JP2018146656A - Phosphor lens and light emission device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a phosphor lens which is applicable to a white light emission device and which enables the miniaturization of the device by reducing the number of components of the device.SOLUTION: There is provided a phosphor lens which includes, as a main component, a complex oxide having ABOtype garnet structure in which one or more elements selected from a group consisting of at least Y, Lu, Sc and La, and Ce are placed at an A site position, and Al is placed at a B side position; includes, as a sug component, at least one oxide selected from a group consisting of a silicon oxide, a zirconium oxide, a titanium oxide and a hafnium oxide in a range of larger than 0 and less than 100 ppm as a mass ratio with respect to the complex oxide; and is made of a sintered body of a transparent ceramic having a total light transmittance of 50% or more at wavelength of 600 nm in optical length of 10 mm.SELECTED DRAWING: Figure 2

Description

  INDUSTRIAL APPLICABILITY The present invention is suitably used as a wavelength converter or a member for illumination, and is a phosphor lens that emits fluorescence in the visible range when excited by light from a semiconductor laser (LD light) or light from a light emitting diode (LED light), and the fluorescence thereof. The present invention relates to a light emitting device using a body lens.

  A phosphor made of a crystal having a garnet structure has been known for a long time, and among them, the YAG: Ce fluorescent powder is the most famous, and has been widely used as a material for an illumination member that produces white light in combination with a blue LED. However, in the past, this phosphor was often made into a powder state and supported by a sealing agent to be used as a phosphor structure.

  There are two known methods for supporting fluorescent powder. One is a method of sealing with a silicone sealant, and the other is a method of sealing with glass. However, the method of sealing with a silicone sealant could not be used in a high temperature environment of 180 ° C. or higher, which is the heat resistant temperature of the silicone resin. Further, in the method of sealing with glass, when heating and cooling with a peak temperature of 300 ° C. is repeated, there is a problem that heat cycle stress cracking due to a difference in linear expansion coefficient between the fluorescent powder and the glass occurs.

In the past, a structure (bulk body) made only of a material that can be a phosphor has been studied. For example, Japanese Patent Laid-Open No. 10-67555 (Patent Document 1) describes Al ₂ O as a representative example of YAG. ₃ and Y ₂ O ₃ as main components and a garnet crystal structure, and contains at least one metal oxide, and the standard production Gibbs energy (ΔGf °) of the metal oxide is Al ₂ O ₃ standard production Gibbs A translucent ceramic having a negative value larger than energy and a metal oxide content of 5 ppm or more and 20000 ppm or less, having an average particle size of 25 μm or less and at least twice the average particle size A translucent ceramic having a homogeneous structure, excellent mechanical strength, and excellent transparency is disclosed.
However, in Patent Document 1, it is merely disclosed as an arc tube having transparency, mechanical strength, and heat resistance, not as a phosphor.

  Production of a structure consisting only of phosphors, that is, transparent ceramic phosphor material (bulk body) seems to be difficult industrially, and a method of dispersing and supporting ceramic phosphors in other transparent ceramic base materials has long been adopted. I came.

  For example, Japanese Patent No. 4122791 (Patent Document 2) discloses a light-emitting device including a ceramic substrate having one or more storage recesses formed on the surface thereof and a light-emitting element mounted on the bottom surface of the storage recesses. A ceramic that contains at least one of a wavelength converting material that emits light having a wavelength different from that of the received light or a light absorbing material that absorbs light of a predetermined wavelength in the ceramic substrate and faces away from the bottom surface of the housing recess A light emitting device is disclosed in which the back surface of the substrate is a light emitting surface. As a result, the ceramic substrate has translucency in the visible light region and is formed by containing a wavelength conversion substance, for example, a YAG phosphor, so that it has excellent light resistance, heat resistance, heat dissipation, and aging. In addition, it is possible to provide a light-emitting device that can suppress variations and can improve color mixing of light.

In addition, although it is a small number, the examination of the structure which consists only of fluorescent substance, ie, a transparent ceramic fluorescent material (bulk body), is tried continuously after that. For example, as another example of garnet-type transparent ceramics, Japanese Patent No. 5462515 (Patent Document 3) includes (1) a general formula RE ₃ M ₅ O ₁₂ (where RE is a general formula Pr _x Lu _3-x or Ce _x Lu _3-x (where 0.0001 ≦ x ≦ 0.3000), and M represents an oxidation represented by at least one of Sr, Al, Ga, Sc, Zr, and Hf). And (2) a transparent ceramic comprising a garnet-type polycrystalline body containing (2) at least one of a) Si or b) Ca and Mg and Si in an amount of 100 to 10,000 ppm by weight in terms of oxide is excellent. It is disclosed that it has transparency, and in particular, it is disclosed that a green fluorescent property having a fluorescence center wavelength of 550 nm can be obtained with a composition of Ce _x Lu _3-x .
However, the transparent ceramics disclosed in Patent Document 3 are based on a scintillator for a radiation detector, and are not suitable for illumination applications that require the emission of white light.

  Further, in the industry of high-intensity white light LED (light emitting diode), a structure made of only phosphors, that is, not a transparent ceramic phosphor material (bulk body), A method of laminating a fluorescent layer with a transparent ceramic layer has been studied.

  In that flow, for example, Japanese Patent No. 5490407 (Patent Document 4) describes a phosphor having a polycrystalline ceramic structure having a doped YAG type phosphor used in a white light-emitting device. The phosphor is embedded in a ceramic matrix having non-light emitting polycrystalline alumina so as to form a ceramic matrix composite, and the ceramic matrix composite has grain boundaries and has a grain boundary of 80 to 99.99 vol. % Alumina, 0.01 to 20 vol. % Of a phosphor having a polycrystalline ceramic structure is disclosed. As a result, a material having a garnet structure such as YAG is a compound with a very narrow composition range, so that a heterogeneous phase appears, so it was difficult to produce a transparent YAG body. Shows the structure of a composite-type transparent ceramic phosphor material that can be properly processed and adopted as a matrix, so that the residual pore size can be reduced and the backscattering loss due to pores and foreign phases can be reduced. It was done.

  Further, in the text of US Pat. No. 6,057,028, additional advantages are disclosed in the form of a luminescent ceramic matrix composite, but the ceramic element is molded, ground, machined, hot stamped or polished to finish in the desired shape. ing. That is, it is shown that the luminescent ceramic matrix composite material itself is formed into a lens shape such as a dome lens, or the upper portion of the element is textured randomly or in the shape of a Fresnel lens.

  Japanese Patent No. 5766683 (Patent Document 5) discloses a luminescent ceramic composite laminate, which is substantially at least one wavelength conversion ceramic layer containing a luminescent material containing YAG: Ce synthesized by fluid system thermochemical synthesis. At least one non-light emitting layer of a transparent ceramic material, the wavelength converting ceramic layer and the non-light emitting layer being laminated in the thickness direction, and the light emitting ceramic composite laminate has a wavelength conversion of at least 0.650 A luminescent ceramic composite laminate for use in white light emitting devices having efficiency (WCE) is disclosed. Here, the wavelength converting ceramic layer is thin, but the substantially transparent non-light emitting layer laminated thereon is made into a “substantially hemispherical” shape which is a general shape, or processed into several other modifications. An example is disclosed.

JP-A-10-67555 Japanese Patent No. 4122791 Japanese Patent No. 5462515 Japanese Patent No. 5490407 Japanese Patent No. 5766683

From the above prior art documents, it can be seen that the conventional wavelength conversion member (phosphor) has three technical problems for white light emitting devices.
The first point is that it is difficult to produce a bulk body made of a transparent ceramic phosphor material alone, especially when the phosphor material has a garnet structure such as YAG. .
The second point is a problem when the ceramic phosphor material is supported by another transparent ceramic bulk material. In general, when the ceramic phosphor material is dispersed and supported in another transparent matrix, the concentration of the activator such as Ce in the dispersed ceramic phosphor material is improved in order to improve the wavelength conversion efficiency of the entire structure. Need to be raised. For example, in the example disclosed in Patent Document 4, the lower limit vol% of cerium for substituting yttrium in YAG ceramics is 2%. This concentration is quite high and the risk of causing concentration quenching and temperature quenching is significantly increased.
Third, after all, it is difficult to provide a bulk body made of a transparent ceramic phosphor material alone. For example, the lens function required for a light emitting device such as a white LED device is separated from the wavelength conversion member. It is a point that needs to be prepared. In this case, the number of parts increases and it is difficult to reduce the size of the light emitting device.

