Light-emitting device and luminaire

Abstract

To provide a light-emitting device and a luminaire that have high light utilization efficiency.SOLUTION: A light-emitting device comprise a light source which has a light-emitting element and also has an optical axis extending in a first direction, and an optical element. The optical element has, on its surface, an incidence region that light emitted from the light source impinges on, a first region which reflects first light entering the optical element from the incidence region toward the light source, an annular second region which surrounds the first region, and an annular third region which surrounds the incidence region. The first region reflects part of the first light reaching a center region of the first region overlapping with the light-emitting element viewed from the first direction and part of the first light reaching an outside region located outside the center region toward the light source. The second region reflects second light entering the optical element from the incidence region. The third region reflects second light reflected by the second region toward the second region.SELECTED DRAWING: Figure 6

Description

Technical Field

[0001] Embodiments relate to a light-emitting device and a lighting device.

Background Art

[0002] In a lighting device for dental treatment, the illuminance and the illuminance distribution are defined by ISO standards in order to reliably illuminate the patient's oral cavity and reduce the light reaching the patient's eyes. Even if a lighting device for dental treatment satisfies the ISO standards, it is preferable that the glare felt by the patient can be further reduced. Also, even for a lighting device for dental treatment, reduction of power consumption is required. In order to reduce glare and power consumption, it is effective to reduce stray light and efficiently cause the light emitted from the light-emitting element to reach the target area.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0004] An object of embodiments is to provide a light-emitting device and a lighting device with high light utilization efficiency.

Means for Solving the Problems

[0005] The light-emitting device according to the embodiment includes a light source having an optical axis extending in a first direction and an optical element. The light source has a light-emitting element. The surface of the optical element has an incident region where light emitted from the light source is incident, a first region located on the opposite side of the incident region and larger than the light-emitting element when viewed from the first direction, which reflects the first light that has entered the optical element from the incident region toward the light source, an annular second region surrounding the first region, and an annular third region surrounding the incident region. The first region reflects, toward the light source, the first light among the first light that has reached the central region overlapping the light-emitting element when viewed from the first direction in the first region and the first light that has reached the outer region located outside the central region. The second region reflects the second light that has entered the optical element from the incident region. The third region reflects the second light reflected by the second region toward the second region. The light reflected by the third region is emitted from the second region. The first light and the second light include the light emitted from the light source and the third light that has been reflected by the first region and then reflected by the light source.

[0006] The lighting device according to the embodiment includes one or more of the above-described light-emitting devices.

Advantages of the Invention

[0007] According to the embodiment, a light-emitting device and a lighting device with high light utilization efficiency can be realized.

Brief Description of the Drawings

[0008]

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Mode for Carrying Out the Invention

[0009] <First Embodiment> FIG. 1 is a top view showing the light-emitting device according to the present embodiment. FIG. 2 is a partially enlarged top view showing region II of FIG. 1. FIG. 3 is a bottom view showing the light-emitting device according to the present embodiment. FIG. 4 is a perspective view showing the light-emitting device according to the present embodiment. FIG. 5 is a side view showing the light-emitting device according to the present embodiment. FIG. 6 is a cross-sectional view taken along line VI-VI shown in FIG. 1. FIG. 7 is a side view, a cross-sectional view, and a line showing the cross-section of the light-emitting device according to the present embodiment. FIG. 8 is a side view, a cross-sectional view, and a line indicating a cross-section of the light-emitting device according to the present embodiment.

[0010] Note that each figure is schematic and is emphasized or simplified as appropriate. Also, even for the same component between figures, the dimensional ratios and the aspect ratios do not necessarily exactly match. Further, in some cases, an end view showing only the cut surface is used as a cross-sectional view. The same applies to other figures described later.

[0011] (Schematic configuration of the light-emitting device) Hereinafter, the configuration of the light-emitting device according to the present embodiment will be schematically described. As shown in FIGS. 1 to 8, the light-emitting device 1 according to the present embodiment includes a light source 10 and an optical element 20. The light source 10 has a light-emitting element 11. The light source 10 has an optical axis C extending in the first direction Z.

[0012] Hereinafter, in this specification, for convenience of explanation, an XYZ orthogonal coordinate system is adopted. The direction in which the optical axis C of the light source 10 extends is defined as the "first direction Z". Also, two directions that are orthogonal to the first direction Z and orthogonal to each other are defined as the "second direction X" and the "third direction Y". Further, in the following description, the first direction Z is also referred to as "up", and the reverse direction of the first direction Z is also referred to as "down", but this expression is also for convenience and has nothing to do with the direction of gravity. For example, although the first direction Z is the main traveling direction of the light emitted from the light-emitting device 1, as will be described later, when the light-emitting device 1 is used as a dental treatment lighting device, the light emission direction is often obliquely downward.

[0013] The surface of the optical element 20 has an incident region 24, a first region 21, a second region 22, and a third region 23. As shown in FIG. 9, light L0 emitted from the light source 10 is incident on the incident region 24. The first region 21 is located on the opposite side of the incident region 24. The first region 21 is larger than the light-emitting element 11 when viewed from the first direction Z. The first region 21 reflects the first light L1 that has entered the optical element 20 from the incident region 24 toward the light source 10. When the first region 21 is divided into a central region 21C that overlaps the light-emitting element 11 when viewed from the first direction Z and an outer region 21E that is located outside the central region 21C, the first region 21 reflects both the first light L1 that has reached the central region 21C and the first light L1 that has reached the outer region 21E toward the light source 10.

