Light source device and projection device

A light source device includes: a semiconductor light emitting element (laser element); an optical element that has a plurality of lens regions which are a plurality of divided regions, and that changes an intensity distribution of a light beam emitted from the semiconductor light emitting element, by the plurality of lens regions; and a phosphor element that emits light having, as excitation light, the light which has had the intensity distribution changed by the optical element. The phosphor element is disposed so that a light emitting surface of the phosphor element is inclined with respect to a plane having an optical axis of the excitation light as a normal line, the plurality of lens regions have respective first focal points different from each other, and light beams incident on the plurality of lens regions and focused on the first focal points overlap on the light emitting surface of the phosphor element.

BACKGROUND

1. Technical Field

The present disclosure relates to a light source device and a projection device, and particularly to a light source device that utilizes light which is emitted by irradiating a phosphor element with light emitted from a semiconductor light emitting element, and that is used in the field of display, such as a projection display device or the field of illumination, such as vehicle lighting and medical lighting, and to a projection device that uses the light source device.

2. Description of the Related Art

There has been conventionally known a light source device that utilizes light which is emitted by irradiating a phosphor element with light emitted from a semiconductor light emitting element.1n such a light source device, in order to improve the light intensity distribution of light (excitation light) with which a phosphor element is irradiated, and to reduce the decrease in the conversion efficiency of the phosphor element due to the effect of heat generation by the excitation light, an attempt to uniformize the light intensity distribution of light with which the phosphor element is irradiated is being made (for instance, Japanese Unexamined Patent Application Publication No. 2013-149449, Japanese Unexamined Patent Application Publication No. 2014-2839)

FIG. 16is a diagram illustrating the configuration of conventional light source device100disclosed in Japanese Unexamined Patent Application Publication No. 2013-149449.

In light source device100illustrated inFIG. 16, light emitted from laser element (laser chip)111of laser light source110enters a plane of incidence of optical rod120, and propagates while being multiply reflected within optical rod120. Thus, when the light emitted from laser light source110arrives at emission surface121of optical rod120, the light intensity distribution is averaged, and the light has a uniform light intensity distribution.

The light emitted from optical rod120is emitted as divergent light, thus is focused by lens130and light emission unit140is irradiated with the light. In this manner, light source device100uniformizes the light intensity distribution of the light with which light emitting unit140is irradiated, using optical rod120.

FIG. 17is a diagram illustrating the configuration of conventional light source device200disclosed in Japanese Unexamined Patent Application Publication No. 2014-2839.

In light source device200illustrated inFIG. 17, the light emitted from laser light sources210is converted into parallel light by collimator lens220, and is incident on hologram element230. Hologram element230is formed so that the light intensity distribution of the excitation light on phosphor240is uniform. In this manner, light source device200uniformizes the light intensity distribution of the excitation light with which phosphor240is irradiated, by hologram element230.

SUMMARY

The light source device disclosed in Japanese Unexamined Patent Application Publication No. 2013-149449 uses an optical rod to obtain a uniform light intensity distribution. However, the optical rod obtains uniform light intensity distribution with an increased number of multiple reflections, and thus the length of the optical rod needs to be increased to some extent. In addition, since the emission light from the optical rod becomes divergent light, the light needs to be focused once by a lens before the phosphor is irradiated with the light, thus the distance from the light emitting element to the phosphor is increased. Thus, a problem arises in that when a uniform light intensity distribution is attempted to be gained using an optical rod, the light source device cannot be miniaturized.

Also, the light source device disclosed in Japanese Unexamined Patent Application Publication No. 2014-2839 uses a hologram element to obtain a uniform light intensity distribution. However, since a hologram element uses diffraction phenomena of light, it is generally said that the hologram element has a lower efficiency than a lens. Also, the efficiency may be significantly reduced by an individual variability in the light emission wavelength of a laser element, change in the light emission wavelength due to a temperature, or the wavefront state (for instance, divergent light or converged light) of incident light to the hologram element, and there is a problem in that excitation light cannot be efficiently guided from a laser element to a phosphor. Also, a laser element can be a single mode laser element or a multi-mode laser element, and when a laser element is used as the light source for illumination, 1 W or higher light emission output is necessary, and it is typical to use a multi-mode laser element. However, in a multi-mode laser element, several emission wavefronts overlap in a multi-mode direction, and thus when a hologram element designed under the assumption of a certain incident wavefront is used, it is expected that a sufficient efficiency is not obtained. Like this, when a uniform light intensity distribution is attempted to be gained using a hologram device, there is a problem in that the light of a laser element cannot be converted into a uniform light intensity distribution efficiently.

The present disclosure has been made to solve the above-mentioned problems, it is an object of the disclosure to provide a light source device that is capable of efficiently converting the light emitted from a semiconductor light emitting element (laser element) into light having a uniform light intensity distribution, and that is compact.

In order to achieve the above-mentioned object, in an aspect of a light source device according to the present disclosure, a light source device includes: a laser element; an optical element that has a plurality of lens regions which are a plurality of divided regions, and that changes an intensity distribution of light emitted from the laser element, by the plurality of lens regions; and a phosphor element that emits light having, as excitation light, the light which has had the intensity distribution changed by the optical element. The phosphor element is disposed so that a light emitting surface of the phosphor element is inclined with respect to a plane having an optical axis of the excitation light as a normal line, the plurality of lens regions have respective first focal points different from each other, and light beams incident on the plurality of lens regions and focused on the first focal points overlap on the light emitting surface of the phosphor element.

With this configuration, light from a laser element incident on an optical element is propagated to the phosphor element as a plurality of light beams each of which is focused on the first focal point, by the plurality of lens regions. At this point, the plurality of light beams overlap with each other on the light emitting surface of the phosphor element, and thus a light intensity distribution is generated, in which the light of the laser element incident on each of the plurality of lens regions overlaps. In other words, the converted light is averaged and has a uniform light intensity distribution. Consequently, it is possible to achieve a light source device that is capable of efficiently converting the light emitted from the laser element to excitation light having a uniform light intensity distribution, and that is compact.

Also, in an aspect of the light source device according to the present disclosure, preferably, the respective first focal points of the plurality of lens regions are present forward or rearward of the light emitting surface of the phosphor element.

