JP6939315B2 - Lighting device - Google Patents

Description

The present disclosure relates to a lighting device that illuminates the inside of a tunnel.

Conventionally, the lighting in the tunnel through which vehicles and the like pass has been devised in various ways for the purpose of improving the safety in the tunnel. For example, in Patent Document 1, by devising the direction and shape of the light distribution in the tunnel lighting equipment, the back surface of the preceding vehicle is brightly illuminated, and the lighting environment is improved especially in a tunnel in an urban area with heavy traffic. Is disclosed.

Japanese Patent No. 3296129

By the way, when a vehicle enters the tunnel from a bright environment illuminated by sunlight or the like, the inside of the tunnel may be uniformly seen as black, and it may be difficult to visually recognize the situation inside the tunnel. This is because even if the inside of the tunnel is illuminated, the brightness inside the tunnel is much smaller than the brightness outside the tunnel due to sunlight. When the human eye adapts to the brightness outside the tunnel due to sunlight, it cannot recognize the difference in brightness of the road surface, wall surface, etc. inside the tunnel, which is much darker than that. Therefore, the inside of the tunnel is uniformly seen as black, and the tunnel looks like a black hole (see FIG. 21). The so-called black frame phenomenon, in which the ceiling and road surface look like a black frame, can occur. In this case, when entering the tunnel, the driver cannot grasp the inside of the tunnel until the eyes adjust to the brightness in the tunnel, which may cause a traffic accident.

Conversely, when going out of the tunnel from inside the tunnel, the outside of the tunnel, which is much brighter than the inside of the tunnel, looks dazzling to the eyes adapted to the brightness inside the tunnel. As a result, a so-called white hole phenomenon may occur in which the outside of the tunnel and the vicinity of the exit inside the tunnel appear uniformly white.

In order to suppress the occurrence of such a black hole phenomenon, a black frame phenomenon, or a white hole phenomenon, conventionally, by arranging lighting mainly in the vicinity of the entrance / exit in the tunnel, the vicinity of the entrance / exit in the tunnel is brightened. Lighting is also done.

However, even with such lighting, the effect is not sufficient, and further improvement of lighting in the tunnel is required.

The present invention has been made in consideration of the above points, and an object of the present invention is to realize effective lighting in a tunnel.

The lighting device according to the present invention
A lighting device that illuminates the inside of a tunnel.
With a coherent light source,
A shaping optical system that shapes the coherent light emitted from the coherent light source,
It includes a diffractive optical element that diffracts the coherent light shaped by the shaping optical system and directs it to an illuminated region.

In the lighting device according to the present invention
The shaping optical system may increase the cross-sectional area of the luminous flux of the coherent light.

In the lighting device according to the present invention
The diffractive optical element includes a plurality of element diffractive optical elements.
At least two element diffractive optical elements included in the plurality of element diffractive optical elements may have different diffraction characteristics.

In the lighting device according to the present invention
The at least two element diffractive optics may illuminate the same area.

In the lighting device according to the present invention
The at least two element diffractive optics may illuminate different regions.

In the lighting device according to the present invention
The at least two element diffractive optical elements include a plane of incident light having a maximum incident angle from the diffractive optical element to the illuminated region and parallel to the normal direction to the illuminated region, and the above. It may be arranged along a direction parallel to the intersection line with the virtual surface on which the diffractive optical element is located.

In the lighting device according to the present invention
The illuminated area may include a lane dividing lane marking and may be located over a predetermined distance from the entrance or exit of the tunnel into the tunnel.

In the lighting device according to the present invention
The illumination of the illuminated area may decrease from the entrance or exit of the tunnel toward the inside of the tunnel.

In the lighting device according to the present invention
The illuminated area is located on the ceiling and / or side wall of the tunnel.
The illuminated area may display information.

According to the present invention, effective lighting in a tunnel can be realized.

FIG. 1 is a diagram for explaining one embodiment according to the present disclosure, and is a perspective view showing a lighting device. FIG. 2 is a diagram showing the positional relationship between the diffractive optical element of the illumination device of FIG. 1 and an example of the illuminated area in an xyz coordinate system. FIG. 3 is a diagram showing the positional relationship between the diffractive optical element of FIG. 2 and the illuminated region in a θV−θH angular coordinate system. FIG. 4 is a diagram showing the positional relationship between the diffractive optical element of FIG. 2 and the illuminated area in the yz coordinate system. FIG. 5 is a diagram showing the positional relationship between the diffractive optical element of FIG. 2 and the illuminated region in the xz coordinate system. FIG. 6 is a flowchart showing an example of the processing procedure of the iterative Fourier transform method. FIG. 7 is a view corresponding to FIG. 1 and is a perspective view showing an example in which the diffractive optical element includes a plurality of element diffractive optical elements. FIG. 8 is a diagram corresponding to FIG. 2, which shows the positional relationship between the diffractive optical element of the illumination device of FIG. 7 and another example of the illuminated region in the xyz coordinate system. FIG. 9 is a diagram corresponding to FIG. 3, which shows the positional relationship between the diffractive optical element of FIG. 8 and another example of the illuminated region in a θV−θH angular coordinate system. FIG. 10 is a diagram showing the positional relationship between the diffractive optical element and the illuminated region in the yz coordinate system, and is a diagram for explaining the deviation of the incident position of the diffracted light in the illuminated region. FIG. 11 is a diagram showing the positional relationship between the diffractive optical element and the illuminated region in the xz coordinate system, and is a diagram for explaining the deviation of the region illuminated by the diffracted light from each element diffractive optical element. .. FIG. 12 is a diagram showing the positional relationship between the diffractive optical element and the illuminated region in the yz coordinate system, and is for explaining an example in which the diffracted light from the element diffractive optical element illuminates a different region within the illuminated region. It is a figure of. FIG. 13 is a diagram corresponding to FIG. 1 and is a diagram showing a modified example of the lighting device. FIG. 14 is a diagram corresponding to FIG. 1 and is a diagram showing another modification of the lighting device. FIG. 15 is a diagram for explaining an application example of the lighting device. FIG. 16 is a diagram for explaining an application example of the lighting device. FIG. 17 is a diagram for explaining another application example of the lighting device. FIG. 18 is a diagram for explaining another application example of the lighting device. FIG. 19 is a diagram for explaining still another application example of the lighting device. FIG. 20 is a diagram for explaining an example of an installation location of the lighting device. FIG. 21 is a diagram for explaining the black hole phenomenon.

