Illumination device and vehicle headlight system

Abstract

The light distribution control of irradiation light is diversified. The lighting device includes: a light source; a convergence unit; a liquid crystal element disposed at a focal position of the light focused by the focusing unit; a projection lens disposed at a position where the light transmitted through the liquid crystal element can be incident; a first polarizing plate disposed between the light source and the liquid crystal element; a second polarizing plate disposed between the liquid crystal element and the projection lens; and a diffractive optical element disposed between the light source and the liquid crystal element, the diffractive optical element having a plurality of light modulation regions, each of the light modulation regions being electrically switchable between a first state in which the refractive index changes periodically or continuously and a second state in which the refractive index is substantially the same. The first state is capable of generating a diffraction effect on incident light, and each of the plurality of light modulation regions is disposed at a position closer to the light source than the focal position and into which the light can be incident.

Description

Technical Field

[0001] The present invention relates to a lighting device and a vehicle headlamp system. Background Art

[0002] Japanese Patent Gazette No. 5238124 (Patent Document 1) describes a lamp having a light source, a reflector, and a lens, and further having a liquid crystal optical element, which is disposed between the light source and the lens and can perform light distribution control over a wide range, which is wider than the range of basic light distribution formed by the light source, the reflector, and the lens. The liquid crystal optical element of the lamp is configured such that when no voltage is applied, it is transparent due to the uniformity of the molecular arrangement and refractive index of the mutually adjacent grating part and non-grating part, and when voltage is applied, the light guided in the liquid crystal layer is refracted in a predetermined direction to become scattered light due to the refractive index difference between the grating part and the non-grating part, thereby expanding the range of irradiation directions for external irradiation.

[0003] Prior art literature

[0004] Patent Literature

[0005] Patent Document 1: Japanese Patent No. 5238124 Summary of the invention

[0006] Problems to be solved by the invention

[0007] One of the objects of a specific embodiment of the present invention is to provide a technology capable of realizing diversified light distribution control of irradiated light in a lighting device such as a vehicle lamp and a system using the lighting device.

[0008] Means for solving problems

[0009] [1] An illumination device according to one embodiment of the present invention includes: (a) a light source; (b) a converging portion for converging the light emitted from the light source; (c) a liquid crystal element arranged at a focal position of the light converged by the converging portion; (d) a projection lens arranged at a position where the light transmitted through the liquid crystal element can be incident; (e) a first polarizing plate arranged between the light source and the liquid crystal element; (f) a second polarizing plate arranged between the liquid crystal element and the projection lens; and (g) a diffractive optical element arranged between the light source and the liquid crystal element, (h) the diffractive optical element has a plurality of light modulation regions, each of which can be electrically switched between a first state and a second state, the first state being a state in which a refractive index changes periodically or continuously, and the second state being a state in which the refractive index is substantially the same, (i) the first state can produce a diffraction effect on incident light, and (j) the plurality of light modulation regions are respectively arranged at positions where the light can be incident and closer to the light source than the focal position.

[0010] [2] A vehicle lighting system according to one embodiment of the present invention comprises: (a) a vehicle lighting device configured using the lighting device of [1]; and (b) a controller connected to the vehicle lighting device for controlling the operation of the liquid crystal element of the vehicle lighting device and the operation of the diffractive optical element according to conditions around the vehicle.

[0011] According to the above configuration, it is possible to realize diversification of the light distribution control of irradiated light in a lighting device such as a vehicle lamp and a system using the lighting device. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 It is a diagram showing a configuration of a vehicle lighting system according to an embodiment.

[0013] Figure 2 It is a schematic plan view for explaining a structural example of a diffractive optical element.

[0014] Figure 3 (A) schematically shows a diffractive optical element. Figure 2 A cross-sectional view of a portion of the cross-sectional structure along the aa line direction shown. Figure 3 (B) is a schematic plan view for explaining a structural example of a comb-teeth electrode of a diffractive optical element.

[0015] Figure 4 It is a schematic cross-sectional view for explaining a structural example of a liquid crystal element.

[0016] Figure 5 It is a schematic top view for explaining a more specific example of a liquid crystal element.

[0017] Figure 6 This is a diagram for explaining the structure of an optical system used to examine the driving conditions of a diffractive optical element.

[0018] Figure 7 (A)~ Figure 7 (C) is a diagram for explaining a method of driving a diffractive optical element.

[0019] Figure 8 (A)~ Figure 8 (C) is a diagram showing a measurement example of light transmitted through a diffractive optical element.

[0020] Fig. 9 The diagram schematically shows light emitted from a light source, focused by a reflector, and incident on a diffractive optical element in a cone shape.

[0021] Fig.10 (A)~ Fig.10(C) is a diagram showing a measurement example of the light intensity distribution of projection light.

[0022] Fig.11 (A) Fig.11 (B) is a diagram for explaining a measurement system used for measuring the transmittance of a diffractive optical element.

[0023] Fig.12 (A) is a graph showing the relationship between the light receiving angle and the transmittance when the projection angle of incident parallel light is set to 0°. Fig.12 (B) is a graph showing the relationship between the light receiving angle and the transmittance when the projection angle of the incident parallel light is set to +30°. Fig.12 (C) is a graph showing the relationship between the light receiving angle and the transmittance when the projection angle of the incident parallel light is set to +60°.

[0024] Fig.13 (A)~ Fig.13 (C) is a diagram schematically showing the state of light incident on a liquid crystal element due to the diffraction effect of a diffractive optical element.

[0025] Fig.14 (A) is a diagram showing an example of the illuminance distribution of projection light when no voltage is applied to the diffractive optical element. Fig.14 (B) is a diagram showing the result of obtaining, by calculation, the illumination distribution of the projection light when a voltage is applied to all the light modulation regions of the diffractive optical element. Fig.14 (C) is a diagram showing the result of obtaining, by calculation, the illumination distribution of the projection light when a voltage is applied to one light modulation region of the diffractive optical element. DETAILED DESCRIPTION

[0026] Figure 1 It is a diagram showing a configuration of a vehicle lighting system according to an embodiment. Figure 1 The vehicle lamp system shown is configured to include a vehicle lamp (lighting device) 1, a controller 2, and a camera 3. The vehicle lamp system detects the positions of the front vehicle, pedestrians' faces, etc. existing around the vehicle (i.e., the conditions around the vehicle) based on the image of the vehicle's surroundings captured by the camera 3, and sets a certain range including the position of the front vehicle, etc. as a dimming range (or non-irradiation range) according to the detection result, sets the range other than the range as a light irradiation range to selectively irradiate light, and irradiates light in various shapes onto the road surface.

[0027] The vehicle lamp 1 is disposed, for example, at a predetermined position in front of the vehicle to form irradiation light for illuminating the front of the vehicle. In addition, the vehicle lamp 1 is provided one on each side of the vehicle, but only one is shown here.