[0014] The second region 22 is an annular region that surrounds the first region 21. The second region 22 reflects the second light L2 that has entered the optical element 20 from the incident region 24 toward the third region 23. The third region 23 is an annular region that surrounds the incident region 24. The third region 23 reflects the second light L2 reflected by the second region 22 toward the second region 22. The light reflected by the third region 23 exits from the second region 22. The first light L1 and the second light L2 include the light L0 emitted from the light source 10 and the third light L3 that is reflected by the light source 10 after being reflected by the first region 21.

[0015] (Detailed Configuration of the Light-Emitting Device) Next, the configuration of the light-emitting device 1 according to the present embodiment will be described in detail. There are also parts that overlap with the above-described schematic description in the following description. Note that the configuration described below is an example, and the present invention is not limited thereto.

[0016] As shown in FIGS. 4 to 6, the light-emitting device 1 may include a substrate 40 in addition to the above-described light source 10 and optical element 20. The substrate 40 is, for example, a printed circuit board (PCB), and is, for example, an aluminum-based rigid substrate. The light source 10 is mounted on the substrate 40. In FIGS. 3, 7, and 8, the substrate 40 is omitted for easy viewing of the drawings.

[0017] As shown in FIG. 6, the light source 10 may have a sealing member 12 in addition to the light emitting element 11. Electric power is supplied to the light emitting element 11 via the substrate 40. The light emitting element 11 is, for example, a Light Emitting Diode (LED). As shown in FIGS. 2 and 6, the light emitting element 11 is rectangular when viewed from the first direction Z, and is, for example, square. When viewed from the first direction Z, the four sides of the light emitting element 11 extend in the second direction X and the third direction Y.

[0018] The sealing member 12 is disposed on the light emitting element 11. The shape of the sealing member 12 is, for example, a dome shape that protrudes in the first direction Z. As shown in FIG. 10, the sealing member 12 includes a light transmissive portion 12a, a reflective portion 12b, and a wavelength conversion portion 12c. The wavelength conversion portion 12c covers the upper surface of the light emitting element 11. The reflective portion 12b covers the side surface of the light emitting element 11. The light transmissive portion 12a covers the light emitting element 11, the reflective portion 12b, and the wavelength conversion portion 12c. The light transmissive portion 12a is made of a light transmissive resin material. The wavelength conversion portion 12c contains a phosphor. For example, the light emitting element 11 emits blue light, and the phosphor contained in the wavelength conversion portion 12c absorbs a part of the blue light emitted from the light emitting element 11 and emits yellow light. As a result, the light L0 emitted from the light source 10 is a mixed color of blue light and yellow light to become white light. Note that the sealing member 12 may not include the reflective portion 12b.

[0019] As shown in FIGS. 4 to 6, the optical element 20 is fixed to the substrate 40. Since the light source 10 is also fixed to the substrate 40, the optical element 20 is fixed to the light source 10. The shape of the optical element 20 is a substantially rotating body having the optical axis C of the light source 10 as the rotation axis. Therefore, when viewed from the first direction Z, the shape of the optical element 20 is substantially circular. However, as will be described later, there is anisotropy between the second direction X and the third direction Y in the third region 23.

[0020] As shown in FIGS. 3 and 6, the incident region 24 and the third region 23 are disposed on the lower surface of the optical element 20. The incident region 24 is a region centered on the center of the lower surface of the optical element 20, that is, the intersection of the lower surface and the optical axis C. The incident region 24 is a surface including a concave curved surface. A recess 25 is defined on the lower surface of the optical element 20 by the incident region 24. The light source 10 is disposed in the recess 25. As shown in FIG. 6, in the cross section including the optical axis C of the light source 10, it is preferable that the depth D of the recess 25 is larger than the width W of the opening of the recess 25. That is, it is preferable that D>W.

[0021] The third region 23 of the optical element 20 is an annular region surrounding the incident region 24. For example, the third region 23 is away from the incident region 24. The third region 23 is inclined with respect to the substrate 40 so as to be displaced upward as it is away from the incident region 24.

[0022] The third region 23 is divided into a plurality of sub-regions 23a along the second direction X. The shape of each sub-region 23a is a strip shape having the third direction Y as the longitudinal direction. Each sub-region 23a is substantially not curved and is substantially flat in the second direction X. Adjacent sub-regions 23a intersect each other. Each sub-region 23a is curved so as to be continuously displaced in the first direction Z in the third direction Y.

[0023] Therefore, as shown in FIG. 7, among the cross sections of the third region 23, the XZ cross section, that is, the first cross section 23xz including the optical axis C of the light source 10 as the first axis and one second axis orthogonal to the first axis and the first axis, and the cross section parallel to the first cross section 23xz are each a broken line formed by connecting a plurality of line segments. The second axis extends in the second direction X. The black circles in the first cross section 23xz indicate the bending points.

[0024] On the other hand, as shown in FIG. 8, among the cross sections of the third region 23, the YZ cross section, that is, the second cross section 23yz including the first axis and the third axis orthogonal to the first axis and the second axis, and the cross section parallel to the second cross section 23yz are each a continuous curve. The third axis extends in the third direction Y.

[0025] On the lower surface of the optical element 20, in the region between the incident region 24 and the third region 23, two or more, for example, three convex portions 26 may be provided. In this case, through holes are respectively arranged at positions on the substrate 40 corresponding to the convex portions 26. By the three convex portions 26 respectively penetrating through the three through holes of the substrate 40, the optical element 20 is fixed to the substrate 40. In FIGS. 3, 7, and 8, the convex portions 26 are omitted. The optical element 20 may be fixed to the substrate 40 by other configurations.

