JP2007091808A - Emitted light color-converting member - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an emitted light color-converting member which does not deteriorate the characteristics of a calcium sulfide fluorescent substance on firing in spite of containing a calcium sulfide fluorescent substance. <P>SOLUTION: This emitted light color-converting member which emits a red fluorescent light, when irradiated with blue light, is characterized in that glass and an inorganic fluorescent substance are contained in a mass ratio of 99.99:0.01 to 70:30; the glass comprises 45 to 55 mass% of SiO<SB>2</SB>, 3 to 7 mass% of B<SB>2</SB>O<SB>3</SB>, 11 to 15 mass% of CaO, 23 to 27 mass% of BaO, 4 to 6 mass% of Al<SB>2</SB>O<SB>3</SB>, and 1 to 3 mass% of ZnO; and the inorganic fluorescent substance comprises a calcium sulfide fluorescent substance (CaS: Eu<SP>2+</SP>). <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a light emitting color conversion member that converts part of blue light emitted from a blue light emitting diode (blue LED) or the like into red light.

In an LED element that converts a wavelength using a phosphor, for example, a phosphor powder is mixed with an organic binder resin or the like (mold resin) that seals the light emitting surface of the LED chip, and the LED is then processed. A part or all of the light emitted from the chip is absorbed and converted to a desired wavelength. For example, Patent Document 1 proposes an LED element having a coating material in which a calcium sulfide phosphor (CaS: Eu ²⁺ ) is dispersed in a transparent resin. This element converts a part of blue light emitted from a blue LED into red light.

However, there is a problem that the mold resin constituting the LED element deteriorates due to heat generation of the LED chip or irradiation with high-output short-wavelength (blue to ultraviolet) light, causing discoloration and the like. Therefore, it has been proposed to fix phosphor powder with glass instead of resin. (For example, Patent Document 2)
JP 2001-267632 A JP 2003-258308 A

  The luminescent color conversion member disclosed in Patent Document 2 is produced by firing a mixed powder of a glass powder having a high softening point and a phosphor powder. The conversion member produced in this way has a feature that glass as a base material is not deteriorated by heat or irradiation light.

  However, although the luminescent color conversion member can be produced without any problem if it is a phosphor having high heat resistance such as a YAG phosphor, in the case of a phosphor having low heat resistance, for example, the above-mentioned calcium sulfide phosphor, the fluorescent light is not emitted during firing. The body may be deteriorated.

  An object of the present invention is to provide a luminescent color conversion member that does not deteriorate the characteristics of the phosphor during firing despite containing the calcium sulfide phosphor.

  As a result of various experiments, the present inventors have found that, if a glass having a specific composition is used, even if a calcium sulfide phosphor is used, the characteristics thereof are not deteriorated, and the present invention is proposed.

That is, the luminescent color conversion member of the present invention is a luminescent color conversion member that emits red fluorescence when irradiated with blue light, and the mass ratio of glass and inorganic phosphor is 99.99: 0.01 to 70:30. The glass is in mass%, SiO ₂ 45-55%, B ₂ O ₃ 3-7%, CaO 11-15%, BaO 23-27%, Al ₂ O ₃ 4-6%, ZnO 1 The inorganic phosphor is composed of calcium sulfide phosphor (CaS: Eu ²⁺ ).

Since the conversion member of the present invention uses a glass having a specific composition, the conversion member can be manufactured without deteriorating the characteristics of the calcium sulfide phosphor (CaS: Eu ²⁺ ) having low heat resistance. In addition, since the glass serving as a base material is stable against heat and irradiation light, it is possible to manufacture a highly reliable and long-life LED element without discoloration. In addition, since the calcium sulfide phosphor (CaS: Eu ²⁺ ) is not directly exposed to the atmosphere, deterioration due to the influence from the atmosphere can be prevented.

  When emitted with blue (400 to 500 nm) excitation light, the luminescent color conversion member of the present invention absorbs at least part of it and converts it into red (600 to 780 nm) fluorescence. And the blue light which permeate | transmits a member, and the red light which arises by wavelength conversion combine, and emits red purple-blue purple light. The luminescent color conversion member of the present invention is a sintered body of glass powder and phosphor powder, and has, for example, a plate-like form.

  The light emitting color conversion member of the present invention can be combined with a blue LED to obtain an LED device that emits reddish purple to blue purple light. Specifically, it is obtained by fixing the plate-like light emitting color conversion member of the present invention to the upper open part of the package on which the blue LED chip is mounted.

