Collimator lens, light radiation device, and vehicle lighting apparatus

A collimator lens in use for a vehicle lighting apparatus includes: an incident surface which allows incident light to become primary light that passes through an inside of the collimator lens; and an emission surface that is configured to emit secondary light parallel to an optical axis of the collimator lens, wherein a diffusion angle of a horizontal component of the primary light is larger than a diffusion angle of a component in a vertical direction of the primary light.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is a U.S. National Stage Application under 35 U.S.C § 371 of International Patent Application No. PCT/JP2018/019305 filed May 18, 2018, which claims the benefit of priority to Japanese Patent Application No. 2017-102639 filed May 24, 2017, the disclosures of all of which are hereby incorporated by reference in their entireties.

TECHNICAL FIELD

The present invention relates to a collimator lens, a light radiation device, and a vehicle lighting apparatus.

Priority is claimed on Japanese Patent Application No. 2017-102639, filed on May 24, 2017, the contents of which are incorporated herein by reference.

BACKGROUND

Patent Document 1 discloses a vehicle headlight unit that includes a liquid crystal element for performing selective light irradiation to a frontward direction of a vehicle. In the vehicle headlight unit, by a parallel optical system, light that is incident on the liquid crystal element is made to be parallel light. In this way, in the related art, a vehicle headlight unit is known in which a parallel optical system (collimator lens) is provided in an optical path.

RELATED ART DOCUMENTS

Patent Documents

SUMMARY OF INVENTION

Problems to be Solved by the Invention

In a general vehicle lighting apparatus, by a projection lens, a light distribution pattern that is wide in a horizontal direction desirable for a vehicle lighting apparatus is formed. In a vehicle lighting apparatus that includes a collimator lens, in a case where the light distribution pattern is formed by a projection lens, it is necessary to form a wide light distribution pattern by refracting parallel light, and there is a problem that a surface shape of a projection optical system and the entire structure of the vehicle lighting apparatus are complicated.

An object of an aspect of the present invention is to provide a collimator lens capable of forming a light distribution pattern preferable for a vehicle lighting apparatus, and a light radiation device and a vehicle lighting apparatus that include such a collimator lens.

Means for Solving the Problem

A collimator lens according to an aspect of the present invention is a collimator lens in use for a vehicle lighting apparatus, the collimator lens including: an incident surface on which the light that is radiated radially from a diffusion center is incident and which allows the incident light to become primary light that passes through an inside of the collimator lens; and an emission surface that is configured to emit secondary light parallel to an optical axis of the collimator lens, wherein a diffusion angle of a horizontal component of the primary light is larger than a diffusion angle of a component in a vertical direction of the primary light.

According to this configuration, the collimator lens refracts the light that is incident on the incident surface and makes the diffusion angle in the horizontal direction to be larger than the diffusion angle in the vertical direction. Thereby, the light distribution pattern of the light emitted as parallel light from the emission surface can be widened in the horizontal direction, and it is possible to form a light distribution pattern preferable for the vehicle lighting apparatus.

In the collimator lens described above, a vertical component of the incident surface may have a hyperbolic shape that is configured to match a hyperbolic focus with the diffusion center.

According to this configuration, since the vertical component of the incident surface has a hyperbolic shape in which the diffusion center is a hyperbolic focus, it is possible to allow the vertical component of the primary light to be parallel light. The collimator lens can prevent expansion in the vertical direction of the light distribution pattern by allowing the vertical component of the light to be the parallel light in the incident surface.

In the collimator lens described above, a horizontal component of the incident surface may have a hyperbolic shape that is configured to match a hyperbolic focus with the diffusion center in a vicinity of the optical axis of the collimator lens and have a shape in which the horizontal component of the incident surface is separated further rearward from the hyperbolic shape as the horizontal component of the incident surface is separated further outward in a horizontal direction from the optical axis of the collimator lens.

