Lighting device

Abstract

To provide a lighting device capable of creating an image with a simple configuration, without using a liquid crystal element and its drive circuit.SOLUTION: A lighting device 10 comprises: a diffractive optical element 50 that includes a microlens array, and receives laser light Ray2 of a visible wavelength emitted by a laser light source 20 and converts the laser light into a light beam group Ray3 corresponding to a dot pattern group to be projected onto a projection surface S; and an optical filter 60 that is arranged on an optical path of the light beam group, and includes an opaque region that does not transmit the light beam group and a transparent region that transmits at least the light beam group.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to a lighting device. [Background technology]

[0002] There is known an illumination device (e.g., a projector) that uses multiple light sources that emit light of different wavelengths, such as RGB light sources, combines the light emitted by each light source using a dichroic mirror, then diffuses it using a homogenizer, and forms an image using a light modulation element such as LCOS (Liquid Crystal On Silicon) (see, for example, Non-Patent Document 1). [Prior art documents] [Non-patent literature]

[0003] [Non-Patent Document 1] Optical Technology Information Magazine "Light Edge" No. 37 (Special Feature: Ushio's New Initiatives Part 2) [Retrieved February 19, 2024], Internet<URL:https: / / www.ushio.co.jp / jp / technology / lightedge / 201206 / 100438.html> Summary of the Invention [Problem to be solved by the invention]

[0004] However, the lighting device described in Non-Patent Document 1 requires a liquid crystal element and a drive circuit for the liquid crystal element, which results in a problem of a large number of parts and a large size.

[0005] The present disclosure has been made to solve such problems, and aims to provide an illumination device that can create an image with a simple configuration without using a liquid crystal element and its drive circuit. [Means for solving the problem]

[0006] The lighting device according to the present disclosure includes a diffractive optical element that includes a microlens array and receives laser light of a visible wavelength emitted by a laser light source and converts the laser light into a group of rays corresponding to a group of dot patterns to be projected onto a projection surface, and an optical filter that is disposed on the optical path of the group of rays and includes an opaque region that does not transmit the group of rays and a transparent region that transmits at least the group of rays.

[0007] With this configuration, an image can be created with a simple configuration without using a liquid crystal element and its drive circuit.

[0008] Furthermore, in the above illumination device, the laser light source may be a plurality of laser light sources that emit laser light of different wavelengths, the optical filter may be a plurality of color filters corresponding to the plurality of laser light sources, the laser light emitted by at least one of the plurality of laser light sources may be incident on the diffractive optical element, and each of the plurality of color filters may include an opaque region that does not transmit a group of light rays emitted by the laser light source corresponding to the color filter and converted by the diffractive optical element, and a transparent region that transmits at least the plurality of light rays.

[0009] Furthermore, in the above illumination device, the laser light source may be a plurality of laser light sources that emit laser light of the same wavelength, the optical filter may be a plurality of polarizing filters corresponding to the plurality of laser light sources, laser light emitted by at least one of the plurality of laser light sources is incident on the diffractive optical element, the plurality of polarizing filters each include an opaque region that does not transmit a group of rays emitted by the laser light source corresponding to the polarizing filter and converted by the diffractive optical element, and a transparent region that transmits at least the plurality of groups of rays, and the plurality of polarizing filters may be arranged with the transmission axes of the respective opaque regions intersecting.

[0010] In the above illumination device, the laser light incident on the diffractive optical element may be parallel light.

[0011] Moreover, the above-described illumination device may further include a lens provided between the plurality of laser light sources and the diffractive optical element, the lens being a lens that collimates the laser light emitted by each of the plurality of laser light sources, and the collimated laser light may be incident on the diffractive optical element.

[0012] In the above illumination device, the laser light incident on the diffractive optical element may be diffused light.

[0013] Moreover, the above-described illumination device may further include a lens provided between the plurality of laser light sources and the diffractive optical element, the lens being a lens that diffuses the laser light emitted by each of the plurality of laser light sources, and the diffused laser light may be incident on the diffractive optical element.

