Patent Publication Number: US-2021188175-A1

Title: Display device and mirror device

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
     This application is a continuation of PCT International Patent Application No. PCT/JP2019/031865 filed on Aug. 13, 2019 which designates the United States, incorporated herein by reference, and which claims the benefit of priority from Japanese Patent Application No. 2018-170074 filed on Sep. 11, 2018, incorporated herein by reference. 
    
    
     BACKGROUND 
     1. Technical Field 
     The present disclosure relates to a display device and a mirror device that are made into a reflection state in which incident light is reflected and a transmission state in which incident light is transmitted and an image is able to be displayed. 
     2. Description of the Related Art 
     Japanese Patent Application Laid-open Publication No. 2001-318374 (JP-A-2001-318374) describes a device capable of being switched into a display state in which an image is displayed and a mirror state (reflection state) in which a reflected image is provided. 
     In the display device in JP-A-2001-318374 has an active region capable of being switched into the display state in which an image is displayed and the mirror state (reflection state) in which a reflected image is provided. The display state and the mirror state have the same area. 
     An object of the present disclosure is to provide a display device and a mirror device in which an area in a mirror state is larger than an area in a display state. 
     SUMMARY 
     A display device according to an embodiment of the present disclosure includes a display panel, and a front panel overlapping with the display panel. The front panel has an active region capable of being switched into a display state in which an image is displayed and a reflection state in which a reflected image is provided and a frame region around the active region, and the frame region is a mirror surface when the active region is the display state and the reflection state. 
     A mirror device according to an embodiment of the present disclosure that is made into a reflection state in which incident light is reflected and a transmission state in which incident light is transmitted and an image is able to be displayed is disclosed. The mirror device includes a display device; and a shooting device shooting an image of a rear part of a vehicle. The display device includes a display panel, and a front panel overlapping with the display panel, the front panel has an active region capable of being switched into a display state in which an image is displayed and a reflection state in which a reflected image is provided and a frame region around the active region, and the frame region is a mirror surface when the active region is the display state and the reflection state. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a schematic plan view for explaining an active region of a display device according to the embodiment; 
         FIG. 2  is a perspective view illustrating an example of the configuration of the display device in the embodiment; 
         FIG. 3  is a plan view illustrating a second translucent electrode of the display device in the embodiment; 
         FIG. 4  is a plan view illustrating a first translucent electrode of the display device in the embodiment; 
         FIG. 5  is a cross-sectional view of the display device in the embodiment; 
         FIG. 6  is a cross-sectional view of the display device in the embodiment; 
         FIG. 7  is a descriptive view for schematically comparing a size of pixels of a display panel and a size of a drive electrode for explanation; 
         FIG. 8  is a block diagram for explaining the display device in the embodiment; 
         FIG. 9  is a schematic view for explaining a transmission state in which incident light is transmitted and a display state in which an image is able to be displayed; 
         FIG. 10  is a schematic view for explaining a reflection state in which the incident light is reflected; 
         FIG. 11  is a descriptive view for schematically explaining a relation between a transmission axis of a first polarizing member and a transmission axis of an optical sheet; and 
         FIG. 12  is a view illustrating a mounting state of a mirror device. 
     
    
    
     DETAILED DESCRIPTION 
     A mode for carrying out the present disclosure (embodiment) will be described in detail with reference to the drawings. Contents described in the following embodiment do not limit the present disclosure. Components described below include those that can be easily thought of by those skilled in the art and substantially the same components. Furthermore, the components described below can be combined as appropriate. The disclosure is merely an example, and appropriate modifications within the gist of the disclosure at which those skilled in the art can easily arrive are naturally encompassed in the range of the present disclosure. In the drawings, widths, thicknesses, shapes, and the like of the components can be schematically illustrated in comparison with actual modes for clearer explanation. They are however merely examples and do not limit interpretation of the present disclosure. In the present specification and the drawings, the same reference numerals denote components similar to those described before with reference to the drawing that has been already referred, and detail explanation thereof can be omitted as appropriate. 
