Lighting device, vehicle headlamp system

Abstract

To provide a technique capable of diversifying light distribution control of illumination light.SOLUTION: An illuminating device includes a light source, a light condensing part, a liquid crystal element arranged at a focal position of light condensed by the light condensing part, a projection lens arranged at a position on which the light passing through the liquid crystal element can be incident, a first polarization plate arranged between the light source and the liquid crystal element, a second polarization plate arranged between the liquid crystal element and the projection lens, and a diffractive optical element arranged between the light source and the liquid crystal element. The diffractive optical element comprises a plurality of light modulation regions each capable of electrically switching between a first state in which a refractive index is periodically or continuously changed, and a second state in which the refractive index is approximately uniform. In the first state, a diffraction effect on incident light can be generated. The plurality of light modulation regions is each arranged at a position on which the light can be incident, and closer to the light source than the focal position.SELECTED DRAWING: Figure 13

Description

[Technical Field]

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

[0002] Japanese Patent No. 5238124 (Patent Document 1) describes a lamp having a light source, a reflector, and a lens, and further comprising a liquid crystal optical element disposed between the light source and the lens to enable light distribution control over a wider range than the basic light distribution constituted by the light source, reflector, and lens. The liquid crystal optical element of this lamp is configured such that when no voltage is applied, it exhibits a transparent state due to the uniformity of the molecular arrangement and refractive index of the adjacent grating and non-grating sections, and when voltage is applied, the difference in refractive index between the grating and non-grating sections causes light guided within the liquid crystal layer to be refracted in a predetermined direction, becoming scattered light, and the direction of illumination toward the outside is widened. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Patent No. 5238124 Summary of the Invention [Problem to be solved by the invention]

[0004] One of the objects of a specific aspect of the present disclosure is to provide a technology that can realize diversification of light distribution control of irradiated light in a lighting device such as a vehicle lamp or a system that uses the same. [Means for solving the problem]

[0005] [1] An illumination device according to one aspect of the present disclosure includes: (a) a light source; (b) a focusing unit that focuses the light emitted from the light source; (c) a liquid crystal element that is disposed at a focal position of the light focused by the focusing unit; (d) a projection lens that is disposed at a position where the light that passes through the liquid crystal element can be incident; (e) a first polarizing plate that is disposed between the light source and the liquid crystal element; (f) a second polarizing plate that is disposed between the liquid crystal element and the projection lens; and (g) a diffractive optical element that is disposed between the light source and the liquid crystal element, wherein (h) the diffractive optical element has a plurality of light modulation regions that can be electrically switched between a first state in which a refractive index changes periodically or continuously and a second state in which the refractive index is substantially uniform, and (i) the first state can produce a diffraction effect on incident light, and (j) each of the plurality of light modulation regions is disposed at a position where the light can be incident and that is closer to the light source than the focal position.

[0006] [2] One aspect of the vehicle lighting system according to the present disclosure is a vehicle lighting system including: (a) a vehicle lighting device configured using the lighting device of [1]; and (b) a controller connected to the vehicle lighting device, which controls the operation of the liquid crystal element of the vehicle lighting device and the operation of the diffractive optical element in accordance with the conditions around the vehicle.

[0007] According to the above configuration, it is possible to realize diversification of light distribution control of irradiated light in a lighting device such as a vehicle lamp or a system using the same. [Brief explanation of the drawings]

[0008] [Figure 1] FIG. 1 is a diagram showing the configuration of a vehicle lighting system according to an embodiment. [Figure 2] FIG. 2 is a schematic plan view illustrating an example of the structure of a diffractive optical element. [Figure 3] Fig. 3(A) is a cross-sectional view schematically showing a partial cross-sectional structure of a diffractive optical element taken along line aa shown in Fig. 2. Fig. 3(B) is a schematic plan view for explaining an example of the structure of comb-shaped electrodes of the diffractive optical element. [Figure 4] FIG. 4 is a schematic cross-sectional view illustrating an example of the structure of a liquid crystal element. [Figure 5] FIG. 5 is a schematic plan view for explaining a more specific example of the liquid crystal element. [Figure 6] FIG. 6 is a diagram for explaining the configuration of an optical system used to examine the driving conditions of a diffractive optical element. [Figure 7] 7(A) to 7(C) are diagrams for explaining a method of driving a diffractive optical element. [Figure 8] 8(A) to 8(C) are diagrams showing an example of measurement of light transmitted through a diffractive optical element. [Figure 9] FIG. 9 is a diagram showing a cone-shaped schematic diagram of light emitted from a light source, collected by a reflector, and incident on a diffractive optical element. [Figure 10] 10(A) to 10(C) are diagrams showing examples of measurements of the light intensity distribution of the projection light. [Figure 11] 11(A) and 11(B) are diagrams for explaining the measurement system used to measure the transmittance of the diffractive optical element. [Figure 12] Fig. 12(A) is a graph showing the relationship between the light receiving angle and transmittance when the projection angle of the incident parallel light is 0°. Fig. 12(B) is a graph showing the relationship between the light receiving angle and transmittance when the projection angle of the incident parallel light is +30°. Fig. 12(C) is a graph showing the relationship between the light receiving angle and transmittance when the projection angle of the incident parallel light is +60°. [Figure 13] 13(A) to 13(C) are diagrams that schematically show how light is subjected to the diffraction effect of the diffractive optical element and then enters a liquid crystal element. [Figure 14] Fig. 14(A) is a diagram showing an example of the illuminance distribution of projected light when no voltage is applied to the diffractive optical element. Fig. 14(B) is a diagram showing the results of calculations of the illuminance distribution of projected light when voltage is applied to all light modulation regions of the diffractive optical element. Fig. 14(C) is a diagram showing the results of calculations of the illuminance distribution of projected light when voltage is applied to one light modulation region of the diffractive optical element. DETAILED DESCRIPTION OF THE INVENTION

[0009] Fig. 1 is a diagram showing the configuration of a vehicle lighting system according to one embodiment. The vehicle lighting system shown in Fig. 1 includes a vehicle lighting device (illumination device) 1, a controller 2, and a camera 3. This vehicle lighting system detects the positions of vehicles ahead, pedestrians' faces, and the like around the vehicle (i.e., the situation around the vehicle) based on an image of the vehicle's surroundings captured by the camera 3, and, based on the detection results, sets a certain range including the position of the vehicle ahead, etc., as a dimming range (or non-illumination range), and sets the other range as a light illumination range, thereby selectively illuminating light and illuminating the road surface with various patterns of light.

