JP2019053887A - Luminaire - Google Patents

Abstract

To provide a luminaire capable of lighting up a lit region with uniform lightness.SOLUTION: A luminaire 10 lights up a lit region LZ on a projection surface Pp. The luminaire has: a coherent light source 20; a shaping optical system 30 (a first lens 31 and a second lens 32) which shapes coherent light emitted from the coherent light source; and a diffraction optical element 40 which lights up the lit region LZ by diffracting the coherent light shaped by the shaping optical system, and projects a plurality of unit images lu on the projection surface. The unit images on the projection surface Pp are higher in density in a certain region than other regions which are longer in projection distance than the certain region.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an illumination device that illuminates an illuminated area on a projection surface.

  For example, as disclosed in Patent Document 1, an illumination device including a light source and a diffractive optical element is known. In the illumination device disclosed in Patent Literature 1, the diffractive optical element diffracts the light from the light source, so that the illumination area located on the projection surface can be illuminated with a desired pattern.

Japanese Patent Laying-Open No. 2015-132707

  As a diffractive optical element, a computer generated hologram (CGH) is known. A computer-generated hologram is produced by designing a structure having an arbitrary diffraction characteristic by calculation on a computer. As a specific example, a desired pattern to be illuminated as an illuminated area is considered as a collection of point images, and an interference pattern due to diverging light from each point image and light scheduled to enter the diffractive optical element is calculated. By fabricating a structure corresponding to the interference pattern, a diffractive optical element can be obtained.

  Strictly speaking, the image reproduced by the diffractive optical element manufactured in this way is a set of images to be a reproduced image of each point image. The point image assumed in the design of the diffractive optical element cannot be enlarged due to restrictions such as the fine structure of the diffractive optical element. Therefore, the reproduction light for reproducing each point image is scattered and incident on the illuminated area. In this case, uneven brightness may occur, and even a region where no light is incident may be generated. However, the actual incident angle of the incident light incident on the diffractive optical element is strictly different from the incident angle of the incident light assumed in the design. The actual incident light becomes diffuse light having a slight diffusion angle. Due to these factors, the reproduction light from the diffractive optical element also becomes divergent light. As a result, the illumination device can illuminate the illuminated area on the projection surface uniformly to some extent.

  However, in recent years, the application range of illumination devices using diffractive optical elements has been expanded. And, it is required to illuminate the illumination device with a wider illumination area or to illuminate the illumination area from a direction greatly inclined with respect to the projection plane due to restrictions on installation of the illumination device. Sometimes it is done. And in the conventional illuminating device mentioned above, the to-be-illuminated area may not be able to be illuminated with sufficient uniform brightness.

  The present invention has been made in consideration of the above points, and an object of the present invention is to provide an illuminating device that can illuminate an illuminated area with uniform brightness.

A first lighting device according to the present invention comprises:
An illumination device that illuminates an illuminated area on a projection surface,
A coherent light source,
A shaping optical system for shaping coherent light emitted from the coherent light source;
A diffractive optical element that diffracts the coherent light shaped by the shaping optical system and projects a plurality of unit images on the projection plane, thereby illuminating the illuminated area;
The density of the unit images on the projection plane is higher in a certain area than in other areas where the projection distance is longer than that in the certain area.

  In the first illuminating device according to the present invention, when the illuminated area is divided into a plurality of divided areas, the density of the unit images on the projection plane in any one divided area is larger than that of the one divided area. Alternatively, the density may be equal to or higher than the density of the unit image on the projection plane in another arbitrary divided region in which the projection distance becomes long.

  In the first illumination device according to the present invention, an incident angle of the coherent light on the projection surface in the certain region is smaller than an incident angle of the coherent light on the projection surface in the other region. May be.

  In the first illuminating device according to the present invention, when the illuminated region is divided into a plurality of divided regions, the incident angle of the coherent light on the projection surface in the one divided region is the other arbitrary The angle of incidence of the coherent light on the projection surface in one divided region may be less than or equal to.

A second lighting device according to the present invention comprises:
An illumination device that illuminates an illuminated area on a projection surface,
A coherent light source,
A shaping optical system for shaping coherent light emitted from the coherent light source;
A diffractive optical element that diffracts the coherent light shaped by the shaping optical system and projects a plurality of unit images on the projection plane, thereby illuminating the illuminated area;
The density of the unit image on the projection surface is higher in a certain region than in other regions where the incident angle of the coherent light on the projection surface is larger than that in the certain region. .

  In the second illumination device according to the present invention, when the illuminated area is divided into a plurality of divided areas, the density of the unit image on the projection plane in any one divided area is higher than that of the one divided area. Also, the density of the unit image on the projection plane in any one other divided region where the incident angle of the coherent light on the projection plane is large is greater than or equal to.

  In the first or second illuminating device according to the present invention, the plurality of unit images may be separated from each other on a certain surface separated from the projection surface along a normal direction to the projection surface.

A third lighting device according to the present invention comprises:
An illumination device that illuminates an illuminated area on a projection surface,
A coherent light source,
A shaping optical system for shaping coherent light emitted from the coherent light source;
A diffractive optical element that diffracts the coherent light shaped by the shaping optical system and projects a plurality of unit images on the projection plane, thereby illuminating the illuminated area;
On a certain surface separated from the projection surface along the normal direction to the projection surface, a region where coherent light for reproducing one unit image is incident is coherent light for reproducing another unit image. Separated from the area.

