Patent Description:
In the related art, as a vehicle lighting apparatus, vehicle lighting apparatuses that use the contrast of light and display an image indicating information on a road surface have been proposed. In <CIT>, information formed by a reflection-type digital light deflection device is displayed on a road surface.

<CIT> discloses a headlight device which has a projection function, and which is provided with: a light source device; an illumination optical system; a video display element; a video-signal control unit; and a projection optical system. The projection optical system is configured so as to have, provided therein from the video display element side, a coaxial lens system having refractive action, a free-form surface lens, and a free-form surface mirror. As a result, video which can be readily seen by a driver and pedestrians can be projected onto a road.

<CIT> discloses a vehicle light fixture that can be fitted to the front end of a vehicle and comprises a compound lens body which is a light guide obtained by molding a translucent resin into an approximately plate shape, a planar light-emitting unit that generates illuminating light, and an optical system which converts the planar light from the light-emitting unit into linear light, and has the light enter the front surface of the light guide, and a diffraction lens which is formed on the rear surface of the light guide upon which linear converted light is incident, and which is for condensing the linear converted light. Light condensed by the lens means is shone onto the road surface in front of the vehicle from the front-facing surface of the wave guide.

<CIT> discloses a method for determining the humidity and temperature of atmospheric air at selected distances along a field of view by passive IR spectrometry. An IR spectrometer is provided. A plurality of IR power densities values received by the spectrometer along the field of view at a plurality of discrete, selected IR wavelengths are measured. A set of equations which equate the measured IR power density to functions of temperature and humidity at the selected wavelengths is provided. From the set of equations the temperature and humidity of the atmospheric air along the field of view at selected range segments along the field of view are calculated.

<CIT> discloses a truck having a warning device which is provided with a projector for projecting the pictorial reference symbol in a floor or a wall surface of the truck main portion. The warning device operates a noiseless drive for the security of the operating range, when pictorial warning symbol is projected in the floor or wall surface of the truck main portion. The projector projects the pictorial reference symbol along the reverse travel direction of the truck main portion. A light source is arranged inside of a designed housing.

<CIT> discloses an information display device for displaying information that allows an attention target to be visually recognized. The information display device includes an image generation unit that identifies an attention target and generates a shadow image with a position of the target as a base point; and a light driving unit that projects the shadow image when a light illuminates.

However, in the vehicle lighting apparatus of the related art, when a variety of images are displayed on a road surface, since an imaging surface is not matched with the road surface, the distance between the image on the road surface and a lens at a near side of the image is greatly different from the distance between the image on the road surface and the lens at a far side of the image. Therefore, there is a problem in that a defocus occurs in which an image is formed at some position, but an image is not formed at frontward and rearward positions of the some position.

An object of an aspect of the present invention is to provide a vehicle lighting apparatus that is capable of clearly displaying an image on a road surface.

According to the present invention, a vehicle lighting apparatus is provided as set forth in claim <NUM>. Preferred embodiments of the present invention may be gathered from the dependent claims.

According to the configuration, even when the reflection surface is a convex curved surface or is a concave curved surface, compared to a case in which light is reflected at a region that reflects light toward a far position from the vehicle, light is reflected at a region that reflects light toward a near position from the vehicle, the distance between a region where light is reflected on the reflection surface and a region where an image is formed on the road surface, which is an imaging surface, is shortened, and it is possible to prevent a defocus of the imaged light distribution pattern. Accordingly, it is possible to provide a vehicle lighting apparatus that is capable of clearly displaying an image on a road surface.

The vehicle lighting apparatus of the claimed invention includes: a plurality of reflection parts, each of which reflects light toward a corresponding region of a plurality of regions on the road surface, each region having a different distance from the vehicle; and a switch part that switches and arranges one of the plurality of reflection parts to a light-receiving position of light emitted from the light-focusing optical system.

According to the configuration, the plurality of reflection parts, each of which reflects light toward a corresponding region of a plurality of regions, each region having a different distance from the vehicle, are switched by the switch part and are arranged at the light-receiving position, and therefore, it is possible to clearly display an image at a position having a different distance on the road surface by each reflection part. Therefore, by switching the reflection part in accordance with an application, it is possible to clearly display an image at a position suitable for each application.

