JP2012142252A - Illumination device and showcase equipped with the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thin type illumination device, and a showcase using the same, capable of uniformly illuminating a translucent shade positioned in front from a rear surface and efficiently illuminating an object for illumination located below.SOLUTION: An illumination unit 2A illuminates the translucent shade 3 located in front thereof as a backlight, and at the same time, illuminates an object for illumination located below. A translucent light guide plate 23 guides light incident from a top end face 23a to a lower-part emission face 23d by total reflection at a front face 23b at a side opposed to the shade 3 and a rear face 23c at its rear side. A plurality of LED light sources 21 are sporadically arrayed along a length direction of the rectangular top end face 23a to emit light incident to the top end face 23a. A plurality of diffusion dots for diffusing the incident light are provided at least at either the front face 23b or the rear face 23c, and the shade 3 is illuminated with light diffused by the diffusion dots and the illumination object is illuminated with light emitted from the lower-part emission face 23d of the light guide plate 23.

Description

  The present invention relates to a lighting device and a showcase including the same, for example, a translucent shade mounted on a showcase installed in a store such as a supermarket or a convenience store, and disposed on the front surface of the showcase. The present invention relates to an illuminating device suitable for illuminating products displayed on a shelf board in a showcase together with a showcase having the same.

  Various types of lighting devices for showcases have been proposed. For example, a lighting device for a showcase described in Patent Document 1 has a function of illuminating a product displayed on a shelf board in a showcase from above, and a translucent shade disposed on the front surface of the showcase It has two illumination functions, for example, a function of illuminating (for example, a lighting plate made of a name plate on which product names and the like are described) from the back. In the lighting device, an LED (light emitting diode) light source is arranged near the lower end of the shade with the light emitting surface facing the back side, and the product is illuminated with the light emitted downward, and the light emitted upward is simultaneously emitted. It is configured to illuminate the shade from the back by reflecting off the reflector.

  Further, Patent Document 2 proposes a showcase illumination device that illuminates a product by combining two types of illumination light. The illuminating device is arranged at the front end of the shelf board, and is configured to illuminate a product displayed on the shelf board from below. Using a transparent product fall prevention guard plate as a light guide plate, the light from the LED light source arranged at the lower end is emitted from the upper end with the same orientation characteristics as the LED light source, and the reflection stuck on the front surface of the guard plate The sheet diffuses and reflects the light being guided toward the back side (that is, the product side) to make the illuminance uniform. By combining the light guide plate and the reflection sheet in this way, the entire illumination light is constituted by the illumination light emitted from the front end of the shelf board and the illumination light deflected to the product side by the reflection sheet.

  A lighting device for a bookshelf having two lighting functions has also been proposed. For example, the lighting device described in Patent Literature 3 is arranged on a shelf board located under the ceiling (that is, a gap with the ceiling), and the book placed on the ceiling, the floor surface in front of the shelf board, and the shelf board. It is a thin illuminating device capable of simultaneously illuminating and the like. When the light emitted from the thin fluorescent tube is incident on the light guide plate that is arranged horizontally with respect to the ceiling, the white reflection sheet placed on the ceiling side surface of the light guide plate out of the light that travels while being totally reflected in the light guide plate. Light deviating from the total reflection angle is emitted from the lower surface of the light guide plate to illuminate the floor surface. Further, the upper end of the light guide plate has a wedge shape whose upper surface is inclined, and the reflected light on the inclined surface is emitted from the lower surface to illuminate the object on the shelf plate, and the refracted light on the inclined surface illuminates the ceiling.

JP 2010-88596 A JP 2010-82115 A JP 2002-42508 A

  However, there are various problems with the illumination devices that have been proposed in the past. For example, in the illuminating device described in Patent Document 1, the LED light source is disposed between the shade and the reflecting plate, and the reflecting surface is inclined, so that the lighting unit disposed on the rear surface of the shade can be thinned. There is a problem that it is difficult. In addition, since the LED light source is arranged near the lower end of the shade, there is a problem that it is difficult to efficiently dissipate heat from the LED substrate serving as a heat source, and the holding mechanism, wiring, etc. are likely to be complicated, which increases the cost. There is a problem of becoming. Furthermore, since the product on the shelf is illuminated using the orientation of the light emitted from the LED light source as it is, only the uppermost stage near the LED light source is illuminated brightly, and the illuminance rapidly increases as it goes to the lower shelf. There is also the problem of falling.

  The showcase described in Patent Document 2 uses a merchandise fall prevention guard provided at the front end of a merchandise shelf as a light guide plate, guides light from an LED light source arranged at the lower end of the guard, and is arranged on the shelf board. It illuminates the face of the product from below, and it is difficult to provide light distribution characteristics for efficiently illuminating the shade and the product shelf.

  The illuminating device described in Patent Document 3 is an illuminating device for illuminating three surfaces of the front horizontal surface of the shelf, the vertical surface of the shelf, and the ceiling surface, and the distance from the illumination target surface as compared with the size of the illumination optical system. However, it is difficult to satisfactorily illuminate an object to be illuminated, that is, a product on an electric lighting plate or a shelf as in a showcase.

  The present invention has been made in view of such a situation, and an object of the present invention is to uniformly illuminate a translucent shade located at the front from the back and efficiently illuminate an illumination object located below. Another object of the present invention is to provide a thin lighting device that can be used and a showcase using the same.

  In order to achieve the above object, a lighting device according to a first aspect of the present invention is a lighting device that performs backlight illumination on a shade having a transmission diffusion characteristic located in front and performs illumination on an illumination object located below. A translucent light guide plate that guides incident light from the upper end surface to the lower exit surface by reflection on the front surface on the side facing the shade and the rear surface on the back side, and along the longitudinal direction of the upper end surface A plurality of LED light sources that are arranged in a discrete manner and emit light incident on the upper end surface, and a diffusion pattern that diffuses incident light on at least one of the front surface and the rear surface Is provided, and the shade is illuminated with light diffused by the diffusion pattern, and the illumination object is illuminated with light emitted from a lower exit surface of the light guide plate.

  In the illumination device according to a second aspect of the present invention, in the first aspect of the invention, as the lower exit surface of the light guide plate is directed downward, the thickness of the light guide plate decreases from the back side toward the front side. It is characterized by including an inclined slope.

  The illumination device according to a third aspect is characterized in that, in the second aspect, an inclination angle θ of the slope with respect to the back surface satisfies the formula: θ <30 °.

  In the illumination device according to a fourth aspect, in the second or third aspect, the front surface of the light guide plate includes a diffusion surface in at least a part of a region facing the inclined surface through the medium of the light guide plate. It is characterized by.

  In the lighting device according to a fifth aspect of the present invention, in any one of the first to fourth aspects, the area of the diffusion portion of the diffusion pattern increases as the distance from the LED light source increases.

  A lighting device of a sixth invention according to any one of the first to fifth inventions, further comprising: a reflecting member that reflects light toward the inside of the light guide plate at a lower portion of the front surface of the light guide plate. And

  The lighting device according to a seventh aspect is characterized in that, in the sixth aspect, the reflecting member diffuses and reflects light toward the light guide plate.

  The lighting device according to an eighth aspect of the present invention is the lighting device according to the sixth or seventh aspect, wherein the reflecting member is integrally attached to the light guide plate without interposing an air layer between the light guide plate. It is characterized by that.

  A lighting device according to a ninth invention is characterized in that, in any one of the first to eighth inventions, the LED light source has light emission peaks discretely at a plurality of visible light wavelengths.

  A lighting device according to a tenth aspect of the present invention is the lighting device according to any one of the first to ninth aspects, wherein light emitted from the back surface of the light guide plate is reflected toward the light guide plate in the vicinity of the back surface of the light guide plate. It has a back plate.

  In an illuminating device according to an eleventh aspect of the invention, in the tenth aspect of the invention, the back plate diffusely reflects light emitted from the back surface of the light guide plate.

  A lighting device according to a twelfth aspect of the present invention is the light guide plate according to any one of the first to eleventh aspects, wherein each light beam emitted from the LED light source is transmitted from the LED light source to an upper end surface of the light guide plate. A shaping optical element that leads to the upper end surface of the LED, and the shaping optical element has a function of diffusing or diverging each light flux in the arrangement direction of the LED light sources, and a direction perpendicular to the arrangement direction of the LED light sources. It has at least one of the function which condenses a light beam, It is characterized by the above-mentioned.

  A lighting device according to a thirteenth invention is characterized in that, in any one of the first to twelfth inventions, left and right end faces of the light guide plate have a reflecting function.

  A lighting device according to a fourteenth aspect of the present invention is the lighting device according to any one of the first to thirteenth aspects, wherein the shade is provided on an upper front surface of a showcase body, and a shelf board on which merchandise as the lighting object is displayed. An illumination device used for a showcase provided inside a case body, wherein the shade is illuminated with light diffused by the diffusion pattern, and the product is illuminated with light emitted from a lower exit surface of the light guide plate. It is characterized by that.

  According to a fifteenth aspect of the present invention, there is provided a showcase including the illumination device according to the fourteenth aspect.

  According to the present invention, since the diffusion pattern for diffusing the incident light is provided on at least one of the front surface and the back surface that reflects on the light guide plate, the translucent shade located in front is provided. Can be illuminated uniformly from the back. At the same time, it is possible to efficiently illuminate the illumination object positioned below with the light emitted from the lower exit surface of the light guide plate. Accordingly, it is possible to realize a lighting device and a showcase using the same that are thin and capable of performing uniform backlight illumination on a shade located in front and efficient illumination on an illumination object located below. Can do.

The perspective view which shows the external appearance of one embodiment of a showcase. Sectional drawing which shows the internal structure of the showcase of FIG. Sectional drawing which shows 1st Embodiment of an illuminating device. The figure which shows the principal part of 1st Embodiment in the state seen from the back side of the light-guide plate. Sectional drawing which shows 2nd Embodiment of an illuminating device. The figure shown in the state which looked at the principal part of 2nd Embodiment from the back side of the light-guide plate. Sectional drawing which shows 3rd Embodiment of an illuminating device. Sectional drawing which shows 4th Embodiment of an illuminating device. The optical path figure of 1st Embodiment of an illuminating device. The optical path figure of 2nd Embodiment of an illuminating device. The optical path figure of 3rd Embodiment of an illuminating device. The optical path figure of 4th Embodiment of an illuminating device. Sectional drawing for demonstrating generation | occurrence | production of the illumination intensity nonuniformity in the light-guide plate lower part. Sectional drawing which shows the specific example of the front side lower part structure of a light-guide plate. Sectional drawing which shows the optical path etc. in the front side lower part structure of the light-guide plate of FIG. 14 (A). Sectional drawing which shows the optical path etc. in the front side lower part structure of the light-guide plate of FIG.14 (B). Sectional drawing which shows an example of the fixation structure of a light-guide plate and a backplate. The principal part sectional drawing which shows the specific example of the fixing structure of a light-guide plate and a backplate.

