Patent ID: 6919977

Claim:
A laser printer comprising: a laser source for producing a laser beam, a torsion oscillator comprising: a plate member having an upper surface, a lower surface, and a rotational axis and being located in the path of the laser beam, a frame disposed in a spaced apart relation to the plate member, a torsion spring mount for mounting the plate member on the frame and for yieldably resisting oscillation of the plate member with a torsion spring force, a reflective surface disposed on a surface of the plate member for reflecting the laser beam, at least one magnet disposed on the plate, and at least one coil located on the frame for producing an oscillation force on the at least one magnet when an alternating electric current is applied to the at least one coil to thereby oscillate the reflective surface about the rotational axis to a rotational angle of oscillation at an oscillation frequency to scan the laser beam through a scanning pattern in at least first and second directions at the oscillation frequency, a imaging surface disposed in the path of the scanning pattern so that the laser beam scans across the imaging surface, a drive mechanism for moving the imaging surface at an imaging surface speed, and a control circuit for controlling the electric current provided to the at least one coil to control the oscillator.