JP2019078886A - Reflection adjusting element and reflection adjusting system including the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a reflection adjusting element and a reflection adjusting system capable of adjusting the reflection of external light incident on a reflecting surface of a reflecting object and the transmission of light emitted from the reflecting surface of the reflecting object. SOLUTION: A reflection adjusting element 30 generates an electric field in a liquid crystal layer 8 containing a dichroic dye and a liquid crystal molecule and an applied voltage to change the direction of the liquid crystal molecule and the dichroic dye. A liquid crystal cell 32 having 11 and 16 and a 1/4 wavelength plate 31 laminated on the liquid crystal cell 32 are provided, and the liquid crystal cell 32 is 1/4 depending on the orientation of the liquid crystal molecule and the dichroic dye. Unpolarized mode M that emits unpolarized light incident from the side opposite to the wavelength plate 31 side to the 1/4 wavelength plate 31 side in the unpolarized state, and from the side opposite to the 1/4 wavelength plate 31 side. It is characterized in that the incident unpolarized light can be switched to a polarization mode in which the incident light is emitted to the 1/4 wavelength plate side in a linearly polarized state. [Selection diagram] Fig. 1

Description

  The present invention relates to a reflection adjusting element and a reflection adjusting system including the same.

  Conventionally, for example, a method of suppressing reflection of extraneous light by using an antireflective film or the like has been proposed (Patent Document 1). Such an antireflective film is attached to the image display surface of an image display apparatus such as organic electroluminescence (OLED), for example, to suppress the reflection of external light.

  Here, a circularly polarizing plate in which a linear polarizing plate and a 1⁄4 wavelength plate are laminated is mainly used as a conventional antireflection film. The circularly polarizing plate converts light directed to the image display surface of the image display device into first linearly polarized light by the linear polarizing plate, and converts it into first circularly polarized light by the subsequent quarter-wave plate. The first circularly polarized light is reflected by the image display surface of the image display device to be second circularly polarized light whose rotational direction is reversed. The second circularly polarized light re-enters the quarter wave plate and is converted to a second linearly polarized light orthogonal to the first linearly polarized light. Then, the second linearly polarized light is blocked by the subsequent linear polarizer, and as a result, the light reflected on the image display surface is suppressed. Thereby, when the extraneous light is incident, the reflected light on the image display surface can be suppressed.

JP, 2006-268007, A

However, a circularly polarizing plate configured by laminating a linear polarizing plate and a quarter-wave plate is, for example, light (circularly polarizing plate) emitted from an image display surface (reflection surface) of an image display device (reflection target) The image display surface of the image display device is circularly polarized because the linear polarizer absorbs at least half of the second circularly polarized light incident and reflected and the image light emitted from the image display device). When observed through the plate, the brightness may decrease.
Therefore, even when there is very little incidence of extraneous light and it is not necessary to suppress the reflected light, the brightness of the emitted light also decreases from the image display surface of the image display device, and the image displayed on the image display surface is There was a case where it became unclear.

  The present invention provides a reflection adjusting element and a reflection adjusting system capable of adjusting the reflection of extraneous light incident on the reflecting surface of the reflecting object and the transmission of light emitted from the reflecting surface of the reflecting object.

  Specifically, the present invention provides the following.

(1) A liquid crystal cell having a liquid crystal layer containing a dichroic dye and liquid crystal molecules, and an electrode for generating an electric field in the liquid crystal layer by an applied voltage to change the direction of the liquid crystal molecules and the dichroic dye.
And a quarter wave plate stacked on the liquid crystal cell,
The liquid crystal cell is
Depending on the orientation of the liquid crystal molecules and the dichroic dye:
A non-polarization mode in which non-polarization light incident from the side opposite to the quarter-wave plate side is emitted to the quarter-wave plate side in the non-polarization state;
It is possible to switch the light in the non-polarization state, which is incident from the side opposite to the quarter-wave plate side, to the polarization mode in which the light is emitted to the quarter-wave plate side in the linear polarization state;
Reflection adjustment element characterized by

(2) The reflection adjustment element of (1),
A control unit that controls a voltage applied to the electrode;
The control unit changes the voltage applied to the electrode, and the reflection adjustment element can be switched to the non-polarization mode or the polarization mode.
Reflection adjustment system characterized by

(3) In (2),
A photometry unit disposed on the liquid crystal cell side of the reflection adjustment element;
The control unit is capable of switching the reflection adjustment element to the polarization mode or the non-polarization mode based on a photometric result by the photometry unit;
Reflection adjustment system characterized by

(4) In (3),
The image display apparatus includes an image display surface which is disposed on the quarter wavelength plate side of the reflection adjusting element and whose luminance can be changed.
The control unit changes the brightness of the image display surface according to a photometric result by the photometric unit.
Reflection adjustment system characterized by

(5) In any of (2) to (4),
A reflection reducing layer is disposed on the reflection adjusting element to reduce reflection;
Reflection adjustment system characterized by

(6) In any of (2) to (5),
In the liquid crystal layer, the transmittance when no electric field is generated is higher than the transmittance when an electric field is generated;
Reflection adjustment system characterized by

  It is possible to adjust the reflection of extraneous light incident on the reflection surface of the reflection target and the transmission of light emitted from the reflection surface of the reflection target.

It is a figure explaining reflection adjustment system 100 containing reflection adjustment element 30 of a 1st embodiment. FIG. 6 is a cross-sectional view illustrating the configuration of a liquid crystal cell 32. It is a figure explaining polarization mode H of reflection adjustment element 30 of a 1st embodiment. It is the table | surface which showed an example of the reflectance in the polarization mode H shown in FIG. 3, the 1st comparison form shown in FIG. 5, and the non-polarization mode M shown in FIG. 6, and the transmittance | permeability. It is a figure explaining 30 A of circularly-polarizing plates of a 1st comparative form. It is a figure explaining non-polarization mode M of reflection adjustment element 30 of a 1st embodiment. It is a figure explaining the 2nd comparative form by which transparent film 32B is arranged at the optical path. It is a graph explaining the switching operation | movement with non-polarization mode M of the reflection adjustment element 30 in the control part 60 of 1st Embodiment, and the polarization mode H. FIG. It is a flowchart which shows operation | movement of the control part 60 of 1st Embodiment. It is a figure which shows the reflection adjustment system of 2nd Embodiment, and is a figure explaining the reflectance in case the reflection adjustment element 30 is polarization mode H. FIG. It is a figure which shows the reflection adjustment system of 2nd Embodiment, and is a figure explaining the reflectance in case the reflection adjustment element 30 is non-polarization mode M. FIG. It is a figure explaining the comparison form (3rd comparison form) of a 2nd embodiment. It is a figure explaining the other comparison form (4th comparison form) of 2nd Embodiment. It is a figure which shows the reflection adjustment system of 3rd Embodiment, and is a figure explaining the reflectance in case the reflection adjustment element 30 is polarization mode H. FIG. It is a figure which shows the reflection adjustment system of 3rd Embodiment, and is a figure explaining the reflectance in case the reflection adjustment element 30 is non-polarization mode M. FIG. It is a figure explaining the comparison form (5th comparison form) of 3rd Embodiment.

(Image display device)
FIG. 1 is a diagram for explaining a reflection adjusting system 100 including a reflection adjusting element 30 according to a first embodiment of the present invention.
The reflection adjustment system 100 performs photometry to measure the external light illuminance near the surface 30 a of the image display device 20, the film-like reflection adjustment element 30 disposed on the image display surface 20 a of the image display device 20, and the reflection adjustment element 30. And a control unit 60 that controls the image display device 20, the reflection adjustment element 30, and the photometry unit 50.

(Image display device)
The image display device 20 is a display device using an organic light emitting diode (OLED), which is an image display panel of a self light emitting element.