[0010] The vehicle lamp 1 is disposed at a predetermined position, for example, at the front of the vehicle, and emits light to illuminate the area ahead of the vehicle. Note that one vehicle lamp 1 is provided on each side of the vehicle, but only one is shown here.

[0011] 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 realized by using a computer system having, for example, a CPU (Central Processing Unit), a ROM (Read Only Memory), a RAM (Random Access Memory), etc., and by running a predetermined operating program on the computer system. The controller 2 of this embodiment turns on the light source 11 in accordance with the operating state of a light switch (not shown) installed at the driver's seat, sets a light distribution pattern in accordance with objects detected by the camera 3, such as a forward vehicle (an oncoming vehicle or a preceding vehicle), a pedestrian, a road sign, or a white line on the road, and supplies a control signal to the liquid crystal element 15 to form an image corresponding to this light distribution pattern.

[0012] The camera 3 takes an image of the space ahead of the vehicle to generate an image, and performs a predetermined image recognition process on this image to detect the position, range, size, type, etc. of the target object, such as the vehicle ahead. The detection results from the image recognition process are supplied to the controller 2 connected to the camera 3. The camera 3 is installed in a predetermined position inside the vehicle's cabin (for example, above the windshield) or in a predetermined position outside the vehicle's cabin (for example, inside the front bumper). If the vehicle is equipped with a camera for another purpose (for example, an automatic braking system, etc.), that camera may be used in common.

[0013] The image recognition processing function of the camera 3 may be performed by the controller 2. In this case, the camera 3 outputs the generated image to the controller 2, and the controller 2 performs image recognition processing based on this 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.

[0014] 1 includes a light source 11, a reflector (reflective member) 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 into a single housing, for example. The light source 11, the diffractive optical element 13, and the liquid crystal element 15 are each connected to a controller 2, and are controlled by the controller 2.

[0015] Light source 11 includes a drive circuit and emits light under the control of controller 2. As an example, light source 11 is a white LED equipped with a blue LED and a yellow phosphor placed at a position where the light emitted from the blue LED is incident, and the blue LED excites the yellow phosphor, resulting in white light being obtained by mixing the blue and yellow colors.

[0016] The reflector 12 is disposed in correspondence with the light source 11, and reflects and collects the light emitted from the light source 11 so that the light is focused at the position of the liquid crystal element 15 (for example, approximately at the center in the thickness direction of the liquid crystal element 15), and then makes the light incident on the liquid crystal element 15. The reflector 12 is, for example, a reflecting mirror having an ellipsoidal reflecting surface. In this case, the light source 11 can be disposed near the focal point of the reflecting surface of the reflector 12. Note that a lens may be used as a light collecting unit instead of the reflector 12.

[0017] The diffractive optical element 13 operates under the control of the controller 2, and widens or narrows the width of incident light or changes the traveling direction of the incident light by utilizing the diffraction effect (diffraction phenomenon) of light. The detailed structure of the diffractive optical element 13 will be described later.

[0018] Polarizing plate 14 is disposed on the light incident surface side of liquid crystal element 15. Polarizing plate 17 is disposed on the light exit surface side of liquid crystal element 15. These polarizing plates 14 and 17, and the liquid crystal element 15 disposed therebetween, form an image corresponding to the light distribution pattern of light irradiated ahead of the vehicle. As an example, the polarizing plates 14 and 17 are disposed so that their transmission axes are approximately perpendicular to each other. Furthermore, the polarizing plates 14 and 17 are disposed so that their transmission axes form an angle of approximately 45° in a plan view with respect to the alignment direction at approximately the center of the liquid crystal layer of liquid crystal element 15 in the layer thickness direction when no voltage is applied.

[0019] The liquid crystal element 15 is disposed at a position including the focal point of the light reflected and condensed by the reflector 12, and is disposed so that the light is incident thereon. The liquid crystal element 15 includes a plurality of pixel units (light modulation units) that can be controlled independently of each other. In this embodiment, the liquid crystal element 15 has a driver (not shown) for applying a drive voltage to each pixel unit. The driver applies a drive voltage to the liquid crystal element 15 to individually drive each pixel unit based on a control signal supplied from the controller 2. As the rough trajectory (optical path) of light emitted from the light source 11 is shown by a thin line in the figure, the light incident on the liquid crystal element 15 is incident at a wide angle with respect 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° with respect to the normal direction of the light incident surface.

[0020] Optical compensator 16 compensates for the phase difference of light transmitted through liquid crystal element 15 and increases the degree of polarization, and is disposed on the light exit surface side of liquid crystal element 15. Specifically, the phase difference of optical compensator 16 is set so that the phase difference combined with the phase difference of liquid crystal layer 15 is 0 or a value close to 0. Note that optical compensator 16 may be omitted.

[0021] The projection lens 18 is disposed at a position where the light reflected and condensed by the reflector 12 and transmitted through the liquid crystal element 15 can enter the projection lens 18, which projects the incident light forward of the vehicle. The projection lens 18 is disposed so that its focal point is formed on the liquid crystal layer of the liquid crystal element 15.

[0022] FIG. 2 is a schematic plan view illustrating an example of the structure of a diffractive optical element. The illustrated diffractive optical element 13 includes three light modulation regions 30a, 30b, and 30c arranged along the X direction in the figure, four terminal portions 31a for applying a drive voltage to the light modulation region 30a, four terminal portions 31b for applying a drive voltage to the light modulation region 30b, and four terminal portions 31c for applying a drive voltage to the light modulation region 30c. The light modulation regions 30a, 30b, and 30c are arranged, for example, along the left-right direction (horizontal direction) of the vehicle. Note that, in the figure, gaps are drawn between the light modulation regions 30a, etc. to make it easy to distinguish between the light modulation regions 30a, 30b, and 30c, but in reality, the light modulation regions 30a, etc. may be arranged without these gaps.