  The present invention has been made in view of the above circumstances, and a phosphor lens that can be applied to a white light-emitting device, can reduce the number of parts of the device, and can be downsized, and a light-emitting device using the same. The purpose is to provide.

In order to achieve the above object, the present invention provides the following phosphor lens and light emitting device.
[1] A ₃ B ₅ O ₁₂ type garnet structure in which at least one element selected from the group consisting of Y, Lu, Sc, and La and Ce enter at the A site position and at least Al enters at the B site position As a mass ratio of at least one oxide selected from the group consisting of silicon oxide, zirconium oxide, titanium oxide, and hafnium oxide as a main component. A phosphor lens comprising a sintered body of a transparent ceramic having a total light transmittance of 50% or more at a wavelength of 600 nm with an optical path length of 10 mm, which is contained in a range of greater than 0 and less than 100 ppm.
[2] The phosphor lens according to [1], in which blue excitation light is incident and emits white light.
[3] The composite oxide has the following formula (1):
_{(La x Lu y Y z Ce} w Sc v Q 1-xyzwv) 3 (Al p Ga q Sc r) 5 O 12 (1)
(Wherein x is from 0 to 0.1, y is from 0 to 1, z is from 0 to 1, w is from 0.0001 to 0.005, v is from 0 to 0.04, x + y + z + w + v ≦ 1 And at least one of y and z is greater than 0. p is 0.4 or more and 1 or less, q is 0 or more and 0.55 or less, r is 0 or more and 0.2 or less, and p + q + r = 1. Q is at least one rare earth element selected from the group consisting of Gd, Tb and Pr.)
The phosphor lens according to [1] or [2], represented by:
[4] When the point light source is arranged on the optical axis on the one lens surface side as the thickness distribution in the radial direction of the lens, and excitation light is incident on the one lens surface from the point light source, The phosphor lens according to [3], which is a convex lens having a thickness distribution in which all the optical path lengths of the transmitted excitation light are equal.
[5] The phosphor lens according to [1] or [2], which has a Ce concentration gradient in the complex oxide in a lens radial direction around the optical axis of the phosphor lens.
[6] The phosphor lens according to [5], wherein the color tone of the emitted light is uniform in the exit plane by a combination of the Ce density gradient in the lens radial direction and the thickness distribution in the lens radial direction.
[7] The phosphor lens according to [6], wherein one lens surface is a flat surface and the other lens surface is a convex lens surface, a Fresnel lens surface, a concave lens surface, or an aspheric lens surface.
[8] The phosphor lens according to any one of [1] to [7], wherein the surface of the lens surface on the outgoing light side is a rough surface having fine irregularities or a pyramid texture.
[9] A light-emitting device including the phosphor lens according to any one of [1] to [8] and a light source that makes excitation light incident on one lens surface of the phosphor lens.

  According to the present invention, since a garnet-type composite oxide having a specific composition is used, a bulk body applicable to a white light emitting device made of a transparent ceramic phosphor alone can be easily manufactured, and further, its lens has a lens function with its outer surface as a predetermined shape. The phosphor lens can be made uniform in the lens exit surface of the color tone of the emitted light, and the number of components can be reduced, and the light emitting device can be reduced in size, and the light emitting device using the same Can provide.

It is a schematic sectional drawing which shows the structural example 1 of the fluorescent substance lens which concerns on this invention. It is a schematic sectional drawing which shows the structural example 2 of the fluorescent substance lens which concerns on this invention. It is a schematic sectional drawing which shows the structural example 3 of the fluorescent substance lens which concerns on this invention.

[Phosphor lens]
The phosphor lens according to the present invention will be described below.
Phosphor lens according to the present invention, at least Y at the A site position, Lu, Sc, contains the one or more elements and Ce selected from the group consisting of La, at least Al enters B-site positions A ₃ B includes a complex oxide having a ₅ O ₁₂ type garnet structure as a main component, silicon oxide as a secondary component, zirconium oxide, said composite at least one oxide selected from the group consisting of titanium oxide and hafnium oxide It consists of a sintered body of transparent ceramics having a total light transmittance of 50% or more at a wavelength of 600 nm with an optical path length of 10 mm, which is contained in a range of greater than 0 and less than 100 ppm as a mass ratio to the oxide. The garnet structure is a cubic crystal having a space group of Ia-3d, and when sintered and densified, it has high transparency without causing birefringence scattering and can be made into a phosphor. This is the most appropriate object of the present invention.

  Further, the phosphor lens of the present invention emits fluorescence by excitation light incident on one lens surface, and refracts the fluorescence and excitation light transmitted through the lens from the other lens surface by the other lens surface. The light path is controlled and emitted.

Here, the composite oxide has the following formula (1):
_{(La x Lu y Y z Ce} w Sc v Q 1-xyzwv) 3 (Al p Ga q Sc r) 5 O 12 (1)
(Wherein x is from 0 to 0.1, y is from 0 to 1, z is from 0 to 1, w is from 0.0001 to 0.005, v is from 0 to 0.04, x + y + z + w + v ≦ 1 And at least one of y and z is greater than 0. p is 0.4 or more and 1 or less, q is 0 or more and 0.55 or less, r is 0 or more and 0.2 or less, and p + q + r = 1. Q is at least one rare earth element selected from the group consisting of Gd, Tb and Pr.)
It is preferable that it is represented by these.

  Note that La, Lu, Y, Ce, Sc, and Q are collectively referred to as elements at the A site. Al, Ga, and Sc are collectively referred to as elements at the B site.

  Among the elements at the A site position in the above formula (1), Ce is promptly emitted while emitting fluorescence having a wavelength of 480 to 710 nm by excitation with LD light or LED light having a peak wavelength in the wavelength range of 410 to 480 nm. Is an element that transitions to a low energy state, and is an essential element for the present invention.

  A combination of La and Y (ie, when x is greater than 0, y is 0, and z is greater than 0), and optionally a combination including Lu (ie, x, y, z are both 0) Greater than), or only Lu (ie, x and z are 0 and y is greater than 0), and a combination of Lu and Y (not including La) (ie, x is 0 and y and z are greater than 0), the peak wavelength of the fluorescence emitted by the excited Ce is changed in the range of 535 to 575 nm by changing the concentration ratio of each component in the combination. It is an element that can be adjusted. Therefore, it is another essential element group for the present invention.

  Sc is an element that occupies both the A site position and the B site position. A preferable effect of Sc is that it can be accommodated at both the A site position and the B site position due to the characteristics of the ionic radius. As mentioned in the above-mentioned Patent Document 4, since a material having a garnet structure is a compound having a very narrow composition, it is difficult to produce a transparent ceramic phosphor because a different phase appears. However, when Sc is added here, when the element at the A site position is insufficient, Sc is selectively filled into the A site position, and when the element at the B site position is insufficient, Sc is present at the B site position. The automatic compensation effect of the A / B site ratio that is selectively filled can be exhibited. As a result, a slight deviation in the blending ratio is automatically corrected by the addition of Sc, so that the width of the garnet composition is substantially widened and the production of the transparent ceramic phosphor becomes easy. Sc is a transparency improving element capable of increasing the total light transmittance at a wavelength of 600 nm to 50% or more. Furthermore, it is an element that can broaden the spectrum band of the fluorescence emitted by Ce, and is another important element for the present invention.

  Q is an element group composed of Gd, Tb, and Pr that can adjust the fluorescence characteristics of the transparent ceramic phosphor material. Specifically, Gd is an element that can broaden the peak wavelength of fluorescence emitted by Ce on the long wave side, and is an important element for the present invention.

  Further, Tb is an element that can improve the intensity of fluorescence emitted by Ce or shift the peak wavelength of fluorescence to the short wave side depending on the amount of addition, and is an important element for the present invention. is there.

  Pr is an element that can improve the intensity of fluorescence emitted by Ce depending on the amount of addition, and is another important element for the present invention.

  Among the elements at the B site position in the above formula (1), Al is an element that controls the heat resistance and heat conductivity of the transparent ceramic phosphor material, and is an essential element for the present invention.

  Ga is an element that can lower the production temperature of the transparent ceramic phosphor material and shift the peak wavelength of fluorescence emitted by Ce to the short wave side, and is an important element for the present invention.