(Reflection adjustment element)
The reflection adjustment element 30 is a member that adjusts the amount of reflection of external light incident on the image display surface 20 a of the image display device 20. The reflection adjustment element 30 has a quarter wavelength plate 31 and a liquid crystal cell 32 stacked, and the surface on the quarter wavelength plate 31 side is attached to the image display surface 20 a of the image display device 20.
The reflection adjustment element 30 is attached to the image display surface 20 a of the image display device 20 by an adhesive layer 14 using, for example, a PSA (Pressure Sensitive Adhesive) adhesive. In addition, in place of the adhesive layer made of the PSA adhesive, another adhesive or adhesive may be used. As another pressure-sensitive adhesive and adhesive, for example, an ultraviolet curable resin, a thermosetting resin, and the like can be used.

(1/4 wave plate)
The 1⁄4 wavelength plate 31 is an element that gives a phase difference of 1⁄4 wavelength to transmitted light and converts linearly polarized light into circularly polarized light. In the quarter wave plate 31 of the present embodiment, an alignment layer for quarter wave plate and a retardation layer for quarter wave plate are laminated on a transparent base material.
The 1⁄4 wavelength plate alignment layer is formed of a photo alignment layer that performs photo alignment. Similar to the alignment layers 13 and 17 provided in the liquid crystal cell 32 described later, various materials to which the method of optical alignment can be applied may be widely applied as the photoalignment material applicable to the alignment layer performing the optical alignment. For example, photolysis type, photodimerization type, photoisomerization type etc. can be mentioned. In the present embodiment, similarly to the orientation layers 13 and 17 described later, a light dimerization type material is used.
The retardation layer for a quarter wave plate is formed of a rod-like liquid crystal material solidified (hardened) in a state of retaining refractive index anisotropy, and the alignment of this liquid crystal material is formed into an alignment film shape for a quarter wave plate It is patterned by the orientation control force of.
As the transparent substrate, the same substrates as the substrates 6 and 15 used for the liquid crystal cell 32 described later can be used.
The quarter wavelength plate 31 is integrated with the liquid crystal cell 32 by the adhesive layer 18 using the above-described PSA adhesive.

The quarter-wave plate 31 is not limited to the above-described type using the polymerizable liquid crystal, and may be a retardation film produced by stretching a film, for example, a COP (cycloolefin polymer). Other methods, such as retardation film manufactured by this method, can also be used.
In addition, the quarter wave plate 31 forms the alignment film shape for the quarter wave plate by forming the fine concavo-convex shape instead of the photo alignment layer as a quarter wave plate alignment layer. It is also possible to use a forming resin layer, a rubbing alignment layer in which an alignment film shape for a 1⁄4 wavelength plate is formed by rubbing processing, or the like.
For example, an ultraviolet curable resin is applied to the forming resin layer. In addition, about this ultraviolet curable resin, the various resin used for a forming process, such as an acryl type, can be widely applied, for example.
Furthermore, in addition to the quarter wavelength plate 31, the reflection adjustment element 30 may include a half wavelength plate. By including a half-wave plate, it is possible to broaden the band that can give uniform retardation to light in a wider wavelength range.

(Liquid crystal cell)
FIG. 2 is a cross-sectional view for explaining the configuration of the liquid crystal cell 32. As shown in FIG.
The liquid crystal cell 32 is a member that changes the amount of transmitted light by changing the electric field of the liquid crystal layer 8 described later, and in the present embodiment, is a liquid crystal cell 32 based on a guest host system.
The liquid crystal cell 32 is configured by sandwiching the liquid crystal layer 8 by the film-like lower laminate 5D and the upper laminate 5U.

(Lower stack, upper stack)
The lower laminate 5D is formed by laminating the transparent electrode 11, the alignment layer 13 and the spacer 12 on the base material 6.
The upper laminate 5U is formed by laminating the transparent electrode 16 and the alignment layer 17 on the base material 15.

(Base material)
Although various transparent resin films can be applied to the substrates 6 and 15, a transparent resin film having a small optical anisotropy and having a transmittance of 80% or more at a visible wavelength (380 to 800 nm) It is desirable to apply
Examples of the material of the transparent resin film include acetyl cellulose-based resins such as triacetyl cellulose (TAC), polyester-based resins such as polyethylene terephthalate (PET) and polyethylene naphthalate (PEN), polyethylene (PE), polypropylene (PP) Polyolefin resins such as polystyrene, polymethylpentene and EVA, vinyl resins such as polyvinyl chloride and polyvinylidene chloride, acrylic resins, polyurethane resins, polysulfone (PEF), polyether sulfone (PES), polycarbonate Mention may be made of resins such as PC), polysulfone, polyether (PE), polyether ketone (PEK), (meth) acronitrile, cycloolefin polymer (COP), cycloolefin copolymer and the like.
In particular, since it is desirable that the substrate located on the quarter wavelength plate 31 side has a low phase difference (a phase difference of 10 nm or less), polycarbonate (PC) or cycloolefin polymer (COP) having a low phase difference is preferable. Resins such as triacetyl cellulose (TAC) and acrylic are preferred. In addition, temporarily, when using the base material larger than the said phase difference (10 nm) as a base material located in the quarter wavelength plate 31 side, with respect to the orientation direction (absorption axis direction) of the dichroic dye of a liquid crystal cell. Therefore, it is necessary to arrange the slow axis directions of the substrate at right angles or in parallel.
In the present embodiment, a polycarbonate film with a thickness of 100 μm is applied to the substrates 6 and 15, but transparent resin films with various thicknesses can be applied.
In addition, although the transparent resin film is used in this embodiment, the base materials 6 and 15 may be not only this but glass.

(Transparent electrode)
The transparent electrodes 11 and 16 are comprised from the transparent conductive film laminated | stacked on the said transparent resin film.
As the transparent conductive film, various transparent electrode materials applied to this kind of transparent resin film can be applied, and a transparent metal thin film having an oxide-based total light transmittance of 50% or more can be mentioned. . For example, tin oxide type, indium oxide type and zinc oxide type can be mentioned.

Examples of tin oxide (SnO ₂ ) include nesa (tin oxide SnO ₂ ), ATO (Antimony Tin Oxide: antimony-doped tin oxide), and fluorine-doped tin oxide.
Examples of indium oxide (In ₂ O ₃ ) -based materials include indium oxide, ITO (Indium Tin Oxide: Indium Tin Oxide), and IZO (Indium Zinc Oxide).
Examples of zinc oxide (ZnO) -based include zinc oxide, AZO (aluminum-doped zinc oxide), and gallium-doped zinc oxide.
In the present embodiment, a transparent conductive film is formed of ITO (Indium Tin Oxide).

(Spacer)
In the present embodiment, a spherical bead spacer 12 is used as the spacer. The bead spacer 12 is provided to define the thickness (cell gap) of the portion of the liquid crystal layer 8 excluding the outer peripheral portion. The bead spacer 12 can be widely applied to a configuration of an inorganic material such as silica, a configuration of an organic material, a configuration of a core-shell structure combining these, and the like. Further, in addition to the configuration of the spherical shape, it may be configured of a rod shape of a cylindrical shape, a prismatic shape or the like.
However, the member for defining the thickness of the liquid crystal layer 8 is not limited to the bead spacer 12. For example, a photoresist may be coated on the side of the substrate 15 and exposed and developed to form a cylindrical shape.
In the above description, the spacer is provided in the lower laminate 5D, but the present invention is not limited to this. Both the upper laminate 5U and the lower laminate 5D, or the upper laminate are described. It may be provided only in the body 5U.

(Alignment layer)
The alignment layers 13 and 17 are subjected to a photoalignment process. As the photoalignment material applicable to the alignment layer for performing photoalignment, various materials to which the method of photoalignment can be applied can be widely applied. For example, photolysis type, photodimerization type, photoisomerization type, etc. It can be mentioned.
In the present embodiment, a light dimerization type material is used. Examples of the photo-dimerization type material include cinnamate, coumarin, benzylidene phthalimidine, benzylidene acetophenone, diphenyl acetylene, stilbazole, uracil, quinolinone, maleimide, or a polymer having a cinnamylidene acetic acid derivative. Among them, a polymer having one or both of cinnamate and coumarin is preferably used in that it has a good alignment control force. As specific examples of such photo-dimerization type materials, for example, compounds described in JP-A-9-118717, JP-A-10-506420, JP-A-2003-505561 and WO2010 / 150748 are disclosed. Can be mentioned.
In addition, it may replace with a photo alignment layer, an alignment layer may be produced by a rubbing process, and a fine line-shaped uneven | corrugated shape may be formed and processed to produce an alignment layer.

