JP2014060328A - Light-emitting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light-emitting device having high efficiency and excellent color rendering properties of emitted light, and capable of suppressing an amount of red phosphors to be used.SOLUTION: A light-emitting device comprises: a light-emitting element; a first resin layer which comes into contact with the light-emitting element, is disposed so as to cover the light-emitting element, and includes a red phosphor; and a second resin layer disposed outside and apart from the first resin layer and includes a phosphor having a shorter emission peak wavelength than the red phosphor.

Description

  The present invention relates to a light emitting device, and more particularly to a light emitting device including a light emitting element and a phosphor.

  2. Description of the Related Art Generally, light emitting devices using light emitting elements such as light emitting diodes (LEDs) and laser diodes (LDs) are known to be small, power efficient, and emit bright colors. . The light-emitting element used in this light-emitting device has a feature that the life of the light-emitting device is long because there is little fear of a ball breakage and high durability against repeated vibration and on / off lighting. Further, in addition to this, it has a feature of excellent initial drive characteristics. Because of such excellent characteristics, light-emitting devices using light-emitting elements are widely used as various light sources such as LED bulbs, LED fluorescent lamps, lighting fixtures such as ceiling lights, and displays.

The spectrum of light emitted from these light emitting elements generally has a peak in a narrow wavelength range. On the other hand, light emitted from a light emitting device used for a lighting fixture or the like is often required to have high color rendering properties, and is required to have a relatively broad spectrum, such as white light.
For this reason, in such applications, many light-emitting devices using light-emitting elements are a mixture of two or more types of phosphors such as a red phosphor and a blue-green to green phosphor or a yellow-green to yellow phosphor. The phosphor-containing layer is included in the state. These phosphors absorb light from the light emitting element and emit light converted to different wavelengths (different colors). As a result, light emitted from the light-emitting element and passed through the phosphor-containing layer without being absorbed by the phosphor, and light emitted from the phosphor-containing layer after being converted by the first phosphor (for example, red phosphor) , Light converted by the second phosphor (a different type of phosphor from the first phosphor, for example, blue-green to green phosphor or yellow-green to yellow phosphor) (converted by the first phosphor) Light of a wide spectrum is obtained by mixing light having a wavelength different from that of light.

  Generally, two or more kinds of phosphors are contained in a resin, and a phosphor-containing layer in contact with the light emitting element is formed by placing a resin containing the phosphor around the light emitting element and then curing the resin. In addition, a bullet-type or surface-mount type light emitting device is often used.

However, depending on the type of phosphor, its characteristics may deteriorate when held at a high temperature for a long time. That is, in a mold-type light emitting element in which the phosphor-containing layer and the light emitting element are in contact, the temperature of the phosphor may increase due to heat generation of the light emitting element, and the light emission efficiency may decrease.
Moreover, in the conventional light-emitting device using the phosphor-containing layer that is included in a state where two types of phosphors are mixed, among the two types of phosphors, the phosphor that emits light (converted light) has a long wavelength side. The absorption spectrum overlaps with the emission spectrum of the phosphor having a short wavelength side, so that the short wavelength side light is absorbed by the long wavelength side phosphor and the light emission efficiency and the color rendering are lowered.

  Therefore, in order to avoid such a problem, for example, as shown in Patent Document 1, a red phosphor layer (on the side close to the light emitting element) (on the side close to the light emitting element) inside the transmission window (film) arranged away from the light emitting element 2. Description of the Related Art A light emitting device in which a light emitting material layer) is formed and a yellowish green to yellow phosphor layer is formed outside a transmission window is known.

Special table 2011-528490 gazette

  However, in the light emitting device of Patent Document 1, it is necessary for light emitted from the light emitting element to pass through a three-layer structure (three solid layers) including a red phosphor layer, a transmission window, and a yellow-green to yellow phosphor layer. is there. When passing through each solid layer, a part of the light entering the respective solid layer is reflected on the surface. The amount of light reflected in this way increases as the number of solid layers that pass through increases, and the light that can be extracted as a light-emitting device decreases.

  The present invention meets these requirements. That is, an object of the present invention is to provide a light-emitting device having high luminous efficiency, excellent color rendering properties of emitted light, and a reduced amount of red phosphor to be used.

  According to a first aspect of the present invention, there is provided a light-emitting element, a first resin layer including a red phosphor disposed in contact with the light-emitting element and covering the light-emitting element, and the first resin. And a second resin layer including a phosphor having an emission peak wavelength shorter than that of the red phosphor, which is disposed outside the layer and spaced apart from the first resin layer. is there.

  A second aspect according to the present invention is the light emitting device according to aspect 1, wherein an air layer is formed between the first resin layer and the second resin layer.

  According to a third aspect of the present invention, in the first aspect, a resin layer that does not substantially contain a phosphor is formed between the first resin layer and the second resin layer. It is a light-emitting device of description.

