JP7066991B2 - LED lighting device for growing plants - Google Patents

Description

The present invention relates to an LED lighting device for growing plants using an LED (light emitting diode) as a light source and used for growing plants, vegetables and seedlings, and a plant cultivation factory using the same.

As lighting equipment used in plant cultivation factories, the demand for lighting equipment using LEDs as a light source, which consumes less power and emits less radiant heat due to light emission, has rapidly expanded in recent years in place of conventional fluorescent lamps and high-pressure sodium lamps. I'm doing it.

As an example of a plant cultivation factory using a lighting device using an LED as a light source, a plant cultivation device in which a plurality of tubular plant growing lights using an LED as a light source are arranged above a plant cultivation shelf has already been widely put into practical use. (See Patent Document 1).

However, when a plurality of tubular LED plant growing lamps disclosed in Patent Document 1 are arranged at appropriate intervals, the intensity of the light hitting the plant varies between the area directly under the linear light source and the other parts. There was room for improvement in terms of what is likely to occur.

On the other hand, an LED lighting device for growing plants in which a plurality of LED elements are arranged on a flexible type circuit board to form a planar light source has also been proposed (see Patent Document 2). According to the LED lighting device having such a configuration, the above-mentioned problem of variation in light intensity can be improved.

Here, when an LED lighting device having an LED element constituting a planar light source arranged on the surface as disclosed in Patent Document 2 is used as a lighting device for growing plants, the plant is used. It is assumed that the water sprayed for growing will frequently be applied to these devices. Therefore, in order to avoid various failures caused by water, such as splashing water on electronic parts such as LED elements and flexible wiring boards, and promoting deterioration of LEDs due to high humidity in the plant cultivation environment, for plant growth. It is essential that the outermost surface of the LED lighting device is waterproofed. This waterproof treatment usually forms a waterproof layer 15A (see FIG. 5) having a thickness equal to or greater than the thickness of the LED element 2 on the outermost surface of the LED lighting device, as shown in FIG. 2 and the like of Patent Document 2. By doing, it was done.

In the LED lighting device disclosed in Patent Document 2, the thickness of the waterproof layer does not impair the flexibility, thinness, and lightness of the entire device that the flexible substrate type lighting device can originally exhibit. If the haze value is increased due to the thickness of the waterproof layer, the light emitted from the LED is diffused and the amount of light to the plant is reduced, and there is room for further improvement in order to avoid these points. ..

Utility Model Registration No. 3189886 Japanese Unexamined Patent Publication No. 2013-251230

The present invention has been made in view of the above circumstances, and is a flexible substrate type LED lighting device for growing plants, which is required for the purpose of flexibility, thinness, lightness, and plant growing. It is an object of the present invention to provide an LED lighting device in which sufficient waterproofness is ensured without impairing the optical characteristics to be obtained.

As a result of diligent research, the present inventors have made a waterproof layer, which has been conventionally formed as an essential component on the outermost surface of a flexible substrate type LED lighting device for growing plants, to follow the unevenness of the LED element. We have found that the above problems can be solved by forming a transparent thin film that is closely formed, and have completed the present invention. Specifically, the present invention provides the following.

(1) An LED lighting device for growing plants, which has a flexible substrate film, a metal wiring portion formed on the surface of the substrate film, and a matrix shape in such a manner that it can be electrically connected to the metal wiring portion. A light-reflecting insulation made of a resin composition containing a white pigment, which is formed on the substrate film and the metal wiring portion so as to cover a plurality of LED elements arranged in the above and an area other than an area for mounting the LED element. A protective layer, a light-reflecting insulating protective layer, and a transparent protective thin film formed over the LED element are provided, and the transparent protective thin film is a thin film having a thickness of 10 μm or more and 40 μm or less. An LED lighting device in which a portion covering the LED element has a shape that follows the shapes of the side wall surface and the upper light emitting surface of the LED element and protrudes from the light emitting surface of the LED lighting device.

In the invention of (1), the waterproof layer, which is an essential component on the outermost surface of the LED lighting device for growing plants, is a transparent thin film formed by following the unevenness of the surface of the flexible wiring substrate. According to this, it is possible to ensure sufficient waterproofness required for an LED lighting device for growing plants without impairing the flexibility, thinness, and lightness inherent in the flexible substrate type lighting device. .. It is also possible to prevent the wavelength range of the light emitted from the LED light source from shifting to an undesired wavelength range.

Here, the "LED element mounting area" in the present specification refers to a portion of the flexible wiring board constituting the LED lighting device for growing plants, which is a joint portion of the LED element to the metal wiring portion, and the joint portion thereof. It refers to a region consisting of a peripheral portion and a portion occupied by a joint structure for mounting an LED element such as a solder portion.

(2) The LED lighting apparatus according to (1), wherein the light-reflecting insulating protective layer and the transparent protective thin film are both thin films made of a resin composition using a urethane-based resin or an acrylic urethane-based resin as a base resin. ..

