JP2014060283A - White light-emitting device, imaging device using the same, illuminating device and liquid crystal display device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light-emitting device capable of reducing fatigue of the eyes.SOLUTION: The light-emitting device includes: a light emitting device 15 that emits light in a region from ultraviolet to blue; a first fluorescent substance 13 that absorbs the light of the region from ultraviolet to blue from the light emitting device and emits light of cyan; a second fluorescent substance 14 that absorbs the light of the region from ultraviolet to blue from the light emitting device and emits light of red; and a sealing substance 12 covering the light emitting device.

Description

  The present invention relates to a white light emitting device. The present invention also relates to an imaging device, an illumination device, and a liquid crystal display device using the same.

  In recent years, white LEDs (Light Emitting Diodes) have been widely used from the viewpoint of energy saving.

  The current general white LED has a configuration in which a blue light emitting element (blue LED chip) and a phosphor are combined. In such a general white LED, a part of the light from the blue LED chip is color-converted by the phosphor, and the blue light from the blue LED chip and the light emitted from the phosphor are mixed to produce white light. ing. As a specific example, Patent Document 1 discloses a light emitting device in which a blue LED chip is molded with a resin containing a yellow phosphor. In the light emitting device, a part of light emitted from the blue LED chip is yellow fluorescent. The body absorbs and converts to yellow light, and the blue light from the blue LED chip and the yellow light from the yellow phosphor are mixed to produce white light.

  However, in such a white LED that combines a conventional blue light emitting element (LED chip) and a phosphor, eye fatigue such as eye strain is not considered, and eye fatigue such as eye strain is reduced. There was a need for a light emitting device.

Patent No. 3503139

  Accordingly, an object of the present invention is to provide a novel light emitting device capable of reducing eye fatigue.

The present invention comprises a light emitting element that emits light in the ultraviolet to blue region,
A first phosphor that absorbs ultraviolet to blue light from the light emitting element and emits light in cyan;
A second phosphor that absorbs ultraviolet to blue light from the light emitting element and emits red light;
A sealing body covering the light emitting element;
It is a light-emitting device containing.

  According to the light emitting device of the present disclosure, eye fatigue such as eye strain can be reduced.

It is typical sectional drawing which shows one Embodiment of the LED device of this invention. (A) to (d) is a figure which shows the manufacturing process of the LED device shown in FIG. It is typical sectional drawing which shows another one Embodiment of the LED device of this invention. It is typical sectional drawing which shows another one Embodiment of the LED device of this invention. It is typical sectional drawing which shows one Embodiment when the LED device of this invention is provided with a filter. It is typical sectional drawing which shows the LED device of the comparative examples 1 and 2. 2 is a transmission spectrum of a filter used in Example 2. 2 is an emission spectrum of Example 1. 2 is an emission spectrum of Example 2. 2 is an emission spectrum of Example 3. 6 is an emission spectrum of Example 4. 7 is an emission spectrum of Example 5. 2 is an emission spectrum of Comparative Example 1. 3 is an emission spectrum of Comparative Example 2. It is explanatory drawing which shows an example of a structure of a LED chip. It is explanatory drawing which shows an example of the imaging device concerning Embodiment 3 of this invention. It is explanatory drawing which shows an example of the illuminating device concerning Embodiment 4 of this invention. It is a general-view figure which shows an example of the liquid crystal display device concerning Embodiment 5 of this invention. It is explanatory drawing which shows an example of a structure of a liquid crystal display device.

  Hereinafter, the present invention will be described in detail with reference to specific embodiments. However, the present invention is naturally not limited to these embodiments, and may be appropriately modified without departing from the technical scope of the present invention. Can be implemented.

One embodiment of the present invention, a light emitting device that emits light in the ultraviolet to blue region,
A first phosphor that absorbs ultraviolet to blue light from the light emitting element and emits light in cyan;
A second phosphor that absorbs ultraviolet to blue light from the light emitting element and emits red light;
A sealing body covering the light emitting element;
It is a light-emitting device containing.

  In one mode of the embodiment, the light-emitting element has an emission peak wavelength in a range of 380 nm to 460 nm.

  In one aspect of the embodiment, the light-emitting element includes a light-emitting layer formed of a nitride semiconductor having a growth surface that is a nonpolar surface or a semipolar surface.

  In one aspect of the embodiment, the first phosphor absorbs light in the ultraviolet to blue region from the light emitting element and emits light having a maximum emission peak wavelength in a range from 480 nm to 520 nm.

  In one aspect of this embodiment, the second phosphor absorbs light in the ultraviolet to blue region from the light emitting element and emits light having a maximum emission peak wavelength from 590 nm to 670 nm.

  In one aspect of the embodiment, the ratio of the emission energy of 380 nm to 460 nm with respect to the emission energy of 380 nm to 830 nm in the emitted light from the light emitting device is 10% or less.

In one aspect of the embodiment, the first phosphor is a phosphor using Eu ²⁺ as the emission center, for example, M ₂ MgSi ₂ O ₇ : Eu ²⁺ (M = Ba, Sr and Ca A phosphor represented by a composition formula of at least one selected from:

  In one aspect of the embodiment, the light emitting device further includes a filter that absorbs at least part of light emission in an ultraviolet to blue region.

Another embodiment of the present invention provides a flashlight comprising the above light emitting device;
A lens on which reflected light from an object irradiated with light from the flashlight is incident;
It is an imaging device provided with.