According to this configuration, since the horizontal component of the incident surface has a hyperbolic shape in which the diffusion center is the hyperbolic focus in the vicinity of the optical axis of the collimator lens, it is possible to allow the horizontal component of the primary light to be closer to parallel light in the vicinity of the optical axis of the collimator lens. Thereby, the density of a light flux emitted from the emission surface can be increased in the vicinity of the optical axis of the collimator lens, and it is possible to realize a light distribution pattern brightened in the vicinity of the middle in the horizontal direction. Further, according to the above configuration, the horizontal component of the incident surface is separated further rearward from the hyperbolic shape as it is separated further outward in the horizontal direction from the optical axis of the collimator lens. Thereby, the horizontal component of the primary light can enlarge the diffusion angle by being separated outward in the horizontal direction from the optical axis of the collimator lens. The collimator lens can realize a light distribution pattern appropriate for a vehicle by diffusing an outside region of the horizontal component of light and increasing the expansion in the horizontal direction of the light distribution pattern.

Further, a light radiation device according to another aspect of the present invention includes: the collimator lens described above; and a light source unit that has a light source main body and that is configured radiate light radially from the diffusion center.

According to this configuration, it is possible to provide a light radiation device that forms a light distribution pattern preferable for a vehicle lighting apparatus.

In the light radiation device described above, the light source unit may have the light source main body and an elliptical reflection surface that is configured to reflect the light radiated from the light source main body and that is configured radiate the light toward the collimator lens, the elliptical reflection surface may be configured in an elliptical shape with reference to a pair of elliptical focuses, the light source main body may be arranged at one of the pair of elliptical focuses, and another of the pair of elliptical focuses may function as the diffusion center.

According to this configuration, a Lambertian-emitted light beam radiated from the light source main body arranged at the one elliptical focus of the elliptical reflection surface can be condensed at the other elliptical focus and can enter the collimator lens at a narrower angle than that of the light radiated from the light source main body. Thereby, the light can efficiently enter the collimator lens, and a light intensity in the vicinity of the optical axis can be increased such that a high illuminance region is formed in the vicinity of the optical axis of the collimator lens.

A vehicle lighting apparatus according to still another aspect of the present invention includes: the light radiation device described above; and an image light formation device that is configured to modulate parallel light radiated from the light radiation device and that forms image light.

According to this configuration, by providing the image light formation device in a route of the light, the light distribution pattern radiated frontward can be changed over time. That is, according to this configuration, the vehicle lighting apparatus can perform an ADB (Adaptive Driving Beam) control.

Advantage of the Invention

According to the aspect of the present invention, it is possible to provide a collimator lens capable of forming a light distribution pattern preferable for a vehicle lighting apparatus, and a light radiation device and a vehicle lighting apparatus that include such a collimator lens.

DESCRIPTION OF THE EMBODIMENTS

Hereinafter, a vehicle lighting apparatus according to an embodiment of the present invention will be described with reference to the drawings.

In the drawings used in the following description, in order to make features easier to understand, feature parts may be enlarged for the sake of convenience, and dimensional ratios or the like of components are not always the same as the actual ones.

In the drawings used in the description of the present embodiment, an XYZ coordinate system may be used as a 3-dimensional orthogonal coordinate system. Hereinafter, in the XYZ coordinate system, a Z-axis direction is referred to as a vehicle frontward/rearward direction, an X-axis direction is referred to as a vehicle rightward/leftward direction, a Y-axis direction is referred to as a vehicle upward/downward direction, a +Z side is referred to as a vehicle frontward side, a −Z side is referred to as a vehicle rearward side, a +Y side is simply referred to as an upward side, and a −Y side is simply referred to as a downward side.

First Embodiment

FIG. 1,FIG. 2andFIG. 3are views schematically showing a vehicle lighting apparatus1according to a first embodiment,FIG. 1is a perspective view,FIG. 2is a side view, andFIG. 3is a plan view. The vehicle lighting apparatus1of the present embodiment is mounted on a vehicle and irradiates a frontward direction (+Z direction) of the vehicle.

The vehicle lighting apparatus1includes a light radiation device10, a condenser lens (first optical system)30, and a cover member40in which an opening41is provided. Further, the vehicle lighting apparatus1may include an outer lens (not shown) at a frontward position of the cover member40. In the vehicle lighting apparatus1, parallel light is radiated from the light radiation device10. The parallel light is condensed by the condenser lens30, passes through the opening41of the cover member40, and is radiated frontward.

