WO2011004795A1

WO2011004795A1 - Light emitting device

Info

Publication number: WO2011004795A1
Application number: PCT/JP2010/061423
Authority: WO
Inventors: 猛宮下; 弘一鈴木
Original assignee: シーシーエス株式会社
Priority date: 2009-07-07
Filing date: 2010-07-05
Publication date: 2011-01-13
Also published as: TW201126769A; JPWO2011004795A1

Abstract

Disclosed is a light emitting device, by which ultraviolet rays and short-wavelength visible rays can be efficiently converted into visible rays having longer wavelengths and the converted visible rays can be efficiently taken out to the outside of the device. The light emitting device is provided with: a base body having a section recessed from the upper end surface of the base body; an LED element which is mounted on the bottom surface of the recess and emits the ultraviolet rays or the short-wavelength visible rays; and a short-wavelength transmission filter, which passes through the ultraviolet rays and the short-wavelength visible rays and reflects the visible rays having the longer wavelengths, a wavelength conversion member which contains a fluorescent material, and a long-wavelength transmission filter, which passes through the visible rays having the longer wavelengths and reflects the ultraviolet rays and the short-wavelength visible rays, said short-wavelength transmission filter, the wavelength conversion member and the long-wavelength transmission filter being disposed in this order from the light emitting surface side of the LED element. The short-wavelength transmission filter is adhered on the base body such that the short-wavelength transmission filter hermetically seals the LED element in the recess.

Description

Light emitting device

The present invention efficiently converts ultraviolet light and short-wavelength visible light into long-wavelength visible light, and can efficiently extract the converted visible light, and also has moisture resistance and heat dissipation. The present invention relates to an excellent light emitting device.

Conventionally, a light-emitting device that emits light of a color different from the emission color of LED elements including white has been developed by combining LED elements that emit ultraviolet rays and short-wavelength visible light and various phosphors ( Patent Document 1). Such a light emitting device using an LED element has advantages such as small size, power saving and long life, and is widely used as a light source for display and a light source for illumination.

Examples of such a light emitting device include a device in which an LED element is mounted in the recess of the substrate on which the recess is formed, and a sealing layer that covers the LED element and a phosphor layer are laminated in this order. . In this light emitting device, most of the ultraviolet rays and short wavelength visible light emitted from the LED elements excite the phosphor and are converted into longer wavelength visible light, but some are not absorbed by the phosphor (visible). In some cases, the phosphor layer is transmitted as it is without being converted into light. In this case, since the conversion efficiency of ultraviolet rays or short-wavelength visible light emitted from the LED element into longer-wavelength visible light is lowered, the light-emitting efficiency of the light-emitting device is lowered. In addition, if ultraviolet rays that are transmitted through the phosphor layer without being converted to visible light are emitted outside the light emitting device, the human body may be adversely affected.

On the other hand, among the visible light emitted by the phosphors excited by ultraviolet rays or short-wavelength visible light emitted by the LED elements, those directed toward the substrate on which the LED elements are mounted are absorbed by the substrate and emit light. Cannot be taken out of the device. For this reason, the light emission efficiency of the light emitting device also decreases due to this factor.

In addition, since the LED element has an extremely long life as compared with the conventional light source, the reflector formed on the base and its inner surface is exposed to visible light for a long time. As described above, the substrate exposed to visible light for a long time deteriorates and changes color. This also affects the emission color of the light emitting device.

Incidentally, Patent Document 2 discloses that a high refractive index layer is provided under the phosphor layer to improve the efficiency of extracting visible light. However, in such a configuration, it is possible to prevent the light from proceeding to the sealing layer, but it is difficult to extract the light that has once traveled into the high refractive index layer into the phosphor layer again.

Further, in Patent Document 3, a first optical filter whose reflectance with respect to excitation light emitted from the LED element is lower than reflectance with respect to fluorescence emitted from the phosphor is disposed between the LED element and the phosphor, It is disclosed that an opening is provided between the reflecting surface formed in the reflector recess and the first optical filter. However, when such an opening is provided, part of the fluorescence emitted by the phosphor proceeds to the bottom surface of the recess through the opening, and most of the fluorescence that has traveled to the bottom surface of the recess is The first optical filter becomes a barrier and cannot be taken out of the light emitting device. For this reason, the luminous efficiency of the light emitting device is reduced.