  Yet another embodiment of the present invention is a lighting device including a light source unit including the light emitting device.

  Yet another embodiment of the present invention is a liquid crystal display device including a backlight including the light emitting device.

  Blue light is said to cause eye fatigue such as eye strain and the like. Further, since light becomes higher as the wavelength of light becomes shorter, it is considered to cause eye fatigue more easily.

  In the conventional white LED, white color is created by mixing the blue light from the LED chip and the light emitted from the phosphor, and therefore it is necessary to emit blue light that causes fatigue and the like from the light emitting device. For example, in the white LED of Patent Document 1, white light is obtained by mixing yellow light emitted from a yellow phosphor by absorbing blue light from a blue LED chip and blue light from a blue LED chip, and obtaining blue light. Blue light emitted from the chip has to be emitted from the light emitting device.

  In contrast, in the present invention, an LED chip that emits light in the ultraviolet to blue region, a phosphor that converts light in the ultraviolet to blue region into cyan light, and a phosphor that converts light in the ultraviolet to blue region into red light; Are used in combination. In the present invention, white light can be created only by the light components emitted by these two types of phosphors, so that the LED chip that emits light in the ultraviolet to blue region is used. The light in the blue region may not be emitted from the light emitting element.

  Therefore, according to the configuration of the present invention, it is possible to suppress the emission of light in the ultraviolet to blue region from the light emitting device as compared with the conventional case, thereby reducing eye fatigue and the burden on the retina, Eye diseases such as eye strain and age-related macular degeneration due to continued bathing can be suppressed.

  In addition, as described above, it is considered that the light becomes higher in energy as the wavelength becomes shorter and is likely to cause fatigue of the eyes. In the present invention, the light used to create white light is more than blue. Since the light has a long wavelength, it is more advantageous in suppressing eye fatigue than a white LED using a blue phosphor.

  Further, in the conventional white LED, it is necessary to emit the LED chip at a high output in order to emit blue light from the light emitting device. However, in the present invention, the LED chip does not emit light from the light emitting device. Therefore, it is considered advantageous in terms of energy consumption efficiency.

  In the present disclosure, white includes light bulb color, warm white, and daylight white.

(Embodiment 1)
Hereinafter, a light emitting device according to an embodiment of the present invention will be described by taking an LED device using an LED chip as a light source as an example.

  FIG. 1 is a schematic cross-sectional view showing an embodiment of an LED device according to the present invention. As shown in FIG. 1, the LED device 51 includes a support body 23, an LED chip 15, and an LED sealing body 12.

  The support body 23 supports the LED chip 15. In this embodiment, since the LED device 51 has a structure capable of surface mounting, the support 23 is a substrate. This embodiment can be used for a high-intensity LED device. The support 23 may have a high thermal conductivity so that heat generated in the LED chip 15 can be efficiently dissipated to the outside. For example, a ceramic substrate made of alumina or aluminum nitride can be used as the support 23.

  As the LED chip 15, one that emits light in the ultraviolet to blue region is used, for example, one having an emission peak wavelength in the range of 200 nm to 460 nm. Specifically, as the LED chip 15, a blue LED chip, a purple LED chip, a near ultraviolet LED chip, or the like is used. The light emission peak wavelength of the LED chip 15 may be, for example, in the range of 380 nm to 460 nm or in the range of 380 nm to 420 nm from the viewpoint of efficiently emitting the phosphor.

  The LED chip 15 is fixed to the support 23 with solder 27 or the like so that the emission surface 15a is on the support 23. The LED chip 15 is electrically connected to an electrode 22 provided on the support by a bonding wire 21.

  The LED chip 15 is covered with an LED sealing body 12, and a silicone resin is used for the LED sealing body 12. The first phosphor 13 and the second phosphor 14 are dispersed in the LED sealing body 12.

  As the silicone resin, a silicone resin having a structure defined by various chemical formulas used as a sealing resin for a semiconductor light emitting device can be used. The silicone resin contains, for example, dimethyl silicone having high discoloration resistance. Moreover, methylphenyl silicone etc. with high heat resistance can also be used as a silicone resin. The silicone resin may be a homopolymer having a main skeleton with a siloxane bond defined by one type of chemical formula, a copolymer containing a structural unit having a siloxane bond defined by two or more types of chemical formulas, or 2 It may be an alloy of more than one type of silicone polymer. In this specification, the silicone resin in the LED sealing body 12 is in a state after curing. Therefore, the LED sealing body 12 is also cured. As described below, the LED sealing body 12 can be manufactured using an uncured silicone resin. The silicone resin is generally a two-component type in which curing is accelerated by mixing a main agent and a curing agent. However, a thermosetting silicone resin or an energy curable silicone resin that cures when irradiated with energy such as light can also be used.

  In addition, the LED sealing body 12 may use things other than a silicone resin, and may use glass, an epoxy resin, or the like. The form in which the LED device 51 includes the phosphor 13 and the phosphor 14 is not limited to the above. For example, the phosphor 13 and the phosphor 14 may be arranged in the form of a phosphor plate on the LED sealing body 12 without being dispersed in the LED sealing body 12. In this case, the phosphor plate contains phosphor 13 and phosphor 14.