  Embodiments of a lighting device and a showcase according to the present invention will be described below with reference to the drawings. In addition, the same code | symbol is mutually attached | subjected to the part which is the same in each embodiment etc., and the corresponding part, and duplication description is abbreviate | omitted suitably.

<< Embodiment of the showcase (FIGS. 1 and 2) >>
FIG. 1 shows the appearance of the showcase 1, and FIG. 2 shows the internal structure of the showcase 1. This showcase 1 is a vertical open showcase installed in a convenience store or a supermarket store, and includes an illumination unit (lighting device) 2 and a shade (for example, a nameplate on which a product name is written). Plate) 3, shelf board 4, exterior (part of the showcase body) 5, heat insulation roll curtain 6 and the like. In addition, although this showcase 1 assumes the open showcase for shops, the use of the lighting unit 2 is not restricted to the showcase 1. For example, a show window, a bookshelf, and the like can have the same configuration as the show case 1 by using the lighting unit 2.

  The showcase body has a substantially U-shaped cross-section (FIG. 2) and a heat-insulating exterior 5 that opens to the front surface, and heat-insulating side plates (not shown) arranged on the left and right. A plurality of shelf boards 4 are installed at predetermined intervals inside the showcase body, and as shown in FIG. 2, products 9 as illumination objects are displayed on each shelf board 4. A translucent shade 3 made of a translucent diffusion plate is disposed on the upper front surface of the showcase body. On the back side of the shade 3, an illumination unit 2 for illuminating the product 9 on the shelf 4 at the same time as illuminating the shade 3 from the back side is arranged. Furthermore, a heat-insulating roll curtain 6 is housed on the back side of the lighting unit 2.

  The illumination unit 2 performs backlight illumination on the shade 3 located in front and illumination on the product 9 on the shelf 4 located below. Since the single lighting unit 2 can illuminate the shade 9 and the products 9 on all the shelf boards 4, it is possible to simplify the wiring for lighting and reduce the cost. The lighting unit 2 includes an LED light source 21 and an LED substrate 22 described later (FIG. 3 and the like). The LED substrate 22 or the like serves as a heat source, but since it is disposed at the top of the showcase 1, heat dissipation is easy and the influence of heat on the product 9 can be most effectively suppressed.

  Since the illumination unit 2 has a thin structure using a light guide plate 23 (FIG. 3 or the like), which will be described later, the space behind the shade 3 can be used effectively. For example, as shown in FIG. 2, it is easy to secure a space for storing the heat insulating roll curtain 6. In a general showcase with a cooling function, in order to increase cooling efficiency and save power, the inside and outside of the showcase are insulated by a heat insulating curtain when the store is closed. When the curtain for heat insulation is not used, it is wound and stored in a roll shape on the back surface of the shade, so that it is necessary to secure a space for arranging the heat insulation curtain on the back of the lighting unit. In the showcase 1 shown in FIG. 2, the use of a thin lighting unit 2 facilitates securing a storage space for the roll curtain 6.

<< 1st Embodiment of an illuminating device (FIG. 3, FIG. 4, FIG. 9) >>
FIG. 3 shows the internal structure of the illumination unit 2A, and FIG. 4 shows the main part of the illumination unit 2A as viewed from the back side of the light guide plate 23. FIG. 9 shows an optical path formed by the illumination unit 2A. The lighting unit 2A, which is the first embodiment of the lighting device, is a lighting device that performs backlight illumination on the translucent shade 3 positioned in front and performs illumination on the product 9 (FIG. 2) positioned below. And includes a plurality of LED light sources 21, an LED substrate 22, a translucent light guide plate 23, a unit holding member 24, a reflection plate (reflection member) 25, and the like.

  The shade 3 disposed on the upper front surface of the exterior 5 (FIGS. 1 and 2) is fixed to a shade frame 31 as shown in FIG. On the back side of the shade 3, a thin plate-shaped light guide plate 23 made of a translucent material having substantially the same area as the shade 3 is disposed. The light guide plate 23 can be produced by molding a resin material such as acrylic. The front surface 23b on the side facing the shade 3 and the back surface 23c on the back side thereof are parallel to each other, and a diffusion pattern for diffusing incident light is provided on the back surface 23c of the light guide plate 23. The diffusion pattern is composed of a large number of dot-like diffusion dots 26 (FIG. 4), and is regularly arranged on the back surface 23c of the light guide plate. Note that the diffusion pattern is not limited to a dot shape, and may be a lattice shape, for example, as long as the diffusion portion and the non-diffusion portion (mirror surface) are mixed substantially uniformly, and may not be regularly arranged. Good. That is, when an arbitrary region of the back surface 23c is cut out, the diffusion portion and the non-diffusion portion may be in a substantially constant ratio. In addition, a rectangular lower surface (lower emission surface) 23d is inclined with respect to the front surface 23b and the back surface 23c so that the lower portion of the light guide plate 23 becomes thinner downward from the back surface to the front surface. A reflection plate 25 that diffuses and reflects light toward the inside of the light guide plate 23 is provided below the front surface 23b having the wedge shape.

  A metal unit holding member 24 is fixed to the inner surface of the exterior 5 on its upper surface. The unit holding member 24 has a back plate 24a that diffuses and reflects the light emitted from the back surface 23c of the light guide plate 23 (for example, scattered light from the diffusion dots 26) toward the back surface 23c in the vicinity of the back surface 23c of the light guide plate 23. As part of it. The light guide plate 23 is fixed to the back plate 24a with a screw (not shown) via a spacing washer. By using a black screw or an opaque white screw for fixing the light guide plate 23, light is scattered at the screw portion. The secondary light source is not used.

  Above the upper end surface (incident side end surface) 23a of the light guide plate 23, a plurality of LED light sources 21 (FIG. 4) are provided along the longitudinal direction of the rectangular upper end surface 23a (that is, the width direction of the showcase 1). Discrete and arranged in a row. The LED light source 21 is electrically connected and fixed on the LED substrate 22, and the LED substrate 22 is fixed to the substrate fixing surface 24 c of the unit holding member 24. By using the metal unit holding member 24, the heat accumulated in the LED substrate 22 can be efficiently radiated, and the LED substrate 22 can be prevented from reaching a high temperature. If the LED substrate 22 or the LED light source 21 itself becomes hot, the light emission efficiency is lowered or the life of the LED is shortened. Therefore, it is important to efficiently dissipate heat. Note that more efficient heat dissipation can be achieved by sandwiching a heat dissipation sheet or heat dissipation grease between the LED substrate 22 and the unit holding member 24.

  The light emitted from the LED light source 21 enters the light guide plate 23 from the upper end surface 23a. However, since the emission angle of the LED is wide, the light beams before and after not hitting the upper end surface 23a of the light guide plate 23 become unnecessary light. When the light emitted to the front side of the light guide plate 23 directly hits the shade 3, it becomes a strong bright line or bright spot on the shade 3, and becomes a factor of degrading the quality of the shade 3. In order to avoid this, an unnecessary light shielding surface 24d is provided on the front side portion of the unit holding member 24 so as to shield the light from directly hitting the shade 3. Further, the light emitted from the back surface 23 c of the light guide plate 23 may be reflected by the unit holding member 24 and then transmitted through the light guide plate 23 to directly illuminate the shade 3. In order to avoid this, the unnecessary light reflecting surface 24b is formed by giving an inclination to the upper part of the back plate 24a of the unit holding member 24, and reflected to the LED light source 21 side.

  The light incident on the light guide plate 23 from the upper end surface 23a is guided to the lower exit surface 23d while being totally reflected by the front surface 23b on the side facing the shade 3 and the back surface (diffusion dot arrangement surface) 23c on the back side. (See the optical path diagram in FIG. 9). And the light inject | emitted from the lower output surface 23d illuminates the goods 9 on the shelf board 4 (FIG. 2). On the rear surface 23c of the light guide plate 23, a plurality of circular and uniform diffusing dots 26 are regularly printed at regular intervals. Therefore, of the light being guided, the light incident on the diffusion dot 26 is diffused on the spot, and is emitted before and after the light guide plate 23 when the total reflection condition is not satisfied. The light emitted to the front side of the light guide plate 23 directly illuminates the shade 3 from the back side, and the light emitted to the back side of the light guide plate 23 is a back plate 24a having a diffuse reflection characteristic (for example, diffusing made of matte white paint). After being reflected by the reflecting surface and transmitted through the light guide plate 23, the shade 3 is illuminated from the back.

  The diffusion dots 26 (FIG. 4) can be produced by printing on the surface of the light guide plate 23 using ink having diffusion characteristics. It is also possible to form diffusion dots (that is, surface-shaped dots composed of fine irregularities that deviate from the total reflection condition) on the plane of the mold and simultaneously form the diffusion dots 26 when the light guide plate 23 is molded. is there. The shape of the diffusion dot 26 is not limited to a circle. However, the circular diffusion dot 26 is preferable because it can be easily formed and an edge is not easily generated in the diffused light.

  The size of the diffusion dots 26 is uniform over the entire surface. The diameter of the diffusion dot 26 is determined so that the diffusion area with respect to the area of the back surface 23c of the light guide plate 23 is about 30%. Specifically, the dot pitch is 1.6 mm, the dot interval is 0.6 mm, and the diameter of the diffusion dots 26 is 1.0 mm. The amount of light guided through the light guide plate 23 becomes smaller as it goes below the light guide plate 23. However, when the area ratio of the diffusing dots 26 (that is, the ratio of the area occupied by the diffusing dots 26 on the diffusing dot arrangement surface) is small, even if the diffusing dot size is made uniform, the amount of decrease is the upper side and lower side of the shade 3 The illuminance is not so different. In this embodiment, the decrease in illuminance on the upper and lower sides of the shade 3 is about 15%. As described above, when the decrease in illuminance can be suppressed, it is preferable to make the dot size uniform because the diffusion dots 26 can be produced at a low cost.

  The diffusion dot 26 removes a part of the light guided downward while being totally reflected in the light guide plate 23 from the total reflection condition by diffusion, and from the back surface (diffusion dot arrangement surface) 23c to the outside of the light guide plate 23. It is something to take out. By using the diffusing dots 26 as reflecting means for obtaining diffused light, the reflectance and luminance distribution can be controlled in detail by the dot size distribution. For this purpose, the area ratio of the diffusion dots 26 at each position from the LED light source 21 on the diffusion dot arrangement surface 23c is important, and the area ratio is determined by specifications such as shade illuminance and shelf illuminance. Further, in order to make the illuminance on the shade 3 more uniform, it is necessary to increase the area ratio of the diffusion dots as the distance from the LED light source 21 increases. For example, if the dot pitch is uniform, the dot diameter is preferably increased as the distance from the LED light source 21 increases, and if the dot size is uniform, the dot pitch is preferably decreased as the distance from the LED light source 21 is increased. . Note that the diffusing dots 26 may be formed on the front surface 23b.

