JPWO2012046441A1 - Surface light source element and lighting device including the same - Google Patents

Abstract

The light source (1) and the light emitted from the light source (1) are incident on one end surface (21), propagate inside, and exit from one main surface (22) orthogonal to the end surface (21). A light guide plate (2), and in the light guide plate (2), when considering a right-handed coordinate space consisting of an X axis, a Y axis, and a Z axis orthogonal to each other, one end face (21) constituting the incident surface Is substantially parallel to the YZ plane, and one main surface (22) constituting the exit surface is substantially parallel to the XY plane and is located in the + Z direction with respect to the other main surface (23), The outgoing light from the outgoing surface (22) has more of the other component than either one of the components in the -Y direction and the + Y direction. A surface light source element in which the luminous flux emitted from the surface is 55% or more of the total emitted luminous flux.

Description

  The present invention relates to a surface light source element and a lighting device including the same, and more particularly to a surface light source element using a light guide plate and a lighting device including the same.

  For light source elements used for illumination, light from the light source is directed directly to the place to be irradiated, or light from the light source arranged on the end face of the light guide plate is extracted from the main surface orthogonal to the end face of the light guide plate and irradiated. There is a method.

  Patent Document 1 discloses an illumination device using a light source having a small size, high efficiency, and high brightness, such as an LED, and a light guide plate. An illuminating device using such a light guide plate can efficiently spread light from a small light source and illuminate a wide range uniformly. Furthermore, since the light source can be downsized or the number of light sources can be reduced, and it is preferable in terms of circuit design in terms of space saving and energy saving, it has been widely used.

  By the way, a light source element using a light guide plate has been widely used as a surface light source element (backlight) of a transmissive image display device typified by a liquid crystal display device. In such an image display device, the light exit surface is directly observed. Therefore, the backlight is usually designed so as to deflect light in the normal direction (front direction) of the light emitting surface (see, for example, Patent Document 2).

  On the other hand, for example, in lighting devices such as spotlights, display shelves, and indirect lighting, there is an application in which only a specific direction is brightened. When a conventional backlight is used for such an application, it is necessary to tilt the surface light source element itself, which increases the size of the illumination device itself.

  With respect to such a problem, Patent Document 3 discloses a method of concentrating light in one direction in the direction in which light propagates in the light guide plate. In this direction, the direction in which light propagates through the light guide plate is primarily limited to one direction, so that light can be concentrated in one direction by removing it from the condition of total reflection inside the light guide plate.

  Patent Document 4 discloses a surface light source element that emits light in an arbitrary direction.

  Patent Document 5 discloses a prism sheet that deflects light emitted from a light guide plate at a certain angle.

  Patent Document 6 discloses a method of separating light emitted from a light guide plate in two directions on a surface orthogonal to the light guide direction by a member provided on the exit surface side. With this method, it is possible to deflect light at a specific angle.

JP 2007-059285 A JP 2005-142128 A JP 2001-229703 A JP 2004-071189 A JP 2007-503007 A JP 2007-294465 A

In the method disclosed in Patent Document 3, since the same amount of light as that on the illumination side is emitted to the observation side on the surface orthogonal to the light guide direction, the design and appearance are inferior, and the energy loss is large.
Patent Document 4 does not show specific means for emitting light in an arbitrary direction.
In the method disclosed in Patent Document 5, a member different from the light guide plate is necessary, and the cost is increased, the reliability is lowered, and the convenience is inferior. Moreover, it aims at a wide viewing angle for a display, and is not suitable for irradiating a specific angle.
Even in the method disclosed in Patent Document 6, as in Patent Document 3, since the same amount of light as that on the illumination side is emitted to the observation side on the surface orthogonal to the light guide direction, the design and appearance are inferior. Loss is also great.

  The present invention has been made in view of the above, and an object thereof is to provide a highly efficient surface light source element that is excellent in design and appearance, and a lighting device including the same.

One aspect of the present invention is:
A light source;
The light emitted from the light source is incident on one end surface, propagates through the inside, and is output from one main surface orthogonal to the end surface, and
In the light guide plate, when considering a right-handed coordinate space consisting of an X axis, a Y axis, and a Z axis orthogonal to each other,
The one end face constituting the incident surface is substantially parallel to the YZ plane,
The one main surface constituting the emission surface is substantially parallel to the XY plane and is positioned in the + Z direction with respect to the other main surface,
The outgoing light from the outgoing surface has more of the other component than either one of the components in the −Y direction and the + Y direction, and has the component in this direction, from the outgoing surface of the light guide plate. In this surface light source element, the emitted light beam is 55% or more of the entire emitted light beam.

In the one aspect, the main surface facing the emission surface has a plurality of recesses, and the recess includes a first surface substantially parallel to the XZ plane and a second surface made of a plane or a curved surface. It is preferable that the normal vector in the + Z direction at an arbitrary location on the second surface has a component that the outgoing light has more of the components in the −Y direction and the + Y direction.
Here, it is preferable that the shape of the concave portion is a part or the whole of a polygonal pyramid, or an elliptical sphere or a part of a cone.
Further, the inclination angle of the second surface from the XY plane is α, and the projection of the normal vector in the + Z direction of the second surface onto the XY plane as viewed from the + Z direction is the counterclockwise angle from the + X direction. Is β, the angle α is preferably 20 ° or more and 80 ° or less, and the absolute value of the angle β is preferably 15 ° or more and 165 ° or less.

