JP3287775B2 - Method and apparatus for measuring quantum efficiency of phosphor - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a method for measuring the quantum efficiency of a phosphor and an apparatus for measuring the quantum efficiency of the phosphor.

[0002]

2. Description of the Related Art The quantum efficiency of a fluorescent material is extremely important as a measure for determining the limit of the efficiency that a fluorescent material for a lamp can attain, for example, and two methods, an absolute value method and a relative value method, have been mainly used. .

In the absolute value method, the number of photons and the number of fluorescent photons of excitation light absorbed by a phosphor are measured independently, and the ratio is obtained. The number of photons of the excitation light absorbed by the phosphor is
For a single wavelength of excitation radiation, measure the irradiance on the phosphor surface using a thermal radiation detector such as a thermopile or an absolute radiometer, and reflect the absolute reflectance of barium sulfate etc. As a standard, the reflectance of the phosphor surface was
-The absorptance was determined from the reflectance, and the photon of the absorbed energy was determined from both values. Then, by measuring the relative fluorescence spectrum from the phosphor minute optical photometer, the absolute amount, the front of the previous thermal type radiation detector or an absolute radiometer, by mounting an optical filter for removing an excitation light , And derive the number of fluorescent photons to determine the quantum efficiency of the phosphor.

[0004] The relative value method is a method of obtaining a relative value of the quantum efficiency by comparative measurement using the quantum efficiency of a certain phosphor as a standard.

[0005]

However, in the absolute value method, since the sensitivity of a thermal radiation detector or an absolute radiometer for quantitatively measuring the number of photons of excitation light and the number of fluorescent photons is low, sufficient measurement accuracy is obtained. There was a problem that could not be obtained.

In the relative value method, although accuracy can be obtained, there is a problem that the quantum efficiency of the standard phosphor must be obtained by the absolute value method (Journal of the Illuminating Engineering Institute, Vol. 69, No. 2 (1985). ) Quantum efficiency of various lamp phosphors).

An object of the present invention is to provide a method for measuring the quantum efficiency of a phosphor, which can accurately measure the quantum efficiency of the phosphor in consideration of the problems of the conventional method for measuring the quantum efficiency of the phosphor. Things.

[0008]

SUMMARY OF THE INVENTION An integrating sphere is mounted on a phosphor to be measured such that the phosphor surface is located at a first window of the integrating sphere. Irradiates the excitation surface, illuminates the phosphor surface with the excitation radiation, integrates the reflection spectrum and the fluorescence spectrum emitted from the phosphor surface with the integrating sphere, and mounts the spectrometer mounted on the third window of the integrating sphere. Measure with The outputs of the spectrophotometer at this time are R (λ) and P (λ), respectively. At this time,
If the correction coefficients for the integration efficiency of the integrating sphere and the efficiency of the spectrophotometer are η and K · f (λ), respectively, the reflection spectrum of the excitation radiation on the phosphor surface is η · K · f (λ) · R (Λ), the fluorescence spectrum is η · K · f (λ) · P (λ). Next, instead of the phosphor, a reflectance standard with a known reflectance is attached to the first window of the integrating sphere and the same measurement is performed to obtain the spectral irradiance η · K incident on the phosphor surface of the excitation radiation.・ F
(Λ) · 1 / α (λ) · E (λ) is obtained. Then α
(Λ) is the spectral reflectance of the reflectance standard, and E (λ) is the reading of the spectrophotometer at this time. From this result, the spectral energy distribution of the excitation radiation absorbed by the phosphor is:

[0009]

Η · K · f (λ) · (1 / α (λ)) · E (λ) −η · K · f (λ) · R (λ) = η · K ｛f (λ) · Since (1 / α (λ)) · E (λ) −f (λ) · R (λ)｝ = η · K · A (λ), the quantum efficiency ε is

[0010]

(Equation 2)

Λ1, λ2: wavelength range in which the fluorescence spectrum exists λ3, λ4: wavelength range of the excitation spectrum, η and K need not be obtained by an absolute radiometer, etc. Can guide quantum efficiency.

In this way, there is no need to measure the absolute amount of η with an absolute radiometer or the like, thereby eliminating measurement errors and realizing accurate measurement of the absolute amount of quantum efficiency of the phosphor.

