Liquid crystal element, lighting device

Abstract

To simplify a liquid crystal element manufacturing step, and improve appearance of a light distribution pattern.SOLUTION: A liquid crystal element includes a liquid crystal layer 18 which is arranged between a first substrate 11 and a second substrate 12, a plurality of auxiliary electrodes 15 arranged in the first substrate, an insulating layer 17 arranged so as to cover the plurality of first electrodes, a plurality of pixel electrodes 13 arranged between the insulating layer and the liquid crystal layer, and a counter electrode 14 arranged in the second substrate, wherein the plurality of pixel electrodes are arranged so as to have a gap therebetween in at least one direction in plan view; each of the plurality of auxiliary electrodes is arranged so as to overlap the gap between the adjacent pixel electrodes in plan view and is connected to any one of the adjacent pixel electrodes through a contact hole 20 provided in the insulating layer; and the insulating layer has an opening 19 in at least a part corresponding to the gap between the adjacent pixel electrodes.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present disclosure relates to a liquid crystal element and a lighting device.

Background Art

[0002] Japanese Patent Application Laid-Open No. 2020-154153 (Patent Document 1) describes a lighting device configured using a liquid crystal element. This liquid crystal element includes a first substrate, a second substrate, and a liquid crystal layer, a counter electrode provided on the first substrate, a plurality of inter-pixel electrodes provided on the second substrate, a first insulating layer provided above the plurality of inter-pixel electrodes, a plurality of pixel electrodes provided above the first insulating layer, and a second insulating layer provided above the plurality of pixel electrodes. The plurality of pixel electrodes are arranged with gaps between them along at least a first direction in a plan view. The plurality of inter-pixel electrodes are each arranged so as to overlap the gap between two adjacent pixel electrodes in the first direction in a plan view and are connected to one of the two pixel electrodes. The second insulating layer is selectively provided for each region overlapping each of the plurality of pixel electrodes in a plan view. By using this liquid crystal element, it is possible to improve the appearance of the light distribution pattern in the lighting device.

[0003] However, the liquid crystal element used in the above-described lighting device needs to be provided with two insulating layers, namely the first insulating layer and the second insulating layer, and the second insulating layer needs to be provided so as to accurately overlap each pixel electrode. Therefore, there is room for improvement in terms of the complexity of the manufacturing process.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0005] One of the objectives of the specific embodiments according to the present disclosure is to provide a technology that can simplify the manufacturing process of a liquid crystal element used in an illumination device capable of freely controlling a light distribution pattern and improve the appearance of the light distribution pattern.

Means for Solving the Problems

[0006] [1] A liquid crystal element according to one aspect of the present disclosure includes: (a) a first substrate and a second substrate arranged opposite to each other; (b) a liquid crystal layer arranged between the first substrate and the second substrate; (c) a plurality of auxiliary electrodes arranged on one surface side of the first substrate facing the liquid crystal layer; (d) an insulating layer arranged on the one surface side of the first substrate covering the plurality of Auxiliary electrodes; (e) a plurality of pixel electrodes arranged between the insulating layer and the liquid crystal layer of the first substrate; (f) a counter electrode arranged on one surface side of the second substrate facing the liquid crystal layer, and (g) the plurality of pixel electrodes are arranged with gaps provided between them in at least one direction in a plan view, (h) each of the plurality of auxiliary electrodes is arranged so as to overlap with the gap between the adjacent pixel electrodes in a plan view, and is mutually connected to any one of the adjacent pixel electrodes through a contact hole provided in the insulating layer, (i) the insulating layer , adjacent has an opening at a portion corresponding to the gap between the adjacent pixel electrodes that face each other, and is a liquid crystal element. [2] An illumination device according to one aspect of the present disclosure includes: (a) the liquid crystal element of [1]; (b) a light source that makes light incident on the liquid crystal element; and (c) a lens that condenses the light transmitted through the liquid crystal element, and is an illumination device.

[0007] According to the above configuration, it becomes possible to provide a technology that can simplify the manufacturing process of a liquid crystal element used in an illumination device capable of freely controlling a light distribution pattern and improve the appearance of the light distribution pattern.

Brief Description of the Drawings

[0008]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

DETAILED DESCRIPTION OF THE INVENTION

[0009] FIG. 1 is a diagram showing the configuration of a vehicle lighting system according to an embodiment. The vehicle lighting system shown in FIG. 1 includes a light source 1, a camera 2, a controller (control device) 3, a driver (liquid crystal driving device) 4, a liquid crystal element 5, a pair of polarizing plates 6a and 6b, and a projection lens 7. This vehicle lighting system detects the positions of a preceding vehicle, a pedestrian, etc. existing around the host vehicle based on an image captured by the camera 2, sets a certain range including the positions of the preceding vehicle, etc. as a dimming range (or non-irradiation range), and sets the other range as a light irradiation range to perform selective light irradiation.