[0014] The illumination device may further include a hologram element provided between the plurality of laser light sources and the diffractive optical element, which receives laser light emitted by at least one of the plurality of laser light sources and forms a specific reconstructed image. [Effects of the Invention]

[0015] The present disclosure makes it possible to provide an illumination device that can create an image with a simple configuration without using a liquid crystal element and its drive circuit. [Brief explanation of the drawings]

[0016] [Figure 1] 1 is a schematic diagram illustrating the configuration of a lighting device 10. FIG. [Figure 2] 2(a) is an enlarged view of the diffractive optical element 50 in FIG. 1 as seen from the direction of arrow AR1, and FIG. 2(b) is a cross-sectional view taken along line AA in FIG. 2(a). [Figure 3] 1 is an example of a group of dot patterns DP projected onto a projection surface S. [Figure 4](a) is an enlarged arrow view of a color filter 60G corresponding to a green laser light source, as viewed from the direction of arrow AR1 in Figure 1, and (b) is an enlarged arrow view of a color filter 60R corresponding to a red laser light source, as viewed from the direction of arrow AR1 in Figure 1. [Figure 5] (a) An example of a green image formed by a dot pattern DP (multiple) formed on the projection surface S, (b) another example of a green image formed by a dot pattern DP (multiple) formed on the projection surface S. [Figure 6] This is an example (modification) in which a hologram element 70 is provided between the laser light source 20 and the diffractive optical element 50. [Figure 7] 10 is an example of a dot pattern formed on the projection surface S and having a shape (for example, a cross shape) corresponding to the reproduced image of the hologram element 70. DETAILED DESCRIPTION OF THE INVENTION

[0017] Hereinafter, an illumination device 10 (image forming device) according to an embodiment of the present disclosure will be described with reference to the accompanying drawings. Corresponding components in each drawing are designated by the same reference numerals, and redundant description will be omitted.

[0018] FIG. 1 is a schematic diagram of the configuration of a lighting device 10. As shown in FIG.

[0019] 1, the illumination device 10 includes a plurality of laser light sources 20 that emit laser light Ray1 having different wavelengths in the visible range. The plurality of laser light sources 20 include, for example, a laser light source 20R that emits red laser light, a laser light source 20G that emits green laser light, and a laser light source 20B that emits blue laser light. The laser light Ray1 emitted by each of the plurality of laser light sources 20 passes through a plurality of lenses 30 provided corresponding to the plurality of laser light sources 20, whereby the laser light Ray1 is converted into parallel light and then enters a dichroic prism 40.

[0020] The laser light Ray1 of each color (each wavelength in the visible range) incident on the dichroic prism 40 is directed along the same optical axis AX 40 The laser beam Ray2 exits the dichroic prism 40 along the axis of the dichroic prism 40. The beam diameter of the laser beam Ray2 exiting the dichroic prism 40 is, for example, 3 mm. The laser beam Ray2 (parallel light) exiting the dichroic prism 40 enters a diffractive optical element 50 (DOE).

[0021] Fig. 2(a) is an enlarged view of the diffractive optical element 50 in Fig. 1 as seen from the direction of arrow AR1, and Fig. 2(b) is a cross-sectional view taken along line AA in Fig. 2(a). The cross-sectional view taken along line BB in Fig. 2(a) is the same as the cross-sectional view taken along line AA.

[0022] The diffractive optical element 50 includes a microlens array and receives laser light Ray1 emitted by each laser light source 20, i.e., laser light Ray2 of each color (each wavelength in the visible range) that passes through the lens 30 and exits the dichroic prism 40. The diffractive optical element 50 converts (diffracts) the laser light Ray2 into a group of rays Ray3 corresponding to the dot pattern to be projected onto the projection surface S. That is, the diffractive optical element 50 diffracts and splits the incident laser light Ray2 in the vertical and horizontal directions. The group of rays Ray3 becomes a bundle of parallel light beams traveling in multiple directions. The diffractive optical element 50 may be, for example, an "ardisia" product by Scivax. Alternatively, the diffractive optical element 50 may be, for example, one described in Japanese Patent No. 7061823.

[0023] As shown in Figures 2(a) and 2(b), the microlens array of the diffractive optical element 50 includes a plurality of lenses 51 arranged two-dimensionally in the X and Y directions. Figures 2(a) and 2(b) show an example in which the lenses 51 are provided on the incident side of the diffractive optical element 50 (the incident side of the laser light Ray2), but this is not limiting. The lenses 51 may be provided on at least one of the incident side and the exit side of the diffractive optical element 50 (the incident side of the laser light Ray2 and the exit side of the laser light Ray2).

[0024] FIG. 3 shows an example of a group of dot patterns DP projected onto a projection surface S.

[0025] The dot pattern is, for example, circular (see FIG. 3), but is not limited to this and may be rectangular or another shape.

