JP2013149835A - Light source and light-emitting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light source capable of maintaining luminous efficiency while reducing color unevenness of light emitted by a light-emitting device.SOLUTION: A light-emitting device comprises: a substrate 11; a light source: and a lens arranged ahead of the light projection direction of the light source. The light source includes: an LED element 13 which is mounted on a light-emitting surface and has an upper face provided with a side along a first direction and a side along a second direction intersecting the first direction; a phosphor-containing layer which covers the upper face of the LED element; a tabular translucent member which is arranged over the substrate and has an upper face and a lower face provided with sides along the first direction and the second direction, and the lower face of which is entirely brought into contact with the phosphor-containing layer; and a reflection member which covers the lateral faces of the LED element, the phosphor-containing layer and the translucent member. The length difference between the side along the first direction of the upper face of the LED element and the sides along the first direction of the upper face and the lower face of the translucent member is smaller than the length difference between the side along the second direction of the upper face of the light-emitting element and the sides along the second direction of the upper face and the lower face of the translucent member.

Description

  The present invention relates to a light emitting device, and more particularly to a light emitting device using a light source on which an LED (Light Emitting Diode) element is mounted.

  In recent years, light emitting devices including light sources using LED elements instead of incandescent bulbs and fluorescent lamps have been used for lighting fixtures, vehicle lamps, and the like. When white light is generated by a light emitting device using an LED element, the LED element is covered with a phosphor-containing resin, and the emitted light from the LED element and the fluorescence from the phosphor excited by the emitted light are mixed. Therefore, a method of generating white light is often used. In particular, a lamp (for example, a headlight or a daytime running lamp) mounted on the front part of an automobile combines a light source and a lens to irradiate white light in a vertical direction with a narrow irradiation angle and a wide irradiation angle in a horizontal direction. In many cases, a light-emitting device that emits light with a horizontally long light distribution is used.

  For example, Patent Document 1 discloses a semiconductor light emitting device mounted on a base material and a semiconductor light emitting device as a light emitting device that generates mixed light of light emitted from an LED device and fluorescence from an excited phosphor. A wavelength converting member formed by mixing a phosphor that converts the wavelength of light emitted from a semiconductor light emitting element into a translucent resin, a transparent adhesive member provided on the wavelength converting member, and a transparent member A transparent plate disposed on the adhesive member and bonded and fixed to the wavelength conversion member via the transparent adhesive member, and a light-transmitting light filled around the semiconductor light emitting element, the wavelength conversion member, the transparent adhesive member, and the transparent plate A light-emitting device including a diffuse reflection member obtained by mixing light-scattering particles in a functional resin is shown.

  As a light emitting device that emits white light using a phosphor that emits yellow fluorescence when excited, Patent Document 2 discloses a base material, a light reflection layer formed on the base material, and light reflection. A silica glass film formed on the layer so as to cover the light reflecting layer, and a blue semiconductor light emitting element fixed to the silica glass layer with a silicone adhesive, wherein the semiconductor light emitting element is yellow fluorescent A light-emitting device sealed with a sealing resin containing a body is shown.

  Patent Document 3 discloses a light emitting device using a lens device in which a cylindrical lens or a toroidal lens and a prism are combined.

JP 2011-204376 A JP 2010-186852 A JP 2010-165484 A

  When a phosphor that emits yellow fluorescence as shown in Patent Document 2 is used in a light emitting device as shown in Patent Document 1, light that does not overlap with the upper surface of the semiconductor light emitting element when viewed from the light extraction surface The light emitted from the peripheral region of the light extraction surface has a relatively long optical path length in the wavelength conversion member of the light emitted from the LED element, and therefore is yellower than the light emitted from the central region of the light extraction surface. Becomes a strong light. When such a light source is used for a vehicular lamp, a white area WH exists in the center on the projection surface SCR illuminated by irradiation light emitted from the light source as shown in FIG. A frame-shaped yellow color uneven region Y (shaded portion in the figure) has occurred. The vehicular lamp must satisfy strict standards regarding the light intensity or chromaticity on the light irradiation surface of the lamp, and the occurrence of the color unevenness has been a problem.

