JP2013073885A - Light-storage lighting apparatus - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a light-storage lighting apparatus storing energy of daytime sunlight and exerting an illumination function of a luminance of 1,000 mcd/m(1 cd/m) or more after elapse of 5 hours after sunset.SOLUTION: An ultrafine foam reflecting sheet 3 is arranged at a bottom part of box-shaped transparent case 1, a light-storage plate 2 is arranged at an upper part of the transparent case 1, and a space S is provided between the ultrafine foam reflecting sheet 3 and the light-storage plate 2. Further, a rear face of the light-storage plate 2 is embossed in a micro rugged shape.

Description

The present invention relates to a phosphorescent lighting device that can store a large amount of light energy from sunlight or the like during the daytime and exhibits excellent afterglow performance by efficiently taking out the light energy stored at night.

In the event of a major earthquake such as the Great East Japan Earthquake, it is expected that it will become a solitary island on the land due to road breaks, etc. In such cases, it is indispensable to transport and rescue relief supplies from the air route by helicopter.
Therefore, in each municipality, helicopters are drawn on the roofs of public facilities such as schools and city halls in order to make it easier for helicopters to receive assistance and rescue. As a helicopter, for example, in Matsuyama City, the letter “Dōgo Elementary” is drawn with paint on the roof of Dogo Elementary School.
In this case, the helicopter can be confirmed during the daytime, but if electricity is interrupted at night, the location cannot be confirmed. Therefore, you will not be able to land.
The phosphorescent member is effective in such cases, but even if sunlight energy is stored in the daytime, the absolute amount of stored light energy is small, and only a small part of the stored light energy can be extracted as light. Therefore, the current situation is that the brightness is not so high that the location can be recognized from the sky.

  In Patent Document 1, Patent Document 2, and Patent Document 3, the structure of each phosphorescent material is shown, but what can be said in common is that a reflective layer is provided directly on the back surface of the phosphorescent layer and light is extracted from both the front surface and the back surface. In other words, light is extracted only from one side (surface).

JP 2011-17210 A JP 2009-157201 A JP 2009-163022 A

In describing the problems of Patent Document 1, Patent Document 2, and Patent Document 3, a mechanism of light storage to light emission of the light storage material and a mechanism of emitting the emitted light to the outside will be described.

First, regarding the mechanism of phosphorescence to luminescence, an alkaline earth-aluminate phosphorescent material having a light emission center of Eu ⁺² is generally used as the phosphorescent material. As a specific example, SrAl ₂ O ₄ is used as a crystal matrix. The mechanism of phosphorescence to light emission will be described taking EuO as an activator and Dy ₂ O ₃ as an activator as an example.

As shown in FIG. 1, Eu ²⁺ dissolved in the SrAl ₂ O ₄ crystal matrix absorbs light (ultraviolet) energy, and electrons in the 4f level are excited to the 5d level. The holes generated by the above are captured and stored in Dy ³⁺ introduced as an activation aid by moving through the valence band. As shown in FIG. 2, the light emission mechanism is such that holes trapped by Dy ³⁺ are released by thermal energy, recombine with electrons excited in the 5d level by moving through the valence band, and emit light.

Next, a mechanism for emitting emitted light to the outside will be described. As shown in FIG. 3, half of the emitted light is emitted toward the front surface, and the other half is emitted toward the reflective layer on the back surface. As shown in FIG. 4, the light directed toward the surface is absorbed by the absorber (for example, carbon that has entered the SrAl ₂ O ₄ crystal matrix) existing in the phosphorescent layer before reaching the surface portion. Arrive at the department.
Here, only a part of the light arriving at the front surface is emitted to the outside, and most of the light is reflected and travels in the reverse direction. The reason why only a part of the light is emitted to the outside is that if the refractive index of the phosphorescent layer is 1.5, for example, there is a critical angle for total reflection with the external air layer (refractive index 1.0). This is because all light hitting the surface at an incident angle of 41.8 degrees or more is totally reflected.

