Patent Publication Number: US-2022229334-A1

Title: Liquid crystal element, lighting apparatus

Description:
TECHNICAL FIELD 
     The present invention relates to a device (system) for irradiating light in a desired pattern in front of a vehicle, for example, and a liquid crystal element suitable for use in the device (system). 
     BACKGROUND ART 
     Japanese Unexamined Patent Application Publication No. 2005-183327 (Patent Document 1) discloses a vehicle headlight including at least a light emitting unit composed of at least one LED and an optical shielding unit which cuts off a part of the light irradiated toward the front from the light emitting unit and forms a cutoff suitable for the light distribution pattern of the vehicle headlight, where the optical shielding unit is comprised of an electro-optical element equipped with light control function and a control unit which controls lighting of the electro-optical element, and is configured to change shape of the light distribution pattern by selectively controlling the light control portion, by the electric switching control of the electro-optical element by the control unit. As the electro-optical element, a liquid crystal element is used, for example. 
     In the vehicle headlight as described above, the electro-optical element such as a liquid crystal element is configured to have a plurality of pixel electrodes in order to realize selective light control. These pixel electrodes are separated from each other so that a voltage can be applied individually, and a gap is provided between each of the pixels for electrical insulation. At this time, the gap between the pixel electrodes is, for example, about 10 μm depending on the formation accuracy. Further, when three or more rows of pixel electrodes are arranged, it is necessary to pass a wiring portion between the pixel electrodes for applying a voltage to each pixel electrode in the intermediate row, thereby the gap between the pixel electrodes becomes larger. The gap between the pixel electrodes are portions that do not contribute to image formation, and cause dark lines to be generated in the light distribution pattern. Ina vehicle headlight, since an image formed by an electro-optical element (an image corresponding to a light distribution pattern) is magnified by a lens or the like and projected to the front of the vehicle, the above-described dark lines are also magnified and become easier to visually recognize, thereby, there is an inconvenience that the appearance of the light distribution pattern is worsened. To cope with this, narrowing the gap between the pixel electrodes can be considered as a solution, but in this case, since it causes an increase in manufacturing cost and may cause a problem such as a short circuit between the pixel electrodes, such a solution is not preferable. Further, narrowing the width of the wiring portion to be disposed between the pixel electrodes can be considered as a solution, but in this case, since the resistance value of the wiring portion increases and it makes it difficult to apply necessary and sufficient voltage to the pixel electrodes, and since the probability of disconnection due to width narrowing also increases, such a solution is not preferable. Here, it should be noted that such inconveniences are not limited to a vehicle headlight, and the same can be said in a general lighting apparatus that controls the light distribution pattern using a liquid crystal element or the like. 
     PRIOR ART DOCUMENT 
     Patent Document 
     Patent Document 1: Japanese Unexamined Patent Application Publication No. 2005-183327 
     SUMMARY OF THE INVENTION 
     In a specific aspect, it is an object of the present invention to provide a technique capable of improving the appearance of a light distribution pattern in a lighting apparatus that controls the light distribution pattern using a liquid crystal element or the like. 
     [1] A liquid crystal element according to one aspect of the present invention is a liquid crystal element having (a) a first substrate, (b) a second substrate arranged to face the first substrate, (c) a first pixel electrode corresponding to a first pixel region arranged on the surface of the first substrate on the second substrate side, (d) a second pixel electrode corresponding to a second pixel region arranged on the surface of the first substrate on the second substrate side, (e) a common electrode arranged on the first substrate side of the second substrate, and (f) a liquid crystal layer arranged between a group of the first pixel electrode and the second pixel electrode and the common electrode, (g) where the first pixel electrode and the second pixel electrode are provided on different layers on the first substrate, and their ends are arranged so as to partially overlap each other in a plan view.
     [2] A lighting apparatus according to one aspect of the present invention is (a) a lighting apparatus capable of variably setting a light distribution pattern including (b) a light source, (c) a liquid crystal element which uses light from the light source to form an image corresponding to the light distribution pattern, (d) an optical system which projects the image formed by the liquid crystal element, and (e) where, as the liquid crystal element, the liquid crystal element described above is used.   

     According to the above configuration, in a lighting apparatus which controls a light distribution pattern using a liquid crystal element or the like, it is possible to improve the appearance of the light distribution pattern. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is a diagram showing the configuration of a vehicle headlight system of one embodiment. 
