# US 10,768,562 B2 · Image forming apparatus > Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt - Number: US 10,768,562 B2 - Document ID: US10768562B2 - Status: Granted - Kind: B2 - Application number: 16/534,426 - Filed: 2019-08-07 - Published: 2020-03-05 - Granted: 2020-09-08 - Earliest claimed: 2018-09-05 - Assignees: Konica Minolta, Inc. - Applicants: Konica Minolta, Inc. - Inventors: Katsuhide Sakai; Yasuhiro Koide; Toshiaki Tanaka; Akihiro Hayashi - Web page: https://patentgrep.com/patent/US10768562B2 ## CPC - G03G 15/50: {Machine control of apparatus for electrographic processes using a charge pattern, e.g. regulating differents parts of the machine, multimode copiers, microprocessor control (sequencing control G03G21/14)} - G03G 15/80: {Details relating to power supplies, circuits boards, electrical connections} - G03G 15/1615: {relating to the driving mechanism for the intermediate support, e.g. gears, couplings, belt tensioning} - G03G 15/2053: {Structural details of heat elements, e.g. structure of roller or belt, eddy current, induction heating} - G03G 15/5008: {Driving control for rotary photosensitive medium, e.g. speed control, stop position control} - G03G 15/55: {Self-diagnostics; Malfunction or lifetime display} - G03G 15/2025: {with special means for lubricating and/or cleaning the fixing unit, e.g. applying offset preventing fluid} - G03G: ELECTROGRAPHY; ELECTROPHOTOGRAPHY; MAGNETOGRAPHY ## Abstract An image forming apparatus forms an image on a sheet, and includes: a rotator used to form the image; a motor that drives the rotator rotationally; a current measurer that measures motor current flowing through a current-carrying path including a winding of the motor, at measurement timing that is timing after the motor starts up; a torque acquirer that acquires a torque value of the motor based on a measured value of the motor current; and a corrector that performs correction for cancellation of an amount of error based on one or both of a variation in characteristic corresponding to motor speed of the motor and a variation in characteristic corresponding to the motor current at the measurement timing, at the acquisition of the torque value by the torque acquirer. ## Claims ### Claim 1 An image forming apparatus that forms an image on a sheet, the image forming apparatus comprising: a rotator used to form the image; a motor that drives the rotator rotationally; a current measurer that measures motor current flowing through a current-carrying path including a winding of the motor, at measurement timing that is timing after the motor starts up; a torque acquirer that acquires a torque value of the motor based on a measured value of the motor current; and a corrector that performs correction for cancellation of an amount of error based on one or both of a variation in characteristic corresponding to motor speed of the motor and a variation in characteristic corresponding to the motor current at the measurement timing, at the acquisition of the torque value by the torque acquirer. ### Claim 2 (depends on 1) The image forming apparatus according to claim 1, wherein based on information indicating, as the amount of error, an amount of loss current corresponding to the motor current for each of a plurality of values of the motor speed, the corrector performs, as the correction, processing of correcting the measured value of the motor current such that the amount of error corresponding to the motor speed and the motor current at the measurement timing is canceled. ### Claim 3 (depends on 1) The image forming apparatus according to claim 1, wherein the corrector stores a first correction value corresponding to a difference between the motor speed and reference motor speed and a second correction value corresponding to a difference between the measured value of the motor current and a reference current value, and performs the correction with the first correction value corresponding to the motor speed and the second correction value corresponding to the measured value of the motor current at the measurement timing. ### Claim 4 (depends on 3) The image forming apparatus according to claim 3, wherein the first correction value is a value proportional to m power of the difference between the motor speed and the reference motor speed, the m being an integer of one or more, and the second correction value is a value proportional to n power of the difference between the measured value of the motor current and the reference current value, the n being an integer of one or more. ### Claim 5 (depends on 1) The image forming apparatus according to claim 1, further comprising: a motor controller that performs vector control of controlling rotation of the motor, wherein the current measurer measures, as the motor current, coil current flowing through the winding. ### Claim 6 (depends on 1) The image forming apparatus according to claim 1, further comprising: a motor controller that performs vector control of controlling rotation of the motor, wherein the current measurer measures, as the motor current, q-axis current that is a current component causing the motor to generate rotary torque in the vector control. ### Claim 7 (depends on 1) The image forming apparatus according to claim 1, further comprising: a life predictor that predicts a life of the rotator, based on the torque value acquired. ### Claim 8 (depends on 1) The image forming apparatus according to claim 1, wherein in a case where the rotator is a roller that conveys the sheet, the current measurer defines, when the motor speed during the conveyance is a first speed, timing at which first waiting time elapses after passage-through-roller timing at which the sheet has completely passed through the roller, as the measurement timing, and defines, when the motor speed during the conveyance is a second speed slower than the first speed, timing at which second waiting time longer than the first waiting time elapses after the passage-through-roller timing, as the measurement timing. ### Claim 9 (depends on 1) The image forming apparatus according to claim 1, wherein the corrector is switchable, in accordance with a load torque characteristic of the rotator, between first mode in which the correction for cancellation of the amount of error based on the variation in characteristic corresponding to the motor speed of the motor and the variation in characteristic corresponding to the motor current at the measurement timing is performed and second mode in which the correction for cancellation of the amount of error based on the variation in characteristic corresponding to the motor speed of the motor at the measurement timing is performed. ### Claim 10 (depends on 1) The image forming apparatus according to claim 1, further comprising: a pad-type fixer including a pad disposed securely, a barrel-shaped fixing belt that rotates around the pad, and a pressing roller as the rotator that rotates the fixing belt, wherein lubricant is interposed between the pad and the fixing belt, and the motor is a drive source that drives the pressing roller rotationally.