JP4438377B2 - Liquid crystal display device and electronic device - Google Patents

Description

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

A transflective liquid crystal display device in which a reflective display region and a transmissive display region are formed within a one-dot region has both a reflective function and a transmissive function, so that the display method can be switched according to the surrounding brightness. Display can be performed, and even when the surroundings are dark while reducing power consumption, good display can be obtained, which is suitable as a display portion of a portable device. As this type of liquid crystal display device, one having a “multi-gap structure” in which the thickness of the liquid crystal layer is different between the reflective display region and the transmissive display region is known (for example, see Patent Document 1). A liquid crystal display device in which this multi-gap structure is applied to a vertical alignment mode liquid crystal display device is also known (see, for example, Patent Document 2).
Japanese Patent Laid-Open No. 11-242226 JP 2002-350853 A

  The technique described in the above-mentioned prior art document is considered to be effective for improving the image quality and wide viewing angle of the transflective liquid crystal display device. However, in a vertical alignment mode liquid crystal display device having a multi-gap structure, it is necessary to form a highly controlled step structure in a fine dot region, so that the manufacturing process is complicated and expensive. Furthermore, when the vertical alignment mode is adopted, it is necessary to independently control the alignment of the vertical alignment liquid crystal for each of the reflective display area and the transmissive display area, and multi-domainization is also required to obtain a good display in all directions The problem becomes difficult. Furthermore, in the above liquid crystal display device, it is necessary to apply a vertical alignment film on which a step due to a multi-gap structure is formed, and this vertical alignment film is inferior in coating properties as compared with a conventional alignment film. In-plane unevenness of the thickness of the vertical alignment film may occur, and the orientation of the liquid crystal may be reduced.

  Further, in the liquid crystal display device in the vertical alignment mode, liquid crystal molecules are tilted radially when a voltage is applied for the purpose of widening the viewing angle of the display and preventing luminance unevenness when the panel is oblique (looks rough and blotch). Thus, it is known to control the orientation to make a multi-domain. In this configuration, when linearly polarized light is incident on the liquid crystal layer, a cross-shaped dark portion is generated in the dot region. Therefore, circularly polarizing plates (¼ wavelength plates) are provided on the outer surfaces of the upper and lower substrates. However, when a circularly polarizing plate is provided on the back side of the liquid crystal panel of the transflective liquid crystal display device, the light emitted from the backlight and reflected by the back surface (side surface of the substrate) of the reflecting film is absorbed by the polarizing plate and transmitted. There arises a problem that sufficient brightness cannot be obtained in display. Furthermore, there are problems such as a decrease in contrast due to the wavelength characteristics of the circularly polarizing plate and an increase in cost due to the use of two circularly polarizing plates.

  The present invention has been made in view of the above-described problems of the prior art, and can provide a display with high brightness, high contrast, a wide viewing angle, and can be manufactured at a low cost. The purpose is to provide.

In order to solve the above problems, the present invention provides a transflective liquid crystal display device that sandwiches a liquid crystal layer between a pair of substrates and performs reflective display and transmissive display in one dot region, The liquid crystal layer includes a liquid crystal having negative dielectric anisotropy in which initial alignment is vertical alignment, and a reflective polarizing layer is provided on the liquid crystal layer side of one of the pair of substrates, and the reflection The polarizing layer has a transmission axis and a reflection axis intersecting the transmission axis, reflects a part of the component parallel to the reflection axis of the incident light, and transmits a part of the transflective reflection polarization. A liquid crystal display device comprising a layer is provided.
According to this configuration, it is possible to satisfactorily perform both transmissive display and reflective display by the transflective reflective polarizing layer. Therefore, high-contrast display can be obtained without using a multi-gap structure, which was almost essential for obtaining a high-contrast display in a transflective liquid crystal display device. Since there is no reduction in contrast due to light leakage at the stepped portion provided in the dot region, high contrast display is possible even when compared to a multi-gap structure liquid crystal display device. In addition, since there is no decrease in the coating uniformity of the vertical alignment film due to the step of the multi-gap structure, the advantage is that a vertical alignment film that is inferior in coating properties compared to conventional alignment films can be easily formed to a uniform film thickness. Can also be obtained.

  In addition, since the reflective polarizing layer is used, the light incident on the liquid crystal layer is linearly polarized light, and the circularly polarizing plate that has been indispensable for the transflective liquid crystal display device that performs display using circularly polarized light. Is not required, and the liquid crystal display device can be easily reduced in thickness and cost. Since a circularly polarizing plate is not used, the backlight light reflected by the reflective polarizing layer passes through the polarizing plate and can be reused for display, and the luminance of transmissive display is superior to conventional liquid crystal display devices. It has become. Furthermore, since the circularly polarizing plate is not necessary, a high contrast display can be obtained without causing a decrease in contrast due to the wavelength dispersion of the circularly polarizing plate.

  In the liquid crystal display device of the present invention, the reflective polarizing layer may be provided on substantially the entire surface of the dot region. In the liquid crystal display device having such a configuration, the reflective polarizing layer partially transmits incident polarized light and reflects some polarized light. Since the reflective polarizing layer can be formed in a solid shape within the dot region, the structure is excellent in terms of ease of manufacturing and yield. Further, as compared with the case where the dot area is divided into a reflective display area and a transmissive display area, the area can be widely used, and the optical design of the pixel is facilitated.

  In the liquid crystal display device of the present invention, the reflective polarizing layer may be partially provided in the dot region. In the liquid crystal display device having such a configuration, the reflective display region is configured by the region where the reflective polarizing layer is partially formed, and the transmissive display region is configured by the remaining non-formed region. In this case, since the transmissive display area and the reflective display area are clearly divided, the optical design can be optimized for each of the reflective display and the transmissive display, which is advantageous in obtaining a higher-quality liquid crystal display device. is there.