In the aspect, it is preferable that the main surface facing the emission surface has a plurality of groove portions, and the longitudinal direction of the groove portions is inclined from the Y axis when viewed from the + Z direction.
Here, when the counterclockwise angle from the + Y direction in the longitudinal direction of the groove portion viewed from the + Z direction is γ, the absolute value of the angle γ is preferably 15 ° or more and 75 ° or less.

  The surface light source element, together with the support and power source of the surface light source element, are used for lighting devices for direct and indirect lighting applications such as spotlights, display shelves for products, etc., downlights, foot lamps, etc. be able to.

  ADVANTAGE OF THE INVENTION According to this invention, it is excellent in the designability and external appearance, and can provide a highly efficient surface light source element.

It is a typical perspective view of the surface light source element which concerns on the 1st Embodiment of this invention. In the surface light source element which concerns on the 1st Embodiment of this invention, it is a figure which shows advancing of the light inside a light-guide plate observed from the output surface side. It is a figure which shows an example of the recessed part of the surface light source element which concerns on the 1st Embodiment of this invention. It is a figure which shows an example of the recessed part of the surface light source element which concerns on the 1st Embodiment of this invention. It is a figure which shows an example of the recessed part of the surface light source element which concerns on the 1st Embodiment of this invention. It is a figure which shows an example of the recessed part of the surface light source element which concerns on the 1st Embodiment of this invention. It is a figure which shows an example of the recessed part of the surface light source element which concerns on the 1st Embodiment of this invention. It is a figure which shows an example of the recessed part of the surface light source element which concerns on the 1st Embodiment of this invention. In the surface light source element which concerns on the 2nd Embodiment of this invention, it is a figure which shows advancing of the light inside a light-guide plate observed from the output surface side. It is a figure which shows an example of the groove part of the surface light source element which concerns on the 2nd Embodiment of this invention. It is a figure which shows an example of the arrangement | sequence of the groove part of the surface light source element which concerns on the 2nd Embodiment of this invention. It is a perspective view which shows advancing of the light in the surface light source element which concerns on the 3rd Embodiment of this invention. It is a figure which shows the structure of the surface light source element which concerns on an Example. It is a figure which shows angle distribution of the brightness | luminance of the surface light source element which concerns on Example 1. FIG. It is a figure which shows angle distribution of the brightness | luminance of the surface light source element which concerns on Example 6. FIG. It is a figure which shows angle distribution of the brightness | luminance of the surface light source element which concerns on Example 7. FIG. It is a figure which shows angle distribution of the brightness | luminance of the surface light source element which concerns on Example 9. FIG. It is a figure which shows the shape of the recessed part in the surface light source element which concerns on the comparative example 1. FIG. It is a figure which shows angle distribution of the brightness | luminance of the surface light source element which concerns on the comparative example 1. FIG. It is a figure which shows the shape of the recessed part in the surface light source element which concerns on the comparative example 2. FIG. It is a figure which shows angle distribution of the brightness | luminance of the surface light source element which concerns on the comparative example 2. FIG. It is a figure which shows angle distribution of the brightness | luminance of the surface light source element which concerns on the comparative example 3. It is a figure which shows the shape of the convex part in the surface light source element which concerns on the comparative example 4. It is a figure which shows angle distribution of the brightness | luminance of the surface light source element which concerns on the comparative example 4.

  Hereinafter, specific embodiments to which the present invention is applied will be described in detail with reference to the drawings. However, the present invention is not limited to the following embodiment. In addition, for clarity of explanation, the following description and drawings are simplified as appropriate.

(Embodiment 1)
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. FIG. 1 is a schematic perspective view of a surface light source element according to this embodiment. The surface light source element includes a light source 1 and a light guide plate 2. As shown in FIG. 1, in a right-handed coordinate space consisting of an X axis, a Y axis, and a Z axis orthogonal to each other, the light guide plate 2 has a main surface that is substantially parallel to the XY plane and an incident surface 21 that is approximately parallel to the YZ plane. I have. Of the two main surfaces, the main surface located in the + Z direction constitutes the emission surface 22.

  Light emitted from the light source 1 and incident from the incident surface 21 of the light guide plate 2 propagates along the X axis mainly through the internal reflection of the light guide plate 2 and exits from the output surface 22. Hereinafter, a direction in which light mainly propagates in the light guide plate as in the X-axis direction in FIG. 1 is referred to as a light guide direction. As shown in FIG. 1, the surface light source element according to the present embodiment can illuminate only a specific place or object brightly by deflecting the light emitted from the emission surface 22 only in the + Y direction. For this reason, it is not necessary to tilt the illumination device toward the illumination target, and unnecessary light is not emitted to the observation side. Therefore, it is possible to realize a highly efficient surface light source element that is excellent in design and appearance. Here, as shown in FIG. 1, the light emission direction can be represented by an angle θ formed with the Z-axis, and an angle φ formed by projection of the light emission direction onto the XY plane and the X-axis.

  FIG. 2 is a diagram illustrating the progress of light inside the light guide plate 2 observed from the + Z direction (exit surface 22 side). As shown in FIG. 2, a plurality of recesses 3 are formed on the back surface 23 facing the emission surface 22. The concave portion 3 includes a surface a substantially parallel to the XZ plane and a surface b composed of a plurality of planes or one or more curved surfaces. The normal vector in the + Z direction of the surface b at an arbitrary position of the surface b has a component in the + Y direction. The recessed part 3 shown by FIG. 2 has a triangular pyramid shape as an example.

