WO2014192194A1

WO2014192194A1 - Light box

Info

Publication number: WO2014192194A1
Application number: PCT/JP2013/084280
Authority: WO
Inventors: 利弥西林
Original assignee: 株式会社デュエラ
Priority date: 2013-05-29
Filing date: 2013-12-20
Publication date: 2014-12-04

Abstract

Provided is a light box which causes light emitted from a light source to be reflected inside a housing, and extracts said light, as surface-emission light, from a light-extraction surface of the housing. The light box is provided with: a housing (100) provided with a light-extraction surface (110), a facing surface (111) facing the light-extraction surface (110), and peripheral surfaces (112) which extend from a periphery of the facing surface (111), and surround a space between the light-extraction surface (110) and the facing surface (111); a light source (120) which is provided to one of the peripheral surfaces (112), and which irradiates the space with light; and a divergence-angle restriction means (130) for restricting, to 40˚ or less, the divergence angle of light emitted from the light source (120) in a plane which includes the optical axis of the light source (120), and which is orthogonal to the light-extraction surface (110). As a result, provided is a light box which can be produced at low cost, which exhibits high uniformity with respect to a light-emission state of the light-extraction surface, and with which the loss of light irradiated from the light source can be suppressed.

Description

light box

The present invention relates to a light box used for a backlight of a display device, a lighting fixture, and an electric signboard.

LEDs (Light Emitting Diodes) have a longer life than incandescent bulbs, fluorescent lamps, and the like, and in recent years, improvement in luminous efficiency, higher output, and lower prices are progressing. Along with this, LEDs have been widely used as light sources of light boxes used for backlights of display devices, lighting fixtures, electric signboards, and the like.

However, since the LED is a point light source, in order to use it for a light box, it is necessary to convert the point emission by the LED into uniform surface emission. As a technique for obtaining surface light emission, an edge light system using a light guide plate, a direct type system in which LEDs are arranged in a planar shape, and the like are known.

The edge light method is a method in which LED light is irradiated to the end face of a light guide plate made of a transparent acrylic plate or the like, and the light is repeatedly reflected inside the light guide plate and taken out from a wide surface of the light guide plate. . Dots for diffusing light are distributed in the light guide plate, and light traveling inside the light guide plate hits the dots and changes direction so that it strikes a wide surface of the light guide plate at an angle smaller than the total reflection angle. The light is emitted to the outside (see, for example, Patent Document 1). According to this method, uniform surface light emission can be easily obtained and a large area can be dealt with. However, there is a drawback that the light emission efficiency is lowered due to the influence of light leakage at the end face of the light guide plate, absorption of light inside the light guide plate, light loss at the dot portion, and the like. In addition, since the light guide plate is relatively expensive, a technique for obtaining surface light emission without using the light guide plate has been demanded due to the recent demand for cost reduction.

On the other hand, the direct type method is a method in which a plurality of LEDs are arranged on the bottom surface of a light box and light is irradiated toward a light extraction surface to which a diffusion plate is attached (for example, see Patent Document 2). In this method, since the light of the LED is directly applied to the diffusion plate, the luminance increases at the portion corresponding to the front of each LED, and uneven luminance occurs. Therefore, this method cannot use LEDs with a large amount of light, and it is necessary to arrange a large number of LEDs with a relatively small amount of light.

Therefore, a technology called a lens method or a light diffusing reflector method has been developed as an improvement of the direct type.

In the lens system, a wide-angle lens or a diffusion lens is attached to the LED in order to suppress the front luminance of the LED in the direct type system as described above (see, for example, Patent Document 3). However, there is a problem that the loss of light is large, the lens is arranged between the LED and the diffusion plate, the light box becomes thick, and the cost for the lens increases.

In the light diffusing reflection plate method, the entire light box is made up of a reflection plate, and surface light emission is made uniform by distributing large and small through holes in the reflection plate on the light extraction surface side (see, for example, Patent Document 4). ). However, due to the structure, multiple reflection inside the light box is unavoidable, and light loss occurs, and the through hole on the light extraction surface includes a very small hole of 0.3 mm. There is a problem that the processing is expensive.

Japanese Patent No.2689781 JP 2003-207780 A JP 2007-115424 A Japanese Patent No. 4280283

The present invention has been made in view of the above points, and the object of the present invention is that it can be manufactured at low cost without using expensive parts, and the uniformity of the light emission state of the light extraction surface is high. An object of the present invention is to provide a light box that can suppress a loss of irradiation light from a light source.