       FIG. 1  is a schematic plan view for explaining an active region of a display device according to the embodiment. As illustrated in  FIG. 1 , the display device has an active region  10  capable of being switched into a display state in which an image is displayed and a mirror state (reflection state) in which a reflected image is provided and a frame region  10 F around the active region  10 . 
       FIG. 2  is a perspective view illustrating an example of the configuration of the display device in the embodiment. A display device  100  includes a first polarizing member  4 , a front panel  1 , an optical sheet  5 , a second polarizing member  31 , a display panel  2 , a third polarizing member  32 , and a backlight  3 . In  FIG. 2 , one direction of a plane of the display panel  2  is an X direction, a direction orthogonal to the X direction in the plane of the display panel  2  is a Y direction, and a direction orthogonal to an X-Y plane is a Z direction. A side of a display surface (or an upper surface) on which the display panel  2  displays an image when seen in the Z direction is referred to as a display surface side (or an upper surface side) and a side of a rear surface (or a lower surface) that is opposite to the display surface (or the upper surface) when seen in the Z direction is referred to as a rear surface side (or a lower surface side). 
     The third polarizing member  32  and the backlight  3  on the rear surface side of the display panel  2  overlap with the display panel  2  when seen in the Z direction. 
     The backlight  3  is an illumination device outputting light toward the display panel  2 . The backlight  3  has, for example, a light source and a light guiding plate, scatters light output from the light source by the light guiding plate, and outputs the light from an output surface facing the display panel  2 . 
     The first polarizing member  4 , the front panel  1 , the optical sheet  5 , and the second polarizing member  31  on the display surface side of the display panel  2  overlap, in this order, with the display panel  2  in the Z direction. As described above, the front panel  1  overlaps with the display panel  2 . 
       FIG. 3  is a plan view illustrating a second translucent electrode of the display device in the embodiment.  FIG. 4  is a plan view illustrating a first translucent electrode of the display device in the embodiment. A second translucent electrode  15  illustrated in  FIG. 3  is formed on a second substrate  12  and overlaps with the active region  10  illustrated in  FIG. 1 . As illustrated in  FIG. 3 , the second translucent electrode  15  is coupled to a drive circuit  17  mounted on a printed board  99  through a flexible printed circuits (FPC)  18 . 
     A first translucent electrode  14  illustrated in  FIG. 4  is formed on a first substrate  11  and overlaps with the active region  10  illustrated in  FIG. 1 . As illustrated in  FIG. 4 , the first translucent electrode  14  is electrically coupled to a conductive column  72 , which will be described later. 
       FIG. 5  is a cross-sectional view of the display device in the embodiment.  FIG. 5  is a view illustrating the display device  100  in the display state in which an image is displayed.  FIG. 6  is a cross-sectional view of the display device in the embodiment.  FIG. 6  is a view illustrating the display device  100  in the reflection state in which incident light is reflected. The cross sections in  FIG. 5  and  FIG. 6  are schematic cross sections cut along line V-V′ illustrated in  FIG. 3 . 
     As illustrated in  FIG. 5  and  FIG. 6 , the display panel  2  is a what-is-called liquid crystal display device. The display panel  2  includes a translucent substrate  21 , a translucent substrate  22 , and a liquid crystal layer  29  sealed by a sealing layer  23  between the substrate  21  and the substrate  22 . The display panel  2  is not limited to the liquid crystal display device and may be an electro-luminescence display device or the like. 
     The liquid crystal layer  29  modulates light passing through the liquid crystal layer  29  in accordance with a state of an electric field. For example, a transverse electric field mode such as fringe field switching (FFS) as one mode of in-plane switching (IPS) is used for the liquid crystal layer  29  in the embodiment. The liquid crystal layer  29  is not however limited thereto, and a longitudinal electric field mode may be used therefor. For example, liquid crystal of any of various modes such as twisted nematic (TN), vertical alignment (VA), and electrically controlled birefringence (ECB) may be used for the liquid crystal layer  29 . 
       FIG. 7  is a descriptive view for schematically comparing a size of pixels of the display panel and a size of a drive electrode for explanation. The display panel  2  displays an image. As illustrated in  FIG. 7 , the display panel  2  includes a large number of pixels Pix arranged in a two-dimensional array. Light output from the backlight  3  (see  FIG. 2 ) is incident on the display panel  2 . The display panel  2  displays an image by changing transmissivities of light incident on respective pixels Pix. 
