JP4358044B2 - Liquid crystal display - Google Patents

Description

  The present invention relates to a liquid crystal display device, and more particularly to a transmissive liquid crystal display device having a micro-reflection function.

  As a liquid crystal display device, a transflective type (two-way display type) that performs both a reflective display that uses outside light such as natural light and room light and a transmissive display that uses illumination light from a backlight. There is a liquid crystal display device.

  This transflective liquid crystal display device performs a reflective display using outside light when sufficient brightness is obtained, and turns off a backlight when sufficient brightness is not obtained. The display is turned on to perform transmissive display using the illumination light. In the case of a reflective display that uses external light, display is performed by reflecting the external light incident from the front side of the display means by the transflective reflector, and transmitting again through the display means, and from the backlight. In the transmissive display using the illumination light, light transmitted through the transflective plate among the illumination light becomes incident light to the display means, and the light is transmitted through the display means and emitted. Is displayed.

  Two types of transflective liquid crystal display devices have been developed and put into practical use: an outside-cell reflector type and an in-cell reflector type. Specifically, the outside-cell reflection plate method is a method in which a transflective plate is attached to the back of a polarizing plate and switching between transmission and reflection is performed by turning the backlight on / off. The in-cell reflection plate method is a method in which a reflection plate made of a metal thin film is provided in a cell in accordance with full color formation in which a color filter is provided for each pixel. As the reflection plate, a half mirror made of a metal thin film or a type in which a hole is formed in a metal film is used.

  Conventionally, the transflective liquid crystal display device having such a method has a problem that a bright display cannot be obtained when using outside light or using light of an illumination panel, or illumination light. In the case of the transmissive display to be used, a sufficient screen luminance can be obtained, but in the case of the reflective display using the external light, there is a problem that the luminance of the screen is not sufficient. For this reason, transflective liquid crystal display devices place importance on the use of reflection under external light by developing the following technology.

  First, there is a technique disclosed in Patent Document 1 as a combination of two back-illuminated light guides. In Patent Document 1, the first light guide, which is a light guide disposed on the rearmost surface, is a light guide having a stepped shape, and a substantially horizontal surface is reflected with respect to the liquid crystal panel having the stepped structure. A film is provided, and the vertical surface transmits light. The second light guide disposed on the first light guide has a unique shape. A technique is disclosed that has a function of capturing light from a first light guide and a function of irradiating light transmitted from a liquid crystal panel onto a horizontal surface provided with a reflective film of the first light guide. ing.

  In addition, whether it is a reflective display that uses external light or a transmissive display that uses illumination light, the screen brightness is sufficient for the illuminance of the usage environment, and the quality is almost the same. As a transflective liquid crystal display device capable of displaying an image, there is a technique disclosed in Patent Document 2. In Patent Document 2, modulation is performed using polarized light reflected from a polarizing reflector using a polarizing reflector.

  In addition, the liquid crystal display device disclosed in Patent Document 3 is light that is transmitted between the liquid crystal display means and the backlight and is reflected to the front side by the backlight through the back side of the polarizing reflection plate during the reflective display. A technique is disclosed in which a contrast compensation polarizing plate that doubles the intensity of light is arranged. The aim is to improve contrast by arranging a polarizing plate for contrast compensation.

Further, in the conventional transflective liquid place display element, Patent Document 4 discloses a technique for solving the problem that the display becomes difficult to see when external light enters the display device when the light source is turned on due to so-called positive / negative reversal. In the disclosed technique, there is a display device having a structure in which a light scatterer is provided below a TN (twisted nematic) liquid crystal panel and a polarization separator is provided below the light scatterer. As in the conventional structure, the negative display and the black display are inverted between the transmissive display with the backlight provided under the liquid crystal display element and the reflective display without using the backlight, but it is brighter than the conventional display. The display is realized.
JP 11-183729 A (publication date: September 14, 2001) JP 2000-180819 A (publication date: June 30, 2000) JP 2000-180835 A (publication date: June 30, 2000) Pamphlet of International Publication No. 98/12594 (Release Date: March 26, 1998)

  As described above, two types of transflective liquid crystal display devices have been developed and put into practical use, that is, an out-cell reflector type and an in-cell reflector type. However, the above-mentioned outside-cell reflector method, in which a transflective plate is attached to the back of the polarizing plate and switching between transmission and reflection by turning the backlight on / off, has poor light utilization efficiency, and backlighting (backlight) There is a problem that the use efficiency of is poor. Furthermore, since a double image is generated due to the thickness of the glass substrate, the usage is limited to a black-and-white panel, and there is a problem that color mixing due to a shadow occurs in a display provided with a color filter.

  Further, until now, when a transflective plate is provided in a pixel, if the transmissive display is regarded as important, it is necessary to make the reflective plate a thin film or to enlarge a hole provided in the reflective film. However, the configuration in which the reflective film is provided in the pixel leads to an increase in cost, and the configuration in which a hole is further formed in the reflective film leads to an increase in cost with processing.

  Moreover, although patent document 1 is a display apparatus which combined two light guides of back lighting and was able to take in external light efficiently, since it has the light guide body of a complicated structure as mentioned above, The thickness of the display device itself increases, and the cost for manufacturing the light guide is inevitable.

  In Patent Document 2, it is necessary to perform negative / positive reversal in transmissive display and reflective display. Furthermore, since the light diffused by the scattered light via the diffusion plate is used in the reflective display, the contrast is lowered. This is because the diffusing plate is on the light guide plate on the rear side of the reflective polarizing plate, and linearly polarized light transmitted through the polarizing reflective plate (has linear vibration and a vertical vibration surface reflected by the reflective polarizing plate). Is based on the fact that the degree of polarization of the reflected polarized light is reduced by being reflected and diffused by the light guide plate and overlapping with the reflected polarized light of the reflective polarizing plate even if it passes through the reflective polarizing plate again.

  The liquid crystal display device disclosed in Patent Document 3 is provided with a contrast compensation polarizing plate between the polarizing reflector and the light guide plate in order to prevent a decrease in contrast. Since only the specular reflection of the reflector is made, the viewing angle is remarkably narrowed.

  Further, in Patent Document 4, since a polarization separator is used, it is inevitable that negative / positive reversal is involved during transmission when the backlight is turned on and when reflection is performed using external light. Further, particularly when the external light intensity and the transmitted light intensity are equal, the brightness and darkness cancel each other. Therefore, there is a problem that display cannot be performed.

  As described above, in the conventional technology, the cost is significantly increased, the thickness of the display device itself is increased, the negative / positive inversion circuit is required, the contrast is significantly decreased, or the viewing angle is decreased, and the external light intensity and the transmitted light intensity are increased. There is a problem that cannot be displayed when they are equal.

  As disclosed in Patent Document 1 and Patent Document 2, in recent years, the performance of both the reflective display type and the transmissive display type has been improved, and a device has been devised so that a good display can be achieved with either display type. However, in actual use, the transmissive display in which the backlight is lit is better in appearance than the reflective display. There is a demand for a liquid crystal display device having a fine reflection function and emphasizing transmission type display.

  However, if this is to be realized with the liquid crystal display device disclosed in the above-mentioned patent document, as described above, a significant increase in cost, an increase in thickness, a negative / positive inversion circuit is required, a significant reduction in contrast, or The viewing angle is reduced.

  Therefore, the present invention has been made in view of the above-described problems, and its purpose is to solve the above-described problems and emphasize fine transmission type display while providing fine reflection even when using external light. An object of the present invention is to provide a liquid crystal display device capable of confirming display contents.

  In order to solve the above-described problems, the liquid crystal display device according to the present invention is an optical that transmits polarized light having a predetermined polarization vibration surface between a liquid crystal layer and a light source that emits light toward the liquid crystal layer. In a liquid crystal display device including a polarizing plate having an axis, light having a polarization vibration plane parallel to the polarization transmission axis is transmitted between the polarizing plate and the light source, and a polarization vibration plane perpendicular to the polarization transmission axis is provided. A polarizing reflector that reflects the light, and the polarizing reflector is disposed such that the polarization transmission axis is opposed to the polarizing plate at a predetermined angle with the optical axis. A light scattering layer for scattering incident light is provided between the light scattering layer and the polarizing plate, and a light diffusion layer for diffusing incident light is provided between the light scattering layer and the polarizing reflector. The light diffusion layer is a gas layer, and the thickness of the light diffusion layer is 0. And wherein the at 1mm or 0.2mm or less.