[0028] The controller 2 controls the operation of the light source 11, the diffractive optical element 13, and the liquid crystal element 15 of the vehicle lamp 1. The controller 2 is implemented by executing a predetermined operation program in a computer system having a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), etc. The controller 2 of this embodiment turns on the light source 11 according to the operation state of a light switch (not shown) provided at the driver's seat, and sets a light distribution pattern corresponding to an object such as a front vehicle (oncoming vehicle, preceding vehicle), a pedestrian, a road sign, a white line on the road, etc. detected by the camera 3, and supplies a control signal for forming an image corresponding to the light distribution pattern to the liquid crystal element 15.

[0029] The camera 3 captures the space in front of the vehicle to generate an image, and performs a predetermined image recognition process on the image to detect the position, range, size, category, etc. of the object such as the vehicle in front. The detection result of the image recognition process is provided to the controller 2 connected to the camera 3. The camera 3 is set at a predetermined position inside the vehicle's cabin (for example, the upper part of the front windshield), or at a predetermined position outside the vehicle's cabin (for example, inside the front bumper). In the case where the vehicle is equipped with a camera for other purposes (for example, an automatic braking system, etc.), the camera can also be shared.

[0030] In addition, the image recognition processing function in the camera 3 may be replaced by the controller 2. In this case, the camera 3 outputs the generated image to the controller 2, and the image recognition processing is performed on the controller 2 side based on the image. Alternatively, both the image and the result of the image recognition processing based on the image may be supplied from the camera 3 to the controller 2. In this case, the controller 2 may further perform its own image recognition processing using the image obtained from the camera 3.

[0031] Figure 1 The vehicle lamp 1 shown is composed of a light source 11, a reflector (reflection component) 12, a diffractive optical element 13, a polarizing plate 14, a liquid crystal element 15, an optical compensation plate 16, a polarizing plate 17, and a projection lens 18. These elements are integrated by being accommodated in a housing (frame), for example. In addition, the light source 11, the diffractive optical element 13, and the liquid crystal element 15 are respectively connected to the controller 2 and receive the operation control of the controller 2.

[0032] The light source 11 includes a driving circuit and emits light under the control of the controller 2. As an example, the light source 11 is a white LED, which includes a blue LED and a yellow phosphor arranged at a position where light emitted by the blue LED is incident. The light source 11 excites the yellow phosphor through the blue LED, and obtains white by mixing blue and yellow.

[0033] The reflector 12 is arranged corresponding to the light source 11, and the light emitted from the light source 11 is reflected and converged in a focused manner at the position of the liquid crystal element 15 (as an example, the approximate center of the thickness direction of the liquid crystal element 15) and is incident on the liquid crystal element 15. The reflector 12 is, for example, a reflector having an elliptical reflecting surface. In this case, the light source 11 can be arranged near the focus of the reflecting surface of the reflector 12. In addition, a lens can be used as a converging portion instead of the reflector 12.

[0034] The diffractive optical element 13 operates under the control of the controller 2 and increases or decreases the width of incident light or changes the traveling direction of incident light by utilizing the diffraction effect (diffraction phenomenon) of light. The detailed configuration of the diffractive optical element 13 will be described later.

[0035] The polarizer 14 is arranged on the light incident surface side of the liquid crystal element 15. The polarizer 17 is arranged on the light exit surface side of the liquid crystal element 15. An image corresponding to the light distribution pattern of the light irradiated to the front of the vehicle is formed by these polarizers 14, polarizer 17 and the liquid crystal element 15 arranged therebetween. As an example, the transmission axes of the polarizers 14 and 17 are arranged in directions that are substantially perpendicular to each other. In addition, the transmission axes of the polarizers 14 and 17 are arranged in directions that are substantially 45° in angle with respect to the orientation direction of the liquid crystal layer of the liquid crystal element 15 when no voltage is applied at the approximate center of the layer thickness direction when viewed from above.

[0036] The liquid crystal element 15 is arranged at a position including the focus of the light reflected and converged by the reflector 12, and is arranged for the light to be incident. The liquid crystal element 15 has a plurality of pixel units (light modulation units) that can be controlled independently of each other. In the present embodiment, the liquid crystal element 15 has a driver (not shown) for providing a driving voltage to each pixel unit. The driver provides the liquid crystal element 15 with a driving voltage for individually driving each pixel unit based on a control signal supplied from the controller 2. As shown in the figure with a thin line indicating the approximate trajectory (optical path) of the light emitted from the light source 11, the light incident on the liquid crystal element 15 is incident at a wide angle relative to the light incident surface side of the liquid crystal element 15. Specifically, the light is incident at a wide angle of about 40° to 60° relative to the normal direction of the light incident surface.

[0037] The optical compensation plate 16 is used to compensate for the phase difference of light passing through the liquid crystal element 15 and improve the polarization degree, and is arranged on the light emitting surface side of the liquid crystal element 15. Specifically, the phase difference of the optical compensation plate 16 is set so that the phase difference obtained by adding the phase difference of the liquid crystal layer 15 is 0 or a value close to 0. In addition, the optical compensation plate 16 can also be omitted.

[0038] The projection lens 18 is disposed at a position where the light reflected by the reflector 12 and focused and transmitted through the liquid crystal element 15 can enter, and projects the incident light forward of the vehicle. The projection lens 18 is disposed so that its focal point is connected to the liquid crystal layer of the liquid crystal element 15 .

[0039] Figure 2 1 is a schematic top view for explaining a structural example of a diffractive optical element. The diffractive optical element 13 shown in the figure is configured to include: three light modulation areas 30a, 30b, and 30c arranged along the X direction in the figure; four terminal portions 31a for providing a driving voltage to the light modulation area 30a; four terminal portions 31b for providing a driving voltage to the light modulation area 30b; and four terminal portions 31c for providing a driving voltage to the light modulation area 30c. The light modulation areas 30a, 30b, and 30c are arranged, for example, along the left-right direction (horizontal direction) of the vehicle. In addition, in the figure, in order to easily distinguish the light modulation areas 30a, 30b, and 30c, gaps are drawn between the light modulation areas 30a, etc., but in fact, the light modulation areas 30a, etc. can be provided without providing these gaps.

[0040] The light modulation region 30a is operated by using the driving voltage input by each terminal portion 31a, and mainly bends the traveling direction of the incident light or expands the width of the incident light by the diffraction effect. Similarly, the light modulation region 30b is operated by using the driving voltage input by each terminal portion 31b, and mainly bends the traveling direction of the incident light or expands the width of the incident light by the diffraction effect. Similarly, the light modulation region 30c is operated by using the driving voltage input by each terminal portion 31c, and mainly bends the traveling direction of the incident light or expands the width of the incident light by the diffraction effect. In addition, in any light modulation region 30a, in addition to diffraction, refraction can also occur.

