An imaging optical system includes an aperture stop, a positive first lens group, and a positive or negative second lens group. Friction is thereby generated between metal interconnects, whereby the component is bonded on circuit substrate. The management controller is operable to asynchronously send management information to the operating system over the communication channel. Further, the zero current detecting circuit can detect a timing at which the charging and discharging voltage of the capacitor as the timing of zero current flowing through the inductor. The circuit module can also include a connector edge of the printed circuit board extending through the housing, and a bracket coupled to the housing including members to surround and protect the connector edge. The generator is arranged to generate electricity upon a reciprocating movement of the drive shaft relative to the stator, and the piston is connected to the drive shaft so as to transmit the reciprocating movement of the piston to the drive shaft.