The alignment layer is not limited to the vertical alignment layer which vertically aligns the liquid crystal, but may be a horizontal alignment layer which horizontally aligns the liquid crystal.
In the case of the vertical alignment layer, a negative liquid crystal having negative dielectric anisotropy in which the liquid crystal falls (horizontal alignment) when a potential difference is applied between two pairs of transparent electrodes is used. In the case of the horizontal alignment layer, the liquid crystal is a positive type liquid crystal having positive dielectric anisotropy, in which the liquid crystal stands (is vertically aligned) when a potential difference is applied between two pairs of transparent electrodes.

In the present embodiment, the mode in which the optical alignment process or the rubbing process is performed on the alignment layers 13 and 17 is described, but the present invention is not limited thereto. The optical alignment process or the rubbing process is performed on the alignment layers 13 and 17 It may be the composition which does not do.
When the optical alignment processing or rubbing processing is not performed on the alignment layers 13 and 17, for example, when the liquid crystal cell 32 is formed, the inflow direction of liquid crystal molecules into the inside surrounded by a sealing material 19 described later is made constant. Thereby, a liquid crystal cell 32 is provided in which liquid crystal molecules and the like are oriented in a certain direction in the absence of an electric field of the liquid crystal layer 8 and alignment is not performed in the alignment layers 13 and 17. Can.

(Liquid crystal layer)
The liquid crystal layer 8 can be widely applied to various liquid crystal materials applicable to the liquid crystal cell 32 of this type. Specifically, a nematic liquid crystal compound, a smectic liquid crystal compound and a cholesteric liquid crystal compound can be applied to the liquid crystal layer 8 as a liquid crystal compound having no polymerizable functional group.
Examples of nematic liquid crystal compounds include biphenyl compounds, terphenyl compounds, phenylcyclohexyl compounds, biphenylcyclohexyl compounds, phenylbicyclohexyl compounds, trifluoro compounds, phenyl benzoate compounds, cyclohexyl benzoate phenyl compounds , Phenylbenzoic acid phenyl compounds, bicyclohexylcarboxylic acid phenyl compounds, azomethine compounds, azo compounds, azooxy compounds, stilbene compounds, tolane compounds, ester compounds, bicyclohexyl compounds, phenylpyrimidine compounds And biphenyl pyrimidine compounds, pyrimidine compounds, and biphenyl ethyne compounds.

Examples of smectic liquid crystal compounds include ferroelectric polymer liquid crystal compounds such as polyacrylates, polymethacrylates, polychloroacrylates, polyoxiranes, polysiloxanes, and polyesters.
As a cholesteric liquid crystal compound, cholesteryl linoleate, cholesteryl oleate, cellulose, a cellulose derivative, polypeptide etc. can be mentioned, for example.

  In the liquid crystal cell 32, a sealing material 19 is disposed so as to surround the liquid crystal layer 8. The upper laminate 5U and the lower laminate 5D are integrally held by the sealing material 19, and the liquid crystal material is prevented from leaking. For example, a thermosetting resin such as an epoxy resin or an acrylic resin, an ultraviolet curable resin, or the like can be used as the sealing material 19.

  In the liquid crystal cell 32, an alternating current voltage whose polarity is switched at a predetermined cycle is applied to the transparent electrodes 11 and 16, and an electric field is formed in the liquid crystal layer 8 by the alternating current voltage. Further, the orientation of liquid crystal molecules provided in the liquid crystal layer 8 is controlled by this electric field, and the transmitted light is controlled.

In the present embodiment, the liquid crystal layer 8 uses a guest host system. The guest-host system is a system using a liquid crystal composition in which a dichroic dye is dissolved as a guest in a nematic liquid crystal which is a host. Since the dichroic dye has a uniaxial light absorption axis and absorbs only light oscillating in the light absorption axis direction, it changes the orientation of the dichroic dye in accordance with the movement of the liquid crystal due to the electric field. By controlling the direction of the light absorption axis, the transmission state of the liquid crystal cell can be changed.
In the liquid crystal layer 8 of the present embodiment, when the dichroic dye is distributed in the vertical direction (direction parallel to the thickness direction of the liquid crystal layer 8), the transmittance can be maximized, and non-polarized light can be obtained. It can be transmitted almost as it is.
On the other hand, when the dichroic dye is distributed in the horizontal direction (the direction perpendicular to the thickness direction of the liquid crystal layer 8), the transmittance can be minimized. At this time, since the light in the direction orthogonal to the absorption axis is transmitted through the liquid crystal layer 8 with little absorption, the liquid crystal cell 32 has the same function as that of the linear polarizing plate.

  Liquid crystal compositions used in the guest host system are roughly classified into positive type and negative type according to the difference in the long axis direction of liquid crystal molecules when an electric field is applied.

In this embodiment, a negative nematic liquid crystal is used. A negative nematic liquid crystal is a liquid crystal in which the dielectric constant is small in the major axis direction and the dielectric anisotropy is large in the direction perpendicular to the major axis, and the major axis direction of liquid crystal molecules with respect to the optical axis when no electric field is applied. It is parallel (parallel to the thickness direction of the liquid crystal layer 8, vertical alignment), and when an electric field is applied, the major axis direction of the liquid crystal molecules is perpendicular to the optical axis (vertical to the thickness direction of the liquid crystal layer 8, horizontal alignment) .
In this embodiment, since the dichroic dye molecules are aligned in the same direction as the liquid crystal molecules, a negative nematic liquid crystal is used as a host, and it is in a transmission state when no electric field is applied and is in a light shielding state when an electric field is applied (normally White mode).

Note that a positive nematic liquid crystal may be used. A positive nematic liquid crystal is a liquid crystal whose dielectric constant is large in the long axis direction and small in the direction perpendicular to the long axis and whose dielectric anisotropy is positive. When no electric field is applied, the long axis direction of liquid crystal molecules is relative to the optical axis. When the electric field is applied, the major axis direction of the liquid crystal molecules is parallel to the optical axis (parallel to the thickness direction of the liquid crystal layer 8, vertical alignment).
When a positive nematic liquid crystal is used as a host, it becomes a light shielding state when there is no electric field, and becomes a transmitting state when an electric field is applied (normally black mode).

  Examples of dichroic dyes used in the guest host system include dyes that are soluble in liquid crystals and have high dichroism, preferably dyes having an order parameter (S value) of 0.7 or more, for example, Dichroic dyes such as azo dyes, anthraquinone dyes, quinophthalone dyes, perylene dyes, indigo dyes, thioindigo dyes, merocyanine dyes, styryl dyes, azomethine dyes and tetrazine dyes may be mentioned.

  The VA method (Vertical Alignment, vertical alignment type) is applied to the alignment control of the liquid crystal layer 8 in the liquid crystal cell 32 of the present embodiment. In the VA system, an alignment layer having an alignment control force in the vertical direction (the thickness direction of the liquid crystal layer 8) is provided on a transparent electrode formed on a substrate, and the liquid crystal layer 8 is sandwiched between upper and lower substrates.

  However, instead of the VA method, various driving methods such as a TN (Twisted Nematic) method and an IPS (In Plane Switching) method may be applied.

Here, in the TN method, an alignment film subjected to rubbing processing or the like in which alignment directions are different from each other by 90 ° is provided on transparent electrodes formed on upper and lower substrates, and the liquid crystal layer 8 is sandwiched. The liquid crystal molecules are aligned along the alignment direction of the alignment film by the alignment regulating force of the alignment film, and the other liquid crystal molecules are aligned along the liquid crystal molecules, so that the liquid crystal molecules are aligned in a 90 ° twisting direction.
In the IPS method, electrodes are formed collectively on one substrate, and the amount of transmitted light is controlled by rotating liquid crystal molecules aligned by an electric field by the electrodes in a lateral (horizontal) direction with respect to the substrate. is there.