  The present invention has been made in view of the above points, and an object of the present invention is to provide a light emitting device capable of reducing color unevenness on a light irradiation surface of a lamp while maintaining light extraction efficiency.

  A light-emitting device of the present invention includes a substrate, a light-emitting element that is mounted on the light-emitting surface and has an upper surface that has a side along the first direction and a side along the second direction intersecting the first direction. A phosphor-containing layer that covers the upper surface of the light-emitting element, an upper surface and a lower surface that are disposed above the substrate and have sides along the first direction and the second direction, and the entire lower surface contains the phosphor A light source having a plate-like translucent member in contact with the layer, a light emitting element, a phosphor-containing layer, and a reflective member covering the side surfaces of the translucent member, and a light source disposed in front of the light projecting direction A difference in length between the side along the first direction of the upper surface of the light emitting element and the side along the first direction of the upper surface and the lower surface of the light-transmitting member is 2 is smaller than the difference in length between the side along the direction 2 and the side along the second direction of the upper and lower surfaces of the translucent member. To.

  In the light emitting device of the present invention, the degree of freedom of light distribution by the lens is low, and in the direction in which it is difficult to reduce color unevenness by lens light distribution, the width of the upper surface of the light emitting element of the light source and the width of the light extraction surface In the direction where the difference is reduced to reduce yellow color unevenness and the degree of freedom of light distribution by the lens is high and it is easy to reduce color unevenness by lens light distribution, the width of the upper surface of the light emitting element of the light source and light extraction The structure is such that the difference in the width of the surface is increased to extract more light from the light emitting element. Thereby, it is possible to efficiently eliminate the uneven color of the irradiation light while maintaining the light extraction efficiency.

It is a projection image by the light emitting device of the conventional example It is a top view of the light source which concerns on Example 1 of this invention. It is sectional drawing of the light source which concerns on Example 1 of this invention. It is sectional drawing of the light source which concerns on Example 1 of this invention. It is a projection image by the light source which concerns on Example 1 of this invention. It is a perspective view of an example of the lens used for Example 1 of the present invention. It is sectional drawing of the light-emitting device using the light source of this invention. It is sectional drawing of the light-emitting device using the light source of this invention.

  Hereinafter, a light-emitting device 1 according to Example 1 of the present invention will be described with reference to FIGS. 2a to 2c, FIGS. 3, 4, and 5a and 5b. FIG. 2A is a plan view of the light source 1A according to the first embodiment of the present invention as viewed from the light emitting surface side. 2b is a cross-sectional view taken along line 2b-2b in FIG. 2a. 2c is a cross-sectional view taken along line 2c-2c in FIG. 2a. FIG. 3 is a projection image obtained by combining the light source 1A and a general lens that is rotationally symmetric with respect to the optical axis. 5a is a cross-sectional view showing the light-emitting device 1 in which the light source 1A and the lens 1B are combined along the line 2c-2c in FIG. 2a, and FIG. 5b shows the light-emitting device 1 in 2b-2b in FIG. 2a. It is sectional drawing shown by the cross section along a line. FIGS. 5a and 5b also show the trajectory of light until the light from the light source 1A reaches the projection surface SCR.

  The light source 1A includes a substrate 11, an LED element 13, a recess 15, a plate 19, a phosphor-containing layer 21, and a reflector layer 23 as shown in FIGS.

Substrate 11 is a substrate having e.g. AlN ceramics, or _Al 2 _{O 3} or the like ceramics, resin or a rectangular plan shape made of metal. The substrate 11 has a recess 15 formed integrally with the substrate by extrusion molding, injection molding, or the like at the center of the light emitting surface side surface (that is, the upper surface of the substrate 11) on which the LED element 13 is mounted. The recess 15 may be formed by overlapping a plurality of substrates with holes.

