Optical: systems and elements – Deflection using a moving element – Using a periodically moving element
Patent
1990-12-18
1992-08-04
Ben, Loha
Optical: systems and elements
Deflection using a moving element
Using a periodically moving element
359216, 359793, G02B 2610
Patent
active
051364182
ABSTRACT:
In an f.theta. lens system in an optical scanner, an approximately parallel light beam from a light source device is formed as a linear image extending in a main scan-corresponding direction and is deflected at an equal angular velocity by a rotary polygon mirror having a reflecting face in the vicinity of the position of the formed linear image. The deflected light beam is formed by an image forming lens system as an image in the shape of a spot on a scanned face to optically scan the scanned face at an approximately equal speed. The image forming lens system forms the light beam deflected by the rotary polygon mirror as an image on the scanned face. The f.theta. lens system has a function for setting a reflecting position of the rotary polygon mirror and the scanned face in an approximately conjugate relation in geometrical optics with respect to a cross scanning direction, and an f.theta. function with respect to a main scanning direction. The f.theta. lens system further has two groups of first and second lenses sequentially arranged from the rotary polygon mirror toward the scanned face. The lenses have first to fourth lens faces which are counted from the side of the rotary polygon mirror and respectively have shapes of a straight line, an arc, a straight line and an arc on the deflecting plane sequentially from the first lens face toward the fourth lens face.
REFERENCES:
patent: 4715699 (1987-12-01), Morimoto
patent: 4919502 (1990-04-01), Yamakawa
patent: 5009472 (1991-04-01), Morimoto
Ben Loha
Ricoh & Company, Ltd.
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