JP6788375B2 - Light emitting device and lighting device - Google Patents

Description

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

In the light emitting device, a combination of a light emitting element and a phosphor that converts a part of the light from the light emitting element into wavelength is often used in order to obtain light emission of a desired color such as white light. In recent years, a light emitting device in which a plurality of light emitting elements are arranged one-dimensionally or two-dimensionally in a plane with a predetermined gap and the gap between adjacent light emitting elements is filled with a sealing resin has been used for lighting equipment, lighting equipment, and the like. Alternatively, it is used for lighting for stage production.
Such a light emitting device has a function of turning on and off a plurality of light emitting elements individually, and when used in a lighting device such as a street light, it can illuminate only the path on which a person is walking, and can be used as a vehicle lighting tool. When used, it is possible to darken only the irradiation portion for a person so as not to give glare to an oncoming vehicle or a person. When used for stage production lighting, it can illuminate only part of it or dim only part of it. Therefore, there is a desire to illuminate the light uniformly when it is lit, and to completely darken the light-extinguishing portion when a part of the light emitting element is turned off.

However, in the above 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 this dark portion, 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, the light is waveguideed from the lit light emitting element toward the turned off light emitting element, and the light is turned off. It reaches the side surface of the light emitting element. Due to this waveguide light, light is emitted from the region around the light emitting element that has been turned off, and the region around the light emitting element that has been turned off is unlikely to become a completely dark part. Therefore, the boundary (cutoff) between the light emitting element that is lit and the light emitting element that is turned off becomes unclear in the projected image.

Patent Document 1 discloses a technique 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 semipermeable membrane having a semipermeable membrane that transmits a part of the light emitted from the light emitting layer. The semitransparent film on the side surface of one light emitting element reflects the light waveguideed in the inter-element region from another adjacent light emitting element to extract the light from the inter-element region, and reaches the side surface of the waveguide light. 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 lit, and makes the cutoff clear when the light emitting element is turned off.

JP-A-2015-177021

However, in the light emitting device of Patent Document 1, the side surface of each light emitting device needs to be covered with a semipermeable membrane, which complicates the manufacturing process.

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

In order to solve the above problems, the light emitting device of the present invention includes a substrate, a plurality of light emitting elements arranged with a gap on the substrate, and a light scattering resin filled between the plurality of light emitting elements. To be equipped. The light scattering resin in at least one peripheral region of the plurality of light emitting devices includes a thermochromic material.

According to the present invention, it is possible to clarify the cutoff in the projected image when at least a part of the plurality of light emitting elements that are individually turned on and off is turned off by using a simple configuration.

(A) is an explanatory view showing the outline of the upper surface structure of the light emitting device 1 of the present embodiment and the path of light as an example when all the light emitting elements are lit, and FIG. It is explanatory drawing which shows the outline of the cross-sectional structure of AA'of () and the path of light. (A) is an explanatory view showing the outline of the upper surface structure of the light emitting device of FIG. 1 (a) and the path of light when the light emitting element arranged at the center is turned off, and FIG. 1 (b) is an explanatory view showing the path of light. It is explanatory drawing which shows the outline of the cross-sectional structure of AA'of () and the path of light. (A) is a top view of the light emitting device 1 of the present embodiment as an example when all the light emitting elements are turned off, and (b) is a cross-sectional view taken along the line AA'of FIG. (A). ..

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

<First Embodiment>
First, the outline of the configuration according to the light emitting device 1 of the first embodiment and the path of the 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 side surfaces thereof have a gap s, and a light scattering property filled between the plurality of light emitting elements 10. The resin 20 is provided. The light scattering resin 20 in the region around at least one of the plurality of light emitting elements 10 (light emitting element 11) contains 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 lit, and emits the light of the light emitting element 11 at the temperature when the light emitting element 11 is turned off. Use a non-transparent material.