[0041] Figure 3 (A) schematically shows a diffractive optical element. Figure 22 is a cross-sectional view of a portion of the cross-sectional structure in the direction of the aa line shown in FIG. 2. In addition, the cross-sectional structure of a portion of the light modulation region 30a is described here, but the cross-sectional structure is the same in the other light modulation regions 30b and 30c. The light modulation region 30a in the diffractive optical element 13 of this embodiment is configured to include a first substrate 32 and a second substrate 33 arranged opposite to each other, a common electrode 34, an opposing electrode 35, an insulating film 36, comb-shaped electrodes 37 and 38, alignment films 39 and 40, and a liquid crystal layer 41.

[0042] The first substrate 32 and the second substrate 33 are, for example, rectangular substrates when viewed from above, and are arranged opposite to each other. The first substrate 32 and the second substrate 33 are transparent substrates such as glass substrates or plastic substrates. Spherical spacers (not shown) such as those made of resin are dispersed between the first substrate 32 and the second substrate 33, and the substrate gap is maintained at a desired size (for example, several μm) by these spherical spacers. In addition, instead of the spherical spacers, columnar bodies made of resin or the like can be set on the first substrate 32 side or the second substrate 33 side and used as spacers.

[0043] The common electrode 34 is provided on one side of the first substrate 32, closer to the one side than the comb-shaped electrodes 37 and 38, and is arranged to overlap with the comb-shaped electrodes 37 and 38 when viewed from above. The counter electrode 35 is provided on one side of the second substrate 33, and is arranged to overlap with the comb-shaped electrodes 37 and 38 when viewed from above. These common electrodes 34 and counter electrodes 35 are formed by appropriately patterning a transparent conductive film such as indium tin oxide (ITO). The common electrode 34 and counter electrodes 35 are respectively provided in a range that roughly coincides with the outer edge of the light modulation area 30a when viewed from above, for example.

[0044] The common electrode 34 and the counter electrode 35 are connected to any one of the above-mentioned terminal portions 31a, respectively, and the applied voltage can be controlled independently. In addition, each terminal portion 31a is provided on the first substrate 32, for example. In this case, the counter electrode 35 and the corresponding terminal portion 31a are electrically connected to each other via, for example, an anisotropic conductive film (not shown) provided at an appropriate position between the first substrate 32 and the second substrate 33.

[0045] The insulating film 36 is provided between the common electrode 34 and the comb-shaped electrodes 37 and 38 on one side of the first substrate 32 in a manner covering the common electrode 34. The insulating film 36 is a film for achieving electrical insulation between the common electrode 34 and the comb-shaped electrodes 37 and 38. As the insulating film 36, for example, a siloxane-based insulating film, an organic insulating film such as an acrylic-based film, an inorganic insulating film such as a SiNx film and a SiOx film can be used. In addition, the insulating film 36 is patterned and provided in a manner not to cover the terminal portions 31a but to expose them.

[0046] Each comb-shaped electrode 37, 38 is provided on the upper side (the side opposite to the second substrate 33) of the insulating film 36 on one side of the first substrate 32. These comb-shaped electrodes 37, 38 are formed by appropriately patterning a transparent conductive film such as indium tin oxide (ITO), for example. Each comb-shaped electrode 37, 38 is arranged so as to overlap with the liquid crystal layer 41 when viewed from above.

[0047] The orientation film 39 is arranged on the upper side of the first substrate 32 in such a manner as to cover the comb-shaped electrodes 37 and 38. The orientation film 40 is arranged on the upper side of the second substrate 33 in such a manner as to cover the opposing electrode 35. These orientation films 39 and 40 are used to limit the orientation state of the liquid crystal layer 41. Each orientation film 39 and 40 is subjected to a uniaxial orientation treatment such as a friction treatment, and has a uniaxial orientation limiting force that specifies the orientation of the liquid crystal molecules of the liquid crystal layer 41 along this direction. The directions of the orientation treatment of each orientation film 39 and 40 are set to be different from each other (antiparallel), for example. As each orientation film 39 and 40, for example, a horizontal orientation film or a vertical orientation film is appropriately used. For example, a polyimide orientation film, a siloxane-based orientation film, etc. can be used.

[0048] The liquid crystal layer 41 is provided between the first substrate 32 and the second substrate 33. The liquid crystal layer 41 is formed using, for example, a nematic liquid crystal material having fluidity. The liquid crystal layer 41 can be formed using a liquid crystal material having negative dielectric anisotropy or a liquid crystal material having positive dielectric anisotropy. The thickness of the liquid crystal layer 41 can be set to about 4 μm, for example.

[0049] Figure 3 (B) is a schematic top view for explaining the construction example of the comb-tooth electrode of the diffractive optical element. As shown in the figure, the comb-tooth electrodes 37 and 38 are respectively composed of a plurality of electrode branches extending along the Y direction in the figure, and the electrode branches are arranged alternately one by one along the X direction in the figure. In addition, Figure 3 The X and Y directions of (B) are Figure 2 The X direction and Y direction are consistent with each other. In addition, the X direction is roughly consistent with the left-right direction (horizontal direction) of the vehicle, and the Y direction is roughly consistent with the up-down direction (vertical direction) of the vehicle. In addition, the X direction and the Y direction are respectively directions roughly perpendicular to the thickness direction of the liquid crystal layer 41 of the diffractive optical element 13. The comb-toothed electrode 37 is connected to the wiring portion 42, and is connected to one of the above-mentioned terminal portions 31a via the wiring portion 42. The comb-toothed electrode 38 is connected to the wiring portion 43, and is connected to one of the above-mentioned terminal portions 31a via the wiring portion 42.

[0050] The length (x1) of each electrode branch of the comb-tooth electrode 37 in the X direction is, for example, 5 μm or less, and the distance (x2) between adjacent electrode branches is, for example, 15 μm or less. Similarly, the length (x3) of each electrode branch of the comb-tooth electrode 38 in the X direction is, for example, 5 μm or less, and the distance (x4) between adjacent electrode branches is, for example, 15 μm or less. In addition, the distance (x5) between an electrode branch of the comb-tooth electrode 37 and an electrode branch of the comb-tooth electrode 38 adjacent thereto is, for example, 5 μm or less. In order to produce the diffraction effect in the diffraction optical element 13, it is particularly preferred to set the length (x1) of each electrode branch in the X direction to 5 μm or less, and set the distance (x5) between an electrode branch of the comb-tooth electrode 37 and an electrode branch of the comb-tooth electrode 38 adjacent thereto to 5 μm or less.

