Image forming apparatus and image displacement correction method

An image forming apparatus comprising:

• a first optical head unit and a second optical head unit that form electrostatic latent images on at least one image carrier, the first optical head unit including a plurality of optical heads arranged in a main scanning direction to overlap each other in the main scanning direction, the second optical head unit including a plurality of optical heads arranged in the main scanning direction to overlap each other in the main scanning direction;
• a detector that is disposed to correspond to a region where the optical heads overlap each other and that detects a displacement amount of each of the optical heads;
• and
• a controller that performs registration by controlling light emission of the optical heads based on the detection by the detector, wherein, in the registration, the controller:
• with one of the plurality of optical heads in the first optical head unit as a reference, performs registration on the other optical heads in the first optical head unit based on the detection by the detector;
• with one of the plurality of optical heads in the second optical head unit as a reference, performs registration on the other optical heads in the second optical head unit based on the detection by the detector;
• and
• performs registration between the first optical head unit and the second optical head unit based on a displacement amount between one of the plurality of optical heads in the first optical head unit and one of the plurality of optical heads in the second optical head unit.

An image displacement correction method in an image forming apparatus including:

• a first optical head group and a second optical head group that form electrostatic latent images on at least one image carrier, the first optical head group including a plurality of first optical heads arranged in a sub-scanning direction, the second optical head group including a plurality of second optical heads arranged in the sub-scanning direction, the first optical head group and the second optical head group overlapping each other in a main scanning direction;
• a detector that is disposed to correspond to a region where the first optical head group and the second optical head group overlap each other and that detects displacement amounts between the first optical heads and the second optical heads;
• and
• a controller that performs registration by controlling light emission of the plurality of first optical heads and the plurality of second optical heads based on the detection by the detector,
• the image displacement correction method comprising:
• with one of the first optical heads in the first optical head group as a reference, performing registration on the other first optical heads in the first optical head group based on the detection by the detector;
• with one of the second optical heads in the second optical head group as a reference, performing registration on the other second optical heads in the second optical head group based on the detection by the detector;
• and
• performing registration between the first optical head group and the second optical head group based on a displacement amount between one of the first optical heads in the first optical head group and one of the second optical heads in the second optical head group.

An image displacement correction method in an image forming apparatus including:

• a belt supported movably in a traveling direction;
• a plurality of image forming units arranged in the traveling direction of the belt, each of the plurality of image forming units including:
• an image carrier;
• a head unit including a first optical head that forms an electrostatic latent image on the image carrier in a first region in the main scanning direction and a second optical head that forms an electrostatic latent image on the image carrier in a second region in the main scanning direction;
• and
• a developing unit that forms developer images corresponding to the electrostatic latent images;
• and
• a detector that detects transferred developer images that are developer images transferred on the belt from the plurality of image forming units,
• wherein the first optical heads in the plurality of image forming units constitute a first optical head group, and the second optical heads in the plurality of image forming units constitute a second optical head group,
• the image displacement correction method comprising:
• acquiring, based on the detection, one or more first displacement amounts between a position in the traveling direction of a first transferred developer image and positions in the traveling direction of one or more second transferred developer images, the first transferred developer image being a transferred developer image corresponding to an electrostatic latent image formed by a reference first optical head that is one of the plurality of first optical heads in the first optical head group, the second transferred developer images being transferred developer images corresponding to electrostatic latent images formed by one or more first optical heads other than the reference first optical head in the first optical head group;
• acquiring, based on the detection, one or more second displacement amounts between a position in the traveling direction of a third transferred developer image and positions in the traveling direction of one or more fourth transferred developer images, the third transferred developer image being a transferred developer image corresponding to an electrostatic latent image formed by a reference second optical head that is one of the plurality of second optical heads in the second optical head group, the fourth transferred developer images being transferred developer images corresponding to electrostatic latent images formed by one or more second optical heads other than the reference second optical head in the second optical head group;
• acquiring, based on the detection, a first joint displacement amount including a displacement amount in the traveling direction and a displacement amount in the main scanning direction between an end portion of a fifth transferred developer image and an end portion of a sixth transferred developer image, the fifth transferred developer image being a transferred developer image corresponding to an electrostatic latent image formed by one of the plurality of first optical heads in the first optical head group, the sixth transferred developer image being a transferred developer image corresponding to an electrostatic latent image formed by one of the plurality of second optical heads in the second optical head group;
• setting, based on the first displacement amounts, conditions for formation of the electrostatic latent images by the first optical head group so that the position in the traveling direction of the first transferred developer image and the positions in the traveling direction of the second transferred developer images approach each other;
• setting, based on the second displacement amounts, conditions for formation of the electrostatic latent images by the second optical head group so that the position in the traveling direction of the third transferred developer image and the positions in the traveling direction of the fourth transferred developer images approach each other;
• and
• setting, based on the first joint displacement amount, conditions for formation of the electrostatic latent images by the first optical head group and conditions for formation of the electrostatic latent images by the second optical head group so that the end portion of the fifth transferred developer image and the end portion of the sixth transferred developer image approach each other.

