Patent ID: 12243960

DETAILED DESCRIPTION

Certain embodiments of the present disclosure will be explained in detail below with reference to the accompanying drawings. The embodiments described below are exemplary, and the light sources, light source device, and the methods of manufacturing the light sources according to the present disclosure are not limited to those described below. For example, the numerical values, shapes, materials, manufacturing steps, and the sequence of the steps described in the embodiments described below are merely examples, and are modifiable in various ways to the extent that such a modification does not cause technical inconsistencies. Each of the embodiments described below is merely exemplary, and various combinations can be made to the extent that such a combination does not cause technical inconsistencies.

The sizes, shapes, and the like of the constituent elements shown in the drawings might be exaggerated for clarity of explanation, and might not reflect the sizes and shapes of, and the relative sizes among the constituent elements in an actual light source. Certain elements might be omitted in a drawing or only a cut end face might be used as a cross-sectional view so as not to make the drawing excessively complex.

In the description below, the constituent elements having practically the same functions are denoted by common reference numerals for which explanation might be omitted. In the description below, terms indicating specific directions or positions (e.g., “upper,” “lower,” “right,” “left” and other terms including or related to these) might be used. These terms, however, are merely used in order to make the relative directions or positions in the drawings being referenced more easily understood. As long as the relationship between relative directions or positions indicated with the terms such as “upper,” “lower,” or the like is the same as those in a referenced drawing, the layout of the elements in other drawings, or actual products and manufacturing equipment outside of the present disclosure, does not have to be the same as those shown in the referenced drawing. In the present disclosure, being “parallel” includes cases where two straight lines, sides, planes, or the like, form an angle in the range of 0° to about ±5° unless otherwise specifically stated.

In the present disclosure, being “perpendicular” or “orthogonal” includes cases where two straight lines, sides, planes, or the like form an angle in the range of from 90° to about ±5° unless otherwise specifically stated. Furthermore, the positional relationships of constituent elements expressed with the term “upper” include cases in which a constituent element is in contact with another, as well as cases in which a constituent element is positioned above another without being in contact.

The drawings referenced below include arrows indicating the x, y, and z axes that are orthogonal to one another. The x direction along the x axis represents a predetermined direction in the plane where the light emission units of the light source according to each embodiment are arranged, i.e., the light emission unit arrangement plane, the direction along the y axis is the direction orthogonal to the x direction in the light emission unit arrangement plane, and the z direction along the z axis is the direction orthogonal to the arrangement plane. The x direction pointed by the arrow represents the +x direction, and the direction opposite the +x direction represents the −x direction. The y direction pointed by the arrow represents the +y direction, and the direction opposite the +y direction represents the −y direction. The z direction pointed by the arrow represents the +z direction, and the direction opposite the +z direction represents the −z direction. In each embodiment, the light source, as an example, outputs light in the +z direction. This, however, is not intended to restrict the orientation of the light source or the light source device in use, and the light source and the light source device can be oriented in any way.

First Embodiment

Structure of Light Source101

FIG.1is a schematic perspective view of a light source101according to a first embodiment,FIG.2Ais a schematic top view of the light source101, andFIG.2Bis a schematic cross-sectional view of the light source101taken along line2B-2B inFIG.2A. The light source101includes a plurality of light emission units51and a light shielding member60.

The light emission units51are one- or two-dimensionally arranged. As used herein, the light emission units51are one-dimensionally arranged when all the light emission units51are aligned along a single row or column, while the light emission units51are two-dimensionally arranged when the light emission units51are arranged in rows and columns. For example, as shown inFIG.2, the light emission units51are two-dimensionally arranged in the x direction and the y direction. In this embodiment, the light source101includes 63 light emission units51arranged in the x and y directions, 7 rows by 9 columns. The number of light emission units51to be included in the light source101is optional, and can be any other number, for example, about 9 to about 400 units arranged 3 rows by 3 columns to 20 rows by 20 columns.

