JP5235939B2 - Optical element and display device using the same - Google Patents

Description

  The present invention relates to an optical element capable of changing a viewing angle of a screen of a display device, and a display device including the same.

  The screen of the display device is required to have various states depending on the use situation, such as a wide viewing angle that is effective when observing by a large number of people and a narrow viewing angle that cannot be seen by others.

  As an optical element that narrows the viewing angle of the screen of a display device, a film (hereinafter referred to as a louver film) in which a light absorbing layer and a transparent layer are alternately arranged to form a louver has been put into practical use.

  The louver film is commercially available from 3M as a trade name Light Control Film, or from Shin-Etsu Polymer Co., Ltd. as a trade name view control film (View Control Film). A louver film is used for public use such as ATM (Automated Teller Machine) or for preventing peeping on a screen in a mobile device such as a mobile phone.

  In addition to the display device that limits the viewing angle with an optical element such as a louver film, a display device that can arbitrarily switch between a wide viewing angle and a narrow viewing angle has been proposed.

  For example, in Patent Document 1, an optical path control plate including a surface light source, two polarizing plates and a twisted nematic liquid crystal cell disposed between them, and a microlens array is provided on the back side of the display liquid crystal cell. A display device is disclosed.

  In this case, the light from the surface light source can be limited by the optical shutter plate to form a light passage region at an arbitrary position, and the optical path can be changed by changing the positional relationship between the position of the microlens and the light passage region. It is controlled and the viewing angle is switched.

  As another liquid crystal display device whose viewing angle can be switched, a display device has been proposed in which a liquid crystal cell for display and a liquid crystal cell for viewing angle control are arranged between two polarizing plates.

  As such a display device, Patent Document 2 discloses a control method for a display device in which a liquid crystal layer of a display liquid crystal cell includes a twisted nematic liquid crystal layer, and the liquid crystal layer of the viewing angle control liquid crystal cell also includes a twisted nematic liquid crystal layer. Has been. In this case, by applying an appropriate voltage to the viewing angle control liquid crystal cell, it is possible to change the viewing angle range in which the contrast ratio is a predetermined value or more.

  Patent Document 3 discloses a conventional case where the liquid crystal molecules of the liquid crystal cell for viewing angle control are aligned in a direction parallel to the substrate constituting the liquid crystal cell, or when the liquid crystal is heated to an isotropic phase state. A display device has been disclosed that has the same viewing angle characteristics as those of the liquid crystal display device and that narrows the viewing angle when the liquid crystal molecules of the liquid crystal cell for viewing angle control are aligned in a direction perpendicular to the substrate.

Japanese Patent Laid-Open No. 5-108023 Japanese Patent Laid-Open No. 10-268251 JP-A-9-105958 International publication number: WO95 / 27919

  A louver film has been put into practical use as an optical element that narrows the viewing angle of a screen of a display device (hereinafter also referred to as a viewing angle limiting element). The louver film has a periodic structure in which a light absorption layer and a transparent layer repeat alternately.

  For this reason, there is a problem that moire occurs between the pixel arrangement of the display element and the periodic structure of the louver film, thereby degrading the image quality. Furthermore, since the louver film includes a light absorption layer, a part of the light is absorbed even in the front direction, and the transmittance is lowered. The louver film is an optical element that restricts transmission of light in two opposite directions such as the upper and lower sides of the screen or the left and right sides in principle.

  The present invention has been made to solve such problems of the prior art, and a first object of the invention is to realize a viewing angle limiting element free from image quality deterioration due to the occurrence of moire.

  Another object of the present invention is to realize a viewing angle limiting element capable of obtaining high transmittance when applied to a liquid crystal display element.

  Another object of the present invention is to realize a viewing angle control element that can darken only one predetermined direction instead of two directions.

  As described above, as a display device capable of switching between a wide viewing angle and a narrow viewing angle, a display device including a planar light source, an optical shutter plate, and an optical path control plate on the back surface of a display liquid crystal cell, There has been proposed a display device in which a display liquid crystal cell and a viewing angle control liquid crystal cell are arranged between polarizing plates.

  In the case of the former display device, an expensive optical member such as a microlens array is required as an optical path control plate. Furthermore, since the microlens array and the optical shutter plate need to be accurately aligned, there is a problem that the product cost increases. Further, there is a problem that moire is generated between the periodic structure of the microlens array and the pixel arrangement of the liquid crystal cell for display, and image quality is likely to be deteriorated.

  On the other hand, the latter display device makes it difficult to recognize an image by reducing the contrast ratio of the screen or inverting the gradation in an oblique direction.

  In this case, the visibility of the image when observed from an oblique direction is deteriorated, but part of the light leaks from the screen. For this reason, it does not function effectively in applications where it is desired to suppress the reflection of the screen image on the front window at night, particularly in an in-vehicle display device.

  Further, for example, even if the visibility of an image deteriorates due to inversion of gradation, character information or the like can be read, so that a sufficient effect may not be obtained from the viewpoint of preventing peeping.

  Also, when a narrow viewing angle state is realized with liquid crystal molecules aligned in a direction perpendicular to the substrate constituting the liquid crystal cell, the vertically aligned liquid crystal actually has a polarization axis for linearly polarized light incident thereon. There is no phase difference in the light traveling in the azimuth angle perpendicular to the azimuth angle parallel to the azimuth angle, and there are four directions in which the viewing angle cannot be controlled.

  One of the objects of the present invention is to solve such problems of the prior art, limit the transmission of light in a predetermined azimuth angle and polar angle range, and further depend on moire even when combined with a display element such as a liquid crystal display panel. An object of the present invention is to provide a viewing angle control element that controls the viewing angle without causing deterioration in image quality, or a display device using the viewing angle control element.

  In order to achieve the above object, the present invention employs, for example, the following means.

  An optical element composed of a first polarizing layer, a second polarizing layer, and a liquid crystal layer disposed between the two polarizing layers, wherein the first and second polarizing layers are linearly polarized light The arrangement is such that the absorption axes are parallel to each other, the liquid crystal layer is composed of discotic liquid crystal with hybrid alignment, and the alignment axis is parallel or orthogonal to the absorption axes of the first and second polarizing layers; To do.

  The optical element includes a first polarizing layer, a second polarizing layer, and a liquid crystal layer disposed between the two polarizing layers. The two polarizing layers have an absorption axis of the polarized light. The liquid crystal layers are made of nematic liquid crystal with hybrid alignment, the alignment axis of which is parallel or orthogonal to the absorption axis of the polarizing layer, and the liquid crystal molecules are aligned in a state of being perpendicular or nearly perpendicular. An optically negative uniaxial medium having an absolute value of Rth greater than 100 nm is provided on the other side. In the optical element, two or more liquid crystal layers may be laminated in order to obtain desired optical characteristics.

  Further, when the present optical element is applied to a liquid crystal display device, the optical element is disposed between the illumination device and the liquid crystal display panel, and both the first polarizing layer and the second polarizing layer, or at least one light source side. A reflective polarizing layer may be disposed.

  Alternatively, both or at least one of the first polarizing layer and the second polarizing layer may be a reflective polarizing layer.

  Furthermore, it is preferable to provide a diffuse reflection means for diffusely reflecting light returning to the illumination device.

  The optical element includes a first polarizing layer, a second polarizing layer, and a liquid crystal layer disposed between the two polarizing layers. The two polarizing layers have an absorption axis of the polarized light. The liquid crystal layers are composed of rod-like liquid crystal molecules, twisted so that their alignment axes are parallel or orthogonal to the absorption axes of the adjacent polarizing layers, and the liquid crystal molecules have a predetermined azimuth and polar angle. In FIG. 4, the alignment state is such that the effective phase difference is zero.

  An optical element including a first polarizing layer, a second polarizing layer, and a third polarizing layer, and a first liquid crystal layer and a second liquid crystal layer, wherein the first liquid crystal layer is a first polarizing layer. The second liquid crystal layer is disposed between the second polarizing layer and the third polarizing layer, and the absorption axis of the first polarizing layer and the third polarizing layer is disposed between the first polarizing layer and the second polarizing layer. Are arranged so that the absorption axes of the second polarizing layer are perpendicular to the absorption axes of the first polarizing layer and the third polarizing layer, and the first and second liquid crystal layers are formed from rod-like liquid crystal molecules. Alignment state in which the alignment axis is twisted so as to be parallel or orthogonal to the absorption axis of the adjacent polarizing layer, and the liquid crystal molecules have an effective phase difference of 0 at a predetermined azimuth and polar angle. It is set as the structure fixed to.

  In addition, the display device includes the optical element, an illumination device, and a liquid crystal display panel, and the liquid crystal display panel includes two polarizing layers and a liquid crystal layer, and controls the transmittance of light from the backlight. The optical element is configured such that one of the polarizing layers constituting this is also used as the polarizing layer constituting the liquid crystal display panel.

  An optical element including a first transparent substrate and a second transparent substrate facing each other and a liquid crystal layer between the substrates, wherein the first and second transparent substrates are aligned with a transparent electrode on each facing surface. The liquid crystal layer includes a film, and the liquid crystal layer is oriented in a state in which the liquid crystal molecules are perpendicular or nearly perpendicular to the substrate surface on the first transparent substrate side, and is parallel or nearly parallel to the substrate surface on the second substrate side Is a nematic liquid crystal having a positive dielectric anisotropy, and an optically negative uniaxial anisotropic medium is provided on the first transparent substrate side. Furthermore, a polarizing layer is provided on each of the first transparent substrate and the second transparent substrate side of the liquid crystal layer, the absorption axes of these polarizing layers are parallel to each other, and the alignment axis on the second transparent substrate side of the liquid crystal layer is polarized light The layer is configured to be parallel or orthogonal to the absorption axis of the layer.

  In the optical element, a reflective polarizing layer may be disposed on both the first polarizing layer and the second polarizing layer, or on the light source side of at least one polarizing layer. Alternatively, both or at least one of the first polarizing layer and the second polarizing layer may be a reflective polarizing layer. Furthermore, it is preferable to provide an illuminating device on the back surface of the viewing angle control element, and diffusing and reflecting means for diffusing and reflecting the light reflected by the reflective polarizing layer and returning to the illuminating device.

  Further, the first transparent substrate and the second transparent substrate facing each other, and a liquid crystal layer between the substrates are provided, and the first polarizing layer is provided on each of the first transparent substrate side and the second transparent substrate side of the liquid crystal layer. And a second polarizing layer, wherein the two polarizing layers have their polarization absorption axes orthogonal to each other, the liquid crystal layer is made of nematic liquid crystal with positive dielectric anisotropy, and its alignment axis is Each of the polarizing layers is twisted so as to be parallel or perpendicular to the absorption axis, and the liquid crystal layer has a Δnd value of 2000 nm or more.

  A plurality of optical elements may be laminated. In this case, the two polarizing layers arranged between the twisted liquid crystal layers may be used as one polarizing layer. Further, at this time, the alignment direction of the liquid crystal molecules in the liquid crystal layer may be arranged so as to be different between the plurality of liquid crystal layers. In addition, the display device includes a liquid crystal display panel, a lighting device disposed on the back surface of the liquid crystal display panel, and the optical element. The liquid crystal display panel includes two polarizing layers and a liquid crystal layer, and transmits light from the lighting device. The image light is formed by controlling the rate, and the viewing angle control element has a configuration in which one of the polarizing layers constituting this is also used as the polarizing layer constituting the liquid crystal display panel.

  A reflective polarizing layer may be disposed on the light source side of the second polarizing layer. Alternatively, the second polarizing layer may be a reflective polarizing layer. Furthermore, an illuminating device may be provided on the back surface of the optical element, and a diffuse reflecting means for diffusing and reflecting light reflected by the reflective polarizing layer and returning to the illuminating device may be provided.

  The present invention limits the transmission of light in a predetermined azimuth angle and polar angle range, and further does not cause image quality deterioration due to moire even when combined with a display element such as a liquid crystal display panel. A display device using the same can be provided.

It is a schematic sectional drawing for demonstrating the viewing angle limiting element of this invention. It is a schematic perspective view for demonstrating the liquid crystal film concerning the viewing angle limiting element of this invention. It is a schematic perspective view for demonstrating the viewing angle limiting element of this invention. It is a schematic perspective view for demonstrating the viewing angle limiting element of this invention. It is a schematic sectional drawing for demonstrating the display apparatus of this invention. It is a schematic front view for demonstrating the structure of the pixel part of the display apparatus of this invention. It is a schematic sectional drawing for demonstrating the display apparatus of this invention. It is a related explanatory drawing of the optical axis of the optical member which concerns on the display apparatus of this invention. It is a schematic sectional drawing for demonstrating the viewing angle limiting element of this invention. It is a schematic sectional drawing for demonstrating the viewing angle limiting element of this invention. It is a schematic sectional drawing for demonstrating the viewing angle limiting element of this invention. It is a schematic sectional drawing for demonstrating the display apparatus of this invention. It is a schematic sectional drawing for demonstrating the display apparatus of this invention. It is a related explanatory drawing of the optical axis of the optical member concerning the display apparatus of the present invention. It is a schematic sectional drawing for demonstrating the display apparatus of this invention. It is a schematic sectional drawing for demonstrating the display apparatus of this invention. It is a related explanatory drawing of the optical axis of the optical member which concerns on the display apparatus of this invention. It is a schematic sectional drawing for demonstrating the viewing angle limiting element of this invention. It is a schematic sectional drawing for demonstrating the liquid crystal film which concerns on the viewing angle limiting element of this invention. It is a relationship explanatory drawing of the optical axis of the optical member which concerns on the viewing angle limiting element of this invention. It is a graph which shows the relationship between the viewing angle and the transmittance | permeability for demonstrating the optical characteristic of the viewing angle limiting element of this invention. It is a schematic sectional drawing for demonstrating the viewing angle limiting element of this invention. It is a schematic sectional drawing for demonstrating the display apparatus of this invention. It is a related explanatory drawing of the optical axis of the optical member which concerns on the display apparatus of this invention. It is a schematic sectional drawing for demonstrating the viewing angle control element of this invention. It is a relationship explanatory drawing of the optical axis of the optical member which concerns on the viewing angle control element of this invention. It is an equitransmittance diagram which shows an example of the optical characteristic of the viewing angle control element of this invention. It is a graph which shows the relationship between the viewing angle and the transmittance | permeability for demonstrating the optical characteristic of the viewing angle control element of this invention. It is a schematic sectional drawing for demonstrating the display apparatus of this invention. It is a relationship explanatory drawing of the optical axis of the optical member which concerns on the viewing angle control element of this invention. It is a schematic sectional drawing for demonstrating the display apparatus of this invention. It is a relationship explanatory drawing of the optical axis of the optical member which concerns on the viewing angle control element of this invention. It is a graph which shows the relationship between the viewing angle and the transmittance | permeability for demonstrating the optical characteristic of the viewing angle control element of this invention. It is a schematic sectional drawing for demonstrating the display apparatus of this invention. It is a related explanatory drawing of the optical axis of the optical member which concerns on the display apparatus of this invention. It is a related explanatory drawing of the optical axis of the optical member which concerns on the display apparatus of this invention. It is a schematic sectional drawing for demonstrating the display apparatus of this invention. It is a related explanatory drawing of the optical axis of the optical member which concerns on the display apparatus of this invention. It is a schematic sectional drawing for demonstrating the display apparatus of this invention. It is a related explanatory drawing of the optical axis of the optical member concerning the display apparatus of the present invention. It is a schematic sectional drawing for demonstrating the display apparatus of this invention. It is a related explanatory drawing of the optical axis of the optical member which concerns on the display apparatus of this invention. It is a schematic sectional drawing for demonstrating the display apparatus of this invention. It is a related explanatory drawing of the optical axis of the optical member concerning the display apparatus of the present invention.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings.

