Light emitting device

A light emitting device includes: a light emitting unit; an optical member configured to transmit or pass light emitted by the light emitting unit, the optical member including: a first region configured to transmit or pass light having a first chromaticity; and a second region configured to transmit or pass light having a second chromaticity different from the first chromaticity; and a movable member configured to move to change a distance between the light emitting unit and the optical member along an optical axis of the light emitting unit.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority to Japanese Patent Application No. 2021-065969, filed on Apr. 8, 2021, and Japanese Patent Application No. 2021-185194, filed on Nov. 12, 2021, the disclosures of which are hereby incorporated by reference in their entireties.

BACKGROUND

The present disclosure relates to a light emitting device.

There are known light emitting devices configured to emit light from a light emitting element upon wavelength conversion by a wavelength conversion member such as phosphor.

Further, configurations have been disclosed in which a thickness of a sealing resin directly above a plurality of sets of light emitting elements differs for the respective sets, thereby making a chromaticity of light emitted from the sealing resin differ when each of the plurality of sets of light emitting elements emits the light alone as a single set (refer to Japanese Patent Publication No. 2017-120897, for example).

SUMMARY

Nevertheless, in the configuration of the above Patent Publication, each of the plurality of sets of light emitting elements is caused to emit light on a per set basis, resulting in a low degree of freedom in color adjustment of the light emitting device.

An object of the present disclosure is to provide a light emitting device having a high degree of freedom in color adjustment of light.

A light emitting device according to an embodiment of the present disclosure includes a light emitting unit, an optical member configured to transmit or pass light emitted by the light emitting unit, and a movable member. The optical member includes a first region configured to transmit or pass light having a first chromaticity. The optical member further includes a second region configured to transmit or pass light having a second chromaticity different from the first chromaticity. The movable member is configured to move to change a distance between the light emitting unit and the optical member along an optical axis of the light emitting unit.

A light emitting device according to an embodiment of the present disclosure includes a light emitting unit, an optical member configured to transmit or pass light emitted by the light emitting unit, a light emission side light distribution member, and a movable member. The optical member includes a first region configured to transmit or pass light having a first chromaticity. The optical member further includes a second region configured to transmit or pass light having a second chromaticity different from the first chromaticity. A light emission side light distribution member is disposed between the light emitting unit and the optical member, and is configured to define a distribution of light from the light emitting unit. The movable member is configured to move to change a distance between the light emitting unit and the light emission side light distribution member in a direction along an optical axis of the light emitting unit.

According to an embodiment of the present disclosure, a light emitting device having a high degree of freedom in color adjustment of light can be provided.

DETAILED DESCRIPTION

Hereinafter, embodiments for carrying out the invention will be described with reference to the drawings. Note that, hereinafter, parts having the same reference numerals appearing in a plurality of drawings indicate identical or equivalent parts or members. In a cross-sectional view, an end surface view illustrating only a cut surface may be used.

Further, while the embodiments described below are examples of light emitting devices embodying the technical concepts of the present invention, the present invention is not limited to the described embodiments. Unless otherwise specified, the dimensions, materials, shapes, relative arrangements, and the like of constituent elements described below are not intended to limit the scope of the present invention to those alone, but are intended to be illustrative. The size, positional relationship, and the like of the members illustrated in the drawings can be exaggerated in order to clarify explanation.

In the drawings described below, directions may be indicated by an X axis, a Y axis, and a Z axis. An X direction along the X axis indicates a predetermined direction in a plane including at least a first region provided with a light emitting device according to the embodiment, a Y direction along the Y axis indicates a direction orthogonal to the X direction in the plane described above, and a Z direction along the Z axis indicates a direction orthogonal to the plane described above.

Also, the direction in the X direction in which the arrow faces is the +X direction and the opposite direction to the +X direction is the −X direction, the direction in the Y direction in which the arrow faces is the +Y direction and the opposite direction to the +Y direction is the −Y direction, and the direction in the Z direction in which the arrow faces is the +Z direction and the opposite direction to the +Z direction is the −Z direction. In the embodiments, a light emitting unit of the light emitting device irradiates light in the +Z direction as an example. Further, an optical axis of the light emitting unit extends along the Z axis. Along the Z axis in this specification includes the subject having a slope within a range of ±10° relative to the Z axis. However, this does not limit the orientation of the light emitting device during use, and the orientation of the light emitting device may be any desired orientation.

A light emitting device according to the embodiment includes a light emitting unit, an optical member configured to transmit or pass light emitted by the light emitting unit, and a movable member configured to change a distance between the light emitting unit and the optical member. Alternatively, the light emitting device according to an embodiment includes: a light emitting unit; an optical member configured to transmit or pass light emitted by the light emitting unit; a light emission side light distribution member disposed between the light emitting unit and the optical member, and configured to define a distribution of light from the light emitting unit; and a movable member configured to change a distance between the light emitting unit and the light emission side light distribution member. This movable member changes the distance between the light emitting unit and the optical member in a direction along an optical axis of the light emitting unit. Further, this movable member changes the distance between the light emitting unit and the light emission side light distribution member in a direction along the optical axis of the light emitting unit. Such a light emitting device is used in applications such as various lighting or light irradiation.

In an embodiment, the optical member includes a first region in which light having a first chromaticity is allowed to be extracted and a second region in which light having a second chromaticity different from the first chromaticity is allowed to be extracted, and is allowed to extract, of the light emitted by the light emitting unit, mixed light formed by light being transmitted or passed through each of the first region and the second region and then being mixed. Further, in an embodiment, the distance between the light emitting unit and the optical member, or the distance between the light emitting unit and the light emission side light distribution member is changed in a direction along the optical axis of the light emitting unit by the movable member. Thus, a light emitting device that can change the chromaticity of mixed light and has a high degree of freedom in color adjustment of light is provided. Here, the term “color adjustment” refers to adjustment of the color of light.

Embodiments will be described below in detail.

First Embodiment

Configuration Example of Light Emitting Device1

FIGS.1A and1Bare schematic diagrams illustrating an example of a configuration of a light emitting device1according to a first embodiment.FIG.1Ais a top view, andFIG.1Bis a cross-sectional view along cutting line IA-IA inFIG.1A.

As illustrated inFIGS.1A and1B, the light emitting device1includes a light emitting unit mounting substrate11, a light emitting element12, a support13, a wavelength conversion plate14, and an actuator15.

The light emitting unit mounting substrate11is a plate-shaped member having a substantially rectangular shape in a plan view, and is a substrate provided with wirings to which light emitting elements and various electrical elements can be mounted. A substrate of various materials such as a metal substrate, a paper phenol substrate, a paper epoxy substrate, or a glass epoxy substrate can be applied to the light emitting unit mounting substrate11.

The light emitting element12is mounted on a surface of the light emitting unit mounting substrate11on the +Z direction side, and is an example of a light emitting unit that emits light. The light emitting element12is a semiconductor element that emits light by itself when voltage is applied. The light emitting element12includes at least a semiconductor layered body and is provided with at least a pair of electrodes having different polarities, for example, a p-side electrode and an n-side electrode.

