# US 2014/0153942 A1 · Image forming apparatus with endless belt and method for calculating meandering amount of belt > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 2014/0153942 A1 - Document ID: US20140153942A1 - Status: Published application - Kind: A1 - Application number: 14/090,612 - Filed: 2013-11-26 - Published: 2014-06-05 - Earliest claimed: 2012-11-30 - Assignees: Kyocera Document Soluitons Inc. - Applicants: Kyocera Document Solutions Inc. - Inventors: Yoshitaka Tokoro - Web page: https://patentgrep.com/patent/US20140153942A1 ## CPC - G03G 15/0189: {primary transfer to an intermediate transfer belt (G03G15/0184 takes precedence)} - G03G 15/1615: {relating to the driving mechanism for the intermediate support, e.g. gears, couplings, belt tensioning} - G03G: ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY ## Abstract An image forming apparatus includes a control unit which controls a correcting operation of correcting the meandering of an endless belt by a roller position adjusting mechanism. Prior to the correcting operation, the control unit causes a toner image for monitoring to be transferred to an area of a circumferential surface of the belt passing a detection area of a density sensor, causes the density sensor to perform a first detecting operation of detecting the toner image for monitoring, subsequently causes the density sensor to perform a second detecting operation of detecting the toner image for monitoring after the circumferential surface of the belt is moved by a predetermined distance, and calculates a meandering amount of the belt by comparing a first density value obtained by the first detecting operation and a second density value obtained by the second detecting operation. ## Claims ### Claim 1 An image forming apparatus, comprising: an endless belt which has a circumferential surface, to which a toner image is to be transferred, and is driven and rotated; an image forming unit which is arranged to face the belt and forms a toner image and transfers the toner image to the belt; a plurality of rollers which include a drive roller for driving and rotating the belt and a belt meandering correction roller for correcting meandering in a belt width direction perpendicular to a rotating direction of the belt and on which the belt is mounted; a roller position adjusting mechanism which corrects the meandering of the belt by adjusting the position of the belt meandering correction roller; a density sensor which has a detection area capable of detecting the density of the toner image and is fixedly arranged such that the detection area faces the circumferential surface of the belt; and a control unit which controls a correcting operation of correcting the meandering of the belt by the roller position adjusting mechanism; wherein, prior to the correcting operation, the control unit: controls the image forming unit while driving and rotating the belt, thereby transferring a toner image for monitoring at least to an area of the circumferential surface of the belt passing the detection area; causes the density sensor to perform a first detecting operation of detecting the toner image for monitoring; causes the density sensor to perform a second detecting operation of detecting the toner image for monitoring after the belt is driven and rotated to move the circumferential surface by a predetermined distance after the first detecting operation; and calculates a meandering amount of the belt by comparing a first density value obtained by the first detecting operation and a second density value obtained by the second detecting operation. ### Claim 2 (depends on 1) An image forming apparatus according to claim 1, wherein: the image forming unit forms a toner image for monitoring having a density gradient in the belt width direction as the toner image for monitoring. ### Claim 3 (depends on 1) An image forming apparatus according to claim 1, wherein: the image forming unit includes a first image forming unit and a second image forming unit tandemly arranged with respect to the belt; and the control unit: causes the first image forming unit to transfer a first toner image for monitoring to the circumferential surface of the belt; causes the first toner image for monitoring to be detected as the first detecting operation; and causes the first toner image for monitoring to be detected again as the second detecting operation after the belt is rotated at least one turn. ### Claim 4 (depends on 1) An image forming apparatus according to claim 1, wherein: the image forming unit includes a first image forming unit and a second image forming unit tandemly arranged with respect to the belt; and the control unit: causes the first image forming unit to transfer a first toner image for monitoring to the circumferential surface of the belt and causes the second image forming unit to transfer a second toner image for monitoring to the circumferential surface of the belt; causes the first toner image for monitoring to be detected as the first detecting operation; and causes the second toner image for monitoring to be detected as the second detecting operation after the belt is moved by a predetermined distance. ### Claim 5 (depends on 4) An image forming apparatus according to claim 4, wherein: the control unit performs the first and second detecting operations within one turn of the belt. ### Claim 6 (depends on 5) An image forming apparatus according to claim 5, wherein: the image forming unit includes four image forming units tandemly arranged with respect to the belt and configured to form toner images of mutually different colors; and the first image forming unit is the image forming unit arranged at one end out of the tandemly arranged four image forming units and the second image forming unit is the image forming unit arranged on the other end. ### Claim 7 (depends on 1) An image forming apparatus according to claim 1, wherein: the density sensor includes a first density sensor and a second density sensor arranged at a distance from each other in the belt width direction; the image forming unit forms a toner image for monitoring having a density variation in a main scanning direction extending along the belt width direction; and the control unit treats a differential density value between a density value detected by the first density sensor and a density value detected by the second density sensor as the first or second density value. ### Claim 8 (depends on 7) An image forming apparatus according to claim 7, wherein: the image forming unit forms the toner image for monitoring so that a width of the toner image for monitoring in a sub scanning direction perpendicular to the main scanning direction gradually changes; and the control unit calculates the meandering amount of the belt by further referring to timings of the first detecting operations and timings of the second detecting operations by the first and second density sensors. ### Claim 9 A method for calculating a meandering amount of an endless belt which has a circumferential surface, to which a toner image is to be transferred, and is driven and rotated, comprising: fixedly arranging a density sensor having a detection area capable of detecting the density of a toner image such that the detection area faces the circumferential surface of the belt; forming a toner image for monitoring in an area of the circumferential surface of the belt passing the detection area; detecting the toner image for monitoring as a first detecting operation by the density sensor; detecting the toner image for monitoring as a second detecting operation by the density sensor after the circumferential surface is moved by a predetermined distance by driving and rotating the belt after the first detecting operation; and calculating the meandering amount in a belt width direction perpendicular to a rotating direction of the belt by comparing a first density value obtained by the first detecting operation and a second density value obtained by the second detecting operation. ### Claim 10 (depends on 9) A method according to claim 9, wherein: a toner image for monitoring having a density variation in a main scanning direction extending along the belt width direction is formed as the toner image for monitoring. ### Claim 11 (depends on 10) A method according to claim 10, wherein: a toner image for monitoring having the density variation and having a width gradually changing in a sub scanning direction perpendicular to the main scanning direction is formed as the toner image for monitoring.