  FIG. 1 is a partial cross-sectional view showing one embodiment of the optical element of the present invention. This optical element can reduce the light transmittance in a specific azimuth and viewing angle range, and is an optical element that can limit the viewing angle of a screen when provided in a display device. Hereinafter, an optical element having such a function is referred to as a viewing angle limiting element.

  The viewing angle limiting element 30 of the present embodiment is formed by laminating a first polarizing plate 2000, a second polarizing plate 2100, and a liquid crystal film 1000 including a discotic liquid crystal layer 100 between these polarizing plates.

  The polarizing plate transmits one of linearly polarized light components orthogonal to each other of light incident thereon, and absorbs the other.

  As the first polarizing plate 2000, for example, a base film made of polyvinyl alcohol or the like obtained by dyeing or adsorbing a dichroic material such as iodine or an organic dye is stretched and absorbed by orienting the dichroic material. It is possible to use a structure in which a polarizing layer 310 that exhibits dichroism is sandwiched between two protective films 220 and 221 made of a triacetyl cellulose film or the like.

  In addition, as the second polarizing plate 2100, a polarizing layer that exhibits absorption dichroism by stretching a base film made of polyvinyl alcohol or the like as in the first polarizing plate 2000 and orienting a dichroic material. A structure in which 300 is sandwiched between two protective films 210 and 211 made of a triacetyl cellulose film or the like can be used.

  The liquid crystal film 1000 is composed of a base film 200 and a liquid crystal layer 100 formed thereon.

  The liquid crystal film 1000 adheres to the first polarizing plate 2000 with the adhesive layer 410 and the second polarizing plate 2100 with the adhesive layer 400. The adhesive layer is made of a transparent adhesive such as acrylic.

  FIG. 2 is a schematic diagram for explaining the structure of the liquid crystal film 1000. The liquid crystal film 1000 is provided with an alignment film 500 made of polyimide or the like on a base film 200 having a small retardation in the in-plane direction such as triacetyl cellulose and optically isotropic, and a discotic liquid crystal such as a triphenylene derivative on the alignment film 500. A discotic compound exhibiting properties is formed into a film. The alignment film 500 is subjected to an alignment process such as a rubbing process, a discotic compound is applied thereon, a discotic nematic phase is formed by controlling the temperature, and the liquid crystal layer 100 is made non-fluidized by fixing the alignment state. Form.

  In the liquid crystal layer 100, the disc surface of the discotic liquid crystal is oriented near or perpendicular to the interface near the air interface, and on the base film 200 side, the disc surface is parallel or nearly parallel to the base film surface. Therefore, the hybrid orientation in which the orientation angle continuously changes in the thickness direction is obtained.

  When the angle formed by the disc surface of the discotic liquid crystal on the substrate film 200 side with the substrate film surface is θ1, the angle formed by the disc surface of the discotic liquid crystal on the side opposite to the substrate film 200 with the substrate film surface is θ2, In general, θ1 = 2 to 5 ° and θ2 = 65 to 75 °.

  The inclination of the disc surface of the discotic liquid crystal with respect to the base film surface is generated along the direction of the alignment treatment performed on the alignment film 500, and an axis parallel to the alignment direction is hereinafter referred to as an alignment axis. In order to make the liquid crystal layer 100 non-fluid, a polymerizable group is introduced into a side chain terminal of a discotic compound such as a triphenylene derivative, and polymerization is performed in a hybrid alignment state to fix the alignment state.

  Such a liquid crystal film has been commercialized from Fuji Photo Film under the trade name WV film, and can be used as a liquid crystal film constituting the viewing angle limiting element of the present invention. 3 and 4 show an absorption axis 2000A of the polarizing layer 310 of the first polarizing plate 2000, an alignment axis 1000A of the liquid crystal layer 100 of the liquid crystal film 1000, and an absorption axis 2100A of the polarizing layer 300 of the second polarizing plate 2100. It is a schematic diagram which shows the relationship.

  As illustrated, in the viewing angle limiting element of this example, the absorption axes of the polarizing layers of the first polarizing plate 2000 and the second polarizing plate 2100 are parallel to each other, and the alignment axis of the liquid crystal layer of the liquid crystal film is the absorption of the polarizing layer. It arrange | positions so that it may be parallel to an axis | shaft (FIG. 3) or orthogonally (FIG. 4).

  In this case, the light incident from the second polarizing plate 2100 (or the first polarizing plate 2000) side passes through the liquid crystal film 1000 after passing through the second polarizing plate 2100 (or the first polarizing plate 2000). Then, the light enters the first polarizing plate 2000 (or the second polarizing plate 2100).

  At this time, light traveling in the liquid crystal film 1000 in an oblique direction in an orientation orthogonal to the alignment axis of the liquid crystal layer 100 causes a phase difference, and the polarization state changes, so that the first polarizing plate 2000 (or the second polarizing plate 2100). ) And the transmittance decreases.

  On the other hand, almost no phase difference occurs in the light traveling in the oblique direction through the liquid crystal film 1000 in an orientation parallel to the alignment axis of the liquid crystal layer 100, so that it is almost absorbed by the first polarizing plate 2000 (or the second polarizing plate 2100). It is transparent without being.

  That is, an optical element can be realized in which the transmittance is smaller in the range where the polar angle is larger in the direction perpendicular to the alignment axis 1000A of the liquid crystal layer than in the direction parallel to the alignment axis 1000A of the liquid crystal layer. In other words, it is possible to realize a viewing angle limiting element in which the viewing angle is narrower in the direction perpendicular to the alignment axis 1000A of the liquid crystal layer than in the direction parallel to the alignment axis 1000A of the liquid crystal layer.

  As illustrated in FIGS. 3 and 4, when the alignment axis 1000 </ b> A of the liquid crystal layer of the liquid crystal film is set in a direction parallel to the vertical direction for convenience, a viewing angle limiting element having a smaller viewing angle in the horizontal direction than in the vertical direction can be realized. .

  Such a viewing angle characteristic is effective in preventing a peep from the side when applied to a display device of a portable device such as a mobile phone, a notebook PC, or a PDA, or a public device such as an ATM.

  Alternatively, when the alignment axis of the liquid crystal layer of the liquid crystal film 1000 is a direction parallel to the left-right direction, a viewing angle limiting element in which the viewing angle in the up-down direction is smaller than the left-right direction can be realized. Such viewing angle characteristics are effective in preventing image light from being reflected on the front windshield of an automobile when applied to an on-vehicle monitor.

  In the above description, the case where the liquid crystal layer of the liquid crystal film 1000 is composed of discotic liquid crystal with hybrid alignment has been described, but the present invention is not limited to this. For example, as the liquid crystal layer of the liquid crystal film 1000, rod-like liquid crystal molecules that are hybrid-aligned and fixed may be used.

  Moreover, you may make it share a part of member which comprises a viewing angle limiting element. FIG. 9 is a partial cross-sectional view showing another example of the viewing angle limiting element of the present invention. This viewing angle limiting element is the same as the element described with reference to FIG. 1 except that the protective film 210 constituting the second polarizing plate 2100 is omitted and the base film 200 constituting the liquid crystal film 1000 is used. The function of the protective film constituting 2100 is also used. In this case, the optical characteristics are not significantly different from those in the above embodiment, and a viewing angle limiting element that is as thin, light, and low in cost as the adhesive layer 400 and the protective film 210 can be realized.

  Further, a plurality of liquid crystal layers may be stacked in order to obtain desired characteristics. FIG. 10 is a partial cross-sectional view showing another example of the viewing angle limiting element of the present invention. This viewing angle limiting element is the viewing angle limiting element described with reference to FIG. 9, and liquid crystal films 1000b and 1000c are further provided between the liquid crystal film 1000 (indicated as 1000a in FIG. 10) and the second polarizing plate 2100. The layers are laminated through transparent adhesive layers 420 and 430.

  The liquid crystal films 1000a, 1000b, and 1000c are composed of a liquid crystal layer 100a and a base film 200a, a liquid crystal layer 100b and a base film 200b, and a liquid crystal layer 100c and a base film 200c, respectively.

  In this case, a viewing angle characteristic that cannot be obtained with a single liquid crystal film, for example, a viewing angle characteristic with a narrower viewing angle can be realized.

  Next, examples of the display device of the present invention will be described. FIG. 5 is a partial sectional view showing a schematic configuration of an embodiment of the display device of the present invention.

  This display device includes a liquid crystal display panel 10, an illumination device 20 disposed on the back surface thereof, and the viewing angle limiting element 30 described in the first embodiment between the liquid crystal display panel 10 and the illumination device 20. Is done.

  The illumination device 20 illuminates the display area of the liquid crystal display panel 10 from the back side. Examples of the illumination device 20 include an edge light method (light guide method), a direct method (reflecting plate method), and a planar light source method. The illumination device 20 may be selected from among these methods and other methods in accordance with the application, purpose, and display area size. Here, an edge light type backlight will be described, but the present invention is not limited to this.

  The illuminating device 20 includes a light guide 22 made of a transparent resin, on which a dot printing with a white pigment or a means for changing a traveling direction of light such as a fine uneven shape or a lens shape is formed on the back surface, and an end face of the light guide 22 A light source 21, a reflection sheet 23 disposed on the back side of the light guide 22, a prism sheet disposed on the front side of the light guide 22, and optical films 24 and 25 such as diffusion sheets. Yes.

  As the light source 21, a linear light source such as a cold cathode tube or a hot cathode tube or a point light source such as a light emitting diode (LED) can be used. Here, a case where an LED is used as the light source 21 will be described below, but the present invention is not limited to this.

  When an LED is used as the light source 21, in order to efficiently make light from the light source incident on the light guide 22, a reflector (not shown) may be provided, or the shape of the mold resin formed around the light emitting unit may be devised.

  In this configuration, light emitted from the light source 21 and incident on the light guide 22 propagates through the light guide 22 while being totally reflected. Of the light propagating in the light guide 22, the light that reaches the means for changing the light traveling direction, which is applied to the back surface of the light guiding body, changes its traveling direction and is emitted from the surface side of the light guide 22. The light emitted from the light guide 22 is adjusted in the emission angle distribution and the in-plane luminance distribution by an optical film such as a prism sheet or a diffusion sheet, and then the liquid crystal display panel 10 through the viewing angle limiting element 30. Is irradiated.

  The liquid crystal display panel 10 uses a transmissive or transflective liquid crystal display panel that displays an image by adjusting the amount of light transmitted from the illumination device 20.

  The liquid crystal display panel 10 is preferably provided with a polarizing plate, and the one that displays an image by controlling the polarization state of light incident on the liquid crystal layer is desirable because an image with a high contrast ratio can be obtained with a relatively low driving voltage. Such a liquid crystal display panel uses linearly polarized light as image light.

  As the liquid crystal display panel 10, for example, a TN (Twisted Nematic) method, a STN (Super Twisted Nematic) method, an ECB (Electrically Controlled Birefringence) method, or the like can be used. In addition, an IPS (In Plane Switching) method or a VA (Vertical Alried) method characterized by a wide viewing angle can be used.

  Alternatively, as the liquid crystal display panel 10, a transflective liquid crystal display panel to which the above method is applied can be used.

  Here, the case where the IPS system is used as the liquid crystal display panel 10 will be described below, but the present invention is not limited to this.

  The liquid crystal display panel 10 includes a transparent substrate 11 and a transparent substrate 12 for a display panel made of flat, transparent and optically isotropic glass or plastic. On the transparent substrate 11, a color filter and an alignment film (both not shown) made of polyimide polymer are laminated. The transparent substrate 12 is formed with an alignment film, an electrode for forming a pixel, a signal electrode, a switching element made of a thin film transistor, etc. (all not shown).

  FIG. 6 is a schematic front view showing the configuration of one pixel of the liquid crystal display panel 10 of the present embodiment. One pixel of the liquid crystal display panel 10 includes a common electrode 33 and a scanning signal electrode 34 formed on the transparent substrate 12, a video signal electrode 3100 and a pixel electrode 32 formed on the upper layer via an insulating film (not shown), an amorphous TFT (Thin Film Transistor) 3500 as a switching element constituted by a porous Si film or a polycrystalline Si film.

  The pixel electrode 32 partially overlaps with the common electrode 33 to form a storage capacitor. The common electrode 33 and the pixel electrode 32 divide one pixel into four regions, and have a zigzag shape while maintaining a substantially constant gap. Further, the zigzag inclination angle γ of the common electrode 33 and the pixel electrode 32 with respect to the vertical direction of the screen of the liquid crystal display panel is about ± 10 °. Further, a protective layer is formed on these upper layers, and an alignment film is formed thereon.

  The two transparent substrates 11 and 12 face each other with the alignment film forming surfaces facing each other, and a space is formed by adhering the periphery with a frame-shaped sealing material with a predetermined gap provided by a spacer (not shown). A liquid crystal layer 13 is provided by sealing and sealing nematic liquid crystal having positive dielectric anisotropy in this space.

  The alignment direction of the major axis of the liquid crystal molecule is defined in the liquid crystal layer 13 by the alignment treatment performed on the alignment films formed on the two transparent substrates 11 and 12. The liquid crystal alignment direction of the liquid crystal layer 13 is a so-called homogeneous alignment that does not twist between the two transparent substrates 11 and 12.

  A polarizing plate 2200 and a polarizing plate 2000 are provided on the front surface of the transparent substrate 11 and the back surface of the transparent substrate 12, respectively.

  FIG. 7 is a schematic cross-sectional view for explaining the vertical cross-sectional structure of the display device of this embodiment, and particularly shows the main constituent members involved in the optical operation of the liquid crystal display panel 10 and the viewing angle limiting element 30. Is.

  In this display device, the viewing angle limiting element 30 and the liquid crystal display panel 10 are arranged in this order from the lighting device side, and the first polarizing plate 2000 constituting the viewing angle limiting device 30 is arranged on the lighting device side of the liquid crystal display panel 10. It also serves as a polarizing plate to be arranged.

  Since the viewing angle limiting element 30 has been described in the above embodiment, the same portions are denoted by the same reference numerals and detailed description thereof is omitted.

  The viewing angle limiting element 30 is adhered to the transparent substrate 12 for the display panel constituting the liquid crystal display panel 10 by the adhesive layer 420. A transparent adhesive such as acrylic may be used for the adhesive layer. A liquid crystal layer 13 for a display panel is provided between the transparent substrates 11 and 12, and a third polarizing plate is adhered to the surface side of the transparent substrate 11 with an adhesive layer 430.

