JP2011207271A - Anti-glare device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To reduce glare by switching a straight-ahead moving state and a deflection state of incident light about each section with an optical deflection liquid crystal cell and bringing a section in which light intensity is reduced by deflection be into a deflection state with a drive device.SOLUTION: The anti-glare device is the optical deflection liquid crystal cell including a liquid crystal layer, a pair of transparent substrates, a pair of transparent electrodes where a superimposed part in a plane view forms an electrode pattern capable of applying a voltage on the liquid crystal layer about each section in a substrate surface, and a prism layer formed on one of the transparent substrates. The anti-glare device includes: the optical deflection liquid crystal cell capable of switching the straight-ahead moving state that the incident light cannot be bent by the prism layer and the deflection state that the incident light can be bent by the prism layer by changing the refractive index of the liquid crystal layer by voltage application about each section; a light intensity sensor measuring the intensity of light permeating through the optical deflection liquid crystal cell; and the drive device successively scanning the sections and switching each section from the straight-ahead moving state to the deflection state when the light intensity exceeds a predetermined threshold, and performing control to keep the deflection state of the section in the case that the light intensity measured by the light intensity sensor is lowered when switched to the deflection state, and return to the straight-ahead moving state in the case that the light intensity is not lowered.

Description

  The present invention relates to an anti-glare device that reduces glare.

  Various devices have been proposed as an anti-glare device that avoids direct sunlight on a vehicle driver (see, for example, Patent Documents 1 to 4). An anti-glare device that moves the sunshade to block light requires a mechanical drive mechanism, and for example, it is difficult to reduce the size of the drive mechanism. Also. An anti-glare device that shields a dazzling part is dark because a part of the driver's field of view is blocked. An anti-glare device that blocks light with a liquid crystal filter using a polarizing plate cannot increase the light transmittance during transmission without blocking light, and the polarizing plate has low durability against heat, ultraviolet rays, and the like. There is a need for new technology related to anti-glare devices.

  In addition, in a liquid crystal cell in which a prism is formed on one inner surface of a pair of substrates, a technique for changing the traveling direction of light by switching the applied voltage and changing the refractive index of the liquid crystal layer has been proposed (for example, Patent Documents). 5).

  In recent years, research on a cholesteric blue phase as a liquid crystal material has been promoted, and a technique for expanding the expression temperature range of the cholesteric blue phase by polymer stabilization treatment has been proposed (for example, see Patent Document 6).

Japanese Patent No. 3820425 JP 2002-87060 A JP 2003-165334 A Japanese Utility Model Publication No. 5-63929 JP 2009-26641 A JP 2003-327966 A

  An object of the present invention is to provide a novel technique relating to an antiglare device.

  According to one aspect of the present invention, there is provided a light deflection liquid crystal cell, a liquid crystal layer, a pair of transparent substrates that are arranged to face each other and sandwich the liquid crystal layer, and the liquid crystal layer side of the pair of transparent substrates A pair of transparent electrodes each formed above, wherein the overlapping portion in plan view forms an electrode pattern capable of applying a voltage to the liquid crystal layer for each section in the substrate surface; One of a pair of transparent substrates, and a prism layer formed above the liquid crystal layer side, and by changing the refractive index of the liquid crystal layer by applying a voltage for each section, incident light is reflected by the prism layer. A light deflection liquid crystal cell that can be switched between a straight state that is not bent and a deflection state in which incident light is bent by the prism layer, and a light intensity that measures the intensity of the incident light when light transmitted through the light deflection liquid crystal cell enters. Sensor and said light intensity When the light intensity measured by the sensor is equal to or greater than a predetermined threshold, the sections are sequentially scanned, and each section is switched from the straight traveling state to the deflection state, and then switched to the deflection state. When the light intensity measured by the light intensity sensor decreases, an anti-glare device is provided that has a drive device that maintains the deflection state of the section, and otherwise returns to the straight-ahead state.

  The light deflection liquid crystal cell can switch between a straight traveling state and a deflecting state of incident light for each section. The drive device can reduce the glare by setting the section where the light intensity is reduced by the deflection to the deflected state.

FIG. 1 is a cross-sectional view in the thickness direction schematically showing an optical deflection liquid crystal cell according to a first embodiment of the present invention. 2A is a schematic perspective view of the prism layer of the first embodiment (and the second embodiment) and a cross-sectional view of the prism, and FIG. 2B is a transparent electrode facing the first embodiment (and the second embodiment). It is a top view which shows roughly the example of a pattern. FIG. 3 is a schematic perspective view showing a structure of a blue phase (blue phase I). FIG. 4 is a schematic side view of an automobile provided with the antiglare device of the embodiment. FIG. 5 is a schematic optical path diagram showing the operation of the anti-glare device of the embodiment. FIG. 6A is a schematic sketch of the scenery seen from the driver when the anti-glare device of the embodiment is operating, and FIG. 6B is a diagram illustrating another example of the installation position of the light intensity sensor. . 7A to 7D are schematic cross-sectional views showing light deflecting liquid crystal cells in which the substrate is disposed with an inclination from the vertical direction. FIG. 8A is a cross-sectional view in the thickness direction schematically showing one layer of a liquid crystal cell of the light deflecting liquid crystal cell of the second embodiment, and FIG. 8B is a stacked cell of the light deflecting liquid crystal cell of the second embodiment. FIG. 4 is a schematic cross-sectional view in the thickness direction of FIG. 2 and a schematic optical path diagram of a light beam transmitted through the light deflecting liquid crystal cell of the second embodiment.

  First, the structure and manufacturing method of the light deflection liquid crystal cell according to the first embodiment of the present invention will be described.

