JP2014175253A - Lighting device - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a lighting device in which a light source is discreet and whose weight is light.SOLUTION: A lighting device 10 includes an optical sheet having a sheet-like main body 35 and a plurality of unit optical elements 40 arranged on one surface 35b of the main body, and a light source 20 for projecting light from one side to the other side in the first direction din parallel with an arrangement direction of the unit optical element. The optical sheet includes a light dispersion layer 31 having a dispersion component 31b and a non-light dispersion layer 32 where the dispersion component is not dispersed. The unit optical element is included in the non-light dispersion layer. The light source has one or more light-emitting members 25. Each of the light emitting members is arranged in such a way that its light axis pd may face to a position on the surface where the unit optical element of the optical sheet and at least a part of the light emitted by each of the light emitting members is directly incident to the optical sheet.

Description

  The present invention relates to an illuminating device, and more particularly, to an illuminating device in which a light source is inconspicuous and reduced in weight.

  Conventionally, various lighting devices have been developed. The illuminating device can be broadly divided into a direct type in which a light source is arranged directly under the optical member, and an edge light type in which a light source is arranged on the side of the optical member as disclosed in Patent Document 1 (both side light type). Called). Among these, in a sidelight type (edge light type) lighting device, typically, a light guide plate, a light source disposed on the side of the light guide plate, and a light control sheet disposed on the light output side of the light guide plate, ,have. The light guide plate adjusts the light amount distribution in the light guide direction, and the light control sheet adjusts the traveling direction of the light emitted from the light guide plate.

JP-A-6-160642

  By the way, in the direct type illumination device, an image of the light source is visually recognized, that is, uneven brightness depending on the arrangement of the light sources is conspicuous, which is not preferable in terms of design. In order to make this uneven brightness invisible, it is necessary to use a diffusion plate having a strong light diffusion function, but in this case, the utilization efficiency of light from the light source is greatly reduced.

  On the other hand, in the sidelight type illumination device, the thickness of the light guide plate that guides light from the light source is increased, and the illumination device becomes heavy. For this reason, in the sidelight type illumination device, it is difficult to increase the size of the light emitting surface. Furthermore, in the illuminating device disclosed in Patent Document 1, the printed pattern formed on the light guide plate is visually recognized, and the design is impaired.

  The present invention has been made in consideration of the above points, and an object of the present invention is to provide an illumination device in which a light source is not conspicuous and is reduced in weight.

The lighting device according to the present invention comprises:
An optical sheet having a sheet-like main body, and a plurality of unit optical elements arranged on one surface of the main body,
A light source that projects light from one side to the other side in a first direction parallel to the arrangement direction of the unit optical elements,
The optical sheet includes a light diffusion layer having a diffusion component and a non-light diffusion layer in which the diffusion component is not dispersed, and the unit optical element is included in the non-light diffusion layer,
The light source has one or more light emitting members,
Each light emitting member is disposed such that its optical axis is directed to a position on the surface of the optical sheet where the unit optical element is provided, and at least a part of the light emitted by each light emitting member is directed to the optical sheet. Directly incident.

  In the illumination device according to the present invention, each unit optical element of the optical sheet may extend linearly in a direction intersecting with the arrangement direction of the unit optical elements.

  In the illumination device according to the present invention, the light emitting member may be disposed at a position shifted along a sheet surface of the optical sheet from a position facing the optical sheet along a normal direction of the optical sheet. .

The illumination device according to the present invention further includes a second light source that projects light so as to go from the other side to the one side in the first direction,
The second light source has one or more light emitting members,
Each light emitting member of the second light source is disposed so that its optical axis is directed to a position on the surface of the optical sheet where the unit optical element is provided, and light is emitted from each light emitting member of the second light source. At least a part of the light may be directly incident on the optical sheet.

  In the illumination device according to the present invention, the light emitting member of the second light source is disposed at a position shifted along a sheet surface of the optical sheet from a position facing the optical sheet along a normal direction of the optical sheet. May be.

  In the illuminating device according to the present invention, the luminance of the side surface of the optical sheet opposite to the side on which the unit optical element is provided is determined to be in-plane along both the normal direction to the optical sheet and the first direction. In the angular distribution of luminance obtained by measuring from each of the directions of the brightness of the brightness that is higher than the brightness in the normal direction of the optical sheet in the direction on both sides of the normal direction to the optical sheet A peak may be present.

  In the illuminating device according to the present invention, the direction in which the peak occurs may be shifted by 20 ° or more from the normal direction of the optical sheet.

In the illumination device according to the present invention, a length A between both ends of the optical sheet along the first direction in a cross section along both the normal direction to the optical sheet and the first direction, and the optical sheet A length B from the optical sheet to the light-emitting member along the normal direction of the optical axis, a width w along the first direction of the unit optical element, and the unit optics along the normal direction of the optical sheet The height h of the element may satisfy the following relationship.
0.5 <h / w <1.5
0.025 <B / A <0.25

  In the illumination device according to the present invention, the optical sheet may be an integrally formed sheet having a thickness of 1.0 mm or more.

  ADVANTAGE OF THE INVENTION According to this invention, the image of a light source can be made not conspicuous enough in an illuminating device, and a illuminating device can be reduced in weight.