With this configuration, the plurality of lens regions can be easily designed so that light beams incident on the plurality of lens regions are focused on different first focal points, and overlap on the light emitting surface of the phosphor element.

Also, in an aspect of the light source device according to the present disclosure, preferably, the plurality of lens regions are divided in a direction of a first axis and in a direction of a second axis perpendicular to the first axis, and the first focal points are located on a plane which is formed by a third axis perpendicular to the first axis and the second axis, and the first axis, the plane including the optical axis of the excitation light.

With this configuration, the above-mentioned plurality of lens regions can be further easily designed, and focus to the different first focal points and overlapping on the phosphor element can be easily achieved.

Also, in an aspect of the light source device according to the present disclosure, preferably, the plurality of lens regions further have respective second focal points different from each other, the second focal points are located on a plane which is formed by the second axis and the third axis, the plane including the optical axis of the excitation light, and of the light beams emitted from the laser element and incident on the optical element, light beams that pass through at least the respective second focal points of the plurality of lens regions overlap on the light emitting surface of the phosphor element.

With this configuration, light from a laser element incident on an optical element is propagated to the phosphor element as a plurality of light beams each of which is also focused on the second focal point, by the plurality of lens regions. Also, at this point, the plurality of light beams overlap with each other on the light emitting surface of the phosphor element, and thus a light intensity distribution is generated, in which the light of the laser element incident on each of the plurality of lens regions overlaps. That is, not only on the plane formed by the third axis and the first axis, but also on the plane formed by the first axis and the second axis, the converted light is averaged and has a uniform light intensity distribution. Consequently, the light emitted from the laser element can be converted to excitation light having a further uniform light intensity distribution.

Also, in an aspect of the light source device according to the present disclosure, preferably, the respective second focal points of the plurality of lens regions are present forward or rearward of the light emitting surface of the phosphor element.

With this configuration, the plurality of lens regions can be easily designed so that light beams incident on the plurality of lens regions are also focused on different second focal points, and overlap on the light emitting surface of the phosphor element.

Also, in an aspect of the light source device according to the present disclosure, preferably, each of the plurality of lens regions has a width in the direction of the second axis smaller than a width in the direction of the first axis, and the phosphor element is inclined, with the direction of the first axis as a rotational axis.

With this configuration, even when the phosphor element is irradiated with an angle with excitation light, the vertical beam diameter and the horizontal beam diameter of the excitation light along the light emitting surface of the phosphor element (as viewed in a normal direction of the light emitting surface) can be easily equalized. Consequently, the light emitted from the laser element can be converted to excitation light having a further uniform light intensity distribution.

Also, in an aspect of the light source device according to the present disclosure, preferably, part or all of the plurality of lens regions is a rectangle or a hexagon.

With this configuration, the region not functioning as a lens can be minimized, and thus light can be converted into excitation light more efficiently.

Also, in an aspect of the light source device according to the present disclosure, preferably, a radiation angle of a light beam emitted from the laser element is different between the direction of the first axis and the direction of the second axis, and the light beam emitted from the laser element enters the plurality of lens regions so that one of the first axis and the second axis for a narrower radiation angle corresponds to the second axis.

With this configuration, the number of lens regions, which function for the intensity distribution (the incident light distribution) of incident light from the laser element, can be increased, and thus the incident light can be converted to excitation light having a further uniform light intensity distribution

Also, in an aspect of the light source device according to the present disclosure, preferably, each of the plurality of lens regions is a Fresnel lens.

With this configuration, the thickness of the optical element can be thinned, and thus the distance from the laser element to the phosphor element can be further reduced. Therefore, further miniaturization of the light source device can be achieved.

Also, an aspect of a projection device according to the present disclosure includes an aspect of one of the light source devices described above.

With this configuration, a compact projection device can be achieved.

It is possible to achieve a light source device that is capable of efficiently converting the light emitted from a semiconductor light emitting element (laser element) into light having a uniform light intensity distribution, and that is compact.

DETAILED DESCRIPTION OF THE EMBODIMENTS

Hereinafter an embodiment of the present disclosure will be described using the drawings. It is to be noted that each of the embodiments described below shows a preferable specific example of the present disclosure. Therefore, the numerical values, the components, the arrangement position and topology of the components, the processes (steps), and the order of the processes that are depicted in the following embodiments are examples, and not intended to limit the present disclosure. Thus, the components in the following embodiments, which are not described in the independent claim that defines the most generic concept of the present disclosure, are regarded as any components.

It is to be noted that in the present description and the drawings, coordinate axis which is first axis, coordinate axis96which is second axis, and coordinate axis97which is third axis indicate three axes of a three-dimensional orthogonal coordinate system. Similarly, coordinate axis95′ which is first axis, coordinate axis96′ which is second axis, and coordinate axis97′ which is third axis also indicate three axes of a three-dimensional orthogonal coordinate system.

Hereinafter, light source device1according to Embodiment 1 of the present disclosure will be described with reference to the drawings.

The configuration of light source device1according to Embodiment 1 of the present disclosure is illustrated inFIG. 1. As illustrated inFIG. 1, light source device1includes semiconductor light emitting device10, optical element20, and phosphor element30.

Semiconductor light emission device10is a packaged light emitting device, and includes semiconductor light emitting element11having optical waveguide11a,and cap (can)12made of metal constituting a package.

Semiconductor light emitting element11is disposed in cap12. Specifically, semiconductor light emitting element11is mounted in a post disposed on a disc-shaped base. In this embodiment, semiconductor light emitting element11is disposed so that the direction of a stripe width of optical waveguide11amatches the direction of coordinate axis95. In other words, semiconductor light emitting element11is disposed so that the longitudinal direction (the stripe direction) of optical waveguide11amatches the direction of coordinate axis97.

Windowpane13is mounted on cap12so that emission light51from semiconductor light emitting element11can pass through cap12. Windowpane13is an example of a translucent member that allows emission light51emitted from semiconductor light emitting element11to pass through, and is sheet glass in this embodiment. It is to be noted that semiconductor light emitting device10further includes a lead pin for supplying power to semiconductor light emitting element11from the outside.

Semiconductor light emitting element11is, for instance, a laser element composed of a nitride semiconductor (for instance, GaN-based laser element), and emits a laser beam having a peak wavelength between 380 nm and 490 nm of wavelength as emission light51.