  In the liquid crystal display device of the present invention, the reflective polarizing layer may include a prism array in which a plurality of prisms are arranged and a dielectric interference film formed on the prism array. The reflective polarizing layer having such a configuration can easily adjust the reflectance and transmittance by the laminated structure of the dielectric interference film, and is particularly used for the configuration in which the reflective polarizing layer is provided on the entire surface of the dot region. Is preferred.

  In the liquid crystal display device of the present invention, the reflective polarizing layer may include a metal reflective film provided with a plurality of fine slit-shaped openings. The reflective polarizing layer having such a configuration has the advantage that the degree of polarization is high and the patterning is easy as compared with the configuration in which the dielectric interference film is formed on the prism array. Therefore, it is a reflective polarizing layer suitable for use in a configuration in which a reflective polarizing layer is partially provided in the dot region.

  In the liquid crystal display device of the present invention, a color filter is provided on one of the pair of substrates, and the color filter is divided into a plurality of planar regions having different chromaticities in the dot region. it can. According to this configuration, it is possible to perform color display with appropriate chromaticity in each of the reflective display region and the transmissive display region, and a liquid crystal display device with more colorful and high image quality can be obtained.

  In the liquid crystal display device of the present invention, an alignment control means for regulating a tilt direction of liquid crystal molecules when a voltage is applied is provided on the liquid crystal layer side of at least one of the pair of substrates. preferable. According to this configuration, it is possible to appropriately control the alignment state of the liquid crystal molecules in the vertical alignment mode when a voltage is applied, and it is possible to effectively reduce the spot-like unevenness at the time of perspective, which has been a problem in the liquid crystal display device in the vertical alignment mode. In addition, a liquid crystal display device with excellent visibility can be provided.

  In the liquid crystal display device according to the aspect of the invention, it is preferable that the orientation control unit has a substantially linear shape in a plan view and extends in a direction intersecting with the reflection axis of the reflective polarizing layer. In the liquid crystal display device of the present invention, since display is performed using linearly polarized light, it is preferable to prevent parallel linearly polarized light from entering the liquid crystal molecules tilted by voltage application by applying the above configuration. . This is because the birefringence by the liquid crystal does not occur for the linearly polarized light incident parallel to the liquid crystal molecules.

  In the liquid crystal display device of the present invention, it is preferable that an intersection angle between the orientation control means and the reflection axis of the reflective polarizing layer is approximately 45 °. With such a configuration, the birefringence action of the liquid crystal can be maximized with respect to linearly polarized light used for display, and a display with high brightness and high contrast can be obtained.

  In the liquid crystal display device according to the aspect of the invention, it is preferable that the orientation control unit has a substantially triangular wave shape in plan view extending so as to intersect with the reflection axis of the reflective polarizing layer. According to this configuration, a plurality of liquid crystal domains having alignment directions intersecting each other can be formed by the alignment control means, and the linearly polarized light incident on the liquid crystal is a polarization direction intersecting with the alignment direction of the liquid crystal molecules. Therefore, it is possible to provide a liquid crystal display device in which a low luminance region is not formed in the dot region and a wide viewing angle display can be obtained.

  In the liquid crystal display device of the present invention, a polarizing layer is provided on the substrate on which the reflective polarizing layer is provided, and the polarizing layer is disposed so that its transmission axis is substantially parallel to the reflective axis of the reflective polarizing layer. It is preferable that According to this configuration, since the polarization direction of the linearly polarized light incident on the reflective polarizing layer and the reflection axis of the reflective polarizing layer are arranged substantially in parallel, when the light reflected by the reflective polarizing layer returns to the polarizing layer Therefore, it is possible to prevent the light from being absorbed by the polarizing layer, and to provide a high-luminance liquid crystal display device with high light utilization efficiency.

  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 that can display with high brightness, high contrast, and a wide viewing angle and can be manufactured at low cost 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)
<Configuration of liquid crystal display device>
FIG. 1 is a circuit configuration diagram of a liquid crystal display device according to a first embodiment of the present invention, FIG. 2 is a configuration diagram showing a schematic planar structure of electrodes, and FIG. 3 is a plan view showing one pixel region. FIG. 4 is a cross-sectional configuration diagram.
The liquid crystal display device shown in these figures is an active matrix color liquid crystal display device using a TFD (Thin film diode) element (two-terminal nonlinear element) as a switching element. Further, the liquid crystal display device according to the present embodiment includes a liquid crystal layer made of a liquid crystal having a negative dielectric anisotropy in which the initial alignment is vertical alignment.

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

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

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

Next, the pixel configuration of the liquid crystal display device 100 of the present embodiment will be described with reference to FIGS. 3 and 4.
FIG. 3 is a plan configuration diagram of one pixel of the liquid crystal display device 100 as viewed from the element substrate 10 side described later, and FIG. 4 is a cross-sectional configuration diagram taken along the line AA ′ in FIG. The liquid crystal display device 100 mainly includes a pixel electrode 31 having a substantially rectangular shape in a plan view provided between two scanning lines 13 extending vertically in FIG. 2 and facing the common electrode 9, and a TFD element 40. Has a dot area. In the illustrated dot areas D1 to D3, a red color material layer 22R, a green color material layer 22G, and a red color material layer 22B are arranged, respectively, and color display is possible with the three dot areas D1 to D3. A large pixel. A color filter of the present liquid crystal display device is formed by the three color material layer groups.