  FIG. 1 is a cross-sectional view in the thickness direction schematically showing the light deflection liquid crystal cell of the first embodiment. A pair of transparent substrates 1 and 11 are prepared. The transparent substrates 1 and 11 are, for example, glass substrates, and have a size of, for example, a width of 1000 mm, a length of 150 mm to 200 mm, and a thickness of 0.7 mmt, respectively.

  A transparent electrode 12 is formed on one substrate 11. The transparent electrode 12 is made of, for example, indium tin oxide (ITO) and has a thickness of 150 nm.

  A prism layer 3 is formed on the other substrate 1 on which no transparent electrode is formed. The prism layer 3 has a shape in which the prisms 3a are arranged on the base layer 3b. The base layer 3b has a thickness of about 2 μm to 30 μm, for example.

  FIG. 2A is a schematic perspective view of the prism layer 3 of the first embodiment and a cross-sectional view (perpendicular to the length direction) of the prism 3a. Each prism 3a has, for example, a triangular prism shape with an apex angle of 75 °, a base angle of 15 °, and a 90 °, and a plurality of prisms 3a are arranged in a direction perpendicular to the prism length direction with the directions of the inclined surfaces aligned. . The height of the prism 3a is, for example, 5.2 μm, and the length of the base of the prism 3a (prism pitch) is, for example, 20 μm.

  A suitable material for the prism layer 3 will be described. In the subsequent main sealant firing step of the liquid crystal cell, for example, heat treatment at 150 ° C. or higher is performed. Further, in the subsequent transparent electrode forming step on the prism layer 3, for example, a heat treatment at 180 ° C. or higher is performed in order to form a transparent electrode with high transparency (low resistance). Therefore, a prism material is desired that does not easily deteriorate in characteristics with respect to heat treatment at a high temperature (for example, 150 ° C. or higher).

  The inventor of the present application performed heat treatment at 220 ° C. for 2 hours for a plurality of prism materials, and evaluated the difference in transmittance in the visible light region before and after the heat treatment. As a result, the acrylic ultraviolet (UV) curable resin showed a slight decrease in transmittance on the short wavelength side, but exhibited a transmittance equivalent to that before the heat treatment in almost all visible wavelength regions. Rate) change was found to be less. In the present specification, “there is little change in characteristics (transmittance)” means that the change in characteristics (transmittance) in the visible light region (wavelength 380 nm to 780 nm) is approximately within 2% compared to before heat treatment. Indicates the state.

  The acrylic UV curable resin has not only heat resistance but also excellent adhesion to glass and has a property of being difficult to adhere to metal (good releasability). Suitable as a material. Epoxy resins are also excellent in heat resistance and are considered to be usable as prism materials. Polyimide can also be used.

  Next, a method for producing the prism layer 3 will be described. Acrylic UV curable resin is dropped on the substrate 1, and a mold on which the prism layer 3 is formed is placed at a predetermined position on the substrate 1, and a thick quartz member or the like is placed on the back side of the substrate for reinforcement. Press in the state. The dripping amount of the UV curable resin can be adjusted according to the size of the prism forming region.

After being pressed and allowed to stand for 1 minute or longer to sufficiently spread the UV curable resin, ultraviolet rays are irradiated from the back side of the substrate 1 to cure the UV curable resin. The irradiation amount of ultraviolet rays is, for example, about 20 J / cm ² . What is necessary is just to set suitably the irradiation amount of an ultraviolet-ray so that resin may harden | cure. Note that a minute groove for air bleeding may be formed on the prism forming die. Further, the mold and the substrate may be superposed in a vacuum.

  Next, the substrate 1 on which the prism layer 3 is formed is washed with a washing machine. For example, brush cleaning using an alkaline detergent, pure water cleaning, air blowing, UV irradiation, and infrared (IR) drying can be sequentially performed. The cleaning method is not limited to this, and high-pressure spray cleaning, plasma cleaning, or the like may be performed.

Returning to FIG. 1, the description will be continued. Further, a transparent electrode 22 made of, for example, ITO is formed on the prism layer 3. Although the transparent electrode 22 can be formed directly on the prism layer 3, for example, an SiO ₂ film 21 may be interposed to improve adhesion. For example, the SiO ₂ film 21 is formed to a thickness of 50 nm by sputtering (AC discharge) at a substrate temperature of 80 ° C.

Next, on the SiO ₂ film 21, for example, an ITO film having a thickness of 100 nm is formed by sputtering (AC discharge) at a substrate temperature of 100 ° C. to form the transparent electrode 22. After the ITO film is formed, for example, baking is performed at 220 ° C. for 1 hour in order to improve the transparency and conductivity of the ITO film.

  In addition to sputtering, vacuum deposition, ion beam method, chemical vapor deposition (CVD), or the like can be used as a film forming method. Also in this case, it is desirable to perform baking at, for example, 220 ° C. for about 1 hour in order to improve transparency and conductivity of the ITO film.

  Next, the transparent electrode 12 on the substrate 11 and the transparent electrode 22 above the prism layer 3 of the substrate 1 are patterned. The transparent electrodes 12 and 22 using ITO can be patterned by, for example, wet etching using ferric chloride using, for example, a resist pattern by photolithography as a mask.

  FIG. 2B is a plan view schematically showing a pattern example of the transparent electrodes 12 and 22. The pattern in the state in which the liquid crystal cell was formed is shown. The transparent electrode 12 is a pattern in which horizontally long lines in the figure are arranged in the vertical direction at intervals of 0.5 mm, for example, with a width of 99.5 mm. The transparent electrode 22 has long lines in the figure with a width of, for example, 99.5 mm. The pattern is arranged in the horizontal direction at intervals of 0.5 mm. The pattern formed on the transparent electrode 22 on the prism layer 3 can be easily patterned when the line length direction is aligned with the prism length direction.

