Image forming apparatus for maintaining a constant beam scanning state

An image forming apparatus comprising:

• a first light beam generator configured to generate first light beams;
• a second light beam generator configured to generate second light beams;
• a scanner configured to reflect the first and second light beams generated by the first and second light beam generators, respectively, toward a scanned surface and to scan the first and second light beams on the scanned surface;
• a first light beam detector configured to detect the first or second light beams which are scanned on the scanned surface by the scanner;
• a first image forming area definer configured to define image forming starting and finishing points in accordance with an output of the first light beam detector, so as to define a first image forming area of the first light beams;
• a second light beam detector provided at a later stage of the first light beam detector along a scanning direction, and configured to detect the first and second light beams which are scanned on the scanned surface within the image forming area defined by the first image forming area definer;
• a second image forming area definer configured to define image forming starting and finishing points in accordance with an output of the second light beam detector, so as to define a second image forming area of the second light beams;
• a third light beam detector provided at a later stage of the first and second light beam detectors along the scanning direction, and configured to detect the first and second light beams which are scanned on the scanned surface within the first and second image forming areas;
• and
• a controller configured to detect information of a first relationship between the first image forming area defined by the first image forming area definer and the second and third light beam detectors in accordance with a first set value for the first image forming area definer and responses of the second and third light beam detectors, and a second relationship between the second image forming area defined by the second image forming area definer and the second and third light beam detectors in accordance with a set value for the second image forming area definer and the responses of the second and third light beam detectors, so as to determine image forming areas of the first and second light beams such that centers of the first and second image forming areas of the first and second light beams coincide with each other when images are formed in accordance with the information of the first and second relationships.

An image forming apparatus comprising:

• a light beam generator configured to generate light beams;
• a scanner configured to reflect the light beams generated by the light beam generator toward a scanned surface and to scan the light beams on the scanned surface;
• a first light beam detector configured to detect the light beams which are scanned on the scanned surface by the scanner;
• a clock generator configured to generate a clock signal having a variable cycle synchronized with an output of the first light beam detector;
• an image forming area definer configured to define an image forming area by setting image forming starting and finishing points along a scanning direction of the light beam in accordance with the clock signal generated by the clock generator;
• a second light beam detector provided at a later stage of the first light beam detector in a scanning direction, and configured to detect the light beams which are scanned on the scanned surface within the image forming area defined by the image forming area definer;
• a third light beam detector provided at a later stage of the first and second light beam detectors in the scanning direction, and configured to detect the first and second light beams which are scanned on the scanned surface within the image forming area defined by the image forming area definer;
• and
• a controller configured to control the variable cycle of the clock signal generated by the clock generator such that the image forming area in the scanned surface has a predetermined area in accordance with a relationship between a set value for the image forming area definer and outputs of the second and third light beam detectors.

An image forming apparatus comprising:

• a light beam generator configured to generate light beams;
• a scanner configured to reflect the light beams generated by the light beam generator toward a scanned surface and to scan the light beams on the scanned surface;
• a first light beam detector configured to detect the light beams scanned on the scanned surface by the scanner;
• a plurality of clock generators configured to respectively generate a plurality of clock signals each having different cycles synchronized with outputs of the first light beam detector;
• a clock selector configured to select any one of the plurality of clock signals generated by the plurality of clock generators;
• an image forming area definer configured to define an image forming area by setting image forming starting an finishing points along a scanning direction of the light beam in accordance with the clock signal selected by the clock selector;
• a second light beam detector provided at a later stage of the first light beam detector in a scanning direction, and configured to detect the light beams which are scanned on the scanned surface within the image forming area defined by the image forming area definer;
• a third light beam detector provided at a later stage of the first and second light beam detectors in the scanning direction, and configured to detect the first and second light beams which are scanned on the scanned surface within the image forming area defined by the image forming area definer;
• and
• a controller configured to control the clock selector such that the image forming area in the scanned surface has a predetermined area in accordance with a relationship between a set value for the image forming area definer and outputs of the second and third light beam detectors.

An image forming apparatus comprising:

• a first light beam scanner configured to form a first image;
• a second light beam scanner configured to form a second image;
• a first scanning state detector configured to detect a first light beam scanning state scanned by the first light beam scanner;
• a second scanning state detector configured to detect a second light beam scanning state scanned by the second light beam scanner;
• an image positional relation detector configured to detect a positional relationship between the first image and the second image;
• a first scanning state changer configured to change the first light beam scanning state scanned by the first light beam scanner;
• a second scanning state changer configured to change the second light beam scanning state scanned by the second light beam scanner;
• a first controller configured to control the first and second scanning state changers such that the positional relationship between the first and second images becomes a predetermined relationship;
• a memory configured to store the first light beam scanning state and the second light beam scanning state when the positional relationship between the first and second images becomes the predetermined relationship;
• and
• a second controller configured to control the first scanning state changer and the second scanning state changer to coincide with the first light beam scanning state and the second light beam scanning state stored in the memory.