  A fourth aspect according to the present invention is the light emitting device according to any one of aspects 1 to 3, wherein a peak wavelength of light emitted from the light emitting element is 420 nm to 490 nm.

In a fifth aspect of the present invention, the phosphor having an emission peak wavelength shorter than that of the red phosphor includes a blue-green to green phosphor, and the blue-green to green phosphor is Ca ₈ MgSi ₄ O ₁₆ C. _{l2: Eu, (Si, Al} ) 6 (N, O) 8: Eu, BaSi 2 O 2 N 2: Eu, (Ba, Sr) 2 SiO 4: Eu, Sr 4 Al 14 O 25: Eu, SrAl 2 The light emission according to any one of aspects 1 to 4, comprising at least one selected from the group consisting of O ₄ : Eu, SrGa ₂ S ₄ : Eu and Ba ₃ Si ₆ N ₂ O ₁₂ : Eu. Device.

In a sixth aspect of the present invention, the phosphor having an emission peak wavelength shorter than that of the red phosphor includes a yellowish green to yellow phosphor, and the yellowish green to yellow phosphor is (Y, Lu, Gd, Tb) ₃ (Al, Ga) ₅ O ₁₂ : Ce, (Sr, Ba) ₂ SiO ₄ : Eu, (Ca, Sr) Si ₂ O ₂ N ₂ : Eu, La ₃ Si ₆ N ₁₁ : Ce, Ca ₃ It includes at least one selected from the group consisting of Sc ₂ Si ₃ O ₁₂ : Ce, CaSc ₂ O ₄ : Ce, (Sr, Ca, Ba) Ga ₂ S ₄ : Eu and ZnS: Cu. It is a light-emitting device in any one of aspect 1-5.

According to a seventh aspect of the present invention, in the red phosphor, the (Ca, Sr) AlSiN ₃ : Eu, (Ca, Sr) ₂ Si ₅ N ₈ : Eu, CaSiN ₂ : Eu, (Ca, Sr) S And at least one selected from the group consisting of: Eu, K ₂ SiF ₆ : Mn, LiEuW ₂ O ₈ and Ca _X (Si, Al) ₁₂ (N, O) ₁₆ : Eu It is a light-emitting device in any one of -6.

In the light-emitting device according to the present invention, the first resin layer containing a red phosphor that has excellent heat resistance and is unlikely to cause a decrease in light emission efficiency due to heat is disposed so as to contact the light-emitting element and cover the light-emitting element.
On the other hand, the second resin layer containing a phosphor having a shorter emission peak wavelength than the red phosphor, which is easily affected by heat and whose emission efficiency is likely to decrease as the temperature rises, is disposed outside the first resin layer (light emitting element). In a direction away from the first resin layer). For this reason, the phosphor contained in the second resin layer (a phosphor having a shorter emission wavelength than that of the red phosphor) is hardly affected by the heat generated by the light emitting element, and the decrease in the light emission efficiency can be suppressed. The light emitted from the light emitting element only needs to pass through the two solid layers of the first resin layer and the second resin layer. For this reason, the light-emitting device which concerns on this invention can obtain high luminous efficiency and high color rendering property.

  As a result, the present invention can provide a light-emitting device that has high efficiency, emits light with excellent color rendering, and suppresses the amount of red phosphor used.

FIG. 1 is a schematic cross-sectional view of a light emitting device 100 according to the present invention. FIG. 2 is a schematic cross-sectional view of a light emitting device 100A according to Modification 1 of the present invention. FIG. 3A is a schematic perspective view of a light emitting device 100C according to Modification 2 of the present invention, and FIG. 3B is a schematic cross-sectional view of the light emitting device 100C. 4A is a schematic perspective view of a light emitting device 100D according to Modification 3 of the present invention, and FIG. 4B is a schematic cross-sectional view taken along line IVb-IVb in FIG. .

  Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the following description, terms indicating a specific direction and position (for example, “up”, “down”, “right”, “left” and other terms including those terms) are used as necessary. These terms are used for easy understanding of the invention with reference to the drawings, and the technical scope of the present invention is not limited by the meaning of these terms. Moreover, the part of the same code | symbol appearing in several drawing shows the same or corresponding part or member.

  The inventors of the present application have excellent heat resistance, and the characteristics of the red phosphor and the temperature characteristics are poor even when heated by the heat generated by the light-emitting element, and the temperature characteristics are poor. The light emitting device of the present invention has been achieved by considering the characteristics of phosphors having a shorter emission peak wavelength than phosphors (for example, blue-green to green phosphors and yellow-green to yellow phosphors).

FIG. 1 is a cross-sectional view of a light emitting device 100 according to the present invention.
The light emitting device 100 includes a light emitting element 12, a first resin layer 8 including a first phosphor 10 that is a red phosphor, and a second phosphor 20 having an emission peak wavelength shorter than the peak wavelength of the red phosphor. And a second resin layer 18 containing.

