Abstract: A casing of an electronic device has a base member, a cover, a bracket and a fastener. The base member made of a bent metal plate has a base and at least three base side walls extending upward from sides of the base. The cover is made of a bent metal plate that is thinner than that of the base member and has a top and at least three cover side walls extending downward from sides of the top. Lower parts of two opposed cover side walls and two opposed base side walls are overlapped with each other thereby to form overlapped portions. The bracket is fixed by the fastener to the base side wall and the cover side wall at the overlapped portion. At least one end portion of the base side wall to which the bracket is fixed and one end portion of the adjacent base side wall are overlapped and connected with each other thereby to form an overlapped end portion.

Abstract: An optical waveguide according to the present invention has a light exit surface located on a side opposite of a back surface. An incident surface connects the back surface and the light exit surface with each other. A plurality of saw-tooth grooves are formed on the back surface. Surfaces defining the saw-tooth grooves include first guide surfaces that reflect light that enters the optical waveguide through the incident surface so that the light advances toward the first guide surface. A plurality of curved surface prisms are provided on the light exit surface. Each prism has a peak line. An arcuate cross-section groove is provided between the peak lines of each adjacent pair of the prisms. Each arcuate cross-section groove is defined by a section of the light exit surface between the peak lines of the corresponding prisms.