[0026] As shown in FIGS. 1 to 6, the first region 21 and the second region 22 are arranged on the upper surface of the optical element 20. The first region 21 is a region centered on the center of the upper surface of the optical element 20, that is, the intersection of the upper surface and the optical axis C. In the present embodiment, the first region 21 is a convex curved surface, which may be a part of a spherical surface, an aspherical surface, or a curved surface combining a part of a spherical surface and an aspherical surface. The first region 21 is preferably, for example, a part of an aspherical surface centered on a point within the light-emitting element 11. The first region 21 is, for example, a rotating surface having the optical axis C of the light source 10 as the rotation axis, and the shape of the convex curved surface when viewed from the first direction Z is circular.

[0027] The second region 22 is an annular region surrounding the first region 21 and is in contact with the first region 21. The second region 22 is inclined with respect to the substrate 40 so as to be displaced upward as it moves away from the first region 21. The angle formed between the substrate 40 and the second region 22 is smaller than the angle formed between the substrate 40 and the third region 23. For this reason, as the distance from the optical axis C increases, the second region 22 and the third region 23 approach each other, and the optical element 20 becomes thinner in the first direction Z. The angle formed between the substrate 40 and the second region 22 is the angle formed between the upper surface of the substrate 40 and the line segment connecting the upper end and the lower end of the second region 22 in a cross section including the optical axis C. The angle formed between the substrate 40 and the third region 23 is the angle formed between the upper surface of the substrate 40 and the line segment connecting the upper end and the lower end of the third region 23 in a cross section including the optical axis C.

[0028] The optical element 20 includes a translucent member 29, a metal member 28, and a reflective member 27. The translucent member 29 is made of a translucent material, for example, a translucent resin material, and is formed of, for example, polymethyl methacrylate (PMMA). The translucent member 29 constitutes the main body of the optical element 20.

[0029] The metal member 28 is, for example, aluminum or silver. The metal member 28 continuously covers the translucent member 29 over the entire first region 21 and the portion in the second region 22 that is in contact with the first region 21. When viewed from the first direction Z, the metal member 28 is circular.

[0030] The reflective member 27 is also, for example, a thin aluminum film or a thin silver film. The reflective member 27 covers the translucent member 29 in the third region 23. When viewed from the first direction Z, the reflective member 27 is annular. In the cross-sectional views of FIGS. 7 and 8, the metal member 28 and the reflective member 27 are omitted for the sake of illustration.

[0031] As shown in FIG. 2, when viewed from the first direction Z, the outer edge of the metal member 28 is located outside the outer edge of the incident region 24, the outer edge of the incident region 24 is located outside the outer edge of the first region 21, the outer edge of the first region 21 is located outside the outer edge of the light source 10, and the outer edge of the light source 10 is located outside the outer edge of the light-emitting element 11. Therefore, when viewed from the first direction Z, the first region 21 is larger than the light-emitting element 11.

[0032] (Operation) Next, the operation of the light-emitting device 1 according to the present embodiment will be described. FIG. 9 is an optical path diagram showing the operation of the light-emitting device according to the present embodiment. FIG. 10 is a diagram showing region X of FIG. 9. FIG. 11 is a bottom view of the light-emitting device according to the present embodiment (FIG. 11A), a cross-sectional view taken along line A-A' shown in this bottom view (FIG. 11B) and a cross-sectional view taken along line B-B' (FIG. 11C), a diagram showing a part of the light trajectory from the light-emitting device to the irradiation region (FIGS. 11D and 11E), and a diagram showing the irradiation region on the imaging surface (FIG. 11F).

[0033] As shown in FIG. 10, when power is supplied to the light-emitting element 11 via the substrate 40, the light-emitting element 11 emits, for example, blue light. The phosphor contained in the wavelength conversion unit 12c absorbs part of this blue light and emits, for example, yellow light. As a result, the blue light and the yellow light are mixed, and white light L0 is emitted from the light source 10.

[0034] As shown in FIGS. 9 and 10, the light L0 emitted from the light source 10 enters the translucent member 29 of the optical element 20 through the incident region 24. When the incident region 24 is a concave curved surface, the incident angle of the light L0 with respect to the incident region 24 is stably smaller than the critical angle, so the incident efficiency is high.

[0035] The light L0 that has entered the optical element 20 from the incident region 24 mainly travels toward the first region 21 and the second region 22. Of the light L0, the light traveling toward the first region 21 is referred to as the first light L1, and the light traveling toward the second region 22 is referred to as the second light L2.

[0036] The first region 21 is a convex curved surface, and since the metal member 28 covering the translucent member 29 is disposed in the first region 21, the first region 21 retroreflects the first light L1. That is, most of the first light L1 is reflected toward the light source 10 at the interface between the translucent member 29 and the metal member 28 in the first region 21. Therefore, both the first light L1 that has reached the central region 21C of the first region 21 and the first light L1 that has reached the outer region 21E are reflected toward the light source 10. When the first region 21 is a rotating surface having the optical axis C of the light source 10 as the rotation axis, the first light L1 is reflected toward the light-emitting element 11 in the light source 10, so the accuracy of retroreflection is high.

[0037] Since the second light L2 enters the second region 22 at an incident angle greater than the critical angle, it is totally reflected in the second region 22. The second light L2 totally reflected by the second region 22 travels toward the third region 23. Since a reflecting member 27 covering the light-transmissive member 29 is disposed in the third region 23, the third region 23 reflects the second light L2 emitted from the second region 22 back toward the second region 22. Since the second light L2 reaching the second region 22 from the third region 23 enters the second region 22 at an incident angle smaller than the critical angle, it is emitted to the outside of the optical element 20 through the second region 22.