[0010] The light source 1 is configured to include, for example, a white light-emitting diode (LED) formed by combining a light-emitting element (LED) that emits blue light with a yellow phosphor. The light source 1 includes, for example, a plurality of white light-emitting diodes arranged in a matrix or line shape. In addition to LEDs, as the light source 1, a laser, or a light source generally used in vehicle lamp units such as incandescent lamps and discharge lamps can be used. The lighting and extinguishing 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 through the polarizing plate 6a. Note that other optical systems (for example, lenses, mirrors, or a combination thereof) may exist on the path from the light source 1 to the liquid crystal element 5.

[0011] The camera 2 captures an image of the front of the host vehicle and outputs the image (information), and is disposed at a predetermined position inside the host vehicle (for example, the upper part inside the windshield). When the host vehicle is equipped with a camera for other uses (for example, an automatic braking system, etc.), that camera may be shared.

[0012] The controller 3 performs image processing based on the image obtained by the camera 2 that captures the front of the host vehicle to detect the position of the vehicle ahead, etc., sets a light distribution pattern with a certain range including the detected position of the vehicle ahead, etc. as a non-irradiation range and the other range as a light irradiation range, and generates a control signal for forming an image corresponding to this light distribution pattern and supplies it to the liquid crystal drive circuit 4. This controller 3 is realized by executing a predetermined operation program in a computer system having, for example, a CPU, ROM, RAM, etc.

[0013] The driver 4 supplies a driving voltage to the liquid crystal element 5 based on the control signal supplied from the controller 3, thereby individually controlling the alignment state of the liquid crystal layer in each pixel region of the liquid crystal element 5.

[0014] The liquid crystal element 5 has, for example, a plurality of pixel regions (light 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 by the driver 4. When the liquid crystal element 5 is irradiated with light from the light source 1, an image having brightness and darkness corresponding to the above-described light irradiation range and dimming range is formed. For example, the liquid crystal element 5 includes a vertically aligned liquid crystal layer and is disposed between a pair of polarizing plates 6a and 6b arranged in a cross Nicol configuration. When no voltage is applied to the liquid crystal layer (or when the voltage is below the threshold value), the light transmittance becomes extremely low (light shielding state), and when a voltage is applied to the liquid crystal layer, the light transmittance becomes relatively high (transmission state).

[0015] The pair of polarizing plates 6a and 6b have, for example, their polarization axes substantially orthogonal to each other and are disposed opposite to each other with the liquid crystal element 5 interposed therebetween. In the present embodiment, a normally black mode is assumed, which is an operation mode in which light is blocked (the transmittance becomes extremely low) when no voltage is applied to the liquid crystal layer. As each of the polarizing plates 6a and 6b, for example, an absorption type polarizing plate made of a general organic material (iodine-based, dye-based) can be used. Further, when heat resistance is emphasized, it is also preferable to use a wire grid type polarizing plate. The wire grid type polarizing plate is a polarizing plate formed by arranging extremely fine wires made of a metal such as aluminum. Further, an absorption type polarizing plate and a wire grid type polarizing plate may be used in combination.

[0016] The projection lens 7 projects, onto the front of the host vehicle, an image (an image having brightness and darkness corresponding to the light irradiation range and dimming range) formed by the light transmitted through the liquid crystal element 5, after expanding it to have a light distribution for a headlight. An appropriately designed lens is used. In the present embodiment, an inverse projection type projector lens is used.

[0017] Figs. 2(A) and 2(B) are schematic cross-sectional views showing the configuration of the liquid crystal element. Fig. 3 is a plan view for explaining the structures of the pixel electrodes, the inter-pixel electrodes, and the wiring portions. Note that the cross-sectional view shown in Fig. 2(A) corresponds to a partial cross-section along the line a-a shown in Fig. 3, and the cross-sectional view shown in Fig. 2(B) corresponds to a partial cross-section along the line b-b shown in Fig. 3.

[0018] The liquid crystal element 5 includes a first substrate 11, a second substrate 12, a plurality of pixel electrodes 13, a common electrode (opposing electrode) 14, a plurality of inter-pixel electrodes (auxiliary electrodes) 15, a plurality of wiring portions 16, an insulating layer (insulating film) 17, and a liquid crystal layer 18.