As the material of the semiconductor, preferably a nitride semiconductor is used. This material can emit short wavelength light which can efficiently excite a wavelength conversion substance such as phosphor included in the wavelength conversion member. The nitride semiconductor is mainly represented by the general formula InxAlyGa1-x-yN (0≤x, 0≤y, x+y≤1). An emission peak wavelength of the light emitting element12is preferably in a range from 400 nm to 530 nm, more preferably in a range from 420 nm to 490 nm, and even more preferably in a range from 450 nm to 475 nm from the viewpoints of light emission efficiency, excitation of the wavelength conversion substance, a color mixing relationship with the light emission thereof, and the like. Further, as the material of the semiconductor, an InAlGaAs semiconductor, an InAlGaP semiconductor or the like can be used. As an example in the present disclosure, a light emitting device employing a light emitting element that emits blue light will be described as the light emitting element12.

Note that the light emitting unit of the light emitting device1is not limited to the light emitting element12, and various types of light sources can be used, such as a xenon lamp or a light emitting device (LED) in which the light emitting element12is inserted in a package. However, in order to efficiently excite the wavelength conversion substance contained in the wavelength conversion member, a light emitting element that emits light of a short wavelength is preferable.

The support13is a cylindrical member having a cross section orthogonal to the Z axis that is substantially rectangular. A central axis of the cylinder is along the Z axis. The support13is provided on a surface of the light emitting unit mounting substrate11on the +Z direction side so that the light emitting element12is disposed inside the cylinder.

A material of the support13is not particularly limited, and a metal material, a resin material, or the like can be selected as appropriate according to the application of the light emitting device1.

The wavelength conversion plate14is an example of an optical member including a first region141in which light having a first chromaticity can be extracted and a second region142in which light having a second chromaticity different from the first chromaticity can be extracted, and is configured to transmit light emitted by the light emitting element12.

The first region141is provided substantially in a center of the wavelength conversion plate14formed into a plate shape, and is formed into a substantially rectangular shape in a plan view. The first region141includes a wavelength conversion member that converts light emitted by the light emitting element12into light of a first wavelength. In the first region141, the light of the first wavelength converted by the wavelength conversion member can be extracted as the light having the first chromaticity. InFIG.1B, the light emitted by the light emitting element12is indicated by a solid line, and light121having the first chromaticity is indicated by a dashed line.

The second region142is a region around the first region141of the wavelength conversion plate14, surrounding the first region141, and has an outer shape that is substantially rectangular in a plan view. The second region142includes a wavelength conversion member that converts the light emitted by the light emitting element12into light of a second wavelength. In the second region142, the light of the second wavelength converted by the wavelength conversion member can be extracted as the light having the second chromaticity. InFIG.1B, light122having the second chromaticity is indicated by a dotted line.

The wavelength conversion member included in each of the first region141and the second region142may be a member in which a wavelength conversion substance is contained in a base member such as a resin, for example, silicone, glass, ceramic, or the like, may be a member in which the wavelength conversion substance is printed on a front surface of a molded body such as glass, or may be a sintered body of the wavelength conversion substance. The wavelength conversion substance is a member that absorbs at least a portion of primary light emitted by the light emitting element, and emits secondary light of a wavelength different from that of the primary light.

Examples of the wavelength conversion substance include an yttrium aluminum garnet based phosphor (Y3(Al,Ga)5O12:Ce, for example), a lutetium aluminum garnet based phosphor (Lu3(Al,Ga)5O12:Ce, for example), a terbium aluminum garnet based phosphor (Tb3(Al,Ga)5O12:Ce, for example), a β-SiALON based phosphor ((Si,Al)3(O,N)4:Eu, for example), an a based SiAlON phosphor (Ca(Si,Al)12(O,N)16:Eu, for example), a nitride based phosphor such as a CASN based phosphor (CaAlSiN3:Eu, for example) or an SCASN based phosphor ((Sr,Ca)AlSiN3:Eu, for example), a fluoride based phosphor such as a KSF based phosphor (K2SiF6:Mn, for example), a KSAF based phosphor (K2(Si,Al)F6:Mn, for example), or an MGF based phosphor (3.5MgO.0.5 MgF2GeO2:Mn, for example), a phosphor having a perovskite structure (CsPb(F,Cl,Br,I)3, for example), and a quantum dot phosphor (CdSe, InP, AgInS2, or AgInSe2, for example). The phosphor described above is a particle. Further, one type of these wavelength conversion substances can be used alone, or two or more types of these wavelength conversion substances can be used in combination.

The actuator15is an example of a movable member that changes the distance between the light emitting element12and the wavelength conversion plate14. The actuator15includes a mover151that can move along the Z axis, and is provided on the support13. An optical axis12cof the light emitting element12substantially matches a center of a light emitting surface of the light emitting element12and corresponds to an optical axis of the light emitting unit. The actuator15can change the distance between the light emitting element12and the wavelength conversion plate14in a direction along the optical axis12cof the light emitting element12.

As the actuator15, a voice coil motor in which a mover including a coil moves in translation in a magnetic field created by magnets, a supersonic motor that converts natural vibration generated by a metal elastic body into translational movement of a mover by frictional force, or the like can be used.

However, the movable member is not limited to the configuration described above, and may be any appropriate configuration as long as the distance between the light emitting element12and the wavelength conversion plate14can be changed in the direction along the optical axis12cof the light emitting element12. For example, the movable member may have a configuration in which a drive unit, such as a motor, is not provided, and an individual manually changes the distance between the light emitting element12and the wavelength conversion plate14in the direction along the optical axis12cof the light emitting element12, and then fixes the wavelength conversion plate14.

The mover151is formed in a cylindrical shape having a substantially rectangular cross section orthogonal to the Z axis, and the wavelength conversion plate14is fixed to an inner surface of the cylinder. The actuator15, by moving the mover151along the Z axis, can move the wavelength conversion plate14along the Z axis and change the distance between the light emitting element12and the wavelength conversion plate14.

Note that, as the wavelength conversion plate14, a plate-shaped member having a substantially rectangular shape in a plan view has been exemplified, but the shape is not limited thereto and may be, for example, a substantially circular shape or a substantially polygonal shape, and need not be plate-shaped, such as sheet-shaped, for example. The first region141may also have a substantially circular shape or a substantially polygonal shape or the like in a plan view.

Similarly, as the support13and the actuator15, a cylindrical member having a substantially rectangular cross section orthogonal to the axis of the cylinder has been exemplified, but the cross section is not limited thereto. The cross section may be a substantially circular shape, a substantially polygonal shape, or the like according to the shape of the wavelength conversion plate14.