  The overlapping portion of the electrodes 12 and 22 forms an electrode pattern in which rectangular sections are arranged in a matrix (dot matrix electrode shape). By selecting each line of the transparent electrodes 12 and 22, the voltage application state to the liquid crystal layer can be controlled for each section defined by the overlap of the selected lines.

  Note that the width of each partition can be changed by appropriately adjusting the width of each line of the transparent electrodes 12 and 22. It is also possible to have a structure in which the width of the compartments is not uniform in the plane.

  Next, the substrates 1 and 11 are washed with a washing machine. For example, brush cleaning using an alkaline detergent, pure water cleaning, air blowing, UV irradiation, and infrared (IR) drying are sequentially performed. The cleaning method is not limited to this, and high-pressure spray cleaning, plasma cleaning, or the like can also be performed.

  Next, a main sealant 16 containing a gap control agent, for example, 2 wt% to 5 wt% is formed on the substrate 1. As a forming method, screen printing or a dispenser can be used. The gap control agent is selected so that the thickness of the liquid crystal layer 15 (from the prism base layer 3b) including the height of the prism 3a is, for example, 10 μm to 20 μm. For example, Sekisui Chemical plastic balls having a diameter of 30 μm are used as the gap control agent, and 4 wt% of this is added to Mitsui Chemicals sealant ES-7500 to form the main sealant.

  On the other substrate 11, as a gap control agent 14, for example, plastic balls made of Sekisui Chemical having a diameter of 17 μm are spread using a dry gap spreader.

  Next, both the substrates 1 and 11 are overlapped, and heat treatment is performed in a state where a pressure is constantly applied by a press machine or the like, thereby curing the main sealant and forming an empty cell. For example, heat treatment is performed at 150 ° C. for 3 hours.

  Next, a liquid crystal material 15 is formed by vacuum injection of a liquid crystal material into the empty cell. After liquid crystal injection, an end sealant is applied to the injection port to seal the liquid crystal cell. Note that the method for forming the liquid crystal layer is not limited to vacuum injection, and, for example, a One Drop Fill (ODF) method may be used.

  As a liquid crystal material for forming the liquid crystal layer 15, in the first embodiment, liquid crystal molecules having positive dielectric anisotropy Δε are included, and a cholesteric blue phase (hereinafter referred to as a blue phase) when no voltage is applied (within a predetermined temperature range). It may be called).

  For example, the following liquid crystal material is used. A ratio of 1: 1 between JC1041-XX (manufactured by Chisso, Δn: 0.142) and 4-cyano-4′-pentylbiphenyl (5CB) (manufactured by Merck, Δn: 0.184), which are liquid crystals exhibiting a cholesteric blue phase 5.6% of a chiral agent ZLI-4572 (manufactured by Merck) is added thereto.

  And the mixed monomer which mixed the monofunctional material and the bifunctional material is added as a photopolymerizable monomer. For example, 2-ethylhexylacrylate (EHA) (manufactured by Aldrich) is used as a monofunctional material, and RM257 (manufactured by Merck) is used as a bifunctional material, and these are mixed so as to have a molar ratio of 70:30.

  In addition, 2,2-dimethyl-2-phenylacetophenone (DMPDP) is used as a photopolymerization initiator, and this is added so as to be 5 mol% with respect to the mixed monomer.

  The photopolymerizable mixed monomer to which the photopolymerization initiator is added is added so as to be 8 mol% with respect to the mixed liquid crystal to which the chiral agent is added. In this way, the liquid crystal material for forming the liquid crystal layer 15 is adjusted. In addition, a liquid crystal, a chiral agent, a photopolymerizable monomer, and a photoinitiator are not limited to these. However, the photopolymerizable monomer is desirably mixed with a monofunctional monomer and a bifunctional monomer.

  When the liquid crystal cell thus formed is heated, a blue phase is exhibited in a narrow temperature range around 60 ° C. While maintaining the temperature exhibiting the blue phase, the liquid crystal cell is irradiated with ultraviolet rays to polymerize the photopolymerizable monomer to form a polymer network, thereby stabilizing the polymer of the blue phase.

For example, the following ultraviolet irradiation is performed. First, the irradiation sequence which repeats the irradiation sequence which will be 10 second non-irradiation after 1 second irradiation is performed 10 times. And after intermittent irradiation, continuous irradiation for 3 minutes is performed. The ultraviolet intensity is, for example, 30 mW / cm ² (365 nm). Note that the exposure conditions are not limited to this, and for example, the intensity of ultraviolet rays can be further reduced (however, the time required for photopolymerization becomes longer).

  The liquid crystal cell subjected to the polymer stabilization treatment exhibits a blue phase in a wide temperature range of about −5 ° C. to 60 ° C. It should be noted that the temperature range showing the blue phase by the polymer stabilization treatment can be expanded by adjusting the liquid crystal material used, the mixing ratio thereof, the polymerization conditions, and the like.

  As described above, the light deflection liquid crystal cell of the first embodiment is manufactured. Next, the operation of the light deflection liquid crystal cell of the first embodiment will be described.

  The light deflecting liquid crystal cell of the example exhibits a blue phase when no voltage is applied. The following is a general description of the blue phase: commentary on the Kikuchi laboratory website (http://kikuchi-lab.cm.kyushu-u.ac) .jp / kikuchilab / bluephase.html).

  The blue phase is optically isotropic, blue phase I having body-centered cubic symmetry, blue phase II having simple cubic symmetry, and blue phase III having isotropic symmetry. There are types. Blue phase I appears on the coldest side and blue phase III appears on the hottest side. The light deflection liquid crystal cell of this embodiment uses a blue phase I.