  Regarding the dot size, it is necessary to reduce the size of the diffusion dot 26 to such an extent that it is not observed as illuminance unevenness on the shade 3. Specifically, if the diameter of the diffusion dot 26 is set to 1/5 or less of the distance from the diffusion dot arrangement surface 23c to the shade 3, unevenness in illuminance due to the diffusion dot 26 can be suppressed to a level where there is no problem. Further, in order to make the illuminance on the shade 3 more uniform, it is preferable to increase the distance from the diffusion dot 26 serving as the secondary light source to the shade 3. Further, it is preferable that the diffusing dots are arranged at a position shorter than the length of the shade in the vertical direction. Therefore, it is preferable to arrange the diffusion dots 26 on the back surface 23c farther than the front surface 23b close to the shade 3 as in this embodiment. Moreover, since it is preferable that the thickness of the illumination unit 2A is thin (for example, 20 mm or less), in order to reduce the illuminance unevenness caused by the diffusion dots 26 on the shade 3, the diameter of the diffusion dots 26 is preferably 4 mm or less. . More preferably, the illuminance unevenness on the shade 3 can be substantially eliminated by setting the diameter of the diffusion dots 26 to 1 mm or less.

  The lower portion of the light guide plate 23 has a wedge shape with the back surface 23c side inclined so that the thickness of the light guide plate decreases toward the lower end. The light that has reached the lower exit surface 23d formed of the slope of the wedge is refracted and emitted to the outside of the light guide plate 23, and becomes illumination light for illuminating the product 9 on the shelf plate 4. Further, a reflecting plate 25 having a diffusion characteristic (for example, Ref White manufactured by Kimoto Co., Ltd.) is attached to the front surface 23b located in front of the lower emission surface 23d, and light totally reflected by the lower emission surface 23d. Is diffusely reflected by the reflector 25. The diffused light is transmitted through the light guide plate 23 from the front surface 23b toward the back surface 23c, emitted from the back surface 23c side, and mainly becomes illumination light for illuminating the product 9 on the upper shelf plate 4. The reflector 25 may be a matte white painted metal plate.

  By making the lower side of the light guide plate 23 into a wedge shape, it is possible to efficiently illuminate with good balance in the front-rear direction from the uppermost stage to the lowermost stage without illuminating light directed toward the shelf plate 4 being biased upward. If the shape is not wedge-shaped, the illumination light is distributed so as to diverge back and forth toward the lower side of the light guide plate 23, so that an orientation for efficiently illuminating the product 9 on the shelf plate 4 can be obtained. The lower portion of the light guide plate 23 is preferably wedge-shaped with the back surface 23c inclined.

  With respect to the wedge shape formed at the lower part of the light guide plate 23, when the inclination angle (that is, the wedge angle) of the lower exit surface 23d formed by the slope of the wedge with respect to the back surface 23c is defined as θ as shown in FIG. Conditional expression (1): It is desirable to satisfy θ <30 °. If the upper limit of conditional expression (1) is exceeded, the amount of light emitted toward the upper shelf 4 out of the amount of light refracted by the lower exit surface 23d and emitted toward the shelf 4 increases, so the lower shelf There is a possibility that the illuminance on the plate 4 becomes extremely dark.

  Conditional expression (1a): It is further desirable to satisfy 5 ° <θ <20 °. By setting 5 ° <θ, the amount of light emitted to the shelf plate 4 side can be further increased, so that the shelf plate 4 side can be illuminated more efficiently. Further, by setting θ <20 °, the amount of light emitted to the lower stage of the shelf board 4 can be increased, and therefore the shelf board 4 can be illuminated in a more balanced manner from the upper stage to the lower stage. In this lighting unit 2A, by setting θ = 15 °, it is possible to perform efficient and well-balanced illumination on each shelf board 4.

  By disposing the reflection plate 25 below the light guide plate 23, useless illumination light emitted forward from the front surface of the showcase 1 can be eliminated. For this reason, the light from the LED light source 21 can be efficiently guided to the shade 3 to be illuminated and the product 9 on the shelf board 4. If the reflecting plate 25 is not present, the light emitted toward the front illuminates the floor portion in front of the showcase 1. In general, since a store using a showcase has lighting on the ceiling or the like, light for illuminating the front floor surface from the showcase 1 is unnecessary. By reflecting the light to the shelf 4 side by the reflecting plate 25, the light from the LED light source 21 can be efficiently guided to the shade 3 to be efficiently illuminated and the product 9 on the shelf 4. It is possible to save power in case 1.

  Since the orientation center of the light diffusely reflected by the reflecting plate 25 is substantially equal to the regular reflection angle, most of the light is refracted by the wedge-shaped lower exit surface 23d to illuminate the lower shelf plate 4 and the diffused light. Of these, the light traveling upward illuminates the top shelf 4. Since not all the light diffusely reflected by the reflecting plate 25 illuminates the uppermost stage, the illumination balance does not deteriorate. The optical path diagram (FIG. 9) shows a state where the light emitted from the illumination unit 2 </ b> A is efficiently illuminated toward the shade 3 and the product 9 on the shelf board 4.

  The light guide plate 23 has a reflecting function on both left and right end surfaces (that is, both end surfaces in the width direction of the shelf plate 4 of the showcase 1). If the left and right end surfaces of the light guide plate 23 have a reflecting function, the light reaching the left and right ends of the light guide plate 23 can be returned into the light guide plate 23. Therefore, the product 9 on the shade 3 and the shelf board 4 can be more efficiently illuminated, and at the same time, the light emitted from both the left and right ends can be prevented from becoming unnecessary light.

<< Front lower structure of light guide plate (FIGS. 13 to 16) >>
As in the lighting unit 2A (FIGS. 3 and 9), in the lighting device having the light guide plate 23 having the lower exit surface 23d made of an inclined surface, the lower exit surface 23d made of an inclined surface has a slope and the reflection at the inclined surface portion. The angle of the emitted light becomes discrete due to the difference in the number of times. That is, unevenness occurs in the illuminance distribution of the emitted light within the cross section where the lower exit surface 23d is inclined. Further, in an illuminating device having an emission part composed of an inclined surface at the lower part of the light guide plate, if the emission angle at the emission surface is large (usually, light with an emission angle of 30 degrees or more is large), chromatic aberration is caused by dispersion of the light guide plate material. In other words, color unevenness occurs on the illumination object. By combining these phenomena, the illumination light is colored with the same period as the period of uneven illuminance. In particular, when the wavelength characteristics of the light source intensity have peaks at discrete wavelengths, the color unevenness of the illumination light becomes significant. For example, when a fluorescent-type white LED is used as a light source, since it has each wavelength peak of blue, which is excitation light, and yellow of a phosphor, color unevenness occurs on the illumination target.

  As described above, in the illumination device having the light emitting portion formed of the inclined surface at the lower portion of the light guide plate, for example, as shown in FIG. 13A, the front surface 23b is opposed to the lower light emission surface 23d through the medium of the light guide plate 23. Is substantially a mirror surface 23e, and when the reflecting plate 25 (the reflecting surface is a substantially mirror surface) located along the front surface 23b is disposed via the air layer 29, most of the illumination light is reflected by total reflection. Light is guided to the exit surface 23d. At this time, the emission angle of the emitted light becomes discrete due to the difference in the number of reflections in the light guide plate 23. Therefore, as shown in FIG. 13B, the illuminance unevenness described above is greatly generated in the illuminance distribution on the irradiated surface 28 at a position away from the emission surface.

  FIG. 13C schematically shows a difference in emission angle of illumination light having different wavelengths. As can be seen from FIG. 13C, when the exit angle (that is, the refraction angle) of the exit light at the lower exit surface 23d is large, the exit angle for each wavelength varies depending on the color dispersion of the light guide plate 23. Due to chromatic dispersion, the emission angle of short wavelength light (dashed line) is larger than that of long wavelength light (dashed line). Therefore, when the illumination light has a wavelength width, color unevenness also occurs with the period of unevenness in illuminance. In particular, when a light source having peaks at a plurality of discrete wavelengths, such as an LED light source, is used, the occurrence of color unevenness becomes significant.

  In order to suppress the occurrence of the illuminance unevenness, it is preferable that the front lower structure of the light guide plate has a function of diffusing and reflecting light toward the light guide plate. In order to give a diffuse reflection function to the front lower portion of the light guide plate, for example, as described above, the reflection plate 25 or the diffusion sheet having a diffuse reflection characteristic is provided on the front surface 23b of the portion located in front of the lower exit surface 23d, What is necessary is just to make the front lower part of the light-guide plate 23 into a diffuse reflection surface.

  14 (A), 14 (C) and 14 (D) show examples using the diffusion sheet 25s or the reflection plate 25 having the diffuse reflection characteristics, and FIG. 14 (B) shows the front surface 23b of the light guide plate 23. The example which made the lower part the diffuse reflection surface is shown. In the illuminating device shown in FIG. 14B, a diffusion surface 23f (for example, the front surface 23b of the light guide plate 23 is formed on at least a part of the region facing the inclined surface (lower emission surface 23d) through the medium of the light guide plate 23. Manufactured by molding). Since the diffusing surface 23f has a fine concavo-convex structure, diffuse reflection is possible by a combination of the diffusing function and the reflecting function of the reflector 25 (the same effect can be obtained when the diffusing surface 23f is mirror-coated). .) Therefore, the light diffused by the diffusing surface 23 f is reflected by the reflecting plate 25 and then reenters the light guide plate 23. As described above, the illuminance unevenness can be effectively improved by forming at least a part of the front surface 23b facing the slope as a diffuse reflection surface.

  In the lighting device shown in FIGS. 14A and 14C, the diffusion sheet 25 s that is a reflection member is integrally attached to the light guide plate 23 without interposing the air layer 29 between the light guide plate 23. In the lighting device shown in FIG. 14D, the reflecting plate 25 that is a reflecting member has an air layer between the light guiding plate 23 and the light guide plate 23. The light guide plate 23 is provided via 29. The diffusion sheet 25s shown in FIG. 14A includes a diffusion layer 25a containing a fine diffusion material that scatters light and a reflection layer 25b that reflects the scattered light. A diffusion sheet 25s shown in FIG. 14C has a diffusion surface 25f having a fine uneven structure and mirror-coated. The reflecting plate 25 shown in FIG. 14D has a diffusing surface 25f having a fine uneven structure and mirror-coated. As described above, by providing the reflecting member having the diffuse reflection characteristic, the illuminance unevenness can be effectively improved. Further, as shown in FIGS. 14A and 14C, the illuminance unevenness can be further effectively improved by integrating the reflecting member and the light guide 23 without the air layer 29 interposed therebetween. Can do.