Example of Production Method of Wavelength Conversion Plate14

Here, a production method of the wavelength conversion plate14will be described.FIGS.2A to2Fare diagrams for explaining an example of the production method of the wavelength conversion plate14in the light emitting device1.FIG.2AtoFIG.2Fare schematic diagrams illustrating each production step.

InFIGS.2A to2F,21ato21fare top views of the wavelength conversion plate14in each production step. Further,22ato22fare cross-sectional views respectively along the cutting line IIA-IIA to the cutting line IIF-IIF illustrated in the top view of each production step.

First, as illustrated inFIG.2A, a wavelength conversion member24included in the second region142is applied and cured on a base23. Subsequently, as illustrated inFIG.2B, a plurality of recessed portions25each having a substantially rectangular shape in a plan view are formed in the wavelength conversion member24on the base23by a punching process. The recessed portion25is a hole penetrating the wavelength conversion member24and reaches the surface of the base23. The number of recessed portions25can be adjusted as appropriate according to the number of wavelength conversion plates14produced from one base23. Note that the recessed portion25need not necessarily penetrate the wavelength conversion member24.

Subsequently, as illustrated inFIG.2C, liquid droplets for a wavelength conversion member26included in the first region141are supplied into the recessed portions25formed inFIG.2Bby a potting process. Subsequently, as illustrated inFIG.2D, the droplets of the wavelength conversion member26supplied into the recessed portions25are cured.

Subsequently, as illustrated inFIG.2E, the wavelength conversion member24and the base23are cut to desired sizes by a cutting process. A cut portion27represents a portion cut by the cutting process. Subsequently, as illustrated inFIG.2F, the base23is removed. Thus, the wavelength conversion plate14is completed.

The wavelength conversion plate14can be produced by such production steps. Note that the production method of the wavelength conversion plate14may include steps other than the steps illustrated inFIGS.2A to2F.

Next,FIGS.3A and3Bare schematic diagrams for explaining another example of the production method of the wavelength conversion plate14in the light emitting device1.FIG.3AandFIG.3Bare schematic diagrams illustrating a part of the production steps. InFIGS.3A and3B,31aand31brepresent top views of the wavelength conversion plate14in a part of the production steps. Further,32aand32bare cross-sectional views respectively along the cutting line IIIA-IIIA and the cutting line IIIB-IIIB illustrated in the top view of each production step.

FIG.3Aillustrates a state in which, similar to the production steps illustrated inFIGS.2A and2B, the recessed portions25having a substantially rectangular shape in a plan view are formed in the wavelength conversion member24on the base23by a punching process.

FIG.3Billustrates a state in which wavelength conversion members28formed in advance at a size that can be fitted into the recessed portions25are fitted into the recessed portions25. Subsequently, similar to the production step illustrated inFIG.2E, the wavelength conversion member24and the base23are cut to desired sizes by a cutting process. Subsequently, similar to the production step illustrated inFIG.2F, the base23is removed. Thus, the wavelength conversion plate14is completed.

The wavelength conversion plate14can also be produced by such production steps.

Color Adjustment of Light Emitting Device1

FIGS.4A and4Bare schematic diagrams for explaining color adjustment of the light emitting device1.FIG.4Ais a schematic diagram illustrating before a color change, andFIG.4Bis a schematic diagram illustrating after a color change.FIGS.4A and4B, similar toFIG.1B, illustrate a cross section along the cutting line IA-IA ofFIG.1A.

InFIG.4A, a distance between a surface of the wavelength conversion plate14on a light emitting element12side and a surface of the light emitting element12on the wavelength conversion plate14side is d1. In this state, substantially the entire light emitted by the light emitting element12passes through the first region141.

The light emitting device1emits the light having the first chromaticity extracted in the first region141. The wavelength conversion member included in the first region141has a light diffusion action due to the wavelength conversion substance, and thus the light extracted from the first region141has a higher light diffusivity compared to that of the light emitted by the light emitting element12. Note that, hereinafter, for ease of explanation, the distance between the surface of the wavelength conversion plate14on the light emitting element12side and the surface of the light emitting element12on the wavelength conversion plate14side is referred to as an optical member distance.

FIG.4Billustrates a state in which the wavelength conversion plate14has been raised in the +Z direction from the state illustrated inFIG.4Aand then stopped by the driving of the actuator15. The optical member distance is d2(d2>d1). In this state, a portion of the light emitted by the light emitting element12is transmitted through the first region141and the other portion is transmitted through the second region142.

The light emitting device1emits mixed light formed by the light having the first chromaticity extracted in the first region141and the light having the second chromaticity extracted in the second region142being mixed. The light extracted in each of the first region141and the second region142has a high light diffusivity with respect to the light emitted by the light emitting element12due to the light diffusion action of the wavelength conversion member, and thus the action of suppressing color unevenness or illuminance unevenness of the mixed light is achieved.

Depending on the optical member distance, a ratio of light intensity between the light121having the first chromaticity and the light122having the second chromaticity changes, changing the chromaticity of the mixed light. The light emitting device1can, by changing the optical member distance, adjust the chromaticity of the mixed light and emit color-adjusted light.

Because there is a corresponding relationship between a position of the mover151and the chromaticity of the light to be emitted, color adjustment can be precisely achieved when the light emitting device1is provided with a detection member that detects the position of the mover151and the color is adjusted on the basis of the detection result of the position of the mover151.

Chromaticity Change Example

Next,FIGS.5A to5Dare diagrams illustrating an example of a chromaticity change of the light emitting device1.FIGS.5A to5Care schematic diagrams illustrating states of the light emitting device1, andFIG.5Dis an xy chromaticity diagram.

In the example illustrated inFIGS.5A to5D, in the first region141, the light emitted by the light emitting element12is converted into light of a wavelength corresponding to white (first chromaticity) near chromaticity coordinates (x, y)=(0.33, 0.34) with the color temperature 5500 K in a CIE1931 chromaticity diagram as the target. Further, in the second region142, the light emitted by the light emitting element12is converted into light of a wavelength corresponding to yellow (second chromaticity) that is in a range from 550 nm to 590 nm.

The optical member distance is dainFIG.5A, the optical member distance is dbinFIG.5B, and the optical member distance is dcinFIG.5C. The optical member distances satisfy da<db<dc. The xy chromaticity diagram illustrated inFIG.5Dindicates chromaticity with chromaticity coordinates x and y as coordinate axes. Plot31inFIG.5Dindicates the chromaticity of the mixed light in the state ofFIG.5A, plot32indicates the chromaticity of the mixed light in the state ofFIG.5B, and plot33indicates the chromaticity of the mixed light in the state ofFIG.5C.

As shown inFIG.5D, the chromaticity of the mixed light changes according to the optical member distance. A chromaticity change30inFIG.5Dresults in a change nearly linear along a line connecting the plots31,32,33. Because the actuator15can change the optical member distance to any distance, the light emitting device1can change the chromaticity of the light to any chromaticity according to the change in the optical member distance.