FIG. 1 is a diagram for explaining an embodiment according to the present invention, and schematically shows a lighting device. FIG. 2 is a longitudinal sectional view showing the illumination device of FIG. FIG. 3 is a perspective view showing a part of the illumination device of FIG. FIG. 4 is a graph showing the angular distribution of luminance on the light emitting surface of the illumination device of FIG. FIG. 5 is a diagram for explaining an example of a method for manufacturing an optical sheet. FIG. 6 is a longitudinal sectional view showing a modification of the lighting device.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings. In the drawings attached to the present specification, for the sake of illustration and ease of understanding, the scale, the vertical / horizontal dimension ratio, and the like are appropriately changed and exaggerated from those of the actual product.

  In this specification, the terms “sheet”, “plate”, and “film” are not distinguished from each other based only on the difference in designation. For example, “sheet” is a concept that includes a member that can be called a plate or a film. Therefore, for example, “optical sheet” is distinguished from a member called “optical plate” or “optical film” only by a difference in the name. Can't be done.

  In addition, “sheet surface (plate surface, film surface)” means a target sheet-like member (plate-like) when the target sheet-like (plate-like, film-like) member is viewed as a whole and globally. It refers to the surface that coincides with the plane direction of the member or film-like member. In the present embodiment, the light emitting surface of the lighting device and the plate surface of the optical sheet are parallel. Also, the front direction refers to the normal direction to the sheet surface of the optical sheet.

  Furthermore, as used in this specification, the shape and geometric conditions and the degree thereof are specified. For example, terms such as “parallel”, “orthogonal”, “identical”, length and angle values, etc. Without being bound by meaning, it should be interpreted including the extent to which similar functions can be expected.

  1-5 is a figure for demonstrating one embodiment of this invention. Among these, FIG. 1 is a figure which shows the installation condition of the illuminating device 10, FIG. 2 is a figure for demonstrating an effect | action of the illuminating device 10, and FIG. 3 demonstrates the optical sheet 30 of the illuminating device 10. FIG. FIG. 4 is a graph showing the light emission characteristics of the illumination device 10, and FIG. 5 is a diagram for explaining an example of a method for manufacturing an optical sheet. The illumination device 10 has a light emitting surface 10a and emits light in a planar shape from the light emitting surface 10a. In the example shown in FIG. 1, the lighting device 10 is embedded in the ceiling 90 so that the light emitting surface 10a is exposed indoors.

  As illustrated in FIGS. 1 and 2, the lighting device 10 includes an optical sheet 30 and a light source 20 that projects light onto the optical sheet 30. The optical sheet 30 has a light incident side surface 30b that receives light from the light source 20, and a light outgoing side surface 30a that faces the indoor side (that is, the illuminated region side). The illumination device 10 includes a case 15 provided so as to face the light incident side surface 30 b of the optical sheet 30. The case 15 covers the light incident side surface 30b of the optical sheet 30 so as to be connected to the entire circumference of the side end surface of the optical sheet 30 at the end thereof. The inner surface of the case 15 is formed as a reflective surface made of a highly reflective material such as metal.

In the example shown, the optical sheet 30 is configured such that a quadrangular shape in plan view, a pair of edge 30c1,30c2 opposite the first direction d _1, opposite to the second direction And another pair of edges. As shown in FIG. 3, in the illustrated example, the first direction d ₁ and the second direction d ₂ are orthogonal to each other.

As shown in FIGS. 1 and 2, the light source 20 includes a first light source 21 and a second light source 22 that are separated in the first direction d ₁ . The first light source 21 is provided in the vicinity of one of the pair of edges facing the first direction d ₁ of the optical sheet 30, and the second light source 22 is opposed to the first direction d ₁ of the optical sheet 30. It is provided in the vicinity of the other 30c2 of the pair of edges. The first light source 21, in the first direction d ₁ of the light projected to face from one side to the other side, the second light source 22, the light as in the first direction d ₁ direction from the other side to the one side Project.

As the light emitting member 25 constituting the light source 20, various known light emitting members 25, for example, a cold cathode tube, in particular, a cold cathode tube with a narrow light distribution direction can be used. However, in the illustrated example, each of the light sources 21 and 22 is configured using a plurality of point light emitting members 25, typically a plurality of light emitting diodes (LEDs) arranged in a line. A large number of light emitting members 25 constituting the light sources 21 and 22 are arranged side by side along the longitudinal direction of the corresponding edge portions 30c1 and 30c2. That is, as shown in FIG. 3, in the present embodiment, a large number of point light emitting members 25 constituting the light sources 21 and 22 are arranged side by side in the second direction d ₂ .

As well shown in FIGS. 2 and 3, in the illumination device 10, the light emitting member 25 that constitutes the light sources 21 and 22 extends outward of the outer contour of the optical sheet 30 along the sheet surface of the optical sheet 30. positioned. More specifically, the light emitting member 25 of the pair of light sources 21 and 22, respectively, are arranged on the position where the both outer sides of the pair of edges 30c1,30c2 opposite the first direction _{d 1.} That is, in plan view (when observed from the normal direction nd to the optical sheet 30), the light emitting members 25 that constitute the light sources 21 and 22 are arranged at positions that do not overlap the optical sheet 30.

  Moreover, in this illuminating device 10, as shown in FIG. 2, the light emitting member 25 which comprises the light sources 21 and 22 is arrange | positioned in the position shifted | deviated from the optical sheet 30 along the front direction nd. More specifically, the light emitting member 25 that constitutes the light sources 21 and 22 is on the side away from the optical sheet 30 along the normal direction nd to the sheet surface of the optical sheet 30 rather than the light incident side surface 30b of the optical sheet 30. It is arranged at a position shifted to the side away from the room. For this reason, as shown in FIG. 2, the light emitted from the light emitting member 25 constituting the light sources 21 and 22 has directivity and can directly enter the light incident side surface 30 b of the optical sheet 30.