[0023] The light modulation region 30a operates in response to a drive voltage input via each terminal 31a, and bends the direction of incident light or widens the width of the incident light primarily through a diffraction effect. Similarly, the light modulation region 30b operates in response to a drive voltage input via each terminal 31b, and bends the direction of incident light or widens the width of the incident light primarily through a diffraction effect. Similarly, the light modulation region 30c operates in response to a drive voltage input via each terminal 31c, and bends the direction of incident light or widens the width of the incident light primarily through a diffraction effect. Note that any of the light modulation regions 30a, etc. may also produce refraction in addition to diffraction.

[0024] Fig. 3(A) is a cross-sectional view schematically showing the cross-sectional structure of a portion of the diffractive optical element taken along line aa in Fig. 2. Note that while the cross-sectional structure of a portion of light modulation region 30a is described here, the cross-sectional structures of the other light modulation regions 30b and 30c are similar. Light modulation region 30a in diffractive optical element 13 of this embodiment is configured to include a first substrate 32 and a second substrate 33 arranged opposite each other, a common electrode 34, a counter electrode 35, an insulating film 36, comb-shaped electrodes 37 and 38, alignment films 39 and 40, and a liquid crystal layer 41.

[0025] The first substrate 32 and the second substrate 33 are each, for example, rectangular substrates in a plan view, and are arranged opposite each other. The first substrate 32 and the second substrate 33 are each, for example, transparent substrates such as glass substrates or plastic substrates. Spherical spacers (not shown) made of, for example, resin are dispersed and arranged between the first substrate 32 and the second substrate 33, and these spherical spacers maintain the gap between the substrates at a desired size (for example, about several μm). Note that instead of the spherical spacers, pillars made of, for example, resin may be provided on the first substrate 32 side or the second substrate 33 side and used as spacers.

[0026] The common electrode 34 is provided on one surface of the first substrate 32 closer to the first surface than the comb-shaped electrodes 37, 38, and is arranged so as to overlap the comb-shaped electrodes 37, 38 in a planar view. The counter electrode 35 is provided on one surface of the second substrate 33, and is arranged so as to overlap the comb-shaped electrodes 37, 38 in a planar view. The common electrode 34 and the counter electrode 35 are formed by appropriately patterning a transparent conductive film made of, for example, indium tin oxide (ITO). The common electrode 34 and the counter electrode 35 are each provided in an area that approximately coincides with the outer edge of the light modulation region 30a in a planar view.

[0027] The common electrode 34 and the counter electrode 35 are each connected to one of the terminals 31a, and the voltage applied to each can be controlled independently. Each terminal 31a is provided, for example, on the first substrate 32. In this case, the counter electrode 35 and the corresponding terminal 31a are electrically connected to each other via an anisotropic conductive film (not shown) provided at an appropriate position between the first substrate 32 and the second substrate 33.

[0028] The insulating film 36 is provided on one surface of the first substrate 32 between the common electrode 34 and each of the comb-like electrodes 37, 38 so as to cover the common electrode 34. The insulating film 36 is a film for achieving electrical insulation between the common electrode 34 and each of the comb-like electrodes 37, 38. The insulating film 36 may be, for example, a siloxane-based insulating film, an acrylic-based organic insulating film, or an inorganic insulating film such as a SiNx film or an SiOx film. The insulating film 36 is patterned so as not to cover the terminal portions 31a but to expose them.

[0029] The comb-shaped electrodes 37, 38 are provided on one surface of the first substrate 32, above the insulating film 36 (the surface facing the second substrate 33). The comb-shaped electrodes 37, 38 are formed by appropriately patterning a transparent conductive film made of, for example, indium tin oxide (ITO). The comb-shaped electrodes 37, 38 are arranged so as to overlap the liquid crystal layer 41 in a plan view.

[0030] The alignment film 39 is disposed on one surface of the first substrate 32, covering the comb-shaped electrodes 37 and 38. The alignment film 40 is disposed on one surface of the second substrate 33, covering the counter electrode 35. These alignment films 39 and 40 regulate the alignment state of the liquid crystal layer 41. Each alignment film 39 and 40 has been subjected to a uniaxial alignment treatment, such as rubbing, and has a uniaxial alignment regulating force that determines the alignment of the liquid crystal molecules in the liquid crystal layer 41 along that direction. The alignment treatment on each alignment film 39 and 40 is set, for example, to be anti-parallel. Each alignment film 39 and 40 may be, for example, a horizontal alignment film or a vertical alignment film. For example, a polyimide alignment film or a siloxane-based alignment film may be used.

[0031] The liquid crystal layer 41 is provided between the first substrate 32 and the second substrate 33. The liquid crystal layer 41 is made of, for example, a nematic liquid crystal material having fluidity. The liquid crystal layer 41 may be made of a liquid crystal material having negative dielectric anisotropy, or may be made of a liquid crystal material having positive dielectric anisotropy. The thickness of the liquid crystal layer 41 may be, for example, about 4 μm.

[0032] FIG. 3B is a schematic plan view illustrating an example of the structure of the comb-shaped electrodes of the diffractive optical element. As shown in the figure, each of the comb-shaped electrodes 37 and 38 includes a plurality of electrode branches extending along the Y direction in the figure, and the electrode branches are alternately arranged one by one along the X direction in the figure. The X and Y directions in FIG. 3B coincide with the X and Y directions in FIG. 2. The X direction substantially coincides with the left-right direction (horizontal direction) of the vehicle, and the Y direction substantially coincides with the up-down direction (vertical direction) of the vehicle. The X and Y directions are each substantially perpendicular to the thickness direction of the liquid crystal layer 41 of the diffractive optical element 13. The comb-shaped electrode 37 is connected to a wiring portion 42 and is connected to one of the terminal portions 31a described above via the wiring portion 42. The comb-shaped electrode 38 is connected to a wiring portion 43 and is connected to one of the terminal portions 31a described above via the wiring portion 42.

[0033] The X-direction length (x1) of each electrode branch of the comb-shaped electrode 37 is, for example, 5 μm or less, and the distance (x2) between adjacent electrode branches is, for example, 15 μm or less. Similarly, the X-direction length (x3) of each electrode branch of the comb-shaped electrode 38 is, for example, 5 μm or less, and the distance (x4) between adjacent electrode branches is, for example, 15 μm or less. Furthermore, the distance (x5) between one electrode branch of the comb-shaped electrode 37 and one electrode branch of the adjacent comb-shaped electrode 38 is, for example, 5 μm or less. In order to generate a diffraction effect in the diffractive optical element 13, it is particularly preferable that the X-direction length (x1) of each electrode branch be 5 μm or less, and that the distance (x5) between one electrode branch of the comb-shaped electrode 37 and one electrode branch of the adjacent comb-shaped electrode 38 be 5 μm or less.

