JP7068639B2 - Direction display device - Google Patents

Description

The present disclosure relates to a direction display device that displays a direction by illuminating an illuminated area.

Directional display devices that display directions have been used for various purposes, for example, for the purpose of guiding the flow of people (for example, Patent Document 1). As such a direction display device, a plurality of light emitters embedded in the ground or a wall surface, a projector fixed to a ceiling, a wall, or the like can be exemplified. However, embedding a luminous body in the ground involves complicated work and is expensive. On the other hand, the projector must be installed so that the optical axis of the image light emitted from the projector is along the normal direction of the non-display surface. For example, the projector is arranged so as to emit image light directly below toward the ground. Otherwise, it is assumed that the image displayed by the projector will be blurred and the displayed direction cannot be identified. That is, these conventional directional display devices have restrictions on the installation location and have not been widely used.

Special Table 2002-505757 Gazette

The present disclosure has been made in consideration of the above points, and an object of the present invention is to provide a direction display device capable of effectively alleviating restrictions on the installation location and displaying directions with high accuracy.

The direction display device according to the present disclosure is
A device that displays the direction by illuminating the illuminated area.
With a coherent light source,
An orthopedic 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 direction display device according to the present disclosure, the shaping optical system may increase the luminous flux cross-sectional area of the coherent light.

In the direction display device according to the present disclosure,
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 direction display device according to the present disclosure, the at least two element diffractive optical elements may illuminate the same area.

In the direction display device according to the present disclosure, the at least two element diffractive optical elements may illuminate different regions.

In the direction display device according to the present disclosure, the light diffracted by the different element diffractive optical elements may illuminate a different element illuminated area among a plurality of element illuminated areas formed by dividing the illuminated area. good.

In the direction display device according to the present disclosure, the at least two element diffractive optical elements include an optical path of incident light having a maximum incident angle from the diffractive optical element to the illuminated region, and have a normal to the illuminated region. It may be arranged along the direction parallel to the intersection of the plane parallel to the direction and the virtual plane on which the diffractive optical element is located.

In the direction display device according to the present disclosure, the minimum value of the incident angle from the diffractive optical element to the illuminated region may exceed 45 °.

In the direction display device according to the present disclosure, each element diffractive optical element may diffract light into a region including an optical path of the 0th order light emitted from the element diffractive optical element.

It is possible to effectively relax the restrictions on the installation location of the direction display device and display the direction with high accuracy.

FIG. 1 is a diagram for explaining one embodiment according to the present disclosure, and is a perspective view showing a direction display device. FIG. 2 is a diagram showing the positional relationship between the diffractive optical element of the direction display 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 area 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 diagram 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, and is a diagram showing the positional relationship between the diffractive optical element of the direction display device of FIG. 7 and another example of the illuminated region in the xyz coordinate system. 9 is a diagram corresponding to FIG. 3, and is a diagram showing 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 direction display device. FIG. 14 is a diagram corresponding to FIG. 1 and is a diagram showing another modification of the direction display device. 15 (a) to 15 (j) are views showing a modified example of the illuminated area.

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 and the aspect ratios are appropriately changed and exaggerated from those of the actual product for the convenience of illustration and comprehension.

In addition, the terms such as "parallel", "orthogonal", and "identical", 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 used. The interpretation is 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 direction display device 10. The direction display device 10 is a device that displays the direction by illuminating the illuminated area Z. That is, the illuminated area Z includes a shape, a pattern, characters, and the like that can display the direction. The observer can grasp a specific direction by observing the illuminated area Z. In the example shown in FIGS. 1 to 5, the illuminated area Z is located far away from the direction display device 10 and is a quadrangular area having a longitudinal direction dl. The longitudinal direction dl of the illuminated area Z extends in a direction crossing the distance of the direction display device 10. However, the area Z is not limited to the examples shown in FIGS. 1 to 5, and the illuminated area Z can be various areas that can indicate a specific direction. 15 (a) to 15 (j) show other examples of the illuminated area Z. In each of the illuminated areas Z shown in FIGS. 15 (a) to 15 (j), the left-right direction of the paper surface can be displayed to the observer, and in particular, FIGS. 15 (c) to 15 (j). The illuminated area Z shown in the above indicates to the observer the rightward direction of the paper surface in the left-right direction.

The direction display device 10 can be used as a device that indicates a direction for guiding the flow of a person. For example, the direction display device 10 can be used as a device for indicating an exit route at the closing of a theater or as a device for indicating an evacuation route in an emergency. Further, as another application example, the direction display device 10 can be used as a device mounted on a moving body such as a car, a train, a ship, an airplane, etc. and displaying the traveling direction of the moving body.

In particular, the direction display device 10 described here has been devised to display the direction with high accuracy, thereby effectively relaxing the restriction on the installation location of the direction display device 10. Therefore, the direction display device 10 described below is not strongly constrained by the position relative to the illuminated area Z, for example, a position far away from the illuminated area or an incident angle of the illuminated light with respect to the illuminated area Z. It can also be installed in a position where the size becomes large.

