JP2011244721A - Wavelength conversion member, and method for plant growth using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a wavelength conversion member in which protruding parts are not peeled off or collapsed during a long-term repeated use and an incident light is converted into the wavelength converted light effective for photosynthesis so as to improve light extraction efficiency, and to provide a method for plant growth using the wavelength conversion member.SOLUTION: The wavelength conversion member includes: an incident light surface in which an incident light enters from a light source; an outgoing light surface from which the wavelength converted light emits; and a plurality of protruding parts which are formed on the basis of at least either of the incident light surface or the outgoing light surface as a reference. The wavelength conversion member contains a fluorescent substance which converts the incident light into the wavelength converted light utilizable for plant growth. The protruding parts are formed by nanoimprint method and average heights of the protruding parts are less than 5 μm.

Description

  The present invention relates to a wavelength conversion member that converts incident light into a wavelength that can be used for plant growth and emits light, and a plant growth method using the same.

  2. Description of the Related Art Conventionally, methods for growing plants, vegetables and the like in greenhouses have been widely used, and plants and vegetables can be stably supplied regardless of the influence of nature.

  By the way, it is known that plants grow by absorbing light energy, that is, grow by performing photosynthesis. In general, chlorophyll α, which is contained in plants and has a role of absorbing light energy, has light absorption peak wavelengths near 420 nm and 660 nm, and light having a peak wavelength near 660 nm is used for photosynthesis. When directly absorbing light from a light source such as the sun, light in the short wavelength region other than the wavelength near 660 nm has low photosynthesis efficiency, so that incident light is converted into light having a wavelength that can be used for plant growth. A number of films have been proposed that have been converted and further improved in light extraction efficiency of wavelength-converted light.

  For example, by providing a plurality of grooves having a specific angle in a film containing a fluorescent agent excited by ultraviolet rays, it is converted into a wavelength effective for photosynthesis, and the amount of light necessary for plant growth is increased in winter. A film having a function of fading in the summer has been proposed (Patent Document 1).

  In addition, for example, a film has been proposed in which a plurality of fine convex structures are formed on one surface of a member containing a fluorescent substance, thereby improving the light extraction efficiency of the surface on which the convex structures are formed ( Patent Document 2).

  However, these proposals have the problem that the apex angle tends to be rounded and the light extraction efficiency decreases because the grooves and convex structures are formed by thermally transferring the surface of the film. In addition, since these proposed films are used in a harsh environment exposed to sunlight for a long time, when used for a long period of time, a plurality of convex structures and a plurality of locations between the grooves, It becomes easy to peel off or collapse at almost the same time, and the light extraction efficiency is drastically reduced. For this reason, there also existed a problem that the growth of a plant was suppressed notably.

  As described above, there is a strong demand for prompt development of a wavelength conversion member that has high light extraction efficiency and does not peel or collapse at the same time due to repeated use over a long period of time.

JP-A-5-153869 JP 2008-203324 A

  An object of the present invention is to solve the above-described problems and achieve the following objects. That is, the present invention provides a wavelength conversion member that converts incident light into a wavelength effective for photosynthesis and improves light extraction efficiency without causing a plurality of protrusions to peel or collapse at the same time due to repeated use over a long period of time. An object of the present invention is to provide a plant growing method using a wavelength conversion member.

Means for solving the problems are as follows. That is,
<1> It is formed on the basis of at least one of the light incident surface for receiving incident light from the light source, the light emitting surface for emitting wavelength-converted light, and the light incident surface and the light emitting surface. A plurality of convex portions, and a wavelength conversion member containing a phosphor that converts incident light into a wavelength that can be used for plant growth, wherein the convex portions are formed by a nanoimprint method, It is a wavelength conversion member characterized by the average height of a convex part being less than 5 micrometers.
<2> The wavelength conversion member according to <1>, wherein the area ratio of the protrusions is less than 30% with respect to the area of the surface on which the protrusions are formed.
<3> The wavelength conversion member according to any one of <1> to <2>, wherein the convex portion has a cone shape.
<4> In the above <3>, the average angle of the apex angles of the cross-sectional shapes cut from the height direction of the convex portions so as to be perpendicular to the surface on which the convex portions are formed is 60 ° to 120 °. It is a wavelength conversion member of description.
<5> From the above <3>, wherein the average angle of the base angles of the cross-sectional shape cut from the height direction of the convex portion to be perpendicular to the surface on which the convex portion is formed is 30 ° to 60 °. <4> The wavelength conversion member according to any one of the above.
<6> The wavelength conversion member according to any one of <4> to <5>, wherein the apex angle has a radius of curvature of 100 μm or less.
<7> The wavelength conversion member according to any one of <5> to <6>, wherein a curvature radius of a base angle is 100 μm or less.
<8> The convex portion is the wavelength conversion member according to any one of <1> to <7>, which the light exit surface has.
<9> A plant growth method for growing a plant using the wavelength conversion member according to any one of <1> to <8>, wherein the wavelength of light incident from a light incident surface of the wavelength conversion member The light emitting surface is arranged such that the light is converted into light having a wavelength that can be used for plant growth, and light is emitted from the light emitting surface of the wavelength conversion member to the plant growth field. This is a method for growing plants.

