JP2017204551A - Light-emitting device and illuminating device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light-emitting device having a plurality of light-emitting elements arranged to go on/out individually, which can make a boundary (cut-off line) between the lit and unlit light-emitting elements clear in a projection image with the plurality of light-emitting elements at least partially unlit while having a simple structure.SOLUTION: A light-emitting device according to the present invention comprises: a substrate; a plurality of light-emitting elements arrayed on the substrate with gaps arranged therebetween; and a light-scattering resin filled among the plurality of light-emitting elements. The light scattering resin in a region around at least one light-emitting element includes a thermochromic material.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a light emitting device including a plurality of light emitting elements.

In order to obtain light emission of a desired color such as white light, a combination of a light emitting element and a phosphor that converts the wavelength of a part of the light from the light emitting element is frequently used. In recent years, a light-emitting device in which a predetermined gap is opened, a plurality of light-emitting elements are arranged one-dimensionally or two-dimensionally in a plane, and a gap between adjacent light-emitting elements is filled with a sealing resin has been used as a lighting device, a lighting fixture, Or it is used for lighting for stage production.
Such a light-emitting device has a function of individually turning on and off a plurality of light-emitting elements, and when used in a lighting device such as a streetlight, it can illuminate only a route on which a person is walking. When used, it is possible to darken only the irradiation part to the person in order not to give glare to the oncoming vehicle or person. When used for stage lighting, it is possible to illuminate only a part or to darken only a part. Therefore, there is a demand to illuminate uniformly at the time of lighting and to turn off the light-emitting element completely when turning off part of the light-emitting element.

  However, in the light emitting device, when the distance between the light emitting elements is large, a slight dark portion (dark line) may be formed between the adjacent light emitting elements in the projected image. In order to suppress the formation of the dark part, it is necessary to reduce the distance between the arranged elements. On the other hand, when the distance between the arranged elements is reduced, when some of the light emitting elements are turned off, light is guided from the lighted light emitting elements to the light emitting elements that are turned off, and the light is turned off. It reaches the side surface of the light emitting element. By this guided light, light is emitted from the peripheral area of the light emitting element that has been turned off, and the peripheral area of the light emitting element that has been extinguished is unlikely to be a complete dark portion. For this reason, the boundary (cut-off) between the light-emitting element that is turned on and the light-emitting element that is turned off becomes unclear in the projected image.

  Patent Document 1 discloses a technology of a light emitting device including a plurality of light emitting elements arranged with a predetermined gap. The side surface of the light emitting element is covered with a semi-transparent film having semi-translucency that transmits part of the emitted light from the light-emitting layer. The semi-transparent film on the side surface of one light-emitting element reflects the light guided through the inter-element region from other adjacent light-emitting elements to extract the light from the inter-element region, and the guided light reaches the element side surface. To prevent. As a result, the light-emitting device of Patent Document 1 prevents the formation of dark lines in the inter-element region when the light-emitting element is turned on, and makes the cut-off clear when the light is turned off.

Japanese Patent Laying-Open No. 2015-177021

  However, in the light emitting device of Patent Document 1, it is necessary to cover the side surface of each light emitting device with a semi-transparent film, and thus the manufacturing process becomes complicated.

  An object of the present invention is to provide a boundary (cutoff) between a light-emitting element that is turned on and a light-emitting element that is turned off when at least some of the plurality of light-emitting elements are turned off, although the structure is simple. It is to provide a light emitting device that makes clear in a projected image.

  In order to solve the above problems, a light-emitting device of the present invention includes a substrate, a plurality of light-emitting elements arranged with a gap on the substrate, a light-scattering resin filled between the plurality of light-emitting elements, Is provided. The light scattering resin in a region around at least one of the plurality of light emitting elements includes a thermochromic material.

  According to the present invention, a cut-off in a projected image can be clarified using a simple configuration when at least a part of a plurality of light emitting elements that are individually turned on and off are turned off.

(a) is explanatory drawing which shows the outline of the upper surface structure of the light-emitting device 1 of this embodiment as an example in case all the light emitting elements are lighting, and the course of light, (b) is a figure (a). 2A is an explanatory diagram showing an outline of the AA ′ cross-sectional structure and a light path. (A) is explanatory drawing which shows the outline of the upper surface structure of the light-emitting device of FIG. 1 (a), and the course of light when the light emitting element arrange | positioned in the center turns off, (b) is figure (a). 2A is an explanatory diagram showing an outline of the AA ′ cross-sectional structure and a light path. (a) is a top view of the light-emitting device 1 of this embodiment as an example when all the light-emitting elements are turned off, and (b) is an AA ′ cross-sectional view of FIG. .

