JPH11329034A - Reflecting film and light emitting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To easily change the directivity and range of the radiated light in conformity with the use condition, and to effectively improve the intensity of the radiated light by including a dielectric reflecting layer having a reflecting surface opposite to a light emitting surface of a light source and a light transmitting adhesive layer tightly fitted onto the reflecting surface. SOLUTION: A reflecting film 4 is provided with a reflecting layer 3 and a light transmitting adhesive layer 2. The reflecting film 4 can be adhered for fixation to a part of a peripheral surface (a light emitting surface) of a light source 1 through the adhesive layer 2, and a light emitting device 10 is thereby formed. Consequently, at a place provided with a light source 1, the reflecting film 4 is adhered to the peripheral surface of the light source 1 at the predetermined coating area, and intensity of the irradiation (radiation) light from a residual part of the periphery, which is not coated by the reflecting film 4, is improved, and the predetermined directivity can be remarkably easily obtained. Ratio of the coating area of the reflecting film 4 is preferably set at 25-75% in relation to the whole area of the peripheral surface (light emitting surface).

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a reflection film and a light-emitting device, and more particularly, to a reflection film particularly suitable for forming a light-emitting device including a light source such as a fluorescent tube, a cold cathode tube, and the like. The present invention relates to a light emitting device formed using such a reflective film.

[0002]

2. Description of the Related Art As is well known, a large number of light sources composed of a high-frequency current illuminant such as a fluorescent tube and a cold cathode tube are used indoors and outdoors for illumination, including a backlight of a liquid crystal display device. Such a light source is required to irradiate (emit) light with high intensity and appropriate intensity depending on the use conditions. In order to satisfy this demand,
A reflector provided behind the reflector, a reflector fluorescent tube or an aperture fluorescent tube coated with a reflective film inside the light source, and the like are used.

A typical example of a conventional reflector used in combination with a light source comprising the above-mentioned high-frequency current emitter is a reflector or the like, which is arranged at a predetermined distance (usually 1 mm or more) from the light source. This is because the reflecting surface of the reflecting device is
This is because it is usually made of a metal layer surface, and when it is arranged close to a fluorescent tube or the like, there is a possibility that high-frequency current leaks.

Further, a reflector fluorescent tube (for example, “(product number) FL30SR” manufactured by NEC Home Electronics Co., Ltd.)
W "), aperture fluorescent tube (for example," (product number) FL32SAD70 "manufactured by NEC Corporation)
Are also known. For example, the above-mentioned reflector fluorescent tube has a reflective film adhered so as to cover about ／ of the inner peripheral surface of the light-transmitting glass tube (covering angle = approximately 240 °). A phosphor is applied to the entire inner peripheral surface. In this fluorescent tube, the phosphor emits light due to vacuum discharge inside the glass tube, and light is intensively emitted from the peripheral surface of the glass tube without the reflective film. Further, the aperture tube is about 4/4 of the inner peripheral surface of the glass tube.
A reflective film is adhered so as to cover the portion of No. 5, and a fluorescent material is applied only to the inner peripheral surface of the reflective film. Light emitted from the aperture surface is not diffused by the phosphor, so that directivity is enhanced.

[0005] As described above, the reflection surface of the reflection device is usually formed from a metal film, plate, vapor deposition film or the like. This is because the metal surface has a relatively high reflectance, so-called specular reflection is possible, and it is easy to enhance the directivity of reflected light. It is also known to use a dielectric reflector to effectively increase the reflectance of the surface without using a metal. For example, Japanese Unexamined Patent Publication No. Hei 9-506837, Japanese Unexamined Patent Publication No. Hei 9-506984, Japanese Unexamined Patent Publication No. Hei 9-511844.
Japanese Patent Application Laid-Open Publication No. H10-163, etc. discloses a dielectric reflection film formed by alternately laminating first and second layers containing dielectrics having different refractive indexes.

Such a dielectric reflection film is formed by laminating a plurality of the above dielectric layers in close contact with each other,
This is a reflective film in which the relationship between the thickness of each layer and the refractive index is determined so as to have a specific wavelength selectivity (a property of transmitting light in a certain wavelength band and reflecting light outside the wavelength band). The expression of wavelength selectivity is that the product of the thickness and the refractive index of the dielectric layer sandwiched between the two layers is one-fourth of the wavelength of the light incident on the dielectric layer, Is higher or lower than the refractive index of either of the two layers sandwiching it, whereby the reflected light at the two interfaces between the two layers and the dielectric layer is strengthened in phase with each other. And a wavelength selective reflection principle (dielectric reflection principle). That is,
A dielectric reflection film including a dielectric layer designed to reflect substantially all wavelengths in the visible light band functions as a specular reflection film with respect to visible light, and can realize, for example, a reflectance of 80% or more. . The dielectric is usually composed of a first polymer and a second polymer having a different refractive index from the first polymer, and does not include a conductive metal.

