WO2012081567A1 - Liquid crystal display device - Google Patents

Abstract

Disclosed is a liquid crystal display device which comprises: a light guide plate that has a light incident surface on an end face; a light source for having light incident on the light incident surface of the light guide plate; a light diffusion plate that is arranged so as to face the light guide plate; a liquid crystal layer that is arranged between the light guide plate and the light diffusion plate; and a pair of electrodes that controls the amount of light, which propagates obliquely within the liquid crystal layer and is diffused and emitted by the light diffusion plate, by producing an electric field inside the liquid crystal layer and changing the refractive index or the magnitude of the birefringence of light that has propagated within the light guide plate and obliquely entered into the liquid crystal layer from the light guide plate.

Description

Liquid crystal device

The present invention relates to a liquid crystal device.
This application claims priority based on Japanese Patent Application No. 2010-279737 filed in Japan on December 15, 2010, the contents of which are incorporated herein by reference.

A liquid crystal device described in Patent Document 1 is known as an edge light type liquid crystal device in which a light source is disposed on an end face of a light guide plate and light emitted from the light source is spread over the entire light guide plate to form a surface light source. The liquid crystal device of Patent Document 1 includes a plurality of light guide plates separated from each other and a plurality of light sources that make light incident on the light guide plates, and partially drives the light sources for each light guide plate.

JP 2010-20961 A

Since the liquid crystal device of Patent Document 1 is a method of spreading light from the end face of the light guide plate to the entire surface of the light guide plate, light cannot be emitted only from a specific region of the light guide plate. Therefore, area active drive that controls the amount of emitted light according to the brightness of the image cannot be performed.

An object of the present invention is to provide an edge light type liquid crystal device capable of emitting light only from a specific region of a light guide plate.

(1) A liquid crystal device according to an aspect of the present invention includes a light guide plate having a light incident surface on an end surface, a light source that causes light to enter the light incident surface of the light guide plate, and a light diffusing plate disposed to face the light guide plate. And a liquid crystal layer disposed between the light guide plate and the light diffusing plate, and an electric field is generated inside the liquid crystal layer to propagate through the light guide plate and from the light guide plate to the liquid crystal layer. A pair for controlling the light quantity of the light emitted obliquely and then diffused by the light diffusion plate through the inside of the liquid crystal layer by changing the refractive index or the birefringence of the light incident obliquely. Electrode.

(2) In the liquid crystal device according to an aspect of the present invention, an optical layer that reflects the first polarized light and transmits the second polarized light different from the first polarized light is interposed between the liquid crystal layer and the light diffusion plate. The pair of electrodes are propagated through the inside of the light guide plate and change the birefringence of the liquid crystal layer of the first polarized light that is obliquely incident on the liquid crystal layer from the light guide plate. The polarization state of the first polarized light traveling obliquely in the liquid crystal layer may be changed.

(3) In the liquid crystal device according to an aspect of the present invention, a polarizing layer that transmits the first polarized light may be provided on an optical path of the light between the light guide plate and the light source.

(4) In the liquid crystal device according to an aspect of the present invention, the liquid crystal layer propagates through the light guide plate and totally reflects the second polarized light incident on the liquid crystal layer obliquely from the light guide plate. Polarized light that is reflected by the liquid crystal layer on the end surface different from the light incident surface of the light guide plate, and converts the second polarized light that has propagated through the light guide plate into the first polarized light and reflects the light into the light guide plate. A conversion layer may be provided.

(5) In the liquid crystal device according to an aspect of the present invention, a polarizing layer that transmits the second polarized light transmitted through the optical layer may be provided between the light diffusion plate and the optical layer.

(6) In the liquid crystal device according to an aspect of the present invention, the pair of electrodes propagates through the light guide plate and is refracted from the liquid crystal layer of the first polarization that is obliquely incident on the liquid crystal layer from the light guide plate. By changing the rate, the first polarized light is transmitted through the liquid crystal layer and emitted from the light diffusing plate, and the first polarized light is totally reflected by the liquid crystal layer and propagates inside the light guide plate. You may switch from the state which does not radiate | emit from the said light diffusing plate.

(7) In the liquid crystal device according to one aspect of the present invention, the liquid crystal layer propagates through the light guide plate and is incident obliquely on the liquid crystal layer, and totally reflects the second polarized light different from the first polarized light. Then, the second polarized light that is totally reflected by the liquid crystal layer and propagates through the inside of the light guide plate is converted into the first polarized light on the end surface different from the light incident surface of the light guide plate, and is converted into the first light guide plate. A reflective polarization conversion layer may be provided.

(8) In the liquid crystal device according to one embodiment of the present invention, the light source includes a plurality of light emitting elements that emit light of different colors, and the plurality of light emitting elements sequentially emit light at different timings. The electrode may generate an electric field in the liquid crystal layer in accordance with a gradation of an image of a color emitted from the light emitting element in accordance with a timing at which the plurality of light emitting elements emit light.

(9) In the liquid crystal device according to one embodiment of the present invention, the pair of electrodes may generate an electric field in a layer thickness direction of the liquid crystal layer.

(10) In the liquid crystal device according to one embodiment of the present invention, the liquid crystal layer may exhibit an isotropic phase in a state where no electric field is applied to the liquid crystal layer without generating an electric field.

(11) In the liquid crystal device according to an aspect of the present invention, the liquid crystal layer includes a direction in which the light is incident on a light incident surface of the light guide plate, and a normal direction of a surface of the light guide plate facing the light diffusion plate. The orientation state may change in a plane including

According to the present invention, it is possible to provide an edge light type liquid crystal device capable of emitting light only from a specific region of the light guide plate.

It is a disassembled perspective view of the liquid crystal display device of 1st Embodiment. It is sectional drawing parallel to YZ plane of a backlight unit. It is a top view of the light guide seen from the Z direction. It is sectional drawing perpendicular | vertical to the light-projection surface of a light source. It is a block diagram which shows the electric constitution of a liquid crystal display device. It is a top view of a plurality of sub illumination fields seen from the Z direction. It is a figure which shows an example of the control method of a light source and a switching area | region. It is a figure which shows the electric field non-application state which does not generate | occur | produce an electric field inside a liquid crystal layer. It is a figure which shows the electric field application state which generated the electric field inside the liquid crystal layer. It is a 1st modification of the backlight unit of 1st Embodiment. It is a 2nd modification of the backlight unit of 1st Embodiment. It is a disassembled perspective view of the liquid crystal display device of 2nd Embodiment. It is sectional drawing parallel to YZ plane of a backlight unit. It is a figure which shows the electric field non-application state which does not generate | occur | produce an electric field inside a liquid crystal layer in the 1st modification of the backlight unit of 2nd Embodiment. It is a figure which shows the electric field application state which generated the electric field inside the liquid crystal layer in the 1st modification of the backlight unit of 2nd Embodiment. It is a disassembled perspective view of the liquid crystal display device of 3rd Embodiment. It is sectional drawing parallel to YZ plane of a liquid crystal display device. It is a disassembled perspective view of the liquid crystal display device of 4th Embodiment. It is sectional drawing parallel to YZ plane of a liquid crystal display device. It is sectional drawing parallel to YZ plane of the liquid crystal display device of 5th Embodiment. It is sectional drawing perpendicular | vertical to the light-projection surface of a light source. It is sectional drawing parallel to YZ plane of the liquid crystal display device of 6th Embodiment. It is a disassembled perspective view of the liquid crystal light control apparatus of 7th Embodiment. It is sectional drawing parallel to YZ plane of the liquid crystal light control apparatus of 7th Embodiment.

FIG. 1 is an exploded perspective view of the liquid crystal display device 1 of the first embodiment. In the following description, the extending direction of the gate line 21 is the X direction, the extending direction of the data line 22 is the Y direction, and the direction perpendicular to the X direction and the Y direction is the Z direction. Will be explained.

The liquid crystal display device 1 includes a liquid crystal panel 2 and a backlight unit (liquid crystal device) 3.

The liquid crystal panel 2 includes a first substrate 10, a second substrate 11, a first polarizing plate 12, and a second polarizing plate 13. The second substrate 11 is disposed to face the first substrate 10. The first polarizing plate 12 is provided on the outer surface side of the first substrate 10. The second polarizing plate 13 is provided on the outer surface side of the second substrate 11.
A rectangular frame-shaped sealing material 19 is provided on the peripheral edge of the facing region where the first substrate 10 and the second substrate 11 face each other. In a space surrounded by the first substrate 10, the second substrate 11, and the sealing material 19, liquid crystal (not shown) is sealed.

The display area 2A is provided inside the sealing material 19. In the display area 2A, a plurality of gate lines 21 extending in the X direction and a plurality of data lines 22 extending in the Y direction are provided on the first substrate 10 in a lattice shape in plan view. A display element corresponding to any one of red, green, and blue is provided at the intersection between the gate line 21 and the data line 22. On the first substrate 10, a plurality of display elements are arranged in a matrix in the X direction and the Y direction, and a display region 2A is formed by the plurality of display elements.

A backlight unit 3 is provided on the back side of the liquid crystal panel 2. The backlight unit 3 includes a plurality of light sources 5 and a light guide 4. The light guide 4 spreads light incident from the plurality of light sources 5 in a planar shape and emits the light toward the liquid crystal panel 2.

The light guide 4 is a light guide panel including a first substrate 41 and a second substrate 42. The second substrate 42 is disposed to face the first substrate 41. The first substrate 41 is a light guide plate having a light incident surface on the end surface 41a. A rectangular frame-shaped sealing material 49 is provided at the peripheral edge of the facing region where the first substrate 41 and the second substrate 42 face each other. A liquid crystal layer is sealed in a space surrounded by the first substrate 41, the second substrate 42, and the sealing material 49.

A plurality of stripe-shaped switching areas 401, 402, 403, 404, and 405 that can be switched between a lighting state (ON state) and a non-lighting state (OFF state) are provided inside the sealing material 49. In the lighting state (ON state), light propagating inside the light guide 4 is emitted to the outside of the light guide 4. In the non-lighting state (OFF state), light propagating inside the light guide 4 is not emitted to the outside of the light guide 4.
The plurality of switching areas 401 to 405 are arranged adjacent to each other in the Y direction.