The first resin layer 8 is disposed so as to contact the light emitting element 12 and cover the light emitting element 12. Thereby, the red phosphor (first phosphor) 10 can be disposed in the vicinity of the light emitting element 12 (for example, a region within 10 mm from the surface of the light emitting element 12).
As described above, by arranging the red phosphor in the vicinity of the light emitting element 12, a part of the light can be absorbed by the red phosphor 10 before the light from the light emitting element 12 diffuses widely.
Further, as described above, the red phosphor 10 has excellent temperature characteristics, and even when the temperature rises, the luminous efficiency hardly decreases. Therefore, there is no problem even if the temperature of the red phosphor 10 rises due to the heat generation of the light emitting element 12.

  The second resin layer 18 is disposed outside the first resin layer 8 (in a direction away from the light emitting element 12) and separated from the first resin layer 8. As a result, the second phosphor 20 having a shorter emission peak wavelength than the red phosphor (first phosphor) 10 is located outside the red phosphor 10 (at a position farther from the light emitting element 12 than the red phosphor 10). The red phosphor 10 is disposed apart from the red phosphor 10.

  By disposing the second resin layer 18 outside the first resin layer 8 away from the first resin layer 8, the second resin layer 18 is dispersed inside the second resin layer 18 due to heat generation of the light emitting element 12. It can suppress that the temperature of the 2nd fluorescent substance 20 rises. As a result, it is possible to reliably suppress the second phosphor 20 from being heated and the luminous efficiency from being lowered.

  Further, by arranging the second phosphor 20 outside the red phosphor 10 so as to be separated from the red phosphor 10, the second phosphor 20 emits light, such as green light or yellow light, Light having a shorter wavelength than the light emitted by the red phosphor can be prevented from being absorbed by the red phosphor 10. For this reason, the light emitted from the light emitting device 100 has high color rendering properties.

  Furthermore, the light emitted from the light emitting element 8 (in this case, including light that has been wavelength-converted by the phosphor) only passes through the two solid layers of the first resin layer 8 and the second resin layer 18. Since it reaches the outside of the light emitting device 100, the light emitting device 100 can obtain high luminous efficiency.

Further, as described above, the light emitting device 100 is arranged so that the first resin layer 8 is in contact with the light emitting element 12 and covers the light emitting element 12. Since the light is emitted from the light emitting element 12 before being diffused widely, a part of the light can be absorbed by the red phosphor 10.
Therefore, for example, the red phosphor used to emit red light having a desired intensity as compared with a light emitting device in which the red phosphor is arranged away from the light emitting element, such as the light emitting device disclosed in Patent Document 1. There is also an effect that the amount can be reduced.
Red phosphors are often more expensive than phosphors having a shorter emission peak wavelength than red phosphors, such as blue-green to green phosphors and yellow-green to yellow phosphors. For this reason, being able to reduce the usage-amount of red fluorescent substance contributes greatly to reduction of the manufacturing cost of the whole light-emitting device.

Furthermore, the light emitting device 100 also has an effect of improving color unevenness for the following reason.
For example, as in the light-emitting device disclosed in Patent Document 1, when the light-emitting elements and all the phosphor layers are arranged apart from each other, uneven color tends to occur. The amount of light emitted from the light emitting element is usually different depending on the angle such as the upper surface and the side surface. Therefore, the amount of light from the light emitting element incident on the phosphor layer is different between, for example, directly above the light emitting element and its periphery in a top view (viewed from the top to the bottom in FIG. 1). In general, the smaller the amount of light incident from the light emitting element, the greater the ratio of wavelength conversion by the phosphor, and the smaller the percentage of light that passes through the phosphor layer without wavelength conversion.
For this reason, the ratio of the light from the light emitting element (light that has not been wavelength-converted) and the light that has been wavelength-converted by the phosphor varies depending on the location on the surface of the phosphor layer. May appear as.

On the other hand, in this invention, the red fluorescent substance 10 is arrange | positioned in the vicinity of the light emitting element 12 by arrange | positioning the 1st resin layer 8 so that the light emitting element 12 may be touched and covered. For this reason, a part of the light emitted from the light emitting element 12 is wavelength-converted in the vicinity of the light emitting element 12 and scattered in various directions. Further, among the light emitted from the light emitting element 12, part of the light that is not wavelength-converted by the red phosphor 10 is also scattered by the red phosphor 10 in various directions.
As a result, although the second resin layer 18 is separated from the light emitting element 12, the light from the light emitting element is relatively uniform on the surface regardless of the location (light that has not undergone wavelength conversion and red fluorescence). (Mixed color light with the light wavelength-converted by the body 10) enters. Therefore, the occurrence of color unevenness is reduced.