In the invention of (2), it was decided to unify the base resin of the resin composition forming the light-reflecting insulating protective layer and the resin composition forming the transparent protective thin film into the same type of resin. According to this, in the LED lighting device of (1), the adhesion of the transparent protective thin film formed by following the unevenness of the surface of the flexible wiring substrate to the light-reflecting insulating protective layer is further strengthened, and (1) The quality stability and durability of the described LED lighting device can be further improved.

(3) A plant cultivation factory in which a lighting system in which the LED lighting devices according to (1) or (2) are arranged side by side in a matrix is arranged on a ceiling surface.

According to the invention of (3), a light source capable of uniformly and stably irradiating an arbitrary necessary range on the floor surface side where the plant is planted with light having a wavelength preferable for growing the plant. Compared with the case where a large number of tubular light sources are installed as in the conventional case, it can be installed in the required range on the ceiling surface side with much less effort. As a result, it is possible to improve the productivity of plants while reducing the installation cost of the light source, which greatly contributes to the improvement of the overall economic efficiency of the plant cultivation factory.

(4) The method for manufacturing an LED lighting device according to (1) or (2), wherein the transparent protective thin film is sprayed on the surface of the light-reflecting insulating protective layer and the LED element with a transparent resin composition. A method for manufacturing an LED lighting device, which is formed by spraying by processing.

According to the invention of (4), the formation of the transparent protective thin film in the manufacture of the LED lighting device according to (1) or (2) is based on the method of spraying the transparent resin composition by spraying. .. According to this manufacturing method, the transparent protective thin film, which is a characteristic component of the LED lighting device according to (1) or (2), can be formed with high accuracy and efficiency.

According to the present invention, it is a flexible substrate type LED lighting device for growing plants, and sufficient waterproofness is ensured without impairing flexibility, thinness, lightness, and required optical characteristics. LED lighting equipment can be provided.

It is a top view schematically showing an example of the LED lighting apparatus of this invention. FIG. 1 is a drawing for explaining the form of a mounting portion of an LED element in the LED lighting device of the present invention, in a state where the light-reflecting insulating protective layer and the transparent protective thin film are removed in the LED lighting device of FIG. It is a cross-sectional enlarged view schematically showing the cross section of the part AA of FIG. 1, and is the drawing which provides the explanation of the layer structure of the LED lighting apparatus of this invention. FIG. 3 is a partially enlarged view of FIG. 3 and is a drawing used to explain the thickness of the transparent protective thin film. It is a drawing which provides the description of the aspect of the transparent protective film in the conventional LED lighting apparatus. It is a figure which shows typically the structure of the plant cultivation factory which can be constructed by using the LED lighting apparatus of this invention.

Hereinafter, first, the overall configuration of the LED lighting device of the present invention, the details of each member constituting the LED lighting device, and the manufacturing method thereof will be described, and later, a plant that can be implemented using this LED lighting device. The details of the cultivation factory will be described. The present invention is not limited to the following embodiments, and can be carried out with appropriate modifications within the scope of the object of the present invention.

<LED lighting device for growing plants>
Hereinafter, the LED lighting device for growing plants of the present invention (hereinafter, also simply referred to as “LED lighting device”) will be described with reference to FIGS. 1 to 4 as appropriate. As shown in FIGS. 1 to 4, the LED lighting device 10 is a lighting device in which a plurality of LED elements 2 are arranged in a matrix on a flexible wiring substrate 1. The flexible wiring board 1 refers to a wiring board in which a metal wiring portion 13 is formed on the surface of a flexible substrate film 11. In the flexible wiring board 1, the metal wiring portion 13 is laminated on the surface of the substrate film 11 via the adhesive layer 12.

The LED element 2 is mounted on a metal wiring portion 13 formed on the surface of the substrate film 11 in a matrix-like arrangement so as to be conductive. In the LED lighting device 10, since the wiring board on which the LED element 2 is mounted is the flexible wiring board 1, it is possible to arrange a plurality of LED elements 2 at a desired high density. Specifically, the arrangement density of the LED elements 2 in the LED lighting device 10 is preferably 0.02 pieces / cm ² or more and 2.0 pieces / cm ² or less, and 0.05 pieces / cm ² or more 1. It is more preferable that the number is 5 pieces / cm ² or less. By setting the arrangement density of the LED elements 2 to 0.02 elements / cm ² or more, the uniformity of the light emission intensity can be sufficiently maintained in a sufficiently preferable range as a surface light source type lighting device for growing plants.

As shown in FIG. 3, in the LED lighting device 10, a light-reflecting insulating protective layer 14 is formed on the substrate film 11 and the metal wiring portion 13 so as to cover the region excluding the LED element mounting region. The light-reflecting insulating protective layer 14 has an insulating function that contributes to the improvement of migration resistance of the flexible wiring board 1 constituting the LED lighting device 10 and a light reflection function that contributes to the improvement of the emission brightness of the LED lighting device 10. It is a layer that combines. This layer is formed of an insulating resin composition containing a white pigment.