The light box according to the present invention, which has been made to solve the above problems,
A light box for reflecting light emitted from a light source inside a housing and taking out light from the light extraction surface of the housing as surface light emission,
a) a housing having a facing surface facing the light extraction surface, and a peripheral surface extending from a peripheral edge of the facing surface and surrounding a space between the light extraction surface and the facing surface;
b) a light source disposed on the peripheral surface and irradiating the space with light;
c) a spread angle regulating means for regulating a spread angle of light emitted from the light source in a plane that includes the optical axis of the light source and is orthogonal to the light extraction surface;
It is characterized by having.

In addition, although LED is typically used as a light source in the present invention, other light sources such as a light bulb, a fluorescent lamp, a cold cathode tube, and the like can also be used.

The light box having the above-described configuration is configured to reflect the irradiation light from the light source inside the housing and extract the reflected light from the light extraction surface. Therefore, it is not necessary to use an expensive light guide plate as in the above-described edge light method, and furthermore, since surface emission can be obtained with a smaller number of LEDs than in the direct irradiation method, it can be manufactured at low cost. it can. Furthermore, by providing a spread angle regulating means for regulating the spread angle of the light emitted from the light source, it is possible to prevent the light emitted from the light source from entering the light extraction surface or the opposite surface in the immediate vicinity of the light source. it can. Thereby, it is possible to prevent the light emission intensity on the light extraction surface from increasing only in the vicinity of the light source and to obtain uniform surface light emission.

In the light box according to the present invention, it is preferable that light from the light source is incident on the facing surface at an incident angle of 70 ° or more.

If the incident angle of light on the opposing surface is increased in this way, the emission angle of the light reflected by the opposing surface also increases. As a result, most of the light incident on the opposing surface from the light source does not go to the light extraction surface in the immediate vicinity, but travels further into the housing. Thereby, it is possible to prevent the amount of light incident on the light extraction surface in a region far from the light source from being reduced, and to obtain more uniform surface light emission.

When the facing surface of the housing is flat and the peripheral surface is substantially perpendicular to the facing surface, part of the light emitted from the light source and reaching the back of the housing has a small incident angle. Is incident on. Since this light is reflected on the peripheral surface at a small emission angle and returns to the front side of the housing, the amount of light reaching the light extraction surface on the back side of the housing is reduced accordingly.
Therefore, it is desirable that the light box according to the present invention be provided with a slope that approaches the light extraction surface as the distance from the light source increases in a region or the facing surface of the peripheral surface facing the light source.

By providing such an inclination, light reaching the back of the casing can be incident on the inclined portion with a large incident angle. Since the light is reflected further toward the back of the housing at a large emission angle and reaches the light extraction surface, a decrease in emission intensity in a region far from the light source is suppressed.

Further, in the light box according to the present invention, it is desirable that the light source is installed so as to be inclined so as to be separated from the light extraction surface as its optical axis is moved away from the light source.

This makes it possible to reduce the light directly traveling from the light source to the light extraction surface, and thus more effectively prevent the emission intensity from increasing in the vicinity of the light source.

In addition, when the light source is arranged so as to be inclined in this way, the incident angle of the light incident on the opposing surface or the peripheral surface becomes small in the vicinity of the light source.
Therefore, the light box according to the present invention is provided with an inclination in the region adjacent to the light source on the peripheral surface or the region on the facing surface adjacent to the region so as to approach the light extraction surface as the light source is approached. It is desirable that

This makes it possible to increase the incident angle of light on the opposing surface or peripheral surface in the region near the light source. As a result, the emission angle of the reflected light in the region also increases, so that the reflected light can be blown into the back of the housing, and more uniform surface emission can be obtained.

In the light box according to the present invention, the divergence angle restricting means has a cross-sectional shape in a plane that includes the optical axis of the light source and that is orthogonal to the light extraction surface, toward the opposite side of the light traveling direction on the optical axis. The cover may be a substantially V-shaped or U-shaped cover that is convex.

Further, the divergence angle regulating means may be a lens.

In addition, when using LED as a light source, the above-mentioned cover and lens are attached directly to the LED chip or attached to the LED substrate, and are not attached directly to the LED or LED substrate, but to another support method. It is good also as a structure which maintains the positional relationship with LED.