[0007]

However, the above-mentioned conventional external reflection devices and light sources with a built-in reflection device have the following problems. In a light source with a built-in reflecting device, a reflecting layer is disposed inside the light source, so that the radiation directivity and the illumination range cannot be easily changed according to the use conditions. On the other hand, in the case of an external reflection device, although it is relatively easy to change the radiation directivity according to the use conditions, the reflection device is bulky, so that the space for the reflection device cannot be sufficiently taken. Difficult to use. Also,
Since the radiation directivity is uniquely determined by the design of the reflection device, it is difficult to arbitrarily change it after installation.

On the other hand, it is not possible to use the dielectric reflection film as described above as a material for forming a reflection surface of an external reflection device (a reflection plate or the like disposed at a predetermined distance from a light source, that is, disposed via an air layer). Although it is known, it does not suggest any means for easily changing the radiation directivity according to use conditions and effectively increasing the radiation light intensity of the light emitting device.

Therefore, an object of the present invention is to easily change the directivity of radiated light and the illumination range in accordance with the use conditions, even when the space for disposing the external reflection device is not sufficient. It is an object of the present invention to provide a reflective film capable of effectively increasing the emission light intensity of a light emitting device. Another object of the present invention is to provide a light emitting device using such a reflective film and capable of effectively increasing the intensity of emitted light.

[0010]

SUMMARY OF THE INVENTION According to the present invention, there is provided a light-emitting device, comprising: a light-emitting surface; A dielectric film having a reflective surface facing the light-emitting surface of the light source, and a light-transmissive adhesive layer in close contact with the reflective surface of the dielectric reflective layer. In a reflective film.

In another aspect of the present invention, a light-transmitting adhesive layer is provided so as to cover (a) a light source and (b) a part of a light-emitting surface of the light source on another surface thereof. With the reflective film of the present invention in close contact with the light emitting surface of the light source,
The light emitting device is characterized in that the intensity of radiated light from the remaining portion of the light emitting surface of the light source that is not covered with the reflective film is increased.

[0012]

BEST MODE FOR CARRYING OUT THE INVENTION Next, the present invention will be described in detail with reference to embodiments. First, from the working surface for the understanding of the present invention, it is as follows: the reflective film of the present invention has a dielectric reflective layer having a reflective surface facing a light emitting surface of a light source, and a dielectric reflective layer of the dielectric reflective layer. A light-transmitting adhesive layer in close contact with the reflection surface. Therefore, in a place where the light emitting device is formed, a desired illumination range (angle range)
It is very easy to arrange the reflection film so that the radiation directivity can be obtained. That is, the work of arranging the reflective film, the reflective film of the present invention, the light-emitting surface of the light source through the light-transmitting adhesive layer, with a predetermined coverage area,
It is only necessary to adhere (adhere) so as to cover a part of the light emitting surface. As a result, the intensity of light emitted from the remaining portion of the light emitting surface of the light source can be effectively increased, and the illumination range and the radiation directivity can be easily and freely controlled.

[0013] The reflecting surface close to the light emitting surface of the light source is
Since it is formed from a polymer (dielectric), even if the light source is a high-frequency current luminous body such as a fluorescent tube or a cold cathode tube, it is possible to reliably prevent a high-frequency current from leaking due to a short circuit or short circuit.
Further, the fact that the reflecting surface of the reflecting film is in close contact with the light emitting surface of the light source via the adhesive layer also has the following effects. Light that reaches the surface of the dielectric reflection layer from the light source is partially reflected on the surface, the rest enters the dielectric reflection layer, is reflected in the layer and is emitted again from the surface, and by a combination of these reflection effects, All light is reflected (dielectric reflection principle). At this time, the surface of the dielectric reflection layer is air (refractive index = 1).
If it is at the interface with light, light emitted from within the layer again through the surface is reflected at its air interface and returned back into the layer. The light returned into the dielectric reflection layer is attenuated in the layer, and as a result, the amount of light reflected by the dielectric reflection layer tends to decrease, and the light emission intensity of the light emitting device tends to decrease. However,
By forming an interface with the adhesive layer instead of the air interface,
The return of light into such a layer can be prevented as much as possible, and the emitted light intensity of the light emitting device can be effectively increased. This is because the refractive index of the adhesive (ie, polymer) is greater than air.

