This application claims the priority benefit under 35 U.S.C. §119 to Japanese Patent Application No. JP2014-236277 filed on Nov. 21, 2014, which disclosure is hereby incorporated in its entirety by reference.
Field
The presently disclosed subject matter relates to a semiconductor light-emitting device having multiple light-emitting elements such as light-emitting diode (LED) elements arranged in a matrix.
Description of the Related Art
Generally, a semiconductor light-emitting device formed by LED elements arranged in a matrix including rows and columns has been used as a vehicle headlamp. In such a semiconductor light-emitting device, luminous intensities of the LED elements are individually controlled in real time to realize an adaptive drive beam (ADB) and an adaptive front-lighting system (AFS) (see: JP2013-54849A & JP2013-54956A).
In an ADB control, when a preceding vehicle including an oncoming vehicle is detected by a radar unit or the like, the luminous intensities of only the LED elements facing toward the preceding vehicle are decreased to decrease the illuminance toward the preceding vehicle while a high-beam mode is maintained. As a result, glare toward the preceding vehicle can be suppressed while the visibility in a high-beam mode can be maintained toward the preceding vehicle.
In an AFS control, when a steering angle read from a steering angle sensor or the like is larger than a predetermined value, the LED elements having high luminous intensities are shifted from a central area of the device to a right side or a left side of the device, to substantially decline the optical axis of the device while the visibility in a high-beam mode is maintained.
Note that each of the LED elements D11, D12, . . . , and D33 is square or rectangular viewed from the top, so that the LED elements D11, D12, . . . , and D33 can be in close proximity to each other.
In the first prior art semiconductor light-emitting device of
On the other hand, when the LED elements D11, D12, . . . , D33 are closer to each other as illustrated in
Thus, in the first prior art semiconductor light-emitting device of
A second prior art semiconductor light-emitting device includes multiple light-emitting elements each with one wavelength-converting layer thereon on a support body, a grid-shaped optical shield wall for separating the multiple light-emitting elements from each other, multiple transparent plates each provided on one of the multiple light-emitting elements, and a grid-type optical shield frame for separating the transparent plates from each other (see: JP2013-187371A). Thus, both of the dark regions and the optical crosstalk can be decreased by the grid-shaped optical shield frame.
In the above-described second prior art semiconductor light-emitting device, however, since the thickness of the walls of the grid-type optical shield frame is actually very large, i.e., several tens of μ m, the dark regions are still very large. Also, the presence of the grid-shaped optical shield frame would increase the manufacturing cost.
A third prior art semiconductor light-emitting device includes multiple light-emitting elements on a support body, a grid-shaped optical shield frame having throughholes corresponding to the light-emitting elements on the support body, and multiple wavelength-converting filter plates each provided in one of the throughholes over one of the light-emitting elements (see: JP2009-134965A). Thus, both of the dark regions and the optical crosstalk can be decreased by the grid-shaped optical shield frame.
In the above-described third prior art semiconductor light-emitting device, however, since the thickness of the walls of the grid-shaped shield frame is actually very large, the dark portions are still very large. Also, the presence of the grid-shaped optical shield frame would increase the manufacturing cost.
The presently disclosed subject matter seeks to solve one or more of the above-described problems.
According to the presently disclosed subject matter, a semiconductor light-emitting device includes a support body, multiple light-emitting elements arranged in a matrix on the support body, a transparent resin layer provided on the light-emitting elements, multiple transparent plates provided on the transparent resin layer, each of the transparent plates being provided over one of the multiple light-emitting elements, and multiple optical shield layers each provided at one of a first side face of a first one of the transparent plates and a second the face of a second one of the transparent plates opposing the first the face of the first transparent plate.
Thus, according to the presently disclosed subject matter, due to the thin optical shield layers, the dark regions between the light-emitting elements can be remarkably decreased or suppressed, while optical crosstalk between the light-emitting elements is hardly generated regardless of the distance between the light-emitting elements.