  According to the present invention, the above-described problems can be solved and the object can be achieved, and the present invention is a method in which incident light is released without peeling or collapsing a plurality of convex portions at the same time due to repeated use over a long period of time. Can be provided with a wavelength conversion member that converts the light into a wavelength effective for photosynthesis and increases the light extraction efficiency, and a plant growth method using this wavelength conversion member.

FIG. 1 is a perspective view showing an example of the wavelength conversion member of the present invention. FIG. 2 is a perspective view showing an example of another embodiment of the wavelength conversion member of the present invention. FIG. 3 is an enlarged cross-sectional view of a part of A-A ′ in FIG. 1. FIG. 4 shows the relationship between the wavelength at the light incident surface of the example and the comparative example and the wavelength of the light emitted from the wavelength-converted light emitting surface, the amount of light incident from the light incident surface, and the light emission. It is a figure which shows an example of the relationship with the light quantity of the light radiate | emitted from a surface. FIG. 5A is a photograph showing an example of the growth of Komatsuna in Example 1. FIG. 5B is a photograph showing an example of the growth of Komatsuna in Comparative Example 3. FIG. 6 shows the relationship between the wavelength at the light incident portion and the wavelength of the light emitted from the wavelength-converted light emitting portion, the amount of light incident from the light incident portion, and the light emitted from the light emitting portion. It is a figure which shows an example of the relationship with the light quantity of.

(Wavelength conversion member)
The wavelength conversion member of the present invention has a light incident surface, a light output surface, and a convex portion, and has other members as necessary.

The shape of the wavelength conversion member is not particularly limited and can be appropriately changed according to the purpose of use. Examples thereof include a rectangular shape, a square shape, and a circular shape, but are easy to process at low cost. Therefore, a rectangular shape is preferable.
The wavelength converting member is not particularly limited, and the light incident surface, the convex portion, and the light emitting surface may be formed by separate members, but can be manufactured at low cost. From the viewpoint, it is preferably formed from a series of members. In the present specification, the series of members may be simply referred to as members. The member may be a film, a sheet, or a flat plate.

  The material for forming the wavelength conversion member is not particularly limited as long as it is transparent and has a certain degree of strength, and examples thereof include resin and glass. Among these, resin is preferable because it is flexible and lightweight.

  The resin is not particularly limited and may be appropriately selected depending on the purpose. For example, the resin is not particularly limited and may be appropriately selected according to the purpose. For example, polystyrene, styrene / methyl Methacrylate copolymer, (meth) acrylic resin, polymethylpentene, allyl glycol carbonate resin, spirane resin, amorphous polyolefin, polycarbonate, polyamide, polyarylate, polysulfone, polyallyl sulfone, polyether sulfone, polyetherimide, polyimide Transparent materials such as diallyl phthalate, fluororesin, polyester carbonate, norbornene resin (ARTON), alicyclic acrylic resin (Optretz), silicone resin, acrylic rubber, silicone rubber, etc. It may be used alone or in combination of two or more thereof. Among these, polystyrene, polycarbonate, acrylic resin, PET, styrene- (meth) acrylic copolymer (MS polymer) and the like are preferable from the viewpoints of transparency, optical properties such as refractive index, and processability.

The haze of the wavelength conversion member is preferably 10% or less, more preferably 2% or less, and particularly preferably 0.5% or less.
When the haze exceeds 10%, the light collection efficiency and light guide efficiency for controlling the incident light and collecting light may be significantly reduced.
Here, the “haze” refers to a value of the degree of cloudiness, and is a value evaluated by a measuring device such as a haze meter (model number: HZ-1, manufactured by Suga Test Instruments Co., Ltd.) in accordance with JIS 7105, for example. is there.

-Phosphor-
The wavelength conversion member contains a phosphor, and the phosphor absorbs the incident light and converts the wavelength into light having a wavelength that can be used for plant growth.

  For example, in photosynthesis, there are various types of chlorophylls that are contained in plants and absorb light energy, but often absorb more light with wavelengths in the region of 400 nm to 500 nm and 600 nm to 750 nm. It is known. For this reason, by incorporating a phosphor that emits light in the vicinity of 600 nm to 750 nm into the wavelength conversion member, the light incident from the light incident surface is converted to a wavelength in the vicinity of 600 nm to 750 nm, and the photoelectric energy is converted into a wavelength from the light emitting surface. Light can be emitted, and photosynthesis can be effectively promoted. That is, by including the phosphor in the wavelength conversion member, light having a specific wavelength can be emitted from the light exit surface.