In order to solve the above-described problem, a liquid crystal display device according to the present invention transmits polarized light having a predetermined polarization vibration surface between a liquid crystal layer and a light source that emits light toward the liquid crystal layer. In a liquid crystal display device including a polarizing plate having an optical axis, a polarizing vibration surface that transmits light having a polarization vibration plane parallel to the polarization transmission axis between the polarizing plate and the light source and is perpendicular to the polarization transmission axis. A polarizing reflection plate that reflects light having a polarization direction, the polarizing reflection plate being arranged so that the polarization transmission axis forms a predetermined angle with the optical axis and faces the polarizing plate. A light scattering layer that scatters incident light is provided between the plate and the liquid crystal layer.

With the above-described configuration, the liquid crystal display device related to the present invention can cause slight reflection while placing importance on transmissive display. Therefore, even when the light source is not turned on, the display content displayed on the liquid crystal layer can be confirmed by using external light.

Specifically, in the liquid crystal display device related to the present invention, when the light source is not lit, out of the external light captured from the outside, the polarized light having the polarization oscillation direction parallel to the optical axis of the polarizing plate (outside Light) passes through the polarizing plate and enters the polarizing reflector. Since the optical axis and the polarization transmission axis are at a predetermined angle, a part of the polarized light that has been transmitted through the polarizing plate and incident on the polarizing reflecting plate has a polarization vibration plane that is the polarization reflecting plate. It does not coincide with the polarization vibration plane parallel to the polarization transmission axis. Therefore, the polarized light does not pass through the polarizing reflector and is reflected by the polarizing reflector. The reflected polarized light again enters the polarizing plate and passes through the liquid crystal layer. As described above, the liquid crystal display device according to the present invention corresponds to the amount of deviation because the optical axis of the polarizing plate and the polarization transmission axis of the polarizing reflecting plate are deviated from each other by a predetermined angle. Even if the light source is not turned on by the reflected light of the outside light, the display content displayed on the liquid crystal layer can be confirmed. That is, the liquid crystal display device related to the present invention can obtain a fine reflection function for performing display by slightly reflecting external light by adopting the above-described configuration.

  In the present invention, “micro-reflection” means that the optical axis of the polarizing plate and the polarization transmission axis of the polarizing reflecting plate are shifted from each other by a predetermined angle as described above. It is a reflection.

In addition, the liquid crystal display device related to the present invention does not include, for example, a component having a reflection function such as a polarizing reflector, and has a fine reflection function using reflection of light incident on a backlight unit such as a light source. The luminance is improved as compared with the case where it is realized.

  Specifically, external light that is taken in from outside, passes through a liquid crystal layer, a light scattering layer, a polarizing plate, and a polarizing reflection plate and enters a backlight including a light source is incident on the polarizing reflection plate again. Of the incident light, light having a polarization vibration plane parallel to the polarization transmission axis of the polarization reflection plate can be transmitted through the polarization reflection plate, and light having a vertical polarization vibration surface is reflected again toward the backlight unit. . The light reflected again in the direction of the backlight unit is repeatedly reflected by the polarization reflector and the backlight unit until it becomes light having a polarization vibration plane parallel to the polarization transmission axis of the polarization reflector. The polarized light reflected by the backlight unit and transmitted through the polarizing reflector also contributes to bright display. In other words, since the polarizing reflector does not have an absorption axis, when a part of the light transmitted through the polarizing reflector is reflected by the backlight unit, the reflection can be repeated until it is transmitted through the polarizing reflector again and used for bright display. .

  On the other hand, when the reflected light reflected by the backlight unit is used for a reflective display without providing a polarizing reflector, the reflected light reflected by the backlight unit is incident on the polarizing plate. Of the obtained light, light having a polarization vibration plane parallel to the optical axis of the polarizing plate can be transmitted, but light having a polarization vibration plane perpendicular to the optical axis is absorbed by the polarizing plate. Therefore, the light that can be used for bright display in the micro-reflection display is only the first reflected light that is reflected by the backlight and transmitted through the polarizing plate, so that the light use efficiency is low and good fine reflection can be realized. Can not.

Therefore, the liquid crystal display device related to the present invention displays not only the reflected light caused by the deviation between the polarization transmission axis and the optical axis, but also the reflected light transmitted through the polarization reflector and reflected by the backlight unit. Since it contributes, in addition to being able to display by microreflection using external light, the utilization efficiency of external light is high.

In addition, the liquid crystal display device related to the present invention includes a light scattering layer between the polarizing reflection plate and the liquid crystal layer, so that the content displayed on the liquid crystal layer is taken into the polarization reflection plate by taking in external light. In the case of confirming using the light reflected (fine reflection), the light reflected by the polarization reflector can be diffused. Therefore, the liquid crystal display device related to the present invention has a wide viewing angle and can realize a display with good fine reflection.

Specifically, when the content displayed on the liquid crystal layer is confirmed using external light taken in and reflected by the polarizing reflector, the external light taken into the liquid crystal display device related to the present invention. Passes through the liquid crystal layer, enters the light scattering layer, scatters, and enters the polarizing reflector. Of the polarized light that has entered the polarizing reflector, the polarized light that has entered the deviation portion of the polarizing transmission plate between the polarization transmission axis and the optical axis is reflected by the polarizing reflector and is incident on the light scattering layer again and scattered. Therefore, since the polarized light that is specularly reflected by the polarizing reflector is scattered by the light scattering layer, it is possible to distribute light in directions other than the specular reflection direction. Therefore, the viewing angle can be enlarged, and better fine reflection display can be realized.

Thus, the liquid crystal display device related to the present invention can cause good fine reflection using external light while placing importance on transmissive display, so even if the light source is not turned on, The display content displayed on the liquid crystal layer can be confirmed.

  In the above-described configuration, the case where the polarization transmission axis of the polarizing reflector matches the optical axis of the polarizing plate is excluded from the predetermined angle. This is because if the polarization transmission axis of the polarizing reflection plate and the optical axis of the polarizing plate coincide with each other, a fine reflection type display cannot be performed.

  In the liquid crystal display device according to the present invention, it is preferable that the polarizing reflection plate is disposed so that the polarization transmission axis forms an angle of 10 degrees or more and 20 degrees or less with the optical axis.

  With the above-described configuration, the liquid crystal display device according to the present invention can have characteristics of a transmittance of 90% or more and a reflectance of 3% or more.

  Therefore, the liquid crystal display device according to the present invention is provided with a fine reflection function in which the content displayed on the liquid crystal layer can be confirmed by taking in external light while placing importance on the transmissive display.

  The liquid crystal display device according to the present invention preferably includes a light diffusion layer for diffusing incident light between the polarizing plate and the polarizing reflector. The light diffusion layer is preferably disposed adjacent to the polarizing reflector. Further, the light diffusion layer is preferably a gas layer.

  With the above-described configuration, when display is performed by slightly reflecting external light, the light that enters the liquid crystal layer from the outside of the liquid crystal display device and passes through the polarizing plate does not reach the polarizing reflector. Light can be reflected from the surface of the light diffusion layer and incident again on the polarizing plate.

  Thereby, when performing display by fine reflection, in addition to the reflected light by the above-described fine reflection, the reflected light on the surface of the light diffusion layer can be used, so the reflectance of external light can be increased, Good display can be performed.

  Further, with the above-described configuration, the light that enters the liquid crystal layer from the outside of the liquid crystal display device and has a polarization vibration plane parallel to the optical axis of the polarizing plate, that is, out of the light that passes through the polarizing plate. Even light having a polarization vibration plane parallel to the polarization transmission axis of the polarization reflection plate can be diffused and reflected by the polarization reflection plate by changing the polarization vibration plane.

  Thereby, the utilization efficiency of external light, that is, the reflectance is further increased, and a good display can be performed.

  In the liquid crystal display device according to the present invention, the light scattering layer is preferably provided between the polarizing plate and the polarizing reflector.

