JP2019174706A - Liquid crystal display device - Google Patents

Abstract

To provide a liquid crystal display device capable of suppressing light leakage in the dark area of the image adjacent to the bright area.SOLUTION: A liquid crystal display device 10 has a liquid-crystal display panel 12 for displaying images. A light emitting part 20 illuminates the liquid-crystal display panel 12. A polymer dispersion type liquid crystal panel 22 disposed between the liquid-crystal display panel 12 and the light emitting part 20, which is capable of switching between the scattering state for scattering incident light from the light emitting part 20 and the non-scattering state that do not scatter the incident light.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a liquid crystal display device that displays an image.

  In a liquid crystal display device, local dimming is performed in which the luminance of each of a plurality of blocks of a backlight is controlled according to the image in order to improve the contrast of the image. In such a liquid crystal display device, when a bright part area exists in a part of the dark part area of the image, light from the backlight leaks into a part adjacent to the bright part area in the dark part area, and this part is visually recognized as slightly bright. There is a possibility. This is called a halo. In order to suppress halo, a display device is known in which the luminance of each block is spatially smoothed to reduce the difference in luminance between adjacent blocks (see, for example, Patent Document 1).

Japanese Patent Laying-Open No. 2015-176137

  Even if the luminance for each block is spatially smoothed, halos may not be sufficiently suppressed.

  The present invention has been made in view of such circumstances, and an object thereof is to provide a liquid crystal display device capable of suppressing light leakage in a portion adjacent to a bright portion region in a dark portion region of an image.

  In order to solve the above problems, a liquid crystal display device according to an aspect of the present invention is disposed between a liquid crystal display panel that displays an image, a light emitting unit that illuminates the liquid crystal display panel, and the liquid crystal display panel and the light emitting unit. A polymer-dispersed liquid crystal panel capable of switching between a scattering state in which incident light from the light emitting portion is scattered and a non-scattering state in which incident light is not scattered.

  ADVANTAGE OF THE INVENTION According to this invention, the light leak of the part adjacent to the bright part area | region in the dark part area | region of an image can be suppressed.

1 is a cross-sectional view schematically showing a liquid crystal display device according to a first embodiment. It is the top view which looked at the polymer dispersion type liquid crystal panel of the liquid crystal display device of FIG. 1 from the front side. FIG. 2 is a cross-sectional view showing the polymer dispersed liquid crystal panel of FIG. 1 in more detail. It is a block diagram of the liquid crystal display device of FIG. It is sectional drawing of the liquid crystal display device of a comparative example. It is a top view of one switching area | region of the polymer dispersion type liquid crystal panel which concerns on 2nd Embodiment. FIG. 7 is a plan view of the switching region of FIG. 6 in which some sub-regions are in a non-scattering state. It is a top view of one switching area | region of the polymer dispersion type liquid crystal panel which concerns on 3rd Embodiment. FIG. 9 is a plan view of the switching region of FIG. 8 in which some sub-regions are in a non-scattering state. It is a top view of one switching area | region of the polymer dispersion type liquid crystal panel which concerns on the modification of 3rd Embodiment. FIG. 11 is a plan view of the switching region of FIG. 10 in which some sub-regions are in a non-scattering state. It is a top view of one switching area | region of the polymer dispersion type liquid crystal panel which concerns on 4th Embodiment. FIG. 13 is a plan view of the switching region of FIG. 12 in which some sub-regions are in a non-scattering state. It is a figure which shows the relationship between the applied voltage and the light transmittance in the sub area | region of FIG. It is a figure which shows an example of the image which the input image data which concerns on 5th Embodiment represents. It is a figure which shows the scattering degree of each sub area | region of the switching area | region corresponding to the image of FIG. It is a figure which shows the other example of the image which the input image data which concerns on 5th Embodiment represents. It is a figure which shows the scattering degree of each sub area | region of the switching area | region corresponding to the image of FIG.

(First embodiment)
Before describing the first embodiment specifically, an outline will be described. The first embodiment relates to a liquid crystal display device that displays an image. In a liquid crystal display device, a liquid crystal display panel displays an image according to image data. The light emitting unit includes a plurality of light emitting regions that illuminate the liquid crystal display panel. The brightness of the plurality of light emitting areas is controlled based on the image data, and local dimming is performed. For example, the brightness of the light emitting area corresponding to the dark area in the image is controlled to the minimum brightness, and the contrast can be improved.

  The polymer-dispersed liquid crystal panel is disposed between the liquid crystal display panel and the light emitting unit, and can switch between a scattering state that scatters incident light from the light emitting unit and a non-scattering state that does not scatter incident light. Includes multiple switching areas. The switching region of the polymer dispersion type liquid crystal panel corresponding to the light emitting region other than the light emitting region having the minimum luminance is controlled to a non-scattering state. Thereby, the light from the light emitting regions other than the light emitting region having the minimum luminance is prevented from spreading and enters the liquid crystal display panel. Therefore, the amount of light traveling toward the dark area adjacent to the bright area can be suppressed.

  FIG. 1 is a cross-sectional view schematically showing a liquid crystal display device 10 according to the first embodiment. FIG. 2 is a plan view of the polymer dispersed liquid crystal panel 22 of the liquid crystal display device 10 of FIG. 1 viewed from the front side. FIG. 1 shows a state in which the liquid crystal display device 10 is disassembled. 1 is a cross-sectional view corresponding to the line AA of FIG.