The vehicle lighting apparatus described above may include a return mirror that reflects light emitted from the light-focusing optical system toward the reflection part that is arranged in the light-receiving position.

According to the configuration, since the light from the light-focusing optical system is reflected toward the reflection part that is arranged in the light-receiving position by the return mirror, it is not necessary to arrange the light-focusing optical system in a direction that faces the reflection part, and it is possible to decrease the thickness in the vertical direction of the light-focusing optical system and decrease the size in the vertical direction of the vehicle lighting apparatus.

In the vehicle lighting apparatus described above, each reflection surface may have a concave shape and may be arranged on a downstream side of an intermediate image along a transmission path of light focused by the light-focusing optical system.

According to the configuration, a reflection surface having a concave shape is employed, and it is possible to display a clear image on the road surface.

In the vehicle lighting apparatus described above, each reflection surface may have a convex shape and may be arranged on an upstream side of an intermediate image along a transmission path of light focused by the light-focusing optical system.

According to the configuration, a reflection surface having a convex shape is employed, and it is possible to display a clear image on the road surface.

The vehicle lighting apparatus of the claimed invention includes: an object detection part that detects an object which is present at a frontward position of the vehicle; and a control part that controls the image generated by the image generation part and a switch mode of the plurality of reflection parts based on a detection condition of the object detection part.

According to the configuration, it is possible to change the direction and position of the display in accordance with frontward circumstances of the vehicle, and therefore, the information of the image displayed on the road surface can be easily understood by a person in the vicinity of the vehicle.

The vehicle lighting apparatus described above may employ a configuration in which the control part changes any one of or both of an orientation of the image and a projection position of the image based on the detection condition of the object detection part.

According to the configuration, it is possible to project necessary information on the road surface such that the information is easily seen in accordance with frontward circumstances of the vehicle.

According to the vehicle lighting apparatus of the aspect of the present invention, it is possible to provide a vehicle lighting apparatus that is capable of clearly displaying an image on a road surface.

Part (a) of <FIG> is a perspective view showing a state in which a road surface is irradiated using a short-distance reflection part in the vehicle lighting apparatus according to the first embodiment. Part (b) of <FIG> is a plan view showing the state in which the road surface is irradiated using the short-distance reflection part in the vehicle lighting apparatus according to the first embodiment.

Part (a) of <FIG> is a perspective view showing a state in which a road surface is irradiated using a middle-distance reflection part in the vehicle lighting apparatus according to the first embodiment. Part (b) of <FIG> is a plan view showing the state in which the road surface is irradiated using the middle-distance reflection part in the vehicle lighting apparatus according to the first embodiment.

Part (a) of <FIG> is a perspective view showing a state in which a road surface is irradiated using a long-distance reflection part in the vehicle lighting apparatus according to the first embodiment. Part (b) of <FIG> is a plan view showing the state in which the road surface is irradiated using the long-distance reflection part in the vehicle lighting apparatus according to the first embodiment.

<FIG> is a schematic view of a projection module of a vehicle lighting apparatus according to a modified example of the first embodiment.

<FIG> is a schematic view of a projection module of a vehicle lighting apparatus according to a second embodiment.

Hereinafter, a vehicle lighting apparatus according to an embodiment is described with reference to the drawings.

In the drawings used in the following description, there may be a case in which, for ease of understanding the features, the featured part is shown to be enlarged, and the dimension ratio of each component or the like is not always the same as an actual one.

<FIG> is a schematic view of a vehicle lighting apparatus <NUM> according to a first embodiment.

The vehicle lighting apparatus <NUM> of the present embodiment is an apparatus that emits light, which has an image, diagonally toward a road surface from a vehicle.

As shown in <FIG>, the vehicle lighting apparatus <NUM> includes a projection module <NUM> that illuminates a frontward direction of a vehicle, a control device <NUM> that controls the projection module <NUM>, and an imaging device <NUM> that detects frontward circumstances and that transmits the frontward circumstances to the control device <NUM>.

<FIG> is a schematic view showing the projection module <NUM> of the present embodiment.

The projection module <NUM> of the present embodiment includes a light source <NUM>, an incident optical system <NUM>, an image generation part <NUM>, and a projection optical system <NUM>.