Then, as shown in FIG. 3, in the LED lighting device 10, the transparent protective thin film 15 is formed so as to cover the light-reflecting insulating protective layer 14 and the LED element 2. The transparent protective thin film 15 is a resinous thin film formed on the outermost surface thereof mainly for ensuring the waterproofness of a lighting device for growing plants.

Further, in the LED lighting device 10, the LED element 2 is mounted in a matrix-like arrangement on the metal wiring portion 13 via the solder portion 16 so as to be conductive.

The size and planar shape of the LED lighting device 10 are not particularly limited. Since the LED lighting device 10 has a high degree of freedom in processing the size and shape, it is possible to flexibly meet various demands in this regard. Further, taking advantage of its flexibility, it can be mounted not only on a flat mounting surface but also on a mounting surface having various shapes.

[Substrate film]
The substrate film 11 is a flexible resin film, and a known thermoplastic resin can be appropriately used as the material thereof. In addition, in the present specification, "having flexibility" means that "the radius of curvature can be bent to at least 1 m or less, preferably 50 cm, more preferably 30 cm, still more preferably 10 cm, and particularly preferably 5 cm. ".

The thermoplastic resin used as the material of the substrate film 11 is required to have high heat resistance and insulating properties. As such a resin, a polyimide resin (PI) having excellent heat resistance, dimensional stability during heating, mechanical strength, and durability, or polyethylene naphthalate (PEN) can be used. Among them, polyethylene naphthalate (PEN) having improved heat resistance and dimensional stability by subjecting it to a heat resistance improving treatment such as an annealing treatment can also be preferably used. Further, polyethylene terephthalate (PET) whose flame retardancy is improved by adding a flame retardant inorganic filler or the like can also be selected as the material resin of the substrate film.

As the thermoplastic resin forming the substrate film 11, one having a heat shrinkage start temperature of 100 ° C. or higher, or one having improved heat resistance so that the same temperature becomes 100 ° C. or higher by annealing or the like may be used. preferable. Normally, the heat generated from the LED element may cause the peripheral portion of the element to reach a temperature of about 90 ° C. From this point of view, it is preferable that the thermoplastic resin forming the substrate film 11 has heat resistance equal to or higher than the above temperature.

The "heat shrinkage start temperature" in the present specification means that a sample film made of a thermoplastic resin to be measured is set in a TMA device, a load of 1 g is applied, and the temperature rises to 120 ° C. at a temperature rise rate of 2 ° C./min. After warming, the amount of shrinkage (% display) at that time is measured, and from the graph that outputs this data and records the temperature and amount of shrinkage, the temperature away from the 0% baseline due to shrinkage is read, and that temperature is heat-shrinked. It is the starting temperature. Further, the "heat-curing temperature" in the present specification is calculated by measuring and calculating the temperature at the rising position of the heat-curing reaction when the heat-curing resin to be measured is heated, and the temperature is defined as the heat-curing temperature. ..

Further, the substrate film 11 is required to be a resin having a high insulating property that can impart the insulating property required for the flexible wiring board 1 constituting the LED lighting device 10. In general, the substrate film 11 preferably has a volume resistivity of 10 ¹⁴ Ω · cm or more, and more preferably 10 ¹⁸ Ω · cm or more.

The thickness of the substrate film 11 is not particularly limited, but is approximately 10 μm or more and 500 μm from the viewpoint of not causing a bottleneck as a heat dissipation path, having heat resistance and insulating properties, and balancing manufacturing costs. Hereinafter, it is preferably 50 μm or more and 250 μm or less. Further, it is preferable that the thickness is within the above range from the viewpoint of maintaining good productivity in the case of manufacturing by the roll-to-roll method.

[Adhesive layer]
The formation of the metal wiring portion 13 on the surface of the substrate film 11 is preferably performed by a dry laminating method via an adhesive layer 12. As the adhesive forming the adhesive layer 12, a known resin-based adhesive can be appropriately used. Among these resin adhesives, urethane-based, polycarbonate-based, or epoxy-based adhesives can be particularly preferably used. The adhesive layer 12 usually remains slightly on the substrate film 11 in a region where the metal wiring portion does not exist after the etching treatment of the metal wiring portion 13.

[Metal wiring part]
As shown in FIGS. 2 and 3, the metal wiring portion 13 is a wiring pattern formed by a conductive substrate such as a metal foil on one surface of the substrate film 11.

The thermal conductivity λ of the metal constituting the metal wiring portion 13 is preferably 200 W / (m · K) or more and 500 W / (m · K) or less, and 300 W / (m · K) or more and 500 W / (m · K) or more. ) The following is more preferable. The electrical resistivity R of the metal constituting the metal wiring portion 13 is preferably 3.00 × 10 ^-8 Ωm or less, and more preferably 2.50 × 10 ^-8 Ωm or less. Here, for the measurement of the thermal conductivity λ, for example, a thermal conductivity meter QTM-500 manufactured by Kyoto Denshi Kogyo Co., Ltd. can be used, and for the measurement of the electric resistance R, for example, a 6517B type electrometer manufactured by Caseley Co., Ltd. can be used. Can be used. According to this, for example, in the case of copper, the thermal conductivity λ is 403 W / (m · K), and the electrical resistivity R is 1.55 × ^10-8 Ωm.