Light incident from the incident surface 21 of the light guide plate 2 has a component in the + Y direction or −Y direction and propagates through the light guide plate 2 by total reflection.
A part of the light L1 propagating with a component in the + Y direction is incident on the surface a substantially parallel to the XZ plane of the recess 3 and is totally reflected by the surface a. Since the surface a is substantially parallel to the XZ plane, the reflected light continues to propagate without being emitted from the inside of the light guide plate 2.

  On the other hand, the light L2 propagating with a component in the -Y direction is incident on the surface b of the recess and is totally reflected by the surface b. Here, since the normal vector in the + Z direction of the surface b has a component in the + Y direction, it is deflected in the + Y direction. Similarly, part of the light propagating with a component in the + Y direction also enters the surface b of the recess and is totally reflected by the surface b in the + Y direction. As shown in FIG. 2, when the reflected light on the surface b deviates from the condition of total reflection with respect to the emission surface 22 of the light guide plate 2, the light is emitted from the emission surface 22.

  Thus, by separately controlling the light propagating with the component in the + Y direction and the light propagating with the component in the -Y direction, the emitted light can be concentrated only in the + Y direction. Therefore, a surface light source element in which light from the emission surface 22 is deflected only in one direction can be realized.

<light source>
Examples of the light source 1 include linear light sources such as cold cathode tubes and hot cathode tubes, and point light sources such as LEDs. One or a plurality of light sources 1 may be arranged on one end face 21 of the light guide plate 2 or on both end faces 21 facing each other. By providing on one end surface 21 of the light guide plate 2, the number of light sources can be reduced, and the weight and size can be reduced. On the other hand, by providing on both end surfaces 21 of the light guide plate 2, the amount of light incident on the light guide plate 2 is increased, and high luminance can be achieved. The number of point light sources may be determined as appropriate. When the number of point light sources is increased, the amount of light incident on the light guide plate 2 is increased, and high brightness can be achieved. When using a plurality of point light sources, it is desirable to arrange them so that the intervals between the point light sources are equal. Thereby, the uniformity between the vicinity of the point light source and the point light source can be improved.

<Light guide plate>
As the material of the light guide plate 2, an acrylic resin such as polymethyl methacrylate (PMMA), a polycarbonate resin (PC), a polystyrene resin (PS), a resin having excellent transparency such as a cycloolefin polymer, or glass can be used. . Among them, PMMA is excellent in terms of lightness and transparency, and PC is excellent in terms of durability.

As a processing method of the light guide plate 2, a method of cutting out from an extruded plate or a cast plate, or a melt molding method such as a heating press or injection molding is preferably used, but it is not limited thereto.
In addition, the manufacturing method in the case where the concave portion 3 is provided in the light guide plate 2 is not particularly limited, but an extrusion molding, an injection molding, or an ultraviolet curable resin using an original shape produced by a photolithographic method, a cutting method or the like is used. 2P (Photo Polymerization) molding method. A suitable molding method may be selected in consideration of the size, shape, and mass productivity of the recess 3.

  The length of the light guide plate 2 in the X-axis direction and the Y-axis direction can be set according to the application. For example, when illuminating a wide place such as an outdoor footlamp or road illumination, or a large object, large illumination that is long in the X and Y axis directions is used. On the other hand, when illuminating a small place such as a table lamp, use a small short illumination in the X and Y axis directions.

  The aspect ratio, which is the ratio of the length of the light guide plate 2 in the X-axis direction and the Y-axis direction, can be changed depending on the place and purpose of installing the illumination. When the length in the X-axis direction is made larger than the length in the Y-axis direction, a large area can be irradiated with a small or small light source, which is highly efficient. In addition, space saving is possible. For this reason, it can be used for display shelves of products, lighting stands on tables, and the like. On the other hand, if the length in the X-axis direction is made smaller than the length in the Y-axis direction, many light sources and large light sources can be used, so that a brighter and lighter surface light source element can be obtained.

<Recess>
The maximum length of the recess 3 in the X-axis direction is desirably 10 μm or more and 1000 μm or less. More desirably, it is 15 μm or more and 700 μm or less. If it is smaller than 10 μm, coloring occurs due to the diffraction phenomenon, and the appearance quality is lowered. Moreover, since the recessed part 3 itself is visually recognized when larger than 1000 micrometers, the quality of an external appearance is reduced.

  The recess 3 includes a surface a substantially parallel to the XZ plane and a surface b formed of a plurality of planes or one or more curved surfaces. The specific shape of the recess 3 is a part or all of a polygonal pyramid, or an elliptical sphere (including a sphere) or a part of a cone. 3 and 4 show cases where the shape of the recess 3 is a triangular pyramid and a quadrangular pyramid, respectively. When the shape of the concave portion 3 is a triangular pyramid or a quadrangular pyramid, the surface b can be composed of a plurality of planes. Therefore, the angle deflected by total reflection on each surface b can be limited. Therefore, it is possible to concentrate light in a specific direction on the + Y direction side of the emission surface 22 and obtain a bright surface light source element in the specific direction.

  As shown in FIG. 3, the surface b of the recess 3 is counterclockwise from the + X direction as viewed from the + Z direction in the direction of the inclination angle α from the XY plane and the direction in which the normal of the surface b is projected onto the XY plane. It can be defined by the angle β. Here, the possible range of the angle α is 0 ° <α <90 °, but is preferably 20 ° or more and 80 ° or less. Moreover, 30 degrees or more and 70 degrees or less are more desirable, and 35 degrees or more and 65 degrees or less are further desirable. In this range, when the light is totally reflected by the surface b, the light is efficiently extracted from the light guide plate. The range that the angle β can take is 0 ° <β <180 ° when deflecting in the + Y direction, but is preferably 15 ° or more and 165 ° or less. Moreover, 25 degrees or more and 155 degrees or less are more desirable, and 30 degrees or more and 150 degrees or less are more desirable. In this range, light is effectively deflected in the + Y direction. When the angle β is smaller than 15 ° or larger than 165 °, the light cannot be deflected in the + Y direction by total reflection, and the light traveling in the −Y direction increases.