  Incidentally, in the illustrated example, the light emitting member 25 includes a point-like light emitter 26 such as an LED, and a cap 27 provided so as to cover the light emitter 26. The cap 27 controls the traveling direction of light emitted from the light emitter 26 and adjusts the light distribution characteristics of the light emitting member 25. That is, the light emitting member 25 does not emit light radially with a uniform luminous intensity, but has directivity. The light emitting member 25 emits light with a different luminous intensity (unit: candela) in each direction, and has a peak luminous intensity in a specific direction pd. As the inclination angle with respect to the specific direction pd increases, the value of the luminous intensity gradually decreases. Preferably, the arrangement of the light emitting members 25 constituting the light source 20 is determined in consideration of the directivity characteristics (light distribution characteristics, in other words, the angle (direction) distribution of luminous intensity) of the light emitting members 25. In the present specification, the above-described specific direction that provides the peak luminous intensity is referred to as an “optical axis”.

As shown in FIG. 2, in a cross section parallel to both the front direction nd and the first direction d _1, the optical axis pd emitting member 25 is included in each first light source 21 and 22, parallel to the optical sheet 30 sheet surface It is inclined from a certain direction and is directed to the optical sheet 30 side. Further, the light emitting member 25 is disposed so that the optical axis pd thereof faces the position on the light incident side surface 30 b of the optical sheet 30. As a result, at least a part of the light emitted by each light emitting member 25 can directly enter the optical sheet 30, that is, can enter the optical sheet 30 without passing through another member.

According to such setting of the optical axis pd, light emitted from the light emitter 26 of the light emitting member 25 can be used very efficiently. From the viewpoint to improve the utilization efficiency of light from the light source 20, as in the illustrated example, the normal direction nd and the surface (FIG along both the first direction d ₁ of the optical sheet 30 2), the arrangement (position, position) of the light emitting member 25 so as to emit light at the maximum luminous intensity toward the middle position between the pair of edge portions 30c1 and 30c2 of the optical sheet 30 or the region near the position. The orientation) is preferably adjusted.

  Next, the optical sheet 30 will be described. The optical sheet 30 described here has a light control function for changing the traveling direction of light. As a specific configuration, as shown in FIGS. 2 and 3, the light incident side surface 30 b of the optical sheet 30 is an optical element surface formed by unit optical elements (unit prisms) 40 arranged side by side ( Prism surface). By this optical element surface, the optical sheet 30 has a function of correcting the traveling direction of the light, in particular, in the illustrated example, the traveling direction of the light is deflected so that the angle formed by the traveling direction of the light with respect to the front direction nd is reduced. It is designed to express the deflection function. Further, the optical sheet 30 contains a diffusion component 31b, and the optical sheet 30 exhibits a light diffusion function by the diffusion component 31b. Hereinafter, the configuration of the optical sheet 30 will be further described in detail.

  The “unit optical element” in the present specification refers to an element having a function of changing the traveling direction of the light by exerting an optical action such as refraction or reflection on the light. ”,“ Unit prism ”, and“ unit lens ”are not distinguished based only on the difference in designation and elements. Similarly, “prism” and “lens” are not distinguished from each other based solely on the difference in designation.

As well shown in FIG. 3, the optical sheet 30 includes a sheet-like main body portion 35 and unit optical elements 40 arranged side by side on a surface 35 b on the light incident side of the main body portion 35. Yes. Each unit optical element 40 extends in a direction intersecting with the arrangement direction and parallel to the film surface of the optical sheet 30. In the illustrated example, when observed from a direction parallel to the normal direction nd to the sheet surface of the optical sheet 30, the arrangement direction of the unit optical elements 40 is a first direction orthogonal to the arrangement direction of the light emitting members 25. It has become a parallel with the d _1. Each unit optical element 40 extends linearly in a second direction d ₂ orthogonal to the first direction d ₁ . Furthermore, the unit optical elements 40 included in the optical sheet 30 are configured identically. The unit optical elements 40 are arranged without a gap, and as a result, the light incident side surface 30 b of the optical sheet 30 is formed by the unit optical elements 40.

The cross section shown in FIG. 2 is a cross section (hereinafter also simply referred to as “main cut surface”) along both the arrangement direction d ₁ of the unit optical elements 40 and the normal direction to the sheet surface of the optical sheet 30. is there. As shown in FIG. 2, each unit optical element 40 has a triangular shape on the main cutting plane. In particular, in the illustrated example, the cross-sectional shape of the unit optical element 40 at the main cutting plane is an isosceles triangle that is arranged symmetrically about the normal direction nd to the sheet surface of the optical sheet 30. According to the optical sheet 30 having such a unit optical element 40, a symmetrical optical function can be exhibited with respect to the light from the first light source 21 and the light from the second light source 22. As a result, symmetrical light distribution characteristics can be exhibited with the front direction nd as the center.

  Further, as described above, the optical sheet 30 includes the diffusion component 31b, and the optical sheet 30 exhibits a light diffusion function by the diffusion component 31b. More precisely, the optical sheet 30 includes a light diffusion layer 31 having a main part 31a made of a resin and a diffusion component 31b dispersed in the main part 31a.