Even when proceeding in the direction of the back surface, the light reaches the back surface part while being absorbed by the absorber existing inside the phosphorescent layer. The light arriving at the back surface is reflected while absorbing a part of energy by the reflection layer, and proceeds in the direction of the surface. In this way, while repeating the reflection on the front surface portion and the back surface portion, the energy is finally absorbed and the light disappears. An ideal material that does not have an absorber inside the phosphorescent layer and does not absorb in the reflective layer should be made, but in reality, most of the stored light energy is absorbed and converted into heat energy, and the remaining one Since part of the light is emitted to the outside, the light extraction efficiency is a very small value.

  As shown in FIG. 5, the light directed toward the reflective layer on the back surface is also absorbed by the majority of the stored light energy and converted into thermal energy, and the remaining part of the light is emitted to the outside. Therefore, the light extraction efficiency is a very small value. Since the light is emitted to the outside by the mechanism as described above, the light extraction efficiency is greatly improved if a structure in which light is emitted from both the front surface and the back surface without having a reflective layer on the back surface.

Specifically, the difference in light extraction efficiency between when the reflective layer is provided on the back surface and when it is not provided will be calculated on the desk. FIGS. 6A and 6B are diagrams illustrating light extraction values when the reflective layer is provided and values at which light attenuates. Values of light extraction in FIGS. 6A and 6B are shown. Is the light extraction efficiency. In the calculation result, (6.8% + 3.3% + 1.6% + 0.8% +...) + (4.9% + 2.4% + 1.2% + 0) .6% + ...) = 13.2% + 9.5% = 22.7% of light is extracted from the surface.

  Explaining a specific calculation example, FIG. 6 (a) is a table that describes the light extraction value when 50% of the light travels in the surface direction and the light attenuation value. When calculating the distance from the back to the back surface, 20% of the light energy is absorbed, 10% of the light energy is absorbed in the reflective layer, and 15% of the light energy reaching the surface can be extracted outside. The light extraction efficiency at this time is 6.8% + 3.3% + 1.6% + 0.8% +... = (50% × 0.9 × 0.15) ÷ (1- (1-0.15 ) × 0.8 × 0.9 × 0.8) = 13.2%.

FIG. 6B shows the light extraction value when 50% of the light travels in the direction of the back surface, and the value at which the light attenuates. The calculation condition is light when the distance from the front surface to the back surface proceeds. 20% of the energy is absorbed, 10% of the light energy is absorbed in the reflection layer, and 15% of the light energy reaching the surface can be extracted to the outside. The light extraction efficiency at this time is 4. 9% + 2.4% + 1.2% + 0.6% + ... = (50% × 0.9 × 0.9 × 0.8 × 0.15) ÷ (1- (1-0.15) × 0.8 × 0.9 × 0.8) = 9.5%.

6 (c) and 6 (d) are diagrams illustrating the light extraction value when the reflection layer is not provided and the value at which the light attenuates. FIGS. 6 (c) and 6 (d) 4 illustrate the light extraction value. The sum of the values is the light extraction efficiency, which is (6.8% + 4.6% + 3.1% + 2.1% + 1.4% + 1.0% + 0.7% +...) + (6.8 % + 4.6% + 3.1% + 2.1% + 1.4% + 1.0% + 0.7% + ...) = 21.1% + 21.1% = 42.2% Become.

  Explaining a specific calculation example, FIG. 6C is a diagram describing a light extraction value when 50% of the light travels in the surface direction and a value at which the light is attenuated. When the distance from the back surface to the back surface is advanced, 20% of the light energy is absorbed and 15% of the light energy reaching the front and back surfaces can be extracted to the outside. The light extraction efficiency at this time is 6.8. % + 4.6% + 3.1% + 2.1% + 1.4% + 1.0% + 0.7% +... = (50% × 0.9 × 0.15) ÷ (1- (1-0 .15) × 0.8) = 21.1%.

FIG. 6 (d) shows the light extraction value when 50% of the light travels in the direction of the back surface and the value at which the light attenuates. The calculation condition is light when the distance from the front surface to the back surface proceeds. Calculated when 20% of the energy is absorbed and 15% of the light energy reaching the front and back surfaces can be extracted to the outside. The light extraction efficiency at this time is 6.8% + 4.6% + 3.1% + 2.1% + 1.4% + 1.0% + 0.7% + ... = (50% × 0.9 × 0.15) ÷ (1− (1−0.15) × 0.8) = 21.1%.