The light source 5 is, for example, a light emitting diode (LED) that emits white light. The light source 5 may be anything that can be used as a point light source, and may be an organic EL (ElectroLuminescence) element. A plurality of light sources 5 are arranged at positions facing the light incident surface 41 a of the first substrate 41. Although five light sources 5 are provided in FIG. 1, the number of light sources 5 is not limited to this. The plurality of light sources 5 are arranged in the X direction with the light emitting surface opposed to the light incident surface 41 a of the first substrate 41.

FIG. 2 is a cross-sectional view of the backlight unit 3 parallel to the YZ plane.

The light guide 4 includes a first substrate 41, a second substrate 42, a liquid crystal layer 45, an optical layer 46, a polarizing layer 47, and a light diffusion plate 48. The second substrate 42 is disposed to face the first substrate 41. The liquid crystal layer 45 is sandwiched between the first substrate 41 and the second substrate 42. The optical layer 46 is provided between the second substrate 42 and the liquid crystal layer 45. The polarizing layer 47 is provided on the outer surface side of the second substrate 42 (the side opposite to the liquid crystal layer 45). The light diffusion plate 48 is provided on the outer surface side of the polarizing layer 47.

The first substrate 41 and the second substrate 42 are transparent plate materials made of polystyrene or glass. An end surface of the first substrate 41 facing the light source 5 is a light incident surface 41 a on which light emitted from the light source 5 is incident. The light incident surface 41a is inclined with respect to the XY plane. The inclination angle of the light incident surface 41 a with respect to the XY plane is an angle at which light emitted from the light source 5 in a direction substantially orthogonal to the light incident surface 41 a is totally reflected inside the first substrate 41.

The light source 5 is preferably a directional light source. In order to satisfy the total reflection condition, it is preferable that the angle range of the light incident on the first substrate 41 is narrowed to about 5 degrees or less.

On the end face different from the light incident face 41a of the first substrate 41 (for example, the end face provided on the side opposite to the side on which the light incident face 41a is provided), the light propagates inside the first substrate 41. A reflection layer 61 is provided that reflects the light incident on the end face toward the inside of the first substrate 41.

The first substrate 41 is provided with a plurality of first electrodes 43. The first electrode 43 is made of a transparent conductive film such as ITO (Indium Tin Oxide). A second electrode 44 is provided on the second substrate 42 so as to face the plurality of first electrodes 43. The second electrode 44 is made of a transparent conductive film such as ITO.
The first electrode 43 is a striped electrode extending in the X direction. The second electrode 44 is a common electrode common to the plurality of first electrodes 43. A region in which the orientation of the liquid crystal layer 45 is controlled by the first electrode 43 and the second electrode 44 (a region where the first electrode 43 and the second electrode 44 face each other) is one switching region. In the light guide 4 of FIG. 2, five first electrodes 43 are provided in the Y direction. Accordingly, five switching areas 401 to 405 are provided in the Y direction.

A polarizing layer 60 that transmits the first polarized light Lp is provided on the light path between the light source 5 and the light incident surface 41a. The polarizing layer 60 is, for example, a polarizing plate having a transmission axis parallel to the intersecting line where the YZ plane and the light incident surface 41a intersect. The first polarized light Lp is light that enters the optical layer 46 as P-polarized light. The polarizing layer 60 is installed on the light incident surface 41a, and the light emitting surface of the light source 5 and the light incident surface 41a of the first substrate 41 face each other with the polarizing layer 60 interposed therebetween. Of the light emitted from the light source 5, the second polarized light Ls incident as S-polarized light on the interface between the second electrode 44 and the optical layer 46 is absorbed or reflected by the polarizing layer 60. Only the first polarized light Lp that enters the interface between the second electrode 44 and the optical layer 46 as P-polarized light enters the inside of the first substrate 41.

The liquid crystal layer 45 includes a liquid crystal having a positive dielectric anisotropy indicating a blue phase. The blue phase is a liquid crystal phase in which a plurality of spiral structures having different spiral axes are in a three-dimensional periodic structure. The blue phase itself is optically isotropic and rearranges into a nematic phase when a voltage is applied. The alignment of the liquid crystal layer 45 is controlled by an electric field generated between the first electrode 43 and the second electrode 44. The blue phase liquid crystal layer 45 exhibits a Kerr effect (Kerr effect). The refractive index of the liquid crystal layer 45 is proportional to the square of the electric field strength. The response time of the blue phase liquid crystal is about 10 microseconds, which is much shorter than the response time of normal nematic liquid crystal (10 milliseconds).

The refractive index of the liquid crystal layer 45 in the electric field application state in which an electric field in the Z direction is generated between the first electrode 43 and the second electrode 44, and no electric field is generated between the first electrode 43 and the second electrode 44. The refractive index of the liquid crystal layer 45 in the state where no electric field is applied is substantially equal to the refractive index of the first substrate 41, the second substrate 42, the first electrode 43, and the second electrode 44. Therefore, light incident from the light incident surface 41 a of the first substrate 41 passes through the first electrode 43, the liquid crystal layer 45, and the second electrode 44 and reaches the optical layer 46.

The optical layer 46 is an optical anisotropic body having a different refractive index depending on the polarization state of incident light. The optical layer 46 has a relatively small refractive index with respect to the first polarized light Lp and a relatively large refractive index with respect to the second polarized light Ls. The refractive index of the optical layer 46 with respect to the first polarized light Lp is smaller than the refractive index of the second electrode 44. Therefore, the first polarized light Lp incident on the optical layer 46 from the second electrode 44 is totally reflected on the surface of the optical layer 46. The refractive index of the optical layer 46 with respect to the second polarized light Ls is equal to or larger than the refractive index of the second electrode 44. Therefore, the second polarized light Ls incident on the optical layer 46 from the second electrode 44 passes through the optical layer 46 and enters the second substrate 42.

In an electric field non-application state, the liquid crystal disposed between the first electrode 43 and the second electrode 44 is in a special alignment state called a blue phase. Therefore, the liquid crystal layer 45 has an optical isotropic phase having no optical anisotropy. The first polarized light Lp incident on the liquid crystal layer 45 is incident on the optical layer 46 without changing the polarization state when no electric field is applied. Therefore, the first polarized light Lp is reflected on the surface of the optical layer 46 and propagates in the light guide 4 in the Y direction. In a region where no voltage is applied between the first electrode 43 and the second electrode 44, no light is emitted to the outside. Therefore, it becomes a non-lighting state (OFF state).

In the electric field application state, the liquid crystal disposed between the first electrode 43 and the second electrode 44 is generally aligned in the Z direction. Therefore, the liquid crystal layer 45 becomes an optically anisotropic phase having optical anisotropy. Since the liquid crystal layer 45 at the time of applying an electric field has birefringence, the first polarized light Lp incident on the liquid crystal layer 45 is elliptically polarized in the liquid crystal layer 45 or the second polarized light orthogonal to the first polarized light Lp. It is converted into Ls (linearly polarized light incident on the optical layer 46 as S-polarized light). Therefore, a part of the first polarized light Lp whose polarization state has been converted by the liquid crystal layer 45 passes through the optical layer 46 and enters the second substrate 42, and reaches the polarizing layer 47.

The polarizing layer 47 is a polarizing plate having a transmission axis parallel to the X direction. Therefore, the second polarized light Ls that has passed through the optical layer 46 passes through the polarizing layer 47, is diffused by the light diffusion plate 48, and is emitted to the outside.
The surface of the light diffusing plate 48 that faces the liquid crystal panel 2 (see FIG. 1) is a light emitting surface 4 a from which light propagated through the light guide 4 is emitted. In a region where a voltage is applied between the first electrode 43 and the second electrode 44, light is emitted to the outside. Therefore, it will be in a lighting state (ON state).

FIG. 2 shows a case where the switching regions 401 and 403 to 405 are in an isotropic phase state (when no electric field is applied: OFF), and the switching region 402 is in an anisotropic phase state (when an electric field is applied: ON). Therefore, the light propagated inside the light guide 4 is selectively emitted from the switching region 402.

FIG. 3 is a plan view of the light guide 4 viewed from the Z direction.

A plurality of light sources shown in FIG. 1 are installed on one end side of the light guide 4 in the Y direction along the end surface (light incident surface) of the first substrate 41. Light emitted from the light source propagates in the light guide 4 in the Y direction, so that a plurality of stripe-shaped light propagation regions 501, 502, 503, 504, and 505 that are long in the Y direction are formed.

The light guide 4 is provided with a plurality of first electrodes 43 and second electrodes 44. The first electrodes 43 are arranged in the Y direction. The second electrode 44 faces the plurality of first electrodes 43.
The first electrode 43 is a striped electrode extending in the X direction. A facing region where one first electrode 43 and second electrode 44 face each other is one switching region 401 to 405. Of one switching region, a region facing one propagation region 501 to 505 is one sub illumination region A. The switching areas 401 to 405 and the sub illumination area A are illumination areas obtained by dividing the light exit surface of the light guide 4. In the light guide 4, a plurality of sub illumination areas A are provided in a matrix in the X and Y directions corresponding to the intersections of the plurality of first electrodes 43 and the plurality of propagation areas 501 to 505. Yes.

Between the 1st electrode 43 and the 2nd electrode 44, the drive voltage corresponding to the light guide panel drive signal for switching the lighting state of the sub illumination area | region A and a non-lighting state from the light guide panel drive circuit 36 is. Supplied. The first electrodes of the sub illumination areas A adjacent in the X direction are connected to each other. For this reason, the orientations of the liquid crystal layers of the plurality of sub illumination areas A adjacent in the X direction are collectively changed. A plurality of sub illumination areas A adjacent in the X direction form one switching area capable of simultaneously switching between the isotropic phase state and the anisotropic phase state. The light guide 4 is provided with a plurality of switching regions 401 to 411 extending in the X direction and adjacent to each other in the Y direction.