  As shown in FIG. 3, the illustrated optical sheet 30 includes a light diffusion layer 31 and a non-light diffusion layer 32 that does not contain the diffusion component 31 b. In the illustrated example, the non-light diffusion layer 32 is disposed on the light incident side with respect to the light diffusion layer 31. That is, the light diffusion layer 31 is disposed on the indoor side of the non-light diffusion layer 32.

  The non-light diffusing layer 32 does not contain a diffusing component and is formed only by a main portion 32a made of a resin material. The non-light diffusion layer 32 constitutes the unit optical element 40 described above and the light incident side portion of the main body 35. On the other hand, the light diffusion layer 31 constitutes a light output side portion of the main body 35 adjacent to the non-light diffusion layer 32. Further, due to the manufacturing method described later, there is no optical interface between the main portion 31 a of the light diffusion layer 31 and the main portion 32 a of the non-light diffusion layer 32. That is, the light enters the optical sheet 30 from the non-light diffusion layer 32 to the light diffusion layer 31 without being optically affected.

  As the resin material forming the main portion 32a of the non-light diffusing layer 32 and the resin material forming the main portion 31a of the light diffusing layer 31, various resin materials having excellent optical characteristics, for example, polycarbonate resins can be used.

  On the other hand, the diffusing component 31b dispersed in the light diffusing layer 31 may be composed of a granular material having a refractive index different from that of the main portion 31a, or a granular material that itself has reflectivity. The particulate material constituting the diffusion component 31b may be a metal compound, a porous material containing a gas, or may be a simple bubble. Further, the shape of the diffusion component 31b made of a granular material is not particularly limited. Therefore, the diffusion component 31b does not have to be spherical (particulate) as in the illustrated example, and can have various shapes such as a spheroid shape and a linear shape.

  The thickness t (see FIG. 2) of the optical sheet 30 having the above configuration is preferably 1.0 mm or more as a numerical value up to the first decimal place rounded off to the first decimal place, and 2.0 mm. More preferably, it is the above. Here, the thickness t of the optical sheet 30 is a length along the normal direction nd of the optical sheet 30 from the light exit side surface 30a of the optical sheet 30 to the top 41 of the unit optical element 40, as shown in FIG. It is. When the thickness of the optical sheet 30 is thin, the optical sheet 30 is bent by its own weight, particularly in the lighting device 10 attached to the ceiling 90. In this case, since the relative position of the optical sheet 30 with respect to the light source 20 deviates from the design value, it becomes impossible to realize illumination with desired light distribution characteristics. However, the thickness t of the optical sheet 30 is preferably 5.0 mm or less in order to avoid an unsuitable weight for attachment to the ceiling 90.

Further, in the cross section of FIG. 2 along both the normal direction nd and the first direction d ₁ to the optical sheet 30, the width w of the unit optical element 40 along the first direction d ₁ and the normal line of the optical sheet 40. The height h of the unit optical element 40 along the direction nd satisfies the following condition (1), and at the same time, the cross section of FIG. 2 along both the normal direction nd and the first direction d ₁ to the optical sheet 30 , The length A between both ends of the optical sheet 30 along the first direction d ₁ and the length B from the optical sheet 30 to the light emitting member 25 along the normal direction nd of the optical sheet 30 are as follows: It is preferable to satisfy 2).
0.5 <h / w <1.5 Condition (1)
0.025 <B / A <0.25 ... Condition (2)
Here, the length B from the optical sheet 30 to the light emitting member 25 along the normal direction nd of the optical sheet 30 is the length of the unit optical element 40 of the optical sheet 30 along the normal direction nd of the optical sheet 30. It is the length from the top 41 to the center position 25a of the light emitting surface of the light emitting member 25. When the condition (1) and the condition (2) are satisfied at the same time, the lighting device 10 attached to the ceiling 90 has an ideal light distribution characteristic, more specifically, by light from the lighting device 10 attached to the ceiling 90. It is possible to realize illumination with more uniform brightness.

  As another specific dimension example regarding the optical sheet 30, the width w (see FIG. 2) along the sheet surface of the optical sheet 30 can be 1 μm or more and 500 μm or less, and the normal to the plate surface of the optical sheet 30. A height h (see FIG. 2) from the surface 35b on one side of the main body 35 of the unit optical element 40 along the direction nd can be set to 0.5 μm or more and 750 μm or less. When the cross-sectional shape of the unit optical element 50 is a triangular shape or a shape formed by chamfering the apex angle of the triangular shape, the angle θa (see FIG. 2) of the apex angle 56 is greater than 36 ° and less than 90 °. It can be.

  Next, a method for manufacturing the optical sheet 30 will be described. In the following description, the optical sheet 30 is formed from a thermoplastic resin by a melt extrusion method using an extrusion device 50.

  The extrusion molding device 50 includes an extruder 55 for extruding a thermoplastic resin into a sheet shape, a roll group 61, 62, 63, 64, 66, 67 for guiding the extrusion material 49 from the extrusion machine 55, and the extrusion material 49. And a shaping sheet supply mechanism 70 that supplies a shaping sheet 74 that functions as a mold for molding. The extruder 55 heats the pellet-shaped thermoplastic resin as a raw material and extrudes the sheet-shaped extruded material 49 from the die 56. The extruded material 49 advances between the first main roll 61 and the second main roll 62, and then between the second main roll 62 and the third main roll 63 and between the third main roll 63 and the fourth main roll 64. And the second main roll 62, the third main roll 63, and the fourth main roll 64 are supported by the outer peripheral surfaces and move. Thereafter, the pushing material 49 passes between the first guide roll 66 and the second guide roll 67.