<Phosphor>
The phosphor 13 and the phosphor 14 absorb a part or all of the wavelength components in the ultraviolet to blue region light emitted from the LED chip 15 and emit fluorescence. The wavelength of light to be absorbed and the wavelength of fluorescence are determined by the type of fluorescent material contained in the phosphor 13 and the phosphor 14. For example, a blue LED chip, a purple LED chip or the like is used as the LED chip 15, and the phosphor 13 is M ₂ MgSi ₂ O ₇ : Eu ²⁺ (at least one selected from M = Ba, Sr and Ca) phosphor. Can be used. In this case, the phosphor 13 absorbs blue light, violet light, and the like emitted from the LED chip 15 and emits cyan fluorescence. As the phosphor 14, a CaAlSiN ₃ : Eu ²⁺ phosphor can be used. In this case, the phosphor 14 absorbs blue light, violet light, and the like emitted from the LED chip 15 and emits red fluorescence. Therefore, cyan and red fluorescence emitted from the phosphor 13 and the phosphor 14 are mixed, and white light is emitted from the LED device 51.

  For example, the phosphor 13 may have a maximum emission peak wavelength of 480 nm or more and 520 nm or less. Further, the phosphor 13 may have, for example, a light emission energy of 480 nm or more and 520 nm or less that is 35% or more of a light emission energy of 380 nm or more and 830 nm or less.

  For example, the phosphor 14 may have a maximum emission peak wavelength of 590 nm to 670 nm. In addition, for example, the phosphor 14 may have a light emission energy of 590 nm to 670 nm that is 45% or more of a light emission energy of 380 nm to 830 nm.

Examples of the phosphor 13 include M ₂ MgSi ₂ O ₇ : Eu ²⁺ (at least one selected from M = Ba, Sr and Ca), and, for example, SrSi ₅ AlO ₂ N ₇ : Eu ²⁺ , BaSi. ₂ O ₂ N ₂ : Eu ²⁺ , BaAl ₂ O ₄ : Eu ²⁺ , BaZrSi ₃ O ₉ : Eu ²⁺ , M ₂ SiO ₄ : Eu ²⁺ (M = at least one selected from Ba, Sr and Ca) ), M ₂ SiS ₄ : Eu ²⁺ (at least one selected from M = Ba, Sr and Ca), and the like, and a phosphor using Eu ²⁺ as the emission center can be used. _{Further, CaSi 12- (m + n)} Al (m + n) O n N 16-n: Ce 3+ can also be used.

As the phosphor 14, in addition to the CaAlSiN ₃ : Eu ²⁺ phosphor, for example, SrAlSi ₄ O ₇ : Eu ²⁺ , M ₂ Si ₅ N ₈ : Eu ²⁺ (M = Ba, Sr and Ca are selected at least) 1 type), MSiN ₂ : Eu ²⁺ (at least one selected from M = Ba, Sr and Ca), MSi ₂ O ₂ N ₂ : Yb ²⁺ (at least one selected from M = Ba, Sr and Ca) _{), Y 2 O 2 S:} Eu 3+, Sm 3+, La 2 O 2 S: Eu 3+, Sm 3+, CaWO 4: Li 1+, Eu 3+, Sm 3+, M 2 SiS 4: Eu ²⁺ (at least one selected from M = Ba, Sr and Ca), LaCuO _2−σ : Eu ³⁺ , Ba ²⁺ , and the like can be used.

  Moreover, the particle diameters of the phosphors 13 and 14 are, for example, 1 μm or more and 30 μm or less, respectively. Moreover, the fluorescent substance 13 and the fluorescent substance 14 are contained in the LED sealing body 12 in the ratio of 3 weight part or more and 70 weight part or less with respect to 100 weight part of sealing bodies, for example. This is because when the content of the phosphors 13 and 14 is less than 3 parts by weight, sufficient intensity of fluorescence cannot be obtained, and the LED device 51 that emits light of a desired wavelength may not be realized. The weight ratio between the phosphor 13 and the phosphor 14 can be appropriately determined according to the desired color tone of white light and the emission intensity of the phosphor 13 and the phosphor 14.

  The phosphor can be manufactured according to a known method.

  Specifically, when preparing an oxide phosphor, the raw material is a high purity (purity 99% or more) hydroxide, oxalate, nitrate, or the like, a compound that becomes an oxide upon firing, or a high purity ( An oxide having a purity of 99% or more can be used. Further, when producing an oxynitride phosphor and a nitride phosphor, high purity (purity 99% or more) nitride can be used in addition to the above-described raw materials.

  Here, in order to promote the reaction, a small amount of fluoride (aluminum fluoride or the like) or chloride (aluminum chloride or the like) can be added.

  The phosphor is produced by mixing and firing the above raw materials. The raw material may be mixed by wet mixing in a solution or dry mixing of a dry powder. A medium stirring mill, a planetary mill, a vibration mill, a jet mill, a V-type mixer, a stirrer, or the like can be used.

  The method for firing the mixed powder varies depending on the composition system of the phosphor. For example, the phosphor is fired in the air or in a reducing atmosphere at a temperature range of 1100 to 1500 ° C. for about 1 to 50 hours.

  The furnace used for firing may be an industrially used furnace, and a continuous or batch type electric furnace or gas furnace such as a pusher furnace may be used.

  The obtained phosphor powder is pulverized again using a ball mill, a jet mill or the like, and further washed or classified as necessary, thereby adjusting the particle size distribution and fluidity of the phosphor powder.

