured by setting the element area (element capacity) of the TFD element 40t to about twice that of the TFD element 40r.

  Also in the liquid crystal display device 200, as in the previous liquid crystal display device 100, the alignment state of the liquid crystal layer 50 in the vertical alignment mode when a voltage is applied can be appropriately controlled. In the reflective display sub-dot SD1, the pixel electrode 131r has a regular octagonal shape in plan view, and the opening 19ra is arranged at the center of the pixel electrode 131r, so that the edge of the pixel electrode 131r and the peripheral edge of the opening 19ra Due to the oblique electric field, a liquid crystal domain exhibiting a substantially radial alignment state in plan view with the opening 19ra at the center when an electric field is applied can be formed in the planar region of the pixel electrode 131r, thereby causing rough spot-like unevenness. Therefore, it is possible to perform reflective display with high image quality and uniform viewing angle characteristics in all directions.

  Further, in the transmissive display sub-dot SD2, the two island-like portions 131a and 131b have a regular octagonal shape in plan view, and the openings 19ta and 19tb are arranged at the center positions of the two island-like portions 131a and 131b. Since the liquid crystal domains similar to the reflective display subdot SD1 can be formed in the respective planar regions of the island portions 131a and 131b, the boundary is fixed and the liquid crystal alignment state is substantially radial in plan view. With the two liquid crystal domains, it is possible to obtain a transmissive display with high image quality and uniform viewing angle characteristics in all directions without causing rough spotted unevenness.

(Third embodiment)
In the transflective liquid crystal display device according to the present invention, taking advantage of the fact that the reflective display subdot SD1 and the transmissive display subdot SD2 can be driven independently, for example, the reflective display subdot SD1 and the transmissive display subdot SD1 are transmitted. It is also possible to display the display sub-dots SD2 with different display gradations. For example, since the reflective display lacks contrast and looks darker than the transmissive display, the display method of the reflective display sub-dot SD1 is a display method that emphasizes the contrast, thereby providing a bright and clear reflection. Display can be obtained.
When the above driving method is applied, an image signal that has been subjected to signal processing that enhances the contrast of the image signal output from the data line driving circuit 201 to the reflective display sub-dot SD1 may be transmitted.
If emphasizing signal processing one example the contrast, the provision of an image processing unit for converting the input signal along the input-output curve gamma _a, as shown by the solid line to the output tone in FIGS. 7 (a) Can be realized. In the input / output curve γa shown in FIG. _7A , the gain of the intermediate gradation region is increased with respect to the input / output curve γ ₀ (input / output curve without gradation correction) indicated by a dotted line in FIG. Therefore, the gain of the gradation region on the low luminance side and the high luminance side is reduced so as to match it, and the display contrast can be further enhanced.

Further, in the liquid crystal display device 100 according to the present invention, the drive mode of the reflective display sub-dot SD1 can be changed in conjunction with the lighting state of the backlight 15 constituting the illumination means. When the backlight 15 is turned on to place the liquid crystal display device 100 in the transmissive display state, the reflective display subdot SD1 is not visually recognized as the main display region. Therefore, when the backlight 15 is turned on, a driving method can be applied in which the reflective display sub-dot SD1 is displayed with further enhanced contrast. In this case, for example, image processing means for performing signal processing along the input / output curve γ _b shown by a solid line in FIG. 7B is provided for the input signal, and the image signal converted into a binary gradation value is received. It is also possible to perform display by outputting to the reflective display subdot SD1. As described above, the reflective display sub-dot SD1 is displayed in binary gradation, thereby obtaining an effect of enhancing the display contrast of the transmissive display sub-dot SD2, which is the main display section when the backlight 15 is turned on.

In the liquid crystal display device 100 according to the present invention, the driving mode of the transmissive display sub-dots SD2 can be changed in conjunction with the lighting state of the backlight 15. That is, in the liquid crystal display device 100, a driving method in which the driving of the transmissive display sub-dot SD2 is stopped while the backlight 15 is turned off can be applied. In the reflective display state in which the backlight 15 is turned off, the transmissive display subdot SD2 is substantially black regardless of the display gradation because there is no light source, and thus is based on the other subdot in the transmissive display state. There is almost no contribution to the display.
Therefore, by using the function of independently driving the sub dots SD1 and SD2 of the liquid crystal display device 100, the display of the transmissive display sub dot SD2 is stopped when the backlight 15 is turned off, thereby reducing the power consumption of the liquid crystal display device 100. For example, it can be suitably used for a display during standby of a mobile phone.
In order to stop the display of the transmissive display subdot SD2, the input of the selection pulse from the scanning line driving circuit 204 to the scanning line 3t connected to the gate of the TFT element 30t of the subdot SD2 is stopped. Good.

  In the conventional liquid crystal display device driving method, flicker is often reduced by a method of inverting the polarity of adjacent dots or lines. However, in the liquid crystal display device according to the present invention, such a sub-dot unit does not. When the drive is performed properly, the polarity of the transmissive display or the reflective display is uniform and a large flicker is generated. In addition, the region in which the orientation can be controlled by the lateral electric field is narrowed. Therefore, in the liquid crystal display device of the present invention, it is preferable that at least the sub-dots in the same dot are driven with the same polarity.

(Electronics)
FIG. 8 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, video phones, 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. Transmissive / reflective display is possible.