The pixel electrode 31 and the common electrode 9 are both made of a transparent conductive material such as ITO (indium tin oxide), and the pixel electrode 31 has two linear opening slits (alignment control) in the dot region. Means) 31 a and 31 a are formed by cutting out the pixel electrode 31. The common electrode 9 is formed with four linear opening slits 9a.
The opening slits 31a and 31a formed in the pixel electrode 31 are arranged in a substantially “<” shape in plan view, and the opening slits 9a formed in the common electrode 9 are arranged on both sides in the width direction of the opening slit 31a. Thus, it is formed to extend substantially parallel to the opening slit 31a. That is, when viewed in the entire display area, the opening slits 31a and the slits 9a are arranged in a substantially triangular wave shape in a plan view extending in the vertical direction of FIG. 3 and are alternately arranged in the horizontal direction of FIG.

  On the other hand, as shown in FIG. 4, the liquid crystal display device 100 has negative dielectric anisotropy in which the initial alignment state is vertical alignment between the element substrate 10 and the counter substrate 25 disposed to face the element substrate 10. The liquid crystal panel includes a liquid crystal layer 50 composed of liquid crystal, and a backlight (illumination device) disposed on the back side (outer surface side of the element substrate 10) of the liquid crystal panel. In addition, a spacer 53 is provided to hold the layer thickness (cell gap) of the liquid crystal layer 50 at the edge of the dot region. In the present embodiment, the spacer 53 is a photo spacer obtained by patterning a resin material such as an acrylic resin using a photolithography technique, but a configuration in which spherical spacers are dispersed in the liquid crystal layer 50 can be applied without any problem. .

  The element substrate 10 is formed by laminating the reflective polarizing layer 17, the pixel electrode 31, the scanning line 13, and the vertical alignment film 19 on the side surface of the liquid crystal layer 50 of the substrate body 10A made of a translucent material such as quartz or glass. It is composed. A polarizing plate (polarizing layer) 18 is provided on the outer surface of the substrate body 10A.

The reflective polarizing layer 17 is a transflective reflective polarizing layer having the configuration shown in the perspective configuration diagram of FIG. That is, a dielectric body in which a prism array 17a made of a thermosetting or photo-curing transparent resin such as an acrylic resin formed on the inner surface of the substrate body 10A and a plurality of dielectric films 17d and 17e are alternately stacked. And an interference film 17b.
The prism array 17a has a plurality of triangular prisms (prism-shaped) ridges 17c having two inclined surfaces, and the plurality of ridges 17c are continuously and periodically formed to have a triangular triangular cross section. This constitutes a prism array.
The dielectric interference film 17b is formed by alternately laminating dielectric films 17d and 17e made of two kinds of materials having different refractive indexes so as to follow the inclined surfaces of the plurality of ridges 17c (so-called three-dimensional photonics). In the case of the present embodiment, for example, seven layers of a TiO ₂ film and a SiO ₂ film are laminated.

  Although not shown in FIG. 4, the upper surface of the dielectric interference film 17b is covered with a resin layer and flattened. As described above, the dielectric interference film 17b formed on the prism array has anisotropy in light propagation characteristics, and when natural light is incident from the upper surface side of FIG. The linearly polarized light parallel to the extending direction is reflected, and the linearly polarized light perpendicular to the extending direction of the ridges 17c is transmitted. That is, the reflective polarizing layer 17 shown in FIG. 4 has a reflection axis parallel to the extending direction of the ridges 17c and a transmission axis perpendicular to the extending direction of the ridges 17c. In the liquid crystal display device 100 of this embodiment, linearly polarized light parallel to the reflection axis of the reflective polarizing layer 17 is incident from the polarizing plate 18 to perform transmissive display. It arrange | positions so that the reflective axis (extension direction of the protrusion 17c) of the polarizing layer 17 may become substantially parallel.

The film thickness of the one-layer dielectric films 17d and 17e constituting the dielectric interference film 17b is about 10 nm to 100 nm, and the total film thickness of the dielectric interference film 17b is about 300 nm to 1 μm. The height of the ridges 17c is 0.5 μm to 3 μm, and the pitch between the ridges 17c and 17c is about 1 μm to 6 μm. As a material for the dielectric films 17d and 17e, Ta ₂ O ₅ , Si or the like can be used in addition to the above TiO ₂ and SiO ₂ .

Note that the stacking pitch of the dielectric films 17d and 17e and the pitch of the ridges 17c are appropriately adjusted to optimum values according to the characteristics of the target reflected polarized light 17. That is, the reflective polarizing layer 17 having the above configuration can control the transmittance (reflectance) according to the number of the dielectric films 17d and 17e stacked. By reducing the number of stacked layers, the reflection axis (the length of the projection 17c) can be reduced. It is possible to increase the transmittance of linearly polarized light parallel to the present direction and decrease the reflectance. However, when more than a predetermined number of layers are stacked, most of the linearly polarized light parallel to the reflection axis is reflected.
The reflective polarizing layer 17 according to the present embodiment reflects about 70% of the linearly polarized light parallel to the incident reflection axis and transmits the remaining about 30% by adjusting the dielectric interference film 17b. ing.

  Next, the pixel electrode 31 and the scanning line 13 are formed on the reflective polarizing layer 17. A TFD element 40 is formed in the same layer as the pixel electrode 31 and the scanning line 13. A vertical alignment film 19 is formed so as to cover the pixel electrodes 31 and the scanning lines 13.

  Next, in the counter substrate 25, the color material layer 22R, the common electrode 9, and the vertical alignment film 26 are stacked on the side surface of the liquid crystal layer 50 of the substrate body 25A made of a light-transmitting material such as glass or quartz. A polarizing plate 16 is disposed on the outer surface of the substrate body 25A. As described above, the color material layer 22R constitutes a color filter together with the color material layers 22G and 22B provided corresponding to each dot region. The common electrode 9 extends in the left-right direction in FIG. 4 and is formed in a stripe shape.

