Patent attributes
A cartridge includes a container, a light guide including incident and emergent portions, and a cover including outer and inner surfaces. When a direction directing from the outer surface toward the inner surface is a first direction, and a direction in which the incident and emergent portions are arranged is a second direction, (i) the outer surface is recessed toward a downstream side of the first direction between the incident and emergent portions, (ii) a first end of a bottom of the recessed portion on an incident portion side is positioned on a side downstream with respect to the first direction, of a second end of the bottom on an emergent portion side, and (iii) the bottom is curved so as to be recessed toward the downstream side of the first direction between the first and second ends relative to an imaginary rectilinear line connecting these ends.