  According to the present invention, it is possible to illuminate the illuminated area with sufficiently uniform brightness.

FIG. 1 is a perspective view illustrating a lighting device for explaining an embodiment according to the present disclosure. FIG. 2 is a diagram for explaining a unit image reproduced by the illumination device. FIG. 3 is a plan view showing an illuminated area illuminated by the illumination device. FIG. 4 is a diagram for explaining a method of manufacturing a diffractive optical element. FIG. 5 is a diagram showing the positional relationship between the diffractive optical element and the illuminated region on the yz plane, and is a diagram for explaining a change in the projected area of the unit image. FIG. 6 is a diagram showing the positional relationship between the diffractive optical element and the illuminated region on the yz plane, and is a diagram for explaining a change in the projected area of the unit image. FIG. 7 is a diagram for explaining the relationship between the projection distance and the projection area of the unit image. FIG. 8 is a diagram for explaining the relationship between the projection distance and the projection area of the unit image. FIG. 9 is a diagram showing the positional relationship between the diffractive optical element and the illuminated region on the yz plane, and is a diagram for explaining the relationship between the incident angle and the projected area of the unit image. FIG. 10 corresponds to FIG. 1 and is a perspective view showing a modification of the lighting device. FIG. 11 is a perspective view corresponding to FIG. 1 and showing another modified example of the illumination device. FIG. 12 is a perspective view corresponding to FIG. 1 and showing still another modification of the lighting device.

  Hereinafter, an embodiment of the present disclosure will be described with reference to the drawings. In the drawings attached to the present specification, for the sake of illustration and ease of understanding, the scale, the vertical / horizontal dimension ratio, and the like are appropriately changed and exaggerated from those of the actual product.

  In addition, as used in this specification, the shape and geometric conditions and the degree thereof are specified. For example, terms such as “parallel”, “orthogonal”, “identical”, length and angle values, etc. are strictly Without being bound by any meaning, it should be interpreted including the extent to which similar functions can be expected.

  FIG. 1 is a perspective view schematically showing the overall configuration of the illumination device 10. The illumination device 10 is a device that illuminates the illuminated area LZ. The illumination device 10 according to the present embodiment includes a coherent light source 20, a shaping optical system 30 that shapes the coherent light emitted from the coherent light source 20, and the coherent light shaped by the shaping optical system 30 to diffract the illuminated region LZ. And a diffractive optical element 40 directed toward the surface. The illumination device 10 illuminates the illuminated region LZ on the projection plane Pp by diffracting coherent light with the diffractive optical element 40 and projecting a plurality of unit images Iu onto the projection plane Pp. In particular, the lighting device 10 according to the present embodiment is devised to illuminate the illuminated area LZ with uniform brightness. Hereinafter, the lighting device 10 according to an embodiment will be described with reference to the illustrated specific example.

  As described above, the illumination device 10 is a device that illuminates the illuminated region LZ on the projection plane Pp. In the illustrated example, the illuminated area LZ in real space is an elongated area having a longitudinal direction dl. The illuminated area LZ has, for example, a ratio of the length in the longitudinal direction dl to the length in the lateral direction dw of 10 or more, and further, the illuminated area LZ in which this ratio is 100 or more, typically A line-shaped illuminated region LZ can also be used. Such an illuminating device can be applied to moving bodies, such as a motor vehicle and a ship, for example. In the moving body, it is necessary to illuminate a region extending forward in the traveling direction. In particular, it is preferable that a headlight of an automatic person traveling at a high speed, a so-called headlamp, brightly illuminates the road surface from the vicinity of the front of the automobile to the distance of the front.

  In the illustrated example, the projection plane Pp is an xz plane defined by a z direction parallel to the longitudinal direction dl and an x direction parallel to the width direction dw. The normal direction nd is parallel to the y direction orthogonal to the xz plane.

  However, it is not restricted to the illustrated example, You may make it the illuminating device 10 illuminate the area | region which has a predetermined outline.

  As described above, the illustrated illumination apparatus 10 includes the coherent light source 20, the shaping optical system 30, and the diffractive optical element 40 as its constituent elements. Hereafter, each component of the illuminating device 10 is demonstrated in order.

  Various types of light sources can be used as the coherent light source 20. Typically, a laser light source that oscillates laser light 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 LZ is illuminated with a color corresponding to the wavelength region of the coherent light oscillated from the coherent light source 20.

  However, the coherent light source 20 may include a plurality of coherent light sources 20, and the light emitted from each of the coherent light sources 20 may be superposed and then directed toward the shaping optical system 30 and the diffractive optical element 40. Further, as in the modification examples shown in FIGS. 10 and 11, the shaping optical systems 30A, 30B, and 30C and the diffractive optical element 40A in which the light emitted from each coherent light source 20 is provided corresponding to the coherent light source 20 are provided. , 40B, and 40C, and then may be superimposed on the illuminated area LZ. In such an example, the plurality of coherent light sources 20 included in the coherent light source 20 may emit light in the same wavelength region. Since the coherent light source 20 includes the coherent light source 20 that emits light in the same wavelength region, the illuminated region LZ can be illuminated brightly.