For example, when the metal wiring portion 13 is made of copper foil, both heat dissipation and electrical conductivity can be achieved at a high level. More specifically, since the heat dissipation from the LED element 2 is stable and the increase in electrical resistance can be prevented, the variation in light emission between the LED elements is reduced and stable light emission becomes possible. In addition, the life of the LED element 2 is also extended. Further, since deterioration of peripheral members such as the substrate film 11 due to heat can be prevented, the product life of the LED lighting device 10 can be extended.

Examples of the metal forming the metal wiring portion 13 include metals such as aluminum, gold, and silver in addition to the above-mentioned copper.

The thickness of the metal wiring portion 13 may be appropriately set according to the magnitude of the withstand current required for the flexible wiring board 1. However, in order to suppress warpage due to heat shrinkage of the substrate film 11 during soldering processing by a reflow method or the like, the thickness of the metal wiring portion 13 is preferably 10 μm or more. On the other hand, the thickness is preferably 50 μm or less, whereby sufficient flexibility of the flexible wiring board 1 can be maintained, and deterioration of handleability due to an increase in weight can be prevented.

[Solder part]
Regarding the joining between the metal wiring portion 13 and the LED element 2, the joining is performed via the soldering portion 16. This soldering can be performed by either a reflow method or a laser method.

[LED element]
The LED element 2 is a light emitting element that utilizes light emission at a PN junction where a P-type semiconductor and an N-type semiconductor are joined. A structure in which P-type electrodes and N-type electrodes are provided on the upper and lower surfaces of the device and a structure in which both P-type and N-type electrodes are provided on one surface of the device have been proposed. The LED element 2 having any structure can be used in the LED lighting device 10 of the present invention, but among the above, the LED element having a structure in which both P-type and N-type electrodes are provided on one side of the element is particularly preferably used. Can be done.

As described above, the LED lighting device 10 directly mounts the LED element 2 on the metal wiring portion 13 capable of exhibiting high heat dissipation. As a result, even when the LED element 2 is arranged at a high density, the excess heat generated at the time of lighting is quickly diffused through the metal wiring portion 13, and the heat is dissipated to the outside of the LED lighting device 10 via the substrate film 11. It can be sufficiently promoted.

[Light reflective insulation protective layer]
As described above, the light-reflecting insulating protective layer 14 is a layer formed in a region excluding the LED element mounting region. The light-reflecting insulating protective layer 14 is a so-called resist layer that improves the migration resistance of the flexible wiring substrate 1 by having sufficient insulating properties, and also improves the emission brightness of the LED lighting device 10. It is also a light-reflecting layer having a light-reflecting property that contributes.

The light-reflecting insulating protective layer 14 can be formed of various resin compositions using a urethane resin or the like as a base resin and further containing a white pigment made of an inorganic filler such as titanium oxide. As the base resin of the resin composition used for forming the light-reflecting insulating protective layer 14, acrylic urethane-based resin, polyester-based resin, phenol-based resin and the like can be appropriately used in addition to urethane-based resin.

However, as the base resin of the resin composition forming the light-reflecting insulating protective layer 14, it is more preferable to use the same or similar resin as the resin composition forming the transparent protective thin film 15 as the base resin. As for the transparent protective thin film 15, it is preferable to use an acrylic urethane-based resin as the main material resin, as will be described later. From this, when the base resin of the resin composition forming the transparent protective thin film 15 is an acrylic urethane-based resin, the base resin of the resin composition for forming the light-reflecting insulating protective layer 14 is a urethane-based resin or It is more preferable to use an acrylic urethane resin.

Examples of the inorganic filler contained as a white pigment in the resin composition forming the light-reflecting insulating protective layer 14 include titanium oxide, alumina, barium sulfate, magnesia, aluminum titrated, boron titrated, barium titanate, and kaolin. At least one selected from talc, calcium carbonate, zinc oxide, silica, mica powder, powdered glass, powdered nickel and powdered aluminum can be used.

The thickness of the light-reflecting insulating protective layer 14 is 10 μm or more and 50 μm or less, more preferably 15 μm or more and 40 μm or less. If the thickness of the light-reflecting insulating protective layer 14 is less than 10 μm, the light-reflective insulating protective layer becomes thin, especially at the edge portion of the metal wiring portion 13, and the metal wiring cannot be covered and is exposed. The risk of not being able to maintain insulation increases. On the other hand, the thickness of the light-reflecting insulating protective layer 14 is preferably 50 μm or less from the viewpoint of maintaining the light-reflecting insulating protective layer by bending the substrate during handling and transportation.