Also, lens15is disposed in proximity to windowpane13forwardly of semiconductor light emitting device10. Lens15has a function of converting emission light51emitted from semiconductor light emitting device10(semiconductor light emitting element11) into substantially parallel light. Lens15is, for instance, a collimator lens.

Optical element20has optical functional unit22having a function of changing the intensity distribution of emission light51emitted from semiconductor light emitting element11. The details of optical functional unit22will be described later.

Emission light51emitted from semiconductor light emitting element11passes through optical element20, and thereby the light intensity distribution is changed, and the light has changed to convergence light and is incident on phosphor element30as excitation light54.

Fluorescent material element30is disposed so that the light emitting surface of phosphor element30is inclined with respect to the surface having the optical axis (travelling direction) of excitation light54as the normal line. Specifically, phosphor element30is disposed so that the light emitting surface is inclined with respect to the central optical axis of optical element20. Therefore, excitation light54enters phosphor element30with a predetermined incident angle. In this embodiment, phosphor element30is inclined around the direction of coordinate axis95(first axis) as a rotational axis direction. Specifically, when coordinate axis95is rotated as a rotational axis, phosphor element30is disposed so that normal direction98of phosphor element30is inclined with respect to coordinate axis96(second axis) by angle θ toward the opposite side from the traveling direction (the direction of coordinate axis97) of excitation light54. In other words, phosphor element30is disposed so that the light emitting surface of phosphor element30is inclined with respect to a plane having the optical axis of excitation light54as the normal line, around coordinate axis95as a rotational axis by angle (90°-θ). Angle θ is a rotational angle (inclination angle) of phosphor element30.

Also, as excitation light54, phosphor element30emits light having an intensity distribution changed by optical element20. Fluorescent material element30has a phosphor as a wavelength conversion material which converts the wavelength of incident light. For instance, phosphor element30has a phosphor layer including phosphors. For instance, phosphors (phosphor particles) are mixed, dispersed in a transparent resin (binder) such as silicone, and are formed in layers which may be used as a phosphor layer. The phosphor fluorescently emits with incident light serving as excitation light. The phosphor is composed of, for instance, cerium-activated yttrium aluminum garnet (YAG: Ce3+) based phosphor material. However, the phosphor is not limited to this.

Part of incident light (excitation light54) to phosphor element30is absorbed in phosphor element30, the wavelength is converted by the phosphor, and forms fluorescence93which radially diffuses, and the other part of incident light is reflected, diffused on the surface or the inside of phosphor element30, and forms scattering light92which radially diffuses (scatters). Synthetic light composed of fluorescence93and scattering light92emits as radiant light91from phosphor element30. In this case, a phosphor material (for instance, yellow phosphor material), which absorbs the light with a wavelength from 420 nm to 480 nm (for instance, blue light) and emits fluorescence with a wavelength from 500 nm to 630 nm, is used as the phosphor material of the phosphor, thereby making it possible to emit white light composed of fluorescence93and scattering light92as radiant light91from phosphor element30.

Next, the configuration and the function of optical functional unit22of optical element20in Embodiment 1 of the present disclosure will be described in detail usingFIG. 2,FIG. 3, andFIG. 4with reference toFIG. 1.

First, the configuration of optical element20will be described usingFIG. 2.FIG. 2is a diagram illustrating the configuration of optical element20in light source device1according to Embodiment 1 of the present disclosure. (a) ofFIG. 2is a plan view of optical element20, and illustrates optical element20as viewed from the emission side of excitation light54. (b) ofFIG. 2is a cross sectional view from IIB-IIB in (a) ofFIG. 2, and (c) ofFIG. 2is a cross sectional view from IIC-IIC in (a) ofFIG. 2. It is to be noted that in (a) ofFIG. 2is the same as A-A inFIG. 1.

As illustrated in (a) to (c) ofFIG. 2, optical element20has a plurality of lens regions21(21a,21b,21c,21d,21e,. . . ) which are a plurality of divided region, as optical functional unit22. Each of the plurality of lens regions21is an individual divided region (unit region) in optical functional unit22. In this embodiment, a plurality of lens regions21are regions divided in the direction of coordinate axis95(first axis) and the direction of coordinate axis96(second axis). Optical element20changes the intensity distribution of emission light51emitted from semiconductor light emitting element U by the plurality of lens regions21(optical functional unit22).

The plurality of lens regions21are each a lens that has a light focusing function. In other words, each of the plurality of lens regions21has a function of individually converging the incident light to optical element20by each lens region21.

In this embodiment, the plan-view shape of each lens region21is a rectangle having width W1and width W2. In each lens region21, width1is set to be greater than width W2(W1>W2). Also, the areas of lens regions21are substantially equal. In addition, in this embodiment, the longitudinal direction of lens region21is the direction of coordinate axis95, and the transverse direction of lens region21is the direction of coordinate axis96. In other words, in each of the plurality of lens regions21, the width in the direction of coordinate axis96(second axis) is smaller than the width in the direction of coordinate axis95(first axis).

It is to be noted that in this embodiment, although all of the plurality of lens regions21are rectangles in optical element20, without being limited to this, part of the plurality of lens regions are rectangles, and the other part of the plurality of lens regions may be shapes other than rectangles.

Next, the function of the plurality of lens regions21(optical functional unit22) in optical element20will be described usingFIG. 3andFIG. 4.FIG. 3is a diagram for illustrating the function of lens region21in a longitudinal direction cross section, and illustrates a light focus state of excitation light54on a plane which is in IIB-IIB cross section in (a) ofFIG. 2, and includes the optical axis of excitation light54(incident light51). Also,FIG. 4is a diagram for illustrating the function of lens region21in the transverse direction cross section, and illustrates a light focus state of excitation light54on a plane which is in IIC-IIC cross section in (a) ofFIG. 2, and includes the optical axis of excitation light54(incident light51).

As illustrated inFIG. 3, the plurality of lens regions21have mutually different first focal points (first focal point positions). First focal point of each of the plurality of lens regions21is located on a plane which is formed by coordinate axis97and coordinate axis95, and includes the optical axis of excitation light54. Also, first focal point of each of the plurality of lens regions21is located on a plane which is one of an infinite number of planes formed by coordinate axis95and coordinate axis96, and is away from optical element20by distance F.

