An illumination device having a light emitting device using organic electroluminescence (hereinafter, referred to as “organic EL”) is increasingly used. For example, the device is put to practical use for a cell-phone display. Compared with conventional illumination devices such as a fluorescent lamp, the illumination device using organic EL has advantages that it has energy-saving property, that it has low heat generating property, that it is thin and lightweight, and that it is environmentally friendly. Since the illumination device using organic EL is a surface light source, a wide range illumination is capable of being attained, or the device becomes flexible when a plastic substrate is used, and therefore the device is capable of being applied to an illumination device which is excellent in design. For this reason, organic EL is being expected as not only illumination device for housing, offices, or vehicles, but also for decorative illumination, or POP illumination.
As an organic EL light emitting device, for example, in Patent Literature 3, planar light emitting device in which luminance unevenness is capable of being reduced, and the area of non-light emitting portion is capable of being reduced is described. In this technique, the distance between predetermined two parallel sides of four sides of a rectangle light emitting portion constituted by a region where only an organic layer is interposed between an planar anode and a planar cathode and the outer circumferential edges of a transparent substrate is smaller than the distance between other two parallel sides of the four sides and the transparent substrate, a cathode power supplying portion and an anode power supplying portion are arranged along the other two parallel sides of the light emitting portion, and anode power supplying portions are arranged on both sides of the cathode power supplying portion in the width direction.
Patent Literature 1 describes an organic EL element in which takeoff terminals of an anode and a cathode are arranged on a short side of a transparent substrate and which has a light emitting region the width of electrode wiring pattern is narrow. Further, Patent Literature 2 describes an organic EL element in which a cathode has a smaller electric resistance than that of an anode, and in which by making the area of the surface of an anode terminal which is connected to the outside larger than that of the surface of a cathode terminal which is connected to the outside, thereby reducing luminance unevenness.
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