Patent Publication Number: US-2022221130-A1

Title: Illumination device

Description:
TECHNICAL FIELD 
     The present invention relates to an illumination device. 
     BACKGROUND ART 
     There has been proposed an illumination device attached to a concave part of a ceiling and having a form of a simulative skylight (see Patent Reference 1, for example). This illumination device includes an illumination panel attached to the concave part of the ceiling and a side wall around the illumination panel. The side wall includes triangular light-emitting regions that can be controlled independently, and simulates a sunny part and a shady part. The sunny part and the shady part simulate a sunny region that wound be formed by light coming in through a skylight if the illumination panel were an actual skylight and a shady region not irradiated with light. 
     PRIOR ART REFERENCE 
     Patent Reference 
     Patent Reference 1: Japanese Patent No. 6081663 
     SUMMARY OF THE INVENTION 
     Problem to be Solved by the Invention 
     However, the Patent Reference 1 has not disclosed how each of the triangular light-emitting regions of the illumination device is independently made to light up, and the relationship between the lighting/non-lighting of the triangular light-emitting regions and the control of a light source is unclear. Thus, when independent lighting/non-lighting control is performed on each of the plurality of triangular light-emitting regions, there is a problem in that the lighting/non-lighting switching stands out and that makes an observer feel unnaturalness. 
     An object of the present invention, which has been made to resolve the above-described problem of the conventional technology, is to provide an illumination device capable of providing the observer with natural scenery as if incoming light from the sun were shining through a light-emitting panel even in an environment with no actual incoming light from the sun. 
     Means for Solving the Problem 
     An illumination device according to an aspect of the present invention includes a frame forming part that is provided at at least one position on an end part of a light-emitting panel having a light emission surface or in a vicinity of the light-emitting panel and includes a bright part region and a dark part region, a light source that emits light to be incident upon the frame forming part, and a light amount regulation part that makes intensity of light heading for a space facing the light emission surface from the dark part region weaker than intensity of light heading for the space from the bright part region in the light entering the frame forming part from the light source, or makes the intensity of the light heading for the space from the bright part region stronger than the intensity of the light heading for the space from the dark part region in the light entering the frame forming part from the light source. 
     Effect of the Invention 
     By using the present invention, it is possible to provide the observer with more natural scenery as if incoming light from the sun were shining through the light-emitting panel. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an exploded perspective view schematically showing a configuration example of an illumination device according to a first embodiment of the present invention. 
         FIG. 2  is an external perspective view schematically showing the configuration example of the illumination device according to the first embodiment. 
         FIG. 3  is a schematic cross-sectional view of the illumination device in  FIG. 2  taken along the line in  FIG. 2 . 
         FIG. 4  is a schematic plan view showing the illumination device in  FIG. 2  as viewed in a −Z direction. 
         FIG. 5  is a perspective view showing a bright part region and a dark part region on a frame-like member of the illumination device according to the first embodiment. 
         FIG. 6  is a block diagram showing a configuration example of a control system of the illumination device according to the first embodiment. 
         FIG. 7  is a schematic diagram showing an example of a state of the illumination device according to the first embodiment observed when the illumination device is looked up at from below. 
         FIG. 8  is a principal part cross-sectional view schematically showing a configuration example of the illumination device according to the first embodiment. 
         FIG. 9A  is a front view showing an example of the bright part region and the dark part region of the frame-like member of the illumination device according to the first embodiment, and  FIG. 9B  is a schematic cross-sectional view taken along the line IX-IX in  FIG. 9A . 
         FIG. 10  is a diagram showing an example of the relationship among the bright part region, the dark part region and a virtual light source in a frame-like member of an illumination device according to a modification of the first embodiment. 
         FIG. 11  is a perspective view showing the bright part region and the dark part region on the frame-like member of the illumination device according to the modification of the first embodiment. 
         FIG. 12  is a schematic diagram showing an example of a state of the illumination device according to the modification of the first embodiment observed when the illumination device is looked up at from below. 
         FIG. 13  is a principal part cross-sectional view schematically showing a configuration example of an illumination device according to a second embodiment of the present invention. 
         FIG. 14  is a principal part cross-sectional view schematically showing a configuration example of an illumination device according to a third embodiment of the present invention. 
         FIG. 15A  is a front view showing an example of the bright part region and the dark part region on a frame-like member of the illumination device according to the third embodiment, and  FIG. 15B  is a schematic cross-sectional view taken along the line XV-XV in  FIG. 15A . 
         FIG. 16  is a principal part cross-sectional view schematically showing a configuration example of an illumination device according to a fourth embodiment of the present invention. 
         FIG. 17  is a rear view showing an example of a frame-like member and a light source unit of the illumination device according to a fourth embodiment. 
         FIG. 18  is a principal part cross-sectional view schematically showing a configuration example of an illumination device according to a modification of the fourth embodiment. 
         FIG. 19  is a schematic diagram showing an example of a state of an illumination device according to a fifth embodiment of the present invention observed when the illumination device is looked up at from below. 
         FIG. 20  is a cross-sectional view schematically showing a configuration example of the illumination device according to the fifth embodiment. 
         FIG. 21A  is a principal part perspective view schematically showing a configuration example of a frame-like member of an illumination device according to the fifth embodiment, and  FIG. 21B  is a schematic cross-sectional view taken along the line XXI-XXI in  FIG. 21A . 
         FIG. 22  is a principal part cross-sectional view schematically showing a configuration example of an illumination device according to a sixth embodiment of the present invention. 
         FIG. 23  is a cross-sectional view schematically showing a configuration example of an illumination device according to a seventh embodiment of the present invention. 
         FIG. 24  is a principal part cross-sectional view schematically showing a configuration example of an illumination device according to the seventh embodiment. 
         FIG. 25  is an exploded perspective view schematically showing a configuration example of a light source unit, a light reflection diffusion member and a frame-like member of an illumination device according to an eighth embodiment of the present invention. 
         FIG. 26  is a perspective view schematically showing the configuration example of the illumination device according to the eighth embodiment. 
         FIG. 27  is a rear view of the frame-like member of the illumination device according to the eighth embodiment as viewed from a back side. 
         FIG. 28  is a schematic cross-sectional view showing a configuration example of an illumination device according to a modification of the first embodiment. 
         FIG. 29  is a schematic cross-sectional view showing another configuration example of the illumination device according to the modification of the first embodiment. 
         FIG. 30  is a schematic cross-sectional view showing another configuration example of the illumination device according to the modification of the first embodiment. 
     
    
    
     MODE FOR CARRYING OUT THE INVENTION 
     An illumination device according to each embodiment of the present invention will be described below with reference to the drawings. The following embodiments are just examples and a variety of modifications are possible within the scope of the present invention. 
     Dimensions and reduction scales of illustrated components can vary from drawing to drawing. Coordinate axes of an XYZ orthogonal coordinate system are shown in the drawings. A Z direction is a normal direction of a light emission surface of a light-emitting panel. Incidentally, in a case where the light emission surface of the light-emitting panel includes a curved surface, an inclined surface, or both of a curved surface and an inclined surface, the Z direction may be defined as a normal direction of a central part of the light emission surface or a direction represented by the sum total of normal vectors of the light emission surface. A+Z direction represents a side in a traveling direction of light emitted from the light emission surface. For example, when the illumination device is attached to a ceiling as a horizontal surface, the +Z direction is a vertical downward direction and the −Z direction is a vertical upward direction. An X direction and a Y direction are directions orthogonal to the Z direction. When the illumination device is attached to a ceiling as a horizontal surface, the X direction and the Y direction are horizontal directions. In the following description, a +Z direction side with respect to the center of the light-emitting panel can be referred to as a front or a front side, and a −Z direction side in a direction opposite to the +Z direction side can be referred to as a rear or a back side. Further, with respect to an arbitrary position on the light emission surface of the light-emitting panel, a side heading towards an end part or the outside of the light emission surface like ±X direction sides and ±Y direction sides can be referred to as a lateral direction or a side face&#39;s side. Furthermore, while components in the drawings that are the same as each other or corresponding to each other are basically assigned the same reference character throughout the drawings, there are cases where different reference characters are assigned to such components in order to explain different features. 
     (1) First Embodiment 
     (1-1) Configuration 
       FIG. 1  is an exploded perspective view schematically showing a configuration example of an illumination device  1  according to a first embodiment.  FIG. 2  is an external perspective view schematically showing the configuration example of the illumination device  1 .  FIG. 3  is a schematic cross-sectional view of the illumination device  1  in  FIG. 2  taken along the line in  FIG. 2 .  FIG. 4  is a schematic plan view showing the illumination device  1  in  FIG. 2  as viewed in the −Z direction.  FIG. 5  is a perspective view showing a bright part region  131  and a dark part region  132  on a frame-like member  120  of the illumination device  1 . 
     The illumination device  1  includes a frame forming part  12  provided at at least one position in an end part of a light-emitting panel  110  having a light emission surface  111  or in the vicinity of the light-emitting panel  110 , a light source unit  140  that emits light towards the frame forming part  12 , and a light amount regulation part  22 . 
     The frame forming part  12  is provided in a predetermined region in an end part of the light-emitting panel  110 , for example. Here, the end part of the light-emitting panel  110  means a region including a side face of the light-emitting panel  110 . Incidentally, the end part of the light-emitting panel  110  includes not only the side face but also parts of a front surface and a back surface of the light-emitting panel  110  (predetermined regions) connected to the side face. Here, the side face of the light-emitting panel  110  is, for example, a surface facing sideways and contacting an edge part of the front surface as the surface where the light emission surface  111  is formed. The back surface of the light-emitting panel  110  is, for example, a surface on the side opposite to the front surface. 
     The frame forming part  12  is provided in a predetermined region including a certain position in the vicinity of the light-emitting panel  110 , for example. Here, the vicinity of the light-emitting panel  110  is a concept including a space facing the side face of the light-emitting panel  110 , a space facing the front surface of the light-emitting panel  110  and a space facing the back surface of the light-emitting panel  110 . 
       FIG. 1  shows an example in which the illumination device  1  includes the frame-like member  120  as an example of the frame forming part  12  and includes a mask  122  as an example of the light amount regulation part  22 . The frame-like member  120  may be provided in a predetermined region in front of the light-emitting panel  110 , for example. The frame-like member  120  may also be provided in a predetermined region lateral to the light-emitting panel  110 , for example. The frame-like member  120  may also be provided in a predetermined region to the rear of the light-emitting panel  110 , for example. Incidentally,  FIG. 3  shows an example in which the frame-like member  120  is provided at a position in front of the light-emitting panel  110  and contacting the end part of the light-emitting panel  110 . 
     The frame-like member  120  may be arranged to surround at least one of a space  112  facing the light emission surface  111  and the light-emitting panel  110 . The frame-like member  120  may also be arranged to surround both of the space  112  and the light-emitting panel  110 . For example, the frame-like member  120  may be arranged to demarcate an outer edge of the space  112  facing the light emission surface  111  in the vicinity of the light-emitting panel  110 . Here, the vicinity of the light-emitting panel  110  may be defined as a space within 500 mm of the light-emitting panel  110 , for example. As already explained earlier, the space in the vicinity is not limited to the +z direction. For example, the frame-like member  120  may be provided at a position within 500 mm of the light-emitting panel  110  in at least one of a forward direction, a rearward direction and a lateral direction. 
     Incidentally, the frame-like member  120  may be arranged with no clearance between the frame-like member  120  and the light-emitting panel  110  in the forward direction, the rearward direction or the lateral direction from the light-emitting panel  110 . In this case, the light-emitting panel  110  and the frame-like member  120  may be connected together via a cushioning material or the like, for example. With such a configuration, it is possible to prevent unnecessary light (light other than light L 1  that is desired to be emitted from the light-emitting panel  110  or light L 2  that is desired to be emitted from the frame-like member  120 ) from being emitted to the inside of the space  112 . 
     Further, the frame-like member  120  may have structure in which a plurality of members are arranged with clearance between each other. Namely, the frame-like member  120  may have structure separated into two or more parts. For example, the frame-like member  120  may have structure separated into parts corresponding to four sides forming an outer periphery of the light emission surface  111  of the light-emitting panel  110 . In that case, the frame-like member  120  may have a shape in which corner parts of the light emission surface  111  are open. The frame-like member  120  may also have a shape in which a part of each side other than the corner parts is open. In that case, the frame-like member  120  may have structure in which parts are arranged with clearance in the X direction and the Y direction. The frame-like member  120  may also have structure in which parts are arranged with clearance in the Z direction like the blind structure, for example. As above, the shape of the frame-like member  120  can be provided with a variety of designability. 
     The light-emitting panel is referred to also as an illumination panel. The light-emitting panel  110  emits illuminating light L 1  towards the space  112 . The light-emitting panel  110  has a planar light emission surface  111 , for example. The light emission surface  111  is not limited to a planar surface. The light emission surface  111  may be curved, for example. Further, the shape of the light-emitting panel  110  is not limited to the shape illustrated in the drawings. Besides the illustrated flat plate-like shape (shape having two surfaces connected to each other by one or more side faces), the light-emitting panel  110  can take a variety of shapes such as a spherical shape, a polyhedral shape, a columnar shape (shape in which two bases are connected to each other by one or more side faces), a barrel shape and a spool shape, for example. The light emission surface  111  is formed on a surface which the light-emitting panel  110  has, for example. Incidentally, the light emission surface  111  may also be formed in a region as a part of a surface which the light-emitting panel  110  has. The formation position, the shape, etc. of the light emission surface  111  are not particularly limited. 
     The light source unit  140  is a light source that emits white light, for example. The light source unit  140  emits the light towards the back side (more specifically, a back surface) of the frame-like member  120 , for example. In that case, a transmissive frame-like member is provided as the frame-like member  120 . Here, the back side of the frame-like member  120  means a side opposite to the front side defined as the side viewed by an observer after the installation of the illumination device. The back surface of the frame-like member  120  means a surface on a side opposite to a surface on the front side (hereinafter referred to as a front surface) defined as the surface viewed by the observer after the installation. Incidentally, “the side viewed by the observer after the installation” is more specifically a side facing the space  112  or a light emission direction of the light-emitting panel  110  (+Z direction). Thus, the front surface of the frame-like member  120  can be a surface facing the space  112  or the light emission direction of the light-emitting panel  110  (+Z direction). For example, the front surface of the frame-like member  120  includes a light emission surface (referred to also as a light-emitting surface) that emits the light L 2  simulating solar light. 
     In the case where the illumination device  1  includes a transmissive frame-like member  120 , the light source unit  140  may be arranged on the back side of the frame-like member  120 . The light source unit  140  may be arranged on the back side of the frame-like member  120  along the shape of the frame-like member  120  as shown in  FIGS. 1 to 4 , for example. The light source unit  140  may be formed with a plurality of LEDs (light-emitting diodes). Incidentally, the LED is an example of a light-emitting element. In that case, the light source unit  140  may be configured so that a plurality of LEDs (light-emitting elements) are arranged to face the back surface of the frame-like member  120  and to be in an array of one line or a plurality of lines along the shape of the frame-like member  120 , for example. 