The light radiation device10has a light source main body12. The light radiation device10radiates light radiated from the light source main body12toward the condenser lens30as parallel light. The light radiation device10has a light source unit11that radiates light radially from a diffusion center11aand a collimator lens (second optical system)20that allows the light radiated from the light source unit11to be parallel light. Further, the light source unit11includes the light source main body12and a reflection member14.

The light source main body12radiates a Lambertian-emitted light beam with a central axis facing upward. The Lambertian-emitted light beam radiated from the light source main body12is reflected frontward by the reflection member14. A light emitting diode (LED) light source or a laser light source can be employed as the light source main body12.

The reflection member14has an elliptical reflection surface13that reflects the light radiated from the light source main body12and that radiates the light toward the collimator lens20. That is, the light source unit11has the elliptical reflection surface13. The elliptical reflection surface13covers the light source main body12from the upper side. The elliptical reflection surface13includes an elliptical sphere shape obtained by an elliptical shape with reference to a pair of elliptical focuses13aand13bbeing rotated with reference to a long axis that passes through the pair of elliptical focuses13aand13b.

The light source main body12is arranged at a first elliptical focus13alocated at a rearward position among the pair of elliptical focuses13aand13b. Due to a property of an ellipse, the light radiated from the first elliptical focus13athat is one of the elliptical focuses is reflected by the elliptical reflection surface13and is condensed to a second elliptical focus13bthat is another of the elliptical focuses. Accordingly, the light radiated from the light source main body12is condensed on the second elliptical focus13band is radiated radially toward the collimator lens20using the second elliptical focus13bas the diffusion center11a. The second elliptical focus13bfunctions as the diffusion center11aof the light source unit11.

According to the present embodiment, the light source unit11arranged at the first elliptical focus13ahas the light source main body12and the elliptical reflection surface13that reflects the light radiated from the light source main body12and that radiates the light toward the collimator lens20. Accordingly, it is possible to allow the Lambertian-emitted light beam radiated from the light source main body12to be incident on the collimator lens20at a narrow diffusion angle (narrow angle) at the second elliptical focus13b. Thereby, it is possible to allow the light to be efficiently incident on the collimator lens20, and it is possible to increase a light intensity in the vicinity of an optical axis AX20such that a high illuminance region is formed in the vicinity of the optical axis AX20of the collimator lens20. Further, by employing such a collimator lens20, it is possible to obtain a light emission having an illuminance gradient in which illuminance decreases at a more outward position from the high illuminance region.

The collimator lens20refracts the light radiated from the diffusion center11aof the light source unit11to form parallel light. The collimator lens20is located at a frontward position of the light source unit11. The collimator lens20has an incident surface21and an emission surface25. The incident surface faces the light source unit11from the front. The light radiated from the light source unit11is incident on the incident surface21. The incident surface21allows the incident light to become primary light L1that passes through the inside of the collimator lens20. The emission surface25faces the condenser lens30. The emission surface25refracts the light (primary light L1) that proceeds through the inside of the collimator lens20and emits secondary light L2toward the condenser lens30. The secondary light L2is light parallel to the optical axis AX20of the collimator lens20(that is, parallel light).

The light emitted from the light source unit11is refracted at the incident surface21in a direction in which the light approaches the optical axis AX20of the collimator lens20and becomes the primary light L1that passes through the inside of the collimator lens20. A diffusion angle of a horizontal component of the primary light L1shown inFIG. 3is larger than a diffusion angle of a vertical component of the primary light L1shown inFIG. 2. That is, an angle formed between the horizontal component of the primary light L1and the optical axis AX20is larger than an angle formed between the vertical component of the primary light L1and the optical axis AX20.

More specifically, in the present embodiment, the vertical component of the primary light L1is substantially parallel to the optical axis AX20. That is, the angle formed between the vertical component of the primary light L1and the optical axis AX20is substantially 0°. On the other hand, the horizontal component of the primary light L1is inclined with respect to the optical axis AX20in a direction in which the horizontal component is separated from the optical axis AX20as it goes frontward. That is, the horizontal component of the primary light L1is diffused with respect to the optical axis AX20.