[0034] To produce a more pronounced diffraction effect in the diffractive optical element 13, it is desirable to set the values ​​of the above-mentioned x1, x2, x3, x4, and x5 as small as possible. This makes it possible to produce a state in which the refractive index in the liquid crystal layer 41 changes periodically at a length equal to or shorter than the wavelength of visible light when a voltage is applied to the liquid crystal layer 41 using the comb-shaped electrodes 37 and 38, the common electrode 34, and the counter electrode 35. By irradiating light to the diffractive optical element 13 in this state, it becomes possible to produce a diffraction effect independently in each of the above-mentioned light modulation regions 30a, 30b, and 30c, making it possible to bend the traveling direction of the light or widen the light as a whole.

[0035] Here, the relationship between the positive / negative dielectric anisotropy of the liquid crystal layer 41, the type of alignment film (vertical / horizontal), the alignment treatment direction of the alignment film, and the extension direction of each electrode branch of the comb-shaped electrodes 37 and 38 will be described. First, when a vertical alignment film is used as the alignment film, there is no particular limitation on the alignment treatment direction relative to the extension direction of each electrode branch (Y direction in the illustrated example). Furthermore, the dielectric anisotropy of the liquid crystal layer 41 may be either positive or negative. In a liquid crystal element for normal display purposes, etc., it is difficult to cause an alignment change in the liquid crystal layer 41 when a liquid crystal material with positive dielectric anisotropy is used under these conditions. However, it has been confirmed that this is possible in the diffractive optical element 13 using the comb-shaped electrodes 37 and 38 as in this embodiment.

[0036] Next, when a horizontal alignment film is used as the alignment film and the liquid crystal layer 41 has a positive dielectric anisotropy, it is desirable that the alignment treatment direction is not orthogonal to the extension direction of each electrode branch (the Y direction in the illustrated example), and is preferably, for example, parallel to the extension direction or at a 45° angle to the extension direction. Furthermore, when a horizontal alignment film is used as the alignment film and the liquid crystal layer 41 has a negative dielectric anisotropy, it is desirable that the alignment treatment direction is not parallel to the extension direction of each electrode branch (the Y direction in the illustrated example), and is preferably, for example, orthogonal to the extension direction or at a 45° angle to the extension direction.

[0037] 4 is a schematic cross-sectional view illustrating an example of the structure of a liquid crystal element. A segment display type liquid crystal element is shown here. Specifically, the illustrated liquid crystal element 15 includes a first substrate 51 and a second substrate 52 arranged opposite each other, a plurality of pixel electrodes 53, a counter electrode 54, alignment films 55 and 56, a liquid crystal layer 57, and a sealing material 58.

[0038] The first substrate 51 and the second substrate 52 are, for example, rectangular substrates in a plan view, and are arranged opposite each other. Spherical spacers (not shown) made of, for example, a resin film are dispersed between the first substrate 51 and the second substrate 52, and these spherical spacers maintain the gap between the substrates at a desired size (for example, about several μm).

[0039] Instead of spherical spacers, pillars 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 this embodiment, the first substrate 51 is arranged to face the polarizing plate 14, and the second substrate 52 is arranged to face the polarizing plate 17. In other words, the second substrate 52 side is arranged to be the light exit side of the liquid crystal element 15, and the first substrate 51 side is arranged to be the light incident side of the liquid crystal element 15.

[0040] A plurality of pixel electrodes 53 are provided on one surface of the first substrate 51. These 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 in the portion where each pixel electrode 53 faces the counter electrode 54.

[0041] The counter electrode 54 is provided on one surface of the second substrate 52. The counter electrode 54 is provided integrally with and faces each pixel electrode 53 of the first substrate 51. The counter electrode 54 is formed by appropriately patterning a transparent conductive film made of, for example, indium tin oxide (ITO).

[0042] The alignment film 55 is disposed on one surface of the first substrate 51, covering the pixel electrodes 53. The alignment film 56 is disposed on one surface of the second substrate 52, covering the counter electrode 54. These alignment films 55, 56 regulate the alignment state of the liquid crystal layer 57. Each alignment film 55, 56 has been subjected to a uniaxial alignment treatment, such as rubbing, and has a uniaxial alignment regulation force that determines the alignment of the liquid crystal molecules in the liquid crystal layer 57 along that direction. The alignment treatment directions of the alignment films 55, 56 are set, for example, to be alternate (anti-parallel). The pretilt angle near the interface between each alignment film 55, 56 and the liquid crystal layer 57 is, for example, approximately 89°. As an example, in this embodiment, an alignment film made of alicyclic polyimide or alicyclic polyamic acid is used.

[0043] The liquid crystal layer 57 is provided between the first substrate 51 and the second substrate 52. The liquid crystal layer 57 is made of, for example, a nematic liquid crystal material having fluidity. The liquid crystal layer 57 is made of, for example, a liquid crystal material having negative dielectric anisotropy. The thickness of the liquid crystal layer 57 can be, for example, about 4 μm.

[0044] 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 seal the liquid crystal layer 57 .

[0045] The internal structure and driving method of the liquid crystal element 15 are not particularly limited, as long as they can freely modulate transmitted light to form a desired image. For example, the liquid crystal element may be configured as an active matrix type liquid crystal element in which a thin film transistor is associated with each pixel portion, or as a simple matrix type liquid crystal element in which multiple striped transparent electrodes are arranged opposite each other and each overlapping area of ​​the transparent electrodes is used as a pixel portion. Furthermore, the liquid crystal element 15 may be a segment display type liquid crystal element having multiple pixel electrodes of any shape provided on one substrate and one (or multiple) counter electrodes provided on the other substrate, and in this case, either multiplex driving or static driving may be used as the driving method.