     The light source unit  140  may also be configured to emit the light towards the front side (more specifically, the front surface) of the frame-like member  120 , for example. In that case, a reflective frame-like member is provided as the frame-like member  120 . In the case where the illumination device  1  includes a reflective frame-like member  120 , the light source unit  140  may be arranged lateral to the light-emitting panel  110 , for example. 
     Incidentally, it is also possible to use a panel-purposed light source  110   a  which will be described later as the light source unit  140 . For example, the light source unit  140  can be left out by splitting light emitted from the panel-purposed light source  110   a  into light heading for the light-emitting panel  110  and light heading for the frame-like member  120 . In that case, the illumination device  1  may include a light splitting part  180  such as a half mirror that turns a part of the light emitted from the panel-purposed light source  110   a  into the light heading for the frame-like member  120 . 
     Further, the light source unit  140  can be left out by receiving the light emitted from the panel-purposed light source  110   a  via the light-emitting panel  110 , for example. For example, the illumination device  1  may make use of light emitted from the light-emitting panel  110  after being emitted from the panel-purposed light source  110   a  and entering the light-emitting panel  110 . In that case, the illumination device  1  may include a light deflection member such as a mirror that deflects the light emitted from the light-emitting panel  110  towards a direction in which the frame-like member  120  is arranged. 
     In the case where the panel-purposed light source  110   a  is used as the light source unit  140 , the illumination device  1  can be considered to include the panel-purposed light source  110   a  as the light source unit  140 . Incidentally, if the panel-purposed light source  110   a  is a light source that uses external light or the like by guiding the light, the illumination device  1  can be considered to include a light guide part for guiding the external light as the light source unit  140 . As above, the illumination device  1  does not necessarily have to include a special light source specially for the frame-like member  120 . 
     The shape of the frame-like member  120  is not limited to the shapes described above. Further, the shape and the position of the light source unit  140 , the color of the emitted light, and the number of the emitted light beams are not limited to the examples described above. 
     The frame-like member  120  emits the light L 2  towards the space  112  by transmitting or reflecting the light emitted from the light source unit  140 . The frame-like member  120  may also emit the light L 2  towards the space  112  by diffusively transmitting or diffusively reflecting the light emitted from the light source unit  140 . 
     While examples in which the frame-like member  120  emits the light L 2  by transmitting and diffusing the light emitted from the light source unit  140  will be mainly described below, it is also possible for the frame-like member  120  to emit the light L 2  by reflecting and diffusing the incident light, for example. Incidentally, it is permissible even if the frame-like member  120  does not have the function of providing the light L 2  with diffuseness. In the following description, the light emitted from the frame-like member  120  to the space  112  is referred to as the light L 2  irrespective of whether the light is diffuse light or not. 
     As shown in  FIG. 3 , the illumination device  1  is attached to a concave part of a ceiling  900 , for example. In this case, the light-emitting panel  110  simulates a skylight. To simulate the skylight, the light-emitting panel  110  emits illuminating light L 1  at a color temperature representing the color of a natural sky towards a space in front (the space  112  in this example) in which the observer (user) is situated, for example. However, the illumination device  1  may also be attached to a position other than the ceiling  900 , such as a wall, a door or a vehicle&#39;s body. While the light-emitting panel  110  can be a panel reproducing a natural sky such as a blue sky as above, the light-emitting panel  110  is not limited to this example. For example, the light-emitting panel  110  can be a panel emitting illuminating light L 1  representing a color other than the sky color. 
     While the specific configuration of the light-emitting panel  110  is not limited, it is possible to take some examples of the light-emitting panel  110 , such as a light guide panel as a light transmissive member that diffuses light by allowing the light to pass through, reflecting and guiding the light, a liquid crystal panel making use of a liquid crystal and a backlight, and an organic EL (ElectroLuminescence) panel. As a suitable example, the light-emitting panel  110  can be a panel that reproduces the color tone of a natural sky such as a blue sky (e.g., blue color with transparency) by using a diffusive body that exerts Rayleigh scattering or similar scattering power on the incident light. For example, the light-emitting panel  110  can be a light guide panel that receives incident light from the panel-purposed light source  110   a  and emits scattered light as the light L 1 . The light-emitting panel  110  can also be a panel of a different type capable of simulating a window. 
     As a concrete example of the light guide panel, there is a panel that includes an optical medium on the nanometer order and generates scattered light by having the incident light scattered by the optical medium. Here, the optical medium on the nanometer order is, for example, nanoparticles, composites (e.g., sol-gel hardened oxide), cavities, surface concave parts, surface convex parts, or the like having size on the nanometer order. 
     By letting light enter such a light guide panel from the back side or the side face&#39;s side, in the process of guiding the light (incident light) in the diffusive body, scattered light having a correlated color temperature higher than that of the incident light can be emitted from the light emission surface  111 . Further, the light guide panel may also be configured to include a scattering layer that exerts predetermined scattering power on the incident light and a transmission layer that allows the incident light to pass through and to function as a light guide path that guides the incident light to a predetermined light guide end while making the light go back and forth between the scattering layer and the transmission layer in the diffusive body. Also with such a multilayer structure, scattered light having a correlated color temperature higher than that of the incident light can be emitted from the light emission surface  111 . 
     As shown in  FIG. 5 , the frame-like member  120  includes the bright part region  131  and the dark part region  132 . In the following description, a part of the frame-like member  120  in which at least one of the bright part region  131  and the dark part region  132  is provided can be referred to as a sunlight expression part  130 . For example, the sunlight expression part  130  may be provided in a predetermined region on the front surface of the frame-like member  120 . The bright part region  131  and the dark part region  132  on the frame-like member  120  respectively simulate a sunny part and a shady part formed by incoming light L from the sun that is assumed to irradiate the frame-like member  120  through the light-emitting panel  110 . To simulate the sunny part and the shady part, the frame-like member  120  emits the light L 2 . 
     The light amount regulation part  22  is provided, for example, in an optical path until the light emitted from the light source unit  140  enters the frame forming part  12  (in this example, the frame-like member  120 ) and is emitted as light heading for the space  112 . For example, the light amount regulation part  22  can be a light restriction member having a function of making the intensity of light heading for the space  112  from the dark part region  132  weaker than the intensity of light heading for the space  112  from the bright part region  131  in the light entering the frame forming part  12  from the light source unit  140 . The light amount regulation part  22  can also be, for example, a light extraction member having a function of strengthening the intensity of the light heading for the space  112  from the bright part region  131  than the intensity of the light heading for the space  112  from the dark part region  132  in the light entering the frame forming part  12  from the light source unit  140 . By providing such a light amount regulation part  22 , the observer is made to visually recognize the dark part region  132  as a region darker than the bright part region  131 . The intensity of light is referred to also as a light amount per unit area or luminance. 
     In the case where the illumination device  1  includes a transmissive frame-like member  120 , the illumination device  1  may include, for example, a light restriction member (hereinafter referred to as a first light restriction member) that makes the intensity of light advancing to the space  112  from the dark part region  132  weaker than the intensity of light advancing to the space  112  from the bright part region  131  by absorbing or reflecting a part of light entering from the back side of the frame-like member  120  as the light amount regulation part  22 . For example, the mask  122  is an example of such a first light restriction member. 
     The first light restriction member can be an optical member that is arranged in the dark part region  132 , or in a region corresponding to the dark part region  132  and situated in an optical path until the light emitted from the light source unit  140  enters the back surface of the frame-like member  120  and is emitted from the front surface of the frame-like member  120  as the light heading for the space  112 , and absorbs or reflects at least a part of the entered light. By including such an optical member, it is possible to make the intensity of light advancing to the space  112  through the dark part region  132  weaker than the intensity of light advancing to the space  112  through the bright part region  131  in the light from the light source unit  140 . 
     Here, the “optical path until the light emitted from the light source unit  140  enters the back surface of the frame-like member  120  and is emitted from the front surface of the frame-like member  120  as the light heading for the space  112 ” includes an optical path until the light emitted from the light source unit  140  enters the back surface of the frame-like member  120  and an optical path until the light entering the back surface of the frame-like member  120  is emitted from the front surface of the frame-like member  120  as the light heading for the space  112 . Therefore, the aforementioned optical path includes not only the path between the light source unit  140  and the frame-like member  120  (e.g., a space on the back side of the frame-like member  120 ) but also the front surface of the frame-like member  120 , various interfaces in the frame-like member  120 , and so forth. 
     The “region corresponding to the dark part region  132 ” in such an optical path means a region (range in directions in which the light spreads) at an arbitrary position (position in the traveling direction of the light) in the optical path in which the light from the light source unit  140  passing through the region turns into the light heading for the space  112  from the dark part region  132  of the frame-like member  120 . For example, when the dark part region  132  is formed on the front surface of the frame-like member  120 , a region on the back surface facing the dark part region  132  formed on the front surface may be specified as the region corresponding to the dark part region  132  in a case where the region means a region on the back surface of the frame-like member  120 . 
     Incidentally, a region corresponding to the bright part region  131  may be defined by replacing the dark part region  132  in the above description of the “region corresponding to the dark part region  132 ” with the bright part region  131 . The same goes for the reflective frame-like member  120 . 
     The first light restriction member may be provided, for example, between the light source unit  140  and the frame-like member  120 , on a surface of the frame-like member  120  where an incidence surface for the light from the light source unit  140  or the light emission surface is formed, or at one of various interfaces existing in the frame-like member  120 , so as to cover the dark part region  132  or the region corresponding to the dark part region  132 . 
     In the case where the illumination device  1  includes a reflective frame-like member  120 , the illumination device  1  may include, for example, a light restriction member (hereinafter referred to as a second light restriction member) that makes the intensity of the light advancing to the space  112  from the dark part region  132  weaker than the intensity of the light advancing to the space  112  from the bright part region  131  by absorbing or transmitting (preventing reflection of) a part of light entering from the front side of the frame-like member  120  as the light amount regulation part  22 . 
     For example, the second light restriction member can be an optical member that is arranged in the dark part region  132 , or in a region corresponding to the dark part region  132  and situated in an optical path until the light emitted from the light source unit  140  enters the front surface of the frame-like member  120  and is emitted again from the front surface of the frame-like member  120  as the light heading for the space  112 , and absorbs or transmits (prevents reflection of) at least a part of the entered light or deflects at least a part of the entered light into an angle not heading for the space  112 . By including such an optical member, it is possible to make the intensity of light reflected by the frame-like member  120  and advancing to the space  112  from the dark part region  132  weaker than the intensity of light advancing to the space  112  from the bright part region  131  in the light from the light source unit  140 . 
     Here, the “optical path until the light emitted from the light source unit  140  enters the front surface of the frame-like member  120  and is emitted again from the front surface of the frame-like member  120  as the light heading for the space  112 ” includes an optical path until the light emitted from the light source unit  140  enters the front surface of the frame-like member  120  and an optical path until the light entering the front surface of the frame-like member  120  is emitted again from the front surface of the frame-like member  120  as the light heading for the space  112 . Therefore, the aforementioned optical path includes not only the path between the light source unit  140  and the frame-like member  120  (e.g., a space on the front side of the frame-like member  120 ) but also the front surface of the frame-like member  120 , various interfaces in the frame-like member  120 , a path between the frame-like member  120  and a light reflection member if the frame-like member  120  and the light reflection member are arranged separately from each other, and so forth. 
     The second optical member may be provided, for example, between the light source unit  140  and the frame-like member  120 , on a surface of the frame-like member  120  where the incidence surface for the light from the light source unit  140  or the light emission surface is formed, at one of various interfaces existing in the frame-like member  120 , or between the frame-like member  120  and the light reflection member, so as to cover the dark part region  132  or the region corresponding to the dark part region  132 . 
       FIG. 6  is a block diagram showing a configuration example of a control system of the illumination device  1 . As shown in  FIG. 6 , the illumination device  1  includes, for example, a panel-purposed light source drive unit  115  as a drive circuit that turns on, adjusts or turns off the panel-purposed light source  110   a  as a light source for the light-emitting panel  110 , a light source drive unit  145  as a drive circuit that turns on, adjusts or turns off the light source unit  140 , and a lighting control unit  116  as a control circuit that controls the panel-purposed light source drive unit  115  and the light source drive unit  145 . The lighting control unit  116  is capable of performing control so that the turning on, adjustment and turning off of the panel-purposed light source  110   a  and the turning on, adjustment and turning off of the light source unit  140  have certain relevance to each other. The lighting control unit  116  may also control the turning on, adjustment and turning off of the panel-purposed light source  110   a  and the turning on, adjustment and turning off of the light source unit  140  independently of each other. Incidentally, while  FIG. 6  shows a case where the panel-purposed light source  110   a  and the light source unit  140  are light sources separate from each other, the panel-purposed light source  110   a  and the light source unit  140  can also be a common light source. In other words, the panel-purposed light source  110   a  may function also as the light source unit  140 . In this case, the panel-purposed light source drive unit  115  functions also as the light source drive unit  145 . Each of the panel-purposed light source  110   a  and the light source unit  140  is, for example, an LED, a laser light-emitting element, a fluorescent lamp or the like. 
       FIG. 7  is a schematic diagram showing an example of a state of the illumination device  1  observed when the illumination device  1  attached to the ceiling  900  is looked up at from below.  FIG. 8  is a principal part cross-sectional view schematically showing a configuration example of the illumination device  1 .  FIG. 9A  is a front view showing an example of the bright part region  131  and the dark part region  132  of the frame-like member  120  of the illumination device  1  shown in  FIG. 8  as viewed in a horizontal direction from the front side (the inside of the space  112 ).  FIG. 9B  is a schematic cross-sectional view taken along the line IX-IX in  FIG. 9A . 
     In this example, the frame-like member  120  is provided at a position in front of the light-emitting panel  110  and contacting the end part of the light-emitting panel  110 . Further, the frame-like member  120  has a shape with an opening part so as to expose the light emission surface  111  of the light-emitting panel  110 . As shown in  FIG. 4  and  FIG. 7 , the frame-like member  120  is formed with four side walls, and the shape of the frame-like member  120  as viewed in the −Z direction is a quadrangle such as a rectangle or a square. However, the shape of the frame-like member  120  as viewed in the −Z direction can also be a shape other than a quadrangle. For example, the shape of the frame-like member  120  as viewed in the −Z direction can be a polygon other than a quadrangle. Further, the shape of the frame-like member  120  as viewed in the −Z direction can be a circle, an ellipse, a shape formed with a smooth curved line, or the like. Incidentally, in this example, the front surface of the frame-like member  120  is an inside surface that is exposed to the observer&#39;s side in the state after the installation of the illumination device  1 , and the back surface of the frame-like member  120  is an outside surface that is not exposed to the observer&#39;s side. 