An image displacement correction method in an image forming apparatus including:

• a first optical head unit and a second optical head unit that form electrostatic latent images on at least one image carrier, the first optical head unit including a plurality of optical heads arranged in a main scanning direction to overlap each other in the main scanning direction, the second optical head unit including a plurality of optical heads arranged in the main scanning direction to overlap each other in the main scanning direction;
• a detector that is disposed to correspond to a region where the optical heads overlap each other and that detects a displacement amount of each of the optical heads;
• and
• a controller that performs registration by controlling light emission of the optical heads based on the detection by the detector,
• the image displacement correction method comprising:
• with one of the plurality of optical heads in the first optical head unit as a reference, performing registration on the other optical heads in the first optical head unit based on the detection by the detector;
• with one of the plurality of optical heads in the second optical head unit as a reference, performing registration on the other optical heads in the second optical head unit based on the detection by the detector;
• and
• performing registration between the first optical head unit and the second optical head unit based on a displacement amount between one of the plurality of optical heads in the first optical head unit and one of the plurality of optical heads in the second optical head unit.

An image displacement correction method in an image forming apparatus including:

• a belt supported movably in a traveling direction;
• a plurality of image forming units arranged in the traveling direction of the belt, each of the plurality of image forming units including:
• an image carrier;
• a head unit including a first optical head that forms an electrostatic latent image on the image carrier in a first region in the main scanning direction and a second optical head that forms an electrostatic latent image on the image carrier in a second region in the main scanning direction;
• and
• a developing unit that forms developer images corresponding to the electrostatic latent images;
• and
• a detector that detects transferred developer images that are developer images transferred on the belt from the plurality of image forming units,
• wherein the first optical heads in the plurality of image forming units constitute a first optical head group, and the second optical heads in the plurality of image forming units constitute a second optical head group,
• the image displacement correction method comprising:
• for each of the head units of the plurality of image forming units, based on the detection, acquiring a joint displacement amount including a displacement amount in the traveling direction and a displacement amount in the main scanning direction between an end portion of a first transferred developer image and an end portion of a second transferred developer image, the first transferred developer image being a transferred developer image corresponding to an electrostatic latent image formed by the first optical head, the second transferred developer image being a transferred developer image corresponding to an electrostatic latent image formed by the second optical head;
• for each of the head units of the plurality of image forming units, based on the joint displacement amount, setting conditions for formation of the electrostatic latent image by the first optical head and conditions for formation of the electrostatic latent image by the second optical head so that the end portion of the first transferred developer image and the end portion of the second transferred developer image approach each other;
• acquiring one or more displacement amounts between a position in the traveling direction of a third transferred developer image and positions in the traveling direction of one or more fourth transferred developer images or between a position in the traveling direction of a fifth transferred developer image and positions in the traveling direction of one or more sixth transferred developer images, the third transferred developer image being a transferred developer image corresponding to an electrostatic latent image formed by a reference first optical head that is one of the plurality of first optical heads in the first optical head group, the fourth transferred developer images being transferred developer images corresponding to electrostatic latent images formed by one or more first optical heads other than the reference first optical head in the first optical head group, the fifth transferred developer image being a transferred developer image corresponding to an electrostatic latent image formed by a reference second optical head that is one of the plurality of second optical heads in the second optical head group, the sixth transferred developer images being transferred developer images corresponding to electrostatic latent images formed by one or more second optical heads other than the reference second optical head in the second optical head group;
• and
• based on the acquired displacement amounts, performing a process of setting conditions for formation of the electrostatic latent images by the first optical head group so that the position in the traveling direction of the third transferred developer image and the positions in the traveling direction of the fourth transferred developer images approach each other, and a process of setting conditions for formation of the electrostatic latent images by the second optical head group so that the position in the traveling direction of the fifth transferred developer image and the positions in the traveling direction of the sixth transferred developer images approach each other.