[0013]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing one embodiment of the present invention. In the figure, a first window 2 of an integrating sphere 1
Then, the phosphor 3 to be measured is attached. Radiation from a light source 4 as a radiation source for exciting the phosphor 3 is focused on the phosphor surface 3 by an optical system 5 through a second window 6 of the integrating sphere 1. At that time, the radiation is transmitted to the optical filter 7.
Thus, the excitation wavelength band to be measured is restricted.

The reflection spectrum and the fluorescence spectrum of the excitation radiation emitted from the phosphor 3 are integrated by the integrating sphere 1 and the spectrometer 9 mounted on the third window 8 of the integrating sphere 1
Measure with The output of the spectrophotometer at this time is R
(Λ) and P (λ).

Next, the same measurement is performed by replacing the phosphor 3 with the reflectance standard 10, and the spectral irradiance of the excitation radiation incident on the phosphor 3 surface is measured. At this time, the spectrophotometer 9
Is E (λ). The correction coefficients for the integration efficiency of the integrating sphere 1 and the efficiency of the spectrophotometer 9 are η and K · f, respectively.
(Λ), the reflection spectrum of the excitation radiation on the phosphor 3 surface is η · K · f (λ) · R (λ), and the fluorescence spectrum is η
K · f (λ) P (λ) Further, if α (λ) is the spectral reflectance of the reflectance standard, the spectral irradiance η · K · f (λ) · (1 / α (λ)) ·
E (λ) is obtained. A reflectance standard 10 is attached to the second window 6 of the integrating sphere 1, and the light of the standard irradiance standard bulb is
By illuminating the reflectance standard and measuring with a spectrometer 9 mounted on the third window 8 of the integrating sphere 1, the relative spectral energy distribution of the measurement system with respect to wavelength is calibrated. The relative spectral distribution valued to the standard spectral irradiance light bulb is
(Λ), if the output of the spectrophotometer at this time is Sr (λ),

[0017]

F (λ) = S (λ) / Sr (λ), so that f (λ) · R (λ) and f (λ) · P
(Λ), f (λ) · E (λ) are obtained as relative values. From this result, the spectral energy distribution of the excitation radiation absorbed by the phosphor is given by the following equation.

[0018]

Η · K · f (λ) · (1 / α (λ)) · E (λ) −η · K · f (λ) · R (λ) = η · K ｛f (λ) · (1 / α (λ)) · E (λ) −f (λ) · R (λ)｝ = η · K · A (λ) The quantum efficiency ε of the phosphor is represented by the number of photons of the excitation light and the number of fluorescent photons. Divided by

[0019]

(Equation 5)

Λ1, λ2: wavelength range where the fluorescence spectrum exists λ3, λ4: wavelength range of the excitation spectrum

[0021]

(Equation 6)

The quantum efficiency of the phosphor can be derived with high accuracy from the relative spectral distribution measured using one measuring optical system without having to determine η with an absolute radiometer or the like.

The correction coefficient η with respect to the integration efficiency of the integrating sphere is a reflectance of the inner wall of the integrating sphere and is a function of the wavelength. When a barium sulfate or PTFE powder is pressed, a wavelength of 250 nm is used. In the range of 800 nm, the reflectance is 9
0% or more, and can be regarded as constant with respect to the wavelength.

When a low-pressure mercury discharge lamp is used as the light source 4, an interference filter that transmits radiation near a wavelength of 254 nm is used as the optical filter 7, and f (λ) · R (λ) when a blue phosphor is used as the phosphor 3 is used. ), F (λ) · P (λ), f (λ) · E
FIG. 2 shows an example of the measurement result of (λ).

Next, a third embodiment will be described with reference to FIG. According to a third aspect of the present invention, in the first embodiment, the reflection spectrum and the fluorescence spectrum of the excitation radiation emitted from the phosphor 3 surface, the radiation component of 45 ° with respect to the normal to the phosphor 3 surface, The light is introduced into the spectrophotometer 9 and measured by a field lens 12 mounted on the front surface of the entrance slit of the spectrophotometer 9.