     As shown in  FIG. 8  and  FIG. 9B , the frame-like member  120  may include a frame body  121  as a base member being a light transmissive member, a mask  122  as the first light restriction member, and a light transmission diffusion member  123  as a first light diffusion member. The light transmission diffusion member  123  has a function of diffusing light passing through the member. The frame body  121  is formed by, for example, integral molding by using a light transmissive material. The mask  122  is arranged on a region as a part of a surface of the frame body  121  of the frame-like member  120  on the front side (the space  112 &#39;s side). Incidentally, the mask  122  does not need to constitute a part of the frame-like member  120 . For example, the mask  122  may be provided independently between the light source unit  140  and the frame-like member  120 . 
     The light transmission diffusion member  123  is arranged on a surface of the mask  122  being a surface of the frame body  121  of the frame-like member  120  on the space  112 &#39;s side. Incidentally, even supposing that the mask  122  is formed on a surface (back surface) of the frame body  121  of the frame-like member  120  on the back side, the light transmission diffusion member  123  is desired to be provided on the surface of the frame body  121  of the frame-like member  120  on the space  112 &#39;s side. In other words, the light transmission diffusion member  123  is desired to be provided at a position closer to the space  112  than the light amount regulation part  22  (in this example, the mask  122 ). 
     The mask  122  has a function of decreasing the light amount by blocking off a part of the light heading for the space  112  through the frame body  121  of the frame-like member  120 . 
     The light transmission diffusion member  123  is formed on the whole or part of the front surface of the frame-like member  120 , for example. The light transmission diffusion member  123  has a function of transmitting and diffusing a part of the incident light. For example, the light transmission diffusion member  123  is formed by applying or printing a light transmission diffusion material on a predetermined region on the front surface of the frame-like member  120 , by sticking a film as a light diffusion member on a predetermined region on the front surface of the frame-like member  120 , or by a combination of these methods. 
     The light transmission diffusion member  123  may be formed, for example, on the whole of the front surface of the frame-like member  120  including the bright part region  131  and the dark part region  132 . With such a configuration, the front surface of the frame-like member  120  can be provided with uniformized texture. Further, it is possible to make the mask  122  and the light source unit  140  be less visually recognizable to the observer when the light source unit  140  is off. 
     It is possible to use a material having relatively high light transmittance as the light transmission diffusion member  123  formed in the bright part region  131  and use a material having relatively low light transmittance as the light transmission diffusion member  123  formed in the dark part region  132 . In that case, the light transmission diffusion member  123  formed in the dark part region  132  is regarded as the first light restriction member. 
     The light transmission diffusion member  123  may be left out in a case where the light incident upon the frame-like member  120  is diffuse light or the frame body  121  itself has the diffusing function due to particles dispersed in the frame body  121 , surface roughening treatment performed on the frame body  121 , or the like. 
     The dark part region  132  included in the front surface of the frame-like member  120  is a region in which a simulative shady part, simulating a shady part as a region formed when the sunlight is blocked off by an object (e.g., window frame), is formed when the light source unit  140  is on. The mask  122  forms the simulative shady part in the dark part region  132 . The dark part region  132  is referred to also as a simulative shady region. The bright part region  131  included in the frame-like member  120  is a region in which a simulative sunny part, simulating a sunny part as a region formed by the irradiation with the sunlight, is formed when the light source unit  140  is on. 
     The dark part region  132  is determined based on installation condition of the illumination device  1  and the position of a virtual sun, for example. The dark part region  132  may be made, for example, to coincide with a shady region that is formed on the frame-like member  120  as a virtual window frame when light from the virtual sun is emitted from the light-emitting panel  110  as a virtual window. Installation environment of the illumination device  1  includes a three-dimensional position (i.e., latitude, longitude and a height direction position) of the illumination device  1 , posture (i.e., an azimuth angle and an elevation angle) of the illumination device  1 , surrounding environment (i.e., the shape and design of the ceiling), and so forth. While the dark part region  132  may be determined based on the position of the actual sun, the dark part region  132  may also be determined based on the position of a virtual sun. For example, when the illumination device  1  is installed in a building in Japan, the dark part region  132  may be determined based on the position of the sun measured in a foreign country. 
     The mask  122  is formed, for example, by applying or printing a member that limits the light transmittance on the frame body  121  being a light transmissive member, by sticking a film that limits the light transmission on the frame body  121 , or by a combination of these methods. As the member that limits the light transmittance, a light absorption member or a light reflection member can be used, for example. As the film, it is also possible to use a polarizing film, paper having a light-blocking property, or the like. The configuration of the mask  122  is not limited to the above-described example. A surface of the mask  122 , especially a back surface (surface not facing the space  112 ), may be formed with a material having high light reflectance (e.g., 50% or higher). Further, the mask  122  can also be a member provided with the aforementioned function by controlling the light transmittance by forming a plurality of minute openings through a film that does not allow light to pass through. The mask  122  may also be formed by using a film having a function of transmitting a part of the incident light and reflecting a part of the incident light. The light transmittance of the mask  122  is desired to be within a range of approximately 1% to 50%. 
     (1-2) Operation 
     In the region corresponding to the bright part region  131 , the light emitted from the light source unit  140  passes through the frame body  121 , is thereafter transmitted through and diffused by the light transmission diffusion member  123 , and is emitted from the frame-like member  120 . Consequently, the bright part region  131  of the frame-like member  120  looks like a bright region with high luminance. In contrast, in the region corresponding to the dark part region  132 , the light emitted from the light source unit  140  passes through the frame body  121  and is thereafter mostly reflected by the mask  122 . Light that passed through the mask  122  without being reflected by the mask  122  is transmitted and diffused by the light transmission diffusion member  123  and is emitted from the frame-like member  120 . The mask  122  can be either a mask that reflects the whole of the incident light or a mask that allows a certain amount of light to pass through. Since the light emitted from the dark part region  132  is the light that passed through the mask  122 , the dark part region  132  of the frame-like member  120  looks like a darker region with lower luminance than the bright part region  131 . In other words, a light emission amount of the bright part region  131  per unit area is high and a light emission amount of the dark part region  132  per unit area is low. Incidentally, since the light emission amount of the frame-like member  120  is low in the dark part region  132  of the frame-like member  120 , it is also possible not to arrange the light source unit  140  on the back side of the dark part region  132  of the frame-like member  120 . In other words, it is also possible to arrange the light source unit  140  only on the back side of the bright part region  131  of the frame-like member  120 . 
     By forming the bright part region  131  and the dark part region  132  as shown in  FIG. 5  and  FIG. 7 , the observer looking up from under the illumination device  1  can feel the bright part region  131  and the dark part region  132  as a sunny part and a shady part. In other words, the observer can feel as if actual solar light, that is, natural light, were coming in through the light-emitting panel  110 . Incidentally, while the solar light actually coming in through a window is substantially parallel light, the light that feels like it is entering through the light-emitting panel through the light-emitting panel  110  due to the bright part region  131  and the dark part region  132  does not need to be parallel light. 
     In the example shown in  FIG. 5  and  FIG. 7 , the illumination device  1  has the bright part region  131  in parts of intra-surface regions of two surfaces corresponding to two sides among the four sides forming the outer periphery of the light emission surface  111 , and forms the simulative sunny part simulating a sunny part in the bright part region  131  when the light source unit  140  is on. Further, the illumination device  1  has the dark part region  132  on two surfaces corresponding to the other two sides and in the remaining parts of the two surfaces on which the bright part region  131  is arranged, and forms the simulative shady part simulating a shady part in the dark part region  132  when the light source unit  140  is on. As above, the illumination device  1  is capable of simulating a situation where the sun exists in the direction of a virtual light source shown in  FIG. 10 . 
     In the example shown in  FIG. 5  and  FIG. 7 , the dark part region  132  is arranged across four surfaces of the frame-like member  120  corresponding to the four sides forming the outer periphery of the light emission surface  111 , and the bright part region  131  is arranged across two surfaces of the frame-like member  120 . In the case where the frame-like member  120  is regarded as being in a quadrangular frame shape having four front surfaces corresponding to the four sides of the light emission surface  111  as above, the bright part region  131  and the dark part region  132  may be arranged as follows: The dark part region  132  may be arranged across the four sides in the frame shape of the frame-like member  120  (more specifically, the four front surfaces of the frame body  121  forming the four sides of the frame shape), and the bright part region  131  may be arranged across two sides in the frame shape of the frame-like member  120  (more specifically, two front surfaces among the four front surfaces of the frame body  121  forming the four sides of the frame shape). Incidentally, besides the above-described examples, it is also possible, for example, to arrange the dark part region  132  across three sides in the quadrangular frame shape and arrange the bright part region  131  across three sides including the other one side in the quadrangular frame shape and two sides connected to both ends of the side as shown in  FIG. 12  which will be explained later. 
     (1-3) Modification 
       FIG. 10  is a diagram showing an example of the relationship among the bright part region  131 , the dark part region  132  and the virtual light source in a frame-like member  120   a  of an illumination device  1   a  as a modification of the illumination device  1  according to the first embodiment. In  FIG. 10 , the virtual light source simulates the sun. The bright part region  131  and the dark part region  132  simulate a sunny region that would be formed by light coming in through a window if the light-emitting panel  110  were an actual window and a shady region not irradiated with light. 
       FIG. 11  is a perspective view showing the bright part region  131  and the dark part region  132  on the frame-like member  120   a  of the illumination device  1   a .  FIG. 12  is a schematic diagram showing an example of a state of the illumination device  1   a  observed when the illumination device  1   a  is looked up at from below. In the example shown in  FIG. 11  and  FIG. 12 , the frame-like member  120   a  has the bright part region  131  on three sides (one side and parts of two sides), and forms the simulative sunny part simulating a sunny part in the bright part region  131 . Further, the frame-like member  120   a  has the dark part region  132  on the other one side and in the remaining parts of the two sides where the bright part region  131  is arranged, and forms the simulative shady part simulating a shady part in the dark part region  132 . Also with such a configuration, it is possible to let the observer feel that natural light is coming in. 
     Further, the bright part region  131  and the dark part region  132  may have the following characteristic in regard to the shape of the dark part region  132  (especially, at the boundaries with the bright part region  131  existing at both ends): That is a characteristic that the two boundaries between the dark part region  132  and the bright part regions  131  overlap with each other when the two boundaries are viewed while being projected on a plane (in the example shown in  FIG. 12 , a YZ plane) parallel to a normal direction of the light emission surface  111 , more specifically, a characteristic that there exists a projection direction (in the example shown in  FIG. 12 , a direction parallel to the X-axis direction) in which the two boundary positions coincide with each other in directions orthogonal to the normal direction of the light emission surface  111 . This is a characteristic appearing as the result of simulating the incoming light from the solar light being parallel light. 
     Further, assuming that the light-emitting panel  110  is an illumination panel that simulates a blue sky in fine weather viewed through a window, the bright part region  131  is desired to be able to simulate a sunny region on a window frame in fine weather and the dark part region  132  is desired to be able to simulate a shady region on the window frame in fine weather. In such cases, it is easily imaginable that the bright part region  131 , that is, a simulative sunny region, at the time of lighting is bright compared with the light-emitting panel  110  at the time of lighting, and at the same time the light L 2  emitted from the bright part region  131  is at a lower color temperature than the light L 1  emitted from the light emission surface  111 . For example, the luminance of the blue sky in fine weather is approximately 5000 [cd/m 2 ] and the luminance of the sunny region on a white diffusion reflection surface commonly used for a window frame member is approximately 30000 [cd/m 2 ]. Further, the color temperature of light when viewing the blue sky in fine weather is approximately 20000 [K] and the color temperature of light when viewing the sunny region on the white diffusion reflection surface is approximately 5000 [K]. Therefore, magnitude relationships regarding the luminance and the color temperature of the emitted light between the light-emitting panel  110  and the bright part region  131  are desired to be maintained as described above. However, the sky viewed through the window is not limited to the blue sky in fine weather, and taking into consideration times of rainy weather, times of cloudy weather, or both of them, it is preferable that the ratio of the luminance (or a luminous flux emitted from an object) between the light-emitting panel  110  and the bright part region  131  be within a range of 20:1 to 1:30. 
     For example, the luminance of the light-emitting panel  110  at the time of lighting may be 100 [cd/m 2 ] to 6000 [cd/m 2 ], or preferably 500 [cd/m 2 ] to 3000 [cd/m 2 ]. In contrast, the luminance of the bright part region  131  at the time of lighting may be 300 [cd/m 2 ] to 30000 [cd/m 2 ], or preferably 1000 [cd/m 2 ] to 12000 [cd/m 2 ]. Further, the correlated color temperature of the light L 1  emitted from the light-emitting panel  110  may be 10000 [K] to 100000 [K], or preferably 20000 [K] to 80000 [K]. In contrast, the correlated color temperature of the light L 2  emitted from the bright part region  131  may be 2000 [K] to 7000 [K], or preferably 2500 [K] to 6500 [K]. 
     Furthermore, a correlated color temperature difference between the light L 1  emitted from the light-emitting panel  110  and the light L 2  emitted from the bright part region  131  may be greater than or equal to 20000 K and less than or equal to 98000 K. 
     Moreover, the ratio of the luminance (or the luminous flux) between the bright part region  131  and the dark part region  132  at the time of lighting is desired to be within a range of 100:1 to 20:1, or preferably, approximately 10:1. However, this relationship is a condition that holds in fine weather, and does not apply to conditions like cloudy weather and nighttime. 
     (1-4) Effect 
     As described above, by using the illumination device  1  or  1   a , the light L 2  emitted from the frame-like member  120  is capable of simulating a sunny region and a shady region on a window frame, and thus even in an environment with no actual incoming light from the sun, it is possible to provide the observer with natural scenery as if the incoming light from the sun were shining through the light-emitting panel. Further, by the combination of the emitted illuminating light L 1  with the light-emitting panel  110  simulating natural light, it is possible to provide the observer with more natural scenery. Furthermore, with the configuration in which the mask  122  is provided in a region of the frame body  121  being a light transmissive member corresponding to the dark part region  132 , the illumination devices  1  and  1   a  have an advantage in that no complicated configuration is necessary, such as an advantage that the simulative shady part (including the boundaries with the simulative sunny region) can be formed in the dark part region  132  with ease. 
     (2) Second Embodiment 
       FIG. 13  is a principal part cross-sectional view schematically showing a configuration example of an illumination device  2  according to a second embodiment.  FIG. 13  shows a configuration example corresponding to the configuration example shown in  FIG. 8 . As shown in  FIG. 13 , the illumination device  2  according to the second embodiment differs from the illumination device  1  according to the first embodiment in the structure of the frame-like member. The illumination device  2  in the second embodiment includes a frame-like member  220  in which the mask  122  is provided on the back surface of the frame body  121  being a light transmissive member. Incidentally, while the mask  122  is shown as one of the components of the frame-like member  220  in the example shown in  FIG. 13 , the mask  122  may also be provided, for example, between the light source unit  140  and the frame-like member  220  (e.g., in the space on the back side of the frame-like member  220 ) as already explained earlier. The second embodiment may be the same as the first embodiment except for the features described above. 