Further, in the light box according to the present invention, it is preferable that the facing surface and the peripheral surface are integrally formed.

This makes it possible to prevent a gap from being formed between the opposing surface and the peripheral surface, and prevent light from leaking from the housing, thereby increasing the light utilization efficiency.

In the light box according to the present invention, it is desirable that the housing has a plurality of protrusions that reflect light from the light source on at least the facing surface.

In the light box according to the present invention, the light source is preferably an LED array in which a plurality of LED elements are arranged in a one-dimensional manner.

In the light box according to the present invention, the light extraction surface has a polygonal shape, and is located at a position corresponding to one or a plurality of sides of the polygon as viewed from a direction perpendicular to the light extraction surface. It is desirable that the light source is arranged.

In the light box according to the present invention, the light extraction surface has a polygonal shape, and the light source is arranged at one or more corners of the polygon as viewed from a direction perpendicular to the light extraction surface. It is desirable that

Further, in the light box according to the present invention, it is preferable that a diffusion plate for diffusing light emitted from the light extraction surface is disposed on the light extraction surface.

As described above, according to the present invention, it is possible to provide a light box that can obtain surface light emission with high uniformity with little loss of irradiation light from a light source and can be manufactured at low cost.

The perspective view which shows the outline of the light box which concerns on 1st Embodiment of this invention. It is a figure which shows the reflective nozzle in the said light box, Comprising: (a) is a perspective view, (b) is a top view, (c) is a side view. It is a schematic diagram which shows the path | route of the light from LED, Comprising: (a) shows the case where there is no reflective nozzle, (b) shows the case where a reflective nozzle is provided. The perspective view which shows the structure which provided the diffusion plate in the said light box. The perspective view which shows the example in the case of attaching LED to the corner of a light box. The perspective view which shows another example in the case of attaching LED to the corner | angular of a light box. The perspective view which shows the example in the case of attaching LED to four corners and two sides of a light box. The perspective view which shows the structure of the light box which concerns on 2nd Embodiment of this invention. It is a figure which shows the said light box, Comprising: (a) is a top view, (b) is a side view. It is a figure which shows the reflective nozzle in the said light box, Comprising: (a) is a perspective view, (b) is a top view, (c) is a side view. It is a schematic diagram which shows the course of the light from LED, Comprising: (a) shows the case where a side surface is perpendicular | vertical with respect to a bottom face, (b) shows the case where a bottom face and a side surface are inclined. The schematic diagram which shows another example of the shape of the light box which concerns on 2nd Embodiment of this invention. The schematic diagram which shows the example of the course of the light at the time of providing a protrusion in the inside of the said light box. The perspective view which shows the shape of the said protrusion. The schematic diagram which shows another example of the shape of the said light box. The perspective view which shows the outline of the light box which concerns on 3rd Embodiment of this invention. The schematic diagram which shows another example of the divergence angle control means in this invention.

Hereinafter, embodiments of a light box according to the present invention will be described with reference to the drawings.

FIG. 1 is a perspective view of a light box according to a first embodiment of the present invention. In the following, the vertical direction is defined with reference to FIG.

The light box according to the present embodiment includes a housing 100 and an LED 120. The casing 100 has a bottom surface 111 and a side surface 112, and has a shallow box shape with an open top surface. Here, the bottom surface 111 corresponds to the facing surface in the present invention, and the side surface 112 corresponds to the peripheral surface. An opening 113 is provided at one place on the side surface 112, and the light emitted from the LED 120 attached to the outside of the housing 100 is emitted from the opening 113 to the inside of the housing 100. The light irradiated to the inside of the housing 100 is reflected by the bottom surface 111 and the side surface 112 of the housing 100 and is extracted from the top surface to the outside. Hereinafter, the upper surface is referred to as a light extraction surface.