The wavelength conversion in the phosphor is not particularly limited, but when the peak wavelength of the light absorbed by the phosphor is λ ₁ (nm) and the peak wavelength of the wavelength-converted light is λ ₂ , it is preferred to have the ₁ <lambda ₂ relationship.
For example, as shown in FIG. 6, incident light using the sun or the like as a light source has a peak wavelength on a shorter wavelength side than the wavelength of light necessary for photosynthesis in plants, and the absorption efficiency for this incident light is high. If the wavelength-converted light has a peak wavelength on the longer wavelength side, it has a peak wavelength at the wavelength of light necessary for photosynthesis in the plant and can efficiently grow plants.
Further, the λ ₁ (nm) is preferably 300 nm to 700 nm, and the λ ₂ (nm) is preferably 400 nm to 1,000 nm.

  The phosphor is not particularly limited as long as the required wavelength can be enhanced, and can be appropriately selected according to the purpose. For example, DCM, DMETCI, DOCI, DODCI, DQOCI, DQTCI, HIDCI, etc. Fluorescent compound, indolenine, coumarin, cresyl violet, cyanine, fluorescein, malachite green, nile blue, oxazine, perylene compound, phenoxazone, phenylalanine, phthalocyanine, pinacyanin, porphine, proflavine, pyridine, pyromethene, rhodamine, riboflavin, stilbene, Examples include styryl compounds, sulforhodamine, uranin and the like. Among these, a perylene compound is preferable, and the perylene compound is not particularly limited as long as it emits fluorescence, and examples thereof include perylene, perylene red, and perylene orange.

Examples of the phosphor include, but are not limited to, the following.

There is no restriction | limiting in particular as content of the said fluorescent substance, Although it can select suitably according to the objective, 0.001 mg-20 mg are preferable with respect to 100 mg of said wavelength conversion members, for example, 0.01 mg-10 mg are More preferably, 0.1 mg to 5 mg is particularly preferable.
If the content is less than 0.001 mg, it may not be possible to effectively convert the wavelength of light incident from the light incident surface, and if it exceeds 20 mg, it may be difficult to maintain the shape. Also, depending on the type of phosphor, the amount of fluorescence may decrease.

<Light incident surface>
The light incident surface 11 is a surface on the side where incident light from a light source is incident.
There is no restriction | limiting in particular as said light source, According to the objective, it can select suitably, For example, artificial light sources, such as the sun (natural light), LED, a halogen lamp, etc. are mentioned.

  Although there is no restriction | limiting in particular as the said light-incidence surface 11, As shown in FIG. 1, you may make it have the light-incidence surface 11 in the whole surface of a wavelength conversion member, and as shown in FIG. You may make it have the light-incidence surface 11 in a part of surface. Among these, as shown in FIG. 1, it is preferable to have a light incident surface 11 on the entire surface of the wavelength conversion member in that light can be received in a large area.

There is no restriction | limiting in particular as the length of the said light-incidence surface 11, Although it can change suitably according to the objective, For example, 1 mm-5,000 mm are preferable, 5 mm-1,000 mm are more preferable, 20 mm-500 mm Is particularly preferred.
When the length is less than 1 mm, the amount of incident light may be too small, and when it exceeds 5,000 mm, the loss of light absorption by the wavelength conversion member may be too large.

There is no restriction | limiting in particular as the refractive index of the light in the said light-incidence surface 11, Although it can change suitably according to the objective, 1.05-1.8 are preferable and 1.1-1.75 are more preferable. 1.2 to 1.7 are particularly preferable, and 1.3 to 1.65 are most preferable.
If the refractive index is less than 1.05, the critical angle is too large, and much of the light propagating inside the member may leak, and if it exceeds 1.8, the interface reflection is large, and the light member The amount of incident light may decrease too much. The refractive index is measured by ellipsometry using, for example, an Abbe refractometer (manufactured by Atago Co., Ltd.).

<Light exit surface>
The light emitting surface 12 is a surface on the side from which the wavelength-converted light is emitted.
The light exit surface 12 is not particularly limited, but as shown in FIG. 1, the light exit surface 12 may be provided on the entire surface opposite to the light entrance surface, as shown in FIG. You may make it have the light-projection surface 12 in a part of member surface. Among them, as shown in FIG. 1, it is preferable to have a light incident surface 12 on the entire surface of the member in terms of increasing the light emission amount.

There is no restriction | limiting in particular as the length of the said light-projection surface 12, Although it can change suitably according to the objective, For example, 1 mm-5,000 mm are preferable, 5 mm-1,000 mm are more preferable, 20 mm-500 mm Is particularly preferred.
When the length is less than 1 mm, the emitted light may be too small, and when it exceeds 5,000 mm, the loss of light absorption by the member may be too large.

<Convex>
The convex portion 13 may be provided on either the light incident surface 11 or the light emitting surface 12, but is preferably provided on the light emitting surface 12 in terms of improving light extraction efficiency.