FIG. 4 is a cross-sectional view perpendicular to the light exit surface 5 a of the light source 5.

The light source 5 includes a light emitting element 71 and a reflection mirror 72. The reflection mirror 72 reflects the light emitted from the light emitting element 71.
The light emitting element 71 is a solid light source (LED chip) formed on the base material 70, for example. The light emitting element 71 is not limited to an LED as long as it can be used as a point light source. The reflection mirror 72 has, for example, the shape of a rotating paraboloid, and the light emitting element 71 is disposed at the focal point of the paraboloid. The light emitting element 71 is integrated with the reflecting mirror 72 by the molding resin 73 in a state where the light emitting element 71 is positioned at the focal position of the reflecting mirror 72.

The light source 5 collimates the light emitted from the light emitting element 71 by the reflection mirror 72. For this reason, light having strong directivity is emitted in the direction of the optical axis of the reflection mirror 72 (the central axis of the paraboloid of revolution). The light emission surface 5 a of the light source 5 is a surface perpendicular to the optical axis of the reflection mirror 72. The light source 5 is disposed so that the light emitting surface 5a faces the light incident surface 41a of the first substrate 41 shown in FIG.
Therefore, the light source 5 emits light having strong directivity in a direction perpendicular to the light incident surface 41 a of the first substrate 41.

8A and 8B are schematic diagrams for explaining the operation of the backlight unit 3. FIG. FIG. 8A is a diagram illustrating a state in which no electric field is applied in the liquid crystal layer 45 without applying an electric field. FIG. 8B is a diagram illustrating an electric field application state in which an electric field is generated inside the liquid crystal layer 45. 8A and 8B, the shape of the liquid crystal 45a as a refractive index ellipsoid is indicated by a circle or an ellipse. A circle indicates an isotropic phase state, and an ellipse indicates an anisotropic phase state. In FIG. 8A and FIG. 8B, only components necessary for the description are illustrated.

As shown in FIG. 8A, the liquid crystal layer 45 is in an optically isotropic phase when no electric field is applied. The light including the first polarized light Lp and the second polarized light Ls emitted from the light source is absorbed or reflected by the polarizing layer 60, and only the first polarized light Lp enters the first substrate 41. Since the liquid crystal layer 45 has an isotropic phase, the polarization state of the first polarized light Lp propagating through the first substrate 41 and obliquely incident on the liquid crystal layer 45 from the first substrate 41 is changed by the liquid crystal layer 45. Without being incident on the optical layer 46. Since the optical layer 46 has a small refractive index with respect to the first polarized light Lp, the first polarized light Lp incident on the optical layer 46 is totally reflected on the surface of the optical layer 46, and the inside of the liquid crystal layer 45 and the first substrate 41. To propagate. The first polarized light Lp is reflected by the optical layer 46 and does not exit from the light diffusion plate 48 to the outside. Therefore, it will be in a non-lighting state.

As shown in FIG. 8B, in the electric field application state, the liquid crystal layer 45 is in an anisotropic phase having optical anisotropy. The polarization state of the first polarized light Lp propagating through the first substrate 41 and obliquely incident on the liquid crystal layer 45 from the first substrate 41 is changed by the liquid crystal layer 45. Since the first polarized light Lp travels in a direction substantially perpendicular to the layer thickness direction of the liquid crystal layer 45, it passes through the liquid crystal layer 45 as compared with a normal configuration in which light travels in the layer thickness direction of the liquid crystal layer. The distance is long. Therefore, the first polarized light Lp is efficiently converted into the second polarized light Ls by the liquid crystal layer 45.

The first polarized light Lp transmitted through the liquid crystal layer 45 and converted into the second polarized light Ls is incident on the optical layer 46. Since the optical layer 46 exhibits a large refractive index with respect to the second polarized light Ls, the second polarized light Ls incident on the optical layer 46 passes through the optical layer 46 and enters the polarizing layer 47. Since the transmission axis of the polarizing layer 47 is parallel to the second polarized light Ls, the second polarized light Ls transmitted through the optical layer 46 reaches the light diffusing plate 48 without being absorbed by the polarizing layer 47, and the light diffusing plate 48. Is diffused and emitted to the outside. Therefore, it will be in a lighting state.

The light diffusion plate 48 diffuses the second polarized light Ls that travels obliquely inside the liquid crystal layer 45 and enters the light diffusion plate 48 obliquely in the normal direction (Z direction) of the light exit surface of the light diffusion plate 48. Let Thereby, the light of a Z direction can be supplied with respect to the liquid crystal panel 2 (refer FIG. 1) facing the light guide 4, and the contrast of the liquid crystal panel 2 can be improved.

FIG. 5 is a block diagram showing an electrical configuration of the liquid crystal display device 1.

The liquid crystal display device 1 includes a liquid crystal panel 2, a backlight unit 3, a video signal control circuit 30, a gradation control circuit 31, a gate line driving circuit 32, a data line driving circuit 33, and a light source control circuit 34. A light source drive circuit 35 and a light guide panel drive circuit 36.

On the first substrate of the liquid crystal panel 2, a plurality of gate lines 21 and a plurality of data lines 22 are arranged in a lattice pattern. A thin film transistor (TFT) 23 is provided corresponding to each intersection of the gate line 21 and the data line 22. The thin film transistor 23 has a gate connected to the gate line 21, a source connected to the data line 22, and a drain connected to the pixel electrode 24. A counter electrode 26 is provided at a position on the second substrate of the liquid crystal panel 2 facing the pixel electrode 24. A counter electrode potential Vcom is supplied to the counter electrode 26 by a power supply circuit (not shown). A liquid crystal layer 25 is sandwiched between the pixel electrode 24 and the counter electrode 26. A region where the orientation of the liquid crystal layer 25 is controlled by one pixel electrode 24 and the counter electrode 26 is a display element PX which is a minimum unit of display.

In the backlight unit 3, a plurality of stripe-shaped propagation areas 501 to 505 and a plurality of stripe-shaped switching areas 401 to 405 are arranged in a lattice pattern. The propagation areas 501 to 505 are formed inside the light guide 4. The switching areas 401 to 405 switch between a lighting state and a non-lighting state of light propagating inside the light guide 4.
The propagation areas 501 to 505 are areas in which light propagates inside the light guide 4.

In each switching region 401 to 405, a first electrode 43 for performing switching control is formed. A region where the propagation regions 501 to 505 overlap with the switching regions 401 to 405 is a sub illumination region A. In the light guide 4, a plurality of sub illumination areas A are provided in a matrix along the X direction and the Y direction. In FIG. 5, the number of light sources 5 is five and the number of switching areas 401 to 405 is five. However, the number of light sources and switching areas is not limited to this.

The video signal control circuit 30 generates an image control signal and a light source control signal based on a video signal input from the outside.

The light source control signal is a signal for instructing the amount of emitted light for each light source 5 and emitting the light at a predetermined timing. The amount of the emitted light is set according to the brightness of the image of the display portion of the liquid crystal panel 2 corresponding to the sub illumination area A (the gradation value of the video signal input from the outside). For example, in a portion where a dark image is displayed, the amount of light emitted from the sub illumination area A (light emitted from the light source 5 corresponding to the sub illumination area A) is reduced. On the other hand, in a portion where a bright image is displayed, the amount of light emitted from the sub illumination area A (light emitted from the light source 5 corresponding to the sub illumination area A) is increased. Thereby, compared with the structure which always irradiates the light of the maximum light quantity to the whole display area of the liquid crystal panel 2, power consumption can be reduced and contrast can also be improved.

The image control signal is a signal that determines what gradation is to be given to each display element PX of the liquid crystal panel 2. The amount of light emitted from the light guide 4 is controlled for each sub illumination area A. Therefore, the gradation value actually obtained for each display element PX corresponds to the amount of light emitted from the sub-illumination area A emitted to each display element PX with respect to the gradation signal obtained from the video signal. Correction (extension processing) is added.

The gradation control circuit 31 generates a horizontal drive signal and a vertical drive signal based on the image control signal. The gate line driving circuit 32 sequentially selects the plurality of gate lines 21 of the liquid crystal panel 2 in the order of S1, S2, S3,..., Sm within one vertical scanning period based on the horizontal driving signal. Based on the horizontal drive signal, the data line drive circuit 33 sequentially outputs the grayscale signals in the order of D1, D2, D3,..., Dn to the plurality of data lines 22 of the liquid crystal panel 2 within one horizontal scanning period. Supply. As a result, an image for one frame is displayed in the display area 2 </ b> A of the liquid crystal panel 2.

The light source control circuit 34 generates a light source drive signal and a light guide panel drive signal based on the light source control signal. The light source drive signal is a signal indicating the brightness, lighting time, and emission timing of the emitted light that each light source 5 should emit. The luminance depends on the magnitude of the drive current that drives the light source 5. The amount of light emitted from the light source 5 is controlled by controlling the lighting time of the light source 5 by pulse width modulation (PWM) when the luminance is constant. The light guide panel drive signal is a signal indicating the timing when each of the switching regions 401 to 405 is in an anisotropic phase state.

The light guide panel drive circuit 36 individually selects the plurality of first electrodes 43 of the light guide 4 within one vertical scanning period based on the light guide panel drive signal, and turns on / off the switching areas 401 to 405. Switch between and. Based on the light source drive signal, the light source drive circuit 35 emits light with the brightness and lighting time designated from each light source 5 within one horizontal scanning period. Thereby, the light of the light quantity controlled by the light source drive circuit 35 is emitted from the plurality of sub illumination areas A toward the liquid crystal panel 2.

FIG. 6 is a plan view of a plurality of sub illumination areas A ₁₁ to A ₅₅ viewed from the Z direction.

The light guide 4 is provided with a plurality of sub illumination areas A ₁₁ to A ₅₅ that can independently control the amount of light emitted toward the liquid crystal panel 2 (see FIG. 1). The sub illumination areas A ₁₁ to A ₅₅ are formed by arranging a plurality of switching areas 401 to 405 and a plurality of propagation areas 501 to 505 in a grid pattern. The amount of light emitted from the sub illumination areas A ₁₁ to A ₅₅ is controlled by the luminance and lighting time of the light source 5 (see FIG. 1) that makes the light incident along the propagation paths 501 to 505.