[0038] On the other hand, the first light L1 retroreflected by the first region 21 and returned to the light source 10 is reflected at the light source 10. More specifically, the first light L1 is reflected at the surface of the sealing member 12, scattered by the phosphor contained in the wavelength conversion unit 12c, converted into light of a different wavelength by the phosphor contained in the wavelength conversion unit 12c and then emitted, reflected at the surface of the light emitting element 11, or reflected by other members constituting the light source 10. The light reflected, scattered, emitted, etc. at the light source 10 in this way is collectively referred to as "third light L3".

[0039] The third light L3 becomes part of the first light L1 and the second light L2 and is reused. In other words, the first light L1 and the second light L2 each include the light emitted from the light source 10 when the light emitting element 11 emits light and the third light L3 reflected at the light source 10 after being reflected in the first region 21. The light emitted from the optical element 20 through the second region 22 is referred to as "fourth light L4". The fourth light L4 is the emitted light of the light emitting device 1.

[0040] As shown in FIG. 11A, the third region 23 is divided into a plurality of sub-regions 23a along the second direction X. Therefore, among the third region 23, the first cross section 23xz parallel to the second direction X as shown in FIG. 7 is a broken line, and the second cross section 23yz parallel to the third direction Y as shown in FIG. 8 is a continuous curve. Thus, the shape of the third region 23 has anisotropy between the second direction X and the third direction Y.

[0041] Therefore, as shown in FIGS. 11B and 11D, for the second direction X, since the reflection angle for each sub-region 23a is slightly different, the fourth light L4 is diffused. On the other hand, as shown in FIGS. 11C and 11E, for the third direction Y, the fourth light L4 emitted from the optical element 20 along the first direction Z is not much diffused and converges on the imaging surface 200.

[0042] As a result, the fourth light L4 spreads along the second direction X on the imaging surface 200. As a result, as shown in FIG. 11F, on the imaging surface 200, the shape of the irradiation region 201 of the fourth light L4 is a substantially rectangular shape in which the length Lx along the second direction X is longer than the length Ly along the third direction Y.

[0043] If the third region 23 has no anisotropy as described above and is a perfect rotating body, the shape of the irradiation region 201 on the imaging surface 200 is the shape reflecting the light emitting element 11. For example, when the shape of the light emitting element 11 is square as viewed from the first direction Z, the shape of the irradiation region 201 is also substantially square.

[0044] (Effect) In the light emitting device 1 according to the present embodiment, the light L0 emitted from the light source 10 enters the optical element 20 from the incident region 24, is totally reflected in the second region 22, is reflected in the third region 23, and exits from the optical element 20 through the second region 22. Thereby, an irradiation region 201 having a predetermined shape can be formed on the imaging surface 200.

[0045] Then, in the first region 21, by reflecting both the first light L1 that has reached the central region 21C and the first light L1 that has reached the outer region 21E toward the light source 10, these lights are reflected by the light source 10 and can be reused. Therefore, the light emitting device 1 has less stray light and high light utilization efficiency. Stray light refers to light that irradiates a region outside the irradiation region 201.

[0046] In the light-emitting device 1, the first region 21 retroreflects the first light L1. As a result, substantially the entire first light L1 is reflected toward the light source 10, so that stray light is further reduced and the light utilization efficiency is further improved.

[0047] Furthermore, by forming the first region 21 as a convex curved surface, the accuracy of reflecting the first light L1 toward the light source 10 is improved. Also, by forming this curved surface as a rotating surface having the optical axis C of the light source 10 as the rotation axis, most of the first light L1 can be reflected toward the light-emitting element 11. As a result, the reflection accuracy of the first light L1 by the first region 21 is further improved. This also reduces stray light and improves the light utilization efficiency.

[0048] Furthermore, by making the incident region 24 concave and disposing the light source 10 in the recess 25 defined by the incident region 24, the light-emitting device 1 can be miniaturized in the first direction Z. Also, in a cross section including the optical axis C of the light source 10, by making the depth D of the recess 25 larger than the width W of the opening of the recess 25, the light-emitting device 1 can also be miniaturized in the XY plane. Further, by forming the incident region 24 with a concave curved surface, the incident angle when the light L0 emitted from the light source 10 enters the incident region 24 becomes small, and the light L0 can be efficiently introduced into the optical element 20. This also reduces stray light and improves the light utilization efficiency.

[0049] Furthermore, since the optical element 20 has a metal member 28 that covers the light-transmitting member 29 in the first region 21, the first light L1 can be surely reflected in the first region 21. Also, since the metal member 28 continuously covers a part of the first region 21 and the second region 22, the second light L2 can be surely reflected even in a region where the incident angle of the second light L2 in the second region 22 is relatively small. Further, since the optical element 20 has a reflecting member 27 that covers the light-transmitting member 29 in the third region 23, the second light L2 can be surely reflected in the third region 23.

[0050] Furthermore, among the cross-sections of the third region 23, the first cross-section 23xz parallel to the XZ plane is formed as a broken line connected by a plurality of line segments, and the second cross-section 23yz parallel to the YZ plane is formed as a continuous curve, whereby the irradiation region 201 on the imaging surface 200 can be expanded along the second direction X. Thereby, the ratio of the length Lx in the second direction X to the length Ly in the third direction Y of the irradiation region 201 can be arbitrarily adjusted.

[0051] Furthermore, since the light source 10 has the wavelength conversion unit 12c containing the phosphor, the options for the color of the light L0 increase. For example, white light L0 can be realized by using an LED that emits blue light.

[0052] Note that the shape of the incident region 24 may be a shape combining a concave surface and a convex surface. For example, a convex portion protruding toward the light source 10 may be provided at the top of the concave portion 25. Thereby, since the light incident on the convex portion is condensed toward the first region 21, the first light L1 and the second light L2 can be separated in the incident region 24.