Here, in the liquid crystal display device of this embodiment, as shown in FIG. 3, the vertically aligned liquid crystal is formed by the opening slits 9 a formed in the common electrode 9 and the opening slits 31 a formed in the pixel electrode 31. The alignment state at the time of voltage application can be appropriately controlled.
FIG. 6A is a schematic cross-sectional view for explaining the alignment regulating action by the opening slits 9a and 9a and the opening slit 31, and is common with the liquid crystal 50 in the cross section along the line DD 'shown in FIG. It is a figure which shows the electrode 9 and the pixel electrode 31. FIG. As shown in FIG. 6A, in the liquid crystal display device 100, when the voltage changes, the liquid crystal molecules 51 are inclined toward both sides of the opening slits 9a and 9a extending substantially perpendicular to the paper surface and the opening slit 31a in the width direction. It has become. That is, in the region on the upper side of the pixel electrode 31 shown in FIG. 3 where the opening slits 9a and 31a are formed to extend upward to the left, a liquid crystal domain aligned in the upper right portion of the figure is formed. Further, in a region where the opening slits 9a and 31a are formed so as to extend to the right in the figure below the pixel electrode 31, a liquid crystal domain oriented in the figure on the lower right is formed. And since the boundary of these liquid crystal domains is fixed on the opening slits 9a and 31a, the unevenness at the time of perspective, which is a problem in display quality in a liquid crystal display device having a vertically aligned liquid crystal layer, is observed. This can be effectively prevented and a good display can be obtained in a wide viewing angle range.

The polarizing plates 16 and 18 are preferably arranged so that their transmission axes intersect the alignment direction of the liquid crystal domains formed when the voltage is applied. Further, it is preferable that the transmission axes of the polarizing plates 16 and 18 are arranged in directions extending in the horizontal direction and the vertical vertical direction in FIG. That is, the polarizing plates 16, 18 and the opening slits 9a, 31a,..., 31a,... So that the alignment direction of the liquid crystal molecules at the time of voltage application and the transmission axes of the polarizing plates 16, 18 intersect at an angle of about 45 °. Are preferably arranged.
In this way, by arranging the transmission axes of the polarizing plates 16 and 18 and the opening slits 9a, 31a, etc., in the liquid crystal display device of this embodiment in the linear polarization mode, a region where the luminance is partially low in the dot region. (Dark part) can be prevented from occurring, and a high-luminance display can be obtained.

In this embodiment, an aperture slit is used as the alignment control means for the vertically aligned liquid crystal. As the alignment control means, dielectric protrusions extending substantially perpendicular to the paper surface as shown in FIG. A configuration in which 9b is formed on the common electrode 9 can also be applied. In this case, the liquid crystal molecules 51 are aligned by the vertical alignment film formed on the surface of the dielectric protrusion 9b, and the same effect is obtained as when a pretilt is given to the liquid crystal around the dielectric protrusion 9b. Therefore, by providing the dielectric protrusions 9b and 9b, the tilt direction of the liquid crystal molecules 51 can be controlled well, and a good display can be obtained in a wide viewing angle range.
Of course, the dielectric protrusion may be provided in place of the opening slit 31a provided in the pixel electrode 31, and the dielectric protrusion may be provided in the plane region of the opening slits 9a and 31a.

  The counter substrate 25 can be provided with light scattering means such as a front scattering plate. With such a configuration, the visibility of the reflective display can be improved, and the display quality can be improved. .

<Display principle of liquid crystal display device>
Next, the display principle of the liquid crystal display device 100 of this embodiment will be described with reference to FIG. In the explanatory view shown in FIG. 7, in order to make the drawing easy to see, components unnecessary for explaining the display principle are omitted. The arrows and the like shown in the polarizing plate 16, the reflective polarizing layer 17, and the polarizing plate 18 indicate the directions of the respective transmission axes, and the arrows and the like shown in the optical path indicate the polarization direction of the light beam.

  First, when dark display (black display) is performed in the reflection mode (see the left side of FIG. 7), no voltage is applied to the liquid crystal layer 50 (non-selection voltage application state), and the liquid crystal molecules 51 are placed between the upper and lower substrates. The substrate is oriented perpendicular to the substrate surface. In this state, the light incident from above the polarizing plate 16 becomes linearly polarized light parallel to the paper surface after passing through the polarizing plate 16 because the transmission axis of the polarizing plate 16 is parallel to the paper surface. This linearly polarized light reaches the reflective polarizing layer 17 with almost no polarization conversion action by the liquid crystal molecules 51. Further, the light passes through the reflective polarizing layer 17 having a transmission axis parallel to the linearly polarized light, and is then absorbed by the polarizing plate 18 having a transmission axis perpendicular to the paper surface, resulting in dark display.

Next, when dark display is performed in the transmission mode (see the left side of FIG. 7), the alignment state of the liquid crystal molecules 51 is the same as that of the dark display in the reflection mode. The light incident on the panel from the backlight 15 is converted into linearly polarized light perpendicular to the paper surface by the polarizing plate 18 having a transmission axis perpendicular to the paper surface, and then enters the reflective polarizing layer 17. Of the polarization component parallel to the reflection axis of the reflective polarizing layer 17, about 70% is reflected and returned to the backlight 15 side, and about 30% is transmitted and enters the liquid crystal layer 50. The light incident on the liquid crystal layer 50 reaches the polarizing plate 16 of the counter substrate 25 and is absorbed without being substantially subjected to the polarization conversion action by the liquid crystal molecules 51, resulting in dark display.
The light reflected by the reflective polarizing layer 17 and returned to the backlight 15 is reflected by the reflective film 15a of the backlight 15 and enters the reflective polarizing layer 17 again. And since the polarization component which permeate | transmitted the reflective polarizing layer 17 is absorbed by the polarizing plate 16, it is not radiated | emitted above the illustration (observer direction) of the liquid crystal display device 100. FIG.