FIG. 1 is a circuit configuration diagram of a liquid crystal display device according to a first embodiment of the present invention. FIG. 2A is a plan configuration diagram showing one pixel region, and FIG. 2B is a cross-sectional configuration diagram taken along the line A-A ′ of FIG. 3 is an enlarged plan view of the TFT element 30r shown in FIG. FIG. 4 is a graph showing electro-optical characteristics of the liquid crystal display device of the first embodiment. FIG. 5 is a circuit configuration diagram of the liquid crystal display device of the second embodiment. 6A is a plan configuration diagram showing one pixel region, and FIG. 6B is a cross-sectional configuration diagram taken along the line A-A ′ in FIG. FIG. 7 is a graph showing input / output curves by the image processing means according to the third embodiment. FIG. 8 is a perspective configuration diagram illustrating an example of an electronic apparatus according to the invention.

Explanation of symbols

  100,200 liquid crystal display device, D, D1 to D3 dot area, SD1 reflective display subdot, SD2 transmissive display subdot, 30r, 30t TFT element (switching element), 40r, 40t TFD element (switching element), 3r , 3t, 13 scan line, 6a, 19r, 19t data line, 110, 204 scan line drive circuit, 120, 201 data line drive circuit, 31r, 31t dielectric protrusion (orientation control means), 19ra, 19ta, 19tb opening (Orientation control means), 9r, 131r reflective display pixel electrode, 9t, 131t transmissive display pixel electrode, 131a, 131b island-like part, 131c connecting part, 15 backlight (illuminating means)

Claims (22)

A liquid crystal display device having a liquid crystal layer sandwiched between a pair of substrates,
One dot area is divided into two planes, and reflective display subdots for reflective display and transmissive display subdots for transmissive display are provided,
The reflective display sub-dot includes a reflective display pixel electrode and a reflective display switching element electrically connected to the reflective display pixel electrode.
The liquid crystal display device, wherein the transmissive display sub-dot includes a transmissive display pixel electrode and a transmissive display switching element electrically connected to the transmissive display pixel electrode.   The liquid crystal display device according to claim 1, wherein the liquid crystal layer includes a liquid crystal whose initial alignment is vertical alignment.   Alignment control means for controlling the alignment direction of liquid crystal molecules when a voltage is applied is provided in the planar area of the reflective display pixel electrode and / or in the planar area of the transmissive display pixel electrode. The liquid crystal display device according to claim 2.   Of the reflective display pixel electrode and the transmissive display pixel electrode, at least one of the electrodes has a plurality of island-shaped portions and a connecting portion that electrically connects the plurality of island-shaped portions. The liquid crystal display device according to claim 2 or 3.   The liquid crystal display device according to claim 4, wherein the orientation control means is disposed at a substantially central portion of the island-shaped portion in plan view.   6. The liquid crystal display device according to claim 1, wherein a liquid crystal capacity of the reflective display sub-dot is substantially equal to a liquid crystal capacity of the transmissive display sub-dot. The switching element is a two-terminal nonlinear element,
The ratio of the liquid crystal capacity of the reflective display sub-dot to the element capacity of the reflective display switching element is substantially equal to the ratio of the liquid crystal capacity of the transmissive display sub-dot to the element capacity of the transmissive display switching element. The liquid crystal display device according to claim 1, wherein: Illuminating means for supplying illumination light to the transmissive display sub-dots,
The drive state of the reflective display subdot and / or the transmissive display subdot can be changed in conjunction with the lighting state of the illumination means. A liquid crystal display device according to 1.   9. The liquid crystal display device according to claim 8, wherein when the illuminating means is turned off, the transmissive display sub-dot is stopped. Image processing means for performing predetermined image processing on the input image signal and outputting to each of the sub dots is further provided,
10. The liquid crystal according to claim 1, wherein the image processing means outputs an image signal obtained by performing signal processing for enhancing display contrast on the reflective display sub-dots. 11. Display device.   11. The image signal output from the image processing unit to the reflective display sub-dot is an image signal obtained by converting an input image signal into a binary gradation value. Liquid crystal display device.   The image signal output from the image processing means to the reflective display sub-dot is an image signal that has been subjected to signal processing for increasing a gain in an intermediate gradation region of the input image signal. The liquid crystal display device according to claim 10. When the lighting means is turned on,
13. The image signal according to claim 10, wherein an image signal subjected to signal processing for enhancing the contrast is output from the image processing unit to the reflective display sub-dots. Liquid crystal display device. A method for driving a liquid crystal display device according to any one of claims 1 to 13,
A driving method of a liquid crystal display device, wherein the transmissive display sub-dot and the reflective display sub-dot are driven in different voltage ranges in which the maximum luminance is obtained by each sub-dot.   15. The method for driving a liquid crystal display device according to claim 14, wherein the transmissive display sub-dot and the reflective display sub-dot in the same dot region are driven with a voltage having the same polarity.   16. The method for driving a liquid crystal display device according to claim 14, wherein gradation display with enhanced contrast is performed in the reflective display sub-dots.   17. The method of driving a liquid crystal display device according to claim 16, wherein binary gradation display is performed in the reflective display sub-dots.   17. The method of driving a liquid crystal display device according to claim 16, wherein gradation correction for increasing a gain in an intermediate gradation region is performed on the reflective display sub-dot.   The driving state of the reflective display subdot and / or the transmissive display subdot is changed in conjunction with a lighting state of an illuminating unit that supplies illumination light to the transmissive display subdot. Item 16. A driving method of a liquid crystal display device according to item 14 or 15.   20. The method of driving a liquid crystal display device according to claim 19, wherein when the illumination unit is turned off, driving of the transmissive display sub-dots is stopped.   20. The method for driving a liquid crystal display device according to claim 19, wherein when the illumination unit is turned on, gradation display with enhanced contrast is performed in the reflective display sub-dots.   An electronic apparatus comprising the liquid crystal display device according to claim 1.

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