Ricoh Company, Ltd.

Hitachi Koki Co., Ltd.

Hiroshi Inenaga

Junshin Sakamoto

According to an aspect of the present invention, there is provided a laser diode array including: a laser array chip including: a substrate; and at least three of laser diodes that are formed on the substrate; first electrodes that are formed on each of the laser diodes so as to be isolated from one another; a sub-mount; and second electrodes that are formed on the sub-mount so as to correspond to the first electrodes and so as to be isolated from one another, wherein the laser array chip is mounted on the sub-mount through the first electrodes and the second electrodes, and wherein, among contacting surfaces between each of the first electrodes and a corresponding one of the second electrodes, a contacting area of a central one of the contacting surfaces is larger than that of an end one of the contacting surfaces.

Laser diode array, optical scanning device and printing apparatus

A semiconductor laser device including an edge-emitting type laser chip having at least three emitting points in one light emitting edge, a sub-mount mounted with the laser chip, and a heat sink bonded to the sub-mount through a solder layer. When R designates a linear expansion coefficient ratio of the heat sink to the sub-mount and D 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:&#x2266;5.48&#xd7;A difference between stress acting on one laser element and another in the laser chip due to shrinkage of the heat sink when melted solder is cooled down is reduced so that a difference in light output characteristics between one light emitting point and another can be reduced.

Semiconductor laser device, light scanner, and image forming apparatus

An annular groove is formed on the upper surface, or a surface C, of a rotor member. A surface D and a surface E of a rotor member, which are located closer to the center than the annular groove when radially viewed, are machined for correcting a dynamic unbalance of the rotor member. Therefore, a nonuniform deformation of the rotor member, which results from a centrifugal load and heat, which are due to the rotation of the rotor member, reaches the inside-diameter defining wall of the annular groove, but does not reach the outside-diameter defining wall of the annular groove since it is blocked by the annular groove.

Growing community of inventors

Ibaraki, Japan

Hiroshi Inenaga