         FIG. 2  is a plan view for explaining the configuration of the liquid crystal element. 
         FIG. 3  is a plan view showing the configuration of the liquid crystal element. 
         FIG. 4A  is a plan view for explaining the configurations of the first pixel electrode, the first wiring portion, and the second wiring portion. 
         FIG. 4B  is a cross sectional view for explaining the configuration of the first pixel electrode, the first wiring portion, and the second wiring portion. 
         FIG. 5A  is a plan view for explaining the configuration of the insulating film. 
         FIG. 5B  is a cross sectional view for explaining the configuration of the insulating film. 
         FIG. 6A  is a plan view for explaining the configuration of the second pixel electrode. 
         FIG. 6B  is a cross sectional view for explaining the configuration of the second pixel electrode. 
         FIG. 7  is across sectional view for explaining a state in which the first substrate and the second substrate are overlapped. 
         FIG. 8A  and  FIG. 8B  are diagrams for explaining the electro-optical characteristics (VT characteristics) of the first pixel region and the second pixel region. 
         FIG. 9A  is a chart showing an example of setting a voltage to be applied to the first pixel electrode and the second pixel electrode at room temperature. 
         FIG. 9B  is a graph showing the relationship between the applied voltage and the gradation shown in  FIG. 9A . 
         FIG. 10A  is a graph for explaining the electro-optical characteristics (VT characteristics) of the first pixel region and the second pixel region at an atmospheric temperature of 60° C. 
         FIG. 10B  is a graph for explaining the electro-optical characteristics (VT characteristics) of the first pixel region and the second pixel region at an atmospheric temperature of 80° C. 
         FIG. 11A  is a chart showing an example of setting the voltage to be applied to the first pixel electrode and the second pixel electrode at an atmospheric temperature of 60° C. 
         FIG. 11B  is a graph showing the relationship between the applied voltage and the gradation shown in  FIG. 11A . 
         FIG. 12A  is a chart showing an example of setting the voltage applied to the first pixel electrode and the second pixel electrode at an atmospheric temperature of 80° C. 
         FIG. 12B  is a graph showing the relationship between the applied voltage and the gradation shown in  FIG. 12A . 
         FIG. 13A  and  FIG. 13B  are graphs showing measurement examples of electro-optical characteristics with respect to obliquely incident light at room temperature. 
         FIG. 14A  is a chart showing the sum of the transmittances in the viewing direction and the reverse viewing direction of the voltage at each gradation shown in  FIG. 9A  described above. 
         FIG. 14B  is a graph showing the relationship between the applied voltage and the gradation shown in  FIG. 14A . 
     
    
    
     MODE FOR CARRYING OUT THE INVENTION 
       FIG. 1  is a diagram showing the configuration of a vehicle headlight system of one embodiment. The vehicle headlight system shown in  FIG. 1  is configured to include a light source  1 , a camera  2 , a controller  3 , a liquid crystal driving device  4 , a liquid crystal element  5 , a pair of polarizers  6   a  and  6   b,  and a projection lens  7 . This vehicle headlight system detects the positions of a vehicle in front, pedestrians, etc. that exist around the own vehicle based on the images taken by the camera  2 , sets a certain region including the position of the vehicle in front or the like as a non-irradiation region (dimming region), and sets the other region as the light irradiation region and performs selective light irradiation. 
     The light source  1  is configured to include a white LED configured by combining a light emitting diode (LED) that emits blue light with a yellow phosphor, for example. The light source  1  is provided with a plurality of white LEDs arranged in a matrix or a line, for example. Here, as the light source  1 , in addition to the LEDs, a laser, or alight source generally used for a vehicle headlight unit such as a light bulb or a discharge lamp can be used. The turn-on and turn-off state of the light source  1  is controlled by the controller  3 . The light emitted from the light source  1  enters the liquid crystal element (liquid crystal panel)  5  via the polarizer  6   a.  Here, another optical system (for example, a lens, a reflecting mirror, or a combination thereof) may exist on the path from the light source  1  to the liquid crystal element  5 . 
     The camera  2  captures the front of the own vehicle and outputs the image (information), and is arranged at a predetermined position (for example, the upper part inside the windshield) in the own vehicle. Here, if the vehicle is equipped with a camera for other purposes (for example, an automatic braking system, etc.), the camera may be shared. 