  By adopting the above-described configuration, when the content displayed on the liquid crystal layer is confirmed using light (fine reflection) that has taken in external light and reflected by the polarizing reflector, the polarizing plate is transmitted through Of the polarized light incident on the polarizing reflector, the light reflected by the polarizing reflector can be scattered and uniformly incident on the surface of the polarizing plate. Therefore, the viewing angle is increased, and a good fine reflection display can be realized.

  In the liquid crystal display device according to the present invention, the light scattering layer is preferably disposed adjacent to the light diffusion layer.

  With the above-described configuration, since the light diffusion layer and the light scattering layer are stacked, the difference in refractive index between the light diffusion layer and the light scattering layer is maximized, and the light scattering effect is enhanced. Therefore, when the content displayed on the liquid crystal layer is confirmed using light reflected from the polarizing reflector by taking in external light, the light transmitted through the polarizing plate and reflected by the polarizing reflector is more It is efficiently diffused, and a good display by slight reflection can be realized.

  In addition, the liquid crystal display device according to the present invention preferably includes a second polarizing plate having an optical axis perpendicular to the optical axis of the polarizing plate on the side opposite to the light source side of the liquid crystal layer.

  With the above-described configuration, the liquid crystal display device according to the present invention includes the polarizing plate and the second polarizing plate on both sides of the liquid crystal layer. Bright display or dark display is not reversed when voltage is applied to the liquid crystal layer or when no voltage is applied. That is, it does not cause negative / positive reversal.

  Therefore, it is not necessary to provide a negative / positive inversion circuit.

As described above, the display element related to the present invention is a polarized light having an optical axis that transmits polarized light having a predetermined polarization vibration plane between the liquid crystal layer and a light source that emits light toward the liquid crystal layer. In a liquid crystal display device having a plate, light having a polarization vibration plane parallel to the polarization transmission axis is transmitted between the polarizing plate and the light source, and light having a polarization vibration plane perpendicular to the polarization transmission axis is reflected. The polarizing reflector is arranged such that the polarization transmission axis is opposed to the polarizing plate at a predetermined angle with the optical axis, and the polarizing reflector, the liquid crystal layer, A light scattering layer for scattering incident light is provided between the two.

With the above-described configuration, the liquid crystal display device related to the present invention can cause slight reflection while placing importance on transmissive display. Therefore, even when the light source is not turned on, the display content displayed on the liquid crystal layer can be confirmed by using external light.

In the liquid crystal display device related to the present invention, the optical axis of the polarizing plate and the polarization transmission axis of the polarizing reflecting plate are shifted by a predetermined angle, so that the deviation of the polarized light transmitted through the polarizing plate is shifted. The light incident on the part is reflected by the polarizing reflector. The display content displayed on the liquid crystal layer can also be confirmed by the reflected light.

  Specifically, the optical axis and the polarization transmission axis form an angle in the range of 10 degrees to 20 degrees. Since the mutual axes are slightly shifted as in the above range, the liquid crystal display device according to the present invention is displayed on the liquid crystal layer by taking in external light while placing importance on the transmissive display. It is possible to realize a fine reflection function that the contents can be confirmed.

  Furthermore, by providing a light scattering layer between the polarizing reflection plate and the liquid crystal layer, it is possible to scatter the light that has taken in external light and has been specularly reflected by the polarizing reflection plate. Therefore, it is possible to provide a liquid crystal display device that has a wide viewing angle and can realize display with good fine reflection.

  One embodiment of the present invention will be described with reference to FIGS. 1 to 7 as follows. However, the present invention is not limited to this.

  FIG. 1 is a schematic view showing a configuration of a liquid crystal display device according to an embodiment of the present invention. A liquid crystal display device 1 shown in FIG. 1 is provided in, for example, a mobile phone, and normally performs transmissive display using illumination light from a light source 15 provided in the liquid crystal display device 1. Even when there is no light, that is, when transmissive display is not performed, information displayed on the liquid crystal display device 1 can be confirmed by performing reflective display using external light.

  Specifically, when the liquid crystal display device 1 performs a transmissive display, the illumination light emitted by turning on the lamp 2 provided in the liquid crystal display device 1 is applied to the polarizing reflector 6 or the light source side polarizing plate. The information formed on the liquid crystal panel 11 is displayed to the user by transmitting through the (polarizing plate) 9 and transmitting through the liquid crystal panel (liquid crystal layer) 11. On the other hand, when the liquid crystal display device 1 performs reflective display, outside light enters the liquid crystal display device 1 and passes through the liquid crystal panel 11 and the light source side polarizing plate 9 to be described later. 6, reflected by the polarizing reflector 6 and the light source 15, transmitted through the light source side polarizing plate 9 again, and transmitted through the liquid crystal panel 11, information formed on the liquid crystal panel to the user. Can be displayed. Therefore, as shown in FIG. 1, the liquid crystal display device 1 includes a lamp 2, a light guide plate 3, a scattering plate 4, a prism sheet 5, a polarizing reflection plate 6, an air layer (light diffusion layer, gas layer). ) 7, the light scattering layer 8, the light source side polarizing plate 9, the first retardation plate 10, the liquid crystal panel 11, the second retardation plate 12, and the external light incident side polarizing plate (second Polarizing plate) 13 and an adhesive material layer 14. The lamp 2 and the light guide plate 3 constitute a light source 15.

  In the liquid crystal display device 1, the scattering plate 4, the prism sheet 5, and the polarization reflection plate 6 are arranged in this order above the light guide plate 3, that is, along the light emission direction of the light guide plate 3. Further, an air layer 7 and a light scattering layer 8 are disposed on the polarizing reflection plate 6. On the light scattering layer 8, a light source side polarizing plate 9, a first retardation plate 10, a liquid crystal panel 11, a second retardation plate 12, and an external light incident side polarizing plate 13 are provided. They are arranged in this order via the adhesive material layer 14.

  The lamp 2 is disposed on the side surface of the light guide plate 3 as shown in FIG. 1, and is used when performing transmissive display. As the lamp 2, a conventionally known lamp can be used, and for example, an LED or a cold cathode tube can be used.

  In the present embodiment, the lamp 2 is disposed on the side surface of the light guide plate 3, and each component member is disposed above the light guide plate 3 through the light guide plate 3 with irradiation light emitted from the lamp 2. However, the present invention is not limited to this. For example, the lamp is used together with the reflecting member, the light source side polarizing plate 9, and the first phase difference. A configuration such as a direct light type disposed below the plate 10 or the liquid crystal panel 11 may be used.

  As described above, the light guide plate 3 irradiates the light emitted from the lamp 2 disposed on the side surface of the light guide plate 3 with the light source side polarizing plate 9 disposed above the light guide plate 3 and the first light guide plate 3. For irradiating in the direction of the phase difference plate 10 and the liquid crystal panel 11. As the light guide plate 3, a conventionally known material can be used.

  The scattering plate 4 scatters the irradiation light incident from the light guide plate 3 so that the irradiation light emitted from the light guide plate 3 is uniformly irradiated to the constituent members stacked on the scattering plate 4. Is provided. As the scattering plate 4, a scattering plate that can be emitted without canceling the polarization state of incident light as much as possible is used.

  The prism sheet 5 is provided to collect the irradiation light scattered by the scattering plate 4. As the prism sheet 5, a conventionally known material can be used.

  The polarization reflector 6 reflects or transmits the linearly polarized light incident from the prism sheet 5. The polarization reflector 6 will be described in detail as follows.

  The polarizing reflector 6 has a polarization transmission axis on its light incident surface. The polarizing reflector 6 transmits polarized light having a polarization vibration plane substantially parallel to the polarization transmission axis (hereinafter referred to as polarization P), and has a polarization vibration plane substantially perpendicular to the polarization transmission axis. The polarized light (hereinafter referred to as polarized light S) is reflected. In the following description, the polarized light that can be transmitted through the polarizing reflector 6 is simply referred to as “polarized light parallel to the polarization transmission axis”. Further, the polarized light reflected by the polarizing reflector 6 is simply referred to as “polarized light perpendicular to the polarization transmission axis”.

  As described above, the trans-reflection plate system of the conventional transflective liquid crystal display device is a system in which a transflective plate is pasted on a polarizing plate and switching between transmission and reflection is performed by turning on / off the backlight. It is. The transflective plate reflects and transmits light at a constant ratio regardless of the polarization vibration plane. When the transflective plate and the polarizing reflector are compared under the same arrangement conditions, a difference is seen in the effect.

