| 摘要 |
PURPOSE:To provide stable high-gradation and high-picture quality images at all times by modulating the pulse width of a semiconductor laser (LD) over all the exposing range. CONSTITUTION:When the fluctuating amount data of sensitivity from the sensitivity characteristic curve of a photosensitive material set in advance are inputted to an exposure control means 30, exposing amount data corresponding to a gradation step stored in a look-up table(LUT) are read out. Next, the fluctuating amount data are added or subtracted to and from these data, and obtained corrected exposing amount data are stored in the LUT again. The means 30 decides a corrected exposing amount corresponding to image signal data and modulates the pulse width at modulation circuits 32C, 32Y and 32M. Thus, the optical outputs of LD 12C, 12Y and 12M can be suppressed within the linear area of characteristics for the LD. Therefore, even for the LD having the non- linear area in a low optical output area, a wide dynamic range can be secured, and stable high-gradation and high-picture quality images can be obtained. |