  Employing each configuration shown in FIG. 14 makes it possible to effectively improve color unevenness when the LED light source has discrete emission peaks at a plurality of visible light wavelengths. Further, as described above, if there is no air layer 29 between the surface having the diffusion function and the light guide plate 23, it becomes possible to increase the diffusion effect, and therefore, the illuminance unevenness and the color unevenness can be reduced and further enhanced. High-quality lighting is possible. Furthermore, by arranging the range of the diffusing surface to be limited to the region almost opposite to the slope, in the region used as shade illumination, it becomes possible to accurately control the illuminance and illuminance distribution of the shade with the diffusion dots, It is also possible to limit the generation of unnecessary light.

  When the thickness of the light guide plate is t1, and the width of the diffusion surface from the lower end of the light guide plate is d (see FIG. 14), it is preferable that the conditional expression (2): 1 <d / t1 <3 is satisfied. It is more preferable to satisfy the conditional expression (1). For example, when θ = 15 °, it is preferable that d = 15 mm and t1 = 6 mm. If the lower limit of conditional expression (2) is not reached, the area of the diffusion region is too small, and it becomes difficult to sufficiently improve illuminance unevenness and color unevenness with respect to products on the shelf. Conversely, if the upper limit of conditional expression (2) is exceeded, the divergence angle of the lower emission light becomes too large, and it becomes difficult to effectively illuminate the object on the shelf. Moreover, there is a possibility that a lot of unnecessary light is generated, and there is a possibility that the illumination efficiency is lowered.

  FIG. 15A shows an optical path by the front lower structure of the light guide plate 23 shown in FIG. 14A, and FIG. In the structure shown in FIG. 15A, the light beam is diffusely reflected on the diffusion sheet 25s without being totally reflected on the surface of the light guide plate 23 in the portion of the diffusion sheet 25s bonded to the light guide plate 23 with the optical double-sided tape. To the lower exit surface 23d. The illumination light that has reached the lower exit surface 23d is diffused by the diffusion sheet 25s and emitted from the lower exit surface 23d at a random exit angle, so that the illuminance distribution on the irradiated surface 28 has almost no illuminance unevenness. Absent. Therefore, high-quality illumination without illuminance unevenness is realized, and color unevenness appearing in combination with the illuminance unevenness period is improved at the same time.

  The optical path by the front lower part structure of the light-guide plate 23 shown to FIG. 14 (B) is shown in FIG. The front surface 23b of the light guide plate has a diffusion surface 23f only on the part facing the lower exit surface 23d. The outside of the diffusing surface 23 f is covered with a substantially mirror surface of the reflecting plate 25 through the air layer 29. Therefore, as with the type shown in FIG. 15, it is possible to improve illuminance unevenness and color unevenness.

<< Fixing structure of light guide plate and back plate (FIGS. 17 and 18) >>
A refrigerated showcase is known which has a humidifying function or a mist-like shower function as a function for preventing the display product from drying. In such a showcase, since the lighting device is used under high humidity, if the distance between the light guide plate and the back plate is too narrow, moisture is filled between the light guide plate and the back plate due to capillary action. There is a risk that. When a moisture layer is formed between the light guide plate and the back plate, the light that should be totally reflected on the surface of the light guide plate is diffusely reflected on the surface of the back plate and emitted to the shade side. Since the light emitted to the shade side increases only in the portion where the water droplets are attached, luminance unevenness occurs on the shade. In addition, since the amount of light guided to the lower part of the light guide plate is reduced, the illumination light is darkened in the lower emission light.

  In order to prevent the formation of the moisture layer, it is desirable to appropriately set the distance from the light guide plate to the back plate. For example, when the distance between the light guide plate and the back plate is t2 (mm) (see FIGS. 3 and 17), it is preferable that the conditional expression (3): 0.1 <t2 <2 is satisfied. If the lower limit of conditional expression (3) is not reached, it will be difficult to reliably secure an air layer between the light guide plate and the back plate, resulting in uneven brightness in the shade or darkening of the lower illumination. There is a risk. On the other hand, if the upper limit of conditional expression (3) is exceeded, the distance between the light guide plate and the back plate becomes too wide, and the optical unit becomes too thick. In addition, the light emitted to the back side due to the diffusion pattern on the back side of the light guide plate may become leakage light to the side other than the shade side, which may reduce the illumination efficiency.

  As shown in FIG. 17, when fixing spot holes 34 are provided in the illumination effective area of the light guide plate 23 and the light guide plate 23 is fixed to the back plate 24a with screws 33 (fixing members), the inside of the light guide plate 23 is formed. As shown in FIG. 18C, when the light to be guided is emitted from the side surface Q of the counterbore 34, the side surface Q of the counterbore 34 becomes a secondary light source, and thus the shade is on the shade. May cause bright spots (illuminance unevenness). In addition, when the transmittance of the fixing member such as the screw 33 is high, the fixing member itself becomes a secondary light source, and there is a possibility that bright spots (illuminance unevenness) occur on the shade. In addition to uneven illumination, if the material of the screw (fixing member) is different from the color of the illumination light, the screw may become a secondary light source and color unevenness may occur.

  In order to suppress the occurrence of the illuminance unevenness, it is preferable to devise screw holes when screws are fixed within the illumination effective area of the light guide plate. For example, as shown in FIG. 18A, a fixing counterbore 34 is provided in the illumination effective area of the light guide plate 23, and the surface of a fixing member / fixing part such as a screw 33 (for example, the surface of the screw head 33a). ) Or substantially the same surface as the surface of the light guide plate 23, or the surface of the fixing member / fixed component protrudes from the surface of the light guide plate 23 as shown in FIGS. 17 and 18B. Is preferred. If the surface of the fixing member / fixing part is made substantially the same as the surface of the light guide plate or protrudes from the surface of the light guide plate, the light emitted from the side surface Q of the counterbore hole 34 is blocked by the head of the screw 33. It is possible to prevent bright spots from occurring on the surface.

  Further, it is desirable to use a material having a low visible light transmittance or a material having a high visible light absorption rate as the material of the fixing member / fixing part such as the screw 33. For example, it is desirable to use a screw 33 made of a material having a low visible light transmittance such as a metal material or a black screw 33. If such a fixing member / fixing part is used, it is possible to prevent illuminance unevenness due to the fact that it itself becomes a secondary light source. Further, when the resin screw is used, if the color is white (for example, light green or light yellow) different from the white of the illumination light, color unevenness due to the screw may occur on the shade. Therefore, color unevenness can be improved by using a metal screw (plating screw) or a black screw with little wavelength dependency in reflection characteristics.

  The width or diameter of the fixing member / fixing part (for example, the outer diameter of the screw head 33a) is w, the distance between the surface of the light guide plate 23 or the tip of the fixing member / fixing part (for example, the tip of the screw head 33a) and the shade 3. Is t3 (see FIGS. 17 and 18), it is desirable that conditional expression (4): w / t3 <3 is satisfied. When the width or diameter w of the fixing member / fixing part exceeds the upper limit of the conditional expression (4) as compared with the distance t3 between the light guide plate 23 and the like and the shade 3, the fixing member / fixing part becomes a shade and the shade 3 May cause uneven illumination.

<< 2nd Embodiment of an illuminating device (FIG. 5, FIG. 6, FIG. 10) >>
FIG. 5 shows the internal structure of the illumination unit 2B, and FIG. 6 shows the main part of the illumination unit 2B as viewed from the back side of the light guide plate 23. FIG. 10 shows an optical path formed by the illumination unit 2B. The illumination unit 2B, which is the second embodiment of the illumination device, is an illumination device that performs backlight illumination on the translucent shade 3 located in front and illumination on the product 9 (FIG. 2) located below. There are a plurality of LED light sources 21, LED substrates 22, translucent light guide plate 23, unit holding member 24, and the like.

  The shade 3 disposed on the upper front surface of the exterior 5 (FIGS. 1 and 2) is fixed to a shade frame 31 as shown in FIG. On the back side of the shade 3, a thin plate-shaped light guide plate 23 made of a translucent material having substantially the same area as the shade 3 is disposed. The light guide plate 23 can be produced by molding a resin material such as acrylic. The front surface 23b on the side facing the shade 3 and the back surface 23c on the back side thereof are parallel to each other, and a plurality of diffusion dots 26 (FIG. 6) for diffusing incident light are provided on the back surface 23c of the light guide plate 23. Further, the rectangular lower exit surface 23d is inclined with respect to the front surface 23b and the back surface 23c so that the lower portion of the light guide plate 23 becomes thinner downward.

  A metal unit holding member 24 is fixed to the inner surface of the exterior 5 on its upper surface. The unit holding member 24 is disposed in the vicinity of the back surface 23c of the light guide plate 23, and reflects the light emitted from the back surface 23c of the light guide plate 23 (for example, scattered light from the diffusion dots 26) to the back surface 23c side by the mirror surface. As part of it. The light guide plate 23 is fixed to the back plate 24a with a screw (not shown) through a spacing washer. By using a black screw or a metal screw (plating screw) having less wavelength dependency in reflection characteristics, the light guide plate 23 is fixed. The light is scattered at the screw portion so that it does not become a secondary light source.

  Above the upper end surface (incident side end surface) 23a of the light guide plate 23, a plurality of LED light sources 21 (FIG. 6) are provided along the longitudinal direction of the rectangular upper end surface 23a (that is, the width direction of the showcase 1). Discrete and arranged in a row. The LED light source 21 is electrically connected and fixed on the LED substrate 22, and the LED substrate 22 is fixed to the substrate fixing surface 24 c of the unit holding member 24. By using the metal unit holding member 24, the heat accumulated in the LED substrate 22 can be efficiently radiated, and the LED substrate 22 can be prevented from reaching a high temperature. If the LED substrate 22 or the LED light source 21 itself becomes hot, the light emission efficiency is lowered or the life of the LED is shortened. Therefore, it is important to efficiently dissipate heat. Note that more efficient heat dissipation can be achieved by sandwiching a heat dissipation sheet or heat dissipation grease between the LED substrate 22 and the unit holding member 24.

  The light emitted from the LED light source 21 enters the light guide plate 23 from the upper end surface 23a. However, since the emission angle of the LED is wide, the light beams before and after not hitting the upper end surface 23a of the light guide plate 23 become unnecessary light. When the light emitted to the front side of the light guide plate 23 directly hits the shade 3, it becomes a strong bright line or bright spot on the shade 3, and becomes a factor of degrading the quality of the shade 3. In order to avoid this, an unnecessary light shielding surface 24d is provided on the front side portion of the unit holding member 24 so as to shield the light from directly hitting the shade 3. Further, the light emitted from the back surface 23 c of the light guide plate 23 may be reflected by the unit holding member 24 and then transmitted through the light guide plate 23 to directly illuminate the shade 3. In order to avoid this, the unnecessary light reflecting surface 24b is formed by giving an inclination to the upper part of the back plate 24a of the unit holding member 24, and reflected to the LED light source 21 side.