  As with the first polarizing plate 2000, the third polarizing plate 2200 stretches the base film made of polyvinyl alcohol or the like and aligns the dichroic material to align the polarizing layer 320 that exhibits absorption dichroism. A structure having a structure sandwiched between two protective films 230 and 240 made of an acetylcellulose film or the like can be used.

  FIG. 8 is a diagram illustrating an example of optical axes such as an absorption axis of a polarizing plate, an alignment axis of a liquid crystal layer for a display panel, and an alignment axis of a liquid crystal layer constituting a liquid crystal film according to the display device of this example.

  Here, as shown in the drawing, the alignment axis 13A of the liquid crystal layer 13 for display panel and the absorption axis 2200A of the linearly polarized light of the third polarizing plate 2200 are parallel to the vertical direction of the screen, and the linearly polarized light of the first polarizing plate 2000 is shown. A case will be described in which the absorption axis 2000A, the absorption axis 2100A of the second polarizing plate 2100, and the alignment axis 1000A of the liquid crystal layer of the liquid crystal film 1000 are orthogonal to the vertical direction of the screen.

  The light emitted from the illumination device 20 passes through the second polarizing plate 2100, then passes through the liquid crystal film 1000 and enters the first polarizing plate 2000.

  At this time, in the direction orthogonal to the alignment axis 1000A of the liquid crystal layer of the liquid crystal film 1000, a phase difference occurs in the light traveling in the oblique direction through the liquid crystal film 1000, the polarization state changes, and a part thereof is the first polarizing plate 2000. Absorbed in. On the other hand, in the direction parallel to the alignment axis 1000A of the liquid crystal layer of the liquid crystal film 1000, there is almost no phase difference in the light traveling in the oblique direction through the liquid crystal film 1000. Transmits without being absorbed.

  The light transmitted through the first polarizing plate 2000 passes through the liquid crystal layer 13 and enters the third polarizing plate 2200. At this time, the polarization state of the light passing through the liquid crystal layer 13 is controlled by applying a voltage corresponding to the video information transmitted from the video information generating unit (not shown) to the common electrode and the pixel electrode, and transmitted through the polarizing plate 2200. The desired image light can be formed by adjusting the amount of light to be emitted. In this case, in the direction orthogonal to the alignment axis 1000A of the liquid crystal layer 100 constituting the liquid crystal film 1000, the screen is dark and visible in a region where the polar angle (viewing angle) is larger than the direction parallel to the alignment axis 1000A of the liquid crystal layer. A bad display device can be realized. In the case of the optical axis arrangement illustrated in FIG. 8, the leakage of image light in the vertical direction of the screen can be reduced. Therefore, when applied to an on-vehicle monitor, image light is prevented from being reflected on the front glass of the automobile. A display device can be realized.

  In the display device of this embodiment, a polarizing plate including a polarizing layer constituting a viewing angle limiting element and a polarizing plate including a polarizing layer constituting a liquid crystal display panel are used as one polarizing plate.

  In this case, the light that is effectively used in the viewing angle limiting element and the light that is effectively used in the liquid crystal display panel are the same linearly polarized light, and the number of polarizing layers that cause light loss is reduced. A display device can be realized. Alternatively, a display device with lower power can be realized if the display has the same brightness.

  Furthermore, since there is no regular arrangement that causes moire between the viewing angle limiting elements and the pixel arrangement of the liquid crystal display panel, display without image quality deterioration due to moire can be realized.

  FIG. 11 is a diagram showing another example of optical axes such as an absorption axis of a polarizing plate, an alignment axis of a liquid crystal layer for a display panel, and an alignment axis of a liquid crystal layer constituting a liquid crystal film according to the display device of this example. is there. Here, as shown in the drawing, the alignment axis 13A of the liquid crystal layer 13 for display panel, the absorption axis 2000A of the linearly polarized light of the first polarizing plate 2000, the absorption axis 2100A of the second polarizing plate 2100, and the alignment of the liquid crystal layer of the liquid crystal film 1000 are shown. The axis 1000A is parallel to the vertical direction of the screen, and the absorption axis 2200A of the linearly polarized light of the third polarizing plate 2200 is orthogonal to the vertical direction of the screen.

  In this case, since the image light in the horizontal direction of the screen can be darkened, when applied to a display device of a portable device such as a mobile phone, a notebook PC, or a PDA, or a public device such as an ATM, the peeping from the horizontal direction is prevented. An effective display device can be realized.

  Although the case where the viewing angle limiting element is disposed between the liquid crystal display panel 10 and the lighting device 20 has been described here, the present invention is not limited to this. For example, the viewing angle limiting element may be arranged on the surface side of the liquid crystal display panel.

  FIG. 15 is a partial sectional view showing a schematic configuration of an embodiment of such a display device of the present invention. This display device is composed of a liquid crystal display panel 10, an illuminating device 20 disposed on the back surface thereof, and the viewing angle limiting element 30 described in (Example 1) disposed on the surface side of the liquid crystal display panel 10. Yes, the same members as those in the above embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  FIG. 16 is a schematic cross-sectional view for explaining the vertical cross-sectional structure of this display device, and particularly shows main constituent members involved in the optical operation of the liquid crystal display panel 10 and the viewing angle limiting element 30. . In this display device, the liquid crystal display panel 10 and the viewing angle limiting element 30 are arranged in this order from the lighting device side, and the second polarizing plate 2100 constituting the viewing angle limiting element 30 is arranged on the lighting device side of the liquid crystal display panel 10. It also serves as a polarizing plate to be arranged. The viewing angle limiting element 30 is adhered to the transparent substrate 11 for the display panel constituting the liquid crystal display panel 10 by the adhesive layer 420.

  FIG. 17 is a diagram showing an example of optical axes such as an absorption axis of a polarizing plate, an alignment axis of a liquid crystal layer for a display panel, and an alignment axis of a liquid crystal layer constituting a liquid crystal film according to this display device.

  Here, as illustrated, the alignment axis 13A of the liquid crystal layer 13 of the liquid crystal display panel 10, the absorption axis 2100A of the linearly polarized light of the second polarizing plate 2100, the alignment axis 1000A of the liquid crystal layer of the liquid crystal film 1000, and the first polarized light. The absorption axis 2000A of the linearly polarized light of the plate 2000 is parallel to the screen vertical direction, and the absorption axis 2200A of the third polarizing plate 2200 is orthogonal to the screen vertical direction.

  Also in this case, the display characteristics having the same characteristics as in the above embodiment can be obtained by the action of the viewing angle limiting element 30. That is, in the direction orthogonal to the alignment axis 1000A of the liquid crystal layer 100 constituting the liquid crystal film 1000, the screen is dark and the visibility is poor in a region where the polar angle (viewing angle) is larger than the direction parallel to the alignment axis 1000A of the liquid crystal layer. A display device can be realized.

  In this case, particularly when a transflective liquid crystal display panel is used as the liquid crystal display panel, a display device capable of limiting the viewing angle not only in the transmissive display mode but also in the reflective display mode can be realized.

  Next, another embodiment of the display device of the present invention will be described. FIG. 12 is a partial cross-sectional view showing a schematic configuration of one embodiment of the display device of the present invention.

  This display device includes a liquid crystal display panel 10, an illumination device 20 disposed on the back surface thereof, and a viewing angle limiting element 31 disposed between the liquid crystal display panel 10 and the illumination device 20.

  In this embodiment, a reflection type polarizing plate is newly provided in the viewing angle limiting element in the embodiment described with reference to FIG. For this reason, the same reference numerals are given to the same parts as those in the above-described embodiment, and the detailed description is omitted.

  In the display device of this example, the reflective polarizing plate 3000 and the reflective polarizing plate 3100 are disposed between the first polarizing plate 2000 and the liquid crystal film 1000 and on the back side of the second polarizing plate 2100 in the above-described embodiment. To do.

  FIG. 13 is a schematic cross-sectional view for explaining the vertical cross-sectional structure of the display device of this embodiment, and particularly shows the main components involved in the optical operation of the liquid crystal display panel 10 and the viewing angle limiting element 31. Is.

  In this display device, the viewing angle limiting element 31 and the liquid crystal display panel 10 are arranged in order from the lighting device side, and the first polarizing plate 2000 constituting the viewing angle limiting element 31 is disposed on the lighting device side of the liquid crystal display panel 10. It also serves as a polarizing plate to be arranged.

  The viewing angle limiting element 31 has a first reflective polarizing plate 3000 disposed between the first polarizing plate 2000 and the liquid crystal film 1000, and is adhered by transparent adhesive layers 440 and 410, respectively. Further, the second reflective polarizing plate 3100 is adhered to the lighting device side of the second polarizing plate 2100 with a transparent adhesive layer 450.

  As the reflective polarizing plate, one that can separate linearly polarized light components orthogonal to each other by reflection and transmission is used.

  As such a reflective polarizing plate, for example, a birefringence reflective polarizing film in which a plurality of polymer films having different birefringence disclosed in Patent Document 4 are laminated, or a phase difference between the front and back of a cholesteric liquid crystal film. A polarizing filter using a film, a dielectric multilayer film in which dielectrics having different refractive indexes are laminated, or a metal wire grid can be used.

  In the case of a birefringent reflective polarizing film, a predetermined linearly polarized light component of light incident on the birefringent reflective film is transmitted, and a linearly polarized light component whose polarization axis is orthogonal to this is reflected from 3M (USA) as a product name DBEF. It can be used as a reflective polarizing plate. A polarizing filter using a metal wire grid forms a conductive metal linear pattern of silver, aluminum, chrome, etc. on a transparent substrate at a pitch of a few hundred angstroms. The reflective polarizing plate can be realized.

  FIG. 14 shows optical axes such as an absorption axis of a polarizing plate, an alignment axis of a liquid crystal layer for a display panel, an alignment axis of a liquid crystal layer constituting a liquid crystal film, and a reflection axis of a reflective polarizing plate. It is a figure which shows an example.

  Here, as shown in the drawing, the alignment axis 13A of the liquid crystal layer 13 for display panel and the absorption axis 2200A of the linearly polarized light of the third polarizing plate 2200 are parallel to the vertical direction of the screen, and the linearly polarized light of the first polarizing plate 2000 is shown. The absorption axis 2000A of the second polarizing plate 2100A, the alignment axis 1000A of the liquid crystal layer of the liquid crystal film 1000, the linearly polarized reflection axis 3000A of the first reflective polarizing plate 3000, and the second reflective polarized light. A case where the linearly polarized reflection axis 3100A of the plate 3100 is orthogonal to the vertical direction of the screen will be described.

  The light emitted from the illumination device 20 is generally non-polarized light. For this reason, out of the light emitted from the illumination device 20 and incident on the second reflective polarizing plate 3100, linearly polarized light corresponding to the reflection axis of the second reflective polarizing plate is reflected, and the polarization direction is orthogonal to this. The linearly polarized light is transmitted.

  The light reflected by the second reflective polarizing plate 2100 returns to the illuminating device 20, and when reflected by the illuminating device 20, its polarization state changes and is incident on the second reflective polarizing plate 2100 again. At this time, a part of the light is reflected by the second reflective polarizing plate, but a part of the light is transmitted. By repeating this, much of the light emitted from the illumination device 20 is transmitted through the second reflective polarizing plate.

  The light transmitted through the second reflective polarizing plate passes through the second polarizing plate 2100 and the liquid crystal film 1000 and enters the first reflective polarizing plate 3000.

  At this time, in the direction orthogonal to the alignment axis of the liquid crystal layer of the liquid crystal film 1000, a phase difference occurs in the light traveling in the liquid crystal film 1000 in an oblique direction, and the polarization state changes, so that a part of the light is the first reflective type. Light reflected by the polarizing plate 3000 and transmitted is reduced.

  On the other hand, in the azimuth parallel to the alignment axis of the liquid crystal layer of the liquid crystal film 1000, almost no phase difference occurs in the light traveling in the oblique direction through the liquid crystal film 1000, so that the polarization state is substantially maintained and the first reflective polarizing plate 3000 The light passes through almost without reflection, and also passes through the first polarizing plate 2000.

  The light transmitted through the first polarizing plate 2000 passes through the liquid crystal layer 13 and enters the third polarizing plate 2200. At this time, the polarization state of the light passing through the liquid crystal layer 13 is controlled by applying a voltage corresponding to the video information transmitted from the video information generating unit (not shown) to the common electrode and the pixel electrode, and transmitted through the polarizing plate 2200. The desired image light can be formed by adjusting the amount of light to be emitted.

  That is, a display device having a dark screen in a region where the polar angle is larger in the direction perpendicular to the alignment axis 1000A of the liquid crystal layer constituting the liquid crystal film 1000 than in the direction parallel to the alignment axis 1000A of the liquid crystal layer can be realized.

  When the light reflected by the first reflective polarizing plate passes through the liquid crystal film 1000 again, a phase difference is generated, and the polarization state changes to change the second polarizing plate 2100 and the second reflective polarizing plate 3100. And returns to the lighting device 20.

  Since the illuminating device 20 includes a member that diffuses and reflects light such as a diffusion sheet, a part of the light returning to the illuminating device 20 is reflected again toward the front direction of the liquid crystal display panel 10 and is reused. The effect of improving the luminance of the image can also be obtained.

  In the case of the optical axis arrangement illustrated in FIG. 14, the leakage of image light in the vertical direction of the screen can be reduced. Therefore, when applied to an on-vehicle monitor, image light is prevented from being reflected on the front glass of the automobile. A display device can be realized.

  Further, in the display device of this embodiment, since the viewing angle limiting element is provided with the reflective polarizing plate, the amount of light absorbed and lost by the polarizing plate can be reduced. Can be realized, or a display device with lower power can be realized if the display has the same brightness.

  It should be noted that the image light is transmitted in the horizontal direction of the screen by changing the optical axis such as the absorption axis of the polarizing plate related to the display device, the alignment axis of the liquid crystal layer for display panel, and the alignment axis of the liquid crystal layer constituting the liquid crystal film It will be apparent from the above embodiment that a dark display device can be realized.

  In the display device of this embodiment, both or one of the first polarizing plate 2000 and the second polarizing plate 2100 may be omitted. In this case as well, the viewing angle limiting element functions, but since the degree of polarization of the reflective polarizing plate is generally lower than that of the absorption-type polarizing plate, the light shielding effect is reduced. In this case, however, a brighter display device can be realized because the number of members that absorb light is reduced.

  Next, another embodiment of the viewing angle limiting element of the present invention will be described. FIG. 18 is a partial cross-sectional view showing a schematic configuration of the viewing angle control element of the present invention. This viewing angle limiting element is the same as the viewing angle limiting element described with reference to FIG. 1, except that the configuration of the liquid crystal layer is mainly changed. Detailed description is omitted.

  The viewing angle limiting element 32 of the present embodiment includes a first polarizing plate 2000, a second polarizing plate 2100, and a liquid crystal film 1100 between these polarizing plates.

  The liquid crystal film 1100 includes transparent substrate films 250 and 251 and a liquid crystal layer 110 formed therebetween.

  The liquid crystal film 1100 is adhered to the polarizing plate 2000 with the adhesive layer 410 and the second polarizing plate 2100 with the adhesive layer 450. The adhesive layer is made of a transparent adhesive such as acrylic.