JP 2005-191197 A JP 2007-27751 A JP 2005-294288 A

The present invention has been made in view of such problems, and efficiently converts ultraviolet rays and short-wavelength visible rays into longer-wavelength visible rays, and efficiently converts the converted visible rays outside the apparatus. Providing a light-emitting device that can be taken out is a main intended problem.

That is, a light-emitting device according to the present invention includes a base having a recess opened at an upper end surface, an LED element that is mounted on the bottom surface of the recess and emits ultraviolet rays or short-wavelength visible light, and a light emission surface side of the LED element Arranged in this order from a short wavelength transmission filter that transmits ultraviolet light and short wavelength visible light and reflects longer wavelength visible light, a wavelength conversion member containing a phosphor, and longer wavelength visible light A long-wavelength transmission filter that transmits ultraviolet light and short-wavelength visible light, and is in close contact with the base so that the short-wavelength transmission filter hermetically seals the LED element in the recess. It is characterized by that. Examples of short-wavelength visible light include violet light, blue light, and green light, and ultraviolet light includes near ultraviolet light.

In such a case, the wavelength conversion member containing the phosphor is sandwiched between the short-wavelength transmission filter and the long-wavelength transmission filter, so that ultraviolet rays or short-wavelength visible light transmitted through the wavelength conversion member. Is reflected by the long wavelength transmission filter and travels through the wavelength converting member again. For this reason, the probability that ultraviolet rays or short-wavelength visible light excites the phosphor and is converted into longer-wavelength visible light can be improved, and the amount of light emission can be increased. On the other hand, among the visible light emitted by the phosphors excited by ultraviolet rays or short-wavelength visible light emitted from the LED element, the light traveling toward the substrate on which the LED element is mounted is the short-wavelength transmission filter. Then, the direction of travel is changed, the direction of travel is changed, the light travels toward the long wavelength transmission filter, passes through the filter, and is emitted outside the apparatus. Therefore, according to the present invention, ultraviolet rays and short-wavelength visible light can be efficiently converted into long-wavelength visible light, and the converted visible light can be efficiently taken out of the apparatus.

Further, the wavelength conversion member can be manufactured in a separate process as a separate body from the substrate on which the LED elements are mounted by potting application to the filter, printing by die coating or ink jet method. For this reason, management of the thickness of the wavelength conversion member is facilitated. Further, using a reference light source having a predetermined wavelength and light intensity, the emission color, illuminance, and the like of the wavelength conversion member are measured, and the wavelength conversion member is classified and managed according to the result, and a desired emission color or A light emitting device having the desired performance can be produced by selecting a device having illuminance and the like and combining it with a suitable LED element, so that variations in the luminescent color, illuminance, etc. of the final light emitting device are suppressed as much as possible. Can do.

Furthermore, since the visible light traveling toward the substrate on which the LED element is mounted is reflected by the short wavelength transmission filter, the visible light reaching the substrate is reduced, the deterioration of the substrate over time is suppressed, The light emission color change of the light emitting device is also suppressed.

In the present invention, since the short wavelength transmission filter is in intimate contact with the base, the short wavelength transmission filter transmits heat of the wavelength conversion member and the like to the base and exhibits a heat radiation (cooling) action. Further, it is possible to satisfactorily suppress the change in the emission color of the light emitting device due to the thermal deterioration of the phosphor in the wavelength conversion member.

Further, in the present invention, the short wavelength transmission filter hermetically seals the inside of the recess, so that gas can be prevented from entering the recess and a reflector made of a metal thin film is formed on the inner surface of the recess. Even when the metal thin film is formed, corrosion due to oxidation, sulfurization, chlorination, or the like of the metal thin film can be prevented. In addition, the short wavelength transmission filter may exhibit a waterproof function.

On the other hand, in the light emitting device described in Patent Document 3, since there is a gap (opening) between the concave reflecting surface of the reflector and the first optical filter, the heat of the phosphor is the first. Even if it is transmitted to the optical filter, it cannot be conducted to the reflector. For this reason, the light emitting device described in Patent Document 3 is inferior in heat dissipation performance, and it is considered that the emission color changes due to the thermal deterioration of the phosphor. Further, in the light emitting device described in Patent Document 3, since gas or moisture enters the recess from the gap (opening), the metal thin film may be corroded when the reflecting surface is made of a metal thin film.