<LED chip>
In the example described above, the LED chip is wire-bonded, but the LED chip used in this embodiment may have another configuration. That is, the LED chip used in the present embodiment may be mounted face-up or mounted by flip chip. Moreover, the LED chip used in the present embodiment may include a light emitting layer formed of a nitride semiconductor having a general polar plane (c-plane) growth surface. Further, a growth surface of a nonpolar surface or a semipolar surface (m-plane, -r-plane, (20-21), (20-2-1), (10-1-3), (11-22) plane, etc.) The light emitting layer formed from the nitride semiconductor which has this may be provided. With an LED chip having a nonpolar plane or a semipolar plane as a growth plane, the influence of the piezoelectric field can be reduced and light with a wavelength of 380 nm to 460 nm (especially a wavelength of 380 nm to 420 nm) can be efficiently generated. Hereinafter, an LED chip including a light emitting layer formed of a nitride semiconductor having an m-plane as a growth surface will be described as an example.

FIG. 15 is an explanatory diagram showing an example of the configuration of the LED chip. The LED chip 15 used in this embodiment includes a substrate 401, an n-type layer 402, a light emitting layer 405, a p-type layer 407, an n-side electrode 408, and a p-side electrode 409. The substrate 401 is, for example, a GaN substrate whose main surface is an m-plane. As the substrate 401, an m-plane SiC substrate with an m-plane GaN layer formed on the surface, an r-plane sapphire substrate with an m-plane GaN layer formed thereon, or an m-plane sapphire substrate may be used. For example, the n-type layer 402 is provided on the substrate 401, and the light emitting layer 405 is disposed between the n-type layer 402 and the p-type layer 407. An undoped layer 406 may be provided between the light emitting layer 405 and the p-type layer 407. The n-type layer 402, the light emitting layer 405, the undoped layer 406, and the p-type layer 407 are, for example, gallium nitride-based compound semiconductor layers having an m-plane growth surface. The n-type layer 402 is, for example, an n-type Al _x Ga _y In _z N (0 ≦ x, y, z ≦ 1, x + y + z = 1) layer doped with Si. The light emitting layer 405 is, for example, a multiple quantum well active layer having a plurality of GaN barrier layers 403 and a plurality of InGaN well layers 404. The light emitting layer 405 may be a single quantum well active layer in which one InGaN well layer 404 is sandwiched between two GaN barrier layers 403. The p-type layer 407 is, for example, a p-type Al _l Ga _m In _n N (0 ≦ l, m, n ≦ 1, l + m + n = 1) layer doped with Mg. The n-side electrode 408 is provided in contact with the n-type layer 402. The p-side electrode 409 is provided in contact with the p-type layer 407.

  In the present specification, the “m-plane” refers to a plane inclined in any direction from the m-plane (m-plane when not inclined) within a range of ± 5 ° and a plurality of step-like m-plane regions. Including the face to have. The inclination angle is defined by the angle formed by the normal line of the growth surface of the light emitting layer 405 and the normal line of the m-plane. The absolute value of the inclination angle θ may be in the range of 5 ° or less or 1 ° or less in the c-axis direction. Further, it may be in the range of 5 ° or less or 1 ° or less in the a-axis direction. Even if there is such a slight inclination, a decrease in internal quantum efficiency due to a piezoelectric field can be sufficiently suppressed. Further, when the growth surface is slightly inclined from the m-plane, the growth surface is generally inclined from the m-plane, but microscopically has a step shape having a step height of 1 to several atoms. It is composed of a plurality of m-plane regions. Therefore, a nitride semiconductor having a growth surface that is a surface inclined at an angle of 5 ° or less from the m-plane or a surface having a plurality of m-plane steps is a nitride having an m-plane with no inclination as the growth surface. It is thought that it has the same property as a semiconductor.

Next, an example of the manufacturing method of the LED chip used in this embodiment will be described. First, before growing a nitride semiconductor, the substrate 401 is washed with a buffered hydrofluoric acid solution (BHF), and then sufficiently washed with water and dried. After cleaning, the substrate 401 is placed in the reaction chamber of the MOCVD apparatus so as not to be exposed to air as much as possible. Thereafter, the substrate surface is heated to approximately 850 ° C. while supplying gas such as ammonia (NH ₃ ), nitrogen, hydrogen, etc., and the substrate surface is cleaned.

The growth of the gallium nitride compound semiconductor layer is performed by, for example, MOCVD (Metal Organic Chemical Vapor Deposition). Trimethylgallium (TMG) or triethylgallium (TEG) and silane (SiH ₄ ) are supplied, and the substrate 401 is heated to about 1100 ° C. to deposit the n-type layer 402. Silane is a source gas for supplying Si, which is an n-type dopant. Next, the supply of SiH ₄ is stopped, the temperature of the substrate is lowered to less than 800 ° C., and the GaN barrier layer 403 is deposited. Further, supply of trimethylindium (TMI) is started to deposit an InGaN well layer 404. The light emitting layer 405 is formed by alternately depositing the GaN barrier layer 403 and the InGaN well layer 404 in two cycles or more. By setting it to two cycles or more, it is possible to prevent the carrier density inside the well layer from becoming excessively large during a large current drive, and to reduce the number of overflowing carriers. The InGaN well layer 404 may be deposited by adjusting the growth time so that the thickness becomes 3 nm or more and 20 nm or less. Furthermore, since the influence of the piezoelectric field can be suppressed by the m-plane growth, the thickness of the well layer can be 6 nm or more. Thereby, the droop of luminous efficiency can be reduced. Further, when the thickness is 20 nm or less, the InGaN well layer can be formed uniformly. Further, the deposition may be performed by adjusting the growth time so that the thickness of the GaN barrier layer 403 is 6 nm or more and 40 nm or less. When the thickness is 6 nm or more, a barrier to the InGaN well layer 404 can be more reliably formed. Further, when the thickness is 40 nm or less, the operating voltage can be lowered. By adjusting the amount of In in the InGaN well layer 404, a desired emission wavelength of 380 nm to 460 nm can be set.

