JP5280635B2 - Liquid crystal display - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a liquid crystal display device with which lowering of contrast and black-and-white reversal due to reflection of external light are prevented, in the liquid crystal display device which uses external light and backlight. <P>SOLUTION: The liquid crystal display device is characterized in that it has: a liquid crystal cell 1 comprising a liquid crystal layer 17 interposed between a pair of glass substrates 11, 12; an absorption type polarizing plate 2 disposed on the one glass substrate 11 side of the liquid crystal cell 1; a reflection type polarizing plate 4 disposed on the other glass substrate 12 side of the liquid crystal cell 1; and in modes using external light, a mode using an illuminating means which is controlled with a first control means to apply a voltage to the liquid crystal cell; and a mode using external light controlled with a second control means to apply a voltage to the liquid crystal cell. <P>COPYRIGHT: (C)2008,JPO&amp;INPIT

Description

  The present invention relates to a liquid crystal display device, and more particularly to a liquid crystal display device effective when using external light.

In recent years, liquid crystal display devices have been mounted on various portable information devices such as mobile phones and PDAs (Personal Digital Assistants). In portable information devices, it is necessary to reduce power consumption as much as possible. Therefore, as a liquid crystal display device, a reflective liquid crystal display device or a transflective liquid crystal display device that uses external light as much as possible and suppresses the use of a backlight is used. It is preferable to use (Patent Document 1).
JP 2000-147487 A

  In the reflection mode of such a reflective liquid crystal display device or a transflective liquid crystal display device, for example, no voltage is applied to the liquid crystal cell, and white light is passed through a pair of polarizing plates arranged in a crossed Nicol state. In some cases, display is performed, a voltage is applied to the liquid crystal cell, and external light transmitted along the electric field is absorbed by a pair of polarizing plates arranged in a crossed Nicol state to perform black display.

  However, in the reflection mode of the reflective liquid crystal display device or the transflective liquid crystal display device, when the display control is performed as described above, the liquid crystal panel appears to shine due to the reflection of external light, and the contrast is reduced, or external light is not emitted. There is a problem in that a black and white reversal phenomenon occurs in which the white display appears black without being reflected off the backlight side.

  The present invention has been made in view of the above points, and an object of the present invention is to provide a liquid crystal display device capable of preventing a decrease in contrast and black and white inversion due to reflection of external light in a liquid crystal display device using external light and backlight light. And

The liquid crystal display device of the present invention includes a liquid crystal cell in which a liquid crystal layer is sandwiched between a pair of glass substrates, an absorption polarizing plate disposed on one glass substrate side of the liquid crystal cell, and the other glass of the liquid crystal cell. In a liquid crystal display device comprising: a reflective polarizing plate disposed on a substrate side; and an illuminating unit that makes light incident on the liquid crystal cell from the reflective polarizing plate side, the liquid crystal cell and the reflective polarizing plate during the placing of the polarizing light diffusion plate so that the have a same transmission axis and the reflection-type polarizing plate, the polarizing light diffusing plate substantially birefringence without base resin birefringence having a structure in which rod-shaped resin are dispersed and oriented in one direction, before Symbol a mode using the illumination means controlled by the first control means for applying a voltage to the liquid crystal cell, the voltage to the liquid crystal cell A mode using external light controlled by the second control means to be applied; Characterized in that it has.

According to this configuration, white display is performed in a crossed Nicols state in a reflection mode using external light, so that contrast reduction and black / white reversal due to external light reflection can be prevented. In addition, a polarizing light diffusing plate having the same transmission axis as that of the reflective polarizing plate is disposed between the liquid crystal cell and the reflective polarizing plate, so that less light is regularly reflected in the mode using external light. Therefore, white display can be performed more reliably.

  In the liquid crystal display device of the present invention, the first control means is control means for displaying black when a voltage is applied and displaying white when no voltage is applied, and the second control means is for applying a voltage. It is preferable that the control means provides white display at black and black display when no voltage is applied.