  More specifically, for example, the transflective plate and the polarizing reflector are respectively (i) an external light incident side polarizing plate, a liquid crystal layer, a light source side polarizing plate, and a transflective plate. It is assumed that the liquid crystal display device is laminated in this order, and (ii) an external light incident side polarizing plate, a liquid crystal layer, a light source side polarizing plate, and a polarizing reflection plate are laminated in this order. In the following, the light utilization efficiency in the case of using the external light of the liquid crystal display devices having the above configurations (i) and (ii) will be described.

  First, from the configuration (i) provided with the above-described transflective plate, polarized light that has passed through the liquid crystal layer, the light source side polarizing plate, and the transflective plate in order from the external light incident side polarizing plate having the configuration (i). Is incident on a backlight unit, etc., and is reflected and refracted. The reflected and refracted light becomes mixed light (S + P) in which the polarization vibration surfaces S and P are mixed. The mixed light (S + P) is incident again on the transflective plate and returns. The mixed light (S + P) transmitted through the transflective plate is incident on the light source side polarizing plate. In the light source side polarizing plate, polarized light P of the incident mixed light (S + P) is transmitted through the light source side polarizing plate. However, the polarized light S is absorbed by the light source side polarizing plate.

  Next, the configuration of (ii) provided with the polarizing reflector will be described. In order from the external light incident side polarizing plate having the configuration of (ii), the liquid crystal layer and the light source side polarizing plate are sequentially transmitted. The polarized light P that has passed through is incident on a backlight unit such as a light source, and is reflected and refracted. The light reflected and refracted by the backlight unit or the like becomes mixed light (S + P) as in the configuration (i) described above. This mixed light (S + P) is incident again on the polarizing reflector. Of the mixed light (S + P) incident on the polarizing reflector, the polarized light P parallel to the polarization transmission axis of the polarizing reflector passes through the polarizing reflector and further passes through the light source side polarizing plate. On the other hand, the polarized light S substantially perpendicular to the polarized light transmission axis does not pass through the polarized light reflector and is reflected again to the backlight unit or the like. The reflected polarized light S is repeatedly reflected and / or refracted between the backlight unit and the polarizing reflector plate to become mixed light (S + P), and the above is repeated, and as a result, reflected to the backlight unit or the like. The polarized light S is also polarized into the polarized light P and sequentially passes through the polarizing reflector.

  That is, of the mixed light (S + P) reflected and refracted by the backlight unit or the like, the configuration of (i) including the transflective plate in which the polarized light S is absorbed by the light source side polarizing plate is obtained by re-polarizing the polarized light. Since it cannot be used, the reflection efficiency decreases.

  On the other hand, by including the polarizing reflection plate and having the configuration (ii), the mixed light (S + P) reflected and refracted by the backlight unit or the like can be efficiently reused. A display with fine reflection can be realized.

  Therefore, the liquid crystal display device according to the present embodiment, which aims at providing a fine reflection function while placing importance on the transmissive display, includes the polarization reflector 6 as shown in FIG. We are trying to improve.

  In addition, since the liquid crystal display device 1 includes the polarization reflection plate 6, the light use efficiency is improved, and thus it is possible to suppress the reduction in brightness in the case of the transmissive display type.

  Specifically, in the case of transmissive display, when illumination light is emitted from a backlight unit including the light source 15, the scattering plate 4, and the prism sheet 5, the illumination light is polarized P and S by the polarization reflector 6. Separated. The polarized light P is transmitted through the polarizing reflector 6. On the other hand, the polarized light S is reflected by the polarizing reflector 6 and returns to the backlight unit, and is reflected and refracted by the backlight unit in the same manner as described above. Of the mixed light (S + P), the polarized light P is the polarized light reflector 6. The polarized light S is also reflected and / or refracted between the backlight unit and the polarizing reflector 6 to become polarized light P and is transmitted through the polarized reflector 6. Can be used.

  On the other hand, in the case where the transflective plate as in (i) above is used, the polarized light S of the mixed light (S + P) obtained by reflection and refraction by the backlight unit is the light source side polarizing plate as described above. Will be absorbed.

  Therefore, the liquid crystal display device 1 can be provided with the polarizing reflection plate 6 to suppress the brightness reduction in the case of the transmissive display type.

  As the polarizing reflector 6, for example, Sumitomo 3M DBEF can be used. In an example described later, Sumitomo 3M DBEF is used for the polarizing reflector 6 so that the polarization transmission axis has a crossing angle of 12 degrees with the optical axis, and a gap 0 between the light source side polarizing plate 9 is used. .2 mm (air layer 7) is provided. However, the present invention is not limited to this.

  In addition, as shown in FIG. 1, the air layer 7 can diffuse light incident on the liquid crystal panel 11 from the outside and transmitted through the light source side polarizing plate 9, and the light scattering with the polarizing reflector 6. It is provided between the layers 8.

  Specifically, by providing the air layer 7, the surface reflected light of the polarizing reflector 6 can be used. That is, the air layer 7 is incident on the outside, passes through the light source side polarizing plate 9, and transmits polarized light that does not reach the polarizing reflector 6 out of the light scattering layer 8. The light can be reflected at the surface, that is, at the interface between the light scattering layer 8 and the air layer 7.

  Therefore, by providing the air layer 7 between the polarizing reflector 6 and the light scattering layer 8, the reflectance of external light can be increased, and the reflective display can be performed more favorably.

  In addition, the air layer 7 is incident on the outside, and out of the light having a polarization vibration plane parallel to the optical axis of the light source side polarizing plate 9, that is, out of the light transmitted through the light source side polarizing plate 9, the polarizing reflection plate 6. Even light having a polarization vibration plane parallel to the polarization transmission axis can be diffused to change the polarization vibration plane so that it can be reflected by the polarization reflector.

  As a result, the reflectance of the external light is further increased and the utilization efficiency of the external light is increased, so that a good display can be performed.

  In the present embodiment, the air layer 7 is used. However, the present invention is limited to air as long as it has the above-described function and has the above-described effects on the liquid crystal display device 1. Instead, it may be an inert gas such as nitrogen or argon.

  Further, as described above, in the embodiments described later, an air layer having a thickness of 0.2 mm is provided. However, the present invention is not limited to this, but when the thickness is less than 0.1 mm, interference fringes may be generated. Therefore, the thickness of the air layer is preferably 0.1 mm or more. Moreover, the upper limit of thickness will not be specifically limited if it is a range which has the effect mentioned above, For example, about 5.0 mm can be made into an upper limit. Therefore, the air layer 7 can be appropriately set within the above range.

  The light scattering layer 8 is provided to scatter light incident on the light scattering layer 8, and as shown in FIG. 1, the air layer 7 side of the light source side polarizing plate 9, specifically, light On both sides of the scattering layer 8, the light source side polarizing plate 9 and the air layer 7 are disposed adjacent to each other. In addition, as light which injects into the light-scattering layer 8 here, visible light is mentioned, for example.

  By providing the light scattering layer 8, the liquid crystal display device 1 according to the present embodiment can perform display with good fine reflection.

  Specifically, light other than the polarized light P parallel to the polarization transmission axis of the polarized light reflection plate 6 is reflected among the light incident on the polarized light reflection plate 6. The reflection on the polarizing reflector 6 is usually specular reflection. Specular reflection refers to reflection that returns 100 reflections with respect to, for example, 100 incident angles only at one reflection angle equal to the incident angle.

  Although the liquid crystal display device 1 will be described in detail later, the optical axis of the light source side polarizing plate 9 and the polarization transmission axis of the polarizing reflector 6 disposed on the light source side of the light source side polarizing plate 9 are configured to be shifted. Therefore, even the polarized light P incident from the external light side polarizing plate 13 side and transmitted through the light source side polarizing plate 9 is partially reflected by the polarization reflection plate 6. This reflection is the microreflection in the present invention. Since this reflection is specular reflection as described above, the angle (incident angle) at which the polarized light transmitted through the light source side polarizing plate 9 is incident on the polarizing reflection plate 6. Will depend on.