7 (a) to 7 (f) are diagrams showing an example of a method for controlling the light sources 51 to 55 and the switching areas 401 to 405. FIG. FIGS. 7A to 7E show the flow of processing in time order. The left part of FIGS. 7A to 7E shows the selection position of the switching area. FIG. 7 (f) is a diagram showing the light amount distribution of the emitted light obtained by the processes of FIGS. 7 (a) to 7 (e). 7A to 7F, the reference numerals of the plurality of light sources 5 shown in FIG. 1 are indicated by different reference numerals (51 to 55) for convenience.

First, as shown in FIG. 7A, in the period from time t0 to t1, the switching area 401 in the first row is switched to the anisotropic phase state. In accordance with this switching timing, a predetermined amount of light is emitted from each of the light sources 51 to 55 within a period from time t0 to t1. In FIG. 7A, for example, the light amounts of the light source 51 and the light source 52 are I1, the light amount of the light source 53 is I2, and the light amounts of the light source 54 and the light source 55 are zero.

Next, as shown in FIG. 7B, the switching area 402 in the second row is switched to the anisotropic phase state in the period from time t1 to t2. In accordance with this switching timing, a predetermined amount of light is emitted from each of the light sources 51 to 55 within a period from time t1 to t2. In FIG. 7B, for example, the light amounts of the light source 51 and the light source 53 are I1, the light amount of the light source 52 is I3, and the light amounts of the light source 54 and the light source 55 are zero.

Next, as shown in FIG. 7C, the switching region 403 in the third row is switched to the anisotropic phase state in the period from time t2 to t3. In accordance with this switching timing, a predetermined amount of light is emitted from each of the light sources 51 to 55 within a period from time t2 to t3. In FIG. 7C, for example, the light amounts of the light source 51, the light source 53, and the light source 55 are I2, and the light amounts of the light source 52 and the light source 54 are I1.

Next, as shown in FIG. 7 (d), in the period from time t3 to t4, the switching area 404 in the fourth row is switched to the anisotropic phase state. In accordance with this switching timing, a predetermined amount of light is emitted from each of the light sources 51 to 55 within a period from time t3 to t4. In FIG. 7D, for example, the light amount of the light source 54 is I2, the light amount of the light source 55 is I1, and the light amounts of the light source 51, the light source 52, and the light source 53 are zero.

Next, as shown in FIG. 7E, the switching area 405 in the fifth row is switched to the anisotropic phase state in the period from time t4 to t5. In accordance with this switching timing, a predetermined amount of light is emitted from each of the light sources 51 to 55 within a period from time t4 to t5. In FIG. 7E, for example, the light amounts of the light source 51, the light source 52, the light source 53, the light source 54, and the light source 55 are all zero.

FIG. 7 (f) is a diagram showing a light amount distribution of light emitted from the light guide 6 during a period from time t1 to t5. This light quantity distribution is controlled based on the brightness distribution of the image for one frame. In the light amount distribution of FIG. 7 (f), the upper left and lower right light amounts of the light guide 4 are large, and the upper right and lower left light amounts of the light guide 6 are small. Therefore, the display image has a light amount distribution suitable for displaying an image with bright upper left and lower right of the screen and dark upper right and lower left of the screen.

The amount of light emitted from each of the sub illumination areas A ₁₁ to A ₅₅ is controlled independently according to the brightness of the display image corresponding to each sub illumination area. The video signal supplied to each display element of the liquid crystal panel 2 is expanded according to the amount of light emitted from the sub illumination area. The liquid crystal display device 1 can display images with low power consumption and high contrast by area active control that combines dimming control and expansion control. In the light control, the amount of light emitted from each of the sub illumination areas A ₁₁ to A ₅₅ is adjusted. In the expansion control, the video signal of each display element of the liquid crystal panel 2 is expanded.

In the liquid crystal display device 1, the birefringence of light that propagates in the Y direction inside the first substrate 41 and enters the liquid crystal layer 45 obliquely from the first substrate 41 is changed. Thus, the amount of light that travels obliquely inside the liquid crystal layer 45 and is diffused by the light diffusion plate 48 and emitted to the outside is controlled. Therefore, high-quality image display by area active control is possible while using the thin backlight unit 3 of the edge light system.

Since the light propagating through the first substrate 41 is incident on the liquid crystal layer 45 at a shallow angle (a large angle greater than the critical angle with respect to the Z direction), the traveling direction is substantially parallel to the Y direction. .
Unlike the case where light is incident in the thickness direction of the liquid crystal layer as in a normal liquid crystal panel, the light travels in a direction substantially perpendicular to the thickness direction of the liquid crystal layer 45. Therefore, even when the distance of light passing through the liquid crystal layer 45 is long and the liquid crystal layer 45 having a small thickness is used, the polarization state of the light can be greatly changed. By reducing the thickness of the liquid crystal layer 45, the magnitude of the voltage applied between the first electrode 43 and the second electrode 44 can be reduced. The blue phase liquid crystal layer 45 is known to have a high driving voltage. However, by reducing the thickness of the liquid crystal layer 45, the driving voltage can be reduced and the power consumption can be reduced.

[First Modification of First Embodiment]
FIG. 9 is a first modification of the backlight unit 3 of the first embodiment.

In the first modification of the first embodiment shown in FIG. 9, the polarizing layer 47 between the light diffusing plate 48 and the optical layer 46 is omitted. This configuration also produces the same effect as the backlight unit 3 in FIG.

[Second Modification of First Embodiment]
FIG. 10 is a second modification of the backlight unit 3 of the first embodiment.

In the second modification of the first embodiment shown in FIG. 10, the polarizing layer 60 provided on the light incident surface of the first substrate 41 is omitted. Further, the first substrate 41 is arranged on a second end surface different from the first end surface that is the light incident surface of the first substrate 41 (for example, an end surface provided on a side opposite to the side on which the light incident surface is provided). A polarization conversion layer 62 is provided for converting the second polarized light Ls propagating through the first polarized light Lp into the first polarized light Lp. The polarization conversion layer 62 includes, for example, a λ / 4 layer 62a disposed on the second end face, and a reflective layer 62b that reflects the second polarized light Ls that has passed through the λ / 4 layer 62a and has become circularly polarized light. Prepare.

The light including the first polarized light Lp and the second polarized light Ls emitted from the light source enters the first substrate 41 from the light incident surface of the first substrate 41. The refractive index of the liquid crystal layer 45 is a refractive index that transmits the first polarized light Lp and totally reflects the second polarized light Ls. For example, when the liquid crystal layer 45 is in an isotropic phase (no electric field applied state), the average refractive index is nD, and when the liquid crystal layer 45 is in an anisotropic phase state (electric field applied state), the ordinary light refractive index is no, The refractive index is ne, and the refractive index of the first substrate 41 or the first electrode that forms an interface with the liquid crystal layer 45 is nW. At this time, if the relationship of no ≦ nD ≦ nW ≦ ne is established, the above operation is possible.

The second polarized light Ls that has propagated through the first substrate 41 is converted into the first polarized light Lp by the polarization conversion layer 62, and is externally transmitted from the sub-illumination region in the anisotropic phase state (electric field applied state) through the light diffusion plate 48. To exit. In the second modification of the first embodiment, the light component absorbed by the polarizing layer 60 is not generated, so that the light emitted from the light source can be used efficiently.

[Second Embodiment]
FIG. 11 is an exploded perspective view of the liquid crystal display device 6 of the second embodiment. In the liquid crystal display device 6, the same reference numerals are given to components common to the liquid crystal display device 1 of the first embodiment, and detailed description thereof will be omitted.

The liquid crystal display device 6 includes a liquid crystal panel 2 and a backlight unit (liquid crystal device) 7.

The backlight unit 7 includes a plurality of light sources 5 and a light guide 8. The light guide 8 spreads light incident from the plurality of light sources 5 in a planar shape and emits the light toward the liquid crystal panel 2.

The light guide 8 is a light guide panel including a first substrate 41 and a second substrate 42. The second substrate 42 is disposed to face the first substrate 41.
The first substrate 41 is a light guide plate having a light incident surface on the end surface 41a. A rectangular frame-shaped sealing material 49 is provided at the peripheral edge of the facing region where the first substrate 41 and the second substrate 42 face each other, and the space surrounded by the first substrate 41, the second substrate 42, and the sealing material 49. The liquid crystal layer is enclosed in

A plurality of stripe-shaped switching areas 401, 402, 403, 404, and 405 that can be switched between a lighting state (ON state) and a non-lighting state (OFF state) are provided inside the sealing material 49. In the lighting state (ON state), light propagating inside the light guide 8 is emitted to the outside of the light guide 8. In the non-lighting state (OFF state), the light propagating inside the light guide 8 is not emitted to the outside of the light guide 8.
The plurality of switching areas 401 to 405 are arranged adjacent to each other in the Y direction.

FIG. 12 is a cross-sectional view of the backlight unit 7 parallel to the YZ plane.

The light guide 8 includes a first substrate 41, a second substrate 42, a liquid crystal layer 45, and a light diffusion plate 48. The second substrate 42 is disposed to face the first substrate 41. The liquid crystal layer 45 is sandwiched between the first substrate 41 and the second substrate 42. The light diffusing plate 48 is provided on the outer surface side (the side opposite to the liquid crystal layer 45) of the second substrate 42.

The first substrate 41 is provided on a second end surface different from the first end surface that is the light incident surface 41a of the first substrate 41 (for example, an end surface provided on a side opposite to the side on which the light incident surface 41a is provided). There is provided a polarization conversion layer 62 that propagates through the substrate and converts the second polarized light Ls incident on the end face thereof into the first polarized light Lp and reflects it toward the inside of the first substrate 41. The first polarized light Lp is polarized light parallel to the YZ plane that propagates through the first substrate 41 and enters the liquid crystal layer 45 from the first substrate 41 as P-polarized light. The second polarized light Ls is polarized light orthogonal to the first polarized light Lp. For example, as illustrated in FIG. 10, the polarization conversion layer 62 includes a λ / 4 layer 62a and a reflective layer 62b. The λ / 4 layer 62a is disposed on the second end face. The reflective layer 62b reflects the second polarized light Ls that has passed through the λ / 4 layer 62a and has become circularly polarized light.