     Also by using the illumination device  2  according to the second embodiment, advantages the same as those of the first embodiment can be obtained. 
     Further, in the illumination device  2  according to the second embodiment, blurring can be caused in the boundary parts between the bright part region  131  and the dark part region  132  on the frame-like member  220  by arranging the mask  122  to be separate from the light transmission diffusion member  123 , and thus it is possible to provide the observer with more natural scenery with a simple configuration. 
     (3) Third Embodiment 
       FIG. 14  is a principal part cross-sectional view schematically showing a configuration example of an illumination device  3  according to a third embodiment.  FIG. 14  shows a configuration example corresponding to the configuration examples shown in  FIG. 8  and  FIG. 13 . As shown in  FIG. 14 , the illumination device  3  according to the third embodiment differs from the illumination devices  1  and  2  according to the first and second embodiments in the structure of the frame-like member. The illumination device  3  in the third embodiment is configured so that the thickness T (length in the traveling direction of the light from the light source unit  140 ) of the frame body  121  being a light transmissive member increases with the increase in the distance from the light emission surface  111 . In the example shown in  FIG. 14 , the mask  122  is provided in a region on the back surface of the frame body  121  corresponding to the dark part region  132 . Further, the light transmission diffusion member  123  is provided on a surface (front surface) on the front side of the frame body  121 . Incidentally, leaving out the light transmission diffusion member  123  is possible similarly to the first embodiment. 
       FIG. 15A  is a front view showing an example of the bright part region  131  and the dark part region  132  on a frame-like member  320  of the illumination device  3  according to the third embodiment, and  FIG. 15B  is a schematic cross-sectional view taken along the line XV-XV in  FIG. 15A . When the configuration shown in  FIG. 14  is employed, the light transmittance in a boundary part  133  between the bright part region  131  and the dark part region  132  on the frame-like member  320  of the illumination device  3  increases with the increase in the distance from the light emission surface  111 . Namely, as shown in  FIG. 15A , on the frame-like member  320  of the illumination device  3 , the blurring in the boundary part  133  between the bright part region  131  and the dark part region  132  increases with the increase in the distance from the light emission surface  111 . 
     When light arriving directly from the sun comes into a window frame via a window, it is imaginable that a sunny part and a shady part are formed as shown in  FIG. 7 , for example. However, more detailed observation clarifies that the blurring of the boundary part between the sunny part and the shady part increases with the increase in the distance from the window. This is because the sun is a light source having a certain size and the boundary of a shadow formed on the window frame blurs with the increase in the distance from the opening of the window to the irradiation position. 
     Therefore, the illumination device  3  changes the spacing between the mask  122  and the light transmission diffusion member  123  so that the spacing gradually increases with the increase in the distance from the light emission surface  111 . With such a configuration, the blurring is gradually increased with the increase in the distance from the light emission surface  111  as shown in  FIG. 15A . Specifically, the frame-like member  320  of the illumination device  3  is configured so that the thickness T of the frame body  121  increases so as to increase the distance between the mask  122  and the light transmission diffusion member  123  with the increase in the distance from the light emission surface  111  of the light-emitting panel  110 . 
     Further, the same advantage as that described above can be obtained by leaving out the light transmission diffusion member  123 , providing the frame body  121  with the scattering power, and then configuring the frame body  121  so that the thickness T of the frame body  121  increases with the increase in the distance from the light emission surface  111  of the light-emitting panel  110 . 
     It is also possible to obtain the same advantage by configuring the mask  122  so that the light transmittance of the region of the mask  122  corresponding to the boundary part  133  with the bright part region  131  increases with the increase in the distance from the light emission surface  111  of the light-emitting panel  110  without changing the thickness T of the frame body  321 . 
     For example, the light transmittance can be varied in a surface by increasing/decreasing printing density of a constituent material having a light blocking function and formed as the mask  122 . 
     As an example, it is also possible to provide a mask  122   a  whose light transmittance varies in a surface instead of the mask  122  as shown in  FIGS. 15A and 15B . The mask  122   a  is configured so that the printing density of the constituent material having the light blocking function decreases or the amount of applying the constituent material decreases with the increase in the distance from the light emission surface  111  of the light-emitting panel  110  at least in a region corresponding to the boundary part  133  forming the boundary with the bright part region  131  included in the dark part region  132 . Incidentally, the mask  122   a  may also be configured so that the thickness of a film forming the mask  122   a  decreases in the region with the increase in the distance from the light emission surface  111  of the light-emitting panel  110 . By changing the light transmittance of the mask  122   a  in a surface as above, the blurring can be caused to the boundary part  133 . 
     Incidentally, the place where the mask  122   a  is formed is not limited to the back surface of the frame-like member  120 . For example, it is also possible to provide the mask  122   a  between the frame body  121  and the light transmission diffusion member  123  as shown in  FIG. 8 . 
     Further, the region where the mask  122   a  is provided is also not limited to the region corresponding to the boundary part  133  included in the dark part region  132 . For example, it is also possible to provide the mask  122   a  in the whole region of the sunlight expression part  130  including a boundary part forming the boundary with the dark part region  132  included in the bright part region  131  or in a region corresponding to the sunlight expression part  130 . In that case, the mask  122   a  may be configured so that the light transmittance in a region corresponding to the bright part region  131  is higher than that in a region corresponding to the boundary part. 
     As described above, by using the illumination device  3  according to the third embodiment, in addition to obtaining the advantages of the first and second embodiments, it is possible to achieve a configuration in which the blurring increases with the increase in the distance from the light emission surface  111  in the boundary part  133  between the bright part region  131  and the dark part region  132  on the frame-like member  320 , by which a window frame can be simulated with high quality. Namely, it is possible to provide the observer with still more natural scenery with a simple configuration. 
     (4) Fourth Embodiment 
       FIG. 16  is a principal part cross-sectional view schematically showing a configuration example of an illumination device  4  according to a fourth embodiment.  FIG. 16  shows a configuration example corresponding to the configuration examples shown in  FIG. 8 ,  FIG. 13  and  FIG. 14 .  FIG. 17  is a rear view showing a configuration example of the illumination device  4  according to the fourth embodiment as viewed from the back side of the frame-like member. 
     The illumination device  4  includes a light reflection diffusion member  150  that connects the back surface of the frame-like member  120  and the light source unit  140 . 
     The light reflection diffusion member  150  has a concave surface in a shape like a semicircular column, and has a function of reflecting and diffusing a part of the incident light and letting the light reach the back surface of the frame-like member  120 . 
     The fourth embodiment may be the same as any one of the first to third embodiments except for the features described above. For example, while the frame-like member  120  in the first embodiment shown in  FIG. 8  is illustrated as an example of the frame-like member in the example shown in  FIG. 16 , the configuration of the frame-like member is not limited to this example. 
     In the example shown in  FIG. 16 , the light source unit  140  includes LEDs  141 , an LED substrate  142  and a light source holder  143 . The light reflection diffusion member  150  is fixed to the light source holder  143 , and an open end of the light reflection diffusion member  150  is arranged to be in proximity to the back surface of the frame-like member  120 . The light reflection diffusion member  150  is formed by painting a metal plate or a resin plate with white, for example. The light reflection diffusion member  150  may also be formed by sticking a film that diffuses light on a metal plate or a resin plate. 
     While most of the light emitted from the light source unit  140  (more specifically, each LED  141 ) directly reaches the back surface of the frame-like member  120 , a part of the light emitted from the light source unit  140  is reflected and diffused by the light reflection diffusion member  150  and consequently reaches the back surface of the frame-like member  120 . By the reflection and diffusion by the light reflection diffusion member  150 , the light from the light source unit  140  can be made to be incident upon the whole region of the back surface of the frame-like member  120  efficiently (without turning the light into stray light). 
     Incidentally, it is also possible for the illumination device  4  to include a light reflection member  150   a  having no diffusing power instead of the light reflection diffusion member  150 . 
     As described above, by using the illumination device  4  according to the fourth embodiment, in addition to obtaining the advantages of the first to third embodiments, it is possible to reduce the loss in the light emitted from the light source unit  140 . Namely, utilization efficiency of the light from the light source unit  140  can be increased. 
       FIG. 18  is a principal part cross-sectional view schematically showing a configuration example of an illumination device  4   a  according to a modification of the fourth embodiment. The illumination device  4   a  shown in  FIG. 18  differs from the illumination device  4  shown in  FIG. 16  in including a light transmission diffusion member  160  as a second light diffusion member between the light source unit  140  and the back surface of the frame-like member  120 . 
     In this example, the light emitted from each LED  141  of the light source unit  140  is diffused by the light transmission diffusion member  160  and then reaches the back surface of the frame-like member  120 . In this case, intensity distributions of the light emitted from a plurality of LEDs arranged in an array are superimposed on each other by the light transmission diffusion member  160 , by which the intensity distribution of the light reaching the frame-like member  120  is uniformized. 
     Also in this example, it is also possible for the illumination device  4   a  to include the light reflection member  150   a  having no diffusing power instead of the light reflection diffusion member  150 . Also in such cases, the light emitted from the light source unit  140  can be prevented from turning into stray light and can be made to efficiently reach the back surface of the frame-like member  120 . 
     In the following description, the light reflection diffusion member  150 , the light reflection member  150   a , the light transmission diffusion member  160  described later, and so forth that are provided in order to deflect (including reflection and diffusion) the light from the light source unit  140  and guide the light to the frame-like member can be collectively referred to as first light deflection members. 
     As described above, by using the illumination device  4   a , since the illumination device  4   a  further includes the light transmission diffusion member  160 , an advantage is obtained in that luminance unevenness in the bright part region can be reduced further, such as an advantage that the intensity distribution of the light emitted from the plurality of LEDs arranged in an array can be uniformized. 
     (5) Fifth Embodiment 
       FIG. 19  is a schematic diagram showing an example of a state of an illumination device  5  according to a fifth embodiment observed when the illumination device  5  is looked up at from below.  FIG. 20  is a cross-sectional view schematically showing a configuration example of the illumination device according to the fifth embodiment.  FIG. 19  shows a configuration example corresponding to the configuration examples shown in  FIG. 8 ,  FIG. 13 ,  FIG. 14  and  FIG. 16 . 
     The illumination device  5  according to the fifth embodiment differs from the illumination devices according to the first to fourth embodiments in that a frame-like member  520  further includes a flange part  230 . 
     Here, the flange part  230  means a part of the frame-like member  520  that is connected to a farthest end part of the region where the sunlight expression part  130  (the bright part region  131 , the dark part region  132 , or both of the bright part region  131  and the dark part region  132 ) is formed, farthest from the light emission surface  111 , and extends outward from the end part. For example, when the illumination device  5  is provided on a ceiling, a part extending outward in a horizontal direction from the end part may be regarded as the flange part. When the illumination device  5  is provided on a wall orthogonal to a horizontal surface, a part extending outward in the vertical direction from the end part may be regarded as the flange part. 
     As shown in  FIG. 20 , the flange part  230  may include a plate-shaped part  231  as a member like a plate and a light diffusion member  232  provided on the front side of the plate-shaped part  231 . While the plate-shaped part  231  may be a light transmissive member, the plate-shaped part  231  may also be a nontransparent member in order to prevent the observer from visually recognizing the light source unit  140 . This does not apply to cases where the illumination device  5  is configured so that the light source unit  140  is invisible due to the light reflection diffusion member  150 , the light reflection member  150   a , the light diffusion member  232  or the like. 
     Further, the frame body  121  may serve also as the plate-shaped part  231 . For example, the frame body  121  may be configured to spread outward from the farthest end part of the region where the sunlight expression part  130  (the bright part region  131 , the dark part region  132 , or both of the bright part region  131  and the dark part region  132 ) is formed farthest from the light emission surface  111 . 
     The light diffusion member  232  is a light reflection diffusion member, for example. The light transmittance in the light reflection diffusion member may be approximately 1% to 50%, for example. Incidentally, the light transmittance in the light reflection diffusion member may also be less than or equal to 10%, for example. 
     The light diffusion member  232  may also be a light transmission diffusion member, for example. The light transmittance in the light transmission diffusion member is higher than or equal to 50%, for example. In that case, the light transmission diffusion member  123  may serve also as the light diffusion member  232 . For example, the light transmission diffusion member  123  may be provided on the front surface of the frame body  121  and on the front surface of the plate-shaped part  231  integrally or continuously. In the aforementioned case where the frame body  121  serves also as the plate-shaped part  231 , a similar configuration can be achieved by forming the light transmission diffusion member  123  to cover the front surface of the frame body  121 . Incidentally, for a reason described later, it is preferable that the light diffusion surface provided on the front surface of the flange part  230  have light reflectiveness at least for light incident from the front side. For example, even in the configuration including a light transmission diffusion member as the light diffusion member  232 , the light transmission diffusion member is desired to reflect a part of the light. 
     When the illumination device  5  is mounted on a ceiling, the flange part  230  is arranged in parallel with or flush with the ceiling surface, for example. When the illumination device  5  is mounted on a wall, the flange part  230  is arranged in parallel with or flush with the wall surface, for example. Incidentally, the shape of the flange part  230  is not limited to the shape illustrated in the drawing. For example, the flange part  230  may be formed with a plurality of members. Further, the illumination device  5  may also employ structure in which the flange part  230  is detachable or structure including no flange part  230 . 
     Furthermore, the frame-like member  520  may include a part to be in parallel with the installation target surface (ceiling surface, wall surface, etc.) and include the sunlight expression part  130  (i.e., the bright part region  131  and the dark part region  132 ) on a front surface of the part (hereinafter referred to as a flange surface  233 ). Incidentally, in not only the fifth embodiment but also other embodiments, the position on the frame-like member where the sunlight expression part  130  is provided is not particularly limited. For example, it is also possible to form the sunlight expression part  130  on the front surface of the frame body  121  and the flange surface shown in  FIG. 20 . 
     Further, while the cross-sectional shape of the frame-like member  520  cut in the Z direction (hereinafter referred to as a vertical sectional shape) is an L-shape and the front surface of the frame body  121  and the flange part  230  on which the sunlight expression part  130  is formed are orthogonally connected to each other in the example shown in  FIG. 20 , the vertical sectional shape of the frame-like member  520  may also be a curved line shape (i.e., the frame-like member  520  may be in a curved surface shape). The bright part region  131  and the dark part region  132  may be provided on the curved surface on the front side of such a frame-like member  520 . In that case, the frame-like member may either include or not include the flange part  230  further connected to an end part of such a curved surface. 
     As already explained earlier, the frame body  121  and the plate-shaped part  231  of the flange part  230  may be formed integrally. The frame body  121  and the plate-shaped part  231  of the flange part  230  may also be connected together by using another component. 