  10 and 11, the coherent light source 20 includes 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 region LZ is adjusted by adjusting the emission of coherent light from each of the coherent light sources 20, more specifically, adjusting the emission start / stop and the emission amount. The color and the brightness of the illuminated area LZ 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 light flux of the coherent light. Typically, the shaping optical system 30 expands the beam cross-sectional area of the coherent light in a cross section orthogonal to the optical axis of the coherent light.

  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 beam. That is, the shaping optical system 30 functions as a collimating optical system. As shown in FIG. 1, the shaping optical system 30 includes 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 light beam. The second lens 32 reshapes the divergent light beam generated by the first lens 31 into a parallel light beam. 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 diffractive 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 LZ. Therefore, the illuminated region LZ is illuminated by the diffracted light from the diffractive optical element 40 (see FIG. 1).

  The diffractive optical element 40 is typically a hologram element. By using a hologram element as the diffractive optical element 40, it becomes easier to design the diffraction characteristics of the hologram element, and the hologram element that illuminates the entire illuminated area LZ having a predetermined position, size, and shape is relatively designed. It can be done easily.

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

  The diffractive optical element 40 can be produced as a computer generated hologram (CGH). A computer-generated hologram is produced by calculating a structure having arbitrary diffraction characteristics on a computer. Therefore, by adopting a computer-generated hologram as the diffractive optical element 40, it is possible to eliminate generation of object light and reference light using a coherent light source or an optical system and recording of interference fringes on a hologram recording material by exposure. it can. For example, as illustrated in FIG. 1, the illumination device 10 is assumed to illuminate an illuminated region LZ having a predetermined size and shape at a predetermined position with respect to the diffractive optical element 40. By inputting information on the illuminated area LZ as a parameter to the computer, a structure having diffraction characteristics that can illuminate the illuminated area LZ, for example, an uneven surface, can be specified by computation on the computer. By forming the specified structure by, for example, resin molding, the diffractive optical element 40 as a computer-generated hologram can be manufactured at a low cost by a simple procedure.

  The light diffracted by the diffractive optical element 40 illuminates the illuminated region LZ 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 LZ. Therefore, the diffracted light from the diffractive optical element 40 is directly incident on the illuminated region LZ. Diffracted light at each point on the diffractive optical element 40 illuminates at least a part of the illuminated region LZ. 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 area LZ.

  As shown in FIG. 2, the diffractive optical element 40 according to the present embodiment diffracts coherent light from the shaping optical system 30 to generate a plurality of unit images Iu on the projection plane Pp. The illuminated area LZ on the projection plane Pp is illuminated by an aggregate of a plurality of unit images Iu. The diffractive optical element 40 is designed as follows. First, as shown in FIG. 3, the shape of the illuminated area LZ is set. Next, as shown in FIG. 3, a point image pattern formed by arranging point images Ip, which are original images of the unit images Iu, on the virtual plane Pv is set. For example, the point image Ip is spread in the illuminated area LZ. In the example shown in FIG. 3, the outer contour of the point image pattern substantially matches the outer contour of the illuminated area LZ.

  Next, as shown in FIG. 4, incident light Li to the diffractive optical element 40 and divergent light Ld from each point image Ip toward the diffractive optical element 40 are set. Here, the “incident light Li to the diffractive optical element 40” is the same optical path as the light that enters the diffractive optical element 40 from the shaping optical system 30 in a state where the diffractive optical element 40 is incorporated in the illumination device 10. Let the light go on. “Divergent light Ld traveling from each point image Ip toward the diffractive optical element 40” is diffracted light that is diffracted at each position of the diffractive optical element 40 and travels toward each point image Ip when the illumination apparatus 10 is actually used. The light travels in the opposite direction and is incident on each position in the diffractive optical element 40 from the position of the point image Ip. Thereafter, an interference pattern on the diffractive optical element 40 formed by the incident light on the diffractive optical element 40 and the divergent light from each point image Ip toward the diffractive optical element 40 is formed, and the fine structure corresponding to the interference pattern Is made. An example of the fine structure is an uneven pattern. The calculation of the interference pattern is performed by a computer including model design of “incident light on the diffractive optical element 40” and “divergent light directed from each point image Ip toward the diffractive optical element 40”. Moreover, the fine structure which consists of an uneven | corrugated pattern can be produced by resin molding using a photolithographic technique.

  Next, the effect | action of the illuminating device 10 demonstrated above is demonstrated.

  As shown in FIG. 1, the coherent light emitted from the light source 20 first enters the shaping optical system 30. The shaping optical system 30 expands the light emitted from the light source 20. That is, the shaping optical system 30 shapes the light so that a region occupied by the coherent light spreads in a cross section orthogonal to the optical axis. The shaping optical system 30 includes a first lens 31 and a second lens 32. As shown in FIG. 1, the first lens 31 of the shaping optical system 30 divides the light emitted from the light source 20 and converts it into a divergent light beam. The second lens 32 of the shaping optical system 30 collimates the divergent light beam into a parallel light beam.