Specifically, central lens region21aof the plurality of lens regions21has focal point55aas first focal point at a position away from optical element20along the direction of coordinate axis97by a certain distance (distance F2), the position being in a plane formed by coordinate axis97and coordinate axis95. Also, lens region21d(the lens region formed adjacent to one side of lens region21ain the direction of coordinate axis95) out of the plurality of lens regions21has focal point55das first focal point at a position with distance F2from optical element20in a plane formed by coordinate axis97and coordinate axis95. Also, lens region21e(the lens region formed adjacent to the other side of lens region21ain the direction of coordinate axis95) out of the plurality of lens regions21has focal point55eas first focal point at a position with distance F2from optical element20in a plane formed by coordinate axis97and coordinate axis95.

Also, incident light to optical element20(incident light51ofFIG. 1) is converged by each of the plurality of lens regions21, and thereby the intensity distribution is changed, and is converted into excitation light54and emitted from the plurality of lens regions21.

Specifically, as illustrated inFIG. 3, the incident light to central lens region21aamong the incident light to optical element20is converted into convergence light (excitation light54a) which is converged to be focused on focal point55a,by lens region21a.Similarly, the incident light to central lens region21damong the incident light to optical element20is converted into convergence light (excitation light54d) which is converged to be focused on focal point55d,by lens region21d.Also, the incident light to central lens region21eamong the incident light to optical element20is converted into convergence light (excitation light54e) which is converged to be focused on focal point55e,by lens region21e.

In this manner, the incident light to the plurality of lens regions21is converted into a plurality of convergence light beams having different focal points at a position with distance F2from optical element20, and emits as a plurality of excitation light beams from optical element20.

In addition, the position of the focal point of each of the plurality of lens regions21is set so that the plurality of convergence light beams (excitation light) overlap with each other at a position with distance L2from optical element20. Specifically, the convergence light beams (excitation light54a,54d,and54e) converged by lens regions21a,21d,and21eoverlap with each other at a position with distance L2from optical element20, and excitation light54with beam width (beam diameter) D1is formed.

Fluorescent substance element30is disposed so that the light emitting surface (for instance, the major surface of the phosphor layer) which is the major surface of phosphor element30is located at a position with distance L2from optical element20. Therefore, the light emitting surface of phosphor element30is irradiated so that the plurality of convergence light beams emitted from the plurality of lens regions21are superimposed with beam width D1.

In this embodiment, a configuration is adopted in which F2>L2so that first focal point of each of the plurality of lens regions21is present on the rear side (the far side) from the light emitting surface of phosphor element30. In other words, phosphor element30is disposed so that the light emitting surface of phosphor element30is located between first focal point of each of the plurality of lens regions21and optical element20. It is to be noted that a configuration may be adopted in which F2<L2so that first focal point of each of the plurality of lens regions21is present on the front side (the near side) from the light emitting surface of phosphor element30. The same effect is also obtained in this case.

In this manner, the light beams incident on the plurality of lens regions21and focused on first focal points overlap on the light emitting surface of phosphor element30. Specifically, light beams incident on the plurality of lens regions21a,21d,and21e,and converged to focal points55a,55d,and55eoverlap on the light surface of phosphor element30.

It is to be noted that in this embodiment, lens regions21other than lens regions21a,21d,and21eout of the plurality of lens regions21arranged along coordinate axis95also have the same function, and the light beams incident on the plurality of lens regions21and focused on first focal points overlap on the light emitting surface of phosphor element30. In other words, in this embodiment, the light beams incident on the plurality of lens regions21arranged along coordinate axis95and focused overlap on the light emitting surface of phosphor element30.

As illustrated inFIG. 1, in the transverse direction cross section, lens region21also has the function as in the longitudinal direction cross section.

As illustrated inFIG. 4, the plurality of lens regions21further have mutually different second focal points (second focal point positions). Second focal point of each of the plurality of lens regions21is located on a plane which is formed by coordinate axis96and coordinate axis97, and includes the optical axis of excitation light54. Also, second focal point of each of the plurality of lens regions21is located on a plane which is one of an infinite number of planes formed by coordinate axis95and coordinate axis96, and is away from optical element20by distance F′.

Specifically, central lens region21aof the plurality of lens regions21has focal point55a′ as second focal point at a position away from optical element20along the direction of coordinate axis97by a certain distance (distance F2′), the position being in a plane formed by coordinate axis96and coordinate axis97. Also, lens region21b(the lens region formed adjacent to one side of lens region21ain the direction of coordinate axis96) out of the plurality of lens regions21has focal point55bas second focal point at a position with distance F2′ from optical element20in a plane formed by coordinate axis96and coordinate axis97. Also, lens region21c(the lens region formed adjacent to the other side of lens region21ain the direction of coordinate axis96) out of the plurality of lens regions21has focal point55cas second focal point at a position with distance F2′ from optical element20in a plane formed by coordinate axis96and coordinate axis97.

The incident light to central lens region21aamong the incident light to optical element20is converted into convergence light (excitation light54a′) which is converged to be focused on focal point55a′, by lens region21a.Similarly, the incident light to central lens region21bamong the incident light to optical element20is converted into convergence light (excitation light54b) which is converged to be focused on focal point55b,by lens region21b.Also, the incident light to central lens region21camong the incident light to optical element20is converted into convergence light (excitation light54c) which is converged to be focused on focal point55c,by lens region21c.

In this manner, even on a plane formed by coordinate axis96and coordinate axis97, the incident light to the plurality of lens regions21is converted into a plurality of convergence light beams having different focal points at a position with distance F2′ from optical element20, and emits as a plurality of excitation light beams from optical element20.

Also, even on a plane formed by coordinate axis96and coordinate axis97, the position of the focal point of each of the plurality of lens regions21is set so that the plurality of convergence light beams (excitation light) overlap with each other at a position with distance L2from optical element20. Specifically, the convergence light beams (excitation light54a′,54b,and54c) converged by lens regions21a,21b,and21coverlap with each other at a position with distance L2from optical element20, and excitation light54with beam width (beam diameter) D2is formed.