  In the liquid crystal display device of the present invention, the illumination means includes a light source and a light guide plate that guides light from the light source to the liquid crystal cell side, and the light guide plate uses the external light mode. In the above, it is preferable to have a structure in which external light is directed to the light source side. Thereby, in the mode using external light, the amount of light returning to the outside world can be reduced, so that black display can be performed more reliably.

  In the liquid crystal display device of the present invention, the reflective polarizing plate is formed on a transparent resin base material having a grid-like convex part with a pitch of 80 nm to 150 nm on the surface and a region including the grid-like convex part. It is preferable that the wire grid polarizing plate is composed of a simple dielectric layer and a metal wire formed on the dielectric layer.

  According to the liquid crystal display device of the present invention, a liquid crystal cell having a liquid crystal layer sandwiched between a pair of glass substrates, an absorptive polarizing plate arranged on one glass substrate side of the liquid crystal cell, and the other of the liquid crystal cell In a liquid crystal display device comprising: a reflective polarizing plate disposed on the glass substrate side; and an illuminating means for making light incident on the liquid crystal cell from the reflective polarizing plate side, a first voltage for applying a voltage to the liquid crystal cell A mode using the illumination means controlled by the control means and a mode using external light controlled by the second control means for applying a voltage to the liquid crystal cell. In a liquid crystal display device using the above, it is possible to prevent contrast reduction and black-and-white reversal due to external light reflection.

  The present inventor paid attention to the problem of external light reflection in a liquid crystal display device using external light and backlight, that is, in a reflection mode using external light, the liquid crystal panel appears to shine due to external light reflection and the contrast is lowered. We focused on the phenomenon of black-and-white reversal in which the white display appears black without external light being reflected off the backlight.

  Therefore, the present inventor actively utilizes the phenomenon that is considered to be undesirable due to external light reflection as described above, and in the reflection mode using external light, the phenomenon that the liquid crystal panel shines due to external light reflection. By using the white display and performing the black display by utilizing the black and white reversal phenomenon of the white display, that is, by performing the white display in the crossed Nicols state in the reflection mode using the external light, the conventional external light The inventors have found that the problem of reflection can be solved and have come to the present invention.

  That is, the gist of the present invention is a liquid crystal cell in which a liquid crystal layer is sandwiched between a pair of glass substrates, an absorption-type polarizing plate disposed on one glass substrate side of the liquid crystal cell, and the other glass of the liquid crystal cell. In a liquid crystal display device, comprising: a reflective polarizing plate disposed on a substrate side; and an illuminating means for making light incident on the liquid crystal cell from the reflective polarizing plate side. First control for applying a voltage to the liquid crystal cell By means of a liquid crystal display device having a mode using the illumination means controlled by the means and a mode using external light controlled by the second control means for applying a voltage to the liquid crystal cell, external light and backlight In a liquid crystal display device using light, it is to prevent contrast reduction and black / white reversal due to external light reflection.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings.
FIG. 1 is a cross-sectional view showing a liquid crystal display device according to an embodiment of the present invention. The liquid crystal display device shown in FIG. 1 includes a liquid crystal cell 1, an absorption polarizing plate 2 disposed on one side of the liquid crystal cell 1, and a polarizing light diffusing plate 3 disposed on the other side of the liquid crystal cell 1. The reflection type polarizing plate 4, the backlight 5 that is an illuminating means disposed on the reflection type polarizing plate 4 side, and the liquid crystal cell 1 and the control unit 6 that controls the driving of the backlight 5 are mainly configured. Yes.

  The liquid crystal cell 1 is mainly composed of a pair of glass substrates 11 and 12 and a liquid crystal layer 17 sandwiched between the pair of glass substrates 11 and 12. On one main surface of one glass substrate 11, a color filter 18, an electrode 13 and an alignment film 15 are laminated in that order, and on one main surface of the other glass substrate 12, the electrode 14 and The alignment film 16 is laminated in that order. The liquid crystal cell 1 is configured such that glass substrates 11 and 12 are disposed so that the alignment films 15 and 16 face each other, and a liquid crystal layer 17 is interposed therebetween. Therefore, the absorption type polarizing plate 2 is arranged on the other main surface side of the one glass substrate 11 of the liquid crystal cell 1, and the reflection type polarizing plate 4 is arranged on the other main surface side of the other glass substrate 12 of the liquid crystal cell 1. Has been.

