Patent ID: 7286266

Claim:
A printer forming halftone spots in cells each having a plurality of pixels by irradiating an exposure beam, said printer comprising: a halftone processor for converting M-bit image data into N (M>N)-bit drive pulse width data for driving said exposure beam, said halftone processor including: a threshold matrix including a plurality of threshold values corresponding to said plurality of pixels; a converter circuit for comparing said each of threshold values output from said threshold matrix with said image data after superposing noise to one of said each of threshold values and said image data, to thereby generate drive pulse width data in accordance with said comparison results; and a pulse position determining circuit for determining a position of a drive pulse for a pixel under processing in accordance with drive pulse width data of pixels adjacent to said pixel under processing; wherein a drive pulse signal is generated at said determined drive pulse position according to said drive pulse width data.