Fluorescent substance element30is disposed so that the light emitting surface (the major surface) of phosphor element30is located at a position with distance L2from optical element20. Therefore, the light emitting surface of phosphor element30is irradiated so that the plurality of convergence light beams emitted from the plurality of lens regions21are superimposed with beam width D2.

Also, in this embodiment, as illustrated inFIG. 4, phosphor element30is disposed so that the normal line of the light emitting surface is matched to coordinate axis96and is rotated by angle θ around coordinate axis95as a rotational axis, and in a state where the normal line is inclined to match coordinate axis97, convergence light beams (excitation light54a′,54b,and54c) converged by lens regions21a,21b,and21cfrom beam width D2.

Thus, radiant light91(FIG. 1) having beam width D3(D3>D2) is formed on the light emitting surface (major surface) of phosphor element30by the effect of inclination of phosphor element30. It is to be noted that from the viewpoint of obtaining light having a uniform intensity distribution, beam width D1and beam width D3on the light emitting surface of phosphor element30are preferably formed to be substantially the same as beam width D1and beam width D2of light emission points, at which fluorescence of phosphor element30is generated, of the plurality of lens regions21. In this case, beam width D2can be made smaller than beam width D1by setting division width W2of the plurality of lens regions21to be smaller than division width W1, and beam width D1and beam width D3can be made substantially the same.

Also, in this embodiment, similarly to first focal point, a configuration adopted in which F2′>L2so that second focal point of each of the plurality of lens regions21is present on the rear side (the far side) from the light emitting surface of phosphor element30. In other words, phosphor element30is disposed so that the light emitting surface of phosphor element30is located between second focal point of each of the plurality of lens regions21and optical element20. It is to be noted that a configuration may be adopted in which F2′<L2so that second focal point of each of the plurality of lens regions21is present on the front side (the near side) from the light emitting surface of phosphor element30. The same effect is also obtained in this case.

Also, in each of the plurality of lens regions21, distance F2to first focal point illustrated inFIG. 3and distance F2′ to second focal point illustrated inFIG. 4may be different (F2≠F2′), or may be the same (F2=F2′). In other words, focal point55aand focal point55a′ in lens region21amay be different, or may be the same.

In this manner, similarly to the light focused on first focal point, the light beams incident on the plurality of lens regions21and focused on second focal point overlap on the light emitting surface of phosphor element30. Specifically, light beams incident on the plurality of lens regions21a,21b,and21c,and converged to focal points55a′,55b,and55coverlap on the light emitting surface of phosphor element30.

It is to be noted that in this embodiment, lens regions21other than lens regions21a,21b,and21cout of the plurality of lens regions21arranged along coordinate axis96also have the same function, and the light beams incident on the plurality of lens regions21and focused on second focal points overlap on the light emitting surface of phosphor element30. In other words, in this embodiment, the light beams incident on the plurality of lens regions21arranged along coordinate axis96and focused overlap on the light emitting surface of phosphor element30.

Next, the manner in which the intensity distribution of incident light51passing through lens region21(optical functional unit22) of optical element20is changed will be described usingFIG. 5.FIG. 5is a diagram for illustrating a change in the intensity distribution of light passing through the optical element of the light source device according to Embodiment 1 of the present disclosure.

InFIG. 5, although the change in the intensity distribution when incident light51incident on the plurality of lens regions21becomes excitation light54and emits in the plane illustrated inFIG. 3will be described, the same goes with the plane illustrated inFIG. 4. Although a description is given limited to 3 lens regions (21a,21d,21e) for the sake of convenience of description inFIG. 5, the same principle applies to the case of 5 lens regions as illustrated inFIG. 2.

InFIG. 5, thin dashed lines in (a) to (c) indicate the light intensity distribution (incident light distribution) of incident light51incident on the plurality of lens regions21. The thick clashed line in (a) ofFIG. 5indicates the light intensity distribution (excitation light distribution) of excitation light54aachieved by lens region21a,the thick dashed line in (b) ofFIG. 5indicates the light intensity distribution (excitation light distribution) of excitation light54dachieved by lens region21d,and the thick dashed line in (c) ofFIG. 5indicates the light intensity distribution (excitation light distribution) of excitation light54eachieved by lens region21e.

As illustrated in (a) to (c) ofFIG. 5, each of excitation light54a,54d,and54ehas such a light intensity distribution that divides the incident light distribution to the plurality of lens regions21.

In this embodiment, it is set that respective excitation light beams54a,54d,and54eemitted from the plurality of lens regions21propagate with convergence light having different focal points, and overlap on the light emitting surface of phosphor element30. Thus, as illustrated in (d) ofFIG. 5, the light intensity distributions (excitation light distributions) of excitation light54a,54d,and54eoverlap with each other and averaged on the light emitting surface of phosphor element30, thus the light intensity distribution as entire excitation light54is uniformized. In this case, as illustrated in (d) ofFIG. 5, the light intensity distribution of excitation light54has a shape corresponding to beam width D1on the light emitting surface of phosphor element30.

Although a description is given limited to 3 lens regions21in this embodiment as described above, it is actually designed that excitation light beams from more lens regions21overlap, thus the effect of averaging of the light intensity distribution is further increased. That is, as the number of divided lens regions is increased, excitation light54having a more uniform light intensity distribution can be obtained.

With light source device1above in this embodiment, the light emitted from semiconductor light emitting element11can be efficiently converted into light having a uniform light intensity distribution. Therefore, decrease in the light emission efficiency of phosphor element30due to heat generation by excitation light54can be reduced. In addition, excitation light54having a uniform light intensity distribution can be formed without using an optical rod or the like, and thus a compact light source device can be achieved.

Modification 1 of Embodiment 1

Modification 1 of Embodiment 1 of the present disclosure will be described usingFIG. 6.FIG. 6is a diagram illustrating the configuration of optical element20in a light source device according to Modification 1 of Embodiment 1 of the present disclosure. (a) ofFIG. 6is a plan view of optical element20in this modification, and (b) ofFIG. 6is a sectional view in VIB-VIB in (a) ofFIG. 6. It is to be noted that in this modification, the components other than optical element20are the same as the components of source device1in Embodiment 1 described above.