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. In all the drawings, components having the same function are given the same reference numerals, and repeated description thereof is omitted.

<First embodiment>
First, the outline of the configuration according to the light emitting device 1 of the first embodiment and the path of light emitted from the side surface of the light emitting element will be described with reference to FIGS. 1 and 2.

  The light-emitting device 1 of the present invention includes a substrate 70, a plurality of light-emitting elements 10 arranged on the substrate 70 so that the side surfaces are spaced from each other, and a light scattering property filled between the plurality of light-emitting elements 10. And a resin 20. The light scattering resin 20 in a region around at least one of the plurality of light emitting elements 10 (light emitting element 11) includes a thermochromic material.

  The thermochromic material 30 is transparent to the light of the light emitting element 11 at the temperature reached by the heat of the light emitting element 11 when the light emitting element 11 is turned on, and the light of the light emitting element 11 is transmitted at the temperature when the light emitting element 11 is turned off. Use one that does not transmit.

  As the light scattering resin 20, a mixture of a light scattering agent that scatters the light of the light emitting element 10 and a binder resin that is transparent to the light of the light emitting element 10 is used.

  The light-emitting element 10 is an element that emits light from an upper surface and a side surface, and a desired element such as an LED element or an EL element can be used.

In such a light emitting device 1, when all the light emitting elements 10 are lit, light is emitted from the upper surface and side surfaces of the light emitting elements 10. The light 40 emitted from the side surface of the light emitting element 10 enters the light scattering resin 20 and is scattered in all directions. A part of the scattered light becomes light (guided light) 43 guided in the direction of the adjacent light emitting element 10 with a gap s. A part of the guided light 43 is scattered by the light scattering resin 20, and another part is reflected by the side surface of the light emitting element 10 that has arrived, and all becomes light 44 toward the upper surface of the light scattering resin 20. Since the thermochromic material 30 is transparent to light during lighting, it does not block the scattering, waveguiding, and reflection of the light 40 from the side surface (FIG. 1). Therefore, light is emitted from the entire top surface of the light emitting device 1.
On the other hand, as shown in FIGS. 2A and 2B, when some of the light emitting elements 11 are turned off and the remaining light emitting elements 10 are turned on, the thermochromic material 30 around the light emitting elements 11 that are turned off. Since the temperature decreases and light is not transmitted, a light shielding region 31 that does not transmit light is formed (FIG. 2). For this reason, the guided light 43 from the light emitting element 10 that is lit cannot pass through the light shielding region 31 and cannot reach the side surface of the light emitting element 11. Therefore, light is not emitted upward from the light-emitting element 11 that is turned off and the surrounding thermochromic material 30, so that the cut-off between the light-emitting element 10 that is turned on and the surrounding area in the projected image is clear.

  With reference to FIGS. 1 to 3, the configuration of the present embodiment will be further described in detail.

  The light emitting device 1 of the present embodiment includes a frame member 80 provided on the substrate 70 in addition to the above-described substrate 70, the plurality of light emitting elements 10 (11), and the light scattering resin 20, and a plurality of light emitting elements. 10 (11) and the wavelength conversion layer 60 disposed on the upper surface of the light-scattering resin 20. The frame member 80 is provided around the light emitting elements 10 arranged on the outermost side with a space therebetween. The side surface of the wavelength conversion layer 60 is covered with a frame material 80. In this embodiment, all the light emitting elements are connected to a drive circuit controlled so as to be able to be turned on and off individually. Further, the light scattering resin 20 containing the thermochromic material 30 is filled in the gaps s between all the light emitting elements 10 (11).

As the thermochromic material 30, a material whose light transmittance of the light emitting element 10 (11) is reversibly changed by the heat of the light emitting element 10 (11) is used. For example, a material that is transparent and transmits light at a temperature when the light-emitting element 10 (11) is turned on, and is colored black at a temperature when the light-emitting element 10 (11) is turned off to prevent light transmission is used. . As an example, a leuco dye whose color changes from colored to transparent (colorless) depending on the temperature (for example, OR-30, OR-60, etc., Recording Materials Research Laboratory, Inc.) can be used.
The concentration of the thermochromic material 30 with respect to the light-scattering resin 20 is set so that the light-emitting element 10 has transparency when lighted, transmits light, and blocks light when turned off.
It is preferable that the refractive index of the thermochromic material 30 when the light-emitting element 10 is turned on is approximately the same as the refractive index of the binder resin constituting the light-scattering resin 20 because the light transmittance is increased.