(Photometry unit)
Returning to FIG. 1, the photometry unit 50 is provided on the surface 30 a of the reflection adjustment element 30 on which the outside light is incident, measures the outside light illuminance in the vicinity of the surface 30 a of the reflection adjustment element 30, and measures the measurement results. Output to 60. The photometry unit 50 can use, for example, an element capable of detecting the brightness, such as a photodiode or a CCD.

(Control unit)
The control unit 60 is connected to the photometry unit 50, each of the electrodes 11 and 16 of the reflection adjustment element 30, and the image display device 20, and based on the measurement information of the photometry unit 50, the reflection adjustment element 30 and the image display device 20. Control (details will be described later).

  As described above, the reflection adjustment element 30 of the present embodiment is a member that adjusts the reflection amount of the external light incident on the image display surface 20 a of the image display device 20. The reflection adjusting element 30 has a polarization mode H giving priority to reducing the reflection of external light on the image display surface 20a, and a non-polarization mode giving priority to improving the transmittance of image light of the image display device 20 emitted from the image display surface 20a. And M.

(Polarization mode H)
FIG. 3 is a view for explaining the polarization mode H of the reflection adjustment element 30 of the present embodiment. In the figure, liquid crystal molecules are indicated by 8a and dichroic dyes are indicated by 8b.
FIG. 4 is a table showing an example of the reflectance and the transmittance in the polarization mode H shown in FIG. 3, the first comparative embodiment shown in FIG. 5, and the non-polarization mode M shown in FIG. The reflectance in parentheses in FIG. 4 is a value related to the light L7 or the light L7a.
In FIG. 3, a voltage is applied between the electrodes 11 and 16, and the liquid crystal molecules 8a and the dichroic dye 8b of the liquid crystal cell 32 are in the horizontal direction (direction perpendicular to the thickness direction of the liquid crystal layer 8). It is in the oriented state, that is, in the horizontal orientation state. The dichroic dye 8b has an elongated molecular shape, and the major axis is the absorption axis X of light, absorbs light oscillating in the direction of the absorption axis X, and transmits light in the direction orthogonal to the absorption axis X .

In FIG. 3, when non-polarized light L1 from the outside emitted from a light source such as sunlight is incident on the surface 30a of the reflection adjustment element 30, a small amount of light L1 ′ is reflected by the surface 30a of the reflection adjustment element 30. Most of the light enters the liquid crystal cell 32. Here, light in a non-polarization state refers to light having vibration components in various directions.
As an example, as shown in FIG. 3, when light L1 in the non-polarization state is incident on the reflection adjustment element 30, 4% of the light L1 L1 is reflected on the surface of the reflection adjustment element 30, and 96% of the light L1 The light L 2 enters the liquid crystal cell 32.

  Then, in the liquid crystal cell 32, a component that vibrates in the direction of the absorption axis X of the dichroic dye is absorbed, and the polarized light L3 that is light in a polarization state that vibrates in the direction orthogonal to the absorption axis X is emitted.

The polarized light L 3 becomes circularly polarized light L 4 when transmitted through the quarter wavelength plate 31.
The circularly polarized light L4 is reflected by the image display surface 20a of the image display device 20 and becomes circularly polarized light L5 rotating in the reverse direction.
When the circularly polarized light L5 is transmitted through the 1⁄4 wavelength plate 31 again, it becomes polarized light L6 orthogonal to the polarized light L3.
Then, since the polarized light L6 vibrates in the same direction as the absorption axis X direction of the dichroic dye 8b in the liquid crystal cell 32, it is almost absorbed by the dichroic dye 8b, and only a small amount of light L7 from the liquid crystal cell 32. I will emit.

As an example, as shown in the column of polarization mode H in FIG. 3 and FIG. 4, the light L7 emitted from the liquid crystal cell 32 is about 4% of the incident light L1. Therefore, the reflectance at the reflection adjustment element 30 is 8% because it is the sum of 4% of the light L1 ′ and 4% of the light L7.
On the other hand, the transmittance of the reflection adjustment element 30 of the image light emitted from the image display surface 20a of the image display device 20 is 40%.

(First comparison form)
FIG. 5 is a view for explaining the circularly polarizing plate 30A of the first comparative embodiment of the present embodiment.
In the first comparative embodiment, a circularly polarizing plate 30A is attached to the image display surface 20a of the image display device 20 instead of the reflection adjustment element 30 of the first embodiment. While the difference between the reflection adjusting element 30 and the circularly polarizing plate 30A is that the reflection adjusting element 30 is a laminate of the liquid crystal cell 32 and the quarter wavelength plate 31, the circularly polarizing plate 30A is a linear polarizing plate 32A. And a quarter wave plate 31.
The direction of the absorption axis XA of the linear polarization plate 32A is the same as the absorption axis X of the liquid crystal cell 32 in the horizontal alignment state shown in FIG.
Also in FIG. 5, as in FIG. 3, when the non-polarized light L1 from the outside emitted from the light source such as sunlight is incident on the linear polarization plate 32A, a slight amount of light L1 ′ is reflected and most of the light is The light is incident on the linear polarizer 32A.
As shown in FIG. 5, as an example, when light L1 in the non-polarization state from the outside emitted from a light source such as sunlight is incident on the linear polarization plate 32A, 3.9% of the light L1 'is reflected, and the rest is About 96% of the light is incident on the linear polarizer 32A. Then, in the linear polarization plate 32A, the component vibrating in the direction of the absorption axis XA is absorbed, and the polarized light L3 vibrating in the direction orthogonal to the absorption axis XA is emitted.

The polarized light L 3 becomes circularly polarized light L 4 when transmitted through the quarter wavelength plate 31.
The circularly polarized light L4 is reflected by the image display surface 20a of the image display device 20 and becomes circularly polarized light L5 rotating in the reverse direction.
When the circularly polarized light L5 is transmitted through the 1⁄4 wavelength plate 31 again, it becomes polarized light L6 orthogonal to the polarized light L3.
The polarized light L6 vibrates in the same direction as the direction of the absorption axis XA of the linear polarizing plate 32A in the linear polarizing plate 32A, so it is almost absorbed, and only a small amount of light L7 is emitted from the linear polarizing plate 32A.
As shown in the column of the first comparative embodiment of FIG. 4 and FIG. 5, as an example, the light L7 emitted from the linear polarization plate 32A is about 0.1% of the incident light L1. Therefore, the reflectance of the reflection adjustment element 30 is 4% because it is the sum of 3.9% of the light L1 ′ and 0.1% of the light L7.
On the other hand, the transmittance of the reflection adjustment element 30 of the image light emitted from the image display surface 20a of the image display device 20 is 40%.

According to the present embodiment, as shown in FIG. 3, when the liquid crystal molecules 8a and the dichroic dye 8b of the liquid crystal cell 32 are in the horizontal alignment state, the linear polarization plate 32A is disposed in the light path instead of the liquid crystal cell 32. The reflectance is slightly increased from 4% to 8%.
However, even at a reflectance of 8%, it is a sufficiently acceptable range as a reflection suppressing function. Further, the transmittance of the image light emitted from the image display surface 20a of the image display device 20 is substantially the same between the present embodiment and the first comparative embodiment.
Therefore, in the polarization mode H, the reflection adjustment element 30 of the present embodiment is judged to have substantially the same performance as the circularly polarizing plate 30A of the first comparative embodiment.

(Non-polarization mode M)
FIG. 6 is a view for explaining the non-polarization mode M of the reflection adjustment element 30 of the present embodiment.
In FIG. 6, no voltage is applied between the electrodes 11 and 16, and the liquid crystal molecules 8a and the dichroic dye 8b of the liquid crystal cell 32 are in the vertical direction (the direction parallel to the thickness direction of the liquid crystal layer 8). Orientation, ie, vertical orientation.
In FIG. 6, when non-polarized light L1 from the outside emitted by a light source such as sunlight is incident on the reflection adjustment element 30, a small amount of light L1a 'is reflected on the surface of the reflection adjustment element 30, and most of The light enters the liquid crystal cell 32.
As an example, as shown in FIG. 6, when light L1 in the non-polarization state is incident on the reflection adjustment element 30, 2% of the incident light L1 light L1a ′ is reflected on the surface of the reflection adjustment element 30, and the remaining 98 % Of light L2a enters the liquid crystal cell 32.