     It is also possible to make a part of the light emitted from the light source unit  140  be emitted in the +Z direction through the flange part  230  by not providing the light reflection diffusion member  150  around the light source unit  140  or by configuring the light reflection diffusion member  150  to transmit a part of the light. In that case, the flange part  230  is formed with the plate-shaped part  231  being a light transmissive member and the light diffusion member  232  being a light transmission diffusion member, for example. 
       FIG. 21A  is a principal part perspective view schematically showing a configuration example of a frame-like member  520   a  of an illumination device  5   a  according to a modification of the fifth embodiment, and  FIG. 21B  is a schematic cross-sectional view taken along the line XXI-XXI in  FIG. 21A . As shown in  FIG. 21 , the frame-like member  520   a  may have structure including a plurality of opening parts  170 . Incidentally, the frame-like member  520   a  may also be configured to include only one opening part  170 . 
     The frame-like member  520   a  includes a frame body  121   a  including the opening parts  170  having a predetermined height, for example. In this example, the sunlight expression part  130  (the bright part region  131 , the dark part region  132 , or both of the bright part region  131  and the dark part region  132 ) is provided at least on side walls  171  of the opening parts  170  of the frame body  121   a . The side walls  171  in this example correspond to a front surface of the frame-like member  520   a  formed by the opening parts  170 . Further, a front surface of the frame body  121   a  corresponds to the aforementioned flange surface  233 . 
     Incidentally, while the flange surface  233  also corresponds to the front surface of the frame-like member  520   a , a light reflection diffusion member is provided as the light diffusion member  232  in this example without providing the sunlight expression part  130  on the flange surface  233 . 
     The frame body  121   a  in this example is a light transmissive member. On the back side of the side walls  171 , a storage part  172  storing the light source unit  140  may be provided to surround the opening parts  170 . In this case, the light source unit  140  is stored in the storage part  172  and emits light to enter the side walls  171  from the back side. Also in this example, a back surface of the side wall  171  as a surface on the back side of the side wall  171  (more specifically, an inner wall of the storage part  172 ) may be provided with the light reflection diffusion member  150  connecting the back surface and the light source unit  140 . 
     It is also possible to provide the light source unit  140  to the rear of the light-emitting panel  110  without providing the frame body  121   a  with the storage part  172  and make the light from the light source unit  140  enter the side walls  171  from the back side via the light-emitting panel  110 . 
     On a front surface of the side wall  171  as a surface on the front side of the side wall  171 , the light transmission diffusion member  123  is provided. Then, the mask  122  is provided in a region on the back side of the light transmission diffusion member  123  and corresponding to the dark part region  132 . While the mask  122  is provided on the back surface of the side wall  171  formed by the storage part  172  in the example shown in  FIG. 21 , the mask  122  may be provided on the front surface of the side wall  171  (however, on the back side of the light transmission diffusion member  123 ), for example. Further, in the case where the light source unit  140  is provided to the rear of the light-emitting panel  110 , it is also possible, for example, to provide the mask  122  on the back surface (surface closer to the light-emitting panel  110 ) of the frame body  121   a , between the frame body  121   a  and the light-emitting panel  110 , or on the back surface of the light-emitting panel  110 . 
     While an example of providing the mask  122  only in the dark part region  132  or a region corresponding to the dark part region  132  is shown in the above-described example, it is also possible, for example, to use the mask  122   a  whose light transmittance varies in a surface and provide the mask  122   a  in a region including the bright part region  131  or a region corresponding to the bright part region  131  (e.g., on a whole surface). In that case, the illumination device  5   a  may include, for example, the mask  122   a  that is configured so that the light transmittance of a region corresponding to the dark part region  132  (or the region corresponding to the dark part region  132 ) becomes lower than the light transmittance of the bright part region  131  (or the region corresponding to the bright part region  131 ). Incidentally, even in such a case, the mask  122   a  is regarded as arranging a member having the function of blocking light in at least the dark part region  132  or the region corresponding to the dark part region  132 , and the mask  122   a  (especially, a part arranged in the dark part region  132  or the region corresponding to the dark part region  132 ) is referred to as the first light restriction member. 
     Incidentally, also in this example, the panel-purposed light source  110   a  can be used instead of the light source unit  140 . In that case, the illuminating light L 1  emitted from a region of the light emission surface  111  of the light-emitting panel  110  where no opening part  170  is provided in front may be used as the light from the light source unit  140 , for example. In that case, the storage part  172  may be left out. In that case, the mask  122  may be either provided at a position on the front surface of the side wall  171  and between the light transmission diffusion member  123  and the frame body  121   a  or provided on the back surface (surface closer to the light-emitting panel  110 ) of the frame body  121   a  or between the frame body  121   a  and the light-emitting panel  110 . 
     With such a configuration, when the light that entered the side wall  171  of the opening part  170  from the back side (including the back surface of the frame body  121   a ) is transmitted by the side wall  171  and emitted as the light L 2 , the intensity of the light heading for the space  112  from the dark part region  132  can be reduced compared with the intensity of the light heading for the space  112  from the bright part region  131  on the side wall  171 . 
     Also in the frame body  121   a , it is possible to employ the configuration in which the thickness T of the region where the sunlight expression part  130  is formed (in this example, the distance between the side wall  171  of the opening part  170  and the surface regarded as the back side of the side wall  171  in the frame body  121   a ) increases with the increase in the distance from the aforementioned light emission surface, and the blurring can be expressed by using the difference in the thickness of the region in such a frame body  121 . 
     It is also possible for the frame-like member  520   a  to use the illuminating light L 1  emitted from regions of the light emission surface  111  of the light-emitting panel  110  where an opening part  170  is provided in front, external light entering from the front of the frame-like member  520   a , or the like instead of the light from the light source unit  140 . In that case, it is possible to form the frame body  121   a  with a light reflection member  124  as a reflective frame-like member  520   b  or to provide the light reflection member  124  (not shown) between the light transmission diffusion member  123  and the frame body  121   a . Here, the light reflection member  124  can be a light reflection diffusion member. In that case, the mask  122  can be a light absorptive mask  122   b  that is provided in a region between the light transmission diffusion member  123  and the light reflection member  124  and corresponding to the dark part region  132  and absorbs reflected light from the light reflection member  124 . Here, the mask  122   b  corresponds to the aforementioned second light restriction member. 
     Incidentally, it is also possible to use a light reflection member  124   a  whose light reflectance varies in a surface (in other words, whose light transmittance varies in a surface) instead of the mask  122   b . In the following description, the light reflection member  124   a  provided instead of the mask  122   b  can be referred to as a mask  122   d . For example, an illumination device  5   b  can achieve the same advantages by including the mask  122   d  configured so that the light reflectance of the dark part region  132  (or the region corresponding to the dark part region  132 ) becomes lower than the light reflectance of the bright part region  131  (or the region corresponding to the bright part region  131 ) instead of the mask  122   b  and the light reflection member  124 . Incidentally, even in such a case, the mask  122   d  is regarded as arranging a member having the function of blocking light in at least the dark part region  132  or the region corresponding to the dark part region  132 , and the mask  122   d  (especially, a part arranged in the dark part region  132  or the region corresponding to the dark part region  132 ) is referred to as the second light restriction member. 
     In this example, the light reflection member is a member whose light transmittance is less than 50%, for example. Incidentally, the light reflection member can also be a member whose light reflectance is less than or equal to 10%. However, this does not apply to cases where the light reflectance is purposely varied in a surface like the aforementioned light reflection member  124   a . In that case, the aforementioned light reflectance may be paraphrased as light reflectance in the bright part region  131  or the region corresponding to the bright part region  131 . 
     With such a configuration, in the reflective frame-like member  520   b , the illuminating light L 1  emitted from a region of the opening part  170  surrounded by the side wall  171  or external light entering from the front can be reflected by the side wall  171  and emitted as the light L 2 , and in that case, the intensity of the light heading for the space  112  from the dark part region  132  can be reduced compared with the intensity of the light heading for the space  112  from the bright part region  131  on the side wall  171 . In the following description, the illumination device  5   a  including the reflective frame-like member  520   b  can be referred to as the illumination device  5   b.    
     Incidentally, it is also possible to arrange a plurality of plate-shaped frame bodies  121  in an array with spacing between each other in front of the light-emitting panel  110  instead of the frame body  121   a  including the opening parts  170 . In that case, regions between side faces of the plurality of frame bodies  121  serve in place of the opening parts  170 . For example, the sunlight expression part  130  may be provided on the side faces or front surfaces of such plate-shaped frame bodies  121 . The frame-like member  520   a ,  520   b  may also be, for example, a member that forms a shape like a louver as a whole by parallelly arranging a plurality of long and narrow plate-shaped (e.g., like plates having a length substantially equal to the length of one side of the light-emitting panel  110 ) frame bodies with spacing between each other in front of the light-emitting panel  110 . It is possible to regard inner walls of openings in front of the light-emitting panel  110  formed by such a plurality of frame bodies  121  (front surfaces of the plurality of frame-like members) as the side walls  171  of the opening parts  170  described earlier and thereby implement a similar configuration. 
     As described above, by using the illumination device  5 ,  5   a  or  5   b  according to the fifth embodiment, in addition to obtaining the advantages of the first to fourth embodiments, the sunlight expression part  130  can be formed in a variety of shapes, and thus it is possible to enrich the designability as an illumination device while providing the observer with natural scenery. 
     (6) Sixth Embodiment 
       FIG. 22  is a principal part cross-sectional view schematically showing a configuration example of an illumination device  6  according to a sixth embodiment.  FIG. 22  shows a configuration corresponding to the configuration example shown in  FIG. 20 . The illumination device  6  according to the sixth embodiment includes a frame-like member  620 . Incidentally, the configuration of the frame-like member  620  may be basically the same as that in the above fifth embodiment. In the example shown in  FIG. 22 , the frame-like member  620  includes the flange part  230  similarly to the frame-like member  520 . 
     Incidentally, it is also possible to leave out the flange part  230 . Further, the frame-like member  620  may include the flange surface  233  instead of the flange part  230 . 
     The sixth embodiment proposes a configuration capable of simulating a window frame to some extent for the light-emitting panel  110  even in the off state of the illumination device  6 , that is, even when the light-emitting panel  110  and the light source unit  140  are in the non-lighting state. A configuration that looks natural in the non-lighting state is more specifically a configuration in which the luminance of the bright part region  131  of the frame-like member  620  is equivalent to or higher than the luminance of the dark part region  132 , and the luminance of a front surface of a part where no sunlight expression part  130  is formed (e.g., the flange part  230  or the flange surface  233 ) is equivalent to or higher than the luminance of the bright part region  131  in a case where the frame-like member  620  includes such a part, in a situation where external light is incident upon the illumination device  6  in the non-lighting state. This means that the relationship between the bright part region  131  and the dark part region  132  regarding the luminance does not invert even in the non-lighting state, and means a situation where the front surface of the part where no sunlight expression part  130  is formed (in the example shown in  FIG. 22 , the light diffusion member  232 ) is visually recognizable in the cases where the frame-like member  620  includes such a part. 
     In the non-lighting state, external light shines on the illumination device  6 . Here, focusing on the bright part region  131 , a part of the external light incident upon the bright part region  131  included in the front surface of the frame-like member  620  passes through the light transmission diffusion member  123 , is reflected by the light reflection diffusion member  150 , passes through the light transmission diffusion member  123  again, and is emitted from the bright part region  131 . Incidentally, when the illumination device  6  further includes the light transmission diffusion member  160  as in the example shown in  FIG. 22 , the incident external light passes through the light transmission diffusion member  123 , passes through the light transmission diffusion member  160  before and after being reflected by the light reflection diffusion member  150 , and then passes through the light transmission diffusion member  123  again. 
     In the following description, such light entering the frame-like member  620  through the front surface and being emitted again from the front surface is referred to as reflected external light RL, in which light emitted from the bright part region  131  is referred to as reflected external light RL 1 , light emitted from the dark part region  132  is referred to as reflected external light RL 2 , and light emitted from a region other than the sunlight expression part  130 , such as the flange part  230  or the flange surface  233 , is referred to as reflected external light RL 3 . 
     Light reflectance R 1 , defined as the ratio of the reflected external light RL 1  to the incident external light in the bright part region  131 , is higher than or equal to 50%, for example. The light reflectance R 1  may be obtained by, for example, irradiating the bright part region  131  with a known amount of light and measuring the returning light with an actinometer or the like. 
     Next, the dark part region will be focused on. External light incident upon the dark part region  132  included in the front surface of the frame-like member  620  passes through the light transmission diffusion member  123 , is partially reflected by the mask  122 , passes through the light transmission diffusion member  123  again, and is emitted from the dark part region  132 . Also in the case of the dark part region  132 , when the illumination device  6  includes the light transmission diffusion member  160 , the incident external light passes through the light transmission diffusion member  123 , passes through the light transmission diffusion member  160  before and after being reflected by the light reflection diffusion member  150 , and then passes through the light transmission diffusion member  123  again. 
     Light reflectance R 2 , defined as the ratio of the reflected external light RL 2  to the incident external light in the dark part region  132 , is higher than or equal to 1% and less than 50%, for example. The light reflectance R 2  may be obtained by, for example, irradiating the dark part region  132  with a known amount of light and measuring the returning light with an actinometer or the like. 
     By configuring the light transmission diffusion member  123 , the light reflection diffusion member  150 , the light transmission diffusion member  160 , the mask  122 , etc. so that the light reflectance R 1  of the bright part region  131  becomes higher than the light reflectance R 2  of the dark part region  132  as above, the light emission amount of the bright part region  131  can be made higher than that of the dark part region  132  also in regard to the external light. 
     Incidentally, in the situation where the external light is incident upon the illumination device  6  in the non-lighting state, the light emitted from the bright part region  131  can include light reflected by the front surface of the frame body  121  and the light transmission diffusion member  123  arranged in the bright part region  131  and light entering through the dark part region  132 , passing through the light transmission diffusion member  123  and the mask  122 , reflected (and diffused) by the light reflection diffusion member  150 , and emitted from the bright part region  131 . Similarly, the light emitted from the dark part region  132  can include light reflected by the front surface of the frame body  121  and the light transmission diffusion member  123  arranged in the dark part region  132  and light entering through the bright part region  131 , passing through the light transmission diffusion member  123  and the mask  122 , reflected (and diffused) by the light reflection diffusion member  150 , and emitted from the dark part region  132 . However, the increase/decrease in the light amount due to these factors can occur in both of the bright part region  131  and the dark part region  132 , and thus the influence of these factors may be neglected. 