[0051] In order to produce the diffraction effect of the diffractive optical element 13 more significantly, the setting values ​​of x1, x2, x3, x4, and x5 are preferably as small as possible. Thus, when a voltage is applied to the liquid crystal layer 41 using the comb-shaped electrodes 37, 38, the common electrode 34, and the opposing electrode 35, a state in which the refractive index changes periodically for a wavelength equal to or less than the wavelength of visible light can be produced in the liquid crystal layer 41. By causing light to be incident on the diffractive optical element 13 in this state, a diffraction effect can be independently produced in each of the above-mentioned light modulation regions 30a, 30b, and 30c, and the traveling direction of light can be bent and the light can be diffused as a whole.

[0052] Here, the relationship between the positive and negative dielectric anisotropy of the liquid crystal layer 41, the type of alignment film (vertical / horizontal), the orientation treatment direction of the alignment film, and the extension direction of each electrode branch of the comb-shaped electrodes 37 and 38 is explained. First, when a vertical alignment film is used as the alignment film, the orientation treatment direction relative to the extension direction of each electrode branch (the Y direction in the illustrated example) is not particularly limited. In addition, the dielectric anisotropy of the liquid crystal layer 41 can be positive or negative. It has been confirmed that in a liquid crystal element for a normal display application, when a liquid crystal material with a positive dielectric anisotropy is used under this condition, it is difficult to cause the liquid crystal layer 41 to produce an orientation change, but it can operate in a diffractive optical element 13 using comb-shaped electrodes 37 and 38 as in the present embodiment.

[0053] Next, when a horizontal alignment film is used as the alignment film and the dielectric anisotropy of the liquid crystal layer 41 is positive, the alignment treatment direction is preferably a direction that is not perpendicular to the extension direction of each electrode branch (in the example shown in the figure, the Y direction), such as a direction preferably in parallel, a direction that is 45° to the extension direction, etc. In addition, when a horizontal alignment film is used as the alignment film and the dielectric anisotropy of the liquid crystal layer 41 is negative, the alignment treatment direction is preferably a direction that is not parallel to the extension direction of each electrode branch (in the example shown in the figure, the Y direction), such as a direction preferably in vertical, a direction that is 45° to the extension direction, etc.

[0054] Figure 4 Schematic cross-sectional view for explaining a structural example of a liquid crystal element. A segment display type liquid crystal element is illustrated here. Specifically, the illustrated liquid crystal element 15 is configured to include a first substrate 51 and a second substrate 52 arranged opposite to each other, a plurality of pixel electrodes 53, an opposing electrode 54, alignment films 55 and 56, a liquid crystal layer 57, and a sealing material 58.

[0055] The first substrate 51 and the second substrate 52 are rectangular substrates when viewed from above, and are arranged opposite to each other. Spherical spacers (not shown) such as those made of resin films are dispersed between the first substrate 51 and the second substrate 52, and the substrate gap is maintained at a desired size (e.g., several μm) by these spherical spacers.

[0056] In addition, instead of the spherical spacers, columnar bodies made of resin or the like may be provided on the first substrate 51 side or the second substrate 52 side and used as spacers. In the present embodiment, the substrates are arranged so that the first substrate 51 faces the polarizing plate 14 and the second substrate 52 faces the polarizing plate 17. That is, the substrates are arranged so that the second substrate 52 side becomes the light emitting side of the liquid crystal element 15 and the first substrate 51 side becomes the light incident side of the liquid crystal element 15.

[0057] A plurality of pixel electrodes 53 are provided on one surface of the first substrate 51. The pixel electrodes 53 are formed by appropriately patterning a transparent conductive film such as indium tin oxide (ITO). In this embodiment, a pixel portion is formed at a portion where each pixel electrode 53 faces a counter electrode 54.

[0058] The counter electrode 54 is provided on one surface side of the second substrate 52. The counter electrode 54 is provided integrally so as to face each pixel electrode 53 of the first substrate 51. The counter electrode 54 is formed by appropriately patterning a transparent conductive film such as indium tin oxide (ITO), for example.

[0059] The orientation film 55 is arranged on the upper side of the first substrate 51 in such a manner as to cover each pixel electrode 53. The orientation film 56 is arranged on the upper side of the second substrate 52 in such a manner as to cover the opposing electrode 54. These orientation films 55 and 56 are used to limit the orientation state of the liquid crystal layer 57. Each orientation film 55, 56 is subjected to a uniaxial orientation treatment such as a friction treatment, and has a uniaxial orientation limiting force that specifies the orientation of the liquid crystal molecules of the liquid crystal layer 57 along this direction. The directions of the orientation treatment of each orientation film 55, 56 are set to be different from each other (antiparallel), for example. The pretilt angle near the interface between each orientation film 55, 56 and the liquid crystal layer 57 is, for example, about 89°. As an example, in the present embodiment, an orientation film formed of alicyclic polyimide or alicyclic polyamic acid is used.

[0060] The liquid crystal layer 57 is provided between the first substrate 51 and the second substrate 52. The liquid crystal layer 57 is formed of, for example, a nematic liquid crystal material having fluidity. The liquid crystal layer 57 is formed of, for example, a liquid crystal material having negative dielectric anisotropy. The thickness of the liquid crystal layer 57 can be set to, for example, about 4 μm.

[0061] The sealing material 58 is provided between the first substrate 51 and the second substrate 52 so as to surround the liquid crystal layer 57 , and seals the liquid crystal layer 57 .

[0062] In addition, there are no particular limitations on the internal structure and driving method of the liquid crystal element 15 as long as the transmitted light can be freely modulated to form a desired image. For example, it can be configured as an active matrix liquid crystal element in which thin film transistors are corresponding to each pixel portion, or it can be configured as a simple matrix liquid crystal element in which a plurality of stripe-shaped transparent electrodes are arranged opposite to each other and each area where these transparent electrodes overlap each other is used as a pixel portion. Furthermore, as the liquid crystal element 15, a segmented display type liquid crystal element can be used, which has a plurality of pixel electrodes of any shape arranged on one substrate and one (or more) opposing electrodes arranged on another substrate. Regarding the driving method in this case, multi-channel driving can be used, and static driving can also be used.

[0063] Figure 5 1 is a schematic top view for illustrating a more specific embodiment of a liquid crystal element. The liquid crystal element 15 of the illustrated embodiment has a plurality of pixel portions (segmented regions) arranged in an effective display area which is an inner area surrounded by a sealing material 58 when viewed from above. In the illustrated liquid crystal element 15, each area represented by a rectangular area or a triangular area of ​​various sizes corresponds to a pixel. In the figure, several pixel portions are denoted by reference numerals for illustration. In this embodiment, the pixel electrodes (described later) constituting each pixel are arranged in a shape substantially the same as the shape of each pixel portion.