  On the other hand, the shaping sheet supply mechanism 70 includes a supply roll 71 that holds the elongated shaping sheet 74 in a wound state, a collection roll 72 that winds and collects the shaping sheet 74 fed out from the supply roll 71, have. When the shaping sheet 74 is unwound from the supply roll 71, it proceeds between the first main roll 61 and the second main roll 62. Next, the shaping sheet 74 passes between the second main roll 62 and the third main roll 63 and between the third main roll 63 and the fourth main roll 64, The third main roll 63 and the fourth main roll 64 are supported by the outer peripheral surfaces and move. Thereafter, the shaping sheet 74 passes between the first guide roll 66 and the second guide roll 67 and is wound around the collection roll 72 and collected.

  As shown in FIG. 5, the high-temperature extrusion material 49 extruded from the extrusion molding device 50 passes between the first main roll 61 and the second main roll 62 in contact with the shaping sheet 74, and thereafter It moves in synchronization with the shaping sheet 74 until it passes between the first guide roll 66 and the second guide roll 67. While the extrusion material 49 and the shaping sheet 74 are overlapped and moved, particularly during the movement while being supported by the outer peripheral surfaces of the second main roll 62, the third main roll 63 and the fourth main roll 64, the extrusion material 49 and the shaping sheet 74 are moved. The material 49 and the shaping sheet 74 are pressed toward each other. The shaping sheet 74 functions as a mold for transferring the shape to the extrusion material 49, and irregularities corresponding to the irregularities to be transferred to the extrusion material 49 are formed on the surface facing the extrusion material 49. Yes. As a result, the optical sheet 30 is produced.

  Here, the shaping sheet 74 is made of resin at least on the surface that comes into contact with the extruded material 49. For example, the shaping sheet 74 is prepared in advance by shaping an ionizing radiation curable resin on a resin base material. By molding the ionizing radiation curable resin on the substrate, a desired shape can be imparted to the shaping sheet 74 with high accuracy.

  That is, in the manufacturing method of the optical sheet 30 described above, the mold surface for molding the extrusion material 49 is formed of a resin having a relatively small heat capacity and relatively poor thermal conductivity. For this reason, the heat of the high-temperature extrusion material 49 extruded from the extrusion molding apparatus 50 does not rapidly take away from the extrusion material 49 to the shaping sheet 74 by contacting the shaping sheet 74. As a result, the high-temperature extrusion material 49 can be accurately deformed following the unevenness formed on the surface of the shaping sheet 74.

  Further, the extruded material 49 keeps in contact with the shaping sheet 74 for a long period of time from the main rolls 61 and 62 to passing through the guide rolls 66 and 67. For this reason, when the extrusion material 49 reaches the guide rolls 66 and 67, the temperature of the extrusion material 49 can be sufficiently lowered to a temperature suitable for releasing from the shaping sheet 74. As a result, the extrusion material 49 can be smoothly released from the shaping sheet 74. Furthermore, since the temperature of the extrusion material 49 has already decreased sufficiently when it is separated from the shaping sheet 74, the shape molded on the extrusion material 49 may be flattened after being separated from the shaping sheet 74. Effectively suppressed. For these reasons, the optical element surface of the optical sheet 30 having the unit optical elements 40 can be molded with high accuracy with respect to the extruded material 49.

  In addition, when the shaping sheet 74 is used, since the molding accuracy (transfer accuracy, shaping accuracy) is improved as described above, the main rolls 61 to 64 are directed to the extrusion material 49 and the shaping sheet 74. There is no need to significantly increase the applied pressure. From this point, damage to the shaping sheet 74 can be alleviated, and the shaping sheet 74 can be used repeatedly. Thereby, the manufacturing cost of the optical sheet 30 can be reduced directly.

  As described above, the optical sheet 30 including the unit optical element 40 having a high aspect ratio (h / w) can be manufactured by a relatively inexpensive melt extrusion molding method.

  In addition, when the extruder 55 of the extrusion molding apparatus 50 performs coextrusion, the optical sheet 30 to be manufactured can include the light diffusion layer 31 and the non-light diffusion layer 32 as described above. In the obtained optical sheet 30, there is substantially no optical interface that can exert an optical action on the transmitted light between the light diffusion layer 31 and the non-light diffusion layer 32.

  Moreover, according to the manufacturing method shown in FIG. 5, the optical sheet 30 integrally formed using the thermoplastic resin is obtained. According to such a manufacturing method, compared with optical sheets obtained by molding an ionizing radiation curable resin on a base material, the optical sheet 30 having a large thickness, for example, exceeding 1 mm, is a single sheet. Can be produced integrally.

  Furthermore, in the extrusion molding apparatus 50, by forming irregularities on the outer peripheral surface of the second main roll 62, a structure corresponding to the irregularities can be formed on the light exit side surface 30 a of the optical sheet 30.

  Next, the operation of the illumination device 10 will be described mainly with reference to FIGS. 1 and 2.

  As described above, in the cross section shown in FIG. 2, the optical axis pd of the light emitted from the light emitting member 25 of the light source 20 extends toward the position on the light incident side surface 30 b of the optical sheet 30. For this reason, a lot of light emitted from the light emitting members 25 of the first light source 21 and the second light source 22 enters the light incident side surface 30b of the optical sheet 30 directly, that is, without entering other members.