  The liquid crystal display device 10 includes a liquid crystal display panel 12, a backlight 14, and a reflective polarizer 16. The backlight 14, the reflective polarizer 16, and the liquid crystal display panel 12 are laminated in order. In the following description, the stacking direction of the components of the liquid crystal display panel 12 is the front side, and the opposite is the back side.

  The liquid crystal display panel 12 includes a display surface 13 and a plurality of pixels P1 arranged in a matrix. The liquid crystal display panel 12 controls transmission or blocking of light from the backlight 14 for each pixel P1 and displays an image on the display surface 13. Although not shown, the liquid crystal display panel 12 includes a lower polarizing plate, a thin film transistor substrate, a color filter substrate, an upper polarizing plate, and the like. The liquid crystal display panel 12 is based on a known technique, and a detailed description thereof is omitted here.

  The backlight 14 is disposed so as to face the liquid crystal display panel 12 via the reflective polarizer 16. The backlight 14 functions as a light source that illuminates the liquid crystal display panel 12 in a planar shape from the back side via the reflective polarizer 16. The backlight 14 includes a light emitting unit 20, a polymer dispersed liquid crystal panel 22, and a prism sheet 24.

  The light emitting unit 20 includes a plurality of light emitting regions R1 that illuminate the liquid crystal display panel 12. The plurality of light emitting regions R1 are arranged in a matrix. The plurality of light emitting regions R1 are not necessarily arranged regularly, and may be irregularly arranged according to the shape of the liquid crystal display panel 12 or display contents. The number of light emitting regions R1 is not particularly limited. The luminance of each light emitting region R1 can be controlled. The three light emitting regions R1 shown in FIG. 1, that is, the three light emitting regions R1 along the line AA in FIG. 2, are also referred to as a light emitting region R1a, a light emitting region R1b, and a light emitting region R1c.

  The light emitting unit 20 includes a frame 30 and a plurality of light emitting sources 32. The frame 30 has a substantially box shape having an opening on the front side. In FIG. 2, the description of the frame 30 is omitted. The plurality of light emitting sources 32 are disposed on the front side of the frame 30. The light emitting sources 32 are disposed in each of the light emitting regions R1. The light emission source 32 is, for example, an LED (Light Emitting Diode).

  The polymer dispersed liquid crystal panel 22 is disposed on the front side of the light emitting unit 20. The polymer-dispersed liquid crystal panel 22 can switch between a scattering state in which incident light from the light emitting unit 20 is scattered and a non-scattering state in which incident light is not scattered. Specifically, the polymer dispersed liquid crystal panel 22 includes a plurality of switching regions R2 that can switch between a scattering state and a non-scattering state. In the non-scattering state switching region R2, the incident light is transmitted without being scattered, and thus is transparent. Therefore, the non-scattering state can also be called a transparent state. The switching region R2 and the light emitting region R1 are arranged in a one-to-one correspondence. The switching region R2 has the same shape and the same area as the light emitting region R1, and overlaps the corresponding light emitting region R1 in plan view. The three switching regions R2 shown in FIG. 1, that is, the three switching regions R2 along the line AA in FIG. 2, are also referred to as a switching region R2a, a switching region R2b, and a switching region R2c.

  The prism sheet 24 is disposed on the front side of the polymer dispersed liquid crystal panel 22, and the traveling direction of the light scattered by the polymer dispersed liquid crystal panel 22 or the light transmitted without being scattered is normal to the liquid crystal display panel 12. Bend to approach the direction nd.

  The reflective polarizer 16 is disposed between the liquid crystal display panel 12 and the backlight 14. The reflective polarizer 16 transmits the linearly polarized light component in one direction of the light emitted from the backlight 14 and reflects the linearly polarized light component in the other direction orthogonal to the one direction. The direction of the transmission axis of the reflective polarizer 16 is substantially parallel to the direction of the transmission axis of a lower polarizing plate (not shown) included in the liquid crystal display panel 12. The light reflected by the reflective polarizer 16 is returned to the backlight 14 and is reflected again by the surface of each layer constituting the backlight 14. The light reflected again on the surface of each layer is changed in polarization direction upon reflection, and returns to the reflective polarizer 16 again.

  FIG. 3 is a cross-sectional view showing the polymer dispersed liquid crystal panel 22 of FIG. 1 in more detail. The polymer dispersed liquid crystal panel 22 includes a first transparent substrate 40, a plurality of electrodes 42, a first alignment film 44, a polymer dispersed liquid crystal layer 46, a second alignment film 48, a common electrode 50, And a second transparent substrate 52.

  The 1st transparent substrate 40 is comprised with the material which has translucency. Examples of such a material include resins such as glass and polyethylene terephthalate (PET).

  The plurality of electrodes 42 are arranged in a matrix on the first transparent substrate 40. The electrode 42 is disposed in each of the switching regions R2. The electrode 42 is a transparent electrode formed of a translucent conductive member such as ITO (Indium Tin Oxide). Although not shown, scanning lines, signal lines, and thin film transistors for switching whether or not to apply a voltage to each electrode 42 are also arranged on the first transparent substrate 40. The first alignment film 44 is made of a light-transmitting material and is disposed on the plurality of electrodes 42.