It is preferable that the reflection film of the present invention further includes a diffusion reflection layer adhered to a surface of the dielectric reflection layer opposite to the reflection surface. As a result, even if the light of the light source cannot be effectively reflected by the dielectric reflection layer alone and includes light in a wavelength band that is transmitted, the light is reflected to the illuminated area as reflected light without substantially changing the wavelength distribution of the light. Can radiate toward

Next, the reflection film and the light emitting device of the present invention and their components will be described. (Reflective Film) As shown in FIG. 1, a reflective film according to one embodiment of the present invention includes a reflective layer 3 and a light-transmitting adhesive layer 2. The reflective film 4 can be fixedly adhered to a part of the peripheral surface (light emitting surface) of the light source 1 via the adhesive layer 2, thereby forming the light emitting device 10. That is, on the spot where the light source 1 is installed, the reflective film 4 is adhered to the peripheral surface of the light source 1 with a predetermined covering area, and irradiation (radiation) from the remaining portion of the peripheral surface not covered with the reflective film is performed. It is extremely easy to increase the light intensity and achieve a predetermined directivity. The shape of the reflective film in the illustrated form is substantially rectangular. In this case, the reflection film is usually arranged such that the long side of the rectangle is substantially parallel to the length direction of the light source 1. Further, the shape of the reflection film is not limited to this, and can be freely selected depending on the application and purpose. For example, a parallelogram, a trapezoid, a circle, an ellipse, a polygon having a geometric regularity, or the like is used.

The ratio of the covering area of the reflective film is usually 1 to 95%, preferably 1 to the total area of the peripheral surface (light emitting surface).
It is in the range of 2 to 85%, particularly preferably 25 to 75%.
If the covering area is too small, the directivity may not be effectively increased, while if too large, the illumination range (angle range) may be narrowed, and in both cases, the practicality as a light emitting device is reduced. May be caused. When the cross section of the light source such as a fluorescent tube is circular, the covering angle (wrapping angle) of the reflective film is usually 5 to 355 °, preferably 45 to 315 °, and particularly preferably 90 to 270 °. Range. If the coating angle is too small, the directivity may not be effectively enhanced, while if it is too large, the illumination range (angle range) may be narrowed, and in either case, the practicality as a light emitting device is reduced. There is a risk of being squeezed. The “covering angle” is defined as a central angle of an arc covered with the reflective film in a transverse section (a section orthogonal to the length direction) of the light source.

The reflection layer is usually composed of a dielectric reflection layer.
In addition to the dielectric reflection layer, the above-mentioned diffusion reflection layer and other layers may be included. However, the reflection surface facing the light emitting surface of the light source is formed from the reflection surface of the dielectric reflection layer, and the adhesive layer needs to be in close contact with the reflection surface of the dielectric reflection layer. The reflectivity of the dielectric reflection layer is usually at least 70%, preferably at least 80%, particularly preferably at least 90%. In addition,
"Reflectance" in this specification is measured using a spectrophotometer.
It is a value measured in the entire wavelength band of 50 to 750 nm. That is, “the reflectance is 70% or more” means that the reflectance is 70% or more in the range of 450 to 750 nm.
% Means that there is no wavelength band having a reflectance of less than 10%.

The light transmittance of the adhesive is usually 70.
%, Preferably at least 80%, particularly preferably at least 90%. The “light transmittance” in this specification is a value measured using a spectrophotometer in the entire wavelength band of 450 to 750 nm. That is, “the transmittance is 70% or more” means that 450 to 750 n
In the range of m, it means that there is no wavelength band having a reflectance of less than 70%.

The total thickness of the reflective layer is not particularly limited as long as the present invention is not impaired. However, in order to easily adhere to the curved light emitting surface, it is preferable to make the flexibility good. From such a viewpoint, usually 1 to 500
μm, preferably 10 to 300 μm. Also, the thickness of the adhesive layer is not particularly limited as long as the present invention is not impaired. However, in order to easily adhere the reflective film to the curved light emitting surface, it is preferable to effectively increase the adhesive force. From such a viewpoint, usually 5 to 200 μm
m, preferably 10 to 100 μm.