  The LED element 13 is provided in the center of the recess 15. The LED element 13 is, for example, a blue light emitting diode that has a square planar shape with a side of 800 μm and emits blue light (wavelength of about 430 nm to 470 nm). The LED element 13 is a flip chip type element having a P electrode and an N electrode on the lower surface, and each of the P electrode and the N electrode is provided on the surface of the substrate 11 via a conductive bump 17 such as Au. The electrode is electrically connected to an electrode (not shown).

  Above the LED element 13, a translucent plate 19 whose upper surface defines the light extraction surface of the light source 1 </ b> A is disposed away from the upper surface of the LED element 13 by a predetermined distance (for example, 50 μm). . The plate 19 is a thin plate member having a rectangular planar shape in which the side S along the first direction is 830 μm and the side L along the second direction intersecting (orthogonal to) the first direction is 1020 μm. The plate 19 may be made of a transparent resin such as an epoxy resin or a colorless and transparent material such as glass. The plate 19 is arranged such that the sides of the lower surface and the upper surface are along the same direction as the sides of the upper surface of the LED element 13, and the difference in length between the side L of the plate 19 and one side of the upper surface of the LED element 13. ΔL is larger than the difference ΔS between the side S of the plate 19 and the length of one side of the upper surface of the LED element. As shown in FIG. 2a, when viewed from the light extraction surface side, there is a peripheral region SR (shaded portion in the figure) where the LED element 13 and the plate 19 do not overlap. Hereinafter, the direction along the side S of the plate 19 is referred to as a first direction of the light source, and the direction along the side L of the plate 19 is referred to as a second direction of the light source.

  Around the LED element 13, a phosphor-containing layer 21 is formed from the peripheral edge of the lower surface of the LED element 13 to the lower surface of the plate 19. Accordingly, the phosphor-containing layer 21 has a substantially trapezoidal cross section perpendicular to the bottom surface along the first direction and the second direction, including the cross section of the LED element 13 (FIGS. 2b and 2c). The phosphor-containing layer 21 may be formed, for example, by potting a phosphor-containing resin on the LED element 13 and placing the plate 19 thereon to cure the resin.

The phosphor-containing layer 21 is made of a translucent material, for example, a silicone resin, an epoxy resin, a urethane resin, or a hybrid resin (epoxy resin + silicone resin). In the phosphor-containing layer 21, for example, a YAG: Ce phosphor in which Ce (cerium) is introduced as an activator in YAG (yttrium, aluminum, garnet: Y ₃ Al ₅ O ₁₂ ) is dispersed. The phosphor emits yellow light having an emission peak wavelength of about 560 nm, for example, by absorbing blue light emitted from the LED element 13 and having a wavelength of about 460 nm. Accordingly, white light is obtained by mixing the blue light emitted from the LED element 13 and not absorbed by the phosphor and the yellow light emitted from the phosphor.

  A reflective material 23 is formed around the LED element 13, the phosphor-containing layer 21, and the plate 19 by filling the concave portion 15 with a reflective material so as to cover these side surfaces. The reflector layer 23 is made of a non-conductive and highly reflective material, for example, a resin in which a reflective filler such as titanium oxide, alumina oxide, or zinc oxide is dispersed. The reflector layer 23 reflects light from the side surfaces of the LED element 13, the phosphor-containing layer 21, and the plate 19 to prevent the light from leaking sideways. Therefore, the light emitted from the LED element 13 is irradiated only from the light extraction surface on the upper surface of the plate 19.

  With the above configuration, the light source 1A is formed.

  In the light extraction surface, the light source 1A reduces the width difference ΔS between the upper surface of the LED element 13 and the light extraction surface (the upper surface of the plate 19) in the first direction so that a lot of yellowish light is emitted. The width of the region SR is reduced to suppress color unevenness, and the difference ΔL in the width between the upper surface of the LED element 13 and the light extraction surface (the upper surface of the plate 19) in the second direction is increased as in the conventional case, and the extraction efficiency is increased. Can be increased.