[0046] FIG. 5 is a schematic plan view 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 (segment regions), which are arranged in an effective display area, which is an inner region surrounded by a sealant 58 in a plan view. In the illustrated liquid crystal element 15, rectangular or triangular regions of various sizes each correspond to a pixel. In the figure, some pixel portions are indicated by reference numerals as examples. In this embodiment, pixel electrodes (described below) constituting each pixel are provided in approximately the same shape as each pixel portion.

[0047] For example, pixel section 70a is a small square pixel section with a small area and a small length in both the x and y directions. Pixel section 70b is a trapezoidal pixel section with a larger x-direction length than pixel section 70a and a slightly larger y-direction length than pixel section 70a. Pixel section 70c is a vertically elongated rectangular pixel section with a smaller x-direction length and a relatively larger y-direction length. Pixel section 70d is a vertically elongated rectangular pixel section with a smaller x-direction length than pixel section 70b. Pixel section 70e is a triangular pixel section with a relatively large x-direction length and a relatively large y-direction length (length of one side). Pixel section 70f is a horizontally elongated pixel section with a very large x-direction length. Pixel section 70g is a vertically elongated rectangular pixel section. Pixel section 70h is a horizontally elongated pixel section with a very large x-direction length. As shown in the figure, the liquid crystal element 15 may include pixel sections of various sizes and shapes other than those illustrated. Each pixel unit 70a, etc. can individually control whether to transmit or not transmit light, and by controlling these appropriately, it is possible to form irradiation light with various light distribution patterns according to the situation ahead of the vehicle.

[0048] FIG. 6 is a diagram illustrating the configuration of an optical system used to examine the driving conditions of a diffractive optical element. The optical system shown in FIG. 6 includes a light source 90 that emits collimated light, a polarizing plate 91 arranged in the traveling direction of the light emitted from the light source 90, an aperture plate 92 having an aperture for narrowing the light transmitted through the polarizing plate 91, a diffractive optical element 13 arranged at a position where the light transmitted through the aperture plate 92 can be incident, and a screen 93 onto which the light emitted from the diffractive optical element 13 is illuminated. The transmission axis of the polarizing plate 91 is in the Y direction as shown in the figure. The diameter of the aperture of the aperture plate 92 is 5 mm. The orientation direction of the diffractive optical element 13 is in the X direction as shown in the figure (a direction perpendicular to the transmission axis of the polarizing plate 91), and the diffractive optical element 13 is arranged in an anti-parallel configuration. The distance between the diffractive optical element 13 and the screen 93 is 10 m.

[0049] Using the above optical system, we investigated the difference in the degree of spread of light 94 transmitted through the diffractive optical element 13 and irradiated onto the screen 93, depending on the driving method of the diffractive optical element 13. The diffractive optical element 13 used in the investigation had the following dimensions: x1 of the comb-shaped electrodes 37 and 38 was 5 μm, x2 was 15 μm, x3 of the comb-shaped electrode 38 was 5 μm, x4 was 15 μm, and the distance x5 between the electrode branches of the comb-shaped electrodes 37 and 38 was 5 μm. The liquid crystal layer 41 had a thickness of 4 μm, and the liquid crystal material used had a negative dielectric anisotropy and a refractive index anisotropy of 0.18. Each of the alignment films 39 and 40 was a vertical alignment film, and was subjected to a rubbing treatment. The alignment treatment direction (rubbing direction) was approximately perpendicular to the extension direction of each electrode branch of the comb-shaped electrodes 37 and 38, and the electrodes were arranged in an anti-parallel configuration. There is no particular limitation on the refractive index anisotropy, but it is preferably 0.15 or more, as described above, and more preferably 0.2 or more.

[0050] 7(A) to 7(C) are diagrams illustrating a method for driving a diffractive optical element. FIG. 7(A) shows a driving method in which a voltage is applied between comb-tooth electrodes 37 and 38. As the electric field distribution is simply indicated by thin lines in the figure, an electric field is generated in the region between comb-tooth electrodes 37 and 38, causing an alignment change in the liquid crystal layer 41 in that region. Almost no alignment change occurs in the regions overlapping with each of comb-tooth electrodes 37 and 38. As a result, regions where an alignment change occurs due to the electric field and regions where no alignment change occurs alternately, resulting in regions with different refractive index distributions. Note that when no voltage is applied, no such refractive index distribution occurs, and the liquid crystal layer 41 is uniformly aligned.

[0051] FIG. 7B shows a driving method in which voltages are applied between the comb-shaped electrodes 37 and 38 and the common electrode 34. As the thin lines in the figure show the electric field distribution, an electric field is generated in the regions between the comb-shaped electrodes 37 and 34 and between the comb-shaped electrodes 38 and 34, causing a change in the alignment of the liquid crystal layer 41 in these regions. Alignment changes are less likely to occur in the regions between the electrode branches of each comb-shaped electrode 37, 38. This results in alternating regions where alignment changes due to the electric field occur and regions where no alignment changes occur, resulting in regions with different refractive index distributions. Regions with different refractive index distributions can be obtained at shorter intervals than with the driving method shown in FIG. 7A. When no voltage is applied, no such refractive index distribution occurs, and the liquid crystal layer 41 is uniformly aligned.

[0052] FIG. 7(C) shows a driving method in which voltages are applied between the comb-tooth electrodes 37 and 38 and the counter electrode 35. As the electric field distribution is simply indicated by thin lines in the figure, an electric field is generated in each region between the comb-tooth electrodes 37 and the counter electrode 35 and between the comb-tooth electrodes 38 and the common electrode 34, causing a change in the alignment of the liquid crystal layer 41 in these regions. With this driving method, an electric field is generated in the thickness direction of the liquid crystal layer 41. An oblique electric field is generated in the region between each of the comb-tooth electrodes 37 and 38, resulting in an alignment state that differs from that in the region overlapping with each of the comb-tooth electrodes 37 and 38. This allows regions with different refractive index distributions to be obtained. Note that when no voltage is applied, no such refractive index distribution occurs, and the liquid crystal layer 41 is uniformly aligned.

[0053] When only the driving method shown in FIG. 7(A) is used, the common electrode 34 and the counter electrode 35 may be omitted from the diffractive optical element 13. When only the driving method shown in FIG. 7(B) is used, the counter electrode 35 may be omitted from the diffractive optical element 13. When only the driving method shown in FIG. 7(C) is used, the common electrode 34 may be omitted from the diffractive optical element 13. Furthermore, when the driving methods shown in FIGS. 7(B) and 7(C) are used, the comb-shaped electrodes 37 and 38 are supplied with the same potential, so they may be electrically connected. Specifically, the wiring portions 42 and 43 (see FIG. 3(B)) may be formed so that they are physically connected at appropriate positions, such as at their ends.