  Then, in the liquid crystal cell 32, since the absorption axis X of the dichroic dye is in the vertical direction (the thickness direction of the liquid crystal layer 8), the non-polarized light L2a incident on the liquid crystal cell 32 is almost all as shown in FIG. It becomes light L3a and is emitted from the liquid crystal cell 32 without being absorbed. Here, the light L3a emitted from the liquid crystal cell 32 is non-polarized light having vibration components in various directions, as in the non-polarized light L1 incident on the liquid crystal cell 32.

When the light L3a is transmitted through the 1⁄4 wavelength plate 31, it becomes light L4a in a non-polarization state. Then, the light L4a is reflected by the image display surface 20a of the image display device 20 and becomes light L5a in a non-polarization state.
Then, the light L5a in the non-polarization state is again transmitted through the quarter wavelength plate 31 to be light L6a in the non-polarization state.
The amount of absorption of the light L6a in the liquid crystal cell 32 is small, and a certain amount of light L7a is emitted from the liquid crystal cell 32 in a non-polarized state.

As an example, as shown in the column of non-polarization mode M in FIG. 6 and FIG. 4, the light L7a emitted from the liquid crystal cell 32 is about 53%. Therefore, the reflectance of the reflection adjustment element 30 is 55% because it is the sum of 2% of the light L1 ′ and 53% of the light L7a.
On the other hand, the transmittance of the reflection adjustment element 30 of the image light emitted from the image display surface 20a of the image display device 20 is 70%.

(Second comparison form)
FIG. 7 is a view for explaining a transparent film 32B of the second comparative embodiment of the present embodiment.
In the second comparative embodiment, a transparent film 32B that slightly absorbs light instead of the reflection adjustment element 30 is attached to the image display surface 20a of the image display device 20.
Also in FIG. 7, as in FIG. 6, when non-polarized light L1 from the outside emitted from a light source such as sunlight is incident on the transparent film 32B, the non-polarized light L1 from the outside is hardly absorbed.
As shown in the drawing, the light L3b transmitted through the transparent film 32B is also a non-polarization state having vibration components in various directions, like the light L1 in the non-polarization state incident on the transparent film 32B from the light source.

The light L3b is reflected by the image display surface 20a of the image display device 20 and enters the transparent film 32B again as light L5b in the unpolarized state. The light L5b is hardly absorbed by the transparent film 32B, and is emitted from the transparent film 32B as light L7b in the non-polarized state.
That is, in the non-polarization mode M, the reflection adjustment element 30 of the present embodiment has substantially the same performance as the transparent film 32B of the second comparative embodiment.

As described above, according to the present embodiment, the reflection adjustment element 30 can switch between the polarization mode H and the non-polarization mode M by controlling the application of a voltage between the electrodes 11 and 16.
When switched to the polarization mode H, the reflection adjusting element 30 functions in substantially the same manner as when the circularly polarizing plate 30A is disposed on the image display surface 20a of the image display device 20, and reduces the reflectance on the image display surface 20a. Can.
When switched to the non-polarization mode M, the reflection adjustment element 30 functions in substantially the same manner as when the transparent film 32B that slightly absorbs light is disposed on the image display surface 20a of the image display device 20. The transmittance of the emitted image light can be improved.

FIG. 8 is a graph for explaining the switching operation between the non-polarization mode M and the polarization mode H of the reflection adjustment element 30 in the control unit 60 of the present embodiment.
The horizontal axis of the graph indicates the illuminance of the ambient light measured by the photometry unit 50. The vertical axis of the graph indicates the light emission luminance of the image display surface 20 a suitable for the observation of the display image when the image display surface 20 a of the image display device 20 is observed through the reflection adjustment element 30.
The line H in FIG. 8 shows the relationship between the ambient light illuminance when the reflection adjustment element 30 is switched to the polarization mode H and the light emission luminance of the image display device 20, and the line M in FIG. 7 shows the relationship between the ambient light illuminance when the mode is switched to the non-polarization mode M, and the light emission luminance of the image display device 20. Further, the value of the ambient light illuminance at the intersection of the line H and the line M in FIG.

In both the non-polarization mode M and the polarization mode H, it becomes difficult to observe the image displayed on the image display surface 20a when the external light illuminance becomes high, and therefore it is necessary to increase the light emission luminance of the image display surface 20a.
Here, when the reflection adjustment element 30 is in the non-polarization mode M, as shown in FIG. 4, the reflectance is higher than in the polarization mode H, so the external light illuminance is high (more than the value P in FIG. When the polarization mode is H, the image on the image display surface 20a becomes difficult to see. Therefore, when the external light illuminance is high, the image display device 20 of the image display surface 20a has a higher image quality when the reflection adjustment element 30 is in the non-polarization mode M, as shown in FIG. The light emission luminance needs to be increased, and the power consumption is increased.
Therefore, when the ambient light illuminance is high (higher than the value P in FIG. 8), the reflection adjustment element 30 is preferably set to the polarization mode H rather than the nonpolarization mode M.

On the other hand, when the external light illuminance is low (lower than the value P in FIG. 8), the non-polarization mode M of the reflection adjustment element 30 has a higher transmittance than the polarization mode H as shown in FIG. Therefore, when the reflection adjustment element 30 is in the non-polarization mode M, as shown in FIG. 8, the image display device 20 does not increase the light emission luminance of the image display surface 20 a as in the polarization mode H. The display surface 20a can be made observable.
Therefore, when the ambient light illuminance is low (lower than the value P in FIG. 8), the reflection adjustment element 30 is preferably set to the non-polarization mode M rather than the polarization mode H.

As mentioned above, when external light illumination intensity is lower than the value P which the line of polarization mode H shown in the graph of FIG. 8 and the line of non-polarization mode M cross, non-polarization mode M is preferred. In addition, when the ambient light illuminance is higher than the value P, the polarization mode H is preferable.
In the present embodiment, when the ambient light illuminance is equal to the value P, the non-polarization mode M is set. However, the present invention is not limited to this, and the polarization mode H is set. It is also good.

FIG. 9 is a flowchart showing the operation of the control unit 60 of this embodiment.
First, in step 1, the control unit 60 measures the ambient light illuminance by the photometry unit 50.
Next, in step 2, the control unit 60 determines whether the ambient light illuminance measured by the photometry unit 50 is equal to or less than the value P shown in FIG. 8.
When the ambient light illuminance measured by the photometry unit 50 is equal to or less than the value P shown in FIG. 8 (Yes in step S2), the control unit 60 sets the reflection adjustment element 30 to the non-polarization mode M in step S3. That is, when the initial state of the reflection adjustment element 30 is the non-polarization mode M, the non-polarization mode M is maintained as it is, and in the polarization mode H, the voltage application between the electrodes 11 and 16 is stopped and the non-polarization mode M is Make it Then, the control unit 60 adjusts the light emission luminance of the image display surface 20a of the image display device 20 based on the line M shown in FIG. 8 in accordance with the ambient light illuminance (step S5).

  When the ambient light illuminance measured by the photometry unit 50 is larger than the value P shown in FIG. 8 (No in step S2), the control unit 60 sets the reflection adjustment element 30 to the polarization mode H in step S4. That is, when the initial state of the reflection adjustment element 30 is the non-polarization mode M, the polarization mode H is maintained as it is, and in the non-polarization mode M, a voltage is applied between the electrodes 11 and 16 to make the polarization mode H . Then, the control unit 60 adjusts the light emission luminance of the image display surface 20a of the image display device 20 based on the line H shown in FIG. 8 in accordance with the ambient light illuminance (step S5).

As mentioned above, the reflection adjustment element 30 of this embodiment controls the application of the voltage to the liquid crystal layer 8, thereby improving the polarization mode H in which the reduction of the reflection of the external light is prioritized in the liquid crystal cell 32 and the transmittance of the image light. To the non-polarization mode M which gives priority.
Thus, for example, when the reflection adjustment element 30 is disposed on the image display surface 20a of the image display device 20, the liquid crystal cell 32 is polarized when the external light illuminance is high and the reflection is large as in the outdoor sun. It is possible to switch to the mode H to reduce the reflectance, and to minimize the reflection of external light on the image display surface 20a.
When the ambient light illuminance is low, such as in a shade or indoors with little illumination, the reflection adjusting element 30 switches the liquid crystal cell 32 to the non-polarization mode M to improve the transmittance and is displayed on the image display surface 20a. Images can be displayed more clearly.