The light source <NUM> emits visible light. A light-emitting diode (LED) light source or a laser light source can be employed as the light source <NUM>.

The incident optical system <NUM> is formed of one or more lenses and the like that focus light from the light source <NUM> and irradiate a reflection control surface of the image generation part <NUM>.

The image generation part <NUM> modulates light emitted from the light source <NUM> and generates an image. In the present embodiment, the image generation part <NUM> is formed of a reflection-type digital light deflection device (DMD, Digital Mirror Device). The image generation part <NUM> formed of the reflection-type digital light deflection device has the reflection control surface configured by arranging a plurality of mirror elements capable of being slanted.

A slant angle of each of the plurality of mirror elements of the image generation part <NUM> is controlled to a reflection side or a light shield side by a signal from the control device <NUM>. The image generation part <NUM> generates a reflection pattern (image) <NUM> having an arbitrary shape by reflection light of the plurality of mirror elements slanted to the reflection side. In the example shown in <FIG>, the image generation part <NUM> generates a reflection pattern <NUM> having an arrow shape.

A light shield member <NUM> that blocks light from each mirror element slanted to the light shield side is provided on the vehicle lighting apparatus <NUM>.

The projection optical system <NUM> illuminates a frontward direction of the vehicle with the reflection pattern <NUM> generated by the image generation part <NUM> as a light distribution pattern <NUM>. The projection optical system <NUM> includes a light-focusing optical system <NUM>, a return mirror <NUM>, and a reflection device <NUM>.

The light-focusing optical system <NUM> is formed of one or more lenses and the like. The light-focusing optical system <NUM> illuminates a reflection part <NUM> of the reflection device <NUM> with the reflection pattern <NUM> generated by the image generation part <NUM> via the return mirror <NUM>. The light-focusing optical system <NUM> focuses the reflection pattern <NUM> emitted from the image generation part <NUM> and forms an intermediate image <NUM>.

The return mirror <NUM> is a mirror that reflects light from the light-focusing optical system <NUM> toward the reflection part <NUM>.

<FIG> is a perspective view of the reflection device <NUM>.

The reflection device <NUM> has a plurality of (three in the present embodiment) reflection parts <NUM> and a switch part <NUM>. The reflection part <NUM> reflects light focused by the light-focusing optical system <NUM> toward a road surface <NUM>. The switch part <NUM> has a shaft part 46a and a drive part 46b that drives the shaft part 46a to be rotated around the shaft.

A plurality of reflection parts <NUM> are fixed to the shaft part 46a at even intervals along a circumferential direction with respect to the shaft center of the shaft part 46a. The switch part <NUM> switches and arranges one of the plurality of reflection parts <NUM> to a light-receiving position at which light emitted from the light-focusing optical system <NUM> is received in accordance with the rotation of the shaft part 46a by the drive part 46b.

In <FIG> and <FIG>, only one reflection part <NUM> of the plurality of reflection parts <NUM> that is arranged at the light-receiving position is shown.

The reflection part <NUM> is a concave reflector used for an expansion projection. The reflection part <NUM> has a reflection surface 45a. The reflection part <NUM> reflects light focused by the light-focusing optical system <NUM> at the reflection surface 45a and projects reflected light onto a predetermined region of the road surface <NUM>. The reflection surface 45a has a concave shape formed of an aspherical free-form surface.

The reflection surface 45a is arranged at a latter part of the intermediate image <NUM> formed by the light-focusing optical system <NUM>. Accordingly, light forms an image at a former part side of the reflection surface 45a, is incident on the reflection surface 45a having a concave shape while extending in a diffusion direction, and is reflected by the reflection surface 45a to thereby be focused again.

The "former part" and the "latter part" mean a sequence relationship (that is, an upstream side and a downstream side in an optical path) along a transmission path of light and do not mean the arrangement of each part in the vehicle lighting apparatus <NUM>.