  On the upper end surface 23a of the light guide plate 23, a shaping optical element made of an anisotropic diffusion surface integrated with the upper end surface 23a is provided. The anisotropic diffusion surface is composed of a diffusion structure having diffusion characteristics only in the arrangement direction of the LED light sources 21 (for example, a line-like random structure perpendicular to the diffusion direction), and can be formed at the same time as the light guide plate 23 is molded. Is possible. By providing diffusion characteristics in the arrangement direction of the LED light sources 21, even if the interval between the LED light sources 21 is widened, the luminance unevenness of the shade 3 in the arrangement direction of the LED light sources 21 can be reduced.

  The light incident on the light guide plate 23 from the upper end surface 23a is guided to the lower exit surface 23d while being totally reflected by the front surface 23b on the side facing the shade 3 and the back surface (diffusion dot arrangement surface) 23c on the back side. (See the optical path diagram in FIG. 10). And the light inject | emitted from the lower output surface 23d illuminates the goods 9 on the shelf board 4 (FIG. 2). On the back surface 23c of the light guide plate 23, a plurality of circular diffusing dots 26 (the size of the diffusing dots 26 increases as they are positioned below) are regularly printed at regular intervals. Therefore, of the light being guided, the light incident on the diffusion dot 26 is diffused on the spot, and is emitted before and after the light guide plate 23 when the total reflection condition is not satisfied. The light emitted to the front side of the light guide plate 23 directly illuminates the shade 3 from the back side, and the light emitted to the back side of the light guide plate 23 is reflected by the back plate 24a (mirror reflection surface) having mirror reflection characteristics, After passing through the light guide plate 23, the shade 3 is illuminated from the back.

  When the back plate 24a is a diffusing surface as in the first embodiment, the illuminance unevenness on the shade 3 due to the diffusing dots 26 is reduced, but the illuminance is lower than that of the mirror surface. If the reflecting surface of the back plate 24a is a mirror surface as in this embodiment, the luminance in the direction of looking up the shade 3 from obliquely below can be increased. Therefore, when the shade 3 is arranged at a high position, the shade 3 can be effectively illuminated.

  The diffusion dots 26 (FIG. 6) can be produced by printing on the surface of the light guide plate 23 using ink having diffusion characteristics. It is also possible to form diffusion dots (that is, surface-shaped dots composed of fine irregularities that deviate from the total reflection condition) on the plane of the mold and simultaneously form the diffusion dots 26 when the light guide plate 23 is molded. is there. The shape of the diffusion dot 26 is not limited to a circle. However, the circular diffusion dot 26 is preferable because it can be easily formed and an edge is not easily generated in the diffused light.

  The diffusion dot 26 removes a part of the light guided downward while being totally reflected in the light guide plate 23 from the total reflection condition by diffusion, and from the back surface (diffusion dot arrangement surface) 23c to the outside of the light guide plate 23. It is something to take out. By using the diffusing dots 26 as reflecting means for obtaining diffused light, the reflectance and luminance distribution can be controlled in detail by the dot size distribution. For this purpose, the area ratio of the diffusion dots 26 at each position from the LED light source 21 on the diffusion dot arrangement surface 23c is important, and the area ratio is determined by specifications such as shade illuminance and shelf illuminance. Further, in order to make the illuminance on the shade 3 more uniform, it is necessary to increase the area ratio of the diffusion dots as the distance from the LED light source 21 increases. This is because the amount of light guided through the light guide plate 23 decreases as it goes below the light guide plate 23.

  When the dot pitch is made uniform, the dot diameter is preferably increased as the distance from the LED light source 21 is increased. When the dot size is made uniform, the dot pitch is preferably decreased as the distance from the LED light source 21 is increased. In this embodiment, the dot pitch of the diffusing dots 26 is uniform, but the diameter of the diffusing dots 26 becomes larger as it is positioned lower (that is, as it gets farther from the LED light source 21). By gradually changing the size of the diffusing dots 26 in this way, even when the amount of light decreases due to the diffusion of the diffusing dots 26 while light is being guided through the light guide plate 23, the uniformity of the illuminance with respect to the shade 3 in the vertical direction is increased. The shade 3 can be illuminated uniformly.

  Regarding the dot size, it is necessary to reduce the size of the diffusion dot 26 to such an extent that it is not observed as illuminance unevenness on the shade 3. Specifically, if the diameter of the diffusion dot 26 is set to 1/5 or less of the distance from the diffusion dot arrangement surface 23c to the shade 3, unevenness in illuminance due to the diffusion dot 26 can be suppressed to a level where there is no problem. Further, in order to make the illuminance on the shade 3 more uniform, it is preferable to increase the distance from the diffusion dot 26 serving as the secondary light source to the shade 3. Therefore, it is preferable to arrange the diffusion dots 26 on the back surface 23c farther than the front surface 23b close to the shade 3 as in this embodiment. Moreover, since it is preferable that the thickness of the illumination unit 2B is thin (for example, 20 mm or less), in order to reduce the illuminance unevenness caused by the diffusion dots 26 on the shade 3, the diameter of the diffusion dots 26 is preferably 4 mm or less. . More preferably, the illuminance unevenness on the shade 3 can be substantially eliminated by setting the diameter of the diffusion dots 26 to 1 mm or less.

  The lower portion of the light guide plate 23 has a wedge shape with the back surface 23c side inclined so that the thickness of the light guide plate decreases toward the lower end. The light that has reached the lower exit surface 23d formed of the slope of the wedge is refracted and emitted to the outside of the light guide plate 23, and becomes illumination light for illuminating the product 9 on the shelf plate 4. By making the lower side of the light guide plate 23 into a wedge shape, it is possible to efficiently illuminate with good balance in the front-rear direction from the uppermost stage to the lowermost stage without illuminating light directed toward the shelf plate 4 being biased upward. If the shape is not wedge-shaped, the illumination light is distributed so as to diverge back and forth toward the lower side of the light guide plate 23, so that an orientation for efficiently illuminating the product 9 on the shelf plate 4 can be obtained. The lower portion of the light guide plate 23 is preferably wedge-shaped with the back surface 23c inclined.

  Regarding the wedge shape formed at the lower part of the light guide plate 23, the inclination angle (that is, the wedge angle) θ of the lower exit surface 23d formed of the slope of the wedge with respect to the back surface 23c is, as described above, the conditional expression (1): It is desirable to satisfy θ <30 °, and it is more desirable to satisfy the conditional expression (1a): 5 ° <θ <20 °. By satisfying the conditional expression (1), it is possible to illuminate the shelf board 4 in a balanced manner from the upper stage to the lower stage. By satisfying the conditional expression (1a), the shelf board 4 side can be illuminated more efficiently. Is possible. In this illumination unit 2B, θ = 15 ° enables efficient and well-balanced illumination for each shelf plate 4.

  In this embodiment, the reflecting plate 25 (FIG. 3) is not disposed in front of the lower exit surface 23d. For this reason, illumination light is also emitted to the front lower side of the showcase 1 (FIG. 10). Compared with the first embodiment, the illuminance on the product 9 on the shelf 4 on the uppermost stage is low, but not only the product 9 but also the store that illuminates only the vicinity of the showcase 1 by dimming the in-store lighting. The feet can also be illuminated brightly.

  The light guide plate 23 has a reflecting function on both left and right end surfaces (that is, both end surfaces in the width direction of the shelf plate 4 of the showcase 1). If the left and right end surfaces of the light guide plate 23 have a reflecting function, the light reaching the left and right ends of the light guide plate 23 can be returned into the light guide plate 23. Therefore, the product 9 on the shade 3 and the shelf board 4 can be more efficiently illuminated, and at the same time, the light emitted from both the left and right ends can be prevented from becoming unnecessary light. Moreover, the space | interval of the LED light source 21 can be expanded, and the number of LED can be reduced.

<< Third Embodiment of Lighting Device (FIGS. 7 and 11) >>
FIG. 7 shows an internal structure of the illumination unit 2C, and FIG. 11 shows an optical path formed by the illumination unit 2C. The lighting unit 2C, which is the third embodiment of the lighting device, is a lighting device that performs backlight illumination on the translucent shade 3 positioned in front and performs illumination on the product 9 (FIG. 2) positioned below. And includes a plurality of LED light sources 21, an LED substrate 22, a translucent light guide plate 23, a unit holding member 24, a reflection plate (reflection member) 25, and the like.

  The shade 3 arranged on the upper front surface of the exterior 5 (FIGS. 1 and 2) is fixed to a shade frame 31 as shown in FIG. On the back side of the shade 3, a thin plate-shaped light guide plate 23 made of a translucent material having substantially the same area as the shade 3 is disposed. The light guide plate 23 can be produced by molding a resin material such as acrylic. The light guide plate 23 is formed of a simple parallel plate, and the front surface 23b on the side facing the shade 3 and the back surface 23c on the back side thereof are parallel to each other. Similar to the first embodiment (FIG. 4), a plurality of diffusion dots 26 for diffusing incident light are provided on the front surface 23b of the light guide plate 23. A reflection plate 25 is provided for reflecting light on the mirror surface toward the inside of the light plate 23.

  Since a general showcase has a width of 1 m or more and a light guide plate to be used becomes large, polishing the glass plate into a wedge shape is a major factor in increasing the cost. However, if the light guide plate 23 is composed of parallel flat plates as in this embodiment, the cost can be reduced, and a glass plate that is resistant to heat and scratches and has no discoloration can be used. Moreover, when using resin materials, such as an acryl, since a board | plate material can be used, it can reduce cost.

  A metal unit holding member 24 is fixed to the inner surface of the exterior 5 on its upper surface. Since the unit holding member 24 has a U-shape with a simple cross section, the cost and thickness of the lighting unit 2C can be effectively reduced. The unit holding member 24 has a back plate 24a that diffuses and reflects the light emitted from the back surface 23c of the light guide plate 23 (for example, scattered light from the diffusion dots 26) toward the back surface 23c in the vicinity of the back surface 23c of the light guide plate 23. As part of it. A light guide plate 23 is fixed to the back plate 24a with a screw (not shown) through a spacing washer. By using a black screw or an opaque white screw for fixing the light guide plate 23, light is scattered at the screw portion. The secondary light source is not used.

  Similar to the first embodiment (FIG. 4), a plurality of LED light sources 21 are disposed above the upper end surface (incident side end surface) 23a of the light guide plate 23 in the longitudinal direction of the rectangular upper end surface 23a (that is, (In the width direction of the showcase 1) are arranged discretely and in a line. The LED light source 21 is electrically connected and fixed on the LED substrate 22, and the LED substrate 22 is fixed to the substrate fixing surface 24 c of the unit holding member 24. By using the metal unit holding member 24, the heat accumulated in the LED substrate 22 can be efficiently radiated, and the LED substrate 22 can be prevented from reaching a high temperature. If the LED substrate 22 or the LED light source 21 itself becomes hot, the light emission efficiency is lowered or the life of the LED is shortened. Therefore, it is important to efficiently dissipate heat. Note that more efficient heat dissipation can be achieved by sandwiching a heat dissipation sheet or heat dissipation grease between the LED substrate 22 and the unit holding member 24.