[0054] 8(A) to 8(C) are diagrams showing measurement examples of light transmitted through a diffractive optical element. These diagrams show observed images of light 94 irradiated onto a screen 93 when the optical system shown in FIG. 6 was used and light was made incident on the central light modulation region 30b in the left-right direction (X direction in FIG. 6) of the diffractive optical element 13. In each driving method, a voltage of 10 V at 150 Hz was applied to the comb-shaped electrodes 37 and 38 of the diffractive optical element 13, and a reference voltage (GND voltage) was applied to the common electrode 34 and the counter electrode 35.

[0055] 8(A) is an example of light measurement 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 38. As shown in the figure, the width of light 94 on the screen 93 when no voltage is applied to the diffractive optical element 13 (OFF) is 12 degrees, whereas the width of light 94 on the screen 93 when a voltage is applied between the comb-shaped electrodes 37 and 38 of the diffractive optical element 13 (ON) is expanded to 22 degrees.

[0056] 8(B) is an example of light measurement when the diffractive optical element 13 is driven by a driving method in which voltages are applied between the comb-shaped electrodes 37 and 38 and the common electrode 34. As shown in the figure, the width of light 94 on the screen 93 when no voltage is applied to the diffractive optical element 13 (OFF) is 12 degrees, whereas the width of light 94 on the screen 93 when voltages are applied between the comb-shaped electrodes 37 and 38 of the diffractive optical element 13 and the common electrode 34 (ON) is expanded to 24 degrees.

[0057] 8(C) is an example of light measurement when the diffractive optical element 13 is driven by a driving method in which voltages are applied between the comb-shaped electrodes 37 and 38 and the counter electrode 35. As shown in the figure, the width of light 94 on the screen 93 when no voltage is applied to the diffractive optical element 13 (OFF) is 12 degrees, whereas the width of light 94 on the screen 93 when voltages are applied between the comb-shaped electrodes 37 and 38 of the diffractive optical element 13 and the counter electrode 35 (ON) is expanded to 18 degrees.

[0058] Therefore, it can be seen that the width of the light 94 can be widened most when using the driving method (see FIG. 7(B)) of applying voltage between the comb-shaped electrodes 37 and 38 of the diffractive optical element 13 and the common electrode 34. On the other hand, it can be seen that the change in the width of the light 94 is smallest when using the driving method (see FIG. 7(C)) of applying voltage between the comb-shaped electrodes 37 and 38 of the diffractive optical element 13 and the counter electrode 35.

[0059] In order to confirm the diffraction effect, the light source 90 in the optical system of FIG. 6 was replaced with a laser light source, and the diffractive optical element 13 was driven by applying voltage between the comb-tooth electrodes 37 and 38 and the common electrode 34. In this case, diffraction spots of first-order or higher light were obtained on the screen 93, and it was confirmed that a diffraction effect was occurring.

[0060] Next, we will describe an example of observing projected light emitted from the projection lens 18 when a diffractive optical element 13 manufactured under the same conditions as those used in the above evaluation was incorporated into the vehicle lighting system shown in Figure 1 and operated. Here, a drive voltage was applied to the liquid crystal element 15 so that the entire surface was light-transmitting. As shown in the conical schematic diagram of Figure 9, light emitted from the light source 11, collected by the reflector 12, and incident on the diffractive optical element 13 is incident at a wide angle with a maximum collection angle of ±40° to 50°, and light is incident from a nearly normal direction near the light modulation region 30b located at the center of the diffractive optical element 13. The diffractive optical element 13 is arranged so that the arrangement direction of each light modulation region 30a to 30c coincides with the left-right direction of the vehicle lighting system.

[0061] Figures 10(A) to 10(C) are diagrams showing measurement examples of the light intensity distribution of the projection light. In these measurement examples, the light intensity distribution was measured with a screen placed 10 m in front of the projection lens 18. Each of the measurement examples in Figures 10(A) to 10(C) shows a roughly elliptical light intensity distribution that extends to the left and right, with the brightness increasing toward the center of the elliptical distribution.

[0062] 10(A) shows the light intensity distribution when no drive voltage is applied to the diffractive optical element 13. In this case, the light intensity distribution is the same as when the diffractive optical element 13 is not provided, and is approximately symmetrical.

[0063] Figure 10(B) shows the light intensity distribution when a drive voltage is applied to the left light modulation region 30a in the diffractive optical element 13, and no drive voltage is applied to the other light modulation regions 30b and 30c. In this case, as can be seen from a comparison with the light intensity distribution in Figure 10(A), the projection light is shifted by approximately 3° to the right in the figure. Note that because the transmitted light is inverted vertically and horizontally by the projection lens 18, the position of the light modulation region 30a and the direction of movement of the projection light are reversed.

[0064] Fig. 10(C) shows the light intensity distribution when a drive voltage is applied to each of the light modulation regions 30a to 30c in the diffractive optical element 13. In this case, as can be seen from a comparison with the light intensity distribution in Fig. 10(A), it can be seen that the projected light spreads to the left and right in the figure.

[0065] By ensuring a larger gap between the diffractive optical element 13 and the liquid crystal element 15, the degree of movement and spread of light can be increased.

[0066] Next, the light distribution control of the diffractive optical element 13 will be described in more detail. As shown in Fig. 11(A), parallel light 100 was incident on the diffractive optical element 13 from the normal direction of the incident surface (projection angle = 0°), and the transmittance was measured by a light-receiving element 101 when the voltage applied between each of the comb-shaped electrodes 37, 38 of the diffractive optical element 13 and the common electrode 34 was set between 0 V and 30 V. Similarly, as shown in Fig. 11(B), parallel light 100 was incident on the diffractive optical element 13 at a projection angle greater than 0° based on the normal direction of the incident surface, and the transmittance was measured by the light-receiving element 101 when the voltage applied between each of the comb-shaped electrodes 37, 38 of the diffractive optical element 13 and the common electrode 34 was set between 0 V and 30 V. The light-receiving element 101 was set to have a light-receiving angle θ that was variable in the positive and negative directions based on the normal direction of the diffractive optical element 13.