As illustrated in (a) and (b) ofFIG. 6, similarly to optical element20in Embodiment 1, optical element20in this modification has a plurality of lens regions21(21a,21b,21c,. . . ) which are a plurality of divided regions as optical functional unit22to change the intensity distribution of emission light51emitted from semiconductor light emitting element11. Also in this modification, the plurality of lens regions21are divided in the direction of coordinate axis95(first axis) and the direction of coordinate axis96(second axis).

In contrast, this modification differs from Embodiment 1 in the plan-view shape of each lens region21. Specifically, although the plan-view shape of each of the plurality of lens regions21in Embodiment 1 described above is a rectangle, the plan-view shape of each of the plurality of lens regions21in this modification is a hexagon. Specifically, the plan-view shape of each lens region21in this modification is a hexagon, and width W2in the direction of coordinate axis96is set to be smaller than width W1in the direction of coordinate axis95.

It is to be noted that as illustrated in (b) ofFIG. 6, the cross sectional shape of optical element20in this modification is the same as the cross sectional shape of optical element20in Embodiment 1 illustrated in (b) ofFIG. 2. Although not illustrated, the cross sectional shape of optical element20in this modification in a plane including coordinate axes95and97is the same as the cross sectional shape of optical element20in Embodiment 1 illustrated in (c) ofFIG. 2.

Optical element20in this modification also has the same function as the function of optical element20in Embodiment 1. Specifically, also in this modification, it is set that respective excitation light beams emitted from the plurality of lens regions21propagate with convergence light having different focal points, and overlap on the light emitting surface of phosphor element30. Consequently, the light intensity distribution of the entire excitation light emitted from optical element20is uniformized.

Consequently, even with light source device in this modification, the light emitted from semiconductor light emitting element11can be efficiently converted into light having a uniform light intensity distribution. Since it is not necessary to use an optical rod or the like, a compact light source device can be achieved.

In addition, in this modification, since the plan-view shape of each of the plurality of lens regions21in optical element20is a hexagon, the beam shape of excitation light on the light emitting surface of phosphor element30can be made further closer to a circle, and thus the region not functioning as a lens can be reduced. Consequently, emission light51of semiconductor light emitting element11can be efficiently converted into excitation light54by optical element20, and the luminance distribution of radiant light91of phosphor element30can be made further closer to a circle.

Modification 2 of Embodiment 1

Modification 2 of Embodiment 1 of the present disclosure will be described usingFIG. 7.FIG. 7is a diagram illustrating the configuration of optical element20in a light source device according to Modification 2 of Embodiment 1 of the present disclosure. (a) ofFIG. 7is a plan view of optical element20in the present modification, and (b)FIG. 7is a cross sectional view in VIIB-VIIB in (a) ofFIG. 7. It is to be noted that in this modification, the components other than optical element20are the same as the components of source device1in Embodiment 1 described above.

As illustrated in (a) and (b) ofFIG. 7, to optical element20in Embodiment 1, optical element20in this modification has a plurality of lens regions21(21a,21b,21c,. . . ) which are a plurality of divided regions as optical functional unit22to change the intensity distribution of emission light51emitted from semiconductor light emitting element11.

Unlike Embodiment 1 described above, in this modification, each of the plurality of lens regions21is a Fresnel lens, however, optical element20in this modification also has the same function as the function of optical element20in Embodiment 1. Specifically, also in this modification, it is set that respective excitation light beams emitted from the plurality of lens regions21propagate with convergence light having different focal points, and overlap on the light emitting surface of phosphor element30. Consequently, the light intensity distribution of the entire excitation light emitted from optical element20is uniformized.

Consequently, even with light source device in this modification, the light emitted from semiconductor light emitting element11can be efficiently converted into light having a uniform light intensity distribution. Since it is not necessary to use an optical rod or the like, a compact light source device can be achieved.

Moreover, in this modification, each of the plurality of lens regions21is a Fresnel lens. Thus, in contrast to Embodiment 1 described above, the thickness of optical functional unit22can be made thin, and the thickness of optical element20itself can also be made thin. As a consequence, the distance from semiconductor light emitting element11to phosphor element30can be reduced, and thus further miniaturization of the light source device can be achieved.

Modification 3 of Embodiment 1

Modification 3 of Embodiment 1 of the present disclosure will be described usingFIG. 8.FIG. 8is a diagram illustrating the configuration of optical element20in a light source device according to Modification 3 of Embodiment 1 of the present disclosure. Also in this modification, the components other than optical element20are the same as the components of source device1in Embodiment 1 described above.

Similarly to optical element20in Embodiment 1, optical element20in this modification has plurality of lens regions21which are a plurality of divided regions. Although the plan-view shape of each lens region21is a rectangle similarly to Embodiment 1, the plurality of lens regions21are formed to have respective different areas in this modification.

Optical element20in this modification also has the same function as the function of optical element20in Embodiment 1. Specifically, also in this modification, it is set that respective excitation light beams emitted from the plurality of lens regions21propagate with convergence light having different focal points, and overlap on the light emitting surface of phosphor element30. Consequently, the light intensity distribution of the entire excitation light emitted from optical element20is uniformized.

Consequently, even with light source device in this modification, the light emitted from semiconductor light emitting element11can be efficiently converted into light having a uniform light intensity distribution. Since it is not necessary to use an optical rod or the like, a compact light source device can be achieved.

Moreover, in this modification, the plurality of lens regions21are formed to have respective different areas in this modification. Consequently, the region not functioning as a lens can be reduced, and it can be designed that the light intensity distribution of excitation light54with which phosphor element30is irradiated is further uniformized. Therefore, decrease in the light emission efficiency of phosphor element30due to heat generation by excitation light can be further reduced.

It is to be noted that in this modification, although the plan-view shape of the plurality of lens regions21is a rectangle as illustrated inFIG. 8, the plan-view shape of the plurality of lens regions21may be a hexagon as illustrated inFIG. 9. Thus, the spot shape of excitation light54on the light emitting surface of phosphor element30can be made further closer to a circle.

Next, light source device1A according to Embodiment 2 of the present disclosure will be described usingFIG. 10.FIG. 10is a diagram illustrating the configuration of light source device1A according to Embodiment 2 of the present disclosure.

The point of difference between light source device1A in this embodiment and light source device1in Embodiment 1 illustrated inFIG. 1is the arrangement direction (orientation) of semiconductor light emitting element11. In this embodiment, semiconductor light emitting device10is disposed at a position rotated 90 degrees around the optical axis of emission light51.