The average height H of the convex portion 13 is less than 5 μm, more preferably 0.01 μm to 4.5 μm, and particularly preferably 0.2 μm to 0.7 μm.
When the average height H is 5 μm or more, the plurality of convex portions 13 are likely to be peeled or collapsed at the same time due to repeated use over a long period of time, and may be costly. When the average height H is less than 0.01 μm, light emission is performed. The amount may be reduced.
The average height is, for example, an average value obtained by measuring ten heights of the convex portion 13 using a step meter.

As shown in FIG. 3, the average distance P (hereinafter also referred to as pitch interval) between the centers of adjacent convex portions 13 of the convex portions 13 is preferably 1 μm to 100 μm, more preferably 2 μm to 50 μm, and more preferably 1 μm to 2.5 μm is particularly preferable.
When the pitch interval P is less than 1 μm, the pitch interval P becomes too dense and the amount of transmitted light may decrease. When the pitch interval P exceeds 100 μm, the emission amount may decrease. The pitch interval is an average value obtained by measuring the circumscribed circle of each convex portion and measuring the distance between the centers of adjacent circumscribed circles when the member surface on which the convex portion 13 is formed is viewed from above. Say. Here, the circumscribed circle can be measured using, for example, an optical microscope.

The area ratio of the convex portion 13 is preferably less than 30%, more preferably 1% to 25%, and particularly preferably 5% to 20%.
When the area ratio exceeds 30%, the transparency of the wavelength conversion member 1 may be hindered, and the incidence of light may be reduced.
The area ratio refers to the occupied area of all the convex portions 13 per unit area, and the area ratio can be measured by, for example, microscopic observation.

There is no restriction | limiting in particular as a shape of the said convex part 13, Although it can change suitably according to the intended purpose, For example, hemispherical shape, cone shape, saw shape, bellows shape, square shape etc. are mentioned.
Examples of the cone shape include a triangular pyramid, a cone, and a quadrangular pyramid. Among these, a cone shape is preferable in terms of light emission efficiency.

When the shape of the convex part 13 is a cone shape, the cross-sectional shape cut | disconnected so that it may become a perpendicular direction toward the said light-projection surface 12 from the height direction of the said convex part 13 becomes a triangle.
As shown in FIG. 3, when the cross-sectional shape is a triangle, the average angle of the apex angle α is preferably 60 ° to 120 °, more preferably 65 ° to 115 °, and particularly preferably 70 ° to 110 °.
If the average angle of the apex angle α is less than 60 °, it may be easily damaged, and if it exceeds 120 °, the light emission efficiency may be too low. The average angle of the apex angle α is an average value obtained by cutting the wavelength converting member 1 from the height direction of the convex portion 13 in the direction perpendicular to the light emitting surface 12 and measuring the apex angles α of 10 points from the cross-sectional shape. Say. The apex angle α can be measured using, for example, an optical microscope.

As shown in FIG. 3, the average angle of the base angle β when the cross-sectional shape is a triangle is preferably 30 ° to 60 °, more preferably 33 ° to 58 °, and particularly preferably 35 ° to 55 °.
If the average angle of the base angle β is less than 30 °, the light emission efficiency may be low, and if it exceeds 60 °, the light emission efficiency may be easily reduced. The average angle of the base angle β is an average value obtained by cutting the wavelength conversion member 1 in the direction perpendicular to the light emitting surface 12 from the height direction of the convex portion 13 and measuring the base angle β of 10 points from the cross-sectional shape. Say. The base angle β can be measured using, for example, an optical microscope.

The radius of curvature of the apex angle (top) is preferably 100 μm or less, more preferably 1 μm to 90 μm, and particularly preferably 5 μm to 80 μm.
When the radius of curvature exceeds 100 μm, the light emission efficiency may be lowered.
The curvature radius can be measured by, for example, a three-dimensional measuring instrument.

The radius of curvature of the base angle (bottom) is preferably 100 μm or less, more preferably 1 μm to 90 μm, and particularly preferably 5 μm to 80 μm.
When the radius of curvature exceeds 100 μm, the light emission efficiency may be lowered.
The curvature radius can be measured by, for example, a three-dimensional measuring instrument.

-Method for forming protrusions-
There is no restriction | limiting in particular as a formation method of the said convex part 13, For example, although it can select suitably according to purposes, such as a cutting method, a nanoimprint method, a laser micromachining, an etching method, the thing of the same shape is formed uniformly For this reason, it is preferable to form the nanoimprint method.