  The light shaped by the shaping optical system 30 is then directed to the diffractive optical element 40. The diffractive optical element 40 diffracts the coherent light from the shaping optical system 30 and directs it to the illuminated region LZ. As shown in FIG. 2, the diffractive optical element 40 reproduces a plurality of unit images Iu corresponding to each of the plurality of point images Ip on the projection plane Pp by diffracting the coherent light from the shaping optical system 30. . The plurality of unit images Iu are projected into the illuminated area LZ on the projection plane Pp. The illuminated area LZ is illuminated by the aggregate of the unit images Iu.

  As described above, the diffractive optical element 40 having such a diffraction characteristic can be produced by a computer-generated hologram as an element for reproducing a large number of point images Ip arranged on the virtual plane Pv. The diffractive optical element 40 configured by the computer-generated hologram is manufactured as a fine structure corresponding to an interference pattern between divergent light from each point image Ip and incident light incident on the diffractive optical element 40 in use. At the time of this production, the number of point images Ip cannot be increased unconditionally due to restrictions in producing a fine structure, computational complexity in a computer, etc., and the point image Ip is designed as a point. The Therefore, in actual use of the illuminating device 10, there may be uneven brightness due to the arrangement of the point images Ip in the illuminated area LZ on the projection plane Pp. Furthermore, it can be assumed that a gap is generated between two adjacent unit images Iu reproduced in the illuminated region LZ. Such a problem becomes particularly prominent when the illuminated region LZ has a large area.

  On the other hand, in the present embodiment, the following three ideas are proposed in order to cope with a problem such as uneven brightness in the illuminated area LZ. The following three ideas can be applied to the illumination device 10 or the diffractive optical element 40 independently of each other. And the illumination device 10 or the diffractive optical element 40 effectively suppresses uneven brightness in the illuminated region LZ by having one or more of the following three devices. Is also possible.

  The first device will be described with reference to FIGS. 5 and 6.

  As described above, assuming that the point image Ip is arranged on the virtual plane Pv, the structure to be added to the diffractive optical element 40 is specified. When the projection plane Pp onto which the unit image Iu is projected overlaps the virtual plane Pv, the point image Ip is diffracted at each position of the diffractive optical element 40 to which the designed diffraction characteristics are given, and the single point image Ip is used as the original image. The diffracted light that reproduces the unit image Iu is condensed in a very narrow region on the projection plane Pp as indicated by a dotted line in FIGS.

  On the other hand, as is apparent from FIGS. 5 and 6, the cross-sectional area of the diffracted light beam that is diffracted at each position of the diffractive optical element 40 to reproduce one unit image Iu is smallest on the virtual plane Pv. That is, the area of the unit image Iu reproduced on the virtual plane Pv by the diffracted light is the smallest. Therefore, on the virtual plane Pv, the area where the coherent light for reproducing one unit image Iu is easily separated from the area where the coherent light for reproducing the other unit image Iu is incident. Here, the cross-sectional area of the light beam means an area occupied by the light beam in a cross section orthogonal to the optical axis of the light beam, in other words, an area through which the light beam passes. Further, the optical axis of the light beam means an axis that passes through the center of the light beam.

  Therefore, in the first device of the present embodiment, the virtual plane Pv is shifted from the projection plane Pp along the normal direction nd to the projection plane Pp. That is, the relative positional relationship between the diffractive optical element 40 and the virtual plane Pv when designing the diffraction characteristics of the diffractive optical element 40 is different from the relative positional relationship between the diffractive optical element 40 and the projection plane Pp in actual use. As a result, the area of one unit image Iu projected on the projection plane Pp is the one unit image projected on a certain plane shifted from the projection plane Pp along the normal direction nd of the projection plane Pp. It can be larger than the area of Iu. At least the area of one unit image Iu projected on the projection plane Pp is one unit projected on the plane at the same relative position as the virtual plane Pv when designing the diffraction characteristics with respect to the diffractive optical element 40. It becomes larger than the area of the image Iu.

  Therefore, when such an illuminating device 10 is used, coherent light for reproducing one unit image Iu is incident on a certain plane spaced from the projection plane Pp along the normal direction nd to the projection plane Pp. The region may be separated from the region where the coherent light for reproducing the other unit image Iu is incident. In other words, when such an illuminating device 10 is used, coherent light that reproduces one unit image Iu is incident on a certain surface separated from the projection surface Pp along the normal direction nd to the projection surface Pp. It is also possible that a gap is formed between the area to which the coherent light for reproducing the other unit image Iu is incident.

  In the specific example shown in FIG. 5, the virtual plane Pv when designing the diffraction characteristics is located above the actual projection plane Pp along the normal direction nd. The diffracted light L5 diffracted at each position of the diffractive optical element 40 is condensed before reaching the projection plane Pp, and then approaches the projection plane Pp while diverging. As a result, the area on the projection plane Pp on which the unit image Iu for reproducing one point image Ip is projected can be made much larger than the size of the point image Ip reproduced on the virtual plane Pv.

  Similarly, in the specific example shown in FIG. 6, the virtual plane Pv is located below the actual projection plane Pp along the normal direction nd. The diffracted light L6 diffracted at each position of the diffractive optical element 40 reaches the projection plane Pp before being condensed or converged on the virtual plane Pv. As a result, the area on the projection plane Pp on which the unit image Iu for reproducing one point image Ip is projected can be made much larger than the size of the point image Ip reproduced on the virtual plane Pv.