  Therefore, by arranging the light scattering layer 8 at the above-described position, the light incident from the external light incident side polarizing plate 13 side can be uniformly incident on the light incident surface of the light source side polarizing plate 9 and the polarized light can be polarized. The light that is specularly reflected by the reflecting plate 6 is not limited to the reflection direction, that is, the light can be distributed in a direction other than the specular reflection direction. Can be incident. Therefore, the viewing angle can be enlarged and good fine reflection can be obtained.

  In the present embodiment, the light scattering layer 8 is disposed on the air layer 7 side of the light source side polarizing plate 9, specifically, adjacent to the air layer 7. By arranging the light scattering layer 8 and the air layer 7 adjacent to each other, the difference in refractive index is maximized compared to the arrangement where the light scattering layer 8 and the air layer 7 are not adjacent to each other. Becomes larger.

  However, the present invention is not limited to this arrangement. FIG. 2 is a configuration diagram in which the light scattering layer 8 is arranged at the interface with the air layer 7 in the polarizing reflector 6. Further, as shown in FIG. 3, it may be arranged between the polarizing reflection plate 6 and the first retardation plate 10, and the first retardation plate 10 and the liquid crystal panel as shown in FIG. 11 may be arranged.

  3 and FIG. 4, an adhesive material having the same diffusion effect as that of the light scattering layer 8 may be used.

  As the light scattering layer 8, an acrylic resin containing flake-shaped titanium dioxide-coated mica prepared so as to have a diffusion coefficient of 80 can be used as in Examples described later. However, the present invention is not limited to this, and for example, a plastic mixed with glass beads, a mixture of materials having different refractive indexes, a polycrystalline mixed plastic, or the like can be used.

  Further, as shown in FIG. 1, the liquid crystal panel 11 has a configuration in which a first retardation plate 10 and a second retardation plate 12 are provided via the adhesive material layer 14.

  The liquid crystal panel 11 will be described with reference to FIG. FIG. 5 is a configuration diagram showing the configuration of the liquid crystal panel 11. The liquid crystal panel 11 includes a pair of substrates 16 and 17 made of a transparent material disposed to face each other, and a liquid crystal material made of a medium that optically modulates by applying an electric field as an optical modulation layer between the pair of substrates. 18 is sandwiched.

  Specifically, the liquid crystal panel 11 is provided with transparent electrodes 19 and 20 that form a plurality of pixel regions by regions facing each other on the inner surfaces of the pair of transparent substrates 16 and 17, respectively, For example, a plurality of colors, for example, red, green, and blue color filters 21 corresponding to a plurality of pixel regions are provided on the inner surface of the substrate 16 and surrounded by the sealing material between the pair of substrates 16 and 17. The liquid crystal material 18 is provided in the region.

  The liquid crystal panel 11 is of an active matrix type using TFTs (thin film transistors) (not shown) as active elements, and the electrodes 20 provided on the inner surface of the substrate 17 are a plurality of pixel electrodes arranged in a matrix. . Each of these pixel electrodes 20 is connected to a plurality of TFTs provided on the inner surface of the substrate 17 so as to correspond to the respective pixel electrodes 20, and the plurality of TFTs are wired on the inner surface of the substrate 17. Not connected to the gate line and data line. The electrode 19 provided on the inner surface of the substrate 16 is a single film-like counter electrode facing all of the plurality of pixel electrodes 20, and the counter electrode 19 is formed on the color filter 21. ing. Further, alignment films 22 and 23 are provided on the inner surfaces of the pair of substrates 16 and 17, respectively. The liquid crystal molecules of the liquid crystal material 18 provided between the substrates 16 and 17 are aligned with the alignment films 22 and 23, respectively. Therefore, the orientation direction in the vicinity of the respective substrates 16 and 17 is restricted, and the two substrates 16 and 17 are twist-oriented with a predetermined twist angle.

  For the pixel electrode 20 and the counter electrode 19, an electrode material such as a transparent electrode material such as ITO (indium tin oxide) can be used.

  The liquid crystal panel 11 has the same configuration as that of a normal transmission type STN panel as in an example described later, and is provided with a color filter in the cell, a STN having a cell thickness of 5 μm, a twist angle of 250 degrees, and Δn = 0.162. Liquid crystal can be used. However, the present invention is not limited to this.

  The liquid crystal panel 11 having such a configuration has a first retardation plate 10 and a second retardation plate on the surface opposite to the facing surfaces of the substrates 16 and 17 via the adhesive material layer 14 respectively. 12 is provided.

  In the present embodiment, as shown in FIG. 5, the alignment of liquid crystal molecules in the liquid crystal material is an STN (super twisted nematic) system. However, the present invention is not limited to this, and a TN (twisted nematic) system or the like may be used.

  In addition, as shown in FIG. 1, the first retardation plate 10 and the second retardation plate 12 are provided to compensate for coloring due to the retardation of the liquid crystal layer, and the adhesive material layer 14 is provided for each of them. The liquid crystal panel 11 is interposed therebetween. Specifically, the first retardation plate 10 is provided on the substrate 17 side of the liquid crystal panel 11 via the adhesive material layer 14, and the second retardation plate 12 is provided on the adhesive material layer 14. Is provided on the substrate 16 side of the liquid crystal panel 11.

  For the first retardation plate 10 and the second retardation plate 12, for example, a retardation film having a retardation of 50 to 1500 nm can be used. A twisted phase difference plate can also be used.

  The axial angle of the retardation plate (first retardation plate 10 and second retardation plate 12) and the axial angle of the polarizing plate (light source side polarizing plate 9 and external light incident side polarizing plate 13) are normally. What is necessary is just to optimize so that it may become black, and in the Example mentioned later, the 1st phase difference plate 10 is made into the 2nd position by 20 degree | times clockwise from a 0-6 o'clock viewing angle to the phase difference film of 430 nm retardation. The retardation film 12 is a retardation film having a retardation of 430 nm, which is attached at 20 degrees counterclockwise. The axis of the external light incident side polarization plate 13 is 5 degrees clockwise from the viewing angle of 0-6 o'clock, and the light source side polarization plate The 9 axis is configured to be 90 degrees clockwise (3-9 o'clock direction). However, the present invention is not limited to this.

  The light source side polarizing plate 9 and the external light incident side polarizing plate 13 have optical axes on their respective light incident surfaces, and are arranged so that their optical axis directions are orthogonal to each other. As shown in FIG. 1, the light source side polarizing plate 9 is disposed on the opposite side of the liquid crystal panel 11 of the first retardation plate 10, and the external light incident side polarizing plate 13 is arranged at the second position. The phase difference plate 12 is disposed on the opposite side of the liquid crystal panel 11.

  The adhesive material layer 14 includes a light scattering layer 8, a light source side polarizing plate 9, a first retardation plate 10, a liquid crystal panel 11, a second retardation plate 12, and an external light incident side polarizing plate 13. And are provided for adhering these components to each other. As the adhesive material layer 14, for example, a polymer for adhesive use such as epoxy, UV curable resin, urethane acrylate, or the like can be used. However, the adhesive material provided in the liquid crystal display device according to the present invention is not limited to this.

  In addition, you may comprise any one layer of the said adhesive material layers 14 using the adhesive material provided with the diffusion effect as mentioned above. As an adhesive material having a diffusion effect, a resin in which glass beads or titanium dioxide-coated mica is dispersed can be used.

  Next, the optical axis in the light source side polarizing plate 9 and the polarization transmission axis in the polarizing reflector 6 will be described in detail as follows.

  FIG. 6 is a graph showing changes in reflectance and transmittance with respect to an angle formed by the polarization transmission axis of the polarizing reflector 6 and the optical axis of the light source side polarizing plate 9 in the liquid crystal display device 1 of the present embodiment. .

  As shown in FIG. 6, when the angle between the optical axis and the polarization transmission axis exceeds 20 degrees, the transmittance is less than 90%. In the liquid crystal display device 1 according to the present embodiment, the transmittance is preferably 90% or more from the viewpoint that the transmissive display is emphasized. Therefore, the angle formed by the optical axis of the light source side polarizing plate 9 and the polarization transmission axis of the polarizing reflector 6 is preferably 18 degrees or less.