Further, in the reflection adjustment system 100 of the present embodiment, the control unit 60 changes the voltage applied to the electrodes 11 and 16 based on the photometric result by the photometry unit 50, and the reflection adjustment element 30 is set to the non-polarization mode M or Switch to polarization mode H.
Thereby, the reflection adjustment system 100 switches the liquid crystal cell 32 of the reflection adjustment element 30 to the polarization mode H when it is determined that the outside light illuminance is higher than the value P based on the photometry result of the photometry unit 50 to display an image. The reflection of external light on the surface 20a can be suppressed as much as possible.
Further, when it is determined that the ambient light illuminance is lower than the value P based on the photometry result of the photometry unit 50, the liquid crystal cell 32 of the reflection adjustment element 30 is switched to the non-polarization mode M to improve the transmissivity. The image displayed on the surface 20a can be displayed more clearly.

In the reflection adjustment system 100 of the present embodiment, the control unit 60 changes the light emission luminance of the image display surface 20 a according to the photometric result by the photometry unit 50.
Thereby, when the external light illuminance is determined to be high, the reflection adjustment system 100 emits light on the image display surface 20a when the polarization mode H is set as compared to when the non-polarization mode M is set. There is no need to increase the luminance, and power consumption can be reduced.
In addition, when the non-polarization mode M is set when it is determined that the ambient light illuminance is low, it is not necessary to increase the light emission luminance of the image display surface 20a compared to when the polarization mode H is set. Power consumption can be reduced.

  The reflection adjustment system 100 of the present embodiment has a so-called normally white mode liquid crystal layer 8 in which the transmittance when no electric field is generated in the liquid crystal layer 8 is higher than the transmittance when an electric field is generated in the liquid crystal layer 8. Is equipped. Thereby, when the frequency of using the reflection adjusting system 100 mainly in the indoor etc. is high, the frequency of using the non-polarization mode M becomes high, so the power consumption by driving the reflection adjusting element 30 (liquid crystal cell 32) is reduced. can do.

  As described above, according to the present embodiment, a small amount of light L1a ′ of the non-polarized light L1 emitted from the light source such as sunlight from the outside enters the reflection adjustment element 30 of the reflection adjustment element 30. Reflects on the surface. However, this can be prevented by sticking a reflection reducing layer (so-called AR film) as described in the third embodiment on the surface of the reflection adjusting element 30.

Second Embodiment
Next, a reflection adjusting system 200 of the second embodiment will be described.
FIG. 10 is a view showing a reflection adjustment system of the second embodiment, and is a view for explaining the reflectance when the reflection adjustment element 30 is in the polarization mode H.
FIG. 11 is a view showing a reflection adjustment system of the second embodiment, and is a view explaining the reflectance when the reflection adjustment element 30 is in the non-polarization mode M.
In the following description and the drawings, parts that perform the same functions as those in the first embodiment described above are given the same reference numerals, and overlapping descriptions will be omitted as appropriate.

In the reflection adjusting system 200 of the present embodiment, as shown in FIG. 10, the reflection adjusting element 30 is disposed on the mirror member 101.
The reflection adjusting element 30 according to the present embodiment is the same as the reflection adjusting element 30 according to the first embodiment described above, so the description of the same parts will be omitted. Further, a control unit 60 (not shown) is connected to each of the electrodes 11 and 16 of the reflection adjustment element 30.
The mirror surface member 101 is a member whose surface is formed in a mirror surface, and is, for example, a rearview mirror of a vehicle. The mirror member 101 has a surface formed in a mirror shape, and a surface of the reflection adjustment element 30 on the side of the 1⁄4 wavelength plate 31 attached.
The control unit 60 switches the reflection adjustment element 30 to the polarization mode H or the non-polarization mode M by controlling the voltage applied to each of the electrodes 11 and 16 of the reflection adjustment element 30. Specifically, when a voltage is applied to the electrodes 11 and 16 of the reflection adjustment element 30, the control unit 60 switches the reflection adjustment element 30 to the polarization mode H and applies a voltage to the electrodes 11 and 16 of the reflection adjustment element 30. Is not applied, the reflection adjustment element 30 is switched to the non-polarization mode M.

(Polarization mode)
When the reflection adjusting element 30 is set to the polarization mode H, as in the first embodiment, when non-polarized light L1 emitted from an external light source such as sunlight is incident on the reflection adjusting element 30, a slight amount The light L 1 ′ is reflected, and most of the light is incident on the reflection adjustment element 30.
As shown in FIG. 10, as an example, when non-polarized light L1 from the outside emitted from a light source such as sunlight is incident on the reflection adjustment element 30, 4% of the light L1 'of the light L1 is reflected and the rest is 96% of the light enters the reflection adjustment element 30.

Then, in the reflection adjustment element 30, in the liquid crystal cell 32, the component that vibrates in the direction of the absorption axis X of the dichroic dye has the incident light in the same manner as in the polarization mode H of the first embodiment (see FIG. 3). The first polarized light (L3 in FIG. 3) which is absorbed and vibrates in a direction orthogonal to the absorption axis X is emitted.
When the first polarized light passes through the 1⁄4 wavelength plate 31, it becomes first circular polarized light (L4 in FIG. 3).
The first circularly polarized light is reflected by the mirror surface of the mirror member 101 and becomes the second circularly polarized light (L5 in FIG. 3) rotating in the reverse direction.
When the second circularly polarized light passes through the quarter wavelength plate 31 again, it becomes second polarized light (L6 in FIG. 3) orthogonal to the first polarized light.
Then, the second polarized light vibrates in the same direction as the absorption axis X direction of the dichroic dye 8b in the liquid crystal cell 32, so it is almost absorbed by the dichroic dye 8b, and only a small amount of light L7 from the liquid crystal cell 32. Comes out.
As shown in FIG. 10, since the light L7 emitted from the liquid crystal cell 32 as an example is 4% of the incident light (96%), it is about 4%. Therefore, the reflectance at the reflection adjustment element 30 is about 8% because it is the sum of 4% of the light L1 ′ and about 4% of the light L7.

(Non-polarization mode)
When the reflection adjustment element 30 is set to the non-polarization mode M, the non-polarization light L1 from the outside emitted from the light source such as sunlight is slightly incident on the reflection adjustment element 30, as in the first embodiment. Light L 1 ′ is reflected, and most of the light is incident on the reflection adjustment element 30.
As shown in FIG. 11, when non-polarized light L1 from the outside emitted from a light source such as sunlight is incident on the reflection adjustment element 30, 4% of light L1 'is reflected and 96% of light is reflected. The light is incident on the adjustment element 30.

Then, the incident light is transmitted through the reflection adjustment element 30, reflected by the mirror member 101, transmitted again through the reflection adjustment element 30, and the light L7 is emitted from the reflection adjustment element 30.
As shown in FIG. 11, as an example, the light L7 emitted from the liquid crystal cell 32 becomes 53% of the incident light (96%) by passing through the reflection adjustment element 30 twice, and is about 51%. Therefore, the reflectance at the reflection adjustment element 30 is about 55% because it is the sum of 4% of the light L1 ′ and about 51% of the light L7.