Next, an undoped GaN layer having a thickness of, for example, 30 nm is deposited on the light emitting layer 405 as the undoped layer 406. Next, a p-type layer 407 is formed on the undoped layer 406. The p-type layer 407 is formed by supplying TMG, NH ₃ , TMA, TMI and Cp ₂ Mg (cyclopentadienyl magnesium) as a p-type impurity material. The p-type layer 407 includes, for example, a p-Al _0.14 Ga _0.86 N layer having a thickness of about 50 nm and a p-GaN layer having a thickness of about 100 nm. The upper part of the p-type layer 407 may be a contact layer with an increased Mg concentration.

  Thereafter, by performing chlorine-based dry etching, a part of the p-type layer 407, the undoped layer 406, the active layer 405, and the n-type layer 402 is removed to form a recess, and the n-type layer 402 is exposed. Next, the n-side electrode 408 is formed at the bottom of the recess. Further, a p-side electrode 409 is formed on the p-type layer 407.

<Manufacturing method of LED device>
Next, although an example of the manufacturing method of the LED device 51 is demonstrated, the manufacturing method of the LED device 51 is not restricted to the following.

  An uncured LED sealing resin mixture is prepared by dispersing phosphor 13 and phosphor 14 in an uncured silicone resin. Under the present circumstances, when the silicone resin to be used is a type which hardens | cures by mixing 2 liquids, an uncured silicone resin contains A liquid and B liquid.

  Next, as shown in FIG. 2A, an uncured LED sealing resin mixture 17 is filled in a mold 9 having a desired shape. When bubbles or the like are generated in the uncured LED sealing resin mixture 17, defoaming is performed using a vacuum defoaming device or the like as necessary. Further, as shown in FIG. 2B, the LED chip 15 is fixed to the support 23 with solder 27 or the like so that the emission surface 15a faces upward, and the electrode 22 and the LED chip 15 are connected by the bonding wire 21. To do. Thereafter, the support 23 is placed on the mold 9 so that the LED chip 15 is embedded in the uncured LED sealing resin mixture 17 in the mold 9, and the LED sealing resin mixture 17 is cured. For example, as shown in FIG. 2 (c), after the LED sealing resin mixture 17 is heated and temporarily cured with the mold 9 attached, the mold 9 is removed, and the LED sealing resin mixture 17 is further removed. Harden. Thereby, at least the emission surface 15a of the LED chip 15 is covered with the LED sealing body 12, and the LED device 51 in which the phosphors 13 and 14 are dispersed in the LED sealing body 12 is completed.

  As described above, according to the present embodiment, white light is generated using the phosphor 13 that emits cyan and the phosphor 14 that emits red, so that the ultraviolet to blue light from the LED device 51 is emitted. The emission can be suppressed as compared with the conventional case, and eye fatigue or the like can be reduced. In particular, in the light emitted from the LED device 51, the ratio of the emission energy of 380 nm to 460 nm to the emission energy of 380 nm to 830 nm can be set to 10% or less.

(Embodiment 2)
The LED device according to Embodiment 2 of the present invention is obtained by adding a filter that absorbs at least a part of light emitted from the ultraviolet to blue regions of the LED chip to the LED device according to Embodiment 1 described above. FIG. 5 is an explanatory diagram illustrating a configuration of the LED device 61 according to the second embodiment. About the same structure as Embodiment 1, the same code | symbol is attached | subjected and description is abbreviate | omitted and only a different part is demonstrated. The LED device 61 according to the second embodiment is obtained by providing the filter 31 so as to cover the LED sealing body 12 in the LED device 51 according to the first embodiment.

  The filter 31 may be, for example, a single layer or multiple layer filter having a light absorption layer, and the light absorption layer has a configuration in which a light absorption material is dispersed in, for example, a matrix (eg, glass, resin). In addition, the filter 31 has, for example, an average transmittance of 380 nm or more and 460 nm or less of 65% or less.

  The position of the filter 31 is not limited to the LED sealing body 12 and may be provided in another place. For example, you may provide on the light emission surface of the apparatus which arranged the LED device 51 of Embodiment 1 in multiple numbers.

  According to the present embodiment, the filter 31 can remove excess light in the ultraviolet to blue region from the LED chip 15 that is not absorbed by the phosphors 13 and 14, thereby further reducing eye fatigue and the like. it can.

  The structure of the LED device described in the first and second embodiments is an example. The LED device of the present embodiment may have a structure other than the structures shown in FIGS. For example, as shown in FIG. 3, in addition to the structure shown in FIG. 5, the LED device has a reflecting mirror 41 provided around the LED chip 15 to emit light from the LED chip 15 in a predetermined light collection state. May be provided. Moreover, you may provide the transparent resin 24 provided with the lens function for adjusting the condensing state of emitted light on the surface of the LED sealing body 12. FIG.