Preferably, the plane dimensions of the reflection film are determined so that the entire light emitting device in which the reflection film is incorporated is not bulky. For example, the plane dimensions of the reflective film are determined so that the entire reflective surface of the reflective film is in close contact with the light emitting surface of the light source (that is, so as not to have a surplus portion that does not adhere to the light emitting surface). Further, the adhesive layer may be disposed on the entire reflection surface of the reflection film, or may be disposed so as to cover a part of the reflection surface. However, when the adhesive layer is disposed on the entire surface on the opposite side of the reflective film, the following advantageous effects are also exhibited. As described below, the dielectric reflective layer is typically formed from a polymer material. Therefore, when the light-emitting device incorporating the reflective film is used for a long time, deformation such as shrinkage and wrinkling is likely to occur due to the heat generated by the light source. However, if the entire reflective surface of the reflective film is fixedly adhered along the light emitting surface, such deformation can be effectively prevented even when the reflective film is in close contact with a light source as a heat source. (Dielectric Reflecting Layer) As described above, in one embodiment of the present invention, the reflecting layer comprises a dielectric reflecting layer. Suitable dielectric reflective layers include the first
A first layer composed of a plurality of layers of a dielectric polymer
And a second set composed of a plurality of layers of a second dielectric polymer having a different refractive index from the first dielectric polymer, wherein the first polymer layer and the second It is formed by alternately laminating polymer layers. That is,
At least one of the first and second sets is such that the product (nd) of the thickness (d, unit: nm) and the refractive index (n) of the polymer is a quarter of the wavelength of the reflected light. It comprises a quarter-wave layer, which is 1, and utilizes the so-called dielectric reflection principle. In addition, since the dielectric reflection layer is formed by laminating a plurality of types of polymers as described above, it has good workability such as cutting and flexibility suitable for adhesion to a curved surface.

The above-described dielectric reflection layer is made of, for example, a dielectric reflection film. Such a dielectric reflection film is formed by (a) forming a dielectric (polymer) layer by multi-layer coating on a transparent flexible film;
(B) It can be formed by a method of forming a multilayer film by a co-extrusion method using a dielectric made of a polymer material. A method for manufacturing such a dielectric reflection film is disclosed in, for example, the aforementioned Japanese Patent Application Laid-Open No. 9-506837.

Polymers that can be used as dielectrics include:
Light transmissive polymers having at least one refractive index, such as polyesters (polyethylene naphthalate, polyethylene terephthalate, copolyesters of ethylene naphthalate-ethylene terephthalate, etc.), acrylic polymers (polymethyl methacrylate, methyl methacrylate and other (meth) A) copolymers with acrylates), polystyrene-based polymers (polystyrene, copolymers of styrene and butadiene, copolymers of styrene and acrylonitrile, etc.), fluorine-based polymers (polyvinylidene fluoride, ethylene fluoride-propylene fluoride copolymer) Polymers), polyethylene, polypropylene, ethylene-acrylic acid copolymer, ethylene-vinyl acetate copolymer, polyvinylidene chloride, polycarbonate, polyurethane, epoxy resin and other polymers are suitable. That. Further, the dielectric reflection film is preferably formed as a multilayer polymer film by the method (b). This is because the workability is good and it is easy to produce the dielectric reflection film of the present invention.

Such a dielectric reflection film is, for example,
A first layer containing one or more of the above-described dielectric polymers and a second layer also containing a dielectric polymer are alternately laminated and formed. Substantially all the layers are smaller than 1 μm, and include a plurality of layers having different thicknesses so as to exhibit the above-described dielectric reflection effect.
The refractive index of each layer is usually 1.1 or more, preferably 1.2 to 2.2.
8 range. Also, the refractive index n1 of the first layer and the second layer
The difference Δn (= | n1-n2 |) from the refractive index n2 of the layer of
Usually in the range of 0.05 to 1.5, preferably 0.1 to 1.0.
Range. When each layer comprises a polymer, each layer is preferably biaxially oriented. This is because the reflectance is effectively improved.

In addition to the above two types, a laminate may be formed by adding one or more dielectric polymer layers. Also, as long as the effect of the present invention is not impaired,
UV absorbers, antioxidants, fungicides, rust inhibitors, hygroscopic agents,
Additives such as colorants, phosphors, and surfactants can also be included. Also, unless the effects of the present invention are impaired,
A dielectric reflection film in which another layer such as a light-transmitting protective layer or a colored layer is formed on the front surface, the back surface, or both surfaces of the dielectric reflection film may be used as the dielectric reflection layer. The thickness of another layer is usually 0.1-100 μm. Further, the dielectric reflection film may be a reflection film having a polarizing effect. (Diffuse reflection layer) In one preferred embodiment of the present invention, the reflection layer comprises:
It is a laminate comprising a dielectric reflection layer and a diffuse reflection layer that is in close contact with a surface (lamination surface) of the dielectric reflection layer opposite to the reflection surface (the surface facing the light source). The diffuse reflection layer, for example,
A reflective paint comprising a binder and light-diffusing particles dispersed in the binder is formed by applying the reflective paint on the laminated surface of the dielectric reflective layer. The coating operation can be performed using a normal coating device such as a knife coater or a bar coater.