[0053] <Modification Example of the First Embodiment> FIG. 12 is an optical path diagram showing the light-emitting device according to this modification example. In this modification example, the same reference numerals are given to the same components as in the first embodiment, and detailed description thereof is omitted. The same applies to other embodiments and their modification examples described later.

[0054] As shown in FIG. 12, the light-emitting device 1a according to this modification example is different in that the metal member 28 is disposed only in the first region 21 and not in the second region 22 as compared with the light-emitting device 1 according to the first embodiment.

[0055] When the positional accuracy between the light source 10 and the optical element 20 and the shape accuracy of the translucent member 29 are sufficiently high and the second light L2 incident from the incident region 24 can be surely totally reflected in the second region 22, the same effects as those of the first embodiment can be obtained also by this modification example. The configurations, operations, and effects other than the above in this modification example are the same as those of the first embodiment.

[0056] <Second Embodiment> FIG. 13 is an optical path diagram showing the light-emitting device according to the present embodiment. FIG. 14 is a partially enlarged optical path diagram showing region XIV of FIG. 13. FIG. 15 is a top view showing the first region of the light-emitting device according to the present embodiment. FIG. 16 is a diagram showing the trajectory of light incident on the corner cube.

[0057] As shown in FIGS. 13 to 16, in the light-emitting device 2 according to the present embodiment, the first region 31 of the optical element 20 has a plurality of corner cubes 31a. Each corner cube 31a is composed of three reflecting surfaces that are perpendicular to each other. In the first region 31, the corner cubes 31a are arranged without gaps. The first region 31 including the plurality of corner cubes 31a is substantially flat as a whole. Further, a metal member 38 is provided in the first region 31. The metal member 38 covers the light-transmissive member 29 in the first region 31. The metal member 38 is, for example, an aluminum thin film or a silver thin film. In FIGS. 13 and 15, the metal member 38 is omitted.

[0058] In the light-emitting device 2, the first light L1 incident from the incident region 24 into the optical element 20 enters one of the corner cubes 31a in the first region 31. As shown in FIG. 16, the first light L1 incident on the corner cube 31a is usually sequentially reflected by the three reflecting surfaces constituting the corner cube 31a and is emitted in the direction opposite to the incident direction. Depending on the incident direction of the first light L1, it may be reflected by only two or one plane and emitted in the direction opposite to the incident direction.

[0059] As a result, when the first region 31 is divided into a central region that overlaps with the light-emitting element 11 when viewed from the first direction Z and an outer region located outside the central region, the first region 31 can reflect both the first light L1 that has reached the central region and the first light L1 that has reached the outer region toward the light source 10. For example, the first region 31 retroreflects the first light L1 toward the light source 10. The configurations, operations, and effects other than those described above in the present embodiment are the same as those in the first embodiment.

[0060] <Modification Example of the Second Embodiment> FIG. 17 is an optical path diagram showing a light-emitting device according to this modification example. As shown in FIG. 17, in the light-emitting device 2a according to this modification example, the virtual curve connecting the vertices of the plurality of corner cubes 31a arranged in the first region 31 is a convex curve, and a metal member 38 is provided in the first region 31. However, in FIG. 17, the metal member 38 is omitted. Even with this, the same effects as in the second embodiment can be obtained. The configurations, operations, and effects other than those described above in the present embodiment are the same as those in the second embodiment.

[0061] <Third Embodiment> FIG. 18 is a perspective view showing a lighting device according to this embodiment. FIG. 19 is an optical path diagram showing the operation of the lighting device according to this embodiment. This embodiment is a lighting device that uses the above-described light-emitting device.

[0062] As shown in FIG. 18, the lighting device 100 according to this embodiment includes one or more light-emitting devices 1 according to the first embodiment. Note that the lighting device 100 may include, instead of the light-emitting device 1, a light-emitting device 1a according to a modification example of the first embodiment, a light-emitting device 2 according to the second embodiment, or a light-emitting device 2a according to a modification example of the second embodiment.

[0063] The lighting device 100 is a lighting device for dental treatment. In the lighting device 100, a frame-shaped frame 101 and six light-emitting devices 1 are provided. The surface of the frame 101 viewed from the Z side in the first direction is inclined in the direction opposite to the first direction Z toward the center of the frame 101. The six light-emitting devices 1 are mounted on the frame 101, and power is supplied through the frame 101. Note that the number of the light-emitting devices 1 is not limited to six and may be one or more.

[0064] As shown in FIG. 19, the optical axes C of the plurality of light-emitting devices 1 are inclined with respect to each other and intersect at the imaging surface 200. Thereby, the irradiation regions 201 formed by the plurality of light-emitting devices 1 overlap each other. That is, the plurality of light-emitting devices 1 form one irradiation region 201. The distance from the lighting device 100 to the imaging surface 200 is 700 mm according to ISO9680 and 650 mm to 700 mm according to JIS T5753 compliant with ISO9680.

[0065] Note that since the optical axes C are inclined with respect to each other among the six light-emitting devices 1, the XYZ orthogonal coordinates shown in FIGS. 18 and 19 do not exactly match the XYZ orthogonal coordinates shown in FIGS. 1 to 17. In FIGS. 18 and 19, the first direction Z indicates the direction in which the central axis of the frame 101 extends. The same applies to each modification described later.

[0066] According to the present embodiment, by adjusting the positional relationship between the patient and the lighting device 100, the irradiation region 201 of the lighting device 100 is positioned at the patient's mouth, the second direction X is made to coincide with the patient's left-right direction, and the third direction Y is made to coincide with the patient's up-down direction. Thereby, the oral cavity of the patient can be illuminated by the rectangular irradiation region 201 whose longitudinal direction is the patient's left-right direction.