  For the color filter 18, the electrodes 13 and 14, and the alignment films 15 and 16, materials used in a normal liquid crystal display device can be used. Moreover, as the absorption-type polarizing plate 2, a normal polarizing plate obtained by adsorbing iodine to a PVA (polyvinyl alcohol) film and stretching the PVA film in a specific direction can be used. The liquid crystal layer 17 employs various methods for improving the viewing angle, such as MVA (Multi-domain Vertical Alignment) method, IPS (In-Plain Switching) method, and OCB (Optically Compensated Birefringence) method. May be.

  A polarizing light diffusing plate 3 having the same transmission axis as that of the reflective polarizing plate 4 is preferably disposed between the liquid crystal cell 1 and a reflective polarizing plate 4 described later. Thereby, in the mode using external light, the light reflected by the reflective polarizing plate 4 can be selectively diffusely reflected, not specularly reflected, so that white display can be performed more reliably. In addition, about a polarizing light diffusing plate, although the material currently disclosed by Japanese translations of PCT publication No. 2002-502503 can be used, there is no birefringence in a film base material, and it has birefringence in a light diffusing agent. Those that exhibit a polarizing light diffusion function are preferred. Such polarizing light diffusers are described in, for example, literature (Hideki Hayashi, Yuko Kazama, Kenro Totani, Noriaki Saito and Toshiyuki Watanabe, “Novel Reflective Type Polarizer Using Birefringent Fibers”, SID 06 DIGEST, pp. 840-843, 2006. As shown in Fig. 2), in the state where stretched fibers having birefringence are arranged in one direction, the space between the fibers has substantially the same refractive index as the fiber stretching direction or the direction perpendicular to the stretching, and substantially no birefringence. Obtained by filling with resin. That is, the polarizing light diffusing plate preferably has a structure in which a rod-like resin having birefringence is oriented and dispersed in one direction in a base resin having substantially no birefringence.

  The reflective polarizing plate 4 includes a transparent resin base material having a grid-like convex portion with a pitch of 80 nm to 150 nm on the surface, a transparent dielectric layer formed on a region including the grid-like convex portion, and a dielectric layer And a metal grid polarizer formed of a metal wire. In such a reflective polarizing plate 4, a transparent resin base material having a grid-like convex portion with a pitch of 80 nm to 150 nm on the surface is prepared, for example, based on the description of Japanese Patent Application Laid-Open No. 2006-224659 of the present applicant. be able to. According to JP 2006-224659 A, using a metal stamper having a concavo-convex grid formed by a grid-shaped convex part having a pitch of 230 nm to 250 nm manufactured using an interference exposure method, the concavo-convex grid is thermally transferred to a thermoplastic resin, The thermoplastic resin provided with the concavo-convex lattice is subjected to free end uniaxial stretching with a stretching ratio of 4 to 6 in the direction parallel to the longitudinal direction of the lattice. As a result, the pitch of the concavo-convex lattice transferred to the thermoplastic resin is reduced, and a resin base material (stretched) having a fine concavo-convex lattice with a pitch of 150 nm or less is obtained. Then, the metal stamper which has a fine uneven | corrugated lattice is produced from the resin base material (drawn | stretched) which has the obtained fine uneven | corrugated lattice using the electrolytic plating method. By using this metal stamper to transfer and form the fine concavo-convex lattice on the surface of the resin base material, it is possible to obtain a resin base material having lattice-like convex portions with a pitch of 150 nm or less. Here, the method of obtaining the resin base material which has a grid | lattice-like convex part is not specifically limited.

  In addition, the polarization direction of the absorption polarizing plate 2 and the polarization direction of the reflective polarizing plate 4 are orthogonal, that is, in a crossed Nicols state.

  The backlight 5 that is an illuminating means is for making light incident on the liquid crystal cell 1 from the reflective polarizing plate 4 side, and includes a light source 51 and a light guide plate 52 that guides light from the light source 51 to the liquid crystal cell 1 side. including. As the light source 51, an LED, a cold cathode tube, or the like can be used. The light guide plate 52 is made of a transparent material such as acrylic resin.