     The display device  100  in the embodiment can be applied to both of a display device for monochrome display and a display device for color display. When the display device  100  for color display is employed, one pixel Pix (unit pixel) as a unit forming a color image includes a plurality of sub pixels. To be more specific, in the display device for color display, one pixel includes, for example, three sub pixels of a sub pixel displaying red (R), a sub pixel displaying green (G), and a sub pixel displaying blue (B). 
     One pixel is not limited to be configured by a combination of the sub pixels of three primary colors of RGB and can also be configured by adding one color or a plurality of colors of sub pixel(s) to the sub pixels of the three primary colors of RGB. To be more specific, one pixel can be configured by adding a sub pixel displaying white (W) for improving luminance and can also be configured by adding at least one sub pixel displaying a complementary color for enlarging a color reproduction range, for example. 
     A plurality of pixel electrodes  25  arranged in a matrix with a row-column configuration and a common electrode  24  are provided on the liquid crystal layer  29  side of the substrate  21  illustrated in  FIG. 5  and  FIG. 6 . The pixel electrodes  25  and the common electrode  24  are insulated from each other by an insulating film  26  and face each other in the Z direction perpendicular to the surface of the substrate  21 . The pixel electrodes  25  and the common electrode  24  are translucent electrodes made of a translucent conductive material (translucent conductive oxide) such as indium tin oxide (ITO). The substrate  21  is a translucent substrate made of glass, resin, or the like. An orientation film  83  is provided on the liquid crystal layer  29  side of the substrate  21 . The third polarizing member  32  is arranged on the side of the substrate  21  that is opposite to the liquid crystal layer  29 . 
     A color filter (not illustrated) and an orientation film  84  are provided on the liquid crystal layer  29  side of the substrate  22  illustrated in  FIG. 5  and  FIG. 6 . The color filter includes color regions colored with three colors of red (R), green (G), and blue (B), for example. The second polarizing member  31  is arranged on the side of the substrate  22  that is opposite to the liquid crystal layer  29 . 
     The display panel  2  includes a drive circuit  27  called a driver IC. The flexible printed circuits (FPC)  28  transmits a signal to the drive circuit  27  and drive power for driving the drive circuit  27 . 
     As illustrated in  FIG. 5  and  FIG. 6 , the front panel  1  includes the first substrate  11 , the second substrate  12 , and a liquid crystal layer  19  sealed by a sealing layer  13  between the first substrate  11  and the second substrate  12 . The first substrate  11  and the second substrate  12  are translucent substrates made of glass, resin, or the like. 
     The liquid crystal layer  19  modulates incident light passing through the liquid crystal layer  19  so as to change the polarization direction of the light in accordance with a state of an electric field. For example, the TN mode is used for the liquid crystal layer  19  in the embodiment. 
     The first translucent electrode  14  having a size that is larger than the entire region of the pixels Pix arranged in a matrix with the row-column configuration illustrated in  FIG. 7  is provided on the liquid crystal layer  19  side of the first substrate  11  illustrated in  FIG. 5  and  FIG. 6 . The second translucent electrode  15  having a size that is larger than the entire region of the pixels Pix arranged in a matrix with the row-column configuration illustrated in  FIG. 7  is provided on the liquid crystal layer  19  side of the second substrate  12 . 
     As illustrated in  FIG. 5  and  FIG. 6 , the first translucent electrode  14  is covered by a translucent insulating film  85  made of silicon nitride or the like. The second translucent electrode  15 , wiring  73 A, and a peripheral reflective portion  73 C are covered by a translucent insulating film  86  made of silicon nitride or the like. Although not illustrated in the drawings, wiring  73 B is also covered by the translucent insulating film  86  made of silicon nitride or the like. The insulating film  85  and the insulating film  86  can prevent short circuit between the second translucent electrode  15  and the first translucent electrode  14 . The insulating film  86  prevents the wiring  73 A, the wiring  73 B, and the peripheral reflective portion  73 C that are covered with the insulating film  86 , from corrosion. 