  The fluorescent material of the present invention contains a composite oxide represented by the above formula (1) as a main component. Furthermore, as a subcomponent, at least one oxide material selected from the group consisting of silicon oxide, zirconium oxide, titanium oxide, and hafnium oxide is greater than 0 and less than 100 ppm relative to the mass of the composite oxide. Included in range. This subcomponent is a component that can make the total light transmittance at a wavelength of 600 nm at an optical path length of 10 mm 50% or more, and is an element group that is particularly important for the present invention even though it is extremely small.

  Here, to contain as a main component means to contain 90% by mass or more of the composite oxide represented by the above formula (1). The content of the composite oxide represented by the formula (1) is preferably 99% by mass or more, more preferably 99.9% by mass or more, and preferably 99.99% by mass or more, It is especially preferable that it is 99.999 mass% or more.

  The transparent ceramic phosphor material of the present invention is composed of the above main component and subcomponent, but may further contain other elements. Examples of other elements include ytterbium (Yb), and various impurity groups typically include calcium (Ca), magnesium (Mg), phosphorus (P), tungsten (Ta), and molybdenum (Mo). it can.

  The content of other elements is preferably 10 parts by mass or less, more preferably 0.1 parts by mass or less, and 0.001 part by mass when the total amount of elements at the A site position is 100 parts by mass. It is particularly preferred that the amount is not more than part (substantially zero).

  In Formula (1), w regarding Ce is in the range of 0.0001 to 0.005, and preferably 0.001 to 0.004. When w is in this range, the intensity of fluorescence emitted by the excited Ce can be secured. When w is less than 0.0001, since the concentration of Ce excited by LD light or LED light having a peak wavelength in the range of 410 to 480 nm is too thin, the intensity of fluorescence emitted by the excited Ce is low. descend. On the other hand, if w is more than 0.005, the fluorescence intensity starts to decrease again due to the concentration quenching of Ce.

  In the formula (1), x relating to La is in the range of 0 to 0.1, preferably 0 to 0.05. When x is in this range, the intensity of the fluorescence emitted by the excited Ce can be secured. When x exceeds 0.1, part of the energy of Ce excited by LD light or LED light having a peak wavelength in the range of 410 to 480 nm is trapped equipotentially, and fluorescence emitted by Ce. This is not preferable because the strength of the steel is reduced. Furthermore, since the lattice strain in the crystal structure also increases, it becomes difficult to manufacture with good characteristic reproducibility, which is not preferable.

  In the formula (1), y related to Lu is in the range of 0 to 1, preferably 0 to 0.996. When y is in this range, an effect of shifting the peak wavelength of the fluorescence emitted by the excited Ce to the short wave side can be obtained. Since the peak wavelength of the fluorescence emitted by Ce monotonously excited in proportion to the increase of y can be shifted to the short wave side, it is preferable to adjust the amount of y according to the desired design wavelength.

  In the formula (1), z related to Y is in the range of 0 to 1, preferably 0 to 0.996. When z is in this range, the intensity of the fluorescence emitted by the excited Ce can be increased, and furthermore, the fluorescence intensity characteristic is stabilized, so that it can be manufactured with good reproducibility. If z is more than 1, the intensity of fluorescence emitted by the excited Ce decreases, which is not preferable.

  In formula (1), v and r related to Sc are 0 ≦ v ≦ 0.04 and 0 ≦ r ≦ 0.2, respectively, preferably 0 <v ≦ 0.04 and 0 <r ≦ 0.2. is there. When v is in this range, the total light transmittance at a wavelength of 600 nm with an optical path length of 10 mm is 50% or more. If v exceeds 0.04, the total light transmittance at a wavelength of 600 nm is reduced to less than 50%, which is not preferable. On the other hand, when r is in the above range, an effect of broadening the spectral bandwidth of the fluorescence emitted by Ce can be obtained. When r exceeds 0.2, a part of the energy of Ce excited by LD light or LED light having a peak wavelength in the range of 410 to 480 nm is relaxed to a low energy state by a transition that does not emit fluorescence. Therefore, it is not preferable.

  In Formula (1), p regarding Al is in the range of 0.4 to 1. When p is in this range, good heat resistance and thermal conductivity can be obtained. If p falls below 0.4, the heat resistance and thermal conductivity are significantly deteriorated, which is not preferable.

  In Formula (1), q regarding Ga is in the range of 0 or more and 0.55 or less. When q is in this range, the fluorescence intensity can be efficiently secured. When q exceeds 0.55, a part of the energy of Ce excited by LD light or LED light having a peak wavelength in the range of 410 to 480 nm is relaxed to a low energy state by a transition that does not emit fluorescence. Therefore, it is not preferable.

  In the formula (1), x + y + z + w + v is 1 or less. When it is not 1, Q is added with at least one rare earth element selected from the group consisting of Gd, Tb, and Pr.

  Further, in the formula (1), y and z cannot be 0 (that is, no addition) at the same time. For example, the main phase of the composite oxide includes a garnet structure including at least Y, Ce, and Al, a garnet structure including Lu, Ce, and Al, or including La, Y, Ce, and Al. A fluorescent material made of transparent ceramics having a garnet structure is preferable. By doing so, the peak wavelength of the fluorescence emitted by Ce can be reliably adjusted in the range of 535 to 575 nm.

By the way, in the complex oxide represented by the formula (1), the total number of moles of the element group at the A site position and the total number of moles of the element group at the B site position are in a ratio of 3 to 5. However, as a result of proceeding with trial production, the ratio of the total number of moles of the element group at the A site position to the total number of moles of the element group at the B site position (mole ratio of A site and B site, B / A) is 3/5 times. Is 1 or more, preferably 1 or more and 1.04 or less, since it was confirmed that the total light transmittance at a wavelength of 600 nm can be secured by 50% or more. In order to set 3/5 times the molar ratio (B / A) between the A site and the B site to 1 or more, preferably 1 or more and 1.04 or less, when each raw material is initially weighed, for example, at the position of the A site Basic ratio of the total number of moles of the element group at the B site position so that the ratio of the total number of moles of the element group to the total mole number of the element group at the A site position in the basic composition (formula (1)) is less than 100%. It is good to weigh by intentionally offset so that the ratio of the element group at the B site position in the composition (formula (1)) to the total number of moles slightly exceeds 100%.
That is, the ratio of the total number of moles of the element group at the A site position and the total number of moles of the element group at the B site position is the molar amount from the actual weighed value of each element (in the case of an oxide, the oxide of each element). It can be determined by calculating the rate.

  If the sintered body of the transparent ceramics defined by the above formula (1) is used, the main phase is a cubic crystal having a garnet lattice (garnet-type cubic crystal), preferably a garnet-type cubic crystal. Become. The main phase means that the garnet cubic crystal as a crystal structure accounts for 90% by volume or more, preferably 95% by volume or more, more preferably 99% by volume or more, and particularly preferably 99.9% by volume or more. Say. It is preferable that the crystal structure is a cubic crystal because the influence of scattering due to birefringence is eliminated and the total light transmittance at a wavelength of 600 nm is improved.

  Furthermore, the fluorescent material made of the transparent ceramic sintered body of the present invention has a cubic phase having a garnet lattice (garnet-type cubic crystal), preferably a garnet-type cubic crystal. The essential element Ce (cerium) can diffuse to every corner of the main phase of the garnet-type cubic crystal, and the segregation coefficient of cerium in the cubic crystal with garnet lattice is almost 1, so cerium segregates at the grain boundary. Therefore, a fluorescent material that does not locally distribute a high concentration in the material in the form of grain boundary segregation or a different phase (second phase) is obtained.

In addition, the subcomponent composed of at least one oxide material selected from the group consisting of silicon oxide, zirconium oxide, titanium oxide, and hafnium oxide is limited to a range of less than 100 ppm as a mass ratio with respect to the composite oxide. As a result, the amount of Ce diffused into the sub-component can be extremely limited, so that Ce is diffused and distributed to every corner of the fluorescent material. Since it can be set as the fluorescent material which does not carry out high concentration distribution locally in the material in the form of (2nd phase), it is preferable.
As described above, when Ce is not locally distributed at a high concentration in the fluorescent material of the present invention, an improvement in thermal quenching resistance can be expected.

  According to the above fluorescent material, the total light transmittance at a wavelength of 600 nm at an optical path length of 10 mm is 50% or more, and LD light or LED light having a peak wavelength in the wavelength range of 410 to 480 nm is incident on this fluorescent material. When a part of the LD light or LED light is transmitted to the side opposite to the incident side and the remaining LD light or LED light is absorbed, the light has a wavelength of 480 to 710 nm and has a peak wavelength (the fluorescence intensity becomes maximum). When the fluorescence intensity that emits fluorescence having a wavelength of 535 to 575 nm and the maximum intensity when the fluorescence is decomposed for each wavelength is defined as 100%, it is 60% or more of the maximum intensity. A phosphor lens made of a sintered body of transparent ceramics having a wavelength band width of 80 nm or more for emitting fluorescence can be provided.