  When the light emitted from the light source 1A is irradiated onto the projection surface SCR using a convex lens that is rotationally symmetric with respect to the optical axis, a projection image as shown in FIG. 3 is obtained. As shown in FIG. 3, the projected image has an uneven yellow color region formed by the strong yellowish light emitted from the peripheral region SR of the light extraction surface of the light source 1 </ b> A around the central white region WH. Y (shaded area in the figure) exists. The uneven color region Y is very small in the first direction where the width of the peripheral region SR of the light source 1A is small, so that it is hardly recognized visually.

  In order to distribute the light emitted from the light source 1A in a laterally long distribution preferable for a daytime running light or a headlight of an automobile, a lens 1B is disposed in a space in front of the light projecting direction of the light source 1A. The lens 1B is a lens including a lens region that can be irradiated and projected so that light emitted from various regions of the light source 1A overlaps in at least one direction. For example, the lens 1B, when used with the light source 1A, forms a parallel light beam having a narrow irradiation angle in the first direction, and at the same time forms a non-parallel light beam having a wide irradiation angle in the second direction. A lens, for example, a lens having different refractive power in the first direction and different refractive power in the second direction (for example, different curvatures) may be used. Examples of such a lens include a cylindrical lens, a toric lens, and a toroidal lens.

  Further, a lens device 30 in which the lens and the prism are combined as shown in FIG. 4 can also be used. In this lens device 30, a central incident surface 31 that is convex toward the LED light source is formed at the central portion of the incident surface 32, and a polygonal radiation is emitted around the central incident surface 31 from the center toward the outer peripheral portion. This is a lens device in which a plurality of prisms 33 are formed in a shape. A toroidal surface as a central exit surface corresponding to the central entrance surface 31 is formed at the center of the exit surface of the lens device 30, and an ambient exit surface corresponding to the prism 33 is formed around the toroidal surface.

  By using the lens 1B as described above, the light emitting device 1 emits the strong yellowish light emitted from the peripheral region SR of the light source 1A and the other central region in the second direction of the light source 1A. In particular, it is possible to generate irradiation light with less color unevenness that is preferable for daytime running lights or headlights of automobiles.

  Here, with reference to FIG. 5a and 5b, the light-emitting device 1 using the toroidal lens whose curvature along a 1st direction is larger than a curvature along a 2nd direction is demonstrated as an example.

  In the light emitting device 1, the light source 1 </ b> A is disposed on a focal line perpendicular to the cross section along the first direction of the lens 1 </ b> B. In this case, the focal line perpendicular to the cross section along the second direction of the lens 1B exists farther from the light source 1A when viewed from the lens 1B. Therefore, the light source 1A and the lens 1B form an optical system that collimates each of the light emitted from each point on the light extraction surface of the light source 1A in the first direction into parallel rays, and in the second direction. Then, an optical system for diffusing the light irradiated from each point on the light extraction surface of the light source 1A without collimating is formed.

  Here, how the light emitted from the light emitting device 1 is irradiated onto the projection surface SCR will be described with reference to FIGS. In this description, the projection plane SCR is a plane on the virtual screen that is perpendicular to the optical axis ax and is at infinity. Further, the end portions of the light extraction surface along the first direction are A and B, respectively, and the end portions of the light extraction surface along the second direction are C and D, respectively. The points on the projection plane SCR, which are emitted from A, B, C and D and reach the light passing through both ends of the cross section of the lens 1B, are respectively A ′, A ″, B ′, B ″, C ′, Let C ″, D ′, D ″. For simplification of the drawing, the light beam is shown as being refracted by the virtual lens surface VP.