  Further, when the angle between the optical axis and the polarization transmission axis is less than 10 degrees, the reflectance is less than 3%. When the reflectance is less than 3%, the liquid crystal display device 1 cannot check the display content displayed on the liquid crystal panel using the microreflection, and therefore the reflectance is 3% or more. Is preferred. Therefore, the angle formed by the optical axis of the light source side polarizing plate 9 and the polarization transmission axis of the polarizing reflector 6 is preferably 12 degrees or more. A more suitable angle is 13 to 17 degrees, and 15 degrees is optimal. However, if transmission is important, it may be 12 degrees, and if reflection is important, it may be 18 degrees.

  Therefore, in the liquid crystal display device 1 of the present embodiment, the optical axis of the light source side polarizing plate 9 and the polarization transmission axis of the polarizing reflector 6 are shifted by an angle in the above range. Reflected polarized light from the polarizing reflector 6 according to the amount enters the light source side polarizing plate 9. This is the “micro-reflection” that is the object of the present invention.

  That is, in the present invention, the “liquid crystal display device having a fine reflection function” specifically means a liquid crystal display device having a reflectance of less than 1%.

  In the display device disclosed in Patent Literature 4, a polarizing separator and a polarizing plate whose absorption axis is shifted are used, which means the light absorber described in the literature, and the contrast is lowered. The purpose is to prevent.

  Patent Document 4 discloses a display device that performs dark display when a black light absorber formed on a light source absorbs external light and performs black display (dark display) in reflective display using external light. Is disclosed. This display device has a structure in which a plurality of openings are provided in the black light absorber so as to be compatible with transmissive display.

  However, in this configuration, since the opening is present, the external light cannot be efficiently absorbed by the light absorber, so the light that could not be absorbed is reflected by the light source, and the black display (dark display) becomes gray display. Contrast is lowered. Therefore, as a configuration capable of obtaining a high contrast at the time of reflective display, another configuration including a gray light absorber without an opening is disclosed, which can absorb external light and is a light source in a transmissive display It is said that the light from the light can also be transmitted and the reduction in contrast can be prevented.

  Therefore, as an alternative to the gray light absorber, the document describes the absorption axis of the polarization separator that achieves the same effect as the gray light absorber and the absorption axis of the polarizing plate under the polarizing plate separator. The structure which shifted is described.

  In the present invention, not only the configuration itself of the polarizing reflector and the polarizing plate and the angle formed by their axes are different, but also the purpose thereof is different. In Patent Document 4, the configuration in which the absorption axis of the polarization separator and the absorption axis of the polarizing plate are shifted is to realize the gray light absorber as described above, that is, to prevent a decrease in contrast. It is said. In this case, the crossing angle between the polarizing plate and the polarization separator is about 45 degrees. Therefore, the angle formed by the shaft is greatly different from the configuration according to the present invention. The purpose of the liquid crystal display device according to the present invention is to cause slight reflection, and as described above, the polarized light transmitted through the light source side polarizing plate 9 is 20 degrees larger than the polarization transmission axis of the polarizing reflecting plate 6. It is the structure which has shifted | deviated in the range which is the following, The fine reflection which is the objective of this invention is realizable with the reflected polarized light from the polarizing reflective plate 6 according to the deviation | shift amount. Therefore, the present invention is a configuration for achieving the above-described object, and is not intended to prevent a decrease in contrast as in Patent Document 4.

  In the present embodiment, the contrast itself is under the control of the light source side polarizing plate 9 and the external light incident side polarizing plate 13, and the polarizing reflector 6 contributes to the contrast only by being visible with slight reflection. Absent.

  Next, the display principle of the liquid crystal display device 1 of the present embodiment will be described as follows.

  FIG. 7 is a diagram showing the configuration of the liquid crystal display device 1 of the present embodiment. The liquid crystal display device 1 shown in FIG. 7 is divided into left and right halves for convenience of explanation, and the left half is shown as a no-voltage application part and the right half is shown as a voltage application part.

  In FIG. 7, in order to indicate the polarization vibration direction of the illumination light, a case where the polarization vibration direction is substantially parallel to the paper surface of the drawing is indicated by an arrow, and a case where the polarization vibration direction is substantially perpendicular to the paper surface. The inner circle is shown as a black circle. In the liquid crystal display device 1 shown in FIG. 1, the lamp 2, the light guide plate 3, the scattering plate 4, and the prism sheet 5 are shown here as the backlight unit 24.

  First, the display principle of the liquid crystal display device 1 according to the present embodiment will be described with reference to FIGS. 7A and 7B with respect to a display when the lamp 2 is lit, that is, a transmissive display.

  As shown in FIGS. 7A and 7B, when the lamp 2 in the liquid crystal display device 1 of the present embodiment is lit, the illumination light is transmitted through the light guide plate 3 constituting the backlight unit 24. The liquid crystal display device 1 is guided in the direction of the constituent members, passes through the scattering plate 4, passes through the prism sheet 5, and enters the polarizing reflection plate 6. The polarization reflection plate 6 is provided with a polarization transmission axis in a direction perpendicular to the paper surface. Therefore, only the polarized light parallel to the polarization transmission axis (polarized light perpendicular to the paper surface in the drawing) out of the linearly polarized light incident on the polarized light reflecting plate 6 is transmitted through the polarized light reflecting plate 6. On the other hand, of the light incident on the polarization reflector 6, the polarization perpendicular to the polarization transmission axis (polarization parallel to the paper surface in the drawing) is directed toward the backlight unit 24 on the surface of the polarization reflector 6. Reflected (hereinafter, this polarized light is referred to as polarized light S).

  Polarized light that has passed through the polarizing reflector 6 (hereinafter, this polarized light is referred to as polarized light P) diffuses by passing through the air layer 7 and the light scattering layer 8. The diffused polarized light P enters the light source side polarizing plate 9. The light source side polarizing plate 9 is provided with an optical axis in a direction substantially perpendicular to the paper surface. Specifically, as described above, the optical axis of the light source side polarizing plate 9 and the polarization transmission axis of the polarizing reflector 6 are 10 degrees or more and 20 degrees or less, preferably 10 degrees or more and 15 degrees or less. It is preferably configured in a state of being shifted at an angle of approximately 15 degrees. Therefore, of the polarized light P incident on the light source side polarizing plate 9, the polarized light P corresponding to the amount of deviation between the optical axis and the polarized light transmission axis is absorbed without passing through the light source side polarizing plate 9. Of the polarized light P incident on the light source side polarizing plate 9, polarized light parallel to the optical axis of the light source side polarizing plate 9 (hereinafter, this polarized light is referred to as polarized light P ′) is transmitted through the light source side polarizing plate 9. .

  On the other hand, the polarized light S reflected in the direction of the backlight unit 24 is reflected and refracted by the backlight unit 24 to become mixed light (S + P). The mixed light (S + P) again enters the polarizing reflector 6, and only the polarized light P of the mixed light passes through the polarizing reflector 6. As described above, the polarized light S is reflected and / or refracted between the backlight unit 24 and the polarized light reflecting plate 6, thereby becoming polarized light P and transmitted through the polarized light reflecting plate 6.

  Of the polarized light P that has passed through the polarization reflector 6, polarized light that is not parallel to the optical axis of the light source side polarizing plate 9 is absorbed by the light source side polarizing plate 9 and is relative to the optical axis of the light source side polarizing plate 9. The parallel polarized light is transmitted through the light source side polarizing plate 9 (hereinafter, this polarized light is referred to as polarized light P ′).

  The polarized light P ′ transmitted through the light source side polarizing plate 9 passes through the first retardation plate 10 (not shown) and enters the liquid crystal panel 11. The liquid crystal material formed in the liquid crystal panel 11 has liquid crystal molecules aligned in the STN mode. As shown in the left half of FIG. 7, when no voltage is applied, the liquid crystal molecules are STN-type, and the major axis direction of the liquid crystal molecules is twisted and aligned in a spiral shape. On the other hand, as shown in the right half, the major axis direction of the liquid crystal molecules is aligned along the electric field direction when a voltage is applied.