A light emission unit51has, for example, a square or rectangular shape in a top view, i.e., in the x-y plane, each side being 100 μm to 500 μm, preferably 200 μm to 400 μm. The light source101has, for example, a square or rectangular shape in the x-y plane, each side being 1 mm to 5 mm, preferably 2 mm to 3 mm. The light source101is about 100 μm to about 1 mm in thickness, for example. The size and the number of light emission units51, and the size of the light source101can be determined in accordance with the application. For example, the light source101can be used as a photographic flash or video lighting of portable devices such as a smartphone or the like.

FIG.2Cis a schematic cross-sectional view of a light emission unit51.FIG.2Dis a schematic top view of the light emission unit51. Each light emission unit51includes a light emitting element20having a light emission face20a, a wavelength conversion member30disposed on the light emission face20a, and a light transmissive member40disposed on the upper face30aof the wavelength conversion member30. In this embodiment, the light emission faces20aof the light emitting elements20are equal in size. A light shielding member60is provided continuously between the light emission units51to cover the lateral faces20cof the light emitting elements20and the lateral faces30cof the wavelength conversion members30. At least a part of the lateral faces of the light transmissive member of each light emission unit is exposed from the light shielding member60. The structure of a light emission unit51will be explained in more detail element by element.

Light Emitting Element20

A light emitting element20has a light emission face20a, an electrode face20band lateral faces20c. On the electrode face20b, positive and negative electrodes21are positioned.

The light emitting element20is a semiconductor light emitting element, such as a laser diode (LD), light emitting diode (LED), or the like. The light emitting element20is typically a LED. The light emitting element20includes, for example, a sapphire or gallium nitride support substrate, and a semiconductor stacked body on the support substrate. The semiconductor stacked body includes an n-type semiconductor layer, a p-type semiconductor layer, an active layer interposed between these two layers, and p-side and n-side electrodes electrically connected to the n-type and p-type semiconductor layers. The semiconductor stacked body may include a nitride semiconductor (InxAlyGa1-x-yN, 0≤x, 0≤y, x+y≤1) capable of emitting light in the ultraviolet to visible spectra. The positive and negative electrodes21are electrically connected to the p-side and the n-side electrodes.

The light emitting element20may be a blue light emitting element, or a light emitting element emitting light of another color, such as red, green, or ultraviolet. In this embodiment, a blue light emitting LED is illustrated as the light emitting element20in each light emission unit51.

The shape of the upper face, the light emission face20a, of a light emitting element20is typically quadrangular. The length of a side of the quadrangular light emission face20ais preferably smaller than the length of the corresponding side of the light emission unit51in a top view. For example, the length of a side of the quadrangular light emitting element20is 50 μm to 300 μm.

Wavelength Conversion Member30

A wavelength conversion member30is disposed on the light emission face20aof each light emitting element20. The wavelength conversion member30absorbs a portion of the light exiting the light emission face20aof the light emitting element20and emits light having a longer wavelength than that of the absorbed light.

In a top view, the wavelength conversion member30is preferably larger than the light emission face20aof the light emitting element20. This allows a larger area than the light emission face20aof the light emitting element20to output wavelength-converted light (e.g., white light). This can reduce the generation of low luminance regions between the light emission units51when multiple light emission units51are lit, even in the case in which the light emitting elements20cannot be arranged at sufficiently small intervals in the light source101.

Each wavelength conversion member30includes, for example, a light transmissive resin and a phosphor. For the phosphor, for example, yttrium aluminum garnet based phosphors (e.g., Y3(Al,Ga)5O12:Ce), lutetium aluminum garnet based phosphors (e.g., Lu3(Al,Ga)5O12:Ce), terbium aluminum garnet based phosphors (e.g., Tb3(Al,Ga)5O12:Ce), β-SiAlON phosphors (e.g., Si,Al)3(ON)4:Eu), α-SiAlON phosphors (e.g., Mz(Si,Al)12(O,N)16(0<z≤2, and M is Li, Mg, Ca, Y, and lanthanide elements excluding La and Ce), nitride based phosphors, such as CASN-based phosphors (e.g., CaAlSiN3:Eu) or SCASN based phosphors (e.g., (Sr,Ca)AlSiN3:Eu), fluoride based phosphors, such as KSF based phosphors (e.g., K2SiF6:Mn) or MGF based phosphors (e.g., 3.5MgO·0.5MgF2·GeO2:Mn), perovskite, chalcopyrite, or quantum dot phosphors can be used.