  The light emitted from the LED light source 21 enters the light guide plate 23 from the upper end surface 23a. However, since the emission angle of the LED is wide, the light beams before and after not hitting the upper end surface 23a of the light guide plate 23 become unnecessary light. When the light emitted to the front side of the light guide plate 23 directly hits the shade 3, it becomes a strong bright line or bright spot on the shade 3, and becomes a factor of degrading the quality of the shade 3. Further, the light emitted from the back surface 23 c of the light guide plate 23 may be reflected by the unit holding member 24 and then transmitted through the light guide plate 23 to directly illuminate the shade 3. In order to avoid these problems, an unnecessary light shielding surface 24d having a wide vertical width is provided on the front side portion of the unit holding member 24 so as to shield the light from directly hitting the shade 3. Further, the distance from the upper end of the shade 3 regulated by the shade frame 31 to the LED arrangement position is also increased, so that no light reaches the shade 3 after being reflected by the back plate 24a.

  The light incident on the light guide plate 23 from the upper end surface 23a is totally reflected by the front surface (diffusion dot arrangement surface) 23b on the side facing the shade 3 and the back surface 23c on the back side thereof, while the rectangular lower emission surface (emission side end surface) ) 23d (refer to the optical path diagram of FIG. 11). And the light inject | emitted from the lower output surface 23d illuminates the goods 9 on the shelf board 4 (FIG. 2). On the front surface 23b of the light guide plate 23, a plurality of circular diffusing dots 26 (the size of the diffusing dots 26 increases as they are positioned below) are regularly printed at regular intervals. Therefore, of the light being guided, the light incident on the diffusion dot 26 is diffused on the spot, and is emitted before and after the light guide plate 23 when the total reflection condition is not satisfied. The light emitted to the front side of the light guide plate 23 directly illuminates the shade 3 from the back side, and the light emitted to the back side of the light guide plate 23 is a back plate 24a having a diffuse reflection characteristic (for example, diffusing made of matte white paint). After being reflected by the reflecting surface and transmitted through the light guide plate 23, the shade 3 is illuminated from the back.

  Similar to the first embodiment, the diffusing dots 26 (FIG. 4) can be produced by printing on the surface of the light guide plate 23 using ink having diffusing characteristics. It is also possible to form diffusion dots (that is, surface-shaped dots composed of fine irregularities that deviate from the total reflection condition) on the plane of the mold and simultaneously form the diffusion dots 26 when the light guide plate 23 is molded. is there. The shape of the diffusion dot 26 is not limited to a circle. However, the circular diffusion dot 26 is preferable because it can be easily formed and an edge is not easily generated in the diffused light.

  The diffusion dot 26 removes a part of the light guided downward while being totally reflected in the light guide plate 23 from the total reflection condition by diffusion, and from the front surface (diffusion dot arrangement surface) 23b to the outside of the light guide plate 23. It is something to take out. By using the diffusing dots 26 as reflecting means for obtaining diffused light, the reflectance and luminance distribution can be controlled in detail by the dot size distribution. For this purpose, the area ratio of the diffusion dots 26 at each position from the LED light source 21 on the diffusion dot arrangement surface 23c is important, and the area ratio is determined by specifications such as shade illuminance and shelf illuminance. Further, in order to make the illuminance on the shade 3 more uniform, it is necessary to increase the area ratio of the diffusion dots as the distance from the LED light source 21 increases. This is because the amount of light guided through the light guide plate 23 decreases as it goes below the light guide plate 23.

  When the dot pitch is made uniform, the dot diameter is preferably increased as the distance from the LED light source 21 is increased. When the dot size is made uniform, the dot pitch is preferably decreased as the distance from the LED light source 21 is increased. In this embodiment, the dot pitch of the diffusing dots 26 is uniform, but the diameter of the diffusing dots 26 becomes larger as it is positioned lower (that is, as it gets farther from the LED light source 21). By gradually changing the size of the diffusing dots 26 in this way, even when the amount of light decreases due to the diffusion of the diffusing dots 26 while light is being guided through the light guide plate 23, the uniformity of the illuminance with respect to the shade 3 in the vertical direction is increased. The shade 3 can be illuminated uniformly.

  Regarding the dot size, it is necessary to reduce the size of the diffusion dot 26 to such an extent that it is not observed as illuminance unevenness on the shade 3. Specifically, if the diameter of the diffusion dot 26 is set to 1/5 or less of the distance from the diffusion dot arrangement surface 23c to the shade 3, unevenness in illuminance due to the diffusion dot 26 can be suppressed to a level where there is no problem. Further, in order to make the illuminance on the shade 3 more uniform, it is preferable to increase the distance from the diffusion dot 26 serving as the secondary light source to the shade 3. Moreover, since it is preferable that the thickness of the illumination unit 2C is thin (for example, 20 mm or less), in order to reduce unevenness in illuminance caused by the diffusion dots 26 on the shade 3, the diameter of the diffusion dots 26 is preferably 4 mm or less. . More preferably, the illuminance unevenness on the shade 3 can be substantially eliminated by setting the diameter of the diffusion dots 26 to 1 mm or less.

  The light guide plate 23 used in this embodiment is composed of parallel flat plates as described above. When the light guide plate 23 made of a parallel plate is used, light is emitted from the lower exit surface 23b of the light guide plate 23 symmetrically in the front-rear direction and the emission angle in the front-rear direction is increased, so that the product can be efficiently illuminated. It becomes difficult. Therefore, in this embodiment, in order to efficiently illuminate the product 9 on the shelf plate 4, a reflection plate 25 (mirror reflection surface) having mirror reflection characteristics is attached to the front surface 23b below the light guide plate 23. ing. By using a mirror as the reflecting plate 25, it is possible to suppress the generation of light that illuminates the upper side of the uppermost shelf 4 without necessity.

  The light guide plate 23 has a reflecting function on both left and right end surfaces (that is, both end surfaces in the width direction of the shelf plate 4 of the showcase 1). If the left and right end surfaces of the light guide plate 23 have a reflecting function, the light reaching the left and right ends of the light guide plate 23 can be returned into the light guide plate 23. Therefore, the product 9 on the shade 3 and the shelf board 4 can be more efficiently illuminated, and at the same time, the light emitted from both the left and right ends can be prevented from becoming unnecessary light.

<< 4th Embodiment of an illuminating device (FIG. 8, FIG. 12) >>
FIG. 8 shows an internal structure of the illumination unit 2D, and FIG. 12 shows an optical path formed by the illumination unit 2D. The illumination unit 2D, which is the fourth embodiment of the illumination device, is an illumination device that performs backlight illumination on the translucent shade 3 positioned in front and performs illumination on the product 9 (FIG. 2) positioned below. There are a plurality of LED light sources 21, LED substrates 22, translucent light guide plate 23, unit holding member 24, and the like.

  The shade 3 arranged on the upper front surface of the exterior 5 (FIGS. 1 and 2) is fixed to a shade frame 31 as shown in FIG. On the back side of the shade 3, a thin plate-shaped light guide plate 23 made of a translucent material having substantially the same area as the shade 3 is disposed. The light guide plate 23 can be produced by molding a resin material such as acrylic. The light guide plate 23 is formed of a simple parallel plate, and the front surface 23b on the side facing the shade 3 and the back surface 23c on the back side thereof are parallel to each other. Similar to the first embodiment (FIG. 4), a plurality of diffusing dots 26 for diffusing incident light are provided on the back surface 23c of the light guide plate 23.

  Since a general showcase has a width of 1 m or more and a light guide plate to be used becomes large, polishing the glass plate into a wedge shape is a major factor in increasing the cost. However, if the light guide plate 23 is composed of parallel flat plates as in this embodiment, the cost can be reduced, and a glass plate that is resistant to heat and scratches and has no discoloration can be used. Moreover, when using resin materials, such as an acryl, since a board | plate material can be used, it can reduce cost.

  A metal unit holding member 24 is fixed to the inner surface of the exterior 5 on its upper surface. Since the unit holding member 24 has a U-shape with a simple cross section, the cost and thickness of the lighting unit 2D can be effectively reduced. The unit holding member 24 has a back plate 24a that diffuses and reflects the light emitted from the back surface 23c of the light guide plate 23 (for example, scattered light from the diffusion dots 26) toward the back surface 23c in the vicinity of the back surface 23c of the light guide plate 23. As part of it. A light guide plate 23 is fixed to the back plate 24a with a screw (not shown) through a spacing washer. By using a black screw or an opaque white screw for fixing the light guide plate 23, light is scattered at the screw portion. The secondary light source is not used.

  Similar to the first embodiment (FIG. 4), a plurality of LED light sources 21 are disposed above the upper end surface (incident side end surface) 23a of the light guide plate 23 in the longitudinal direction of the rectangular upper end surface 23a (that is, (In the width direction of the showcase 1) are arranged discretely and in a line. The LED light source 21 is electrically connected and fixed on the LED substrate 22, and the LED substrate 22 is fixed to the substrate fixing surface 24 c of the unit holding member 24. By using the metal unit holding member 24, the heat accumulated in the LED substrate 22 can be efficiently radiated, and the LED substrate 22 can be prevented from reaching a high temperature. If the LED substrate 22 or the LED light source 21 itself becomes hot, the light emission efficiency is lowered or the life of the LED is shortened. Therefore, it is important to efficiently dissipate heat. Note that more efficient heat dissipation can be achieved by sandwiching a heat dissipation sheet or heat dissipation grease between the LED substrate 22 and the unit holding member 24.

  The light emitted from the LED light source 21 enters the light guide plate 23 from the upper end surface 23a. However, since the emission angle of the LED is wide, the light beams before and after not hitting the upper end surface 23a of the light guide plate 23 become unnecessary light. When the light emitted to the front side of the light guide plate 23 directly hits the shade 3, it becomes a strong bright line or bright spot on the shade 3, and becomes a factor of degrading the quality of the shade 3. Further, the light emitted from the back surface 23 c of the light guide plate 23 may be reflected by the unit holding member 24 and then transmitted through the light guide plate 23 to directly illuminate the shade 3. In order to avoid these problems, an unnecessary light shielding surface 24d having a wide vertical width is provided on the front side portion of the unit holding member 24 so as to shield the light from directly hitting the shade 3. Further, the distance from the upper end of the shade 3 regulated by the shade frame 31 to the LED arrangement position is also increased, so that no light reaches the shade 3 after being reflected by the back plate 24a.

  Between the LED light source 21 and the upper end surface 23a of the light guide plate 23, a concave meniscus cylindrical lens 27 is disposed on the LED light source 21 side as a shaping optical element for collecting light in the thickness direction of the light guide plate 23. . The meniscus cylindrical lens 27 can increase the light injection efficiency to the light guide plate 23 even when the LED light source 21 having a large angle orientation characteristic in the front-rear direction is used. Therefore, the light emitted from the LED light source 21 can be efficiently used as illumination light.