[0067] Then, as described above, since the light-emitting device 1 has less stray light, the light reaching the patient's eyes is less, and the patient can be less likely to feel dazzled. Further, since the light-emitting device 1 has high light utilization efficiency, the lighting device 100 also has high light utilization efficiency. As a result, power-saving and high-illuminance lighting can be realized.

[0068] <First Variation of the Third Embodiment> FIG. 20 is a perspective view showing the lighting device according to this variation, as viewed from the Z side in the first direction. FIG. 21 is a perspective view showing the lighting device according to this variation, as viewed from the side opposite to the Z side in the first direction. FIG. 22 is a side view showing the lighting device according to this variation.

[0069] As shown in FIGS. 20 to 22, in the lighting device 110 according to this variation, an annular frame 111 and six light emitting devices 1 are provided. The frame 111 has an upper surface 111a facing the Z side in the first direction and a lower surface 111b facing the side opposite to the Z side in the first direction. The surface 111a of the frame 111 as viewed from the Z side in the first direction is inclined in the direction opposite to the first direction Z toward the center of the frame 111. That is, the upper surface 111a is displaced in the first direction Z as it moves away from the central axis C111 of the frame 111.

[0070] The six light emitting devices 1 are arranged on the upper surface 111a of the frame 111. However, the six light emitting devices 1 are not arranged at equal intervals along the outer periphery of the frame 111, but are arranged in three on each of the regions on both sides of the upper surface 111a in the second direction X. The lower surface of the substrate 40 of each light emitting device 1 is fixed to the upper surface 111a of the frame 111. The configurations, operations, and effects other than those described above in this variation are the same as those in the third embodiment.

[0071] <Second Variation of the Third Embodiment> FIG. 23 is a perspective view showing the lighting device according to this variation, as viewed from the Z side in the first direction. FIG. 24 is a perspective view showing the lighting device according to this variation, as viewed from the side opposite to the Z side in the first direction. FIG. 25 is a side view showing the lighting device according to this variation.

[0072] As shown in FIGS. 23 to 25, in the lighting device 120 according to this modification example, an annular frame 121 and six light-emitting devices 1 are provided. The surface 121a of the frame 121 viewed from the Z side in the first direction and the surface 121b of the frame 121 viewed from the direction opposite to the first direction Z are inclined in the direction opposite to the first direction Z toward the center of the frame 121. That is, the upper surface 121a and the lower surface 121b are displaced in the first direction Z as they are farther from the central axis C121 of the frame 121. The frame 121 is divided into eight sections along the outer periphery of the frame 121, and through-holes 129 are provided in six sections excluding the two sections arranged on both sides in the third direction Y, respectively.

[0073] The outer peripheral portion of the upper surface of the optical member 20 of each light-emitting device 1 is fixed to the area surrounding the through-hole 129 on the lower surface 121b of the frame 121. Thereby, the light-emitting device 1 is arranged on the lower surface 121b side of the frame 121, and the optical member 20 of the light-emitting device 1 is exposed from the upper surface 121a of the frame 121 at the through-hole 129. The configurations, operations, and effects other than those described above in this modification example are the same as those in the third embodiment.

[0074] <Third Modification Example of the Third Embodiment> FIG. 26 is a perspective view showing the lighting device according to this modification example, as viewed from the Z side in the first direction. FIG. 27 is a perspective view showing the lighting device according to this modification example, as viewed from the side opposite to the first direction Z. FIG. 28 is a side view showing the lighting device according to this modification example. FIG. 29 is a partially enlarged cross-sectional view showing the lighting device according to this modification example.

[0075] As shown in FIGS. 26 to 29, in the lighting device 130 according to this modification example, an annular frame 131, an annular flat substrate 132, and six light-emitting devices 1 are provided. The configuration of the frame 131 is the same as the configuration of the frame 121 in the second modification example. The optical member 20 of the light-emitting device 1 is fixed to the lower surface 131b of the frame 131 and is exposed from the upper surface 131a of the frame 131 at the through-hole 139.

[0076] The flat substrate 132 is located below the frame 131 and is fixed to the frame 131. When viewed from the first direction Z, the outer periphery of the flat substrate 132 is disposed inside the outer periphery of the frame 131. That is, when viewed from the first direction Z, the entire flat substrate 132 is hidden behind the frame 131. The upper surface 132a and the lower surface 132b of the flat substrate 132 are flat and parallel to the XY plane.

[0077] In this modified example, the substrate 40 is not provided in the light-emitting device 1, and the light source 10 is fixed to the upper surface 132a of the flat substrate 132. The optical member 20 is not fixed to the flat substrate 132 but is fixed to the frame 131. It is preferable that a part of the optical member 20 is in contact with the flat substrate 132. However, the optical member 20 may be separated from the flat substrate 132. As described above, since the light source 10 is fixed to the flat substrate 132, the optical member 20 is fixed to the frame 131, and the flat substrate 132 is fixed to the frame 131, the positional relationship between the light source 10 and the optical member 20 is fixed in each light-emitting device 1.

[0078] Since the upper surface 132a of the flat substrate 132 is flat, the optical axes C of the light sources 10 are parallel to each other and parallel to the central axis C131 of the frame 131. On the other hand, since the surface 131a of the frame 131 viewed from the first direction Z side is inclined in the direction opposite to the first direction Z, the main directions of the light L4 emitted from the six light-emitting devices 1 are inclined to each other. The inclination angle θ of the main direction of the light L4 with respect to the optical axis C of the light source 10 is, for example, 0 degrees to 22 degrees. The light L4 emitted from each light-emitting device 1 intersects at the imaging surface 200. The configurations, operations, and effects other than the above in this modified example are the same as those in the third embodiment.