Action and Advantageous Effects of Light Emitting Device1

As described above, the light emitting device1includes the light emitting element12(light emitting unit), the wavelength conversion plate14(optical member) configured to transmit or pass light emitted by the light emitting element12, and the actuator15(movable member) configured to change the distance between the light emitting element12and the wavelength conversion plate14. The actuator15changes the distance between the light emitting element12and the wavelength conversion plate14in the direction along the optical axis12cof the light emitting element12.

The wavelength conversion plate14includes the first region141in which the light121having the first chromaticity can be extracted and the second region142in which the light122having the second chromaticity different from the first chromaticity can be extracted, and can extract, of the light emitted by the light emitting element12, mixed light formed by light being transmitted or passed through each of the first region141and the second region142and then being mixed.

In this embodiment, the optical member distance between the light emitting element12and the wavelength conversion plate14is changed by the actuator15, and consequently, the ratio of the light intensity between the light121having the first chromaticity and the light122having the second chromaticity is changed according to the optical member distance, thereby changing the chromaticity of mixed light. The light emitting device1can change the chromaticity of light to any chromaticity according to the change in the optical member distance caused by the actuator15. This makes it possible to provide a light emitting device having a high degree of freedom in color adjustment of light.

Further, in this embodiment, the first region141includes the wavelength conversion member configured to convert the light emitted by the light emitting element12into light of the first wavelength, and the second region142includes the wavelength conversion member configured to convert the light emitted by the light emitting element12into light of the second wavelength. In this embodiment, the first wavelength and the second wavelength may be different or may be the same. In a case in which the first wavelength and the second wavelength are different, the wavelength conversion member in the first region and the wavelength conversion member in the second region include wavelength conversion substances different from each other, for example. In a case in which the first wavelength and the second wavelength are the same, the wavelength conversion substances included in the wavelength conversion member in the first region and the wavelength conversion member in the second region may be the same with different concentrations, for example. Further, in a case in which there are a plurality of types of wavelength conversion substances included in both the wavelength conversion member in the first region and the wavelength conversion member in the second region and the same types of wavelength conversion substances are included in these members, blending ratios of the wavelength conversion substances included in the first region and the second region may be different.

As the wavelength conversion members included in each of the first region141and the second region142, members that convert wavelengths to a variety of wavelengths can be selected, making it possible to mix the light converted by each wavelength conversion member and thus further increase the degree of freedom of color adjustment of light. Further, the wavelength conversion member further diffuses the light emitted by the light emitting element12, making it possible to suitably suppress the color unevenness or the illuminance unevenness of the mixed light.

Further, in this embodiment, the second region142surrounds the first region141. As a result, for example, in the plane including the first region141, anisotropy of the color mixture of the light converted in the second region142and the light converted in the first region141is suppressed, making it possible to suppress the color unevenness of the light color-adjusted in the light emitting device1. From the viewpoint of suppressing color unevenness, the second region142is preferably around the first region141, surrounding the first region141.

Further, although white light is exemplified as the first chromaticity and yellow light is exemplified as the second chromaticity in this embodiment, the chromaticity of each is not limited thereto, and the first chromaticity and the second chromaticity can be selected as appropriate according to the application of the light emitting device1.

Furthermore, in this embodiment, the second region142may include a passing portion through which the light emitted by the light emitting element12passes without wavelength conversion. The passing portion includes a material having light transmittance with respect to, of the light emitted by the light emitting element12, at least wavelengths of visible light. The wavelength of visible light is in a range from 380 nm to 780 nm.

In the second region142, light emitted by the light emitting element12and passed through the passing portion can be extracted as the light having the second chromaticity. The second region142is, for example, glass or a resin such as polycarbonate or silicone.

At this time, the wavelength conversion plate14can be produced by, for example, fitting a member constituting the first region141into a through hole of a plate-shaped member configured to include a material having light transmittance with respect to visible light, the through hole being formed at a position corresponding to the first region141.

Note that the first region141can also be configured to include a passing portion through which light emitted by the light emitting element12passes without wavelength conversion. That is, a wavelength conversion plate in which only one of the first region141or the second region142includes a wavelength conversion substance can also be used.

First Modified Example of First Embodiment

Next, a light emitting device1aaccording to a first modified example of the first embodiment will be described. Note that components that are the same as those described in the above-mentioned embodiment will be denoted by the same reference numerals, and redundant descriptions thereof will be omitted as appropriate. This is also true for each of the following embodiments and modified examples.

Configuration Example of Light Emitting Device1a

FIGS.6A and6Bare cross-sectional views illustrating an example of a configuration of the light emitting device1a.FIG.6Ais a view illustrating before a color change, andFIG.6Bis a view illustrating after a color change.FIGS.6A and6Billustrate cross sections including a first region and a second region of a filter plate of the light emitting device1a.

As illustrated inFIGS.6A and6B, the light emitting device1aincludes a filter plate14aand an LED12a. The filter plate14ais an example of an optical member including a first region141ain which light having the first chromaticity can be extracted and a second region142ain which light having the second chromaticity different from the first chromaticity can be extracted, and is configured to transmit or pass light emitted by the LED12a.

The first region141ais provided in a central portion of the filter plate14aformed into a plate shape, and includes a passing portion that is a through hole through which the light emitted by the LED12apasses. This passing portion is formed into a substantially rectangular shape in a plan view. In the first region141a, the light emitted by the LED12aand passed through the first region141acan be extracted as the light having the first chromaticity. InFIGS.6A and6B, light121ahaving the first chromaticity is indicated by a solid line.

The second region142ais a region around the first region141aof the filter plate14a, surrounding the first region141a, and has an outer shape formed into a substantially rectangular shape in a plan view. The second region142aincludes a color filter that transmits, of the light emitted by the LED12a, the light of the second wavelength. In the second region142a, the light of the second wavelength that has passed through the color filter can be extracted as the light having the second chromaticity. InFIGS.6A and6B, light122ahaving the second chromaticity is indicated by a dot-dash line.

The color filter included in the second region142ais a member containing a dye substance composed of an inorganic compound or an organic compound including a metal oxide, with a resin, such as silicone, or glass as a base material, for example. The dye substance is a member that absorbs at least a portion of primary light emitted by the LED12aand transmits secondary light including a portion of wavelengths included in the primary light.

The filter plate14acan be produced by forming a through hole corresponding to the first region141ain a plate-shaped member including the color filter.

The LED12ais an example of a light emitting unit that emits light and is mounted on the surface of the light emitting unit mounting substrate11on the +Z direction side. The LED12aemits white light, for example. The LED12aincludes at least a light emitting element125including at least one pair of electrodes128having different polarities, a wavelength conversion member126disposed on the light emitting element125and containing a wavelength conversion substance, and a covering member127having light reflectivity and covering at least a lateral surface of the light emitting element125and a lateral surface of the wavelength conversion member126. A shape of the LED12ain a plan view is, for example, a square with one side being in a range from 1 mm to 3 mm.