For the light transmissive resin, a silicone resin, modified silicone resin, epoxy resin, modified epoxy resin, acrylic resin, or fluorine resin can be used. A blend of these resins may alternatively be used.

The wavelength conversion member30may include several types of phosphors, for example, a phosphor that absorbs blue light and emits yellow light and a phosphor that absorbs blue light and emits red light. This allows the light emission unit51to emit desired white light.

The wavelength conversion members30may contain a light diffusing material to the extent that it does not block light. The light diffusing material content in the wavelength conversion members30can be adjusted such that the transmittance of the wavelength conversion members30with respect to the light exiting the light emitting elements20and/or the wavelength-converted light is 50% to 99%, preferably 70% to 90%. For the light diffusing material, for example, titanium oxide, silicon oxide, aluminum oxide, zinc oxide, or glass can be used.

For the wavelength conversion members30, glass containing a phosphor may be used. Alternatively, the wavelength conversion members may be a sintered body composed only of a phosphor, or a sintered body which includes a phosphor and any of the light diffusing materials described above.

Light Transmissive Member40

A light transmissive member40is provided on the upper face30aof each wavelength conversion member30, covering the upper face30a. The light transmissive member40constitutes the light emission face of a light emission unit51. The light transmissive member40can reduce the luminance nonuniformity of the light exiting the wavelength conversion member30.

Each light transmissive member40has an upper face40aand a lower face located opposite to the upper face40a. The light transmissive member40, when the upper face40ais viewed from above, has a first region R1positioned above a light emitting element20, and a second region R2positioned outward from the first region R1. In this embodiment, the area of the first region R1is larger than the area of the light emission face20aof the light emitting element20, but the area of the first region R1may be the same as the area of the light emission face20a. InFIG.2D, for the sake of clarity, no hatching is applied to the first region R1, but the same hatching patterns as those inFIG.2Care applied to the second region R2and the light shielding member60. As shown inFIG.2D, the second region R2surrounds the first region R1.

In each light transmissive member40, the first region R1is larger in thickness than the second region. In other words, the thickness t2of the second region R2is smaller than the thickness t1of the first region R1. In this embodiment, a recessed portion40r(i.e., second groove162described later) is created in the peripheral portion of each light transmissive member40in the upper face of the light source101, whereby a second region R2is formed in each light transmissive member40. The creation of a recessed portion40rmakes the area of the upper face40asmaller than the lower face40b.

Each light transmissive member40has lateral faces positioned between the upper face40aand the lower face40b. The lateral faces each have a first lateral face40c1and a second lateral face40c2in the height direction of the light transmissive member40. The first lateral face40c1and the second lateral face40c2are defined by the recessed portion40r. Each light transmissive member40may have an intermediary face40dbetween the first lateral face40c1and the second lateral face40c2which is substantially parallel to the upper face40aand the lower face40b.

The first lateral face40c1is the lateral face of the recessed portion40r, and is contiguous with the upper face40a. The second lateral face40c2is contiguous with the lower face40b. The intermediary face40dis the bottom face of the recessed portion40r. As described later, the first lateral face40c1is exposed from the light shielding member60, but the second lateral faces40c2are covered by the light shielding member60. In other words, each light transmissive member40is constructed such that the recessed portion40rcreated exposes at least some portions of the lateral faces from the light shielding member60.