  The polymer dispersed liquid crystal layer 46 is disposed on the first alignment film 44. The polymer dispersed liquid crystal layer 46 is, for example, a normal mode liquid crystal layer in which liquid crystals are dispersed in gaps between polymer networks formed in a mesh shape. The alignment of the liquid crystal is controlled by a voltage applied between the electrode 42 and the common electrode 50. In a state where a voltage is applied between the electrode 42 and the common electrode 50, the liquid crystal is aligned in one direction, the refractive indexes of the polymer and the liquid crystal coincide with each other, and the illumination light is scattered at the interface between the polymer and the liquid crystal. Does not occur. In a state where no voltage is applied between the electrode 42 and the common electrode 50, the liquid crystals are randomly oriented, the refractive indexes of the polymer and the liquid crystal are different from each other, and the scattering of illumination light is caused at the interface between the polymer and the liquid crystal. Arise. Each of the plurality of switching regions R2 is controlled to a non-scattering state when the first voltage is applied, and is controlled to a scattering state when a second voltage lower than the first voltage is applied. The second voltage is, for example, 0 V, and the state where the second voltage is applied includes a state where no voltage is applied. Here, when the polymer dispersed liquid crystal layer 46 is a normal mode liquid crystal layer, the first alignment film 44 and the second alignment film 48 are unnecessary. On the other hand, as will be described later, as the polymer dispersed liquid crystal layer 46, a reverse mode liquid crystal layer that is in a scattering state when a voltage is applied and is in a non-scattering state when no voltage is applied may be used. When a reverse mode liquid crystal layer is used as the polymer dispersion type liquid crystal layer 46, the polymer dispersion type liquid crystal panel 22 includes the first alignment film 44 and the second alignment film 48 as described above.

  The polymer-dispersed liquid crystal layer 46 is based on a known technique, and detailed description thereof is omitted here.

  The second alignment film 48 is made of a light-transmitting material and is disposed on the polymer dispersed liquid crystal layer 46. The common electrode 50 is disposed on the second alignment film 48. The common electrode 50 is also a transparent electrode formed by a translucent conductive member such as ITO. The second transparent substrate 52 is disposed on the common electrode 50.

  FIG. 4 is a block diagram of the liquid crystal display device 10 of FIG. The liquid crystal display device 10 includes a control unit 60 in addition to the configuration of FIG. Image data of an image displayed on the liquid crystal display panel 12 is input to the control unit 60. The controller 60 controls the voltage applied to each of the plurality of pixels P1 of the liquid crystal display panel 12 based on the image data. The control unit 60 controls the luminance of each of the plurality of light emitting regions R1 of the light emitting unit 20 of the backlight 14 based on the image data.

  The controller 60 controls each of the plurality of switching regions R2 of the polymer dispersed liquid crystal panel 22 to a scattering state or a non-scattering state based on the luminance of each light emitting region R1. Specifically, when there is a light emitting region R1 whose luminance is equal to or lower than a predetermined value, the control unit 60 controls the switching region R2 corresponding to the light emitting region R1 whose luminance is higher than the predetermined value to a non-scattering state, and the luminance is a predetermined value. The switching region R2 corresponding to the following light emitting region R1 is controlled to be in a scattering state. When there is no light emitting region R1 having a luminance equal to or lower than a predetermined value, the control unit 60 controls the switching region R2 corresponding to the light emitting region R1 having a luminance higher than the predetermined value in the scattering state. That is, the control unit 60 controls all the switching regions R2 to be in a scattering state when the luminances of all the light emitting regions R1 are higher than a predetermined value. The predetermined value can be appropriately determined by experiment or simulation.

  The control unit 60 includes an image feature amount calculation unit 62, an image delay unit 64, a calculation unit 66, an image correction unit 68, a luminance setting unit 70, and a scattering degree setting unit 72. The image feature amount calculation unit 62 divides input image data into a plurality of pixel units, for example, 5 × 5 pixel units, and calculates a feature amount for each pixel unit. As the feature amount, for example, a value representing the brightness of the image such as an average pixel value or a maximum pixel value can be used.

  The image delay unit 64 delays the image data in order to correct the image. The calculating unit 66 calculates the luminance of each light emitting region R1 of the light emitting unit 20 based on the feature amount calculated by the image feature amount calculating unit 62. The calculating unit 66 calculates the degree of scattering of each switching region R2 of the polymer dispersion type liquid crystal panel 22 based on the feature amount calculated by the image feature amount calculating unit 62. This corresponds to the calculation unit 66 calculating the degree of scattering of each switching region R2 based on the luminance of each light emitting region R1. Here, the calculation unit 66 calculates the degree of scattering corresponding to the scattering state and the degree of scattering corresponding to the non-scattering state.

  The calculation unit 66 calculates the luminance distribution of the backlight 14 based on the calculated luminance of each light emitting region R1 and the calculated degree of scattering of each switching region R2. The calculation unit 66 calculates a correction value for correcting the pixel value of each pixel P1 of the image according to the luminance distribution so that the peak luminance of the image is not changed by the light of the calculated luminance distribution.

  The image correction unit 68 multiplies the correction value of each pixel P1 calculated by the calculation unit 66 by the pixel value of the corresponding pixel P1 of the image data delayed by the image delay unit 64, and obtains the pixel of each pixel P1 obtained. The value is output to the liquid crystal display panel 12. In the liquid crystal display panel 12, a voltage corresponding to the pixel value is applied to each of the plurality of pixels P1, and the light transmittance of the pixel P1 is controlled according to the applied voltage.

  The luminance setting unit 70 sets a first control value so that the light emission source 32 emits light with the luminance of each light emitting region R1 calculated by the calculation unit 66, and outputs the set first control value to the backlight 14. .

  The scattering degree setting unit 72 sets the second control value so that the scattering degree of each switching region R2 calculated by the calculation unit 66 is obtained, and outputs the set second control value to the backlight. In the polymer dispersion type liquid crystal panel 22, a voltage corresponding to the second control value is applied to each switching region R2.