A polarizing layer is not provided on the light path between the light source 5 and the light incident surface 41a. Light including the first polarized light Lp and the second polarized light Ls emitted from the light source 5 enters the first substrate 41 from the light incident surface 41 a of the first substrate 41.

The liquid crystal layer 45 includes a liquid crystal having a positive dielectric anisotropy indicating a blue phase. The refractive index of the liquid crystal layer 45 is a refractive index that transmits the first polarized light Lp and totally reflects the second polarized light Ls. For example, when the liquid crystal layer 45 is in an isotropic phase (no electric field applied state), the average refractive index is nD, and when the liquid crystal layer 45 is in an anisotropic phase state (electric field applied state), the ordinary light refractive index is no, Assuming that the refractive index is ne and the refractive index of the first substrate 41 or the first electrode forming an interface with the liquid crystal layer 45 is nW, the relationship of no ≦ nD ≦ nW ≦ ne is established.

In a state in which no electric field in the Z direction is generated between the first electrode 43 and the second electrode 44, the first polarized light Lp and the second polarized light Ls incident on the liquid crystal layer 45 are refracted with an average refractive index nD. . Since the average refractive index nD is smaller than the refractive index nW of the first electrode 43, the first polarized light Lp and the second polarized light Ls are totally reflected at the interface between the liquid crystal layer 45 and the first electrode 43, and Propagates the interior in the Y direction. In a region where no voltage is applied between the first electrode 43 and the second electrode 44, no light is emitted to the outside. Therefore, it becomes a non-lighting state (OFF state).

In an electric field application state in which an electric field is generated between the first electrode 43 and the second electrode 44, the first polarized light Lp incident on the liquid crystal layer 45 is refracted by the refractive index ne of extraordinary light, and the second polarized light Ls is Refracts at the refractive index no of ordinary light. The refractive index ne of extraordinary light is larger than the refractive index nW of the first electrode 43. Therefore, the first polarized light Lp is transmitted through the interface between the liquid crystal layer 45 and the first electrode 43 and travels obliquely inside the liquid crystal layer 45 to cause the second electrode 44, the second substrate 42, and the light diffusion plate 48 to pass through. To the outside. The refractive index no of ordinary light is smaller than the refractive index nW of the first electrode 43. Therefore, the second polarized light Ls is totally reflected at the interface between the liquid crystal layer 45 and the first electrode 43 and propagates in the first substrate 41 in the Y direction. Then, the light is converted into the first polarized light Lp by the polarization conversion layer 62, passes through the liquid crystal layer 45 in the region to which the electric field is applied, travels obliquely inside the liquid crystal layer 45, and enters the second electrode 44 and the second substrate 42. The light is emitted to the outside through the light diffusion plate 48. In a region where a voltage is applied between the first electrode 43 and the second electrode 44, light is emitted to the outside. Therefore, it will be in a lighting state (ON state).

In the liquid crystal display device 6, the refractive index of light propagating in the Y direction through the first substrate 41 and incident obliquely on the liquid crystal layer 45 from the first substrate 41 is changed. Thus, the amount of light that travels obliquely inside the liquid crystal layer 45 and is diffused by the light diffusion plate 48 and emitted to the outside is controlled. Therefore, high-quality image display by area active control is possible while using the thin backlight unit 7 of the edge light system.

In the liquid crystal display device 6, since no polarizing layer is provided between the light source 5 and the light incident surface 41a of the first substrate 41, no light component is absorbed by the polarizing layer. Therefore, the light emitted from the light source 5 can be used efficiently.

[First Modification of Second Embodiment]
13A and 13B are a first modification of the backlight unit 7 of the second embodiment. FIG. 13A is a diagram showing a state in which no electric field is applied in the liquid crystal layer 45 without generating an electric field. FIG. 13B is a diagram showing an electric field application state in which an electric field is generated inside the liquid crystal layer 45. In FIG. 13A and FIG. 13B, only components necessary for explanation are illustrated.

In the first modification of the second embodiment shown in FIGS. 13A and 13B, the nematic liquid crystal 46b having positive dielectric anisotropy is used instead of the blue phase liquid crystal layer, and the propagation direction of the first polarization Lp is changed. The alignment state of the liquid crystal 45b is changed in the plane including the same. The liquid crystal layer 45 is a horizontal alignment in which the alignment state when no electric field is applied is aligned in a direction substantially perpendicular to the layer thickness direction of the liquid crystal layer 45, and the alignment state when an electric field is applied is the layer thickness direction of the liquid crystal layer 45. It is a vertical alignment that is aligned substantially in parallel. The liquid crystal 45b has an alignment state in a plane including the direction in which light enters the light incident surface of the first substrate 41 and the normal direction (Z direction) of the surface facing the light diffusion plate 48 of the first substrate 41. Change. When the refractive index of ordinary light of the liquid crystal layer 45 is no, the refractive index of extraordinary light is ne, and the refractive index of the first substrate 41 or the first electrode forming an interface with the liquid crystal layer 45 is nW, no <nW <ne. A relationship is established.

As shown in FIG. 13A, in the state where no electric field is applied, the first polarized light Lp and the second polarized light Ls incident on the liquid crystal layer 45 are refracted at the refractive index no of ordinary light. The refractive index no of ordinary light is smaller than the refractive index nW of the first electrode 43. Therefore, the first polarized light Lp and the second polarized light Ls are totally reflected at the interface between the liquid crystal layer 45 and the first electrode 43 and propagate in the first substrate 41 in the Y direction. In a region where no voltage is applied between the first electrode 43 and the second electrode 44, no light is emitted to the outside. Therefore, it becomes a non-lighting state (OFF state).

As shown in FIG. 13B, in the electric field application state, the first polarized light Lp incident on the liquid crystal layer 45 is refracted with the refractive index ne of extraordinary light, and the second polarized light Ls is refracted with the refractive index no of ordinary light. The refractive index ne of extraordinary light is larger than the refractive index nW of the first electrode 43. Therefore, the first polarized light Lp is transmitted through the interface between the liquid crystal layer 45 and the first electrode 43 and travels obliquely inside the liquid crystal layer 45 to cause the second electrode 44, the second substrate 42, and the light diffusion plate 48 to pass through. To the outside. The refractive index no of ordinary light is smaller than the refractive index nW of the first electrode 43. Therefore, the second polarized light Ls is totally reflected at the interface between the liquid crystal layer 45 and the first electrode 43 and propagates in the first substrate 41 in the Y direction. Then, the light is converted into the first polarized light Lp by the polarization conversion layer 62, passes through the liquid crystal layer 45 in the region to which the electric field is applied, travels obliquely inside the liquid crystal layer 45, and enters the second electrode 44 and the second substrate 42. The light is emitted to the outside through the light diffusion plate 48. In a region where a voltage is applied between the first electrode 43 and the second electrode 44, light is emitted to the outside. Therefore, it will be in a lighting state (ON state).

13A and 13B, although the alignment form of the liquid crystal layer 45 is different from that of the blue phase liquid crystal layer, the lighting state and the non-lighting state can be controlled by substantially the same action.

[Third Embodiment]
FIG. 14 is an exploded perspective view of the liquid crystal display device 100 of the third embodiment.

The liquid crystal display device 100 includes a first substrate 110, a plurality of light sources 105, a second substrate 111, a polarizing layer 113, and a light diffusing plate 118. The light source 105 makes light incident on the end surface (light incident surface) 110 a of the first substrate 110. The second substrate 111 is disposed to face the first substrate 110. The polarizing layer 113 is provided on the outer surface side of the second substrate 111. The light diffusing plate 118 is provided on the outer surface side of the polarizing layer 113.
A rectangular frame-shaped sealing material 119 is provided at the peripheral edge of the facing region where the first substrate 110 and the second substrate 111 face each other. Liquid crystal (not shown) is sealed in a space surrounded by the first substrate 110, the second substrate 111, and the sealing material 119.

A display region 100A is provided inside the sealing material 119. In the display area 100 </ b> A, a plurality of gate lines 121 extending in the X direction and a plurality of data lines 122 extending in the Y direction are provided on the first substrate 110 in a lattice shape in plan view. A display element corresponding to any one of red, green, and blue is provided at the intersection between the gate line 121 and the data line 122. On the first substrate 110, a plurality of display elements are arranged in a matrix in the X direction and the Y direction, and a display region 100A is formed by the plurality of display elements.

The light source 105 is, for example, a light emitting diode (LED) that emits white light. The light source 105 may be anything that can be used as a point light source, and may be an organic EL (Electro-Luminescence) element. A plurality of light sources 105 are arranged at positions facing the light incident surface 110 a of the first substrate 110. In FIG. 14, five light sources 105 are provided, but the number of light sources 105 is not limited to this. The plurality of light sources 105 are arranged in the X direction with the light emitting surface opposed to the light incident surface 110 a of the first substrate 110. The configuration of the light source 105 is the same as that of the light source 5 shown in FIG.

FIG. 15 is a cross-sectional view of the liquid crystal display device 100 parallel to the YZ plane.

The liquid crystal display device 100 includes a first substrate 110, a light source 105, a second substrate 111, a liquid crystal layer 115, an optical layer 116, a polarizing layer 113, and a light diffusing plate 118. The light source 105 makes light incident on the end surface (light incident surface) 110 a of the first substrate 110. The second substrate 111 is disposed to face the first substrate 110. The liquid crystal layer 115 is sandwiched between the first substrate 110 and the second substrate 111. The optical layer 116 is provided between the second substrate 111 and the liquid crystal layer 115. The polarizing layer 113 is provided on the outer surface side of the second substrate 111 (the side opposite to the liquid crystal layer 115). The light diffusing plate 118 is provided on the outer surface side of the polarizing layer 113.

