Patent ID: 11932031
Assignee: CANON KABUSHIKI KAISHA
Field: Textile and paper machines (Mechanical engineering)
Classification: CPC B  G | IPC B  G

Claim 0:
1. An image forming apparatus comprising:
an image forming unit including a plurality of developing rollers that develop electrostatic images formed on a plurality of photoconductors, and configured to form an image developed by the plurality of developing rollers on a sheet;
a brushless motor of a sensorless type including a rotor formed of a permanent magnet and a stator provided with a plurality of coils corresponding to phases of the rotor, the brushless motor being a driving source of the plurality of developing rollers;
a drive circuit including a semiconductor device having a switching element and a gate driver, and configured to apply voltages to the plurality of coils for driving the motor, and to detect current values flowing through the plurality of coils to specify a rotational position of the rotor;
a plurality of clutches provided in drive transmission paths from the brushless motor to the plurality of developing rollers, and configured to switch transmitting and disconnecting a driving force from the brushless motor to each of the plurality of developing rollers; and
a control unit configured to control the drive circuit and the plurality of clutches,
wherein
the drive circuit is installed on a different substrate than a substrate of the brushless motor, and
the control unit is configured to control the drive circuit to start rotation of the brushless motor in a state where the driving force from the brushless motor to the plurality of developing rollers is disconnected by the plurality of clutches, and is configured to control the plurality of clutches in order to transmit the driving force from the brushless motor to each of the plurality of developing rollers, in order, after a rotation speed of the brushless motor has reached a predetermined speed.