As the light emitting element125of the LED12a, an element that is the same as the light emitting element12illustrated in the first embodiment can be used. Further, as the wavelength conversion member126of the LED12a, a member that is the same as the wavelength conversion member included in the wavelength conversion plate14described in the first embodiment can be used. A shape of the light emitting element125of the LED12ain a plan view and a shape of the wavelength conversion member126of the LED12ain a plan view are each, for example, a square with one side being in a range from 0.5 mm to 2 mm. In a plan view, a size of the wavelength conversion member126is preferably equivalent to or larger than that of the light emitting element125.

The covering member127preferably has light reflectivity in order to extract light from the light emitting element125toward an upper surface side (+Z direction), and preferably has an outer peripheral width of 50 μm or greater in a plan view. For example, the light reflectivity of the covering member127with respect to an emission peak wavelength of the light emitting element125is preferably 70% or greater, more preferably 80% or greater, and even more preferably 90% or greater. Further, the covering member127is preferably white, and preferably contains a white pigment, such as titanium oxide, magnesium oxide, or the like, for example, in the base material of the covering member127. Examples of the base material of the covering member127include a resin such as silicone, epoxy, phenol, polycarbonate, acrylic, and the like, or a modified resin thereof.

Note that the light emitting unit of the light emitting device1ais not limited to the LED12a, and various types of light sources such as a xenon lamp can be utilized. However, it is preferable that the light emitting device1aemits white light in order for the filter plate14ato selectively transmit light of various wavelengths.

Color Adjustment of Light Emitting Device1a

InFIG.6A, the optical member distance between a surface of the filter plate14aon the −Z direction side and a surface of the LED12aon the +Z direction side is d1. In this state, almost all of the light emitted by the LED12apasses through the entire first region141a. The light emitting device1aemits the light of the first chromaticity extracted in the first region141a.

FIG.6Billustrates a state in which the filter plate14ahas been raised in the +Z direction from the state illustrated inFIG.6Aand then stopped by the driving of the actuator15. The optical member distance is d2(d2>d1). In this state, a portion of the light emitted by the LED12apasses through the first region141aand the other portion is transmitted through the second region142a.

The light emitting device1aemits mixed light formed by the light having the first chromaticity extracted in the first region141aand the light having the second chromaticity extracted in the second region142abeing mixed. Depending on the optical member distance, a ratio of light intensity between the light121ahaving the first chromaticity and the light122ahaving the second chromaticity changes, changing the chromaticity of the mixed light. The light emitting device1acan, by changing the optical member distance, adjusted the chromaticity of the mixed light and emit color-adjusted light.

Action and Advantageous Effects of Light Emitting Device1a

As described above, the light emitting device1aincludes the LED12a(light emitting unit), the filter plate14a(optical member) configured to transmit or pass light emitted by the LED12a, and the actuator15(movable member) configured to change the distance between the LED12aand the filter plate14a. The actuator15changes the distance between the LED12aand the filter plate14ain the direction along an optical axis12acof the LED12a.

The filter plate14aincludes the first region141ain which the light121ahaving the first chromaticity can be extracted and the second region142ain which the light122ahaving the second chromaticity different from the first chromaticity can be extracted, and can extract, of the light emitted by the LED12a, mixed light formed by the light passed through the first region141aand the light transmitted through the second region142abeing mixed.

The light emitting device1achanges the chromaticity of the mixed light by changing the distance between the LED12aand the filter plate14aby the actuator15. The light emitting device1acan change the chromaticity of the light to any chromaticity according to the change in the optical member distance caused by the actuator15. This makes it possible to provide a light emitting device having a high degree of freedom in color adjustment of light.

Further, in this embodiment, the filter plate14ais configured to including a color filter, making it possible to fabricate the optical member with ease at low cost.

Second Modified Example of First Embodiment

Next,FIGS.7A and7Bare cross-sectional views illustrating an example of a configuration of a light emitting device1baccording to a second modified example of the first embodiment.FIG.7Ais a view illustrating before a color change, andFIG.7Bis a view illustrating after a color change.FIGS.7A and7Billustrate cross sections including a first region and a second region of a filter plate of the light emitting device1b.

As illustrated inFIGS.7A and7B, the light emitting device1bincludes a filter plate14b. The filter plate14bincludes a first region141band a second region142b.

The first region141bis provided in a central portion of the filter plate14bformed into a plate shape, and includes a color filter that transmits, of the light emitted by the LED12a, the light of a first wavelength. The first region141bis formed into a substantially rectangular shape in a plan view. In the first region141b, light emitted by the LED12aand transmitted through the first region141bcan be extracted as the light having the first chromaticity. InFIGS.7A and7B, light121bhaving the first chromaticity is indicated by a dot-dash line.

The second region142bis a region around the first region141bof the filter plate14b, surrounding the first region141b, and has an outer shape formed into a substantially rectangular shape in a plan view. The second region142bincludes a passing portion through which the light emitted by the LED12apasses without wavelength conversion. The passing portion included in the second region142bincludes a material having light transmittance with respect to at least the wavelengths of visible light of the light emitted by the LED12a. The wavelength of visible light is in the range from 380 nm to 780 nm.

In the second region142a, light emitted by the LED12aand passed through the passing portion can be extracted as the light having the second chromaticity. The second region142ais, for example, glass or a resin such as polycarbonate or silicone. InFIGS.7A and7B, the light of the LED12aand light122bhaving the second chromaticity are indicated by solid lines.

The filter plate14bcan be produced by fitting a member constituting the first region141binto a through hole of a plate-shaped member configured to include a material having light transmittance with respect to visible light, the through hole being formed at a position corresponding to the first region141b, or the like.

The color adjustment action and advantageous effects of the light emitting device1bare similar to those of the light emitting device1a. Note that although examples have been illustrated in which either the first region or the second region is a filter plate including a color filter in the light emitting device1baccording to this modified example and the light emitting device1aaccording to the first modified example, a filter plate including a color filter can be used for both the first region and the second region. Further, one of the first region and the second region can be a filter plate including a color filter, and the other can be a wavelength conversion plate including a wavelength conversion sub stance.

Third Modified Example of First Embodiment

FIGS.8A and8Bare cross-sectional views illustrating an example of a configuration of a light emitting device1caccording to a third modified example of the first embodiment.FIG.8Ais a view illustrating before a color change, andFIG.8Bis a view illustrating after a color change.FIGS.8A and8Billustrate cross sections including a first region and a second region of a wavelength conversion plate of the light emitting device1c.

As illustrated inFIGS.8A and8B, the light emitting device1cincludes a light diffusion unit16. The light diffusion unit16is provided on a side opposite to the light emitting element12with the wavelength conversion plate14interposed between the light diffusion unit16and the light emitting element12, and is configured to diffuse light transmitted or passed through the wavelength conversion plate14.

