Image forming apparatus

摘要

An image forming apparatus drives and rotates at least one of a photosensitive drum and a transport roller with use of a stepping motor in a multi-phase excitation mode. The image forming apparatus includes: a constant-voltage control unit controlling the stepping motor by applying a constant voltage for each phase; a constant-current control unit controlling the stepping motor by regulating an amount of current for each phase by a chopping control; a measuring unit measuring a chopping count of each phase on a per-step basis; a chopping count determination unit determining whether the chopping count of each phase is less than or equal to a predetermined count; and a control switching unit causing the constant-voltage control unit to control the stepping motor when the chopping count determination unit determines affirmatively, and causing the constant-current control unit to control the stepping motor when the chopping count determination unit determines negatively.

主权项

1. An image forming apparatus for driving and rotating, with use of a stepping motor in a multi-phase excitation mode, at least one of a photosensitive drum on which an electrostatic latent image is to be formed and a transport roller that transports a recording sheet, the image forming apparatus comprising:
a constant-voltage control unit configured to control a drive of the stepping motor by applying a constant voltage for each phase according to a clock signal; a constant-current control unit configured to control the drive of the stepping motor by regulating an amount of current for each phase by a chopping control where supply of current is compared to a threshold current amount; a measuring unit configured to measure a chopping count of each phase on a per-step basis; a chopping count determination unit configured to determine whether the chopping count of each phase is less than or equal to a predetermined count; and a control switching unit configured to cause the constant-current control unit to control the drive of the stepping motor when the chopping count determination unit determines the chopping count of each phase is not less than or equal to the predetermined count, and to switch to the constant-voltage control unit to control the drive of the stepping motor when the chopping count determination unit determines the chopping count of each phase is less than or equal to the predetermined count.