The horizontal component of the light means a travel direction of light in a plane parallel to a horizontal surface (X-Z plane), and the vertical component of the light means a travel direction of light in a plane parallel to a vertical surface (Y-Z plane).

According to the present embodiment, the collimator lens20refracts the light that is incident on the incident surface21such that the diffusion angle in the horizontal direction is increased relative to the vertical direction. Thereby, a light distribution pattern of the light emitted as the parallel light at the emission surface25can be widened in the horizontal direction relative to the vertical direction, and it is possible to form a light distribution pattern preferable for a vehicle lighting apparatus.

A vertical component and part of a horizontal component of the incident surface21of the collimator lens20have a hyperbolic shape. In general, a hyperbolic curve is constituted of a pair of continuous curves. Further, the hyperbolic curve constituted of the pair of curves is drawn with reference to a pair of focuses. Each of the pair of focuses of the hyperbolic curve is arranged at an inner side of the curve. The hyperbolic shape means a curve shape of one of the pair of curves. Further, a hyperbolic focus means one of the pair of focuses with reference to the hyperbolic curve, which is not surrounded by a curve that constitutes a hyperbolic shape. The hyperbolic focus is arranged on the optical axis AX20of the collimator lens20behind the incident surface21.

As shown inFIG. 2, the vertical component of the incident surface21has a hyperbolic shape that matches the hyperbolic focus with the diffusion center11aof the light source unit11. By appropriately setting a parameter of the hyperbolic shape in accordance with a refractive index of the collimator lens20, due to a property of the hyperbolic shape, the light radiated from the hyperbolic focus is refracted at the incident surface21having the hyperbolic shape and becomes parallel light. Accordingly, in the present embodiment, it is possible to allow the vertical component of the primary light L1refracted at the incident surface21to become parallel to the optical axis AX20. Thereby, it is possible for the collimator lens20to prevent the expansion in the vertical direction of the light distribution pattern radiated frontward.

Since the vertical component of the primary light L1is parallel to the optical axis AX20in the incident surface21, there is no need to refract the light at the emission surface25. Accordingly, the vertical component of the emission surface25has a linear shape that is orthogonal to the optical axis AX20.

As shown inFIG. 3, the horizontal component of the incident surface21has a hyperbolic shape H that matches the hyperbolic focus with the diffusion center in the vicinity of the optical axis AX20and has a shape that is separated further rearward from the hyperbolic shape H as it is separated further outward in the horizontal direction from the optical axis AX20. As described above, by appropriately setting the parameter of the hyperbolic shape in accordance with the refractive index of the collimator lens20, due to the property of the hyperbolic shape, the light radiated from the hyperbolic focus is refracted at the incident surface21in the vicinity of the optical axis AX20and becomes parallel light. Accordingly, in the present embodiment, it is possible to allow the horizontal component of the primary light L1refracted at the incident surface21to be parallel to the optical axis AX20in the vicinity of the optical axis AX20. Thereby, in the vicinity of the optical axis AX20, it is possible to increase the density of the light flux emitted from the emission surface25, and it is possible to realize a light distribution pattern brightened in the vicinity of the middle in the horizontal direction. Further, according to the present embodiment, the horizontal component of the incident surface21is separated further rearward from the hyperbolic shape as it is separated further outward in the horizontal direction from the optical axis AX20. Thereby, it is possible for the horizontal component of the primary light L1to expand the diffusion angle by being separated outward in the horizontal direction from the optical axis AX20. Accordingly, the collimator lens20can increase the expansion in the horizontal direction of the light distribution pattern and realize a light distribution pattern appropriate for the vehicle by diffusing an outer region of the horizontal component of the light.

The horizontal component of the primary light L1advances in a direction inclined with respect to the optical axis AX20at the incident surface21, is refracted at the emission surface25, and is radiated toward the condenser lens30as the secondary light L2that is parallel to the optical axis AX20. The horizontal component of the emission surface25has a convex shape that protrudes toward the condenser lens30.

According to the present embodiment, the collimator lens20refracts the light that is incident on the incident surface21and increases the diffusion angle in the horizontal direction relative to the diffusion angle in the vertical direction. Thereby, the light distribution pattern of the light emitted as parallel light from the emission surface25can be widened in the horizontal direction, and it is possible to form a light distribution pattern preferable for the vehicle lighting apparatus1.