As the nanoimprint method, the convex portion 13 can be formed by transferring in advance with a stamper (mold) having a desired concave-convex shape. Specifically, a photoresist layer made of a photoresist material is applied onto a stamper master (silicon substrate) by a spin coat method or the like, and laser light is condensed on the photoresist layer by an optical lens and irradiated. After forming the micropores, performing an etching process such as reactive ion etching (RIE), adjusting the depth of the micropores formed on the original plate, and then removing the photoresist layer, the desired irregularities are obtained. A stamper having a shape is produced.
A nanoimprint layer made of a nanoimprint material is formed on the light emitting surface 12 that emits light, the nanoimprint layer is pressed with the stamper, and heated or irradiated with light as necessary to form a convex portion 13 on the light emitting surface 12. Let

The photoresist material is not particularly limited and may be appropriately selected depending on the purpose. Examples thereof include a photoresist material that uses a normal photoreaction, and a photoresist material that uses a thermal reaction. Photoresist materials that can use thermal reactions are preferred in that they are fine, have a fine structure around the irregularities, and can exhibit a higher effect on light interaction.
Examples of photoresist materials that can use the thermal reaction include methine dyes (cyanine dyes, hemicyanine dyes, styryl dyes, oxonol dyes, merocyanine dyes, etc.), macrocyclic dyes (phthalocyanine dyes, naphthalocyanine dyes, porphyrin dyes, etc.), Examples thereof include azo dyes (including azo metal chelate dyes), arylidene dyes, complex dyes, coumarin dyes, azole derivatives, triazine derivatives, 1-aminobutadiene derivatives, transdermal acid derivatives, and quinophthalone dyes.

There is no restriction | limiting in particular as said nanoimprint material, According to the objective, it can select suitably, For example, the imprint resist composition containing at least any one of a thermoplastic resin and a photocurable resin is mentioned.
Examples of the imprint resist composition include novolac resins, epoxy resins, acrylic resins, organic glass resins, and inorganic glass resins.

The thickness of the photoresist layer is preferably 5% or more and less than 200% with respect to the average height of the protrusions 13 formed on the surface of the stamper.
If the thickness is less than 5%, the resist amount may be insufficient and the desired convex portion 13 may not be formed.

  As the thickness of the photoresist layer, for example, a part of the photoresist layer is peeled off from the light emitting surface 12 on which the photoresist layer is formed, and a step (height) after peeling is determined by an AFM apparatus (OLS, Olympus Corporation). Manufactured).

The viscosity of the imprint resist composition is preferably 1 mPa · s to 200 mPa · s at 25 ° C., and more preferably 1 mPa · s to 100 mPa · s.
The viscosity of the imprint resist composition can be measured using, for example, an ultrasonic viscometer.

<Other members>
Examples of the other members include a reflective layer and a light guide.

-Reflecting part-
You may make it have the reflection part 14 in the side surface in the said light-incidence surface 11 as needed.
There is no restriction | limiting in particular as long as it has a high reflectance as a forming material of the said reflection part 14, It can select suitably according to the objective, For example, metals, such as silver, aluminum, gold | metal | money, copper, magnesium, high refractive index TiO ₂ , ZnS, silicon and other dielectrics and semiconductors.

-Light guide-
As shown in FIG. 2, the light guide unit 15 is disposed between the light incident surface 11 and the light emitting surface 12, and guides the wavelength-converted light to the light emitting surface 12. The length of the wavelength conversion member 1 is appropriately changed.

There is no restriction | limiting in particular as the length of the said light guide part 15, Although it can change suitably according to a use purpose, For example, 10 mm-10,000 mm are preferable, 100 mm-5,000 mm are more preferable, 500 mm- 2,000 mm is particularly preferable.
If the length is less than 10 mm, the amount of light that can be guided is less and the efficiency may be lower than the length to guide light. May decrease.

(Plant growing method)
The plant growth method of the present invention is a method of growing a plant using the wavelength conversion member of the present invention, and uses the wavelength of light incident from the light incident surface 11 of the wavelength conversion member for plant growth. The light emitting surface 12 is arranged so as to be wavelength-converted to light having a possible wavelength and to be emitted from the light emitting surface 12 of the wavelength converting member to a plant growing place.

There is no restriction | limiting in particular as said plant cultivation place, The water area etc. which grow the algae containing the greenhouse which grows vegetables etc., and a micro algae are mentioned.
For example, in a greenhouse for growing vegetables or the like, the wavelength conversion member 1 is affixed to the inner surface of the greenhouse to efficiently extract light that has been converted to a wavelength at which plants such as vegetables can perform photosynthesis. be able to.

  Examples of the present invention will be described below, but the present invention is not limited to these examples.

Example 1
<Production of wavelength conversion member>
A fluorescent acrylic plate having a length of 200 mm, a width of 200 mm, a thickness of 2 mm, and a refractive index of 1.5 (manufactured by Acryya Co., Ltd., condensed red) is used. This surface was used as the light exit surface.

1 ml of 2,2,3,3-tetrafluoro-1-propanol, a compound A (30 mg) represented by the following structural formula as a photoresist compound on a silicon substrate having the same shape (200 mm × 200 mm) as the light emitting surface. The solution was applied to a thickness of 100 nm using a spin coat method while rotating at 1,000 rpm to form a photoresist layer on the silicon substrate.

  With respect to the photoresist layer formed on the silicon substrate, the pitch interval of the shortest distance between adjacent recesses at a linear speed of 5 m / s and 14 mW with PulseTech Kogyo NEO1000 (wavelength 405 nm, NA 0.85). A plurality of micropores were formed so that the average height was 3 μm and the concave shape was a cone. Thereafter, reactive ion etching (RIE) treatment is performed to adjust the depth of the plurality of fine holes in which the photoresist layer is formed to 3 μm, and the photoresist layer is adjusted to 2,2,3,3-tetrafluoro-1-propanol. Removed. The stamper was fabricated by removing the photoresist layer.

