The present disclosure provides a vacuum cleaner including a nozzle base having a main suction opening and a housing pivotally mounted on the nozzle base. Also present is a spring arm, which is connected to one side wall and extends in the direction of the opposite side wall and is able to pivot resiliently toward and away from the base plate within a flexion zone. The terminal receives the SIB including the updated access barring information immediately without waiting for the arrival of next modification period, resulting in improvement of access barring efficiency. Conversely, if the macula is in the process of degenerating by the progressive loss of protective pigments, then the impinging of the narrow band of visible blue light upon the macula, via the alternate apertures, will evoke the fixation reflex. The encoder introduces a global full search around a candidate from a coarser level, in case an initial local search fails.