The vertical component of the incident surface21means a cross-sectional shape along the vertical direction of the incident surface21. In other words, the vertical component of the incident surface21means a surface shape of the incident surface21in a cross-section parallel to a vertical plane (Y-Z plane) parallel to the optical axis AX20. Similarly, the horizontal component of the incident surface21means a cross-sectional shape along the horizontal direction of the incident surface21. In other words, the horizontal component of the incident surface21means a surface shape of the incident surface21in a cross-section parallel to a horizontal plane (X-Z plane).

The condenser lens30is arranged at a frontward position of the light radiation device10. The condenser lens30functions as a projection lens. An optical axis AX30of the condenser lens30is matched with the optical axis AX20of the collimator lens20of the light radiation device10. The condenser lens30condenses the light radiated from the light radiation device10. The condenser lens30forms condensing points30aand30bat frontward and rearward positions. Here, one of the pair of condensing points30aand30barranged at a frontward position of the condenser lens30is referred to as a frontward condensing point30a. Another of the pair of condensing points30aand30barranged at a rearward position of the condenser lens30is referred to as a rearward condensing point30b. The secondary light L2as parallel light radiated from the light radiation device10is condensed to the frontward condensing point30aby the condenser lens30.

In the present embodiment, the pair of condensing points30aand30bare matched with an optical focus of the condenser lens30. However, the condensing point means a point to which the condenser lens30can most condense the light and does not necessarily have to be a focus in a strict sense.

The condenser lens30may be a condenser lens that does not have a strict focus as long as the condenser lens30can condense light, and in that case, a point to which the light is most condensed is defined as the condensing point.

FIG. 4is a schematic view of the vehicle lighting apparatus1of the present embodiment. Light La that passes through a point separated from the optical axis AX30of the condenser lens30by a distance y in a direction orthogonal to the optical axis AX30and that is incident on the condenser lens30is incident on a focus (condensing point30a) of the condenser lens30, when an effective focal distance of the condenser lens30is F, at an angle θ=tan−1(y/F) with respect to the optical axis AX30and is then projected toward a vehicle frontward direction. The effective focal distance F is a distance to a focus (condensing points30aand30b) from an intersection point CP in a lens of extension lines of optical paths before entering and after exiting the condenser lens30.

According to the equation described above, a light distribution pattern of a surface distribution appropriate for the vehicle formed as parallel light by the collimator lens20is converted into light having a predetermined angle and is projected to a vehicle frontward direction.

In the present embodiment, the condenser lens30is a convex lens in which a rearward surface is a flat surface and a frontward surface is a convex surface. However, the condenser lens30is an example of a first optical system that condenses light to the frontward condensing point30a, and the configuration of the condenser lens30is not limited to the present embodiment. For example, as the first optical system, instead of the condenser lens30, a plurality of optical systems may be configured to be aligned in a frontward/rearward direction such that optical axes of the plurality of optical systems are matched with each other.FIG. 4is a schematic view, and the frontward surface and the rearward surface of the condenser lens30are shown as convex surfaces. In this way, the frontward surface and the rearward surface of the condenser lens30may be a convex surface.

The cover member40has a plate shape. The cover member40is arranged at a frontward position of the condenser lens30. The cover member40overlaps at least part of the condenser lens30when seen from the frontward direction. That is, the cover member40covers the condenser lens30from the frontward direction. A frontward surface40aof the cover member40functions as a design surface. That is, the frontward surface40aof the cover member40makes it difficult to see an internal structure including the condenser lens30and the light radiation device10when seen from the frontward direction. Thereby, the cover member40enhances a design property of the vehicle lighting apparatus1.

The opening41that penetrates in the frontward/rearward direction is provided in the cover member40. In the present embodiment, the opening41is a pinhole. The opening41may be, for example, a slit that extends in one direction. Further, a shape of the opening41may be a shape widened in the horizontal direction in conformity with a shape of a light distribution pattern radiated frontward.