On this stamper, the imprint compound (PAK-01, manufactured by Toyo Gosei Co., Ltd.) was dropped, and an acrylic plate (manufactured by Acryya Co., Ltd., Condensed Red 2 mm thickness) was adhered. Light irradiation surface by irradiating twice on this acrylic plate under the conditions of a conveyor speed of 760 cm / min and 75 mJ / cm ² using a UV irradiator (ECS-401GX, manufactured by Eye Grandage Co., Ltd.) while being pressed with the stamper. Convex portions were formed on the surface, and the wavelength conversion member of Example 1 was produced.
The average height of the convex portion was measured at 10 points with a three-dimensional measuring instrument (manufactured by Olympus), and the average value was taken as the average height of the convex portion, and the average height was 3 μm.
The pitch interval is measured by measuring the circumscribed circle of the convex portion with a three-dimensional measuring instrument (manufactured by Olympus), measuring the distance between the centers of adjacent circumscribed circles at 10 points, and setting the average value as the pitch interval, and the pitch interval is 12 μm. Met.
The average angle of the apex angle and the average angle of the base angle of the cross section of the convex portion was measured with a three-dimensional measuring instrument (manufactured by Olympus), and the average value was taken as the average angle of the apex angle and the average angle of the base angle. The average apex angle was 90 ° and the average base angle was 45 °.
When the area ratio was measured with a three-dimensional measuring instrument (manufactured by Olympus), it was 25%.
When the radius of curvature of the apex and base angles was measured with a three-dimensional measuring instrument (Olympus), the radius of curvature of the apex angle was 10 μm and the radius of curvature of the base angle was 5 μm.

(Evaluation)
The ratio of the transmittance and the reflectance of the wavelength conversion member of Example 1, the cultivation test and the peel test were evaluated as follows. The results are shown in Table 1.

<Ratio of transmittance and reflectance>
For the wavelength conversion member transmittance, an integrating sphere was attached to a spectrophotometer (manufactured by Ocean Photonics, USB-2000), and the transmittance including fluorescence emission was measured for each wavelength of 400 nm to 700 nm. Light was incident from a direction perpendicular to the light incident surface of the wavelength conversion member, and the intensity of the light transmitted through the wavelength conversion member was compared with a blank value where the wavelength conversion member was not placed. The incident light wavelength was 550 nm.
For the reflectance of the wavelength conversion member, an integrating sphere is attached to a spectrophotometer (manufactured by Ocean Photonics, USB2000), the reflectance is measured for each wavelength of 400 to 700 nm, and fluorescence emission at an incident light wavelength of 550 nm is measured. The reflectance was included. Here, as a reference value, the reflectance of the standard white plate was set to 100%.
Based on the measured transmittance and reflectance, the ratio of transmittance and reflectance (transmittance / reflectance) was calculated.

<Plant growth evaluation>
As shown in FIG. 5A, the light output surface of the manufactured wavelength conversion member was set to the inside and the bottom, and the floor area of the plant growing place was covered with the wavelength conversion member so as to be about 40,000 mm ² (side 200 mm). A box was provided. 40 seeds of Komatsuna 922770 (Sakata Seed, Lot 356992, New Zealand) was embedded in the medium. In addition, vermiculite (manufactured by Cainz) was used as a medium, and a hyponica fertilizer (manufactured by Kyowa Co., Ltd.) diluted 500 times and dispersed in the medium was used.
Using an eco-lamp bulb (NIHONYUSAC, white 95W) as a light source, continue irradiation for 24 hours, and measure the total weight of 20 komatsuna grown 20 days after the day when the komatsuna seeds were buried in the medium. The plant growth was evaluated.

<Peel test>
The wavelength conversion member of Example 1 was placed in an atmosphere having a temperature of 80 ° C. and a humidity of 85% RH. After 3 days (72 hours), the state of the convex portion of the wavelength conversion member was observed and evaluated based on the following evaluation criteria.
〔Evaluation criteria〕
A: No peeling of the convex part B: Little peeling of the convex part (the peeling rate of the convex part is less than 5% of the whole convex part)
Δ: There is some peeling of the convex part (the peeling rate of the convex part is 5% or more and less than 10% of the whole convex part)
X: There are many peelings of a convex part, and it cannot endure use (the peeling rate of a convex part is 10% or more of the whole convex part)

(Example 2)
In Example 1, the wavelength conversion member in Example 2 was manufactured in the same manner as in Example 1 except that the average height of the protrusions was changed from 3 μm to 4.5 μm and the pitch interval was changed from 12 μm to 18 μm.
In the same manner as in Example 1, the ratio between transmittance and reflectance, plant growth evaluation, and peel test were performed. The results are shown in Table 1.