  FIG. 19 is a schematic diagram for explaining the structure of the liquid crystal film 1100. In this figure, the electrodes and the power source for fixing the alignment state of the liquid crystal layer 110 are schematically shown.

  The liquid crystal film 1100 is provided with alignment films 520 and 510 made of polyimide or the like on a base film 250 and a base film 251 having a small retardation in the in-plane direction such as triacetyl cellulose, and these films. A liquid crystal layer 110 made of rod-like liquid crystal molecules is provided between them.

  The liquid crystal layer 110 is basically oriented by twisting 90 ° between the two base films 250 and 251 by the orientation treatment on the orientation films 520 and 510.

  In order to make the liquid crystal layer non-fluid, a polymerizable group is introduced into the side chain terminal of the liquid crystal compound, a power source 5200 is connected between the electrodes 5000 and 5100, and a predetermined voltage is applied to the liquid crystal layer. It is important to fix the alignment state by polymerization.

  By controlling the electric field intensity when fixing the alignment state of the liquid crystal layer, the viewing angle characteristic of the viewing angle limiting element can be changed.

  FIG. 20 shows an absorption axis 2000A of the polarizing layer of the first polarizing plate 2000, an alignment axis 1100OA on the first polarizing plate side of the liquid crystal layer of the liquid crystal film 1100, an alignment axis 1100LA on the second polarizing plate side, It is a schematic diagram which shows the relationship of the absorption axis 2100A of the polarizing layer of the polarizing plate 2100.

  As shown in the drawing, in the viewing angle limiting element of this example, the absorption axes of the polarizing layers of the first polarizing plate and the second polarizing plate are orthogonal to each other, and the alignment axis of the liquid crystal layer of the liquid crystal film is the absorption axis of the polarizing layer. Arrange them so that they are parallel.

  Here, as shown, for convenience, when the azimuth angle in the right direction of the screen is 0 ° and the angle is defined counterclockwise, the absorption axis 2000A of the polarizing layer of the first polarizing plate 2000 is 45 °, and the liquid crystal film 1100 The alignment axis 1100A on the first polarizing plate side of the liquid crystal layer is 225 °, the alignment axis 1100LA on the second polarizing plate side, and the absorption axis 2100A of the polarizing layer of the second polarizing plate 2100 are 135 °.

  In this case, light incident on the liquid crystal layer of the liquid crystal film from the second polarizing plate 2100 (or the first polarizing plate 2000) side passes through the liquid crystal layer in the front direction, that is, in the direction where the azimuth angle and polar angle are 0 °. In doing so, the plane of polarization is rotated by 90 ° and transmitted through the first polarizing plate 2000 (or the second polarizing plate 2100).

  On the other hand, of the light incident on the liquid crystal layer of the liquid crystal film from the second polarizing plate 2100 (or the first polarizing plate 2000) side, a predetermined azimuth angle in which the effective phase difference of the liquid crystal layer 110 is 0 or becomes small. In the polar angle range, the light is absorbed by the first polarizing plate 2000 (or the second polarizing plate 2100).

  That is, a viewing angle limiting element capable of shielding light within a predetermined azimuth angle and polar angle range can be realized.

  For example, in the optical axis arrangement illustrated in FIG. 20, a liquid crystal layer constituting the liquid crystal film uses a nematic liquid crystal compound having a refractive index anisotropy Δn of 0.1 and a dielectric anisotropy Δε of 9.9. When the alignment state is fixed in a state where the liquid crystal layer thickness is 20 μm, the pretilt angle is about 3 degrees, and the electric field strength is 70 KV / m, a viewing angle limiting element having the characteristics illustrated in FIG. 21 can be realized.

  That is, it is possible to realize a viewing angle limiting element that has a wide viewing angle in the left-right direction and the downward direction and can reduce the amount of light emitted from the screen only in the upward direction. Such viewing angle characteristics are effective in preventing image light from being reflected on the front windshield of an automobile when applied to an on-vehicle monitor.

  Note that a part of the members constituting the viewing angle limiting element may be shared. FIG. 22 is a partial cross-sectional view showing another example of the viewing angle limiting element of the present invention. This viewing angle limiting element is the same as the element described with reference to FIG. 18 except that the protective film 210 constituting the second polarizing plate 2100 and the protective film 221 constituting the first polarizing plate are omitted, and the liquid crystal film 1100 is formed respectively. The base films 250 and 251 to be configured also serve as a protective film for the polarizing plate. In this case, the optical characteristics are not significantly different from those of the above-described embodiments, and a viewing angle limiting element that is thin, light, and low in cost can be realized as much as the adhesive layer and the protective film.

  In order to obtain desired characteristics, a plurality of viewing angle limiting elements may be laminated. In this case, two viewing angle limiting elements are simply laminated by using two polarizing plates (polarizing layers) disposed between the liquid crystal films constituting the plurality of viewing angle limiting elements. A thin and lightweight viewing angle limiting element can be realized at a lower cost than the case.

  Specifically, a viewing angle limiting element including a first polarizing layer, a second polarizing layer, and a third polarizing layer, and a first liquid crystal layer and a second liquid crystal layer, the first liquid crystal layer Is disposed between the first polarizing layer and the second polarizing layer, the second liquid crystal layer is disposed between the second polarizing layer and the third polarizing layer, and the first polarizing layer and the third polarizing layer are disposed. The absorption axes of the polarizing layers are parallel to each other, and the absorption axes of the second polarizing layer are arranged to be orthogonal to the absorption axes of the first polarizing layer and the third polarizing layer.

  The first and second liquid crystal layers are composed of rod-shaped liquid crystal molecules, twisted so that the alignment axes thereof are parallel or orthogonal to the absorption axes of the adjacent polarizing layers, respectively, and the liquid crystal molecules have predetermined azimuth and polar angles. , The alignment state is fixed so that the effective phase difference is zero.

  In this case, it is possible to realize an optical element having a low transmittance at a predetermined azimuth angle and polar angle at which the effective phase difference is zero in each of the two liquid crystal layers. That is, a viewing angle limiting element capable of shielding light at two predetermined azimuth angles and polar angles can be realized.

  In this case, a viewing angle characteristic that cannot be obtained by a single liquid crystal film, for example, a viewing angle characteristic with a narrower viewing angle, or a viewing angle limiting element capable of limiting light transmission in a range of a plurality of azimuth angles and polar angles is realized. be able to.

  Next, examples of the display device of the present invention will be described. FIG. 23 is a partial cross-sectional view showing a schematic configuration of an embodiment of the display device of the present invention.

  This display device includes a liquid crystal display panel 10, an illuminating device 20 disposed on the back surface thereof, and the viewing angle limiting element 32 described in the fourth embodiment between the liquid crystal display panel 10 and the illuminating device 20. Is done. For this reason, the same reference numerals are given to the same members as those in the above embodiment, and the detailed description is omitted.

  The liquid crystal display panel 10 uses a transmissive or transflective liquid crystal display panel that displays an image by adjusting the amount of light transmitted from the illumination device 20.

  The liquid crystal display panel 10 is preferably provided with a polarizing plate, and the one that displays an image by controlling the polarization state of light incident on the liquid crystal layer is desirable because an image with a high contrast ratio can be obtained with a relatively low driving voltage. Such a liquid crystal display panel uses linearly polarized light as image light.

  As the liquid crystal display panel 10, for example, a TN (Twisted Nematic) method, an STN (Super Twisted Nematic) method, an ECB (Electrical Controlled Birefringence) method, or the like can be used. In addition, an IPS (In Plane Switching) method or a VA (Vertical Alried) method characterized by a wide viewing angle can be used.

  Alternatively, as the liquid crystal display panel 10, a transflective liquid crystal display panel to which the above method is applied can be used.

  Here, the case where the liquid crystal display panel 10 is an active matrix drive type provided with a switching element such as a thin film transistor for each pixel and the TN mode is used as a display mode will be described, but the present invention is not limited to this.

  The liquid crystal display panel 10 includes a transparent substrate 11 and a transparent substrate 12 for a display panel made of flat, transparent and optically isotropic glass or plastic. On the transparent substrate 11, a color filter, a transparent electrode, and an alignment film (all not shown) made of a polyimide polymer are laminated. The transparent substrate 12 is formed with an alignment film, electrodes for forming pixels, signal electrodes, scanning electrodes, switching elements such as thin film transistors (all not shown).

  The two transparent substrates 11 and 12 face each other with the alignment film forming surfaces facing each other and form a space inside by adhering the periphery with a frame-shaped sealing material with a certain gap provided by a spacer (not shown). A liquid crystal layer 16 is provided by sealing and sealing nematic liquid crystal having positive dielectric anisotropy.

  The alignment direction of the major axis of the liquid crystal molecule is defined by the alignment treatment performed on the alignment film formed on the two transparent substrates 11 and 12. The liquid crystal layer 16 is made of twisted nematic liquid crystal in which the orientation direction of liquid crystal molecules is continuously twisted by 90 ° between the two transparent substrates 11 and 12. A polarizing plate 2200 and a polarizing plate 2000 are disposed on the front surface of the transparent substrate 11 and the back surface of the transparent substrate 12, respectively.

  In this display device, the viewing angle limiting element 32 and the liquid crystal display panel 10 are arranged in order from the lighting device 20 side, and the first polarizing plate 2000 constituting the viewing angle limiting element 32 is on the lighting device side of the liquid crystal display panel 10. The polarizing plate is also used as a polarizing plate.

  Since the viewing angle control element 32 has been described in the above embodiment, the same portions are denoted by the same reference numerals and detailed description thereof is omitted.

  The viewing angle limiting element 32 adheres to the transparent substrate 12 constituting the liquid crystal display panel 10 with an adhesive layer. A transparent adhesive such as acrylic may be used for the adhesive layer. Further, the liquid crystal layer 16 is provided between the transparent substrates 11 and 12, and the third polarizing plate 2200 is adhered to the surface side of the transparent substrate 11 with an adhesive.

  FIG. 24 is a schematic diagram for explaining the relationship between the optical axes such as the absorption axis of the polarizing plate, the alignment axis of the liquid crystal layer for display panel, and the alignment axis of the liquid crystal layer constituting the liquid crystal film according to the display device of this example. FIG.

  Here, for the sake of convenience, the azimuth angle in the right side of the screen is defined as 0 °, and the angle is defined counterclockwise. As shown in the figure, the absorption axis 2200A of the polarizing layer of the third polarizing plate 2200, the absorption axis 2100A of the polarizing layer of the second polarizing plate 2100, and the alignment axis of the liquid crystal layer of the liquid crystal film 1100 on the second polarizing plate side. 1100LA is set to 135 °, the alignment axis 16OA on the third polarizing plate side of the liquid crystal layer 16 and the absorption axis 2000A of the polarizing layer of the first polarizing plate 2000 are set to 45 °, and the first polarizing plate side of the liquid crystal layer 16 is set. The alignment axis 16LA is 315 °, and the alignment axis 1100OA on the first polarizing plate side of the liquid crystal layer of the liquid crystal film 1100 is 225 °.

  The light emitted from the lighting device 20 passes through the second polarizing plate 2100, then passes through the liquid crystal film 1100 and enters the first polarizing plate 2000.

  The light passing through the liquid crystal layer 110 of the liquid crystal film has a plane of polarization rotated by 90 ° when passing through the liquid crystal layer in the front direction, that is, in the range where the azimuth angle and polar angle are 0 ° and in the vicinity thereof. 2000 is transmitted.

  On the other hand, of the light that passes through the second polarizing plate 2100 and enters the liquid crystal layer of the liquid crystal film, the liquid crystal layer 110 has an effective phase difference of 0, or a predetermined azimuth and polar angle at which the phase difference becomes small. Light traveling into the range is absorbed by the first polarizing plate 2000.

  The light transmitted through the first polarizing plate 2000 passes through the liquid crystal layer 16 and enters the third polarizing plate 2200. At this time, the polarization state of light passing through the liquid crystal layer is controlled by applying a voltage corresponding to the video information transmitted from the video information generation unit (not shown) to the liquid crystal layer through the pixel electrode, and the polarizing plate 2200. The desired image light can be formed by adjusting the amount of light that passes through.

  In the display device of this embodiment, by arranging the optical axes illustrated in FIG. 24, it is possible to realize a display device that has a wide viewing angle in the left-right direction and the downward direction and a small amount of light emitted from the screen in the upward direction. Such viewing angle characteristics are effective in preventing image light from being reflected on the front windshield of an automobile when applied to an on-vehicle monitor.

  In the display device of this embodiment, the polarizing plate including the polarizing layer constituting the viewing angle limiting element and the polarizing plate including the polarizing layer constituting the liquid crystal display panel are used as one polarizing plate.

  In this case, the light that is effectively used in the viewing angle limiting element and the light that is effectively used in the liquid crystal display panel are the same linearly polarized light, and the number of polarizing layers that cause light loss is reduced. A display device can be realized. Alternatively, a display device with lower power can be realized if the display has the same brightness.

  Further, since there is no regular arrangement that causes moiré between the viewing angle limiting element and the pixel arrangement of the liquid crystal display panel, it is possible to realize display without image quality deterioration due to moiré.

  Next, embodiments of the viewing angle control element of the present invention will be described with reference to the drawings. FIG. 25 is a schematic sectional view for explaining an example of the viewing angle control element of the present invention.

  The viewing angle control element 35 includes a first transparent substrate 50 and a second transparent substrate 51 made of flat, transparent and optically isotropic glass or plastic, a polarization state switching means 1200 including a liquid crystal layer 150, an optical In particular, the retardation plate 70 is made of a negative uniaxial anisotropic medium, and the first polarizing plate 2000 and the second polarizing plate 2100 are included.

  A transparent electrode 60 and an alignment film 550 made of a polyimide-based polymer are laminated on the second transparent substrate 51. The first transparent substrate 50 has the same structure as the second transparent substrate 51 and the transparent electrode 61, In addition, an alignment film 551 is stacked.

  As the transparent electrode, a transparent conductive material mainly composed of indium oxide such as indium / zinc / oxide (also referred to as IZO) or indium / tin / oxide (also referred to as ITO) can be used.

  The transparent electrodes 60 and 61 formed on the two transparent substrates 50 and 51 are connected to a power source via wiring and switching elements (not shown), so that at least two predetermined electrodes are provided on the transparent electrodes 60 and 61. A voltage is selectively applied.

  In other words, a predetermined potential difference is generated in the transparent electrodes 60 and 61 so that a plurality of electric fields having a predetermined strength can be selectively applied to the liquid crystal layer 150.

  The two transparent substrates 50 and 51 are arranged so that the surfaces on which the transparent electrode and the alignment film are formed face each other, and a certain gap is provided between the two transparent substrates through a spacer (not shown). A space is formed by sealing the periphery of the gap in a frame shape with a sealing material 55. The liquid crystal layer 150 is configured by sealing nematic liquid crystal having positive dielectric anisotropy in this space.