     The controller  3  detects the position of the vehicle in front or the like by performing image processing based on the image obtained by the camera  2  that captures the front of the own vehicle, sets a light distribution pattern in which the detected position of the vehicle in front or the like is set as the non-irradiation region and the other region is set as the light irradiation region, and generates a control signal for forming an image corresponding to this light distribution pattern to be supplied to the liquid crystal driving device  4 . The controller  3  is realized by executing a predetermined operation program in a computer system having, for example, a CPU, a ROM, a RAM, or the like. 
     The liquid crystal driving device  4  individually controls the alignment state of the liquid crystal layer in each pixel region of the liquid crystal element  5  by supplying a drive voltage to the liquid crystal element  5  based on a control signal supplied from the controller  3 . 
     The liquid crystal element  5  has, for example, a plurality of pixel regions (optical modulation regions) that can be individually controlled, and the transmittance of each pixel region is variably set according to the magnitude of the voltage applied to the liquid crystal layer provide by the liquid crystal driving device  4 . By irradiating the liquid crystal element  5  with the light from the light source  1 , an image having a contrast corresponding to the above-described light irradiation region and non-irradiation region is formed. For example, the liquid crystal element  5  is provided with a vertically aligned liquid crystal layer, arranged between a pair of polarizers  6   a  and  6   b  in a crossed Nicol arrangement, the light transmittance becomes extremely low (light-shielding state) when no voltage (or a voltage below a threshold value) is applied to the liquid crystal layer, and the light transmittance becomes relatively high (transmission state) when a voltage is applied to the liquid crystal layer. 
     The pair of polarizers  6   a  and  6   b  have their polarization axes substantially orthogonal to each other, for example, and are arranged so as to face each other with the liquid crystal element  5  interposed therebetween. In the present embodiment, a normally black mode which is an operation mode in which light is shielded (transmittance becomes extremely low) when no voltage is applied to the liquid crystal layer is assumed. As the polarizers  6   a  and  6   b,  for example, an absorption type polarizer made of a general organic material (iodine-based or dye-based) can be used. Further, when heat resistance is desired, it is preferable to use a wire grid type polarizer. A wire grid type polarizer is a polarizer formed by arranging ultrafine wires made of metal such as aluminum. Further, an absorption type polarizer and a wire grid type polarizer may be used in combination. 
     The projection lens  7  spreads an image (an image having a contrast corresponding to the light irradiation region and the non-irradiation region) formed by the light transmitting through the liquid crystal element  5  in order to suit light distribution for headlights and projects it in front of the own vehicle, and an appropriately designed lens is used. In this embodiment, an inverted projection type projector lens is used. 
       FIG. 2  is a plan view for explaining the configuration of the liquid crystal element  5 .  FIG. 3  is a cross sectional view showing the configuration of the liquid crystal element  5 . Here, the cross sectional view shown in  FIG. 3  corresponds to the cross section taken along the line a-a shown in  FIG. 2  and  FIG. 4  which is to be described later. As shown in each figure, the liquid crystal element  5  is configured to include a plurality of first pixel regions (first pixel portion)  51  and a plurality of second pixel regions (second pixel portion)  52 . Here, in  FIG. 2 , each second pixel region  52  is shown with a pattern so that each first pixel region  51  and each second pixel region  52  can be easily distinguished. Here, the left-right direction of the liquid crystal element corresponds to the left-right direction of the light distribution projected in front of the own vehicle. 
     Each first pixel region  51  and each second pixel region  52  are, for example, rectangular in a plan view as shown in 
       FIG. 2 . Further, each of the first pixel regions  51  and each of the second pixel regions  52  are connected to the liquid crystal driving device  4 , and is statically driven, for example, and the light transmittance can be individually controlled. As shown in  FIG. 3 , each first pixel region  51  applies a voltage to the liquid crystal layer  19  by each first pixel electrode (first individual electrode)  13  provided on a first substrate  11  side and a common electrode  18  provided on a second substrate  12  side, and by changing the alignment direction of the liquid crystal molecules in the liquid crystal layer  19  by the voltage, the transmittance of the light transmitting through each electrode is changed. Each second pixel region  52  applies a voltage to the liquid crystal layer  19  by each second pixel electrode (second individual electrode)  14  provided on the first substrate  11  side and a common electrode  18  provided on the second substrate  12  side, and by changing the alignment direction of the liquid crystal molecules in the liquid crystal layer  19  by the voltage, the transmittance of the light transmitting through each electrode is changed. 