On the other hand, when bright display (white display) is performed in the reflection mode (see the right side of FIG. 7), a voltage is applied to the liquid crystal layer 50 (selection voltage application state), and the liquid crystal molecules 51 are aligned in the substrate surface direction. Let the state be In the present embodiment, the phase difference of the liquid crystal layer 50 is λ / 2 in this voltage application state. The linearly polarized light parallel to the paper surface incident on the liquid crystal layer 50 via the polarizing plate 16 is converted into linearly polarized light perpendicular to the paper surface by the action of the liquid crystal layer 50 and enters the reflective polarizing layer 17. Then, about 70% of the light incident on the reflective polarizing layer 17 is reflected and enters the liquid crystal layer 50, and the remaining about 30% is transmitted through the reflective polarizing layer 17. The light that has returned to the liquid crystal layer 50 is returned to linearly polarized light parallel to the paper surface by the liquid crystal layer 50, enters the polarizing plate 16, is transmitted through the polarizing plate 16, and is radiated toward the viewer to provide a bright display.
Incidentally, about 30% of the light transmitted through the reflective polarizing layer 17 passes through the polarizing plate 18 and is reflected by the reflective film 15a of the backlight, and enters the back surface (backlight side surface) of the reflective polarizing layer 17. Since this light is parallel to the reflection axis of the reflective polarizing layer, a part of the light passes through the reflective polarizing layer 17 and enters the liquid crystal layer 50, and is used as display light. As described above, in the liquid crystal display device 100 of the present embodiment, the reflectance of the reflective polarizing layer 17 itself is about 70%, but the light transmitted through the reflective polarizing layer 17 can also be used for display, and bright reflection is achieved. A display can be obtained.

Next, when the bright display in the transmission mode is performed (see the right side of FIG. 7), the alignment state of the liquid crystal molecules 51 is the same as that in the reflection mode. Light incident from the backlight 15 and converted into linearly polarized light perpendicular to the paper surface by the polarizing plate 18 is incident on the reflective polarizing layer 17 from the back side, and about 30% of the light is transmitted and incident on the liquid crystal layer 50. The remaining approximately 70% is reflected by the reflective polarizing layer 17 and returns to the backlight 15.
The light incident on the liquid crystal layer 50 is converted into linearly polarized light parallel to the paper surface by the action of the liquid crystal layer 50, is incident on the polarizing plate 16, is transmitted through the polarizing plate 16, and is emitted toward the viewer, thereby providing a bright display. Further, the light reflected by the reflective polarizing layer 17 is reflected by the reflective film 15a of the backlight 15 and enters the reflective polarizing layer 17 again, and part of the light is transmitted and enters the liquid crystal layer 50 as display light. Used. Here, the light reflected again by the reflective polarizing layer 17 is transmitted through the reflective polarizing layer 17 and used as display light while being repeatedly reflected from the reflective film 15a.
As described above, in the liquid crystal display device 100 of the present embodiment, the transmittance of the reflective polarizing layer 17 itself is about 30%, but the light from the backlight 15 can be reused for high efficiency backlight light. Can be used, and a high-luminance transmissive display can be obtained.

The liquid crystal display device 100 of the present embodiment having the above-described configuration includes the transflective reflective polarizing layer 17 on the inner surface of the element substrate 10, so that the electro-optical characteristics of the reflective display and the transmissive display can be made uniform. In addition, a high contrast display can be obtained without adopting a multi-gap structure, and it is not necessary to form a step in a fine dot region, so that the liquid crystal display device can be manufactured at low cost. Moreover, it becomes easy to form the opening slits 9a, 31a, etc. provided as the orientation control means and the projections of the dielectric material.
Furthermore, since the liquid crystal alignment is not disturbed due to the steps of the multi-gap structure, a high-contrast display is possible even when compared with a multi-gap structure liquid crystal display device.

When the multi-gap structure and the vertical alignment liquid crystal are combined, unevenness in the thickness of the vertical alignment film 19 may occur due to the unevenness of the coating surface due to the level difference and the low coating property of the vertical alignment film itself. However, in the present liquid crystal display device, the coated surfaces of the vertical alignment films 19 and 26 are flat, and a vertical alignment film having a uniform film thickness and excellent alignment controllability can be formed.
The transflective reflective polarizing layer 17 is provided on the entire surface in the dot region and does not require patterning. Therefore, the transflective reflective polarizing layer 17 is easy to manufacture and provides excellent flatness on the surface of the element substrate 10. It contributes to the improvement.

. In addition, by enabling high luminance display in the linear polarization mode, a circularly polarizing plate (for example, a λ / 4 phase difference plate or a λ / 4 phase difference, which has been conventionally used in a liquid crystal display device in a vertical alignment mode). A combination of a plate and a λ / 2 phase difference plate is not required, and the device can be made thinner and less expensive than conventional liquid crystal display devices, and the wavelength dispersion of the circularly polarizing plate can be reduced. There is also an advantage that a high-contrast display can be obtained because the resulting contrast is not lowered.
As described above, the liquid crystal display device of this embodiment can obtain a bright transmissive display without providing a reflective polarizing plate and a circularly polarizing plate outside the element substrate 10, and is a portable device in which thinning and weight reduction are important. It is extremely excellent as a transflective liquid crystal display device used for LCDs.