  The alignment film 551 formed on the first transparent substrate 50 is a vertical alignment film that aligns liquid crystal molecules in a direction perpendicular to the substrate surface, and the alignment film 550 formed on the second transparent substrate is formed by an alignment process such as a rubbing process. An alignment film in which the liquid crystal molecules are aligned in a state slightly tilted from 2 to 4 degrees from the substrate surface. For this reason, the liquid crystal layer 150 of this viewing angle control element is aligned with the liquid crystal molecules at an angle perpendicular to or close to the substrate surface on the first transparent substrate side, and with respect to the substrate surface on the second transparent substrate side. Thus, a hybrid orientation in which the orientation angle continuously changes in the thickness direction is obtained by orientation in a state that is parallel or slightly inclined.

  A phase difference plate 70 made of an optically negative uniaxial anisotropic medium is provided on the first transparent substrate side of the polarization state switching unit 1200. As the retardation plate 70, a film of triacetyl cellulose used as a protective film for a polarizing plate can be used.

  The optical properties of the retardation plate 70 are characterized by the thickness direction retardation value Rth defined by the equation (1).

    Rth = (nz− (nx + ny) / 2) d (1)

  Here, nz is the refractive index in the thickness direction, nx and ny are the main refractive indexes in the in-plane direction, and d is the thickness. In general, a triacetyl cellulose film used as a protective film for a polarizing plate has a thickness of about Rth = −40 nm, but there is a triacetyl cellulose film having a thickness of 2 to 3 times, that is, Rth = −80 to −120 nm. The value of Rth required for the phase difference plate 70 varies depending on the characteristics required for the viewing angle control element. To achieve Rth with a larger absolute value, the thickness of the triacetylcellulose film is increased, or a plurality of films are laminated, or a film made of a polymer material having a large absolute value of Rth other than triacetylcellulose is used. Alternatively, a cholesteric liquid crystal layer is used.

  In the case of using a cholesteric liquid crystal layer, the pitch may be adjusted so that the wavelength range of selective reflection expressed by the cholesteric liquid crystal layer does not exist in the visible wavelength range. When light is incident from an oblique direction, the wavelength range of selective reflection shifts to the short wavelength side. Therefore, even if light is incident from an oblique direction, the wavelength range of selective reflection is the ultraviolet region. It is desirable to prevent light from reflecting.

  A first polarizing plate 2000 and a second polarizing plate 2100 are provided outside the phase difference plate 70 and the second transparent substrate 51, respectively. The polarizing plate described above can be used as the polarizing plate.

  The first transparent substrate 50 and the phase difference plate 70, the phase difference plate 70 and the first polarizing plate 2000, and the second transparent substrate 51 and the second polarizing plate 2100 are interposed through an acrylic or other transparent adhesive. And stick.

  FIG. 26 is a diagram illustrating an example of optical axes such as an absorption axis of a polarizing plate and an alignment axis of a liquid crystal layer according to the viewing angle control element of this example.

  Hereinafter, as illustrated, the absorption axis 2000A of the first polarizing plate 2000, the alignment axis 1200A of the liquid crystal layer 150 of the polarization state switching unit 1200 on the second transparent substrate 51 side, and the second polarizing plate 2100 Both absorption axes 2100A are in a direction parallel to the vertical direction for convenience. In this case, when any voltage of about 0 to 3 V is applied to the liquid crystal layer 150, the transmittance in the oblique direction, that is, in the range where the polar angle is large, in the direction perpendicular to the alignment axis 1200A of the liquid crystal layer 150 and in the vicinity thereof. And the viewing angle is narrowed. On the other hand, when a voltage of 7 V or more is applied to the liquid crystal layer, the transmittance increases in the oblique direction in the same direction, that is, in the range where the polar angle is large, and the viewing angle increases.

  At this time, in the direction parallel to the alignment axis of the liquid crystal layer 150, the transmittance does not change in the oblique direction regardless of the change in the voltage applied to the liquid crystal layer 150.

  For example, as the nematic liquid crystal constituting the liquid crystal layer 150, a liquid crystal layer having a refractive index anisotropy Δn of 0.095 and a dielectric anisotropy Δε of 5.2 is used. Is −500 nm, the viewing angle control element having the viewing angle characteristics illustrated in FIGS. 27 and 28 can be realized.

  FIG. 27 is an equitransmittance diagram showing the viewing angle characteristics of the viewing angle control element 35. The AC voltage applied to the liquid crystal layer 150 of the polarization state switching means 1200 via the transparent electrode 60 and the transparent electrode 61 is 2V and 9V. The state when In FIG. 27, the transmittance at a viewing angle (polar angle) of 0 ° is normalized to 100%, and 90% to 20% are described every 10%.

  28 shows the viewing angle (polar angle) on the horizontal axis and the transmittance on the vertical axis, and shows the viewing angle dependence of the transmittance in the vertical and horizontal directions for convenience shown in FIG.

  As shown in the figure, when the liquid crystal layer 150 of the polarization state switching unit 1200 is driven at 2 V, the transmittance decreases in the left-right direction as the viewing angle increases. On the other hand, when the liquid crystal layer 150 of the polarization state switching unit 1200 is driven at 9 V, high transmittance can be realized in a wide viewing angle range. At this time, in the vertical direction, the transmittance does not change regardless of the driving voltage of the liquid crystal layer 150 of the polarization state switching unit 1200.

  That is, the viewing angle in the direction orthogonal to the alignment axis of the liquid crystal layer can be narrowed or widened by changing the voltage applied to the liquid crystal layer 150 of the polarization state switching means 1200, that is, the driving voltage. An angle control element can be realized.

  When the retardation plate 70 is made of triacetyl cellulose, the protective film and the adhesive layer can be omitted by using the protective film of the first polarizing plate and the retardation plate 70, so that the viewing angle is thinner and lighter. A control element can be realized.

  Next, another embodiment of the display device of the present invention will be described with reference to the drawings. FIG. 29 is a partial cross-sectional view showing a schematic configuration of an embodiment of a display device of the present invention.

  This display device is composed of a liquid crystal display panel 10, an illuminating device 20 disposed on the back surface thereof, and the viewing angle control element 35 described in the sixth embodiment. The members having the same functions as those of the above-described embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  Here, the case where the IPS system is used as the liquid crystal display panel 10 will be described as in the above-described embodiment described with reference to FIG. 5, but the present invention is not limited to this.

  In this display device, the liquid crystal display panel 10 and the viewing angle control element 35 are arranged in order from the lighting device 20 side, and the second polarizing plate 2100 constituting the viewing angle control element 35 is arranged on the surface side of the liquid crystal display panel 10. It also serves as a polarizing plate to be arranged.

  For this reason, the second polarizing plate 2100 may be adhered to the transparent substrate 11 of the liquid crystal display panel 10 with an adhesive and may be disposed apart from the second transparent substrate 51 of the viewing angle control element 35, but an unnecessary interface. In order to reduce reflection, an adhesive may be provided between the second transparent substrate 51 and the second polarizing plate 2100, or a transparent medium having a refractive index close to these may be filled.

  The third polarizing plate 2300 adheres to the transparent substrate 12 constituting the liquid crystal display panel with an adhesive.

  FIG. 30 is a diagram for explaining the relationship among optical axes such as the absorption axis of the polarizing plate, the alignment axis of the liquid crystal layer of the liquid crystal display panel, and the alignment axis of the liquid crystal layer of the polarization state switching means according to the display device of this embodiment. FIG.

  Here, hereinafter, as shown in FIG. 30, the absorption axis 2000A of the first polarizing plate 2000, the alignment axis 1200A of the liquid crystal layer 150 of the polarization state switching means 1200, the absorption axis 2100A of the second polarizing plate 2100, and the liquid crystal The alignment axis 13A of the liquid crystal layer 13 of the display panel is parallel to the vertical direction of the screen, and the absorption axis 2300A of the third polarizing plate 2300 is arranged to be orthogonal to the vertical direction of the screen.

  In this case, the light emitted from the illumination device 20 enters the third polarizing plate 2200 that constitutes the liquid crystal display panel 10.

  The light transmitted through the third polarizing plate 2200 passes through the liquid crystal layer 13 and enters the second polarizing plate 2100. At this time, by applying a voltage corresponding to the video information transmitted from the video information generation unit (not shown), the polarization state of the light passing through the liquid crystal layer 13 is controlled, and the amount of light passing through the polarizing plate 2100 is adjusted. As a result, image light is formed.

  The image light transmitted through the second polarizing plate 2100 passes through the polarization state switching means 1200 and the phase difference plate 70 that constitute the viewing angle control element 35 and enters the first polarizing plate 2000.

  When any voltage of about 0 to 3 V is applied to the liquid crystal layer 150 of the viewing angle control element, the direction perpendicular to the alignment axis on the second polarizing plate 2100 side of the liquid crystal layer 150 and the region in the vicinity thereof, that is, the oblique direction, In the range where the polar angle is large, the transmittance is lowered and the viewing angle is narrowed. On the other hand, when a voltage of 7 V or higher is applied to the liquid crystal layer 150, the transmittance increases in the oblique direction in the same direction, that is, in the range where the polar angle is large, and the viewing angle becomes wide.

  At this time, in the direction parallel to the alignment axis of the liquid crystal layer 150, the transmittance does not change in the oblique direction regardless of the change in the voltage applied to the liquid crystal layer 150.

  That is, by changing the voltage applied to the liquid crystal layer 150 of the polarization state switching means 1200, that is, the driving voltage, the viewing angle in the direction orthogonal to the alignment axis of the liquid crystal layer 150 can be narrowed or widened. .

  In the case of the optical axis arrangement illustrated in FIG. 30, the brightness of the image light in the left-right direction of the screen can be arbitrarily reduced to deteriorate visibility. Such switching of viewing angle characteristics is effective in preventing a peep from the side when applied to a display device of a portable device such as a mobile phone, a notebook PC, or a PDA, or a public device such as an ATM.

  In the display device of this embodiment, the polarizing plate constituting the viewing angle control element and the polarizing plate constituting the liquid crystal display panel are combined with one polarizing plate. In this case, the light that is effectively used in the viewing angle control element and the light that is effectively used in the liquid crystal display panel are the same linearly polarized light, and the number of polarizing layers that cause the loss of light is reduced. Display device can be realized. Alternatively, a display device with lower power can be realized if the display has the same brightness.

  In the display device of this embodiment, the viewing angle control element 35 is disposed on the front side of the liquid crystal display panel. In this case, when a transflective type is applied as the liquid crystal display panel, a display device capable of switching the viewing angle not only in transmissive display but also in reflective display can be realized.

  In the display device of this embodiment, the case where the viewing angle control element is arranged on the front side of the liquid crystal display panel is described, but the present invention is not limited to this. That is, the viewing angle control element may be disposed between the liquid crystal display panel and the lighting device.

  At this time, a reflective polarizing plate may be disposed on both the first polarizing plate and the second polarizing plate constituting the viewing angle control element, or on the light source side of at least one polarizing plate. Alternatively, both or at least one of the first polarizing plate and the second polarizing plate may be a reflective polarizing plate. Further, it is preferable that the illumination device includes a diffuse reflection means for diffusing and reflecting the light reflected by the reflective polarizing plate and returning to the illumination device.

  In this case, part of the light emitted from the illumination device 20 is reflected by the reflective polarizing plate and returns to the illumination device 20 again. The light returning to the illuminating device 20 is reflected and reused. At this time, when the viewing angle is narrowed by the viewing angle control element, a part of the reused light returns to the front direction. The effect that the brightness is improved is obtained.

  Next, another embodiment of the viewing angle control element of the present invention will be described with reference to the drawings. FIG. 31 is a schematic sectional view for explaining an example of the viewing angle control element of the present invention. This viewing angle control element is the same as the viewing angle control element described in Example 6, except that the orientation state of the liquid crystal molecules in the liquid crystal layer and the direction of the absorption axis of the polarizing plate are changed, and the retardation plate 70 is eliminated. The same members as those in the embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  The viewing angle control element 36 includes a first transparent substrate 50 and a second transparent substrate 51, a polarization state switching unit 1300 including a liquid crystal layer 160, a first polarizing plate 2000 and a second polarizing plate 2100. The

  The first transparent substrate 50 includes a transparent electrode 62 and an alignment film 553 made of a polyimide polymer, and the second transparent substrate 51 includes the first transparent substrate 50 and the transparent electrode 63. In addition, an alignment film 552 is stacked.

  The transparent electrodes 62 and 63 formed on the two transparent substrates 50 and 51 are connected to a power source via wiring and switching elements (not shown), so that at least two predetermined electrodes are provided on the transparent electrodes 62 and 63. A voltage is selectively applied.

  That is, by setting the transparent electrodes 62 and 63 to a predetermined potential, a plurality of electric fields having a predetermined intensity can be selectively applied to the liquid crystal layer 160.

  The two transparent substrates 50 and 51 are arranged so that the surfaces on which the transparent electrode and the alignment film are formed face each other. At this time, a fixed gap is provided between the two transparent substrates by sandwiching a spacer (not shown), and a space is formed by sealing the periphery of the gap in a frame shape with the sealing material 55. The liquid crystal layer 160 is configured by sealing nematic liquid crystal having positive dielectric anisotropy in this space.

  In this embodiment, the alignment films 553 and 552 formed on two transparent substrates are each subjected to an alignment process such as a rubbing process, so that the liquid crystal molecular major axis of the liquid crystal layer 160 is continuously between the two transparent substrates. Thus, a so-called TN liquid crystal element configured to be twisted by 90 ° is formed.

  A first polarizing plate 2000 and a second polarizing plate 2100 are provided outside the first transparent substrate 50 and the second transparent substrate 51, respectively. The polarizing plate described above can be used as the polarizing plate.

  The first transparent substrate 50 and the first polarizing plate 2000, and the second transparent substrate 51 and the second polarizing plate 2100 are adhered through a transparent adhesive such as acrylic.

  FIG. 32 is a diagram illustrating an example of optical axes such as an absorption axis of a polarizing plate and an alignment axis of a liquid crystal layer according to the viewing angle control element of this example. As shown in the drawing, in the viewing angle control element of this example, the absorption axes of the polarizing layers of the first polarizing plate 2000 and the second polarizing plate 2100 are orthogonal to each other, and the alignment axes of the liquid crystal layers of the polarization state switching means 1300 are respectively It arrange | positions so that it may become parallel with the absorption axis of the polarizing plate which adjoins.

  Here, as shown, for convenience, when the azimuth angle in the right direction of the screen is 0 ° and the angle is defined counterclockwise, the absorption axis 2000A of the polarizing layer of the first polarizing plate 2000 is 45 °, and the polarization state is switched. The alignment axis 1300OA on the first polarizing plate side of the liquid crystal layer 160 of the means 1300 is set to 225 °, the alignment axis 1300LA on the second polarizing plate side of the liquid crystal layer 160 of the polarization state switching means 1300, and the second polarizing plate 2100. The absorption axis 2100A of the polarizing layer is set to 135 °.

  When a driving voltage is not applied to the liquid crystal layer 160 of the polarization state switching unit 1300, most of the light transmitted through the second polarizing plate 2100 and incident on the polarization state switching unit 1300 passes through the liquid crystal layer 160. The light has a plane of polarization rotated by 90 ° and is transmitted through the first polarizing plate 2000, so that the transmittance is increased over a wide viewing angle range.