The light transmissive members40can be constructed by using a similar resin to the light transmissive resin used for the wavelength conversion members30. The light transmissive members40can be formed of glass or a ceramic having light transmissivity.

The light transmissive members40preferably contain a light diffusing material. For the light diffusing material, the same or a similar material to the light diffusing material that can be added to the wavelength conversion members30can be used.

Light Shielding Member60

A light shielding member60is continuously disposed between the light emission units51while covering the lateral faces20cof the light emitting elements20and the lateral faces30cof the wavelength conversion members30in each light emission unit51. The light shielding member60has light shielding properties or light reflectivity. By covering at least these lateral faces, the light shielding member60can hinder the light exiting the lateral faces20cof the light emitting element20and the lateral faces30cof the wavelength conversion member30in each light emission unit51from entering any adjacent light emission unit51.

In this embodiment, the light shielding member60extends from the lateral faces of the light emitting elements20to cover the electrode faces20bof the light emitting elements20. However, the surfaces of the electrodes21on the electrode faces20bare exposed from the light shielding member60. Because the wavelength conversion members30are larger than the light emission faces20aof the light emitting elements20, the areas of the lower faces30bnot in contact with the light emission faces20aare covered by the light shielding member60. The light shielding member60also covers the second lateral faces40c2of the light transmissive members40.

The reflectance of the light shielding member60is preferably 20% to 95%, for example, more preferably 50% to 95%. The light shielding member60, for example, includes a light diffusing material and a resin material. For the resin material and the light diffusing material, a light transmissive resin and a light diffusing material similar to those used for the wavelength conversion members30can be used. The light shielding member may contain a light absorbing material such as carbon black in addition to the light diffusing material.

Operation of Light Source101

In a light source101, the light exiting the light emission faces20aof the light emitting elements20passes through the wavelength conversion members30and the light transmissive members40before exiting the light source. At this time, the wavelength of at least a portion of the light from the light emitting elements20is converted by the wavelength conversion members30. The light externally output includes the light which has exited the light emitting elements20and the wavelength-converted light. For example, in the case in which the light emitting elements20emit blue light and the wavelength conversion members30contain at least a yellow-emitting phosphor, the light source101emits white light resulting from mixing the blue light and the yellow light.

The light source101structured as above has good emission characteristics during partial irradiation. Specifically, because the wavelength conversion members30are larger than the light emission faces20aof the light emitting elements20in a top view, the light source can output white light through larger areas than the light emission faces20aof the light emitting elements20. This can reduce the generation of low luminance regions between the light emission units51when multiple light emission units51are lit, even in the case in which the light emitting elements20cannot be arranged at sufficiently small intervals.

Furthermore, the distance between the wavelength conversion members30in two adjacent light emission units51is smaller than the distance between the corresponding light emitting elements20. In the light source101, a light shielding member60is disposed between the facing lateral faces of the light emitting elements20and the facing lateral faces30cof the wavelength conversion members30of adjacent light emission units51. This can hinder the light from the light emitting element20in each light emission unit51from entering the wavelength conversion members30of any adjacent light emission unit51, as well as reducing the propagation of light between adjacent wavelength conversion members30. This can reduce the leakage of light along the boundary between a lit light emission unit51and an unlit light emission unit51.

Each light transmissive member40includes a first region R1positioned above the light emitting element20and a second region R2located on the outside of the first region R1. In each light transmissive member40, as compared to the first region R1located immediately above the light emitting element20in which the luminance is relatively high, a smaller thickness is given to the second region R2located in the periphery of the first region R1and having low luminance. Accordingly, allowing the light transmissive members40to contain a light diffusing material can reduce the absorption and diffusion of light by the second region R2as compared to the first region R1of each light transmissive member40, thereby enhancing the luminance uniformity of the light exiting the light transmissive members40.