  According to the first device for the illumination device 10 as described above, a plurality of unit images Iu can be projected onto the projection plane Pp without gaps, and the illuminated area LZ can be uniformly illuminated with uniform brightness. It becomes possible. On the other hand, setting the number of unit images Iu more than necessary can be avoided, and an increase in the number of point images Ip at the time of designing the diffraction characteristics can be effectively suppressed. Accordingly, it is possible to easily manufacture the lighting device 10 that can suppress uneven brightness without increasing the burden on the computer at the time of designing the diffraction characteristics more than necessary.

  As shown in FIGS. 5 and 6, when the virtual plane Pv and the projection plane Pp are displaced along the normal direction nd, the position of the point image Ip on the virtual plane Pv and the projection plane Pp The position of the unit image Iu is shifted along the plane directions of the virtual plane Pv and the projection plane Pp. When manufacturing the diffractive optical element 40 by shifting the virtual plane Pv and the projection plane Pp along the normal direction nd, the arrangement pattern of the point images Ip on the virtual plane Pv is determined in consideration of such shift. Is preferred.

  The second device will be described with reference to FIGS.

  As described above, in the design of the diffraction characteristics when the diffractive optical element 40 is manufactured, the diffraction characteristics for reproducing the point image Ip are to be imparted to the diffractive optical element 40. However, in the actually produced diffractive optical element 40, as shown in FIGS. 7 and 8, coherent light that is diffracted at each position of the diffractive optical element 40 and reproduces one unit image Iu on the projection plane Pp is Depending on the diffusion characteristics of incident light, it becomes diffused light with some diffusion angle. Therefore, the unit image Iu reproduced on the projection plane Pp is a region having a certain area. As shown in FIG. 8, when the projection distance Lp representing the distance from each position of the diffractive optical element 40 to the incident position of the diffracted light diffracted at that position onto the projection plane Pp becomes longer, the projection plane Pp The unit image Iu is projected onto the top. On the contrary, as shown in FIG. 7, when the projection distance Lp is shortened, the unit image Iu is projected onto the projection plane Pp to be small.

  Therefore, it is preferable that a larger number of unit images Iu be projected onto a region where the projection distance Lp in the illuminated region LZ, which tends to be smaller in size, is projected on the projection plane Pp. Therefore, in the second device of the present embodiment, the density of the unit images Iu on the projection plane Pp is changed in the illuminated area LZ. Specifically, the density of the unit images Iu on the projection plane Pp is higher in a certain area than in other areas where the projection distance is longer than that in the certain area. That is, the unit image Iu is reproduced at a high density in a region on the projection plane Pp different from the region on the projection plane Pp where the projection distance Lp tends to be long and the unit image Iu tends to be large.

  As described above, FIG. 3 shows an example of an array pattern of a large number of point images Ip set in the illuminated area LZ. However, in the example shown in FIG. 3, the projection plane Pp is disposed at a position overlapping the virtual plane Pv, and the first device described above is not made. Therefore, when the illumination device 10 performs illumination, the unit image Iu is reproduced in the illuminated area LZ corresponding to each of the point images Ip shown in FIG.

  In the example shown in FIG. 3, the illuminated area LZ has a longitudinal direction dl. The illumination device 10 illuminates the illuminated area LZ from one side in the longitudinal direction dl. In the example shown in FIG. 3, the illuminated area LZ is divided into six divided areas DZ along the longitudinal direction dl for convenience of explaining the density of the unit image Iu. The first to sixth divided regions DZ1 to DZ6 have the same area. The illustrated illuminated region LZ includes first to sixth divided regions DZ1 to DZ6 from one side close to the illumination device 10 in the longitudinal direction dl toward the other side separated from the illumination device 10. The projection distance Lp is the longest in the sixth divided area DZ6 and the shortest in the first divided area DZ1. The projection distance Lp gradually decreases from the sixth divided area DZ6 to the first divided area DZ1. When the projection distance Lp is shortened, the unit image Iu is reproduced on the projection plane Pp as described above.

  On the other hand, as shown in FIG. 3, the number of point images Ip located in each divided region DZ is different. For this reason, when the illumination device 10 performs illumination, the number of unit images Iu projected in each divided region DZ is also different. That is, the density of the unit images Iu representing the number of unit images Iu existing per unit area differs among the plurality of divided regions DZ. In particular, in the illustrated example, the density of the unit image Iu on the projection plane Pp in any one divided region DZ is any other one division in which the projection distance Lp is longer than the one divided region DZ. The density is equal to or higher than the density of the unit image Iu on the projection plane Pp in the region DZ. More specifically, the density of the unit images Iu in each divided area DZ gradually increases from the sixth divided area DZ6 toward the first divided area DZ1.

  According to the example shown in FIG. 3, the density of the unit image Iu reproduced in each divided area DZ obtained by dividing the illuminated area LZ increases as the projection distance Lp to the divided area DZ decreases. To go. That is, the unit image Iu can be reproduced at a higher density in the divided region DZ where the projected area of one unit image Iu is smaller. Thereby, the uneven brightness in the illuminated area LZ on the projection plane Pp can be more effectively suppressed. For example, the unit image Iu can be reproduced without a gap on the projection plane Pp.