[0019] The first substrate 11 and the second substrate 12 are each, for example, a substrate having a rectangular shape in plan view, and are arranged to face each other. As each substrate, for example, a transparent substrate such as a glass substrate or a plastic substrate can be used. Between the first substrate 11 and the second substrate 12, spherical spacers (not shown) made of, for example, a resin film are dispersedly arranged, and the substrate gap is maintained at a desired size (for example, about several μm) by these spherical spacers. Note that instead of the spherical spacers, columnar bodies made of resin or the like may be provided on the first substrate 11 side or the second substrate 12 side and used as spacers.

[0020] The plurality of pixel electrodes 13 are provided on one surface side of the first substrate 11 on one surface of the insulating layer 17 (the surface in contact with the liquid crystal layer 18). Each pixel electrode 13 is Contact physically and electrically connected to one inter-pixel electrode 15 and one wiring portion 16 connected to this inter-pixel electrode via a hole 20 provided in the insulating layer 17. Each pixel electrode 13 is formed by appropriately patterning a transparent conductive film such as indium tin oxide (ITO). Each pixel electrode 13 has, for example, an outer edge shape having a rectangular shape in plan view, and is arranged in a matrix along the X direction and the Y direction. A gap is provided between the pixel electrodes 13.

[0021] The common electrode 14 is provided on one surface side of the first substrate 11. This common electrode 14 is integrally provided so as to face each pixel electrode 13 of the second substrate 12. The common electrode 14 is formed by appropriately patterning a transparent conductive film such as indium tin oxide (ITO), for example. A pixel region (light modulation region) is formed in each region where the common electrode 14 and each pixel electrode 13 overlap.

[0022] The plurality of inter-pixel electrodes 15 are provided between one surface side of the first substrate 11 and the insulating layer 17. Each inter-pixel electrode 15 is arranged so as to overlap the gap between adjacent pixel electrodes 13 in a plan view. Each inter-pixel electrode 15 is formed by appropriately patterning a transparent conductive film such as indium tin oxide (ITO), for example.

[0023] The plurality of wiring portions 16 are provided between one surface side of the first substrate 11 and the insulating layer 17. Each wiring portion 16 is arranged so as to overlap each pixel electrode 13 in a plan view. Each wiring portion 16 is formed by appropriately patterning a transparent conductive film such as indium tin oxide (ITO), for example. Each wiring portion 16 is for applying a voltage from the driver 4 to each pixel electrode 13.

[0024] The insulating layer 17 is provided so as to cover each inter-pixel electrode 15 and each wiring portion 16 on one surface side of the first substrate 11. The insulating layer 17 has an opening 19 at least in a portion corresponding to each inter-pixel electrode 15. In the present embodiment, the insulating layer 17 is provided in a range corresponding to each pixel electrode 13, and all the spaces between the pixel electrodes 13 are openings 19. The insulating layer 17 has a planar shape such that the end position of each pixel electrode 13 and the end position of the insulating layer 17 substantially coincide in a portion overlapping each pixel electrode 13. The insulating layer 17 is, for example, a SiNx film, a SiO2 film, or a SiON film, and can be formed by a vapor phase process such as a sputtering method or a solution process. Note that an organic insulating film may be used as the insulating layer 17. The layer thickness of the insulating layer 17 is, for example, about 1 μm. layer 17's end position is substantially the same in a plan view. The insulating layer 17 is, for example, a SiNx film, a SiO2 film, or a SiON film, and can be formed by a vapor phase process such as a sputtering method or a solution process. Note that an organic insulating film may be used as the insulating layer 17. The layer thickness of the insulating layer 17 is, for example, about 1 μm.

[0025] The liquid crystal layer 18 is provided between the first substrate 11 and the second substrate 12. In the present embodiment, the liquid crystal layer 18 is composed of a nematic liquid crystal material having a negative dielectric anisotropy Δε, containing a chiral material, and having fluidity. In the liquid crystal layer 18 of the present embodiment, the alignment direction of the liquid crystal molecules when no voltage is applied is in a state inclined in one direction, and is set to have a substantially vertical alignment with a pretilt angle within a range of, for example, 85° or more and less than 90° with respect to each substrate surface.

[0026] Although not shown, an alignment film is provided on one surface side of the first substrate 11 so as to cover each pixel electrode 13, and an alignment film is provided on one surface side of the second substrate 12 so as to cover the common electrode 14. In the present embodiment, a vertical alignment film that regulates the alignment state of the liquid crystal layer 18 into a vertical alignment is used as each alignment film. Each alignment film is subjected to a uniaxial alignment treatment such as a rubbing treatment, and has a uniaxial alignment regulating force that defines the alignment of the liquid crystal molecules in the liquid crystal layer 18 in that direction. The directions of the alignment treatments for the respective alignment films are set to be, for example, alternate (antiparallel). The film thickness of each alignment film is, for example, 50 nm to 70 nm.