Hereinafter, an embodiment of the present disclosure will be described with reference to the drawings. In the drawings attached to the present specification, the scale, aspect ratio, etc. are appropriately changed from those of the actual product and exaggerated for the convenience of illustration and comprehension.

In addition, the terms such as "parallel", "orthogonal", and "same", and the values of length and angle, etc., which specify the shape and geometric conditions and their degrees as used in the present specification, are strictly referred to. It is interpreted to include the range in which similar functions can be expected, without being bound by any meaning.

FIG. 1 is a perspective view schematically showing the overall configuration of the lighting device 10. The lighting device 10 is a device that illuminates the illuminated area Z. As will be described later, the illuminated area Z is located at any location in the tunnel 1, for example, on the side wall portion 2, the ceiling portion 3, and the road 5 in the tunnel 1. The illuminated area Z may illuminate a specific area, or may display characters, figures, pictures, photographs, moving images, or a combination thereof. In the example shown in FIGS. 1 to 5, the illuminated area Z is a quadrangular area located far away from the lighting device 10 and having a longitudinal direction dl. The longitudinal direction dl of the illuminated area Z extends in the direction across the distance of the lighting device 10.

The lighting device 10 described here has been devised to illuminate a predetermined area with high accuracy, thereby effectively relaxing the restrictions on the installation location of the lighting device 10. Therefore, in the lighting device 10 described below, the position far away from the illuminated area and the incident angle of the illumination light with respect to the illuminated area Z are not strongly constrained by the position relative to the illuminated area Z. It can be installed even in a position where it becomes large.

Hereinafter, one embodiment will be described with reference to the illustrated specific examples.

As shown in FIG. 1, the lighting device 10 includes a coherent light source 20 that projects light and a diffracting optical element 40 that diffracts the light emitted from the coherent light source 20. As shown in FIGS. 1 and 2, the lighting device 10 has a shaping optical system 30 between the coherent light source 20 and the diffractive optical element 40 along the optical path of the light emitted from the coherent light source 20. .. In the illustrated example, the light emitted from the coherent light source 20 goes to the illuminated region Z through the shaping optical system 30 and the diffractive optical element 40. Hereinafter, each component of the lighting device 10 will be described in order.

As the coherent light source 20, various types of light sources can be used. Typically, a laser light source can be used as the coherent light source 20, and a semiconductor laser light source can be exemplified as a specific example. In the example shown in FIG. 1, the coherent light source 20 includes a single light source. Therefore, in the illustrated example, the illuminated region Z is illuminated with a color corresponding to the wavelength range of the coherent light oscillated from the coherent light source 20.

However, the coherent light source 20 includes a plurality of coherent light sources 20 so that the illuminated area Z can be illuminated with a desired color, and after the light emitted from each coherent light source 20 is superimposed, the shaping optical system 30 and the diffraction are performed. It may be directed toward the optical element 40. Further, as in the modified examples shown in FIGS. 13 and 14, the shaping optical systems 30A, 30B, 30C and the diffractive optical element 40A provided so that the light emitted from each coherent light source 20 corresponds to the coherent light source 20 is provided. , 40B, 40C, and then overlapped on the illuminated area Z. In such an example, the plurality of coherent light sources 20 included in the coherent light source 20 may not only emit light in different wavelength ranges but also emit light in the same wavelength range. By including the coherent light source 20 in which the coherent light source 20 emits light in the same wavelength range, it is possible to brightly illuminate the illuminated region Z.

In the examples shown in FIGS. 13 and 14, the coherent light source 20 has a first coherent light source 20A, a second coherent light source 20B, and a third coherent light source 20C. When the coherent light source 20 includes a plurality of coherent light sources, the illumination of the illuminated area Z is performed by adjusting the emission of the coherent light from each coherent light source 20, more specifically, the start / stop and the emission amount of the emission. The color and the brightness of the illuminated area Z may be controlled.

Next, the shaping optical system 30 will be described. The shaping optical system 30 shapes the coherent light emitted from the coherent light source 20. In other words, the shaping optical system 30 shapes the shape of the cross section orthogonal to the optical axis of the coherent light and the three-dimensional shape of the luminous flux of the coherent light. Typically, the shaping optical system 30 increases the luminous flux cross-sectional area of the coherent light in a cross section orthogonal to the optical axis of the coherent light. That is, the optical path area la2 of the coherent light after being emitted from the shaping optical system 30 is larger than the optical path area la1 of the coherent light before being incident on the shaping optical system 30.