In the illustrated example, a light guide plate for making the light quantity distribution along the irradiation direction (light guide direction) of light from the light source 20 is not provided. However, as described above, the optical axis pd of the light emitted from the light emitting member 25 of the light source 20 extends toward the position on the light incident side surface 30b of the optical sheet 30, and the light emission characteristics of the light emitting member 25 are as follows. For example, adjustment is possible with a cap 27. As a result, the light amount distribution in the first direction d _1, can be made uniform to the extent that does not cause discomfort.

  The light from the light emitting member 25 is also emitted in a direction inclined from the optical axis pd of the light emitting member 25. Therefore, a part of the light emitted from the light emitting member 25 of the light source 20 enters the reflecting surface 16 of the case 15 directly, that is, without entering another member. Such light can be incident on the light incident side surface 30 b of the optical sheet 30 after being reflected by the reflecting surface 16.

  The optical sheet 30 has a deflection function that deflects the traveling direction of light so that the angle formed by the traveling direction of light with respect to the front direction nd is small, and a light diffusion function that diffuses light. Among these, the deflection function is expressed by the unit optical element 40 of the optical sheet 30, and the light diffusion function is mainly expressed by the light diffusion layer 31 of the optical sheet 30. The unit optical element 40 forms the light incident side surface 30 b of the optical sheet 30, and the light diffusion layer 31 is provided on the light output side of the optical sheet 30. For this reason, the light incident on the optical sheet 30 is first subjected to the deflection function and then the light diffusion function.

As shown well in FIG. 2, the basic principle of the deflection function by the unit optical element 40 having a triangular cross section is that light incident from one surface (incident surface) of the unit optical element 40 is converted to the other surface ( By totally reflecting on the total reflection surface), the angle formed by the traveling direction of the light with respect to the front direction nd is reduced. As shown in FIG. 2, the light emitting member 25 included in the first light source 21 irradiates light toward the one side in a position to and the first direction d ₁ on one side in the first direction d ₁ to the other side . The light from each light emitting member 25 of the first light source 21 enters the unit optical element 40 from a surface located on one side of the unit optical element 40 and is totally reflected on the other surface of the unit optical element 40. To do. On the other hand, the light emitting member 25 included in the second light source 22 irradiates light toward the other side to the one side in a position to and the first direction d ₁ to the other side in the first direction d _1. Therefore, the light from each light emitting member 25 of the second light source 22 is incident on the unit optical element 40 from the surface located on the other side of the unit optical element 40, and on one surface of the unit optical element 40. Total reflection.

  Such a deflection function by the unit optical element 40 is mainly exerted on a light component parallel to the arrangement direction of the unit optical elements 40. Then, by appropriately designing the cross-sectional shape of the unit optical element 40, the aspect ratio (height h / width w of the unit optical element 40) particularly in relation to the main incident angle of the light source light to the optical sheet 30. ) Is set, the degree of the deflection function in the unit optical element 40 of the optical sheet 30 can be adjusted.

  The light incident on the optical sheet 30 through the unit optical element 40 then travels in the main body portion 35 from the non-light diffusion layer 32 to the light diffusion layer 31 having a light diffusion function. The light diffusion layer 31 has a main part 31a and a diffusion component 31b dispersed in the main part 31a, and expresses a light diffusion function due to the internally added diffusion component 31b. Thereby, the angular distribution of luminance after being deflected by the unit optical element 40 of the optical sheet 30 can be changed smoothly. The degree of the diffusion function of the light diffusion layer 31 is as follows: the resin material forming the main portion 31a, the thickness of the main portion 31a, the configuration of the diffusion component 31b (shape, size (particle size), refractive index, etc.), diffusion component 31b By appropriately setting the concentration and the like, the degree of the light diffusion function of the light diffusion layer 31 can be adjusted within a very wide range.

  The light diffused by the light diffusion layer 31 of the optical sheet 30 is then emitted from the light emitting surface 10a of the illumination device 10 formed by the light exiting side surface 30a of the optical sheet 30.

Here, FIG. 4 shows an example of ideal light emission characteristics of the illumination device 10. Graph shown in FIG. 4, the luminance of the light emitting surface 10a of the illumination device 10 made by Idemitsu side 30a of the optical sheet 30, along both the normal direction nd and the first direction d ₁ of the optical sheet 30 It is an angular distribution of luminance obtained by measuring from each direction in the plane. In the angular distribution of the luminance on the light emitting surface 10a of the illumination device 10 shown in FIG. There is also a luminance peak with high luminance. More specifically, in the angular distribution of luminance on the light emitting surface 10a of the illumination device 10 shown in FIG. 4, there is no luminance peak in the front direction nd. Preferably, a luminance peak exists in a direction inclined by 20 ° or more with respect to the front direction nd.

For example, in the example shown in FIG. 2, the traveling direction of light projected from the first light source 21 and transmitted through the optical sheet 30 is not narrowed down to the normal direction nd of the optical sheet 30, and is caused by this light. peak of the angular distribution of luminance that is formed is caused in a direction inclined with respect to the front direction nd toward the other side from one side in the first direction d _1. On the other hand, the traveling direction of the light projected from the second light source 22 and transmitted through the optical sheet 30 is not narrowed down to the normal direction nd of the optical sheet 30, and the peak of the luminance angular distribution formed due to this light occurs in a direction inclined with respect to the front direction nd toward one side from the other side in the first direction d _1. According to such light from the first light source 21 and light from the second light source 22, as shown in FIG. 4, a direction inclined by 20 ° or more with respect to the normal direction nd to the optical sheet 30. In addition, it is possible to generate a luminance peak that is higher in luminance than the luminance in the normal direction nd of the optical sheet 30.

