According to the present invention, even if information on a page displayed on a browser browsed by a user shifts to another page, the user can select and store a necessary page. The dynamic feedback control circuit is capable of changing a clock frequency of a clock signal supplied the charge pump from a first non-zero value to a second non-zero value depending on the difference between the word line voltage and a target threshold voltage. Both the discharge sound attenuator and the suction sound attenuator can further include filter media disposed within their internal cavities. The collar rests against the flange plate and is joined with the flange plate.