The light transmissive members40have the first lateral faces40c1that are not covered by the light shielding member60. In other words, between two adjacent light emission units51in the light source101, the first lateral faces40c1of the light transmissive members40face one another without interposing a light shielding member60. This allows the light to laterally exit the first lateral faces40c1of the light transmissive members40, thereby lessening the luminance decline along the boundary between two adjacent light emission units51. This can reduce the generation of a dark line between two adjacent light emission units51when both are lit.

Method of Manufacturing Light Source101

One embodiment of a method of manufacturing a light source101will be explained.FIG.3is a flowchart of an example of a method of manufacturing a light source101, andFIGS.4A to4Kare cross-sectional views each showing a process in the method of manufacturing a light source101shown inFIG.3. The method of manufacturing a light source101according to this embodiment includes at least, a light emitting element bonding step (S1), a first groove forming step (S2), a light shielding member disposing step (S3), and a second groove forming step (S4).

Light Emitting Element Bonding Step (S1)

As shown inFIG.4A, a light transmissive layer140which is a monolithic body of light transmissive members and a wavelength conversion layer130which is a monolithic body of wavelength conversion members are adhered by using an adhesive or an adhesive sheet to obtain a stacked body150. The light transmissive layer140and the wavelength conversion layer130may have the size that corresponds to a light source101, or a size for producing multiple light sources101. The light transmissive layer140of the stacked body150is temporality fixed to a support120.

As shown inFIG.4B, a plurality of light emitting elements20are bonded to the stacked body150. The light emitting elements120are arranged and bonded to the wavelength conversion layer130while allowing the light emission faces20aof the light emitting elements20to face the wavelength conversion layer130. By disposing an adhesive or adhesive sheet on the surface of the wavelength conversion layer130or the light emission faces20aof the light emitting elements20in advance, the light emitting elements20can be bonded to the wavelength conversion layer130via the adhesive material. The light emitting elements20are one- or two-dimensionally arranged using the pitch used for the light emission units51in the light source101.

The bonding between the light transmissive layer140and the wavelength conversion layer130, and between the wavelength conversion layer130and the light emitting elements20may be done directly without interposing any adhesive material by utilizing the tackiness of the light transmissive layer140and the wavelength conversion layer130.

First Groove Forming Step (S2)

As shown inFIG.4C, first grooves161which segmentize the stacked body150are formed between adjacent light emitting elements20. By applying a dicing saw blade or the like at the positions of the stacked body150indicated by the arrows inFIG.4B, the first grooves161as shown inFIG.4Chaving a width w1are formed in the stacked body150by cutting from the wavelength conversion layer130side. This provides each light emitting element20with a wavelength conversion member30and a light transmissive member40. The lateral faces30cof the wavelength conversion members30and the lateral faces40cof the light transmissive members40are exposed at the lateral faces defining the first grooves161.

In this process, the first grooves161do not have to completely segmentalize the stacked body150. It is sufficient for the first grooves to completely segmentalize at least the wavelength conversion layer130and reach the light transmissive layer140. The light transmissive layer140may be partially removed or not removed at all by the first grooves161.

Light Shielding Member Disposing Step (S3)

As shown inFIG.4D, a light shielding member60is disposed between the light emitting elements20. Specifically, the light shielding member60is disposed to cover the lateral faces30cof the wavelength conversion members30and the lateral faces40cof the light transmissive members40exposed at the lateral faces defining the first grooves161and the lateral faces20cof the light emitting elements20. In this embodiment, the light shielding member60is disposed to cover the electrode faces20band the electrodes21on the electrode face20bof the light emitting elements20. The light shielding member60can be formed, for example, by transfer molding, potting, printing, spraying, or the like.

As shown inFIG.4E, the surfaces of the electrodes21of the light emitting elements20are exposed by grinding or cutting off a portion of the light shielding member60from the upper face60b.

Second Groove Forming Step (S4)

As shown inFIG.4F, the support120is removed from the light transmissive members40to expose the upper faces40aof the light transmissive members40located opposite to the faces in contact with the wavelength conversion members30. As shown inFIG.4G, second grooves162that expose some portions of the lateral faces of the light transmissive members40from the light shielding member60are formed by removing from the upper face40aside the outer edge portions of the light shielding member60located between the light transmissive members40. The second grooves162can be formed by using a blade, such as a dicing saw.