Here, the term "thickness of the light-reflecting insulating protective layer" as used herein means the outermost surface of the same layer or the interface with another film, layer, or substrate facing the same layer, and the other side from the surface. It shall mean the distance to the outermost surface on the surface side or the other interface facing the same surface. If there is a variation in the distance within each of the planes of the light-reflecting insulating protective layer to be measured, the average value of the distance is referred to. However, in calculating this average value, the thickness of a part of the protective film fluctuates locally due to the influence of the uneven shape of the facing layer such as the edge part of the metal wiring part directly under the insulating protective film to be measured. This part is excluded from the element for calculating the above-mentioned average value as the noise of the thickness. The distance can be measured, for example, by observing the vertical cross section of the LED lighting device with a metallurgical microscope, an electron microscope, or the like.

Further, the light-reflecting insulating protective layer 14 preferably has a light reflectance of 80% or more, and more preferably 90% or more, at a wavelength of 420 nm or more and 780 nm or less. The LED lighting device 10 contains, for example, 10 parts by mass or more of titanium oxide with respect to 100 parts by mass of a urethane-based or acrylic urethane-based base resin, so that the thickness of the light-reflecting insulating protective layer 14 is 35 μm. In some cases, the light reflectance of the same layer can be set to 80% or more. Since it is difficult to accurately measure the absolute reflectance, the relative reflectance with the comparative standard sample is usually used for the above-mentioned light reflectance. In the present invention, barium sulfate is used as a comparative standard sample. For the light reflectance in the present invention, an integrating sphere attachment device (for example, ISR2200 manufactured by Shimadzu Corporation) is attached to a spectrophotometer (for example, UV2450 manufactured by Shimadzu Corporation), barium sulfate is used as a standard plate, and a standard plate is used. The relative reflectance set to 100% is used as the measured value.

[Transparent protective thin film]
As described above, the transparent protective thin film 15 is a thin film having waterproofness and transparency formed on the outermost surface of the LED lighting device 10 following the shapes of the side wall surface and the upper light emitting surface of the LED element 2. .. Due to the waterproof property of the transparent protective thin film 15, it is possible to prevent water from entering the inside of the LED lighting device 10 when the LED lighting device 10 is used as a light source for plant cultivation. Further, as a specific index of the above transparency, the transparency of the transparent protective thin film 15 may be 1.0% or less as long as the haze value measured in accordance with JIS-K7136 is 2.0% or less. Is more preferable.

The transparent protective thin film 15 can be formed of various resin compositions using an acrylic urethane resin or the like as a base resin. As the base resin of the resin composition used for forming the transparent protective thin film 15, urethane-based resin, polyester-based resin, phenol-based tree and the like can be appropriately used in addition to acrylic urethane-based resin.

However, as the base resin of the resin composition forming the transparent protective thin film 15, it is more preferable to use the same or similar resin as the resin composition forming the light-reflecting insulating protective layer 14 as the base resin. As a preferable specific combination, a combination in which the base resin of the resin composition forming the light-reflecting insulating protective layer 14 is a urethane-based resin and the resin forming the transparent protective thin film 15 is an acrylic urethane-based resin can be mentioned. can.

As shown in FIG. 3, the transparent protective thin film 15 has the shape of the side wall surface and the upper light emitting surface of the LED element 2 in which the portion covering the LED element 2 which is a part thereof protrudes from the surface of the light reflective insulating protective layer 14. The LED lighting device 10 is formed so as to have a shape protruding outward from the light emitting surface of the LED lighting device 10. As shown in FIG. 3, the protruding portion of the transparent protective thin film 15 that covers the LED element 2 maintains its protruding shape in a manner of being in close contact with each surface of the LED element 2. The height of the LED element 2 protruding from the surface of the light-reflecting insulating protective layer 14 varies depending on the type and size of the LED element used and the details of the mounting mode, but is 0.5 mm to 2 mm. Generally, the height is about this level, and the present invention also assumes the existence of unevenness of this level.

The upper limit of the thickness of the transparent protective thin film 15 is 40 μm or less, preferably 30 μm or less, and more preferably 25 μm or less. By setting the thickness of the transparent protective thin film 15 to 40 μm or less at the maximum and making it a thin film having a shape that follows the unevenness of the surface of the flexible wiring substrate 1 as shown in FIG. 3, the LED lighting device 10 is good. It is possible to maintain flexible flexibility, thinness, light weight, and good optical properties required for plant growing applications.

The lower limit of the thickness of the transparent protective thin film 15 is 10 μm or more, preferably 15 μm or more. By making the thickness of the transparent protective thin film 15 at least 10 μm or more and making it a thin film having a shape that follows the unevenness of the surface of the flexible wiring board 1 as shown in FIG. 3, the LED lighting device 10 is planted. It is possible to provide sufficient waterproofness required for growing applications.