In the illustrated example, the shaping optical system 30 shapes the coherent light emitted from the coherent light source 20 into a widened parallel light flux. That is, the shaping optical system 30 functions as a collimating optical system. As shown in FIG. 1, the orthopedic optical system 30 has a first lens 31 and a second lens 32 in the order along the optical path of coherent light. The first lens 31 shapes the coherent light emitted from the coherent light source 20 into a divergent luminous flux. The second lens 32 reshapes the divergent luminous flux generated by the first lens 31 into a parallel luminous flux. That is, the second lens 32 functions as a collimating lens.

Next, the diffractive optical element 40 will be described. The diffractive optical element 40 is an element that exerts a diffracting action on the light emitted from the coherent light source 20. The diffractive optical element 40 diffracts the light from the coherent light source 20 and directs it to the illuminated region Z. Therefore, the illuminated area Z is illuminated by the diffracted light of the diffractive optical element 40 (see FIG. 1).

The diffractive optical element 40 diffracts the coherent light shaped by the shaping optical system 30 within a predetermined diffusion angle range in the angular space to illuminate the illuminated region Z at a predetermined position and size. The diffractive optical element 40 is typically a hologram element. As will be described later, by using the hologram element as the diffraction optical element 40, it becomes easy to design the diffraction characteristics of the hologram element, and the hologram element illuminates the entire area of the illuminated region Z having a predetermined position, size and shape. The design of is also relatively easy.

The illuminated area Z is provided at a predetermined position with respect to the diffractive optical element 40 in a predetermined size and shape. The position, size and shape of the illuminated region Z depend on the diffraction characteristics of the diffractive optical element 40, and the position, size and shape of the illuminated region Z can be arbitrarily adjusted by adjusting the diffraction characteristics of the diffractive optical element 40. Can be adjusted to. Therefore, when designing the diffractive optical element 40, the position, size, and shape of the illuminated area Z are first determined, and the diffraction characteristics of the diffractive optical element 40 are determined so that the entire area of the determined illuminated area Z can be illuminated. Should be adjusted.

The diffractive optical element 40 can be produced as a computer-generated hologram (CGH). A computer-synthesized hologram is produced by designing a structure having arbitrary diffraction characteristics by calculation on a computer. Therefore, by adopting the computer-synthesized hologram as the diffractive optical element 40, it is not necessary to generate object light and reference light using a coherent light source or an optical system, and to record interference fringes on the hologram recording material by exposure. can. As shown in FIG. 1, for example, the illuminating device 10 is supposed to illuminate the illuminated area Z having a predetermined size and shape at a predetermined position with respect to the diffractive optical element 40. By inputting information about the illuminated area Z into a computer as a parameter, a structure having a diffraction characteristic capable of illuminating the illuminated area Z, for example, an uneven surface can be specified by a computer calculation. By forming the specified structure by, for example, resin shaping, the diffractive optical element 40 as a computer composite hologram can be manufactured at low cost by a simple procedure.

The light diffracted by the diffractive optical element 40 illuminates the illuminated area Z as illumination light. In the illustrated example, no other optical element or the like is interposed between the diffractive optical element 40 and the illuminated region Z. Therefore, the diffracted light in the diffractive optical element 40 is directly incident on the illuminated region Z. The diffracted light at each point on the diffractive optical element 40 illuminates at least a part of the illuminated region Z. That is, the diffracted light at each point on the diffractive optical element 40 travels within a predetermined diffusion angle range to illuminate the illuminated region Z.

Here, in FIG. 2, the illuminated area Z in the real space is shown in a perspective view. Further, FIG. 3 shows an illuminated region Z in an angular space with reference to the position where the diffractive optical element 40 is provided. In FIG. 3, the illuminated region Z is shown by the angular coordinates with respect to the reference position on the diffractive optical element 40, specifically, the coordinate system represented by the angle θV and the angle θH. Here, as shown in FIG. 4, the angle θV represents the relative position of the illuminated region Z with respect to the reference position on the diffractive optical element 40 in the projection on the yz plane of FIG. 2 as an angle with respect to the z-axis direction. There is. Further, as shown in FIG. 5, the angle θH represents the relative position of the illuminated region Z with respect to the reference position on the diffractive optical element 40 in the projection on the xz plane of FIG. 2 as an angle with respect to the z-axis direction. ..

In the non-limiting example shown in FIGS. 1 to 5, the diffractive optical element 40 is arranged so that its emission surface is located on the xy surface, and the illuminated region Z extends on the xz surface. There is. However, the present invention is not limited to this example, and for example, the illuminated area Z may be inclined with respect to the xz plane.

For the design of the diffractive optical element 40, for example, an iterative Fourier transform method is used. FIG. 6 is a flowchart showing an example of the processing procedure of the iterative Fourier transform method. First, from the irradiance distribution on the illuminated region Z, the angular spatial distribution of the primary diffracted light intensity from the diffractive optical element 40 is calculated by a computer, and a random phase distribution is prepared (step S1).

Next, a complex amplitude distribution of the electric field is generated by combining the angular space distribution calculated in step S1 with a random phase distribution (step S2). Next, the obtained complex amplitude distribution is subjected to an inverse Fourier transform (IFT) to generate a complex amplitude distribution of the electric field on the illuminated region Z (step S3).