The light diffusion unit16is configured to include a metal or a resin material, and is a plate-shaped member having an uneven shape in which a width and a height, being in the same range as or greater than the wavelength of the light emitted by the light emitting element12, vary randomly depending on the position. The uneven shape diffuses the light passing through the light diffusion unit16.

However, the light diffusion unit16is not limited to the above, and may be any appropriate member as long as a member that diffuses transmitted light. For example, the light diffusion unit may be configured to include a resin material containing scattering particles.

The color adjustment action of the light emitting device1cis similar to that of the light emitting device1described above.

Action and Advantageous Effects of Light Emitting Device1c

The light transmitted through the light diffusion unit16has a higher light diffusivity with respect to the light transmitted through the wavelength conversion plate14due to a light diffusion action of the light diffusion unit16. As a result, the color unevenness or the illuminance unevenness of the light mixed upon transmission through the wavelength conversion plate14can be suppressed.

AlthoughFIGS.8A and8Billustrate a configuration in which the light emitting device1cincludes the wavelength conversion plate14, the light emitting device1cmay include a filter plate instead of the wavelength conversion plate14. Although the color unevenness or the illuminance unevenness of the mixed light tends to increase due to the low light diffusivity of the filter plate with respect to the wavelength conversion plate, by providing the light diffusion unit16, such unevenness can suitably be suppressed.

Further, instead of providing the light diffusion unit16, light diffusivity can be enhanced and the color unevenness or the illuminance unevenness of the mixed light can be suppressed, by forming an uneven shape or the like on at least one surface of the wavelength conversion plate or the filter plate on the +Z direction side or the −Z direction side to roughen the surface. Alternatively, at least one of the first region and the second region of the wavelength conversion plate or the filter plate may be configured to include a resin material containing scattering particles.

Further, the light diffusion unit16also functions as a cover for the light emitting device1cand thus, by providing the light diffusion unit16, foreign matter can be prevented from entering the light emitting device1cor the like, and the aesthetic appeal of the light emitting device1ccan be improved.

Second Embodiment

Configuration Example of Light Emitting Device1d

FIGS.9A and9Bare cross-sectional views illustrating a configuration of a light emitting device1daccording to a second embodiment.FIG.9Ais a view illustrating before a color change, andFIG.9Bis a view illustrating after a color change.FIGS.9A and9Billustrate a cross section including a first region and a second region of a wavelength conversion plate of the light emitting device1d.

As illustrated inFIGS.9A and9B, the light emitting device1dincludes a Fresnel lens17and an actuator15d.

The Fresnel lens17is an example of a light emission side light distribution member disposed between the light emitting element12and the wavelength conversion plate14and configured to define a distribution of light from the light emitting element12, and is an example of a lens included in the light emission side light distribution member.

The Fresnel lens17is a lens formed so that a curved surface of the lens is divided into regions having substantially concentric circular shapes and folded within a desired thickness. As illustrated inFIGS.9A and9B, the Fresnel lens17has a saw blade-like cross-sectional shape. Further, the Fresnel lens17has a substantially concentric circular shape axisymmetric about the optical axis12cof the light emitting element12.

Optical characteristics of the Fresnel lens17, such as light distribution characteristics, can be selected as appropriate according to the application of the light emitting device1d. The optical characteristics of the Fresnel lens17can be determined by widths or heights of the circles in the substantially concentric circular shape, and the like. Such a Fresnel lens17can be produced by injection molding of a resin material or the like.

The Fresnel lens17is attached to a surface of the wavelength conversion plate14on the −Z direction side. However, the Fresnel lens17may be adhered to the surface of the wavelength conversion plate14on the −Z direction side using an adhesive or the like, and the Fresnel lens17and the wavelength conversion plate14may be integrally formed.

The light emitted by the light emitting element12enters the Fresnel lens17and, after being changed in propagation direction due to refraction or diffraction by the Fresnel lens17, enters the wavelength conversion plate14. The converted light of each of the first region141and the second region142included in the wavelength conversion plate14is mixed.

The actuator15dis an example of a movable member that changes the distance between the light emitting element12and the Fresnel lens17. The actuator15dchanges the distance between the light emitting element12and the Fresnel lens17, as a result, the chromaticity of the mixed light is changed. The configuration of the actuator15dis similar to that of the actuator15, with the targets for which the distance is changed differing from those of the actuator15.

Action and Advantageous Effects of Light Emitting Device1d

In this embodiment, the Fresnel lens17(light emission side light distribution member) is provided between the light emitting element12and the wavelength conversion plate14, thereby changing a light distribution angle of the light transmitted through the Fresnel lens17. As a result, the light distribution angle of the light color-adjusted by the light emitting device1dcan be changed. Further, the substantially concentric circular shape of the Fresnel lens17can be made eccentric with respect to the optical axis12cof the light emitting element12, and the direction in which the color-adjusted light is emitted can also be changed.

Further, by disposing the Fresnel lens17between the light emitting element12and the wavelength conversion plate14, a spread of light emitted by the light emitting element12can be suppressed, and thus an area of the wavelength conversion plate14and a size of the light emitting device1dcan be reduced. Further, a distance across which the wavelength conversion plate14is moved by the actuator15dcan be shortened compared to a case in which the Fresnel lens17is not disposed, making it possible to reduce the size of the light emitting device1din this regard as well.

Note that the advantageous effects other than those described above are similar to those indicated in the first embodiment.

Further, although this embodiment exemplifies a configuration in which the Fresnel lens17is attached to the surface of the wavelength conversion plate14on the −Z direction side, the position is not limited thereto, and the Fresnel lens17may be disposed at any appropriate position as long as between the light emitting element12and the wavelength conversion plate14. That is, the position of the wavelength conversion plate14may be fixed, and the Fresnel lens17may move between the light emitting element12and the wavelength conversion plate14by the actuator15d.

Further, although this embodiment exemplifies the Fresnel lens17as the light emission side light distribution member, the member is not limited thereto, and various lenses such as a plano-convex lens, a biconvex lens, a meniscus lens, or a combination thereof can be used as the light emission side light distribution member. However, when the Fresnel lens17is used, a thickness of the lens can be reduced, which is more preferable from the perspective of reducing the size of the light emitting device1d.

Further, although this embodiment exemplifies a configuration in which the light emitting device1dincludes the wavelength conversion plate14, the configuration may include the filter plate14aor14binstead of the wavelength conversion plate14. Further, the light emitting device1dneed not necessarily include the light diffusion unit16.

Further, instead of providing the Fresnel lens17, a substantially concentric circular shape can be formed on at least a portion of the surface of the wavelength conversion plate14on the light emitting element12side (surface on the −Z direction side). This can cause this surface to function as a Fresnel lens. In this case, the wavelength conversion plate14overlaps the light emitting element12in a plan view, and includes a light distribution member on the surface of the wavelength conversion plate14on the light emitting element12side, the light distribution member defining the distribution of the light from the light emitting element12. That is, the wavelength conversion plate14has a substantially concentric circular shape of a Fresnel lens on the surface of the wavelength conversion plate14on the light emitting element12side.