  In the liquid crystal display device of this embodiment, since it is not necessary to provide the reflective polarizing layer 17 with an opening for transmissive display, it is easy to manufacture and can be manufactured at low cost. Since there is no opening, transmissive display or reflective display is performed on the entire surface of the pixel region, and there is an advantage that light use efficiency is high and a bright display can be obtained. In addition, since negative / positive inversion does not occur in the reflection mode and the transmission mode, even when transmissive display is performed in an environment where external light is incident on the liquid crystal panel, a high-quality display can be obtained without causing a decrease in contrast. Can do.

(Second Embodiment)
<Configuration of liquid crystal display device>
Next, a second embodiment of the present invention will be described with reference to the drawings. FIG. 8 is a plan configuration diagram showing one pixel provided in the liquid crystal display device 200 of the present embodiment, FIG. 9 is a cross-sectional configuration diagram taken along line BB ′ in FIG. 8, and FIG. 10 is a liquid crystal display device 200. FIG. The liquid crystal display device of the present embodiment is characterized in that it has the same basic configuration as that of the first embodiment and adopts different configurations for the reflective polarizing layer and the color filter. Therefore, in FIG. 8 thru | or 10, the same code | symbol is attached | subjected to the same component as FIG. 1 thru | or FIG. 7, and detailed description is abbreviate | omitted.

As shown in FIG. 8, in the liquid crystal display device 200 of the present embodiment, a reflective polarizing layer 117 extending in the dot region arrangement direction (the left-right direction in the drawing) is provided across the dot regions D1 to D3. In each dot area, an area where the reflective polarizing layer 117 is provided is a reflective display area, and a non-formation area 117a of the reflective polarizing layer 117 is a transmissive display area.
Similar to the first embodiment, the pixel electrode 31a and the common electrode 9 are provided with opening slits 9a, 31a, which constitute orientation control means for controlling the tilt direction of the liquid crystal molecules when a voltage is applied. Sometimes a plurality of liquid crystal domains are formed.

  The reflective polarizing layer 117 is arranged so as to cover about ¼ of the dot area from the upper and lower ends of each dot area in the figure, and the reflective polarizing layer 117 arranged on the upper side in the figure extends in the upper left direction in the figure. The reflective polarizing layer 117 disposed on the lower side in the figure overlaps with the opening slits 31a and 9a in a plan view and overlaps with the opening slits 31a and 9a extending in the upper right direction in the figure in a plan view. With this configuration, the liquid crystal domains formed when a voltage is applied are equivalent in the reflective display region and the transmissive display region, and a wide viewing angle display can be obtained in both the reflective display and the transmissive display. .

Next, looking at the cross-sectional structure shown in FIG. 9, the liquid crystal display device 200 includes a liquid crystal panel in which a liquid crystal layer 50 is sandwiched between the element substrate 10 and the counter substrate 25 that are disposed opposite to each other, and the back surface of the liquid crystal panel. And a backlight (illumination device) 15 disposed on the side.
The element substrate 10 has a configuration in which the reflective polarizing layer 117, the pixel electrode 31, and the vertical alignment film 19 are stacked on the side surface of the liquid crystal layer 50 of the substrate body 10A, and the polarizing plate 18 is provided on the outer surface side of the substrate body 10A. I have.

The reflective polarizing layer 117 is a reflective polarizing layer whose perspective configuration is shown in FIG. That is, the metal reflective film 117b formed on the inner surface of the substrate body 10A has a configuration in which a plurality of fine slit-shaped openings 117c are formed at a predetermined pitch. For the metal reflective film 117b, a light reflective metal material such as aluminum or silver can be suitably used.
The openings 117c are formed substantially parallel to each other, and the widths of the openings 117c are substantially the same. The thickness of the metal reflective film 117b is 100 nm to 400 nm, and the width of the opening 117c is about 30 nm to 300 nm. Further, the width of one metal reflective film 117b is about 30 nm to 300 nm.

  With the above configuration, the reflective polarizing layer 117 reflects a polarized component parallel to the extending direction of the metal reflecting film 117b in the incident light, and transmits a polarized component perpendicular to the extending direction of the metal reflecting film 117b. It is like that. That is, the reflective polarizing layer 117 has a reflection axis parallel to the extending direction of the metal reflection film 117b and a transmission axis perpendicular to the reflection axis. In the present embodiment, the reflection axis of the reflective polarizing layer 117 and the transmission axis of the polarizing plate 18 are arranged substantially in parallel.

  Next, on the counter substrate 25, the color material layer 22R, the common electrode 9, and the vertical alignment film 26 are laminated on the side surface of the liquid crystal layer 50 of the substrate body 25A, and the polarizing plate 16 is disposed on the outer surface side of the substrate body 25A. It has the provided configuration. The color material layer 22R is divided into two color material regions 22Rr and 22Rt in the dot region, and the color material region 22Rr is provided at a position overlapping the reflective display region (that is, the formation region of the reflective polarizing layer 117). The color material region 22Rt is provided at a position overlapping the transmissive display region (that is, the reflective polarizing layer non-formation region 117a). As described above, the color display is performed using the different color material regions 22Rr and 22Rt for the reflective display and the transmissive display, so that appropriate chromaticity can be displayed for each display mode, and a high-quality display is achieved. Can get to.

<Display principle>
Next, the display principle of the liquid crystal display device of this embodiment will be described with reference to FIG. In the explanatory diagram shown in FIG. 10, components that are not necessary for the description of the display principle are omitted in order to make the drawing easier to see. The arrows and the like shown in the polarizing plate 16, the reflective polarizing layer 117, and the polarizing plate 18 indicate the directions of the respective transmission axes, and the arrows and the like shown in the optical path indicate the polarization direction of the light beam.