As the LED element, specifically, those having a radiation peak at 490 nm or less are preferably used, and more preferably those having a radiation peak in the near ultraviolet region of 360 to 430 nm.

Specifically, the short-wavelength transmission filter and the long-wavelength transmission filter have a boundary where the level of the reflectance and transmittance of the electromagnetic wave is reversed 10 nm or more larger than the emission peak wavelength of the LED element and 500 nm. A dielectric multilayer film having the following wavelength region is preferable, and a dielectric multilayer film having a boundary in the wavelength region of 440 nm or less is more preferable. A dielectric multilayer film is formed by selecting and laminating two or more films having different refractive indexes from a thin film made of a highly transparent substance such as a metal oxide. It is also excellent.

When the light emitting device according to the present invention emits white light, the phosphors are phosphors emitting red light (hereinafter referred to as red phosphors), phosphors emitting green light (hereinafter referred to as green phosphors). And a phosphor that emits blue light (hereinafter referred to as a blue phosphor).

According to the present invention as described above, ultraviolet rays and short-wavelength visible light can be efficiently converted into long-wavelength visible light, and the converted visible light can be efficiently taken out of the apparatus. Moreover, according to this invention, the moisture resistance and heat dissipation of a light-emitting device can also be improved.

It is a typical longitudinal cross-sectional view of the light-emitting device which concerns on one Embodiment of this invention. It is a graph which shows the outline | summary of the transmittance | permeability and reflectance of the short wavelength transmission filter in the embodiment. It is a graph which shows the outline | summary of the transmittance | permeability and reflectance of the long wavelength transmission filter in the embodiment. It is an optical path explanatory view showing a part of the optical path of the light emitting device according to the embodiment. It is a typical longitudinal cross-sectional view of the light-emitting device which concerns on other embodiment. It is a typical longitudinal cross-sectional view of the light-emitting device which concerns on other embodiment. It is a typical longitudinal cross-sectional view of the light-emitting device which concerns on other embodiment. It is a graph which shows the outline | summary of the transmittance | permeability and reflectance of the long wavelength transmission filter in other embodiment. It is a typical top view of the wavelength conversion member in other embodiments. It is a typical longitudinal section of a wavelength conversion member in other embodiments.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

As shown in FIG. 1, the light emitting device 1 according to the present embodiment includes a base body 2 having a recess 22 that opens on an upper end surface 21, an LED element 3 mounted on a bottom surface 221 of the recess 22, and an LED element 3. A transparent member 4 to be sealed, and a short wavelength transmission filter 5, a wavelength conversion member 6, and a long wavelength transmission filter 7 laminated on the transparent member 4 in this order are provided.

Each part will be described in detail.
The base 2 has a recess 22 that opens to the upper end surface 21. For example, a base 2 is formed by molding an insulating material having high thermal conductivity such as alumina or aluminum nitride.

The base body 2 mounts an LED element 3 to be described later on the bottom surface 221 of the recess 22, and a wiring conductor (not shown) for electrically connecting the LED element 3 to the bottom surface 221. Is formed. This wiring conductor is led to the outer surface of the light emitting device 1 through a wiring layer (not shown) formed inside the base 2 and connected to the external electric circuit board, whereby the LED element 3 and the external electric circuit board are connected. Are electrically connected.

A step portion 23 is formed on the side surface 222 of the concave portion 22 of the base 2, and a short wavelength transmission filter 5 described later is disposed on the upper end surface of the step portion 23 so that the peripheral edge portion is placed. Thus, the short wavelength transmission filter 5 is configured to be positioned with respect to the base 2 both in the axial direction and in the axis orthogonal direction.

Furthermore, a metal thin film having a high reflectivity is formed on the inner surface including the side surface 222 and the bottom surface 221 of the recess 22 of the base 2 by applying metal plating such as silver, aluminum, gold, etc., and functions as a reflector. is doing. The ultraviolet or visible light reflected downward by a long wavelength transmission filter 7 described later and transmitted through the wavelength conversion member 6 and the short wavelength transmission filter 5 is reflected again toward the wavelength conversion member 6 by the metal thin film. be able to.