  FIG. 3 is a schematic perspective view showing the structure of the blue phase I (according to the above-mentioned commentary article). In the blue phase, the liquid crystal molecules in the vicinity of the center are formed in a structure in which double-twisted cylinders Cy, which are aggregates of liquid crystal molecules that are allowed to twist in all lateral directions, are assembled in a lattice shape orthogonal to each other. Yes.

  Since the blue phase is optically isotropic, the refractive index of the liquid crystal layer viewed from the normal direction of the substrate of the light deflecting liquid crystal cell of the first embodiment is the ordinary ray refractive index no and the extraordinary ray refraction of the liquid crystal material. The average value of the rate ne is (2no + ne) / 3, and is equal for both of the polarization components orthogonal to each other of the incident light (light traveling in the normal direction of the substrate) to the light deflection liquid crystal cell.

  On the other hand, in the light deflecting liquid crystal cell of the first embodiment, when a sufficiently high voltage (which varies depending on the cell configuration, for example, about 20 V) is applied, the voltage is applied in the thickness direction of the liquid crystal layer, and positive dielectric anisotropy As a result, the twisted structure of the liquid crystal molecules in the blue phase is eliminated, and almost all the liquid crystal molecules rise in the normal direction of the substrate, indicating a homeotropic phase.

  In the homeotropic phase, the refractive index of the liquid crystal layer viewed from the normal direction of the substrate is an ordinary ray refractive index no, and polarized light beams incident on the light deflection liquid crystal cell (light rays traveling in the normal direction of the substrate) are orthogonal to each other. Equal in both components.

  In the first embodiment, the ordinary ray refractive index no of the liquid crystal material is 1.521, and the extraordinary ray refractive index ne is 1.683. Therefore, the refractive index of the liquid crystal layer with respect to incident light is estimated to be about 1.574 in the blue phase when no voltage is applied and 1.521 in the homeotropic phase when voltage is applied, regardless of the polarization direction. The refractive index of the prism material is 1.51.

  As described above, the light deflecting liquid crystal cell of the first embodiment deflects incident light by the action of the prism because the refractive index of the liquid crystal layer and the prism layer is different when no voltage indicating the blue phase is applied (when the voltage is off). Will be. On the other hand, when a voltage indicating a homeotropic phase is applied (when the voltage is on), the refractive indexes of the liquid crystal layer and the prism layer are equal, and the incident light travels almost straight. These actions do not depend on the polarization direction of the incident light, and both polarization components of the incident light can be deflected and traveled straight.

  The difference between the refractive index of the first member and the refractive index of the second member is within 2% (more preferably within 1%) with respect to the refractive index of the first member or the refractive index of the second member. In this case, it is assumed that the refractive indexes of both members are equal.

  The electrode pattern of the embodiment divides the substrate surface into a plurality of sections. By switching the voltage off state and the voltage on state for each section, the deflection state and the straight traveling state can be switched.

  In addition, although the example in which the refractive indexes of the liquid crystal layer and the prism layer are equal when the voltage is on is described, the refraction of the liquid crystal layer and the prism layer is performed when the voltage is off (although a prism material having a high refractive index is required). The rate may be the same. In this case, when the voltage is off, a straight traveling state is obtained, and when the voltage is on, the deflection state is obtained.

  In the light deflection liquid crystal cell of the first embodiment, a transparent electrode is formed on the prism layer in the substrate on the prism layer side. It is possible to perform light deflection even in a light deflection liquid crystal cell having a structure in which a transparent electrode on the prism layer side is formed on a substrate, a prism layer is formed on the transparent electrode, and voltage is applied to the liquid crystal layer through the prism layer. Is possible. However, the drive voltage can be reduced by forming the transparent electrode on the prism layer.

  The light deflection liquid crystal cell of the first embodiment has a high response speed at room temperature, for example, about 200 μsec at the rise from the blue phase to the homeotropic phase, and about 20 μsec at the fall from the homeotropic phase to the blue phase, for example. It is.

  Next, an antiglare device using the light deflection liquid crystal cell of the first embodiment will be described. The anti-glare device of the present embodiment is installed in an automobile. For example, strong light from the sun enters the vehicle interior through the windshield and reduces glare felt by the driver.

  FIG. 4 is a schematic side view of an automobile provided with the antiglare device of the embodiment. The light deflection liquid crystal cell 31 is disposed in the upper part on the windshield. A light intensity sensor 32 for measuring the light intensity is attached to the headrest of the driver's seat.

  The windshield surface may be inclined from the vertical direction. In the light deflection liquid crystal cell 31 arranged on the inclined front glass surface, it is likely that dazzling light is likely to enter the substrate from an oblique direction.

  As described above with respect to the principle of operation, in the vertically aligned homeotropic phase (when voltage is applied), light incident from the substrate normal direction, that is, light traveling parallel to the optical axis direction (major axis direction) of liquid crystal molecules, It was assumed that both polarization components felt an ordinary ray refractive index.

  However, in the vertically aligned homeotropic phase, the effect of refractive index anisotropy is slight for incident light from an orientation of about 30 ° or less from the major axis direction of the liquid crystal molecules, and the characteristics are almost isotropic. Is obtained. Accordingly, the characteristics of the light deflection liquid crystal cell 31 that are substantially the same as those when light is incident from the normal direction of the substrate can be obtained until the inclination angle of the windshield surface from the vertical direction is within about 30 °. Let's go.

  Since the blue phase (when no voltage is applied) is isotropic, the refractive index does not depend on the incident direction. Note that even if the angle of inclination of the windshield from the vertical direction becomes larger (even if it becomes more obliquely incident), the operation of the light deflection liquid crystal cell 31 does not become impossible at all.