[0067] 12(A) is a graph showing the relationship between the acceptance angle and transmittance when the projection angle of incident parallel light is 0°. When the voltage applied to the diffractive optical element 13 is 10 V and when it is 20 V, the characteristics are almost the same, and the characteristic lines are almost overlapping. As shown in the figure, the transmittance of light traveling straight in the direction of acceptance angle = 0° is approximately 85% when the applied voltage is 0 V, and decreases to about 30% as the applied voltage is increased, and it can be seen that the transmittance spreads to the left and right directions (directions where the absolute value of the acceptance angle is large) accordingly.

[0068] Figure 12(B) is a graph showing the relationship between the acceptance angle and transmittance when the projection angle of incident parallel light is set to +30°. A positive projection angle corresponds to the state in which parallel light is incident from the direction shown in Figure 11(B) above. The transmittance of light traveling straight in the direction of acceptance angle = -30° is approximately 80% when the applied voltage is 0 V, and decreases to around 30% as the applied voltage is increased, with the result that the transmittance expands mainly to the left (positive acceptance angle).

[0069] Figure 12(C) is a graph showing the relationship between the acceptance angle and transmittance when the projection angle of incident parallel light is set to +60°. A positive projection angle corresponds to the state in which parallel light is incident from the direction shown in Figure 11(B) above. The transmittance of light traveling straight in the direction of acceptance angle = -60° is approximately 60% when the applied voltage is 0 V, and decreases to 30% or less as the applied voltage is increased, and it can be seen that the transmittance increases mainly to the left (positive acceptance angle).

[0070] 13(A) to 13(C) are diagrams showing the state of light that is subjected to the diffraction effect of the diffractive optical element and enters a liquid crystal element. In each diagram, for convenience, the light that is collected at the position of the liquid crystal element 15 (light traveling from bottom to top in the diagram) is divided into three light beams L1, L2, and L3, each indicated by a dotted line. Light beam L1 is light that is mainly incident on each light modulation region 30a of the diffractive optical element 13, light beam L2 is light that is mainly incident on each light modulation region 30b of the diffractive optical element 13, and light beam L3 is light that is mainly incident on each light modulation region 30c of the diffractive optical element 13.

[0071] When no voltage is applied to any of the light modulation regions 30a to 30c of the diffractive optical element 13, as shown in Figure 13(A), the light L1 to L3 emitted from the light source 11 and collected by the reflector 12 passes directly through the diffractive optical element 13 and enters the liquid crystal element 15, forming a focus at the position of the liquid crystal element 15.

[0072] 13B, light L1 incident on this light modulation region 30a is bent and spreads before entering the liquid crystal element 15. The other light beams L2 and L3 are incident on the liquid crystal element 15 as they are. Therefore, the projection light that passes through the liquid crystal element 15 and is projected by the projection lens 18 is irradiated while spreading to the left side in the figure.

[0073] Although not shown, the same occurs when a voltage is applied only to the light modulation region 30c of the diffractive optical element 13, in which case light L3 incident on the light modulation region 30c bends and spreads before entering the liquid crystal element 15. The other light beams L1 and L2 are incident directly on the liquid crystal element 15. Therefore, the projection light that passes through the liquid crystal element 15 and is projected by the projection lens 18 is irradiated while spreading to the right in the drawing.

[0074] 13C, when a voltage is applied to all of the light modulation regions 30a to 30c of the diffractive optical element 13, the light beams L1 to L3 emitted from the light source 11 and collected by the reflector 12 are incident on the liquid crystal element 15 while spreading to the left and right. Therefore, the projection light transmitted through the liquid crystal element 15 and projected by the projection lens 18 is irradiated while spreading to the left and right in the figure.

[0075] In this way, the degree of spread of the projected light can be controlled using each of the light modulation regions 30a to 30c, so that when the vehicle is traveling at a relatively high speed, for example when traveling on a highway, the projected light does not spread but is concentrated in the front direction of the vehicle, and on the other hand, when the vehicle is traveling at a relatively low speed, for example when traveling in an urban area, the projected light spreads to the left and right, thereby realizing a light distribution state according to the traveling situation and improving visibility in front of the vehicle. Also, by selectively using the diffraction effect of either of the light modulation regions 30a, 30c, it is possible to increase the amount of light irradiated to the left front or right front of the vehicle depending on the traveling direction of the vehicle, thereby improving visibility in the traveling direction of the vehicle.

[0076] 14A is a diagram showing an example of the illuminance distribution of the projected light when no voltage is applied to the diffractive optical element 13. When the diffraction effect of the diffractive optical element 13 is not used, the illuminance distribution is almost symmetrical around the reference position of 0° in the left-right direction, as shown in the figure.

[0077] FIG. 14(B) shows the calculated illuminance distribution of projected light when voltage is applied to all light modulation regions of the diffractive optical element. The calculation was performed assuming a distance of 8 mm between the diffractive optical element 13 and the liquid crystal element 15. This distance corresponds to a 45° incident angle of light passing through the light modulation region 30a of the diffractive optical element 13 and entering the center of the liquid crystal element 15. As shown in the figure, applying voltage to all light modulation regions 30a to 30c spreads the high-illuminance band to the left and right. The intensity of the light striking the center of the liquid crystal element 15 at this time is reduced to approximately two-thirds, resulting in a spread of approximately ±5° to the left and right.

[0078] FIG. 14(C) shows the calculated illuminance distribution of projected light when a voltage is applied to light modulation region 30a, which is one of the light modulation regions of the diffractive optical element. The calculation was performed assuming a distance of 8 mm between the diffractive optical element 13 and the liquid crystal element 15. In this case, it can be seen that the high-illuminance band shifts by approximately +5°. The angle at which the high-illuminance band shifts can be increased by increasing the distance between the diffractive optical element 13 and the liquid crystal element 15. For example, if the distance is set to 20 mm, the high-illuminance band is expected to shift by approximately +12.5°. This value satisfies the deflection angle required for AFS (Adaptive Front-Lighting System) technology, which variably controls the light irradiation direction according to the vehicle's traveling direction.