[0079] <First Comparative Example> FIG. 30 is an optical path diagram showing a light-emitting device according to this comparative example. As shown in FIG. 30, in the light-emitting device 301 according to this comparative example, the upper surface of the optical element 320 is continuously displaced upward as it moves away from the optical axis C. For this reason, the first region 321 of the optical element 320 corresponding to the first region 21 in the light-emitting device 1 according to the first embodiment has a continuous surface with the second region 322. That is, the first region 321 is not convex, and no corner cube is formed. Furthermore, no metal member is provided.

[0080] In the light-emitting device 301, the light emitted from the light source 10, traveling through the optical element 320, and reaching the first region 321 is not reflected in the first region 321 and is emitted outside the optical element 320 through the first region 321. This light becomes stray light L301, and a part of it reaches the patient's eyes. For this reason, the patient is likely to feel dazzle. Also, since the light reaching the irradiation region 201 decreases by the amount of stray light generated, the light utilization efficiency is low.

[0081] <Second Comparative Example> FIG. 31 is an optical path diagram showing the light-emitting device according to this comparative example. As shown in FIG. 31, in the light-emitting device 302 according to this comparative example, a metal member 328 is provided in the first region 321. Thereby, the stray light L301 is reduced.

[0082] However, a part of the light reflected by the metal member 328 is totally reflected in the incident region 324. Therefore, the light that enters the optical element 320 from the incident region 324, is reflected by the metal member 328, and is totally reflected by the incident region 324 is reflected by the second region 322, reflected by the third region 323, and emitted from the light-emitting device 302 through the second region 322, becoming stray light L302. When a part of the stray light L302 reaches the patient's eyes, the patient is likely to feel dazzle. Also, since the light utilization efficiency is low due to the generation of stray light.

[0083] <Third Comparative Example> FIG. 32 is an optical path diagram showing the light-emitting device according to this comparative example. As shown in FIG. 32, in the light-emitting device 303 according to this comparative example, a light-shielding member 338 is provided in the first region 321. Thereby, the stray light L301 shown in FIG. 30 is reduced. Further, since substantially no light is reflected by the light-shielding member 338, the stray light L302 shown in FIG. 31 is also reduced. However, since the light that has reached the first region 321 is absorbed by the light-shielding member 338, the light utilization efficiency is low.

[0084] <Test Example> The light-emitting device 1 according to the first embodiment, the light-emitting device 301 according to the first comparative example, the light-emitting device 302 according to the second comparative example, and the light-emitting device 303 according to the third comparative example were actually manufactured, supplied with the same power to emit light, and the illuminance at the center of the irradiation region 201 was measured. When the central illuminance of the light-emitting device 301 was set to 100.0%, the central illuminance of the light-emitting device 302 was 109.8%, the central illuminance of the light-emitting device 303 was 95.7%, and the central illuminance of the light-emitting device 1 was 117.2%. Thus, the central illuminances of the light-emitting devices 301, 302, and 303 were lower than the central illuminance of the light-emitting device 1.

[0085] Each of the above-described embodiments and modifications thereof is an example embodying the present invention, and the present invention is not limited to these embodiments and modifications. For example, in each of the above-described embodiments and modifications, those in which some components are added, deleted, or changed are also included in the present invention. Further, each of the above-described embodiments and modifications can be implemented in combination with each other.

[0086] The present invention includes the following aspects.

[0087] (Appendix 1) A light source having a light-emitting element and having an optical axis extending in a first direction, An optical element, And comprising, The surface of the optical element is, An incident region where the light emitted from the light source is incident, A first region that is located on the opposite side of the incident region, is larger than the light-emitting element when viewed from the first direction, and reflects the first light that has entered the optical element from the incident region toward the light source. The first region reflects, toward the light source, the first light that has reached a central region that overlaps with the light-emitting element when viewed from the first direction in the first region among the first light, and the first light that has reached an outer region located outside the central region. A second annular region that surrounds the first region and reflects second light that has entered the optical element from the incident region. A third annular region that surrounds the incident region and reflects the second light reflected by the second region back toward the second region. It has The light reflected in the third region is emitted from the second region. The first light and the second light include the light emitted from the light source and the third light that is reflected by the light source after being reflected in the first region. Light-emitting device.

[0088] (Appendix 2) The first region is the light-emitting device according to Appendix 1 that retroreflects the first light.

[0089] (Appendix 3) The first region is the light-emitting device according to Appendix 1 or 2 that is a convex curved surface.

[0090] (Appendix 4) The convex curved surface is a rotating surface that has the optical axis of the light source as the rotation axis, which is the light-emitting device according to Appendix 3.

[0091] (Appendix 5) The first region is the light-emitting device according to Appendix 1 or 2 that has a plurality of corner cubes.

[0092] (Appendix 6) The plurality of corner cubes are arranged convexly with respect to the second region, which is the light-emitting device according to Appendix 5.

[0093] (Supplementary Note 7) The light incident region is concave, and the light source is disposed within the concave portion of the optical element defined by the light incident region, and is the light emitting device according to any one of Supplementary Notes 1 to 6.

[0094] (Supplementary Note 8) The light incident region includes a curved surface, and is the light emitting device according to Supplementary Note 7.

[0095] (Supplementary Note 9) In a cross section including the optical axis of the light source, the depth of the concave portion is greater than the width of the opening of the concave portion, and is the light emitting device according to Supplementary Note 7 or 8.

[0096] (Supplementary Note 10) The optical element has a light transmissive member, and a metal member covering the light transmissive member in the first region, and is the light emitting device according to any one of Supplementary Notes 1 to 9.