Here, since the transparent protective thin film 15 of the LED lighting device 10 is a resin film having an extremely small thickness unlike the conventional waterproof layer (15A in FIG. 5), the resin composition as a material is applied by spray treatment. It is preferable to select the forming method (spray coating method) (details of the manufacturing method will be described later). In the case of this manufacturing method, as shown in FIG. 4, the thickness of each portion of the transparent protective thin film 15 is increased. Tends to vary. Specifically, for example, when the coating amount of the material resin composition is set based on the thickness (D2) on the upper surface of the metal wiring portion 13 or the LED element 2, the resin composition used as the material. Due to the fluidity of the LED element, the thickness (D1) at the edge portion of the LED element tends to be the smallest, and the thickness (D3) around the lower portion of the side wall of the LED element 2 tends to be the largest. At the time of manufacturing the LED lighting device 10, the amount of the resin composition forming the transparent protective thin film 15 by incorporating the occurrence of such a thickness variation for each portion of the transparent protective thin film 15 in advance is applied at the time of coating. In terms of the thickness of the film, the viscosity of the composition to be coated should be taken into consideration as necessary, and the coating amount should be within the range of about 15 μm to 30 μm in the thickness of the film at the time of coating. By setting, the thickness of the transparent protective thin film 15 can be set to 10 μm or more even in the thinnest portion and 40 μm or less even in the thickest portion.

Here, the "thickness of the transparent protective thin film" as used herein means from the interface with the outermost surface of the film or another film, layer, or substrate facing the same film, and the surface side opposite to that surface. It shall refer to the distance to the outermost surface or the other facing interface. As described above, the distances generally vary within each of the above planes of the transparent protective thin film to be measured. Therefore, in the LED lighting device of the present invention, the thickness of the transparent protective thin film around the edge portion of the above-mentioned LED element, which is highly likely to have the smallest thickness due to its structure, is measured, and the thickness is the largest within the range. The thickness of the small portion (D1) is regarded as the minimum value of the thickness of the transparent protective film. Similarly, the thickness around the lower part of the side wall of the LED element 2 is measured, and the thickness (D3) of the thickest portion within the range is measured. It shall be regarded as the maximum value of the thickness of the transparent protective film. The above distance, that is, the thickness of each layer can be measured, for example, by observing the vertical cross section of the LED lighting device with a metallurgical microscope, an electron microscope, or the like.

As described above, in the LED lighting device 10, the function for ensuring the waterproof performance of the surface is secured by the transparent protective thin film 15, that is, the ultra-thin resin thin film having a thickness of at most 40 μm or less that can be formed by the spray coating method. It was configured to be. On the other hand, in the conventional LED lighting device for growing plants, as shown in FIG. 5, a transparent resin having a thickness larger than the protrusion height of the LED element 2 which is normally expected to have a protrusion of at least 500 μm or more. The layer was a waterproof layer 15A and was arranged on the surface on the light emitting surface side. The thickness of the waterproof layer 15A is structurally inevitably at least about 500 μm or more. That is, in the LED lighting device 10 of the present invention, the thickness of the resin layer formed on the outermost surface on the light emitting surface side that guarantees the function as a waterproof layer is about 1/10 or less of that of the conventional product. The thickness of the layer formed on the surface on the light emitting surface side is increased by 10 times or more in this way because of the flexibility and lightness of the flexible wiring board 1 and the optical characteristics of the light emitted from the LED element 2. Both have a clear negative impact. The present invention has a technical feature in that such a negative influence is eliminated by making a fundamental improvement in the structure of the waterproof layer on the surface on the light emitting surface side.

[Manufacturing method of LED lighting device]
The LED lighting device 10 can be manufactured by a conventionally known flexible wiring board for LED elements and a known method for manufacturing various LED modules in which LED elements are mounted. However, for the formation of a transparent protective thin film having a shape peculiar to the present application, it is preferable to use a method of spraying a transparent resin composition onto the transparent protective thin film. Hereinafter, a preferable manufacturing method in which the transparent protective thin film is formed by this method will be described.

(Etching process)
A metal wiring portion 13 such as a copper foil used as a material for the metal wiring portion 13 is laminated on the surface of the substrate film 11 to obtain a laminated body as a material. As the laminating method, a method of adhering a metal foil to the surface of the substrate film 11 with an adhesive, a method of directly plating the surface of the substrate film 11 or a vapor phase film forming method (sputtering, ion plating, electron beam deposition, etc.) A method of vapor-depositing the metal wiring portion 13 by vacuum vapor deposition, chemical vapor deposition, etc.) can be mentioned. From the viewpoint of cost and productivity, a method of adhering the metal foil to the surface of the substrate film 11 with a urethane-based adhesive is advantageous.

Next, an etching mask patterned in the shape required for the metal wiring portion 13 is formed on the surface of the metal foil of the laminated body. The etching mask is provided so that the wiring pattern forming portion of the metal foil, which will be the metal wiring portion 13 in the future, is prevented from being corroded by the etching solution. The method for forming the etching mask is not particularly limited, and for example, the etching mask may be formed on the surface of the laminated film by exposing the photoresist or dry film through the photomask and then developing it, or an inkjet printer. An etching mask may be formed on the surface of the laminated film by a printing technique such as.

