An electrically powered linear actuator having a thrust assembly, a motor with a rotor surrounding at least a portion of the thrust assembly and a rotary encoder with a rotation sensing member rotatable with the rotor. Each shift register stage has a pull-up unit, a carry unit, a carry control unit, an input unit and a pull-down unit. To link digitized images, a copy of a digitized image of one serial section is positioned over a digitized image of another serial section. The capacity reflects a current amount of available power for the battery minus the amount of power to reserve. An image display condition of the liquid crystal panel of the display apparatus is captured by the display apparatus itself. The curved edge displays operational characteristics of the headphones.