[0097] (Supplementary Note 11) The metal member continuously covers the first region and a part of the second region, and is the light emitting device according to Supplementary Note 10.

[0098] (Supplementary Note 12) The optical element has a light transmissive member, and a reflective member covering the light transmissive member in the third region, and is the light emitting device according to any one of Supplementary Notes 1 to 9.

[0099] (Supplementary Note 13) Among the cross sections of the third region, with the optical axis of the light source as the first axis, a first cross section including the first axis and one second axis orthogonal to the first axis, and cross sections parallel to the first cross section are each a broken line formed by connecting a plurality of line segments, Among the cross sections of the third region, a second cross section including the first axis, and a third axis orthogonal to the first axis and the second axis, and cross sections parallel to the second cross section are each a continuous curve, and is the light emitting device according to any one of Supplementary Notes 1 to 12.

[0100] (Appendix 14) The light source is the light-emitting device according to any one of Appendices 1 to 13, further having a wavelength conversion section.

[0101] (Appendix 15) The lighting device includes one or more light-emitting devices according to any one of Appendices 1 to 14.

[0102] (Appendix 16) The lighting device according to Appendix 15, which is for dental treatment.

Description of Reference Numerals

[0103] 1, 1a, 2, 2a Light-emitting device 10 Light source 11 Light-emitting element 12 Sealing member 12a Translucent portion 12b Reflective portion 12c Wavelength conversion section 20 Optical element 21 First region 21C Central region 21E Outer region 22 Second region 23 Third region 23a Sub-region 23xz First cross-section 23yz Second cross-section 24 Incident region 25 Concave portion 26 Convex portion 27 Reflective member 28 Metal member 29 Translucent member 31 First region 31a Corner cube 38 Metal member 40 Substrate 100 Lighting device 101 Frame 110 Lighting device 111 Frame 111a Upper surface 111b Lower surface 120 Lighting device 121 Frame 121a Upper surface 121b Lower surface 129 Through-hole 130 Lighting device 131 Frame 131a Upper surface 131b Lower surface 132 Flat substrate 132a Upper surface 132b Lower surface 139 Through-hole 200 Imaging plane 201 Irradiation area 301, 302, 303 Light-emitting device 320 Optical element 321 First region 322 Second region 323 Third region 324 Incident region 328 Metal member 338 Light-shielding member C Optical axis C111 Central axis of frame 111 C121 Central axis of frame 121 C131 Central axis of frame 131 D Depth of recess 25 L0 Light L1 First light L2 Second light L3 Third light L4 Fourth light L301, L302 Stray light Lx Length along the second direction X of the irradiation area 201 Ly Length along the third direction Y of the irradiation area 201 W Width of the opening of the recess 25 X Second direction Y Third direction Z First direction θ Inclination angle of the main direction of the light L4 with respect to the optical axis C of the light source 10

Claims

1. A light source having a light emitting element and having an optical axis extending in a first direction, An optical element, Comprising, The surface of the optical element is, An incident region where the light emitted from the light source is incident, A first region located on the opposite side of the incident region, larger than the light emitting element when viewed from the first direction, and reflecting the first light that has entered the optical element from the incident region toward the light source. Among the first light, the first light that has reached the central region overlapping the light emitting element when viewed from the first direction in the first region and the first light that has reached the outer region located outside the central region are reflected toward the light source. The first region, A second annular region surrounding the first region, the second region reflecting the second light that has entered the optical element from the incident region, A third annular region surrounding the incident region, the third region reflecting the second light reflected by the second region toward the second region, Having, The light reflected in the third region is emitted from the second region, The first light and the second light include the light emitted from the light source and the third light reflected by the light source after being reflected in the first region, A light emitting device.

2. The light emitting device according to claim 1, wherein the first region retroreflects the first light.

3. The light emitting device according to claim 1, wherein the first region is a convex curved surface.

4. The light emitting device according to claim 3, wherein the convex curved surface is a rotational surface having the optical axis of the light source as a rotation axis.

5. The light emitting device according to claim 1, wherein the first region has a plurality of corner cubes.

6. The light emitting device according to claim 5, wherein the plurality of corner cubes are arranged convexly with respect to the second region.

7. The light emitting device according to claim 1, wherein the incident region is concave, and the light source is disposed in a recess of the optical element defined by the incident region.

8. The light emitting device according to claim 7, wherein the incident region includes a curved surface.

9. The light emitting device according to claim 7, wherein in a cross section including the optical axis of the light source, the depth of the recess is larger than the width of the opening of the recess.

10. The optical element is, A translucent member, A metal member covering the translucent member in the first region, The light emitting device according to claim 1, having.

11. The light emitting device according to claim 10, wherein the metal member continuously covers the first region and a part of the second region.

12. The optical element is, A light-transmissive member, a reflective member that covers the light-transmissive member in the third region, The light-emitting device according to claim 1, comprising:

13. Among the cross-sections of the third region, with the optical axis of the light source as the first axis, a first cross-section including the first axis and one second axis orthogonal to the first axis, and a cross-section parallel to the first cross-section are each a broken line formed by connecting a plurality of line segments. The light-emitting device according to claim 1, wherein among the cross-sections of the third region, a second cross-section including the first axis and a third axis orthogonal to the first axis and the second axis, and a cross-section parallel to the second cross-section are each a continuous curve.

14. The light-emitting device according to claim 1, wherein the light source further includes a wavelength conversion unit.

15. An illumination device including one or more of the light-emitting devices according to any one of claims 1 to 14.

16. The illumination device according to claim 15, which is for dental treatment.

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