In this embodiment, because the second grooves162each have a larger width w2than the width w1of the first grooves161, the outer edge portions of the light transmissive members40facing one another via the light shielding member60are also made absent by the second grooves162. The second grooves162which do not reach the wavelength conversion members30have a depth of about one half of the thickness of the light transmissive members40. In the case in which the stacked body150is not completely segmentalized by the first grooves161formed during the first groove forming step, the second grooves162are formed to the depth to reach the first grooves161.

The cross-sectional shape of a second groove162reflects the cross-sectional shape of the blade used to form the second groove162. In this embodiment, the tip of a blade having a rectangular cross-sectional shape as shown inFIG.5Aforms the first lateral faces40c1that are perpendicular to the upper faces40a. Forming the second grooves162provides the light transmissive members40with the first lateral faces40c1exposed from the light shielding member60and the second lateral faces40c2covered by the light shielding member60.

The light source101is completed in this manner. In the case in which the light transmissive layer140and the wavelength conversion layer130have the size that corresponds to multiple light sources101, the multiple light sources101are linked by the light shielding member60. Accordingly, the light sources101are completed after cutting the light shielding member60along the boundaries of the light sources101.

Other Forms

Various modifications can be made to the light source according to the present disclosure. As described above, the shape of the first lateral faces of the light transmissive member40of each light emission unit51can be changed by using a blade having a different tip in forming the second grooves162.

In the case of forming the second grooves162using a blade having a tip that has a U-shaped or curved line cross section as shown inFIG.5B, the first lateral faces40c1of a light transmissive member40each have a curved portion as shown inFIG.6A. The second lateral faces40c2, similar toFIG.2C, are planar because the second lateral faces40c2are formed by the first grooves161.

In the case of forming the second grooves162using a blade having a tip that has a trapezoidal cross section as shown inFIG.5C, the first lateral faces40c1of the light transmissive member40are oblique to the vertical direction as shown inFIG.6B.

As described above, the direction of the light exiting the first lateral faces40c1can be altered by changing the shape or the inclination of the first lateral faces40c1. This can adjust the distribution of the light laterally exiting the light emission units51.

FIGS.7A and7Bshow an example of a light source102having light transmissive members in another form. As shown inFIGS.7A and7B, the light source102differs from the light source101shown inFIGS.2A and2Bin that each light emission unit52has a light transmissive member that has no second lateral faces. In each light emission unit52of the light source102, the first lateral faces41c1of the light transmissive member42are contiguous with the upper face40aand the lower face40bwithout any second lateral face. In other words, the lateral faces of the light transmissive member42of each light emission unit52of the light source102are entirely exposed from the light shielding member60. The first lateral faces42c1each have a curved face portion. The light source102including the light transmissive members42with such a shape can be produced by forming second grooves162that reach the wavelength conversion members30by using a blade having the cross-sectional shape shown inFIG.5B. Similarly, a light source103including the light transmissive member43shown inFIG.7Ccan be produced by forming second grooves162that reach the wavelength conversion member30using a blade having the cross-sectional shape shown inFIG.5C. The light transmissive member43has planar first lateral faces43c1oblique to the vertical direction.

Second Embodiment

FIG.8Ais a schematic cross-sectional view of a light source104according to a second embodiment, andFIG.8Bis a schematic cross-sectional view of a light emission unit54. The light source104differs from the light source101of the first embodiment such that the area of the upper face44ais larger than the lower face44bof the light transmissive member44in each light emission unit54. Similar to the first embodiment, the thickness of the second region R2is smaller than the first region R1in the light transmissive member44. The first lateral faces44c1are exposed from the light shielding member60, and the second lateral faces44c2are covered by the light shielding member60. The light source104exhibits a similar effect to that achieved by the first embodiment.