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 the upper surface and the 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 the side surface of the light emitting element 10. The light 40 emitted from the side surface of the light emitting element 10 is incident on the light scattering resin 20 and scattered in all directions inside the light scattering resin 20. A part of the scattered light becomes light (waveguided light) 43 that is guided in the direction of the adjacent light emitting element 10 with a gap s. A part of the waveguide light 43 is scattered by the light scattering resin 20, and the other part is reflected by the side surface of the light emitting element 10 that has reached, and all of them become the light 44 toward the upper surface of the light scattering resin 20. Since the thermochromic material 30 is transparent to light when lit, it does not block the scattering, waveguide, and reflection of the light 40 from the side surface (FIG. 1). Therefore, light is emitted from the entire upper 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 element 11 that is turned off is turned on. As the temperature drops and light is not transmitted, a light-shielding region 31 that does not transmit light is formed (FIG. 2). Therefore, the waveguide light 43 from the lit light emitting element 10 cannot pass through the light shielding region 31 and cannot reach the side surface of the light emitting element 11. Therefore, since the light is not emitted upward from the light emitting element 11 that is turned off and the thermochromic material 30 around the light emitting element 11, the cutoff between the light emitting element 10 that is turned off and the surrounding region thereof in the projected image becomes clear.

The configuration of the present embodiment will be described in detail with reference to FIGS. 1 to 3.

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

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 is used that is transparent and transmits light at the temperature at which the light emitting element 10 (11) is lit, and is colored black at the temperature at which the light emitting element 10 (11) is extinguished to prevent light transmission. .. As an example, a leuco dye (for example, OR-30 or OR-60 of Recording Materials Research Institute Co., Ltd.) that changes its color from colored to transparent (colorless) depending on the temperature 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 it is lit, transmits light, and blocks light when it is extinguished.
It is preferable that the refractive index of the thermochromic material 30 when the light emitting element 10 is lit is about the same as the refractive index of the binder resin constituting the light scattering resin 20 because the light transmission is enhanced.

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 in the binder resin is such that a part of the light 40 emitted from the side surface of the light emitting element 10 is dispersed while being waveguideed so that the light can be emitted from the upper surface of the light scattering resin 20 in a uniform distribution. Set to.
The binder resin may be any one having transparency and heat resistance, and 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 smaller than the refractive index of the wavelength conversion layer 60. As a result, 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 in a square matrix shape (3 rows × 3 columns) in the two-dimensional direction with a predetermined gap s on the substrate 70. There is. The arrangement of the light emitting elements 10 is determined so that the desired light distribution can be obtained. The interval s is a distance at which a dark line does not occur in the projected image of the position between the light emitting element 10 and the light emitting element 10, and the heat from the light emitting element 10 is conducted to the surrounding thermochromic material 30 to reach the discoloration temperature. A distance is required so that the light-shielding region 31 is generated by reaching the light-shielding region 31.

The wavelength conversion layer 60 covers the entire upper surfaces of the plurality of light emitting elements 10 (11) and 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 obtained by dispersing a fluorescent substance such as a YAG-based phosphor or a SiAlON-based phosphor in a translucent resin such as a silicone resin, an epoxy resin, or an inorganic binder and curing the layer. Alternatively, fluorescent glass or fluorescent ceramic can be used. In this embodiment, a YAG-based phosphor is used.

The substrate 70 is a substrate made of AlN, and the 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 power feeding electrode pad arranged on a part of the upper surface of the light emitting element 10 (11) is, for example, a gold wire (not shown). It is connected to the wiring pattern of the substrate 70 using. By controlling the supply of current to the individual light emitting elements 10 (11) via the wiring pattern and the wire, the turning on and off of the individual light emitting elements 10 (11) is controlled.

The frame material 80 is used as an injection frame when injecting the light scattering resin 20 and the resin forming the wavelength conversion layer 60, but it can be omitted. As the material of the frame material 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 when 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 this case (FIG. 2) will be described. As an example, the thermochromic material 30 which is colored black at 65 ° C. or lower and becomes transparent at 70 ° C. or higher will be described.

When all the light emitting elements 10 (11) are turned off (FIGS. 3A and 3B), the temperature of the thermochromic material 30 in the light scattering resin 20 becomes lower than 65 ° C. depending on the room temperature. It is black.