[0026] If the pitch P of the lenses 51 (see FIG. 2(b)) is too small compared to the wavelength λ of the laser light emitted by the laser light source 20, diffraction will be difficult to occur. Therefore, as long as there are enough lenses 51 within the distribution angle of the laser light to cause diffraction, the pitch P should be sufficiently larger than the wavelength λ of the laser light, for example, 5 times or more, and preferably 10 times or more.

[0027] The pitch P of the lenses 51 is, for example, 10 μm, and the height H is, for example, 7 μm.

[0028] The material of the diffractive optical element 50 is, for example, PDMS with a refractive index of 1.53.

[0029] The group of rays Ray 3 converted by the diffractive optical element 50 is incident on the color filter 60 .

[0030] The color filter 60 is an optical filter that is disposed on the optical path of the light ray group Ray3 converted by the diffractive optical element 50 and includes opaque regions that do not transmit the light ray group Ray3 and transmissive regions that transmit the light ray group Ray3. The color filter 60 (opaque regions) may be, for example, a dichroic filter. A plurality of color filters 60 are provided corresponding to the plurality of laser light sources 20. For example, the color filters 60 are a color filter 60G for green laser light and a color filter 60R for red laser light. The color filters 60G and 60R are attached to the aperture element in an overlapping state and are disposed on the optical path of the light ray group Ray3 converted by the diffractive optical element 50.

[0031] Figure 4(a) is an enlarged view of a color filter 60G corresponding to a green laser light source, as seen from the direction of arrow AR1 in Figure 1. In Figure 4(a), the arrowed area A1 in the color filter 60G corresponding to the green laser light source represents an opaque area through which the green light ray group Ray3 does not pass. This opaque area is a filter area that reflects or absorbs the green light ray group Ray3. On the other hand, the hatched area HT1 in the color filter 60G represents a transmissive area through which the light ray group Ray3 passes.

[0032] 4(b) is an enlarged view of the color filter 60R corresponding to the red laser light source, as viewed from the direction of the arrow AR1 in FIG. 1. In FIG. 4(b), the circular area A2 in the color filter 60R corresponding to the red laser light source represents an opaque area through which the red light ray group Ray3 does not pass. This opaque area is a filter area that reflects or absorbs the red light ray group Ray3. On the other hand, the hatched area HT2 in the color filter 60R represents a transmissive area through which the light ray group Ray3 passes.

[0033] In the lighting device 10 configured as described above, when the laser light source 20G that emits green laser light is turned on, an image formed on the projection surface S will be described.

[0034] When the laser light source 20G is turned on, the green laser light Ray1 emitted by the laser light source 20G is converted into parallel light by passing through the lens 30, and then enters the dichroic prism 40. The green laser light Ray1 that has entered the dichroic prism 40 is aligned along the same optical axis AX 40 The green laser light Ray1 emitted from the dichroic prism 40 is incident on the diffractive optical element 50. The diffractive optical element 50 receives the green laser light Ray1 emitted by the laser light source 20G, i.e., the green laser light Ray2 (parallel light) that has passed through the lens 30 and is emitted from the dichroic prism 40, and converts the laser light Ray2 into a group of rays Ray3 that corresponds to a group of dot patterns (see FIG. 3) to be projected onto the projection surface S.

[0035] The green light ray group Ray3 converted by the diffractive optical element 50 does not pass through the arrow area A1 (non-transmitting area) of the color filter 60G. On the other hand, the green light ray group Ray3 converted by the diffractive optical element 50 passes through the hatched area H1 (transmitting area) of the color filter 60G and the color filter 60R (circular area A2, hatched area H2). As a result, as shown in FIG. 5(a), a green image (arrow image) composed of a plurality of dot patterns DP is formed (projected) on the projection surface S. FIG. 5(a) shows an example of a green image composed of a plurality of dot patterns DP formed on the projection surface S.

[0036] Next, an image formed on the projection surface S when the laser light source 20R that emits red laser light is turned on will be described.

[0037] When the laser light source 20R is turned on, the red laser light Ray1 emitted by the laser light source 20R is converted into parallel light by passing through the lens 30, and then enters the dichroic prism 40. The red laser light Ray1 that has entered the dichroic prism 40 is aligned along the same optical axis AX 40 The red laser light Ray1 emitted from the dichroic prism 40 is incident on the diffractive optical element 50. The diffractive optical element 50 receives the red laser light Ray1 emitted by the laser light source 20R, i.e., the red laser light Ray2 (parallel light) that has passed through the lens 30 and is emitted from the dichroic prism 40, and converts the laser light Ray2 into a group of rays Ray3 that correspond to a group of dot patterns (see FIG. 3) to be projected onto the projection surface S.