  FIG. 5 is a schematic optical path diagram showing the operation of the anti-glare device of the embodiment. In addition to the light deflection liquid crystal cell 31 and the light intensity sensor 32, the antiglare device further includes a drive device 33 that drives the light deflection liquid crystal cell 31.

  In the reference state, the light deflection liquid crystal cell 31 has the entire surface in a straight-on state where the voltage is on, and the incident light is transmitted as it is. The driver can see the same scenery as when the light deflection liquid crystal cell 31 is not disposed.

  At some point, strong light from the light source LS such as the sun passes through the light deflection liquid crystal cell 31 and enters the driver's eyes, and the driver feels dazzling. At the same time, strong light also enters the light intensity sensor 32 disposed in the vicinity of the driver's eyes.

  Data corresponding to the light intensity measured by the light intensity sensor 32 is transmitted to the driving device 33. The drive device 33 stores a light intensity that the driver feels dazzling as a threshold value, and determines whether the measured light intensity is equal to or greater than the threshold value.

  When it is determined that the light intensity is equal to or higher than the threshold value, the driving device 33 starts scanning the section of the light deflection liquid crystal cell 31. The sections on the entire surface are sequentially scanned so that each section is switched from the voltage on state to the voltage off state, that is, each section is switched from the straight traveling state to the deflected state.

  The section 31a through which the light beam from the light source LS transmits, which is the cause of the glare, is switched from the straight traveling state to the deflected state, so that the light path of the dazzling light beam from the optical path LP1 reaching the vicinity of the eyes of the driver, The light intensity measured by the light intensity sensor 32 is lowered by turning to the optical path LP2 that reaches the place deviated from the vicinity of the driver's eyes. The light deflection liquid crystal cell 31 is installed on the windshield with the prism length direction as a horizontal direction, for example, and bends light upward, for example.

  On the other hand, even if the section 31b that does not transmit light from the light source LS that does not cause glare is switched from the straight traveling state to the deflecting state, the light intensity measured by the light intensity sensor 32 does not change substantially. It should be noted that the light intensity measured by the light intensity sensor 32 may be slightly increased or slightly decreased by switching the section 31b that does not transmit the light from the light source LS to the deflected state.

  The drive device 33 maintains the deflected state in the section where the light intensity is reduced. Thereby, reduction of glare is achieved. On the other hand, the section where the light intensity does not change or rises is returned to the straight traveling state. Thereby, the view of the scenery as usual is maintained in the section that does not contribute to the reduction of the glare. In addition, in the section made into the deflection state, the scenery of a part slightly off from the scenery seen in the straight traveling state can be seen.

  In order to reduce the number of sections in the deflected state (change in appearance), the deflected state is maintained when the light intensity drop is greater than or equal to a predetermined intensity (when greatly contributing to the reduction in glare). If this is not the case, the vehicle can be returned to the straight state.

  In addition, after an anti-glare operation is once performed (after the light intensity is determined to be equal to or higher than the threshold, scanning is performed and the state of each section is determined), an appropriate interval (for example, after a few minutes), All sections are returned to the straight-ahead state (returned to the reference state), and it can be determined whether a strong light intensity equal to or higher than the threshold is still measured. If the light intensity is weaker than the threshold value, the reference state is maintained as it is. If a strong light intensity still higher than the threshold is measured, the light can be deflected again by performing another scan.

  FIG. 6A is a schematic sketch of the scenery seen from the driver when the anti-glare device of the embodiment is operating. A section through which direct sunlight is transmitted (shown by a broken line) is deflected so that the direct sunlight does not enter the driver's eyes. On the other hand, the surrounding sections remain straight and the scenery such as traffic lights is seen as usual.

  FIG. 6B is a diagram illustrating another example of the installation position of the light intensity sensor 32. The light intensity sensor 32 can also be disposed in the vicinity of the driver's eyes by attaching it to a frame of glasses or a headband. If necessary, the light intensity sensors 32 can be arranged at a plurality of locations.

  In addition, it seems that the amount of information for the driver is larger in the landscape in front of the vehicle than in the landscape in the upper front. For example, in order to better cope with such a situation, the section of the light deflection liquid crystal cell arranged on the windshield is narrower (finer) toward the lower side (relatively straight forward side in the light deflection liquid crystal cell surface). ) By doing so, it becomes easier to deflect a dazzling portion in a limited manner toward the lower side in the plane of the light deflection liquid crystal cell.

  When the light deflection liquid crystal cell is installed on the windshield surface inclined from the vertical direction, it is preferable that the prism arrangement is as follows.

  With reference to FIGS. 7A-7D, a preferred prism arrangement will be discussed. 7A to 7D are schematic cross-sectional views showing a state in which the light deflection liquid crystal cells are arranged with the substrate inclined from the vertical direction. In each of FIGS. 7A and the like, the up and down direction on the paper indicates the vertical up and down direction, the right side indicates the driver side, and the left side indicates the driver front side.

  7A and 7C show the arrangement in which the substrate PR with the prism layer is placed on the driver side and the substrate SB without the prism is placed on the front side with respect to the liquid crystal layer LC, and FIGS. 7B and 7D show the liquid crystal layer LC. The substrate PR with the prism layer is placed on the front side, and the substrate SB without the prism is placed on the driver side.

  7A to 7D, the prisms of the substrate PR with the prism layer are arranged in the vertical direction with the length direction being horizontal (perpendicular to the paper surface). 7A and 7B show an arrangement in which the prism slope is closer to the horizontal direction than the substrate surface (for example, the liquid crystal layer side surface of the substrate SB without prisms), and FIGS. 7C and 7D show the prism rather than the substrate surface. This is an arrangement in which the slope is in the direction of a prism that is nearly vertical.