As the binder, ordinary polymers and resins for coatings can be used, for example, (meth) acrylate copolymers, polyurethane resins, silicone polymers (including silicone-polyurea copolymers), fluorine Polymer, vinyl chloride polymer, epoxy resin and the like. The light transmittance of the above polymer and the like is preferably as high as possible, and is usually 80% or more.

The light diffusing particles are, for example, white inorganic particles such as titanium oxide and barium sulfate; glass particles; ceramic particles; organic polymer particles; air bubbles; The light diffusing particles may be solid or hollow. The diameter of the light diffusing particles is usually 0.05 to 10 μm. The thickness of the diffuse reflection layer is determined so as to exhibit the above-mentioned effects, and is usually 10 to 100 μm. The mixing ratio of the light diffusing particles in the reflective coating is usually 20 to 800 parts by weight based on 100 parts by weight of the binder (solid content). (Adhesive) The adhesive is preferably as transparent as possible, and has a refractive index of usually 1.3 to 1.8, preferably 1.4 to 1.6. The type of the adhesive is preferably a pressure-sensitive type (pressure-sensitive adhesive), a hot melt type, a heat-sensitive (heat activated type) type, a solvent activated type, or a curable type. The curing type is preferably one that is cured by heat, moisture, or radiation (such as ultraviolet rays).

Suitable adhesives are pressure-sensitive adhesives containing silicone-based polymers (including silicone-polyurea-based copolymers), acrylic polymers, polyurethanes, rubber-based polymers (natural rubber, styrene-based copolymers, etc.). is there. Above all, acrylic pressure-sensitive adhesives are suitable because they have high transparency, high adhesion, and high refractive index (normally 1.4 or more).

The acrylic polymer of the acrylic pressure-sensitive adhesive includes isooctyl acrylate, butyl acrylate,
4 to 14 carbon atoms such as 2-ethylhexyl acrylate
An acrylate monomer having an alkyl group having a polar group such as (meth) acrylic acid, carboxyalkyl (meth) acrylate, hydroxyalkyl (meth) acrylate, or N, N-dialkylacrylamide, which is used if necessary; A) a polymer obtained from a reactant containing an acrylate monomer, or a composition containing such a polymer.

The above adhesive can be provided, for example, by applying a coating solution containing a polymer or a polymer composition on the dielectric reflection layer. Also, after applying a coating solution containing a reactant that produces a polymer after polymerization, a polymerization operation (ultraviolet polymerization, thermal polymerization, or the like) may be performed on the reflective layer to form an adhesive layer. Alternatively, a film adhesive separately formed on a release film can be transferred from the release film onto the dielectric reflection layer.

The adhesive is usually colorless, but contains a coloring agent such as a pigment or a dye unless the effects of the present invention are impaired.
It may be colored. Further, additives such as an ultraviolet absorber, an antioxidant, a fungicide, a rust inhibitor, a moisture absorbent, a phosphorescent substance, and a surfactant can be contained. (Light Emitting Device) The light emitting device of the present invention comprises: (a) a light source;
(B) The light-emitting device is characterized in that the light-emitting device is provided with the reflective film that is in close contact with the light-emitting surface of the light source via an adhesive layer so as to cover a part of the light-emitting surface of the light source. The light source used in the light emitting device of the present invention can be a fluorescent tube, a hot cathode, a cold cathode tube, a neon tube, a xenon tube, etc., and the output is
Usually, it is 2W to 200W. The shape of the light source is not particularly limited, and may be a straight pipe (linear); a circle (including an ellipse); a bent shape representing a character, a figure, or the like. In the light emitting device of the present invention, the total reflection surface of the reflection film can be brought into close contact with the light emission surface of the light source. In this case, since the outer shape and dimensions of the light emitting device are substantially the same as the light source used,
Problems caused by bulkiness when the conventional external reflection device is included can be easily solved.

The light-emitting device of the present invention can be used as a lighting device for downlighting a display such as a room light, a desk light, or a showcase, or a direct light box, a light box of an edge light system, a neon sign. Also, it can be used as a light source for an internal illumination type signboard or the like. For example, it can be applied to a direct light box as follows. The light emitting device (light source) is disposed in a light guide space of a box (usually a rectangular parallelepiped) having a cavity (light guide space). The box usually includes a top plate having a light-transmitting light-emitting surface, opaque side plates (four), and a bottom plate. The inner surface of the side plate and the bottom plate (the surface facing the light guide space)
Coated with reflective material. The top plate is preferably a white translucent diffuse transmission plate. On the other hand, the light emitting device is arranged between the top plate and the bottom plate. Further, a light-emitting device is manufactured by adhering the reflective film of the present invention to a light source so that light is emitted with a predetermined directivity. In this case, the ratio of the coating area of the reflective film is usually in the range of 10 to 50%. The number of light emitting devices (light sources) to be arranged is usually 1 to 10, preferably 2 to 6. The light emitting device is arranged parallel to the bottom plate and / or the top plate. When a plurality of light emitting devices are used, the light emitting devices are usually arranged in parallel with each other.

