An image processing device includes a pre-processing unit, an adder, a quantization unit, a post-processing unit and a surrounding error calculating unit. This arrangement, or layout, is applicable to electronic hand-held or desktop computing, typing, and calculating devices, and assists users in locating letters and typing more efficiently. Since a portion of the insulating film extending off the sidewalls is removed, there is no need for etching of the insulating film when the contact holes are formed and only an insulating film is etched. In accordance with the number of the drive lines D1 to Dn to be connected to the drive current source 70, the control means 8 changes the resistances of the scanning switch means 21 to 2m corresponding to the scanning lines S1 to Sm connected to the second potential to become the unselected state, into at least two stages. In addition, a leaf spring 61 is provided which provides the catching hooks with an elastic force that prevents the catching hooks from being inadvertently detached from the stoppers in a state in which the catching hooks are caught to the stoppers this structure prevents during the opening and closing operation of any one of the doors the other door from being opened. The thermal protection device may include a temperature sensor and a comparator for generating an over temperature flag signal usable for turning off the overheated power transistor.