  Next, the operation and effect of the liquid crystal display device 10 will be described. In FIG. 1, as an example, the plurality of pixels P1 corresponding to the light emitting region R1a are controlled to the highest light transmittance, and the plurality of pixels P1 corresponding to the light emitting region R1b are controlled to the lowest light transmittance. Among the plurality of pixels P1 corresponding to the light emitting region R1c, some of the pixels P1 are controlled to have the highest light transmittance, and the other pixels P1 are controlled to have the lowest light transmittance. The pixel P1 having the highest light transmittance is, for example, a white display pixel, but is not particularly limited. The pixel P1 having the lowest light transmittance is a black display pixel. The plurality of pixels P1 having the highest light transmittance constitutes a bright area R10 of the image, and the plurality of pixels P1 having the lowest light transmittance constitutes a dark area R12 of the image.

  For example, the light emitting region R1a and the light emitting region R1c are controlled to the maximum luminance, and the light emitting region R1b is controlled to the minimum luminance. The light emission source of the light emitting region R1b does not emit light.

  In the polymer dispersion type liquid crystal panel 22, the switching region R2a and the switching region R2c are controlled to a non-scattering state, and the switching region R2b is controlled to a scattering state.

  The light emitted from the light source 32 in the light emitting region R1a is incident on the switching region R2a of the polymer dispersion type liquid crystal panel 22 from the back side, passes through the switching region R2a without being scattered, and is transmitted through the prism sheet 24, the reflective polarizer. 16. The pixel P1 having the highest light transmittance of the liquid crystal display panel 12 is transmitted and emitted to the front side as image light.

  Similarly, the light emitted from the light emitting source 32 in the light emitting region R1c is transmitted through the switching region R2c without being scattered, and the pixel P1 having the highest light transmittance of the prism sheet 24, the reflective polarizer 16, and the liquid crystal display panel 12. And is emitted to the front side as image light.

  FIG. 1 schematically shows light distribution characteristics. For example, the light emitted from the light emitting source 32 in the light emitting region R1a enters the liquid crystal display panel 12 without widening the light distribution characteristics. For the sake of clarity, the change in the light traveling direction on the prism sheet 24 is not represented in the light distribution characteristics.

  Since the light emitting source 32 in the light emitting region R1b does not emit light, there is no light from the light emitting source 32 toward the pixel P1 corresponding to the light emitting region R1b, and the contrast between the bright region R10 and the dark region R12 of the image is improved. it can.

  Here, a liquid crystal display device of a comparative example will be described. FIG. 5 is a cross-sectional view of a liquid crystal display device 10X of a comparative example. The comparative example is different from the liquid crystal display device 10 in that a scattering plate 100 is disposed instead of the polymer dispersed liquid crystal panel 22. Also in FIG. 5, the light transmittance of the pixel P1 and the luminance of the light emitting region R1 are the same as those of the liquid crystal display device 10.

  In the comparative example, the light emitted from the light emitting source 32 in the light emitting region R1a is scattered by the scattering plate 100 to widen the light distribution characteristics, and the highest light of the prism sheet 24, the reflective polarizer 16, and the liquid crystal display panel 12. The light passes through the pixel P1 having the transmittance and is emitted to the front side as image light.

  Therefore, in the comparative example, in the light incident on the liquid crystal display panel 12, the angle formed with the normal direction nd of the liquid crystal display panel 12 is relatively large, and the amount of light L1X directed toward the pixel P1 in the dark area R12 is relatively large. Since the light L1X has a relatively large amount of light, there is a possibility that the light L1X is visible to the observer through the pixel P1 in the dark area R12. That is, there is a possibility that light leaks to a portion adjacent to the bright portion region R10 in the dark portion region R12 and this portion is visually recognized slightly brightly.

  On the other hand, in the liquid crystal display device 10 of the present embodiment, the light emitted from the light emitting source 32 in the light emitting region R1a is incident on the liquid crystal display panel 12 without being scattered in the switching region R2a. Therefore, the light incident on the liquid crystal display panel 12 has a relatively large angle with the normal direction nd of the liquid crystal display panel 12, and the amount of light L1 directed to the pixel P1 in the dark region R12 is smaller than that in the comparative example. Such light L1 is unlikely to be viewed by an observer through the pixel P1 in the dark region R12. That is, it can suppress that the part adjacent to the bright part area | region R10 in the dark part area | region R12 is visually recognized a little brightly.

  Moreover, according to the brightness | luminance of light emission area | region R1, corresponding switching area | region R2 can be controlled to a non-scattering state or a scattering state. Since the second voltage such as the ground voltage is applied to the switching region R2 corresponding to the light emitting region R1 whose luminance is equal to or lower than the predetermined value, the switching region R2 to which the first voltage is applied can be reduced, and the power consumption can be reduced.

  In addition, when there is no light emitting region R1 having a luminance equal to or lower than a predetermined value, all the switching regions R2 are controlled to be in a scattering state. For example, in an image in which the dark region R12 does not exist, the viewing angle is widened by the scattered light. Can do.

  The controller 60 may control all the switching regions R2 of the polymer dispersed liquid crystal panel 22 to be in a non-scattering state when the light emitting region R1 having a luminance equal to or lower than a predetermined value exists. In this case, the power consumption increases as compared with the case where a part of the switching regions R2 is controlled to be in the scattering state, but the other effects described above can be obtained and the control can be simplified. Further, in this case, the polymer dispersed liquid crystal panel 22 is not divided into a plurality of switching regions R2, and the plurality of electrodes 42 are configured as an integrated electrode similar to the common electrode 50, so that the scattering state and the non-scattering state are entirely achieved. You may comprise so that a state can be switched. Thereby, the structure of the polymer-dispersed liquid crystal panel 22 can be simplified.