  The control unit 6 applies a voltage to the liquid crystal cell 1 and performs a first control to display black when the voltage is applied, and display white when no voltage is applied, and display white when the voltage is applied. Second control is performed to display black when no voltage is applied. The first control is performed in a mode using the backlight 5, and the second control is performed in a mode using external light. That is, in the mode using external light (reflection mode), the control unit 6 applies a voltage to the liquid crystal cell 1 so as to display white when the voltage is applied and display black when no voltage is applied. In the used mode (transmission mode), a voltage is applied to the liquid crystal cell 1 so as to display black when the voltage is applied and display white when no voltage is applied. Moreover, the control part 6 switches ON / OFF of the light source 51, and switches reflection mode and transmission mode. In the present embodiment, the control unit 6 is configured to perform both the first control and the second control. In the present invention, the control unit 6 includes a first control unit that performs the first control, The structure which provided the 2nd control part which performs 2nd control, respectively may be sufficient.

  As shown in FIG. 4, in the reflection mode (external light mode), the control unit 6 turns off the LED, which is the light source 51, and applies a voltage to the liquid crystal cell 1 when displaying white (ON), thereby displaying black. When this is done, no voltage is applied to the liquid crystal cell 1 (OFF). In the transmissive mode (backlight mode), the LED as the light source 51 is turned on, and no voltage is applied to the liquid crystal cell 1 when displaying white (OFF), and a voltage is applied to the liquid crystal cell 1 when displaying black. (ON). That is, in the liquid crystal display device of the present invention, the drive control in the black and white display is reversed between the reflection mode and the transmission mode. Therefore, as shown in FIG. 5, in the case of the reflection mode (external light mode), a characteristic curve (broken line) in which the transmittance increases as the applied voltage increases is shown, and the transmission mode (backlight mode). In this case, a characteristic curve (solid line) is shown in which the transmittance decreases as the applied voltage increases.

  In addition, for the mode determination of the reflection mode and the transmission mode, for example, a photo sensor is mounted, the light amount is detected by the photo sensor, and the control unit 6 performs the mode determination based on the detection result to switch the mode. (The light source may be turned on / off). For example, when the liquid crystal display device of the present invention is mounted on a mobile phone, a photo sensor is mounted on the mobile phone, and the mode is switched by the detection method as described above.

Next, a display operation in the liquid crystal display device having the above configuration will be described.
FIG. 2 is a diagram showing a light transmission state in the external light mode of the liquid crystal display device according to the embodiment of the present invention, and FIG. 3 is a backlight of the liquid crystal display device according to the embodiment of the present invention. It is a figure which shows the permeation | transmission state of the light in the mode.

  First, the display operation in the external light mode (reflection mode) will be described with reference to FIGS. When black display (black mode) is performed in the external light mode, the controller 6 does not apply a voltage to the liquid crystal cell 1 as shown in FIG. At this time, the light source 51 is also turned off by the controller 6. In this state, as shown in FIG. 2A, since the rubbing directions of the alignment films 13 and 14 are orthogonal to each other, the liquid crystal molecules 17a are twisted by 90 ° between the alignment films 13 and 14 and aligned. Light (external light) incident from the absorption polarizing plate 2 side is converted into linearly polarized light in a specific direction (arrow direction) by the absorption polarizing plate 2. This linearly polarized light is rotated by 90 ° along the alignment twist of the liquid crystal molecules 17 a, passes through the reflective polarizing plate 4 arranged in a crossed Nicol state, is emitted toward the backlight 5, and is scattered back by the backlight 5. Absent. For this reason, the display on the liquid crystal panel is black.