  As shown in FIG. 1, the light beams Lfa and Lfb spreading from the light emitting surface 10a of the lighting device 10 to a certain angle range θr are on a surface substantially parallel to the light emitting surface 10a, usually on a surface parallel to the floor surface. The process proceeds to areas Za and Zb having different widths. As shown in FIG. 1, the region Za in which the light beam Lfa traveling in the direction inclined with respect to the front direction nd travels is wider than the region Zb in which the light beam Lfb traveling in the front direction nd directly below the light emitting surface 10 a travels. . Therefore, from the viewpoint of aligning the illuminance at each position in the area where the illumination device 10 is installed, for example, from the viewpoint of aligning the illuminance at each position in the room where the illumination device 10 is installed on the ceiling 90, the optical sheet 30. It is preferable that a luminance peak having higher luminance than the luminance in the normal direction nd of the optical sheet 30 exists in the direction that is on both sides of the normal direction nd to the front. In particular, it is preferable that a luminance peak exists in a direction inclined by 20 ° or more with respect to the front direction nd.

As described above, the degree of the deflection function by the unit optical element 40 in the optical sheet 30 that directly affects the angular distribution of luminance is related to the main incident angle of the light source light to the optical sheet 30 in units. Adjustment is possible by setting the aspect ratio (height h / width w) of the optical element 40. In particular, the width w along the first direction nd of the unit optical element 40 in the cross section of FIG. 2 along both the normal direction nd to the optical sheet 30 and the first direction d ₁ , and the normal direction of the optical sheet 40. Light emission from the optical sheet 30 along the normal direction nd of the optical sheet 30, the height h of the unit optical element 40 along nd, the length A between both ends of the optical sheet 30 along the first direction d ₁ When the length B to the member 25 satisfies the conditions (1) and (2) described above, the normal direction of the optical sheet 30 in a direction inclined by 20 ° or more with respect to the normal direction nd to the optical sheet 30 There was a tendency that there was a luminance peak that was higher than the luminance at nd.
0.5 <h / w <1.5 Condition (1)
0.025 <B / A <0.25 ... Condition (2)

  According to the present embodiment as described above, the position facing the optical sheet 30 forming the light emitting surface 10a of the illumination device 10, that is, the position facing the optical sheet 30 along the normal direction nd of the optical sheet 30. The light emitting member 25 that forms the light source 20 does not exist. Therefore, uneven brightness due to the arrangement of the light emitting members 25 of the light source 20 does not occur on the light emitting surface 10a of the lighting device 10. Further, since there is no thick light guide plate for guiding light from the light emitting member 25 that constitutes the light source 20, the lighting device 10 can be reduced in weight. Thereby, it becomes possible to enlarge the light emitting surface 10a of the illuminating device 10.

  Further, according to the present embodiment, the single optical sheet 30 has a function of deflecting the traveling direction of light from the light source 20 and a function of diffusing the light. Therefore, the number of optical sheets included in the illumination device 10 can be reduced. Thereby, the manufacturing cost of the illuminating device 10 can be directly reduced, and the illuminating device 10 can be reduced in thickness and weight. The optical sheets are members for controlling the traveling direction of light, but on the other hand, some of the incident light is reflected and some of the incident light is absorbed. As a result, most of the light emitted from the light emitting member 25 constituting the light source 20 is absorbed by any of the optical sheets and cannot be used for displaying an image. On the other hand, according to the above-described embodiment, the light from the light source 20 is transmitted only through the optical sheet 30 and is emitted from the light emitting surface 10 a of the illumination device 10. For this reason, the utilization efficiency of the light emitted by the light emitting member 25 forming the light source 20 can be significantly increased.

  In particular, according to the illustrated example, the illumination device 10 includes only the optical sheet 30 as optical sheets for changing the traveling direction of light from the light source 20. Therefore, the lighting device 10 can be significantly reduced in thickness and weight, and the light use efficiency from the light source 20 can be greatly improved.

  Note that various modifications can be made to the above-described embodiment. Hereinafter, an example of modification will be described with reference to the drawings. In the following description and the drawings used in the following description, the same reference numerals as those used for the corresponding parts in the above embodiment are used for the parts that can be configured in the same manner as in the above embodiment. A duplicate description is omitted.

  For example, in the above-described embodiment, an example of the cross-sectional shape of the main cutting surface of the unit optical element 40 has been described, but the present invention is not limited to this. For example, although the cross-sectional shape in the main cut surface of the unit optical element 40 has a triangular shape, the cross-sectional shape in the main cut surface of the unit optical element 40 can be designed in various shapes. For example, the triangular top portion forming the cross-sectional shape of the unit optical element 40 may be chamfered. In addition, on the main cut surface of the optical sheet, at least one of the two sides extending from the triangular main body 35 described above may be deformed so as to be a curve that bulges outward. Furthermore, the unit optical element 40 may have a curved outer contour on the main cut surface of the optical sheet 30. That is, the surface of the unit optical element 40 may be configured as a curved surface. As an example of a specific shape, the unit optical element 40 has a shape corresponding to a part of an ellipse (a semi-ellipse as an example) or a part of a circle (a semi-circle as an example) on the main cut surface of the optical sheet 30. You may do it.