  The phosphor lens of the present invention is a transparent material (transparent ceramic) having the above-described configuration, and can further impart a lens function by making the lens surface into a predetermined shape. Here, this is referred to as a lens shape function.

As the simplest lens shape function, there is a case where the phosphor lens has a convex shape.
That is, the transparent ceramic used in the present invention is excited by blue excitation light (LD light or LED light) having a peak wavelength in the range of 410 to 480 nm, and part of the light is converted to fluorescence having a wavelength of 480 to 710 nm. It is a material having a function of converting, mixing with a blue excitation light component that has not been converted, and emitting (emitting) white light to the outside. The white light referred to in the present invention is white light having a color temperature included in 2700K to 6500K defined in ANSI C78.377.

  Here, the ratio of the wavelength conversion of the blue excitation light component is proportional to the optical path length. Therefore, if the optical path length is different for each position of the light component emitted from the phosphor lens, mixed color tone unevenness occurs. On the other hand, the light component emitted from the LD or LED that is the light source of the excitation light generally has a point light source type propagation shape. Then, if both side surfaces (both lens surfaces) of the phosphor lens are flat (flat plate type), the optical path length of the straight component passing through the center of the optical axis is the shortest, and the outer periphery that is incident and propagates obliquely in the lens The optical path length of the light component increases and becomes longer (optical path length dispersion). Therefore, in the present invention, when the thickness of the phosphor lens is made to have a thickness gradient in the radial direction so that the center of the optical axis is thicker and thinner toward the outer peripheral side so as to cancel out this optical path length dispersion, the color tone of the emitted light The in-plane distribution is preferably minimized.

  That is, when the point light source is arranged on the optical axis on one lens surface side of the phosphor lens as the thickness distribution of the phosphor lens, and excitation light is incident on the one lens surface from the point light source, the lens It is preferable to have a thickness distribution so that the optical path lengths of the excitation light passing through the inside are all equal. Alternatively, when one lens surface is a flat surface and the other lens surface is a convex lens surface, the other lens surface is arranged with a point light source on the optical axis on the one lens surface side. When the excitation light is incident on the one lens surface, it is preferable to have such a surface shape that the optical path lengths of the excitation light transmitted through the lens are all equal. Thereby, for example, uniform white light is obtained as the emitted light.

  The thickness distribution in the lens radial direction of the phosphor lens changes depending on the numerical aperture (NA) of the light component emitted from the light source (blue LD or LED) used, the distance from the phosphor lens, etc. When designing a light-emitting device (white LED module), it can be calculated by taking these into account. In general, an aspherical lens shape having a certain curvature is often used.

  Up to this point, the case where the phosphor lens of the present invention is made of transparent ceramics having a uniform composition in the lens has been described. In the phosphor lens of the present invention, the diameter of the lens centering on the optical axis of the phosphor lens is described. You may make it have the density | concentration gradient of Ce in the said complex oxide in a direction. In this case, in addition to having a convex shape as described above, a convex type, a convex lens type, a Fresnel lens type, an aspherical lens are used in accordance with the concentration gradient in the lens radial direction of the Ce concentration of the composite oxide to be contained. White light can be made uniform as various types of lens shapes such as a mold. One lens surface may be a flat surface, and the other lens surface may be a convex lens surface, a Fresnel lens surface, a concave lens surface, or an aspheric lens surface. In this case, the concentration gradient range of Ce is close to the lower limit so that, for example, the lower concentration component does not fall below the lower limit 0.0001 of w so as to be the composition range represented by the above formula (1). It is preferable that the component on the higher concentration side is designed closer to the upper limit as long as the upper limit of 0.005 is not exceeded. By doing so, even if concentration gradient relaxation due to thermal diffusion in the sintering process occurs, it does not deviate from the range of the above formula (1), which is preferable.

  There are various methods for providing a Ce concentration gradient in the lens radial direction. As the simplest method, a sintered body of a transparent ceramic having a low Ce concentration is formed in advance, and a transparent ceramic phosphor material film having a high Ce concentration is applied to the surface by spin coating or spraying. There is a method in which Ce is thermally diffused from the surface to the inside by sintering. Although this method is simple, it can diffuse only a film with a uniform thickness formed on the lens surface, so that it can only have a concentration distribution corresponding to the thickness distribution in the depth direction of the lens, and it is still completely free optical design Cannot be guaranteed.

  As another method, if a core / clad type double molding method is adopted in the molding process, the Ce concentration gradient is changed to a positive gradient in which the concentration increases from the center of the lens toward the outer periphery, and a negative gradient in which the concentration decreases. Can also be freely given.

  A core / clad type double molding method comprising a core rod part and a clad outer cylinder part having different Ce concentrations can be performed by the following procedure. That is, first, a core rod portion designed using a certain Ce concentration (using a powder raw material to which Ce has been added at a certain concentration) is molded by a single-screw press molding machine. Subsequently, the obtained green body is loaded at the approximate center of a single-axis press molding machine having a diameter slightly larger than the diameter of the first single-axis press molding machine. At this time, a guide jig or the like can be used to set the substantially center. Then, a concentric (doughnut-shaped) space is created on the outer periphery of the green body, and this donut-shaped space (the space for forming the cladding layer) is filled with powder for the cladding outer cylinder part with a different Ce concentration from the core rod part. To do. In this state, a core-clad type double-molded green body can be produced by re-molding the core rod part together with this one-size large uniaxial press molding machine. After that, it is possible to apply a concentration gradient in the radial direction by thermally diffusing Ce, particularly in the sintering process, by turning to a ceramic manufacturing process after degreasing as usual.

  At this time, the Ce concentration gradient, for example, the Ce concentration in the raw material powders of the above two compositions is such that the lower concentration component falls below the lower limit 0.0001 of w so that the composition range is represented by the above formula (1). It is preferable to design closer to the lower limit in a range that does not exceed the upper limit in a range in which the component on the higher concentration side does not exceed the upper limit of 0.005 of w. By doing so, even if concentration gradient relaxation due to thermal diffusion in the sintering process occurs, it does not deviate from the range of the above formula (1), which is preferable.

  Specifically, the lens shape of the phosphor lens is designed so as to increase the light extraction efficiency, that is, when the lens is thick at the center of the optical axis of the lens, such as a convex type or a convex lens type, or as a Fresnel lens type. When there is no change in the thickness in the radial direction as much as possible, each is designed, and then blue light that excites the phosphor material (transparent ceramic) constituting the phosphor lens is incident from the bottom center or top center of the concentric circle From these results, the optical path length of the linear component of the incident light at the center of the optical axis and various angular components traveling with a divergence angle in the lens outer peripheral direction are calculated. As a result, the optical path length of the linear component is calculated. In the case where the Ce concentration becomes shorter, the Ce concentration becomes deeper as it goes in the outer peripheral direction as the lens radial direction. May be so Usumaru as proceeds in the outer peripheral direction as the radial direction.

  When this method is used, for example, both a pattern in which the Ce concentration in the core rod portion is high and the Ce concentration in the cladding portion is low and a pattern in which the Ce concentration in the core rod portion is low and the Ce concentration in the cladding portion is high are produced. Therefore, it is preferable to thermally diffuse these by sintering, whereby a phosphor lens in which a Ce concentration gradient can be freely given to a plus gradient or a minus gradient with respect to the lens radial direction can be manufactured.

  In this way, by using a functional transparent ceramic having a Ce concentration gradient in the composite oxide, the optical path length of the excitation light incident component described above is made equal to improve the in-plane uniformity of the color tone of the emitted light. In addition, it is possible to provide a lens function for adjusting the emission angle of the mixed white light component emitted from the phosphor lens. That is, from the refractive index of the phosphor lens and the propagation angle of each light component in the plane propagating inside the lens, the emission angles of all the emitted light components are reduced toward the lens optical axis center according to Snell's law, or vice versa. In addition, an optical design as a lens that diverges from the center of the lens optical axis toward the outer peripheral direction can be realized.

  As described above, the phosphor lens of the present invention is not only a transparent phosphor, but can also have a color tone adjustment function and an optical design function by further providing a lens shape. . In addition, the external light extraction efficiency can be improved by making the surface (outgoing surface) from which light is further emitted as a rough surface having fine irregularities or a pyramid texture as required.