Details of the elements constituting the light emitting device 100 will be described below.
-Light emitting element In embodiment shown in FIG. 1, the light emitting element 12 is arrange | positioned at the bottom face of the recessed part formed in the support body (LED package) 2. As shown in FIG. One or more supports 2 are provided on the mounting substrate 7, and the mounting substrates 7 are disposed on the bottom surface of the recess provided in the housing 6.
The light emitting element 12 may be a semiconductor element such as a light emitting diode (LED) or a laser diode (LD) that emits light spontaneously by applying a voltage.
As the light emitting element 12, it is preferable to use a surface mount type LED, and a light emitting element having an arbitrary emission wavelength can be selected according to the use of the light emitting device 100. For example, as the light emitting element 12 of blue (light with a wavelength of 430 nm to 490 nm), green or yellow green (light with a wavelength of 490 nm to 570 nm), a nitride-based semiconductor (In _X Al _Y Ga _1-XY N, 0 ≦ X, 0 ≦ Y, X + Y ≦ 1) and the like can be used. Further, as the red light emitting element 3 (light having a wavelength of 580 nm to 800 nm), GaAlAs, AlInGaP, or the like can be used.

Here, since the light-emitting device 100 of the present invention contains the first phosphor 10 and the second phosphor 20, the nitride semiconductor (which can emit light at a short wavelength and can excite these phosphors efficiently ( _{In X Al Y Ga 1-X} -Y N, 0 ≦ X, 0 ≦ Y, X + Y ≦ 1) is preferably used. For example, a blue LED is preferably used as the light emitting element 12. However, the component composition, emission color, size, and the like of the light emitting element 12 are not limited to the above, and can be appropriately selected according to the purpose. The light emitting element 12 may be an element that outputs not only visible light but also ultraviolet rays and infrared rays.

  In the embodiment shown in FIG. 1, a plurality of light emitting elements 12 are arranged on one support 2, but the present invention is not limited to this, and the light output required by the light emitting device 100 and the light emitting device 100 of the light emitting device 100 are not limited thereto. One or two or more arbitrary numbers of light emitting elements 12 may be arranged on one support 2 in consideration of the use and dimensions. When a plurality of light emitting elements 12 are arranged, for example, they may be arranged in any form such as being arranged on the bottom surface of the cavity 4 in the vertical direction and / or the horizontal direction.

The p electrode and the n electrode of each light emitting element 12 are connected to one and the other of the bonding wire 14a and the bonding wire 14b, respectively. The bonding wire 14a and the bonding wire 14b are respectively connected to different leads (not shown), whereby the light emitting element 12 is electrically connected to a power source (not shown) provided outside the light emitting device 100. Emits light of a desired wavelength.
Note that the method of electrically connecting the light emitting element 12 to the power source is not limited to this. For example, one of the p electrode and the n electrode is provided on the bottom surface of the light emitting element 12 and directly connected to the lead, etc. Any known power feeding method (voltage application method) of the light emitting element may be used.

First resin layer and first phosphor The first resin layer 8 including the first phosphor (red phosphor) 10 may contact the light emitting element 12 and cover the light emitting element 12 in any form. .
In the embodiment shown in FIG. 1, the first resin layer 8 is formed by filling the cavity 4 of the package resin 2 with a resin containing the first phosphor 10 (that is, sealing the light emitting element 12). ing. Although arbitrary resin may be used for resin used for the 1st resin layer 8, it is preferable to use transparent resin. This is for suppressing the light emitted from the light emitting element 12 and the first phosphor 10 from being absorbed. Examples of suitable resins include silicone resins and epoxy resins used with sealing resins. After such a resin is melted and the red phosphor 10 is mixed and dispersed, the mixture of the resin and the red phosphor 10 is filled in the cavity 4 and the resin is cured to thereby cure the first resin layer. 8 can be formed.

  In the embodiment shown in FIG. 1, the upper surface of the first resin layer 8 is a convex surface that protrudes upward in the plane of FIG. 1. However, the present invention is not limited to this form, and may be any form such as a flat surface and a concave surface protruding downward in the drawing.

As the red phosphor 10, for example, a SCASN phosphor such as (Sr, Ca) AlSiN ₃ : Eu, a CASN phosphor such as CaAlSiN ₃ : Eu, Ca ₂ Si ₅ N ₈ : Eu, Ca _X (Si , Al) ₁₂ (N, O) ₁₆ : Eu (where X is an arbitrary number), α sialon-based phosphors, CaSiN ₂ : Eu, (Ca, Sr) S: Eu, K ₂ SiF ₆ : Mn, LiEuW ₂ O ₈ or the like can be used.
The red phosphor in the present specification means a phosphor having an emission wavelength of light emitted by absorbing and converting light within a range of 580 nm to 800 nm, and a blue-green to green phosphor is A phosphor having an emission wavelength in the range of 490 nm to 550 nm is meant, and a yellow-green to yellow phosphor means a phosphor having an emission wavelength in the range of 510 nm to 580 nm.

The red phosphor 10 is preferably contained in a weight ratio of 0.01% to 500% with respect to the resin of the first resin layer 8.
Needless to say, it is preferable that the first resin layer 8 does not substantially contain a phosphor other than the red phosphor, such as a blue-green to green phosphor and a yellow-green to yellow phosphor. Here, “substantially not containing” in the present specification means that it is not intentionally added. That is, it is not excluded that it is inevitably contained.
Moreover, the 1st resin layer 8 may contain substances other than the red fluorescent substance 10 and resin like a filler and a spreading | diffusion agent as needed.