[0064] For example, pixel portion 70a is a small square pixel portion with a small length in both the x-direction and the y-direction. Pixel portion 70b is a trapezoidal pixel portion with a larger length in the x-direction than pixel portion 70a and a slightly larger length in the y-direction than pixel portion 70a. Pixel portion 70c is a vertically elongated rectangular pixel portion with a small length in the x-direction and a relatively large length in the y-direction. Pixel portion 70d is a vertically elongated rectangular pixel portion with a smaller length in the x-direction than pixel portion 70b. Pixel portion 70e is a triangular pixel portion with a relatively large length in the x-direction and a relatively large length in the y-direction (the length of one side). Pixel portion 70f is a large horizontally elongated pixel portion with a very large length in the x-direction. Pixel portion 70g is a vertically elongated rectangular pixel portion. Pixel portion 70h is a horizontally elongated pixel portion with a very large length in the x-direction. In addition, as shown in the figure, in addition to the illustrated structure, liquid crystal element 15 also has pixel portions of various sizes and shapes. Each pixel unit 70 a and the like can independently control the transmission and non-transmission of light, and by appropriately controlling these, it is possible to form irradiated light of various light distribution patterns corresponding to the situation ahead of the vehicle.

[0065] Figure 6 This is a diagram for explaining the structure of an optical system used to examine the driving conditions of a diffractive optical element. Figure 6 The optical system shown is configured to include: a light source 90 that emits collimated light; a polarizer 91 that is arranged in the traveling direction of the light emitted from the light source 90; an aperture plate 92 that is used to reduce the light that passes through the polarizer 91 and has an opening; a diffractive optical element 13 that is arranged at a position where the light that passes through the aperture plate 92 can be incident; and a screen 93 that is irradiated with the light emitted from the diffractive optical element 13. The transmission axis of the polarizer 91 is the Y direction shown in the figure. The diameter of the opening of the aperture plate 92 is 5 mm. The orientation processing direction of the diffractive optical element 13 is the X direction shown in the figure (the direction perpendicular to the transmission axis of the polarizer 91), and it is anti-parallel. The distance between the diffractive optical element 13 and the screen 93 is 10 m.

[0066] Regarding the diffusion degree of the light 94 transmitted through the diffractive optical element 13 and irradiated to the screen 93, the difference caused by the driving method of the diffractive optical element 13 was verified using the above-mentioned optical system. Regarding the diffractive optical element 13 used in the verification, x1 of the comb-shaped electrodes 37 and 38 was set to 5μm, x2 was set to 15μm, x3 of the comb-shaped electrode 38 was set to 5μm, x4 was set to 15μm, and the distance x5 between the electrode branches of the comb-shaped electrodes 37 and 38 was set to 5μm. In addition, the layer thickness of the liquid crystal layer 41 was set to 4μm, and as the liquid crystal material, a material with negative dielectric constant anisotropy and refractive index anisotropy of 0.18 was used. A vertical alignment film was used for each alignment film 39 and 40, and a rubbing treatment was performed as an alignment treatment. The alignment treatment direction (rubbing direction) was set to a direction substantially perpendicular to the extension direction of each electrode branch of each comb-shaped electrode 37 and 38, and was set to an anti-parallel configuration. The refractive index anisotropy is not particularly limited, but is more preferably 0.15 or more as described above, and further preferably 0.2 or more.

[0067] Figure 7 (A)~ Figure 7 (C) is a diagram for explaining a method of driving a diffractive optical element. Figure 7 (A) represents a driving method in which a voltage is applied between the comb-tooth electrode 37 and the comb-tooth electrode 38. As the electric field distribution is simply represented by a thin line in the figure, an electric field is generated in the area between the comb-tooth electrode 37 and the comb-tooth electrode 38, and an orientation change of the liquid crystal layer 41 occurs in this area. There is almost no orientation change in the area overlapping with each comb-tooth electrode 37, 38. As a result, areas where orientation changes caused by the electric field occur and areas where no orientation changes occur are alternately generated, so that areas with different refractive index distributions can be obtained. In addition, when no voltage is applied, such a refractive index distribution does not occur, and the liquid crystal layer 41 is uniformly oriented.

[0068] Figure 7 (B) represents a driving method of applying a voltage between the comb-tooth electrode 37 and the comb-tooth electrode 38 and the common electrode 34 respectively. As the electric field distribution is simply represented by thin lines in the figure, an electric field is generated in each region between the comb-tooth electrode 37 and the common electrode 34 and between the comb-tooth electrode 38 and the common electrode 34, and an orientation change of the liquid crystal layer 41 occurs in this region. It is difficult to produce an orientation change in the region near the middle of the electrode branches of each comb-tooth electrode 37 and 38. As a result, regions where orientation changes caused by the electric field occur and regions where no orientation changes occur are alternately generated, so that regions with different refractive index distributions can be obtained. As described above Figure 7Compared with the driving method shown in (A), regions with different refractive index distribution can be obtained at shorter intervals. In addition, when no voltage is applied, such a refractive index distribution does not occur, and the liquid crystal layer 41 is uniformly aligned.

[0069] Figure 7 (C) represents a driving method in which a voltage is applied between the comb-tooth electrode 37 and the comb-tooth electrode 38 and the opposing electrode 35. As the electric field distribution is simply represented by thin lines in the figure, an electric field is generated in each region between the comb-tooth electrode 37 and the opposing electrode 35 and between the comb-tooth electrode 38 and the common electrode 34, and an orientation change of the liquid crystal layer 41 occurs in this region. In this driving method, an electric field is generated in the thickness direction of the liquid crystal layer 41. An inclined electric field is generated in the region between each comb-tooth electrode 37, 38, so that an orientation state different from that of the region overlapping with each comb-tooth electrode 37, 38 can be obtained. Thus, a region with a different refractive index distribution can be obtained. In addition, when no voltage is applied, such a refractive index distribution is not generated, and the liquid crystal layer 41 is uniformly oriented.

[0070] When using only Figure 7 When the driving method shown in (A) is used, the common electrode 34 and the counter electrode 35 can be omitted from the diffractive optical element 13. Figure 7 When the driving method shown in (B) is used, the counter electrode 35 can be omitted from the diffractive optical element 13. Figure 7 In the driving method shown in (C), the common electrode 34 can be omitted from the diffractive optical element 13. Figure 7 (B) Figure 7 In the driving method shown in (C), since the comb-shaped electrodes 37 and 38 are given the same potential, they can also be electrically connected. Figure 3 (B)) The wiring portions 42 and 43 may be formed in such a way that they are physically connected at appropriate positions such as ends.

[0071] Figure 8 (A)~ Figure 8 (C) is a diagram showing an example of measuring light passing through a diffractive optical element. Figure 6 The optical system shown in the figure makes light incident on the diffractive optical element 13 in the left and right directions ( Figure 6 In each driving method, a voltage of 150 Hz and 10 V is applied to the comb-shaped electrodes 37 and 38 of the diffractive optical element 13, and a reference voltage (GND voltage) is applied to the common electrode 34 and the counter electrode 35.