  On the other hand, when white display (white mode) is performed in the external light mode, the controller 6 applies a voltage to the liquid crystal cell 1 as shown in FIG. At this time, the light source 51 is turned off by the controller 6. In this state, as shown in FIG. 2B, the twisted alignment state of the liquid crystal molecules 17a is solved and the liquid crystal molecules 17a are aligned along the electric field. Light (external light) incident from the absorption polarizing plate 2 side is converted into linearly polarized light in a specific direction (arrow direction) by the absorption polarizing plate 2. This linearly polarized light passes through the liquid crystal layer 17 as it is and is reflected by the reflective polarizing plate 4 arranged in a crossed Nicols state. At this time, since the polarizing light diffusing plate 3 is disposed between the liquid crystal cell 1 and the reflective polarizing plate 4, the light reflected by the reflective polarizing plate 4 is in a diffused state. For this reason, the display on the liquid crystal panel is a white display.

  When performing white display (white mode) in the backlight mode, the controller 6 does not apply a voltage to the liquid crystal cell 1 as shown in FIG. At this time, the light source 51 is turned on by the controller 6. In this state, as shown in FIG. 3A, since the rubbing directions of the alignment films 13 and 14 are orthogonal to each other, the liquid crystal molecules 17a are twisted by 90 ° between the alignment films 13 and 14 and aligned. Light (backlight) incident from the reflective polarizing plate 4 side is converted into linearly polarized light in a specific direction (arrow direction) by the reflective polarizing plate 4. This linearly polarized light rotates 90 ° along the alignment twist of the liquid crystal molecules 17a, passes through the absorption polarizing plate 2 arranged in a crossed Nicol state, and is emitted to the outside. For this reason, the display on the liquid crystal panel is a white display.

  On the other hand, when performing black display (black mode) in the backlight mode, the controller 6 applies a voltage to the liquid crystal cell 1 as shown in FIG. At this time, the light source 51 is turned on by the controller 6. In this state, as shown in FIG. 3B, the twisted alignment state of the liquid crystal molecules 17a is released and the liquid crystal molecules 17a are aligned along the electric field. Light (backlight) incident from the reflective polarizing plate 4 side is converted into linearly polarized light in a specific direction (arrow direction) by the reflective polarizing plate 4. This linearly polarized light passes through the liquid crystal layer 17 as it is, and is absorbed by the absorptive polarizing plate 2 arranged in a crossed Nicols state. For this reason, the display on the liquid crystal panel is black.

  In the liquid crystal display device according to the present embodiment, light guide plate 52 preferably has a structure in which external light is directed toward light source 51 in a mode using external light. As a structure for directing external light toward the light source 51, a prism 52a, a protrusion, or the like can be provided on any main surface of the light guide plate 52 as shown in FIG. In this case, the formation position and size of the prism 52 a and the protrusions are appropriately set so that external light is directed to the light source 51. By doing so, this makes it possible to reduce the amount of light that returns to the outside world in a mode that uses external light, so that black display can be performed more reliably.

Next, examples performed for clarifying the effects of the present invention will be described.
(Production of wire grid polarizer)
-Creation of a lattice-shaped convex stamper First, from the fine concavo-convex lattice having a pitch of 230 nm and a fine concavo-convex height of 350 nm using the method described in Japanese Patent Application Laid-Open No. 2006-224659 of the present applicant. A nickel stamper having a pitch and height of the fine concavo-convex grating on the surface of 140 nm / 162 nm, a thickness of 0.3 mm, a length of 300 mm, and a width of 180 mm was produced.

-Production of lattice-shaped convex transfer film using ultraviolet curable resin A COP film (Arton) with a thickness of 100 μm was irradiated with 100 mJ / cm ² of ultraviolet light having a central wavelength of 173 nm to produce a silane coupling agent (Shin-Etsu Chemical). Kogyo Co., Ltd., KBM-5103) A silane coupling agent solution consisting of 0.5 wt%, acetic acid 0.1 wt%, water 20 wt%, ethanol 89.7 wt% was spin-coated and dried. Thereafter, an ultraviolet curable resin (PAK01 manufactured by Toyo Gosei Co., Ltd.) was applied to about 0.01 mm, and a nickel stamper and a film were formed from the ends on the nickel stamper having the fine uneven grating with the 140 nm pitch with the coating surface facing down. The ultraviolet curable resin was cured by irradiating it with 1000 mJ / cm ^{2 of} ultraviolet rays using an ultraviolet lamp having a central wavelength of 365 nm from the COP film side. Then, the COP film was peeled from the nickel stamper to produce a lattice-shaped convex transfer film having a length of 300 mm and a width of 180 mm.