Here,FIGS.10A and10Bare cross-sectional views illustrating an example of a configuration of a light emitting device1daaccording to a modified example of the second embodiment,FIG.10Abeing a view before a color change, andFIG.10Bbeing a view after a color change. With such a configuration as well, an action and advantageous effects similar to those of the light emitting device1dcan be achieved.

Third Embodiment

Relationship Between Light Distribution Angle and Chromaticity in Light Emitting Device1e

Next,FIG.11is a schematic diagram illustrating a first example of a relationship between a light distribution angle and a color temperature of a light emitting device1eaccording to a third embodiment. An φ axis illustrated inFIG.11indicates the distribution angle of light emitted by the light emitting device1e, and a K axis indicates a color temperature of the light emitted by the light emitting device1e. A +φ direction indicates a direction in which the light distribution angle widens, and a −φ direction indicates a direction in which the light distribution angle narrows. A +K direction indicates a direction in which the color temperature increases, and a −K direction indicates a direction in which the color temperature decreases.

Further,FIG.11illustrates only a portion of the configuration of the light emitting device1e, and illustrates four states in which the light distribution angle φ and the color temperature K are different as light emitting devices1ea,1eb,1ec,1ed.

As illustrated inFIG.11, the light emitting device1eincludes a Fresnel lens18. The Fresnel lens18is an example of an irradiation side light distribution member that defines a distribution of the light transmitted or passed through the wavelength conversion plate14.

The Fresnel lens18is provided on the side opposite to the light emitting element12with the wavelength conversion plate14interposed between the Fresnel lens18and the light emitting element12, and is movable along the Z axis by an actuator separate from the actuator15. The configuration of the Fresnel lens18is similar to that of the Fresnel lens17illustrated in the second embodiment, with the disposed position different from that of the Fresnel lens17.

The Fresnel lens18changes the distribution of light emitted by the light emitting element12and transmitted or passed through the wavelength conversion plate14, thereby changing the distribution angle of the light color-adjusted by the light emitting device1d.

Here, a distance between an apex of a hemispherical region in a center of the Fresnel lens18and a surface of the wavelength conversion plate14on the Fresnel lens18side is referred to as a lens distance. As illustrated inFIG.11, a lens distance haof the light emitting device1eais equal to a lens distance hbof the light emitting device1eb, and a lens distance hcof the light emitting device1ecis equal to a lens distance haof the light emitting device1ed. The lens distance hcis longer than the lens distance ha. Accordingly, as the lens distance lengthens, the distribution angle of the light color-adjusted by the light emitting device1enarrows.

On the other hand, an optical member distance deaof the light emitting device1eais equal to an optical member distance decof the light emitting device1ec, and an optical member distance debof the light emitting device1ebis equal to an optical member distance deaof the light emitting device1ed. The optical member distance deais longer than the optical member distance deb. Accordingly, as the optical member distance lengthens, the color temperature of the light color-adjusted by the light emitting device1elowers.

FIG.12is an image diagram illustrating a second example of the relationship between the distribution angle and the color temperature of the light emitted by the light emitting device1e, and shows an image diagram of luminous flux emitted by the light emitting device1ewhen viewed from an emission direction side of the light emitting device1e. Specifically,FIG.12shows the light distribution angle φ and the color temperature K of the light emitted in each state of the light emitting devices1ea,1eb,1ec,1edas an image diagram.

InFIG.12, the images shown for the light emitting device1ecand the light emitting device1edhave small diameters of luminous flux and narrow light distribution angles compared to those of the images shown for the light emitting device1eaand the light emitting device1eb. InFIG.12, the images shown for the light emitting device1eaand the light emitting device1echave a reddish luminous flux and a low color temperature compared to those of the images shown for the light emitting device1eband the light emitting device1ed.

Action and Advantageous Effects of Light Emitting Device1e

As described above, in this embodiment, the Fresnel lens18(irradiation side light distribution member) that defines the distribution of the light transmitted or passed through the wavelength conversion plate14is provided on the side opposite to the light emitting element12(light emitting unit) with the wavelength conversion plate14(optical member) interposed between the Fresnel lens18and the light emitting element12.

The light distribution angle φ can be changed by changing the lens distance, and the color temperature can be changed by changing the optical member distance. As a result, the light emitting device1ecan emit light at a desired light distribution angle while increasing the degree of freedom of color adjustment.

Note that, although this embodiment exemplifies a configuration in which the Fresnel lens18is moved along the Z axis and the lens distance is changed by an actuator different from the actuator15, the configuration is not limited thereto. For example, the Fresnel lens18may be fixed and the wavelength conversion plate14may be moved along the Z axis to change the lens distance. Further, the Fresnel lens18and the wavelength conversion plate14may be integrated and moved by the actuator15.

Further, although this embodiment exemplifies a configuration in which the light emitting device1eincludes the wavelength conversion plate14, the configuration may include the filter plate14aor14binstead of the wavelength conversion plate14.

Further, the advantageous effects other than those described above are the same as those indicated in the first embodiment.

Modified Example of Third Embodiment

FIGS.13A and13Bare cross-sectional views illustrating an example of a configuration of a light emitting device1faccording to a modified example of the third embodiment.FIG.13Ais a view illustrating before a color change, andFIG.13Bis a view illustrating after a color change.FIGS.13A and13Billustrate cross sections including a first region and a second region of a wavelength conversion plate of the light emitting device1f.

As illustrated inFIGS.13A and13B, the light emitting device1fincludes an array lens19. The array lens19is an example of an irradiation side light distribution member that defines a distribution of the light transmitted or passed through the wavelength conversion plate14.

The array lens19is provided on the side opposite to the light emitting element12with the wavelength conversion plate14interposed between the array lens19and the light emitting element12. Further, the array lens19is integrated with the wavelength conversion plate14and movable along the Z axis by the actuator15. Here, the array lens19and the wavelength conversion plate14being integrated includes a state of separation and a state of contact between the array lens19and the wavelength conversion plate14.

The array lens19is an optical element including a plurality of lenses arrayed in two dimensions. The number, spacing, or arrangement of the plurality of the lenses, or the diameter, radius of curvature, shape, and the like of the individual lenses can be selected as appropriate according to the application of the light emitting device1f. Further, the array lens19can also be produced using materials such as glass or resin.

In this way, by providing the array lens19on the side opposite to the light emitting element12with the wavelength conversion plate14interposed between the array lens19and the light emitting element12, the distribution of the light emitted by the light emitting device1fcan be changed from, for example, a Lambert light distribution. Further, an interior of the light emitting device1fis not visible, making it also possible to improve the aesthetic appeal of the light emitting device1f.