  First, when performing dark display (black display) in the reflection mode (see the left side of FIG. 10), the liquid crystal layer 50 is not applied with a voltage (non-selection voltage applied state), and the liquid crystal molecules 51 are placed between the upper and lower substrates. The substrate is oriented perpendicular to the substrate surface. In this state, the light incident from above the polarizing plate 16 becomes linearly polarized light parallel to the paper surface after passing through the polarizing plate 16 because the transmission axis of the polarizing plate 16 is parallel to the paper surface. This linearly polarized light reaches the reflective polarizing layer 117 with almost no polarization conversion action by the liquid crystal molecules 51. Further, the light passes through the reflective polarizing layer 117 having a transmission axis parallel to the linearly polarized light, and is then absorbed by the polarizing plate 18 having a transmission axis perpendicular to the paper surface, resulting in dark display.

Next, when dark display is performed in the transmission mode (see the left side of FIG. 10), the alignment state of the liquid crystal molecules 51 is the same as that of the dark display in the reflection mode. The light incident on the panel from the backlight 15 is converted into linearly polarized light perpendicular to the paper surface by the polarizing plate 18 having a transmission axis perpendicular to the paper surface, and then transmitted through the non-formation region 117a of the reflective polarizing layer 117. Is incident on. The light incident on the liquid crystal layer 50 reaches the polarizing plate 16 of the counter substrate 25 and is absorbed without being substantially subjected to the polarization conversion action by the liquid crystal molecules 51, resulting in dark display.
The light incident on the reflective polarizing layer 117 is reflected by the same layer having a reflection axis perpendicular to the paper surface, returns to the backlight 15, and is repeatedly reflected between the reflective film 15 a of the backlight 15. And the light which permeate | transmitted the said non-formation area | region 117a while repeating such reflection is absorbed by the polarizing plate 16 similarly to the above.

  On the other hand, when bright display (white display) is performed in the reflection mode (see the right side of FIG. 10), a voltage is applied to the liquid crystal layer 50 (selection voltage application state), and the liquid crystal molecules 51 are aligned in the substrate surface direction. Let the state be In the present embodiment, the phase difference of the liquid crystal layer 50 is λ / 2 in this voltage application state. The linearly polarized light parallel to the paper surface incident on the liquid crystal layer 50 via the polarizing plate 16 is converted into linearly polarized light perpendicular to the paper surface by the action of the liquid crystal layer 50 and is incident on the reflective polarizing layer 117. Then, the light is reflected by the reflective polarizing layer 117 having a reflection axis perpendicular to the paper surface and returns to the liquid crystal layer 50. The light that has returned to the liquid crystal layer 50 is returned to linearly polarized light parallel to the paper surface by the liquid crystal layer 50, enters the polarizing plate 16, is transmitted through the polarizing plate 16, and is radiated toward the viewer to provide a bright display.

Next, when the bright display in the transmission mode is performed (see the right side of FIG. 10), the alignment state of the liquid crystal molecules 51 is the same as the bright display in the reflection mode. Light incident from the backlight 15 and converted into linearly polarized light perpendicular to the paper surface by the polarizing plate 18 is incident on the reflective polarizing layer 17 from the back side, and the light incident on the non-formation region 117a is transmitted and transmitted through the liquid crystal layer 50. Is incident on. The light incident on the liquid crystal layer 50 is converted into linearly polarized light parallel to the paper surface by the action of the liquid crystal layer 50, is incident on the polarizing plate 16, is transmitted through the polarizing plate 16, and is emitted toward the viewer, thereby providing a bright display.
The light reflected by the reflective polarizing layer 117 is reflected by the reflective film 15a of the backlight 15 and enters the reflective polarizing layer 117 again, and the component incident on the non-formation region 117a is transmitted and enters the liquid crystal layer 50. And used as display light.
As described above, in the liquid crystal display device 100 of the present embodiment, the backlight light reflected by the back surface of the reflective polarizing layer 117 is reused to perform transmissive display, so that a bright transmissive display can be obtained. It can be done.

The liquid crystal display device 200 according to the present embodiment having the above-described configuration includes the transflective reflective polarizing layer 117 on the inner surface of the element substrate 10, so that the electro-optical characteristics of the reflective display and the transmissive display can be aligned. In addition, a high contrast display can be obtained without adopting a multi-gap structure, and it is not necessary to form a step in a fine dot region, so that the liquid crystal display device can be manufactured at low cost. Moreover, it becomes easy to form the opening slits 9a, 31a, etc. provided as the orientation control means and the projections of the dielectric material.
Furthermore, since the liquid crystal alignment is not disturbed due to the steps of the multi-gap structure, a high-contrast display is possible even when compared with a multi-gap structure liquid crystal display device.

  When the multi-gap structure and the vertical alignment liquid crystal are combined, unevenness in the thickness of the vertical alignment film 19 may occur due to the unevenness of the coating surface due to the level difference and the low coating property of the vertical alignment film itself. However, in the present liquid crystal display device, the coated surfaces of the vertical alignment films 19 and 26 are flat, and a vertical alignment film having a uniform film thickness and excellent alignment controllability can be formed.