  In the LED device of the above embodiment, the LED chip 15 is supported by a substrate-like support. However, the LED device of the present embodiment may be an LED device in which an LED chip is supported by a lead frame. Specifically, the LED device shown in FIG. 4 includes a lead frame 42a and a lead frame 42b, which are supports provided with a recess 42c. The LED chip 15 is fixed to the bottom of the recess 42c of the lead frame 42a. The side surface of the recess 42c functions as a reflecting mirror. The LED sealing body 12 in which the phosphors 13 and 14 are dispersed is provided so as to fill the recess 42c. The LED chip 15 is electrically connected to the lead frames 42a and 42b by the bonding wires 21. Further, the entire upper portion including the recess 42c of the lead frame 42a is sealed with a transparent resin 24 having a shell shape.

(Embodiment 3)
The LED devices of Embodiments 1 and 2 can be used for an imaging device. FIG. 16 is an explanatory diagram illustrating an example of an imaging apparatus according to the third embodiment of the present invention. An imaging apparatus 600 according to the third embodiment includes a lens 601 and a flashlight 602. The imaging device 600 is, for example, a digital camera, a mobile phone, a smartphone, or the like. The flashlight 602 includes the LED device 51 described above. Reflected light from the object irradiated with light from the flashlight 602 is incident on the lens 601. The incident reflected light is photoelectrically converted by the image sensor of the imaging device 600, for example. An electrical signal from the image sensor is recorded as image data in a recording device such as a semiconductor memory element.

(Embodiment 4)
The LED device of Embodiments 1 and 2 can be used for a lighting device. FIG. 17 is an explanatory diagram illustrating an example of a lighting apparatus according to the fourth embodiment of the present invention. The illumination device 700 according to the fourth embodiment includes a light source unit 701. Illumination device 700 is, for example, a spotlight, a ceiling light, an automobile headlight, or the like. The light source unit 701 includes the LED device 51 described above. According to the configuration of the present embodiment, it is possible to provide a high-quality optical space according to the application.

(Embodiment 5)
The LED devices of Embodiments 1 and 2 can be used for a liquid crystal display device. FIG. 18 is a schematic view of a liquid crystal display device 800 according to the fifth embodiment of the present invention. The liquid crystal display device 800 is, for example, a personal computer (PC) monitor, a notebook personal computer, a television, a personal digital assistant (PDA), a smartphone, a tablet PC, or a mobile phone.

  FIG. 19 is an explanatory diagram showing a configuration of the liquid crystal display device 800. The liquid crystal display device 800 may be an edge light type, a direct type, or another configuration. Here, the edge light type will be described as an example. The liquid crystal display device 800 includes, for example, backlights 801 and 802 including a plurality of LED devices 51, a reflection plate 803 that reflects light from the backlight, a light guide plate 804 that guides light reflected by the reflection plate 803, And a liquid crystal panel 805 that displays an image using light from the light guide plate 804.

  According to the configuration of this embodiment, even when the screen of the liquid crystal display device is viewed for a long time, the light emitted from the ultraviolet region to the blue region from the LED device is reduced, thereby reducing eye fatigue such as eye strain. be able to.

  EXAMPLES Hereinafter, although an Example and a comparative example are given and this invention is demonstrated in detail, this invention is not limited to these Examples.

<Evaluation method>
The CIE chromaticity coordinates and emission spectra of the LED devices obtained in the following examples and comparative examples were measured using a photometric / colorimetric device (manufactured by Hamamatsu Photonics). The emission ratio of blue (380 nm to 460 nm) was determined from the ratio of the emission energy of 380 nm to 460 nm with respect to the emission energy of 380 nm to 830 nm.

[Example 1]
<Preparation of phosphor sample>
A method for manufacturing the phosphor used for the first phosphor is described below. BaCO ₃ , MgO, SiO ₂ and Eu ₂ O ₃ were used as starting materials, and these were weighed to a predetermined amount and mixed for 30 minutes at a rotational speed of 200 rpm using a planetary ball mill. Water or ethanol was used as the solvent. This mixed solution is sufficiently dried, and the dried powder is baked at 1100 ° C. to 1400 ° C. for 4 hours in a mixed gas of H ₂ 2% · N ₂ 98% to obtain Ba ₂ MgSi ₂ O ₇ : Eu ^2+. (BMS) A cyan phosphor was obtained. A commercially available CaAlSiN ₃ : Eu ²⁺ (CASN) red phosphor was used as the second phosphor.

<Production of LED device>
Next, 5 g of dimethyl silicone resin (Shin-Etsu Chemical KER-2600) A, 5 g of B, 5.15 g of the first phosphor and 3.04 g of the second phosphor were weighed, and the mortar Then, the mixture was passed through a three-roll kneader (EXAKT M50) five times to obtain an uncured LED sealing resin mixture.

  Thereafter, this uncured LED encapsulating resin mixture was defoamed with a vacuum defoaming device (manufactured by Nidec Anelva) for 5 minutes, then placed on an LED chip having a peak wavelength at 405 nm, and cured at 150 ° C. for 30 minutes. The LED device as shown in FIG. 1 was completed. An emission spectrum of the device manufactured by the above-described method is shown in FIG. Table 1 shows the CIE chromaticity coordinate values and the emission ratio of blue (380 nm to 460 nm).