  On the other hand, when a driving voltage is applied to the liquid crystal layer 160 of the polarization state switching unit 1300, the effective phase difference of the liquid crystal layer 160 is 0 out of the light transmitted through the second polarizing plate 2100 and incident on the polarization state switching unit 1300. Alternatively, most of the light traveling in a predetermined azimuth angle and polar angle direction having a value close to 0 is absorbed by the first polarizing plate 2000.

  That is, when a voltage is not applied to the liquid crystal layer 160, a wide viewing angle can be obtained, and when a driving voltage is applied to the liquid crystal layer 160, a viewing angle control element that can shield light in a predetermined azimuth angle and polar angle direction can be realized.

  For example, the nematic liquid crystal constituting the liquid crystal layer 160 has a refractive index anisotropy Δn of 0.1 and a dielectric anisotropy Δε of 9.9, a liquid crystal layer thickness of 29 μm, and a pretilt angle of about 3 degrees. In this case, the viewing angle control element having the viewing angle characteristic illustrated in FIG. 33 can be realized.

  FIG. 33 is a diagram showing the viewing angle dependence of the transmittance in the vertical direction for convenience shown in FIG. 32, with the horizontal axis representing the viewing angle (polar angle) and the vertical axis representing the transmittance.

  As shown in the figure, when a voltage is applied to the liquid crystal layer 160 of the polarization state switching means 1300, the transmissivity in the left-right direction and the downward direction hardly changes, but the transmissivity is reduced in a predetermined viewing angle range corresponding to the drive voltage only in the upward direction. can do.

  That is, it is possible to realize a viewing angle control element that has a wide viewing angle in the left-right direction and the downward direction, and can switch the screen brightness as needed only in the upward direction. Such viewing angle characteristics are effective in preventing image light from being reflected on the front windshield of an automobile when applied to an on-vehicle monitor.

  As a result of the examination, it is desirable to set the value of Δnd of the liquid crystal layer to 2000 nm or more in order to control the transmittance in a predetermined azimuth angle and polar angle direction with almost no change in the transmittance in the front direction. found. When the TN display mode is applied to the liquid crystal display panel, this is about four times larger than the Δnd value of the liquid crystal layer of about 400 to 500 nm, and cannot be easily estimated.

  On the other hand, if the Δnd value of the liquid crystal layer 160 is too large, the minimum value of the transmittance obtained in a predetermined azimuth angle and polar angle direction where the transmittance is desired to be controlled becomes high, and a sufficient light shielding effect cannot be obtained. Therefore, it is desirable that the value of Δnd of the liquid crystal layer 160 be 5000 nm or less.

  That is, it is desirable that the Δnd of the liquid crystal layer of the viewing angle control element using the TN liquid crystal as in this embodiment be 2000 nm or more and 5000 nm or less. In particular, in the azimuth angle and polar angle direction where it is not necessary to control the transmittance, the change in the transmittance when a predetermined voltage is applied to the liquid crystal layer is further reduced, and the predetermined azimuth angle and In order to reduce the minimum transmittance obtained in the polar angle direction, it is desirable to set the liquid crystal layer to Δnd 2500 nm to 3500 nm.

  The driving voltage of the liquid crystal layer 160 is preferably 3 V or less, more preferably 2 V or less, in order to reduce the change in transmittance in the front direction. At this time, the frequency is set to a value that does not cause flicker and does not deteriorate the display of the liquid crystal display panel. Specifically, it may be 60 Hz or more.

  Next, another embodiment of the display device of the present invention will be described with reference to the drawings. FIG. 34 is a partial sectional view showing a schematic configuration of an embodiment of the display device of the present invention.

  This display device is composed of a liquid crystal display panel 10, an illuminating device 20 disposed on the rear surface thereof, and the viewing angle control element 36 described in the eighth embodiment regarding the surface side of the liquid crystal display panel 10. The members having the same functions as those of the above-described embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  Here, the case where the TN method is used as the liquid crystal display panel 10 will be described as in the above-described embodiment described with reference to FIG. 23, but the present invention is not limited to this.

  In this display device, the liquid crystal display panel 10 and the viewing angle control element 36 are arranged in order from the lighting device 20 side, and the second polarizing plate 2100 constituting the viewing angle control element 36 is disposed on the surface side of the liquid crystal display panel 10. It also serves as a polarizing plate to be arranged.

  For this reason, the second polarizing plate 2100 may be adhered to the transparent substrate 11 of the liquid crystal display panel 10 with an adhesive, and may be disposed apart from the second transparent substrate 51 of the viewing angle control element 36.

  The third polarizing plate 2300 adheres to the transparent substrate 12 constituting the liquid crystal display panel 10 with an adhesive.

  FIG. 35 is a diagram for explaining the relationship among the optical axes such as the absorption axis of the polarizing plate according to the display device of this embodiment, the alignment axis of the liquid crystal layer of the liquid crystal display panel, and the alignment axis of the liquid crystal layer of the polarization state switching means. FIG.

  As shown in FIG. 35, for convenience, when the azimuth angle on the right side of the screen is 0 ° and the angle is defined counterclockwise, the absorption axis 2000A of the polarizing layer of the first polarizing plate 2000 is 45 °, and the polarization state switching means The alignment axis 1300OA on the first polarizing plate side of the liquid crystal layer 1300 is 225 °, the alignment axis 1300LA on the second polarizing plate side of the liquid crystal layer of the polarization state switching means 1300, and the polarizing layer of the second polarizing plate 2100 The absorption axis 2100A is 135 °.

  The alignment axis 16OA on the second polarizing plate side of the liquid crystal layer 16 of the liquid crystal display panel 10 is 45 °, the alignment axis 16LA on the third polarizing plate side of the liquid crystal layer 16 of the liquid crystal display panel 10 is 315 °, The absorption axis 2300A of the third polarizing plate is 45 °.

  In this case, the light emitted from the illumination device 20 and transmitted through the third polarizing plate 2300 constituting the liquid crystal display panel 10 passes through the liquid crystal layer 16 and enters the second polarizing plate 2100. At this time, the polarization state of light passing through the liquid crystal layer 16 is controlled by applying a voltage corresponding to the video information transmitted from the video information generating unit (not shown) to the liquid crystal layer 16, and the second polarizing plate 2100 is Desired video light can be formed by adjusting the amount of transmitted light.

  The image light that passes through the second polarizing plate 2100 passes through the polarization state switching means that constitutes the viewing angle control element 36 and enters the first polarizing plate 2000.

  When a driving voltage is not applied to the liquid crystal layer 160 of the polarization state switching unit, most of the light transmitted through the second polarizing plate 2100 and incident on the polarization state switching unit passes through the liquid crystal layer 160. The plane of polarization of the light is rotated by 90 ° and is transmitted through the first polarizing plate 2000, so that the transmittance is high over a wide viewing angle range.

  On the other hand, when a driving voltage is applied to the liquid crystal layer 160 of the polarization state switching unit, the effective phase difference of the liquid crystal layer 160 is 0 or less among the light that is transmitted through the second polarizing plate 2100 and incident on the polarization state switching unit. Light traveling in a predetermined azimuth angle and polar angle direction close to 0 is absorbed by the first polarizing plate 2000.

  That is, it is possible to realize a display device that can obtain a wide viewing angle when no driving voltage is applied to the liquid crystal layer 160 and can darken image light in a predetermined azimuth angle and polar angle direction when a driving voltage is applied to the liquid crystal layer.

  In the display device of this embodiment, a display device that can control the brightness of the image light in the upward direction of the screen can be realized. Such viewing angle characteristics are effective in preventing the reflection of image light on the front windshield of an automobile when necessary when applied to an on-vehicle monitor.

  Further, by changing the optical axis of the liquid crystal layer 16 of the viewing angle control element 36, a display device can be realized in which the brightness of an image can be switched when observing from a predetermined polar angle direction at an azimuth angle corresponding to the right direction of the screen. For example, as shown in FIG. 36, when the azimuth angle in the right direction of the screen is 0 ° and the angle is defined counterclockwise, the absorption axis 2000A of the polarizing layer of the first polarizing plate 2000 is 45 °, and the polarization state switching means 1300 The alignment axis 1300OA on the first polarizing plate side of the liquid crystal layer is 135 °, the alignment axis 1300LA on the second polarizing plate side of the liquid crystal layer of the polarization state switching means 1300 is 45 °, and the second polarizing plate 2100 The absorption axis 2100A of the polarizing layer is 135 °. The alignment axis 16OA on the second polarizing plate side of the liquid crystal layer 16 of the liquid crystal display panel 10 is 45 °, the alignment axis 16LA on the third polarizing plate side of the liquid crystal layer 16 of the liquid crystal display panel 10 is 315 °, The absorption axis 2300A of the third polarizing plate is 45 °.

  In this case, it is possible to realize a display device that can arbitrarily switch between a state in which a bright image can be observed and a state in which the image becomes dark and sufficient visibility cannot be obtained when the screen is observed from the right oblique direction.

  When such a viewing angle characteristic is applied to a vehicle-mounted monitor, for example, in the case of a right-hand drive vehicle, the visibility on the driver side can be switched according to the traveling state of the vehicle. For example, while the car is stopped, the screen can be observed from both the driver's seat and the passenger's seat, but when the car is running, the image can be observed from the passenger's seat as if it was stopped, but the image is sufficient from the driver's seat. It can be made invisible.

  In other words, when images such as TV and DVD are displayed on a vehicle-mounted monitor, the image can be viewed as usual from an observer other than the driver, but by making it invisible to the driver, the driver This can increase the concentration of people and promote safe driving.

  In the display device of this embodiment, the polarizing plate constituting the viewing angle control element and the polarizing plate constituting the liquid crystal display panel are shared by one polarizing plate. In this case, the light that is effectively used in the viewing angle control element and the light that is effectively used in the liquid crystal display panel are the same linearly polarized light, and the number of polarizing layers that cause the loss of light is reduced. Display device can be realized. Alternatively, a display device with lower power can be realized if the display has the same brightness.

  In the display device of this embodiment, the viewing angle control element 36 is arranged on the front side of the liquid crystal display panel. In this case, when the transflective type is applied as the liquid crystal display panel, a display device capable of switching the viewing angle not only in the transmissive display mode but also in the reflective display mode can be realized.

  In the display device of this embodiment, the case where the viewing angle control element 36 is arranged on the front side of the liquid crystal display panel 10 has been described, but the present invention is not limited to this. That is, the viewing angle control element 36 may be disposed between the liquid crystal display panel 10 and the lighting device 20.

  Next, another embodiment of the display device of the present invention will be described with reference to the drawings. FIG. 37 is a partial cross-sectional view showing a schematic configuration of an embodiment of the display device of the present invention.

  In this display device, a viewing angle control element is further added to the surface side of the display device described in the ninth embodiment. That is, the display device 1 of the present embodiment includes the liquid crystal display panel 10, the illumination device 20 disposed on the back surface thereof, the viewing angle control element 36 disposed on the front surface side of the liquid crystal display panel 10, and the visual field disposed on the front surface side. A member that is composed of the corner control element 37 and that has the same function as in the above embodiment is given the same reference numeral, and detailed description thereof is omitted.

  In this display device, a liquid crystal display panel 10, a viewing angle control element 36, and a viewing angle control element 37 are arranged in this order from the lighting device 20 side.

  The viewing angle control element 37 has the same basic structure as the viewing angle control element 36. That is, the two transparent substrates 52 and 53 on which the transparent electrode and the alignment film are formed, the liquid crystal layer 170 sealed between the transparent substrates, and the front surface side of the transparent substrate 52 and the back surface side of the transparent substrate 53 are disposed. It is comprised from a polarizing plate. The alignment axis of the liquid crystal layer 170 constituting the viewing angle control element 37 and the absorption axis of the polarizing layer of the polarizing plate 2400 disposed on the surface side thereof are different from those of the viewing angle control element 36.

  In this embodiment, the second polarizing plate 2100 constituting the viewing angle control element 36 is also used as a polarizing plate disposed on the surface side of the liquid crystal display panel 10, and the first polarizing plate 2100 constituting the viewing angle control element 36 is used. The polarizing plate 2000 is also used as a polarizing plate disposed on the back side of the viewing angle control element 37.

  Here, the first polarizing plate 2000 is adhered to the transparent substrate 50 constituting the viewing angle control element 36 by an adhesive, and the second polarizing plate 2100 is adhered to the transparent substrate 11 constituting the liquid crystal display panel 10 by an adhesive. To do. The third polarizing plate 2300 adheres to the transparent substrate 12 constituting the liquid crystal display panel 10 with an adhesive, and the polarizing plate 2400 adheres to the transparent substrate 52 constituting the viewing angle control element 37 with an adhesive. Does not limit the transparent substrate that adheres the polarizing plate.

  FIG. 38 is a diagram for explaining the relationship between the optical axes such as the absorption axis of the polarizing plate, the alignment axis of the liquid crystal layer of the liquid crystal display panel, and the alignment axis of the liquid crystal layer of the viewing angle control element according to the display device of this embodiment. FIG.

  As shown in FIG. 38, the display device of the present embodiment is the same as the above-described embodiment described with reference to FIG. 36 with respect to the absorption axis of the polarizing plate and the alignment axis of the liquid crystal layer of the liquid crystal display panel 10 and the viewing angle control element 36. And In addition, the alignment axis 170LA on the first polarizing plate 2000 side of the liquid crystal layer 170 of the viewing angle control element 37 is 225 °, and the alignment axis 170OA on the polarizing plate 2400 side is 315 °. The absorption axis 2400A of the polarizing layer of the polarizing plate 2400 is 135 °.

  In FIG. 38, the notation of the sign of the alignment axis of the liquid crystal layer of the viewing angle control element 36 is different from that of FIG. 36, and the alignment axis of the liquid crystal layer 160 on the first polarizing plate 2000 side is expressed as 160OA. The orientation axis 160LA of the liquid crystal layer 160 on the plate 2001 side is indicated. These are shown in FIG. 36 as the alignment axis 1300OA on the first polarizing plate side and the alignment axis 1300LA on the second polarizing plate side of the liquid crystal layer of the polarization state switching means 1300 constituting the viewing angle control element 36, respectively. Indicates the same thing.

  In this case, the light emitted from the illumination device 20 and transmitted through the third polarizing plate 2300 constituting the liquid crystal display panel 10 passes through the liquid crystal layer 16 and enters the second polarizing plate 2100. At this time, the polarization state of light passing through the liquid crystal layer 16 is controlled by applying a voltage corresponding to the video information transmitted from the video information generating unit (not shown) to the liquid crystal layer 16, and the second polarizing plate 2100 is Desired video light can be formed by adjusting the amount of transmitted light.

  The light transmitted through the second polarizing plate 2100 passes through the liquid crystal layer 160 constituting the viewing angle control element 36 and enters the first polarizing plate 2000.

  When no driving voltage is applied to the liquid crystal layer 160 of the viewing angle control element 36, most of the light that passes through the second polarizing plate 2100 and passes through the liquid crystal layer 160 has a plane of polarization rotated by 90 °. Therefore, the transmittance is high over a wide viewing angle range.

