JP2017152522A - Light-emitting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light-emitting device which is uniform in emission luminance and color tone.SOLUTION: A light-emitting device is provided, which comprises: a light-emitting element; an encapsulation member for encapsulating the light-emitting element; and a phosphor included in at least a part of the encapsulation member, absorbing a part of light from the light-emitting element, and converting the absorbed part of light into light of a wavelength different from an emission wavelength of the light-emitting element. The light-emitting element and the phosphor are similar in color. The light emission peak wavelength of the phosphor is located within a range of less than 20 nm from a peak wavelength of the light-emitting element toward a longer wavelength side.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a light emitting device that outputs light using a phosphor.

A light emitting device using a light emitting element as a light source has been put into practical use. In recent years, the luminous efficiency has been improved rapidly, and there is an increasing demand for color quality.

There is a problem in that the light emitting element is affected by subtle differences in film formation temperature and thickness in the wafer manufacturing process, and the light emitting characteristics and electrical characteristics of the light emitting element vary. At present, by measuring the total number of light emitting elements, the output, wavelength, and forward voltage VF are finely selected and used in respective ranks. This is because the characteristics of the light-emitting element greatly affect the characteristics of the product. The output of the light emitting element greatly affects the brightness, and the electrical characteristics relate to the efficiency such as lm / W.

  For example, in Patent Document 1 below, manufactured light emitting elements are classified into a plurality of light emitting wavelength regions, and a combination of a first light emitting element classified on the long wavelength side and a second light emitting element classified on the short wavelength side is combined. Thus, a light emitting diode (light emitting device) with uniform light emission luminance and color tone is easily formed with a good yield.

Japanese Patent No. 4932978

  However, since the light-emitting diode (light-emitting device) according to Patent Document 1 must use a plurality of light-emitting elements, the cost increases. Accordingly, the present invention provides a light emitting device with uniform light emission luminance and color tone even when a single light emitting element is used.

  According to one embodiment of the present invention, a light-emitting element, a sealing member that seals the light-emitting element, and contained in at least a part of the sealing member, absorb a part of light from the light-emitting element, A phosphor that converts light having a wavelength different from the emission wavelength of the light emitting element, the light emitting element and the phosphor have similar colors, and the emission peak wavelength of the phosphor is longer than the peak wavelength of the light emitting element. A light emitting device is provided which is located in a range of less than 20 nm on the wavelength side.

  According to the present invention, it is possible to provide a light emitting device with uniform light emission luminance and color tone even when using light emitting elements with varying emission wavelengths.

It is a schematic sectional drawing of the light-emitting device which concerns on embodiment of this invention. It is the figure which showed the measurement distribution of the light emission wavelength of the light-emitting device which concerns on embodiment of this invention. It is the figure which showed the spectral relationship of the fluorescent substance of the light-emitting device which concerns on Example 1 of this invention, and a light emitting element. It is the figure which showed the spectral relationship of the fluorescent substance and light emitting element of the light-emitting device which concern on Example 2 of this invention. It is the figure which showed the spectral relationship of the fluorescent substance and light emitting element of the light-emitting device which concern on Example 3 of this invention. It is a schematic sectional drawing of the light-emitting device which concerns on other embodiment of this invention.

  Next, an embodiment of the present invention will be described with reference to the drawings. In the following description of the drawings, the same or similar parts are denoted by the same or similar reference numerals. However, it should be noted that the drawings are schematic and ratios of thicknesses of the respective regions are different from actual ones. Therefore, specific thicknesses and dimensions should be determined in consideration of the following description. Moreover, it is a matter of course that portions having different dimensional relationships and ratios are included between the drawings.

As shown in FIG. 1, a light emitting device 1 according to an embodiment of the present invention includes a light emitting element 10 that is disposed in a housing 40 having a recess and emits visible light, and is excited by light emitted from the light emitting element 10 to emit light. A phosphor 21 that emits light having a small wavelength difference from 10 and a sealing member 30 containing the phosphor 21 are filled in the recess of the housing 40 so as to cover the light emitting element 10. Hereafter, each element which comprises the light-emitting device of this invention is demonstrated in detail.

(Light emitting element)
As the light emitting element 10, a semiconductor light emitting element such as an LED or a laser diode can be employed. In the following examples, description will be made using a blue light emitting element having an emission wavelength of 440 nm to 460 nm. However, the light emitting element 10 is not limited to blue, and may be green or red.