When all the light emitting elements 10 (11) are lit (FIGS. 1A and 1B), the light (blue light) 50 and 40 from the upper surface and the side surface of the light emitting element 10 (11) are emitted. .. The temperature of the thermochromic material 30 contained in the light scattering resin 20 rises due to the heat of the light emitting element 10 (11) due to light emission, and when the temperature reaches 70 ° C., the color of the thermochromic material changes from black to transparent (colorless). It changes to. As a result, the transmission of the light 40 from the side surface of the light emitting element 10 (11) toward the wavelength conversion layer 60 is not hindered.
The light 50 emitted from the upper surface of the light emitting element 10 (11) is incident on the wavelength conversion layer 60, and a part of the light 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) becomes a waveguide light 43 that is incident on the light scattering resin 20 and is waveguided while being partially scattered by a light scattering agent, and is adjacent to the light emitting elements. Head to 10 (11). The light scattered by the light scattering resin 20 becomes the 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 elements 10 (11) is reflected by the side surface thereof and heads 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 is incident on 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, a 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. As a result, 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 drops, so that the light scattering resin 20 around the central light emitting element 11 contains the light scattering element 11. When the temperature of the thermochromic material 30 is lowered to 65 ° C. or lower, the thermochromic material turns black. As a result, a light-shielding region 31 made of the light-scattering resin 20 containing the thermochromic material 30 colored in black is formed around the central light-emitting element 11. On the other hand, since the light emitting element 10 surrounding the light emitting element 11 continues to light, the light scattering resin 20 around these light emitting elements 10 remains transparent, and the light 40 from the side surface is the side surface of the central light emitting element 11. The waveguide light 43 propagates in the light scattering resin 20 toward the light scattering resin 20. 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 waveguide light 43 and does not reach the side surface of the light-emitting element 11. As a result, no light is emitted from the region around the light emitting element 11, and the light emitting element 11 and its peripheral region that have been turned off can be completely turned off.

According to the present embodiment, when a part of the plurality of light emitting elements 10 (light emitting element 11) is turned off, the thermochromic material 30 in the surrounding region is colored black to form the light shielding region 31. The cutoff in the projected image becomes clear. Further, when all the light emitting elements 10 (11) are lit, the amount of light emitted from the upper surface of the light scattering resin 20 is not reduced because the thermochromic material 30 becomes transparent. 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 preferably determined in consideration of the calorific value of the light emitting element 10 and the ambient temperature atmosphere. Further, the discoloration temperature can be controlled by the molecular structure and composition of the thermochromic material 30.

As the light emitting element 10 (11), a face-down type or the like may be used as long as it is an LED element that emits blue light having a predetermined wavelength.

When the thermochromic material 30 also 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 changes depending on the temperature has been described, but the thermochromic whose color changes depending on the temperature depending on the application of the light emitting device 1 such as used as a stage lighting light source. Material 30 can also be used.

As the binder resin used for the light scattering resin 20, a heat-responsive polymer resin having transparency at a high temperature and light-shielding at a low temperature, whose transmittance changes reversibly depending on the temperature, may be used. .. In this case, a combination of the heat-responsive polymer resin and the 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 containing the thermochromic material 30 has been described, but the light emitting elements 10 (11) to be individually turned off are determined. If so, the gap s around the light emitting element 11 may be filled with the light scattering resin 20 containing the thermochromic material 30. Further, in the present embodiment, the case where the light emitting elements 10 are arranged in a square matrix in the two-dimensional direction has been described, but the present invention is not limited to this, and the light emitting elements 10 may be arranged in the one-dimensional direction.

Next, an example of the manufacturing method of 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 having a side of 300 mm are arranged in a square matrix shape (3 rows × 3 columns) in the two-dimensional direction with a predetermined gap s. Implement.

Next, wire bonding is performed between 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 at intervals around the light emitting element 10 arranged on the outermost side.

Then, a resin paste before curing is prepared in which a predetermined amount of the thermochromic material 30 is uniformly dispersed in the light scattering resin 20 containing a predetermined amount of the scattering agent. The prepared resin paste is injected between the frame material 80 and the side surface of the light emitting element 10 on the frame material 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.). As a result, the thermochromic material 30-containing light scattering resin 20 packed between all the light emitting elements 10 is formed.

Next, a transparent resin (transparent resin paste) before curing, in which the yellow phosphor is dispersed at a predetermined concentration, is prepared, and the transparent resin paste is applied to all the upper surfaces of the blue light emitting elements 10 using a dispenser, and the cured light scattering property. It is applied so as to cover the upper surface of the resin 20 and the side surface of the frame material 80, and is cured under predetermined curing conditions (heating, ultraviolet irradiation, etc.) to form the wavelength conversion layer 60.