Since the obtained complex amplitude distribution was calculated using a random phase distribution, it has a light intensity distribution that reflects the randomness. Next, the obtained light intensity distribution is modified according to the design illumination intensity distribution on the illuminated area Z (step S4). Next, the complex amplitude distribution including the light intensity distribution corrected in step S4 and the phase information of the complex amplitude distribution generated in step S3 is subjected to a Fourier transform to perform a Fourier transform, and the complex amplitude distribution of the electric field on the diffractive optical element 40 is performed. Is calculated (step S5). Next, a complex amplitude distribution is generated by replacing the light intensity distribution included in the complex amplitude distribution calculated in step S5 with the angular spatial distribution calculated in step S1 (step S6). Next, the processing after step S3 is repeated using the complex amplitude distribution generated in step S6.

As the processes of steps S3 to S6 are repeated, the light intensity distribution in the emission angle space from the diffractive optical element 40 approaches the light intensity distribution calculated in step S1.

The processing procedure of FIG. 6 is a process on the premise that the illuminated region Z is far from the diffraction optical element 40, and the diffraction image on the illuminated region Z is a Fraunhofer diffraction image. Therefore, even if the normal direction nd of the illuminated area Z is not parallel to the normal direction nd1 of the emission surface of the diffractive optical element 40, the illumination intensity can be made uniform over the entire area of the illuminated area Z, and the illuminated area can be uniformed. Blurring in Z can be suppressed.

By the way, in the example shown in FIG. 1, the illuminated area Z is set apart from the lighting device 10 in the z direction and extends in the x direction orthogonal to the z direction. In such an example, if the traveling direction of the illumination light L1 from the illumination device 10 deviates even slightly in the yz plane, the width w of the illuminated region Z fluctuates greatly. Further, even if the illuminated area Z is located in the vicinity of the illumination device 10, if the incident angle α of the illumination light L1 emitted from the illumination device 10 to the illuminated area Z becomes large, the illumination is similarly performed. The width w of the illuminated area Z fluctuates greatly due to a slight deviation in the traveling direction of the light L1. Then, if the width w becomes thicker, it is assumed that the illuminated region Z can no longer be recognized as an elongated region by the observer located in the vicinity of the illuminated region Z. Due to such a problem, a lighting device that requires high-precision lighting has conventionally been restricted in its installation position, and is located in the vicinity of the illuminated area Z or at a position where the angle of incidence of the illumination light on the illuminated area Z becomes small. Had to be placed in.

The incident angle α to the illuminated region Z is an angle formed by the traveling direction of the incident light with respect to the normal direction nd of the illuminated region Z.

On the other hand, in the lighting device 10 described here, the optical path of the illumination light L1 is adjusted by the diffractive optical element 40. In general, since the optical path adjusting function of the diffractive optical element 40 is highly accurate, the illuminated area Z can be illuminated with a desired pattern with high accuracy. Therefore, the position relative to the illuminated area Z is not strongly constrained, for example, a position far away from the illuminated area Z, a position where the incident angle α of the illumination light with respect to the illuminated area Z becomes large, and the like. Also, the lighting device 10 can be installed.

For example, according to the diffractive optical element 40 made of a computer-synthesized hologram manufactured by the design described with reference to FIG. 6, the traveling direction of light incident from a certain direction is ± 0.01 ° in an angular space. It can be adjusted with precision. By using such a diffractive optical element 40, the incident angle α of the illuminated area Z at a distance of 1 m or more and 300 m or less from the diffractive optical element 40 and the illuminated area Z of the illumination light becomes 45 ° or more at the minimum. It is possible to illuminate the illuminated area Z having a maximum of 89.99 ° or less with a desired pattern with high accuracy.

Further, as a further device, as shown in FIG. 7, the diffractive optical element 40 may have a plurality of element diffractive optical elements 41. The plurality of element diffractive optical elements 41 are arranged by dividing the diffractive optical element 40 into a plane. In other words, the diffractive optical element 40 is configured by tiling a plurality of element diffractive optical elements 41. In this example, each element diffractive optical element 41 exerts a diffracting action on the light emitted from the coherent light source 20. That is, each element diffractive optical element 41 is configured as a hologram element or the like as described above.

Also in the example shown in FIG. 7, the illuminated area Z illuminated by the illumination device 10 is a quadrangular region located far away from the illumination device 10 and having a longitudinal direction. However, the longitudinal direction dl of the illuminated area Z extends in the direction away from the lighting device 10, that is, in the z direction. 8 and 9 are views corresponding to FIGS. 2 or 3, respectively, and show the illuminated area Z of FIG. 7 in a real space or an angular space.

As shown in FIG. 10, when lights L101 and L102 are emitted in parallel directions from two positions on the diffractive optical element 40 and are incident on the illuminated region Z, the two lights L101 and L102 are illuminated. It is incident on different points in the region Z. When the two lights L101 and L102 are displaced in a direction non-parallel to the illuminated area Z, the amount of deviation a'[m] of the incident position in the illuminated area Z is the two lights L101 and L102. It becomes larger than the minimum deviation amount a [m] of the optical path of. Specifically, when the optical paths of the two lights L101 and L102 are deviated by a [m] on the surface along the normal direction nd to the illuminated area Z, the incident position on the illuminated area Z The amount of deviation a'[m] is expressed by the following equation using the angle of incidence α [°] on the illuminated area Z.
a'= a / cosα ・ ・ ・ Equation (1)
That is, the deviation amount a'[m] on the illuminated area Z is equal to or greater than the actual deviation amount a [m] of the light beam.