Specifically, in Embodiment 1 described above, semiconductor light emitting element11is disposed so that the direction of the stripe width of optical waveguide11amatches the direction of coordinate axis95, however, in this embodiment, semiconductor light emitting element11is disposed so that the direction of the stripe width of optical waveguide11amatches the direction of coordinate axis96. In other words, in this embodiment, semiconductor light emitting element11is disposed so that the longitudinal direction (the stripe direction) of optical waveguide11amatches the direction of coordinate axis97. It is to be noted that in this embodiment, the light source device is the same as light source device1in Embodiment 1 described above other than the arrangement direction (orientation) of semiconductor light emitting element11.

Here, the radiation angle of emission light emitted from semiconductor light emitting element11is different between the direction of coordinate axis95and the direction of coordinate axis96. In general, in semiconductor light emitting element11having optical waveguide11a,the radiation angle of emission light emitted in the direction of the stripe width is small, and the radiation angle of emission light emitted in the direction perpendicular to the stripe width direction is large. For instance, inFIG. 10, emission light51from semiconductor light emitting element11has a narrow optical distribution width in A-A direction (the direction of coordinate axis96), and twice the optical distribution width or greater in the direction (the direction of coordinate axis95) perpendicular to A-A direction.

The configuration of optical element20in this embodiment is the same as the configuration of optical element20in Embodiment 1 described above illustrated inFIG. 2. Also, optical element20in Modification 1, Modification 2, and Modification 3 of Embodiment 1 may be used. In other words, inFIG. 10, for A-A direction of optical element20, that is, for IIC-IIC direction inFIG. 2, VIB-VIB direction inFIG. 6, and VIIB-VIIB direction inFIG. 7, each lens region21is designed so that width W2is smaller than width W1. In short, in each lens region21, the width in the direction of coordinate axis96is smaller than the width in the direction of coordinate axis95.

Thus, in this embodiment, the plurality of lens regions21are formed so that A-A direction with a narrow incident light distribution width corresponds to narrow width (W2) of the plurality of lens regions21of optical element20, and the direction (the direction perpendicular to A-A) with a wider incident light distribution width corresponds to wide width (W1).

Consequently, in this embodiment, emission light51emitted from semiconductor light emitting element11enters the plurality of lens regions21so that the direction with a narrow radiation angle corresponds to the narrow width (coordinate axis96) of each lens region21.

Also in light source device LA above in this embodiment, it is set that respective excitation light beams emitted from the plurality of lens regions21propagate with convergence light having different focal points, and overlap on the light emitting surface of phosphor element30. Consequently, the light intensity distribution of the entire excitation light emitted from optical element20is uniformized.

Consequently, even with light source device in this modification, the light emitted from semiconductor light emitting element11can be efficiently converted into light having a uniform light intensity distribution. Since it is not necessary to use an optical rod or the like, a compact light source device can be achieved.

Furthermore, in this embodiment, emission light51with a narrow radiation angle emitted from semiconductor light emitting element11corresponds to the narrow width of each lens region21.

With this configuration, it is possible to increase the number of effective lens regions21that effect on the intensity distribution (incident light distribution) of incident light51of semiconductor light emitting element11. Consequently, the number of converted excitation light beams corresponding to lens regions21is increased, and the number of excitation light beams overlapping on the light emitting surface of phosphor element30is increased. Therefore, the light intensity distribution is averaged by more excitation light beams, and thus excitation light54having a more uniform light intensity distribution can be obtained.

Next, light source device1B according to Embodiment 3 of the present disclosure swill be described usingFIG. 11andFIG. 12.FIG. 11is a diagram illustrating the configuration of light source device1B according to Embodiment 3 of the present disclosure.FIG. 12is a diagram illustrating the configuration and function of optical element20in light source device1B.

As illustrated inFIG. 11, semiconductor light emitting element11is disposed so that the direction of the stripe width of optical waveguide11amatches the direction of coordinate axis95′, and emission light51emits from semiconductor light emitting element11in the direction of coordinate axis99.

In this embodiment, similarly to Embodiment 1, the plurality of lens regions21having different focal points are formed on the plane of incidence of optical element20. Similarly to first focal point and second focal point of each lens region21in Embodiment 1, the respective focal points of the plurality of lens regions21may be different or may be the same in two planes perpendicular to each other.

Also unlike Embodiment 1, in this embodiment, optical element20is disposed so that the normal line of optical element20is inclined by angle θ around coordinate axis95′ as a rotational axis with respect to the optical axis (coordinate axis99) of emission light51of semiconductor light emitting device10.

Incident light51to optical element20is reflected and focused by the plurality of lens regions21, and becomes excitation light54, with which phosphor element30is irradiated. Since the excitation light beams corresponding to lens regions21overlap with each other on the light emitting surface of phosphor element30, the light intensity distributions of the excitation light beams are averaged on the light emitting surface of phosphor element30. Consequently, entire excitation light54generated by optical element20has a uniform light intensity distribution.

It is to be noted that in this embodiment, in order to increase reflection of emission light51from semiconductor light emitting element11, reflection film24is formed on the plane of incidence of optical element20. Reflection film24is composed of a plurality of dielectric materials having different refractive indices, for instance. For instance, reflection film24is formed by stacking multiple layers of materials such as SiO2, TiO2, Ta2O5, Nb2O5by a sputter device or a deposition device. Alternatively, reflection film24may be composed of metal having a high optical reflectivity, for instance, Ag, Cu, Au, Al, or an alloy of these.

Also, phosphor element30is disposed so that the normal direction of the light emitting surface (major surface) substantially matches coordinate axis99. Although phosphor element30may be disposed in an inclined manner as in Embodiment 1, radiant light91can be emitted in a direction perpendicular to a reference plane by disposing phosphor element30as in this embodiment. Thus, from the viewpoint of constructing a light source device, it is preferable to dispose phosphor element30as in this embodiment.

It is to be noted that the incidence angle of incident angle51incident on phosphor element30can be adjusted by rotation angle θ of optical element20. In order to take more radiant light91from the phosphor element, it is preferable that rotation angle θ be less than 45 degrees, and it is more preferable that rotation angle θ be set between 30 degrees and 40 degrees.

