Patent ID: 8294745
Filing Date: 2012-10-23
Classification: B41J

Abstract:
1. An optical writing device comprising: a light source that emits multiple laser beams; a separating unit that separates each of the multiple laser beams into a monitor beam for measuring a quantity of light and a scanning beam for scanning a photoreceptor to form an image of image data; a photoelectric conversion unit that measures a light quantity of the monitor beam and outputs a monitor voltage with respect to each of the multiple laser beams depending on the light quantity of the monitor beam; a storage unit that stores therein a plurality of predetermined initial correction values with respect to the multiple laser beams as initial values of correction values for correcting a set common current which is common to the multiple laser beams and used for emitting the laser beams from the light source; a calculating unit that updates the common current on the basis of the monitor voltages, and calculates reference currents for the respective laser beams by correcting the updated common current with the initial correction values; a control unit that calculates correction values by updating the initial correction values on the basis of the monitor voltages, obtains corrected currents by correcting the updated common current with the calculated correction values, and controls each light quantity of each of the laser beams on the basis of each of the corrected currents; and a determining unit that obtains ratios of the respective corrected currents to the reference currents, determines whether any of the ratios is larger than a predetermined threshold value, and determines that the light source is degraded if the ratios is larger than the threshold value.