A break-action firearm with a breech housing, a barrel section that can pivot about a hinge bearing on the breech housing, and a removable fore-end, which contains on its front end a locking mechanism and on its rear end a bearing section for pivoting connection to the breech housing. Afterwards, a closed-loop tracking control operation of the optical disk drive is performed according to the input tracking error signal calibrated with the dynamic offset. The organic layer is a layer that generates light by recombination of charge carriers. The camera can a user to move between full screen display of stored images and the browsing mode multiple times, with little repetitive finger andor hand motion, without blocking viewing of the screen, and while allowing the hands to be retained in a convenient picture taking position. The second Schmidt trigger generates a PWM output signal with a variable frequency in accordance with the first and second currents.