Optical-writing control device, image forming apparatus, and method of controlling optical writing device

An image forming apparatus comprising an optical-writing control device that controls a plurality of light sources to form electrostatic latent images on a plurality of photosensitive elements, the light sources and the photosensitive elements being provided on a per-color basis of different colors, the optical-writing control device comprising:

• a light-emission control unit that controls each of the plurality of light sources based on information on pixels constituting an image to be formed, thereby exposing each of the plurality of photosensitive elements to light;
• a detection-signal acquiring unit that acquires a detection signal output from a sensor on a conveying path where developing-agent images obtained by developing the electrostatic latent images formed on the photosensitive elements using developing agents of the different colors are transferred and conveyed;
• and
• a correction-value calculating unit that calculates correction values for use in correcting a transfer position at which the developing-agent images are to be transferred onto a sheet, overlaying positions at which the developing-agent images of the different colors are to be overlaid on one another, and densities of the developing-agent images based on the detection signal output from the sensor upon detection of a correction pattern for use in correcting the transfer position, a correction pattern for use in correcting the overlaying positions, and a correction patter for use in correcting the densities, wherein
• the detection-signal acquiring unit determines a timing of detecting the pattern for use in correcting the overlaying positions and a timing of detecting the pattern for use in correcting the densities based on a correction value calculated based on the detection signal output upon detection of the pattern for use in correcting the transfer position, and
• the light-emission control unit controls light emission from each of the plurality of light sources so as to cause the pattern for use in correcting the overlaying positions to have a width, in a main-scanning direction, that depends on a width in the main-scanning direction of a detection area of the sensor, and controls light emission from each of the light sources so as to cause the pattern for use in correcting the transfer position to have a width, in the main-scanning direction, that is wider than the width in the main-scanning direction of the pattern for use in correcting the overlaying positions.

A method of controlling an optical-writing control device that controls a plurality of light sources to form electrostatic latent images on a plurality of photosensitive elements, the light sources and the photosensitive elements being provided on a per-color basis of different colors, the optical-writing control device including

• a light-emission control unit that controls each of the plurality of light sources based on information on pixels constituting an image to be formed, thereby exposing each of the plurality of photosensitive elements to light,
• a detection-signal acquiring unit that acquires a detection signal output from a sensor on a conveying path where developing-agent images obtained by developing the electrostatic latent images formed on the photosensitive elements using developing agents of the different colors are transferred and conveyed, and
• a correction-value calculating unit that calculates correction values for use in correcting a transfer position at which the developing-agent images are to be transferred onto the sheet, overlaying positions at which the developing-agent images of the different colors are to be overlaid on one another, and densities of the developing-agent images based on detection signals output from the sensor upon detection of a correction pattern for use in correcting the transfer position, a correction pattern for use in correcting the overlaying positions, and a correction patter for use in correcting the densities, the method comprising:
• controlling light emission from each of the plurality of light sources so as to cause the pattern for use in correcting the overlaying positions to have a width, in main-scanning direction, that depends on a width in the main-scanning direction of a detection area of the sensor;
• controlling light emission from each of the light sources so as to cause the pattern for use in correcting the transfer position to have a width, in the main-scanning direction, that is wider than the width in the main-scanning direction of the pattern for use in correcting the overlaying positions;
• and
• determining a timing of detecting the pattern for use in correcting the overlaying positions and a timing of detecting the pattern for use in correcting the densities based on a correction value calculated based on the detection signal output upon detection of the pattern for use in correcting the transfer position.