-2nd resin layer, 2nd fluorescent substance, and air layer The 2nd resin layer 18 containing the dispersed 2nd fluorescent substance 20 is 1st on the outer side of the 1st resin layer 8 in arbitrary forms. You may arrange | position away from the resin layer 8.

In the embodiment of FIG. 1, the outer periphery of the second resin layer 18 has a shape that widens from the cavity (lower end (bottom side, lower part of FIG. 1)) to the upper end (upper part of FIG. 1) of the housing 6. It is arranged in contact with the upper end of the cavity).
For such a second resin layer 18, for example, the second resin layer 18 is formed in advance as a resin cover using a resin and a second phosphor, and the outer periphery of the resin cover is encased. It can be obtained by placing and fixing so as to contact the upper end of the cavity of the body 6.

Any resin may be used as the resin used for the second resin layer 18. One suitable example is a transparent resin. This is because the light emitted from the light emitting element 12, the first phosphor 10, and the second phosphor (at least one of the green phosphor and the yellow phosphor) is suppressed from being absorbed. Another preferred example is a translucent resin in which a transparent material contains a diffusing material such as TiO ₂ or SiO ₂ . The light emitted from the light emitting element 12, the first phosphor 10, and the second phosphor (at least one of the green phosphor and the yellow phosphor) is suppressed to some extent, and the light is sufficiently diffused. Because it can.

  Examples of such suitable resins include silicone resins and epoxy resins. After mixing and dispersing the red phosphor 10 in such a molten state, the resin in which the red phosphor 10 is dispersed is filled in a mold and the resin is cured to form a resin cover having a predetermined shape. it can. The second resin layer 18 can be obtained by disposing the resin cover above the cavity of the housing 6.

  In the embodiment shown in FIG. 1, the second resin layer 18 has a convex shape that protrudes upward in the paper surface of FIG. 1. However, it is not limited to this shape, and may be any shape such as a flat surface and a concave shape protruding downward in the drawing.

When a green phosphor is used as the second phosphor 20, for example, a chlorosilicate-based phosphor such as Ca ₈ MgSi ₄ O ₁₆ Cl ₂ : Eu, (Si, Al) ₆ (N, O) ₈ : Eu Such a β sialon phosphor can be used.
When a yellow phosphor is used as the second phosphor 20, for example, an yttrium / aluminum / garnet phosphor (YAG phosphor) can be used. For example, in a YAG phosphor, a part or all of Y may be substituted with Tb, Lu, or the like. _{Specifically, Tb 3 Al 5 O 12:} Ce, Lu 3 Al 5 O 12: may be Ce or the like. Furthermore, phosphors other than the above-described phosphors having the same performance, function, and effect can be used. In addition, Eu-activated silicate phosphor may be used. Ca ₈ MgSi ₄ O _{16 Cl 2} : Eu, (Si, Al) ₆ (N, O) ₈ : Eu, BaSi ₂ O ₂ N ₂ : Eu, (Ba, Sr) ₂ SiO ₄ : Eu, Sr4Al ₁₄ O ₂₅ : Eu, SrAl ₂ O ₄ : Eu, SrGa ₂ S ₄ : Eu, Ba ₃ Si ₆ N ₂ O ₁₂ : Eu, (Sr, Ba) ₂ SiO ₄ : Eu, (Ca, Sr) Si ₂ O ₂ N _{2 : Eu, La 3 Si 6 N} 11: Ce, Ca 3 Sc 2 Si 3 O 12: Ce, CaSc 2 O 4: Ce, (Sr, Ca, Ba) Ga 2 S 4: Eu, ZnS: Cu.
The second phosphor 20 may include a plurality of types of phosphors including these exemplified phosphors.

The second phosphor 20 is preferably contained in a weight ratio of 0.1% to 200% with respect to the resin of the second resin layer 18.
Needless to say, it is preferable that the second resin layer 18 does not substantially contain a phosphor other than the green and yellow phosphors such as a red phosphor.
Moreover, the 2nd resin layer 18 may contain substances other than the 2nd fluorescent substance 20 and resin like a filler and a spreading | diffusion agent as needed.

In the embodiment shown in FIG. 1, the first resin layer 8 and the second resin layer 18 are separated by an air layer (space) 16.
Since the air layer 16 has an excellent heat insulating effect, the heat generated by the light emitting element 12 can be sufficiently suppressed from being transmitted to the second resin layer 18, particularly the second phosphor 20. For this reason, the temperature rise of the 2nd fluorescent substance 20 by the heat_generation | fever of the light emitting element 12 is fully suppressed, and the fall of the luminous efficiency of the 2nd fluorescent substance 20 is fully suppressed.
The distance between the first resin layer 8 and the second resin layer 18 is preferably 1 mm to 50 mm. If the distance between the first resin layer 8 and the second resin 18 is too close, the heat insulating effect on the second resin layer is reduced. If the distance is too far, the size of the light emitting device 100 is increased, resulting in cost reduction. This can be a disadvantage.