The LED element 3 emits ultraviolet rays or short-wavelength visible light, and has a radiation peak at 360 to 430 nm, for example. For example, the LED element 3 is formed by laminating a gallium nitride-based compound semiconductor in the order of an n-type layer, a light-emitting layer, and a p-type layer on a sapphire substrate or a gallium nitride substrate.

The LED element 3 is flip-chip mounted on the bottom surface 221 of the concave portion 22 using solder bumps, gold bumps (not shown) with the gallium nitride compound semiconductor facing down (the bottom surface 221 side of the concave portion 22).

The translucent member 4 is filled in the concave portion 22 and seals the LED element 3. For example, the translucent member 4 is made of a silicone resin having excellent translucency and heat resistance and having a small difference in refractive index from the LED element 3. It is. When such a translucent member 4 is provided, the light extraction efficiency from the LED element 3 can be improved, and thermal deterioration of the phosphor 61 can be prevented.

The short-wavelength transmission filter 5 is a low-pass filter that reflects visible light and selectively transmits only electromagnetic waves from the ultraviolet region to the near-ultraviolet region, and is provided on the translucent member 4. Is in close contact with the side surface 222 of the recess 22 and hermetically seals the interior of the recess 22. Specifically, for example, as shown in FIG. 2, the short wavelength transmission filter 5 is a dielectric multilayer film in which the transmittance and reflectance of electromagnetic waves are reversed with the vicinity of 430 nm as a boundary. Such a dielectric multilayer film is formed, for example, by attaching a film material to a glass substrate or the like.

The wavelength conversion member 6 contains a phosphor 61 inside and is provided on the short wavelength transmission filter 5. Examples of such a wavelength conversion member 6 include those in which the phosphor 61 is dispersed in a silicone resin that is excellent in translucency and heat resistance and has a small refractive index difference from the translucent member 4. In addition, the concave portion 22 may be filled with an uncured silicone resin in which the phosphor 61 is dispersed, or a sheet processed into a predetermined size may be used. .

The phosphor 61 contained in the wavelength conversion member 6 is not particularly limited, and examples thereof include a red phosphor, a green phosphor, a blue phosphor, and a yellow phosphor. Among these, when the red phosphor, the green phosphor, and the blue phosphor are used in combination, the light emitting device 1 that emits white light can be configured.

In a white light emitting device configured such that blue light is mixed with yellow light emitted from a yellow phosphor using an LED element that emits blue light, there is a difference in optical path length on the light emitting surface of the light emitting device. It is known that uneven color tone tends to occur. On the other hand, in the light-emitting device 1 according to the present embodiment, the phosphor 61 that uses a red phosphor, a green phosphor, and a blue phosphor in combination, ultraviolet rays emitted from the LED element 3 or visible light having a short wavelength. The red light, the green light, and the blue light emitted from each phosphor 61 excited by the light beam are mixed to emit white light. At this time, ultraviolet light and short wavelength visible light emitted from the LED element 3 are emitted from the light emitting device 1. Therefore, the above-described uneven color tone is unlikely to occur.

Then, the mixed light emitted from the light emitting device 1 using the LED element 3 that emits ultraviolet rays and visible light having a short wavelength and using the red phosphor, the green phosphor, and the blue phosphor as the phosphor 61 is on the Planck locus. The natural white color is very close to sunlight.

The long-wavelength transmission filter 7 is a high-pass filter that reflects electromagnetic waves in the ultraviolet region to the near-ultraviolet region and selectively transmits only visible light, and is provided on the wavelength conversion member 6, and the periphery thereof is a recess 22. The opening part of the recessed part 22 is covered so that the side surface 222 may be contacted. Specifically, for example, as shown in FIG. 3, the long wavelength transmission filter 7 is a dielectric multilayer film in which the reflectance and transmittance of electromagnetic waves are reversed with a vicinity of 430 nm as a boundary. Such a dielectric multilayer film is formed, for example, by attaching a film material to a glass substrate or the like.