The opening41is arranged on the optical axis AX30of the condenser lens30. The parallel light (secondary light L2) radiated from the light radiation device10is refracted by the condenser lens30and is condensed onto the optical axis AX30of the condenser lens30. Accordingly, it is possible to allow light having a narrowed passing range to pass through the opening41by arranging the opening41on the optical axis AX30of the condenser lens30. That is, it is possible make the opening41small and make it difficult to see the internal structure of the vehicle lighting apparatus1by arranging the opening41on the optical axis AX30of the condenser lens30.

Further, in the present embodiment, the opening41is located at the frontward condensing point30aof the condenser lens30. The light refracted by the condenser lens30is most condensed to the frontward condensing point30a.

It is possible to make the opening41to be the smallest one by arranging the opening41at the frontward condensing point30a, and as a result, it is possible to enhance an effect of the cover member40making it difficult to see the internal structure of the vehicle lighting apparatus1.

According to the present embodiment, the cover member40that overlaps at least part of the condenser lens30is provided at a frontward position of the condenser lens30. Therefore, the internal structure is shielded from the frontward direction, and it is possible to realize the vehicle lighting apparatus1having an enhanced design property. Further, the opening41located on the optical axis AX30of the condenser lens30is provided in the cover member40. The light parallelized by the light radiation device10enters the condenser lens30, is condensed on the optical axis AX30, and passes through the opening41. Accordingly, the light that radiates the frontward direction is not shielded by the cover member40.

Further, according to the present embodiment, since the frontward surface40aof the cover member40functions as a design surface, the size of the design surface can be determined without being restricted by the size of the condenser lens30. Accordingly, it is possible to provide the vehicle lighting apparatus1having a compact appearance and an enhanced design property.

Further, according to the present embodiment, a distribution having an illuminance gradient is generated in the parallel light (secondary light L2) radiated by the light radiation device10by appropriately designing the incident surface21and the emission surface25of the collimator lens20. Thereby, the vehicle lighting apparatus1can form a light distribution pattern in which the illuminance decreases at a further outward position from the high illuminance region (refer toFIG. 5andFIG. 6).

In the present embodiment, the vehicle lighting apparatus1has the condenser lens30and the cover member40in which the opening41provided. However, the vehicle lighting apparatus1may not have the condenser lens30and the cover member40as long as the light that is made parallel light by the collimator lens20is radiated frontward.

Second Embodiment

Next, a vehicle lighting apparatus101of a second embodiment will be described with reference toFIG. 4. The vehicle lighting apparatus101of the second embodiment is mainly distinguished in that the vehicle lighting apparatus101includes an image light formation device150compared to the embodiment described above. The same component as that of the embodiment described above is given by the same reference numeral and description thereof will be omitted.

The vehicle lighting apparatus101includes the image light formation device150that forms image light in addition to the light radiation device10, the condenser lens (first optical system)30and the cover member40. The image light formation device150modulates light and forms image light. In the present embodiment, the image light formation device150is a transmission-type liquid crystal panel that forms image light when light passes through the image light formation device150. However, the image light formation device150may be a reflection-type liquid crystal panel or may be a DMD (Digital Mirror Device) in which a plurality of pivotable micromirrors are arranged in an array (matrix) and which forms image light when reflecting light. It is possible to allow the light that is incident on the condensing optical system to become image light by arranging the image light formation device150in a route from the light source main body12to the condenser lens30, and a light distribution pattern radiated frontward can be changed over time. That is, according to this configuration, the vehicle lighting apparatus can perform an ADB (Adaptive Driving Beam) control.

Hereinafter, in the description of the present embodiment, the image light formation device is referred to as a liquid crystal panel150.

The liquid crystal panel150is arranged between the light radiation device10and the condenser lens30. That is, the image light is formed by allowing part of the light that is made parallel light by the light radiation device10to pass through the liquid crystal panel150and shielding another part of the light. Since it is possible to make the light that passes through the liquid crystal panel150to be parallel light by arranging the liquid crystal panel150between the light radiation device10and the condenser lens30, it is possible to form clearer image light. That is, according to the present embodiment, it is possible to form a clearer light distribution pattern by forming the image light by the liquid crystal panel150using the parallel light radiated from the light radiation device10.

Further, a liquid crystal panel that diffuses the passing light may be used as the liquid crystal panel150. The diffused light is not condensed to the frontward condensing point30aby the condenser lens30.