As the light scattering agent of the light scattering resin 20, titanium oxide, zinc oxide, or the like can be used. The content of the light scattering agent with respect to the binder resin is such that a part of the light scattering agent 20 is scattered while being guided through the side surface of the light emitting element 10 and can be emitted from the upper surface of the light scattering resin 20 with a uniform distribution. Set to.
Any binder resin may be used as long as it has transparency and heat resistance. For example, dimethyl silicone (manufactured by Shin-Etsu Chemical Co., Ltd.) can be used. The refractive index of the binder resin is preferably about the same as or lower than the refractive index of the wavelength conversion layer 60. Thereby, the light from the upper surface of the light scattering resin 20 can be efficiently incident on the wavelength conversion layer 60.

  As an example of the light emitting element 10 (11), an LED element that emits blue light having a predetermined wavelength is used. In the example of FIG. 2A, these light emitting elements 10 (11) are arranged on a substrate 70 in a square matrix (3 rows × 3 columns) in a two-dimensional direction with a predetermined gap s. Yes. The arrangement of the light emitting elements 10 is determined so that a desired light distribution can be obtained. The interval s is a distance at which a dark line is not generated in a projected image at a position between the light emitting elements 10 and 10, and heat from the light emitting elements 10 is conducted to the surrounding thermochromic material 30 to change its color temperature. It is necessary to have such a distance that the light-shielding region 31 is generated by the arrival.

  The wavelength conversion layer 60 covers the upper surfaces of the plurality of light emitting elements 10 (11) and the entire upper surface of the light scattering resin 20, and the upper surface of the wavelength conversion layer 60 serves as a light extraction surface of the light emitting device 1. The wavelength conversion layer 60 is typically a layer in which a phosphor such as a YAG phosphor or SiAlON phosphor is dispersed and cured in a translucent resin such as a silicone resin, an epoxy resin, or an inorganic binder. Alternatively, fluorescent glass or fluorescent ceramic can be used. In this embodiment, a YAG phosphor is used.

  The substrate 70 is an AlN substrate, and a wiring pattern is formed of a conductive metal such as Au. When the light emitting element 10 (11) is a face-up type LED element, the electrode pad for power feeding disposed on a part of the upper surface of the light emitting element 10 (11) is, for example, a gold wire (not shown). And connected to the wiring pattern of the substrate 70. By controlling the current supply to the individual light emitting elements 10 (11) via the wiring pattern and the wires, the lighting and extinguishing of the individual light emitting elements 10 (11) are controlled.

  The frame member 80 is used as an injection frame when injecting the resin that forms the light scattering resin 20 and the wavelength conversion layer 60, but may be omitted. As a material of the frame member 80, ceramic, resin, or the like can be used.

  Next, when all the light emitting elements 10 (11) are turned off (FIG. 3), when all the light emitting elements 10 (11) are turned on (FIG. 1), and some of the light emitting elements 11 are turned off. The operation of each part of the light emitting device 1 of the present embodiment in the case of being (FIG. 2) will be described. In addition, as an example, it demonstrates using the thermochromic material 30 which colors black at 65 degrees C or less, and becomes transparent at 70 degrees C or more.

  When all the light emitting elements 10 (11) are turned off (FIGS. 3A and 3B), the thermochromic material 30 in the light-scattering resin 20 has a temperature lower than 65 ° C. at room temperature. Presents a black color.