By disposing the second resin layer 18 outside the first resin layer 8 away from the first resin layer 8, the second phosphor (green phosphor and / or yellow phosphor) as described above. ) The light emitted by 20 can be prevented from being absorbed by the red phosphor 10.
In particular, this effect is remarkable in the light-emitting device 100 in which the housing 6 has a cavity having a shape extending from the lower end toward the upper end.
That is, a part of the light emission of the light emitting element 12 that has passed through the first resin layer 8 is absorbed by the second phosphor 20 of the second resin layer 18, and the second phosphor 20 has yellow light and / or Emits green light (yellowish green light). A part of the light emitted from the second phosphor 20 is emitted backward, that is, from the top to the bottom in FIG. However, in the light emitting device 100 shown in FIG. 1, the second resin layer 18 has a considerably larger area than the first resin layer 8 when viewed from the top to the bottom of FIG. Most of the light emitted backward by the phosphor 20 reaches the cavity surface of the housing 6, not the first resin layer 8 (in particular, the red phosphor 10). For this reason, of the light emitted by the second phosphor 20, the light absorbed by the red phosphor 10 is extremely small, and the efficiency of the light emitting device 100 is increased.

In addition, the surface of the cavity is formed by arranging a reflective material such as metal plating such as silver (Ag) on the cavity surface of the housing 6 or making the cavity surface of the housing 6 a bright color such as white. It is preferable to keep the reflectance of light high.
Thereby, not only the light of the second phosphor 20 emitted backward, but also the light reaching the surface of the cavity including the light emission of the light emitting element 12 and the light emission of the red phosphor 10 is shown in the upper part of FIG. This is because the efficiency of the light emitting device 100 can be further increased by reflecting in the direction toward the second resin layer 18.

  The casing 6 has a cavity inside as described above, and has the package resin 2 on the bottom surface of the cavity. The housing 6 and the package resin 2 may be integrally molded from the same resin using one mold, for example. Alternatively, the housing 6 may be formed on the bottom surface of the cavity of the housing 6 after the housing 6 is formed in advance using a material other than the same resin as the resin package 2 or a resin such as ceramic.

The housing 6 (when formed of resin) and the resin package 2 may be formed of any resin. Examples of preferable resins include nylon resins, epoxy resins, and silicone resins.
If necessary, a reflective material such as metal plating such as silver (Ag) may be disposed on the surface of the cavity 4 of the package resin 2 or the surface of the cavity 4 may be a bright color such as white. Thereby, the reflectance of the light on the surface of the cavity 4 can be improved, and the light from the light emitting element 12 that has reached the surface of the cavity 4 and the light emission of the first phosphor 10 are shown in FIG. 18), the efficiency of the light emitting device 100 can be further increased.

Next, the light emission mechanism of the light emitting device 100 will be described.
In the light emitting device 100 having the above configuration, light having a predetermined wavelength peak (for example, blue light) is emitted from the light emitting element 12 by supplying power to the light emitting element 12 through the bonding wires 14a and 14b. .
Part of the light emitted from the light emitting element 12 passes through the first resin layer 8 without changing the wavelength, and enters the second resin layer 18 through the space 16. Further, another part of the light emitted from the light emitting element 12 is absorbed by the red phosphor 10 dispersed in the first resin layer 8 and converted in wavelength, and red light is emitted from the red phosphor 10. This red light passes through the space 16 and enters the second phosphor layer 18.

  The light emitting element 12 generates heat during light emission, and this heat generation is transmitted to the first resin layer 8 in contact with the light emitting element 12. As a result, the red phosphor 10 is heated to a high temperature such as about 80 ° C. or higher. However, at such a temperature, the luminous efficiency of the red phosphor 10 hardly decreases as described above.

Part of the light emitted from the light emitting element 12 (light that has not been wavelength-converted) that has entered the second resin layer 18 passes through the second resin layer 18 without changing its wavelength, and is outside the second resin layer 18. To reach. Another part of the light emitted from the light emitting element 12 (light that has not undergone wavelength conversion) that has entered the second resin layer 18 is absorbed by the second phosphor (green phosphor and / or yellow phosphor) 20. . The second phosphor 20 emits green light and / or yellow light, and most of the green light and / or yellow light goes out of the second resin layer 18.
Most of the red light entering the second resin layer 18 goes out of the second resin layer 18 without being absorbed by the second phosphor 20.

  As a result of the above, outside the second resin layer 18, the light that has arrived from the light emitting element without changing the wavelength (the light emitted from the light emitting element 12), red light, and at least one of green light and yellow light Mixed light is obtained. Since this mixed light has a wide spectrum, it has excellent color rendering properties.

