Patent ID: 8002278

Claim:
A printing apparatus comprising: a housing including a feeding tray and an ejecting tray; an image forming unit disposed in said housing; a drive motor disposed in said housing; and a driving device disposed in said housing and driven by said drive motor, said driving device being adapted to convey a sheet of paper from said feeding tray onto said ejecting tray and including: a. a first driving unit including a sun gear rotatable about an axis, a planet carrier rotatable about the axis, and a planetary gear disposed rotatably on said planet carrier and meshing with said sun gear, and b. a second driving unit including a driven gear meshing with said planetary gear; a movable member movable in said housing between first and second positions, wherein when said movable member is moved from said first position to said second position, said planetary gear is pushed by said movable member to remove from said driven gear; and a coiled compression spring disposed between said movable member and said housing for biasing said movable member to said second position; wherein said planet carrier is pivotable relative to said sun gear to remove said planetary gear from said driven gear; and said image forming unit includes a toner cartridge disposed removably in said housing and positioned such that, when said toner cartridge is inserted into said housing, said movable member is pushed by said toner cartridge to compress said coiled compression spring so that said movable member is moved to said first position, thereby allowing said planetary gear to mesh with said driven gear, and when said toner cartridge is removed from said housing, said movable member is biased by said coiled compression spring to said second position to thereby remove said planetary gear from said driven gear.