[0038] At this time, the red laser beam Ray2 has the same optical axis as the green laser beam Ray2, and therefore enters the same incident point on the diffractive optical element 50 that is common to red and green.

[0039] The red light beam group Ray3 converted by the diffractive optical element 50 does not pass through the circular area A2 (non-transmitting area) of the color filter 60R. On the other hand, the red light beam group Ray3 converted by the diffractive optical element 50 passes through the hatched area H2 (transmitting area) of the color filter 60R and the color filter 60G (arrow area A1, hatched area H2). As a result, as shown in FIG. 5(b), a red image (stop sign image) composed of a plurality of dot patterns DP is formed (projected) on the projection surface S. FIG. 5(b) shows another example of a green image composed of a plurality of dot patterns DP formed on the projection surface S.

[0040] The distance L1 (see FIG. 1) between the dichroic prism 40 and the diffractive optical element 50 is adjusted so that the group of rays Ray 3 is highly constructive with each other. The distance L1 is, for example, about 12 to 15 mm.

[0041] The distance L2 (see FIG. 1) between the diffractive optical element 50 and the color filter 60 is, for example, a value between 50 and 100 mm. If this distance L2 is short, multiple diffracted beams will overlap, resulting in a blurred projected image. Therefore, if the filter is positioned at a distance that is greater than or equal to the distance at which all of the diffracted beams are separated, the projected image will be sharp.

[0042] The distance L3 (see FIG. 1) between the color filter 60 and the projection surface S may be any appropriate distance.

[0043] As described above, according to this embodiment, by switching the laser light source to be turned on, it is possible to create images with a simple configuration without using a liquid crystal element and its drive circuit.

[0044] Furthermore, by emitting laser beams of different wavelengths on the same optical axis and using a common diffractive optical element 50 for the laser beams of different wavelengths, it is possible to reduce the number of parts and simplify the configuration of the device.

[0045] Next, a modified example will be described.

[0046] In the above embodiment, an example has been described in which the laser light incident on the diffractive optical element 50, i.e., the laser light Ray2 that is converted into parallel light by passing through the lens 30 and emitted from the dichroic prism 40, is parallel light, but the present invention is not limited to this. For example, the laser light incident on the diffractive optical element 50 may be diffused light.

[0047] The inventor has confirmed that when diffused light is incident on the diffractive optical element 50, unevenness (interference) in the image formed by the dot pattern DP projected onto the projection surface S is suppressed more than when parallel light is incident on the diffractive optical element 50, resulting in a better image.

[0048] Furthermore, by adjusting the position of the lens 30 relative to the laser light source 20 and adjusting the degree of diffusion of the laser light incident on the diffractive optical element 50, it is possible to find the diffused light (degree of diffusion) that suppresses image unevenness (interference).

[0049] In the above embodiment, an example was described in which the color filter 60G for green laser light and the color filter 60R for red laser light were used as the color filter 60, but this is not limiting. A color filter for blue laser light may also be used as the color filter 60. Furthermore, a single color filter may also be used as the color filter 60.

[0050] In addition, in the above embodiment, an example was described in which multiple laser light sources 20 (20G, 20R) that emit laser light Ray1 of different wavelengths and multiple color filters 60 (60G, 60R) corresponding to these laser light sources 20 (20G, 20R) were used, but this is not limited to this.

[0051] For example, instead of the laser light source 20, multiple (e.g., two) laser light sources that emit laser light of the same wavelength may be used, and instead of the color filter 60, multiple (e.g., two) polarizing filters that correspond to the polarization directions of the laser light emitted by the multiple laser light sources may be used.

[0052] The polarizing filter is an optical filter that is placed on the optical path of the group of rays Ray3 converted by the diffractive optical element 50 and includes a non-transparent area (e.g., a polarizing film) through which the group of rays Ray3 does not pass and a transparent area through which the group of rays Ray3 passes.

[0053] For example, one polarizing filter includes an opaque region (e.g., arrow region A1 in FIG. 4(a)) through which the group of rays Ray3 does not pass and a transmissive region (e.g., hatched region H1 in FIG. 4(a)) through which the group of rays Ray3 passes. The other polarizing filter includes an opaque region (e.g., circular region A2 in FIG. 4(b)) through which the group of rays Ray3 does not pass and a transmissive region (e.g., hatched region H2 in FIG. 4(b)) through which the group of rays Ray3 passes. Note that one polarizing filter and the other polarizing filter are positioned so that the transmission axes of their polarizing films (opaque regions) intersect (e.g., orthogonal to each other).