The glass used in the present invention has a role as a medium for stably holding the inorganic phosphor, and is composed of SiO ₂ , B ₂ O ₃ , CaO, BaO, Al ₂ O ₃ , and ZnO components. The content of is SiO ₂ 45-55%, B ₂ O ₃ 3-7%, CaO 11-15%, BaO 23-27%, Al ₂ O ₃ 4-6%, ZnO 1-3 by mass percentage. %. The reason for determining the above range is as follows.

SiO ₂ is a component that forms a glass network. When the content is less than 45% by mass, chemical durability tends to deteriorate. On the other hand, if it exceeds 55% by mass, the sintering temperature becomes high and the phosphor tends to deteriorate. The preferred range of SiO ₂ is 48 to 52%.

B ₂ O ₃ is a component that significantly improves the meltability by lowering the melting temperature of the glass. When the content is less than 3% by mass, it is difficult to obtain the effect. On the other hand, when it exceeds 7 mass%, chemical durability tends to deteriorate. A more preferable range of B ₂ O ₃ is 4 to 6%.

  CaO is a component that improves the meltability by lowering the melting temperature of the glass. When the content is less than 11% by mass, it is difficult to obtain the effect of improving the meltability. When the content is more than 15% by mass, the chemical durability tends to deteriorate. A more preferable range of CaO is 12 to 14%.

  BaO is a component that improves the meltability by lowering the melting temperature of the glass and suppresses the reaction with the phosphor. When the content is less than 23% by mass, the reaction suppression effect with the phosphor tends to be reduced. On the other hand, when it exceeds 27 mass%, chemical durability tends to deteriorate. A more preferable range of BaO is 24 to 26%.

Al ₂ O ₃ is a component that improves chemical durability. When the content is less than 4%, chemical durability tends to deteriorate. On the other hand, when it exceeds 6 mass%, the meltability of the glass tends to deteriorate. A more preferable range of Al ₂ O ₃ is 4.5 to 5.5%.

  ZnO is a component that improves the meltability by lowering the melting temperature of the glass. When the content is less than 1%, the meltability is deteriorated. If it exceeds 3% by mass, the chemical durability tends to deteriorate. A more preferable range of ZnO is 1.5 to 2.5%.

The inorganic phosphor used in the present invention is a calcium sulfide phosphor (CaS: Eu ²⁺ ) which is a phosphor having low heat resistance. This phosphor has low chemical durability, and is deteriorated by moisture, heat, and light when used alone for a long time. Therefore, it is usually used in a vacuum or a rare gas. However, when the sintered body is made of glass powder, the phosphor is not directly exposed to the atmosphere, and deterioration due to the influence from the atmosphere hardly occurs.

  In addition to the above phosphors, other phosphors such as YAG phosphors, oxide phosphors, nitride phosphors, oxynitride phosphors, etc. may be used in combination.

  Moreover, in this invention, it is preferable that the mixing ratio of glass and inorganic fluorescent substance exists in the range of 99.99: 0.01-70: 30 by mass ratio. The energy conversion efficiency of the conversion member varies depending on the type and content of phosphor particles dispersed in the glass and the thickness of the conversion member. The phosphor content and the thickness of the conversion member may be adjusted so as to optimize the energy conversion efficiency, but if the phosphor is too much, it becomes difficult to sinter and the porosity increases, It becomes difficult for the excitation light to be efficiently irradiated onto the phosphor, and the mechanical strength of the conversion member is likely to decrease. On the other hand, if the amount is too small, it becomes difficult to emit light sufficiently. Therefore, the content ratio of the glass and the phosphor is preferably adjusted in the range of 99.99: 0.01 to 70:30, more preferably 99.95: 0.05, as described above. It is preferable to adjust in the range of ˜80: 20, particularly 99.92: 0.08 to 85:15.

  A method for producing the luminescent color conversion member of the present invention will be described below.

  First, the glass powder having the above composition and the calcium sulfide phosphor powder are mixed in a mass ratio of 99.99: 0.01 to 70:30.

  Next, the obtained mixed powder is formed into a predetermined shape. In order to produce a conversion member with high energy conversion efficiency, it is important that the thickness is thin and the phosphor is uniformly dispersed in the member. In order to produce such a member, a green sheet may be produced using the above mixed powder. In order to produce a green sheet, a binder, a plasticizer, a solvent and the like are used together with the glass powder and the phosphor powder.

  The proportion of the glass powder and inorganic phosphor powder in the green sheet is generally about 50 to 80% by mass.