  On the other hand, when a driving voltage is applied to the liquid crystal layer 160 of the viewing angle control element 36, the effective phase difference of the liquid crystal layer 160 of the light passing through the second polarizing plate 2100 and passing through the liquid crystal layer 160 is 0, or Light traveling in a predetermined azimuth angle and polar angle direction close to 0 is absorbed by the first polarizing plate 2000.

  That is, when a driving voltage is not applied to the liquid crystal layer 160, a wide viewing angle is obtained, and when a driving voltage is applied to the liquid crystal layer, the image light becomes dark in a predetermined azimuth angle and polar angle direction. In the present embodiment, it is possible to realize a display device in which the brightness of an image can be switched by viewing from a predetermined polar angle direction at an azimuth angle corresponding to the right direction of the screen by the viewing angle control element 36.

  Next, the light transmitted through the first polarizing plate 2000 passes through the liquid crystal layer 170 constituting the viewing angle control element 37 and enters the polarizing plate 2400. When no driving voltage is applied to the liquid crystal layer 170 of the viewing angle control element 37, the polarization plane of most of the light that passes through the first polarizing plate 2000 and passes through the liquid crystal layer 170 is rotated by 90 °. Since 2400 is transmitted, the transmittance is high over a wide viewing angle range.

  On the other hand, when a driving voltage is applied to the liquid crystal layer 170 of the viewing angle control element 37, the effective phase difference of the liquid crystal layer 170 is 0 in the light passing through the first polarizing plate 2000 and passing through the liquid crystal layer 170, or Light traveling in a predetermined azimuth angle and polar angle direction close to 0 is absorbed by the polarizing plate 2400.

  That is, when a driving voltage is not applied to the liquid crystal layer 170, a wide viewing angle is obtained, and when a driving voltage is applied to the liquid crystal layer 170, the image light becomes dark in a predetermined azimuth angle and polar angle direction. In this embodiment, it is possible to realize a display device in which the brightness of an image can be switched by observing from a predetermined polar angle direction at an azimuth angle corresponding to the left direction of the screen by the viewing angle control element 37.

  As described above, the display device of the present embodiment can realize a display device that can switch the brightness of an image when observed from a predetermined polar angle direction at an azimuth angle corresponding to the right direction or the left direction of the screen or the right direction and the left direction. .

  That is, when only the viewing angle control element 36 is driven, it is possible to realize a display device that can switch the brightness of a video in a predetermined polar angle direction only at an azimuth angle corresponding to the right direction of the screen. Further, when only the viewing angle control element 37 is driven, it is possible to realize a display device capable of switching the brightness of a video in a predetermined polar angle direction only at an azimuth angle corresponding to the left direction of the screen. Furthermore, when the viewing angle control element 36 and the viewing angle control element 37 are driven at the same time, it is possible to realize a display device that can switch the brightness of a video in a predetermined polar angle direction at azimuth angles corresponding to the right direction and left direction of the screen.

  As described above, in the display device according to the present embodiment, when the image is observed obliquely in the left-right direction of the screen, the brightness of the image can be reduced to deteriorate the visibility. Such viewing angle characteristics are effective in preventing a peep from the side when applied to display devices of portable devices such as mobile phones, notebook PCs, and PDAs, and public devices such as ATMs.

  In particular, in the display device of the present embodiment, the brightness of the image in the predetermined polar angle direction can be controlled independently in the left direction and the right direction of the screen. For this reason, for example, it is possible to improve the visibility by making the screen brighter for the person on the left side of his / her own, but not to peep from the right direction. .

  In the display device of this embodiment, the polarizing plate constituting the viewing angle control element and the polarizing plate constituting the liquid crystal display panel are also used as one polarizing plate. In this case, the light that is effectively used in the viewing angle control element and the light that is effectively used in the liquid crystal display panel are the same linearly polarized light, and the number of polarizing layers that cause the loss of light is reduced. Display device can be realized. Alternatively, a display device with lower power can be realized if the display has the same brightness.

  In the display device of this embodiment, the viewing angle control element 36 and the viewing angle control element 37 are arranged on the front side of the liquid crystal display panel 10. In this case, when a transflective display panel is applied as the liquid crystal display panel 10, a display device capable of switching the viewing angle not only in the transmissive display mode but also in the reflective display mode can be realized.

  Next, another embodiment of the display device of the present invention will be described with reference to the drawings. FIG. 39 is a partial sectional view showing a schematic configuration of one embodiment of the display device of the present invention.

  In this display device, the reflective polarizing plate 3200 is newly arranged between the transparent substrate 53 constituting the viewing angle control element 37 and the first polarizing plate 2000 in the display device described in the tenth embodiment. The members having the same functions as those in the above embodiment are given the same reference numerals, and detailed description thereof is omitted.

  As the reflective polarizing plate, one that can separate linearly polarized light components orthogonal to each other by reflection and transmission is used.

  As such a reflective polarizing plate, for example, a birefringence reflective polarizing film in which a plurality of polymer films having different birefringence disclosed in Patent Document 4 are laminated, or a phase difference between the front and back of a cholesteric liquid crystal film. A polarizing filter using a film, a dielectric multilayer film in which dielectrics having different refractive indexes are laminated, or a metal wire grid can be used.

  In the case of a birefringent reflective polarizing film, a predetermined linearly polarized light component of light incident on the birefringent reflective film is transmitted, and a linearly polarized light component whose polarization axis is orthogonal to this is reflected from 3M (USA) as a product name DBEF. It can be used as a reflective polarizing plate.

  A polarizing filter using a metal wire grid forms a conductive metal linear pattern of silver, aluminum, chrome, etc. on a transparent substrate at a pitch of a few hundred angstroms. The reflective polarizing plate can be realized.

  Here, the reflective polarizing plate 3200 adheres to the transparent substrate 53 constituting the viewing angle control element 37 with an adhesive, but the present invention does not limit the transparent substrate that adheres the polarizing plate.

  FIG. 40 shows the absorption axis of the polarizing plate, the reflection axis of the reflective polarizing plate, the alignment axis of the liquid crystal layer of the liquid crystal display panel, the alignment axis of the liquid crystal layer of the polarization state switching means, etc. It is a figure for demonstrating the relationship of an optical axis.

  As shown in FIG. 40, in the display device of this embodiment, the absorption axis of the polarizing plate and the alignment axis of the liquid crystal layer of the liquid crystal display panel 10, the viewing angle control element 36, and the viewing angle control element 37 will be described with reference to FIG. The same as the above-described embodiment. The reflection axis of the reflective polarizing plate 3200 is 45 °.

  In this case as well, as in the above-described embodiment, a display device that can switch the brightness of an image when observed from a predetermined polar angle direction at an azimuth angle corresponding to the right direction or the left direction of the screen or the right direction and the left direction can be realized.

  That is, when only the viewing angle control element 36 is driven, it is possible to realize a display device that can switch the brightness of a video in a predetermined polar angle direction only at an azimuth angle corresponding to the right direction of the screen. Further, when only the viewing angle control element 37 is driven, it is possible to realize a display device capable of switching the brightness of a video in a predetermined polar angle direction only at an azimuth angle corresponding to the left direction of the screen. Furthermore, when the viewing angle control element 36 and the viewing angle control element 37 are driven at the same time, it is possible to realize a display device that can switch the brightness of a video in a predetermined polar angle direction at azimuth angles corresponding to the right direction and left direction of the screen.

  In particular, in the display device of this embodiment, when a voltage of 3 V or higher, more preferably 5 V or higher is applied to the liquid crystal layer 170 of the viewing angle control element 37, external light is reflected by the reflective polarizing plate 3200 and looks like a mirror. Can be realized.

  That is, it is possible to realize a display device capable of switching between a state in which a wide viewing angle is realized, a state in which the screen is darkened in a predetermined azimuth angle and polar angle direction, and visibility is deteriorated, and a state like a mirror. it can.

  When the screen is in a mirror-like state, it is desirable that the lighting device 20 is turned off and no image is displayed on the liquid crystal display panel 10. This is to reduce the power consumption of the display device by preventing the illumination device 20 and the liquid crystal display panel 10 from consuming unnecessary power when the screen is in a mirror-like state.

  Note that the first polarizing plate 2000 can be omitted in the display device of this embodiment. In this case, since the number of polarizing layers causing light loss is reduced, a brighter display device can be realized. Alternatively, a display device with lower power can be realized if the display has the same brightness.

  However, at present, the reflective polarizing plate 3200 generally has a low degree of polarization. Therefore, when the first polarizing plate 2000 is omitted, the minimum transmittance achieved in the predetermined azimuth angle and polar angle direction in which the brightness is controlled by the viewing angle control element 36 is the first polarizing plate 2000. There is a concern that it will be higher than the case of preparation.

  Therefore, the necessity of the first polarizing plate 2000 may be selected according to the required characteristics.

  Next, another embodiment of the display device of the present invention will be described with reference to the drawings. FIG. 41 is a partial cross-sectional view showing a schematic configuration of an embodiment of the display device of the present invention.

  This display device changes the positional relationship between the viewing angle control elements 36 and 37 and the liquid crystal display panel 10 in the display device described in (Embodiment 10), and is the same as a member that performs the same function as the above embodiment. Reference numerals are assigned and detailed description is omitted.

  In this display device, a viewing angle control element 37, a viewing angle control element 36, and a liquid crystal display panel 10 are arranged in this order from the illumination device 20 side.

  A polarizing plate 2400 is disposed on the back side of the viewing angle control element 37, and the second polarizing plate 2100 constituting the viewing angle control element 36 is also used as a polarizing plate on the front side of the viewing angle control element 37. Further, the first polarizing plate 2000 constituting the viewing angle control element 36 is also used as a polarizing plate disposed on the back side of the liquid crystal display panel 10, and a third polarizing plate 2300 is disposed on the front side of the liquid crystal display panel 10. To do.

  Here, the first polarizing plate 2000 is adhered to the transparent substrate 12 constituting the liquid crystal display panel 10 by an adhesive, and the second polarizing plate 2100 is adhered to the transparent substrate 51 constituting the viewing angle control element 36 by an adhesive. To do. The third polarizing plate 2300 adheres to the transparent substrate 11 constituting the liquid crystal display panel 10 with an adhesive, and the polarizing plate 2400 adheres to the transparent substrate 53 constituting the viewing angle control element 37 with an adhesive. Does not limit the transparent substrate that adheres the polarizing plate.

  FIG. 42 is a diagram for explaining the relationship among the optical axes such as the absorption axis of the polarizing plate, the alignment axis of the liquid crystal layer of the liquid crystal display panel, and the alignment axis of the liquid crystal layer of the viewing angle control element according to the display device of this embodiment. FIG.

  As shown in FIG. 42, in the display device of this example, the absorption axis 2400A of the polarizing layer of the polarizing plate 2400 is 45 °, and the alignment axis 170LA on the polarizing plate 2400 side of the liquid crystal layer 170 of the viewing angle control element 37 is 225 °. The orientation axis 170OA on the second polarizing plate 2100 side is 315 °. The absorption axis 2100A of the polarizing layer of the second polarizing plate 2100 is 135 °, the alignment axis 160LA on the second polarizing plate 2100 side of the liquid crystal layer 160 of the viewing angle control element 36 is 45 °, and the first polarization The orientation axis 160OA on the plate 2000 side is set to 135 °. The absorption axis 2000A of the polarizing layer of the first polarizing plate 2000 is 45 °, the alignment axis 16LA on the first polarizing plate 2000 side of the liquid crystal layer 16 of the liquid crystal display panel 10 is 315 °, and the liquid crystal display panel 10 The alignment axis 16OA on the third polarizing plate 2300 side of the liquid crystal layer 16 is 45 °, and the absorption axis 2300A of the polarizing layer of the third polarizing plate 2300 is 135 °.

  In this case, light emitted from the illumination device 20 and transmitted through the polarizing plate 2400 constituting the viewing angle control element 37 passes through the liquid crystal layer 170 and enters the second polarizing plate 2100. When a driving voltage is not applied to the liquid crystal layer 170 of the viewing angle control element 37, the polarization plane of most of the light that passes through the polarizing plate 2400 and passes through the liquid crystal layer 170 is rotated by 90 °. Since 2100 is transmitted, the transmittance is high over a wide viewing angle range.

  On the other hand, when a driving voltage is applied to the liquid crystal layer 170 of the viewing angle control element 37, the effective phase difference of the liquid crystal layer 170 is 0 or close to 0 among the light that passes through the polarizing plate 2400 and passes through the liquid crystal layer 170. The light traveling in the predetermined azimuth angle and polar angle direction is absorbed by the second polarizing plate 2100.

  That is, when no driving voltage is applied to the liquid crystal layer 170, bright illumination light is obtained in a wide viewing angle range, and when a driving voltage is applied to the liquid crystal layer 170, the illumination device 20 emits light in a predetermined azimuth angle and polar angle direction. The illumination light becomes dark. In this embodiment, the viewing angle control element 37 can switch the brightness of illumination light that is an azimuth angle corresponding to the left direction of the screen and that is directed to a predetermined polar angle direction.

  Next, the light transmitted through the second polarizing plate 2100 passes through the liquid crystal layer 160 constituting the viewing angle control element 36 and enters the first polarizing plate 2000.

  When no driving voltage is applied to the liquid crystal layer 160 of the viewing angle control element 36, most of the light that passes through the second polarizing plate 2100 and passes through the liquid crystal layer 160 has a plane of polarization rotated by 90 °. Therefore, the transmittance is high over a wide viewing angle range.

  On the other hand, when a driving voltage is applied to the liquid crystal layer 160 of the viewing angle control element 36, the effective phase difference of the liquid crystal layer 160 of the light passing through the second polarizing plate 2100 and passing through the liquid crystal layer 160 is 0, or Light traveling in a predetermined azimuth angle and polar angle direction close to 0 is absorbed by the first polarizing plate 2000.

  That is, when no driving voltage is applied to the liquid crystal layer 160, bright illumination light is obtained in a wide viewing angle range, and when the driving voltage is applied to the liquid crystal layer 160, the illumination device 20 emits light in a predetermined azimuth angle and polar angle direction. The illumination light becomes dark. In this embodiment, the viewing angle control element 36 can switch the brightness of illumination light having an azimuth angle corresponding to the right direction of the screen and directed in a predetermined polar angle direction.

  The light transmitted through the first polarizing plate 2000 passes through the liquid crystal layer 16 constituting the liquid crystal display panel 10 and enters the third polarizing plate 2300. At this time, the polarization state of light passing through the liquid crystal layer 16 is controlled by applying a voltage corresponding to the video information transmitted from the video information generation unit (not shown) to the liquid crystal layer 16, and the third polarizing plate 2300 is Desired video light can be formed by adjusting the amount of transmitted light.

  Therefore, when only the viewing angle control element 36 is driven, it is possible to realize a display device that can switch the brightness of a video in a predetermined polar angle direction only at an azimuth angle corresponding to the right direction of the screen. Further, when only the viewing angle control element 37 is driven, it is possible to realize a display device capable of switching the brightness of a video in a predetermined polar angle direction only at an azimuth angle corresponding to the left direction of the screen. Furthermore, when the viewing angle control element 36 and the viewing angle control element 37 are driven at the same time, it is possible to realize a display device that can switch the brightness of a video in a predetermined polar angle direction at azimuth angles corresponding to the right direction and left direction of the screen.