・ Modification 1
FIG. 2 is a cross-sectional view of a light emitting device 100A according to Modification 1 of the present invention.
In the light emitting device 100 described above, the first resin layer 8 and the second resin layer 18 are separated via the air layer 16, whereas in the light emitting device 100A, the first resin layer 8 and the second resin layer 18 are separated from each other. The resin layer 18 is spaced apart via the third resin layer 16A.
The other configuration of the light emitting device 100A is the same as that of the light emitting device 100.
Below, only the structure different from the light-emitting device 100 among 100 A of light-emitting devices is demonstrated.

The third resin layer 16 </ b> A is transparent or translucent so that light emitted from the first resin layer 8 can reach the second resin layer 18. It is preferable that the light exiting the first resin layer 8 is transparent so that it can reach the second resin layer 18 with high efficiency.
The resin that constitutes the third resin layer may be the same as or different from the resin that constitutes the first resin layer 8 and / or the resin that constitutes the second resin layer 18.
Examples of preferable resins constituting the third resin layer 16A include epoxy resins and silicone resins.

  The third resin layer 16A preferably does not substantially contain a phosphor such as a red phosphor, a green phosphor and a yellow phosphor. This is because the effect of separating the red phosphor 10 included in the first resin layer 8 from the green phosphor and / or the yellow phosphor 20 included in the second resin layer 18 can be further ensured.

  Thus, by providing the third resin layer 16A, the difference in refractive index between the resin contained in the first resin layer 8 and the resin contained in the second resin layer 18 can be reduced, and the light extraction efficiency can be reduced. Can be improved.

  Further, the third resin layer 16A may contain a diffusing agent and / or a filler as necessary.

  Instead of the third resin layer 16A, a light-transmitting layer having the same shape as the third resin layer 16A may be provided by using a light-transmitting material other than a resin such as glass or ceramics.

  Similar to the light emitting device 100, the light emitting device 100A has high efficiency and can obtain light having excellent color rendering properties. In addition, the amount of red phosphor used can be suppressed.

・ Modification 2
FIG. 3A is a perspective view of a light emitting device 100C according to Modification 2 of the present invention, and FIG. 3B is a cross-sectional view of the light emitting device 100C.
The light emitting device 100C is a so-called light bulb type light emitting device used in place of a light bulb.
A description will be given below of the configuration of the light emitting device 100 </ b> C centering on a portion different from the light emitting device 100.
Therefore, the configuration of the light emitting device 100C not described below may be the same as that of the light emitting device 100.

  In the light emitting device 100 </ b> C, the support (LED package) 2 is disposed on the mounting substrate 7 disposed on the bottom surface of the recess of the housing 6. In the embodiment shown in FIG. 3 (FIGS. 3A and 3B), one light emitting element 12 is disposed on the bottom surface of each concave portion of the plurality of supports 2, but this is not the only mode. It is not something. For example, a single support 2 is disposed and a plurality of light emitting elements 12 are disposed on the bottom surface of the recess, or a plurality of light emitting elements are disposed on the bottom surfaces of the respective recesses of the plurality of supports 2. The body 2 and the light emitting element 12 may be arranged in any form.

In the recess of the support 2, the first resin layer 8 including the first phosphor 10 is disposed so as to contact the light emitting element 12 and cover the light emitting element 12. The same.
Further, the second resin layer 18 including the second phosphor 20 is disposed away from the first resin layer 8, and the first resin layer 8 and the second resin layer 18 are separated from each other. The air layer 16 may be formed between them as in the light emitting device 100.

  The light emitting element 12 is electrically connected to a circuit pattern (not shown) formed on the mounting substrate 7 via the bonding wires 14a and 14b, so that the light emitting element 12 can be supplied with power.

  The housing 6 is fixed on the main body 30. The main body portion 30 may house a heat radiating member and a circuit therein as necessary. The main body 30 has a base 50 attached to the lower part thereof.

  The main body 30 is preferably formed using a member having excellent heat resistance. Moreover, since it is a part which is easy to touch a person's hand directly, it is preferable to form using a member with low heat conductivity. Furthermore, it is preferable to use a material having excellent mechanical strength. Moreover, it is preferable to form from the member which is easy to manufacture, and heat resistant resin, a ceramic, etc. are preferable members. More specifically, preferable examples of the member include polycarbonate (PC) and polybutylene terephthalate (PBT).

  The base 50 is made of a conductive material such as metal and is electrically connected to the circuit pattern on the mounting substrate 7 described above.

・ Modification 3
FIG. 4A is a perspective view of a light emitting device 100D according to Modification 3 of the present invention, and FIG. 4B is a cross-sectional view taken along line IVb-IVb in FIG. In FIG. 4A, the description of the first resin layer 8 and the second resin layer 18 is omitted in order to facilitate understanding of the arrangement and the like of the light emitting element 12.
The light emitting device 100D is a so-called fluorescent lamp type light emitting device that is used in place of a fluorescent lamp.
A description will be given below of the configuration of the light emitting device 100 </ b> D with a focus on differences from the light emitting device 100. Therefore, the configuration of the light emitting device 100D not described below may be the same as that of the light emitting device 100.