The light source104can be manufactured by modifying the steps of forming the first grooves161and the second groves162in the method of manufacturing a light source according to the first embodiment. Specifically, as shown inFIG.9A, first grooves171that reach the light transmissive layer140are formed by segmentalizing the wavelength conversion layer130between the light emitting elements20from the wavelength conversion layer130side. The width w1of the first grooves171is set larger than the width w1of the first grooves161of the first embodiment. The first grooves171are formed so as not to reach the support120. In other words, the light transmissive layer140is not segmentalized by the first grooves171. Forming the first grooves171segmentalizes the wavelength conversion layer130, providing each light emission unit54with a wavelength conversion member30. A light shielding member60is disposed in the first grooves171.

Then second grooves that reach the light shielding member60are formed by partially removing the light transmissive layer140located between the light emitting elements from the light transmissive layer140side. This provides light transmissive members40respectively positioned on the wavelength conversion members30. When forming the second grooves172, as shown inFIG.9B, the width w2of the second grooves172is preferably set smaller than the width w1of the first grooves171. In this embodiment, the depth of the second grooves172is set to cut the light transmissive layer140and reach the first grooves171. By forming the second grooves172, the light transmissive layer140is segmentalized to form light transmissive members44respectively corresponding to the light emission units54.

Other Forms

Similar to the first embodiment, by changing the shape of the blade used when forming the first grooves171, the shape of the second lateral faces of the light transmissive member44in each light emission unit54can be changed.

In the case of forming the first grooves171by using a blade having a curved edge in a cross section shown inFIG.5B, the second lateral faces40c2of the light transmissive member44each include a curved face portion as shown inFIG.10A.

In the case of forming the first grooves171by using a blade having a trapezoidal cross section shown inFIG.5C, the second lateral faces40c2of the light transmissive member44are oblique to the vertical direction as shown inFIG.10B.

Forming the first grooves171by using a blade having the same shape as that of the blade for forming the second grooves172and making the width w1of the first grooves171the same as the width of the second grooves172can produce a light source105which includes light emission units55each equipped with the light transmissive member45in the form shown inFIG.10C. The light source105differs from the light source101of the first embodiment such that the area of the upper face45aand the area of the lower face45bof the light transmissive member45are equal in each light emission unit55. Each light transmissive member45has lateral faces45ccontiguous with the upper face45aand the lower face45bin which a portion of each lateral face45con the upper face45aside is exposed from the light shielding member60and the other portion on the lower face45bside is covered by the light shielding member60.

Third Embodiment

FIG.11is a schematic top view of a light source106according to a third embodiment. The light source106differs from the light source101of the first embodiment such that the light emission faces of the light emitting elements in the light emission units do not have the same size.

The light source106includes a plurality of two-dimensionally arranged light emission units56. The light emission units56include a plurality of first light emission units56A, a plurality of second light emission units56B, a plurality of third light emission units56C, and a plurality of fourth light emission units56D.

As indicated by various hatching patterns inFIG.11, the light emission faces20aof the light emitting elements in the first light emission units56A, the second light emission units56B, the third light emission units56C, and the fourth light emission units56D are different. Assuming that the areas of the light emission faces20afor the first light emission units56A, the second light emission units56B, the third light emission units56C, and the fourth light emission units56D are Aa, Ab, Ac, Ad, respectively, they satisfy the relationship, Aa<Ab<Ac<Ad.

The distances from the center C of the light emission face of the light source106in which the light emission units56are arranged (i.e., the upper face of the light source106) to the centers of the first light emission units56A, the second light emission units56B, the third light emission units56C, and the fourth light emission units56D in a top view are assumed to be ra, rb, rc, and rd, respectively. These distances for any two light emission units56selected in which the light emission faces20ahave different areas satisfy the relationship, ra<rb<rc<rd. In other words, the larger the light emission face20aof the light emitting element20of the light emission unit, the more distant it is from the center C.