[Example 2]
A filter (SCF-50S-44Y manufactured by Sigma Koki Co., Ltd.) was installed on the light emitting surface of the LED device produced in Example 1, and the LED device as shown in FIG. 5 was completed. The transmission spectrum of the filter used is shown in FIG. FIG. 9 shows an emission spectrum of the device manufactured by the above method. Table 1 shows the CIE chromaticity coordinate values and the emission ratio of blue (380 nm to 460 nm).

[Example 3]
<Preparation of phosphor sample>
A method for manufacturing the phosphor used for the first phosphor is described below. BaCO ₃ , CaCO ₃ , MgO, SiO ₂ , and Eu ₂ O ₃ were used as starting materials, and these were weighed to a predetermined amount and mixed at a rotational speed of 200 rpm for 30 minutes using a planetary ball mill. Water or ethanol was used as the solvent. This mixed solution is sufficiently dried, and the dried powder is fired at 1100 ° C. to 1400 ° C. for 4 hours in a mixed gas of 2% H ₂ and 98% N ₂ (Ba, Ca) ₂ MgSi ₂ O _7. : Eu ²⁺ (BCMS) cyan phosphor was obtained. A commercially available CaAlSiN ₃ : Eu ²⁺ (CASN) red phosphor was used as the second phosphor.

<Production of LED device>
Next, 5 g of dimethyl silicone resin (Shin-Etsu Chemical KER-2600) A, 5 g of B, 5.15 g of the first phosphor and 3.04 g of the second phosphor were weighed, and the mortar Then, the mixture was passed through a three-roll kneader (EXAKT M50) five times to obtain an uncured LED sealing resin mixture.

  Thereafter, this uncured LED encapsulating resin mixture was defoamed with a vacuum defoaming device (manufactured by Nidec Anelva) for 5 minutes, then placed on an LED chip having a peak wavelength at 405 nm, and cured at 150 ° C. for 30 minutes. The LED device as shown in FIG. 1 was completed. FIG. 10 shows an emission spectrum of the device manufactured by the above method. Table 1 shows the CIE chromaticity coordinate values and the emission ratio of blue (380 nm to 460 nm).

[Example 4]
<Preparation of phosphor sample>
A method for manufacturing the phosphor used for the first phosphor is described below. BaCO ₃ , MgO, SiO ₂ and Eu ₂ O ₃ were used as starting materials, and these were weighed to a predetermined amount and mixed for 30 minutes at a rotational speed of 200 rpm using a planetary ball mill. Water or ethanol was used as the solvent. This mixed solution is sufficiently dried, and the dried powder is baked at 1200 ° C. to 1500 ° C. for 4 hours in a mixed gas of H ₂ 2% and N ₂ 98% to obtain Ba ₂ MgSi ₂ O ₇ : Eu ^2+. (BMS) A cyan phosphor was obtained. A commercially available 3.5MgO.0.5MgF ₂ .GeO ₂ : Mn ⁴⁺ (MFG) red phosphor was used as the second phosphor.

<Production of LED device>
Next, dimethylsilicone resin (manufactured by Shin-Etsu Chemical Co., Ltd., KER-2600) Weighed 5 g of agent A, 5 g of agent B, 3.85 g of the first phosphor, and 4.34 g of the second phosphor, and mortar Then, the mixture was passed through a three-roll kneader (EXAKT M50) five times to obtain an uncured LED sealing resin mixture.

  Thereafter, this uncured LED encapsulating resin mixture was defoamed with a vacuum defoaming device (manufactured by Nidec Anelva) for 5 minutes, then placed on an LED chip having a peak wavelength at 405 nm, and cured at 150 ° C. for 30 minutes. The LED device as shown in FIG. 1 was completed. An emission spectrum of the device manufactured by the above-described method is shown in FIG. Table 1 shows the CIE chromaticity coordinate values and the emission ratio of blue (380 nm to 460 nm).

[Example 5]
<Preparation of phosphor sample>
A method for manufacturing the phosphor used for the first phosphor is described below. BaCO ₃ , SiO ₂ , Si ₃ N ₄ and Eu ₂ O ₃ were used as starting materials. These were weighed to a predetermined amount and mixed for 30 minutes at a rotational speed of 200 rpm using a planetary ball mill. Water or ethanol was used as the solvent. This mixed solution is sufficiently dried, and the dried powder is baked at 1200 ° C. to 1500 ° C. for 4 hours in a mixed gas of H ₂ 2% · N ₂ 98%, thereby BaBa ₂ O ₂ N ₂ : Eu ^2+. A (BaSiON) cyan phosphor was obtained. A commercially available CaAlSiN ₃ : Eu ²⁺ (CASN) red phosphor was used as the second phosphor.

<Production of LED device>
Next, 5 g of dimethyl silicone resin (Shin-Etsu Chemical KER-2600) A, 5 g of B, 4.83 g of the first phosphor, and 3.35 g of the second phosphor were weighed, and the mortar Then, the mixture was passed through a three-roll kneader (EXAKT M50) five times to obtain an uncured LED sealing resin mixture.

  Thereafter, this uncured LED encapsulating resin mixture was defoamed with a vacuum defoaming device (manufactured by Nidec Anelva) for 5 minutes, then placed on an LED chip having a peak wavelength at 405 nm, and cured at 150 ° C. for 30 minutes. The LED device as shown in FIG. 1 was completed. FIG. 12 shows an emission spectrum of the device manufactured by the above method. Table 1 shows the CIE chromaticity coordinate values and the emission ratio of blue (380 nm to 460 nm).