(Casing)
The housing 40 is provided with an electrical wiring 70, and the light emitting element 10 is electrically connected to the die pad 50 on the electrical wiring 70. A drive current flows through the light emitting element 10 by applying a voltage between the positive electrode and the negative electrode of the light emitting element 10. Thereby, the light emitting element 10 emits light.
Moreover, the housing | casing 40 has a recessed part and the light emitting element 10 is mounted in the bottom part of the said recessed part. The concave portion has a bottom portion and a side portion, and is composed of a space having a shape in which a cross-sectional area perpendicular to the optical axis increases continuously or stepwise from the bottom portion toward the light extraction direction of the light emitting device 10. Say part. The shape of the bottom part and the side part is not particularly limited as long as this condition is satisfied.
Further, a reflective layer made of a metal or an alloy is formed on the side surface (on the inner peripheral surface) of the concave portion of the housing 40. The reflective layer does not necessarily have to be formed on the entire surface of the side surface of the recess, but the light emitted from the light emitting element 10 to the side is irradiated so that the effect of improving the light emission efficiency by the reflective layer is maximized. It is preferable to provide a reflective layer over the entire region.

(Phosphor)
The phosphor 21 is of the same color as the light emitting element 10 to be used. Specifically, a phosphor having a wavelength difference of less than 20 nm on the long wavelength side is used for the light emitting element 10. For example, in the case of a blue light emitting element having a wavelength of 440 nm, a phosphor having an emission peak wavelength of less than 460 nm is used. The phosphor used this time can absorb a part of light from the light emitting element and convert it into light having a long wavelength, and can change or correct the emission color of the light emitting device. Any phosphor can be used as long as it can be excited by light from the light emitting element, and the light emission color, durability, and the like of the light emitting device are taken into consideration in the selection. The phosphor 21 may be uniformly dispersed in the sealing member 30 or may be localized in a part of the region.

(Sealing member)
The sealing member 30 is a member formed so as to cover the light emitting element 10 and is provided mainly for the purpose of protecting the light emitting element 10 from the external environment. As the material of the sealing member 30, it is preferable to employ a material that is transparent to the light of the light emitting element 10 and is excellent in durability, weather resistance, and the like.
For example, an appropriate material can be selected from silicone (including silicone resin, silicone rubber, and silicone elastomer), epoxy resin, glass, and the like in relation to the emission wavelength of the light emitting element 10. When the light emitted from the light-emitting element includes light in a short wavelength region, ultraviolet degradation is a problem. Therefore, it is preferable to employ a material having high resistance to ultraviolet degradation such as silicone.

Example 1
As the light emitting element 10, an element that emits light having a wavelength of 440 nm is used. As the phosphor 21, (Ba, Sr) MgAl ₁₀ O ₁₇ : Eu ²⁺ (BAM) phosphor can be used. In addition to the above, the phosphor 21 may be, for example, (Ba, Sr, Ca, Mg) ₁₀ (PO ₄ ) ₆ Cl ₂ : Eu ²⁺ , CaMgSi ₂ O ₆ : Eu ²⁺ , Sr ₂ P ₂ O ₇ : Sn ²⁺ , (Ba, Sr, Ca) ₃ MgSi ₂ O ₈ : Eu ²⁺ , CaAl ₂ O ₄ : Eu ²⁺ , ZnS: Ag, Cl, Ca ₂ B ₅ O ₉ (Br, Cl): Eu ²⁺ , ZnGa ₂ O ₄ etc. Can be adopted.

  Samples were prepared in which the blending ratio of the phosphor 21 to the sealing member 30 was 0% (transparent resin: Comparative Example 1), 10% (sample S1), 25% (sample S2), and 50% (sample S3). Note that if the phosphor 21 is blended more than the sealing member 30, the emission intensity decreases. Further, the phosphor 21 preferably has a smaller particle diameter, and specifically, the average particle diameter is preferably 10 μm or less.

  The sealing member 30 mixed with the phosphor 21 was filled in the concave portion of the housing 40 on which the light emitting element 10 was mounted, and the light emitting device 1 according to Example 1 of the present invention was obtained.