For example, in the diffractive optical element 40 shown in FIG. 7, assuming that the two element diffractive optical elements 41 arranged in the y-axis direction have the same diffraction characteristics, the two element diffractive optical elements 41 As shown in FIG. 11, the illuminated areas are the illuminated area Z1 shown by the solid line and the illuminated area Z2 shown by the dotted line, respectively, and the illuminated area Z1 and the illuminated area Z2 are in the z-axis direction. It will shift. The amount of deviation of the illuminated area Z1 and the illuminated area Z2 in the z-axis direction is significantly larger than the amount of deviation of the two element diffractive optical elements 41 in the y-axis direction.

From the above points, it is preferable that the diffractive optical element 40 has a plurality of element diffractive optical elements 41, and at least two element diffractive optical elements 41 included in the plurality of element diffractive optical elements have different diffraction characteristics. .. In this example, the diffraction characteristics of at least two element diffractive optical elements 41 can be set according to the relative position of the element diffractive optical element 41 with respect to the region to be illuminated by each element diffractive optical element 41. For example, when each element diffractive optical element 41 illuminates the entire area of the illuminated area Z, the element diffractive optical element 41 takes into consideration the relative position of each element diffractive optical element 41 with respect to the illuminated area Z. Diffraction characteristics may be determined. According to such an example, each of the plurality of element diffractive optical elements 41 can illuminate the illuminated area Z with a desired pattern with high accuracy.

The above equation (1) holds that the maximum distance between the two lights L101 and L102 on the plane orthogonal to the illuminated area Z is the minimum deviation amount a [m]. If it is. Then, when the lights L101 and L102 are displaced along the plane orthogonal to the illuminated region Z, the deviation of the incident position on the illuminated region Z becomes maximum, and the deviation amount is the a'[of the above-mentioned equation (1). m]. Further, as is clear from the equation (1), as the incident angle α [°] increases, the amount of deviation a'[m] of the incident position on the illuminated area Z also increases, and the incident angle α [°] increases. As it becomes smaller, the amount of deviation a'[m] of the incident position on the illuminated area Z also becomes smaller.

Therefore, from the viewpoint of illuminating the illuminated area Z with a desired pattern with high accuracy, a plurality of objects arranged along the line of intersection lx between one surface pl1 and the other surface pl2 shown in FIG. It is preferable that each of the element diffraction optical elements 41 has its diffraction characteristics adjusted according to its position. One surface pl1 that specifies the line of intersection lx includes the optical path of the incident light L81 that maximizes the incident angle α [°] from the diffractive optical element 40 to the illuminated region Z, and is the normal direction to the illuminated region Z. It is a plane parallel to nd. That is, this surface pl1 is located on the exit surface of the diffractive optical element 40 such that the normal direction nd to the illuminated region Z and the maximum angle α [°] with respect to the normal direction nd are formed. It includes a straight line la that connects the position and a certain position on the illuminated area Z. On the other hand, the other surface pl2 is a virtual surface on which the exit surface of the diffractive optical element 40 is located. In the illustrated example, this plane pl2 is the xy plane.

That is, assuming that the plurality of element diffractive optical elements 41 have the same diffraction characteristics, they are illuminated by the diffracted light from the element diffractive optical elements 41 arranged at different positions along the direction of the intersection line lp. The area on the illuminated area Z will change significantly. Therefore, adjusting the diffraction characteristics of the element diffractive optical elements 41 arranged in the direction of the line of intersection lk separately from the other element diffractive optical elements 41 increases the illuminated area Z in a desired pattern. It is effective for accurate lighting. Further, as a premise, dividing the diffractive optical element 40 in the direction of the line of intersection LX is effective in illuminating the illuminated area Z with a desired pattern with high accuracy.

In the example shown in FIG. 7, the plurality of element diffractive optical elements 41 are arranged in a matrix. In other words, the diffractive optical element 40 is divided in the y-axis direction corresponding to the direction of the line of intersection lk, and is further arranged in the x-axis direction orthogonal to the y-axis direction. In this example, each of the plurality of element diffractive optical elements 41 arranged in the y-axis direction corresponding to the direction of the line of intersection lk may have different diffraction characteristics depending on their arrangement positions. Further, each of the plurality of element diffraction optical elements 41 arranged in the x-axis direction may also have different diffraction characteristics depending on their arrangement positions. On the other hand, the plurality of element diffractive optical elements 41 may be arranged in the y-axis direction corresponding to the direction of the line of intersection lk, and each element diffractive optical element 41 may be elongated in the x-axis direction.

As yet another device, in the example in which the diffractive optical element 40 includes a plurality of element diffractive optical elements 41, at least two element diffractive optical elements 41 may illuminate different regions as shown in FIG. good.

Assuming that the angle formed by the traveling direction of the diffracted light with respect to the traveling direction of the 0th-order light is the diffraction angle, the structure of the diffraction optical element for realizing diffraction according to this diffraction angle, for example, the unevenness forming an interference fringe pattern Design the pitch. Further, in order to optimize the diffraction efficiency, a configuration that can affect the diffraction efficiency depending on the structure of the diffraction optical element for realizing the diffraction designed according to the diffraction angle, as a specific example, the interference fringe pattern The depth of the unevenness that forms the Therefore, when a structure for realizing a wide range of diffraction angles is provided in one diffractive optical element, it is necessary to optimize a configuration that can affect the diffraction efficiency at each position in the one diffractive optical element. .. For example, when it is necessary to provide unevenness with a wide range of pitches in one diffractive optical element, it is necessary to optimize the depth of unevenness at that position according to the pitch of the unevenness at each position. However, it is virtually impossible to give such a complex configuration to an actual luminaire, nor is it commercially viable. As a result, in a diffractive optical element having a wide diffraction angle range and capable of diffusing the illumination light over a wide range, the diffraction efficiency is lowered, and the energy efficiency of the lighting device is lowered accordingly.