     The first substrate  11  causes liquid crystal orientation of the liquid crystal layer  19  making contact with an orientation film  81  to be one direction through the orientation film  81 . Similarly, the second substrate  12  causes liquid crystal orientation of the liquid crystal layer  19  making contact with an orientation film  82  to be a direction differing from the liquid crystal orientation of the orientation film making contact with the first substrate  11  through the orientation film  82 . 
     The first translucent electrode  14  and the second translucent electrode  15  face each other in the Z direction perpendicular to the surface of the first substrate  11 . The first translucent electrode  14  and the second translucent electrode  15  are made of a translucent conductive material (translucent conductive oxide) such as ITO. In the embodiment, the first translucent electrode  14  is a drive electrode that changes a state of the liquid crystal layer  19  with an electric field while a voltage to be supplied thereto is changed. The second translucent electrode  15  is a fixed potential electrode that keeps a fixed potential with a fixed voltage. 
     As illustrated in  FIG. 7 , the area of the active region  10  is the same as the area of the display region in which all the pixels Pix are arranged. 
     As illustrated in  FIG. 5 , the flexible printed circuits (FPC)  18  and the wiring  73 A on the second substrate  12  are electrically coupled to each other with a bonding pad  74 A. As illustrated in  FIG. 3 , the wiring  73 A is a part of a metal layer  73 . As illustrated in  FIG. 5 , the wiring  73 A couples a bonding pad  74  and the conductive column  72  that is electrically coupled to the first translucent electrode  14 . The drive circuit  17  transmits power of the first translucent electrode  14  to the front panel  1  through the FPC  18 , the wiring  73 A, and the conductive column  72 . 
     The metal layer  73  is made of aluminum, chromium, silver, or the like with metallic gloss. As illustrated in  FIG. 3 , the metal layer  73  has the wiring  73 A, the wiring  73 B, and the peripheral reflective portion  73 C. The metal layer  73  is patterned, so that the wiring  73 A, the wiring  73 B, and the peripheral reflective portion  73 C in the same layer are formed. A distance between the wiring  73 A and the wiring  73 B and a distance between the wiring  73 A and the peripheral reflective portion  73 C are 1 μm to 20 μm. Insulation is ensured by setting the distance between the wiring  73 A and the wiring  73 B and the distance between the wiring  73 A and the peripheral reflective portion  73 C to be equal to or more than 1 μm whereas slits are not easily viewed by setting the distances to be equal to or less than 20 μm. Although a distance between the wiring  73 B and the peripheral reflective portion  73 C is set to be 1 μm to 20 μm similarly in the embodiment, the wiring  73 B and the peripheral reflective portion  73 C may be electrically coupled to each other. 
     As illustrated in  FIG. 3 , the flexible printed circuits (FPC)  18  and the wiring  73 B on the second substrate  12  are electrically coupled to each other with a bonding pad  74 B. The wiring  73 B is electrically coupled to the second translucent electrode  15 . The drive circuit  17  transmits power of the second translucent electrode  15  to the front panel  1  through the FPC  18 . 
     The peripheral reflective portion  73 C is arranged into a C shape so as to surround the active region  10  and overlaps with the frame region  10 F illustrated in  FIG. 1 . The wiring  73 A, the wiring  73 B, and the peripheral reflective portion  73 C have metallic gloss and therefore look like mirror surfaces when seen from a viewer side. That is to say, the wiring  73 A, the wiring  73 B, and the peripheral reflective portion  73 C reflect light LL on the viewer side. For example, the wiring  73 A and the peripheral reflective portion  73 C reflect the light LL on the viewer side in  FIG. 5 . 
     A base material layer  64  made of a cycloolefin polymer is formed on the side of the second substrate  12  that is opposite to the liquid crystal layer  19 . The display surface side of the base material layer  64  is subjected to rubbing processing to have specific orientation. 
     The first polarizing member  4  is formed on the display surface side of the base material layer  64 . In other words, the first polarizing member  4  is formed on the surface of the second substrate  12  on the opposite side to the liquid crystal layer  19 . The first polarizing member  4  is a coating-type polarizing layer formed by mixing a liquid crystal material and a dichroic dye. The liquid crystal material is self-oriented along the specific orientation given to the base material layer  64 , so that the dichroic dye is also oriented to one direction. The first polarizing member  4  absorbs linearly polarized light in a second polarization direction orthogonal to a first polarization direction. 