Note that although this embodiment exemplifies a configuration in which the wavelength conversion plate14and the array lens19move integrally along the Z axis by the actuator15, the configuration is not limited thereto. For example, the array lens19may be movable along the Z axis independently of the wavelength conversion plate14by an actuator different from the actuator15. Further, although this embodiment exemplifies a configuration in which the light emitting device1fincludes the wavelength conversion plate14, the configuration may include the filter plate14aor14binstead of the wavelength conversion plate14.

Further, the advantageous effects other than those described above are the same as those indicated in the first embodiment.

Fourth Embodiment

Chromaticity Change Example of Light Emitting Device1g

Next,FIGS.14A to14Dare diagrams illustrating an example of a chromaticity change of a light emitting device1gaccording to a fourth embodiment.FIG.14AtoFIG.14Care schematic diagrams illustrating states of the light emitting device1g, andFIG.14Dis an xy chromaticity diagram. InFIG.14AtoFIG.14C, the light emitted by the light emitting element12is indicated by a solid line, and the light121having the first chromaticity is indicated by a dashed line.

As illustrated inFIGS.14A to14D, the light emitting device1gincludes a wavelength conversion plate14g. Further, the wavelength conversion plate14gincludes a first region141g, a second region142g, and a third region143g. The second region142gsurrounds the first region141g, and the third region143gsurrounds the second region142g.

In the third region143g, light having a third chromaticity different from each of the first chromaticity extracted in the first region141gand the second chromaticity extracted in the second region142gcan be extracted. The wavelength conversion plate14gcan extract mixed light formed by light transmitted or passed through each of the first region141g, the second region142g, and the third region143gand then being mixed. InFIG.14AtoFIG.14C, the light emitted by the light emitting element12is indicated by a solid line, the light having the first chromaticity is indicated by a dashed line, the light having the second chromaticity is indicated by a dotted line, and the light having a third chromaticity is indicated by a dot-dash line.

In the example illustrated inFIGS.14A to14D, in the first region141g, the light emitted by the light emitting element12is converted into light of a wavelength corresponding to white (first chromaticity) near chromaticity coordinates (x, y)=(0.33, 0.34) with the color temperature 5500 K in a CIE1931 chromaticity diagram as the target. Further, in the second region142g, the light emitted by the light emitting element12is converted into light of a wavelength corresponding to yellow (second chromaticity) that is in a range from 550 nm to 590 nm. Further, in the third region143g, the light emitted by the light emitting element12is converted into light of a wavelength corresponding to red (third chromaticity) that is from 640 nm to 770 nm.

The actuator15changes a distance between the light emitting element12and the wavelength conversion plate14g, as a result, the chromaticity of the mixed light is changed. The optical member distance is represented as dainFIG.14A, the optical member distance is represented as dbinFIG.14B, and the optical member distance is represented as dcinFIG.14C. Plot41inFIG.14Dindicates the chromaticity of the mixed light in the state ofFIG.14A, plot42indicates the chromaticity of the mixed light in the state ofFIG.14B, and plot43indicates the chromaticity of the mixed light in the state ofFIG.14C.

As shown inFIG.14D, the chromaticity of the mixed light changes according to the optical member distance. Here, a blackbody locus50shown inFIG.14Dindicates a chromaticity change of irradiated light in a case in which external light energy is fully absorbed and an ideal object (blackbody) that irradiates all energy at 100% is heated. With the chromaticity change30of the light emitting device1shown inFIG.5Ddescribed above, the plots31,32,33change substantially linearly, and thus deviate from the curve of the blackbody locus50.

In contrast, in this embodiment, the third region143g, in which red light can be extracted, surrounds the second region142g. Therefore, when the optical member distance increases, the light emitted by the light emitting element12reaches the third region143g, and red light is extracted in the third region143g. With this, the color of the light emitted by the light emitting device1gshifts toward red. As a result, a chromaticity change40of the mixed light is a change along the blackbody locus50.

Action and Advantageous Effects of Light Emitting Device1g

As described above, in this embodiment, the wavelength conversion plate14gincludes the third region143gin which the light having the third chromaticity different from each of the first chromaticity and the second chromaticity can be extracted, and can extract mixed light formed by light being transmitted through each of the first region141g, the second region142g, and the third region143gand then being mixed.

The actuator15changes the distance between the light emitting element12and the wavelength conversion plate14g, as a result, the chromaticity of the mixed light is changed. This chromaticity change40of light follows the blackbody locus50. Accordingly, the light emitting device1gcan extract and emit light that changes in chromaticity along the blackbody locus50.

Further, although this embodiment exemplifies a configuration in which the light emitting device1gdoes not include a light emission side light distribution member such as a Fresnel lens, the light emitting device1gmay include such a light emission side light distribution member. In this case, the actuator15changes the distance between the light emitting element12and the light emission side light distribution member, as a result, the chromaticity of the mixed light is changed. This chromaticity change of light follows the blackbody locus. Accordingly, an action and advantageous effects similar to those of the light emitting device1gdescribed above can be achieved.

Further, the light emitting device1gcan also include an irradiation side light distribution member such as a light diffusion unit or an array lens.

Fifth Embodiment

Next,FIGS.15A to15Dshow diagrams for illustrating a light emitting device1haccording to a fifth embodiment.FIG.15Ashows a schematic diagram illustrating the filter plate14a,FIG.15Bshows a schematic diagram illustrating the wavelength conversion plate14, andFIGS.15C and15Dshow xy chromaticity diagrams.

The light emitting device1his configured so that a plurality of optical members can be attached thereto and detached therefrom, and the filter plate14aand the wavelength conversion plate14can replace each other. For example, in an application for adjusting a color temperature, the filter plate14aincluding a first region in which white light emitted by an LED can be extracted and a second region

through which light emitted by an LED is transmitted and yellow (warm color) light can be extracted is mounted on the light emitting device1h.

On the other hand, in another application such as a color cast measure, the wavelength conversion plate14including a first region in which magenta light can be extracted and a second region in which green light can be extracted is mounted on the light emitting device1h. Note that the term “color cast” refers to a state in which the overall color of an image is shifted to a specific color.

The light emitting device1h, in a case in which the filter plate14ais mounted, can adjust the color along a chromaticity change60from white to yellow, as shown inFIG.15C. Further, the light emitting device1h, in a case in which the wavelength conversion plate14is mounted, can adjust the color along a chromaticity change70from magenta to green as shown inFIG.15D.

According to the configuration of the light emitting device1h, color adjustment of an even higher degree of freedom can be achieved. Note that the fifth embodiment can also be combined with the above-described embodiments.

Although the preferred embodiments and the like have been described in detail above, the disclosure is not limited to the above-described embodiments and the like, various modifications and substitutions can be made to the above-described embodiments and the like without departing from the scope described in the claims.

Note that the first region may include a passing portion through which light emitted by the light emitting unit passes, and the second region may include a transmitting portion through which light emitted by the light emitting unit is transmitted.

The light emitting device of the present invention can be suitably utilized for lighting, a camera flash, a vehicle headlight, and the like. However, the light emitting device of the present invention is not limited to these applications.