Laser beam scanner and photographic printer including a driver for driving a modulator using optical modulation data

A photographic printer including a laser beam scanner, a conveyor for conveying a photographic paper to a predetermined scanning plane of the laser beam scanner and a developer for developing a latent image exposed on the photographic paper by the laser beam scanner, wherein

• the laser beam scanner comprising:
• at least a set of laser light sources for emitting laser light beams,
• a laser driver provided with a laser light intensity sensor and adapted for driving at least one laser light source to emit a laser light beam within a first predetermined variation range under a feedback control using said laser light intensity sensor,
• a modulator for modulating intensity of a the laser light beam passing through said modulator,
• a modulator driver for driving said modulator by using a set of optical modulation data for the laser light beam, and
• a modulated beam sensor disposed on an optical path of the laser light beam downstream of said modulator for sensing the intensity of the laser light beam that has passed through said modulator and has been modulated by said modulator;
• said modulator driver including:
• a renewable first memory for memorizing the set of optical modulation data corresponding to respective stages of gradation of image data for laser light beam;
• a second memory for memorizing a set of standard intensity values corresponding to a plurality of predetermined stages of the gradation of the image data for laser light beam;
• a difference calculator for calculating difference values between actual intensities of the laser light beam sensed by said modulated beam sensor and the standard intensity values stored in said second memory;
• and
• a compensator for compensating the optical modulation data in accordance with the difference values calculated by said difference calculator to maintain the intensity of the laser light beam having passed through said modulator within a second predetermined variation range less than the first predetermined variation range at each stage of gradation.

A laser beam scanner comprising:

• a set of laser light sources for emitting laser light beams;
• a plurality of laser light intensity sensors, each of said laser light intensity sensors senses at least one intensity of the laser light beam emitted from at least one of said laser light sources;
• a plurality of laser drivers, each of said laser drivers drives at least one of said laser light sources to emit the laser light beam within a first predetermined variation range under a feedback control using at least one of said laser light intensity sensors;
• a plurality of modulators, each of said modulators modulates at least one of intensity of at least one of the laser light beams;
• a plurality of modulator drivers, each of said modulator drivers drives at least one of said modulators using a set of optical modulation data for each laser light beam;
• a plurality of modulated beam sensors, each of said modulated beam sensors senses at least one of intensity of at least one of the laser light beams modulated by each of said modulators;
• each of said modulator drivers includes:
• a renewable first memory for memorizing the set of optical modulation data corresponding to respective stages of gradation of image data for each laser light beam;
• a second memory for memorizing a set of standard intensity values corresponding to a plurality of predetermined stages of the gradation of the image data for each laser light beam;
• a difference calculator for calculating difference values between actual intensities of the laser light beam sensed by modulated beam sensor and the standard intensity values stored in said second memory;
• and
• a compensator for compensating the optical modulation data in accordance with the difference values calculated by said difference calculator to maintain the intensities of the laser light beams having passed through at least one of said modulators within a second predetermined variation range which is less than the first predetermined variation range at each stage of gradation.