(Example 3)
In Example 1, the wavelength conversion member in Example 3 was manufactured in the same manner as in Example 1 except that the average height of the protrusions was changed from 3 μm to 0.6 μm and the pitch interval was changed from 12 μm to 2.4 μm. .
In the same manner as in Example 1, the ratio between transmittance and reflectance, plant growth evaluation, and peel test were performed. The results are shown in Table 1.

Example 4
In Example 1, the wavelength conversion member in Example 4 was manufactured in the same manner as in Example 1 except that the average height of the protrusions was changed from 3 μm to 0.3 μm and the pitch interval was changed from 12 μm to 1.2 μm. .
In the same manner as in Example 1, the ratio between transmittance and reflectance, plant growth evaluation, and peel test were performed. The results are shown in Table 1.

(Example 5)
Example 1 is different from Example 1 except that the average angle of the apex angle is 90 ° to 110 °, the average angle of the base angle is both 45 ° to 35 °, and the pitch interval is 12 μm to 17.1 μm. Similarly, the wavelength conversion member in Example 5 was manufactured.
In the same manner as in Example 1, the ratio between transmittance and reflectance, plant growth evaluation, and peel test were performed. The results are shown in Table 1.

(Example 6)
Example 1 is the same as Example 1 except that the average angle of the apex angle is 90 ° to 30 °, the average angle of the base angle is both 45 ° to 75 °, and the pitch interval is 12 μm to 3.2 μm. Similarly, the wavelength conversion member in Example 6 was manufactured.
In the same manner as in Example 1, the ratio between transmittance and reflectance, plant growth evaluation, and peel test were performed. The results are shown in Table 1.

(Example 7)
Example 7 is the same as Example 1 except that the average base angle is 45 ° to one 40 °, the other is 50 ° and the pitch interval is 12 μm to 18.3 μm. The wavelength conversion member in was manufactured.
In the same manner as in Example 1, the ratio between transmittance and reflectance, plant growth evaluation, and peel test were performed. The results are shown in Table 1.

(Example 8)
In Example 1, the wavelength conversion member in Example 8 was manufactured in the same manner as in Example 1 except that the area ratio was changed from 25% to 35% and the pitch interval was changed from 12 μm to 10.2 μm.
In the same manner as in Example 1, the ratio between transmittance and reflectance, plant growth evaluation, and peel test were performed. The results are shown in Table 1.

Example 9
Example 1 is the same as Example 1 except that the apex angle is 45 ° to 130 °, the average base angle is 45 ° to 25 °, and the pitch interval is 12 μm to 25.7 μm. And the wavelength conversion member in Example 9 was manufactured.
In the same manner as in Example 1, the ratio between transmittance and reflectance, plant growth evaluation, and peel test were performed. The results are shown in Table 1.

(Example 10)
Example 1 is the same as Example 1 except that the average angle of the apex angle is 90 ° to 10 °, the average angle of the base angle is both 45 ° to 85 °, and the pitch interval is 12 μm to 1 μm. Thus, the wavelength conversion member in Example 10 was manufactured.
In the same manner as in Example 1, the ratio between transmittance and reflectance, plant growth evaluation, and peel test were performed. The results are shown in Table 1.

(Example 11)
In Example 1, the wavelength conversion member in Example 11 was manufactured in the same manner as in Example 1 except that the radius of curvature of the apex angle was changed from 10 μm to 40 μm.
In the same manner as in Example 1, the ratio between transmittance and reflectance, plant growth evaluation, and peel test were performed. The results are shown in Table 1.

(Example 12)
In Example 1, the wavelength conversion member in Example 12 was manufactured in the same manner as in Example 1 except that the radius of curvature of the base angle was changed from 5 μm to 40 μm.
In the same manner as in Example 1, the ratio between transmittance and reflectance, plant growth evaluation, and peel test were performed. The results are shown in Table 1.

(Example 13)
In Example 1, the wavelength conversion member in Example 13 was produced in the same manner as in Example 1 except that the cross-sectional shape of the convex portion was changed from a triangle to a hemisphere.
In the same manner as in Example 1, the ratio between transmittance and reflectance, plant growth evaluation, and peel test were performed. The results are shown in Table 1.

(Example 14)
In Example 1, the wavelength conversion member in Example 14 was produced like Example 1 except having provided the convex part also in the light-incidence surface.
In the same manner as in Example 1, the ratio between transmittance and reflectance, plant growth evaluation, and peel test were performed. The results are shown in Table 1.

(Example 15)
In Example 1, wavelength conversion in Example 15 was performed in the same manner as in Example 1 except that the average angle of the apex angle was changed from 90 ° to 126 ° and the average angle of the base angle was changed from 45 ° to 27 °. A member was prepared.
In the same manner as in Example 1, the ratio between transmittance and reflectance, plant growth evaluation, and peel test were performed. The results are shown in Table 1.