Next, the metal foil in the portion not covered by the etching mask is removed by the dipping solution. As a result, the portion of the metal foil other than the portion that becomes the metal wiring portion 13 is removed.

Finally, an alkaline stripper is used to remove the etching mask. As a result, the etching mask is removed from the surface of the metal wiring portion 13.

(Light reflective insulating protective layer forming process)
After forming the metal wiring portion 13, the light-reflecting insulating protective layer 14 is further laminated and formed. This formation is not particularly limited as long as it is a coating means capable of uniformly coating the material resin composition, and for example, screen printing, offset printing, dip coater, brush coating, and all other ordinary methods can be used. ..

(LED element mounting process)
The LED element 2 is mounted by joining the LED element 2 to the metal wiring portion 13 by soldering. The joining by soldering can be performed by a reflow method or a laser method. In the reflow method, the LED element 2 is mounted on the metal wiring portion 13 via solder, and then the flexible wiring substrate 1 is conveyed into the reflow furnace, and hot air having a predetermined temperature is blown to the metal wiring portion 13 in the reflow furnace. By attaching, the solder paste is melted and the LED element 2 is soldered to the metal wiring portion 13. The laser method is a method in which the solder is locally heated by a laser to solder the LED element 2 to the metal wiring portion 13. The solder bonding of the LED element 2 to the metal wiring portion 13 is preferably performed by laser irradiation from the back surface side of the substrate film 11. As a result, it is possible to more reliably suppress the ignition of the organic component of the solder due to heating and the damage to the base material due to the ignition. In this step, the solder portion 16 is formed at the position shown in FIG.

(Transparent protective thin film forming process)
After mounting the LED element 2, the transparent protective thin film 15 is further formed. The method for forming the transparent protective thin film 15 is a method of spraying a transparent resin composition by a spray treatment in order to form the resin film into a thin film within the above-mentioned thickness range (hereinafter referred to as "spray coating method"). ). The transparent protective thin film 15 is formed by the spray coating method, for example, by spraying a coating liquid for spray coating treatment containing an acrylic urethane resin onto a desired region on the flexible wiring substrate 1 with a spray coating machine. Can be done by forming. By forming the transparent protective thin film 15 by the spray coating method, the thickness of the transparent protective thin film 15 is kept within a predetermined ultra-thin thickness range, and the shape of the film is emitted by the LED lighting device 10. It is possible to easily follow the uneven shape on the surface side.

<Plant cultivation factory>
FIG. 6 is a diagram schematically showing the configuration of a plant cultivation plant 100 using the LED lighting device 10 of the present invention. In the plant cultivation factory 100, a lighting system is provided in which a medium area for cultivating a plant 3 is provided inside a building or the like, and LED lighting devices 10 are juxtaposed in a matrix on the ceiling surface above the medium area. Have been placed.

Since the LED lighting device 10 maintains flexibility and lightness, it is much easier to install the lighting system on the entire ceiling surface as compared with the case of using a conventional tubular lighting device or the like. Can be done. Further, since the LED lighting device 10 is a so-called flexible substrate type member, it has extremely high adaptability to a ceiling surface having various sizes and shapes, and is considered to be applied to plant cultivation factories having various designs.

Further, it is also possible to easily realize a multi-layered plant cultivation factory by vertically stacking a plurality of single-layered cultivation units provided with a medium region for cultivating the plant 3 and a ceiling surface. In this case as well, the ease of installation and the light weight of the LED lighting device 10 have an advantage. With such an embodiment, it is possible to realize an increase in yield per unit area.

<Creation of LED lighting device>
The LED lighting devices (test samples) of Examples and Comparative Examples were manufactured as follows.

(Example)
A copper foil (thickness 35 μm) for forming a metal wiring portion is laminated on one surface of a film substrate (polyethylene naphthalate, thickness 50 μm) having a size of 500 mm × 400 mm, and then a copper foil for metal wiring is provided. Etching treatment was performed to form a metal wiring portion having the same pattern in all the examples and comparative examples.
Then, on the substrate film and the metal wiring part, a urethane-based resin is used as a base resin, and an insulating ink made by adding titanium oxide at a ratio of 20% by mass to the base resin is used for screen printing to a thickness of 15 μm. A light-reflecting insulating protective layer was formed.
Next, in the metal wiring section, multiple LED elements ("NFSL757GT" (manufactured by Nichia Corporation)) are placed alternately in 10 rows and 11 rows at a horizontal 4 mm pitch and a vertical 3.5 mm pitch. It was mounted in 12 rows by soldering. This LED element is a top light emitting type light emitting element, and has an outer shape of a rectangular parallelepiped having a size of 3.0 mm (length) × 3.0 mm (width) × 0.65 mm (height).
Further, the insulating protective layer and the LED element were covered, and a transparent protective thin film having a shape following the shape of the LED element was formed by a spray coating method in the manner shown in FIG. As the resin composition for forming the transparent protective thin film, a coating liquid for spray coating treatment containing an acrylic urethane resin is used, and the pressure of the film at the coating stage is set to 25 μm by a spray coating machine. bottom.
The LED lighting device manufactured as described above was used as the LED lighting device of the embodiment.