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

As shown in FIG. 1, the direction display device 10 includes a coherent light source 20 that projects light and a diffractive optical element 40 that diffracts light emitted from the coherent light source 20. As shown in FIGS. 1 and 2, the direction display 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. There is. In the illustrated example, the light emitted from the coherent light source 20 passes through the shaping optical system 30 and the diffractive optical element 40 and heads toward the illuminated region Z. Hereinafter, each component of the direction display 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 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 corresponding to the coherent light source 20 by the light emitted from each coherent light source 20 are provided. , 40B, 40C, and then superimposed 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 orthopedic optical system 30 enlarges 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 luminous flux cross-sectional area la2 of the coherent light after being emitted from the shaping optical system 30 is larger than the luminous flux cross-sectional 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 the 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 toward the illuminated region Z. Therefore, the illuminated region 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 diffractive 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 area 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 direction display 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 the 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, for example, by resin shaping, the diffractive optical element 40 as a computer-synthesized 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 example, an iterative Fourier transform method is used in the design of the diffractive optical element 40. FIG. 6 is a flowchart showing an example of the processing procedure of the iterative Fourier transform method. First, based on the radiation illuminance distribution on the illuminated region Z to be realized by diffraction by the diffractive optical element 40, the angular spatial distribution of the primary diffracted light intensity from the diffractive optical element 40 is calculated by a computer and randomly. A 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). Then, 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 is 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 lighting intensity distribution on the illuminated area Z (step S4). After that, a Fourier transform is applied to 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 to obtain the complex amplitude distribution of the electric field on the diffractive optical element 40. Calculate (step S5). Next, a complex amplitude distribution is generated in which the light intensity distribution included in the complex amplitude distribution calculated in step S5 is replaced with the angular spatial distribution calculated in step S1 (step S6). Next, using the complex amplitude distribution generated in step S6, the processes after step S3 are repeated.

While 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 direction display 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 direction display device 10 deviates even slightly in the yz plane, the width w of the illuminated region Z greatly fluctuates. Further, even if the illuminated area Z is located in the vicinity of the direction display device 10, if the incident angle α of the illumination light L1 emitted from the direction display device 10 to the illuminated area Z becomes large, the same applies. The width w of the illuminated area Z greatly fluctuates due to a slight deviation in the traveling direction of the illumination light L1. If the width w becomes thicker, it is assumed that the illuminated area Z can no longer be recognized as an elongated area by the observer located in the vicinity of the illuminated area Z. In this case, the observer cannot specify either direction from the shape of the area illuminated by the illumination light. That is, the observer cannot even understand that the lighting for indicating the direction is provided. Due to such a problem, the directional display device that requires high-precision lighting has conventionally been limited in its installation position, and the angle of incidence of the illumination light on the vicinity of the illuminated area Z or the illuminated area Z becomes small. It had to be placed in a position.

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 direction display 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 direction display 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 ± 0.1 ° 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 region Z at a distance of 1 m or more and 120 m or less from the diffractive optical element 40 and the illuminated region 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 direction display device 10 is located far away from the direction display device 10 and is a quadrangular region having a longitudinal direction. However, the longitudinal direction dl of the illuminated area Z extends in a direction away from the direction display 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 real space or angular space, respectively.

As shown in FIG. 10, when the 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'[mm] of the incident position into the illuminated area Z is the two lights L101 and L102. It becomes larger than the minimum deviation amount a [mm] of the optical path of. Specifically, when the optical paths of the two light L101 and L102 are deviated by a [mm] 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'[mm] 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'[mm] on the illuminated area Z is equal to or larger than the actual deviation amount a [mm] 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 diffraction 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 true because the maximum distance between the two lights L101 and L102 on the plane orthogonal to the illuminated area Z is a [mm]. This is the case. Then, when the light 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 a'[1] described above. mm]. Further, as is clear from the equation (1), as the incident angle α [°] increases, the amount of deviation a'[mm] of the incident position on the illuminated region Z also increases, and the incident angle α [°] increases. When it becomes smaller, the amount of deviation a'[mm] 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 lux 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. The one-sided 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 the normal direction to the illuminated region Z. It is a plane parallel to nd. That is, this surface pl1 is located on the emission surface of the diffractive optical element 40 having a maximum angle α [°] with respect to the normal direction nd to the illuminated region Z and the normal direction nd. It includes a linear component la connecting a 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 emission 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 along the crossing line lx. The area on the illuminated area Z will change significantly. Therefore, it is effective to individually adjust the diffraction characteristics of the element diffraction optical elements 41 arranged in the direction of the line of intersection lx in order to illuminate the illuminated area Z with a desired pattern with high accuracy. .. Further, as a premise, it is effective to divide the diffractive optical element 40 in the direction of the line of intersection lux in order to illuminate the illuminated area Z with a desired pattern with high accuracy.

In the example shown in FIG. 7, the plurality of element diffraction 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 lx, 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 the arrangement position thereof. 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 lx, 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 the 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 practically impossible to give such a complicated configuration to an actual direction display device, and it cannot be commercially established. As a result, in a diffractive optical element having a wide diffraction angle range and capable of diffusing illumination light over a wide range, the diffraction efficiency is lowered, and the energy efficiency of the direction display device is lowered accordingly. ..