  The light incident on the light guide plate 23 from the upper end surface 23a is totally reflected by the front surface 23b on the side facing the shade 3 and the back surface (diffusion dot arrangement surface) 23c on the back side thereof, while being a rectangular lower emission surface (emission side end surface) ) 23d (refer to the optical path diagram of FIG. 12). And the light inject | emitted from the lower output surface 23d illuminates the goods 9 on the shelf board 4 (FIG. 2). On the rear surface 23c of the light guide plate 23, a plurality of circular and uniform diffusing dots 26 are regularly printed at regular intervals. Therefore, of the light being guided, the light incident on the diffusion dot 26 is diffused on the spot, and is emitted before and after the light guide plate 23 when the total reflection condition is not satisfied. The light emitted to the front side of the light guide plate 23 directly illuminates the shade 3 from the back side, and the light emitted to the back side of the light guide plate 23 is a back plate 24a having a diffuse reflection characteristic (for example, diffusing made of matte white paint). After being reflected by the reflecting surface and transmitted through the light guide plate 23, the shade 3 is illuminated from the back.

  Similar to the first embodiment, the diffusing dots 26 (FIG. 4) can be produced by printing on the surface of the light guide plate 23 using ink having diffusing characteristics. It is also possible to form diffusion dots (that is, surface-shaped dots composed of fine irregularities that deviate from the total reflection condition) on the plane of the mold and simultaneously form the diffusion dots 26 when the light guide plate 23 is molded. is there. The shape of the diffusion dot 26 is not limited to a circle. However, the circular diffusion dot 26 is preferable because it can be easily formed and an edge is not easily generated in the diffused light.

  The size of the diffusion dots 26 is uniform over the entire surface. The diameter of the diffusion dot 26 is determined so that the diffusion area with respect to the area of the back surface 23c of the light guide plate 23 is about 30%. Specifically, the dot pitch is 1.6 mm, the dot interval is 0.6 mm, and the diameter of the diffusion dots 26 is 1.0 mm. The amount of light guided through the light guide plate 23 becomes smaller as it goes below the light guide plate 23. However, when the area ratio of the diffusing dots 26 (that is, the ratio of the area occupied by the diffusing dots 26 on the diffusing dot arrangement surface) is small, even if the diffusing dot size is made uniform, the amount of decrease is the upper side and the lower side of the shade 3. The illuminance is not so different. In this embodiment, the decrease in illuminance on the upper and lower sides of the shade 3 is about 15%. As described above, when the decrease in illuminance can be suppressed, it is preferable to make the dot size uniform because the diffusion dots 26 can be produced at a low cost.

  The diffusion dot 26 removes a part of the light guided downward while being totally reflected in the light guide plate 23 from the total reflection condition by diffusion, and from the back surface (diffusion dot arrangement surface) 23c to the outside of the light guide plate 23. It is something to take out. By using the diffusing dots 26 as reflecting means for obtaining diffused light, the reflectance and luminance distribution can be controlled in detail by the dot size distribution. For this purpose, the area ratio of the diffusion dots 26 at each position from the LED light source 21 on the diffusion dot arrangement surface 23c is important, and the area ratio is determined by specifications such as shade illuminance and shelf illuminance. Further, in order to make the illuminance on the shade 3 more uniform, it is necessary to increase the area ratio of the diffusion dots as the distance from the LED light source 21 increases. For example, if the dot pitch is uniform, the dot diameter is preferably increased as the distance from the LED light source 21 increases, and if the dot size is uniform, the dot pitch is preferably decreased as the distance from the LED light source 21 is increased. .

  Regarding the dot size, it is necessary to reduce the size of the diffusion dot 26 to such an extent that it is not observed as illuminance unevenness on the shade 3. Specifically, if the diameter of the diffusion dot 26 is set to 1/5 or less of the distance from the diffusion dot arrangement surface 23c to the shade 3, unevenness in illuminance due to the diffusion dot 26 can be suppressed to a level where there is no problem. Further, in order to make the illuminance on the shade 3 more uniform, it is preferable to increase the distance from the diffusion dot 26 serving as the secondary light source to the shade 3. Therefore, it is preferable to arrange the diffusion dots 26 on the back surface 23c farther than the front surface 23b close to the shade 3 as in this embodiment. Since the illumination unit 2D is preferably thin (for example, 20 mm or less), in order to reduce unevenness in illuminance caused by the diffusion dots 26 on the shade 3, the diameter of the diffusion dots 26 is preferably 4 mm or less. . More preferably, the illuminance unevenness on the shade 3 can be substantially eliminated by setting the diameter of the diffusion dots 26 to 1 mm or less.

  In this embodiment, the reflector 25 (FIG. 7) is not disposed in front of the lower exit surface 23d. For this reason, illumination light is also emitted to the front lower side of the showcase 1 (FIG. 12). Compared with the third embodiment, the illuminance on the product 9 on the shelf 4 on the uppermost stage is small. However, in a store that illuminates only the vicinity of the showcase 1 by dimming the in-store lighting, not only the product 9 The feet can also be illuminated brightly.

  The light guide plate 23 has a reflecting function on both left and right end surfaces (that is, both end surfaces in the width direction of the shelf plate 4 of the showcase 1). If the left and right end surfaces of the light guide plate 23 have a reflecting function, the light reaching the left and right ends of the light guide plate 23 can be returned into the light guide plate 23. Therefore, the product 9 on the shade 3 and the shelf board 4 can be more efficiently illuminated, and at the same time, the light emitted from both the left and right ends can be prevented from becoming unnecessary light.

<< Characteristics etc. of Embodiment of Lighting Device >>
Table 1 below shows the characteristic points of the respective lighting units 2A to 2D. Further, as can be seen from the above description, each embodiment includes the following characteristic configurations (# 1) to (# 15).

  (# 1): A lighting device for performing backlight illumination on a shade having a transmission diffusion characteristic located in front and illuminating an illumination object located below, and a front surface on the side facing the shade and its A translucent light guide plate that guides incident light from the upper end surface to the lower exit surface by reflection on the back side of the back side, and discretely arranged along the longitudinal direction of the upper end surface, A plurality of LED light sources for emitting incident light, and a diffusion pattern for diffusing incident light is provided on at least one of the front surface and the back surface, and diffused by the diffusion pattern. The illumination device illuminates the shade with light and illuminates the illumination object with light emitted from a lower exit surface of the light guide plate.

  (# 2): The lower exit surface of the light guide plate includes a slope that is inclined so that the thickness of the light guide plate decreases from the back side toward the front side as it goes downward ( # 1) The lighting device described.

  (# 3): The illumination device according to (# 2), wherein an inclination angle θ of the slope with respect to the back surface satisfies the formula: θ <30 °.

  (# 4): (# 2) or (# 3), wherein the front surface of the light guide plate includes a diffusing surface in at least a part of a region facing the slope through the medium of the light guide plate Lighting equipment.

  (# 5): The illuminating device according to any one of (# 1) to (# 4), wherein an area of a diffusion portion of the diffusion pattern is increased as the distance from the LED light source is increased.

  (# 6): The reflector according to any one of (# 1) to (# 5), wherein a reflection member that reflects light toward the inside of the light guide plate is provided at a lower portion of the front surface of the light guide plate. Lighting equipment.

  (# 7): The illumination device according to (# 6), wherein the reflection member diffuses and reflects light toward the light guide plate.

  (# 8): The reflective member is integrally attached to the light guide plate without an air layer between the light guide plate (# 6) or (# 7) The lighting device described.

  (# 9): The illumination device according to any one of (# 1) to (# 8), wherein the LED light source has emission peaks discretely at a plurality of visible light wavelengths.

  (# 10): A back plate for reflecting light emitted from the back of the light guide plate toward the light guide plate is provided near the back of the light guide plate (# 1) to (# 9). The illumination device according to any one of the above.

  (# 11): The illumination device according to (# 10), wherein the back plate diffusely reflects the light emitted from the back surface of the light guide plate.

  (# 12): A shaping optical element that guides each light beam emitted from the LED light source to the upper end surface of the light guide plate is provided between the LED light source and the upper end surface of the light guide plate. The light source has at least one of a function of diffusing or diverging each light flux in the arrangement direction of the LED light sources and a function of condensing each light flux in a direction perpendicular to the arrangement direction of the LED light sources. The illumination device according to any one of (# 1) to (# 11).

  (# 13): The lighting device according to any one of (# 1) to (# 12), wherein both left and right end surfaces of the light guide plate have a reflecting function.

  (# 14): A lighting device for use in a showcase provided with the shade on the upper front surface of the showcase body, and provided with a shelf on the inside of the showcase body on which products as the lighting objects are displayed, Any one of (# 1) to (# 13), wherein the shade is illuminated with light diffused by the diffusion pattern and the product is illuminated with light emitted from a lower exit surface of the light guide plate. The lighting device according to item.

  (# 15): A showcase comprising the illumination device according to (# 14). That is, a showcase main body, a shade having transmission diffusion characteristics provided on the upper front surface of the showcase main body, a shelf plate provided inside the showcase main body for displaying products, and the front position A lighting device that performs backlight illumination on a shade and that also illuminates the product located below, wherein the illumination device has a front surface on the side facing the shade and a rear surface on the back side thereof. A light-transmitting light guide plate that guides incident light from the upper end surface to the lower exit surface by reflection at the light, and light that is discretely arranged along the longitudinal direction of the upper end surface and incident on the upper end surface A plurality of LED light sources, and a diffusion pattern for diffusing incident light is provided on at least one of the front surface and the back surface, and the diffusion While illuminating the shade light scattered in turn, showcase, characterized in that illuminating the product with light emitted from the lower exit surface of the light guide plate.

  According to the configuration (# 1), diffusion that diffuses incident light on at least one of the front and back surfaces that reflect on the light guide plate (that is, only the front surface, only the back surface, or both the front and back surfaces) Since the pattern (for example, a plurality of diffusion dots) is provided, a part of the light being guided is sequentially extracted with the diffusion dots, for example, and the shade with the transmission diffusion characteristic located in front is uniform from the back Can be illuminated. At the same time, it is possible to efficiently illuminate the illumination object positioned below with the light emitted from the lower exit surface of the light guide plate. Accordingly, it is possible to realize an illumination device that is thin and capable of performing backlight illumination on a shade located in front and illumination on an illumination object located below.

  For example, as shown in the configuration (# 14), the shade is provided on the upper front surface of the showcase main body, and the shelf that displays the product as the illumination object is provided in the showcase main body. If the illumination device of 1) is used to illuminate the shade with the light diffused by the diffusion pattern and illuminate the product with the light emitted from the lower exit surface of the light guide plate, the uniform backlight illumination of the shade and Lighting of the product shelf can be efficiently performed with one lighting device. With the configuration (# 15) provided with such an illumination device, a thin and energy-saving showcase (# 15) can be realized. Since the LED light source and the LED substrate serving as the heat source are located on the upper front surface of the showcase body, the heat source can be kept away from the product on the shelf board. In addition, heat dissipation from the top plate of the showcase body is facilitated, and wiring to the board and waterproof / moisture-proof treatment are also facilitated.

