Optical image forming device having a plurality of drawing beams and a monitoring beam

An optical image forming device comprising:

• a scanning device comprising a scanning lens for scanning, in a predetermined scanning range in a main scanning direction, a plurality of drawing beams on an image plane and a monitoring beam;
• said plurality of drawing beams being scanned such that drawing beams adjacent to each other in a sub-scanning direction pass a predetermined position in the scanning range on said image plane at a different time, said sub-scanning direction being transverse to said main scanning direction, said monitoring beam being scanned prior to scanning said drawing beam;
• a scale clock generator that generates scale clock signals based on said monitoring beam which passed said scanning lens for identifying positions of said monitoring beam in said scanning range;
• an acoustooptic element through which said plurality of drawing beams pass, said acoustooptic element modulating each of said drawing beams individually;
• said acoustooptic element including a plurality of transducers, each transducer being simultaneously actuated with another of said plurality of transducers in accordance with said scale clock signals generated by said scale clock generator;
• and
• means for delaying modulating timing for each of said plurality of drawing beams so that modulations for each of said drawing beams at a same position in said main scanning direction are completed synchronously with a corresponding scale clock signal of a series of said scale clock signals generated by said scale clock generator.

An optical image forming device comprising:

• scanning means comprising a scanning lens for scanning, in a main scanning direction, a plurality of drawing beams on an image plane and a monitoring beam in a predetermined scanning range;
• said plurality of drawing beams being scanned such that drawing beams adjacent to each other in a sub-scanning direction pass a predetermined position in the scanning range on said image plane at a different time, said sub-scanning direction being transverse to said main scanning direction, said monitoring beam being scanned prior to scanning said drawing beams;
• a scale clock generator that generates scale clock signals based on said monitoring beam which passed through said scanning lens for identifying positions of said monitoring beam in said scanning range;
• an acoustooptic device through which said plurality of drawing beams pass, said acoustooptic device modulating each of said drawing beams individually;
• a plurality of memory devices for storing drawing data of each of said plurality of drawing beams;
• and
• a plurality of delay devices for controlling a timing for reading said drawing data from said plurality of memory devices in accordance with said scale clock signals obtained by said scale clock generator so that modulations for each of said drawing beams at a same position in said main scanning direction are completed synchronously with a corresponding scale clock signal of a series of said scale signals generated by said scale clock generator.