-Formation of dielectric layer using sputtering method An inorganic transparent dielectric material was applied to the obtained ultraviolet curable resin lattice-shaped convex transfer film using a sputtering method. In this example, Si ₃ N ₄ was used as the inorganic transparent dielectric, and Si ₃ N ₄ was deposited on the lattice-shaped convex transfer film produced by the above method. In this case, as a layer thickness comparison sample, a glass substrate having a smooth surface is inserted into the apparatus together with a lattice-shaped convex transfer film, Ar gas pressure is 0.70 Pa, sputtering power is 4 W / cm ² , and lamination speed is 0.20 nm / s. The film was formed so that the Si ₃ N ₄ lamination thickness on the smooth glass substrate was 7 nm.

-Metal vapor deposition using vacuum vapor deposition After laminating Si ₃ N ₄ on the grid-like convex transfer film, metal was deposited using electron beam vacuum vapor deposition (EB vapor deposition). In this example, aluminum (Al) was used as a metal, and aluminum was deposited at a vacuum degree of 2.5 × 10 ⁻³ Pa, a deposition rate of 4 nm / s, and at room temperature. In this case, as a layer thickness comparison sample, a glass substrate having a smooth surface was inserted into the apparatus together with a lattice-shaped convex transfer film, and vapor deposition was performed so that the aluminum deposition thickness on the smooth glass substrate was 200 nm.

・ Elimination of unnecessary metal by etching After depositing Al on the lattice-shaped convex transfer film, the film is washed in 0.1 wt% sodium hydroxide aqueous solution at room temperature for 80 seconds, and then immediately washed with water to stop the etching. I let you. Then, the film was dried and the wire grid polarizing plate was produced. The size of the wire grid polarizing film is 300 mm long and 180 mm wide. When the cross section of the film is observed with a field emission scanning electron microscope, the pitch of the grating is 140 nm, and the height of the formed aluminum wire is 130 nm. The width was 55 nm.

-Polarization performance evaluation using a spectrophotometer The degree of polarization and light transmittance of a wire grid polarizing plate produced using a spectrophotometer were measured. The degree of polarization was 99.97% and the light transmittance was 41.2%. . Here, the light transmittance in the parallel Nicols state and the direct Nicols state with respect to the linearly polarized light was measured, and the degree of polarization was calculated from the following formula. The measurement wavelength range was 400 nm to 800 nm as visible light, and the weighted average value corresponding to the visibility for each wavelength was adopted for the degree of polarization and the light transmittance.
Polarization degree = (Imax−Imin) / (Imax + Imin)
Here, Imax is the transmitted light intensity at the time of parallel Nicols, and Imin is the transmitted light intensity at the time of crossed Nicols.

(Production of liquid crystal display device)
The liquid crystal display device shown in FIG. 1 was assembled using the obtained wire grid polarizing plate, a TN liquid crystal cell used for a commercially available mobile phone, and a sidelight type backlight. In the mode using the backlight (transmission mode), the display is black when the voltage is applied and white when the voltage is not applied. As the reflective polarizing plate 4, a wire grid polarizing plate is used, and as the polarizing light diffusing plate 3, the PET fiber content of 180 μm in thickness is obtained from a PET fiber having a diameter of 3 μm and an ultraviolet curable resin by the manufacturing method shown in the above-mentioned document. A film was prepared and used in such a way that the amount of the liquid was about 60% by volume. A light guide plate having a cross-sectional shape shown in FIG. 6 is used for the sidelight type backlight so that light from the LED serving as the light source is reflected mainly by the prism shape provided on the surface of the light guide plate and directed toward the liquid crystal cell. .

Example 1
When the polarizing light diffusing plate 3 is inserted into the liquid crystal display device and light is irradiated from outside the liquid crystal display device with the light source 51 turned off as an external light mode, a black display is obtained in the absence of voltage application, and voltage application is performed. White display was obtained in the state, and uniform white display was obtained at an angle within 45 degrees from the perpendicular to the liquid crystal display surface. In the backlight mode, when the light source 51 was turned on, white display was obtained when no voltage was applied, and black display was obtained when the voltage was applied. In addition, even when an image signal is input to the liquid crystal display device, a good image display can be obtained by performing the drive control according to the present invention in the external light mode and the backlight mode.

