Optical scanning apparatus

An optical scanning apparatus which scans an image surface of a photoconductive medium along a main scanning line by focusing a deflected light beam into a spot on the image surface, so that an electrostatic image is produced on the scanned image surface, comprising:

• a plurality of light source means for emitting first and second beams;
• first and second coupling lens means for respectively coupling the first and second beams emitted by the plurality of light source means;
• rotary deflector means, having pairs of mutually-opposite reflection surfaces, for deflecting the first beam, coupled by the first coupling lens means, in a first direction by one of the reflection surfaces, and for deflecting the second beam, coupled by the second coupling lens means, in a second direction opposite to the first direction, by another of the reflection surfaces;
• and
• first and second imaging means for scanning the image surface along a first half of the main scanning line by focusing and deflecting the first beam, deflected by the rotary deflector means, into a first spot on the image surface, and for scanning the image surface along a second half of the main scanning line by focusing and deflecting the second beam, deflected by the rotary deflector means, into a second spot on the image surface, such that the first and second halves form a substantially straight scanning line on the image surface when the rotary deflector means is rotated.

An optical scanning apparatus which scans an image surface of a photoconductive medium along a main scanning line by focusing and deflecting a light beam onto the image surface, so as to produce an electrostatic image on the image surface, comprising:

• a plurality of light sources which emit first and second beams;
• first and second coupling lens units which respectively couple the first and second beams emitted by the plurality of light sources;
• a rotary deflector, having pairs of mutually-opposite reflection surfaces, which deflects the first beam, coupled by the first coupling lens unit, in a first direction by one of the reflection surfaces, and deflects the second beam, coupled by the second coupling lens unit, in a second direction opposite to the first direction, by another of the reflection surfaces;
• first and second imaging units which scan the image surface along a first half of the main scanning line by focusing and deflecting the first beam, deflected by the rotary deflector, onto the image surface, and scan the image surface along a second half of the main scanning line by focusing and deflecting the second beam, deflected by the rotary deflector, onto the image surface, wherein the first imaging unit includes a first optical axis and a first sub-deflector, and the second imaging unit includes a second optical axis and a second sub-deflector;
• a beam sync detection unit which detects both a position of start of the first half of the main scanning line in a sub-scanning direction and a position of start of the second half of the main scanning line in the sub-scanning direction;
• and
• a beam-scan position control unit which controls a quantity of rotation of one of the first and second sub-deflectors with respect to the sub-scanning direction based on the detected positions output from the beam sync detection unit, such that the first and second halves form a substantially straight scanning line on the image surface when the rotary deflector is rotated.

An image forming system in which an electrostatically-charged image surface of a photoconductive medium is linearly scanned along a main scanning line by an optical scanning apparatus by focusing and deflecting a light beam onto the image surface, so as to produce an electrostatic image on the image surface, the optical scanning apparatus comprising:

• a plurality of light sources which emit first and second beams;
• first and second coupling lens units which respectively couple the first and second beams emitted by the plurality of light sources;
• a rotary deflector, having pairs of mutually-opposite reflection surfaces, which deflects the first beam, coupled by the first coupling lens unit, in a first direction by one of the reflection surfaces, and deflects the second beam, coupled by the second coupling lens unit, in a second direction opposite to the first direction, by another of the reflection surfaces;
• first and second imaging units which scan the image surface along a first half of the main scanning line by focusing and deflecting the first beam, deflected by the rotary deflector, onto the image surface, and scan the image surface along a second half of the main scanning line by focusing and deflecting the second beam, deflected by the rotary deflector, onto the image surface, wherein the first imaging unit includes a first optical axis and a first sub-deflector, and the second imaging unit includes a second optical axis and a second sub-deflector;
• a beam sync detection unit which detects both a position of start of the first half of the main scanning line in a sub-scanning direction and a position of start of the second half of the main scanning line in the sub-scanning direction;
• and
• a beam-scan position control unit which controls a quantity of rotation of one of the first and second sub-deflectors with respect to the sub-scanning direction based on the detected positions output from the beam sync detection unit, such that the first and second halves form a substantially straight scanning line on the image surface when the rotary deflector is rotated.

An optical scanning apparatus which scans an image surface of a photoconductive medium along a main scanning line by focusing and deflecting a light beam onto the image surface, so as to produce an electrostatic image on the image surface, comprising:

• a plurality of light source means for emitting first and second beams;
• first and second coupling lens means for respectively coupling the first and second beams emitted by the plurality of light sources;
• rotary deflector means, having pairs of mutually-opposite reflection surfaces, for deflecting the first beam, coupled by the first coupling lens means, in a first direction by one of the reflection surfaces, and for deflecting the second beam, coupled by the second coupling lens means, in a second direction opposite to the first direction, by another of the reflection surfaces;
• first and second imaging means for scanning the image surface along a first half of the main scanning line by focusing and deflecting the first beam, deflected by the rotary deflector means, onto the image surface, and for scanning the image surface along a second half of the main scanning line by focusing and deflecting the second beam, deflected by the rotary deflector means, onto the image surface, wherein the first imaging means includes a first optical axis and a first sub-deflector, and the second imaging means includes a second optical axis and a second sub-deflector;
• beam sync detection means for detecting both a position of start of the first half of the main scanning line in a sub-scanning direction and a position of start of the second half of the main scanning line in the sub-scanning direction;
• and
• beam-scan position control means for controlling a quantity of rotation of one of the first and second sub-deflectors with respect to the sub-scanning direction based on the detected positions output from the beam sync detection means, such that the first and second halves form a substantially straight scanning line on the image surface when the rotary deflector means is rotated.