Similarly to Embodiment 1, the plurality of lens regions21are a plurality of divided regions, and may be any of rectangles (FIG. 2), hexagons (FIG. 6), hexagonal Fresnel lenses (FIG. 7), rectangles with different areas (FIG. 8), and hexagons with different areas (FIG. 9).

Although each of the plurality of lens regions21has different widths in two perpendicular directions, it is preferable that lens regions21are disposed so that the narrower width corresponds to A-A direction illustrated inFIG. 11.

With such disposition, the region not functioning as a lens can be reduced in the plurality of lens regions21, and thus emission light51from semiconductor light emitting element11can be efficiently converted into excitation light54. Thus, phosphor element30can be irradiated with excitation light54having a more uniform light intensity distribution.

Also in light source device1B above in this embodiment, it is set that respective excitation light beams emitted from the plurality of lens regions21propagate with convergence light having different focal points, and overlap on the light emitting surface of phosphor element30. Consequently, the light intensity distribution of the entire excitation light54emitted from optical element20is uniformized.

Consequently, even with light source device in this modification, the light emitted from semiconductor light emitting element11can be efficiently converted into light having a uniform light intensity distribution.

Furthermore, in this embodiment, the light emitted from semiconductor light emitting element11is reflected by optical element20, and excitation light54is formed. Thus, the distance between semiconductor light emitting device10and phosphor element30can be further reduced, and thus further miniaturization of the light source device can be achieved.

Modification of Embodiment 3

A modification of Embodiment 3 of the present disclosure will be described usingFIG. 13andFIG. 14.FIG. 13is a diagram illustrating the configuration of light source device1C according to a modification of Embodiment 3 of the present disclosure.FIG. 14is a diagram illustrating the configuration and function of optical element20in light source device1C.

As illustrated inFIG. 13, in light source device1C in this modification, the arrangement orientation of semiconductor light emitting device10is changed in light source device1B of Embodiment 3 illustrated inFIG. 11.

Specifically, semiconductor emission device10in this modification is disposed at a position for which the arrangement orientation of semiconductor light emitting device10inFIG. 11is rotated 90 degrees around the optical axis of emission light51. In other words, in Embodiment 3 described above, semiconductor light emitting element11is disposed so that the direction of the stripe width of optical waveguide11amatches the direction of coordinate axis95′. However, in this modification, semiconductor light emitting element11is disposed so that the direction of the stripe width of optical waveguide11amatches the direction perpendicular to a plane formed by coordinate axis95′ and coordinate axis99.

Also, in optical element20in this modification, the plurality of lens regions21having focal points different from each other are formed on the surface (the surface, opposed to the plane of incidence, of optical element20) on the opposite side of the plane of incidence, to which emission light51from semiconductor light emitting device10is incident.

Focal point55of each of the plurality of lens regions21is set on the front side (the near side) of phosphor element30. Similarly to first focal point and second focal point of each lens region21in Embodiment 1, respective focal points55of the plurality of lens regions21may be different or may be the same in two planes perpendicular to each other.

Also, all of the same components as those described in Embodiment 3 are applicable to the components of the plurality of lens regions21. In this case, lens regions21may be disposed so that the narrower side thereof corresponds to A-A direction.

As illustrated inFIG. 14, antireflection film23is formed on the plane of incidence of optical element20to reduce the reflection of emission light51from semiconductor light emitting device10. On the other hand, reflection film24is formed on the surface of the plurality of lens regions21formed on the opposite side of the plane of incidence of optical element20.

Antireflection film23and reflection film24are composed of a plurality of dielectric materials having different refractive indices, for instance. For instance, antireflection film23and reflection film24are formed by stacking multiple layers of materials such as SiO2, TiO2, Ta2O5, Nb2O5by a sputter device or a deposition device. It is to be noted that reflection film24may be composed of metal having a high optical reflectivity, for instance, Ag, Cu, Au, Al, or an alloy of these.

Optical element20is configured in this manner, and thus emission light51from semiconductor light emitting element11efficiently enters optical element20, and is focused and reflected by the plurality of lens regions21and reflection film24efficiently, and is emitted to phosphor element30as excitation light54.

In this case, in this modification, as illustrated inFIG. 13, excitation light54, which propagates to phosphor element30, is once focused at focal point55located in front of phosphor element30, and becomes divergent light, with which the light emitting surface of phosphor element30is irradiated.

Also in light source device1C above in this modification, it is set that respective excitation light beams emitted from the plurality of lens regions21propagate with convergence light having different focal points, and overlap on the light emitting surface of phosphor element30. Consequently, the light intensity distribution of the entire excitation light emitted from optical element20is uniformized.

Consequently, even with light source device in this modification, the light emitted from semiconductor light emitting element11can be efficiently converted into light having a uniform light intensity distribution. Since it is not necessary to use an optical rod or the like, a compact light source device can be achieved.

Next, projection device2according to Embodiment 4 of the present disclosure will be described usingFIG. 15.FIG. 15is a diagram illustrating a configuration of projection device2according to Embodiment 4 of the present disclosure.

Projection device2is, for instance, a lighting tool for vehicle headlight, and includes light source device1in Embodiment 1, and reflector60. Reflector60is a reflecting member for changing the radiant angle of radiant light91from light source device1for forward projection.

Since projection device2in this embodiment uses light source device1in Embodiment 1, a compact projection device can be achieved.

It is to be noted that in this embodiment, although light source device1in Embodiment 1 is used, without being limited to this, for instance, the light source device in each modification of Embodiment 1, or in Embodiment 2 or Embodiment 3 may be used as the light source for projection device2.

Other Modifications

Although the light source device and the projection device according to the present disclosure have been described above based on the embodiments and modifications, the present disclosure is not limited to the embodiments and modifications described above. For instance, an embodiment obtained by applying various modifications which may occur to those skilled in the art to each embodiment and modification, and an embodiment which is implemented by combining components and functions of each embodiment and modification in any manner without departing from the essence of the present disclosure are also included in the present disclosure.

INDUSTRIAL APPLICABILITY

The present disclosure is widely applicable to various optical devices, such as a light source device having a semiconductor light emitting element and a phosphor element, and a projection device using the light source device.