  According to the second device for the illumination device 10 as described above, a plurality of unit images Iu can be reproduced on the projection plane Pp without gaps, and the illuminated area LZ can be uniformly illuminated with uniform brightness. It becomes possible. On the other hand, setting the number of unit images Iu more than necessary can be avoided, and an increase in the number of point images Ip at the time of designing the diffraction characteristics can be effectively suppressed. Accordingly, it is possible to easily manufacture the lighting device 10 that can suppress uneven brightness without increasing the burden on the computer at the time of designing the diffraction characteristics more than necessary.

  The third device will be described with reference to FIG.

  As described above, when the actually produced diffractive optical element 40 is used, the coherent light that is diffracted at each position of the diffractive optical element 40 and reproduces one unit image Iu on the projection plane Pp is the incident light. Depending on the diffusion characteristics and the like, the diffused light has a certain diffusion angle. Therefore, the unit image Iu reproduced on the projection plane Pp is generated in a region having a certain area. As shown in FIG. 9, when the incident direction of the coherent light for reproducing the unit image Iu onto the projection plane Pp is inclined with respect to the normal direction nd of the projection plane Pp, the unit image Iu is on the projection plane Pp. Further spread. More specifically, as shown in FIG. 1, the unit image Iu is a projection obtained by projecting the incident direction of coherent light for reproducing the unit image Iu onto the projection plane Pp along the normal direction nd of the projection plane Pp. It extends in the direction dx on the surface Pp.

  If the incident angle θi of the coherent light that reproduces the unit image Iu on the projection plane Pp representing the angle formed by the normal direction nd of the projection plane Pp with respect to the projection plane Pp of the coherent light increases. The unit image Iu is greatly projected on the projection plane Pp. On the other hand, when the incident angle θi decreases, the unit image Iu is projected smaller on the projection plane Pp. In the example shown in FIG. 9, the diffusion angle θd of the diffracted light L91 is the same as the diffusion angle θd of the diffracted light L92. The area of the unit image Iu projected onto the projection plane Pp by the diffracted light L91 with the increased incident angle θi is the area of the unit image Iu projected onto the projection plane Pp with the diffracted light L92 with the decreased incident angle θi. Is bigger than.

  Therefore, it is preferable that a larger number of unit images Iu are projected onto a region where the incident angle θi is smaller in the illuminated region LZ where the size of the unit image Iu projected onto the projection plane Pp tends to be smaller. Therefore, in the third device of the present embodiment, the density of the unit images Iu on the projection plane Pp is changed in the illuminated area LZ. Specifically, the density of the unit images Iu on the projection plane Pp is higher in a certain area than in other areas where the incident angle θi is larger than that in the certain area. That is, the unit image Iu is reproduced at a high density in a region on the projection plane Pp different from the region on the projection plane Pp where the incident angle θi tends to increase and the unit image Iu tends to increase.

  Here, the illuminated area LZ shown in FIG. 3 is from the one side close to the illuminating device 10 in the longitudinal direction dl toward the other side separated from the illuminating device 10, and the first to sixth divided regions DZ1 to DZ1. DZ6 is included. The incident angle θi is the largest in the sixth divided region DZ6 and the smallest in the first divided region DZ1. The incident angle θi gradually decreases from the sixth divided region DZ6 to the first divided region DZ1.

  On the other hand, in the example shown in FIG. 3, the density of the unit images Iu representing the number of unit images Iu existing per unit area is different among the plurality of divided regions DZ. In particular, in the illustrated example, the density of the unit image Iu on the projection plane Pp in any one divided region DZ is the other arbitrary one divided with an incident angle θi larger than that of the one divided region DZ. The density is equal to or higher than the density of the unit image Iu on the projection plane Pp in the region DZ. More specifically, the density of the unit images Iu in each divided area DZ gradually increases from the sixth divided area DZ6 toward the first divided area DZ1.

  According to the example shown in FIG. 3, the density of the unit image Iu reproduced in each divided area DZ obtained by dividing the illuminated area LZ increases as the incident angle θi to the divided area DZ decreases. To go. That is, the unit image Iu can be reproduced at a higher density in the divided region DZ where the projected area of one unit image Iu is smaller. Thereby, the uneven brightness in the illuminated area LZ on the projection plane Pp can be more effectively suppressed. For example, the unit image Iu can be reproduced without a gap on the projection plane Pp.

  According to the third device for the illumination device 10 as described above, a plurality of unit images Iu can be reproduced on the projection plane Pp without gaps, and the illuminated area LZ can be uniformly illuminated with uniform brightness. It becomes possible. On the other hand, setting the number of unit images Iu more than necessary can be avoided, and an increase in the number of point images Ip at the time of designing the diffraction characteristics can be effectively suppressed. Accordingly, it is possible to easily manufacture the lighting device 10 that can suppress uneven brightness without increasing the burden on the computer at the time of designing the diffraction characteristics more than necessary.

  In the example shown in FIG. 3, the projection distance Lp is longer in the divided area DZ where the incident angle θi is larger, and the projection distance Lp is shorter in the divided area DZ where the incident angle θi is smaller. Therefore, the above-described second device and third device are realized at the same time, and it becomes possible to illuminate the illuminated region LZ evenly with uniform brightness.

