| US 7,542,496 B2 | ||
| Semiconductor laser device, light scanner, and image forming apparatus | ||
| Hiroshi Inenaga, Hitachinaka (Japan); and Junshin Sakamoto, Hitachinaka (Japan) | ||
| Assigned to Ricoh Company, Ltd., Tokyo (Japan) | ||
| Filed on Nov. 09, 2007, as Appl. No. 11/937,690. | ||
| Claims priority of application No. 2006-305133 (JP), filed on Nov. 10, 2006; and application No. 2007-269038 (JP), filed on Oct. 16, 2007. | ||
| Prior Publication US 2008/0112729 A1, May 15, 2008 | ||
| Int. Cl. H01S 3/04 (2006.01); H01S 5/00 (2006.01) | ||
| U.S. Cl. 372—36 [372/50.12] | 6 Claims |
| 1. A semiconductor laser device comprising:
an edge-emitting type laser chip having at least three light emitting points in one light emitting edge;
a sub-mount mounted with the laser chip; and
a heat sink made of a highly thermal conductive material and bonded to the sub-mount through a solder laser; wherein:
when R designates a linear expansion coefficient ratio of the heat sink to the sub-mount [(linear expansion coefficient of
the heat sink)/(linear expansion coefficient of the sub-mount)], and D (mm) designates a distance between light emitting points
at opposite ends in the light emitting edge of the laser chip;
materials of the sub-mount and the heat sink and the distance D are set to satisfy the following relation:
D≤5.48×R−2.13.
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