     The optical sheet  5  transmits the linearly polarized light in the first polarization direction and reflects the linearly polarized light in the second polarization direction. The optical sheet  5  is also referred to as a reflective polarizing plate. 
       FIG. 8  is a block diagram for explaining the display device in the embodiment. The display device  100  in the embodiment is used as a room mirror in a vehicle in  FIG. 8 . A controller  9  is a computer including a central processing unit (CPU) as an arithmetic device and a memory as a storage device, for example. The controller  9  can also implement various functions by executing a computer program using these hardware resources. 
     To be specific, the controller  9  loads the computer program stored in a predetermined storage unit (not illustrated) on a memory and causes the CPU to execute instructions included in the computer program loaded on the memory. The controller  9  includes a mirror surface state determination unit  93  and an image controller  94  in the embodiment. The mirror surface state determination unit  93  and the image controller  94  are functions of the controller  9  that are implemented by executing the computer program using the hardware resources. 
     The image controller  94  controls lighting and extinction of the backlight  3  and the light amount and light intensity in lighting in accordance with an instruction execution result by the CPU. The image controller  94  transmits an image signal to be displayed on the display panel  2  to the drive circuit  27  through a flexible printed circuits  28  in accordance with the instruction execution result by the CPU, and the drive circuit  27  displays an image on the display panel  2 . The mirror surface state determination unit  93  controls the drive circuit  17  through the FPC  18  in accordance with an instruction signal of the display state on an input unit  202  to make a state in which the drive circuit  17  applies a voltage to the first translucent electrode  14 . The voltage to the first translucent electrode  14  thereby becomes equal to or higher than a threshold. Alternatively, the mirror surface state determination unit  93  controls the drive circuit  17  through the FPC  18  in accordance with an instruction signal of the reflection state on the input unit  202  to make a state in which the drive circuit  17  applies no voltage to the first translucent electrode  14 . The applied voltage to the first translucent electrode  14  thereby becomes lower than the threshold. 
     For example, the controller  9  is coupled to a shooting device  201  of a vehicle  200 , as illustrated in  FIG. 8 . The shooting device  201  shoots a rear part BD of the vehicle  200 , and an image of the rear part BD of the vehicle  200  is transmitted to the controller  9 . The display device  100  displays the image of the rear part BD of the vehicle  200  in the display state. A position at which the shooting device  201  is mounted on the vehicle may be a position enabling shooting of a front part FD of the vehicle  200  or a position enabling shooting of the surrounding of the vehicle  200 . 
       FIG. 9  is a schematic view for explaining a transmission state in which incident light is transmitted and the display state in which an image is able to be displayed. As illustrated in  FIG. 9 , the first polarizing member  4  absorbs linearly polarized light in a second polarization direction PA 2  orthogonal to a first polarization direction PA 1 . 
     The linearly polarized light in the first polarization direction PA 1  passes through the first polarizing member  4  and is incident on the front panel  1 . As illustrated in  FIG. 6 , the front panel  1  is in a state in which the drive circuit  17  applies a voltage to the first translucent electrode  14 . The front panel  1  thereby outputs the linearly polarized light in the first polarization direction PA 1  that has been incident from the first polarizing member  4  to the optical sheet  5  while keeping the linearly polarized light in the first polarization direction PA 1 . 
     When the display panel  2  displays an image, the first polarizing member  4 , the front panel  1 , and the optical sheet  5  are made into a state of opening a shutter for the linearly polarized light in the first polarization direction PA 1 , so that the image is easy to be viewed. 
     The linearly polarized light in the first polarization direction PA 1  that has been incident from the front panel  1  passes through the optical sheet  5 . The second polarizing member  31  transmits the linearly polarized light in the first polarization direction PA 1 . As described above, the image on the display panel  2  can be viewed from the display surface side of the first polarizing member  4 . 
     The display panel  2  outputs the image with the linearly polarized light in the first polarization direction PA 1  through the second polarizing member  31 . 