(Second Embodiment)
The second embodiment is different from the first embodiment in that each switching region R2 includes a plurality of sub-regions. Below, it demonstrates centering on difference with 1st Embodiment.

  FIG. 6 is a plan view of one switching region R2 of the polymer dispersion type liquid crystal panel 22 according to the second embodiment. FIG. 7 is a plan view of the switching region R2 of FIG. 6 in which some of the sub-regions R3 are in a non-scattering state. Each of the plurality of switching regions R2 includes a plurality of subregions R3 arranged in a matrix. The sub-region R3 and the pixel P1 are arranged in a one-to-one correspondence. Each of the plurality of sub-regions R3 can be switched between a scattering state and a non-scattering state. The sub-region R3 has the same shape and the same area as the pixel P1, and overlaps the corresponding pixel P1 in plan view. Although illustration is omitted, the electrode 42 is disposed in each of the sub-regions R3. In FIG. 6, all the sub-regions R3 are in a scattering state.

  As in the first embodiment, each of the plurality of sub-regions R3 is controlled to a non-scattering state when the first voltage is applied, and is controlled to a scattering state when the second voltage is applied. .

  When there is a pixel P1 to which a voltage lower than the predetermined voltage is present, the control unit 60 controls the sub-region R3 corresponding to the pixel P1 to which a voltage equal to or higher than the predetermined voltage is applied to a non-scattering state, and is lower than the predetermined voltage. The sub-region R3 corresponding to the pixel P1 to which the voltage is applied is controlled to be in a scattering state. In the liquid crystal display panel 12, the higher the voltage applied to the pixel P1, the higher the luminance of the pixel P1. The pixel P1 to which a voltage lower than the predetermined voltage is applied is a black display pixel. The pixel P1 to which a voltage equal to or higher than a predetermined voltage is applied is a pixel having a luminance higher than that of a black display pixel, and is a display pixel other than black. The predetermined voltage can be appropriately determined by experiment or simulation.

  When there is no pixel P1 to which a voltage lower than the predetermined voltage is applied, the control unit 60 controls the sub-region R3 corresponding to the pixel P1 to which a voltage equal to or higher than the predetermined voltage is applied in a scattering state. That is, when the voltage applied to each of all the pixels P1 is equal to or higher than the predetermined voltage, the control unit 60 controls all the sub-regions R3 to be in a scattering state.

  According to the present embodiment, the corresponding sub-region R3 can be controlled to the non-scattering state or the scattering state based on the applied voltage of the pixel P1. Since the second voltage such as the ground voltage is applied to the sub-region R3 corresponding to the pixel P1 to which a voltage equal to or higher than the predetermined voltage is applied, the region to which the first voltage is applied is compared with the first embodiment. Further reduction can reduce power consumption.

  Further, when there is no pixel P1 to which a voltage lower than the predetermined voltage is applied, all the sub-regions R3 are controlled to be in a scattering state. For example, in an image in which no dark region exists, the viewing angle is widened by the scattered light. be able to. The effect of the first embodiment can also be obtained.

(Third embodiment)
The third embodiment is different from the second embodiment in that a part of the sub-region R3 is maintained in a non-scattering state regardless of voltage application. Below, it demonstrates centering around difference with 2nd Embodiment.

  FIG. 8 is a plan view of one switching region R2 of the polymer dispersion type liquid crystal panel 22 according to the third embodiment. FIG. 9 is a plan view of the switching region R2 of FIG. 8 in which some of the sub-regions R3 are in a non-scattering state.

  Each of the plurality of sub-regions R3 includes a first region R30 that can be switched between a scattering state and a non-scattering state, and a second region R32 that is maintained in the non-scattering state. In the polymer dispersion type liquid crystal layer 46, the liquid crystal is dispersed in the gap between the polymer networks formed in the first region R30, but the liquid crystal exists in the gap between the polymer networks in the second region R32. do not do. Therefore, the second region R32 is substantially transparent regardless of whether a voltage is applied, and can also be referred to as a transparent region.

  The first region R30 is generally circular and is positioned approximately at the center of the sub-region R3. The areas of the plurality of first regions R30 are substantially equal to each other. The second region R32 is a portion other than the first region R30 in the sub-region R3.

  When the first region R30 is controlled to be in a scattering state, the sub-region R3 is assumed to be in a scattering state. When the first region R30 is controlled to be in a non-scattering state, the sub-region R3 is in a non-scattering state.

  FIG. 10 is a plan view of one switching region R2 of the polymer-dispersed liquid crystal panel 22 according to a modification of the third embodiment. FIG. 11 is a plan view of the switching region R2 of FIG. 10 in which some of the sub-regions R3 are in a non-scattering state. In this example, the second region R32 is generally circular and is positioned approximately at the center of the sub-region R3. The areas of the plurality of second regions R32 are substantially equal to each other. The first region R30 is a portion other than the second region R32 of the sub-region R3.

  The polymer-dispersed liquid crystal layer 46 used in the polymer-dispersed liquid crystal panel 22 can be produced as follows using a known photopolymerization phase separation method, for example. First, the laminated first transparent substrate 40, the electrode 42, and the first alignment film 44, and the laminated second transparent substrate 52, the common electrode 50, and the second alignment film 48 are arranged facing each other with a space therebetween. A mixture of liquid crystal and ultraviolet curable resin is injected between the first alignment film 44 and the second alignment film 48.