From the above calculation results, when the reflective layer is not provided, the light extraction efficiency is about 1.9 times that when the reflective layer is provided, and the light extraction efficiency is greatly improved.
For the above reasons, the problem of Patent Document 1, Patent Document 2, and Patent Document 3 is that the efficiency of extracting stored light is low.

An object of the present invention is to store daytime sunlight energy and to exhibit an illumination function with a luminance of 1000 mcd / m ² (1 cd / m ² ) or more after 5 hours from sunset.

In order to solve the above-mentioned problems, the basic structure of the present invention is such that a cylindrical portion is integrally formed on the front side of the transparent case, a phosphorescent plate is provided at the tip opening of the cylindrical portion, and is surrounded by the cylindrical portion. A reflective plate is provided on the bottom surface of the transparent case, and a space is provided between the phosphorescent plate and the reflector plate for emitting visible light emitted from the rear surface portion of the phosphorescent plate to the outside, and the rear surface portion of the phosphorescent plate. The structure is provided with minute irregularities for scattering light.
By adopting such a structure, light can be emitted not only from the front surface but also from the back surface of the phosphorescent plate. However, there is a new problem that light emitted from the back surface hits the reflection plate and returns to the phosphorescent plate again.

In order to solve a new problem, the present invention has a structure in which minute unevenness for scattering light is further provided on the back surface of the phosphorescent plate.
With such a structure, the light emitted from the back side of the phosphorescent plate is scattered and emitted, and more light is emitted directly to the outside without hitting the reflecting plate. Further, a reflection plate having a diffuse reflectance of 90% or more was used as the reflection plate so that a larger amount of light emitted from the rear surface of the phosphorescent plate was emitted to the outside. By adopting such a structure, the light hitting the reflection plate is also greatly scattered, and most of the light is directly emitted to the outside without hitting the phosphorescent plate.

  For example, the space space and the minute irregularities are designed so that the ratio of the light emitted from the back side of the phosphorescent plate directly to the outside without colliding with the reflection plate is 60% or more. If the space space part and the reflection plate are designed so that the ratio of the light that is struck directly to the outside without colliding with the phosphorescent plate is 70% or more, the light emitted from the back side of the phosphorescent plate 88% can be taken out. The calculation formula at this time is expressed as 100% − (100% −60%) × (100% −70%) = 88%.

  When an ultrafine foamed reflective sheet manufactured by Furukawa Electric is used as the reflective plate material having a diffuse reflectance of 90% or more, the total reflectance is as high as 99%, and 96% of the reflected light is diffusely reflected. Will do.

An object of the present invention is to store sunlight energy in the daytime, and to exhibit a lighting function with a luminance of 1000 mcd / m ² (1 cd / m ² ) or more after 5 hours from sunset. In order to achieve the purpose, there is a problem that not only the efficiency of extracting the stored light energy is increased, but also a large amount of light energy must be stored.

  As a first measure for solving the above problems, the phosphorescent lighting device according to the present invention is a sintered body having a light-transmitting property that is densified to 98% or more of the theoretical density by hot pressing or the like as the phosphorescent plate. It was decided to use. When densified by hot pressing or the like, the fine pores existing in the sintered body are reduced, and thereby light scattering inside the phosphorescent plate becomes very weak, and the translucency is finally improved. If a sintered body having such translucency is used, the thickness of the phosphorescent plate can be increased, and as a result, a large amount of light energy can be stored.

  When the thickness of the non-translucent phosphorescent plate is increased, sunlight cannot reach the bottom of the phosphorescent plate due to the effect of light scattering due to minute pores etc. existing inside the phosphorescent plate, and can store a little light energy. Not only is this not possible, but the distance traveled when the reflection from the front surface to the back surface is repeated becomes longer, resulting in more light energy being absorbed.

As a specific example, when the thickness of a light-transmitting sintered body made of SrAl ₂ O ₄ and Eu ⁺² that is _an emission center is dissolved in about 0.5% of Sr in the crystal base is 2 mm, It is possible to store a huge amount of light energy that can emit light with a luminance of about 80 cd / m ² for 20 hours, and the luminance after 5 hours after sunset finally becomes 1000 mcd / m ² (1 cd / m ² ) The above lighting function can be exhibited.