Accordingly, the diffused light does not easily pass through the opening41of the cover member40, and it is possible to make the light distribution pattern radiated frontward clear.

The liquid crystal panel150is arranged to be orthogonal to the optical axis AX30of the condenser lens30at the rearward condensing point30bof the condenser lens30. By arranging the liquid crystal panel150at the rearward condensing point30b, even in a case where non-parallel light is included in the light radiated from the light radiation device10, it is possible to form a clear light distribution pattern.

In general, the liquid crystal element used in the liquid crystal panel is known to have a transmissive performance changed depending on an incident angle of light. That is, the liquid crystal element has a property in which the liquid crystal element has the highest contrast (light-dark transmissivity ratio) with respect to the light from a specified angle (for example, a direction orthogonal to the liquid crystal panel), and the contrast is decreased as the angle is deviated from the specified angle. Therefore, when the light that is incident on the liquid crystal element has an angular distribution, the light-dark transmissivity ratio of the entire image light may be also decreased in accordance with a decrease in contrast of a region in which the light most deviated from the specified angle is incident.

According to the present embodiment, by arranging the liquid crystal panel150to be orthogonal to the parallel light, it is possible to use only the light having the incident angle with the highest contrast of the liquid crystal panel150, and it is possible to increase the light-dark transmissivity ratio of the image light. That is, according to the present embodiment, it is possible to provide the vehicle lighting apparatus101that forms a clear light distribution pattern.

In this way, the liquid crystal panel150exhibits a high performance when parallel light is incident on the liquid crystal panel150. Accordingly, the vehicle lighting apparatus101of the present embodiment is most effective when the liquid crystal panel150is used as the image light formation device.

According to the present embodiment, in addition to the above effect obtained by providing the liquid crystal panel150, it is possible to provide the same effects as those of the first embodiment.

EXAMPLES

Hereinafter, the effects of the present invention will be made clearer by the examples. The present invention is not limited to the following examples and can be appropriately modified and implemented without departing from the scope of the invention.

[Light Distribution Pattern Corresponding to First Embodiment]

FIG. 5shows a simulation result of a light distribution pattern P1in the vehicle lighting apparatus1of the first embodiment described above with respect to a virtual vertical screen facing the vehicle lighting apparatus1. In the simulation, an effective lens height of the condenser lens30is 30 mm, and a dimension in the vertical direction of the cover member40is 10 mm.

As shown inFIG. 5, in the light distribution pattern P1, a high illuminance band is provided at a center, the width in the horizontal direction is wider than that in the vertical direction, and the light distribution pattern P1is formed in a shape preferable as a light distribution pattern of the vehicle lighting apparatus. Further, when a total light flux of the light distribution pattern P1is confirmed, efficiency of utilization of the light is 50% or more even in a case where light loss in an outer lens (omitted inFIG. 1toFIG. 3) is considered. Therefore, according to the vehicle lighting apparatus1of the first embodiment, it is possible to form a preferable light distribution pattern P1with high efficiency and enhanced design properties. The efficiency of utilization of the light is an index that represents a ratio of a light flux radiated frontward to the total light flux radiated from the light source main body using a percentage.

[Light Distribution Pattern Corresponding to Second Embodiment]

FIG. 6shows a simulation result of the light distribution pattern P101in the vehicle lighting apparatus101of the second embodiment described above with respect to a virtual vertical screen facing the vehicle lighting apparatus101.

In the simulation, the liquid crystal panel150shields some of the passing light (a right upper region of the center in the light distribution pattern P101).

As shown inFIG. 5, the light distribution pattern P101corresponding to the second embodiment provides the same effects as those of the light distribution pattern P1corresponding to the first embodiment and is able to form a region to which the light is not partially radiated. That is, according to the light distribution pattern P101corresponding to the second embodiment, it is possible to clearly perform the ADB control of partially masking the radiation of light.

While various embodiments of the present invention have been described, the configurations, the combinations of the configurations and the like in the embodiments are examples, and additions, omissions, and substitutions of the configurations and other modifications can be made without departing from the scope of the invention. Further, the present invention is not limited by the embodiment.

DESCRIPTION OF THE REFERENCE SYMBOLS