The reflecting material covering the inner surfaces of the side plate and the bottom plate is as follows:
Those having no conductivity are preferred, and the above-mentioned diffuse reflection layer is usually used. However, it is preferable to use a dielectric reflection film in order to effectively increase the radiation intensity of light from the light emitting surface. In addition, using the reflective film of the present invention prepared using a dielectric reflective film having both reflective surfaces, the reflective film is adhered to the inner surface of the side plate and the bottom plate through the adhesive layer to provide good reflectivity. You can also.

Further, the shape of the reflective film constituting the light emitting device is adjusted so that most of the light from the light emitting device is emitted toward the bottom plate and the side plates, and a part of the light is also emitted toward the top plate. It is preferred to determine the dimensions. Thereby, the brightness on the light emitting surface can be uniformly increased. For example, as shown in FIGS. 2 and 3, it is preferable that a plurality of slits (cuts) 14 are provided in two long sides (both edges in the width direction) of the substantially rectangular reflective film 4. The shape of the slit is preferably a polygon such as a triangle or a quadrangle, a circle, an ellipse, or a shape derived from a shape obtained by regularly combining a plurality of curves as illustrated. The maximum depth of the cut from the edge of the long side portion of the reflective film (the maximum dimension in the direction from the edge toward the center of the reflective film) is usually 2 to 20 mm, and preferably 3 to 10 mm. Further, the distance between adjacent slits (the distance between the center portions of the slits in the direction along the long side of the reflective film) depends on the cutting depth of the slits, but is usually 2 to 20 mm, preferably 3 to 20 mm.
10 mm. The shapes of the plurality of slits are generally substantially the same, but a plurality of slits having different shapes and / or dimensions can be combined depending on the application.

The direct type light box as described above can improve the light emission luminance and the luminance unevenness on the light emitting surface, as compared with the conventional light box.

[0035]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described with reference to the embodiments. It should be understood that the present invention is not limited to these examples. Example 1 (1) Formation of reflective film: First, a dielectric reflective film used as a dielectric reflective layer was prepared. This dielectric reflection film was produced by the method disclosed in the above-mentioned Japanese Patent Publication No. 9-506837. The two polymers forming the alternating layers were polymethyl methacrylate and an ethylene naphthalate-ethylene terephthalate based copolyester. The reflectivity of the dielectric reflection film is about 80 to 10
0% (450-750 nm) and the thickness is about 70 μm
Met.

Next, a thickness of 8 on the reflection surface of the dielectric reflection layer.
A 0 μm acrylic pressure-sensitive adhesive (light transmittance = about 98%) was laminated to form a reflective film of this example. The reflective film of this example had good flexibility. Both the reflectance and the light transmittance were measured using a self-recording spectrophotometer “(type) U-4000” manufactured by Hitachi, Ltd. (2) Production of Light Emitting Device: The reflective film of this example was cut to have a predetermined size and shape, and this was cut into a fluorescent tube, “(trademark) Paruk Day FL-20 manufactured by Matsushita Electric Industrial Co., Ltd.
The light-emitting device of this example was formed by manually adhering to the peripheral surface of SS.EX-D / 18 "so as to have a predetermined coating (wrapping) angle, and fixed on the light-emitting surface of a fluorescent tube.