In the light emitting device 1 according to such an embodiment, as shown in FIG. 4, the wavelength conversion member 6 containing the phosphor 61 is sandwiched between the short wavelength transmission filter 5 and the long wavelength transmission filter 7. Thus, the ultraviolet rays and the short wavelength visible light U transmitted through the wavelength conversion member 6 are reflected by the long wavelength transmission filter 7 and travel through the wavelength conversion member 6 again. For this reason, it is possible to improve the probability that ultraviolet rays or short-wavelength visible light U excites the phosphor 61 and is converted into longer-wavelength visible light V, thereby increasing the amount of light emission. On the other hand, among the visible light V emitted from the phosphor 61 excited by the ultraviolet light emitted from the LED element 3 or the visible light U having a short wavelength, the light traveling toward the substrate 2 is reflected by the short wavelength transmission filter 5. Then, the traveling direction is changed, the light travels toward the long wavelength transmission filter 7, passes through the filter 7, and is emitted outside the apparatus 1. Therefore, according to the light emitting device 1, the ultraviolet light or the short wavelength visible light U is efficiently converted into the long wavelength visible light V, and the converted visible light V is efficiently extracted outside the device 1. Can do.

Further, the wavelength conversion member 6 can be manufactured in a separate process as a separate body from the substrate 2 on which the LED element 3 is mounted, by potting application to the

filters

5 and 7, printing by die coating or inkjet method. is there. For this reason, management of the thickness of the wavelength conversion member 6 becomes easy. Further, using a reference light source having a predetermined wavelength and light intensity, the emission color, illuminance, and the like of the wavelength conversion member 6 are measured, and the wavelength conversion member 6 is classified and managed according to the result, and a desired emission color or Since the light emitting device 1 having the desired performance can be manufactured by selecting the one having the illuminance and the like and combining with the suitable LED element 3, the variation in the light emission color and the illuminance of the light emitting device 1 which is the final product can be reduced. It can be suppressed as much as possible.

Furthermore, since the visible light V traveling toward the substrate 2 is reflected by the short wavelength transmission filter 5, the visible light V reaching the substrate 2 is reduced, and the deterioration of the substrate 2 with time is suppressed. A change in emission color of the light emitting device 1 is also suppressed.

In the present invention, since the peripheral edges of the short wavelength transmission filter 5 and the long wavelength transmission filter 7 are in contact with the side surface 222 of the recess 22, the heat generated by the

filters

5 and 7 from the wavelength conversion member 6 and the LED element 3. Is transmitted to the substrate 2 to exhibit a heat dissipation effect, and the change in the emission color of the light-emitting device 1 due to the thermal deterioration of the phosphor in the wavelength conversion member 6 can be satisfactorily suppressed.

In particular, in the present embodiment, by using a dielectric multilayer film having excellent thermal conductivity as the short wavelength transmission filter 5 and the long wavelength transmission filter 7, the heat generated from the LED element 3 and the phosphor 61 can be efficiently used as a substrate. Therefore, it is possible to more effectively prevent thermal deterioration of the phosphor 61 and reduction in luminous efficiency and luminance.

Moreover, although the silicone resin which comprises the translucent member 4 and the wavelength conversion member 6 has high gas transmittance, in this embodiment, the short wavelength transmission filter 5 and the long wavelength transmission filter 7 are gas and water | moisture content in the recessed part 22. Therefore, the corrosion of the metal thin film formed on the inner surface of the recess 22 due to oxidation, sulfidation, chlorination, or the like can be prevented.

The present invention is not limited to the above embodiment.

For example, the light emitting device 1 is not limited to the one shown in FIG. 1 and is mounted on the upper end surface 21 of the base 2 so that the long wavelength transmission filter 7 covers the opening of the recess 22 as shown in FIG. Alternatively, as shown in FIG. 6, the short wavelength transmission filter 5 may be placed on the upper end surface 21 of the base 2 so as to cover the opening of the recess 22.

Further, as shown in FIG. 7, the long wavelength transmission filter 7 is placed on the upper end surface 21 of the base 2 so as to cover the opening of the concave portion 22, and the step portion 23 has a plurality of steps. The periphery of the short wavelength transmission filter 5 may be placed on the upper end surface, and the upper end surface of the upper stage may be in contact with the lower surface periphery of the wavelength conversion member 6. By adopting such a configuration, heat generated from the wavelength conversion member 6 can be more efficiently conducted and released directly or through the long wavelength transmission filter 7 and the short wavelength transmission filter 5 to the base 2. Therefore, the cooling efficiency of the light emitting device 1 can be increased.