  The binder is a component that increases the film strength after drying and imparts flexibility, and the content thereof is generally about 0.1 to 30% by mass. As the binder, for example, polyvinyl butyral resin, methacrylic acid resin and the like can be used, and these can be used alone or in combination.

  The plasticizer is a component that controls the drying speed and imparts flexibility to the dry film, and the content is generally about 0 to 10% by mass. As the plasticizer, for example, dibutyl phthalate, butyl benzyl phthalate or the like can be used, and these can be used alone or in combination.

  The solvent is a material for slurrying the material, and its content is generally about 1 to 30% by mass. As the solvent, for example, toluene, methyl ethyl ketone or the like can be used alone or in combination.

  As a method for producing a green sheet, a predetermined amount of a binder, a plasticizer, a solvent and the like are added to the mixed powder of the glass powder and the phosphor powder to form a slurry. Next, the slurry is formed on a film of polyethylene terephthalate (PET) or the like by a doctor blade method. Subsequently, after the sheet molding, the organic solvent binder can be removed by drying to obtain a green sheet.

  Subsequently, the mixed powder formed into a predetermined shape is fired. When formed into a green sheet, the green sheet is cut to a desired size, laminated in multiple layers to the desired thickness, and then integrated by thermocompression to produce a laminate, which is then baked on an alumina setter to emit light. A conversion member is obtained. When deformation is confirmed in the luminescent color conversion member after firing, the deformation can be suppressed by firing in advance while sandwiching the green sheet with porous ceramics or the like. The firing temperature is preferably 700 to 1000 ° C. The reason is that it becomes difficult to obtain a dense sintered body at a temperature lower than 700 ° C., and the glass and calcium sulfide phosphor easily react at a temperature higher than 1000 ° C.

  In this way, a chemically stable luminescent color conversion member can be produced. In particular, when produced using a green sheet, it is possible to obtain a light emitting color conversion member that is chemically stable, large in size, thin in thickness, uniform in thickness, and high in energy conversion efficiency.

  Hereinafter, the present invention will be described based on examples.

First, SiO ₂ 50% by mass _{percentage, B 2 O 3 5%,} CaO 13%, BaO 25%, Al 2 O 3 5%, so that the composition containing 2% ZnO, the glass raw material of various oxides After mixing and mixing uniformly, it was put in a platinum crucible and melted at 1400 ° C. for 2 hours to obtain a homogeneous glass. This was pulverized with alumina balls and classified to obtain glass powder having an average particle diameter of 2.5 μm.

  Furthermore, calcium sulfide phosphor powder was added to the prepared glass powder in a mass ratio of 95: 5 and mixed to prepare a mixed powder.

  Next, 30% by mass of methacrylic acid resin as a binder, 3% by mass of dibutyl phthalate as a plasticizer, and 20% by mass of toluene as a solvent are added to 100% by mass of the mixed powder, and mixed to prepare a slurry. did. Subsequently, the slurry was formed into a sheet on a PET film by a doctor blade method and dried to obtain a green sheet having a thickness of 50 μm. Subsequently, the green sheet was cut into a size of 100 × 100 mm, three sheets were laminated, and integrated by thermocompression bonding to produce a laminate.

  Then, it put on the alumina setter and baked at 800 degreeC in the electric furnace, and produced the smooth plate-shaped luminescent color conversion member.

  The luminescent color conversion member thus obtained was irradiated with blue light from behind the member, and violet light, which is a mixed color of red light and transmitted blue light by calcium sulfide, was obtained. Moreover, when the energy conversion efficiency was measured, the energy conversion efficiency was 13%.

  The energy conversion efficiency depends on the energy (a) of the light source, the energy (b) of the light having the same wavelength as the light source transmitted through the luminescent color conversion member, and the wavelength of the light source in the luminescent color conversion member using a spectrophotometer. The energy of the converted light was determined by measuring (c) and calculating from c / (ab) × 100 (%).

Claims (1)

An emission color conversion member that emits red fluorescence when irradiated with blue light, comprising glass and an inorganic phosphor in a mass ratio of 99.99: 0.01 to 70:30, wherein the glass is in mass%, _{SiO 2 45~55%, B 2 O} 3 3~7%, CaO 11~15%, BaO 23~27%, Al 2 O 3 4~6%, consists 1 to 3% ZnO, inorganic phosphor sulfide A luminescent color conversion member comprising a calcium phosphor (CaS: Eu ²⁺ ).