Laser beam luminous energy correction method, laser driving apparatus, laser beam scanner and image recording device

摘要

The object of the present invention is to precisely correct the luminous energy of a laser beam on a scanned surface which varies according to scanning and varies according to an angle of incidence with the scanned surface when a laser beam emitted from a semiconductor laser for emitting a laser beam having luminous energy according to supply current is scanned on the scanned surface via a scanning optical system.To achieve the above object, only modulation current when supply current supplied to a semiconductor laser is divided into threshold current having a current value in the vicinity in the spontaneous emission area of an extrapolated point which is an intersection with an axis when a linear part corresponding to a laser emission area in the supply current-to-output luminous energy characteristic of the semiconductor laser is extrapolated up to the axis showing that luminous energy is zero and modulation current which is a residual current component acquired by subtracting threshold current from supply current is regulated based upon a gain control value acquired by multiplying a gain set value which functions as the criterion of gain for converting image data to modulation current by a correction coefficient according to an angle of incidence.