  Next, for example, a mask covering the second region R32 is arranged on the first transparent substrate 40, and ultraviolet light is irradiated through the mask. Thereby, the liquid crystal moves from the second region R32 to the first region R30 irradiated with ultraviolet light, and in this state, the ultraviolet curable resin in the first region R30 is cured. In the first region R30, a liquid crystal layer in which liquid crystal is dispersed in a gap between polymer networks is formed.

  Next, the mask is removed and ultraviolet light is irradiated. Thereby, the ultraviolet curable resin in the second region R32 is also cured. Since almost no liquid crystal remains in the second region R32, the second region R32 becomes transparent.

  Next, the operation and effect of the liquid crystal display device 10 will be described. As an example, a situation is assumed in which all the sub-regions R3 are controlled to be in a scattering state. The light traveling toward the transparent second region R32 above the light emission source 32 is not scattered and passes through the second region R32 to the front side. A part of the light traveling toward the first region R30 above the light source 32 is scattered by the first region R30 and emitted to the front side, and the rest is reflected to the back side.

  The light reflected to the back side is reflected by the surface on the front side of the frame 30 and reaches a position far from the light emitting source 32 in the same switching region R2. By transmitting this light through the second region R32 far from the light emitting source 32, the amount of light emitted to the front side at a position far from the light emitting source 32 in the switching region R2 as compared with the second embodiment. Can be more. Therefore, an in-plane distribution of brightness different from that of the second embodiment can be obtained. Compared with the second embodiment, the amount of light emitted from the sub-region R3 far from the light emission source 32 increases, so that the same can be achieved even when the distance between the light emission source 32 and the polymer dispersed liquid crystal panel 22 is made closer. In-plane distribution of luminance can be obtained. Therefore, the thickness of the liquid crystal display device 10 can be made thinner than that in the second embodiment. The effect of the second embodiment can also be obtained.

(Fourth embodiment)
The fourth embodiment differs from the third embodiment in that the areas of the first region R30 and the second region R32 in each sub-region R3 of one switching region R2 are not constant. Below, it demonstrates centering around difference with 3rd Embodiment.

  FIG. 12 is a plan view of one switching region R2 of the polymer dispersion type liquid crystal panel 22 according to the fourth embodiment. FIG. 13 is a plan view of the switching region R2 of FIG. 12 in which some of the sub-regions R3 are in a non-scattering state.

  The second region R32 is generally circular and is positioned approximately at the center of the sub-region R3. The first region R30 is a portion other than the second region R32 of the sub-region R3.

  For each of the plurality of switching regions R2, in plan view, the sub-region R3 farther from the light source 32 of the corresponding light-emitting region R1 has a smaller area of the first region R30 and a larger area of the second region R32. Become. That is, in plan view, the area of the first region R30 is smaller and the area of the second region R32 is larger as the subregion R3 is farther from the center of the switching region R2.

  In the illustrated example, the area of the second region R32 is the smallest in the sub-region R3 at the center of the switching region R2. In the outermost 16 sub-regions R3 of the switching region R2, the area of the second region R32 is the largest. In the eight sub-regions R3 surrounding the central sub-region R3 of the switching region R2, the area of the second region R32 is a size between the maximum and the minimum.

  Compared to the comparative example of the third embodiment, in the sub-region R3 that is close to the light source 32 and has a large amount of incident light, the area of the transparent second region R32 is small, and is reflected by the first region R30. The amount of light reaching the position far from the light emitting source 32 in the switching region R2 can be increased by increasing the amount of light. In the sub-region R3 that is far from the light emitting source 32 and has a small amount of incident light, the area of the transparent second region R32 is larger, so that the amount of light transmitted through the second region R32 can be increased. Compared with the modification of the third embodiment, the amount of light emitted from the sub-region R3 far from the light emitting source 32 is increased, so that the distance between the light emitting source 32 and the polymer dispersed liquid crystal panel 22 is made closer. Also, the same luminance in-plane distribution can be obtained. Therefore, the thickness of the liquid crystal display device 10 can be further reduced. The effect of the third embodiment can also be obtained.

(Fifth embodiment)
The fifth embodiment differs from the second embodiment in that a voltage corresponding to the voltage applied to the corresponding pixel P1 is applied to the sub-region R3. Below, it demonstrates centering around difference with 2nd Embodiment.

  FIG. 14 is a diagram showing the relationship between the applied voltage and the light transmittance in the sub-region R3 of FIG. The light transmittance increases as the applied voltage increases. That is, the degree of scattering decreases as the applied voltage increases. Thus, each of the plurality of sub-regions R3 scatters incident light with a degree of scattering corresponding to the applied voltage.

  The control unit 60 controls the voltage applied to the sub-region R3 that is controlled to the scattering state according to the voltage applied to the corresponding pixel P1. For example, the control unit 60 controls the voltage applied to the sub-region R3 controlled to the scattering state so that the voltage applied to the corresponding pixel P1 increases.

  FIG. 15 is a diagram illustrating an example of an image represented by input image data according to the fifth embodiment. This image is an image corresponding to one switching region R2. The image has gradation in luminance, and the luminance decreases as the distance from the center increases. The brightness at the center of the image is the highest, and the brightness at the four corners of the image is the lowest.