  Such a roughening method is not particularly limited, but a conventionally known blasting or etching process may be used, and as a recent technique, texture indenting by nanoimprinting is also possible, which is advantageous in terms of cost. Therefore, this method can also be suitably used.

  From here on, the phosphor lens of the present invention can be provided with a lens shape function as described above, although it is also related to the overall design including the heat radiation design when incorporated as a white light emitting device (for example, a white LED module). . Therefore, for example, if you want to make the heat sink contact the side (lens surface) or bottom of the phosphor lens, fit part or all of the side of the phosphor lens to the heat sink according to the shape of the contact surface of the heat sink. It can also be processed. If the heat sink contact surface is flat, the portion where the phosphor lens is fitted can be a flat surface, and if it is curved, the portion where the phosphor lens is fitted corresponds to the curved surface. It can also be fitted.

  As a method for producing the transparent ceramic constituting the phosphor lens of the present invention, there are a single crystal production method such as a floating zone method and a micro pull-down method, and a ceramic production method, and any production method may be used. However, in general, the single crystal manufacturing method has a certain degree of restriction in the design of the concentration ratio of the solid solution, and the ceramic manufacturing method is more preferable in the present invention.

  Hereinafter, the ceramic production method will be described in more detail as an example of the production method of the phosphor lens of the present invention, but the single crystal production method that follows the technical idea of the present invention is not excluded.

《Ceramics manufacturing method》
[material]
The raw material used in the present invention is selected from the group consisting of cerium (Ce), lutetium (Lu), yttrium (Y), lanthanum (La), scandium (Sc), and gallium (Ga) as the main starting material. At least one element selected from the group consisting of aluminum (Al), and optionally a rare earth element Q (Q is gadolinium (Gd), terbium (Tb), praseodymium (Pr)) A metal powder of each constituent element consisting of (elements), an aqueous solution of nitric acid, sulfuric acid, uric acid or the like, or a complex oxide powder of the above elements can be suitably used. In particular, each oxide powder of each element is preferable because it is stable and safe and easy to handle. The purity of these raw materials is preferably 99.9% by mass or more.

  Furthermore, as a starting material of the subcomponent, metal powder of at least one subcomponent constituent element selected from the group consisting of silicon (Si), zirconium (Zr), titanium (Ti), hafnium (Hf), or nitric acid, An aqueous solution of sulfuric acid, uric acid or the like, an alkoxide of the above element, or an oxide powder of the above element can be suitably used. In particular, each oxide powder of each element is preferable because it is stable and safe and easy to handle. The purity of these raw materials is preferably 99.9% by mass or more.

  Moreover, it does not specifically limit about the powder shape of the said raw material, For example, square, spherical, and plate-shaped powder can be utilized suitably. Moreover, it can use suitably even if it is the powder which carried out secondary aggregation, and it can use suitably also if it is the granular powder granulated by granulation processes, such as a spray-dry process. Furthermore, the preparation process of these raw material powders is not particularly limited. A raw material powder produced by a coprecipitation method, a pulverization method, a spray pyrolysis method, a sol-gel method, an alkoxide hydrolysis method, or any other synthesis method can be suitably used. Further, the obtained raw material powder may be appropriately treated by a wet ball mill, a bead mill, a jet mill, a dry jet mill, a hammer mill or the like.

  For example, when preparing a phosphor lens having a uniform composition, a predetermined amount of the starting material of the main component is weighed so as to be a molar ratio of the composite oxide of the formula (1), and further from the blending amount of the starting material. Weigh out a predetermined amount of the starting materials of the above-mentioned subcomponents with respect to the mass converted to the composite oxide so as to have a predetermined blending amount, mix and fire, and then use the composite oxide of the desired configuration as the main component It is good to obtain a baking raw material. That is, it consists of yttrium oxide powder or lutetium oxide powder, lanthanum oxide powder, cerium oxide powder, scandium oxide powder, aluminum oxide powder, gallium oxide powder, and gadolinium, terbium, praseodymium added as necessary. It is preferable that at least one rare earth oxide powder selected from the group and a secondary component starting material are mixed and then fired in a crucible to produce a fired raw material. Thereafter, the fired raw material is pulverized to obtain a raw material powder.

  When producing a phosphor lens by a core-clad type double molding method comprising a core rod part and a clad outer cylinder part with different Ce concentrations, the amount of Ce compounded and the molar ratio of all components are designed in advance. Two kinds of starting materials adjusted so as to become the salted ume are weighed and mixed, and thereafter, firing and pulverization are performed in the same manner as described above to prepare two materials, a core rod material and a clad material.

  The baking temperature at this time is 1000-1400 degreeC, Preferably it is 1200 degreeC or more.

  Various organic additives may be added to the composite oxide raw material powder used in the present invention for the purpose of improving the quality stability and the yield in the production process. In the present invention, these are not particularly limited. That is, various dispersants, binders, lubricants, plasticizers, and the like can be suitably used.

[Manufacturing process]
In the present invention, the above raw material powder is pressed into a predetermined shape, degreased, and then sintered to produce a sintered body with a relative density of at least 95% or more. It is preferable to perform a hot isostatic pressing (HIP (Hot Isostatic Pressing)) process after that.

(Molding)
In the production method of the present invention, a normal press molding process can be suitably used. That is, it is possible to suitably use a very general pressing process in which a raw material powder is filled in a mold and pressed from a certain direction. In order to produce a double-molded green body comprising a core rod part and a clad outer cylinder part, two or more press moldings having different inner diameters (in the case of a cylindrical shape) or different inner sides (in the case of a polygonal shape) It is preferable to prepare a jig. Moreover, it is preferable to prepare a preliminary jig for arranging the core rod green body in a slightly larger press molding jig as a molding guide for arranging the core rod part at the approximate center of the cladding layer. Further, a CIP (Cold Isostatic Pressing) process in which the container is hermetically stored in a deformable waterproof container and pressurized with hydrostatic pressure can be used. The applied pressure may be appropriately adjusted while confirming the relative density of the obtained molded body, and is not particularly limited. For example, if the pressure is controlled within a pressure range of about 300 MPa or less that can be handled by a commercially available CIP device, the manufacturing cost can be suppressed. It's okay. Alternatively, not only a molding process but also a hot press process, a discharge plasma sintering process, a microwave heating process, and the like that can be performed all at once at the time of molding can be suitably used.

  In addition, when it is not necessary to produce a double-molded green body composed of a core rod part and a clad outer cylinder part, it is possible to produce a molded body by a cast molding method instead of a press molding method. Molding methods such as pressure casting molding, centrifugal casting molding, and extrusion molding can also be employed by optimizing the combination of the shape and size of the oxide powder as a starting material and various organic additives.

(Degreasing)
In the production method of the present invention, a normal degreasing step can be suitably used. That is, it is possible to go through a temperature rising degreasing process by a heating furnace. Also, the type of atmospheric gas at this time is not particularly limited, and air, oxygen, hydrogen, inert gas, and the like can be suitably used. Note that in the case of adding an easily oxidizable element such as terbium, it is preferable to select an atmosphere with a reduced oxygen partial pressure because variations in valence fluctuations can be reduced. The degreasing temperature is not particularly limited, but when a raw material mixed with an organic additive is used, it is preferable to raise the temperature to a temperature at which the organic component can be decomposed and eliminated.

(Sintering)
In the production method of the present invention, a general sintering process can be suitably used. That is, a heating and sintering process such as a resistance heating method or an induction heating method can be suitably used. The atmosphere at this time is not particularly limited, but an inert gas, oxygen, hydrogen, vacuum, or the like can be suitably used.

  The sintering temperature in the sintering step of the present invention is appropriately adjusted depending on the starting material selected. In general, using a selected starting material, a temperature on the low temperature side of about several tens of degrees Celsius to 200 to 400 degrees Celsius is suitably selected from the melting point of various composite oxide sintered bodies to be produced. In addition, when attempting to produce a garnet-type composite oxide sintered body in which a temperature zone in which a phase change to a phase other than a cubic crystal is present in the vicinity of the selected temperature, conditions under which the temperature zone is strictly excluded and If controlled and sintered, the mixture of phases other than cubic crystals can be suppressed, and birefringence scattering can be reduced.

  The sintering holding time in the sintering process of the present invention is appropriately adjusted depending on the starting material selected. In general, a few hours is often sufficient. However, holding for several tens of hours can be suitably employed to improve the diffusion uniformity of cerium. Further, the relative density of the composite oxide sintered body after the sintering process must be densified to 95% or more at least.

