Light beam scanning apparatus with controller for varying spacing between a plurality of scanning beams

A laser printer for printing information at a desired pixel density selected from among a plurality of densities, comprising:

• a plurality of lasers generated a plurality of laser beams respectively;
• a prism synthesizing said laser beams in the same direction and with slightly deviated positions from each other;
• a deflector deflecting said laser beams for scanning;
• a photoconductive element mounted to be scanned parallely on the surface thereof by said laser beams;
• a detector detecting deviation from a set position of said plural laser beams on said surface by detecting at least part of said laser beams;
• adjusters adjusting the position of said laser beams with respect to each other on said surface in accordance with said detected deviation;
• and
• a controller controlling at least one of said adjusters so that different positions of said laser beams on said surface are selectively set in accordance with the desired printing pixel density of the information to provide the set position for said detector.

A laser printer for printing information at a desired pixel density selected from among a plurality of densities, comprising:

• a source generating a plurality of laser beams;
• a deflector deflecting said laser beams for scanning;
• a photoconductive device mounted to be scanned parallely on the surface thereof by said laser beams;
• position detectors having photodetecting regions and detecting deviation from a set position of said plural beams on said surface by at least part of said laser beams;
• adjusters adjusting the positions of said laser beams on said surface in accordance with the deviation detected by said position detector;
• and
• a controller controlling at least one of said position detectors to selectively provide the set position by selectively changing the photodetecting regions of said position detectors so that the positions of said laser beams on said surface are correspondingly changed in accordance with the desired pixel density of the information.

A laser printer for printing information at a desired pixel density selected from among a plurality of densities, comprising:

• a source for generating a plurality of laser beams;
• a deflector deflecting said laser beams for scanning;
• a photoconductive device mounted to be scanned parallely on the surface thereof by said laser beam;
• a position detector having a plurality of light detecting segments mounted with respect to each other so as to receive respective portions of said laser beams and detecting deviation of said laser beams from a set position between the segments;
• means for maintaining said laser beams at the set position in accordance with the detected deviation by a feedback control so that the relative positions of said laser beams with respect to each other are held at the set position;
• and
• a controller electrically connected to said position detector, and said source, and said controller selectively changing the segments of said position detector to selectively change the set position at a value corresponding to the desired pixel density from among a plurality of values corresponding to different pixel densities so that said means for maintaining will maintain the laser beam relative positions at the set position corresponding to the selected desired pixel densities.

A laser printer for printing information at a desired pixel density selected from among a plurality of densities, comprising:

• means, including a prism, synthesizing two laser beams to travel along a path in the same direction and with slightly deviating positions from each other;
• a deflector deflecting said laser beams for scanning;
• a photoconductive device mounted to be scanned parallely on the surface thereof by said laser beams;
• a position detector having a plurality of photoconductive segments combined and mounted to receive at least a portion of said two laser beams and detecting a deviation of the position of said laser beams from a set position on the surface on the basis of a relationship between the segments;
• adjusters adjusting the path of said laser beams in accordance with the detected deviation;
• and
• a controller electrically connected to said position detector, said means for synthesizing lasers and said deflector, said controller changing the relationship of the segments of said position detector to selectively change the set position from among a plurality of different set positions and selectively providing a modulating frequency from among a plurality of different modulating frequencies to said means for synthesizing laser beams and selecting a scanning speed of said deflector from among a plurality of different scanning speeds, with each of said selecting being in accordance with the desired pixel density from among a plurality of different pixel densities.

A recorder for recording information at a desired pixel density selected from among a plurality of densities, comprising:

• means synthesizing at least two laser beams to travel along a path in the same direction and with slightly deviating positions from each other;
• means scanning said laser beams;
• a position detector mounted to receive at least a portion of said laser beams and detecting a deviation of the position of at least said portion from a set position;
• adjusters adjusting the path relative position of said laser beams in accordance with the detected deviation;
• and
• a controller to selectively change the set position from among a plurality of different set positions selectively providing a modulating frequency from among a plurality of different modulating frequencies to said means for synthesizing laser beams and selecting a scanning speed of said deflector from among a plurality of different scanning speeds, with each of said selecting being in accordance with the desired pixel density from among a plurality of different pixel densities.