     Next, the region of the front surface of the frame-like member  620  where no sunlight expression part  130  is formed (e.g., the flange part  230 , the flange surface  233  or the like) will be focused on. When the frame-like member  620  includes such a region, it is desirable to configure the frame-like member  620  further considering the following situation: When external light is incident upon the front surface of the region or the light diffusion member  232  arranged on the front surface, the external light is reflected by the front surface of the frame body (the plate-shaped part  231  or the frame body  121   a ) forming the region, the surface of the light diffusion member  232 , or both of them, and is emitted again from the region. 
     Here, light reflectance R 3 , defined as the ratio of the reflected external light RL 3  to the incident external light in the region of the frame-like member  620  where no sunlight expression part  130  is formed, is higher than or equal to 50%, for example. More specifically, the light reflectance R 3  is desired to be equivalent to or higher than the light reflectance R 1 . The light reflectance R 3  may be obtained by, for example, irradiating the front side of the region where no sunlight expression part  130  is formed with a known amount of light and measuring the returning light with an actinometer or the like. 
     By configuring the light transmission diffusion member  123 , the light reflection diffusion member  150 , the light transmission diffusion member  160 , the frame body  121 , the light diffusion member  232 , the plate-shaped part  231 , etc. so that the light reflectance R 3  of the region where no sunlight expression part  130  is formed such as the flange part  230  and the flange surface  233  becomes equivalent to or higher than the light reflectance R 1  of the bright part region  131  as above, the light emission amount of the region where no sunlight expression part  130  is formed can be made equivalent to or higher than that of the bright part region  131  also in regard to the external light. 
     As described above, by using the illumination device  6 , in addition to obtaining the advantages of the first to fifth embodiments, it is made possible to feel that a window and a window frame exist even in the non-lighting state with a simple configuration. 
     (7) Seventh Embodiment 
       FIG. 23  is a cross-sectional view schematically showing a configuration example of an illumination device  7  according to a seventh embodiment of the present invention. The illumination device  7  is configured so that especially a part of a frame-like member  720  where the sunlight expression part  130  is formed is inclined with respect to the normal line of the light emission surface  111 . 
     More specifically, the frame-like member  720  (more specifically, the frame body  121 ) in this example includes a part that extends outward toward the front. With such a part included in the frame-like member  720 , the area of the sunlight expression part  130  captured in the observer&#39;s field of view can be increased. 
     In this example, the frame body  121  is in a tapered shape in which the opening size of the opening part  170  formed by the frame body  121  (opening region in an XY cross section) increases with the increase in the distance from the light emission surface  111 . 
     Further, the frame-like member  720  in this example includes the flange part  230  that spreads outward from the farthest end part of the frame body  121  farthest from the light emission surface  111 . In this example, the frame body  121  serves also as the plate-shaped part  231  of the flange part  230 . Namely, these parts are formed integrally. 
     On the front surface of the frame body  121  including the flange part  230 , the sunlight expression part  130  (the bright part region  131 , the dark part region  132 , or both of the bright part region  131  and the dark part region  132 ) is provided. While the area of the sunlight expression part  130  captured in the observer&#39;s field of view is increased further in this example by forming the sunlight expression part  130  not only on the front surface of the inclined part of the frame body  121  but also on the front surface of the flange part  230 , the sunlight expression part  130  does not necessarily have to be provided on the flange part  230 . 
     In the example shown in  FIG. 23 , the mask  122  is arranged on the back surface of the frame body  121  of the frame-like member  720  on the right side of the drawing. The example shown in  FIG. 23  is an example in which the whole region on the front side of the frame-like member  720  on the right side of the drawing is the dark part region  132  and the whole region on the front side of the frame-like member  720  on the left side of the drawing is the bright part region  131 . 
     Further, the light transmission diffusion member  123  is arranged on the front surface of the frame body  121  of the frame-like member  720  and the front surface of the flange part  230  on the right side of the drawing. Similarly, the light transmission diffusion member  123  is arranged on the front surface of the frame body  121  of the frame-like member  720  and the front surface of the flange part  230  on the left side of the drawing. Incidentally, a part of the light transmission diffusion member  123  in this example (more specifically, the part arranged on the front surface of the flange part  230 ) serves also as the light transmission diffusion member as the light diffusion member  232 . Incidentally, it is also possible to arrange the mask  122  at a position on the front surface of the frame body  121  and between the frame body  121  and the light transmission diffusion member  123 . 
     In such a configuration, when light from the light source unit  140  is incident upon the back side of the frame body  121  of the frame-like member  720  on the right side of the drawing, the light is diminished by the mask  122 , then passes through the frame body  121  and the light transmission diffusion member  123 , and is emitted from the dark part region  132  as the light heading for the space  112 . On the other hand, when light from the light source unit  140  is incident upon the back side of the frame body  121  of the frame-like member  720  on the left side of the drawing, the light passes through the frame body  121  and the light transmission diffusion member  123  without being diminished by the mask  122 , and is emitted from the bright part region  131  as the light heading for the space  112 . 
     Except for the above-described features, the illumination device  7  shown in  FIG. 23  may be the same as the illumination device in any one of the first to sixth embodiments. 
     Incidentally, while  FIG. 23  shows an example in which the illumination device  7  includes the light splitting part  180 , light emitted from a light source unit  140   a  is split by the light splitting part  180  into light heading for the frame-like member  720  and light heading for the light-emitting panel  110 , and thereby the light source unit  140   a  serves also as the panel-purposed light source  110   a , it is also possible to provide the light source unit  140   a  and the panel-purposed light source  110   a  separately from each other. Such a configuration including the light splitting part  180  is not limited to the example in the seventh embodiment. Even in the seventh embodiment, it is also possible to employ a configuration including no light splitting part  180  described earlier in other embodiments. Further, in the configuration of  FIG. 23  in which the frame-like member  230  is in the tapered shape, other components such as the light-emitting panel and the light source may have the configurations described in other embodiments. 
     Further, the shape of the flange part  230  is not limited to the shape illustrated in the drawing. For example, the flange part  230  may be formed with a plurality of members. Further, the illumination device  7  may also employ structure in which the flange part  230  is detachable or structure including no flange part  230 . It is also possible to configure the illumination device  7  so that the frame-like member  720  includes a horizontal part (flange surface  233 ) and the flange surface  233  includes a bright part region and a dark part region. The flange surface  233  may also be a nontransparent member. Further, the cross-sectional shape of the frame-like member  720  may also be a curved line shape (i.e., the frame-like member  720  may be in a curved surface shape). The frame-like member in a curved surface shape can serve as both of the frame-like member  720  and the flange part  230  shown in  FIG. 23 . 
     As described above, by using the illumination device  7  according to the seventh embodiment, in addition to obtaining the advantages of the first to sixth embodiments, the bright part region simulating a sunny region and the dark part region simulating a shady region become easier to visually recognize since the area of the sunlight expression part  130  captured in the observer&#39;s field of view increases. 
     Further, by using the illumination device  7 , a larger amount of light can be emitted from the bright part region  131  enlarging due to the increase in the area of the sunlight expression part  130 . 
       FIG. 24  is a principal part cross-sectional view schematically showing a configuration example of an illumination device  7   a  according to a modification of the seventh embodiment. In  FIG. 24 , each component identical or corresponding to a component shown in  FIG. 23  is assigned the same reference character as in  FIG. 23 . The illumination device  7   a  greatly differs from the illumination device  7  shown in  FIG. 23  in that a light guide part  740  for guiding the light emitted from the light source unit  140  is provided between the light source unit  140  and the frame-like member  720  including a part that extends outward toward the front. Incidentally, the illumination device  7   a  shown in  FIG. 24  differs from the illumination device  7  shown in  FIG. 23  also in that the flange part  230  of the frame-like member  720  does not include the sunlight expression part  130  or the light diffusion member  232 . However, the frame-like member  720  may also be configured to include the sunlight expression part  130  and the light diffusion member  232  also in the example shown in  FIG. 24 . 
     In the illumination device  7   a , one end of the light guide part  740  (in the example in the drawing, an end in the −X direction) is arranged to be in proximity to an end of the back surface of the frame-like member  720  on the light-emitting panel  110 &#39;s side. Further, the light source unit  140  is arranged at a position facing the other end of the light guide part  740  (in the example in the drawing, an end in the +X direction). The end of the light guide part  740  on the frame-like member  720 &#39;s side and the frame-like member  720  may be either fixed to each other by using a transparent adhesive agent or the like or facing each other via an air interface. 
     The light guide part  740  is provided corresponding to the light source unit  140  arranged on the back side of the frame-like member  720 , for example. For example, the light guide part  740  may be provided to cover a region of the back surface of the frame-like member  720  corresponding to the sunlight expression part  130  in a rear view. Incidentally, while the example shown in  FIG. 24  shows only a region corresponding to the bright part region  131 , in the dark part region  132  or a region corresponding to the dark part region  132 , one end of a light guide part  740  is arranged to be in proximity to an end of the back surface of the frame-like member  720  including the mask  122  on the light-emitting panel  110 &#39;s side. 
     In this example, the light guide part  740  is arranged along the shape of the frame-like member  720  so that a light incidence end is situated on an end side of the light-emitting panel  110  and a light emission end is situated on a central side of the light-emitting panel  110 . However, the light guide part  740  is arranged to be inclined with respect to the frame-like member  720  so that a part closer to the light source unit  140  is farther from the frame-like member  720  and a part farther from the light source unit  140  is closer to the frame-like member  720 . 
     The light guide part  740  in this example includes a light reflection diffusion member  750  that diffuses a part of the incident light (in this example, light from the light source unit  140 ). The light reflection diffusion member  750  is formed by printing a print material including a material that reflects and diffuses light, performing surface treatment (e.g., treatment for forming a rough surface that irregularly reflect light) on a member forming the light guide part  740 , sticking a film including a material that reflects and diffuses light, or the like. The light reflection diffusion member  750  is arranged at a position inside the light guide part  740  and on the light-emitting panel  110 &#39;s side and reflects and diffuses light traveling in the light guide part  740 . 
     In  FIG. 24 , when light from the light source unit  140  enters the light guide part  740 , the light guide part  740  guides the light as light heading for an opposing end, more specifically, light heading for the end of the frame-like member  720  on the light-emitting panel  110 &#39;s side (in the example in the drawing, light traveling in the −X direction), and emits the light from the opposing end. Further, the light guide part  740  reflects and diffuses a part of the light guided towards the opposing end with the light reflection diffusion member  750 , thereby turns the light into light traveling in the +Z direction, and emits the light. As above, a part of the light traveling in the light guide part  740  travels substantially in the −X direction from the end side towards the center of the light-emitting panel  110  and is incident upon the frame-like member  720 . Meanwhile, another part of the light traveling in the light guide part  740  is reflected and diffused by the light reflection diffusion member  750 , consequently travels in the +Z direction as the forward direction through a wall surface of the light guide part  740  (more specifically, a wall surface on the frame-like member  720 &#39;s side), and is incident upon the back side of the frame-like member  720  situated in front of the light guide part  740 . 
     The light arriving at the frame-like member  720  as above is partially reflected by the mask  122  if the mask  122  is there, thereafter diffused by the light transmission diffusion member  123 , and is emitted as the light L 2 , similarly to light incident upon another transmissive frame-like member. 
     Since a part of the light traveling in the light guide part  740  is extracted by the light reflection diffusion member  750  through the wall surface on the frame-like member  720 &#39;s side, the intensity of the light guided in the light guide part  740  decreases as the light travels in the light guide part  740 . In  FIG. 24 , the light emitted from the light source unit  140  and entered the light guide part  740  gradually decreases in the light intensity as the light travels in the −X direction as the light guide direction from the light incidence end situated at the left end of the light guide part  740  in  FIG. 24 . Accordingly, the light intensity of diffuse light L 3  (light emitted in the +Z direction) deriving from the guided light in the light guide part  740  also decreases as the position moves in the light guide direction from the light incidence end. 
     On the other hand, the light intensity of the diffuse light L 3  at the time of arriving at the back surface of the frame-like member  720  after being emitted in the +Z direction from the light guide part  740  attenuates depending on the distance D between the light guide part  740  and the frame-like member  720 . Namely, the light intensity of the diffuse light L 3  decreases with the increase in the distance D between the light guide part  740  and the frame-like member  720 . 
     In consideration of the above-described properties, in the illumination device  7   a  in this example, the light guide part  740  is arranged so that the distance to the frame-like member  720  decreases as the position moves in the light guide direction from the light incidence end. In the example shown in  FIG. 24 , the light emission end of the light guide part  740  is the closest to the frame-like member  720  and the light incidence end of the light guide part  740  is the farthest from the frame-like member  720 . With such an arrangement, even though the intensity of the diffuse light L 3  emitted from the light guide part  740  decreases as the position moves in the light guide part  740  towards the light guide end, that is, towards the central side of the light-emitting panel  110 , the amount of the attenuation of the diffuse light L 3  until arriving at the frame-like member  720  can be made to decrease as the position moves towards the light guide end. Consequently, variations in the intensity distribution of the diffuse light L 3  arriving at the back surface of the frame-like member  720  decrease and variations in the luminance in the bright part region formed on the light transmission diffusion member  123 &#39;s side of the frame-like member  720  decrease irrespective of the X direction position in the frame-like member  720 . 
     For example, an angle formed by the surface of the frame-like member  720  on which the sunlight expression part  130  is formed and the light guide direction of the light guide part  740  or the probability of occurrence of the diffuse light L 3  in the light guide part  740  (or the amount of attenuation of the guided light with respect to its traveling distance) may be adjusted so that the amount of attenuation of the guided light in the light guide part  740  with respect to the traveling distance and the amount of attenuation of the diffuse light L 3  emitted from the light guide part  740  with respect to the traveling distance cancel each other out. 
     As described above, by using the illumination device  7   a , the variations in the luminance in the bright part region can be decreased. 
     (8) Eighth Embodiment 
       FIG. 25  is a principal part exploded perspective view schematically showing a configuration example of an illumination device  8  according to an eighth embodiment.  FIG. 26  is a principal part perspective view schematically showing the configuration example of the illumination device  8 .  FIG. 27  is a rear view of the configuration example shown in  FIG. 26  as viewed from the back side of the frame-like member. A frame-like member  820  in the eighth embodiment has the same structure as any one of the frame-like members in the first to seventh embodiments. However, the illumination device  8  does not need to include the mask (more specifically, the mask  122 ,  122   a  or the like) in the first to seventh embodiments. 
     The illumination device  8  differs from the illumination devices in the first to seventh embodiments in not including the mask and in the structure of the aforementioned light reflection diffusion member  150 . More specifically, in the illumination device  8 , the light reflection diffusion member  150  has the function of the first light restriction member. Namely, the light reflection diffusion member  150  of the illumination device  8  is arranged only in a region of the frame-like member  120  facing the bright part region  131  and is configured so that the light from the light source unit  140  does not reach a region (reference character  152  in the drawing) of the frame-like member  120  facing the dark part region  132  or so as to reduce the amount of light reaching the region facing the dark part region  132 . Thus, in the illumination device  8 , no mask is provided on the front surface of the frame-like member  120  where the dark part region  132  is provided or on the back surface of the frame-like member  120 . 