(Comparative Example 1)
In Example 1, the wavelength conversion member in Comparative Example 1 was manufactured in the same manner as in Example 1 except that the average height of the convex portions was changed from 3 μm to 10 μm and the pitch interval was changed from 12 μm to 40 μm.
In the same manner as in Example 1, the ratio between transmittance and reflectance, plant growth evaluation, and peel test were performed. The results are shown in Table 1.

(Comparative Example 2)
In Example 1, the wavelength conversion member in Comparative Example 2 was manufactured in the same manner as in Example 1 except that the convex portion was not provided.
In the same manner as in Example 1, the ratio between transmittance and reflectance, plant growth evaluation, and peel test were performed. The results are shown in Table 1.

(Comparative Example 3)
In Example 1, the wavelength conversion member in the comparative example 3 was manufactured like Example 1 except having replaced the fluorescent acrylic board containing fluorescent substance with the acrylic board which does not contain fluorescent substance.
When the ratio of transmittance and reflectance was measured in the same manner as in Example 1, it could not be measured because it did not contain fluorescent radiation.
In the same manner as in Example 1, plant growth evaluation and a peel test were performed. The results are shown in Table 1.

(Comparative Example 4)
In Example 1, the wavelength conversion member in Comparative Example 4 was produced in the same manner as in Example 1 except that the average height of the protrusions was changed from 3 μm to 6 μm.
In the same manner as in Example 1, the ratio between transmittance and reflectance, plant growth evaluation, and peel test were performed. The results are shown in Table 1.

  It can be seen from Table 1 that the wavelength conversion members in Examples 1 to 15 can greatly promote plant growth compared to the wavelength conversion members in Comparative Examples 1 to 4. Moreover, the wavelength conversion member in Examples 1-15 has also shown the favorable result also in the peeling test, and a convex part does not peel at the same period by long-term repeated use.

4, in Example 1, light having a wavelength peak of about 660 nm is emitted on the light emitting surface, and light (600 nm to 750 nm) effective for photosynthesis is emitted, whereas Comparative Example 3 is emitted. Then, it can be seen that light having a wavelength peak of about 450 nm and light having a wavelength peak of about 550 nm are emitted, and light that is effective for photosynthesis is hardly emitted.
As can be seen from the photograph showing the growth situation of Example 1 in FIG. 5A and the photograph showing the growth situation of Comparative Example 3 in FIG. 5B, Example 1 has a leaf of Komatsuna in comparison with Comparative Example 3. This is also clear from the fact that there are many and the growth is fast.
According to the wavelength conversion member of the present invention and the plant growth method using the same, since the convex portion does not peel or collapse at the same time due to repeated use over a long period of time, incident light is converted into a wavelength effective for photosynthesis. However, since the light extraction efficiency is not drastically reduced, plant growth is not suppressed.

  In the wavelength conversion member of the present invention, since the convex portion does not peel or collapse at the same time due to repeated use over a long period of time, light is converted into a wavelength capable of photosynthesis over a long period of time, and the light extraction efficiency is drastically reduced. Therefore, it can be used in various situations. For example, it can be widely used in plant growing methods, solar cells, photoelectric conversion elements, and the like.

DESCRIPTION OF SYMBOLS 1 Wavelength conversion member 11 Light incident surface 12 Light output surface 13 Convex part 14 Reflecting part 15 Light guide part

Claims (9)

A light incident surface for receiving incident light from a light source;
A light exit surface for emitting the wavelength-converted light;
A plurality of convex portions formed on the basis of at least one of the light incident surface and the light emitting surface, and
A wavelength conversion member containing a phosphor that converts incident light into a wavelength that can be used for plant growth,
The convex portion is formed by a nanoimprint method,
An average height of the convex portions is less than 5 μm.   The wavelength conversion member according to claim 1, wherein an area ratio of the convex portions is less than 30% with respect to an area of a surface on which the convex portions are formed.   The wavelength conversion member according to claim 1, wherein the shape of the convex portion is a cone shape.   4. The wavelength conversion according to claim 3, wherein the average angle of the apex angles of the cross-sectional shape cut so as to be perpendicular to the surface on which the convex portions are formed from the height direction of the convex portions is 60 ° to 120 °. Element.   The average angle of the base angle of the cross-sectional shape cut so as to be perpendicular to the surface on which the convex portion is formed from the height direction of the convex portion is 30 ° to 60 °. The wavelength conversion member as described in 2.   The wavelength conversion member according to claim 4, wherein the apex angle has a radius of curvature of 100 μm or less.   The wavelength conversion member according to claim 5, wherein the radius of curvature of the base angle is 100 μm or less.   The wavelength conversion member according to claim 1, wherein the convex portion is provided on the light emitting surface. A plant growth method for growing a plant using the wavelength conversion member according to claim 1, wherein the wavelength of light incident from a light incident surface of the wavelength conversion member is used for plant growth. A method for growing a plant, wherein the light emitting surface is arranged so as to be wavelength-converted into light having a possible wavelength and to emit light from the light emitting surface of the wavelength converting member to a plant growing place.