In the case of deflecting in the −Y direction, the range that the angle β can take is −180 ° <β <0 °, but is preferably −165 ° or more and −15 ° or less. Further, it is more preferably −155 ° or more and −25 ° or less, and further preferably −150 ° or more and −30 ° or less. In this range, light is effectively deflected in the -Y direction. If the angle β is smaller than −165 ° or larger than −15 °, the light cannot be deflected in the −Y direction by total reflection, and the light traveling in the + Y direction increases.
That is, the absolute value of the angle β is preferably 15 ° or more and 165 ° or less, more preferably 25 ° or more and 155 ° or less, and 30 ° or more and 150 ° regardless of whether the light is polarized in the + Y direction or the −Y direction. The following is more desirable.

  5, FIG. 6, and FIG. 7 show a case where the shape of the recess 3 is an elliptical sphere, a sphere, and a part of a cone, respectively. By making the shape of the concave portion 3 a part of an elliptic sphere, a sphere, or a cone, the surface b can be configured by a curved surface. In this case, it is possible to increase the range of angles deflected in the + Y direction by total reflection on the surface b. Therefore, a surface light source element suitable for uniformly irradiating a wide place on the + Y direction side of the emission surface 22 can be obtained.

  As shown in FIG. 8, the recess 3 may be provided with a flat surface substantially parallel to the XY plane on the upper surface. Manufacturing is facilitated by providing a flat surface.

  The arrangement method of the recesses 3 can be arbitrarily selected according to the purpose and the manufacturing method, such as a lattice shape, a staggered lattice shape, or a random arrangement. In a place where many concave portions 3 are provided, more light is extracted. Therefore, in order to obtain a surface light source element with uniform brightness, the density of the recesses 3 is modulated in the plane of the light guide plate 2 such that the recesses 3 are provided sparsely in a place near the light source and densely in a place far from the light source. It is desirable.

  The interval between two adjacent recesses 3 is preferably 10 μm or more and 5000 μm or less. If it is smaller than 10 μm, coloring occurs due to the diffraction phenomenon, and the appearance quality is lowered. On the other hand, when it is larger than 5000 μm, the recess 3 itself is visually recognized, so that the quality of the appearance is lowered.

  As described above, in the surface light source element according to the present embodiment, light is deflected in a specific direction on the light emission surface orthogonal to the incident surface on which light from the light source is incident, and a specific place or object is By irradiating, it is possible to obtain a surface light source element that does not emit light in an unnecessary direction, has high efficiency, and is excellent in design. In addition, by using the surface light source element of the present invention, it is possible to obtain a lighting device having a good appearance because it illuminates a product or place brightly and does not emit light in an unnecessary direction with high efficiency.

(Embodiment 2)
Next, a second embodiment of the present invention will be described in detail with reference to the drawings. In the light guide plate 2 according to the present embodiment, a groove 4 is formed instead of the recess 3 in the first embodiment. A plurality of the groove portions 4 are formed on the back surface 23 facing the emission surface 22. Here, the longitudinal direction of the groove 4 is inclined from the Y axis as viewed from the + Z direction. Other configurations are the same as those in the first embodiment.

  FIG. 9 is a diagram illustrating the progress of light inside the light guide plate 2 observed from the + Z direction. Light incident from the incident surface 21 of the light guide plate 2 propagates inside the light guide plate 2 with a component in the + Y direction or the −Y direction. The light L11 propagating with a component in the + Y direction is incident on the surface 41 of the groove 4 facing the incident surface 21. At this time, since the surface 41 is a surface inclined in the + Y direction, it is totally reflected by the surface 41 and deflected in the + Y direction. Further, the total reflection reflects light from the light exiting surface 22 of the light guide plate 2 in order to deviate from the condition of total reflection with respect to the light exiting surface 22 of the light guide plate 2.

  The light L12 propagating with a component in the −Y direction also enters the surface 41 of the groove 4 facing the incident surface 21 and is totally reflected. At this time, the light is further greatly deflected in the + Y direction by total reflection and is emitted from the light exit surface 22 of the light guide plate 2. A surface 42 of the groove 4 that does not face the incident surface 21 is a shadow of the surface 41 for light propagating through the light guide plate 2. Accordingly, there is no light incident on the surface 42 and totally reflected and deflected in the −Y direction, and a surface light source element in which light from the emission surface 22 is deflected only in one direction can be realized.

<Groove>
The width of the groove 4 is preferably 10 μm or more and 1000 μm or less. More desirably, it is 15 μm or more and 700 μm or less. If it is smaller than 10 μm, coloring occurs due to the diffraction phenomenon, and the appearance quality is lowered. On the other hand, if it is larger than 1000 μm, the groove part itself is visually recognized, so that the quality of the appearance is lowered.

  For example, as shown in FIG. 10, the inclination of the groove 4 can be defined by a counterclockwise angle γ from the + Y direction. The possible range of the inclination angle γ of the groove 4 is 0 ° <γ <90 ° when deflecting in the + Y direction, but is preferably 15 ° or more and 75 ° or less. Moreover, 25 degrees or more and 65 degrees or less are more desirable, and 30 degrees or more and 60 degrees or less are further desirable. In this range, the emitted light is effectively deflected in the + Y direction. If the angle γ is smaller than 15 ° or larger than 75 °, the light cannot be deflected in the + Y direction by total reflection, and the light traveling in the −Y direction increases.