  A case where no voltage is applied (FIG. 7A) will be described. When the polarized light P ′ transmitted through the light source side polarizing plate 9 is incident on the liquid crystal panel 11, the major axis direction of the liquid crystal molecules is twisted and oriented in a spiral manner, so that the polarization vibration direction is polarized parallel to the paper surface. To do. The polarized light whose polarization oscillation direction is parallel to the paper surface passes through the second retardation plate 12 (not shown) and enters the external light incident side polarizing plate 13. The external light incident side polarizing plate 13 has an optical axis orthogonal to the optical axis of the light source side polarizing plate 9. Therefore, the polarized light having a polarization oscillation direction parallel to the paper surface incident on the external light incident side polarizing plate 13 is transmitted through the external light incident side polarizing plate 13. That is, the display is bright (bright display).

  Next, a case where a voltage is applied (FIG. 7B) will be described. When the polarized light P ′ transmitted through the light source side polarizing plate 9 is incident on the liquid crystal panel 11, the major axis direction of the liquid crystal molecules is aligned along the electric field application direction. The liquid crystal panel 11 is transmitted with the substantially vertical polarized light. The polarized light substantially perpendicular to the paper surface is absorbed by the external light incident side polarizing plate 13 having an optical axis substantially parallel to the paper surface. That is, the display is dark (dark display).

  Next, display based on slight reflection performed by taking in external light will be described with reference to FIGS.

  As shown in FIGS. 7C and 7D, when external light is incident on the external light incident side polarizing plate 13 having an optical axis substantially parallel to the paper surface, it is substantially parallel to the optical axis. The polarized light passes through the external light incident side polarizing plate 13, passes through the second retardation plate 12 (not shown), and enters the liquid crystal panel 11.

  First, a case where no voltage is applied to the liquid crystal panel 11 (FIG. 7C) will be described. Polarized light having a polarization oscillation direction parallel to the paper surface incident on the liquid crystal panel 11 is oriented by twisting the major axis direction of the liquid crystal molecules in a spiral shape, so that the polarization vibration direction is substantially perpendicular to the paper surface. Polarize. The polarized light substantially perpendicular to the paper surface passes through the first retardation plate 10 (not shown) and enters the light source side polarizing plate 9. The light source side polarizing plate 9 has an optical axis orthogonal to the optical axis of the external light incident side polarizing plate 13. Therefore, the polarized light that has passed through the first retardation plate 10 passes through the light source side polarizing plate 9 as it is. Polarized light transmitted through the light source side polarizing plate 9 (hereinafter, this polarized light is referred to as polarized light Q) diffuses by passing through the light scattering layer 8 and the air layer 7. Here, out of the polarized light Q transmitted through the light source side polarizing plate 9, the polarized light that does not reach the light source side polarizing plate 9 is reflected on the surface of the air layer 7.

  The light reflected by the surface of the air layer 7 is scattered by the light scattering layer 8 and enters the light source side polarizing plate 9 again. Of the light incident on the light source side polarizing plate 9 again, polarized light parallel to the optical axis of the light source side polarizing plate 9 passes through the light source side polarizing plate 9 and enters the liquid crystal panel 11. The polarized light incident on the liquid crystal panel 11 is polarized in the direction of polarization oscillation parallel to the plane of the paper, passes through the external light incident side polarizing plate 13 and contributes to bright display (bright display).

  On the other hand, out of the polarized light Q incident on the polarizing reflection plate 6, the polarization that is not parallel to the polarization transmission axis of the polarization reflection plate 6 has the polarization transmission axis of the polarization reflection plate 6 and the optical axis of the light source side polarizing plate 9. Therefore, it is reflected by the polarizing reflector 6 (hereinafter, this polarized light is referred to as polarized light R). The polarized light R is diffused by passing through the light scattering layer 8 and the air layer 7 and enters the light source side polarizing plate 9 again. Of the light incident on the light source side polarizing plate 9 again, the polarized light P ′ parallel to the optical axis of the light source side polarizing plate 9 is incident on the liquid crystal panel 11 and the liquid crystal panel 11 makes the polarization vibration direction substantially parallel to the paper surface. The light is polarized, enters the external light incident side polarizing plate 13, and passes through the external light incident side polarizing plate 13. That is, bright display (bright display) can be performed.

  On the other hand, of the polarized light Q that has entered the polarizing reflector 6, the polarized light that has passed through the polarizing reflector 6 (hereinafter, this polarized light is referred to as polarized light Q ′) is incident on the backlight unit 24. A part of the polarized light Q ′ incident on the backlight unit 24 is reflected and refracted by the backlight unit 24. The reflected / refracted light is incident on the polarizing reflector 6 again. Of the light incident on the polarizing reflector 6, polarized light parallel to the polarization transmission axis of the polarizing reflector 6 (polarized light P in the figure) can be transmitted, and polarized light perpendicular to the polarization transmission axis is backlit again. Reflected in the direction of the unit 24 (polarized light S in the figure). The polarized light reflected again in the direction of the backlight unit 24 is repeatedly reflected and / or refracted between the polarization reflector 6 and the backlight unit 24, and is polarized parallel to the polarization transmission axis of the polarization reflector 6. And is transmitted through the polarizing reflector 6 (polarized light P in the figure). Of the polarized light transmitted through the polarizing reflector 6, polarized light parallel to the optical axis of the light source side polarizing plate 9 is transmitted through the light source side polarizing plate 9, and polarized light perpendicular to the optical axis of the light source side polarizing plate 9 is the light source side. Absorbed by the polarizing plate 9. Polarized light that has passed through the light source side polarizing plate 9 (polarized light P ′ in the drawing) passes through the first retardation plate 10 (not shown), enters the liquid crystal panel 11, and changes the polarization vibration direction with respect to the paper surface. The light is polarized in parallel and enters the external light incident side polarizing plate 13. The polarized light parallel to the paper surface is transmitted through the external light incident side polarizing plate 13 having an optical axis parallel to the paper surface, and a bright display (bright display) can be performed.

  Therefore, in addition to the reflected light caused by the deviation between the polarization transmission axis and the optical axis, the reflected light that is transmitted through the polarization reflector 6 and reflected by the backlight unit 24 also contributes to bright display. The liquid crystal display device according to the embodiment has high light utilization efficiency in addition to being capable of displaying by microreflection using external light.

  Next, the case where a voltage is applied (FIG. 7D) will be described. When the polarized light that has passed through the external light incident side polarizing plate 13 is incident on the liquid crystal panel 11, the major axis direction of the liquid crystal molecules is aligned along the direction of electric field application. The liquid crystal panel 11 is transmitted while maintaining the substantially parallel polarized light. The polarized light substantially parallel to the paper surface is absorbed by the light source side polarizing plate 9 having an optical axis substantially perpendicular to the paper surface. That is, the display is dark (dark display).

  Thus, in the liquid crystal display device 1 according to the present embodiment, both the bright display in the transmissive display and the bright display in the fine reflection display are displayed when no voltage is applied, and in the dark display and the fine reflection display in the transmissive display. Both a dark display and a voltage display are displayed. That is, the liquid crystal display device 1 according to the present embodiment is a liquid crystal display device that does not perform negative / positive inversion.

  Thus, when the liquid crystal display device 1 is used, the optical axis of the light source side polarizing plate 9 and the polarization transmission axis of the polarizing reflector 6 are 10 degrees or more, more preferably 12 degrees or more and 20 degrees. Hereinafter, since the angle is more preferably in the range of 15 degrees or less, among the polarized light incident on the polarizing reflector 6, the polarized light that has entered the portion of the polarizing reflector 6 that is shifted by the above angle, Reflected by the polarizing reflector 6. The reflected polarized light again enters the light source side polarizing plate 9, passes through the liquid crystal panel 11, and passes through the external light incident side polarizing plate 13. As described above, the liquid crystal display device 1 is configured so that the optical axis of the light source side polarizing plate 9 and the polarization transmission axis of the polarizing reflector plate are slightly deviated, so that the external light corresponding to the deviated amount is obtained. Even if the light source 15 is not turned on by the reflected light of the light, that is, by the slight reflection, the display content displayed on the liquid crystal panel 11 can be confirmed.

  Further, in the case where fine reflection is to be realized with a configuration including a transflective reflector, it is necessary to make the reflector thin or increase the hole provided in the reflector. However, the structure in which the reflective film is provided in the pixel leads to an increase in cost, and even when a hole is provided in the reflective film, an increase in cost is inevitable with the processing. Therefore, since the liquid crystal display device 1 has a configuration including a polarization reflection plate instead of a semi-transmission reflection plate, a liquid crystal display device emphasizing transmission type with a slight reflection can be realized without significantly increasing the cost. can do.