     As shown in  FIG. 2 , in a plan view, in the X direction in the figure, each first pixel region  51  and each second pixel region  52  are arranged to have the ends of each region in contact with each other so that no gap is formed therebetween. Further, each first pixel region  51  and each second pixel region  52  are alternately arranged one by one along the X direction in the figure. Further, in the Y direction in the figure, each first pixel region  51  and each second pixel region  52  are arranged with a gap (for example, a few μm). 
     As shown in  FIG. 3 , the liquid crystal element  5  is configured to include a first substrate  11  and a second substrate  12  arranged to face each other, a plurality of first pixel electrodes  13  provided on the first substrate  11 , a plurality of second pixel electrodes  14 , an insulating film  15 , a plurality of first wiring portions  21  and a plurality of second wiring portions  22 , a common electrode  18  provided on the second substrate  12 , and a liquid crystal layer  19  arranged between the first substrate  11  and the second substrate  12 . Here, although not shown for convenience of explanation, the first substrate  11  and the second substrate  12  are appropriately provided with an alignment film in order to regulate the alignment state of the liquid crystal layer  19 . 
     The first substrate  11  and the second substrate  12  are each a rectangular substrate in a plan view, and are arranged so as to face each other. As each substrate, for example, a transparent substrate such as a glass substrate or a plastic substrate can be used. A plurality of spherical spacers made of resin are dispersedly arranged between the first substrate  11  and the second substrate  12  for example, and the spacers keep the substrate gap at a desired distance (for example, approximately a few μm). Here, columnar spacers made of resin may be used instead of the spherical spacers. 
     Each first pixel electrode  13  is provided on one surface side of the first substrate  11 . Further, each first wiring portion  21  is provided on one surface side of the first substrate  11 . Further, each second wiring portion  22  is provided between each first pixel electrodes  13  on one surface side of the first substrate  11 . Each first pixel electrode  13 , each first wiring portion  21 , and each second wiring portion  22  are configured by appropriately patterning a transparent conductive film such as indium tin oxide (ITO). The above-described first pixel region  51  is demarcated at each of the overlapping regions of the first pixel electrode  13  and the common electrode  18 . 
     Each second pixel electrode  14  is provided on the upper side of the insulating layer  15  on one surface side of the first substrate  11 . That is, each first pixel electrode  13  is arranged closer to the first substrate  11  than each second pixel electrode  14 . Each second pixel electrode  14  is configured by appropriately patterning a transparent conductive film such as indium tin oxide (ITO). The above-described second pixel region  52  is demarcated at each of the overlapping regions of the second pixel electrode  14  and the common electrode  18 . 
     Each first pixel electrode  13  and each second pixel electrode  14  are alternately arranged one by one in the X direction in the figure, and the ends of adjacent electrodes in the X direction are provided to slightly overlap each other in the Z direction in the figure. The overlapping region R, which is the region where the ends of the adjacent first pixel electrodes  13  and the second pixel electrodes  14  partially overlap, has a width of approximately a few μm to 15 μm, for example. By providing such an overlapping region R, positional deviation tolerance during manufacture can be increased, and the gap between the first pixel region  51  and the second pixel region  52  (the gap in the X direction in  FIG. 2 ) can be reliably eliminated. 
     Each first wiring portion  21  is connected to one of the first pixel electrodes  13  to apply a voltage to the first pixel electrode  13  (refer to  FIG. 4  to be described later). Each second wiring portion  22  is connected to one of the second pixel electrode  14  via the first insulating film  15  in order to apply a voltage to the second pixel electrode  14 , and is arranged at a position where it overlaps with at least a part of one of the second pixel electrode  14  in a plan view. 
     The insulating film  15  has translucency, and is provided on one surface side of the first substrate  11  so as to cover the upper side of each first pixel electrode  13 . This insulating film  15  is, for example, an oxide film or a nitride film such as a SiO 2  film or a SiON film, and can be formed by a vapor phase process such as a sputtering method or a solution process. Here, as the insulating film  15 , an organic insulating film may be used. The thickness of the insulating film  15  is preferably about 0.4 μm to 1.5 μm, for example. Further, the dielectric constant of the insulating film  15  is preferred to be a high value, for example, 4 or more, and further preferably, 8 or more. 
