| 摘要 |
PROBLEM TO BE SOLVED: To provide an optical scanner which accurately controls an amount of light even a laser diode having nonlinear characteristics of driving current and an amount of light is used.SOLUTION: A relation between a driving current Iop and an optical output Po can be generated from a monitor value of a charge voltage Vcsh as I-L characteristics 72 because the charge voltage Vcsh is in a linear relation with the driving current Iop. The I-L characteristics 72 are polynomially approximated based on a table indicative of the relation between a monitor value of each Vcsh and an amount of light ratio (Po/Po_max) when three types of APCs are performed, and a mathematical expression is derived which provides a relation between an instruction voltage (charge voltage Vcsh) and an amount of light emission (Po/Po_max) of a vertical cavity surface-emitting laser (VCSEL). A CPU determines, based on the linear relation between the mathematical expression, and the charge voltage Vcsh and the driving current Iop, a driving current Iop (=Ib+Isw) to be applied so that the amount of light emission of the VCSEL is desirably obtained, where Isw is switching current and Ib is bias current. |
