Patent ID: 6862171

Claim:
A portable electronic device comprising: an expansion base module including a housing that has front and rear ends and opposite first and second side walls that extend between said front and rear ends in a longitudinal direction, each of said first and second side walls being formed with parallel upper and lower sliding grooves that extend in said longitudinal direction and that open toward each other in a transverse direction relative to said longitudinal direction; a system module mounted slidably on said expansion base module and having two opposite sides; and a pair of sliding units mounted slidably and respectively on said first and second side walls of said housing, respectively connected to said opposite sides of said system module, and slidable relative to said expansion base module in said longitudinal direction, each of said sliding units including a sliding seat, a first upper rolling member that is rotatably mounted on said sliding seat, said sliding seat is disposed outwardly of said lower sliding groove in the respective one of said first and second side walls, that is received in said upper sliding groove in the respective one of said first and second side walls, and that is in rolling contact with the respective one of said first and second side walls, and a first lower rolling member that is rotatably mounted on said sliding seat, said sliding seat is disposed outwardly of said upper sliding groove in the respective one of said first and second side walls, that is received in said lower sliding groove in the respective one of said first and second side walls, and that is in rolling contact with the respective one of said first and second side walls.