  When the prism slope is nearly horizontal, the proportion of the prism slope in the observer's field of view decreases. That is, it is difficult to obtain a desired refraction effect by the prism slope portion (prism long side portion). On the contrary, the proportion of the stepped portion of the prism (prism short side portion) in the field of view increases.

  Therefore, compared to the prism arrangement in which the prism slope is closer to the horizontal than the substrate surface as shown in FIGS. 7A and 7B, the prism arrangement in which the prism slope is closer to the vertical than the substrate surface as shown in FIGS. 7C and 7D. Is preferable.

  The description will be continued assuming that the refractive index of the liquid crystal layer LC is higher than the refractive index of the prism layer or the transparent substrate. The light incident from the high refractive index liquid crystal layer LC side may be totally reflected at the interface with the low refractive index substrate PR with prism layer or the substrate SB without prism.

  7C and 7D, the total reflection at the interface between the liquid crystal layer LC and the front substrate is more disturbed by the driver than the total reflection at the interface between the liquid crystal layer LC and the driver side substrate. It may be easy to do. This is because the downward direction that is preferably not visible may be visible to the driver due to total reflection.

  The interface between the liquid crystal layer LC and the front substrate is due to the prism-less substrate SB in the arrangement of FIG. 7C, and is due to the prism-equipped substrate PR in the arrangement of FIG. 7D. Compared with the arrangement in FIG. 7C, the arrangement in FIG. 7D has the interface between the liquid crystal layer LC and the front substrate closer to the vertical due to the prism slope. For this reason, it can be said that the arrangement of FIG. 7D is an arrangement in which, even if total reflection occurs, the possibility of reflected light entering the eyes of the driver is low, and the visual field is less likely to be disturbed.

  In summary, the angle between the vertical direction and the prism slope (prism long side) is smaller than the angle between the vertical direction and the substrate (the prism slope is closer to the vertical than the substrate) (see FIG. 7C). 7D), and it is more preferable to arrange the prism layer in front of the liquid crystal layer (FIG. 7D).

  As described above, the light deflection liquid crystal cell of the embodiment can be switched between the deflection state and the straight traveling state of the incident light for each section. An antiglare device using such a light deflection liquid crystal cell can reduce glare by setting a section through which a dazzling light beam is transmitted to a deflected state.

  In the antiglare device of the above-described embodiment, the section for performing light deflection is automatically selected (the driver does not need to manually shield the light by moving the sun visor), so that driving safety can be improved.

  In an anti-glare device that blocks out a dazzling part, a part of the field of view becomes dark and unnatural, but the anti-glare device of the example shows an unnatural part because the scene of the dazzling section can be seen slightly off. There is little. Non-dazzling sections can be maintained in the normal view.

  In addition, although the anti-glare apparatus of an Example uses a liquid crystal element, the light deflection liquid crystal cell of an Example does not use a polarizing plate, For example, it can be set as the high light transmittance of 90% or more. It is. A high light transmittance is suitable for disposing in a window such as a windshield.

  The light deflection liquid crystal cell of the first embodiment uses switching between a blue phase and a homeotropic phase. Thereby, with one liquid crystal cell, it is possible to simultaneously switch between deflection and straight travel for both polarization components of incident light. In addition, since the response is fast, it is suitable for high-speed scanning of the entire section when used in an anti-glare device.

  Next, the light deflection liquid crystal cell of the second embodiment will be described. In the first embodiment, a liquid crystal exhibiting a blue phase is used. However, as described in the second embodiment, a light deflection liquid crystal cell can be formed even by using a nematic liquid crystal that is a general liquid crystal. However, in the second embodiment, an optical deflection liquid crystal cell is manufactured by stacking two liquid crystal cells.

  FIG. 8A is a cross-sectional view in the thickness direction schematically showing a liquid crystal cell for one layer of the light deflection liquid crystal cell of the second embodiment. As in the first embodiment, a pair of transparent substrates 1 and 11 are prepared. However, in the second embodiment, transparent electrodes 2 and 12 (for example, made of ITO and having a thickness of 150 nm) are formed on both substrates 1 and 11, respectively.

  Next, the transparent electrode 12 on the substrate 11 and the transparent electrode 2 on the substrate 1 are patterned. The pattern of the transparent electrodes 12 and 2 is the same as the pattern of the transparent electrodes 12 and 22 of the first embodiment (for example, the transparent electrode 22 of the first embodiment is replaced with the transparent electrode 2 of the second embodiment). Yes (see FIG. 2B). That is, by selecting each line of the transparent electrodes 12 and 2, the voltage application state to the liquid crystal layer can be controlled for each section defined by the overlap of the selected lines.

  Next, the prism layer 3 is formed on the transparent electrode 2 of the substrate 1. The prism layer 3 has, for example, the same shape as the prism layer of the first embodiment (see FIG. 2A), and is formed in the same manner as the prism layer of the first embodiment. However, in the second embodiment, the prism layer 3 is formed on the transparent electrode 2. Since the transparent electrode 2 using ITO absorbs ultraviolet rays, the amount of ultraviolet rays irradiated for curing the prism layer 3 is desirably adjusted according to the film thickness of the transparent electrode 2. Further, as in the first embodiment, the substrate 1 on which the prism layer 3 is formed is cleaned by a cleaning machine.

  Next, the alignment film 13 is formed of polyimide or the like on the transparent electrode 12 of the substrate 11. For example, an SE-410 made by Nissan Chemical is formed by flexographic printing to a thickness of 80 nm and baked at 180 ° C. for 1.5 hours. The alignment film 13 may be formed by inkjet, spin coating, slit coating, or slit and spin coating.