For Comparative Example 1 and Samples S1 to S3, the emission characteristics at the time of current injection (IF = 50 mA) were obtained into each light-emitting device using a spectroradiometer SR-3A manufactured by Topcon Technohouse Co., Ltd. Table 1 shows the results.

From the results of Table 1, it can be seen that both the emission peak wavelength and the dominant wavelength are shifted by several nm toward the long wavelength side. The wavelength rank of a general light emitting element is in increments of 2.5 nm. As shown in FIG. 2, one wavelength rank can be moved to the longer wavelength side at a phosphor concentration of 25%, and two wavelength ranks can be moved to the longer wavelength side at a phosphor concentration of 50%.

FIG. 3 shows the emission spectrum and excitation spectrum of the BAM phosphor, and the spectrum of a blue light emitting device having a wavelength of 440 nm.
The excitation spectrum of BAM is a graph relatively showing at which wavelength BAM emits light, and this excitation spectrum suggests that light is efficiently emitted in the ultraviolet region.
It can be seen that in the wavelength region where the emission spectrum of the blue light emitting element and the excitation spectrum of the BAM overlap, a part of the light of the blue light emitting element is absorbed to emit BAM.
For this reason, a part of the light of the blue light emitting element is absorbed, and light conversion by BAM becomes possible.

(Example 2)
As the light emitting element 10, an element that emits light having a wavelength of 447 nm is used. As the phosphor 21, for example, Sr ₃ MgSi ₂ O ₈ : Eu ²⁺ (SMS) phosphor can be used. In addition to this, the phosphor 21 may be, for example, (Ba, Sr) MgAl ₁₀ O ₁₇ : Eu ²⁺ , (Ba, Sr, Ca, Mg) ₁₀ (PO ₄ ) ₆ Cl ₂ : Eu ²⁺ , CaMgSi ₂ O ₆ : ^{_{Eu 2+, Sr 2 P 2 O}} 7: Sn 2+, (Ba, Sr, Ca) 3 MgSi 2 O 8: Eu 2+, CaAl 2 O 4: Eu 2+, ZnS: Ag, Cl, Ca 2 B 5 O 9 ( Br, Cl): Eu ²⁺ , ZnGa ₂ O ₄ , CaGa ₂ S ₄ : Ce ³⁺ , BaAl ₂ S ₄ : Eu ²⁺ , and the like can be used.

  Samples were prepared in which the blending ratio of the phosphor 21 to the sealing member 30 was 0% (transparent resin: Comparative Example 2), 10% (sample S4), 25% (sample S5), and 50% (sample S6).

  The sealing member 30 mixed with the phosphor 21 was filled in the concave portion of the housing 40 on which the light emitting element 10 was mounted to obtain the light emitting device 1 according to Example 2 of the present invention.

For Comparative Example 2 and Samples S4 to S6, emission characteristics at the time of current injection (IF = 50 mA) were obtained into each light-emitting device using a spectroradiometer SR-3A manufactured by Topcon Technohouse Co., Ltd. Table 2 shows the results.

  From the results in Table 2, it can be seen that both the emission peak wavelength and the dominant wavelength are shifted to the longer wavelength side. As shown in FIG. 2, it can be moved by one wavelength rank at a phosphor concentration of 10%, two wavelength ranks at a phosphor concentration of 25%, and five wavelength ranks at a phosphor concentration of 50%.

FIG. 4 shows an emission spectrum and an excitation spectrum of an SMS phosphor, and a spectrum of a blue light emitting device having a wavelength of 447 nm.
As in the first embodiment, a part of the light emitted from the blue light emitting element is absorbed, and light conversion by SMS is possible.

(Example 3)
As the light emitting element 10, an element that emits light having a wavelength of 460 nm is used. For example, a Ca ₃ MgSi ₂ O ₈ : Eu ²⁺ (CMS) phosphor can be used as the phosphor 21. In addition to this, the phosphor 21 may be, for example, Sr ₂ P ₂ O ₇ : Sn ²⁺ , (Ba, Sr, Ca) ₃ MgSi ₂ O ₈ : Eu ²⁺ , ZnS: Ag, Cl, ZnGa ₂ O ₄ , CaGa _2. S ₄ : Ce ³⁺ , BaAl ₂ S ₄ : Eu ²⁺ , Sr ₆ P ₅ BO ₂₀ : Eu ²⁺ , BaGa ₂ S ₄ : Eu ²⁺ , Sr ₅ Si ₄ O ₁₀ Cl ₆ : Eu ²⁺ , Ca ₈ Mg (SiO ₄ ) ₄ Cl ₂ : Eu ²⁺ can be used.

