US 2004/0057751 A1Published application

Image forming apparatus

AssigneeSeiko Epson Corporation

InventorsYasuhiro Matsuo, Satoru Miyamoto, Minoru Kishigami

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Abstract

In an image forming apparatus of the present invention, during the image forming operation, the completion of development by one of development cartridges is followed by the rotation of a rotary for setting the next development cartridge to a development position. The rotational speed v of the rotary for this is increased linearly to the maximum speed vmax and, after that, is decreased linearly to stop the rotary when the next development cartridge reaches the development position. During the replacement of the development cartridge in the non-image forming operation, the rotary is rotated to set the development cartridge to be replaced to the replacement position. The rotational speed of the rotary for this is set to be a constant speed v1 in a region other than a contact region where an input gear of the development side is in contact with a driving gear of the fixed side and a speed lower than the speed v1 in the contact region (the minimum speed v2). Therefore, the impact during collision between the input gear of the development unit and the development unit driving gear according to the rotation of the rotary in the non-image forming operation can be effectively reduced and the time required for rotation of the rotary in the non-image forming operation can be shortened.

Claims14

Dependent claims

An image forming apparatus comprising at least:

a rotary, a rotary driving motor for rotating the rotary, a plurality of development units each of which is mounted to said rotary such that the development unit is replaceable at a replacement position and has a development roller for carrying developer and an input gear, a development unit driving motor for driving said development roller, a development unit driving gear which is disposed outside said rotary such that the development unit driving gear can be selectively meshed with one of said input gears and to which the driving force of said development unit driving motor is transmitted, and a control device for controlling the drive of said rotary driving motor and said development unit driving motor, wherein
during the image forming operation, said development rollers of the respective development units are set at the development position relative to a photoreceptor by turns according to the rotation of said rotary and, at the development position, said input gears of the respective development units are meshed with said development unit driving gear so as to drive said development rollers with the driving force of said development unit driving motor by turns, thereby achieving multi-color development,
said image forming apparatus being characterized by further comprising a rotary driving motor control means which controls said rotary driving motor for the rotation of said rotary during the non-image forming operation such that the rotational speed of said rotary in a contact region where said input gear collides with said development unit driving gear is lower than the rotational speed of said rotary in a region other than said contact region.

An image forming apparatus comprising a developing device of a rotary development type having a rotary on which a plurality of development units are mounted, and a locking means for positioning said rotary in order to selectively set said development units at a predetermined position and for locking the rotary at the predetermined position, wherein

said locking means comprises a lockable position formed on said rotary side, a locking member which is movably disposed on the body of the image forming apparatus and has a locking position where the locking member is engaged with said lockable position to lock said rotary and an evacuation position where the locking member is not engaged with said lockable position, a shifting means for shifting said locking member to said evacuation position, and a biasing means for biasing said locking member to said locking position,
said image forming apparatus being characterized in that said locking member has a contact portion which can come in contact with said lockable position before the engagement with said lockable position according to the rotation of said rotary.

Dependencies are inferred from the claim text.