In this embodiment, the reflecting film is formed as a reflecting film with a length (vertical) substantially equal to the length of the fluorescent tube in the longitudinal direction and three kinds of covering angles (90 °, 180 °, and 270 °). Three types of reflective films cut into a substantially rectangular shape having a width (horizontal) such that the entire surface is in close contact were prepared, and three types of light emitting devices were manufactured. Fabrication of these light emitting devices was extremely easy at any covering angle. (3) Directivity evaluation: The radiation directivity of the light emitting device was measured as follows. That is, the light emitting device is rotated at 5 ° intervals around an axis along the length direction of the fluorescent tube,
The irradiation luminance at each angle was measured with a luminance meter (“(product number) BM-7” manufactured by Topcon Corporation), and the directivity was evaluated based on the results. FIG. 4 shows the results plotted on a graph in which the horizontal axis represents the rotation angle and the vertical axis represents the luminance. In the figure, Curve I is the one not using the reflective film of this example for comparison, Curve II is the one wound at 90 °, Curve III is the one wound at 180 °, and Curve IV is 270 ° winding. Note that the angle “0 °” is a point at the center in the circumferential direction on the peripheral surface of the remaining portion that is not covered with the reflective film of the fluorescent tube in a cross section (circle) crossing the length direction of the light emitting device (fluorescent tube). It was determined that the luminance meter and the light-emitting device were arranged such that an extension of a line connecting the center line of the cross-section circle and the light-receiving surface of the luminance meter intersected perpendicularly. From this graph, it can be seen that as the covering angle increases, the illuminable range becomes narrower, and instead the brightness improves. That is, by using the reflective film of the present invention, the radiation directivity can be easily and effectively improved. Note that the distance between the light receiving surface of the luminance meter and the light emitting surface of the light emitting device was about 1 m. Example 2 A reflective film of this example was formed in the same manner as in Example 1 except that the dielectric reflective film further included a diffuse reflection layer in close contact with the surface opposite to the reflection surface. The diffuse reflection layer is made of a white reflection paint containing barium sulfate (“(Product name) New LP Super” manufactured by Toyo Ink Co., Ltd.)
The film was directly applied to a dielectric reflection film and dried so that the thickness after drying was 50 μm. Using this reflective film, a light emitting device was formed in the same manner as in Example 1, and the directivity was evaluated. In the case of this example, as in the first embodiment, the radiation directivity could be easily and effectively improved.

In the reflection film of Example 1, 40
The reflectance for light in the wavelength band of 0 to 450 nm is about 6
Although it was in the range of 5 to 80%, in Example 2, diffuse reflection was performed.
400 to 450 nm wavelength band
Reflectance for light in the region has increased to about 90-98%
(Measured by the above spectrophotometer). That is, the emission of the light source itself
When the light wavelength distribution extends from 400 to 450 nm
Also, with almost no change in the wavelength distribution of the reflected light,
It was found that irradiation could be performed toward the illuminated area. Comparative Example 1 Without using an adhesive, a dielectric reflective film can be used as the light emitting surface of the fluorescent tube.
Except that it is wound around and placed in the same manner as in Example 1.
Example light emitting devices were formed. The covering (wrapping) angle is 9
0 °, 180 °, and 270 °, light emitting surface and dielectric reflection
Although there is an air layer between the film and the reflective surface,
Make sure that the dielectric reflection filter is as close as possible
Lum was wrapped around a fluorescent tube. As a result, compared to the first embodiment
As a result, it was found that the luminance decreased by about 3.5%. Sand
That is, in order to effectively improve both the brightness and the directivity,
Uses the reflective film of the present invention, and reflects the light emitting surface of the light source
It is better to make the reflective surface of the film adhere closely with the adhesive.
It turned out.Example 3 Using the light emitting device of the present invention, a direct type
To box was formed.

First, a commercially available light box ("(product name) medical X-ray observation apparatus" manufactured by Kihara Medical Industry Co., Ltd.)
The light-emitting device of this example was formed by adhering the reflection film produced in Example 1 to the fluorescent tube incorporated in the device. In this example, a rectangular (about 420 mm long × about 15 mm wide) reflective film was first formed, and a plurality of slits were provided on two long sides of the reflective film.
The shape of the slit is a substantially isosceles triangle, the maximum depth of the cut from the edge of the long side of the reflective film is 5 mm,
The distance between adjacent slits was 5 mm. Also, the coverage area ratio was about 14% (see FIG. 2).

Next, four light emitting devices of the present example are arranged in the light guide space of the light box so as to be parallel to the top plate and to be parallel to each other. Light box formed. The light-emitting device is arranged so that its light-emitting surface (the portion not covered with the reflective film) faces the bottom plate, and most of the light from the light-emitting device is emitted toward the bottom plate and the side plates, and Part of the light was emitted toward it. In addition, the top plate was formed from a milky white diffuse transmission acrylic plate, and the inner surfaces of the inner walls (bottom plate and four side plates) of the light box were painted with a white diffuse reflection paint.

The front luminance of the light emission surface of the top plate of the direct type light box was measured using a luminance meter ((product number) LS-110, manufactured by Minolta Co., Ltd.). The average luminance was 840 cd / m ² and the luminance unevenness (minimum value / maximum value × 100) was 65%. On the other hand, when measured without using the reflective film of the present invention, the average luminance was 9%.
The luminance was 54 cd / m ² and the luminance unevenness was 58%. That is, it was found that by replacing the light source of the ordinary light box with the light emitting device of the present invention, the luminance unevenness can be improved without greatly lowering the light emission luminance.
The distance between the light receiving surface of the luminance meter and the light emitting surface of the light box was about 1 m. Example 4 On the inner wall (bottom plate and four side plates) of the light box,
A direct-type light box of this example was formed in the same manner as in Example 3, except that the reflection surface of the dielectric reflection film used in Example 1 was bonded toward the light guide space.

