Optical printer and driving method therefor

An optical printer for printing a grayscale image on a photosensitive recording medium based on image data, the optical printer comprising:

• a printing head having a plurality of light emitting elements arranged in a main scan direction, for projecting light beams toward the photosensitive recording medium;
• a driving device for driving the light emitting elements while determining time lengths of driving the individual light emitting elements per each pixel in accordance with tonal levels of pixels to print that are represented by the image data;
• a control device for changing luminance of the light emitting elements according a predetermined characteristic curve as the determined driving time for each pixel elapses;
• and
• a scanning device for shifting the printing head relative to the photosensitive recording medium in a sub scan direction perpendicular to the main scan direction after each line of the image is recorded on the photosensitive recording medium.