  Samples with a blending ratio of the phosphor 21 to the sealing member 30 of 0% (transparent resin: Comparative Example 3), 10% (sample S7), 25% (sample S8), and 50% (sample S9) were prepared.

  The sealing member 30 mixed with the phosphor 21 was filled in the recess of the housing 40 on which the light emitting element 10 was mounted, and the light emitting device 1 according to Example 3 of the present invention was obtained.

For Comparative Example 3 and Samples S7 to S9, emission characteristics at the time of current injection (IF = 50 mA) were obtained into each light emitting device using a spectroradiometer SR-3A manufactured by Topcon Technohouse Co., Ltd. Table 3 shows the results.

  From the results in Table 3, it can be seen that both the emission peak wavelength and the dominant wavelength are shifted to the longer wavelength side. As shown in FIG. 2, the wavelength rank did not move at the phosphor concentrations of 10% and 25%, but can be moved by two wavelength ranks at the phosphor concentration of 50%.

FIG. 5 shows an emission spectrum and an excitation spectrum of a phosphor of CMS, and a spectrum of a blue light emitting element having a wavelength of 460 nm.
As in Example 1, a part of the light emitted from the blue light emitting element is absorbed, and light conversion by CMS becomes possible.

Although the said Examples 1-3 showed the light emitting device of the same color which shifted the wavelength of the blue light emitting element to the long wavelength side, as shown in FIG. If the second phosphor 22 capable of blue excitation is arranged, white light can be obtained.

Incidentally, as the second phosphor _{22, Ca 8 Mg (SiO 4} ) 4 Cl 2: Eu 2+, (Ba, Sr, Ca) 3 MgSi 2 O 8: Eu 2+, Mn 2+, (Ba, Sr, ^{_{Ca) 2 SiO 4: Eu 2+}} , (Ca, Mg) 3 Sc 2 Si 3 O 12: Ce 3+, CaSc 2 O 4: Ce 3+, SrGa 2 S 4: Eu 2+, Si 6-z Al z O z N ^{_{8-z: Eu 2+, Sr}} 3 Si 13 Al 3 O 2 N 21: Eu 2+, Ba 3 Si 6 O 12 N 2: Eu 2+, (Ba, Sr, Ca) Si 2 O 2 N 2: Eu 2+, AlON: Mg, Mn ²⁺ , (Y, Ga) ₃ (Al, Gd) ₅ O ₁₂ : Ce ³⁺ , La ₃ Si ₆ N ₁₁ : Ce ³⁺ , (Sr, Ca, Ba) ₃ SiO ₅ : Eu ²⁺ , Ca -Α ^{_{SiAlON: Eu 2+, (Sr,}} Ca) AlSiN 3: Eu 2+, (Ba, Sr, Ca) 2 Si 5 N 8: Eu 2+, Sr 2 Si 7 Al 3 O 2 N 13: Eu 2+, K 2 SiF 6 : Mn ⁴⁺ , Sr (LiAl ₃ N ₃₄ ): Eu ²⁺ , Al ₂ O ₃ : Cr ³⁺ can be used.

As described above, the present invention naturally includes various embodiments not described herein. Therefore, the technical scope of the present invention is defined only by the invention specifying matters according to the scope of claims reasonable from the above description.

DESCRIPTION OF SYMBOLS 1 ... Light-emitting device 10 ... Light-emitting element 21 ... 1st fluorescent substance 22 ... 2nd fluorescent substance 30 ... Sealing member 40 ... Case 50 ... Die pad 60- ..Wire 70: Electric wiring

Claims (1)

A light emitting element;
A sealing member for sealing the light emitting element;
A phosphor that is contained in at least a part of the sealing member, absorbs part of the light from the light emitting element, and converts the light into a light having a wavelength different from the emission wavelength of the light emitting element;
With
The light emitting element and the phosphor are similar colors,
The emission peak wavelength of the phosphor is located in a range of less than 20 nm on the long wavelength side from the peak wavelength of the light emitting element.

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