The first substrate 110 and the second substrate 111 are transparent plate materials made of polystyrene or glass. An end surface of the first substrate 110 facing the light source 105 is a light incident surface 110 a on which light emitted from the light source 105 is incident. The first substrate 110 is a light guide plate having a light incident surface on the end surface 110a. The light incident surface 110a is inclined with respect to the XY plane. The inclination angle of the light incident surface 110 a with respect to the XY plane is an angle at which light emitted from the light source 105 in a direction substantially orthogonal to the light incident surface 110 a is totally reflected inside the first substrate 110.

The light source 105 is preferably a directional light source. In order to satisfy the total reflection condition, it is preferable that the angle range of the light incident on the first substrate 110 is narrowed to about a half width of 5 degrees or less.

The reflective layer 130 is provided on an end surface different from the light incident surface 110a of the first substrate 110 (for example, an end surface provided on a side opposite to the side on which the light incident surface 110a is provided). The reflective layer 130 is light that propagates inside the first substrate 110 and reflects the light incident on the end surface thereof toward the inside of the first substrate 110.

The first substrate 110 is provided with a plurality of first electrodes 124 made of a transparent conductive film such as ITO (Indium Tin Oxide). A second electrode 125 made of a transparent conductive film such as ITO is provided on the second substrate 124 so as to face the plurality of first electrodes 124. The first electrode 124 is a pixel electrode provided for each display element. The second electrode 125 is a common electrode (counter electrode) common to the plurality of first electrodes 124. A region in which the orientation of the liquid crystal layer 115 is controlled by one first electrode 124 and one second electrode 125 (a region where the first electrode 124 and the second electrode 125 face each other) is the minimum display corresponding to one display element. It is an area. In FIG. 15, five first electrodes 124 are provided in the Y direction, but actually, hundreds to thousands of first electrodes 124 are provided.

On the inner surface side (liquid crystal layer 115 side) of the second substrate 111, a color filter layer 117 is provided in which a color filter 117a of any one of red, green, and blue is arranged for each display element. On the inner surface side of the color filter layer 117, an optical layer 116 is provided over the entire display region 100a. A second electrode 125 is provided on the inner surface side of the optical layer 116. A polarizing layer 113 that transmits the second polarized light Ls that has passed through the optical layer 116 is provided on the outer surface side of the second substrate 111. A light diffusing plate 118 that diffuses and emits the second polarized light transmitted through the polarizing layer 113 is provided on the outer surface side of the polarizing layer 113.

A polarizing layer 112 that transmits the first polarized light Lp is provided on the light path between the light source 105 and the light incident surface 110a. The polarizing layer 112 is, for example, a polarizing plate having a transmission axis parallel to the intersecting line where the YZ plane and the light incident surface 110a intersect. The first polarized light Lp is light that enters the optical layer 116 as P-polarized light. The polarizing layer 112 is installed on the light incident surface 110a, and the light emitting surface of the light source 105 and the light incident surface 110a of the first substrate 110 face each other with the polarizing layer 112 interposed therebetween. Of the light emitted from the light source 105, the second polarized light Ls that enters the interface between the second electrode 125 and the optical layer 116 as S-polarized light is absorbed or reflected by the polarizing layer 112. Only the first polarized light Lp that enters the interface between the second electrode 125 and the optical layer 116 as P-polarized light enters the first substrate 110.

The liquid crystal layer 115 includes a liquid crystal having a positive dielectric anisotropy indicating a blue phase. The blue phase is a liquid crystal phase in which a plurality of spiral structures having different spiral axes are in a three-dimensional periodic structure. The blue phase itself is optically isotropic, and is transformed to a nematic phase by applying a voltage. The orientation of the liquid crystal layer 115 is controlled by an electric field generated between the first electrode 124 and the second electrode 125. The blue phase liquid crystal layer 115 exhibits a Kerr effect (Kerr effect). The refractive index of the liquid crystal layer 115 is proportional to the square of the electric field strength. The response time of the blue phase liquid crystal is about 10 microseconds, which is much shorter than the response time of normal nematic liquid crystal (10 milliseconds).

An electric field is not generated between the first electrode 124 and the second electrode 125, and the refractive index of the liquid crystal layer 115 in an electric field application state in which an electric field in the Z direction is generated between the first electrode 124 and the second electrode 125. The refractive index of the liquid crystal layer 115 in a state where no electric field is applied is substantially equal to the refractive indexes of the first substrate 110, the second substrate 111, the first electrode 124, and the second electrode 125. Therefore, light incident from the light incident surface 110 a of the first substrate 110 passes through the first electrode 124, the liquid crystal layer 115, and the second electrode 125 and reaches the optical layer 116.

The optical layer 116 is an optical anisotropic body having a different refractive index depending on the polarization state of incident light. The optical layer 116 has a relatively small refractive index with respect to the first polarized light Lp and a relatively large refractive index with respect to the second polarized light Ls. The refractive index of the optical layer 116 with respect to the first polarized light Lp is smaller than the refractive index of the second electrode 125. Therefore, the first polarized light Lp incident on the optical layer 116 from the second electrode 125 is totally reflected on the surface of the optical layer 116. The refractive index of the optical layer 116 with respect to the second polarized light Ls is equal to or larger than the refractive index of the second electrode 125. Therefore, the second polarized light Ls incident on the optical layer 116 from the second electrode 125 passes through the optical layer 116 and enters the second substrate 111.

In an electric field non-application state, the liquid crystal disposed between the first electrode 124 and the second electrode 125 is in a special alignment state called a blue phase. Accordingly, the liquid crystal layer 115 has an optical isotropic phase having no optical anisotropy. The first polarized light Lp incident on the liquid crystal layer 115 is incident on the optical layer 116 without changing the polarization state when no electric field is applied. Therefore, the first polarized light Lp is reflected on the surface of the optical layer 116 and propagates in the liquid crystal display device 100 in the Y direction. In a region where no voltage is applied between the first electrode 124 and the second electrode 125, no light is emitted to the outside. Therefore, it becomes a non-lighting state (OFF state).

In the electric field application state, the liquid crystal disposed between the first electrode 124 and the second electrode 125 is generally aligned in the Z direction. Therefore, the liquid crystal layer 115 becomes an optically anisotropic phase having optical anisotropy. Since the liquid crystal layer 115 upon application of an electric field has birefringence, the first polarized light Lp incident on the liquid crystal layer 115 is elliptically polarized light in the liquid crystal layer 115 or second polarized light Ls (optical) orthogonal to the first polarized light Lp. Linearly polarized light that is incident on the layer 116 as S-polarized light). Therefore, a part of the first polarized light Lp whose polarization state is converted by the liquid crystal layer 115 passes through the optical layer 116 and enters the second substrate 111, and reaches the polarizing layer 113.

The polarizing layer 113 is a polarizing plate having a transmission axis parallel to the X direction. Therefore, the second polarized light Ls that has passed through the optical layer 116 passes through the polarizing layer 113, is diffused by the light diffusion plate 118, and is emitted to the outside. The surface of the light diffusing plate 118 is a light emitting surface 118 a from which light propagated through the liquid crystal display device 100 is emitted. In a region where a voltage is applied between the first electrode 124 and the second electrode 125, light is emitted to the outside. Therefore, it will be in a lighting state (ON state).

The amount of light incident on the first substrate 110 from the light source 105 is set according to the brightness of the image of the display element illuminated by the light source 105 (the gradation value of the video signal input from the outside). For example, in a display element displaying a dark image, the amount of light emitted from the light source 105 is reduced. On the other hand, for a display element displaying a bright image, the amount of light emitted from the light source 105 is increased. Accordingly, the video signal supplied to the display element is expanded according to the amount of light emitted from the light source 105. As a result, power consumption can be reduced and contrast can be improved as compared with a configuration in which the entire display region is always irradiated with the maximum amount of light.

In the liquid crystal display device 100, the birefringence of the light that propagates in the Y direction inside the first substrate 110 and enters the liquid crystal layer 115 obliquely from the first substrate 110 is changed. Thus, the amount of light that travels obliquely inside the liquid crystal layer 115 and is diffused by the light diffusion plate 118 and emitted to the outside is controlled. Therefore, high-quality image display by area active control is possible while realizing a thin liquid crystal display device of the edge light system.

Since the light propagating through the first substrate 110 is incident on the liquid crystal layer 115 at a shallow angle (a larger angle than the critical angle with respect to the Z direction), the traveling direction is substantially parallel to the Y direction. . Unlike the case where light is incident in the thickness direction of the liquid crystal layer as in a normal liquid crystal panel, the light travels in a direction substantially perpendicular to the thickness direction of the liquid crystal layer 115. Therefore, even when the distance of light passing through the liquid crystal layer 115 is long and the liquid crystal layer 115 having a small thickness is used, the polarization state of the light can be greatly changed. By reducing the thickness of the liquid crystal layer 115, the magnitude of the voltage applied between the first electrode 124 and the second electrode 125 can be reduced.
The blue phase liquid crystal layer 115 is known to have a high driving voltage. However, by reducing the thickness of the liquid crystal layer 115, the driving voltage can be reduced and the power consumption can be reduced.

[Fourth Embodiment]
FIG. 16 is an exploded perspective view of a liquid crystal display device (liquid crystal device) 101 according to the fourth embodiment. In the liquid crystal display device 101, the same reference numerals are given to components common to the liquid crystal display device 100 of the third embodiment, and detailed description thereof will be omitted.

The liquid crystal display device 101 includes a first substrate 110, a plurality of light sources 105, a second substrate 111, and a light diffusion plate 118. The light source 105 makes light incident on the end surface (light incident surface) 110 a of the first substrate 110. The second substrate 111 is disposed to face the first substrate 110. The light diffusion plate 118 is provided on the outer surface side of the second substrate 111.
A rectangular frame-shaped sealing material 119 is provided at the peripheral edge of the facing region where the first substrate 110 and the second substrate 111 face each other. Liquid crystal (not shown) is sealed in a space surrounded by the first substrate 110, the second substrate 111, and the sealing material 119.