[0027] The liquid crystal element 5 of the present embodiment has several tens to several hundreds of pixel regions, each of which is defined as a region where the common electrode 14 and each pixel electrode 13 overlap in a plan view, and these pixel regions are arranged in a matrix. In the present embodiment, the shape of each pixel region is configured to be, for example, a square shape, but the shape of each pixel region can be arbitrarily set, such as a mixture of rectangular and square shapes. The common electrode 14, each pixel electrode 13, and each inter-pixel electrode 15 are connected to the driver 4 via each wiring portion 16 or the like, and are, for example, statically driven.

[0028] While referring to FIG. 3, the structures of each pixel electrode, each inter-pixel electrode, and each wiring portion 16 will be described. In the present embodiment, each pixel electrode 13 is arranged in three rows along the Y direction and arranged in an arbitrary number along the X direction. Here, for each pixel electrode 13, the one in the first row from the top in the figure is denoted as pixel electrode 13a, the one in the second row is denoted as pixel electrode 13b, and the one in the third row is denoted as pixel electrode 13c. Also, for the inter-pixel electrode 15, the one associated with the first-row pixel electrode 13a is denoted as inter-pixel electrode 15a, the one associated with the second-row pixel electrode 13b is denoted as inter-pixel electrode 15b, and the one associated with the third-row pixel electrode 13c is denoted as inter-pixel electrode 15c. Furthermore, for the wiring portion 16, the one associated with the first-row pixel electrode 13a and inter-pixel electrode 15a is denoted as wiring portion 16a, the one associated with the second-row pixel electrode 13b and inter-pixel electrode 15b is denoted as wiring portion 16b, and the one associated with the third-row pixel electrode 13c and inter-pixel electrode 15c is denoted as wiring portion 16c.

[0029] Each pixel electrode 13a is provided in the insulating layer 17 Contact and is connected to the lower-layer inter-pixel electrode 15a and wiring portion 16a via the hole 20a. Thereby, the pixel electrode 13a, the inter-pixel electrode 15a, and the wiring portion 16a are at the same potential. Each Contact hole 20a has an outer edge shape that is substantially triangular in a plan view as shown in the figure, and is provided corresponding to one of the four corners (the upper left corner in the figure) of each pixel electrode 13a in a plan view. Note that Contact the plan view shape of the hole 20a is not limited to a substantially triangular shape, and may be a polygon, a circle, an ellipse, or the like. Also, Contact although the case where the formation position of the hole 20a is provided at one of the four corners of each pixel electrode is shown, it can be provided at an arbitrary position such as the center of the pixel electrode.

[0030] Similarly, each pixel electrode 13b is provided in the insulating layer 17 ContactIt is connected to the inter-pixel electrode 15b and the wiring portion 16b on the lower layer side via the hole 20b. As a result, the pixel electrode 13b, the inter-pixel electrode 15b, and the wiring portion 16b are at the same potential. Similarly, each pixel electrode 13c is provided in the insulating layer 17 Contact It is connected to the inter-pixel electrode 15c and the wiring portion 16c on the lower layer side via the hole 20c. As a result, the pixel electrode 13c, the inter-pixel electrode 15c, and the wiring portion 16c are at the same potential.

[0031] Each inter-pixel electrode 15a is arranged so as to overlap with the gap between two adjacent pixel electrodes 13a in the X direction in plan view. In the present embodiment, each inter-pixel electrode 15a is arranged such that its left outer edge in plan view and the right outer edge of the pixel electrode 13a arranged on its left are substantially in the same position in the vertical direction. Similarly, each inter-pixel electrode 15b is arranged so as to overlap with the gap between two adjacent pixel electrodes 13b in the X direction in plan view, and a part of the region is arranged so as to partially overlap with the pixel electrode 13b on its right. Similarly, each inter-pixel electrode 15c is arranged so as to overlap with the gap between two adjacent pixel electrodes 13c in the X direction in plan view, and a part of the region is arranged so as to partially overlap with the pixel electrode 13c on its right.

[0032] Each wiring portion 16a is connected to one of the inter-pixel electrodes 15a and extends upward in the figure. In the present embodiment, each wiring portion 16a is integrally provided with the same width as the corresponding inter-pixel electrode 15a. Each wiring portion 16a is connected to the driver 4.