Accordingly, the second light emission units56B are more distant from the center C than the first light emission units56A (ra<rb), and the areas of the light emission faces20aof the light emitting elements20of the second light emission units56B are larger than the areas of the light emission faces20aof the light emitting elements20of the first light emission units56A. The first light emission units56A similarly satisfy the relationship with the third light emission units56C and the fourth light emission units56D. The second light emission units56B also similarly satisfy the relationship with the third light emission units56C and the fourth light emission units56D. The third light emission units56C also similarly satisfy the relationship with the fourth light emission units56D.

The light source106structured as above has higher luminance in the peripheral area than the central area of the light emission face101awhen all light emission units56are lit. Such light emission characteristics can achieve more appropriate lighting when used in combination with a projection lens in a lighting device. The details will be explained in relation to a fourth embodiment.

Fourth Embodiment

An embodiment of a light source device will be explained.FIG.12Ais a schematic front view of a light source device201, andFIG.12Bis a schematic cross-sectional view of the light source device201taken along line12B-12B inFIG.12A.

The light source device201includes a lens202and a light source203. In this embodiment, the light source device201further includes a substrate205and a support204. For the light source203, a light source according to any of the embodiments described above can be used. For example, the light source203is the light source106of the third embodiment. The light source203is disposed on the substrate205. The substrate205provided with a drive circuit that can independently drive the light emission units56of the light source203is electrically connected to each of the light emitting elements20in the light emission units57.

The support204retains the lens202at a predetermined distance from the light emission face203aof the light source203. The lens202, for example, is a convex lens, and the optical axis of the lens202is aligned with the center of the light emission face203a.

The lens202is a projection optical system and expansively projects the light from the light source203. When the light emission units57are partially driven, the light having the intensity and the irradiation range corresponding to the light intensity or blinking resulting from the partial driving is projected through the lens202.

The projected light has good emission characteristics during partial irradiation, as explained with reference to the first embodiment. Because the light exiting the light source203is expansively projected by the lens202, similar to an imaging optical system, the amount of light decreases in the peripheral area. However, as explained with reference to the third embodiment, such a light amount decline is lessened because the peripheral portion of the light emission face203ahas higher luminance than the central area. Accordingly, uniform light without illuminance nonuniformity can illuminate an object.

Test Example

The luminance distribution of the light exiting a light source according to an embodiment was measured by simulation. The luminance of the light source having light emission units51arranged in four rows by four columns shown inFIG.2Cas a test example was measured by simulation.FIG.13Ashows the luminance distribution of the light source of the test example. As a comparative example, the luminance of a light source similar to the test example except that the light transmissive member has no lateral faces exposed from the light shielding member was measured by simulation.FIG.13Bshows the luminance distribution of the light source of the comparative example. In the light emission units51of the test example, the thickness t1of each first region R1(FIG.2C) was 60 μm, the thickness t2of each second region R2was 30 μm. The light emission units of the comparative example had no first regions R1, and the thickness of each light transmissive member was 30 μm. The distance between the lateral faces of the light transmissive members and between the lateral faces of the wavelength conversion members facing via the light shielding member was 25 μm in both the test and comparative examples.FIG.13AandFIG.13Beach show the luminance distribution when the four light emission units in the center were not lit, i.e., the 12 light emission units in the peripheral area were lit. InFIGS.13A and13B, the whiter the area, the higher the luminance is.

As is understood fromFIGS.13A and13B, in the test example, there is hardly any region with reduced luminance between the lit light emission units in the peripheral area, whereas in the comparative example, there are low luminance regions between the light emission units. In the test example, the contrast between the lit area and the unlit area is high, whereas in the comparative example, the contrast between the lit and unlit areas is low. This shows that the light source of this example has good emission characteristics during partial irradiation.

Any of the light sources and light source devices according to the present invention can be used as a light emitting device in various applications. For example, it can be suitably used as a light emitting device for various lighting applications.