At least the inner surface (reflection surface) of the housing 100 is made of a material having a reflectance in the visible light range of 85% or more and a total light transmittance of 10% or less. Specifically, a metal steel plate that has been polished so that it is glossy, or a metal plate that has been subjected to metal plating or high diffuse reflection coating, or thermoplastic resin injection molding, sheet bending, or sheet molding What was shape | molded by methods, such as a process, can be used. Specific examples of thermoplastic resins that can be used include acrylic resins, methacrylic resins, polyolefins, polyamides, polyesters, polycarbonates, styrenic resins, polyethers, polyurethanes, polyphenylene sulfides, polyester amides, polyether esters, polyvinyl chlorides. , Modified polyphenylene ether, polyarylate, polysulfone, polyimide, polyetherimide, polyamideimide, or a copolymer containing these as main components, or a mixture thereof, but is not limited thereto. . As a more suitable material, a sheet material (fine foam reflection sheet) containing fine bubbles can be mentioned. As the fine foam reflection sheet, an acrylic foam sheet (for example, “Diffle” manufactured by Duela Co., Ltd.) manufactured by a supercritical fine foam sheet molding process and having a visible light diffuse reflectance of 90% or more is used. Is desirable. Here, the diffuse reflectance of the visible light means the ratio of the diffuse reflectance flux to the incident light flux, measured at a wavelength of 550 nm with a self-recording spectrophotometer, and diffused on a white plate in which fine powder of barium sulfate is hardened. This is a value obtained as a relative value with a reflectance of 100%. As the self-recording spectrophotometer, for example, UV-3100PC (manufactured by Shimadzu Corporation) can be used.

The housing 100 preferably has a bottom surface 111 and a side surface 112 integrally formed. Integral molding is a method like injection molding, in which resin is injected with the same mold so that the bottom and side surfaces are integrated, or sheet-like material is softened by heat and then vacuum or compressed air is used. The bottom surface and the side surface are formed into an integral shape by a method called vacuum forming in which a sheet is pressed against a mold with the pressure of By integrally molding, it is possible to prevent a gap from being formed between the bottom surface 111 and the side surface 112, and it is possible to send light that has entered the housing 100 to the light extraction surface 110 without leaking.

The light box according to the present embodiment further includes a reflection nozzle 130 (corresponding to a cover in the present invention) attached to the LED 120 as a characteristic component of the present invention. Hereinafter, the function of the reflection nozzle 130 will be described.

Generally, the light emitted from the LED is emitted from the LED surface at a spread angle of about 90 ° to 130 °. However, in the configuration in which the light of the LED 120 is irradiated from the side surface 112 as in the light box of the present embodiment, when the light is irradiated at such a wide angle, a large amount of light travels toward the light extraction surface 110 in the vicinity of the LED 120 ( FIG. 3 (a)). As a result, only the vicinity of the LED 120 becomes bright, and conversely, the portion far from the LED 120 becomes relatively dark, so that the surface emission state on the light extraction surface 110 becomes uneven. Therefore, in the light box according to the present embodiment, the reflection nozzle 130 as shown in FIG. 2 is mounted on the LED 120 to limit the light spreading angle in the vertical direction (FIG. 3B). Thereby, the light reaching the light extraction surface 110 and the bottom surface 111 in the vicinity of the LED 120 can be reduced, and the light from the LED 120 can reach a farther region in the housing 100. As a result, since the light from the LED 120 reaches the entire area within the housing 100, it is possible to obtain uniform surface emission on the light extraction surface 110.

1 and 2, the reflection nozzle 130 has a shape in which the opening angle is small in the vertical direction and the opening angle is widened in the horizontal direction. In addition, an LED attachment hole 131 for exposing the light emitting portion of the LED 120 into the reflection nozzle 130 is provided in the central portion of the reflection nozzle 130. The cross-sectional shape in the vertical direction of the reflection nozzle 130 is set so that the irradiation angle of the emitted light from the LED 120 is 40 ° or less, preferably 30 ° or less, and the light emitted from the LED 120 is irradiated at an angle close to parallel light rays. I will let you. The cross-sectional shape is preferably a curve close to a part of an ellipse or a curve close to a parabola, although it depends on the light emission angle of the LED 120 itself. On the other hand, the cross-sectional shape in the left-right direction is designed to an appropriate value according to the dimensions of the housing 100 and the mounting position of the LED 120. Specifically, it is desirable that the irradiation angle of the light emitted from the LED 120 is 80 ° to 140 °. Thereby, light can be irradiated in a direction parallel to the light extraction surface 110 with a sufficient spread angle.