In the embodiment shown in FIG. 4 (FIGS. 4A and 4B), the light emitting element 12 is arranged directly on the mounting substrate 7 without using a support.
However, the present invention is not limited to this mode, and the support 2 may be used similarly to the light emitting device 100 or the light emitting device 100C.

The light emitting element 12 is electrically connected to a circuit pattern (not shown) formed on the mounting substrate 7 via the bonding wires 14a and 14b, so that the light emitting element 12 can be supplied with power.
In the embodiment of FIG. 4, the light emitting elements 12 are arranged in a line, but the present invention is not limited to this. The light emitting elements 12 may be arranged in an arbitrary form such as being arranged in a plurality of rows or a staggered arrangement.

  The mounting substrate 7 is fixed on the housing 6. The casing 6 has caps 52 arranged at both ends. At least one of the two caps 52 is electrically connected to a circuit pattern formed on the mounting substrate 7 described above.

  The first resin layer 8 including the first phosphor 10 is disposed so as to be in contact with the light emitting element 12 and cover the light emitting element 12, as in the light emitting device 100. However, since the package resin is not used in the embodiment of FIG. 4, the bottom surface of the first resin layer 8 is in contact with the mounting substrate 7.

Further, the second resin layer 18 including the second phosphor 20 is disposed away from the first resin layer 8, and the first resin layer 8 and the second resin layer 18 are separated from each other. The air layer 16 may be formed between them as in the light emitting device 100.
The second resin layer 18 preferably extends from one base 52 to the other base 52 in FIG.
This is because the light emission of the light emitting element 12 can be efficiently converted into light having a peak wavelength shorter than the emission peak wavelength of the red phosphor 10.

DESCRIPTION OF SYMBOLS 2 Support body 4 Cavity of support body 6 Housing | casing 7 Mounting substrate 8 1st resin layer 10 1st fluorescent substance (red fluorescent substance)
12 Light emitting element 14a, 14b Bonding wire 16 Air layer 16A 3rd resin layer 18 2nd resin layer 20 2nd fluorescent substance (green fluorescent substance and / or yellow fluorescent substance)
30 Main body 50, 52 Base 100, 100A, 100C, 100D Light emitting device

Claims (7)

A light emitting element;
A first resin layer including a red phosphor disposed in contact with and covering the light emitting element;
A second resin layer including a phosphor having an emission peak wavelength shorter than that of the red phosphor, which is disposed outside the first resin layer and spaced from the first resin layer;
A light emitting device comprising:   The light emitting device according to claim 1, wherein an air layer is formed between the first resin layer and the second resin layer.   2. The light emitting device according to claim 1, wherein a resin layer that does not substantially contain a phosphor is formed between the first resin layer and the second resin layer.   The light emitting device according to claim 1, wherein a peak wavelength of light emitted from the light emitting element is 420 nm to 490 nm. The short phosphors having peak emission wavelength than the red phosphor comprises a blue-green to green phosphor,該青green to green _{phosphor, Ca 8 MgSi 4 O 16 C} l2: Eu, (Si, Al) 6 (N, O) ₈ : Eu, BaSi ₂ O ₂ N ₂ : Eu, (Ba, Sr) ₂ SiO ₄ : Eu, Sr ₄ Al ₁₄ O ₂₅ : Eu, SrAl ₂ O ₄ : Eu, SrGa ₂ S ₄ : The light-emitting device according to claim 1, comprising at least one selected from the group consisting of Eu and Ba ₃ Si ₆ N ₂ O ₁₂ : Eu. The phosphor having an emission peak wavelength shorter than that of the red phosphor includes yellow-green to yellow phosphor, and the yellow-green to yellow phosphor is (Y, Lu, Gd, Tb) ₃ (Al, Ga) ₅ O. ₁₂ : Ce, (Sr, Ba) ₂ SiO ₄ : Eu, (Ca, Sr) Si ₂ O ₂ N ₂ : Eu, La ₃ Si ₆ N ₁₁ : Ce, Ca ₃ Sc ₂ Si ₃ O ₁₂ : Ce, CaSc 6. The composition according to claim 1, comprising at least one selected from the group consisting of ₂ O ₄ : Ce, (Sr, Ca, Ba) Ga ₂ S ₄ : Eu and ZnS: Cu. The light emitting device according to 1. The red phosphor is (Ca, Sr) AlSiN ₃ : Eu, (Ca, Sr) ₂ Si ₅ N ₈ : Eu, CaSiN ₂ : Eu, (Ca, Sr) S: Eu, K ₂ SiF ₆ : Mn, LiEuW ₂ O ₈ and _{Ca X (Si, Al) 12} (N, O) 16: according to any one of claims 1 to 6, characterized in that it comprises at least one selected from the group consisting of Eu Light-emitting device.

Images