(Third comparison form)
FIG. 12 shows a comparison form (third comparison form) of the second embodiment.
The third comparative embodiment differs from the second embodiment in that, instead of the reflection adjusting element 30, a circularly polarizing plate 30A including a linear polarizing plate and a quarter wavelength plate is disposed. The quarter-wave plate side of the circularly polarizing plate 30A is attached to the mirror member.
In this case, as in the first comparative embodiment (see FIG. 5), about 4% of the light L1 'of the light incident on the circularly polarizing plate 30A is reflected by the circularly polarizing plate 30A, and 96% is circularly polarizing plate It injects into the inside of 30A. The light incident on the circularly polarizing plate 30A is transmitted through the circularly polarizing plate 30A to be circularly polarized light, and is reflected by the mirror surface of the mirror member 101 to be reversely rotated circularly polarized light, and is mostly transmitted while passing through the circularly polarizing plate 30A again Is absorbed, and the light L7 emitted from the circularly polarizing plate 30A is 0.1% of the light (96%) incident on the circularly polarizing plate 30A, and thus becomes about 0.1%. Therefore, the reflectance of the circularly polarizing plate 30A is about 4.1%, which is the sum of about 4% of the light L1 ′ and about 0.1% of the light L7.

(Fourth comparative form)
FIG. 13 shows another comparison form (fourth comparison form) of the second embodiment.
The fourth comparative embodiment differs from the second embodiment in that the mirror member 101 is not provided with a reflection adjusting element. That is, the surface of the mirror member 101 is the outermost surface.
In this case, the light L1 incident on the mirror surface of the mirror member 101 is 100% reflected.

According to this embodiment, when the liquid crystal molecules 8a and the dichroic dye 8b of the liquid crystal cell 32 are in the horizontal alignment state (polarization mode H) (see FIG. 10), the circularly polarizing plate 30A is used in the light path instead of the reflection adjustment element 30. The reflectance is slightly increased from 4.1% to 8% as compared to the third comparative embodiment in which the arrangement is made. However, even at a reflectance of 8%, it is a sufficiently acceptable range as a reflection suppressing function.
Therefore, in the polarization mode H, the reflection adjustment element 30 of the present embodiment is judged to have substantially the same performance as the circularly polarizing plate 30A of the third comparative embodiment.

As mentioned above, the reflection adjustment system 200 of this embodiment switches the polarization mode H and the non-polarization mode M by controlling the application of the voltage to the reflection adjustment element 30 according to the external light illuminance by the control unit 60. it can.
When switching to the polarization mode H, the reflection function of the mirror member 101 can be reduced by functioning in the same manner as in the case where the circularly polarizing plate 30A is disposed instead of the reflection adjusting element 30 in the light path of the third comparative embodiment.
For example, when the mirror member 101 is used as a rearview mirror of a vehicle, glare is reduced by switching the reflection adjustment element 30 to the polarization mode H when the light of a following vehicle or the like enters the rearview mirror and is dazzling. Can.

Further, when switched to the non-polarization mode M, it functions in the same manner as when the reflection adjustment element 30 of the fourth comparative embodiment is omitted, and the transmittance can be improved as compared with the polarization mode H.
Therefore, when the mirror member 101 is used as a rearview mirror of a vehicle, it is not necessary to suppress the reflected light when the strong light is not incident on the rearview mirror, so the reflection adjustment system 200 The mode can be switched to the non-polarization mode M, which has high transmittance, so that the rear aspect of the vehicle can be well mirrored.

Third Embodiment
Next, a reflection adjustment system 300 of the third embodiment will be described.
FIG. 14 is a view showing a reflection adjustment system of the third embodiment, and is a view for explaining the reflectance when the reflection adjustment element 30 is in the polarization mode H.
FIG. 15 is a view showing a reflection adjusting system of the third embodiment, and is a view explaining a reflectance when the reflection adjusting element 30 is in the non-polarization mode M.
In the following description and the drawings, parts that perform the same functions as those in the first embodiment described above are given the same reference numerals, and overlapping descriptions will be omitted as appropriate.

In the reflection adjusting system 300 of the present embodiment, as shown in FIG. 14, the reflection adjusting element 30 is disposed on the mirror member 101, and the reflection reducing layer 102 is disposed on the opposite side of the reflection member 30 to the mirror member. ing.
The reflection adjusting element 30 according to the present embodiment is the same as the reflection adjusting element 30 according to the first embodiment described above, so the description of the same parts will be omitted. Further, a control unit 60 (not shown) is connected to each of the electrodes 11 and 16 of the reflection adjustment element 30.
The mirror surface member 101 is a member whose surface is formed in a mirror surface, and is, for example, a rearview mirror of a vehicle. The mirror member 101 has the surface formed in a mirror shape and the surface on the 1⁄4 wavelength plate 31 side of the reflection adjustment element 30 attached.
The reflection reduction layer 102 is a layer that prevents reflection of incident light, and, for example, a low refractive index layer having a refractive index of 1.20 to 1.40 and a high refractive index layer having a refractive index of 1.60 to 2.00. An antireflective film (AR film) for preventing reflection by the two-layer laminated structure of the above, or an antireflective film or the like for achieving antireflection by the uneven shape may be formed on the surface. The reflection reducing layer 102 is attached to the surface of the reflection adjusting element 30 on the liquid crystal cell 32 side.
The control unit 60 switches the reflection adjustment element 30 to the polarization mode H or the non-polarization mode M by controlling the voltage applied to each of the electrodes 11 and 16 of the reflection adjustment element 30. Specifically, when a voltage is applied to the electrodes 11 and 16 of the reflection adjustment element 30, the control unit 60 switches the reflection adjustment element 30 to the polarization mode H and applies a voltage to the electrodes 11 and 16 of the reflection adjustment element 30. Is not applied, the reflection adjustment element 30 is switched to the non-polarization mode M.

(Polarization mode)
When the reflection adjustment element 30 is set to the polarization mode H, even if light L1 from the outside emitted from the light source such as sunlight is incident on the surface of the reflection reduction layer 102, the light reflected on the surface is reduced. Is almost 0%.
Then, about 100% of light passes through the reflection reducing layer 102 and enters the reflection adjusting element 30.
As shown in FIG. 14, as an example, when non-polarized light L1 from the outside emitted from a light source such as sunlight is incident on the reflection adjustment element 30, approximately 100% of light is incident on the reflection adjustment element 30.

Then, in the reflection adjustment element 30, in the liquid crystal cell 32, the component that vibrates in the direction of the absorption axis X of the dichroic dye has the incident light in the same manner as in the polarization mode H of the first embodiment (see FIG. 3). The first polarized light (L3 in FIG. 3) which is absorbed and vibrates in a direction orthogonal to the absorption axis X is emitted.
When the first polarized light passes through the 1⁄4 wavelength plate 31, it becomes first circular polarized light (L4 in FIG. 3).
The first circularly polarized light is reflected by the mirror surface of the mirror member 101 and becomes the second circularly polarized light (L5 in FIG. 3) rotating in the reverse direction.
When the second circularly polarized light passes through the quarter wavelength plate 31 again, it becomes second polarized light (L6 in FIG. 3) orthogonal to the first polarized light.
Then, the second polarized light vibrates in the same direction as the absorption axis X direction of the dichroic dye 8b in the liquid crystal cell 32, and therefore, is absorbed almost by the dichroic dye 8b, and only a small amount of light from the liquid crystal cell 32. I will emit.
Then, a slight amount of light emitted from the liquid crystal cell 32 is transmitted through the reflection reducing layer 102 and emitted from the surface of the reflection reducing layer 102 as light L7.
As shown in FIG. 14, the light L7 emitted from the surface of the reflection reducing layer 102 as an example is 4% of the incident light (about 100%), so it is about 4%. Therefore, the reflectance of the reflection adjustment element 30 is about 4% because it is the sum of about 0% of the light L1 ′ and about 4% of the light L7.

(Non-polarization mode M)
When the reflection adjustment element 30 is set to the polarization mode H, even if light L1 from the outside emitted from the light source such as sunlight is incident on the surface of the reflection reduction layer 102, the light reflected on the surface is reduced. Is almost 0%.
Then, about 100% of light passes through the reflection reducing layer 102 and enters the reflection adjusting element 30.
As shown in FIG. 15, as an example, when light L1 in the non-polarization state from the outside emitted from a light source such as sunlight is incident on the reflection adjustment element 30, about 0% of the light L1 ′ is reflected and light of about 100% Is incident on the reflection adjustment element 30.