A projection direction frontward region 45b of the reflection surface 45a reflects light toward the road surface <NUM> on a vehicle near side. A projection direction rearward region 45c of the reflection surface 45a reflects light toward the road surface <NUM> on a vehicle far side. The reflection surface 45a is formed to have a curvature that is continuously changed from the projection direction rearward region 45c toward the projection direction frontward region 45b in accordance with the distance to a projection target (a near position from the vehicle to a far position from the vehicle of the road surface <NUM>). That is, the reflection surface 45a has a curvature that is gradually increased from a projection direction rearward side toward a projection direction frontward side. Thereby, compared to a case in which light is reflected at the projection direction rearward region 45c that reflects light toward a far position from the vehicle, light is reflected at the projection direction frontward region 45b that reflects light toward a near position from the vehicle, the distance between a region where light is reflected on the reflection surface 45a and a region where an image is formed on the road surface <NUM>, which is an imaging surface, is shortened, and it is possible to prevent a defocus of the imaged light distribution pattern <NUM>.

As shown in <FIG>, the reflection device <NUM> of the present embodiment has a short-distance reflection part 45X, a middle-distance reflection part 45Y, and a long-distance reflection part 45Z. The reflection surface 45a of each of the reflection parts 45X, 45Y, and 45Z is set so as to reflect light toward a corresponding region of a plurality of regions on the road surface <NUM>, each region having a different distance from the vehicle. Each reflection surface 45a of the short-distance reflection part 45X, the middle-distance reflection part 45Y, and the long-distance reflection part 45Z is formed such that as the reflection surface 45a has a shorter distance to the position which is irradiated with reflection light, the reflection surface 45a has a curved surface having a larger average curvature. Part (a) and part (b) of <FIG> show a state in which the road surface <NUM> is irradiated with the light distribution pattern <NUM> using the short-distance reflection part 45X. Part (a) and part (b) of <FIG> show a state in which the road surface <NUM> is irradiated with the light distribution pattern <NUM> using the middle-distance reflection part 45Y. Part (a) and part (b) of <FIG> show a state in which the road surface <NUM> is irradiated with the light distribution pattern <NUM> using the long-distance reflection part 45Z.

With reference back to <FIG>, the configuration of the vehicle lighting apparatus <NUM> is described.

The imaging device <NUM> that controls the projection module <NUM> has an object detection part <NUM> that detects, by capturing an image of a frontward direction of a vehicle and processing the image, an object that is present in the frontward direction of the vehicle and transmits a detection signal to a control part <NUM>.

On the other hand, the control device <NUM> has a configuration that is capable of performing a process of controlling a slant mode of the mirror element of the image generation part <NUM> to thereby form an image and, at the same time, arranging a reflection part <NUM> selected from a plurality of reflection parts <NUM> by the switch part <NUM> to a light-receiving position from the light-focusing optical system <NUM>.

The control device <NUM> has a memory <NUM> in which control information of a variety of images and the like are set in advance, the control part <NUM> that generates a control signal based on information from the memory <NUM> and a signal from the imaging device <NUM>, and a drive part <NUM> that drives part of or all of the light source <NUM>, the image generation part <NUM>, and the reflection device <NUM> based on the control signal.

The control part <NUM> controls the image by the slant mode of each mirror element of the image generation part <NUM> via the drive part <NUM> and controls a switch mode in which any of the reflection parts <NUM> of the reflection device <NUM> is arranged at the light-receiving position based on a detection condition of the object detection part <NUM> or an input operation of a driver and the like.

In such a vehicle lighting apparatus <NUM>, as shown in part (a) and part (b) of <FIG>, when the presence of a pedestrian <NUM> at a road shoulder in the vicinity of the frontward position of the vehicle is detected by the imaging device <NUM>, the short-distance reflection part 45X is switched to and arranged at the light-receiving position in the reflection device <NUM>. In the image generation part <NUM>, a transversely oriented image that is adapted for the pedestrian <NUM> at the road shoulder is generated, and light from the light source <NUM> is emitted from the light-focusing optical system <NUM>. Thereby, it is possible to display an image having an appropriate orientation when seen by the pedestrian <NUM>, on the road surface <NUM>.

For example, when indicating that right of way is given to a pedestrian <NUM> who will cross the road, it is possible to display an image in a state where characters are rotated such that the display is appropriate when seen by the pedestrian <NUM> at the road shoulder.