When the LED 120 equipped with such a reflective nozzle 130 is attached to the housing 100 such that its optical axis is parallel to the light extraction surface 110 (and the bottom surface 111), the light from the LED 120 is reflected on the bottom surface of the housing 100. The incident angle when directly entering 111 is 70 ° or more. As described above, when the incident angle of light on the bottom surface 111 is increased, the emission angle of the light reflected by the bottom surface 111 is increased accordingly. As a result, the light emitted from the LED 120 can travel to the back of the housing 100, and a sufficient amount of light can be obtained even in a region far from the LED 120.

Although the material and manufacturing method of the reflective nozzle 130 are not particularly limited, for example, a metal material such as iron, stainless steel, aluminum, or magnesium alloy formed by a method such as sheet metal processing, a welded structure, or casting, The thermoplastic resin may be molded by a method such as injection molding, sheet bending, or sheet molding. Specific examples of thermoplastic resins that can be used include acrylic resins, methacrylic resins, polyolefins, polyamides, polyesters, polycarbonates, styrenic resins, polyethers, polyurethanes, polyphenylene sulfides, polyester amides, polyether esters, polyvinyl chlorides. , Modified polyphenylene ether, polyarylate, polysulfone, polyimide, polyetherimide, polyamideimide, or a copolymer containing these as main components, or a mixture thereof, but is not limited thereto. . The inner surface (reflective surface) of the reflective nozzle 130 may be plated with metal. Further, the reflection nozzle 130 may be made of the same material as that of the housing 100, and both may be integrally formed. Thereby, it is possible to prevent light from leaking between the reflective nozzle 130 and the housing 100.

As shown in FIG. 4, a diffusion plate 140 for diffusing light emitted from the light extraction surface can be installed on the light extraction surface of the light box. In particular, when the light box according to the present embodiment is used as a backlight for a liquid crystal display or the like, the diffusion plate 140 needs to be provided.

In FIG. 1, the LED 120 is provided only at one place on the side surface 112 of the housing 100. However, as shown in FIGS. (Refer nozzles are omitted for simplification in FIGS. 5 to 7). The number and position of the LEDs 120 can be appropriately set according to the shape and dimensions of the housing 100, for example, the ratio of length to width. In the example of FIG. 5, the two LEDs 120 are arranged at two opposite corners, and in the example of FIG. 6, they are arranged at two adjacent corners. Further, in the example of FIG. 7, the LEDs 120 are provided at two opposite corners of the four corners of the housing 100 and the four side surfaces 112. The arrangement as shown in FIG. 7 is effective when the size of the casing 100 is large in the vertical direction or the horizontal direction, and the amount of light is insufficient in the central portion only by irradiation from the four corners.

Subsequently, a light box according to a second embodiment of the present invention will be described.

8 is a perspective view of the light box according to the present embodiment, and FIG. 9 is a plan view and a side view of the light box according to the embodiment. In the present embodiment, an LED array 122 in which a plurality of LED elements 121 are arranged in a row as a light source is attached to one of the side surfaces 112 of the housing 100. An opening (not shown) is provided in the side surface 112 to which the LED array 122 is attached, and light from each LED enters the housing 100 through the opening.

In the present embodiment, a long reflective nozzle 130 as shown in FIG. 10 is used as a means for regulating the spread angle of light from the LED array 122. The reflective nozzle 130 has a length that can cover the entire longitudinal direction of the LED array 122, and a long hole-shaped LED is attached to expose the light emitting portion of each LED element 121 in the reflective nozzle 130. A hole 131 is provided. The cross-sectional shape of the reflection nozzle 130 in the vertical direction is set so that the irradiation angle of the emitted light from the LED array 122 is 40 ° or less, preferably 30 ° or less, as in the first embodiment. Moreover, although this cross-sectional shape also depends on the light emission angle of the LED array 122 itself, it is desirable that the cross-sectional shape be a curve close to a part of an ellipse or a curve close to a parabola. The cross-sectional shape in the left-right direction is such that the spread angle of the emitted light from the LED array 122 is 0 ° to 40 ° depending on the ratio of the length of the LED array 122 and the side surface 112 to which the LED array 122 is attached. It is desirable to do so.

Furthermore, the light box of the present embodiment has a feature that a part of the bottom surface 111 and the side surface 112 of the housing 100 is inclined. Hereinafter, this point will be described with reference to FIG. Here, a region close to the LED array 122 (on the left side in FIG. 11) along the optical axis of the LED element 121 located in the center of the LED array 122 is located on the front side, and a region far from the LED array 122 (on the right side in FIG. 11). This is called the back (in FIG. 11, the reflection nozzle is omitted for simplification).