[0033] Each wiring portion 16b is connected to one of the inter-pixel electrodes 15b and extends upward in the figure. Each wiring portion 16b is connected to the driver 4. In the present embodiment, in plan view, each wiring portion 16b has a partial region that partially overlaps with the pixel electrode 13b adjacent in the X direction to the inter-pixel electrode 15b to which it is connected, a partial region disposed between this pixel electrode 13b and the pixel electrode 13a adjacent in the Y direction thereto, and a partial region disposed so as to overlap with this pixel electrode 13a, and these partial regions are provided integrally.

[0034] In each wiring portion 16b, a partial region disposed between two adjacent pixel electrodes 13a and 13b in the Y direction also functions as an inter-pixel electrode disposed between these pixel electrodes 13a and 13b. Thereby, the region that substantially functions as a pixel region can be expanded.

[0035] Each wiring portion 16c is connected to one of the inter-pixel electrodes 15c and extends upward in the figure. Each wiring portion 16c is connected to the driver 4. In the present embodiment, in plan view, each wiring portion 16c has a partial region that partially overlaps with the pixel electrode 13c adjacent in the X direction to the inter-pixel electrode 15c to which it is connected, a partial region disposed between this pixel electrode 13c and the pixel electrode 13b adjacent in the Y direction thereto, a partial region disposed so as to overlap with this pixel electrode 13b with the insulating layer 17 therebetween, a partial region disposed so as to overlap with this pixel electrode 13b and the pixel electrode 13a adjacent in the Y direction thereto with the insulating layer 17 therebetween, and a partial region disposed between the pixel electrode 13a and the pixel electrode 13b, and these partial regions are provided integrally.

[0036] In each wiring portion 16c, a partial region disposed between two adjacent pixel electrodes 13b and 13c in the Y direction also functions as an inter-pixel electrode disposed between these pixel electrodes 13b and 13c. Thereby, the region that substantially functions as a pixel region can be expanded.

[0037] Here, when a voltage is applied to the pixel electrode 13c to make its region in a light-transmitting state, the same voltage is also applied to a partial region 21 of the wiring portion 16c, so this region also becomes a light-transmitting state. At this time, for example, if each region corresponding to the pixel electrode 13a or the pixel electrode 13b is in a non-transmitting state (or a low-transmitting state), the light-transmitting state of the partial region 21 may be visually recognized as a bright spot. Regarding this, it can be eliminated, for example, by leaving the portion corresponding to the partial region 21 of the insulating layer 17 as it is, as in the liquid crystal element 5a of the modified embodiment shown in FIG. 4(A). Also, as in the liquid crystal element 5b of the modified embodiment shown in FIG. 4(B), it can be eliminated by providing a columnar spacer (columnar body) 22 made of resin or the like so as to overlap with the partial region 21. Note that FIGS. 4(A) and 4(B) respectively correspond to the cross-sections taken along the c-c line shown in FIG. 3. Also, for the components common to the liquid crystal element 5 of the above-described embodiment and each of the liquid crystal elements 5a and 5b of the modified embodiments, the same reference numerals are given, and detailed descriptions thereof are omitted.

[0038] FIGS. 5(A) to 5(D) and FIGS. 6(A) and 6(B) are diagrams for explaining the manufacturing method of the liquid crystal element of the present embodiment. Note that FIGS. 5(A), 5(C), and 6(A) correspond to the cross-sections taken along the a-a line in FIG. 3 described above, and FIGS. 5(B), 5(D), and 6(B) correspond to the cross-sections taken along the b-b line in FIG. 3 described above. Also, in the following description, preferred examples of materials, film thicknesses, film-forming methods, etc. when forming various films and layers are shown, but these are merely examples.

[0039] Prepare the first substrate 11, and form each inter-pixel electrode 15 and each wiring portion 16 on one surface side of this first substrate 11 (see FIGS. 5(A) and 5(B)). For example, an ITO film can be formed by a sputtering method, and each inter-pixel electrode 15 and each wiring portion 16 can be obtained by patterning this ITO film by photolithography technology. Similarly, prepare the second substrate 12, and form the common electrode 14 on one surface side of this second substrate 12.

[0040] Next, an insulating layer 17 is formed so as to cover the inter-pixel electrodes 15 and each wiring portion 16 (see FIGS. 5(A) and 5(B)). For example, a SiNx film (e.g., a silicon nitride film such as a Si3N4 film) with a film thickness of about 0.3 μm is formed by plasma CVD. Further, a contact hole 20 is formed. The contact hole 20 can be formed, for example, by a reactive ion etching method using a fluorocarbon-based gas. The contact hole 20 preferably has a forward taper shape such that the width (diameter) becomes narrower as it approaches the first substrate 11, and particularly preferably, the taper shape is 40° to 60°. Thereby, the film forming property at the contact hole 20 is improved when forming the pixel electrode 13 described below.