In the case of deflecting in the −Y direction, the range that the angle γ can take is −90 ° <γ <0 °, but is preferably −75 ° or more and −15 ° or less. Further, it is more preferably −65 ° or more and −25 ° or less, and further preferably −60 ° or more and −30 ° or less. In this range, the emitted light is effectively deflected in the -Y direction. If the angle γ is smaller than −75 ° or larger than −15 °, the light cannot be deflected in the −Y direction by total reflection, and the light toward the + Y direction increases.
That is, the absolute value of the angle γ is preferably 15 ° or more and 75 ° or less, more preferably 25 ° or more and 65 ° or less, and more preferably 30 ° or more and 60 ° regardless of whether the light is polarized in the + Y direction or the −Y direction. The following is more desirable.

  The groove 4 can be a lenticular lens or a prism. In the case of a prism, the inclination angle of the inclined surface from the XY plane is desirably 42 ° or more. Here, in a general light guide plate material, the refractive index n is 1.5 to 1.6. Therefore, by making the slope larger than the critical angle in this material, it is possible to reduce the light incident on the surface of the prism that does not oppose the incident surface of the light guide plate, and to concentrate the light only in one direction.

  The arrangement of the grooves 4 can be arbitrarily set according to the purpose. In a place where many grooves 4 are provided, more light is extracted. Therefore, in order to obtain a surface light source element with uniform luminance, the density of the groove 4 can be modulated within the surface of the light guide plate 2 such that the groove 4 is provided sparsely at a location near the light source and dense at a location far away. desirable.

  The interval between two adjacent groove portions 4 is preferably 10 μm or more and 5000 μm or less. If it is smaller than 10 μm, coloring occurs due to the diffraction phenomenon, and the appearance quality is lowered. On the other hand, if it is larger than 5000 μm, the groove 4 itself is visually recognized, so that the quality of the appearance is lowered. In addition, when providing the light source 1 in the both ends of the light-guide plate 2, as shown in FIG. 11, you may provide the groove part 4 so that each light source may be opposed.

(Embodiment 3)
Next, a third embodiment of the present invention will be described in detail with reference to the drawings. The light guide plate 2 according to the present embodiment includes an outgoing light control member 50 having a plurality of convex portions 5 on the outgoing surface 22 instead of the concave portions 3 in the first embodiment. The convex portion 5 has a substantially frustoconical shape, and is in optical contact with the light guide plate 2. Here, one side of the cross-sectional shape passing through the upper and lower surfaces of the truncated cone and parallel to the YZ plane is substantially parallel to the Z axis. Other configurations are the same as those in the first embodiment.

  FIG. 9 is a diagram illustrating the progress of light inside the light guide plate 2 and the emitted light control member 50 having the convex portion 5. When the light propagating inside the light guide plate 2 enters the portion of the convex portion 5 in close contact with the light guide plate 2, the light enters the convex portion 5 and is totally reflected by the side surface of the convex portion 5 having a truncated cone shape. The light is emitted from the control member 50. At this time, the light L22 traveling in the convex portion 5 with a component in the −Y direction is totally reflected by the side surface on the −Y direction side of the truncated cone, converted into the + Y direction, and emitted. On the other hand, the light L21 traveling in the convex portion 5 with a component in the + Y direction is totally reflected on the side surface on the + Y direction side of the truncated cone, but the side surface on the + Y direction side is inclined with respect to the Z axis. Therefore, the light is only slightly converted to the + Z direction while remaining in the + Y direction. As described above, since the light is concentrated in the + Y direction after total reflection inside the convex portion 5, a surface light source element in which the light is deflected only in one direction can be realized.

<Emission light control member>
The maximum width in the X-axis direction of the convex portion 5 is desirably 10 μm or more and 1000 μm or less. More desirably, it is 15 μm or more and 700 μm or less. If it is smaller than 10 μm, coloring occurs due to diffraction phenomenon, and the appearance quality is lowered. On the other hand, if it is larger than 1000 μm, the convex portion 5 itself is visually recognized, so that the quality of the appearance is lowered.

  The arrangement method of the convex portions 5 can be arbitrarily selected according to the purpose and the manufacturing method, such as a lattice shape, a staggered lattice shape, or a random arrangement. In a place where many convex portions 5 are provided, more light is extracted. Therefore, in order to obtain a surface light source element with uniform brightness, the density of the convex portions 5 is modulated in the plane of the light guide plate 2 such that the convex portions 5 are provided sparsely at a location close to the light source and dense at a remote location. It is desirable.

  The interval between two adjacent convex portions 5 is preferably 10 μm or more and 5000 μm or less. If it is smaller than 10 μm, coloring occurs due to the diffraction phenomenon, and the appearance quality is lowered. On the other hand, when it is larger than 5000 μm, the convex portion 5 itself is visually recognized, so that the quality of the appearance is lowered.