In the above-mentioned manufacturing method, 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, but the gaps around the light emitting elements 10 (11) that turn on and off are s. When only the thermochromic material-containing light-scattering resin 20 is filled, in the step of forming the above-mentioned light-scattering resin 20, a scattering resin paste that does not contain a thermochromic material separately from the thermochromic material-containing resin paste Is prepared, and a step of filling the gaps other than the gaps around the light emitting element 10 (11) that is turned on and 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 the metal substrate by 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 by using a gold wire. By mounting the light emitting device 1 on a metal substrate, the heat of the light emitting element 10 can be efficiently conducted to the metal substrate, and the heat drawing efficiency of the light emitting element 10 can be improved.

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

1 ... light emitting device, 10 ... light emitting element, 20 ... light scattering resin, 30 ... thermochromic material, 60 ... wavelength conversion layer, 70 ... substrate, s ... gap

Claims (6)

A light emitting device including a substrate, a plurality of light emitting elements arranged with a gap on the substrate, and a light scattering resin filled between the plurality of light emitting elements.
In the first light emitting element, which is at least one of the plurality of light emitting elements, the light scattering resin in the surrounding region contains a thermochromic material.
The thermochromic material is a material in which the light transmission rate changes reversibly when the temperature reaches the discoloration temperature, and at a temperature reached by the heat of the first light emitting element when the first light emitting element is lit. It is transparent, and at the temperature at which the first light emitting element is turned off, the light emitted from the other light emitting element is blocked and does not reach the first light emitting element .
The distance between the first light emitting element and the second light emitting element adjacent to the first light emitting element among the plurality of light emitting elements is such that the first light emitting element and the second light emitting element are lit. If this is the case, the temperature at which the thermochromic material between the first light emitting element and the second light emitting element becomes transparent is reached, and the first light emitting element and the second light emitting element become transparent. When only one of them is lit, the thermochromic material around the luminescent element that is lit does not reach a temperature at which it becomes transparent, and a light-shielding region that blocks light from the lit light-emitting element. A light emitting device characterized by a distance that causes A light emitting device according to any one of claims 1,
A light emitting device characterized in that a wavelength conversion layer that converts at least a part of the light emitted from the light emitting element is arranged on the upper surface of the plurality of light emitting elements and the light scattering resin. The light emitting device according to claim 1 or 2 .
The thermochromic material is a light emitting device characterized in that it is black at a temperature at which the light is blocked. The light emitting device according to any one of claims 1 to 3 .
A light emitting device characterized in that the light emitting elements in which the light scattering resin containing the thermochromic material is arranged around the light emitting elements can be individually extinguished. A lighting device using the light emitting device according to any one of claims 1 to 4 . With the board
A first light emitting element and a second light emitting element, which are arranged on the substrate with a gap and can be turned on and off independently,
A light-scattering resin located in the gap and covering the side surfaces of the first light emitting element and the second light emitting element,
A light emitting device including the first light emitting element, the second light emitting element, and a wavelength conversion layer covering the upper surface of the light scattering resin layer.
The light-scattering resin contains a thermochromic material or a heat-responsive polymer resin whose light transmittance changes reversibly with temperature, and is one of the first light emitting element and the second light emitting element. When is lit and the other is off, the light of the lit light emitting element is blocked so that it does not reach the lit light emitting element.
The thermochromic material is colored at room temperature, and at a temperature reached by the light scattering resin around the light emitting element that is turned on when either the first light emitting element or the second light emitting element is turned on. Is a material having a discoloration temperature that changes from the colored state to the light transmitting state.
The thermosetting polymer resin is shielded from light at a low temperature, and the light scattering resin around the light emitting element that is turned on when either the first light emitting element or the second light emitting element is turned on reaches. It is a material that is transparent at high temperatures.
The wavelength conversion layer is made of a layer in which a phosphor is dispersed in a translucent resin, fluorescent glass or fluorescent ceramic, and at least a part of the light emitted from the first light emitting element and the second light emitting element is different. Converts to colored light and emits it from the top surface to the outside ,
The first light emitting element and the second light emitting element are adjacent to each other, and the distance between the first light emitting element and the second light emitting element is the distance between the first light emitting element and the second light emitting element. When is lit, the temperature at which the thermochromic material between the first light emitting element and the second light emitting element becomes transparent is reached, and the first light emitting element and the second light emitting element are emitted. When only one of the elements is lit, the thermochromic material around the illuminating element that is lit does not reach a temperature at which the thermochromic material becomes transparent, and the light from the lit light emitting element is blocked. A light emitting device characterized by a distance that creates a light-shielding area .

Images