     In the illumination device  8 , instead of the mask, a side surface  151  of the light reflection diffusion member  150  is provided in a boundary part between a region on the back side of the frame-like member  120  corresponding to the bright part region  131  and a region on the back side of the frame-like member  120  corresponding to the dark part region  132 . In this example, this side surface  151  corresponds to the first light restriction member. In the following description, such a surface provided in the boundary part between the region on the back side of the frame-like member  120  corresponding to the bright part region  131  and the region on the back side of the frame-like member  120  corresponding to the dark part region  132  and having the function of blocking light can be referred to as a blocking wall  151 . 
     Incidentally, the frame-like member may include the light reflection member  150   a  having no diffusing power instead of the light reflection diffusion member  150  also in this example; however, also in that case, the light reflection member  150   a  is assumed to be arranged only in the region of the frame-like member  120  facing the bright part region  131 . In other words, the light reflection member  150   a  is assumed to have the blocking wall  151  provided in the boundary part between the region facing the bright part region  131  and the region facing the dark part region  132 . 
     Incidentally, such a blocking wall  151  can also be, in a broad sense, regarded as an optical member provided in “a region corresponding to the dark part region  132 ” in “the optical path until the light emitted from the light source unit  140  enters the back surface of the frame-like member  120  and is emitted again from the front surface of the frame-like member  120  as the light heading for the space  112 ”. 
     Further, in the light reflection diffusion member  150 , the blocking wall  151  (side surface  151 ) may be configured so that the spacing between the light reflection diffusion member  150  and the frame-like member  120  gradually increases with the increase in the distance from the light emission surface  111  of the light-emitting panel  110 . With such a configuration, it is possible to leak out a part of the light emitted from the light source unit  140 . With this configuration, it is possible to form blurring similar to the blurring in the boundary part shown in  FIG. 15A . 
     As described above, by using the illumination device  8  according to the eighth embodiment, advantages similar to those of the first to seventh embodiments can be obtained even without providing the mask (e.g., the mask  122  or the mask  122   a ) on the surface of the frame-like member where the dark part region  132  is provided. However, the illumination device  8  can also be further provided with a mask similar to the mask in any one of the first to seventh embodiments. 
     (9) Modifications 
     In the illumination devices in the first to eighth embodiments described above, the light-emitting panel can also be a side light incidence panel upon which light is incident from the side. In that case, the frame forming part  12  may be provided on an end part of the light-emitting panel or in a space facing the end part. 
       FIG. 28  to  FIG. 30  are schematic cross-sectional views schematically showing configuration examples of illumination devices according to modifications of the embodiments. As shown in  FIG. 28  to  FIG. 30 , the positional relationship between the light-emitting panel  110  and the frame forming part  12  is not limited to the above-described examples. In these examples, the observer views the frame forming part  12  through the light-emitting panel  110 . In this case, the observer recognizes a region of the frame forming part  12  where the light restriction member is formed (or a region of the frame forming part  12  where no light extraction member is formed) as the dark part region  132 , for example. Further, the observer recognizes a region of the frame forming part  12  where the light extraction member is formed (or a region of the frame forming part  12  where no light restriction member is formed) as the bright part region  131 , for example. 
     For example, in the example of the illumination device shown in  FIG. 28 , the frame forming part  12  is implemented by the frame-like member  120  arranged lateral to the light-emitting panel  110 , more specifically, arranged in a space facing an end face of the light-emitting panel  110 . The frame-like member  120  shown in  FIG. 28  implements a reflective frame-like member by including the light reflection member  124  on the back side of the frame body  121  (in this example, on the side opposite to the side facing the space  112 ). In the illumination device in this example, the light absorptive mask  122   b , for example, is provided in the dark part region  132  or a region corresponding to the dark part region  132  between the light reflection member  124  and the light transmission diffusion member  123  provided close to the front surface of the frame-like member  120 . 
     Also in this example, it is possible to leave out the light transmission diffusion member  123 . In that case, the mask  122   b  may be provided in the dark part region  132  or a region corresponding to the dark part region  132  between the frame body  121  and the light reflection member  124 , such as on the back surface of the frame body  121  of the frame-like member  120 . 
     Here, the mask  122   b  can be a polarization mask, for example, to have the function of transmitting the light from the panel-purposed light source  110   a  incident upon the front side of the frame-like member  120  while blocking (absorbing) returning light as the incident light reflected by the light reflection member  124  and returning to the mask  122   b.    
     In the example shown in  FIG. 28 , the mask  122   b  is arranged on the back surface of the frame body  121  of the frame-like member  120  on the right side of the drawing. The example shown in  FIG. 28  is an example in which the whole region on the front side of the frame-like member  120  on the right side of the drawing is the dark part region  132  and the whole region on the front side of the frame-like member  120  on the left side of the drawing is the bright part region  131 . 
     Incidentally, it is also possible to leave out the mask  122   b  and the light reflection member  124  by using the mask  122   d  whose light reflectance varies in a surface. 
     Further, in the example shown in  FIG. 28 , the sunlight expression part  130  is made to emit light by using the panel-purposed light source  110   a  instead of the light source unit  140 . More specifically, light emitted from the panel-purposed light source  110   a  provided at an end part (opposing end part) of the light-emitting panel  110  opposing the light-emitting panel  110 &#39;s end part (provision end part) provided with the frame-like member  120 , passing through the light-emitting panel  110 , and thereafter emitted from the end part as the light guide end is used instead of the light from the light source unit  140 . 
     For example, upon the frame-like member  120  provided on the right side of the light-emitting panel  110  in  FIG. 28 , light emitted from the panel-purposed light source  110   a  provided on the left side of the light-emitting panel  110  in the drawing, guided in the light-emitting panel  110 , and emitted from the right-side end part of the light-emitting panel  110  in the drawing is incident. The light incident upon the front side of the frame-like member  120  as above passes through the light transmission diffusion member  123 , the frame body  121  and the mask  122   b  and is thereafter reflected by the light reflection member  124 . The light reflected by the light reflection member  124  is diminished by the mask  122   b  if it is in a region where the mask  122   b  exists, thereafter passes through the frame body  121  and the light transmission diffusion member  123 , and is emitted as the light heading for the space  112 . 
     For example, upon the frame-like member  120  provided on the left side of the light-emitting panel  110  in  FIG. 28 , light emitted from the panel-purposed light source  110   a  provided on the right side of the light-emitting panel  110  in the drawing, guided in the light-emitting panel  110 , and emitted from the left-side end part of the light-emitting panel  110  in the drawing is incident. The light incident upon the front side of the frame-like member  120  as above passes through the light transmission diffusion member  123  and the frame body  121  and is thereafter reflected by the light reflection member  124 . The light reflected by the light reflection member  124  is diminished by the mask  122   b  if it is in a region where the mask  122   b  exists, thereafter passes through the frame body  121  and the light transmission diffusion member  123 , and is emitted as the light heading for the space  112 . 
     Incidentally, while the frame-like member  120  is provided lateral to the light-emitting panel  110  in order to make use of light emitted from an end part of the light-emitting panel  110  in the example shown in  FIG. 28 , it is also possible, in a case where the light-emitting panel  110  is configured to emit light from the back surface, for example, to provide a frame-like member  120 , configured to receive the light emitted from the back surface of the light-emitting panel  110  and reflect the light forward, to the rear of the light-emitting panel  110  (more specifically, at a position close to a rear end part of the light-emitting panel  110 ). 
     In the example of the illumination device shown in  FIG. 29 , the sunlight is expressed by using side faces forming end parts of the light-emitting panel  110 , without providing a separate frame body as the frame forming part  12 . Namely, in the illumination device shown in  FIG. 29 , the frame forming part  12  is provided on the side faces forming the end parts of the light-emitting panel  110  (specifically, side faces inclined so as to withdraw into the back side). 
     In this example, the light-emitting panel  110  has an inclined surface, inclined with respect to the light emission surface  111 , in each end part, and the bright part region  131  and the dark part region  132  are provided on the inclined surface. In the example shown in  FIG. 29 , a mask  122   c  that transmits (prevents reflection of) the light heading for the light-emitting panel  110  from the panel-purposed light source  110   a  and blocks (e.g., absorbs, reflects or the like) the light from the light source unit  140  is provided in a region on the inclined surface where the dark part region  132  is provided. 
     Further, in a region on the inclined surface where the bright part region  131  is provided, an antireflection member  125  (e.g., antireflection film) that transmits (prevents reflection of) the light heading for the light-emitting panel  110  from the panel-purposed light source  110   a  and the light from the light source unit  140  may be provided. 
     Incidentally, the mask  122   c  may be left out in a case where the light from the light source unit  140  is reflected by the inclined surface even if no mask  122   c  is provided. Further, the antireflection member  125  may be left out in a case where the light from the light source unit  140  passes through the light-emitting panel  110  without being reflected by the inclined surface even if no antireflection member  125  is provided. 
     In the example shown in  FIG. 29 , the mask  122   c  corresponds to the light restriction member (more specifically, the first light restriction member). Further, the antireflection member  125  corresponds to the light extraction member. In the following description, the light extraction member provided for a transmissive frame forming part  12  as shown in  FIG. 29  can be referred to as a first light extraction member. 
     For example, the mask  122   c  in this example absorbs or reflects at least a part of the light from the light source unit  140  (in this example, the light from the light source unit  140  incident upon the back side of a side face of the light-emitting panel  110  from the rear of the light-emitting panel  110 ) in the dark part region  132  or a region corresponding to the dark part region  132  included in the frame forming part  12  provided on an end part of the light-emitting panel  110  and thereby decreases the amount of the light heading for the space  112  from the dark part region  132  compared with a case where the member does not exist. Accordingly, the intensity of the light heading for the space  112  from the dark part region  132  can be made lower than the intensity of the light heading for the space  112  from the bright part region  131 . 
     Further, for example, the antireflection member  125  in this example facilitates the transmission (more specifically, prevents the reflection) of at least a part of the light from the light source unit  140  (in this example, the light from the light source unit  140  incident upon the back side of a side face of the light-emitting panel  110  from the rear of the light-emitting panel  110 ) in the bright part region  131  or a region corresponding to the bright part region  131  included in the frame forming part  12  provided on an end part of the light-emitting panel  110  and thereby increases the amount of the light heading for the space  112  from the bright part region  131  compared with a case where the member does not exist. Accordingly, the intensity of the light heading for the space  112  from the bright part region  131  can be made higher than the intensity of the light heading for the space  112  from the dark part region  132 . 
     In such a configuration, the observer recognizes the bright part region  131  and the dark part region  132  on each inclined surface as a side face through the light emission surface  111  of the light-emitting panel  110 . 
     Incidentally, in the example shown in  FIG. 29 , the light-emitting panel  110  is assumed to be a diffusive panel including particles or the like. In that case, the light L 2  can be diffused by configuring the light-emitting panel  110  so that the light from the light source unit  140  enters the light-emitting panel  110  through the inclined surface of the light-emitting panel  110 , passes through the inside of the light-emitting panel  110 , and is thereafter emitted from the light emission surface  111 . In this case, the particles or the like included in the light-emitting panel  110  correspond to the light transmission diffusion member  123 . 
     As another method, it is also possible to diffuse the light L 2  by performing surface treatment of turning a region as a part of the light emission surface  111  of the light-emitting panel  110  for emitting the light from the light source unit  140  (region adjoining a side face) into a rough surface or the like. In this case, the surface-treated part formed on the light emission surface  111  to exhibit diffusing power corresponds to the light transmission diffusion member  123 . 
     While the frame forming part  12  is provided on the side faces of the light-emitting panel  110  included in the end parts of the light-emitting panel  110  in the example shown in  FIG. 29 , it is also possible to provide the frame forming part  12  on a region as a part of the back surface or the front surface of the light-emitting panel  110  (e.g., region adjoining a side face). 
     While the example in  FIG. 29  showed an example in which the end part where the frame forming part  12  is provided serves also as an incidence surface through which the light from the panel-purposed light source  110   a  enters the light-emitting panel  110 , the mask  122   c  may be replaced with the aforementioned mask  122  having no polarization dependence in a case where the end part does not serve also as the incidence surface for the light from the panel-purposed light source  110   a.    
     Further, in a case where the illumination device includes a transmissive frame-like member and the frame-like member is arranged at a position upon which the light from the panel-purposed light source  110   a  is incident, the configuration on the surface of the frame-like member may be made the same as the above-described configuration on the side face of the light-emitting panel  110 . For example, it is possible to provide the mask  122   c  in the dark part region  132  of the frame-like member or a region of the frame-like member corresponding to the dark part region  132  and provide the antireflection member  125  in the bright part region  131  of the frame-like member or a region of the frame-like member corresponding to the bright part region  131 . While the illumination device includes the light source unit  140  in  FIG. 29 , the illumination device may also be configured more simply to make the panel-purposed light source  110   a  serve also as the light source unit  140 . Further, it is not necessarily essential to arrange light sources on both sides in the drawing; the illumination device may also employ a configuration in which a light source is arranged only on one side. In that case, the end part of the light-emitting panel  110  on the side where the panel-purposed light source  110   a  is arranged does not need to be inclined. Further, since an end part (opposing end part) opposing the end part of the light-emitting panel  110  on the side where the panel-purposed light source  110   a  is arranged does not serve also as the incidence surface for the light from the panel-purposed light source  110   a , the mask  122   c  arranged on the opposing end part may also be the mask  122  having no polarization dependence. 
     It is also possible, for example, to leave out the light source unit  140  and configure the frame forming part  12  to emit light by using the light from the panel-purposed light source  110   a  as shown in  FIG. 30 . In the example shown in  FIG. 30 , the frame forming part  12  is formed on the back surface forming an end part of the light-emitting panel  110 . Further, a light deflection member  126  for extracting the light emitted from the panel-purposed light source  110   a  and guided in the light-emitting panel  110  from the light emission surface  111  is provided in a region on the back surface of the light-emitting panel  110  specified as the bright part region  131 . 
     Here, the light deflection member  126  is an optical member having a deflection function of deflecting the light propagating in the light-emitting panel  110  at the back surface of the light-emitting panel  110  and thereby having the light emitted from the light emission surface  111 . In the following description, the light deflection member  126  can be referred to as a second light deflection member. 
     At least a part of the light deflected by the light deflection member  126  is emitted at an angle not satisfying the total reflection condition at the light emission surface  111 . Here, light propagating in the light-emitting panel  110  without being incident upon the light deflection member  126  is reflected by the light emission surface  111  and is not emitted from the light emission surface  111 , for example. 