When all the light emitting elements 10 (11) are lit (FIGS. 1A and 1B), light (blue light) 50 and 40 from the upper surface and side surfaces of the light emitting elements 10 (11) is emitted. . The temperature of the thermochromic material 30 contained in the light-scattering resin 20 is increased by the heat of the light emitting element 10 (11) due to light emission. When the temperature reaches 70 ° C., the color of the thermochromic material is transparent from black to colorless (colorless). Changes to. Thereby, transmission of the light 40 from the side surface of the light emitting element 10 (11) toward the wavelength conversion layer 60 is not inhibited.
The light 50 emitted from the upper surface of the light emitting element 10 (11) enters the wavelength conversion layer 60, and a part of the light 50 is converted into yellow light by the phosphor. On the other hand, the light 40 emitted from the side surface of the light-emitting element 10 (11) enters the light-scattering resin 20, and becomes a guided light 43 that is guided while being partially scattered by the light-scattering agent. Head for 10 (11). The light scattered by the light scattering resin 20 becomes light 41 directed from the inside of the light scattering resin 20 toward the wavelength conversion layer 60. The light 44 that has reached the adjacent light emitting element 10 (11) is reflected by the side surface thereof and travels toward the wavelength conversion layer 60. The light from the side surface of the light emitting element 10 (11) finally enters the wavelength conversion layer 60 together with the light 50 from the upper surface of the light emitting element 10 (11).
Therefore, substantially uniform blue light enters the wavelength conversion layer 60 from the upper surface of the light emitting element 10 (11) and the upper surface of the light scattering resin 20. In the wavelength conversion layer 60, part of the blue light is converted into yellow fluorescence by the phosphor, and the converted yellow fluorescence and the remaining blue light are mixed. Thereby, white light is emitted from the upper surface of the wavelength conversion layer 60 to the outside.

  Next, when only the central light-emitting element 11 is turned off (FIGS. 2A and 2B), the temperature of the light-emitting element 11 is lowered, so that it is contained in the light-scattering resin 20 around the central light-emitting element 11. When the temperature of the thermochromic material 30 is lowered to 65 ° C. or lower, the thermochromic material changes to black. As a result, a light shielding region 31 is formed around the central light emitting element 11 by the light scattering resin 20 containing the thermochromic material 30 colored black. On the other hand, since the light-emitting elements 10 surrounding the light-emitting elements 11 continue to be lit, the light-scattering resin 20 around these light-emitting elements 10 remains transparent, and the light 40 from the side faces the side faces of the central light-emitting element 11. It becomes the guided light 43 propagating in the light scattering resin 20 toward. However, since the light shielding region 31 is formed around the light emitting element 11, it is absorbed by the light shielding region 31 of the guided light 43 and does not reach the side surface of the light emitting element 11. Thereby, no light is emitted from the area around the light emitting element 11, and the light emitting element 11 that has been turned off and its peripheral area can be turned off completely.

  According to the present embodiment, when part of the plurality of light emitting elements 10 (light emitting element 11) is turned off, the thermochromic material 30 in the surrounding area is colored black and the light shielding area 31 is formed. The cut-off in the projected image becomes clear. In addition, when all the light emitting elements 10 (11) are turned on, the thermochromic material 30 becomes transparent, so that the amount of light emitted from the upper surface of the light scattering resin 20 is not reduced. Almost uniform light can be emitted from the upper surface of the light emitting element 10 (11) and the upper surface of the light scattering resin 20.

  Although the discoloration temperature of the thermochromic material 30 is set to 65 ° C. in the above embodiment, it is preferable to determine the calorific value of the light emitting element 10 and the surrounding temperature atmosphere. Further, the color change temperature can be controlled by the molecular structure and blending of the thermochromic material 30.

  The light-emitting element 10 (11) may be a face-down type as long as it is an LED element that emits blue light having a predetermined wavelength.

  In the case where the thermochromic material 30 has a function of scattering light, a light scattering agent may also be used.

  In the above description, the case of the thermochromic material 30 whose transmittance varies depending on the temperature has been described. However, depending on the use of the light emitting device 1 such as a stage illumination light source, the thermochromic material whose color varies depending on the temperature. Material 30 can also be used.

  As the binder resin used for the light-scattering resin 20, a heat-responsive polymer resin that has transparency at high temperatures and shields light at low temperatures and reversibly changes its transmittance depending on temperature may be used. . In this case, a combination of a thermoresponsive polymer resin and a light scattering agent can be used as the light scattering resin 20 without using the thermochromic material 30.

  In the present embodiment, the case where the gaps s between all the light emitting elements 10 are filled with the light scattering resin 20 including the thermochromic material 30 has been described, but the light emitting elements 10 (11) to be individually turned off are determined. If it is, the gap s around the light emitting element 11 only needs to be filled with the light scattering resin 20 including the thermochromic material 30. In the present embodiment, the case where the light emitting elements 10 are arranged in a square matrix shape in the two-dimensional direction has been described. However, the present invention is not limited to this, and the light emitting elements 10 may be arranged in a one-dimensional direction.

  Next, an example of a method for manufacturing the light emitting device 1 of the present embodiment will be described.

