| US 7,532,227 B2 | ||
| Optical scanner and image forming apparatus | ||
| Tomohiro Nakajima, Tokyo (Japan); Akira Kojima, Chiba (Japan); Ikuko Yamashiro, Kanagawa (Japan); Seizo Suzuki, Kanagawa (Japan); Taku Amada, Kanagawa (Japan); Yoshinori Hayashi, Kanagawa (Japan); and Kazuyuki Shimada, Tokyo (Japan) | ||
| Assigned to Ricoh Company, Ltd., Tokyo (Japan) | ||
| Filed on Jul. 01, 2003, as Appl. No. 10/609,577. | ||
| Claims priority of application No. 2002-193652 (JP), filed on Jul. 02, 2002; application No. 2002-274073 (JP), filed on Sep. 19, 2002; application No. 2002-274075 (JP), filed on Sep. 19, 2002; and application No. 2002-276311 (JP), filed on Sep. 20, 2002. | ||
| Prior Publication US 2004/0036936 A1, Feb. 26, 2004 | ||
| Int. Cl. B41J 15/14 (2006.01); B41J 27/00 (2006.01) | ||
| U.S. Cl. 347—241 [347/256] | 14 Claims |
| 1. An optical scanner for scanning an image carrier comprising:
an illuminant part emitting an optical beam;
a deflecting part deflecting the optical beam;
an image forming part focusing the deflected optical beam on the image carrier; and
an optical axis adjustment part adjusting an optical axis of the optical beam with respect to a sub-scanning direction during
an image writing operation of image data,
the optical axis adjustment part comprising a prism for adjustment of a scanning position or a beam spot position of the optical
beam on the image carrier with respect to a sub-scanning direction during the writing of image data by rotating the prism
on an optical axis of the optical beam to deflect the incoming optical beam within a maximum deflection angle Φ, the maximum
deflection angle Φ being defined in a formula Φ=(n−1)×α in which n is a refractive index of the prism and α is an apex angle
of the prism, and the apex angle α of the prism satisfies:
0.1<β×tan[(n−1)×α]<1.0
in which β is a lateral magnification of all optical systems with respect to the sub-scanning direction, to compensate for
misalignment of the scanning position or beam spot position due to fluctuation in rotation of the image carrier.
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