[0072] Figure 8(A) is an example of measuring light when the diffractive optical element 13 is driven by a driving method of applying a voltage between the comb-shaped electrode 37 and the comb-shaped electrode 38. As shown in the figure, the width of the light 94 on the screen 93 in the state where no voltage is applied to the diffractive optical element 13 (OFF) is 12 degrees, while the width of the light 94 on the screen 93 in the state where a voltage is applied between the comb-shaped electrode 37 and the comb-shaped electrode 38 of the diffractive optical element 13 (ON) is expanded to 22 degrees.

[0073] Figure 8 (B) is an example of measuring light when the diffractive optical element 13 is driven by a driving method in which a voltage is applied between the comb-shaped electrodes 37 and the comb-shaped electrodes 38 and the common electrode 34. As shown in the figure, the width of the light 94 on the screen 93 in the state where no voltage is applied to the diffractive optical element 13 (OFF) is 12 degrees, while the width of the light 94 on the screen 93 in the state where a voltage is applied between the comb-shaped electrodes 37 and the comb-shaped electrodes 38 and the common electrode 34 of the diffractive optical element 13 (ON) is spread to 24 degrees.

[0074] Figure 8 (C) is an example of measuring light when the diffractive optical element 13 is driven by a driving method in which a voltage is applied between the comb-shaped electrodes 37 and the comb-shaped electrodes 38 and the counter electrode 35. As shown in the figure, the width of the light 94 on the screen 93 in the state where no voltage is applied to the diffractive optical element 13 (OFF) is 12 degrees, while the width of the light 94 on the screen 93 in the state where a voltage is applied between the comb-shaped electrodes 37 and the comb-shaped electrodes 38 and the counter electrode 35 of the diffractive optical element 13 (ON) is spread to 18 degrees.

[0075] Therefore, it can be seen that in the driving method using the voltage applied between the comb-shaped electrodes 37 and 38 of the diffractive optical element 13 and the common electrode 34 (see Figure 7 In the case of (B), the width of the light 94 is maximized. On the other hand, it is known that in the driving method using a voltage applied between the comb-shaped electrodes 37 and 38 of the diffractive optical element 13 and the counter electrode 35 (see Figure 7 In the case of (C)), the change in the width of light 94 is minimal.

[0076] In order to confirm the diffraction effect, Figure 6 When the light source 90 in the optical system is replaced with a laser light source and the diffraction optical element 13 is driven by a driving method in which a voltage is applied between the comb-tooth electrode 37 and the comb-tooth electrode 38 and the common electrode 34, a diffraction spot of more than one light is obtained on the screen 93, and it can be confirmed that a diffraction effect has occurred.

[0077] Next, a method of assembling the diffractive optical element 13 produced under the same conditions as those used in the above evaluation into the above Figure 1 Observation example of projection light emitted from the projection lens 18 when the vehicle lighting system shown in FIG. 1 is operated. Here, a driving voltage is applied to the liquid crystal element 15 so that the entire surface becomes a light-transmitting state. Fig. 9 As shown in the schematic diagram of the middle cone, the light emitted from the light source 11 and converged by the reflector 12 and incident on the diffractive optical element 13 is incident at a wide angle with a maximum convergence angle of ±40° to 50°, and the light is incident from a substantially normal direction near the light modulation area 30b arranged in the center of the diffractive optical element 13. The diffractive optical element 13 is arranged in a manner such that the arrangement direction of each light modulation area 30a to 30c is consistent with the left-right direction of the vehicle lamp system.

[0078] Fig.10 (A)~ Fig.10 (C) is a diagram showing an example of measuring the light intensity distribution of the projection light. In this example, a screen is arranged 10 m in front of the projection lens 18 to measure the light intensity distribution. Fig.10 (A)~ Fig.10 In each measurement example of (C), a substantially elliptical light intensity distribution extending to the left and right is shown, and the area with higher brightness is closer to the center of the elliptical distribution.

[0079] Fig.10 (A) shows the light intensity distribution when no driving voltage is applied to the diffractive optical element 13. In this case, the light intensity distribution is the same as that when the diffractive optical element 13 is not provided, and becomes a substantially bilaterally symmetrical light intensity distribution.

[0080] Fig.10 (B) shows the light intensity distribution when a driving voltage is applied to the light modulation area 30a on the left side of the diffractive optical element 13, and no driving voltage is applied to the other light modulation areas 30b and 30c. Fig.10 Comparison of the light intensity distribution of (A) shows that the projection light moves to the right by about 3° in the figure. In addition, the transmitted light is reversed vertically and horizontally by the projection lens 18, so the position of the light modulation area 30a is opposite to the moving direction of the projection light.

[0081] Fig.10 (C) shows the light intensity distribution when a driving voltage is applied to each light modulation region 30a to 30c in the diffractive optical element 13. In this case, Fig.10 Comparison of the light intensity distribution in (A) shows that the projection light diffuses to the left and right in the figure.

[0082] Furthermore, by ensuring a larger interval between the diffractive optical element 13 and the liquid crystal element 15 , the degree of movement and diffusion of light can be further increased.

[0083] Next, the light distribution control of the diffractive optical element 13 will be described in further detail. Fig.11 As shown in (A), parallel light 100 is incident on the diffractive optical element 13 from the normal direction of the incident surface (projection angle = 0°), and the transmittance when the voltage applied between each comb-shaped electrode 37, 38 and the common electrode 34 of the diffractive optical element 13 is set between 0V and 30V is measured by the light receiving element 101. Fig.11 As shown in (B), parallel light 100 with a projection angle greater than 0° based on the normal direction of the incident surface is incident on the diffractive optical element 13, and the transmittance when the voltage applied between each comb-shaped electrode 37, 38 and the common electrode 34 of the diffractive optical element 13 is set between 0V and 30V is measured by the light receiving element 101. The light receiving element 101 variably sets the light receiving angle θ based on the normal direction of the diffractive optical element 13 to a positive direction and a negative direction.

[0084] Fig.12 (A) is a graph showing the relationship between the receiving angle and the transmittance when the projection angle of the incident parallel light is set to 0°. The case where the voltage applied to the diffractive optical element 13 is 10V and the case where it is 20V show substantially the same characteristics, so the characteristic lines substantially overlap. As shown in the figure, it can be seen that the transmittance of light traveling straight in the direction of the receiving angle = 0° is about 85% when the applied voltage is 0V, and is reduced to about 30% by increasing the applied voltage, and accordingly diffuses in the left and right directions (directions with larger absolute values ​​of the receiving angle).

[0085] Fig.12 (B) is a graph showing the relationship between the receiving angle and the transmittance when the incident parallel light has a projection angle of +30°. A positive projection angle means that the parallel light is incident from the above Fig.11 The state of incident light in the direction shown in (B). It can be seen that the transmittance of light traveling straight in the direction of the light receiving angle = -30° is about 80% when the applied voltage is 0V, and it decreases to about 30% by increasing the applied voltage, and accordingly mainly diffuses to the left direction (the direction of the light receiving angle is positive).