  On the AlN substrate 70 on which the wiring pattern is printed, nine blue light emitting elements 10 each having a side of 300 mm are arranged in a square matrix (3 rows × 3 columns) in a two-dimensional direction with a predetermined gap s. Implement.

  Next, wire bonding is performed on the electrode pad of the blue light emitting element 10 and the wiring pattern of the AlN substrate 70 using a gold wire, and the light emitting element 10 and the substrate 70 are electrically connected.

  Next, the frame member 80 is arranged around the light emitting element 10 arranged on the outermost side with a space therebetween.

  Thereafter, a resin paste before curing in which a predetermined amount of thermochromic material 30 is uniformly dispersed in a light scattering resin 20 containing a predetermined amount of scattering agent is prepared. The prepared resin paste is injected between the frame member 80 and the side surface of the light emitting element 10 on the frame member 80 side, and is injected so as to fill the gap s between the adjacent light emitting elements 10. The injected resin paste is cured under predetermined conditions (heating, ultraviolet irradiation, etc.). Thereby, the thermochromic material 30 containing light scattering resin 20 filled between all the light emitting elements 10 is formed.

  Subsequently, a transparent resin (transparent resin paste) before curing, in which a yellow phosphor is dispersed at a predetermined concentration, is prepared, and the transparent resin paste is used as a dispenser to cure all the blue light emitting elements 10 and cure the light scattering property. The wavelength conversion layer 60 is formed by applying the resin 20 so as to cover the upper surface of the resin 20 and the side surfaces of the frame member 80 and curing the resin 20 under predetermined curing conditions (heating, ultraviolet irradiation, etc.).

  In the manufacturing method described above, the case where the gaps s between all the light emitting elements 10 are filled with the light scattering resin 20 containing the thermochromic material has been described. However, the gaps s around the light emitting element 10 (11) that turns on and off. In the case where only the thermochromic material-containing light scattering resin 20 is filled, in the step of forming the light scattering resin 20 described above, the scattering resin paste that does not contain the thermochromic material separately from the thermochromic material-containing resin paste And a step of filling a gap other than the gap around the light emitting element 10 (11) to be turned on / off with a resin paste containing no thermochromic material is added.

  In the light emitting device 1 of the present embodiment, the substrate 70 can be further mounted on a metal substrate (for example, made of Cu). In this case, the substrate 70 is bonded to a metal substrate using an adhesive containing a metal (for example, Ag) filler, and the wiring pattern of the substrate 70 and the wiring pattern of the metal substrate are wire-bonded using a gold wire. By mounting the light emitting device 1 on the metal substrate, the heat of the light emitting element 10 can be efficiently conducted to the metal substrate, and the heat extraction efficiency of the light emitting element 10 can be increased.

  The light-emitting device of the present invention described above can be used as a light source such as a light-emitting array or an LED array, or as a light source of a lighting device such as general lighting, street light, headlamp, or stage lighting.

DESCRIPTION OF SYMBOLS 1 ... Light-emitting device, 10 ... Light emitting element, 20 ... Light-scattering resin, 30 ... Thermochromic material, 60 ... Wavelength conversion layer, 70 ... Substrate, s ... Gap

Claims (7)

A light-emitting device comprising: a substrate; a plurality of light-emitting elements arranged on the substrate with a gap; and a light-scattering resin filled between the plurality of light-emitting elements,
The light-emitting device, wherein the light-scattering resin in a region around at least one of the plurality of light-emitting elements includes a thermochromic material. The light-emitting device according to claim 1,
The thermochromic material is transparent at a temperature reached by heat of the light emitting element when the light emitting element is turned on, and does not transmit the light at a temperature when the light emitting element is turned off. The light-emitting device according to claim 1 or 2,
The light-emitting device is characterized in that the light-scattering resin is a transparent binder resin in which a light-scattering agent is dispersed. The light-emitting device according to any one of claims 1 to 3,
A light-emitting device, wherein a wavelength conversion layer for wavelength-converting at least part of light emitted from the light-emitting elements is disposed on the plurality of light-emitting elements and the light-scattering resin. The light-emitting device according to claim 3,
The light-emitting device, wherein a refractive index of the thermochromic material is approximately the same as a refractive index of the binder. The light-emitting device according to any one of claims 1 to 5,
The light-emitting device, wherein the light-emitting element in which the light-scattering resin containing the thermochromic material is arranged can be turned off individually.   The illuminating device using the light-emitting device as described in any one of Claims 1-6.

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