  In the above-described embodiment, the illumination apparatus 10 includes the coherent light source 20, the shaping optical system 30 that shapes the coherent light emitted from the coherent light source 20, and the diffractive optical that diffracts the coherent light shaped by the shaping optical system 30. Element 40. Then, the diffractive optical element 40 diffracts the coherent light and reproduces the plurality of unit images Iu on the projection plane Pp, thereby illuminating the illuminated area LZ. Coherent light that is diffracted at each position of the diffractive optical element 40 and reproduces one unit image Iu on the projection surface Pp becomes diffused light having a certain diffusion angle depending on the diffusion characteristics of incident light and the like. . Therefore, the unit image Iu is projected onto a region having a certain area on the projection plane Pp. When the projection distance Lp representing the distance from each position of the diffractive optical element 40 to the incident position of the diffracted light diffracted at that position on the projection plane Pp becomes longer, the unit image Iu becomes larger on the projection plane Pp. Played. On the contrary, if the projection distance Lp is shortened, the unit image Iu is reproduced on the projection plane Pp to be small. In the above-described embodiment, the density of the unit image Iu on the projection plane Pp is higher in a certain area than in other areas where the projection distance Lp is longer than that in the certain area. ing. That is, the unit image Iu can be reproduced with high density in a region on the projection plane Pp different from the region on the projection plane Pp where the projection distance Lp tends to be long and the unit image Iu tends to be large. Therefore, uneven brightness in the illuminated area LZ on the projection surface Pp can be effectively suppressed, and the illuminated area LZ can be illuminated with sufficiently uniform brightness.

  In the specific example of the embodiment described above, when the illuminated region LZ is divided into a plurality of divided regions DZ, the density of the unit image Iu on the projection plane Pp in any one divided region DZ is the one The density is equal to or higher than the density of the unit images Iu on the projection plane Pp in any one other divided area DZ in which the projection distance Lp is longer than the divided area DZ. In such an example, the density of the unit image Iu reproduced in each divided area DZ obtained by dividing the illuminated area LZ increases as the projection distance Lp to the divided area DZ decreases. That is, the unit image Iu can be reproduced at a higher density in the divided region DZ where the area of one unit image Iu is smaller. Thereby, the uneven brightness in the illuminated area LZ on the projection plane Pp can be more effectively suppressed. For example, it is possible to reproduce a unit image without a gap on the projection plane Pp.

  In the embodiment described above, the illumination device 10 diffracts the coherent light source 20, the shaping optical system 30 that shapes the coherent light emitted from the coherent light source 20, and the coherent light shaped by the shaping optical system 30. And a diffractive optical element 40. Then, the diffractive optical element 40 diffracts the coherent light and reproduces the plurality of unit images Iu on the projection plane Pp, thereby illuminating the illuminated area LZ. At this time, if the incident direction of the coherent light for reproducing the unit image Iu to the projection plane Pp is inclined with respect to the normal direction nd of the projection plane Pp, the unit image Iu spreads on the projection plane Pp. If the incident angle θi of the coherent light that reproduces the unit image Iu on the projection plane Pp representing the angle formed by the normal direction nd of the projection plane Pp with respect to the projection plane Pp increases, A large unit image Iu is reproduced on Pp. On the contrary, if the incident angle θi is shortened, the unit image Iu is reproduced small on the projection plane Pp. In the embodiment described above, the density of the unit image Iu on the projection plane Pp is such that the incident angle θi of coherent light on the projection plane Pp is larger in a certain area than in the certain area. It is higher than other areas. That is, the unit image Iu can be reproduced at a high density in a region on the projection plane Pp different from the region on the projection plane Pp where the incident angle θi tends to increase and the unit image Iu tends to increase. Therefore, uneven brightness in the illuminated area LZ on the projection surface Pp can be effectively suppressed, and the illuminated area LZ can be illuminated with sufficiently uniform brightness.

  In the specific example of the embodiment described above, when the illuminated region LZ is divided into a plurality of divided regions DZ, the density of the unit image Iu on the projection plane Pp in any one divided region DZ is the one The incident angle θi of the coherent light on the projection plane Pp is larger than the density of the unit image Iu on the projection plane Pp in any other divided area DZ than in the division area DZ. In such an example, the density of the unit image Iu reproduced in each divided area DZ obtained by dividing the illuminated area LZ is increased as the incident angle θi of the coherent light to the projection plane Pp increases to the divided area DZ. It gets higher. That is, the unit image Iu can be reproduced at a higher density in the divided region DZ where the area of one unit image Iu is smaller. Thereby, the uneven brightness in the illuminated area LZ on the projection plane Pp can be more effectively suppressed. For example, the unit image Iu can be reproduced without a gap on the projection plane Pp.