  First, refer to FIG. FIG. 5 a is a cross-sectional view of the light emitting device 1 along the first direction. In FIG. 4a, the light emitted from the end A of the light extraction surface of the light source 1A is indicated by a solid line, and the light emitted from the end B is indicated by a broken line. Since the light source 1A is on a focal line perpendicular to the cross section along the first direction of the lens 1B, the light emitted from the end portions A and B is collimated and passes through the lens 1B as shown in the figure. They are parallel to each other and reach between A ′ and A ″ and between B ′ and B ″ on the projection surface SCR at infinity. Since the light beams shown by the solid lines and the light beams shown by the broken lines are parallel, when these lights reach the projection plane SCR at infinity, the distance between A′A ″ and the distance between B′B ″ are At most, it is equal to or smaller than the width of the lens along the first direction, and A ′ and A ″ and B ′ and B ″ can be regarded as substantially the same point. Accordingly, in the first direction, the light emitted from each region of the light source 1A maintains the positional relationship on the light extraction surface of the light source 1A, and does not substantially overlap with each other as A ′ (≈A ″). The projection surface is irradiated so as to form one projection image of the light source 1A between B ′ (≈B ″).

  Reference is now made to FIG. FIG. 5 b is a cross-sectional view of the light emitting device 1 along the second direction. In FIG. 5b, the light emitted from the end C of the light extraction surface of the light source 1A is indicated by a solid line, and the light emitted from the end D is indicated by a broken line. Since the light source 1A is closer to the lens 1B than the focal line perpendicular to the cross section along the second direction of the lens 1B, the light emitted from the ends C and D is, as illustrated, the lens 1B. Even after passing through, the light travels in the direction of diffusion without being collimated and reaches the projection plane SCR. Since the light emitted from C and D and passed through the lens 1B is diffused to each other, the further away from the lens 1B, the farther away from each other, the distance between C ′ and C ″ on the projection surface SCR at infinity and It reaches between D ′ and D ″. Here, the projection image of the light source 1A is formed between D ′ and C ′ and between D ″ and C ″ by the light incident on the incident points at both ends of the lens 1B. In other words, the projection image of the light source 1A is formed between C ′ and D ′ by the light emitted from C ′ and D ′ and incident on the upper edge of the lens 1B, and below the lens 1B. A projected image of the light source 1A is formed between C ″ and D ″ by the light incident on the side ends. Further, in the region from the projected image formed between D ′ and C ′ to the projected image formed between D ″ and C ″, the light that has passed through the region between both ends of the lens 1B Thus, a plurality of projection images of the light source 1A are formed so as to overlap each other along the second direction. In this way, the light emitted from each region of the light source 1A spreads along the second direction, is largely overlapped with each other, and is mixed and irradiated onto the projection surface SCR.

  As described above, the light emitted from the light source 1A of the light emitting device 1 spreads along the second direction by the lens 1B and is distributed horizontally, and is emitted from various positions of the light source 1A along the second direction. The irradiated light is irradiated so as to be superimposed. Therefore, in the second direction, a desired laterally long light distribution is achieved, and at the same time, the intense yellowish light emitted from the peripheral region SR of the light source 1A and the white light emitted from the central region are mixed and irradiated. It is possible to reduce the color unevenness of the entire light. That is, in the second direction, even when intense yellowish light is emitted from the peripheral region SR of the light source 1A, by combining the lens 1B, it is possible to reduce the color unevenness of the entire irradiation light. Regarding the direction 2, it is possible to adopt a structure that can extract more light from the light emitting element, that is, a structure in which the difference between the width of the upper surface of the light emitting element and the width of the light extraction surface is relatively large.

  In the above description, the basic optical system of the light emitting device of the present invention has been described as a lens having a single focal point in the cross section along the second direction in order to simplify the description. It is not limited to. For example, in a cross section along the second direction, a shape in which a plurality of lenses having different focal lengths are combined may be used in order to control the light diffusion angle.

  In the above description, it has been described that the light source 1A is disposed on the focal line perpendicular to the cross section along the first direction, that is, on the focal point. However, in the light emitting device of the present invention, the virtual screen located at infinity. As long as the position is in the vicinity of the focal point that can be regarded as a substantially focal point with respect to the upper projection surface, it does not have to be placed on the exact focal point.