(Hot isostatic pressing (HIP))
In the production method of the present invention, after the sintering step, an additional step of performing a hot isostatic pressing (HIP) treatment can be provided.

Incidentally, the pressurized gas medium type in this case, argon, an inert gas such as nitrogen or Ar-O ₂ can be used suitably. The pressure applied by the pressurized gas medium is preferably 50 to 300 MPa, and more preferably 100 to 300 MPa. If the pressure is less than 50 MPa, the transparency improvement effect may not be obtained. If the pressure exceeds 300 MPa, further improvement in transparency cannot be obtained even if the pressure is increased, and the load on the device may be excessive and may damage the device. . The applied pressure is preferably 196 MPa or less, which can be processed with a commercially available HIP device, for convenience and convenience.

  Further, the treatment temperature (predetermined holding temperature) at that time may be appropriately set depending on the type of material and / or the sintering state, and is set, for example, in the range of 1000 to 2000 ° C., preferably 1200 to 1800 ° C. At this time, as in the case of the sintering step, it is essential that the temperature be below the melting point and / or the phase transition point of the composite oxide constituting the sintered body. The composite oxide sintered body exceeds the melting point or exceeds the phase transition point, making it difficult to perform an appropriate HIP treatment. Moreover, if the heat treatment temperature is less than 1000 ° C., the effect of improving the transparency of the sintered body cannot be obtained. In addition, although there is no restriction | limiting in particular about the holding time of heat processing temperature, It is good to adjust suitably, checking the characteristic of the complex oxide which comprises a sintered compact.

  In addition, although the heater material, heat insulating material, and processing container which perform HIP processing are not particularly limited, graphite, molybdenum (Mo), platinum (Pt), or tungsten (W) can be suitably used.

(Annealing)
In the production method of the present invention, oxygen deficiency occurs in the obtained transparent oxide ceramics sintered body after the HIP treatment, and a light gray appearance is exhibited, or conversely, an easily oxidizable constituent element In some cases, coloration occurs due to absorption of charge transfer. In these cases, it is preferable to perform annealing at a temperature equal to or lower than the HIP processing temperature (for example, 900 to 1500 ° C.).

It is preferable to appropriately adjust the atmosphere gas and the pressure of the annealing treatment depending on the composition to be obtained. Vacuum, Ar, H ₂ , N ₂ , O ₂ , and the pressurized environment thereof can be suitably selected.

(processing)
In the manufacturing method of the present invention, the transparent oxide ceramics sintered body obtained by the above series of steps is appropriately processed into a desired thickness and size so that it can be used for lighting components, lighting units, and lighting modules that are expected to be used. Can be incorporated.

  At this time, in accordance with the emission wavelength of the light source (LD or LED) having a peak wavelength within the range of 410 to 480 nm, as well as the emission intensity, the thickness adjustment is performed so that the chromaticity of the emitted light falls within a desired white range, It is preferable to adjust the concentration of Ce to be added. It is also preferable to process into a convex shape or a convex lens shape with a thickness gradient so that the optical path lengths of the light rays incident and propagated within the surface of the transparent oxide ceramic sintered body are substantially equal. Furthermore, it is also preferable to process the surface shape with a lens function for the purpose of condensing the white light beam emitted from the transparent oxide ceramic sintered body or conversely scattering it at a wide angle. Of course, a texture having an antireflection function for preventing reflection on the inner side of the lens may be applied to the surface from which light is emitted.

[Light emitting device]
The light-emitting device of the present invention includes the above-described phosphor lens of the present invention and a light source that makes excitation light incident on one lens surface of the phosphor lens. At this time, it is preferable to use the blue light of the LD or LED as the excitation light because white light is obtained as the outgoing light.

  Hereinafter, the present invention will be described more specifically with reference to examples and comparative examples, but the present invention is not limited to the following examples.

[Example 1]
A system having a uniform Ce concentration will be taken up as a sintered body of transparent ceramics constituting a phosphor lens.
Lutetium oxide powder, lanthanum oxide, gadolinium oxide powder, yttrium oxide powder, cerium oxide powder, scandium oxide powder manufactured by Shin-Etsu Chemical Co., Ltd., and aluminum oxide powder manufactured by Nippon Light Metal Co., Ltd., manufactured by Yamanaka Futec Co., Ltd. Gallium oxide powder and tetraethyl orthosilicate (TEOS) manufactured by Yamanaka Hutech Co., Ltd. were obtained. All the purity was 99.9 mass% or more.
Using the above raw materials, raw materials were prepared at a mixing ratio of final compositions shown in Table 1. Note that the amount of SiO ₂ added (in parentheses after “SiO ₂ ”) is obtained by calculating the equivalent amount of the SiO ₂ component produced in the process of adding TEOS to the starting material and firing it. It is calculated | required as a ratio with respect to the mass converted into composite oxide from the compounding quantity of the other starting material of said.

  Subsequently, the raw material was dispersed and mixed in ethanol using an alumina ball mill. The processing time was 20 hours. Thereafter, the slurry was dried, and each raw material powder obtained was fired at 1000 to 1400 ° C. After that, dispersion and mixing were performed again in ethanol using an alumina ball mill. The processing time was 20 hours. Each of the obtained slurries was finished into a granular raw material having an average particle diameter of 20 μm by spray drying.

  A part of each raw material powder obtained here was put in an alumina crucible and fired in a high temperature muffle furnace at 1500 ° C. for a holding time of 3 hours to obtain a fired raw material. The obtained fired raw material was subjected to diffraction pattern analysis using a powder X-ray diffractometer manufactured by Panalical. As a result, cubic crystals considered to be the crystal phase of the garnet-type oxide were confirmed from these firing raw materials.

  The granular raw material prepared earlier is filled into a mold with a diameter of 8 mm, temporarily formed into a cylindrical shape with a thickness of 15 mm by a uniaxial press molding machine, and then subjected to a hydrostatic pressure press treatment at a pressure of 198 MPa. A molded body was obtained. The obtained molded body was degreased in a muffle furnace at 500 to 1000 ° C. for 2 hours. Subsequently, the dried molded body was charged into a resistance heating type atmospheric furnace and treated at 1500 to 1670 ° C. for 1 to 20 hours in an oxygen atmosphere to obtain a sintered body. At this time, the sintering temperature was adjusted so that the sintered relative density of the sample was 95%.

  The obtained sintered body was charged into a carbon heater HIP furnace and subjected to HIP treatment in Ar at 200 MPa, 1500-1700 ° C. for 2 hours. As a result, a cylindrical rod-shaped transparent ceramic sintered body having an outer diameter of about 5 mm and a thickness of about 12 mm was obtained.

  The front and back surfaces of a part of the obtained sintered body were ground and polished to prepare a mirror-finished phosphor rod having a length of 10 mm. The total light transmittance at a wavelength of 600 nm was measured for this mirror-finished phosphor rod using a spectrophotometer (V-670) manufactured by JASCO Corporation in the following manner.

(Measurement method of total light transmittance)
The total light transmittance is a method of integrating and evaluating all the light rays that have passed through the sample, including the forward scattering component, and specifically, evaluating by condensing the light with an integrating sphere. As a procedure, first, a blank light transmittance in the vicinity of a wavelength of 600 nm is collected by an integrating sphere, and a base light amount; I ₀ is set. Subsequently, a sample is placed in the optical path, and all the light rays that have passed through the sample are collected by an integrating sphere to evaluate the amount of light; I. Then, the total light transmittance is calculated by the following formula.
Total light transmittance = I / I ₀ × 100

  As a result, the total light transmittance of the sample of this example at a total length of 10 mm at a wavelength of 600 nm is as shown in Table 2.

  Subsequently, the obtained sintered body was cut out into a circular plate shape having a thickness of 0.8 mm (this is called a transparent ceramic phosphor). Furthermore, a commercially available LD chip (wavelength 460 mm, laser emission angle 10 degrees) was prepared, and a 0.8 mm thick transparent ceramic phosphor plate with a thickness of 0.8 mm was lasered at the center of the optical axis (circular center) when the beam was separated 10 mm. The sintered body was optically designed to receive the beam.