[0079] According to the above-described embodiment, it is possible to realize diversification of light distribution control of irradiated light in a lighting device such as a vehicle lamp or a system using the same.

[0080] The present disclosure is not limited to the above-described embodiments, and various modifications can be made within the scope of the gist of the present disclosure. For example, the number of light modulation regions included in the diffractive optical element 13 is not limited to the three illustrated. In the above-described embodiments, the light modulation regions are arranged in one direction, but they may be arranged in two directions. In the above-described embodiments, the diffractive optical element 13 is arranged between the light source 10 and the polarizing plate 14, but the diffractive optical element 13 may be arranged between the polarizing plate 14 and the liquid crystal element 15. The former arrangement is more preferable because it allows a relatively large distance to be secured between the diffractive optical element 13 and the liquid crystal element 15.

[0081] Furthermore, while the above-described embodiments have been described using a four-wheel vehicle as an example, the technical concepts of the present disclosure can be similarly applied to headlights of various vehicles other than four-wheel vehicles. Furthermore, while the above-described embodiments have illustrated a vehicle lamp as an example of a lighting device, the present disclosure can be applied to lighting devices for displaying various images, such as road surfaces, street lights, railroad crossing signals, and direction guides. Furthermore, in the case of a vehicle lamp, projected light spreads left and right as shown in FIG. 10 , it is desirable for the bright area that spreads horizontally to move left and right while remaining bright. For this reason, the comb-shaped electrodes used in the diffractive optical element have straight slits. For other applications (such as lighting devices), comb-shaped electrodes with slits whose slit direction is changed relative to the direction of light incident on the diffractive optical element may also be used. For example, when light is incident from the direction shown in FIG. 9 , the electrodes in the light modulation region 30b may be horizontal slit electrodes, and the electrodes in the light modulation region 30a may be "L"-shaped slit electrodes. Furthermore, various comb-shaped electrode structures, such as U-shaped, concentric circular, and elliptical, may also be used.

[0082] The present disclosure has the following additional features.

[0083] (Appendix 1) A light source and a light collecting unit that collects the light emitted from the light source; a liquid crystal element disposed at a focal position of the light condensed by the condensing 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; a diffractive optical element disposed between the light source and the liquid crystal element; Including, the diffractive optical element has a plurality of light modulation regions that can be electrically switched between a first state in which the refractive index changes periodically or continuously and a second state in which the refractive index is substantially uniform; the first state is capable of producing a diffraction effect on incident light; each of the plurality of light modulation areas is disposed at a position where the light can be incident and closer to the light source than the focal position; Lighting equipment. (Appendix 2) the diffractive optical element is disposed between the light source and the first polarizing plate. 10. The lighting device of claim 1. (Appendix 3) the diffractive optical element is disposed between the first polarizing plate and the liquid crystal element. 10. The lighting device of claim 1. (Appendix 4) Each of the plurality of light modulation regions of the diffractive optical element is a liquid crystal layer provided between a first substrate and a second substrate disposed opposite to each other; a comb-shaped electrode provided on the first substrate so as to overlap the liquid crystal layer in a plan view, 4. The lighting device according to claim 1. (Appendix 5) Each of the plurality of light modulation regions of the diffractive optical element is a common electrode provided on one surface of the first substrate facing the liquid crystal layer closer to the one surface than the comb-shaped electrode, and arranged so as to overlap the comb-shaped electrode in a plan view; an insulating film disposed between the comb-shaped electrode and the common electrode; 5. The lighting device of claim 4, comprising: (Appendix 6) Each of the plurality of light modulation regions of the diffractive optical element is a counter electrode provided on one surface of the second substrate facing the liquid crystal layer and arranged so as to overlap the comb-shaped electrode in a plan view; 6. The lighting device of claim 5, comprising: (Appendix 7) the comb-shaped electrode has a plurality of electrode branches, 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. 7. The lighting device according to any one of claims 4 to 6. (Appendix 8) A vehicle lamp configured using the lighting device according to any one of Supplementary Notes 1 to 7; a controller connected to the vehicle lamp, the controller controlling the operation of the liquid crystal element of the vehicle lamp and the operation of the diffractive optical element in accordance with the situation around the vehicle; Including, Vehicle lighting system. [Explanation of symbols]

[0084] 1: vehicle lamp (illumination device), 2: controller, 3: camera, 11: light source, 12: reflector (reflective member), 13: diffractive optical element, 14: polarizing plate, 15: liquid crystal element, 16: optical compensation plate, 17: polarizing plate, 18: projection lens, 30a, 30b, 30c: light modulation area, 32: first substrate, 33: second substrate, 34: common electrode, 35: counter electrode, 36: insulating film, 37, 38: comb-shaped electrodes, 39, 40: alignment film, 41: liquid crystal layer

Claims

1. A light source and a light collecting unit that collects the light emitted from the light source; a liquid crystal element disposed at a focal position of the light condensed by the condensing 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; a diffractive optical element disposed between the light source and the liquid crystal element; Including, the diffractive optical element has a plurality of light modulation regions that can be electrically switched between a first state in which a refractive index changes periodically or continuously and a second state in which the refractive index is substantially uniform; the first state is capable of producing a diffraction effect on incident light; each of the plurality of light modulation areas is disposed at a position where the light can be incident and closer to the light source than the focal position; Lighting equipment.

2. the diffractive optical element is disposed between the light source and the first polarizing plate. The lighting device according to claim 1 .

3. the diffractive optical element is disposed between the first polarizing plate and the liquid crystal element; The lighting device according to claim 1 .

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

5. Each of the plurality of light modulation regions of the diffractive optical element is a common electrode provided on one surface of the first substrate facing the liquid crystal layer closer to the one surface than the comb-shaped electrode, and arranged so as to overlap the comb-shaped electrode in a plan view; an insulating film disposed between the comb-shaped electrode and the common electrode; 5. The lighting device of claim 4, comprising:

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

7. the comb-shaped electrode has a plurality of electrode branches, 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.

5. The lighting device according to claim 4.

8. a vehicle lamp configured using the lighting device according to claim 1; a controller connected to the vehicle lamp, the controller controlling the operation of the liquid crystal element of the vehicle lamp and the operation of the diffractive optical element in accordance with the situation around the vehicle; Including, Vehicle lighting system.

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