In order to deal with such a problem, as shown in FIG. 12, the light diffracted by the different element diffractive optical elements 41 divides the illuminated area Z into different elements among the plurality of elements 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 in 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 region Z can be brightly illuminated with a constant energy. Since the burden on the power supply 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 direction display 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 diffractive 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 diffractive 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 direction display device 10 can be further effectively improved.

In one embodiment described above, the direction display device 10 is a device that displays the direction by illuminating the illuminated area Z, and shapes the coherent light source 20 and the coherent light emitted from the coherent light source 20. It includes a shaping optical system 30 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 angle space with high accuracy. As a result, the illuminated region Z far away from the direction display device 10 and the illuminated region where the normal direction nd of the diffractive optical element 40 exceeds a large angle, for example, 45 ° with respect to the normal direction nd1. Z can be illuminated with high accuracy in a desired desired pattern. Then, when the illuminated area Z has a specific shape, for example, an elongated shape, the direction can be displayed. Such a direction display device 10 can select its installation position with a high degree of freedom. Since the degree of freedom of the installation position is improved, the direction display device 10 is used to display the direction even in an environment where it is impossible to suspend the projector or when it is difficult to install an embedded display device. It can be performed.

Further, the power consumption of the direction display device 10 is significantly lower than that of the projector. Therefore, for example, by installing it together with a battery combined with a solar cell or the like, it is possible to meet the demand for electric power. That is, since it is easy to secure a power source, it is possible to improve the degree of freedom in the installation position of the direction display device 10, and it is also possible to carry it.

Such a direction display device 10 can be arranged at a position away from the illuminated area Z where the direction is displayed, for example, as a direction display device that indicates a direction for guiding the flow of people. The operation of the direction display device 10 may be automatically performed based on the detection result of the sensor or the like according to the application. For example, the direction display device 10 may include an illuminance sensor and illuminate the illuminated area Z to display the direction as the brightness of the installation environment of the direction display device 10 changes. Further, the direction display device 10 may include an acceleration sensor capable of detecting an earthquake, and may display the direction by illuminating the illuminated area Z with the detection of the earthquake by the acceleration sensor. Further, the direction display device 10 may include a camera and illuminate the illuminated area Z based on the image pickup result of the camera to display the direction.

Further, in one specific example of the above-described embodiment, the shaping optical system 30 expands the luminous flux cross-sectional 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 cross-sectional area of the luminous flux increases. 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, in the illustrated example, 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 area with high accuracy, and as a result, can illuminate the illuminated area Z with high accuracy and display the direction.

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 in one element diffractive optical element 41 can be reduced. Therefore, the diffraction angle ranges Rθ1 and Rθ2 in each element diffraction optical element 41 can be narrowed. This makes it possible to improve the diffraction efficiency of each element diffraction optical element 41. As a result, the energy efficiency of the direction display device 10 can be improved. That is, the illuminated area Z can be brightly illuminated and the direction can be clearly displayed 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 plane pl1 and the virtual plane pl2 on which the diffractive optical element 40 is located may be arranged along a direction parallel to the intersection line 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 has the arrangement pitch of the adjacent element diffractive optical elements a. Then, only a'expressed by the following equation shifts on 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 the 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 an 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 displacement 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 lx 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 thereof. 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 embodiments, these embodiments are not intended to limit one embodiment. One embodiment described above can be implemented in various other specific examples, and various omissions, replacements, and changes can be made without departing from the gist thereof.

10 Direction display 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 2nd lens 40 Diffraction optical element 41 Element diffractive optical element 41a 1st element diffractive optical element 41b 2nd element diffractive optical element Z illuminated area Ze element illuminated area Ze1 1st element illuminated area Ze2 2nd element illuminated area

Claims (5)

A direction display device that displays the direction by illuminating the illuminated area.
With a coherent light source,
An orthopedic optical system that shapes the coherent light emitted from the coherent light source,
A diffractive optical element that diffracts the coherent light shaped by the shaping optical system and directs it to an illuminated region.
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 illuminated area is divided into two or more element illuminated areas along its longitudinal direction.
The light diffracted by the different element diffractive optical elements of the at least two element diffractive optics illuminates the different element illuminated areas of the two or more element illuminated areas.
The illuminated area is a direction display device having a longitudinal direction in a direction away from the direction display device when observing the illuminated area from the normal direction . The direction display device according to claim 1 , wherein the length of the element illuminated area along the longitudinal direction becomes longer as the element illuminated area is separated from the direction display device. The direction display device according to claim 1 or 2 , wherein the 0th-order light emitted from each of the at least two element diffractive optical elements travels into the element illuminated region illuminated by the element diffractive optical element. The direction display device according to any one of claims 1 to 3 , wherein the orthopedic optical system expands the luminous flux cross-sectional area of the coherent light. The at least two element diffractive optical elements include an optical path of incident light having a maximum incident angle from the diffractive optical element to the illuminated region, and a plane parallel to the normal direction to the illuminated region, and the above. The direction display device according to any one of claims 1 to 4 , which is arranged along a direction parallel to the intersection with the virtual surface on which the diffractive optical element is located.

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