  As a second measure for solving the above-mentioned problem, the phosphorescent illumination device according to the present invention has a spherical shape as the phosphorescent plate and is hollowed inside, and has excellent translucency in which the hollowed outer portion is densified. A transparent resin plate containing the phosphorescent powder material was used. In the phosphorescent powder material where the inside is hollowed out and the outside part that is hollowed out is densified, the number of pores existing inside the phosphorescent powder material is reduced, so that light scattering inside the phosphorescent powder material is weakened, and finally Translucency will be improved. In particular, it is effective to use a large spherical powder having a particle size of 50 μm or more, preferably 100 μm or more. If such a translucent phosphorescent plate is used, the thickness of the phosphorescent plate can be increased, and as a result, a large amount of light energy can be stored.

As a specific example, SrAl ₂ O ₄ is used as the crystal matrix, and Eu ⁺² that is the emission center is dissolved in about 0.5% of Sr in the crystal matrix. The outer part is spherical and hollow. If the thickness of the transparent resin plate containing a phosphorescent powder material with high density and excellent translucency is 8 mm, it is possible to store a huge amount of light energy that can emit light with a brightness of about 80 cd / m2 for 20 hours. Thus, it becomes possible to exhibit an illumination function with a luminance of 1000 mcd / m ² (1 cd / m ² ) or more after 5 hours have elapsed since sunset.

In this case, when an acrylic resin is used as the transparent resin, the refractive index is about 1.5, and the refractive index of the phosphorescent powder material is about 1.7, so the relative ratio of the refractive index is 1.7 ÷ 1.5 = 1. .13, and light scattering at the interface between the phosphorescent powder material and the acrylic resin becomes very weak. The above problem can be solved by dispersing such a phosphorescent powder material having excellent translucency in a transparent resin such as an acrylic resin.

The light-storing powder material having excellent translucency, which is spherical and has a hollow outer part and a dense outer part, is obtained by putting the light-storing powder material into an ultra-high temperature plasma atmosphere and rapidly cooling it. When the phosphorescent powder material is put in an ultra-high temperature plasma atmosphere, the charged material melts and becomes a spherical shape when rapidly cooled, and the inside becomes hollow, and the hollowed outer portion becomes dense, resulting in light transmission. A phosphorescent powder material having excellent properties can be obtained.
That is, when a phosphorescent powder material of about 50 μm to 100 μm is put into an ultra-high temperature plasma atmosphere, a large number of micropores existing inside the phosphorescent powder material are melted and rapidly cooled to gather in one place as an internal cavity. On the outside, a fine spherical powder having a fine pore size of about 50 μm to 100 μm is obtained.

According to the present invention, a large amount of light energy from sunlight or the like can be stored in the daytime, and a phosphorescent lighting device that exhibits excellent afterglow performance can be obtained by efficiently taking out the light energy stored at night.

A diagram showing the mechanism (1) of phosphorescence to light emission taking SrAl ₂ O ₄ as a crystal matrix, EuO as an activator, and Dy ₂ O ₃ as an activator. SrAl ₂ O ₄ as a host _crystal, shows a EuO as an activator, the mechanism of the phosphorescent-emitting took _Dy 2 _{O 3} as an example as an activator aid (2) The figure which shows the mechanism (1) by which the light emitted in the luminous layer is emitted to the outside The figure which shows the mechanism (2) by which the light emitted in the phosphorescent layer is emitted to the outside The figure which shows the mechanism (3) by which the light emitted in the luminous layer is emitted to the outside (A)-(d) is a figure which shows light extraction efficiency Sectional drawing of the phosphorescent illumination apparatus which concerns on this invention Enlarged sectional view of phosphorescent material particles

  Preferred embodiments of the present invention will be described below with reference to the accompanying drawings. FIG. 7 is a cross-sectional view of the phosphorescent illumination device according to the present invention. With reference to FIG. 7, the structure of the phosphorescent illumination device and the mechanism for extracting light to the outside will be described.