[0086] Fig.12 (C) is a graph showing the relationship between the receiving angle and the transmittance when the incident parallel light has a projection angle of +60°. A positive projection angle means that the parallel light is incident from the above Fig.11It is known that the transmittance of light traveling straight in the direction of the light receiving angle = -60° is about 60% when the applied voltage is 0V, and it decreases to below 30% by increasing the applied voltage, and accordingly mainly diffuses to the left direction (the direction where the light receiving angle is positive).

[0087] Fig.13 (A)~ Fig.13 (C) is a diagram schematically showing the situation of light incident on the liquid crystal element due to the diffraction effect of the diffractive optical element. In each figure, for convenience, the light that converges on the position of the liquid crystal element 15 (in the figure, the light traveling from bottom to top) is divided into three lights L1, L2, and L3, which are represented by dotted lines respectively. Light L1 is mainly light incident on each light modulation area 30a of the diffractive optical element 13, light L2 is mainly light incident on each light modulation area 30b of the diffractive optical element 13, and light L3 is mainly light incident on each light modulation area 30c of the diffractive optical element 13.

[0088] When no voltage is applied to any of the light modulation regions 30a to 30c of the diffractive optical element 13, Fig.13 As shown in (A), the lights L1 to L3 emitted from the light source 11 and focused by the reflector 12 directly pass through the diffractive optical element 13 and enter the liquid crystal element 15 , forming a focus at the position of the liquid crystal element 15 .

[0089] In addition, when a voltage is applied only to the light modulation region 30a of the diffractive optical element 13, as shown in FIG. Fig.13 As shown in (B), the light L1 incident on the light modulation area 30a is diffused and bent and incident on the liquid crystal element 15. The other lights L2 and L3 directly enter the liquid crystal element 15. Therefore, the projection light projected by the projection lens 18 through the liquid crystal element 15 is diffusely irradiated to the left side in the figure.

[0090] Although not shown in the figure, the same is true when a voltage is applied only to the light modulation region 30c of the diffractive optical element 13. In this case, the light L3 incident on the light modulation region 30c is diffused and bent and is incident on the liquid crystal element 15. The other lights L1 and L2 are directly incident on the liquid crystal element 15. Therefore, the projection light that is projected by the projection lens 18 after passing through the liquid crystal element 15 is diffusely irradiated to the right side in the figure.

[0091] In addition, when a voltage is applied to all of the light modulation regions 30a to 30c of the diffractive optical element 13, as shown in FIG. Fig.13 As shown in (C), the lights L1 to L3 emitted from the light source 11 and focused by the reflector 12 are diffused to the left and right and enter the liquid crystal element 15. Therefore, the projection light transmitted through the liquid crystal element 15 and projected by the projection lens 18 is diffused to the left and right in the figure.

[0092] In this way, the diffusion degree of the projection light can be controlled by using each light modulation area 30a to 30c. Therefore, when the vehicle travels at a relatively high speed, such as when traveling on a highway, the projection light is not diffused but concentrated in the front direction of the vehicle. On the other hand, when the vehicle travels at a relatively low speed, such as when traveling in an urban area, the projection light is diffused to the left and right, etc., so that the light distribution state corresponding to the driving condition can be realized and the visibility in front of the vehicle can be improved. In addition, by selectively using the diffraction effect of any one of the light modulation areas 30a and 30c, for example, the light irradiated to the left front or right front of the vehicle can be increased according to the traveling direction of the vehicle, so that the visibility in the traveling direction of the vehicle can be improved.

[0093] Fig.14 (A) is a diagram showing an example of the illuminance distribution of the projection light when no voltage is applied to the diffractive optical element. When the diffraction effect of the diffractive optical element 13 is not used, as shown in the figure, the illuminance distribution becomes approximately symmetrical around the reference position 0° of the left-right angle.

[0094] Fig.14 (B) is a diagram showing the result of calculating the illumination distribution of the projection light when a voltage is applied to all the light modulation areas of the diffractive optical element. The calculation is performed assuming that the distance between the diffractive optical element 13 and the liquid crystal element 15 is 8 mm. This distance between them is equivalent to the case where the incident angle of the light incident on the central part of the liquid crystal element 15 through the light modulation area 30a of the diffractive optical element 13 is 45°. As shown in the figure, it can be seen that by applying a voltage to all the light modulation areas 30a to 30c, the high illumination band spreads to the left and right. At this time, the intensity of the light irradiated to the central part of the liquid crystal element 15 is reduced to about 2 / 3, and accordingly spreads to the left and right to about ±5°.

[0095] Fig.14 (C) is a diagram showing the result of calculating the illumination distribution of the projection light when a voltage is applied to the light modulation area 30a, which is a light modulation area of ​​the diffractive optical element. In addition, the calculation is performed assuming that the distance between the diffractive optical element 13 and the liquid crystal element 15 is 8 mm. In this case, it can be seen that the high illumination band moves to about +5°. In addition, by setting the distance between the diffractive optical element 13 and the liquid crystal element 15 to be larger, the angle of movement of the high illumination band can be further increased. For example, when the distance between them is set to 20 mm, the high illumination band is expected to move to about +12.5°. This value can meet the deflection angle required in the AFS (Adaptive Front-Lighting System) technology that variably controls the light irradiation direction according to the direction of travel of the vehicle.

[0096] According to the above-described embodiments, it is possible to realize diversification of the light distribution control of irradiated light in a lighting device such as a vehicle lamp and a system using the lighting device.

[0097] In addition, the present invention is not limited to the contents of the above-mentioned embodiments, and can be implemented by various deformations within the scope of the main purpose of the present invention. For example, the number of light modulation areas possessed by the diffractive optical element 13 is not limited to the 3 illustrated. In the above-mentioned embodiments, each light modulation area is arranged in one direction, but it can also be arranged in two directions. In addition, in the above-mentioned embodiments, the diffractive optical element 13 is arranged between the light source 10 and the polarizing plate 14, but the diffractive optical element 13 can also be arranged between the polarizing plate 14 and the liquid crystal element 15. In addition, the former configuration can ensure that the distance between the diffractive optical element 13 and the liquid crystal element 15 is relatively large, so it is more preferred.