Then, the incident light passes through the reflection adjusting element 30, is reflected by the mirror member 101, passes through the reflection adjusting element 30 and the reflection reducing layer 102 again, and the light L7 is emitted from the reflection adjusting element 30.
As shown in FIG. 15, as an example, light L7 emitted from the liquid crystal cell 32 becomes 53% of the incident light (100%) by passing through the reflection adjustment element 30 and the reflection reduction layer 102 twice, so It will be 53%. Therefore, the reflectance of the reflection adjustment element 30 is about 53% because it is the sum of about 0% of the light L1 ′ and about 53% of the light L7.

(Fifth comparative embodiment)
FIG. 16 is a comparison form (fifth comparison form) of the third embodiment.
The difference with the third embodiment of the fifth comparative embodiment is that instead of the reflection adjustment element 30, a circularly polarizing plate 30A including a linear polarizing plate and a quarter wavelength plate is disposed. The quarter-wave plate side of the circularly polarizing plate 30A is attached to the mirror member.
In this case, as in the third embodiment described above, as shown in FIG. 16, even if the light L1 in the non-polarization state is incident on the reflection reduction layer 102, the light L1 ′ reflected on the surface is about 0%. Approximately 100% of the light enters the circularly polarizing plate 30A through the reflection reducing layer 102.
The light incident on the circularly polarizing plate 30A passes through the circularly polarizing plate 30A to become first circularly polarized light, and is reflected by the mirror surface of the mirror member 101 to be reversely rotated second circularly polarized light, and is incident on the circularly polarizing plate 30A again The light L7 which is mostly absorbed during transmission and is emitted from the circularly polarizing plate 30A and transmitted through the reflection reducing layer 102 is 0.1 of the light (100%) incident on the circularly polarizing plate 30A. Because it is%, it will be about 0.1%. Therefore, the reflectance of the circularly polarizing plate 30A is about 0.1% because it is the sum of about 0% of the light L1 ′ and about 0.1% of the light L7.

According to the present embodiment, when the liquid crystal molecules 8a and the dichroic dye 8b of the liquid crystal cell 32 are in the horizontal alignment state (polarization mode H) (see FIG. 14), the circularly polarizing plate 30A is used in the light path instead of the reflection adjustment element 30. The reflectance is slightly increased from 0.1% to 4% as compared to the fifth comparative embodiment in which the arrangement is made. However, even at a reflectance of 4%, it is a sufficiently acceptable range as a reflection suppressing function.
Therefore, in the polarization mode H, the reflection adjustment element 30 of the present embodiment is judged to have substantially the same performance as the circularly polarizing plate 30A of the fifth comparative embodiment.

As described above, in the reflection adjusting system 300 of the present embodiment, as in the second embodiment described above, the polarization mode H is controlled by controlling the application of the voltage to the reflection adjusting element 30 according to the external light illuminance by the control unit 60. And non-polarization mode M can be switched.
When switching to the polarization mode H, the reflection function of the mirror member 101 can be reduced by functioning in the same manner as in the case where the circularly polarizing plate 30A is disposed instead of the reflection adjusting element 30 in the light path of the third comparative embodiment.
For example, when the mirror member 101 is used as a rearview mirror of a vehicle, glare is reduced by switching the reflection adjustment element 30 to the polarization mode H when the light of a following vehicle or the like enters the rearview mirror and is dazzling. Can.

Further, when switched to the non-polarization mode M, it functions in the same manner as when the reflection adjustment element 30 of the fourth comparative embodiment is omitted, and the transmittance can be improved as compared with the polarization mode H.
Therefore, when the mirror member 101 is used as a rearview mirror of a vehicle, it is not necessary to suppress the reflected light when the strong light is not incident on the rearview mirror, so the reflection adjustment system 300 The mode can be switched to the non-polarization mode M, which has high transmittance, so that the rear aspect of the vehicle can be well mirrored.
Furthermore, the reflection adjustment system 300 according to the present embodiment is provided with the reflection reducing layer on the surface of the reflection adjusting element 30, so that the reflected light on the surface of the reflection adjusting element 30 can be reduced. The rate can be further reduced than in the case of the second embodiment described above.

  In the above-described embodiments, specific numerical values are described as an example of the reflectance, but these numerical values can be appropriately adjusted according to the design specifications of the liquid crystal layer 8, the driving voltage, and the like.

(Modified form)
As mentioned above, although the suitable embodiment of this embodiment was described, the present invention is not limited to this.
In the above-described embodiment, the colored layer may be provided as a reflection reducing layer. Here, the colored layer is a layer colored in a specific color, and for example, a color filter can be applied. In this case, it is desirable that the color filter be provided on the surface on the quarter-wave plate side of the reflection adjustment element because it is necessary to consider the alignment between the pixels of the image display device 20 and the pixels of the color filter and parallax. .
In the first embodiment, a color filter may be provided on the image display surface 20 a of the image display device 20. Thereby, the reflection suppression effect of the reflection adjustment system 100 can be further improved.

  Further, in the first embodiment, the image display device 20 uses an image display element using an organic light emitting diode which is an image display panel by a self light emitting element, but is not limited thereto. R (red), G (green) Other self-luminous image display devices may be used, such as LEDs (B) and blue (B), provided for each pixel.

  Further, the photometry unit described in the first embodiment may be provided in the reflection adjustment system of the second embodiment and the third embodiment. In this case, the photometric unit is provided, for example, on the opposite side of the reflection adjustment element 30 to the mirror surface member, so as to automatically switch between the polarization mode H and the non-polarization mode M based on the photometric result of the photometric unit. It is also good.

  In addition, the reflection reduction layer 102 described in the third embodiment may be applied to the reflection adjustment system 100 of the first embodiment. In this case, for example, the reflection reducing layer can be disposed on the surface of the reflection adjusting element 30 on the liquid crystal cell 32 side.

  In addition, although the reflection adjustment system 100 according to the first embodiment has been described as an example in which the photometric unit 50 is provided, the present invention is not limited to this, and the photometric unit 50 may be omitted.

8 liquid crystal layer 8a liquid crystal molecule 8b dichroic dye 11 electrode 16 electrode 17 alignment layer 18 adhesive layer 20 image display device 20a image display surface 30 reflection control element 30a surface 31 wave plate 32 liquid crystal cell 32A linear polarization plate 50 photometry unit 60 control Section 100 reflection adjustment system 101 mirror surface 102 reflection reduction layer

Claims (6)

A liquid crystal cell comprising a liquid crystal layer containing a dichroic dye and liquid crystal molecules, and an electrode for generating an electric field in the liquid crystal layer by an applied voltage to change the directions of the liquid crystal molecules and the dichroic dye;
And a quarter wave plate stacked on the liquid crystal cell,
The liquid crystal cell is
Depending on the orientation of the liquid crystal molecules and the dichroic dye:
A non-polarization mode in which non-polarization light incident from the side opposite to the quarter-wave plate side is emitted to the quarter-wave plate side in the non-polarization state;
It is possible to switch the light in the non-polarization state, which is incident from the side opposite to the quarter-wave plate side, to the polarization mode in which the light is emitted to the quarter-wave plate side in the linear polarization state;
Reflection adjustment element characterized by A reflection adjusting element according to claim 1;
A control unit that controls a voltage applied to the electrode;
The control unit changes the applied voltage to the electrode, and the reflection adjustment element can be switched to the polarization mode or the non-polarization mode.
Reflection adjustment system characterized by A photometry unit disposed on the liquid crystal cell side of the reflection adjustment element;
The control unit is capable of switching the reflection adjustment element to the non-polarization mode or the polarization mode based on the photometry result by the photometry unit;
The reflection adjustment system according to claim 2, characterized in that The image display apparatus includes an image display surface which is disposed on the quarter wavelength plate side of the reflection adjusting element and whose luminance can be changed.
The control unit changes the brightness of the image display surface according to a photometric result by the photometric unit.
The reflection adjustment system according to claim 3, characterized in that A reflection reducing layer is disposed on the reflection adjusting element to reduce reflection;
The reflection adjustment system according to any one of claims 2 to 4, characterized in that In the liquid crystal layer, the transmittance when no electric field is generated is higher than the transmittance when an electric field is generated;
The reflection adjustment system according to any one of claims 2 to 5, characterized in that

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