  FIG. 16 is a diagram illustrating the degree of scattering of each sub-region R3 of the switching region R2 corresponding to the image of FIG. The central sub-region R3 corresponding to the pixel P1 having the highest luminance is in a non-scattering state and has the lowest scattering degree. The sub-region R3 other than the central sub-region R3 is in a scattering state, and the sub-region far from the center has a higher degree of scattering. The four corner sub-region R3 corresponding to the pixel P1 having the lowest luminance has the highest degree of scattering.

  FIG. 17 is a diagram illustrating another example of an image represented by input image data according to the fifth embodiment. The image has gradation in luminance, and the luminance decreases as the distance from one vertex increases.

  FIG. 18 is a diagram illustrating the degree of scattering of each sub-region R3 of the switching region R2 corresponding to the image of FIG. The sub-region R3 corresponding to the pixel P1 with the highest luminance is in a non-scattering state and has the lowest scattering degree. The sub-region R3 other than the sub-region R3 is in a scattering state, and the degree of scattering increases as the sub-region R3 is distant from the non-scattering sub-region R3. The sub-region R3 corresponding to the pixel P1 having the lowest luminance has the highest scattering degree.

  According to the present embodiment, the degree of scattering of the sub-region R3 can be controlled more finely according to the luminance of the pixel P1. Therefore, when image data of an image having gradation in luminance is input, an image closer to the image represented by the image data can be displayed. The effect of the third embodiment can also be obtained.

  The present invention has been described based on the embodiments. This embodiment is an exemplification, and it will be understood by those skilled in the art that various modifications can be made to the respective constituent elements or combinations of the respective treatment processes, and such modifications are also within the scope of the present invention. By the way.

  For example, the third or fourth embodiment may be combined with the fifth embodiment. New embodiments resulting from the combination have the effects of the combined embodiments.

  In each embodiment, the polymer dispersed liquid crystal layer 46 may be a reverse mode liquid crystal layer that is in a scattering state when a voltage is applied and is in a non-scattering state when no voltage is applied. In this case, the effects of the embodiments except for the reduction in power consumption can be obtained. As the liquid crystal display panel 12, a liquid crystal display panel 12 having a luminance that decreases as the voltage applied to the pixel P1 increases may be used. In this case, in the second embodiment or the like, the control of the control unit 60 may be changed in accordance with this characteristic.

One embodiment of the present invention is as follows.
[Item 1]
A liquid crystal display panel for displaying images;
A light emitting unit for illuminating the liquid crystal display panel;
A polymer-dispersed liquid crystal disposed between the liquid crystal display panel and the light emitting unit and capable of switching between a scattering state in which incident light from the light emitting unit is scattered and a non-scattering state in which the incident light is not scattered. A panel,
A liquid crystal display device comprising:
According to this aspect, when an image including a bright area with high luminance and a dark area with low luminance is displayed on the liquid crystal display panel, the polymer dispersion type liquid crystal panel emits incident light from the light emitting section in a non-scattering state. By transmitting the light, the spread of light toward the liquid crystal display panel can be suppressed as compared with the scattering state. Therefore, the amount of light traveling toward the dark area adjacent to the bright area can be suppressed. Therefore, it can suppress that the part adjacent to the bright part area | region in a dark part area | region is visually recognized brightly.

[Item 2]
A control unit for controlling the brightness of each of the plurality of light emitting regions included in the light emitting unit based on the image data of the image;
The polymer-dispersed liquid crystal panel includes a plurality of switching regions each capable of switching between the scattering state and the non-scattering state,
The switching area and the light emitting area are arranged in a one-to-one correspondence,
The control unit controls a switching region corresponding to a light emitting region whose luminance is higher than the predetermined value to the non-scattering state when there is a light emitting region whose luminance is a predetermined value or less, and the light emitting region whose luminance is the predetermined value or less. The liquid crystal display device according to item 1, wherein a switching region corresponding to is controlled to the scattering state.
In this case, the corresponding switching region can be controlled to the non-scattering state or the scattering state according to the luminance of the light emitting region.

[Item 3]
Each of the plurality of switching regions is controlled to the non-scattering state when a first voltage is applied, and is controlled to the scattering state when a second voltage lower than the first voltage is applied. Item 3. A liquid crystal display device according to item 2.
In this case, power consumption can be reduced.

[Item 4]
The control unit controls the switching region corresponding to the light emitting region whose luminance is higher than the predetermined value to the scattering state when there is no light emitting region whose luminance is equal to or lower than the predetermined value. A liquid crystal display device according to 1.
In this case, the viewing angle can be widened by the scattered light.

[Item 5]
A controller for controlling a voltage applied to each of the plurality of pixels of the liquid crystal display panel based on the image data of the image;
The polymer dispersed liquid crystal panel includes a plurality of switching regions, and each of the plurality of switching regions includes a plurality of sub-regions,
The sub-region and the pixel are arranged in a one-to-one correspondence,
Each of the plurality of sub-regions can switch between the scattering state and the non-scattering state,
When there is a pixel to which a voltage lower than a predetermined voltage is applied, the control unit controls a sub-region corresponding to a pixel to which a voltage higher than the predetermined voltage is applied to the non-scattering state, and is lower than the predetermined voltage. Item 2. The liquid crystal display device according to item 1, wherein a sub-region corresponding to a pixel to which a voltage is applied is controlled to the scattering state.
In this case, the corresponding sub-region can be controlled to a non-scattering state or a scattering state based on the applied voltage of the pixel.

[Item 6]
Each of the plurality of sub-regions is controlled to the non-scattering state when a first voltage is applied, and is controlled to the scattering state when a second voltage lower than the first voltage is applied. Item 6. The liquid crystal display device according to Item 5, wherein
In this case, power consumption can be reduced.