As shown in part (a) and part (b) of <FIG>, when a road surface display is requested by the input operation of the driver and the like, the middle-distance reflection part 45Y is switched to and arranged at the light-receiving position in the reflection device <NUM>. In the image generation part <NUM>, an image that is directed in the near side and that is adapted for the driver and the like with respect to information requested by the driver and the like is generated, and light from the light source <NUM> is emitted from the light-focusing optical system <NUM>. Thereby, it is possible to display an image having an appropriate orientation when seen by the driver, on the road surface <NUM>.

For example, information such as a legal speed, route guidance, and warning of a frontward obstacle in an appropriate direction when seen by the driver can be displayed on the road surface <NUM> for the driver at a middle-distance position of the road surface <NUM>.

As shown in part (a) and part (b) of <FIG>, when the presence of an oncoming vehicle <NUM> is detected by the imaging device <NUM>, the long-distance reflection part 45Z is switched to and arranged at the light-receiving position in the reflection device <NUM>. In the image generation part <NUM>, an inversely oriented image that is adapted for the driver of the oncoming vehicle <NUM> is generated, and light from the light source <NUM> is emitted from the light-focusing optical system <NUM>. Thereby, it is possible to display an image having an appropriate orientation when seen by the driver of the oncoming vehicle <NUM>, on the road surface <NUM>.

For example, when notifying a far oncoming vehicle <NUM> of a pedestrian <NUM> who is crossing the road and the like, it is possible to display an image in a state where characters are inverted such that the display is appropriate when seen from the oncoming vehicle <NUM>.

According to the vehicle lighting apparatus <NUM> of the present embodiment, the reflection part <NUM> that reflects light having an image as the reflection pattern <NUM> toward the road surface <NUM> is formed to have a curvature that is continuously changed in accordance with the distance to a projection target (a near position from the vehicle to a far position from the vehicle of the road surface). Thereby, it is possible to clearly display an image on the road surface <NUM>, and it is possible to draw a high-quality image without a defocus.

According to the vehicle lighting apparatus <NUM> of the claimed invention, the plurality of reflection parts <NUM>, each of which reflects light toward a corresponding region of a plurality of regions, each region having a different distance from the vehicle, can be switched by the switch part <NUM> and can be arranged at the light-receiving position. By switching the reflection part <NUM> in accordance with an application, it is possible to provide a vehicle lighting apparatus <NUM> that clearly displays an image at a position suitable for each application. Further, when emitting reflection light to a long distance, it is possible to prevent the light from diffusing and to prevent the illumination intensity from being decreased.

The vehicle lighting apparatus <NUM> of the claimed invention includes the object detection part <NUM> and the control part <NUM> that controls the image generated by the image generation part <NUM> land a switch mode of the plurality of reflection parts <NUM> based on a detection condition of the object detection part <NUM>. Therefore, it is possible to change the orientation and position of the image in accordance with frontward circumstances of the vehicle, and the information of the image displayed on the road surface can be easily understood by a person in the vicinity of the vehicle.

In the vehicle lighting apparatus <NUM> of the present embodiment, the control part <NUM> changes the image generated by the image generation part <NUM> and changes the orientation of the image in accordance with frontward circumstances of the vehicle. Further, in the vehicle lighting apparatus <NUM> of the present embodiment, the control part <NUM> selects any of the short-distance reflection part 45X, the middle-distance reflection part 45Y, and the long-distance reflection part 45Z and thereby changes the projection position of the image in accordance with frontward circumstances of the vehicle. Thereby, it is possible to project necessary information on the road surface such that the information is easily seen in accordance with frontward circumstances of the vehicle.

The first embodiment described above can be changed without departing from the scope of the invention. For example, the combination of the selection from the short-distance reflection part 45X, the middle-distance reflection part 45Y, and the long-distance reflection part 45Z and the orientation of the image is not limited. For example, it is possible to display a transversely oriented image on the road surface <NUM> by the long-distance reflection part 45Z.