  At this time, since the refractive index in the visible light region is approximately 1.8 in any of the transparent ceramic phosphors having the above compositions, n1.8 was used in the optical design. Of the beam having an emission angle of 10 degrees (an angle inclined by 10 degrees with respect to the optical axis), it is a component having an angle of 10 degrees that propagates through the transparent ceramic phosphor at the widest angle (so that the optical path length becomes the longest). This is 5.54 degrees propagation in the transparent ceramic phosphor due to Snell's law. When the incident surface side is a flat surface and the output side surface is designed to be convex so as to be equal to the optical path length, the cross-sectional shape shown in FIG. 1 is obtained. That is, a slight aspherical convex shape in which the central portion of the optical axis is convex 1.005 times as compared with the outermost peripheral portion (outer peripheral portion). In FIG. 1, the convex state is exaggerated. Based on this result, the transparent ceramic phosphor in a circular plate shape with a thickness of 0.8 mm is polished into an aspheric lens shape in which one side is slightly convex as shown in FIG. A sample of phosphor lens 1 was obtained. Since the aspherical convex shape in this case can be said to be almost flat, even in the state of the circular plate, the mixed color tone unevenness of the emitted light is negligible.

  When the excitation light is applied to the substantially central portion (optical axis center) of the fluorescent lens 1 from the LD chip from a position 10 mm away from the flat surface (incident surface) of the obtained fluorescent lens 1 on its optical axis, The light emitted from the convex lens (outgoing surface) side of the phosphor lens 1 was white light with no color tone irregularity in any composition.

  Next, after a beam having an exit angle of 10 degrees is incident on the transparent ceramic phosphor and propagates, all light components are emitted from the exit surface of the transparent ceramic phosphor in a substantially parallel manner (that is, as parallel light). We designed a convex shape with the collimating lens function.

  Again, it is the component with the angle of 10 degrees that propagates through the transparent ceramic phosphor at the widest angle among the beams with the emission angle of 10 degrees. This propagates at 5.54 degrees in the transparent ceramic phosphor. Thereafter, in order for the angle emitted into the atmosphere to be 0 degrees, the emission surface needs to be inclined by 12.4 degrees with respect to the flat surface. Similarly, when a convex surface in which all other propagation components are emitted substantially in parallel is designed, the cross-sectional shape shown in FIG. 2 is obtained. According to this design, a circular plate-shaped transparent ceramic phosphor having a thickness of 0.8 mm was polished, and both surfaces were mirror-finished to obtain a phosphor lens 2 sample.

  When the excitation light is irradiated from the LD chip to the substantially central portion (optical axis center) of the phosphor lens 2 from a position 10 mm away from the flat surface (incident surface) of the obtained phosphor lens 2 on the optical axis. The light emitted from the convex lens (outgoing surface) side of the phosphor lens 2 was white in any composition and was collimated light such as a laser pointer.

  As described above, a phosphor lens made of a sintered body of transparent ceramics that emits fluorescence when excited by a commercially available LD chip, and a lens that eliminates optical path aberrations or adjusts the beam profile of the emitted light to collimated light A phosphor lens with a function could be produced.

[Example 2]
A system in which the Ce concentration is graded in the lens radial direction as a sintered body of transparent ceramics constituting the phosphor lens will be described.
Gadolinium oxide powder, yttrium oxide powder, cerium oxide powder, scandium oxide powder manufactured by Shin-Etsu Chemical Co., Ltd., and aluminum oxide powder manufactured by Nippon Light Metal Co., Ltd., gallium oxide powder manufactured by Yamanaka Futech Co., Ltd., and Yamanaka Futech Tetraethyl orthosilicate (TEOS) manufactured by Co., Ltd. was obtained. All the purity was 99.9 mass% or more.
Using the above raw materials, composition 1: (Gd _0.55 Y _0.4295 Ce _0.0005 Sc _0.02 ) ₃ (Al _0.6 Ga _0.3 Sc _0.1 ) ₅ O ₁₂ + SiO ₂ (90 ppm) and composition 2: (Gd _0.55 Y _0.425 Ce _0.005 Sc _0.02 ) Two kinds of raw materials were prepared at a mixing ratio of ₃ (Al _0.6 Ga _0.3 Sc _0.1 ) ₅ O ₁₂ + SiO ₂ (90 ppm). Note that the amount of SiO ₂ added (in parentheses after “SiO ₂ ”) is obtained by calculating the equivalent amount of the SiO ₂ component produced in the process of adding TEOS to the starting material and firing it. It is calculated | required as a ratio with respect to the mass converted into composite oxide from the compounding quantity of the other starting material of said.

  Subsequently, the above two raw materials were dispersed and mixed in ethanol using an alumina ball mill. The processing time was 20 hours. Thereafter, the slurry was dried, and each raw material powder obtained was fired at 1000 to 1400 ° C. After that, dispersion and mixing were performed again in ethanol using an alumina ball mill. The processing time was 20 hours. Each of the obtained slurries was finished into a granular raw material having an average particle diameter of 20 μm by spray drying.

  Part of the raw material powders of compositions 1 and 2 obtained here were separately put in an alumina crucible and fired in a high-temperature muffle furnace at 1500 ° C. for a holding time of 3 hours to obtain a fired raw material. The obtained fired raw material was subjected to diffraction pattern analysis with a powdered X-ray diffractometer manufactured by Panalical. As a result, cubic crystals considered to be a crystalline phase of the garnet-type oxide were confirmed from this firing raw material.

  Of the granular raw materials prepared earlier, the raw material of composition 1 (the raw material having the above composition and the Ce ratio at the A site position of 0.0005) is first filled into a 5 mm diameter mold, and uniaxial press After temporarily forming into a 15 mm-thick columnar shape with a molding machine, the obtained temporary molded body was set using a special jig in the approximate center of a 10 mm diameter mold. After that, the jig was removed, and this time, the raw material of composition 2 (the raw material which was not initially raw material with a diameter of 5 mm, the raw material having the above composition and the Ce ratio of 0.005 at the A site position) Additional filling). Moreover, what reverse the combination of the composition of a core part and an outer peripheral part was also prepared. That is, first, using a raw material of composition 2 (a raw material having a Ce ratio of 0.005 at the A site position in the above composition), a metal mold having a diameter of 5 mm is filled and temporarily formed into a cylinder having a thickness of 15 mm by a uniaxial press molding machine. After molding, the obtained temporary molded body was then set in the approximate center of a 10 mm diameter mold using a dedicated jig. After that, the jig was removed, and this time, the raw material of composition 1 (the raw material which was not initially raw material with a diameter of 5 mm, the raw material having the above composition and the Ce ratio of 0.0005 at the A site position) Additional filling). In this state, each was molded again with a uniaxial press molding machine to produce a core / clad mold. No cracks or the like occurred in the obtained molded body.

  Two types of the obtained core / clad molds were subjected to an isostatic pressing at a pressure of 198 MPa to obtain a CIP compact. The obtained molded body was degreased in a muffle furnace at 500 to 1000 ° C. for 2 hours. Subsequently, the dried molded body was charged into a resistance heating type atmospheric furnace and treated at 1500 to 1650 ° C. for 10 to 20 hours in an oxygen atmosphere to obtain a sintered body. At this time, the sintering temperature was appropriately adjusted so that the sintered relative density of each sample was 95%. Further, Ce was treated for at least 10 hours or more so that a gentle concentration gradient with respect to the radial direction in the sintered body was formed by thermal diffusion. Since the concentration of Ce originally added is thin, there is no method for quantitatively evaluating the concentration gradient of Ce in the radial direction after sintering, and the concentration gradient is given by adjusting the sintering time based on experience. did.

  Each obtained sintered body was charged into a HIP furnace made of carbon heater and subjected to HIP treatment in Ar at 200 MPa, 1500 to 1650 ° C. for 2 hours. As a result, a cylindrical core / clad type transparent ceramic sintered body having an outer diameter of about 7 mm and a thickness of about 12 mm was obtained.

  With respect to a part of the obtained sintered body, the total light transmittance at a wavelength of 600 nm was measured in the same manner as in Example 1. As a result, the total light transmittance at a wavelength of 600 nm and a total length of 10 mm was 67%.

  Subsequently, the obtained sintered body was cut out into a circular plate shape having a thickness of 1.0 mm to obtain a transparent ceramic phosphor. Furthermore, a commercially available LD chip (wavelength 460 mm, laser emission angle 10 degrees) was prepared, and a 1.0 mm thick circular plate-shaped transparent ceramic phosphor was lasered at the center of the optical axis (circular center) when the beam was separated 10 mm. The sintered body was optically designed to receive the beam. For the transparent ceramic phosphor having the above composition, n1.8 was used in the optical design.