In order to deal with such a problem, as shown in FIG. 12, the light diffracted by the different element diffracting optical element 41 divides the illuminated area Z into different elements among the plurality of element illuminated areas Ze. The illuminated area may be illuminated. In the example shown in FIG. 12, the illuminated area Z is divided into a first element illuminated area Ze1 and a second element illuminated area Ze2. The first element illuminated region Ze1 may be illuminated by the diffracted light from one element diffracting optical element 41a, and the second element illuminated region Ze2 may be illuminated by the diffracted light from the other element diffracting optical element 41b. .. The diffraction angle ranges Rθ1 and Rθ2 of the element diffractive optical elements 41a and 41b are narrower than the diffraction angle range Rθ when the diffracted light is spread over the entire area of the illuminated region Z. As a result, the diffraction efficiency of the element diffraction optical element 41 can be improved, and the illuminated area Z can be brightly illuminated with a constant energy. Since the burden on the power source can be reduced in this way, it is possible to supply electric power by a battery or the like, and from this point as well, the degree of freedom regarding the installation position of the lighting device 10 can be improved.

The number of element illuminated areas Ze included in the illuminated area Z is not limited to two, and may be three or more. In the example shown by the alternate long and short dash line in FIGS. 8 and 9, the illuminated area Z includes four element illuminated areas Ze. In this example, the diffractive optical element 40 includes four or more element diffractive optical elements 41, and each element illuminated region Ze is illuminated by diffracted light from one or more element diffractive optical elements 41.

Further, each element diffracting optical element 41 may diffract light into the element illuminated region Ze including the optical path of the 0th order light emitted from the element diffracting optical element 41. According to such an example, the angle formed by the traveling direction of the diffracted light with respect to the traveling direction of the 0th-order light, that is, the diffraction angle can be reduced. As a result, the diffraction efficiency of each element diffraction optical element 41 can be further effectively improved, and as a result, the energy efficiency of the lighting device 10 can be further effectively improved.

Next, an application example of the lighting device 10 of the present invention will be described with reference to FIGS. 15 to 20.

15 and 16 are diagrams for explaining an application example of the lighting device 10. FIG. 15 is a perspective view showing the tunnel 1 and the road 5 passing through the tunnel 1, and FIG. 16 is a plan view showing the tunnel 1 and the road 5. In FIG. 16, the ceiling portion 3 of the tunnel 1 is not shown.

The tunnel 1 is provided so as to cover a part of the road 5 along the extending direction of the road 5. In the illustrated example, the tunnel 1 covers the road 5 over the entire width direction of the road 5. The tunnel 1 has two side wall portions 2 facing each other in the width direction of the road 5 with the road 5 in between, and a ceiling portion 3 connecting the upper portions of the side wall portions 2 and covering the upper part of the road 5. .. In particular, in the illustrated example, the tunnel 1 has a substantially arc shape in a cross section orthogonal to the extending direction of the road 5, and the side wall portions 2 and the ceiling portion 3 form a smoothly continuous wall surface. ..

The road 5 is provided with a lane marking 6 for partitioning the lane in which the vehicle travels. The lane marking 6 is provided in a linear shape such as a solid line or a broken line along the extending direction of the road 5. In the illustrated example, the road 5 has a lane in which a vehicle heading to one side should travel and a lane in which a vehicle heading to the other side should travel along the extending direction of the road 5 in the central portion in the width direction of the road 5. A roadway center line 7 (carriageway line 6) is provided to partition the road, and a roadway outer line 8 (carriageway line 6) is provided to separate the roadway and the roadside zone near both ends in the width direction of the road 5. .. In addition, the present invention is not limited to this, and other lane markings such as a lane boundary line that separates a plurality of lanes on which vehicles heading in the same direction should travel may be provided as the lane marking 6.

In the illustrated example, the illuminated area Z is located on the lane marking 6 of the road 5. In particular, the illuminated area Z includes the lane marking 6 and is located over a predetermined distance from the entrance or exit of the tunnel 1 toward the inside of the tunnel. The lighting device 10 is provided on the ceiling portion 3 of the tunnel 1. As will be described later, the lighting device 10 may be provided at another location such as the side wall portion 2.

17 and 18 are diagrams for explaining another application example of the lighting device 10. FIG. 17 is a perspective view showing the tunnel 1 and the road 5 passing through the tunnel 1, and FIG. 18 is a plan view showing the tunnel 1 and the road 5. In FIG. 18, the ceiling portion 3 of the tunnel 1 is not shown.

In the illustrated example, the illuminated area Z is located on the side wall 2 of the tunnel 1. In particular, the illuminated area Z is located on the side wall portion 2 over a predetermined distance from the vicinity of the entrance or exit of the tunnel 1 toward the inside of the tunnel. In the illustrated example, the lighting device 10 is provided on the side wall portion 2 facing the side wall portion 2 in which the illuminated area Z is provided. Not limited to this, the lighting device 10 may be provided at another location such as the ceiling portion 3.