As shown in FIG. 11A, when the bottom surface 111 of the housing 100 is flat and substantially perpendicular to the side surface 112, part of the light reaching the back of the housing 100 is part of the back side surface 112. And return to the front side of the housing 100. Accordingly, the amount of light reaching the light extraction surface 110 on the back side of the housing 100 is reduced accordingly. Therefore, in the present embodiment, by providing the bottom surface 111 and the side surface 112 with an inclination as shown in FIG. 11B in the region on the back side of the housing 100, the light reaching the back of the housing 100 is transmitted. Thus, the light is reflected upward so as to enter the light extraction surface 110 efficiently. The inclination may be a shape such that the inner surface (the bottom surface 111 and the side surface 112) of the housing approaches the light extraction surface 110 as it moves away from the LED array 122, but is desirably located at the center of the LED array 122. When viewed in a cross section including the optical axis of the LED element 121 and perpendicular to the light extraction surface 110, the optical element has a curved surface like a part of an ellipse, and the optical axis of the LED element 121 is projected onto the inner surface of the housing. It is assumed that the curvature of the curve obtained in this manner monotonously decreases from the LED element 121 side. Further, in the cross section, the bottom surface is set such that variations in incident angles (α1, α2, α3,... In FIG. 11B) of light directly incident on the bottom surface 111 and the side surface 112 from the LED element 121 are within 10 °. It is preferable to design the shape. Thereby, the reflected light from the bottom surface 111 can be uniformly incident on the entire light extraction surface 110.

As shown in FIG. 12, the LED array 122 may be attached by being inclined downward so that the optical axis of each LED element 121 is separated from the light extraction surface 110 as the distance from the LED element 121 increases. In the figure, the reflection nozzle is omitted for simplification). Thereby, the light directly incident on the light extraction surface 110 from the LED array 122 can be reduced.

However, in this case, the amount of light reflected by the bottom surface 111 in the vicinity of the LED array 122 and incident on the light extraction surface 110 is increased. Therefore, in order to prevent this, as shown in FIG. 12, it is desirable to provide an inclination on the front side of the housing 100 such that the bottom surface 111 and the side surface 112 approach the light extraction surface 110 as the LED array 122 is approached. Such an inclination can increase the incident angle of light that directly enters the bottom surface 111 or the front side surface 112 from the LED 120. As a result, the emission angle of the reflected light from the bottom surface 111 or the side surface 112 also increases, so that the reflected light can reach the back of the housing 100. The inclination is preferably designed so that the incident angle α of light directly incident on the bottom surface 111 or the near side surface 112 from the LED element 121 is 70 ° or more.

Furthermore, a plurality of protrusions 150 are provided on the bottom surface 111 of the light box according to the present embodiment. Each of these protrusions 150 has a shape that protrudes from the bottom surface 111 of the housing 100 toward the light extraction surface 110, and light rays that travel along the bottom surface 111 of the housing 100 as shown in FIG. 13. Is intended to be reflected toward the light extraction surface 110. The shape of the protrusion 150 is not particularly limited, and may be any shape such as a rectangular parallelepiped, a pyramid shape, a hemispherical shape, and the like. However, the hemispherical shape as shown in FIG. 14 is most preferable because the light beam that collides with the projection 150 and can travel while spreading toward the light extraction surface 110 can be easily processed. The height of the protrusion 150 is preferably about 0.5 mm to 3 mm. The number and arrangement of the protrusions 150 are appropriately set so that the illuminance distribution on the light extraction surface 110 is optimal. Specifically, it is conceivable that the portion near the LED array 122 is likely to be bright and therefore the number of protrusions 150 is reduced, and the portion far from the LED array 122 is likely to be dark and the number of protrusions 150 is increased.

The shape of the bottom surface 111 and the side surface 112 of the housing 100 may be changed stepwise as shown in FIG. 11B in addition to changing continuously as shown in FIG. Further, a stepped step may be provided as shown in FIG. Note that in the configuration in which such an inclination is provided, the boundary between the bottom surface 111 and the side surface 112 of the housing 100 may not be clear.