First, the core composition is composition 1: (Gd _0.55 Y _0.4295 Ce _0.0005 Sc _0.02 ) ₃ (Al _0.6 Ga _0.3 Sc _0.1 ) ₅ O ₁₂ + SiO ₂ (90 ppm), and the cladding composition is composition 2: (Gd _0.55 Y _0.425 Ce _0.005 Sc _0.02 ) ₃ (Al _0.6 Ga _0.3 Sc _0.1 ) ₅ O ₁₂ + SiO ₂ (90 ppm) Starting from a core-clad type transparent ceramic sintered body with a concentration gradient in which the Ce concentration decreases toward the center A lens shape similar to 1 was finished. That is, polishing was performed to form an aspheric lens having a slightly convex center on one side. Note that this structure is a comparative example for confirming the state of occurrence of uneven color tone as a configuration in which the influence of the Ce concentration gradient appears almost as it is.

  When the excitation light is applied to the substantially central portion (optical axis center) of the fluorescent lens 1 from the LD chip from a position 10 mm away from the flat surface (incident surface) of the obtained fluorescent lens 1 on its optical axis, The light emitted from the convex lens (outgoing surface) side of the phosphor lens 1 was bluish at the center, and turned to white as it moved to the outer peripheral portion, and became mixed color light with uneven color tone in the radial direction.

  The phosphor lens 1 of FIG. 1 is practically nearly flat with the optical axis center slightly thicker (1.005 times thicker). In this state, the Ce concentration is adjusted so as to decrease toward the center of the optical axis with respect to the radial direction and to increase toward the outer peripheral portion, so that the fluorescence conversion efficiency at the center of the optical axis becomes insufficient. It is presumed that the blue color of the LD chip was emitted strongly. On the other hand, it is presumed that the outer peripheral portion was able to exhibit a white color tone because the Ce concentration was sufficient.

  Although the color rendering properties of this structure seem to have decreased at first glance, an optical design with an in-plane gradient of Ce concentration was made, so that a deliberately strong blue-colored white phosphor with a central bluish color was produced. It can also be said that it has become possible.

Next, the core composition is composition 2: (Gd _0.55 Y _0.425 Ce _0.005 Sc _0.02 ) ₃ (Al _0.6 Ga _0.3 Sc _0.1 ) ₅ O ₁₂ + SiO ₂ (90 ppm), and the cladding composition is composition 1: (Gd _0.55 Y _0.4295 Ce _0.0005 Sc _0.02 ) ₃ (Al _0.6 Ga _0.3 Sc _0.1 ) ₅ O ₁₂ + SiO ₂ (90 ppm) Starting from a core-clad type transparent ceramic sintered body having a concentration gradient in which the Ce concentration increases toward the center Processed into a concave lens.

  As in Example 1, it is the component with the angle of 10 degrees that propagates through the transparent ceramic phosphor at the widest angle among the beams with the exit angle of 10 degrees, and this is 5.54 due to Snell's law in the transparent ceramic phosphor. Propagation. The angle formed by the surface that is emitted from the opposite side without total reflection (not reaching the critical angle) and the propagation direction is about 33 degrees. In other words, the relative angle to the incident surface is about 27.4 degrees. Therefore, for safety reasons, the component that propagates through the transparent ceramic phosphor at the widest angle among the beams with an emission angle of 10 degrees is inclined by 25 degrees at the position where the component is emitted from the transparent ceramic phosphor, and the inner component is When the lens shape was designed such that the inclination was more gradual (flat), the concave cross section shown in FIG. 3 was obtained. The transparent ceramic phosphor having a thickness of 1.7 mm was polished according to this design, and both surfaces were mirror-finished to obtain a sample of the phosphor lens 3.

  When the excitation light is irradiated from the LD chip to the substantially central portion (optical axis center) of the phosphor lens 3 from a position 10 mm away on the optical axis from the flat surface (incident surface) of the obtained phosphor lens 3, The light emitted from the concave lens (outgoing surface) side of the phosphor lens 3 is white with no color unevenness, and is a wide-angle scattered light whose emission angle is twice or more wider than the emission angle from the LD. It was.

  If the exit surface has a concave lens shape, the relative optical path length of the light component propagating on the outer periphery of the phosphor lens will be extended, but the concentration of Ce will be increased so that the Ce concentration is higher at the center of the optical axis and lower toward the lens outer periphery. For this reason, it is considered that the color tone was successfully corrected despite the increase in the optical path length.

  As described above, it is a phosphor lens made of a sintered body of transparent ceramics that emits fluorescence when excited by a commercially available LD chip, and can have a Ce concentration gradient inside the phosphor lens while being transparent, As a result, a phosphor lens with a lens shape function that enables more free lens design could be manufactured.

[Example 3]
An example in which the surface shape of the sintered body obtained in Example 1 and having a mirror-finished length of 10 mm on the front and back surfaces is further given will be described. Table 2 shows the total light transmittance at a wavelength of 600 nm with an optical path length of 10 mm of the sintered body (before giving a pyramidal texture surface shape).
Here, a microstructure transfer jig having a pyramid texture structure coated with DLC (diamond-like carbon) was prepared in-house. The pyramid texture was designed with a pitch and depth of about 1 μm. A pyramidal texture was transferred to both ends of the mirror-finished rod using the jig by imprinting.
The total light transmittance at a wavelength of 600 nm at an optical path length of 10 mm of the obtained transparent ceramic rod body with a texture structure was measured again. As a result, the transmittance was improved to the values shown in Table 3.

  As described above, a transparent ceramic phosphor that is excited by an LD chip and emits fluorescence and has a surface shape design for improving the transmittance could be produced. When applied to a phosphor lens, the lens is more excellent in transparency.

  Although the present invention has been described with the embodiment, the present invention is not limited to the embodiment, and other embodiments, additions, changes, deletions, and the like can be conceived by those skilled in the art. As long as the effects of the present invention are exhibited in any aspect, they are included in the scope of the present invention.

1, 2, 3 Phosphor lens

Claims (9)

A composite having an A ₃ B ₅ O ₁₂ type garnet structure in which at least one element selected from the group consisting of Y, Lu, Sc, and La and Ce enter at the A site position and at least Al at the B site position An oxide as a main component and at least one oxide selected from the group consisting of silicon oxide, zirconium oxide, titanium oxide and hafnium oxide as a subcomponent is larger than 0 as a mass ratio with respect to the composite oxide. A phosphor lens made of a transparent ceramic sintered body having a total light transmittance of 50% or more at a wavelength of 600 nm with an optical path length of 10 mm, contained in a range of less than 100 ppm.   The phosphor lens according to claim 1, wherein blue excitation light is incident and emits white light. The composite oxide has the following formula (1):
_{(La x Lu y Y z Ce} w Sc v Q 1-xyzwv) 3 (Al p Ga q Sc r) 5 O 12 (1)
(Wherein x is from 0 to 0.1, y is from 0 to 1, z is from 0 to 1, w is from 0.0001 to 0.005, v is from 0 to 0.04, x + y + z + w + v ≦ 1 And at least one of y and z is greater than 0. p is 0.4 or more and 1 or less, q is 0 or more and 0.55 or less, r is 0 or more and 0.2 or less, and p + q + r = 1. Q is at least one rare earth element selected from the group consisting of Gd, Tb and Pr.)
The fluorescent substance lens of Claim 1 or 2 represented by these.   As a thickness distribution in the radial direction of the lens, when a point light source is placed on the optical axis on one lens surface side and excitation light is incident on the one lens surface from the point light source, excitation is transmitted through the lens. 4. The phosphor lens according to claim 3, which is a convex lens having a thickness distribution in which all optical path lengths of light are equal.   3. The phosphor lens according to claim 1, wherein the phosphor lens has a concentration gradient of Ce in the complex oxide in a lens radial direction around the optical axis of the phosphor lens.   The phosphor lens according to claim 5, wherein the color tone of the emitted light is uniform in the emission surface by a combination of the Ce concentration gradient in the lens radial direction and the thickness distribution in the radial direction of the lens.   7. The phosphor lens according to claim 6, wherein one lens surface is a flat surface and the other lens surface is a convex lens surface, a Fresnel lens surface, a concave lens surface, or an aspheric lens surface.   The phosphor lens according to any one of claims 1 to 7, wherein the surface of the lens surface on the outgoing light side is a rough surface having fine irregularities or a pyramid texture.   A light emitting device comprising: the phosphor lens according to claim 1; and a light source that makes excitation light incident on one lens surface of the phosphor lens.

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