In this embodiment, when the transflective reflective polarizing layer 117 is provided, the reflective polarizing layer 117 is partially provided in the dot area, and transmissive display is performed in the non-formation area. The layer 117 has a structure in which the metal reflective film 117b is patterned as shown in FIG. 11, and the non-formation region 117a can be formed at the same time in the patterning process for forming the opening 117c, so that efficient manufacture is possible.
Further, the reflective polarizing layer 117 shown in FIG. 11 has an advantage that the degree of polarization can be made higher than that of the reflective polarizing layer 17 mainly composed of a dielectric interference film, and can be easily patterned so that the reflective display area and the transmissive display area can be obtained. Thus, a liquid crystal display device capable of providing a colorful display can be realized by combining with a multi-color color material layer as in this embodiment.
In addition, since negative / positive inversion does not occur in the reflection mode and the transmission mode, even when transmissive display is performed in an environment where external light is incident on the liquid crystal panel, a high-quality display can be obtained without causing a decrease in contrast. Can do.

In addition, by enabling high luminance display in the linear polarization mode, a circularly polarizing plate (for example, a λ / 4 phase difference plate or a λ / 4 phase difference, which has been conventionally used in a liquid crystal display device in a vertical alignment mode). A combination of a plate and a λ / 2 phase difference plate is not required, and the device can be made thinner and less expensive than conventional liquid crystal display devices, and the wavelength dispersion of the circularly polarizing plate can be reduced. There is also an advantage that a high-contrast display can be obtained because the resulting contrast is not lowered.
As described above, the liquid crystal display device of this embodiment can obtain a bright transmissive display without providing a reflective polarizing plate and a circularly polarizing plate outside the element substrate 10, and is a portable device in which thinning and weight reduction are important. It is extremely excellent as a transflective liquid crystal display device used for LCDs.

(Electronics)
FIG. 12 is a perspective configuration diagram of a mobile phone which is an example of an electronic apparatus provided with the liquid crystal display device according to the present invention in a display unit. The mobile phone 1300 includes the liquid crystal display device of the present invention in a small size display unit. 1301, and includes a plurality of operation buttons 1302, a mouthpiece 1303, and a mouthpiece 1304.
The liquid crystal display device of the above embodiment is not limited to the mobile phone, but is an electronic book, a personal computer, a digital still camera, a liquid crystal television, a viewfinder type or a monitor direct view type video tape recorder, a car navigation device, a pager, and an electronic notebook. , Calculators, word processors, workstations, videophones, POS terminals, devices equipped with touch panels, etc., can be suitably used as image display means, and in any electronic device, display of high brightness, high contrast, wide viewing angle Can be provided.

FIG. 1 is a circuit configuration diagram of a liquid crystal display device according to a first embodiment. FIG. 2 is a plan view of the display area. FIG. 3 is a diagram illustrating a pixel plane configuration. FIG. 4 is a cross-sectional configuration diagram of the same. FIG. 5 is an explanatory view of the operating principle. FIG. 6 is a perspective configuration diagram of the reflective polarizing layer. FIG. 7 is an explanatory view of the orientation control means. FIG. 8 is a configuration diagram of a pixel plane according to the second embodiment. FIG. 9 is a cross-sectional configuration diagram of the same. FIG. 10 is a diagram for explaining the operating principle. FIG. 11 is a perspective configuration diagram of the reflective polarizing layer. FIG. 12 is a perspective configuration diagram illustrating an example of an electronic apparatus.

Explanation of symbols

  100,200 Liquid crystal display device, 9 common electrode (data line), 10 element substrate, 17,117 reflective polarizing layer, 17a prism array, 17b dielectric interference film, 18 polarizing plate (polarizing layer), 25 counter substrate, 31 pixels Electrode, 9a, 31a Open slit, 22R, 22G, 22B Color material layer (color filter), 40 TFD element, 117b Metal reflective film, D1-D3 dot region,

Claims (9)

A transflective liquid crystal display device that sandwiches a liquid crystal layer between a pair of substrates and performs reflective display and transmissive display in one dot region,
The liquid crystal layer includes a liquid crystal having negative dielectric anisotropy in which initial alignment is vertical alignment,
A reflective polarizing layer is provided on the liquid crystal layer side of one of the pair of substrates,
The reflective polarizing layer has a transmission axis and a reflection axis intersecting the transmission axis, and reflects a part of the component parallel to the reflection axis of the incident light and transmits a part thereof. A reflective polarizing layer ,
Among the pair of substrates, on the liquid crystal layer side of at least one of the substrates, an orientation regulating means for regulating the tilt direction of the liquid crystal molecules at the time of voltage application is provided
The liquid crystal display device according to claim 1, wherein the orientation regulating means has a substantially straight line shape in a plan view and extends in a direction intersecting with the reflection axis of the reflective polarizing layer at an angle of about 45 ° .   The liquid crystal display device according to claim 1, wherein the reflective polarizing layer is provided on substantially the entire surface of the dot region.   The liquid crystal display device according to claim 1, wherein the reflective polarizing layer is partially provided in the dot region.   4. The reflective polarizing layer includes a prism array in which a plurality of prisms are arranged, and a dielectric interference film formed on the prism array. The liquid crystal display device described.   The liquid crystal display device according to claim 1, wherein the reflective polarizing layer includes a metal reflective film provided with a plurality of fine slit-shaped openings. A color filter is provided on one of the pair of substrates,
6. The liquid crystal display device according to claim 3, wherein the color filter is partitioned into a plurality of planar regions having different chromaticities within the dot region. 2. The liquid crystal display device according to claim 1, wherein the orientation restricting unit has a substantially triangular wave shape in a plan view extending so as to intersect with a reflection axis of the reflective polarizing layer. A polarizing layer is provided on the substrate provided with the reflective polarizing layer;
The liquid crystal display device according to claim 1 , wherein the polarizing layer is arranged so that a transmission axis thereof is substantially parallel to a reflection axis of the reflective polarizing layer. . An electronic apparatus comprising the liquid crystal display device according to claim 1 .

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