The above and other advantages and features of the presently disclosed subject matter will be more apparent from the following description of certain embodiments, as compared with the prior art, taken in conjunction with the accompanying drawings, wherein:
In
The transparent plates 411, 412, . . . , and 433 can be individually designed and manufactured to improve the manufacturing yield. That is, each of transparent plates 411, 412, . . . , and 433 is determined to be successful or defective. As a result, only the transparent plates determined to be defective would be scrapped. Contrary to this, the transparent plate 4 of
Each of the transparent plates 411, 412, . . . , and 433 is located over the LED elements D11, D12, . . . , and D33, respectively. The transparent plates 411, 412, . . . , and 433 are a little larger than the LED elements D11, D12, . . . , and D33 viewed from the top. The shape of the transparent plates 411, 412, . . . , and 433 depends upon that of the LED elements D11, D12, . . . , and D33. That is, if the LED elements D11, D12, . . . , and D33 are square viewed from the top, the transparent plates 411, 412, . . . , and 433 are square viewed from the top. Also, if the LED elements D11, D12, . . . , and D33 are rectangular view from the top, the transparent plates 411, 412, . . . , and 433 are rectangular viewed from the top.
Also, one optical shield layer OS is formed on one of a side face of one transparent plate and a side face of its adjacent transparent plate opposing the side face of the one transparent plate. For example, as illustrated in
The optical shield layer OS is made of metal such as Ag, Pt, Al, Rh, Ti or carbon black for shielding the transparent plates from visible light of their adjacent LED elements. In this case, the metal is reflective rather absorptive, and carbon black is absorptive rather reflective. That is, the optical shield layer OS is reflective and/or absorptive; however, the optical shield layer OS is not completely reflective or not completely absorptive. As a result, the light emitting regions ER11, ER12, . . . , and ER33 are partitioned by the optical shield layers OS, not by the transparent plates 411, 412, . . . and 433.
Note that reflective materials rather than absorptive materials are preferable for the optical shield layer OS, in order to exhibit a high light extraction efficiency and avoid the generation of heat.
If the optical shield layers OS are completely reflective, since lights that arrive from the LED element D21 to the optical shield layers OS are totally reflected by the optical shield layers OS, these lights would be emitted from the light emitting region ER21. Also, since lights that arrive from the LED element D22 to the optical shield layers OS are totally reflected by the optical shield layer OS, these lights would be emitted from the light emitting regions ER22. Therefore, the dark region DR between the LED element D21 and D22 determined by the optical shield layers OS is decreased, so that the light emitting regions ER21 and ER22 of the LED elements D21 and D22 are increased. Also, the optical crosstalk between the light emitting regions ER21 and ER22 can be suppressed regardless of the distance between the LED elements D21 and D22.
On the other hand, if the optical shield layers OS are completely absorptive, lights that arrive from the LED element D21 to the optical shield layers OS are completely absorbed by the optical shield layers OS, and also, lights that arrive from the LED element D22 to the optical shield layers OS are completely absorbed by the optical shield layers OS. Therefore, although the dark region DR between the LED elements D21 and D22 is not decreased, so that the light emitting regions ER21 and ER22 of the LED elements D21 and D22 are not increased, optical crosstalk between the light emitting regions ER21 and ER22 is hardly generated.
Also, in order to increase the light emitting regions ER21 and ER22, the LED elements D21 and D22 can be closer to each other. In this case, the dark region DR between the LED elements D21,and D22 determined by the spacing therebetween can be decreased or suppressed to increase the light emitting regions ER21 and ER22, while optical crosstalk between the light emitting regions ER21 and ER22 is hardly generated. However, the light emitting regions ER21 and ER22 are partitioned by the transparent plates 421 and 422, particularly, their optical shield layers OS, not by the LED elements D21 and D22. In this case, the thickness of the optical shield layers OS is very thin as will be explained later. Therefore, the spacing between the transparent plates 421 and 422 can be easily reduced to increase the light emitting regions ER21 and ER22, thus making the entire extracted light uniform.
