A vacuum cleaner includes a dust collector that compresses dust stored inside a dust container to minimize the volume of the dust. The fast cell search method disclosed detects the \u201cclass indices\u201d with simple processing. A post-development processing control portion causes the intermediate lateral conveyance portion and the developing portion to operate continuously from and after a development process and then stop. The other two leads are used for sensing voltages produced by the thermopile and the RTD. The conductor and receiver are positioned relative to one another such that movement of the receiver magnet creates a second time-varying magnetic field in a vicinity of the conductor to thereby induce current in the conductor. The memory device may generate a relatively large flat band voltage gap according to an applied bias voltage.