[0041] Note that, as the material for forming the insulating layer layer 17, other inorganic insulating materials (e.g., a silicon oxide film such as SiO2) may be used, or organic insulating materials (e.g., acrylic-based materials) may be used.

[0042] Next, each pixel electrode 13 is formed on one surface side of the insulating layer 17 (see FIGS. 5(A) and 5(B)). Here too, for example, an ITO film is formed by sputtering, and each pixel electrode 13 can be obtained by patterning this ITO film by photolithography technology. At this time, a part of the pixel electrode 13 is also formed in the contact hole 20 described above, and the inter-pixel electrode 15 or the wiring portion 16 on the lower layer side is connected to the pixel electrode 13.

[0043] Next, the portion of the insulating layer 17 that exists between the pixel electrodes 13 in plan view is removed (see FIGS. 5(C) and 5(D)). This step is preferably performed, for example, using each pixel electrode 13 as an etching mask and by a reactive ion etching method using a fluorocarbon-based gas. Thereby, the opening 19 can be accurately provided in accordance with the position of each pixel electrode 13. Further, each opening 19 formed here preferably has a forward taper shape such that the width (diameter) becomes narrower as it approaches the first substrate 11, and particularly preferably, the taper shape is 40° to 60°.

[0044] In this step, instead of completely removing the portion of the insulating layer 17 between the pixel electrodes 13 to completely expose the inter-pixel electrodes 15, an insulating layer (thin layer portion) 17a covering the inter-pixel electrodes 15 (or wiring portions 16) may be left at the bottom of the opening 19 as in the modified embodiment shown in FIG. 7(A). That is, as an insulating film for the inter-pixel electrodes 15, Pixel an insulating layer 17a having a film thickness thinner than that of the insulating layer 17 can be provided in a region that does not overlap with the electrode 13. The formation of the insulating layer 17a can be realized by controlling the etching time and the like. In this case, the film thickness of the insulating layer 17a is relatively thin with respect to the film thickness of the original insulating layer 17, and is preferably about 30% (0.3 times), and preferably 60% (0.6 times) or less.

[0045] Also, as in the modified embodiment shown in FIG. 7(B), after this step, on the first substrate 11, an insulating layer 23 made of an SiO2 film or the like is preferably formed so as to cover the insulating layer 17, the inner walls of the opening 19, and the inter-pixel electrodes 15 and the wiring portions 16 exposed at the bottom thereof. In this case, it is also possible to provide the insulating layer 17a as shown in FIG. 7(A). That is, the insulating layer 23 is provided so as to continuously cover the pixel electrode 13 and the opening 19 (the inter-pixel electrode 15 or the insulating layer 17a exposed in the opening 19). The insulating layer 23 can be formed, for example, by flexographic printing. The film thickness can be, for example, 500 Å to 800 Å. In this case, the film forming property of the insulating layer 23 can be improved by making the opening 19 in a tapered shape. Similarly, it is also preferable to form an insulating layer so as to cover the common electrode 14 on the second substrate 12. In addition, when providing such an insulating layer 23, it is more preferable to form the above-mentioned insulating layer 17 using an inorganic material. Generally, since inorganic materials have higher heat resistance, it is possible to prevent the insulating layer 17 from deteriorating due to heat treatment or the like during the formation of the insulating layer 23 or the like.

[0046] Next, an alignment film (not shown) is formed on one surface side of each of the first substrate 11 and the second substrate 12. Here, a vertical alignment film is formed by flexographic printing, inkjet method, etc., and after heat treatment, alignment treatment such as rubbing is performed. The film thickness of the alignment film can be, for example, 500 Å to 800 Å. By making the opening 19 in a tapered shape, the film forming property of the alignment film can be improved.

[0047] Next, a sealing material (not shown) for sealing around the liquid crystal layer 18 is formed on one surface side of one of the first substrate 11 and the second substrate 12 (for example, the first substrate 11). Also, a gap control material is sprayed on one surface side of the other of the first substrate 11 and the second substrate 12 (for example, the second substrate 12). Here, a gap control material with a particle size of about 3 μm to 6 μm can be used, for example. Instead of the gap control material, a spacer such as a resin pillar may be provided.

