US Patent 9863614 Beam-control member and illumination device

A beam-control member has a substantially cylindrical holder that is light-permeable, and a first beam-control member disposed on an end surface of the holder, the first beam-control member reflecting part of the light emitted from a light-emitting element and admitting part of the light. A guide protrusion and a tab are provided on the end surface of the holder. A concave portion corresponding to the tab is provided on an outer circumferential part of one surface of the first beam-control member. The first beam-control member is radially mated in a rotatable manner along the guide protrusion. Rotating the first beam-control member on the end surface of the holder so that the tab and the concave portion engage causes the first beam-control member to be secured on the end surface of the holder.