  As described above, in the display device according to the present embodiment, when the image is observed obliquely in the left-right direction of the screen, the brightness of the image can be reduced to deteriorate the visibility. Such viewing angle characteristics are effective in preventing a peep from the side when applied to display devices of portable devices such as mobile phones, notebook PCs, and PDAs, and public devices such as ATMs.

  In particular, in the display device of the present embodiment, the brightness of the image in the predetermined polar angle direction can be controlled independently in the left direction and the right direction of the screen. For this reason, for example, it is possible to improve the visibility by making the screen brighter for the person on the left side of his / her own, but not to peep from the right direction. .

  In the display device of this embodiment, the polarizing plate constituting the viewing angle control element and the polarizing plate constituting the liquid crystal display panel are also used as one polarizing plate. In this case, the light that is effectively used in the viewing angle control element and the light that is effectively used in the liquid crystal display panel are the same linearly polarized light, and the number of polarizing layers that cause the loss of light is reduced. Display device can be realized. Alternatively, a display device with lower power can be realized if the display has the same brightness.

  In the display device of this embodiment, the viewing angle control element 36 and the viewing angle control element 37 are disposed on the back side of the liquid crystal display panel 10. In this case, when a transflective display panel is applied as the liquid crystal display panel 10, a brighter display can be obtained in the reflective display mode because there is no member that loses light on the surface side of the liquid crystal display panel. . Further, by disposing the liquid crystal display panel 10 on the outermost surface of the display device, it is possible to realize a display device with a smaller depth at a position where an image is displayed.

  Next, another embodiment of the display device of the present invention will be described with reference to the drawings. FIG. 43 is a partial cross-sectional view showing a schematic configuration of an embodiment of the display device of the present invention.

  This display device changes the positional relationship between the viewing angle control elements 36 and 37 and the liquid crystal display panel 10 in the display device described in (Embodiment 10), and is the same as a member that performs the same function as the above embodiment. Reference numerals are assigned and detailed description is omitted.

  In this display device, a viewing angle control element 37, a liquid crystal display panel 10, and a viewing angle control element 36 are arranged in this order from the illumination device 20 side.

  A polarizing plate 2400 is disposed on the back side of the viewing angle control element 37, and the third polarizing plate 2300 constituting the liquid crystal display panel 10 is also used as a polarizing plate on the front side of the viewing angle control element 37. The second polarizing plate 2100 constituting the viewing angle control element 36 is also used as a polarizing plate disposed on the surface side of the liquid crystal display panel 10, and the first polarizing plate 2000 is provided on the surface side of the viewing angle control element 36. Deploy.

  Here, the first polarizing plate 2000 is adhered to the transparent substrate 50 constituting the viewing angle control element 36 by an adhesive, and the second polarizing plate 2100 is adhered to the transparent substrate 11 constituting the liquid crystal display panel 10 by an adhesive. To do. The third polarizing plate 2300 adheres to the transparent substrate 12 constituting the liquid crystal display panel 10 with an adhesive, and the polarizing plate 2400 adheres to the transparent substrate 53 constituting the viewing angle control element 37 with an adhesive. Does not limit the transparent substrate that adheres the polarizing plate.

  FIG. 44 is a diagram for explaining the relationship between optical axes such as the absorption axis of the polarizing plate, the alignment axis of the liquid crystal layer of the liquid crystal display panel, and the alignment axis of the liquid crystal layer of the viewing angle control element according to the display device of this embodiment. FIG.

  As shown in FIG. 44, in the display device of this example, the absorption axis 2400A of the polarizing layer of the polarizing plate 2400 is 135 °, and the alignment axis 170LA on the polarizing plate 2400 side of the liquid crystal layer 170 of the viewing angle control element 37 is 225 °. The alignment axis 170OA on the third polarizing plate 2300 side is 315 °. The absorption axis 2300A of the polarizing layer of the third polarizing plate 2300 is 45 °, the alignment axis 16LA on the third polarizing plate 2300 side of the liquid crystal layer 16 of the liquid crystal display panel 10 is 315 °, and the liquid crystal display panel 10 The alignment axis 16OA of the liquid crystal layer 16 on the second polarizing plate 2100 side is 45 °. The alignment axis 160LA on the second polarizing plate 2100 side of the liquid crystal layer 160 of the viewing angle control element 36 is 45 °, and the alignment axis 160OA on the first polarizing plate 2000 side is 135 °. The absorption axis 2000A of the polarizing layer of the first polarizing plate 2000 is 45 °.

  In this case, light emitted from the illumination device 20 and transmitted through the polarizing plate 2400 constituting the viewing angle control element 37 passes through the liquid crystal layer 170 and enters the second polarizing plate 2100. When no driving voltage is applied to the liquid crystal layer 170 of the viewing angle control element 37, the polarization plane of most of the light transmitted through the polarizing plate 2400 and passing through the liquid crystal layer 170 is rotated by 90 °, and the third polarizing plate Since 2300 is transmitted, the transmittance is high over a wide viewing angle range.

  On the other hand, when a driving voltage is applied to the liquid crystal layer 170 of the viewing angle control element 37, the effective phase difference of the liquid crystal layer 170 is 0 or close to 0 among the light that passes through the polarizing plate 2400 and passes through the liquid crystal layer 170. The light traveling in the predetermined azimuth angle and polar angle direction is absorbed by the third polarizing plate 2300.

  That is, when no driving voltage is applied to the liquid crystal layer 170, bright illumination light is obtained in a wide viewing angle range, and when a driving voltage is applied to the liquid crystal layer 170, the illumination device 20 emits light in a predetermined azimuth angle and polar angle direction. The illumination light becomes dark. In this embodiment, the viewing angle control element 37 can switch the brightness of illumination light that is an azimuth angle corresponding to the left direction of the screen and that is directed to a predetermined polar angle direction.

  The light transmitted through the third polarizing plate 2300 passes through the liquid crystal layer 16 constituting the liquid crystal display panel 10 and enters the second polarizing plate 2100. At this time, the polarization state of light passing through the liquid crystal layer 16 is controlled by applying a voltage corresponding to the video information transmitted from the video information generating unit (not shown) to the liquid crystal layer 16, and the second polarizing plate 2100 is Desired video light can be formed by adjusting the amount of transmitted light.

  Next, the light transmitted through the second polarizing plate 2100 passes through the liquid crystal layer 160 constituting the viewing angle control element 36 and enters the first polarizing plate 2000.

  When no driving voltage is applied to the liquid crystal layer 160 of the viewing angle control element 36, most of the light that passes through the second polarizing plate 2100 and passes through the liquid crystal layer 160 has a plane of polarization rotated by 90 °. Therefore, the transmittance is high over a wide viewing angle range.

  On the other hand, when a driving voltage is applied to the liquid crystal layer 160 of the viewing angle control element 36, the effective phase difference of the liquid crystal layer 160 of the light passing through the second polarizing plate 2100 and passing through the liquid crystal layer 160 is 0, or Light traveling in a predetermined azimuth angle and polar angle direction close to 0 is absorbed by the first polarizing plate 2000.

  That is, when a driving voltage is not applied to the liquid crystal layer 160, a bright image is obtained in a wide viewing angle range, and when a driving voltage is applied to the liquid crystal layer 160, the image becomes dark in a predetermined azimuth angle and polar angle direction. In this embodiment, the viewing angle control element 36 can switch the brightness of the image in the predetermined polar angle direction, which is an azimuth angle corresponding to the right direction of the screen.

  Therefore, when only the viewing angle control element 36 is driven, it is possible to realize a display device that can switch the brightness of a video in a predetermined polar angle direction only at an azimuth angle corresponding to the right direction of the screen. Further, when only the viewing angle control element 37 is driven, it is possible to realize a display device capable of switching the brightness of a video in a predetermined polar angle direction only at an azimuth angle corresponding to the left direction of the screen. Furthermore, when the viewing angle control element 36 and the viewing angle control element 37 are driven at the same time, it is possible to realize a display device that can switch the brightness of a video in a predetermined polar angle direction at azimuth angles corresponding to the right direction and left direction of the screen.

  As described above, in the display device according to the present embodiment, when the image is observed obliquely in the left-right direction of the screen, the brightness of the image can be reduced to deteriorate the visibility. Such viewing angle characteristics are effective in preventing a peep from the side when applied to display devices of portable devices such as mobile phones, notebook PCs, and PDAs, and public devices such as ATMs.

  Also in the display device of the present embodiment, the brightness of the image in the predetermined polar angle direction can be controlled independently in the left direction and the right direction of the screen. For this reason, for example, it is possible to improve the visibility by making the screen brighter for the person on the left side of his / her own, but not to peep from the right direction. .

  In the display device of this embodiment, the polarizing plate constituting the viewing angle control element and the polarizing plate constituting the liquid crystal display panel are also used as one polarizing plate. In this case, the light that is effectively used in the viewing angle control element and the light that is effectively used in the liquid crystal display panel are the same linearly polarized light, and the number of polarizing layers that cause the loss of light is reduced. Display device can be realized. Alternatively, a display device with lower power can be realized if the display has the same brightness.

  In the above examples, the case where a polarizing plate having a polarizing layer composed of polyvinyl alcohol as a base material is sandwiched between protective films is described. However, by using a coating type polarizing layer, the protective film is omitted. May be.

  Moreover, you may make it perform the antireflection process by an antireflection film in the interface which contacts air in each member.

  In the display device of the present invention, a reflective polarizing plate may be disposed on the outermost surface. At this time, the reflection axis of the reflective polarizing plate is arranged so as to be parallel to the absorption axis of the polarizing layer of the polarizing plate arranged closest to the surface among the polarizing plates constituting the display device.

  In this case, when the lighting device is turned on and the liquid crystal display panel is driven, an image can be seen through the reflective polarizing plate. On the other hand, when the illumination device is turned off, the external light is reflected by the reflective polarizing plate, so that the screen looks like a mirror.

  In addition, when image light emitted in an oblique direction is restricted by a viewing angle limiting element or a viewing angle control element, the visibility of the image becomes worse due to reflection of external light by the reflective polarizing plate, and high peeping is required. Preventive effect can be obtained.

  The viewing angle limiting element and the viewing angle control element of the present invention can suppress or control the transmission of light in a predetermined azimuth angle and polar angle direction. For this reason, when applied to an on-vehicle display device, an effect of preventing the reflection of image light on the front window can be obtained. Moreover, if it uses for the display apparatus of ATM or a public terminal, the peep prevention effect by persons other than a user will be acquired.

  In addition, since the display device to which the viewing angle limiting element or the viewing angle control element of the present invention is applied has an effect of preventing peeping, portable devices such as mobile phones, PDAs, notebook PCs and the like that are expected to be used in crowds. It is also suitable as a display device for equipment.

  DESCRIPTION OF SYMBOLS 1 Display apparatus, 10 Liquid crystal display panel, 11, 12, 50, 51 Transparent substrate, 13, 16, 100, 150, 160, 170 Liquid crystal layer, 20 Illumination device, 30, 31 Viewing angle limiting element, 70 Phase difference plate, 200 base film, 210, 220 protective film, 300 polarizing layer, 400 adhesive layer, 500 alignment film, 1000, 1100 liquid crystal film, 1200, 1300 polarization state switching means, 2000 first polarizing plate, 2100 second polarizing plate 2200, 2300 Third polarizing plate, 2400 polarizing plate.

Claims (3)

A first polarizing layer; a second polarizing layer; and a liquid crystal layer disposed between the first polarizing layer and the second polarizing layer, the first polarizing layer and the second polarizing layer. And the liquid crystal layer is a hybrid-aligned nematic liquid crystal, and the alignment axis of the liquid crystal layer is the same as that of the first polarizing layer and the second polarizing layer. An optical element comprising a retardation plate having an optically negative uniaxial medium on a side that is parallel or orthogonal to an absorption axis and on which the liquid crystal molecules of the liquid crystal layer are aligned in a vertical or nearly vertical state ,
An illumination device for irradiating light toward the optical element;
A third polarizing layer and a liquid crystal layer disposed between the first polarizing layer or the second polarizing layer and the third polarizing layer, and adjusting the amount of light emitted from the illumination device; And a liquid crystal display panel for displaying an image. A first transparent substrate; a second transparent substrate disposed opposite to the first transparent substrate; a liquid crystal layer disposed between the first transparent substrate and the second transparent substrate; A first transparent electrode and a first alignment film disposed between a liquid crystal layer and the first transparent substrate; a second transparent electrode and a second disposed between the liquid crystal layer and the second transparent substrate; An alignment film, a retardation plate composed of an optically negative uniaxial anisotropic medium disposed on the first transparent substrate side as viewed from the liquid crystal layer, and the liquid crystal layer side as viewed from the retardation plate A first polarizing layer disposed on the opposite side of the liquid crystal layer, and a second polarizing layer disposed on the second transparent substrate side when viewed from the liquid crystal layer,
The liquid crystal molecules of the liquid crystal layer are aligned in a state perpendicular or nearly perpendicular to the substrate surface on the first transparent substrate side, and in a state parallel to or nearly parallel to the substrate surface on the second transparent substrate side. It consists of nematic liquid crystal with positive dielectric anisotropy,
The absorption axes of the first polarizing layer and the second polarizing layer are parallel to each other,
An optical element, wherein an alignment axis of the second alignment film is parallel or orthogonal to absorption axes of the first polarizing layer and the second polarizing layer. A first transparent substrate; a second transparent substrate disposed opposite to the first transparent substrate; a liquid crystal layer disposed between the first transparent substrate and the second transparent substrate; A first transparent electrode and a first alignment film disposed between a liquid crystal layer and the first transparent substrate; a second transparent electrode and a second disposed between the liquid crystal layer and the second transparent substrate; An alignment film, a retardation plate composed of an optically negative uniaxial anisotropic medium disposed on the first transparent substrate side as viewed from the liquid crystal layer, and the liquid crystal layer side as viewed from the retardation plate A first polarizing layer disposed on the opposite side of the liquid crystal layer, and a second polarizing layer disposed on the second transparent substrate side when viewed from the liquid crystal layer,
The liquid crystal molecules of the liquid crystal layer are aligned in a state perpendicular or nearly perpendicular to the substrate surface on the first transparent substrate side, and in a state parallel to or nearly parallel to the substrate surface on the second transparent substrate side. The aligned dielectric anisotropy is composed of a nematic liquid crystal, the absorption axes of the first polarizing layer and the second polarizing layer are parallel to each other, and the alignment axis of the second alignment film is An optical element parallel or orthogonal to the absorption axes of the first polarizing layer and the second polarizing layer;
An illumination device for irradiating light toward the optical element;
A third polarizing layer and a liquid crystal layer disposed between the first polarizing layer or the second polarizing layer and the third polarizing layer, and adjusting the amount of light emitted from the illumination device to adjust the image And a liquid crystal display panel for displaying the display.

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