     The light deflection member  126  is implemented by a prism, for example. In that case, the light deflection member  126  may be arranged continuously to cover the bright part region  131  on the back surface of the light-emitting panel  110 . In this case, the size of each prism may be varied. Further, the light deflection member  126  can be substituted with a member other than a prism having the deflection function. The light deflection member  126  can be substituted with a print pattern or a surface-treated part such as a rough surface, for example. In this case, light is diffused and reflected by the print pattern or the surface-treated part such as a rough surface, by which light entering the region in the light-emitting panel  110  where the light deflection member  126  is formed is emitted from the light emission surface  111 . In this case, density of the print pattern per unit area may be varied. It is also possible to stick a film having the light diffusion function. 
     Further, in the example shown in  FIG. 30 , an antireflection member  125   a  for preventing the light emitted from the panel-purposed light source  110   a  and guided in the light-emitting panel  110  from heading for the light emission surface  111  may be provided in a region on the back surface of the light-emitting panel  110  specified as the dark part region  132 . Incidentally, the antireflection member  125   a  can be left out in a case where the light-emitting panel  110  is configured so that the light propagating in the light-emitting panel  110  is reflected by the light emission surface  111  and is not emitted from the light emission surface  111  as described earlier. 
     Also with a configuration like that shown in  FIG. 30 , the observer recognizes the bright part region  131  and the dark part region  132  on the back surface through the light emission surface  111  of the light-emitting panel  110 . 
     In the example shown in  FIG. 30 , the light deflection member  126  corresponds to the light extraction member. Further, the antireflection member  125   a  corresponds to the light restriction member (more specifically, the second light restriction member). In the following description, the light extraction member provided for a reflective frame forming part  12  as shown in  FIG. 30  can be referred to as a second light extraction member. 
     For example, the light deflection member  126  in this example deflects (including reflection) at least a part of the incident light and thereby increases the amount of the light heading for the space  112  from the bright part region  131  compared with a case where the member does not exist. 
     Further, for example, the antireflection member  125   a  in this example allows at least a part of the incident light (in this example, the light guided in the light-emitting panel  110 ) to pass through the dark part region  132  or a region corresponding to the dark part region  132  without being reflected in the region and thereby decreases the amount of the light heading for the space  112  from the dark part region  132  compared with a case where the member does not exist. 
     Also in this example, the end part where the frame forming part  12  is formed is not limited to the back surface. For example, it is also possible to provide the frame forming part  12  on a region as a part of a side face or the front surface of the light-emitting panel  110 . 
     Incidentally, in a case where the frame forming part  12  is provided on an end part of the front surface, a third light deflection member  125   b  (not shown) that reflects at least a part of the incident light (in this example, the light guided in the light-emitting panel  110 ) in the dark part region  132  or a region corresponding to the dark part region  132  and turns the light into light not heading for the space  112  may be provided instead of the antireflection member  125   a . Here, the third light deflection member  125   b  may also be represented as a light deflection member that is provided in the dark part region  132  or a region corresponding to the dark part region  132  and deflects (including reflection) the light emitted from the panel-purposed light source and guided in the light-emitting panel into an angle not heading for the space  112 . Incidentally, in a case where the front surface of the light-emitting panel is functioning as a part of a light guide path for guiding the light incident from the panel-purposed light source by means of total reflection, the third light deflection member  125   b  can be the light-emitting panel&#39;s front surface itself. The third light deflection member is an example of the second light restriction member. 
     Further, the configuration shown in  FIG. 30  is also applicable to the frame-like member. For example, the configuration on the surface of a reflective frame-like member may be made the same as the above-described configuration on the back surface of the light-emitting panel  110 . For example, it is possible to provide the antireflection member  125   a  in the dark part region  132  of the frame-like member or a region of the frame-like member corresponding to the dark part region  132  and provide the light deflection member  126  in the bright part region  131  of the frame-like member or a region of the frame-like member corresponding to the bright part region  131 . 
     It is possible to appropriately combine some of the configurations of illumination devices in the above first to eighth embodiments. For example, a plurality of frame-like members may be arranged in front of, lateral to, or to the rear of the light-emitting panel. It is also possible to arrange a plurality of frame forming parts  12  on a side face, the front surface or the back surface forming an end part of the light-emitting panel. It is also possible to use both of the frame-like member and the frame forming part  12  making use of an end part of the light-emitting panel  110 . 
     In the present application, a range represented by a term like “parallel” and “orthogonal” indicating the position of a component, positional relationship between components or the shape of a component is a range taking into account tolerances in the manufacture, variations in the assembly, or the like. Therefore, when such a term like “parallel” and “orthogonal” indicating the position of a component, positional relationship between components or the shape of a component is used without describing “substantially” in the present application, the range represented by such a term means a range taking into account the tolerances in the manufacture, the variations in the assembly, or the like. 
     Further, while embodiments of the present invention have been described as above, the present invention is not limited to these embodiments. For example, while the examples described above showed examples in which the bright part region  131  and the dark part region  132  as the sunlight expression part  130  are provided on the frame-like member or an end part of the light-emitting panel corresponding to the frame-like member, it is also possible to provide only the bright part region  131  or only the dark part region  132 , for example. 
     Based on the above-described embodiments, the contents of the present invention will be described below as appendixes. 
     Appendix 1 
     An illumination device comprising: a frame forming part ( 12 ) that is provided at at least one position on an end part of a light-emitting panel having a light emission surface or in a vicinity of the light-emitting panel and includes a bright part region ( 131 ) and a dark part region ( 132 ); 
     a light source ( 140 ,  110   a ) that emits light to be incident upon the frame forming part; and 
     a light amount regulation part ( 22 ) that makes intensity of light heading for a space facing the light emission surface from the dark part region weaker than intensity of light heading for the space from the bright part region in the light entering the frame forming part from the light source, or strengthens the intensity of the light heading for the space from the bright part region than the intensity of the light heading for the space from the dark part region in the light entering the frame forming part from the light source. 
     Appendix 2 
     The illumination device according to appendix 1, comprising a first light transmission diffusion member ( 123 ) provided at a position closer to the space than the light amount regulation part ( 22 ). 
     Appendix 3 
     The illumination device according to appendix 1 or 2, wherein the frame forming part ( 12 ) includes a frame-like member ( 120 ,  120   a ,  220 ,  320 ,  420 ,  520 ,  520   a ,  520   b ,  620 ,  720 ,  820 ) on which the bright part region and the dark part region are provided. 
     Appendix 4 
     The illumination device according to appendix 3, wherein the frame-like member includes a light transmissive member ( 121 ,  121   a ), 
     the light source is arranged to make light enter the frame-like member from a back side of the frame-like member when a surface of the frame-like member on a side facing the space is defined to be on a front side and a side opposite to the front side is defined as the back side, and 
     the light amount regulation part includes a first light restriction member ( 122 ,  122   a ,  122   c ,  151 ) that is arranged in the dark part region or a region corresponding to the dark part region in an optical path until the light emitted from the light source enters a back surface of the frame-like member and is emitted from a front surface of the frame-like member as light heading for the space and absorbs or reflects at least a part of incident light. 
     Appendix 5 
     The illumination device according to appendix 4, wherein the first light restriction member is a mask ( 122 ,  122   a ,  122   c ) that decreases an amount of the light heading for the space from the dark part region by blocking a part of light advancing to the space through the frame-like member. 
     Appendix 6 
     The illumination device according to appendix 5, wherein 
     the light transmissive member ( 121  in  FIG. 14 ) is configured so that its thickness increases with an increase in a distance from the light emission surface in at least a region including the bright part region or the dark part region, and 
     the mask is provided on the back side of the light transmissive member. 
     Appendix 7 
     The illumination device according to appendix 5 or 6, wherein the mask ( 122   a ) has light transmittance varying in a surface and is configured so that the light transmittance of a boundary part between the dark part region and the bright part region increases with an increase in a distance from the light emission surface. 
     Appendix 8 
     The illumination device according to any one of appendixes 4 to 6, wherein the mask ( 122   a ) has light transmittance varying in a surface and is configured so that the light transmittance of the dark part region becomes lower than the light transmittance of the bright part region. 
     Appendix 9 
     The illumination device according to any one of appendixes 4 to 8, further comprising a first light deflection member ( 150 ,  150   a ,  160 ) that deflects the light from the light source and guides the light to the frame-like member, 
     wherein the first light deflection member includes a light reflection member ( 150   a ) that reflects the light from the light source unit and guides the light to the frame-like member or a light reflection diffusion member ( 150 ) that reflects and diffuses the light from the light source unit and guides the light to the frame-like member. 
     Appendix 10 
     The illumination device according to appendix 9, wherein the first light deflection member further includes a light transmission diffusion member ( 160 ) that is provided between the frame-like member and the light reflection member or the light reflection diffusion member. 
     Appendix 11 
     The illumination device according to appendix 9 or 10, wherein the light reflection member or the light reflection diffusion member includes a blocking wall ( 151 ) as a surface having a function of blocking light in a boundary part between a region on the back side corresponding to the bright part region  131  and a region on the back side corresponding to the dark part region  132 . 
     Appendix 12 
     The illumination device according to any one of appendixes 4 to 11, further comprising a light guide part ( 740 ) that scatters the light from the light source while guiding the light, wherein 
     the light guide part is configured so that its region farther from the frame-like member emits more scattered light, and 
     the frame-like member receives the scattered light emitted from the light guide part and emits light heading for the space. 
     Appendix 14 
     The illumination device according to appendix 3, wherein 
     the frame-like member includes a light reflection member ( 124 ), 
     the light source is arranged to make light enter the frame-like member from a front side of the frame-like member when a surface of the frame-like member on a side facing the space is defined to be on the front side and a side opposite to the front side is defined as a back side, and 
     the light restriction member includes a second light restriction member ( 122   b ,  122   d ,  125   a ,  125   b ) that is arranged in the dark part region or a region corresponding to the dark part region in an optical path until the light emitted from the light source enters a front surface of the frame-like member and is emitted again from the front surface as light heading for the space and absorbs or transmits at least a part of incident light or deflects at least a part of the incident light into an angle not heading for the space. 
     Appendix 15 
     The illumination device according to any one of appendixes 3 to 14, wherein 
     the frame-like member includes a frame body ( 121   a ) provided on a light emission direction side of the light emission surface and including an opening part ( 170 ), and 
     the bright part region and the dark part region are provided at least on a side wall ( 171 ) of the opening part. 
     Appendix 16 
     The illumination device according to any one of appendixes 3 to 15, wherein when a traveling direction of the light emitted from the light emission surface is defined as a direction toward a front, the frame-like member has a shape that extends outward toward the front. 
     Appendix 17 
     The illumination device according to any one of appendixes 3 to 16, wherein the frame-like member is arranged to surround at least one of the space and the light-emitting panel. 
     Appendix 18 
     The illumination device according to any one of appendixes 3 to 17, comprising a flange part that is connected to a farthest end part of a region of the frame-like member where at least the bright part region or the dark part region is provided, farthest from the light emission surface, and extends outward from the end part. 
     Appendix 19 
     The illumination device according to appendix 18, wherein a frame body forming the frame-like member and the flange part are formed integrally. 
     Appendix 20 
     The illumination device according to appendix 1 or 2, wherein 
     the frame forming part is formed on a surface forming an end part of the light-emitting panel, and 
     the light amount regulation part includes a mask ( 122   c ) that is provided in a region on the surface specified as the dark part region and transmits light heading for the light-emitting panel from a panel-purposed light source while blocking the light from the light source or an antireflection member ( 125 ) that is provided in a region on the surface specified as the bright part region and transmits the light heading for the light-emitting panel from the panel-purposed light source and the light from the light source. 
     Appendix 21 
     The illumination device according to appendix 1 or 2, wherein 
     the frame forming part is formed on a surface forming an end part of the light-emitting panel, and 
     the light amount regulation part includes a second light deflection member ( 126 ) that is provided in a region on the surface specified as the bright part region and deflects light emitted from a panel-purposed light source and guided in the light-emitting panel and thereby has the light emitted from the light emission surface or a second light restriction member ( 125   a ,  125   b ) that is provided in a region on the surface specified as the dark part region and transmits or deflects the light emitted from the panel-purposed light source and guided in the light-emitting panel and thereby turns the light into light not heading for the space. 
     Appendix 22 
     The illumination device according to any one of appendixes 1 to 21, comprising a light splitting part that splits the light from the light source into light heading for an incidence surface of the light-emitting panel and light heading for the frame forming part. 
     Appendix 23 
     The illumination device according to any one of appendixes 1 to 22, wherein the light incident upon the frame forming part includes light emitted from the light source, passing through the light-emitting panel and being incident upon the frame forming part. 
     Appendix 24 
     The illumination device according to appendix 23, wherein the light incident upon the frame forming part includes light emitted from the light source, being incident upon an end face of the light-emitting panel, being guided in the light-emitting panel and thereafter being emitted from the light-emitting panel. 
     Appendix 25 
     The illumination device according to any one of appendixes 1 to 24, comprising a light-emitting panel that includes an optical medium on a nanometer order and emits scattered light generated by having incident light scattered by the optical medium from the light emission surface as the light-emitting panel. 
     Appendix 26 
     The illumination device according to any one of appendixes 1 to 25, wherein a ratio of luminance or luminous flux of the bright part region relative to the light emission surface in a state in which the light-emitting panel is emitting light is within a range of 1/20 to 30. 
     Appendix 27 
     The illumination device according to any one of appendixes 1 to 25, wherein a difference between a relative color temperature of the light emitted from the light emission surface and a relative color temperature of the light emitted from the bright part region in a state in which the light-emitting panel is emitting light is greater than or equal to 20000 K and less than or equal to 98000 K. 
     DESCRIPTION OF REFERENCE CHARACTERS 
     
         
           1 - 8 ,  1   a ,  4   a ,  5   a ,  5   b ,  7   a : illumination device 
           110 : light-emitting panel 
           111 : light emission surface 
           112 : space 
           12 : frame forming part 
           22 : light amount regulation part 
           120 ,  120   a ,  220 ,  320 ,  420 ,  520 ,  520   a ,  520   b ,  620 ,  720 ,  820 : frame-like member 
           121 ,  121   a : frame body 
           122 ,  122   a ,  122   b ,  122   c ,  122   d : mask 
           122   c : polarization mask 
           123 : light transmission diffusion member 
           124 ,  124   a : light reflection member 
           125 ,  125   a : antireflection member 
           126 : light deflection member 
           130 : sunlight expression part 
           131 : bright part region 
           132 : dark part region 
           133 : boundary part 
           140 ,  140   a : light source unit 
           150 : light reflection diffusion member 
           151 : blocking wall 
           150   a : light reflection member 
           160 : light transmission diffusion member 
           170 : opening part 
           171 : side wall 
           172 : storage part 
           180 : light splitting part 
           110   a : panel-purposed light source 
           115 : panel-purposed light source drive unit 
           116 : lighting control unit 
           145 : light source drive unit 
           230 : flange part 
           233 : flange surface 
           231 : plate-shaped part 
           232 : light diffusion member 
           740 : light guide part 
           750 : light reflection diffusion member