Next, instead of the phosphor 3, the excitation radiation is made incident on a spectral reflectance standard 10, and a reflection component of 45 ° with respect to the normal of the reflection surface is reflected by the plane mirror 11 and the field lens. The spectrophotometer 9 is introduced into the spectrophotometer 9 and measured, and the gonio characteristic of reflection on the phosphor screen 3 (spatial distribution of intensity with respect to the incidence / emission angle, light distribution characteristic) and the gonio characteristic of fluorescence emission are similar. As is the reflection spectrum,
The output of the spectrophotometer when measuring the fluorescence spectrum is R
(Λ), P (λ), when measuring the reflectance spectrum of the reflectance standard
The quantum efficiency is calculated assuming that the output of the spectrophotometer is E (λ) .

Next, a fifth embodiment will be described with reference to FIG. In the configuration of claim 1, when the integrating sphere 1 is small, of the excitation radiation focused on the phosphor surface 3 through the second window 6 of the integrating sphere 1 by the optical system 5,
After the component reflected on the phosphor surface 3 is repeatedly reflected on the inner wall of the integrating sphere 1, the component is again incident on the phosphor surface 3 to excite the phosphor 3. Then, as shown in FIG. 4, in order to obtain a fluorescence component by this re-excitation, one end is made incident on the inner wall of the integrating sphere 1 through the second window 6 of the integrating sphere 1, and the fluorescence emitted by the reflected component is emitted. Is measured. FIG. 5 shows the fluorescence emission spectrum by the re-excitation radiation in comparison with the fluorescence emission component when the excitation radiation is directly incident on the phosphor. Both are normalized by the peak intensity of the excitation emission spectrum. When a phosphor surface having a diameter of 15 mm is measured with an integrating sphere having a diameter of 6 cm, in a blue phosphor having a reflectance of 10% and a quantum efficiency of 85%, 1.5% in terms of quantum efficiency is a fluorescence emission component by re-excitation. Assuming that the output of the spectrophotometer of the re-excitation emission spectrum and the fluorescence emission spectrum thereby is Rr (λ) and Pr (λ), the fluorescence emission component P ′ (λ) excluding the re-excitation is given by the following equation.

[0028]

P ′ (λ) = P (λ) −Pr (λ) · ｛Rr (λ
p) / R (λp)｝ where λp is the peak wavelength of the excitation emission spectrum and the re-excitation emission spectrum. Instead of this peak wavelength ratio, a ratio of values obtained by integrating Rr (λ) and R (λ) with respect to wavelength in a wavelength range where the emission spectrum exists can be applied to (Equation 7). . If this P ′ (λ) is P (λ) in (Equation 6), the quantum efficiency excluding the influence of re-excitation can be obtained.

It should be noted that claims 2 and 4, and claim 6
The invention of claim 1 is a case where the excitation radiation having a single wavelength is used, while the excitation radiation having a wavelength spread is used in each of claims 1, 3 and 5.

[0030]

As is apparent from the above description,
According to the present invention, there is no need to measure the absolute amount of η with an absolute radiometer or the like, thereby eliminating measurement errors and realizing accurate measurement of the absolute amount of the quantum efficiency of the phosphor.

[Brief description of the drawings]

FIG. 1 is a configuration diagram of a measurement system according to an embodiment of the present invention.

FIG. 2 is a graph showing an example of measured values of spectral distribution characteristics of a blue phosphor in the embodiment of FIG.

FIG. 3 is a configuration diagram of a measurement system according to a third embodiment of the present invention.

FIG. 4 is a configuration diagram of a measurement system according to a fifth embodiment of the present invention.

FIG. 5 is a graph showing an example of measured values of spectral distribution characteristics of a blue phosphor according to the embodiment of the present invention.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 integrating sphere 2 first window of integrating sphere 3 phosphor 4 light source 5 optical system 6 second window of integrating sphere 7 optical filter 8 third window of integrating sphere 9 spectrometer 10 spectral reflectance standard 11 plane mirror 12 Field lens

──────────────────────────────────────────────────続 き Continuation of the front page (56) References JP-A-3-138539 (JP, A) JP-A-3-138538 (JP, A) JP-A-10-73486 (JP, A) ADV. MATER. , 9 [3] (1997), p230-232 MOL. CRYST. LIQ. CRY ST. , VOL. 283 (1996), pp. 51-56 (58) Fields investigated (Int. Cl. ⁷ , DB name) G01J 3/00-3/52 G01N 21/62-21/74 G01J 1/00-1/60 JICST file (JOIS) Practical file (PATOLIS) Patent file (PATOLIS)

Claims (8)