     The optical sheet  5  transmits the linearly polarized light in the first polarization direction PA 1  that has been incident from the display panel  2 . 
     The front panel  1  outputs the linearly polarized light in the first polarization direction PA 1  that has been incident from the optical sheet  5  to the first polarizing member  4  while keeping the linearly polarized light in the first polarization direction PA 1 . 
     The linearly polarized light in the first polarization direction PA 1  passes through the first polarizing member  4  and is output, as an image, to the display surface side of the first polarizing member  4 . 
     As described above, when the mirror surface state determination unit  93  illustrated in  FIG. 8  receives the instruction signal of the transmission state on the input unit  202 , the drive circuit  17  operates so as to make the transmission state in which the incident light is transmitted. The image controller  94  controls the backlight  3  and the display panel  2  to display an image on the display panel  2 . 
       FIG. 10  is a schematic view for explaining the reflection state in which the incident light is reflected. As illustrated in  FIG. 10 , the first polarizing member  4  absorbs the linearly polarized light in the second polarization direction PA 2  orthogonal to the first polarization direction PA 1 . 
     The linearly polarized light in the first polarization direction PA 1  passes through the first polarizing member  4  and is incident on the front panel  1 . As illustrated in  FIG. 5 , the front panel  1  is in a state in which the drive circuit  17  applies no voltage to the first translucent electrode  14 . The front panel  1  thereby converts the linearly polarized light in the first polarization direction PA 1  that has been incident from the first polarizing member  4  into the linearly polarized light in the second polarization direction PA 2  and outputs it to the optical sheet  5 . 
     The optical sheet  5  reflects the linearly polarized light in the second polarization direction PA 2  that has been incident from the front panel  1 . 
     The linearly polarized light in the second polarization direction PA 2  that has been reflected by the optical sheet  5  is incident on the front panel  1 . The front panel  1  converts the linearly polarized light in the second polarization direction PA 2  that has been incident from the optical sheet  5  into the linearly polarized light in the first polarization direction PA 1  and outputs it to the first polarizing member  4 . 
     The linearly polarized light in the first polarization direction PA 1  from the front panel  1  passes through the first polarizing member  4 , and an image on the display surface side of the first polarizing member  4  is displayed like a mirror surface when seen from the display surface side of the first polarizing member  4 . 
     Even when the display panel  2  displays an image, the first polarizing member  4 , the front panel  1 , and the optical sheet  5  are made into a state of closing the shutter for the linearly polarized light in the second polarization direction PA 2  provided by converting the linearly polarized light in the first polarization direction PA 1  that has been output from the display panel  2 . As a result, the image is not easily viewed. 
     To be specific, the display panel  2  outputs the image with the linearly polarized light in the first polarization direction PA 1  through the second polarizing member  31 . 
     The optical sheet  5  transmits the linearly polarized light in the first polarization direction PA 1  that has been incident from the display panel  2 . 
     The front panel  1  converts the linearly polarized light in the first polarization direction PA 1  that has been incident from the optical sheet  5  into the linearly polarized light in the second polarization direction PA 2  and outputs it to the first polarizing member  4 . 
     The first polarizing member  4  absorbs the linearly polarized light in the second polarization direction PA 2 , and the image is not easily viewed on the display surface side of the first polarizing member  4 . 
     As described above, when the mirror surface state determination unit  93  illustrated in  FIG. 8  receives the instruction signal of the reflection state on the input unit  202 , the drive circuit  17  operates so as to make the reflection state in which the incident light is reflected. In the reflection state, the image is not easily viewed even when the image is displayed on the display panel  2 . The image controller  94  therefore controls to display no image on the display panel  2  when the mirror surface state determination unit  93  illustrated in  FIG. 8  receives the instruction signal of the reflection state on the input unit  202 . 
     The first polarizing member  4  contains no iodine. Iodine has a property of absorbing a wavelength of visible light on the short wavelength side. When a polarizing plate causing general iodine to be adsorbed to a film of polyvinyl alcohol (PVA) and stretching in one direction to align orientations of molecules to a constant direction is used instead of the first polarizing member  4  to make the mirror state (reflection state) in which a reflected image is provided as illustrated in  FIG. 10 , there is the possibility that the wavelength of the reflected image on the short wavelength side is absorbed by iodine, whiteness has a greenish tint, and color shift occurs in a reflected image. Unlike this, in the display device  100  in the embodiment, the wavelength of the reflected image on the short wavelength side is not easily absorbed by the first polarizing member  4  in comparison with iodine, and the whiteness is close to neutral. 