  Next, a rubbing process is performed on the prism layer 3 above the substrate 1. The rubbing direction is made parallel to the prism length direction so that the major axis direction of the liquid crystal molecules is aligned with the prism length direction. The rubbing process is also performed on the alignment film 13 above the substrate 11 so as to be anti-parallel alignment when the substrate 1 and the cell are formed.

  Next, as in the first embodiment, for example, the one substrate 1 is formed so that the thickness of the liquid crystal layer 15 (from the prism base layer 3b) including the height of the prism 3a is, for example, 10 μm to 20 μm. A main sealant 16 containing a gap control agent is formed thereon, a gap control agent 14 is dispersed on the other substrate 11, the substrates 1 and 11 are overlapped, and the main sealant is cured, An empty cell is formed.

  Next, a liquid crystal material 15 is formed by vacuum injection of a liquid crystal material into the empty cell. The method for forming the liquid crystal layer is not limited to vacuum injection, and for example, an ODF method may be used.

  In the second embodiment, a nematic liquid crystal having a positive dielectric anisotropy Δε is used for the liquid crystal layer 15. As the liquid crystal material of the second embodiment, for example, a product manufactured by Dainippon Ink & Chemicals with Δn = 0.298, having an ordinary ray refractive index no of 1.525 and an extraordinary ray refractive index ne of 1.823. Can be used. The refractive index of the prism material is 1.51, for example.

  In the second embodiment, the ordinary ray refractive index no is equal to that of the prism material, and the extraordinary ray refractive index ne is selected to be different from that of the prism material. Thus, when the liquid crystal layer exhibits an extraordinary ray refractive index ne, the prism layer deflects incident light, and when the liquid crystal layer exhibits an ordinary ray refractive index no, the incident light travels straight as it is (the direction of the prism layer is changed). Can't bend).

  After liquid crystal injection, an end sealant is applied to the injection port to seal the liquid crystal cell. After sealing, for example, heat treatment is performed at 120 ° C. for 1 hour to adjust the alignment state of the liquid crystal. Thus, the first liquid crystal cell of the light deflection liquid crystal cell of the second embodiment is manufactured.

  In the same manner, a second liquid crystal cell is also produced. However, the rubbing direction of the second liquid crystal cell is different from that of the first liquid crystal cell. In the first liquid crystal cell, the rubbing direction was made parallel to the prism length direction. In the second liquid crystal cell, the rubbing direction is orthogonal to the prism length direction.

  For the prism layer 3 of the substrate 1 of the second liquid crystal cell, for example, a rubbing process is performed in a direction of going up the prism slope. The alignment film 13 of the counter substrate 11 is subjected to a rubbing process so that antiparallel alignment is obtained when cells are formed.

  The first and second liquid crystal cells are stacked such that the prism length directions are aligned and the sections are exactly overlapped in plan view, thereby producing the light deflection liquid crystal cell of the second embodiment.

  Next, the operation of the light deflection liquid crystal cell of the second embodiment will be described with reference to FIG. 8B. FIG. 8B is a schematic cross-sectional view in the thickness direction of the light deflection liquid crystal cell of the second embodiment, and also shows a schematic optical path of incident light (incident from the substrate normal direction) and outgoing light. .

  The light deflection liquid crystal cell 41 is formed by laminating first and second liquid crystal cells 41a and 41b. For example, the first liquid crystal cell 41a is disposed on the light source side, and the second liquid crystal cell 41b is disposed on the opposite side.

  The corresponding sections of the first and second liquid crystal cells 41a and 41b are controlled to the same voltage application state (off state or on state). First, the operation in the section 41c in the voltage off state will be described.

  In the section 41c in the voltage-off state, in the first liquid crystal cell 41a, the major axis direction of the liquid crystal molecules Ma is aligned with the prism length direction (direction perpendicular to the paper surface). The major axis direction of the molecule Mb is aligned in a direction orthogonal to the prism length direction.

  The liquid crystal layer of the first liquid crystal cell 41a exhibits an extraordinary ray refractive index ne with respect to the polarization component La in the prism length direction of incident light. As a result, the polarization component La is deflected by the prism of the first liquid crystal cell 41a.

  On the other hand, for the polarization component Lb perpendicular to the prism length direction of the incident light, the liquid crystal layer of the first liquid crystal cell 41a exhibits the ordinary ray refractive index no, and the polarization component Lb is not bent by the prism, Go straight through the first liquid crystal cell.

  The liquid crystal layer of the second liquid crystal cell 41b exhibits an extraordinary ray refractive index ne with respect to the polarization component Lb that has been transmitted straight through the first liquid crystal cell 41a. Thereby, the polarization component Lb is deflected by the prism of the second liquid crystal cell 41b.

  For the polarization component La deflected by the first liquid crystal cell 41a, the liquid crystal layer of the second liquid crystal cell 41b exhibits an ordinary ray refractive index no, and the polarization component La is not reflected by the prism of the second liquid crystal cell. The direction is not changed, and the light travels in the direction deflected by the first liquid crystal cell 41a. In this way, both polarization components of the incident light are deflected in the section 41c in the voltage-off state.

  Next, the operation in the voltage-on state section 41d will be described. Since the liquid crystal molecules have a positive dielectric anisotropy, the major axis direction of the liquid crystal molecules Ma and Mb is the substrate normal direction in both the first and second liquid crystal cells 41a and 41b in the voltage-on section 41d. It is aligned.

  The liquid crystal layers of the first and second liquid crystal cells 41a and 41b have the ordinary ray refractive index no for both the polarization component La in the prism length direction of the incident light and the polarization component Lb orthogonal to the prism length direction. Indicates. Therefore, the polarization components La and Lb go straight without being bent by the prisms of either the first or second liquid crystal cell. In this way, the incident light travels straight in the section 41d in the voltage-on state.