  In the above-described embodiment, the example in which the unit optical elements 40 included in the optical sheet 30 are formed in the same manner has been described, but the present invention is not limited thereto. The plurality of unit optical elements 40 may be configured to form a Fresnel lens.

  Furthermore, the unit optical element 40 is not limited to a linear element arranged one-dimensionally, but may be a dot-like element arranged two-dimensionally to constitute a microlens (fly eye lens).

  Furthermore, in embodiment mentioned above, although LED was illustrated as the point light emission member 25 of the light sources 20, 21, and 22, it is not restricted to this, You may use another point light emitter. Further, the light emitting member 25 of the light sources 20, 21, 22 is not limited to the point light emitting member, and a linear light emitting member such as a cold cathode tube may be used.

Furthermore, in the above-described embodiment, an example in which the pair of light sources 21 and 22 are provided so as to correspond to the pair of edge portions 30c1 and 30c2 of the optical sheet 30, respectively, is not limited thereto, Only one light source may be provided in the illumination device 10. For example, as shown in FIG. 6, one of the pair of light sources 21 and 22 may be omitted. In such an example, the unit cross-sectional shape of the optical element 40, it is sufficient deflect light from the light source 20 located on one side in the first direction d _1, it becomes symmetrical around the front direction nd There is no need to be.

Furthermore, in the above-described embodiment, the example in which the lighting device 10 has only one light emitting surface 10a has been described, but the present invention is not limited thereto. As shown in FIG. 6, the illuminating device 10 may have a pair of optical sheets 30 disposed to face each other, and each optical sheet 30 may form a light emitting surface 10a. In the example shown in FIG. 6, the pair of optical sheets 30 are arranged to face each other so that the unit optical elements 40 face each other. Light source 20 is directed to a region to be a between the pair of the optical sheet 30, as directed from one side to the other side in the first direction d _1, emits light. In this example, it is preferable that the light emitting member 25 included in the light source 20 has two optical axes pd that are directed to positions on the light incident side surface 30 b of each optical sheet 30. The illuminating device 10 shown by FIG. 6 is installed in the wall 91 which divides two rooms as an example. The two light emitting surfaces 10a of the illuminating device 10 are exposed in each room, and emit light to each of the two rooms.

  In addition, although the some modification with respect to embodiment mentioned above was demonstrated above, naturally, it is also possible to apply combining several modifications suitably.

DESCRIPTION OF SYMBOLS 10 Illuminating device 10a Light-emitting surface 15 Case 16 Reflective surface 20 Light source 21 1st light source 22 2nd light source 25 Light-emitting member 26 Light-emitting body 27 Cap 30 Optical sheet 30a Light emission side surface 30b Light-incidence side surface 30c1 Edge, 1st edge 30c2 Edge , Second edge 31 light diffusing layer 31a main portion 31b diffusing component 32 non-light diffusing layer 32a main portion 35 main body portion 40 unit optical element 49 extrusion material 50 extrusion molding device 55 extrusion machine 56 die 61, 62, 63, 64 main Rolls 66 and 676 Guide roll 70 Molding sheet supply mechanism 71 Supply roll 72 Collection roll 74 Molding sheet 75 Second mold sheet supply mechanism 76 Second supply roll 77 Second collection roll 79 Second mold sheet 90 Ceiling 91 Wall

Claims (6)

An optical sheet having a sheet-like main body, and a plurality of unit optical elements arranged on one surface of the main body,
A light source that projects light from one side to the other side in a first direction parallel to the arrangement direction of the unit optical elements,
The optical sheet includes a light diffusion layer having a diffusion component and a non-light diffusion layer in which the diffusion component is not dispersed, and the unit optical element is included in the non-light diffusion layer,
The light source has one or more light emitting members,
Each light emitting member is disposed such that its optical axis is directed to a position on the surface of the optical sheet where the unit optical element is provided, and at least a part of the light emitted by each light emitting member is directed to the optical sheet. Directly incident lighting device. A second light source that projects light from the other side toward the one side in the first direction,
The second light source has one or more light emitting members,
Each light emitting member of the second light source is disposed so that its optical axis is directed to a position on the surface of the optical sheet where the unit optical element is provided, and light is emitted from each light emitting member of the second light source. The lighting device according to claim 1, wherein at least a part of light is directly incident on the optical sheet.   The luminance on the side opposite to the side on which the unit optical element is provided of the optical sheet is measured from each direction in the plane along both the normal direction to the optical sheet and the first direction. In the angular distribution of luminance obtained by this, there is a luminance peak that is higher in luminance than the luminance in the normal direction of the optical sheet in the direction that is on both sides of the normal direction to the optical sheet. 2. The lighting device described in 2.   The lighting device according to claim 3, wherein a direction in which the peak is generated is deviated by 20 ° or more from a normal line direction of the optical sheet. The length A between both ends of the optical sheet along the first direction and the normal direction of the optical sheet in the cross section along both the normal direction to the optical sheet and the first direction. A length B from the optical sheet to the light emitting member, a width w of the unit optical element along the first direction, a height h of the unit optical element along a normal direction of the optical sheet, The lighting device according to any one of claims 1 to 3, wherein satisfies the following relationship.
0.5 <h / w <1.5
0.025 <B / A <0.25   The lighting device according to any one of claims 1 to 5, wherein the optical sheet is an integrally formed sheet having a thickness of 1.0 mm or more.

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