Further, in
Thus, in the semiconductor light-emitting device of
In
hc>hd
Also, the cross section of the cavities CV is convex or fan-shaped to surround all the sides of the LED elements D11, D12, . . . , and D33. Therefore, each of the cavities CV serves as an optical shield. As a result, lights that arrive from the LED elements D11, D12, . . . , and D33 to the cavities CV are reflected and/or absorbed by the cavities CV, so that the optical crosstalk between the light emitting regions ER21 and ER22 can further be suppressed regardless of the distance between the LED elements D21 and D22.
Since lights from the LED elements D21 and D22 are leaked through the wavelength-converting layer 3 between the cavities CV and the optical shield layers OS to increase the crosstalk, the height he of the cavities CV is preferably close to the height 11, of the lower surface of the transparent plates 411, 412, . . . , and 433. That is, the smaller the difference between the height hc and the height h, the smaller the crosstalk between the LED elements D11, D12, . . . , and D33. Particularly, when hc≧ht, so that the cavities CV are immediately adjacent to the optical shield layers OS, the crosstalk between the LED elements D11, D12, . . . , and D33 can completely be suppressed.
The wavelength-converting layer 3 is present uniformly between the LED elements D11, D12, . . . , and D33 and the transparent plates 411, 412, . . . , and 433. Additionally, as indicated by FL in
A method for manufacturing the semiconductor light-emitting device of
First, referring to
Next, a reflective layer 14 and a cap layer 15 are formed on the p-type AlInGaN layer 13 by a sputtering process or the like, and are patterned by a photolithography/etching process. The reflective layer 14 is made of metal such as Ag, Pt, Ni, Al, Pd or their alloy having good ohmic contact characteristics with the p-type AlInGaN layer 13, and the cap layer 15 is made of refractory metal such as Ti, Pd, Mo, Ru or Ir or noble metal such as Pt or Au. The cap layer 15 is hardly migrated to avoid the migration of the reflective layer 14. The reflective layer 14 and the cap layer 15 serve as a p-side electrode. Note that a metal oxide layer made of indium tin oxide (ITO) or indium zinc oxide (IZO) can be inserted between the p-type AlInGaN layer 13 and the reflective layer 14 to enhance the reflectivity.
Next, an etching adjustment layer 16 is formed by a sputtering process or the like, and is patterned by a photolithography/etching process. The etching adjustment layer 16 is made of insulating material such as silicon dioxide or silicon nitride to isolate the LED elements D21 and D22 from each other. The etching adjustment layer 16 serves as an etching stopper as well as a protecting layer for wiring layers of the support body 2.
Next, a contact hole CONT1 is perforated in the p-type AlInGaN layer 13 and the active AlInGaN layer 12 to reach the n-type AlInGaN layer 11.
Next, an insulating layer 17 is formed on the entire surface including the sidewall of the contact hole CONT1 by a CVD process or the like. Then, a photolithography/etching process is performed upon the insulating layer 17 to expose the bottom of the contact hole CONT1 and form a contact hole CONT2 in the insulating layer 17 opposing the cap layer 15. The insulating layer 17 is made of silicon dioxide or silicon nitride. In this case, the contact hole CONT1 reaches the n-type AlInGaN layer 11 before the formation of the insulating layer 17.
Next, an n-side electrode 18 is formed in the contact hole CONT1 by a sputtering process or the like and a photolithography/etching process. The n-side electrode 18 is made of metal such as Ti, Al, Pt or Au having good ohmic contact characteristics with the n-type AlInGaN layer 11.
Next, an adhesive layer 311 including Au on its upper surface portion is formed on the n-side electrode 18. The adhesive layer 311 is used for the bonding layer 31 of
On the other hand, referring to
Next, an insulating layer 23 made of silicon dioxide or the like is formed by a CVD process on the p-side wiring layers 22.