According to the vehicle lighting apparatus <NUM> of the present embodiment, since the light from the light-focusing optical system <NUM> is reflected toward the reflection part <NUM> by the return mirror <NUM>, it is not necessary to arrange the light-focusing optical system <NUM> in a direction that faces the reflection part <NUM>. Thereby, it is possible to decrease the thickness in the vertical direction of the light-focusing optical system <NUM> and decrease the size in the vertical direction of the vehicle lighting apparatus <NUM>. Thereby, it is possible to easily downsize a housing of the vehicle lighting apparatus <NUM>.

The return mirror <NUM> may be omitted. <FIG> shows a projection module 11A of a modified example that is adoptable in the present embodiment. The projection module 11A is different in that the projection module 11A does not include the return mirror <NUM> compared to the embodiment described above. According to the present modified example, it is possible to reduce the number of components and to provide a low-cost vehicle lighting apparatus <NUM>.

<FIG> is a schematic view showing a projection module <NUM> of a vehicle lighting apparatus <NUM> of a second embodiment.

The same reference numerals are given to constituents having the same configuration as those of the embodiment described above, and description of the constituents is omitted.

The vehicle lighting apparatus <NUM> of the present embodiment includes a reflection device <NUM> having a reflection part <NUM>. The reflection part <NUM> has a reflection surface 145a having a convex shape. The reflection surface 145a is arranged on an upstream side of an intermediate image <NUM> along a transmission path focused by the light-focusing optical system <NUM>. Accordingly, light is incident on the reflection surface 145a having a convex shape while being focused, the distance between the reflection surface and the imaging surface is adjusted by the reflection surface 145a, and the light is reflected in the frontward direction.

The reflection surface 145a having a convex shape has a curvature that is gradually increased from a projection direction rearward side toward a projection direction frontward side.

A projection direction frontward region 145b of the reflection surface 145a reflects light toward the road surface <NUM> on a vehicle far side. A projection direction rearward region 145c of the reflection surface 145a reflects light toward the road surface <NUM> on a vehicle near side. The reflection surface 145a is formed to have a curvature that is continuously changed from the projection direction rearward region 145c toward the projection direction frontward region 145b in accordance with the distance to a projection target (a near position from the vehicle to a far position from the vehicle of the road surface <NUM>). That is, the reflection surface 145a has a curvature that is gradually increased from a projection direction rearward side toward a projection direction frontward side. Thereby, compared to a case in which light is reflected at the projection direction frontward region 145b that reflects light toward a far position from the vehicle, light is reflected at the projection direction rearward region 145c that reflects light toward a near position from the vehicle, the distance between a region where light is reflected on the reflection surface 145a and a region where an image is formed on the road surface <NUM>, which is an imaging surface, is shortened, and it is possible to prevent a defocus of the imaged light distribution pattern <NUM>.

In any of the embodiments described above, the vehicle lighting apparatus <NUM> as described above may be provided separately from a headlight or may be incorporated in a headlight.

Claim 1:
A vehicle lighting apparatus (<NUM>) that is adapted to emit light diagonally toward a road surface (<NUM>) from a vehicle, the vehicle lighting apparatus (<NUM>) comprising:
a light source (<NUM>);
an image generation part (<NUM>) that is configured to modulate light emitted from the light source (<NUM>) and to generate an image;
a light-focusing optical system (<NUM>) that is adapted to focus light having the image generated by the image generation part (<NUM>);
a plurality of reflection parts (<NUM>), each reflection part (<NUM>) being adapted to reflect light focused by the light-focusing optical system (<NUM>) and to project reflected light toward the road surface (<NUM>), wherein each of the plurality of reflection parts (<NUM>) is adapted to reflect light toward a corresponding region of a plurality of regions on the road surface (<NUM>), each region having a different distance from the vehicle, wherein each reflection part (<NUM>) has a reflection surface (45a) having a curvature that is gradually increased continuously throughout the entire reflection surface from a projection direction rearward side toward a projection direction frontward side;
a switch part (<NUM>) that is configured to switch and arrange one of the plurality of reflection parts (<NUM>) to a light-receiving position of light emitted from the light-focusing optical system (<NUM>);
an object detection part (<NUM>) that is adapted to detect an object which is present at a frontward position of the vehicle; and
a control part (<NUM>) that is configured to control the image generated by the image generation part (<NUM>) and a switch mode of the plurality of reflection parts (<NUM>) based on a detection condition of the object detection part (<NUM>).