     The polarizing plate causing general iodine to be adsorbed to the film of PVA and stretching in one direction to align the orientations of the molecules to a constant direction is used for the first polarizing member  4  instead of the above-mentioned coating-type polarizing plate to make the mirror state (reflection state) in which a reflected image is provided as illustrated in  FIG. 10 , there is the possibility that stretching of the polarizing plate deteriorates smoothness of the surface to cause unevenness in the reflected image. Unlike this, the display device  100  in the embodiment uses the first polarizing member  4  that does not stretch. The surface of the first polarizing member  4  therefore has smoothness to prevent unevenness in the reflected image. A material of the first polarizing member  4  can be selected in accordance with a desired polarizing degree and unevenness in the reflected image. Furthermore, the material of the polarizing plate can be made different for each region. 
       FIG. 11  is a descriptive view for schematically explaining a relation between a transmission axis of the first polarizing member and a transmission axis of the optical sheet.  FIG. 11  indicates a transmission axis direction PU 1  of the first polarizing member  4 , a rubbing direction PB 2  of the orientation film  82 , a rubbing direction PB 1  of the orientation film  81 , a transmission axis direction PU 2  of the optical sheet  5 , and a reflection axis direction PM of the optical sheet  5 . 
     As illustrated in  FIG. 11 , the rubbing direction PB 2  of the orientation film  82  and the rubbing direction PB 1  of the orientation film  81  intersect with each other when seen from above. The transmission axis direction PU 1  of the first polarizing member  4  and the transmission axis direction PU 2  of the optical sheet  5  are parallel with each other. The transmission axis direction PU 1  of the first polarizing member  4  and the reflection axis direction PM of the optical sheet  5  intersect with each other. The first polarizing member  4  and the optical sheet  5  transmit the linearly polarized light in the first polarization direction PA 1 . 
       FIG. 12  is a view illustrating a mounting state of a mirror device. In  FIG. 12 , the display device  100  in the embodiment is used as a room mirror arranged in an upper center portion of a window W. The mirror device is made into the reflection state in which incident light is reflected and the transmission state in which the incident light is transmitted and an image is able to be displayed. 
     When an applied voltage to the first translucent electrode  14  is lower than the threshold, the reflection state in which the incident light is reflected is made, and the display device  100  serves as a mirror that mirror-reflects the incident light from a rear part of the vehicle and enables the rear part of the vehicle to be viewed. The controller  9  illustrated in  FIG. 8  does not display an image of the rear part BD of the vehicle  200  on the display panel  2  in the reflection state. 
     The display panel  2  of the display device  100  displays an image of the rear part that has been shot by the shooting device  201  (see  FIG. 8 ) in the display state. Alternatively, the display panel  2  of the display device  100  may display an image around the vehicle that has been shot by a shooting device in the display state. 
     The display device  100  in the embodiment may be applied to a side mirror  101  of the vehicle. Although the side mirror  101  of the vehicle is arranged outside the vehicle, it may be arranged in the vehicle. 
     As described above, the display device  100  includes the display panel  2  and the front panel  1  overlapping with the display panel  2 . The display device  100  further includes the first polarizing member  4 , the optical sheet  5 , and the second polarizing member  31 . The first polarizing member  4  absorbs the linearly polarized light in the second polarization direction PA 2  orthogonal to the first polarization direction PA 1 . The optical sheet  5  reflects the linearly polarized light in the second polarization direction PA 2  and transmits the linearly polarized light in the first polarization direction PA 1 . The front panel  1  can convert the polarization direction of the incident light into another polarization direction in accordance with the applied voltage. The front panel  1  is arranged between the first polarizing member  4  and the optical sheet  5 . The display panel  2  overlaps with the front panel  1  in the Z direction through the second polarizing member  31  transmitting the linearly polarized light in the second polarization direction PA 2  with respect to the optical sheet  5 . The active region  10  can thereby be switched between the display state in which an image is displayed, which is illustrated in  FIG. 6  and  FIG. 9 , and the mirror state (reflection state) in which a reflected image is provided, which is illustrated in  FIG. 5  and  FIG. 10 . 