     The common electrode  18  is provided on one surface side of the second substrate  12 . This common electrode  18  is provided so as to overlap all first pixel electrodes  13  and all second pixel electrodes  14  in a plan view. The common electrode  18  is configured by appropriately patterning a transparent conductive film such as indium tin oxide (ITO), for example. 
     The liquid crystal layer  19  is interposed between the first substrate  11  and the second substrate  12 . In the present embodiment, the liquid crystal layer  19  is configured by using a nematic liquid crystal material having a negative dielectric anisotropy Δε and having fluidity. The liquid crystal layer  19  of the present embodiment is set so that the alignment direction of the liquid crystal molecules when no voltage is applied is substantially vertically aligned. 
     Here, as described above, alignment films are provided on one surface side of the first substrate  11  and one surface side of the second substrate  12 , respectively. As each alignment film, a vertical alignment film that regulates the alignment state of the liquid crystal layer  19  to vertically align is used. Each alignment film is subjected to a uniaxial alignment treatment such as a rubbing treatment, and has a uniaxial alignment regulating force that regulates the alignment of the liquid crystal molecules of the liquid crystal layer  19  in that direction. The directions of the alignment treatment for each alignment film are set to be staggered (anti-parallel), for example. 
       FIG. 4A  is a plan view for explaining the configurations of the first pixel electrode, the first wiring portion, and the second wiring portion. Further,  FIG. 4B  is a cross sectional view for explaining the configurations of the first pixel electrode, the first wiring portion, and the second wiring portion. As shown in  FIG. 4A , on one surface side of the first substrate  11 , each first pixel electrode  13  is provided in a region corresponding to each first pixel region  51 . In the figure, reference numerals  13   a,    13   b,  and  13   c  are used in order to distinguish each of the first pixel electrodes  13 . Further, in the figure, reference numerals  21   a,    21   b,  and  21   c  are used in order to distinguish each of the first wiring portions  21 , and reference numerals  22   a,    22   b,  and  22   c  are used in order to distinguish each of the second wiring portions  22 . 
     A first pixel electrode  13   a  arranged in the lower part of the figure corresponds to one first pixel region  51 . A first wiring portion  21   a  is connected to the first pixel electrode  13   a.  The first wiring portion  21   a  extends from the lower end of the first pixel electrode  13   a  to the lower end of the first substrate  11 . A first pixel electrode  13   b  arranged in the middle part of the figure corresponds to one first pixel region  51 . A first wiring portion  21   b  is connected to the first pixel electrode  13   b.  In the figure, the first wiring portion  21   b  extends through the right side of each of the first pixel electrode  13   b  and the first pixel electrode  13   a  to the lower end of the first substrate  11 . A first pixel electrode  13   c  arranged in the upper part of the figure corresponds to one first pixel region  51 . A first wiring portion  21   c  is connected to the first pixel electrode  13   c.  In the figure, the first wiring portion  21   c  extends through the right side of each of the first pixel electrode  13   b,  the first pixel electrode  13   a,  and the first wiring portion  21   b,  to the lower end of the first substrate  11 . 
     In the figure, second wiring portions  22   a,    22   b,  and  22   c  are arranged on the right side of the first pixel electrodes  13   a,    13   b,  and  13   c  and the first wiring portions  21   a,    21   b,  and  21   c.  In detail, the second wiring portion  22   a  is provided between the other second wiring portions  22   b  and  22   c.  The second wiring portion  22   a  is associated with a second pixel electrode  14   a  to be described later, and has a shorter length in the Y direction than the other second wiring portions  22   b  and  22   c.  The second wiring portion  22   b  is provided between the first wiring portion  21   c  and the second wiring portion  22   a.  The second wiring portion  22   b  is associated with a second pixel electrode  14   b  to be described later, and has a shorter length in the Y direction than the wiring portion  22   c.  The second wiring portion  22   c  is provided on the right side of the second wiring portion  22   a.  The second wiring portion  22   c  is associated with a second pixel electrode  14   c  to be described later, and has a longer length in the Y direction than the other wiring portions  22   a  and  22   b.    