According to the application example described with reference to FIGS. 15 and 16 and the application example described with reference to FIGS. 17 and 18, when entering the tunnel from a bright environment illuminated by sunlight or the like, the inside of the tunnel Even if a black hole phenomenon or a black frame phenomenon occurs, the lane marking 6 or the side wall portion 2 is illuminated for a predetermined distance from the entrance of the tunnel 1 to the inside of the tunnel 1, so that the tunnel 1 is illuminated. The section line 6 or the side wall portion 2 can be easily seen by the occupants of the vehicle trying to enter the inside. Therefore, before entering the tunnel 1, the occupants of the vehicle are asked about the situation in the tunnel 1, for example, whether the road 5 extends linearly in the tunnel 1, curves to the right or left, or goes uphill. It is possible to easily recognize whether it is a tunnel or a downhill. This enables safe operation before and after entering the entrance of the tunnel 1.

FIG. 19 is a diagram for explaining still another application example of the lighting device 10. FIG. 19 is a perspective view showing a tunnel 1 and a road 5 passing through the tunnel 1.

In the illustrated example, the illuminated area Z is located on the ceiling 3 of the tunnel 1. In this application example, the illuminated area Z has a shape including a numerical value indicating a speed limit. Therefore, the illuminated area Z is formed so as to display the speed limit information on the ceiling portion 3 of the tunnel 1. In the illustrated example, the lighting device 10 is installed on a pole 51 provided on the road side in front of the tunnel 1. Not limited to this, the illuminated area Z may be located at another location such as the side wall portion 2. Further, the illuminated area Z may be formed so as to display information other than the speed limit. Further, the lighting device 10 may be installed at other places such as the side wall portion 2 and the ceiling portion 3 of the tunnel 1.

According to this application example, information such as a speed limit can be displayed on the ceiling portion 3 and the side wall portion 2 in the tunnel 1. Therefore, in order to display information in the tunnel 1, it is not necessary to provide an additional display device such as an electric display board. As a result, information can be displayed in the tunnel 1 with a simple configuration and low cost.

In each of the above-mentioned application examples, the installation location of the lighting device 10 is not particularly limited. As shown in FIG. 20, the lighting device 10 can be installed at various locations such as the side wall portion 2 of the tunnel 1, the ceiling portion 3, the roadside, or the pole 51 provided on the road center line 7. ..

Further, in the application example described with reference to FIGS. 15 and 16 and the application example described with reference to FIGS. 17 and 18, the illuminated area Z gradually increases from the entrance or exit of the tunnel 1 toward the inside of the tunnel 1. It can also be formed so that its illuminance is reduced. For example, a lighting device 10 is installed on a side wall portion 2, a ceiling portion 3, or a pole 51 near the entrance or exit of the tunnel 1, and a direction forming a relatively small angle with the extending direction of the road 5 toward the inside of the tunnel 1. By emitting the illumination light toward the tunnel 1 and forming the illuminated area Z by the illumination light, the illuminance of the illuminated area Z decreases as it goes from the entrance of the tunnel 1 to the inside of the tunnel 1. Can be formed into.

In this case, as the eyes of the occupant of the vehicle entering the tunnel 1 adapt to the brightness in the tunnel 1, the brightness of the illuminated area Z becomes smaller, so that the occupant in the tunnel 1 is in the illuminated area. I don't feel Z dazzling. This enables safer operation before and after entering the entrance of the tunnel 1.

Although some application examples have been shown above, it is natural that two or more application examples may be used in combination.

In the embodiment described above, the lighting device 10 is a lighting device 10 that illuminates the inside of the tunnel 1, and is a coherent light source 20 and a shaping optical system 30 that shapes the coherent light emitted from the coherent light source 20. And a diffractive optical element 40 that diffracts the coherent light shaped by the shaping optical system 30 and directs it toward the illuminated region Z. In such an embodiment, the optical path of the light is directed to the illuminated region Z by the diffractive optical element 40 that diffracts the coherent light shaped by the shaping optical system 30. According to the diffractive optical element 40, the traveling direction of the coherent light shaped by the shaping optical system 30 can be diffracted into a desired angular space with high accuracy. As a result, the illuminated area Z far away from the illuminating device 10 and the illuminated area Z in which the normal direction nd of the diffractive optical element 40 exceeds a large angle, for example, 45 ° with respect to the normal direction nd1. Can be illuminated with high accuracy in a desired desired pattern. The installation position of such a lighting device 10 can be selected with a high degree of freedom.

Further, the power consumption of the lighting device 10 is significantly lower than that of the projector. Therefore, for example, it is possible to meet the power demand by installing it together with a battery in which a solar cell or the like is combined. That is, since it is easy to secure a power source, the degree of freedom in the installation position of the lighting device 10 can be improved.

Such a lighting device 10 can be arranged at a position away from the illuminated area Z where illumination is performed. The operation of the lighting device 10 may be automatically performed based on the detection result of the sensor or the like according to the application. For example, the lighting device 10 may include an illuminance sensor and illuminate the illuminated area Z as the brightness outside the tunnel 1 changes. That is, the illuminated area Z may be illuminated when the brightness outside the tunnel 1 is larger than the predetermined brightness. Further, the lighting device 10 may include a vehicle detection sensor, detect that the vehicle is approaching the tunnel 1, and illuminate the illuminated area Z. Further, the lighting device 10 may include the vehicle speed detection sensor and illuminate the illuminated area Z when the speed of the vehicle approaching the tunnel 1 exceeds a predetermined speed.