  In the above-described embodiment, the illumination apparatus 10 includes the coherent light source 20, the shaping optical system 30 that shapes the coherent light emitted from the coherent light source 20, and the diffractive optical that diffracts the coherent light shaped by the shaping optical system 30. Element 40. Then, the diffractive optical element 40 diffracts the coherent light and reproduces the plurality of unit images Iu on the projection plane Pp, thereby illuminating the illuminated area LZ. Such a diffractive optical element 40 can be produced as a computer-generated hologram that reproduces a large number of point images Ip arranged on the virtual plane Pv. In this case, a computer-generated hologram can be produced as a fine structure corresponding to the interference pattern of diverging light from each point image Ip and assumed incident light. At this time, the number of point images Ip cannot be increased unconditionally due to restrictions in manufacturing a fine structure, restrictions on the amount of calculation in a computer, and the point images Ip are designed as points. . For this reason, in the actual use of the illuminating device 10, there may be uneven brightness due to the arrangement of the point images Ip in the illuminated area LZ on the projection plane Pp. On the other hand, in the embodiment described above, the virtual plane Pv on which the point image Ip is arranged in the design of the diffractive optical element 40 is shifted along the normal direction nd from the actual projection plane Pp to the projection plane Pp. Can be set. According to the embodiment described above, the region on which the coherent light that reproduces one unit image Iu is incident on the virtual plane Pv that is separated from the projection plane Pp along the normal direction nd of the projection plane Pp is However, on the actual projection plane Pp, the coherent light that reproduces each unit image Iu is more diffused than on the virtual plane Pv. It can be incident on a wider area. Therefore, uneven brightness in the illuminated area LZ on the projection surface Pp can be effectively suppressed, and the illuminated area LZ can be illuminated with sufficiently uniform brightness.

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

  Hereinafter, an example of modification will be described with reference to the drawings. In the following description and the drawings used in the following description, for parts that can be configured in the same manner as the specific examples described above, the same reference numerals as those used for the corresponding parts in the specific examples described above are used, and overlapping descriptions are given. Is omitted.

  As a specific example of the above-described embodiment, an example in which the illumination device 10 illuminates a long and narrow area has been described. The illuminating device 10 may illuminate a region having a predetermined contour, and thus function as a device that displays the predetermined contour. An example of the predetermined contour is an arrow.

  Further, as in the example shown in FIG. 12, the diffractive optical element 40 includes a plurality of element diffractive optical elements 41, and each element diffractive optical element projects a plurality of unit images Iu onto the projection plane Pp. Also good. In this case, each element diffractive optical element 41 may illuminate the entire illuminated area LZ, or may illuminate a part of the illuminated area LZ. When the plurality of element diffractive optical elements 41 illuminate different areas, the areas illuminated by the element diffractive optical elements 41 may overlap each other, or may be shifted from each other so as not to overlap. May be.

10 illuminating device 20 coherent light source 20A first coherent light source 20B second coherent light source 20C third coherent light source 30 shaping optical system 31 first lens 32 second lens 40 diffractive optical element 41 element diffractive optical element dl longitudinal direction dw width direction nd method Line direction Iu Unit image Ip Point image θd Diffusion angle Lp Projection distance θi Incident angle Pv Virtual surface Pp Projection surface LZ Illuminated area DZ Divided area

Claims (8)

An illumination device that illuminates an illuminated area on a projection surface,
A coherent light source,
A shaping optical system for shaping coherent light emitted from the coherent light source;
A diffractive optical element that diffracts the coherent light shaped by the shaping optical system and projects a plurality of unit images on the projection plane, thereby illuminating the illuminated area;
The illumination device, wherein the density of the unit images on the projection plane is higher in a certain area than in other areas where the projection distance is longer than that in the certain area.   When the illuminated area is divided into a plurality of divided areas, the density of the unit image on the projection plane in any one divided area is any other arbitrary projection distance that is longer than the one divided area. The illumination device according to claim 1, wherein the illumination device has a density equal to or higher than the density of the unit images on the projection plane in one divided region.   The illumination device according to claim 1, wherein an incident angle of the coherent light on the projection surface in the certain region is smaller than an incident angle of the coherent light on the projection surface in the other region.   When the illuminated region is divided into a plurality of divided regions, the incident angle of the coherent light on the projection surface in the one arbitrary divided region is the projection angle on the projection surface in the other arbitrary one of the divided regions. The illumination device according to claim 2, wherein the illumination device has an incident angle equal to or smaller than an incident angle of the coherent light. An illumination device that illuminates an illuminated area on a projection surface,
A coherent light source,
A shaping optical system for shaping coherent light emitted from the coherent light source;
A diffractive optical element that diffracts the coherent light shaped by the shaping optical system and projects a plurality of unit images on the projection plane, thereby illuminating the illuminated area;
The density of the unit image on the projection plane is higher in a certain area than in other areas where the incident angle of the coherent light on the projection plane is larger than that in the certain area. .   When the illuminated area is divided into a plurality of divided areas, the density of the unit image on the projection plane in any one divided area is higher than that of the one divided area. The illumination device according to claim 5, wherein the illumination device has a density equal to or higher than the density of the unit image on the projection plane in any one other divided region in which the incident angle becomes large.   The illumination device according to claim 1, wherein the plurality of unit images are separated from each other on a certain surface separated from the projection surface along a normal direction to the projection surface. An illumination device that illuminates an illuminated area on a projection surface,
A coherent light source,
A shaping optical system for shaping coherent light emitted from the coherent light source;
A diffractive optical element that diffracts the coherent light shaped by the shaping optical system and projects a plurality of unit images on the projection plane, thereby illuminating the illuminated area;
On a certain surface separated from the projection surface along the normal direction to the projection surface, a region where coherent light for reproducing one unit image is incident is coherent light for reproducing another unit image. A lighting device spaced from the area.

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