As described above, the LED can be attached to any position on the side surface of the housing even in the configuration in which the slope and the protrusion are provided on the bottom surface. FIG. 16 shows an example in which LEDs 120 are provided at the four corners of the housing 100 (for the sake of simplicity, the reflective nozzle is omitted). In this case, the light beam from each LED 120 travels from the four corners toward the center of the housing 100. Also in this example, each LED 120 is attached so as to be inclined downward so that the optical axis is separated from the light extraction surface 110 as the distance from the LED 120 increases. Therefore, in this example, the inner surface (that is, the bottom surface 111 and the side surface 112) of the casing 100 has a shape in which the central portion and the four corners are raised, in other words, four quadrangular pyramids with the apex facing downward are arranged two by two. The shape is different. Thereby, the incident angle of the light directly incident on the bottom surface 111 and the side surface 112 from each LED 120 can be increased in the entire casing 100, and surface emission with high uniformity can be obtained.

Instead of using the reflection nozzle as described above as the spread angle regulating means in the present invention, a lens 160 is disposed in front of the LED 120 as shown in FIG. 17, and the spread angle of light from the LED 120 is regulated by the lens 160. You may make it do.

Hereinafter, an experiment conducted for demonstrating the effect of the present invention will be described.

[Comparative example]
SAMSUNG color liquid crystal monitor 21.5-inch (BX2250) backlight part is taken out, light is emitted with the light guide plate and diffusion sheet (thickness 0.2mm) attached, and the overall luminance and luminance distribution at that time Was measured. For the luminance measurement, RISA-Color ONE / 3 (3CCD 1/3 in 12.5-50mm zoom lens) manufactured by Highland Co., Ltd. was used.

At this time, the overall luminance was 3153.5 cd / m ² . The luminance distribution at this time was as shown in Table 1. The luminance distribution is expressed as a ratio of each region when the luminance of each region obtained by dividing the light emitting surface into five parts in the vertical direction and the horizontal direction is measured and the central part is 100% (hereinafter the same). ).

[Experimental Example 1]
The light box having the configuration shown in FIGS. 8 and 9 was subjected to the same measurement as described above. Specifically, the liquid crystal monitor has a light extraction surface of 476 mm in width and 270 mm in length corresponding to a size of 21.5 inches, and the bottom surface and side surfaces are vacuum-molded with a reflection sheet (Duela Co., Ltd. “Diffure” 400 μm) (molding temperature 170). A light box having an integrated housing that is made up of the reflective sheet, and the reflective nozzle made of the reflective sheet is attached to the same light source (LEDs arranged in a straight line) as used in the comparative example, This was mounted on the side of the long side of the light box to emit light. The bottom surface of the housing was formed so as to draw a gentle curved surface from the side surface on which the LED was mounted toward the side surface facing the surface, and hemispherical projections with a diameter of 2 mm were distributed on the inner surface. Further, a diffusion sheet (thickness 0.2 mm) was attached to the light extraction surface.

At this time, the overall luminance was 3449.1 cd / m ² . Further, the luminance distribution at this time was as shown in Table 2.

As a result of the above, in the light box of Experimental Example 1, the overall luminance was improved by 9.4% compared to the comparative example. From this, it was confirmed that the light loss at the light guide plate was large in the light guide plate method of the comparative example, whereas the light loss was suppressed in the method of the present invention. In addition, regarding the luminance distribution, although the luminance was high in the region close to the LED light source (first row in Table 2), it was confirmed that the variation in luminance was smaller in the other portions than in the comparative example.

[Experiment 2]
The light box of Experimental Example 1 was prepared by removing the reflective nozzle attached to the LED, and the LED was caused to emit light. As a result, the light emission in the vicinity of the LED light source became too strong, and it became dark from the center of the light box to the opposite side of the light source.

[Experiment 3]
An LED was produced by exchanging the bottom surface of the light box of Experimental Example 1 with a flat plate (without protrusions) parallel to the light extraction surface. As a result, the incident angle of the light beam hitting the bottom reflector on the side closer to the LED was less than 50 °, and the reflected light was directed directly to the light extraction surface, resulting in an increase in brightness near the LED. Further, since the luminance was high even on the side far from the light source, the luminance distribution was unbalanced with the dark central portion as a whole. This is presumably because the direction of light does not change due to the protrusion, and the light toward the light extraction surface is reduced at the center of the light box.