[0054] According to this modification, when one laser light source is turned on, an image (arrow image) made up of a plurality of dot patterns DP is formed (projected) on the projection surface S. When the other laser light source is turned on, an image (stop sign image) made up of a plurality of dot patterns DP is formed (projected) on the projection surface S.

[0055] FIG. 6 shows an example (modification) in which a hologram element 70 is provided between the laser light source 20 and the diffractive optical element 50. In FIG.

[0056] The hologram element 70 is a hologram element that receives laser light emitted by at least one of the plurality of laser light sources 20 and forms (reproduces) a specific reproduced image (for example, a reproduced image in the shape of a cross).

[0057] According to this modification, as shown in Fig. 7, it is possible to form a dot pattern on the projection surface S in a shape (for example, a cross shape) corresponding to the reproduced image of the hologram element 70. Fig. 7 shows an example of a dot pattern formed on the projection surface S in a shape (for example, a cross shape) corresponding to the reproduced image of the hologram element 70.

[0058] All the numerical values ​​shown in the above embodiment are merely examples, and it goes without saying that other appropriate numerical values ​​can be used.

[0059] The above-described embodiments are merely examples in all respects. The present disclosure should not be construed as being limited by the description of the above-described embodiments. The present disclosure can be implemented in various other forms without departing from the spirit or main characteristics thereof. [Explanation of symbols]

[0060] 10...Lighting equipment 20, 20B, 20G, 20R...Laser light source 30...Lens 40...Dichroic prism 50...Diffractive optical element 51...Lens 60, 60G, 60R...Color filters 70...Hologram element DP...dot pattern P...Pitch Ray1, Ray2...Laser light Ray3...ray group S…Projection surface

Claims

1. a diffractive optical element including a microlens array, which receives laser light having a wavelength in the visible range emitted by a laser light source and converts the laser light into a group of light rays corresponding to a group of dot patterns to be projected onto a projection surface; an optical filter disposed on an optical path of the group of light rays, the optical filter including a non-transmitting region that does not transmit the group of light rays and a transmitting region that transmits at least the group of light rays.

2. the laser light source is a plurality of laser light sources that emit laser light of different wavelengths, the optical filters are a plurality of color filters corresponding to the plurality of laser light sources, laser light emitted from at least one of the plurality of laser light sources is incident on the diffractive optical element; 2. The illumination device according to claim 1, wherein each of the plurality of color filters includes an opaque region through which a group of light rays emitted by a laser light source corresponding to the color filter and converted by the diffractive optical element does not pass, and a transparent region through which at least the group of light rays passes.

3. the laser light source is a plurality of laser light sources that emit laser light of the same wavelength, the optical filters are a plurality of polarizing filters corresponding to the plurality of laser light sources, laser light emitted from at least one of the plurality of laser light sources is incident on the diffractive optical element; each of the plurality of polarizing filters includes a non-transmitting region through which a group of light rays emitted by a laser light source corresponding to the polarizing filter and converted by the diffractive optical element does not pass, and a transmitting region through which at least the group of light rays passes; The lighting device according to claim 1 , wherein the plurality of polarizing filters are arranged such that the transmission axes of the non-transmitting regions of the polarizing filters intersect with each other.

4. The illumination device according to claim 1 , wherein the laser light incident on the diffractive optical element is parallel light.

5. further comprising a lens provided between the plurality of laser light sources and the diffractive optical element; the lens is a lens that collimates the laser light emitted from each of the plurality of laser light sources, 5. The illumination device according to claim 4, wherein the collimated laser light is incident on the diffractive optical element.

6. 2. The illumination device according to claim 1, further comprising a hologram element provided between the plurality of laser light sources and the diffractive optical element, the hologram element receiving laser light emitted by at least one of the plurality of laser light sources and forming a specific reconstructed image.

7. 3. The illumination device according to claim 2, wherein laser beams having different wavelengths emitted from the plurality of laser light sources are incident on a common diffractive optical element.

8. 8. The lighting device according to claim 7, wherein the opaque areas of the color filters are formed by dichroic filters.

9. 9. The illumination device according to claim 1, wherein the laser light incident on the diffractive optical element is diffused light.

10. further comprising a lens provided between the plurality of laser light sources and the diffractive optical element; the lens is a lens that diffuses the laser light emitted from each of the plurality of laser light sources, The illumination device according to claim 9 , wherein the diffused laser light is incident on the diffractive optical element.

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