Next, an n-side wiring layer 24 is formed by a sputtering process or the like and a photolithography/etching process on the insulating layer 23.
Next, a contact hole CONT3 is perforated by a photolithography/etching process in the insulating layer 23 to reach the p-side wiring layers 22.
Next, a p-side electrode 25 is formed by a sputtering process and the like and a photolithography/etching process in the contact hole CONT3 of the insulating layer 23.
Next, an adhesive layer 312 including Au on its upper surface portion is formed on the n-side wiring layer 24. The adhesive layer 312 is used for the bonding layer 31 of
Next, referring to
Next, the growing sapphire substrate 10 is removed by a wet etching process or the like.
As occasion demands, a sand blast process is performed upon the n-type AlInGaN layer 11, so that the n-type AlInGaN layer 11 can have a protruded light extracting surface to suppress the total internal reflection component and the Fresnel component, thus improving the light extracting efficiency.
Next, referring to
The structure of
Next, referring to
Next, referring to
As occasion demands, a sand blast process is performed upon the transparent plates 411, 412, . . . , and 433 and the top surface of the wavelength-converting layer 3 to suppress the total internal reflection component and the Fresnel component, thus improving the light extracting efficiency.
Thus, the semiconductor light emitting device of
Finally, the support body 2 is mounted on a printed circuit board (not shown), and necessary wires are bonded between the semiconductor light-emitting device and the printed circuit board. As occasion demands, the entirety of the semiconductor light-emitting device is resin-molded (not shown).
The LED elements D11, D12, . . . , and D33 are provided at intersections between the p-side wiring layers 22 and the n-side wiring layers 24 which are isolated by the insulating layer 23. Therefore, the LED elements D11, D12, . . . , and D33 are operated individually in real time by supplying voltages to the p-side wiring layers 22 and the n-side wiring layer 24.
In
In
The flat top surface FLF of the wavelength-converting layer 3 can be realized by adding some wavelength-converting layer (paste) to the recess indicated by FL in
In
The method for manufacturing the semiconductor light-emitting device of
In
In the above-described embodiments, phosphor particles such as YAG particles are included in the wavelength-converting layer 3; however, such phosphor particles can be included in the transparent plates 411, 412, . . . , and 433. In this case, the wavelength-converting layer 3 is replaced by a transparent resin layer made of epoxy resin, silicone resin, urethane resin, or their hybrid resin without phosphor particles.
Also, in the above-described embodiments, the cavities CV or the optical shield resin members CVR completely occupy the regions between the LED elements D11, D12, . . . , and D33, i.e., there is no wavelength-converting layer in the regions between the LED elements D11, D12, . . . , and D33; however, parts of the wavelength-converting layer 3 can be formed in the regions between the LED elements D11, D12, . . . , and D33.
Further, the LED elements D11, D12, . . . , and D33 can be of a flip-chip type.
Furthermore, in the above-described embodiments, the LED elements are square or rectangular viewed from the top; however, the LED elements can be triangular or hexagonal viewed from the top, so that the LED elements can be in close proximity to each other.
It will be apparent to those skilled in the art that various modifications and variations can be made in the presently disclosed subject matter without departing from the spirit or scope of the presently disclosed subject matter. Thus, it is intended that the presently disclosed subject matter covers the modifications and variations of the presently disclosed subject matter provided they come within the scope of the appended claims and their equivalents. All related or prior art references described above and in the Background section of the present specification are hereby incorporated in their entirety by reference.
Number | Date | Country | Kind |
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2014-236277 | Nov 2014 | JP | national |
Number | Name | Date | Kind |
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20130329440 | Tsutsumi | Dec 2013 | A1 |
Number | Date | Country |
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2009-134965 | Jun 2009 | JP |
2013-54849 | Mar 2013 | JP |
2013-54956 | Mar 2013 | JP |
2013-187371 | Sep 2013 | JP |
Number | Date | Country | |
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20160148912 A1 | May 2016 | US |