     In the figure, an inter-pixel electrode  23   b  extending in the X direction is connected to the second wiring portion  22   b.  The inter-pixel electrode  23   b  is provided so as to overlap with the gap (see  FIG. 2 ) provided between adjacent second pixel regions  52  in the Y direction. Similarly, in the figure, an inter-pixel electrode  23   c  extending in the X direction is connected to the second wiring portion  22   c.  This inter-pixel electrode  23   c  is provided so as to overlap with the gap (see  FIG. 2 ) provided between adjacent second pixel regions  52  in the Y direction. When a voltage is applied to the second pixel electrodes  14   b  and  14   c  which are connected to the second wiring portions  22   b  and  22   c,  these inter-pixel electrodes  23   b  and  23   c  become the same potential as the second pixel electrodes  14   b  and  14   c.  Therefore, when a voltage is applied to the second pixel electrodes  14   b  and  14   c,  the alignment direction of the liquid crystal molecules of the liquid crystal layer  19  can be changed even at the gap between the adjacent second pixel regions  52  in the Y direction, thereby allowing to prevent or alleviate generation of dark lines corresponding to the gap. 
       FIG. 5A  is a plan view for explaining the configuration of the insulating film.  FIG. 5B  is a cross sectional view for explaining the configuration of the insulating film. As shown in each figure, the insulating film  15  is provided on one surface side of the first substrate  11  so as to cover each first pixel electrode  13 , each first wiring portion  21 , and each second wiring portion  22 . Further, this insulating film  15  is provided with openings (through holes)  24   a,    24   b,  and  24   c  for exposing a part of each of the second wiring portions  22   a,    22   b,  and  22   c.  Through these openings  24   a,    24   b,  and  24   c,  each of the second wiring portions  22   a,    22   b,  and  22   c  and each of the second pixel electrodes  14   a,    14   b,  and  14   c  (refer to  FIG. 6A ) are physically and electrically connected to each other. 
       FIG. 6A  is a plan view for explaining the configuration of the second pixel electrode.  FIG. 6B  is a cross sectional view for explaining the configuration of the second pixel electrode. As shown in each figure, on one surface side of the insulating film  15  of the first substrate  11 , each second pixel electrode  14  is provided in a region corresponding to each second pixel region  52 . In the figure, reference numerals  14   a,    14   b,  and  14   c  are used in order to distinguish each of the second pixel electrodes  14 . A second pixel electrode  14   a  is physically and electrically connected to the second wiring portion  22   a  on the lower layer side via the opening  24   a  of the insulating film  15 . A second pixel electrode  14   b  is physically and electrically connected to the second wiring portion  22   b  on the lower layer side via the opening  24   b  of the insulating film  15 . A second pixel electrode  14   c  is physically and electrically connected to the second wiring portion  22   c  on the lower layer side via the opening  24   c  of the insulating film  15 . Further, as described above, each of the second pixel electrodes  14   a,    14   b,  and  14   c  is respectively arranged so as to have an overlapping region R between each of the first pixel electrodes  13   a,    13   b,  and  13   c.    
     Further, the second pixel electrodes  14   a,    14   b,  and  14   c  are provided so as to overlap the first wiring portions  21   b  and  21   c  and the second wiring portions  22   a,    22   b,  and  22   c  in a plan view. In this way, since the wiring portions can be arranged on the lower layer side of the pixel electrode, it is not necessary to secure a space for arranging the wiring portion outside each pixel region. Thereby, the gap between each pixel electrode can be eliminated. 
       FIG. 7  is a cross sectional view for explaining a state in which the first substrate and the second substrate are overlapped. Here, a method for manufacturing the liquid crystal element of the present embodiment will be briefly described. First, as shown in  FIG. 4A  and  FIG. 4B , each first pixel electrodes  13  and the like are formed on one surface side of the first substrate  11 . Next, as shown in  FIG. 5A  and FIG.  5 B, the insulating film  15  is formed on one surface side of the first substrate  11  so as to cover each first pixel electrode  13  and the like, and the openings  24   a,  etc. are further formed. Further, as shown in  FIG. 6A  and  FIG. 6B , each second pixel electrode  14  is formed on the upper side of the insulating film  15 . On the other hand, the common electrode  18  is formed on one surface side of the second substrate  12 . Alignment treatment is appropriately performed to one surface side of each of the first substrate  11  and the second substrate  12  thus obtained, and both substrates are arranged to overlap each other. By injecting a liquid crystal material between the first substrate  11  and the second substrate  12 , the liquid crystal layer  19  is formed. From the above, the liquid crystal element of the present embodiment can be obtained (refer to  FIG. 3 ). The first wiring portion, the second wiring portion, and the common electrode of the liquid crystal element  5  are electrically connected to the liquid crystal driving device  4 , and are configured so that the liquid crystal driving device  4  can supply a driving voltage to the liquid crystal element  5  based on a control signal supplied from the controller  3 . 
