A switch mode power supply has a first and second branch of an inductive element; a first switching element and a second switching element connected in series. The evaluation unit has a drive load detecting function of detecting a drive load of the blower, and a conveyance state determining function of determining whether the conveyance state reached a predetermined conveyance state, based on the detected drive load. Concurrently, the one-dimensional or two-dimensional optical reading apparatus measures a length or a spread area of the reacted portion. The block readwrite controller is coupled between the memory array and an external interconnect.