  In order to optically adhere the light guide plate 2 and the outgoing light control member 50 having the convex portion 5, a fixed layer may be provided between the light guide plate 2 and the outgoing light control member 50. Examples of the fixing layer include an adhesive, a pressure-sensitive adhesive, an adhesive, a photocurable resin, and the like, and a photocurable adhesive is preferably used from the viewpoint of handleability and productivity. Examples of the adhesive material include those based on an appropriate polymer such as rubber, acrylic, vinyl alkyl ether, silicone, polystyrene, polyurethane, polyether, polyamide, and styrene. Among them, an acrylic pressure-sensitive adhesive material mainly composed of a polymer mainly composed of an alkyl ester of acrylic acid or methacrylic acid is preferable because it is excellent in transparency, weather resistance, and heat resistance. Adhesives include, for example, conductive inorganic particles such as silica, alumina, titania and zirconia, tin oxide and indium oxide, cadmium oxide and nonmony oxide, and organic particles such as crosslinked or uncrosslinked polymers. One kind or two or more kinds of suitable transparent particles can be contained to obtain a light diffusion type.

  Furthermore, the surface modification of the light guide plate 2 and the material forming the convex portions 5 of the outgoing light control member 50 are made self-adhesive so that the light guide plate 2 and the outgoing light control member 50 do not go through a fixed layer. You may make it optically adhere to. In this case, it is preferable to provide a flat portion at the tip of the convex portion 5. When the flat portion is in close contact, the width of the optical close contact portion can be obtained with high accuracy.

  Further, the surface shape of the outgoing light control member 50 is formed on a transparent substrate by using a stamper or a female die, etc., by a hot press method, a 2P method by ultraviolet curing, a casting method by thermal curing, injection molding, or the like. be able to. As the transparent substrate, resin such as acrylic resin, polycarbonate resin, polystyrene resin, cycloolefin polymer, or glass is used. In the present embodiment, it is preferable to transfer the shape with a photocurable resin onto a transparent base material using an acrylic resin or a polycarbonate resin.

  The photocurable resin used when transferring to the base material determines the optical performance of the produced outgoing light control member 50 and is preferably selected as appropriate according to the desired performance. As a component of the photocurable resin, monomers or oligomers that can be radically polymerized are used alone or in combination of two or more. However, it is usually preferable to use two or more, and the mechanical requirements for the outgoing light control member 50 are required. Strength, impact resistance, heat resistance, surface hardness and the like can be imparted. Specific examples of the component include aliphatic, alicyclic and aromatic monomers, or ester-type (meth) acrylate obtained by condensation reaction of polyalcohol with acrylic acid or methacrylic acid, or two or more in the molecule. A urethane poly (meth) acrylate obtained by a urethanization reaction between an isocyanate compound having an isocyanate group and a (meth) acrylate containing a hydroxyl group or a thiol group, a compound having at least two epoxy groups in the molecule, and an acrylic Polyester (meta) obtained by condensation reaction with epoxy poly (meth) acrylate obtained by glycidyl group ring-opening reaction with acid or methacrylic acid, or saturated or unsaturated polycarboxylic acid, polyhydric alcohol and (meth) acrylic acid ) (Meth) acryloyl functional monomers or oligomers such as acrylates And, styrene, chlorostyrene, bromostyrene, and vinyl compounds such as divinylbenzene, diethylene glycol bis allyl carbonate, diallyl phthalate, (meth) allyl compounds such as diallyl biphenylene rate and the like. These monomers may be used individually by 1 type, and may mix 2 or more types.

  The stamper used for producing the emission light control member 50 is, for example, coating a negative or positive photosensitive resin on a glass substrate and exposing the photosensitive resin through a photomask or using a laser drawing apparatus. It can produce by performing electroforming after exposing and developing. It can also be produced by cutting.

  On the light exit surface of the exit light control member 50, surface irregularities may be directly transferred, or a diffusion layer may be provided by applying a diffuser liquid mixed with light-transmitting fine particles. The viewing angle characteristics are smoothed by the diffusion layer, and good quality can be obtained.

  Examples of the present invention will be described below, but the present invention is not limited to these examples. With respect to the surface light source element shown in the schematic diagram of FIG. 13, the angular distribution of luminance was analyzed using illumination design analysis software LightTools (registered trademark). The conditions used for the analysis are described below.

As shown in FIG. 13, the light source 1 has a rectangular parallelepiped side with a height of 4 mm and a width of 20 mm as a light emitting part, and the angular characteristics of light emission have a Lambertian distribution.
The size of the light guide plate 2 was 20 mm in the Y direction, 300 mm in the X direction, and 4 mm in thickness. The material of the light guide plate 2 was PMMA (refractive index 1.49). One light source 1 is installed on the end surface 21 of the light guide plate 2, and a reflection plate that performs diffuse reflection is disposed on the side surface of the light guide plate 2 and on the outside of the bottom surface 23 of the light guide plate 2. A concave portion or a groove portion is provided on the surface of the light guide plate 2 facing the output surface 22, or an output light control plate having a convex portion that is optically in close contact with the output surface 22 of the light guide plate 2.

  Using the above model, light was analyzed from the exit surface of the light guide plate by simulation, and each angle luminance L (θ, φ) near the center of the light guide plate was obtained. Here, the inclination of the emitted light from the + Z direction is θ, and the angle obtained in the counterclockwise direction from the + X direction when viewed from the + Z direction in the direction projected onto the XY plane in this direction is φ. At this time, when the luminance has a component in the + Y direction, φ is larger than 0 ° and smaller than 180 °.

Of the emitted light, a light beam I (+ Y) emitted with a component in the + Y direction and a light beam I (−Y) emitted with a component in the −Y direction are respectively expressed by the following equations (1), Calculated from (2).

Furthermore, the ratio of I (+ Y) to the sum of I (+ Y) and I (−Y) was calculated. Table 1 shows the ratio of I (+ Y) in Examples and Comparative Examples.