       FIG. 8A  and  FIG. 8B  are diagrams for explaining the electro-optical characteristics (VT characteristics) of the first pixel region and the second pixel region. As shown in  FIG. 8A , the measurement point which passes through the first pixel region  51  is defined as B, the measurement point which passes through the second pixel region  52  is defined as A, and an example of measuring the electro-optical characteristics at each measurement point A and B at room temperature (25° C.) is shown in  FIG. 8B . Comparing the first pixel region  51  and the second pixel region  52 , in the first pixel region  51 , the voltage from the first pixel electrode  13  is divided by the insulating film  15  and then applied to the liquid crystal layer  19 , whereas in the second pixel region  52 , the voltage from the second pixel electrode  14  is directly applied to the liquid crystal layer  19 . Depending on the presence or absence of the divided voltage, there is a difference in electro-optical characteristics between the first pixel region  51  and the second pixel region  52 . Therefore, in order to obtain the same transmittance in the first pixel region  51  and the second pixel region  52  in the gradation display region (for example, between an applied voltage of about 3 to 8 V), the voltage applied to the first pixel region  51  (measurement point B) is set to a value relatively larger than the voltage applied to the second pixel region  52  (measurement point A), in correspondence with the value equivalent to the voltage divided by the insulating film  15 . 
     Specifically, assuming that the capacitance of the insulating layer  15  is C in , the capacitance of the liquid crystal layer  19  is C LC , the voltage applied to the first pixel electrode  13  is V down , and the voltage applied to the second pixel electrode  14  is V up , then the relationship between these values can be expressed as follows. 
         V   down =( C   in /( C   in   +C   LC ))* V   up    
     Here, assuming that the electrode area is  5 , the dielectric constant of the insulating layer  15  is ε in , the film thickness of the insulating layer  15  is d in , the dielectric constant of the liquid crystal layer  19  is ε LC , and the film thickness of the liquid crystal layer  19  is d LC , then C in  and C LC  can be expressed as follows. 
         C   in =( S/d   in )*ε in  
 
         C   LC =( S/d   LC )*ε LC  
 
     Therefore, theoretically, if the applied voltages to the first pixel electrode  13  and the second pixel electrode  14  are set so as to satisfy the above relational expressions, the difference in electro-optical characteristics between the first pixel region  51  and the second pixel region  52  is eliminated, and unevenness in the brightness of the irradiation light can be suppressed. 
       FIG. 9A  is a chart showing an example of setting the voltage applied to the first pixel electrode and the second pixel electrode at room temperature. Further,  FIG. 9B  is a graph showing the relationship between the applied voltage and the gradation shown in  FIG. 9A . Here, in the liquid crystal element according to the above embodiment, a liquid crystal element in which the layer thickness of the liquid crystal layer  19  being 4 μm and the refractive index anisotropy Δn being about 0.13 is used (the same applies hereinafter). In  FIG. 9A , in a case where the gradation is divided into 9 stages, the chart shows the applied voltage at which a desired transmittance can be obtained. It can be seen that the required voltages are different between measurement point A and measurement point B. For example, when obtaining the transmittance of gradation “5”, 3.8V is applied to the second pixel electrode  14  corresponding to measurement point A, and 5.4V is applied to the first pixel electrode  13  corresponding to measurement point B. Same applies to other gradations. In this way, by setting the voltage applied to the first pixel electrode  13  and the second pixel electrode  14  with a difference, the difference in electro-optical characteristics between the first pixel region  51  and the second pixel region  52  is reduced, and unevenness in the brightness of the irradiation light can be suppressed. In the illustrated example, in the range from gradation “0” to gradation “8”, the difference in transmittance at each of the measurement points A and B is within ±1.5%, and it can be said that the transmittances are substantially the same. Further, except for gradation “3”, the difference in transmittance is within ±1.0%, and it can be said that the transmittances are substantially the same. In the case of forming high-intensity irradiation light in front of the vehicle as in the present embodiment, if the difference in transmittance is within ±2.0%, it can be said that the transmittances are substantially the same. 