[0048] Next, the first substrate 11 and the second substrate 12 are opposed to each other on their respective one surface sides and bonded together to form a cell (see FIGS. 6(A) and 6(B)). For example, with the first substrate 11 and the second substrate 12 overlapped, a heat treatment or a light irradiation treatment is performed while applying a constant pressure using a press or the like to cure the sealing material. At this time, the first substrate 11 and the second substrate 12 can be arranged such that the alignment treatment directions (for example, rubbing directions) with respect to each other are staggered. Note that the alignment treatment directions may be the same or may intersect, and may be appropriately selected depending on how the liquid crystal layer 18 operates in what operation mode.

[0049] Thereafter, a liquid crystal layer 18 is formed by filling a liquid crystal material between the first substrate 11 and the second substrate 12, and the injection port is sealed with a sealing material. Thereby, the liquid crystal element 5 shown in FIGS. 2(A) and 2(B) is completed. Here, although the vacuum injection method is assumed as the filling method of the liquid crystal material, the ODF method may be used.

[0050] Next, the effects obtained by the liquid crystal element 5 of the present embodiment will be described. FIG. 8(A) is a diagram for explaining measurement points (measurement locations) of electro-optical characteristics in a liquid crystal element. FIG. 8(B) is a diagram showing a measurement example of electro-optical characteristics. As shown in FIG. 8(A), the relationship between the applied voltage and the transmittance at each of measurement point A that passes through the inter-pixel electrode 15 and does not pass through the insulating layer 17, and measurement point B that passes through the pixel electrode 13 and the insulating layer 17 is measured, and a measurement example thereof is shown in FIG. 8(B).

[0051] As shown in FIG. 8(B), it can be seen that the characteristics particularly near the threshold value at measurement points A and B are almost the same. This is because by providing the opening 19 in the insulating layer 17, almost the same voltage is applied to the liquid crystal layer 18 at both measurement points A and B. It is common general knowledge in the art that the threshold voltage does not depend on the layer thickness of the liquid crystal layer 18. A slight difference in transmittance is seen in a relatively high range of the applied voltage, which is considered to be due to the difference in the liquid crystal layer thickness caused by the presence or absence of the insulating layer 17. The insulating layer 17 is, for example, about 0.3 μm, and it can be said that the difference in the liquid crystal layer thickness is very small. Therefore, considering the case of obtaining a halftone transmittance, it can be said that the transmittance for the same applied voltage is almost equal at measurement points A and B. That is, an illumination device in which dark lines or bright lines are less likely to occur in the portion corresponding to the inter-pixel electrode 15 regardless of the applied voltage can be realized. In principle, the same effect can be obtained in an illumination device using a liquid crystal element of a modified embodiment in which the above-described insulating layer 17a remains (see FIG. 7(A)) or a modified embodiment in which the insulating layer 23 is provided entirely (see FIG. 7(B)).

[0052] FIGS. 9(A) and 9(B) are diagrams showing measurement examples of electro-optical characteristics in a liquid crystal element of a modified embodiment in which the insulating layer (thin layer portion) 17a remains (see FIG. 7(A)). Note that measurement points A and B are the same as those shown in FIG. 8(A) described above. As shown in each figure, by leaving the insulating layer 17a in the portion corresponding to the inter-pixel electrode 15, an effect of correcting the transmittance difference at measurement points A and B can be obtained. The reason therefor will be considered below.

[0053] Since the layer thickness of the liquid crystal layer 18 is different between the measurement point A and the measurement point B, a transmittance difference corresponding to that amount can occur. Generally, when the liquid crystal layer 18 is in the vertical alignment mode, there is a layer thickness dependence of the transmittance. For example, considering a vertical alignment type liquid crystal element in which the chromaticity xy value becomes white when the liquid crystal layer thickness is 4 μm, when the liquid crystal layer thickness is slightly thicker than that, the chromaticity xy value shifts slightly toward the yellow side, but the transmittance tends to be slightly higher. It is considered that the transmittance difference at the measurement points A and B in the electro-optical characteristics shown in FIG. 8(B) described above shows a very slight influence.

[0054] On the other hand, when the insulating layer 17a exists at the position corresponding to the measurement point A, the threshold value at the measurement point A becomes slightly higher. This is because the applied voltage is divided between the insulating layer 17a and the liquid crystal layer 18. For example, assuming that the dielectric constant of the insulating layer 17a and the dielectric constant of the liquid crystal layer 18 are approximately equal for the sake of simplicity of calculation, the voltage (divided voltage) applied to the liquid crystal layer 18 at the measurement point A can be considered simply by the film thickness ratio of the layer thickness of the liquid crystal layer 18 and the layer thickness of the insulating layer 17a at the measurement point A.