Example 1
As Example 1, a simulation was performed on a surface light source element having a recess as shown in FIG. The concave portion is a triangular pyramid obtained by dividing a regular quadrangular pyramid whose bottom surface on the XY plane is a square having a side of 100 μm into two by a plane (XZ plane) including the diagonal line (X axis) of the bottom surface and perpendicular to the bottom surface. The angle β obtained from the + Z direction counterclockwise when viewed from the + Z direction in the direction of inclination α of the surface b from the XY plane and the normal of the surface b projected onto the XY plane is α = 55 °, β = 45 °.

  FIG. 14 shows the luminance with respect to φ at each θ (= 0 °, 20 °, 40 °, 60 °, 80 °) shown in FIG. As shown in FIG. 14, light is concentrated in the + Y direction. Moreover, as shown in Table 1, the ratio with respect to the light radiate | emitted to the whole is 66%. Since the rate of emission in the −Y direction is small, there is no light emitted from the surface light source element when observed from the −Y direction. Therefore, a surface light source element having a good design property in which only the object to be illuminated is brightly illuminated can be obtained. In addition, since the outgoing angle range is very narrow, the surface light source element is suitable for irradiating only a specific object.

(Examples 2 to 5)
As Example 2-5, it simulated about the surface light source element which has a recessed part as shown in FIG. Example 2 has α = 55 °, β = 30 °, Example 3 has α = 55 °, β = 60 °, Example 4 has α = 45 °, β = 45 °, and Example 5 has α = 35 °. , Β = 45 °. The other conditions are the same as in the first embodiment. As shown in Table 1, also in Examples 2 to 5, it is possible to obtain surface light source elements that are efficiently deflected in the + Y direction and have a high ratio of emission in the + Y direction and suitable for irradiation in only one direction. It is. In addition, it is possible to adapt the direction of emission by appropriately selecting the angles α and β according to the position of the irradiation target, the angle from illumination, and the like.

(Example 6)
As Example 6, a simulation was performed on a surface light source element having a recess as shown in FIG. The recess has a shape composed of a part of a hemisphere having a diameter of 200 μm. The angle α obtained from the + Z direction counterclockwise as viewed from the + Z direction in the direction α of the plane b projected from the XY plane and the normal of the surface b onto the XY plane is α <90 °, 45 ° <Β <135 °.

  FIG. 15 shows the luminance with respect to φ at each θ (= 0 °, 20 °, 40 °, 60 °, 80 °). As shown in FIG. 15, light is deflected in the + Y direction. Further, as shown in Table 1, 58% of light is emitted in the + Y direction. Therefore, a surface light source element having a good design property in which only the object to be illuminated is brightly illuminated can be obtained. In addition, since the angular characteristics are smooth, the surface light source element is suitable for irradiating a wide area or a large object with a good appearance whose brightness does not change abruptly depending on the angle.

(Examples 7 and 8)
As Examples 7 and 8, a simulation was performed on a surface light source element having prism-shaped grooves having a width of 100 μm and an apex angle of 90 ° as shown in FIG. As the angle γ taken counterclockwise from the + Y direction in the longitudinal direction of the groove, γ = 45 ° in the seventh embodiment and γ = 30 ° in the eighth embodiment. The luminance with respect to φ at each θ (= 0 °, 20 °, 40 °, 60 °, 80 °) in Example 7 is shown in FIG. As shown in FIG. 16, light is deflected in the + Y direction. Further, as shown in Table 1, 55% of light was emitted in the + Y direction in Example 7 and 58% in Example 8. In the case where the groove portion formed of the prism is provided as in the seventh and eighth embodiments, a surface light source element suitable for irradiating only a specific element can be obtained by concentrating light only in a specific narrow angle range.

Example 9
As Example 9, a simulation was performed on a surface light source element using an emitted light control member as shown in FIG. The emitted light control member has a convex portion that is optically in close contact with the light guide plate, and the convex portion is a truncated cone having a width of 100 μm. One side on the −Y direction side is parallel to the Z axis in a cross section that passes through the center of the lower surface (contact surface with the light guide plate) of the truncated cone and is parallel to the YZ plane. The inclination angle of one side on the −Y direction side facing this side from the XY plane is 55 °.

  FIG. 17 shows the luminance with respect to φ at each θ (= 0 °, 20 °, 40 °, 60 °, 80 °). As shown in FIG. 17, light is deflected in the + Y direction. As shown in Table 1, in Example 9, 69% of light was emitted in the + Y direction. That is, the light emitted in the −Y direction is efficiently reduced, and the observer is not directly irradiated from the surface light source element when observed from the −Y direction. That is, it is possible to obtain a surface light source element that can irradiate an object installed in the + Y direction with particularly good appearance.

(Comparative Example 1)
As Comparative Example 1, a simulation was performed on a surface light source element having a recess as shown in FIG. The concave portion is formed of a regular quadrangular pyramid having a side of 100 μm and an inclined angle of 55 °. The luminance with respect to φ at each θ is shown in FIG. As shown in FIG. 19, at the same time as being deflected in the + Y direction, it is also deflected in the -Y direction. Therefore, as shown in Table 1, the rate of emission in the + Y direction is 50%. Therefore, it is not suitable for irradiating a specific object.

(Comparative Example 2)
As Comparative Example 2, a simulation was performed on a surface light source element having a concave portion formed of a hemisphere having a diameter of 100 μm as shown in FIG. The luminance with respect to φ at each θ is shown in FIG. As shown in FIG. 21, light is emitted in all directions. Therefore, as shown in Table 1, the component deflected in the + Y direction is 50%. When observed from a specific direction, there is light reaching the observer from the surface light source element, and the appearance quality deteriorates.