(Example 2)
When the display was evaluated in the same manner as in Example 1 without inserting the polarizing light diffusing plate 3 into the liquid crystal display device, black and white display and image display were favorably obtained. However, the white display in the external light mode was inferior in homogeneity compared to Example 1 due to the direction of the external light.

  The present invention is not limited to the embodiment described above, and can be implemented with various modifications. In the said embodiment, about a polarizing plate and a polarizing light diffusing plate, it is not limited to a plate-shaped thing, It shall be a film-like body and a sheet-like thing. In the above embodiment, the case where monochrome display is performed in the liquid crystal display device has been described. However, halftone display can be performed by changing the voltage level. Even in this case, in the external light mode, the voltage is controlled based on a characteristic curve (broken line) in which the transmittance increases as the applied voltage increases.

  In addition, the dimensions, materials, and the like in the above embodiment are illustrative, and can be implemented with appropriate changes. In addition, various modifications can be made without departing from the scope of the present invention.

It is sectional drawing which shows the liquid crystal display device which concerns on embodiment of this invention. (A), (b) is a figure which shows the permeation | transmission state of the light in the case of the external light mode of the liquid crystal display device which concerns on embodiment of this invention. (A), (b) is a figure which shows the permeation | transmission state of the light in the backlight mode of the liquid crystal display device which concerns on embodiment of this invention. It is a figure which shows the control aspect of the control part in the liquid crystal display device which concerns on embodiment of this invention. It is a figure which shows the relationship between the applied voltage and the transmittance | permeability in the liquid crystal display device which concerns on embodiment of this invention. It is a figure which shows the other example of the light-guide plate of the backlight in the liquid crystal display device which concerns on embodiment of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Liquid crystal cell 2 Absorption type polarizing plate 3 Polarizing light diffusing plate 4 Reflective type polarizing plate 5 Backlight 6 Control part 11,12 Glass substrate 13,14 Electrode 15,16 Alignment film 17 Liquid crystal layer 17a Liquid crystal molecule 18 Color filter 51 Light source 52 Light guide plate 52a Prism

Claims (4)

A liquid crystal cell in which a liquid crystal layer is sandwiched between a pair of glass substrates, an absorptive polarizing plate disposed on one glass substrate side of the liquid crystal cell, and a reflective type disposed on the other glass substrate side of the liquid crystal cell In the liquid crystal display device comprising: a polarizing plate; and an illuminating unit that makes light incident on the liquid crystal cell from the reflective polarizing plate side, the reflective polarizing plate is provided between the liquid crystal cell and the reflective polarizing plate. the same transmission axis arranged polarizing light diffusion plate so that the have a, the polarizing light diffusing plate rod-like resin having a birefringence in one direction during substantially no birefringence base resin and orientation to a dispersed structure, before Symbol a mode using the illumination means controlled by the first control means for applying a voltage to the liquid crystal cell, a second control means for applying a voltage to the liquid crystal cell A mode using external light to be controlled Crystal display device.   The first control means is a control means that displays black when a voltage is applied and displays white when a voltage is not applied. The second control means displays white when a voltage is applied, and the voltage is not applied. 2. The liquid crystal display device according to claim 1, wherein the liquid crystal display device is a control means for displaying black. The illumination means includes a light source and a light guide plate that guides light from the light source to the liquid crystal cell side, and the light guide plate transmits external light to the light source side in the mode using the external light. The liquid crystal display device according to claim 1, wherein the liquid crystal display device has a structure to be directed. The reflective polarizing plate includes a transparent resin base material having a grid-like convex portion with a pitch of 80 nm to 150 nm on the surface, a transparent dielectric layer formed on a region including the grid-like convex portion, and the dielectric The liquid crystal display device according to any one of claims 1 to 3 , wherein the liquid crystal display device is a wire grid polarizing plate composed of a metal wire formed on a layer.

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