[0055] FIG. 9(A) shows the electro-optical characteristics when the layer thickness of the insulating layer 17a is 0.09 μm. As the threshold value of the liquid crystal layer 18, it is about 1.02 times that when the insulating layer 17a does not exist, and almost the same transmittance is obtained at the measurement points A and B in the entire range of the applied voltage. Further, FIG. 9(B) shows the electro-optical characteristics when the layer thickness of the insulating layer 17a is 0.17 μm. As the threshold value of the liquid crystal layer 18, it is about 1.04 times that when the insulating layer 17a does not exist. Although the transmittance difference is suppressed within an allowable range compared with the previous example, a slight transmittance difference can be seen in the low applied voltage range (generally in the range of 3V to 4.5V). Since the layer thickness of the insulating layer 17 is 0.3 μm, it can be said that it is preferable to leave about 30% of the original layer thickness of the insulating layer 17 as the film thickness of the insulating layer 17a, and it is preferably about 60% or less.

[0056] According to the embodiment as described above, in the liquid crystal element used in a vehicle lamp system (lighting device) capable of freely controlling the light distribution pattern, it is possible to improve the appearance of the light distribution pattern while simplifying the manufacturing process of the liquid crystal element.

[0057] Note that the present disclosure is not limited to the content of the above-described embodiment, and various modifications can be made and implemented within the scope of the gist of the present disclosure. For example, the configuration of the vehicle lamp system shown in the above-described embodiment is an example and is not limited. Further, in the above-described embodiment, an example in which the present invention is applied to a system that performs selective light irradiation on the front of the vehicle has been described, but the application range of the present invention is not limited thereto. For example, the present invention may be applied to a system that irradiates light obliquely forward of the vehicle according to the traveling direction of the vehicle, a system that adjusts the optical axis of the headlamp according to the inclination of the vehicle in the front-rear direction, a system that electronically switches between the high beam and the low beam of the headlamp, and the like. Furthermore, the present invention may be applied not only to vehicle applications but also to lighting devices in general.

Explanation of Reference Numerals

[0058] 1: Light source, 2: Camera, 3: Controller, 4: Driver, 5, 5a, 5b: Liquid crystal element, 6a, 6b: Polarizing plate, 7: Projection lens, 11: First substrate, 12: Second substrate, 13: Pixel electrode, 14: Common electrode, 15: Inter-pixel electrode, 16: Wiring portion, 17, 17a: Insulating layer, 18: Liquid crystal layer, 19: Opening, 20: Contact hole

Claims

1. A first substrate and a second substrate arranged opposite to each other, a liquid crystal layer disposed between the first substrate and the second substrate, a plurality of auxiliary electrodes disposed on one surface side of the first substrate facing the liquid crystal layer, an insulating layer disposed on the one surface side of the first substrate to cover the plurality of auxiliary electrodes, a plurality of pixel electrodes disposed between the insulating layer and the liquid crystal layer of the first substrate, a counter electrode disposed on one surface side of the second substrate facing the liquid crystal layer, comprising, in a plan view, the plurality of pixel electrodes are arranged with gaps provided between them in at least one direction, each of the plurality of auxiliary electrodes is arranged to overlap with the gap between the adjacent pixel electrodes in a plan view, and is mutually connected through a contact hole provided in one of the adjacent pixel electrodes and the insulating layer, the insulating layer has an opening at a portion corresponding to the gap between the adjacent pixel electrodes, a liquid crystal element.

2. The insulating layer has a substantially same planar shape as the plurality of pixel electrodes in a plan view, and a portion where the pixel electrodes do not exist corresponds to the opening, The liquid crystal element according to claim 1.

3. The insulating layer is composed of a silicon nitride film or a silicon oxide film, The liquid crystal element according to claim 1 or 2.

4. The opening of the insulating layer has a tapered shape in which the width or diameter becomes smaller as it approaches the one surface of the first substrate, The liquid crystal element according to any one of claims 1 to 3.

5. The insulating layer has a thin layer portion which is a portion covering a part of the auxiliary electrode at the bottom of the opening and has a relatively smaller film thickness than a portion corresponding to the plurality of pixel electrodes, The liquid crystal element according to any one of claims 1 to 4.

6. The layer thickness of the thin layer portion is 0.3 times or more and 0.6 times or less of the layer thickness of the portion corresponding to the plurality of pixel electrodes of the insulating layer, The liquid crystal element according to claim 5.

7. Further comprising a second insulating layer continuously covering the plurality of pixel electrodes and the opening, The liquid crystal element according to any one of claims 1 to 6.

8. The liquid crystal element according to any one of claims 1 to 7, a light source for making light incident on the liquid crystal element, a lens for condensing light transmitted through the liquid crystal element, comprising, an illumination device.

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