(Comparative Example 3)
As Comparative Example 3, a simulation was performed for a surface light source element having prism-shaped grooves having a width of 100 μm and an apex angle of 90 ° as shown in FIG. If the angle γ is taken counterclockwise from the + Y direction, then γ = 0 °. The luminance with respect to φ at each θ (= 0 °, 20 °, 40 °, 60 °, 80 °) is shown in FIG. As shown in FIG. 22, it is deflected in the + Y direction and simultaneously in the -Y direction. Therefore, as shown in Table 1, the rate of emission in the + Y direction is 50%. Therefore, it is not suitable for irradiating a specific object.

(Comparative Example 4)
As Comparative Example 4, a simulation was performed for a surface light source element using an emitted light control member as shown in FIG. The convex part of the emitted light control member has a truncated cone shape with a width of 100 μm and an inclination angle of 60 °. FIG. 24 shows the luminance with respect to φ at each θ (= 0 °, 20 °, 40 °, 60 °, 80 °). As shown in FIG. 24, the same amount of the component deflected in the −Y direction exists at the same time as the component deflected in the + Y direction on the side surface of the convex portion. Therefore, as shown in Table 1, the rate of emission in the + Y direction is 50%. Therefore, it is not suitable for irradiating an object existing in a specific direction.

  The surface light source element described above can deflect light in one direction on the light emitting surface orthogonal to the light incident surface of the light guide plate. Therefore, the lighting device including the surface light source element does not emit light in unnecessary directions, has high efficiency, and has a good appearance. Specifically, it is suitable for direct or indirect lighting such as spotlights, display lighting used for display shelves of goods, downlights, foot lamps, and the like.

  This application claims the priority on the basis of Japanese application Japanese Patent Application No. 2010-226709 for which it applied on October 6, 2010, and takes in those the indications of all here.

1: Light source 2: Light guide plate 21: Light entrance plate entrance surface 22: Light guide plate exit surface 23: Light guide plate bottom surface 3: Concave portion a: Concave surface b: Concave surface 4: Groove portion 41: Groove portion Surface 42 facing the incident surface of the optical plate: Of the groove portion, a surface not facing the incident surface of the light guide plate 5: Convex portion 50: outgoing light control member α: inclination angle β of the surface b from the XY plane β: viewed from the + Z direction The angle γ counterclockwise from the + X direction of the projection of the normal vector of the surface b onto the XY plane γ: the counterclockwise angle θ from the + Y direction in the longitudinal direction of the groove portion θ: the inclination φ of the emitted light from the + Z direction φ: Angle L (θ, φ) of projection from the + X direction in the projection of the light emission direction seen from the + Z direction onto the XY plane: Luminance I (+ Y) of light emitted in the direction determined by θ and φ: + Y A light beam I (−Y) emitted from the exit surface of the light guide plate with a component in the direction: Light beam emitted from the emission surface of the plate

Claims (8)

A light source;
The light emitted from the light source is incident on one end surface, propagates through the inside, and is output from one main surface orthogonal to the end surface, and
In the light guide plate, when considering a right-handed coordinate space consisting of an X axis, a Y axis, and a Z axis orthogonal to each other,
The one end face constituting the incident surface is substantially parallel to the YZ plane,
The one main surface constituting the emission surface is substantially parallel to the XY plane and is positioned in the + Z direction with respect to the other main surface,
The outgoing light from the outgoing surface has more of the other component than either one of the components in the −Y direction and the + Y direction, and has the component in this direction, from the outgoing surface of the light guide plate. A surface light source element in which the emitted light beam is 55% or more of the entire emitted light beam. Having a plurality of recesses on the main surface facing the exit surface;
The recess is
A first surface substantially parallel to the XZ plane;
A second surface comprising a flat surface or a curved surface,
The normal vector in the + Z direction at an arbitrary location on the second surface has a component that the emitted light has more of components in the −Y direction and the + Y direction. The surface light source element according to claim 1.   The surface light source element according to claim 2, wherein the shape of the concave portion is a part or all of a polygonal pyramid, or a part of an elliptical sphere or a cone. The inclination angle of the second surface from the XY plane is α, and the projection of the normal vector in the + Z direction of the second surface viewed from the + Z direction onto the XY plane is the counterclockwise angle from the + X direction to β. Then,
The surface light source element according to claim 2, wherein the angle α is 20 ° or more and 80 ° or less, and the absolute value of the angle β is 15 ° or more and 165 ° or less. Having a plurality of grooves on the main surface facing the exit surface;
The surface light source element according to claim 1, wherein the longitudinal direction of the groove portion is inclined from the Y axis when viewed from the + Z direction. When the counterclockwise angle from the + Y direction in the longitudinal direction of the groove portion viewed from the + Z direction is γ,
The surface light source element according to claim 5, wherein an absolute value of the angle γ is 15 ° or more and 75 ° or less. An emission light control member having a main surface substantially parallel to the XY plane and disposed on the emission surface side of the light guide plate;
The emitted light control member is
The main surface on the light guide plate side has a plurality of frustoconical convex portions that are in close contact with the light guide plate,
The convex portion is
2. The surface light source according to claim 1, wherein a trapezoid is formed in a cross section passing through the centers of the upper and lower surfaces of the truncated cone and parallel to the YZ plane, and one side of the trapezoid is substantially parallel to the Z axis. element.   A lighting device comprising: the surface light source element according to claim 1, a support for the surface light source element, and a power source.

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