  Thus, also in the light deflection liquid crystal cell of the second embodiment, the deflection / straightness of incident light can be controlled for each section. Therefore, the anti-glare device using the light deflecting liquid crystal cell of the second embodiment can be manufactured in the same manner as the anti-glare device using the light deflecting liquid crystal cell of the first embodiment (see FIGS. 4 to 6). .

  However, the second light deflection liquid crystal cell has a laminated structure of two liquid crystal cells in order to deflect both polarization components of incident light. Even in a light deflection liquid crystal cell using only one layer of liquid crystal cell, one polarization component can be deflected, so that a certain degree of effect can be obtained by using it in an anti-glare device.

  The response speed of the liquid crystal cell of the second embodiment using nematic liquid crystal is, for example, 50 msec at the rise and about 200 msec at the fall at room temperature, and the liquid crystal cell of the first embodiment using the blue phase liquid crystal. Slower than the response speed of. However, it is sufficiently fast compared to manual switching.

  In the liquid crystal cell of the second embodiment, the transparent electrode on the prism layer side may be formed on the prism layer as in the first embodiment.

  In the above embodiment, 15 ° is given as an example of the prism tilt angle. However, the prism tilt angle can be changed as necessary so that a light deflection angle suitable for the anti-glare device can be obtained. Note that the dimensions of the light deflection liquid crystal cell, the width of each section, and the like can be changed as necessary.

  In addition, although the anti-glare device for automobiles in which the light deflection liquid crystal cell is disposed on the windshield of the automobile has been described as an example, an anti-glare device used in other places may be manufactured. For example, an anti-glare device for a motorcycle in which a light deflection liquid crystal cell is arranged in a goggle portion of a motorcycle helmet, and an indoor anti-glare device in which a light deflection liquid crystal cell is arranged in a window of a building are also conceivable.

  In the case of an antiglare device for automobiles, the light deflection liquid crystal cell is not fixed on the windshield, but is movable (such as the arrangement of the substrate of the light deflection liquid crystal cell) like a sun visor attached to a general vehicle. It is conceivable that the angle can be adjusted. In this case, it may be desirable to reinforce the light deflection liquid crystal cell by providing a frame or the like. In the case of the sun visor type, the size of the substrate is assumed to be, for example, about 450 mm wide and 200 mm long.

  Although the present invention has been described with reference to the embodiments, the present invention is not limited thereto. It will be apparent to those skilled in the art that various modifications, improvements, combinations, and the like can be made.

DESCRIPTION OF SYMBOLS 1, 11 Transparent substrate 2, 12, 22 Transparent electrode 3 Prism layer 3a Prism 3b Base layer 13 Orientation film 14 Gap control agent 15 Liquid crystal layer 16 Main sealing agent 21 SiO ₂ film 31 Light deflection liquid crystal cell 32 Light intensity sensor 33 Driving device LS light source

Claims (10)

A light deflecting liquid crystal cell,
A liquid crystal layer;
A pair of transparent substrates disposed opposite to each other and sandwiching the liquid crystal layer;
A pair of transparent electrodes respectively formed above the pair of transparent substrates on the liquid crystal layer side, wherein the overlapping portions in plan view can apply a voltage to the liquid crystal layer for each section in the substrate surface A pair of transparent electrodes forming a pattern;
One of the pair of transparent substrates, and a prism layer formed above the liquid crystal layer side, and changing the refractive index of the liquid crystal layer by applying a voltage for each of the sections, thereby allowing incident light to be incident on the prism layer. A light deflection liquid crystal cell capable of switching between a straight traveling state that is not bent by the light beam and a deflection state in which incident light is bent by the prism layer;
A light intensity sensor that receives the light transmitted through the light deflection liquid crystal cell and measures the intensity of the incident light; and
When the light intensity measured by the light intensity sensor is equal to or greater than a predetermined threshold, the sections are sequentially scanned, and each section is switched from the straight traveling state to the deflection state, and then switched to the deflection state. When the light intensity measured by the light intensity sensor decreases, the anti-glare device includes a drive device that performs control to maintain the deflection state of this section, and to return to the straight-ahead state when the light intensity is not measured.   2. The antiglare device according to claim 1, wherein in the light deflection liquid crystal cell, the liquid crystal layer exhibits a cholesteric blue phase when no voltage is applied.   The drive device maintains a deflected state when a certain light intensity reduction range is greater than or equal to a predetermined intensity when a certain section is switched to a deflected state in the control, and returns to a straight traveling state otherwise. 3. The antiglare device according to 1 or 2.   The antiglare device according to any one of claims 1 to 3, wherein the light deflection liquid crystal cell is disposed on a windshield of an automobile.   The anti-glare device according to claim 4, wherein the light intensity sensor is disposed on a headrest of a driver's seat.   The antiglare device according to claim 4 or 5, wherein the section is narrower toward a lower side.   The light deflection liquid crystal cell is installed with the transparent substrate inclined from the vertical direction, and the prism layer has an angle formed between the vertical direction and the prism inclined surface smaller than an angle formed between the vertical direction and the transparent substrate. The anti-glare device according to any one of claims 1 to 6, which is arranged as described above.   The anti-glare device according to claim 7, wherein the prism layer is disposed on the opposite side of the observer with respect to the liquid crystal layer.   The antiglare device according to any one of claims 1 to 8, wherein the light deflection liquid crystal cell has a polymer network formed in a part of the liquid crystal layer to stabilize the polymer of a cholesteric blue phase. .   The prevention according to any one of claims 1 to 9, wherein an electrode on the prism layer side of the pair of transparent electrodes of the light deflection liquid crystal cell is formed above the liquid crystal layer side of the prism layer. Dazzle device.

Images