US Patent 7390137 Writing instrument

A writing instrument comprising a smooth elongate case has a recessed switch for extending and retracting the tip of an ink cartridge. This allows the tip to be extended and retracted with one hand, while at the same time preventing the switch from being snagged by the contents or threads inside a pocket. A second embodiment provides two cartridges and a three-way switch, allowing one tip to be extended at one end of the instrument while the other end remains within the case. A third embodiment utilizes a single cartridge with two writing tips, one at either end.