(Comparative example)
Instead of the transparent protective thin film in the LED lighting device of the embodiment, a transparent waterproof layer having a thickness larger than the protruding height of the LED element is formed on the surface on the light emitting surface side as shown in FIG. The LED lighting device manufactured in the same manner as the example was used as the LED lighting device of the comparative example. In the LED lighting device of the comparative example, a resin composition using the same acrylic urethane-based transparent resin as the base resin as in the example is used by a dip method so that the thickness from the light emitting surface of the LED element to the surface of the waterproof layer is 500 μm. By molding, a waterproof layer was formed.

<Evaluation example 1: Optical characteristics>
For the LED display devices of Examples and Comparative Examples, the optical characteristics, specifically, the transparency of the transparent protective thin film of Examples and the waterproof layer of Comparative Examples were tested according to JIS K-7136 (haze). It was measured by the test to be measured). The measurement results were evaluated according to the following evaluation criteria. The evaluation results are as shown in Table 1.
(Evaluation criteria)
Haze value 2.0% or less: ○
Haze value exceeds 2.0%: ×

<Evaluation example 2: Waterproofness>
For the LED display devices of Examples and Comparative Examples, the waterproofness on the light emitting surface side was measured by a test according to JIS C0920 (a test for evaluating waterproof performance). The measurement results were evaluated according to the following evaluation criteria. The evaluation results are as shown in Table 1.
(Evaluation criteria)
Waterproofness satisfies IPX5: ○
Waterproofness has not achieved IPX5: ×

<Evaluation example 3: Insulation>
The insulation of the LED display devices of Examples and Comparative Examples was measured by a test according to JIS C-6481. The insulation resistance value under normal conditions was evaluated according to the following evaluation criteria. The evaluation results are as shown in Table 1.
(Evaluation criteria)
Insulation resistance value 1.0 x ¹⁰⁸ or more: ○
Insulation resistance value less than 1.0 x ¹⁰⁸ : x

<Evaluation example 5: Economic efficiency>
When the material amount cost per unit area for ensuring the waterproof function was calculated for the LED display devices of the examples and the comparative examples, the material amount cost of the comparative example was about 25 times the material amount cost of the example. Was confirmed. Based on this, the economic efficiency of the examples was evaluated as ○, and the economic efficiency of the comparative examples was evaluated as ×.

It is clear from the structure that the LED lighting device of the present invention is advantageous in flexibility and lightness as compared with the conventional product represented by the LED lighting device of the comparative example. In addition, as shown in Table 1, the LED lighting device of the present invention has a lower manufacturing cost than the conventional product, while ensuring sufficient waterproofness and insulation, which are essential requirements for agricultural applications. It can be seen that the optical characteristics are improved compared to the conventional product.

1 Flexible wiring board 11 Board film 12 Adhesive layer 13 Metal wiring part 14 Light reflective insulation protective layer 15 Transparent protective thin film 16 Handa part 2 LED element 10 LED lighting device 100 Plant cultivation factory

Claims (5)

An LED lighting device for growing plants
Flexible substrate film and
The metal wiring portion formed on the surface of the substrate film and
A plurality of LED elements arranged in a matrix so as to be conductive to the metal wiring portion, and
A light-reflecting insulating protective layer formed on the substrate film and the metal wiring portion, which covers a region other than the LED element mounting region, and is made of a resin composition containing a white pigment.
The light-reflecting insulating protective layer and the transparent protective thin film formed over the LED element are provided.
The transparent protective thin film has a shape in which a portion covering the LED element protrudes from the light emitting surface of the LED lighting device, following the shapes of the side wall surface and the upper light emitting surface of the LED element.
The thickness of the transparent protective thin film is 15 μm or more and 30 μm or less on the upper light emitting surface of the LED element, and 10 μm or more on the thinnest part, which is thinner than the thickness on the upper light emitting surface of the LED element. The thickest part is 40 μm or less, which is thicker than the thickness on the upper light emitting surface of the LED element.
LED lighting device. The LED element is a top light emitting type LED element.
The LED lighting device according to claim 1. The LED lighting device according to claim 1 or 2 , wherein the light-reflecting insulating protective layer and the transparent protective thin film are both thin films made of a resin composition based on a urethane-based resin or an acrylic urethane-based resin. A plant cultivation factory in which a lighting system in which the LED lighting devices according to any one of claims 1 to 3 are arranged side by side in a matrix is arranged on a ceiling surface. The method for manufacturing an LED lighting device according to any one of claims 1 to 3 .
A method for manufacturing an LED lighting device, wherein the transparent protective thin film is formed by spraying a transparent resin composition onto the surfaces of the light-reflecting insulating protective layer and the LED element by spray treatment.

Images