(57) [Claims] 1. A single wavelength radiation is incident on a phosphor to be measured, the reflected component of the phosphor surface of the single wavelength radiation and the total radiation of the fluorescent light excited by the single radiation. The components are integrated by an integrating sphere and the spectral energy distribution is measured with a spectrophotometer mounted on the window of the integrating sphere, and then, instead of the phosphor, a spectral reflectance standard is applied to the single wavelength radiation is incident, the integrated by the total reflection component the integrating sphere, the spectral distribution in said spectral photometric unit measures, the at wavelengths is incident radiation in phosphor surface reflection measurements at the phosphor surface From the measured reflectance at the spectral reflectance standard and the absolute reflectance of the spectral reflectance standard for the wavelength, calculate the absorption energy and the amount of photons absorbed by the phosphor, and then measure the fluorescence emission measured at the phosphor surface Spectrum Calculating the quantum efficiency of the phosphor from the ratio of the quantum of light absorbed by the phosphor and the quantum of light emitted by the fluorescent light, wherein the quantum efficiency of the phosphor is calculated. . 2. Exciting radiation is incident on a phosphor to be measured, and a reflection component of the radiation on the phosphor surface and a total emission component of fluorescence emission excited by the radiation are integrated by an integrating sphere, The spectral energy distribution is measured by a spectrophotometer attached to the window of the integrating sphere, and then, instead of the phosphor, the excitation radiation is incident on a spectral reflectance standard, and the total reflection component is integrated by the integration. Integrate with a sphere, measure its spectral distribution with the spectrophotometer, measure the reflectance of the radiation incident on the phosphor surface at the phosphor surface, the reflectance measurement value at the spectral reflectance standard, and the spectral reflectance standard. From the absolute reflectance for the wavelength, the absorption energy of the phosphor and the amount of absorbed photons are calculated, and then, from the spectrum measured on the phosphor surface, the spectrum of the excitation radiation is separated and removed, and the remaining spectrum is removed. Calculating the photon quantity from the fluorescence emission spectrum, and calculating the quantum efficiency of the phosphor from the ratio of the photon quantity absorbed by the phosphor and the photon quantity of the fluorescence emission, wherein the quantum efficiency of the phosphor is calculated. Efficiency measurement method. 3. A single-wavelength radiation impinging on the phosphor to be measured, wherein the single-wavelength radiation has a reflection component substantially 45 ° with respect to a normal of the phosphor surface, and the single-wavelength radiation. A radiant component of substantially 45 ° with respect to a normal to the phosphor surface of the fluorescent light excited by is guided to a spectrophotometer by an optical system, and the spectral energy distributions of both components are measured simultaneously. instead of phosphor, the spectral reflectance standard, said to be incident radiation of a single wavelength, by the optical system substantially 45 ° reflection component with respect to the normal of the reflecting surface, in the spectroscopic measurement light controller Guide, measure the spectral distribution thereof, at the wavelength of the radiation incident on the phosphor surface, the reflection measurement value on the phosphor surface, the reflection measurement value on the spectral reflectance standard and the wavelength of the spectral reflection standard on the wavelength. From the absolute reflectance, the absorption of the phosphor Calculate the energy and the amount of absorbed light quantum, and then calculate the amount of light quantum from the fluorescence emission spectrum measured on the phosphor surface, from the ratio of the amount of light quantum absorbed by the phosphor and the amount of light quantum of the fluorescence emission, A method for measuring the quantum efficiency of a phosphor, comprising calculating the quantum efficiency of the phosphor. 4. The excitation radiation is incident on the phosphor to be measured, the reflection component of the excitation radiation being substantially 45 ° with respect to the normal to the phosphor surface, and the fluorescence emission excited by the excitation radiation. , Substantially 4 with respect to the normal to the phosphor surface.
5% radiation component is guided to the spectrophotometer by the optical system,
The spectral energy distributions of both were measured simultaneously, and then
Instead of the phosphor, the excitation radiation is incident on a spectral reflectance standard, and a reflection component of substantially 45 ° with respect to a normal of the reflection surface is guided by the optical system to the spectroscope.