[Comparative Example 1]
A commercially available Y ₃ Al ₅ O ₁₂ : Ce ³⁺ (YAG) yellow phosphor is used as the phosphor, 5 g of dimethyl silicone resin (Shin-Etsu Chemical KER-2600) A, 5 g of B agent, and phosphor 16 After weighing in an amount of 8.18 g and mixing in a mortar, the mixture was passed 5 times through a three-roll kneader (EXAKT M50) to obtain an uncured LED encapsulating resin mixture.

  Thereafter, this uncured LED encapsulating resin mixture was defoamed for 5 minutes with a vacuum defoaming device (manufactured by Nidec Denerva), then placed on an LED chip having a peak wavelength at 445 nm, and cured at 150 ° C. for 30 minutes. The LED device shown in FIG. 6 was completed (reference numeral 16 represents a phosphor). FIG. 13 shows an emission spectrum of the device manufactured by the above method. Table 1 shows the CIE chromaticity coordinate values and the emission ratio of blue (380 nm to 460 nm).

[Comparative Example 2]
Commercially available BaMgAl ₁₀ O ₁₇ : Eu ²⁺ (BAM) blue phosphor, β-SiAlON: Eu ²⁺ (SiAlON) green phosphor, and commercially available CaAlSiN ₃ : Eu ²⁺ (CASN) red Using a phosphor, weighed 5 g of dimethyl silicone resin (Shin-Etsu Chemical KER-2600) A, 5 g of B, 0.74 g of BAM, 2.21 g of SiAlON, and 5.24 g of CASN, After mixing in a mortar, the mixture was passed 5 times through a three-roll kneader (EXAKT M50) to obtain an uncured LED sealing resin mixture.

  Thereafter, this uncured LED encapsulating resin mixture was defoamed with a vacuum defoaming device (manufactured by Nidec Anelva) for 5 minutes, then placed on an LED chip having a peak wavelength at 405 nm, and cured at 150 ° C. for 30 minutes. The LED device shown in FIG. 6 was completed (reference numeral 16 represents a phosphor). FIG. 14 shows an emission spectrum of the device manufactured by the above method. Table 1 shows the CIE chromaticity coordinate values and the emission ratio of blue (380 nm to 460 nm).

  As is clear from Table 1, it can be seen that the blue light emission ratio is 10% or less in all the samples prepared in the examples. Further, as is clear from Example 2, it can be seen that the blue light emission ratio can be further reduced by using the filter.

  Embodiments of the present invention include, for example, lighting devices such as spotlights, ceiling lights, and automobile headlights, imaging devices such as digital cameras, mobile phones, and smartphones, monitors for personal computers (PCs), notebook personal computers, It can be used for liquid crystal display devices such as televisions, personal digital assistants (PDAs), smartphones, tablet PCs, and mobile phones.

DESCRIPTION OF SYMBOLS 9 Mold 12 LED sealing body 13 1st fluorescent substance 14 2nd fluorescent substance 15 LED chip 17 LED sealing resin mixture 21 Bonding wire 22 Electrode 23 Support body 24 Transparent resin 31 Filter 41 Reflective mirror 51, 61 LED apparatus

Claims (12)

A light emitting element emitting light in the ultraviolet to blue region;
A first phosphor that absorbs ultraviolet to blue light from the light emitting element and emits light in cyan;
A second phosphor that absorbs ultraviolet to blue light from the light emitting element and emits red light;
A sealing body covering the light emitting element;
Including a light emitting device.   The light emitting device according to claim 1, wherein the light emitting element has an emission peak wavelength in a range of 380 nm to 460 nm.   The light emitting device according to claim 2, wherein the light emitting element includes a light emitting layer formed of a nitride semiconductor having a growth surface that is a nonpolar surface or a semipolar surface.   The said 1st fluorescent substance absorbs the light of the ultraviolet region from the said light emitting element, and emits the light which has the largest light emission peak wavelength in 480 nm or more and 520 nm or less. Light emitting device.   The second phosphor according to any one of claims 1 to 4, wherein the second phosphor absorbs light in an ultraviolet to blue region from the light emitting element and emits light having a maximum emission peak wavelength in a range from 590 nm to 670 nm. Light emitting device.   6. The light emitting device according to claim 1, wherein in the light emitted from the light emitting device, a ratio of light emission energy of 380 nm to 460 nm to light emission energy of 380 nm to 830 nm is 10% or less. The light emitting device according to any one of claims 1 to 6, wherein the first phosphor is a phosphor using Eu ²⁺ as an emission center. 8. The phosphor according to claim 1, wherein the first phosphor is a phosphor represented by a composition formula of M ₂ MgSi ₂ O ₇ : Eu ²⁺ (at least one selected from M = Ba, Sr and Ca). The light emitting device according to any one of the above.   The light emitting device according to any one of claims 1 to 8, further comprising a filter that absorbs at least a part of light emitted in an ultraviolet to blue region of the light emitting element. A flashlight comprising the light emitting device according to any one of claims 1 to 9,
A lens on which reflected light from an object irradiated with light from the flashlight is incident;
An imaging apparatus comprising:   A lighting device comprising a light source unit comprising the light emitting device according to claim 1.   A liquid crystal display device comprising a backlight including the light emitting device according to claim 1.

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