  As shown in FIG. 7, a cylindrical portion 1 a is formed in front of the transparent case 1 (left side in FIG. 7). The cylindrical portion 1a is arbitrary such as a cylindrical shape or each cylindrical shape. An ultrafine foamed reflection sheet 3 is disposed at the bottom surrounded by the tubular part 1a, and a phosphorescent plate 2 is disposed at the opening at the front end of the tubular part 1a. A space S is provided between them. In addition, the back surface (space space S side) of the phosphorescent plate 2 is embossed into a minute uneven shape.

  The phosphorescent plate 2 is made of a phosphorescent powder material and a transparent resin, and the particles of the phosphorescent powder material have a spherical shape in which the inside is hollowed and the hollowed outer portion is densified as shown in FIG. . In order to manufacture the phosphorescent powder material having such a structure, for example, the phosphorescent material or precursor obtained by sintering is powdered, and the obtained phosphorescent material or precursor is obtained to have a melting point higher than that of the phosphorescent material. A method of melting by heating and then rapidly cooling can be considered. Incidentally, the heating temperature is preferably 1700 ° C. or higher, and the cooling rate to 900 ° C. is preferably 400 ° C./second or higher, and the steps from the heating and melting to the rapid cooling are continuously performed by passing through the plasma region. Is possible.

  As shown in FIG. 7, the light energy of sunlight is stored inside the phosphorescent plate 2. When the stored light energy is emitted, a part of the emitted light is emitted to the outside from the surface portion of the light storage plate 2. Part of the emitted light is radiated from the back surface of the phosphorescent plate 2 to the space S.

  At this time, since the back surface of the phosphorescent plate 2 is embossed into a minute uneven shape, scattering of the emitted light occurs, and about 60% of the light emitted to the space S is emitted to the outside through the side surface of the transparent case 1. Is done. The remaining 40% of light reaches the ultrafine foamed reflective sheet 3 and is reflected and radiated again into the space S. However, since this member has a large diffuse reflectance of 96%, it was emitted into the space S. About 70% of the light is emitted to the outside through the side surface of the transparent case 1. With this mechanism, 88% of the light emitted from the back surface of the phosphorescent plate 2 can be taken out. The light extraction performance is further improved by embossing the surface portion of the phosphorescent plate 2 into a micro uneven shape.

At this time, if the thickness of the phosphorescent plate 2 is increased in order to store a large amount of light energy of sunlight, the sunlight reaches the bottom of the phosphorescent plate 2 due to light scattering due to fine pores etc. existing inside the phosphorescent plate 2 As a result, only a little light energy can be stored. For this reason, in the phosphorescent illumination device according to the present invention, the transparent resin plate having a spherical shape, the inside being hollowed out, and the hollowed out outer portion being densified and containing a phosphorescent powder material having excellent translucency is 8 mm in thickness. The phosphorescent plate 2 was used. Even if the thickness is as very large as 8 mm, it is possible to store a huge amount of light energy that can emit light having a luminance of about 80 cd / m @ 2 for 20 hours because it has little scattering and translucency, which is an object of the present invention. It becomes possible to exhibit an illumination function with a luminance of 1000 mcd / m ² (1 cd / m ² ) or more after 5 hours from sunset.

1 ... transparent case, 2 ... phosphorescent plate, 3 ... reflective sheet, S ... space

Claims (4)

A cylindrical portion is integrally formed on the front side of the transparent case, a phosphorescent plate is provided at a front end opening of the cylindrical portion, a reflecting plate is provided on a bottom surface of the transparent case surrounded by the cylindrical portion, and the phosphorescent A space for emitting visible light emitted from the back surface of the phosphorescent plate to the outside is provided between the plate and the reflection plate, and a minute unevenness for scattering light is provided on the back surface of the phosphorescent plate. A phosphorescent illuminating device. The phosphorescent illuminating device according to claim 1, wherein a reflecting plate having a diffuse reflectance of 90% or more is used as the reflecting plate to scatter light. The phosphorescent illumination device according to claim 1 or 2, wherein the phosphorescent plate is a sintered body having a light-transmitting property that is densified to 98% or more of a theoretical density. apparatus. 3. The phosphorescent illumination device according to claim 1 or 2, wherein the phosphorescent plate is a transparent resin plate that contains a phosphorescent powder material that is spherical and has a hollow inside and a hollow outside. A phosphorescent illumination device characterized by that.

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