Further, the long wavelength transmission filter 7 is not limited to the one having the optical characteristics as shown in FIG. 3 as long as the reflectance and transmittance of the electromagnetic wave are reversed around 430 nm as a boundary. It may have optical characteristics as shown and transmit some ultraviolet rays or visible light having a short wavelength. If it is such, when it is necessary to exhibit color rendering properties by violet light, or when it is necessary to improve the heat dissipation characteristics, ultraviolet rays or short wavelengths of light reflected by the long wavelength transmission filter 7 and absorbed by the base 2 are used. This is effective when it is necessary to reduce visible light and suppress deterioration of the substrate 2.

Furthermore, the wavelength conversion member 6 does not have to be uniformly dispersed of the phosphors 61 that emit light of different colors, and is provided with fluorescent regions that emit light of different colors. Also good. That is, for example, as shown in FIG. 9, a red fluorescent region R containing a red phosphor, a green fluorescent region G containing a green phosphor, and a blue fluorescent region B containing a blue phosphor are arranged side by side in the horizontal direction. If so, the blue light emitted from the blue phosphor and the green light emitted from the green phosphor are not absorbed by the other phosphors 61, so that the energy conversion efficiency and the light extraction efficiency can be improved. . As shown in FIG. 10, in the wavelength conversion member 6, the red fluorescent region R, the green fluorescent region G, and the blue fluorescent region B may be laminated in this order from the LED element 3 side.

Further, the LED element 3 may be connected to a wiring conductor provided on the base 2 using wire bonding.

Furthermore, the translucent member 4, the short wavelength transmission filter 5, the wavelength conversion member 6, and the long wavelength transmission filter 7 do not have to be in contact with each other, and a translucent heat dissipation member or the like is interposed therebetween. It may be. In addition, as the said translucent heat radiating member, what consists of material with high heat conductivity, such as quartz, sapphire, and diamond, was excellent in translucency. The translucent heat radiating member may be provided on the long wavelength transmission filter 7 to cover the opening of the recess 22.

In addition, the present invention is not limited to the above-described embodiments, and may be configured by appropriately combining some or all of the various configurations described above without departing from the spirit of the present invention.

According to the light-emitting device of the present invention, ultraviolet rays and short-wavelength visible light are efficiently converted into longer-wavelength visible light to increase the amount of light emission, and the converted visible light is efficiently converted into a device. Can be taken out. Moreover, according to the light-emitting device which concerns on this invention, the moisture resistance and heat dissipation of a light-emitting device can also be improved.

DESCRIPTION OF SYMBOLS 1 ... Light-emitting device 2 ... Base | substrate 3 ... LED element 4 ... Translucent member 5 ... Short wavelength transmission filter 6 ... Wavelength conversion member 7 ... Short wavelength transmission filter

Claims

A base body having a recess opening in the upper end surface;
An LED element mounted on the bottom surface of the recess and emitting visible light of ultraviolet or short wavelength;
A short wavelength transmission filter that transmits ultraviolet light and short wavelength visible light and reflects longer wavelength visible light, disposed in this order from the light emitting surface side of the LED element, a wavelength conversion member containing a phosphor, And a long wavelength transmission filter that transmits longer wavelength visible light and reflects ultraviolet light and shorter wavelength visible light, and
The light emitting device, wherein the short wavelength transmission filter is in close contact with the base so that the LED element is hermetically sealed in the recess.
The light-emitting device according to claim 1, wherein the LED element has a radiation peak at 490 nm or less.
The short wavelength transmission filter and the long wavelength transmission filter have a boundary where the level of the reflectance and transmittance of the electromagnetic wave is reversed in a wavelength region of 10 nm or more larger than the emission peak wavelength of the LED element and 500 nm or less. The light-emitting device according to claim 1, which is a dielectric multilayer film.
2. The light emitting device according to claim 1, wherein the phosphor is a phosphor that emits red light, a phosphor that emits green light, and a phosphor that emits blue light.