[Item 7]
The control unit controls, when there is no pixel to which a voltage lower than the predetermined voltage is applied, a sub-region corresponding to a pixel to which a voltage higher than the predetermined voltage is applied to the scattering state. Item 7. The liquid crystal display device according to item 5 or 6.
In this case, the viewing angle can be widened by the scattered light.

[Item 8]
Each of the plurality of sub-regions includes a first region that can be switched between the scattering state and the non-scattering state, and a second region that is maintained in the non-scattering state. 8. A liquid crystal display device according to any one of 7 above.
In this case, the thickness of the liquid crystal display device can be reduced.

[Item 9]
The light emitting unit includes a plurality of light emitting regions, and a light emitting source disposed in each of the plurality of light emitting regions,
The switching area and the light emitting area are arranged in a one-to-one correspondence,
Regarding each of the plurality of switching regions, the area of the first region is smaller and the area of the second region is larger as the sub-region is farther from the light emitting source of the corresponding light emitting region in plan view. Item 9. The liquid crystal display device according to item 8, wherein
In this case, the liquid crystal display device can be made thinner.

[Item 10]
The control unit controls a voltage applied to the sub-region controlled to the scattering state according to a voltage applied to a corresponding pixel,
10. The liquid crystal display device according to any one of items 5 to 9, wherein each of the plurality of sub-regions scatters the incident light with a scattering degree corresponding to an applied voltage.
In this case, when image data of an image having gradation in brightness is input, an image closer to the image represented by the image data can be displayed.

P1, pixel, R1, R1a, R1b, R1c, light emitting region, R2, R2a, R2b, R2c, switching region, R3, sub-region, R30, first region, R32, second region, 10 ... liquid crystal display device, 12 DESCRIPTION OF SYMBOLS ... Liquid crystal display panel, 20 ... Light emission part, 22 ... Polymer dispersion type liquid crystal panel, 32 ... Light emission source, 60 ... Control part.

Claims (10)

A liquid crystal display panel for displaying images;
A light emitting unit for illuminating the liquid crystal display panel;
A polymer-dispersed liquid crystal disposed between the liquid crystal display panel and the light emitting unit and capable of switching between a scattering state in which incident light from the light emitting unit is scattered and a non-scattering state in which the incident light is not scattered. A panel,
A liquid crystal display device comprising: A control unit for controlling the brightness of each of the plurality of light emitting regions included in the light emitting unit based on the image data of the image;
The polymer-dispersed liquid crystal panel includes a plurality of switching regions each capable of switching between the scattering state and the non-scattering state,
The switching area and the light emitting area are arranged in a one-to-one correspondence,
The control unit controls a switching region corresponding to a light emitting region whose luminance is higher than the predetermined value to the non-scattering state when there is a light emitting region whose luminance is a predetermined value or less, and the light emitting region whose luminance is the predetermined value or less. The liquid crystal display device according to claim 1, wherein a switching region corresponding to is controlled to the scattering state.   Each of the plurality of switching regions is controlled to the non-scattering state when a first voltage is applied, and is controlled to the scattering state when a second voltage lower than the first voltage is applied. The liquid crystal display device according to claim 2.   3. The control unit according to claim 2, wherein when there is no light emitting region having a luminance equal to or lower than a predetermined value, the control unit controls the switching region corresponding to the light emitting region whose luminance is higher than the predetermined value to the scattering state. 3. A liquid crystal display device according to 3. A controller for controlling a voltage applied to each of the plurality of pixels of the liquid crystal display panel based on the image data of the image;
The polymer dispersed liquid crystal panel includes a plurality of switching regions, and each of the plurality of switching regions includes a plurality of sub-regions,
The sub-region and the pixel are arranged in a one-to-one correspondence,
Each of the plurality of sub-regions can switch between the scattering state and the non-scattering state,
When there is a pixel to which a voltage lower than a predetermined voltage is applied, the control unit controls a sub-region corresponding to a pixel to which a voltage higher than the predetermined voltage is applied to the non-scattering state, and is lower than the predetermined voltage. The liquid crystal display device according to claim 1, wherein a sub-region corresponding to a pixel to which a voltage is applied is controlled to the scattering state.   Each of the plurality of sub-regions is controlled to the non-scattering state when a first voltage is applied, and is controlled to the scattering state when a second voltage lower than the first voltage is applied. The liquid crystal display device according to claim 5.   The control unit controls, when there is no pixel to which a voltage lower than the predetermined voltage is applied, a sub-region corresponding to a pixel to which a voltage higher than the predetermined voltage is applied to the scattering state. The liquid crystal display device according to claim 5 or 6.   6. Each of the plurality of sub-regions includes a first region that can be switched between the scattering state and the non-scattering state, and a second region that is maintained in the non-scattering state. 8. A liquid crystal display device according to any one of 7 to 7. The light emitting unit includes a plurality of light emitting regions, and a light emitting source disposed in each of the plurality of light emitting regions,
The switching area and the light emitting area are arranged in a one-to-one correspondence,
Regarding each of the plurality of switching regions, the area of the first region is smaller and the area of the second region is larger as the sub-region is farther from the light emitting source of the corresponding light emitting region in plan view. The liquid crystal display device according to claim 8. The control unit controls a voltage applied to the sub-region controlled to the scattering state according to a voltage applied to a corresponding pixel,
10. The liquid crystal display device according to claim 5, wherein each of the plurality of sub-regions scatters the incident light with a degree of scattering corresponding to an applied voltage.