[Experimental Example 4]
A light box in which the bottom surface of the light box of Experimental Example 1 was replaced with one having no protrusion was created, and the LED was caused to emit light. As a result, the side near the LED and the central part were dark, and the side far from the LED was bright.

[Experimental Example 5]
LEDs with reflection nozzles were attached to the four corners of the light box in FIG. 16 to emit light. As a result, substantially uniform surface light emission was obtained with the central edge on the long side slightly darkened.

[Experimental Example 6]
An LED was added to the central portion of each long side of the light box of Experimental Example 5 to emit light. As a result, although the central end portion on the long side was conversely bright, the overall light emission state was good.

[Experimental Example 7]
As shown in FIG. 5, two LEDs equipped with reflective nozzles were mounted on the diagonal of a light box having a flat bottom surface to emit light. As a result, the light quantity of the LED was insufficient and the corner portion where the LED was not mounted became dark, but the uniformity of the central portion was not bad. Moreover, the optimal luminance distribution was obtained when the LED irradiation direction was slightly shifted from the center.

[Experimental Example 8]
An LED light emission experiment was performed on the light box of Experimental Example 7 from which one LED was removed. In addition, LED was installed so that an optical axis might go to the center of a light box. As a result, the light quantity of the LED was insufficient, and only the central portion of the light box was brightened, but a good light emission state was obtained at the central portion.

DESCRIPTION OF SYMBOLS 100 ... Case 110 ... Light extraction surface 111 ... Bottom 112 ... Side 113 ... Opening 120 ... LED
122 ... LED array 130 ... reflection nozzle 140 ... diffusing plate 150 ... projection 160 ... lens

Claims

A light box for reflecting light emitted from a light source inside a housing and taking out light from the light extraction surface of the housing as surface light emission,
a) a housing having a facing surface facing the light extraction surface, and a peripheral surface extending from a peripheral edge of the facing surface and surrounding a space between the light extraction surface and the facing surface;
b) a light source disposed on the peripheral surface and irradiating the space with light;
c) a spread angle regulating means for regulating a spread angle of light emitted from the light source in a plane that includes the optical axis of the light source and is orthogonal to the light extraction surface;
A light box characterized by comprising:
The light box according to claim 1, wherein light from the light source is incident on the facing surface at an incident angle of 70 ° or more.
3. The light box according to claim 1, wherein a slope of the region facing the light source or the facing surface of the peripheral surface is provided so as to approach the light extraction surface as the distance from the light source increases.
The light box according to any one of claims 1 to 3, wherein the light source is installed so as to be inclined so as to move away from the light extraction surface as its optical axis is moved away from the light source.
The area on the peripheral surface adjacent to the light source or the area on the facing surface adjacent to the area is provided with an inclination so as to approach the light extraction surface as the light source is approached. 5. The light box according to any one of 4.
The divergence angle regulating means is substantially V-shaped such that a cross-sectional shape of a plane including the optical axis of the light source and orthogonal to the light extraction surface is convex toward the opposite side of the light traveling direction on the optical axis. The light box according to any one of claims 1 to 5, wherein the light box comprises a cover having a shape or a substantially U-shape.
The light box according to any one of claims 1 to 5, wherein the divergence angle regulating means comprises a lens.
The light box according to any one of claims 1 to 7, wherein the facing surface and the peripheral surface are integrally formed.
The light box according to any one of claims 1 to 8, wherein the housing has a plurality of protrusions that reflect light from the light source on at least the facing surface.
The light box according to any one of claims 1 to 9, wherein the light source is an LED array in which a plurality of LED elements are arranged one-dimensionally.
The light extraction surface has a polygonal shape, and the light source is disposed at a position corresponding to one or a plurality of sides of the polygon as viewed from a direction perpendicular to the light extraction surface. The light box according to any one of claims 1 to 10.
The light extraction surface has a polygonal shape, and the light source is arranged at one or a plurality of corners of the polygon when viewed from a direction perpendicular to the light extraction surface. The light box according to any one of 1 to 11.
13. The light box according to claim 1, wherein a diffusion plate for diffusing light emitted from the light extraction surface is disposed on the light extraction surface.
A backlight of a display device, characterized by using the light box according to any one of claims 1 to 13.
A lighting fixture using the light box according to any one of claims 1 to 13.