       FIG. 10A  is a graph for explaining the electro-optical characteristics (VT characteristics) of the first pixel region and the second pixel region at an atmospheric temperature of 60° C. Further,  FIG. 10B  is a graph for explaining the electro-optical characteristics (VT characteristics) of the first pixel region and the second pixel region at an atmospheric temperature of 80° C. As in the case of room temperature described above, it can be seen that there is a difference in electro-optical characteristics between the first pixel region (measurement point B) and the second pixel region  52  (measurement point A) even in a high temperature atmosphere. 
       FIG. 11A  is a chart showing an example of setting the voltage applied to the first pixel electrode and the second pixel electrode at an atmospheric temperature of 60° C. Further,  FIG. 11B  is a graph showing the relationship between the applied voltage and the gradation shown in  FIG. 11A .  FIG. 12A  is a chart showing an example of setting the voltage applied to the first pixel electrode and the second pixel electrode at an atmospheric temperature of 80° C. Further,  FIG. 12B  is a graph showing the relationship between the applied voltage and the gradation shown in  FIG. 12A . As in the case of room temperature described above, by setting the voltage applied to the first pixel electrode  13  and the second pixel electrode  14  with a difference, the difference in electro-optical characteristics between the first pixel region  51  and the second pixel region  52  is reduced, and unevenness in the brightness of the irradiation light can be suppressed. 
       FIG. 13A  and  FIG. 13B  are graphs showing measurement examples of electro-optical characteristics with respect to obliquely incident light at room temperature.  FIG. 13A  shows the electro-optical characteristics when light is incident from 20° direction with respect to the substrate normal in a viewing direction, and  FIG. 13B  shows the electro-optical characteristics when light is incident from 20° direction with respect to the substrate normal in a reverse viewing direction. Further,  FIG. 14A  is a chart showing the sum of the transmittances in the viewing direction and the reverse viewing direction of the voltage at each gradation shown in  FIG. 9A  described above.  FIG. 14B  is a graph showing the relationship between the applied voltage and the gradation shown in  FIG. 14A . From these results, it can be seen that, by applying the same gradation voltage as when visually recognizing from the front direction at room temperature, light can be irradiated with the same brightness at both the measurement points A and B even when the viewing angle direction changes. It can also be seen that, although the linearity of the gradation is slightly lost, the gradation is not inverted. Here, it can be seen that the same gradation voltage as the voltage optimized for the normal direction can be used even in the direction of the strictest viewing angle. 
     According to the above embodiment, in a plan view, since it is possible to eliminate the gap between the pixel regions at least in the left-right direction of the liquid crystal element, the occurrence of dark lines caused by the gap between the pixel regions in the irradiation light to the front of the vehicle can be prevented, and the appearance of the light distribution pattern can be improved. 
     Here, the present invention is not limited to the contents of the above-described embodiment, and can be variously modified and implemented within the scope of the gist of the present invention. For example, in the above-described embodiment, a case where the boundaries between the pixel regions of the liquid crystal element are arranged vertically and horizontally has been illustrated, but the boundaries between the pixel regions may be arranged in an oblique direction. Further, the boundary is not limited to a straight line, but may be a curved line. Further, in the above-described embodiment, vertical alignment is exemplified as the alignment mode of the liquid crystal layer of the liquid crystal element, but the alignment mode is not limited thereto, and for example, a twist alignment mode may be used. Further, an optical compensator such as a C plate may be provided on one side or both sides of the liquid crystal element. Further, in the above-described embodiment, a liquid crystal element where each of the pixel regions are arranged along the two directions which are the vertical direction and the lateral direction (X and Y directions) has been illustrated, but the liquid crystal element may be configured to have each pixel region arranged along at least one direction (for example, X direction). 
     DESCRIPTION OF REFERENCE NUMERALS 
       1 : Light source 
       2 : Camera 
       3 : Controller 
       4 : Liquid crystal driving device 
       5 : Liquid crystal element 
       6   a,    6   b:  Polarizer 
       7 : Projection lens 
       11 : First substrate 
       12 : Second substrate 
       13 ,  13   a,    13   b,    13   c:  First pixel electrode 
       14 ,  14   a,    14   b,    14   c:  Second pixel electrode 
       15 : Insulation film 
       18 : Common electrode 
       19 : Liquid crystal layer 
       21 ,  21   a,    21   b,    21   c:  First wiring portion 
       22 ,  22   a,    22   b,    22   c:  Second wiring portion 
       23   b,    23   c:  Inter-pixel electrode 
       24 ,  24   a,    24   b,    24   c:  Opening (Through hole) 
       51 : First pixel region 
       52 : Second pixel region