  Further, since the liquid crystal display device 1 includes the light source side polarizing plate 9 and the external light incident side polarizing plate 13 on both sides of the liquid crystal panel 11, the liquid crystal panel can be used for transmission type display and display by slight reflection. When the voltage is applied to 11 or when no voltage is applied, the bright display or dark display is not reversed. That is, it does not cause negative / positive reversal. Therefore, since it is not necessary to provide a negative / positive inversion circuit, there is no need to increase the cost and expand the occupied space by providing the negative / positive inversion circuit.

  In addition, since the liquid crystal display device 1 is used to provide the air layer 7, when light is reflected by using external light, the light source side polarizing plate 9 is transmitted and the light scattering is performed. Of the polarized light that has passed through the layer 8, polarized light that does not reach the polarizing reflector 6 can be reflected on the surface of the air layer 7, that is, on the interface between the light scattering layer 8 and the air layer 7.

  Further, the air layer 7 is polarized and reflected out of light having a polarization vibration plane incident from the outside and parallel to the optical axis of the light source side polarizing plate 9, that is, out of light transmitted through the light source side polarizing plate 9. Even the light having a polarization vibration plane parallel to the polarization transmission axis of the plate 6 can be diffused and reflected by the polarization reflection plate by changing the polarization vibration plane.

  Therefore, by providing the air layer 7 between the polarizing reflector 6 and the light scattering layer 8, the reflectance of external light can be increased, and the reflective display can be performed more favorably.

  In this embodiment, an air layer is used. However, the light diffusion layer of the liquid crystal display device according to the present invention is not limited to air or gas, and has the same effect as the air layer 7. Other material layers may be used as long as they perform.

  Further, by using the liquid crystal display device 1, since the liquid crystal display device 1 includes the light scattering layer 8, the content displayed on the liquid crystal panel is taken in and reflected by the polarization reflector 6. When the confirmation is performed using the emitted light, the light reflected by the polarization reflector 6 is diffused. Thereby, the liquid crystal display device 1 can realize a display with an excellent viewing angle by widening the viewing angle. By providing the light scattering layer 8, it is possible to diffuse the light that is specularly reflected on the surface of the polarizing reflector. That is, since specular reflection on the surface of the polarizing reflector can be suppressed, light can be distributed in directions other than the specular reflection direction, and a better fine reflection display can be realized.

  The light scattering layer 8 is provided between the liquid crystal panel 11 and the polarizing reflection plate 6, more specifically, between the liquid crystal panel 11 and the first retardation plate 10, or the first retardation plate. 10 and the light source side polarizing plate 9 may be provided. However, since the light source side polarizing plate 9 is provided on the air layer 7 side, the air layer 7 and the light scattering layer 8 are refracted. The rate difference is maximized. For this reason, the light scattering effect is enhanced, and the light reflected by the polarizing reflector 6 can be diffused more efficiently, so that it is possible to realize a good display by microreflection.

Hereinafter, the present invention will be described in detail based on examples, but the present invention is not limited thereto.
〔Example〕
The following description describes the liquid crystal display device according to the present embodiment.

  In this example, the same configuration of the liquid crystal display device as that in FIG. 1 in the above-described embodiment is provided. As the liquid crystal panel 11, a STN liquid crystal having the same configuration as that of a normal transmissive STN panel, a color filter provided in the cell, a cell thickness of 5 μm, a twist angle of 250 degrees, and Δn = 0.162 was used.

  The axial angle of the phase difference plate (first phase difference plate and second phase difference plate) and the axial angle of the polarizing plate (light source side polarizing plate and external light incident side polarizing plate) are normally black. In this embodiment, the first retardation plate is a retardation film having a retardation of 430 nm, and the second retardation plate has a retardation of 20 degrees clockwise from the 0-6 o'clock viewing angle. A 430 nm phase difference film is pasted at 20 degrees counterclockwise, the axis of the external light incident side polarizing plate is 5 degrees clockwise from the viewing angle of 0-6 o'clock, and the axis of the light source side polarizing plate is 90 degrees clockwise. It was made to become a degree (3-9 o'clock direction).

  As the light scattering layer, an acrylic resin containing scaly titanium dioxide-coated mica prepared so as to have a diffusion coefficient of 80 was used.

  Sumitomo 3M DBEF was used as the polarizing reflector. The polarized light transmission axis has a crossing angle of 12 degrees with the optical axis of the light source side polarizing plate, and an air layer is provided so as to have a gap of 0.2 mm between the light source side polarizing plate, A prism sheet, a scattering plate, and an LED backlight with a light guide plate are arranged below.

  When a transmissive display and a slightly reflective display are performed using the liquid crystal display device having the above-described configuration, a transmittance of 40% or more and a reflectance of about 0.5% can be obtained. It was.

  Therefore, the liquid crystal display device has a fine reflection function with a reflectance of less than 1% even in a non-lighting state of the backlight, and has a wide viewing angle due to non-specular reflection, so that it can capture outside light. In the environment, the display content displayed on the liquid crystal panel can be recognized even when the backlight is not lit.

  The liquid crystal display device according to the present invention can cause slight reflection while placing importance on transmissive display. Therefore, it is possible to provide a liquid crystal display device capable of confirming the display content displayed on the liquid crystal layer by using external light even when the light source is not turned on.

  Therefore, for example, the present invention can be widely applied to image display devices such as PDAs, watches, various monitors, electronic paper, etc., or information display devices such as mobile phones.

It is the figure which showed the structure of the liquid crystal display device which is one Embodiment of this invention. It is the figure which showed the structure of the liquid crystal display device from which the arrangement | positioning of the light-scattering layer of the liquid crystal display device shown in FIG. 1 differs. It is the figure which showed the structure of another liquid crystal display device from which the arrangement | positioning of the light-scattering layer of the liquid crystal display device shown in FIG. 1 differs. It is the figure which showed the structure of another liquid crystal display device from which the arrangement | positioning of the light-scattering layer of the liquid crystal display device shown in FIG. 1 differs. It is the figure which showed the structure of the liquid crystal panel of the liquid crystal display device shown in FIG. It is the graph which showed the change of the reflectance and the transmittance | permeability with respect to the angle which the polarization transmission axis of the polarizing reflector in the liquid crystal display device which is one Embodiment of this invention makes, and the optical axis of a light source side polarizing plate. It is explanatory drawing explaining the transmission type display and fine reflection display in the liquid crystal display device which is one Embodiment of this invention.

DESCRIPTION OF SYMBOLS 1 Liquid crystal display device 2 Lamp 3 Light guide plate 4 Scattering plate 5 Prism sheet 6 Polarization reflecting plate 7 Air layer (gas layer, light diffusion layer)
8 Light scattering layer 9 Light source side polarizing plate (polarizing plate)
11 Liquid crystal panel (liquid crystal layer)
13 Outside light incident side polarizing plate (second polarizing plate)
14 Adhesive material layer 15 Light source

Claims (3)

In a liquid crystal display device including a polarizing plate having an optical axis that transmits polarized light having a predetermined polarization vibration surface between a liquid crystal layer and a light source that emits light toward the liquid crystal layer.
Between the polarizing plate and the light source, a polarizing reflector that transmits light having a polarization vibration plane parallel to the polarization transmission axis and reflects light having a polarization vibration plane perpendicular to the polarization transmission axis,
The polarizing reflector is disposed such that the polarization transmission axis faces the polarizing plate at a predetermined angle with the optical axis,
A light scattering layer that scatters incident light is provided between the polarizing reflector and the polarizing plate,
Between the light scattering layer and the polarizing reflector, a light diffusion layer for diffusing incident light is provided,
The light diffusion layer is a gas layer,
The thickness of the said light-diffusion layer is 0.1 mm or more and 0.2 mm or less, The liquid crystal display device characterized by the above-mentioned.   2. The liquid crystal display device according to claim 1, wherein the polarizing reflection plate is disposed such that the polarization transmission axis forms an angle of 10 degrees or more and 20 degrees or less with the optical axis.   The liquid crystal display device according to claim 1, further comprising a second polarizing plate having an optical axis orthogonal to the optical axis of the polarizing plate on a side opposite to the light source side of the liquid crystal layer.

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