The spectral distribution is measured, and at the wavelength of the radiation incident on the phosphor surface, the reflection measurement value at the phosphor surface, the reflection measurement value at the spectral reflectance standard, and the absolute reflection at the wavelength of the spectral reflection standard. From the rate, the absorption energy of the phosphor and the amount of light quantum absorbed are calculated, and then from the fluorescence emission spectrum measured on the phosphor surface, the amount of light quantum is calculated, and the amount of light quantum absorbed by the phosphor and the fluorescence A method for measuring the quantum efficiency of a phosphor, characterized in that the quantum efficiency of the phosphor is calculated from a ratio of light quantum amounts of light emission. 5. A single wavelength radiation is incident on the phosphor to be measured, the reflected component of the phosphor surface of the single wavelength radiation and the total emission of the fluorescent emission excited by the single radiation. The components are integrated by an integrating sphere, and the spectral energy distribution is measured by a spectrophotometer attached to the window of the integrating sphere, and then the single wavelength radiation is incident on the inner wall of the integrating sphere, Is integrated into the phosphor, and the fluorescence emission component is measured by the spectrophotometer, subtracted from the total emission component of the fluorescence emission measured earlier, reflected on the phosphor surface and reflected by the inner wall of the integrating sphere. The fluorescence emission component generated by being incident on the phosphor again is removed, and only the entire emission component of the fluorescence emission by the first input emission of the single emission is separated,
Then, instead of the phosphor, the spectral reflectance standard, the radiation of a single wavelength is incident, and integrating the total reflection component by said integrating sphere, to measure the spectral distribution in the spectroscopic measurement light controller At the wavelength of the radiation incident on the phosphor surface,
From the reflectance measurement value on the phosphor surface, the reflectance measurement value on the spectral reflectance standard and the absolute reflectance for the wavelength of the spectral reflectance standard, calculate the absorption energy and the absorbed photon quantity of the phosphor, Calculating the quantum of light from the fluorescence emission spectrum measured on the phosphor surface, and calculating the quantum efficiency of the phosphor from the ratio of the quantum of light absorbed by the phosphor and the quantum of the fluorescence. Characteristic method for measuring quantum efficiency of phosphor. 6. The excitation radiation is incident on the phosphor to be measured, and the reflected component of the radiation on the phosphor surface and the total emission component of the fluorescent emission excited by the radiation are integrated by an integrating sphere, The spectral energy distribution is measured by a spectrophotometer attached to the window of the integrating sphere, and then the excitation radiation is made incident on the inner wall of the integrating sphere, integrated in the integrating sphere, made incident on the phosphor, and the fluorescence emission is obtained. The component is measured by the spectrophotometer, subtracted from the total emission component of the fluorescence emission measured earlier, reflected on the phosphor surface, reflected by the inner wall of the integrating sphere, and again incident on the phosphor to generate the generated fluorescence. Removing the luminescent component, separating only the total radiant component of the fluorescence emission by the first input radiation of the excitation radiation, and then injecting the excitation radiation into a spectral reflectance standard instead of the phosphor, Total reflection component Integrating with an integrating sphere, measuring the spectral distribution with the spectrophotometer, measuring the reflection on the phosphor surface of the radiation incident on the phosphor surface, measuring the reflection with the spectral reflectance standard, and measuring the spectral reflection. From the standard absolute reflectance for the wavelength, the absorption energy of the phosphor and the amount of absorbed photons are calculated, and then the spectrum of excitation radiation is separated and removed from the spectrum measured on the surface of the phosphor, and the remaining fluorescence emission Calculating the quantum efficiency of the phosphor from the spectrum, calculating the quantum efficiency of the phosphor from the ratio of the optical quantum absorbed by the phosphor and the photoquantity of the fluorescence emission. Method. 7. An integrating sphere having first, second, and third windows opened at a predetermined position, an optical system, and a spectrometer, and the first window has fluorescence to be measured. A body and a reflectance standard may be disposed, wherein said second window is disposed with said optical system;
7. The phosphor quantum efficiency measuring apparatus, wherein the spectrometer is arranged in the third window, and the phosphor quantum efficiency measuring method according to claim 1, 2, 5, or 6 can be executed. 8. An optical system, a plane mirror, a field lens, and a spectrometer, wherein a single-wavelength radiation or excitation radiation emitted from the optical system is incident on a phosphor or a spectral reflectance standard. 5. The phosphor quantum efficiency measuring apparatus according to claim 3, wherein said method is capable of executing the phosphor quantum efficiency measuring method according to claim 3.