[0098] In addition, in the above-mentioned embodiment, a four-wheel vehicle is used as an example for explanation, but the technical concept of the present invention can also be applied to the headlights of various vehicles other than four-wheel vehicles. In addition, in the above-mentioned embodiment, a vehicle lamp is illustrated as an example of a lighting device, but it is not limited to this. For example, the content of the present invention can be applied to a lighting device for depicting various images such as road surfaces, street lights, crossing signals, and direction guides. In addition, in the case of a vehicle lamp, it is preferred that Fig.10 As shown in the example, the projection light diffuses to the left and right, and the bright area diffused in the horizontal direction moves to the left and right while maintaining the bright state. Therefore, the comb-tooth electrode used in the diffractive optical element adopts a straight slit shape. In the case of assuming other uses (illumination devices, etc.), a comb-tooth electrode with a slit direction changed relative to the direction of the light incident on the diffractive optical element can also be used. For example, when light comes from Fig. 9 When incident in the direction shown, the electrodes of the light modulation area 30b can be horizontal slit electrodes, and the electrodes of the light modulation area 30a can also be "く"-shaped slit electrodes. Furthermore, various comb-tooth electrode structures such as U-shaped, concentric circles, and elliptical shapes can also be used.

[0099] The present invention has the following additional features.

[0100] (Note 1)

[0101] A lighting device, comprising:

[0102] light source;

[0103] a converging portion for converging the light emitted from the light source;

[0104] a liquid crystal element disposed at a focal position of the light converged by the converging portion;

[0105] a projection lens disposed at a position where the light transmitted through the liquid crystal element can be incident;

[0106] A first polarizer, disposed between the light source and the liquid crystal element;

[0107] A second polarizing plate disposed between the liquid crystal element and the projection lens; and

[0108] a diffractive optical element disposed between the light source and the liquid crystal element,

[0109] The diffractive optical element has a plurality of light modulation regions, each of which can be electrically switched between a first state and a second state, wherein the first state is a state in which the refractive index changes periodically or continuously, and the second state is a state in which the refractive index is substantially the same.

[0110] The first state can cause the incident light to produce a diffraction effect,

[0111] The plurality of light modulation regions are respectively arranged at positions where the light can be incident and closer to the light source than the focal position.

[0112] (Note 2)

[0113] The lighting device according to Supplement 1, wherein:

[0114] The diffractive optical element is arranged between the light source and the first polarizer.

[0115] (Note 3)

[0116] The lighting device according to Supplement 1, wherein:

[0117] The diffractive optical element is arranged between the first polarizing plate and the liquid crystal element.

[0118] (Note 4)

[0119] The lighting device according to any one of Supplementary Notes 1 to 3, wherein:

[0120] The plurality of light modulation regions of the diffractive optical element respectively include:

[0121] a liquid crystal layer disposed between a first substrate and a second substrate that are arranged opposite to each other; and

[0122] The comb-teeth-shaped electrode is provided on the first substrate so as to overlap with the liquid crystal layer in a plan view.

[0123] (Note 5)

[0124] The lighting device according to Supplement 4, wherein:

[0125] The plurality of light modulation regions of the diffractive optical element respectively include:

[0126] a common electrode provided on a side of the first substrate facing the liquid crystal layer and closer to the surface than the comb-teeth-shaped electrode, and arranged to overlap with the comb-teeth-shaped electrode in a plan view; and

[0127] An insulating film is disposed between the comb-shaped electrode and the common electrode.

[0128] (Note 6)

[0129] The lighting device according to Supplement 5, wherein:

[0130] Each of the plurality of light modulation regions of the diffractive optical element includes a counter electrode provided on a surface of the second substrate facing the liquid crystal layer and arranged to overlap with the comb-shaped electrode in a plan view.

[0131] (Note 7)

[0132] The lighting device according to any one of Supplementary Notes 4 to 6, wherein:

[0133] The comb-shaped electrode has a plurality of electrode branches.

[0134] The width of each of the plurality of electrode branches is 5 μm or less, and the distance between adjacent electrode branches is 5 μm or less.

[0135] (Note 8)

[0136] A vehicle lighting system, comprising:

[0137] A vehicle lamp, comprising the lighting device according to any one of appendices 1 to 7; and

[0138] A controller is connected to the vehicle lamp and controls the operation of the liquid crystal element of the vehicle lamp according to the conditions around the vehicle and controls the operation of the diffractive optical element.

[0139] Description of Reference Numerals

[0140] 1: vehicle lamp (lighting device), 2: controller, 3: camera, 11: light source, 12: reflector (reflecting component), 13: diffraction optical element, 14: polarizer, 15: liquid crystal element, 16: optical compensation plate, 17: polarizer, 18: projection lens, 30a, 30b, 30c: light modulation area, 32: first substrate, 33: second substrate, 34: common electrode, 35: opposing electrode, 36: insulating film, 37, 38: comb-shaped electrodes, 39, 40: orientation film, 41: liquid crystal layer.

Claims

1. A lighting device, comprising: light source; a converging portion for converging the light emitted from the light source; a liquid crystal element disposed at a focal position of the light converged by the converging portion; a projection lens disposed at a position where the light transmitted through the liquid crystal element can be incident; A first polarizer, disposed between the light source and the liquid crystal element; A second polarizer, disposed between the liquid crystal element and the projection lens; as well as a diffractive optical element disposed between the light source and the liquid crystal element, The diffractive optical element has a plurality of light modulation regions, each of which can be electrically switched between a first state and a second state, wherein the first state is a state in which the refractive index changes periodically or continuously, and the second state is a state in which the refractive index is substantially the same. The first state can cause the incident light to produce a diffraction effect, The plurality of light modulation regions are respectively arranged at positions where the light can be incident and closer to the light source than the focal position.

2. The lighting device according to claim 1, wherein: The diffractive optical element is arranged between the light source and the first polarizer.

3. The lighting device according to claim 1, wherein: The diffractive optical element is arranged between the first polarizing plate and the liquid crystal element.

4. The lighting device according to claim 1, wherein: The plurality of light modulation regions of the diffractive optical element respectively include: a liquid crystal layer disposed between a first substrate and a second substrate that are arranged opposite to each other; and The comb-teeth-shaped electrode is provided on the first substrate so as to overlap with the liquid crystal layer in a plan view.

5. The lighting device according to claim 4, wherein: The plurality of light modulation regions of the diffractive optical element respectively include: a common electrode disposed on a side of the first substrate that is opposite to the liquid crystal layer and closer to the surface than the comb-teeth-shaped electrode, and arranged to overlap with the comb-teeth-shaped electrode in a plan view; as well as An insulating film is disposed between the comb-shaped electrode and the common electrode.

6. The lighting device according to claim 5, wherein: Each of the plurality of light modulation regions of the diffractive optical element includes a counter electrode provided on a surface of the second substrate facing the liquid crystal layer and arranged to overlap with the comb-shaped electrode in a plan view.

7. The lighting device according to claim 4, wherein: The comb-shaped electrode has a plurality of electrode branches, each of the plurality of electrode branches has a width of 5 μm or less, and a distance between adjacent electrode branches is 5 μm or less.

8. A vehicle lighting system, comprising: A vehicle lamp, which is formed using the lighting device according to claim 1; and A controller is connected to the vehicle lamp and controls the operation of the liquid crystal element of the vehicle lamp according to the conditions around the vehicle and controls the operation of the diffractive optical element.

Images