FIG. 17 is a cross-sectional view of the liquid crystal display device 101 parallel to the YZ plane.

The liquid crystal display device 101 includes a first substrate 110, a light source 105, a second substrate 111, a liquid crystal layer 115, and a light diffusion plate 118. The light source 105 makes light incident on the end surface (light incident surface) 110 a of the first substrate 110. The second substrate 111 is disposed to face the first substrate 110. The liquid crystal layer 115 is sandwiched between the first substrate 110 and the second substrate 111. The light diffusion plate 118 is provided on the outer surface side of the second substrate 111.

A polarization conversion layer 131 is provided on a second end surface different from the first end surface that is the light incident surface 110a of the first substrate 110 (for example, an end surface provided on a side opposite to the side on which the light incident surface 110a is provided). Is provided. The polarization conversion layer 131 is light that has propagated inside the first substrate 110, and converts the second polarized light Ls incident on the end surface thereof into the first polarized light Lp and reflects it toward the inside of the first substrate 110. .
The first polarized light Lp is polarized light parallel to the YZ plane that propagates through the first substrate 110 and enters the liquid crystal layer 115 from the first substrate 110 as P-polarized light. The second polarized light Ls is polarized light orthogonal to the first polarized light Lp. For example, as illustrated in FIG. 10, the polarization conversion layer 131 includes a λ / 4 layer 62a and a reflective layer 62b. The λ / 4 layer 62a is disposed on the second end face. The reflective layer 62b reflects the second polarized light Ls that has passed through the λ / 4 layer 62a and has become circularly polarized light.

A polarizing layer is not provided on the optical path of light between the light source 105 and the light incident surface 110a.
Light including the first polarized light Lp and the second polarized light Ls emitted from the light source 105 enters the first substrate 110 from the light incident surface 110 a of the first substrate 110.

The liquid crystal layer 115 includes a liquid crystal having a positive dielectric anisotropy indicating a blue phase. The refractive index of the liquid crystal layer 115 is a refractive index that transmits the first polarized light Lp and totally reflects the second polarized light Ls. For example, the average refractive index when the liquid crystal layer 115 is isotropic (no electric field applied state) is nD, and the ordinary refractive index when the liquid crystal layer 115 is an anisotropic phase (electric field applied state) is no. When the refractive index is ne and the refractive index of the first substrate 110 or the first electrode 124 that forms an interface with the liquid crystal layer 115 is nW, the relationship of no ≦ nD ≦ nW ≦ ne is established.

In a state where no electric field in the Z direction is generated between the first electrode 124 and the second electrode 125, the first polarized light Lp and the second polarized light Ls incident on the liquid crystal layer 115 are refracted with an average refractive index nD. . Since the average refractive index nD is smaller than the refractive index nW of the first electrode 124, the first polarized light Lp and the second polarized light Ls are totally reflected at the interface between the liquid crystal layer 115 and the first electrode 124, and Propagates the interior in the Y direction. In a region where no voltage is applied between the first electrode 124 and the second electrode 125, no light is emitted to the outside. Therefore, it becomes a non-lighting state (OFF state).

In an electric field application state in which an electric field is generated between the first electrode 124 and the second electrode 125, the first polarized light Lp incident on the liquid crystal layer 115 is refracted with the refractive index ne of extraordinary light, and the second polarized light Ls is Refracts at the refractive index no of ordinary light. The refractive index ne of extraordinary light is larger than the refractive index nW of the first electrode 124. Therefore, the first polarized light Lp passes through the interface between the liquid crystal layer 115 and the first electrode 124, travels obliquely inside the liquid crystal layer 115, and passes through the second electrode 125, the second substrate 111, and the light diffusion plate 118. To the outside. The refractive index no of ordinary light is smaller than the refractive index nW of the first electrode 124. Therefore, the second polarized light Ls is totally reflected at the interface between the liquid crystal layer 115 and the first electrode 124 and propagates in the first substrate 110 in the Y direction. Then, the light is converted into the first polarized light Lp by the polarization conversion layer 131, passes through the liquid crystal layer 115 in the region to which the electric field is applied, and travels obliquely through the liquid crystal layer 115 to form the second electrode 125, the second substrate 111, and the like. The light is emitted to the outside through the light diffusion plate 118. In a region where a voltage is applied between the first electrode 124 and the second electrode 125, light is emitted to the outside. Therefore, it will be in a lighting state (ON state).

In the liquid crystal display device 101, the refractive index of light propagating in the Y direction through the first substrate 110 and obliquely incident on the liquid crystal layer 115 from the first substrate 110 is changed. Thus, the amount of light that travels obliquely inside the liquid crystal layer 115 and is diffused by the light diffusion plate 118 and emitted to the outside is controlled. Therefore, high-quality image display by area active control is possible while realizing a thin liquid crystal display device of the edge light system.

In the liquid crystal display device 101, since no polarizing layer is provided between the light source 105 and the light incident surface 110a of the first substrate 110, no light component is absorbed by the polarizing layer. Therefore, the light emitted from the light source 105 can be used efficiently.

[Fifth Embodiment]
FIG. 18 is a cross-sectional view parallel to the YZ plane of the liquid crystal display device (liquid crystal device) 102 of the fifth embodiment. In the liquid crystal display device 102, components common to the liquid crystal display device 100 of the third embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

The difference between the liquid crystal display device 102 and the liquid crystal display device 100 of the third embodiment is that the color filter layer is omitted and different light colors (for example, red light, green light, and blue light) are applied to the light source 135. A plurality of light emitting elements that emit light are provided, and light of different colors is sequentially emitted from each light emitting element at different timings. In addition, an electric field corresponding to the gradation of the image of the color emitted from the light emitting elements is generated inside the liquid crystal layer 115 in accordance with the timing at which the plurality of light emitting elements emit light.

FIG. 19 is a cross-sectional view perpendicular to the light exit surface 135a of the light source 135. FIG.

The light source 135 includes a light emitting element 71R, a light emitting element 71G, a light emitting element 71B, and a reflection mirror 72. The light emitting element 71R emits red light. The light emitting element 71G emits green light. The light emitting element 71B emits blue light. The reflection mirror 72 reflects the light emitted from the light emitting elements 71R, 71G, 71B.
The light emitting elements 71R, 71G, 71B are solid light sources (LED chips) formed on the base material 70, for example. The light emitting elements 71R, 71G, 71B are not limited to LEDs as long as they can be used as point light sources.
The reflection mirror 72 has, for example, a paraboloid shape. The light emitting elements 71R, 71G, 71B are disposed at the focal point of the paraboloid. The light emitting elements 71 </ b> R, 71 </ b> G, 71 </ b> B are integrated with the reflection mirror 72 by the mold resin 73 while being positioned at the focal position of the reflection mirror 72.

The light source 135 collimates the light emitted from the light emitting elements 71R, 71G, 71B by the reflection mirror 72. For this reason, light having strong directivity is emitted in the direction of the optical axis of the reflection mirror 72 (the central axis of the paraboloid of revolution). The light emission surface 135 a of the light source 135 is a surface perpendicular to the optical axis of the reflection mirror 72. The light source 135 is disposed such that the light emitting surface 135a faces the light incident surface 110a of the first substrate 110 shown in FIG. Accordingly, the light source 135 emits light having strong directivity in a direction perpendicular to the light incident surface 110a of the first substrate 110.

Each display element of the liquid crystal display device 102 sequentially displays red, green, and blue images.
In accordance with the display timing of the image, the red light emitting element 71R, the green light emitting element 71G, and the blue light emitting element 71B provided in the light source 135 sequentially emit light. The amount of light incident on the first substrate 110 from the light source 135 (red light emitting element 71R, green light emitting element 71G, blue light emitting element 71B) is the brightness of the image of the display element illuminated by the light source 135 (from the outside). It is set according to the gradation value of the input video signal. For example, in a display element displaying a dark image, the amount of light emitted from the light source 135 is reduced. On the other hand, for a display element displaying a bright image, the amount of light emitted from the light source 135 is increased. Along with this, the video signal supplied to the display element is expanded according to the amount of light emitted from the light source 135. As a result, power consumption can be reduced and contrast can be improved as compared with a configuration in which the entire display region is always irradiated with the maximum amount of light.

[Sixth Embodiment]
FIG. 20 is a cross-sectional view parallel to the YZ plane of the liquid crystal display device (liquid crystal device) 103 of the sixth embodiment. In the liquid crystal display device 103, the same reference numerals are given to components common to the liquid crystal display device 101 of the fourth embodiment, and detailed description thereof will be omitted.

The liquid crystal display device 104 is different from the liquid crystal display device 101 of the fourth embodiment in that the color filter layer is omitted and light of different colors (for example, red light, green light, and blue light) is supplied to the light source 135. A plurality of light emitting elements that emit light are provided, and light of different colors is sequentially emitted from each light emitting element at different timings. In addition, an electric field corresponding to the gradation of the color image emitted from the light emitting elements is generated inside the liquid crystal layer 115 in accordance with the timing at which the plurality of light emitting elements emit light. The configuration of the light source 135 is the same as the configuration shown in FIG.

Each display element of the liquid crystal display device 104 sequentially displays red, green, and blue images.
In accordance with the display timing of the image, the red light emitting element 71R, the green light emitting element 71G, and the blue light emitting element 71B provided in the light source 135 sequentially emit light. The amount of light incident on the first substrate 110 from the light source 135 (red light emitting element 71R, green light emitting element 71G, blue light emitting element 71B) is the brightness of the image of the display element illuminated by the light source 135 (from the outside). It is set according to the gradation value of the input video signal. For example, in a display element displaying a dark image, the amount of light emitted from the light source 135 is reduced. On the other hand, for a display element displaying a bright image, the amount of light emitted from the light source 135 is increased. Along with this, the video signal supplied to the display element is expanded according to the amount of light emitted from the light source 135. As a result, power consumption can be reduced and contrast can be improved as compared with a configuration in which the entire display region is always irradiated with the maximum amount of light.

