A rotation detective circuit of a dc brushless motor using a fixed bias voltage includes a transistor, and a signal adjuster. Each of the link members includes two horizontally arranged and parallel longitudinal outboard stringers and a horizontally arranged and parallel longitudinal center stringer centered between the two outboard stringers. The alignment key also includes first and second opposed, inwardly facing jaw members shaped for longitudinally bridging across a predetermined exterior portion of adjacent first and second sidewalls, respectively, of the adjacent channel sections. In one approach, the controller receives a request to transfer data to a receiver. Though titanium oxide is a material which tends to manifest a crystalline structure even in the form of a thin film, a mixed high refractive dielectric film can be obtained, containing titanium oxide causing little change over time in optical properties by rendering the resulting thin film amorphous by inhibiting growth of a crystal of titanium oxide by adding another metal oxide.