The front luminance of the light emitting surface of the top plate of the direct type light box was measured in the same manner as in Example 3. The average luminance was 1698 cd / m ² and the luminance unevenness was 83%.
Met. That is, it was found that the luminance and the luminance unevenness can be greatly improved by replacing the light source of the ordinary light box with the light emitting device of the present invention and covering the inner wall of the light guide space with the dielectric reflection film. In the light box of this example, when measured without using a reflective film covering the light source, the average luminance was 1902 cd.
/ M ² , and luminance unevenness was 80%. Example 5 A reflective film of this example was prepared in the same manner as in Example 2 except that a blue light-transmitting colored layer was disposed between the adhesive (acrylic pressure-sensitive adhesive) layer and the dielectric reflective film. Was formed. That is, the dielectric reflection layer of this example was composed of the dielectric reflection film and the colored layer. The coloring layer was a coating film having the following composition, and had a thickness of 0.5 μm. Composition of the light-transmitting colored layer: Heliogen Blue L6700F (blue pigment obtained from BASF) 100 parts by weight Disperbyk 161 (dispersant obtained from BYK-Chemie) 15 parts by weight CARBOSET GA1162 (obtained from BF Goodrich) (Acrylic polymer) 163 parts by weight SU8 (epoxy crosslinking agent obtained from Shell Chemical Company) 107 parts by weight Using the reflective film of this example, a light emitting device was formed in the same manner as in Example 1, and the directivity was evaluated. . In the case of this example, as in the first embodiment, the radiation directivity could be easily and effectively improved. The color of the emitted light is blue (x value of chromaticity =
About 0.276, y value = 0.294). The luminous color of the light source (fluorescent tube) itself is such that the chromaticity x value is about 0.5.
310, y value = 0.322. In addition, the chromaticity of the emission color was measured by the above-described luminance meter (“(product number) BM-7” manufactured by Topcon Corporation).

According to the results of this example, when the reflective film of the present invention contains the above-mentioned light-transmitting colored layer, the color of emitted light (emission color) can be changed without changing the color of the light source. I knew I could do it. For example, a light-emitting device having a desired light-emitting color can be easily formed at a light-emitting device installation site without preparing a light-emitting device having a predetermined light-emitting color like a neon tube in advance.

[0044]

As described above, according to the present invention, even when the space for arranging the external reflection device cannot be sufficiently obtained, the directivity of the radiated light and the illumination range are set to the use conditions. There is provided a reflective film that can be easily changed and that can effectively increase the intensity of emitted light of a light emitting device. Further, a light emitting device capable of effectively increasing the intensity of radiated light by using such a reflective film is also provided.

[Brief description of the drawings]

FIG. 1 is a sectional view showing a preferred embodiment of a light emitting device according to the present invention.

FIG. 2 is a cross-sectional view showing a preferred shape of the reflection film according to the present invention.

FIG. 3 is a sectional view showing another preferred shape of the reflection film according to the present invention.

FIG. 4 is a graph showing the results of evaluating the radiation directivity of the light emitting device according to the present invention, in which the rotation angle is plotted on the horizontal axis and the irradiation luminance is plotted on the vertical axis.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 light source 2 adhesive layer 3 reflective layer 4 reflective film 10 light emitting device 14 slit

 ──────────────────────────────────────────────────の Continued on the front page (72) Inventor Shinji Sugii 2-33-1 Tamagawadai, Setagaya-ku, Tokyo Sumitomo 3M Limited

Claims (2)

[Claims] 1. A reflecting film which is in close contact with a part of a light emitting surface of a light source so as to cover the light emitting surface and increases the intensity of radiated light from the remaining uncoated portion of the light emitting surface. A reflection film, comprising: a dielectric reflection layer having a reflection surface; and a layer of a light-transmitting adhesive adhered on the reflection surface of the dielectric reflection layer. 2. The light source according to claim 1, wherein (a) the light source and (b) the light source is in close contact with the light emitting surface of the light source via a light transmitting adhesive layer so as to cover a part of the light emitting surface of the light source. A light-emitting device comprising: the reflection film according to claim 1, wherein the intensity of radiated light from the remaining portion of the light-emitting surface of the light source that is not covered with the reflection film is increased.