  In the example above. Although the LED element 13 is a flip chip type element, an element may be used in which an electrode is disposed on the upper surface of the element and power is supplied by wire bonding.

  In the above-described embodiment, the LED element 13 is square and the plate 19 is rectangular. However, in other cases, ΔL may be larger than ΔS. For example, the LED element 13 may be rectangular and the plate 19 may be square, or both the LED element 13 and the plate 19 may be rectangular. Further, ΔS may be 0.

  In the above-described embodiment, the phosphor-containing layer 21 is formed from the peripheral edge of the bottom surface of the LED element 13 to the lower surface of the plate 19, but such a configuration is not necessarily required. For example, the phosphor-containing layer 21 may be formed from the side surface of the LED element 13 to the side surface of the plate 19, or the phosphor-containing layer 21 may be formed from the upper surface of the LED element 13 to the side surface of the plate 19. Good.

  Further, in the above-described embodiment, the substrate 11 has a structure having the recess 15, but such a structure is not necessarily required. For example, by using a resin having a high viscosity as the resin for forming the reflector layer 23, the reflector layer 23 can be formed on the side surfaces of the LED element 13, the phosphor resin layer 21 and the plate 19 without filling the recess 15 with the resin. If it is possible to form a structure covering the surface, it is possible to adopt a structure without the recess 15.

  Various numerical values, dimensions, materials, and the like in the above-described embodiments are merely examples, and can be appropriately selected according to the use and the light-emitting element, the sealing resin, and the like used.

DESCRIPTION OF SYMBOLS 1 Light-emitting device 1A Light source 1B Lens 11 Board | substrate 13 LED element 15 Recessed part 17 Bump 19 Plate 21 Phosphor containing layer 23 Reflector layer 30 Lens apparatus 31 Center entrance plane 32 Entrance plane 33 Prism

Claims (5)

A substrate,
A light emitting element mounted on the light emitting surface and having an upper surface having a side along the first direction and a side along the second direction intersecting the first direction, and covers the upper surface of the light emitting element A phosphor-containing layer; and an upper surface and a lower surface that are disposed above the substrate and have sides along the first direction and the second direction, and the entire lower surface is the phosphor-containing layer. A light source having a plate-shaped translucent member in contact with the light-emitting element, the phosphor-containing layer, and a reflective member that covers a side surface of the translucent member;
A lens disposed in front of the light projecting direction of the light source,
The difference in length between the side along the first direction of the upper surface of the light emitting element and the side along the first direction of the upper and lower surfaces of the translucent member is the second of the upper surface of the light emitting element. A light emitting device characterized by being smaller than the difference in length between the side along the direction and the side along the second direction of the upper and lower surfaces of the translucent member.   2. The lens according to claim 1, wherein the lens has a lens region that is non-rotationally symmetric with respect to an optical axis, and the lens region does not collimate light that has arrived from the light source at least in the second direction. The light-emitting device of description.   3. The light emitting device according to claim 1, wherein the lens region has a curvature different from the first direction and a curvature along the second direction. 4.   4. The light emitting device according to claim 3, wherein the lens region has a curvature along the first direction larger than a curvature along the second direction. A substrate,
A light emitting element mounted on the light emitting surface and having a top surface having a side along a first direction and a side along a second direction intersecting the first direction;
A phosphor-containing layer covering an upper surface of the light emitting element;
A plate-like shape that is disposed above the substrate, has an upper surface and a lower surface that have sides along the first direction and the second direction, and the entire lower surface is in contact with the phosphor-containing layer. A translucent member;
A reflective member that covers a side surface of the light emitting element, the phosphor-containing layer, and the translucent member;
The difference in length between the side along the first direction of the upper surface of the light emitting element and the side along the first direction of the upper and lower surfaces of the translucent member is the second of the upper surface of the light emitting element. The light source is characterized by being smaller than the difference in length between the side along the direction and the side along the second direction of the upper and lower surfaces of the translucent member.

Images