  Since the illuminance ratio between the shade and the product on the shelf can be controlled by, for example, the size and density of the diffusion dots, it is easy to set an arbitrary illuminance ratio. Therefore, the illuminance ratio can be easily set according to the installation position, usage method, etc. of the showcase. For example, by increasing the diffusion dot area ratio with respect to the total area of the back surface or the front surface of the light guide plate, it is possible to increase the light amount ratio of the illumination light that illuminates the shade out of the total illumination light. Conversely, by reducing the dot area ratio, the light quantity ratio of the shelf illumination can be increased. In order to increase the dot area ratio, the dot diameter may be increased when the dot pitch is constant. Further, when the dot diameter is constant, the dot pitch may be reduced. It is desirable to select the dot pitch and the dot diameter within a range in which the uneven distribution is not reflected on the shade.

  In the shape where the lower end of the light guide plate is just a chamfered flat plate, for example, not only the light emitted toward the front of the showcase increases, but also the light emitted toward the back side is centered on the top shelf There is a risk of illuminating. On the other hand, as shown in the configuration (# 2), the lower exit surface of the light guide plate has a shape (for example, a wedge shape) including an inclined surface that is inclined so as to become thinner from the back side to the front side as it goes downward. If it is (illumination unit 2A, 2B), it can illuminate efficiently not only to the top shelf board in a showcase but to the shelf board of a lower stage.

  As in the configuration (# 3), when the inclination angle θ with respect to the back surface of the inclined surface satisfies the formula: θ <30 °, the shelf board can be illuminated in a balanced manner from the upper stage to the lower stage.

  As in the configuration (# 4), when the front surface of the light guide plate includes a diffusion surface in at least a part of the region facing the slope through the medium of the light guide plate, uneven illuminance is effectively improved. It becomes possible.

  As in the configuration (# 5), when the area of the diffusion portion of the diffusion pattern is increased as the distance from the LED light source increases, the shade can be illuminated more uniformly. For example, if the area of the diffusing dots (the size of the diffusing dots, the density, etc.) is increased with increasing distance from the LED light source (illumination units 2B, 2C), Since the amount of light sequentially extracted by the diffusion dots can be kept constant, the shade can be illuminated more uniformly. In addition, it is preferable that a spreading | diffusion dot is 1/2 or less of the area of a dot arrangement | positioning surface (the front surface or back surface of a light-guide plate). Further, the diffusion dots may be formed by printing on the surface of the light guide plate, or may be formed by molding integrally with the light guide.

  As in the configuration (# 6), if a reflecting member is provided at the lower part of the front surface of the light guide plate (lighting units 2A and 2C), for example, useless light emitted toward the front of the showcase is emitted. It is possible to efficiently illuminate the product on the shelf board that is the object to be illuminated. If the reflecting member also has a diffusing function (illumination unit 2A) as in the configuration (# 7), a wider range of illumination is possible. In order to add a reflection function to the lower part of the front surface of the light guide plate, for example, a reflective sheet may be applied to the lower part of the front surface of the light guide plate. A reflective surface may be formed.

  The illuminance of the shelf and the illuminance in front of the showcase can be easily set according to the installation position, usage method, etc., depending on whether the lower end shape (# 2) of the light guide plate and the reflecting member (# 6, # 7) are present. . For example, if the store where the showcase is installed has sufficient illumination, only the shade and the interior of the showcase need be illuminated, so by providing a reflective surface at the lower end of the light guide plate (lighting units 2A and 2C) It is possible to efficiently illuminate the inside of the showcase by eliminating unnecessary light for illuminating the front floor portion of the case. On the other hand, when it is necessary to illuminate the front floor of the showcase (when the in-store lighting is dark, etc.), if a reflecting surface is not provided at the lower part of the light guide plate (illumination units 2B and 2D), not only the interior of the showcase The front floor of the showcase can also be illuminated.

  As in the configuration (# 8), when the reflecting member is integrally attached to the light guide plate without interposing an air layer between the light guide plate and the illuminance unevenness can be effectively improved. It becomes possible.

  As in the configuration (# 9), when the LED light source is configured to have emission peaks discretely at a plurality of visible light wavelengths, color unevenness can be effectively improved.

  The diffused light generated by the diffusing dots provided on the light guide plate is either light that diffuses to the shade side of the light guide plate, light that guides the light guide plate again, or light that diffuses to the back side of the light guide plate. If the back plate has a reflection function in the vicinity of the back of the light guide plate as in the configuration (# 10) (illumination units 2A to 2D), the light diffused on the back side of the light guide plate is efficiently diffused to the shade side. Can be used as illumination light. If the back plate also has a diffusion function (illumination units 2A, 2C, 2D) as in the configuration (# 11), the name plate on the shade can be observed brightly from a wider range. The back plate may be formed integrally with the holding member of the LED substrate. Moreover, it is preferable that the surface which connects the holding surface of a LED board and a backplate has an inclination which approaches the back surface of a light-guide plate toward a backplate from a holding surface. If comprised in this way, it can prevent that the reflected light in a holding member illuminates a shade directly, becomes a bright line, and generate | occur | produces a brightness nonuniformity.

  Since the LED light source to be used is a point light source, it is necessary to devise light for illuminating the thin light guide plate. If the function of diffusing or diverging each light beam in the arrangement direction of the LED light sources is added by a shaping optical element (anisotropic diffusion surface, negative power optical element, etc.) as in the configuration (# 12) (illumination unit 2B) The illuminance unevenness in the arrangement direction of the discretely arranged LEDs can be reduced. In order to add such a shaping optical element, for example, an anisotropic diffusion plate having a large diffusion angle is arranged in the LED arrangement direction between the LED light source and the upper end surface of the light guide plate, or on the upper end surface of the light guide plate. A diffusion surface having the same diffusion function is integrally molded, or a lens (for example, a cylindrical lens array) having negative optical power in the LED light source arrangement direction is inserted between the LED light source and the upper end surface of the light guide plate. You can do it.

  If a function of condensing each light beam in a direction perpendicular to the arrangement direction of the LED light sources (thickness direction of the light guide plate) is added by a shaping optical element (positive power optical element or the like) (illumination unit 2D), Even if the light guide plate is a thin plate, efficient light injection is possible. In order to add such a shaping optical element, for example, a lens having a positive optical power in a direction perpendicular to the arrangement direction of the LED light sources between the LED light source and the upper end surface of the light guide plate (for example, A cylindrical lens) may be inserted.

  If the left and right end faces of the light guide plate (for example, both end faces in the width direction of the showcase shelf) are provided with a reflecting function as in the configuration (# 13) (illumination units 2A to 2D), the left and right ends of the light guide plate The reached light can be returned into the light guide plate. Therefore, it is possible to more efficiently illuminate the shade and the object to be illuminated (such as a shelf-shaped product), and at the same time, it is possible to prevent the light emitted from the left and right ends from becoming unnecessary light.

1 Showcase 2, 2A, 2B, 2C, 2D Lighting unit (lighting device)
3 Shades (lighting boards)
4 Shelf 5 Exterior (part of the showcase body)
6 Roll curtain 9 Product (lighting object)
21 LED light source 22 LED substrate 23 light guide plate 23a upper end surface 23b front surface 23c rear surface 23d lower exit surface 23e substantially mirror surface 23f diffusion surface 24 unit holding member 24a rear plate 24b unnecessary light reflecting surface 24c substrate fixing surface 24d unnecessary light shielding surface 25 reflecting plate (Reflective member)
25s diffusion sheet (reflective member)
25a Diffusion layer 25b Reflection layer 25f Diffusion surface 26 Diffusion dots (diffusion pattern)
27 Meniscus Cylindrical Lens (Shaping Optical Element)
28 Irradiated surface 29 Air layer 33 Screw 34 Counterbore

Claims (15)

An illumination device that performs backlight illumination on a shade having transmission diffusion characteristics located in front and illuminates an illumination object located below,
A translucent light guide plate that guides incident light from the upper end surface to the lower exit surface by reflection on the front surface on the side facing the shade and the rear surface on the back side, and discrete along the longitudinal direction of the upper end surface And a plurality of LED light sources that emit light that is incident on the upper end surface,
A diffusion pattern for diffusing incident light is provided on at least one of the front surface and the back surface, and the shade is illuminated with the light diffused by the diffusion pattern and emitted from the lower emission surface of the light guide plate. An illuminating device for illuminating the object to be illuminated with the emitted light.   2. The illumination according to claim 1, wherein the lower emission surface of the light guide plate includes an inclined surface that is inclined so that the thickness of the light guide plate decreases from the back side toward the front side as it goes downward. apparatus.   The lighting device according to claim 2, wherein an inclination angle θ of the inclined surface with respect to the back surface satisfies the formula: θ <30 °.   The lighting device according to claim 2, wherein the front surface of the light guide plate includes a diffusion surface in at least a part of a region facing the slope through the medium of the light guide plate.   The illuminating device according to claim 1, wherein an area of the diffusion portion of the diffusion pattern increases as the distance from the LED light source increases.   The lighting device according to claim 1, further comprising a reflecting member that reflects light toward the inside of the light guide plate at a lower portion of the front surface of the light guide plate.   The lighting device according to claim 6, wherein the reflecting member diffuses and reflects light toward the light guide plate.   The lighting device according to claim 6 or 7, wherein the reflecting member is integrally attached to the light guide plate without interposing an air layer between the light guide plate and the light guide plate.   The lighting device according to claim 1, wherein the LED light source has emission peaks discretely at a plurality of visible light wavelengths.   10. The illumination according to claim 1, further comprising a back plate that reflects light emitted from the back surface of the light guide plate toward the light guide plate in the vicinity of the back surface of the light guide plate. apparatus.   The lighting device according to claim 10, wherein the back plate diffusely reflects light emitted from the back surface of the light guide plate.   Between the LED light source and the upper end surface of the light guide plate, a shaping optical element that guides each light beam emitted from the LED light source to the upper end surface of the light guide plate is provided. 2. A function of diffusing or diverging each light beam in an arrangement direction and a function of condensing each light beam in a direction perpendicular to the arrangement direction of the LED light sources. The illuminating device of any one of -11.   The lighting device according to claim 1, wherein both left and right end surfaces of the light guide plate have a reflecting function.   An illumination device for use in a showcase provided with the shade on the upper front surface of the showcase body and a shelf on which the product as the illumination object is displayed is provided inside the showcase body, and diffuses in the diffusion pattern The illumination device according to claim 1, wherein the shade is illuminated with the emitted light and the product is illuminated with the light emitted from the lower emission surface of the light guide plate.   A showcase comprising the illumination device according to claim 14.