Patent ID: 7140795

Claim:
A printer comprising: a sheet storage unit for storing printing sheets, the sheet storage unit having a storage tray; a pick-up unit for ejecting one of the printing sheets stored in the sheet storage unit at a time; a delivery unit for delivering the printing sheet ejected from the pick-up unit; a printing unit for printing an image on the printing sheet delivered from the delivery unit; and a sheet discharge unit for discharging the printing sheet sent from the printing unit, the units being disposed inside a chassis having a slot, wherein, the printer has a chassis and the chassis has slot within with the storage tray can be inserted, the storage tray comprises a sheet storage case for strong a plurality of printing sheets in a stack and having an opening on at least one side and a cover for covering the at least a portion of the opening on the sheet storage case, the cover comprises a cover body and an moveable member supported by the cover body so that the moveable member can freely open and close the opening on the sheet storage case, the moveable member being pivotally attached to the cover body and having locking protrusions extending from those portions pivotally attached to the cover body, the protrusions having a camming surface, the pick-up unit can eject one of the printing sheets at a time from the sheet storage case when the entire storage tray is disposed inside the slot of the chassis, the moveable member can be opened and closed and the printing sheet can be stored in or ejected from the sheet storage case when the storage tray is partly pulled out of the slot of the chassis, the sheet storage case has locking grooves on opposite parallel sides thereof in which the locking protrusion of the moveable member engages, each locking groove having a releasing engagement portion and a stopping engagement portion, the locking protrusions engage with the releasing engagement portions to lock the moveable member in a cover-open position when the moveable member is opened, the locking protrusions engage with the stopping engagement portions to lock the moveable member in a cover-closed position when the moveable members are closed, and the locking protrusions being configured to slide on their camming surfaces between the stopping engagement portions and the releasing engagement portions.