Further, in one specific example of the above-described embodiment, the shaping optical system 30 expands the optical path area of the coherent light. According to such an example, according to the conservation law of Etandu, the coherent light shaped by the shaping optical system 30 narrows its radiated solid angle as the optical path area increases, that is, the cross-sectional area of the luminous flux increases. Become. therefore. The divergence angle of the coherent light shaped by the shaping optical system 30 can be made significantly smaller than the divergence angle of the coherent light before the incident of the shaping optical system 30. That is, the divergence angle of the incident light on the diffractive optical element 40 can be effectively reduced. As a result, the illuminated area Z can be illuminated with a desired pattern with higher accuracy by diffraction with the diffraction optical element 40.

Further, in one specific example of the above-described embodiment, the diffractive optical element 40 includes a plurality of element diffractive optical elements 41, and at least two element diffractive optical elements 41 included in the plurality of element diffractive optical elements 41. It was made to have different diffraction characteristics. In this example, the diffraction characteristics of each element diffractive optical element 41 can be adjusted according to the relative position of each element diffractive optical element 41 with respect to the illuminated region Z. Therefore, each element diffractive optical element 41 can illuminate a predetermined region with high accuracy.

Further, the at least two element diffractive optical elements 41 may illuminate different regions. According to this example, the region to be illuminated by the diffracted light of one element diffracting optical element 41 can be reduced. Therefore, the diffraction angle ranges Rθ1 and Rθ2 in each element diffraction optical element 41 can be narrowed. Thereby, the diffraction efficiency of each element diffraction optical element 41 can be improved. As a result, the energy efficiency of the lighting device 10 can be improved. That is, the illuminated area Z can be brightly illuminated without increasing the input energy.

Further, the at least two element diffractive optical elements 41 include the optical path L81 of the incident light beam having the maximum incident angle α from the diffractive optical element 40 to the illuminated region Z, and are in the normal direction nd to the illuminated region Z. The parallel surface pl1 and the virtual surface pl2 on which the diffractive optical element 40 is located may be arranged along the direction parallel to the line of intersection lx. When the adjacent element diffractive optical elements 41 have the same diffraction characteristics, the light incident on the illuminated region Z from each element diffractive optical element 41 at the same incident angle α minimizes the arrangement pitch of the adjacent element diffractive optical elements. Assuming that the amount of deviation is a, the amount of deviation is a'represented by the following equation in the illuminated area.
a'= a / cosα ・ ・ ・ Equation (1)
The diffracted light from the plurality of element diffractive optical elements 41 having the same diffraction characteristics is subjected to element diffractive optics on the illuminated region Z having the normal direction nd non-parallel to the normal direction nd1 of the diffractive optical element 40. It is incident on a region deviated by the arrangement pitch a or more of the element 41. This amount of deviation becomes maximum when the incident angle α is maximum. That is, when the plurality of element diffractive optical elements 41 arranged along the line of intersection lx between the surface pl1 and the surface pl2 have the same diffraction characteristics, the deviation of the region illuminated by each element diffractive optical element 41 The amount a'is the maximum. Therefore, the diffraction characteristics of the element diffractive optical elements 41 arranged along the intersecting line lp are set according to the relative position with respect to the illuminated region Z to be illuminated by the element diffractive optical element 41 or a part of the region. By setting, the illuminated area Z can be illuminated with a desired pattern with higher accuracy.

Although one embodiment has been described by a plurality of specific examples, these specific examples are not intended to limit one embodiment. The above-described embodiment can be implemented in various other specific examples, and various omissions, replacements, and changes can be made without departing from the gist thereof.

1 Tunnel 2 Side wall 3 Ceiling 5 Road 6 Section line 7 Road center line 8 Road outside line 10 Lighting device 20 Coherent light source 20A 1st coherent light source 20B 2nd coherent light source 20C 3rd coherent light source 30 Orthopedic optical system 31 1st lens 32 Second lens 40 Diffraction optical element 41 Element Diffractive optical element 41a First element Diffractive optical element 41b Second element Diffractive optical element Z Illuminated area Ze 1 Illuminated area Ze1 First element Illuminated area Ze2 Second element Illuminated area

Claims (7)

A lighting device that illuminates the inside of a tunnel.
With a coherent light source,
A shaping optical system that shapes the coherent light emitted from the coherent light source,
E Bei and a diffractive optical element for directing the illuminated region diffracts the coherent light is shaped by the shaping optical system,
The diffractive optical element includes a plurality of element diffractive optical elements.
At least two element diffractive optical elements included in the plurality of element diffractive optical elements have different diffraction characteristics.
The at least two element diffractive optical elements are illuminating devices that illuminate different regions. The illuminating device according to claim 1, wherein the shaping optical system expands the cross-sectional area of the luminous flux of the coherent light. The lighting device according to claim 1 or 2, wherein the coherent light is simultaneously incident on all the element diffractive optical elements. The at least two element diffractive optical elements include a plane of incident light having a maximum incident angle from the diffractive optical element to the illuminated region and parallel to the normal direction to the illuminated region, and the above. The lighting device according to any one of claims 1 to 3 , which is arranged along a direction parallel to the line of intersection with the virtual surface on which the diffractive optical element is located. The lighting device according to any one of claims 1 to 4 , wherein the illuminated area includes a lane dividing line and is located over a predetermined distance from the entrance or exit of the tunnel toward the inside of the tunnel. .. The lighting device according to claim 5 , wherein the illuminance of the illuminated area decreases toward the inside of the tunnel from the entrance or exit of the tunnel. The illuminated area is located on the ceiling and / or side wall of the tunnel.
The lighting device according to any one of claims 1 to 6 , wherein the illuminated area displays information.

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