[Others]
In the above-described embodiment, the liquid crystal device mainly using the liquid crystal layer of the blue phase has been described, but the alignment mode of the liquid crystal layer is not limited to this. The refractive index or the birefringence of the first polarized light propagating through the light guide plate and incident obliquely (approximately in a direction perpendicular to the thickness direction of the liquid crystal layer) from the light guide plate to the liquid crystal layer is changed by an electric field. Any liquid crystal layer can be used. In all the embodiments described above, a liquid crystal layer using an alignment form other than the blue phase, such as the liquid crystal layer described in the first modification of the second embodiment, can also be used.

In the above-described embodiment, the pair of electrodes that generate an electric field inside the liquid crystal layer are arranged separately on the first substrate and the second substrate. This method is a liquid crystal device that generates an electric field in the thickness direction of the liquid crystal layer inside the liquid crystal layer, and is a so-called vertical electric field type liquid crystal device. However, the electric field is not necessarily generated in the thickness direction of the liquid crystal layer. For example, a so-called lateral electric field type liquid crystal device such as an IPS (In-Plane? Switching) method or an FFS (Fringe? Field? Switching) method may be used.

In the above-described embodiment, the first polarized light is P-polarized light, and the refractive index or the birefringence magnitude of the liquid crystal layer where the P-polarized light is refracted is controlled by the pair of electrodes. However, the first polarization is not limited to P polarization. Depending on the orientation of the liquid crystal layer and the direction in which the electric field is generated, there is a direction in which the refractive index and the magnitude of birefringence can easily be changed. Therefore, the polarized light along that direction may be used as the first polarized light.

In the above-described embodiment, the light guide plate having the light incident surface on the end surface, the light source that makes the light incident on the light incident surface of the light guide plate, the light diffusion plate arranged to face the light guide plate, the light guide plate and the light diffusion plate, A liquid crystal layer disposed between the liquid crystal layer and the refractive index or the birefringence of light incident on the liquid crystal layer obliquely from the light guide plate by generating an electric field inside the liquid crystal layer and propagating through the light guide plate. As an example of a liquid crystal device, a backlight unit and a liquid crystal display including a pair of electrodes that control the amount of light that travels obliquely through the liquid crystal layer and is diffused by the light diffusion plate and emitted by changing The apparatus has been described. However, the use of such a liquid crystal device is not limited to a backlight unit or a liquid crystal display device. It can be widely applied to other uses such as a lighting device used for indoor lighting. As an example, a case where a liquid crystal device is used as a lighting device will be described as a seventh embodiment.

[Seventh Embodiment]
In the first to sixth embodiments, the liquid crystal display device that displays an image has been described. In the seventh embodiment, a liquid crystal dimming device that is a surface light source that emits light to the outside will be described.

FIG. 21 is an exploded perspective view of the liquid crystal light control device (liquid crystal device) 1101 of the seventh embodiment. Components common to the liquid crystal display device 100 of the third embodiment in the liquid crystal light control device 1101 are assigned the same reference numerals, and detailed descriptions thereof are omitted.

The liquid crystal light control device 1101 includes a first substrate 110, a plurality of light sources 105, a second substrate 111, and a light diffusion plate 118. The light source 105 makes light incident on the end surface (light incident surface) 110 a of the first substrate 110. The second substrate 111 is disposed to face the first substrate 110. The light diffusion plate 118 is provided on the outer surface side of the second substrate 111.
A rectangular frame-shaped sealing material 119 is provided at the peripheral edge of the facing region where the first substrate 110 and the second substrate 111 face each other. Liquid crystal (not shown) is sealed in a space surrounded by the first substrate 110, the second substrate 111, and the sealing material 119.

FIG. 22 is a cross-sectional view parallel to the YZ plane of the liquid crystal light control device 1101 of the seventh embodiment. Components common to the liquid crystal display device 101 of the fourth embodiment in the liquid crystal light control device 1101 are denoted by the same reference numerals, and detailed description thereof is omitted.

The liquid crystal dimming device 1101 is different from the liquid crystal display device 101 of the fourth embodiment in that the color filter layer is omitted, and the light source 135 is provided with a plurality of light emitting elements that emit different amounts of white light. The point is that light of different amounts of light is emitted sequentially at different timings. In addition, an electric field corresponding to the gradation of the image of the color emitted from the light emitting elements is generated inside the liquid crystal layer 115 in accordance with the timing at which the plurality of light emitting elements emit light.

The light emitting elements PX11 to PX15 of the liquid crystal light control device 1101 sequentially emit white light having different light amounts.
And according to the timing of the light emission, each light emitting element provided in the light source 135 emits light sequentially. The amount of light incident on the first substrate 110 from the light source 135 is set according to the brightness of the light emitting elements PX11 to PX15 illuminated by the light source 135. For example, in a light emitting element that emits weak light, the amount of light emitted from the light source 135 is reduced. On the other hand, in the light emitting element emitting strong light, the amount of light emitted from the light source 135 is increased. Thereby, power consumption can be reduced as compared with a configuration in which the entire light emitting region is always irradiated with the maximum amount of light.

In the seventh embodiment, a light emitting diode that emits white light is used as the light source 135, but the present invention is not limited to this. For example, as described with reference to FIG. 19, as the light source 135, a light emitting element 71R that emits red light, a light emitting element 71G that emits green light, and a light emitting element 71B that emits blue light. It may be used.

In the seventh embodiment, as described with reference to FIG. 18, the polarizing layer 113 may be provided between the first substrate 110 and the light diffusion plate 118.

The present invention can be used in the field of edge light type liquid crystal devices.

DESCRIPTION OF SYMBOLS 3 ... Backlight unit (liquid crystal device), 5 ... Light source, 7 ... Backlight unit (liquid crystal device), 41 ... 1st board | substrate (light guide plate), 41a ... Light incident surface, 43 ... 1st electrode, 44 ... 2nd electrode, 45 ... Liquid crystal layer, 46 ... Optical layer, 47 ... Polarizing layer, 48 ... Light diffusing plate, 60 ... Polarized light Layer, 62 ... polarization conversion layer, 71R, 71G, 71B ... light emitting element, 100, 101, 102, 103 ... liquid crystal display device (liquid crystal device), 110 ... first substrate (light guide plate) 110a ... light incident surface, 112 ... polarizing layer, 113 ... polarizing layer, 115 ... liquid crystal layer, 116 ... optical layer, 118 ... light diffusion plate, 124 ... first. 1 electrode, 125 ... second electrode, 131 ... polarization conversion layer, 135 ... light source, Lp ... first polarization Ls ··· second polarization

Claims (11)

1. A light guide plate having a light incident surface on an end surface;
   A light source that makes light incident on a light incident surface of the light guide plate;
   A light diffusing plate disposed opposite to the light guide plate;
   A liquid crystal layer disposed between the light guide plate and the light diffusion plate;
   By generating an electric field inside the liquid crystal layer, propagating through the light guide plate, and changing the refractive index or birefringence of the light incident obliquely on the liquid crystal layer from the light guide plate, A pair of electrodes for controlling the amount of the light emitted obliquely through the liquid crystal layer and diffused by the light diffusion plate;
   A liquid crystal device comprising:
2. Between the liquid crystal layer and the light diffusion plate, an optical layer that reflects the first polarized light and transmits the second polarized light different from the first polarized light is provided,
   The pair of electrodes change the liquid crystal layer by changing the birefringence of the liquid crystal layer of the first polarized light propagating through the light guide plate and obliquely incident on the liquid crystal layer from the light guide plate. The liquid crystal device according to claim 1, wherein the polarization state of the first polarized light traveling obliquely in the layer is changed.
3. The liquid crystal device according to claim 2, wherein a polarizing layer that transmits the first polarized light is provided on an optical path of the light between the light guide plate and the light source.
4. The liquid crystal layer propagates through the light guide plate and totally reflects the second polarized light incident obliquely on the liquid crystal layer from the light guide plate.
   The second polarized light that has been totally reflected by the liquid crystal layer and propagated through the inside of the light guide plate is converted into the first polarized light on the end surface different from the light incident surface of the light guide plate and reflected to the inside of the light guide plate. The liquid crystal device according to claim 2, further comprising a polarization conversion layer.
5. The liquid crystal device according to claim 2, wherein a polarizing layer that transmits the second polarized light transmitted through the optical layer is provided between the light diffusion plate and the optical layer.
6. The pair of electrodes changes the refractive index of the liquid crystal layer of the first polarized light propagating through the light guide plate and obliquely incident on the liquid crystal layer from the light guide plate. Switching between a state in which the light is transmitted through the liquid crystal layer and emitted from the light diffusing plate, and a state in which the first polarized light is totally reflected by the liquid crystal layer and propagates in the light guide plate and is not emitted from the light diffusing plate. Item 2. A liquid crystal device according to item 1.
7. The liquid crystal layer totally reflects a second polarized light different from the first polarized light that propagates through the light guide plate and is obliquely incident on the liquid crystal layer;
   The second polarized light that has been totally reflected by the liquid crystal layer and propagated through the inside of the light guide plate is converted into the first polarized light on the end surface different from the light incident surface of the light guide plate and reflected to the inside of the light guide plate. The liquid crystal device according to claim 6, further comprising a polarization conversion layer.
8. The light source includes a plurality of light emitting elements that emit light of different colors,
   The plurality of light emitting elements sequentially emit light at different timings,
   2. The pair of electrodes according to claim 1, wherein an electric field corresponding to a gradation of an image of a color emitted from the light emitting element is generated inside the liquid crystal layer in accordance with a timing at which the plurality of light emitting elements emit light. Liquid crystal device.
9. 2. The liquid crystal device according to claim 1, wherein the pair of electrodes generate an electric field in a layer thickness direction of the liquid crystal layer.
10. The liquid crystal device according to claim 9, wherein the liquid crystal layer exhibits an isotropic phase in a state where an electric field is not applied without generating an electric field inside the liquid crystal layer.
11. The alignment state of the liquid crystal layer changes in a plane including a direction in which the light is incident on a light incident surface of the light guide plate and a normal direction of a surface of the light guide plate facing the light diffusion plate. 9. A liquid crystal device according to item 9.

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