     The front panel  1  is located to be closer to an observer than the display panel  2 . The front panel  1  can be switched into a first front panel state of outputting the incident linearly polarized light in the first polarization direction PA 1  while keeping the linearly polarized light in the first polarization direction PA 1  and a second front panel state of converting the incident linearly polarized light in the first polarization direction PA 1  into the linearly polarized light in the second polarization direction PA 2  and outputting it in accordance with a state in which the drive circuit  17  applies a voltage to the first translucent electrode  14 . 
     The active region  10  is thereby made into the reflection state in the first front panel state whereas the active region  10  is made into the display state in the second front panel state. Power consumption in the reflection state is smaller than power consumption in the display state. In other words, when the applied voltage is lower than the threshold, the incident light is reflected in the display device  100 . As a result, the power consumption in the reflection state can be reduced in the display device  100 . 
     In the embodiment, the frame region  10 F around the active region  10  is a mirror surface. When the active region  10  is in the reflection state, the active region  10  and the frame region  10 F reflect light, and the area of the mirror surface therefore becomes larger than that in the active region  10 . 
     The metal layer  73  having metallic gloss is arranged in the frame region  10 F, and the frame region  10 F is the mirror surface when seen from the observer side. As illustrated in  FIG. 1 , in the display device  100  in the embodiment, when the active region  10  is made into the reflection state, the frame region  10 F is also in the reflection state, and the area of the mirror surface therefore seems to be increased. 
     In the display device  100  in the embodiment, when the active region  10  is made into the display state, the frame region  10 F is still in the reflection state, and an image is displayed in a region framed by the mirror surface with the frame region  10 F. 
     As described above, the front panel  1  includes the first substrate  11  and the second substrate  12  facing the first substrate  11  on the opposite side to the display panel  2 . The liquid crystal layer  19  is sealed between the first substrate  11  and the second substrate  12 . The first translucent electrode  14  is provided on the liquid crystal layer  19  side of the first substrate  11 . The second translucent electrode  15  is provided on the liquid crystal layer  19  side of the second substrate  12 . The metal layer  73  is provided on the second substrate  12 . The metal layer  73  is therefore closer to the observer than the sealing layer  13 , so that lowering of the reflectivity by the sealing layer  13  can be prevented. 
     Although the preferred embodiment of the present disclosure has been described above, the present disclosure is not limited by the embodiment. For example, the present disclosure is not limited to be applied to the mirror device used in the vehicle and can be applied also to a mirror such as a general full-length mirror. Although the boundary of the active region is linear, it is not particularly limited and may have a curved shape or a character shape formed by combining curves, or the like. Contents disclosed in the embodiment are merely examples, and various modifications can be made in a range without departing from the gist of the present disclosure. Appropriate modifications in a range without departing from the gist of the present disclosure naturally belong to the technical range of the present disclosure. For example, translucent optical resin or any of various films that does not inhibit actions provided by the aspect described in the embodiment may be provided between components of the first polarizing member  4 , the optical sheet  5 , the front panel  1 , the second polarizing member  31 , and the display panel  2  in the above-mentioned embodiment. The first polarizing member  4  may be the polarizing plate causing iodine to be adsorbed to the film of PVA and stretching in one direction to align the orientations of the molecules to the constant direction. In this case, the base material layer  64  is omitted, and the first polarizing member  4  is provided on the side of the second substrate  12  that is opposite to the liquid crystal layer  19 . 
     The following configuration may also be employed. That is, the drive circuit  17  applies a fixed voltage to the first translucent electrode  14 , and the first front panel state and the second front panel state as described above are switched in accordance with whether the drive circuit  17  applies the voltage to the first translucent electrode  14 . 
     Other operation and effect provided by the aspect described in the embodiment that are obvious from description of the present specification or at which those skilled in the art can arrive as appropriate should be interpreted to be provided by the present disclosure.