| US 7,526,238 B2 | ||
| Developing device, process cartridge and image forming apparatus moving toner particles by a phase-shifting electric field | ||
| Masaaki Yamada, Tokyo (Japan); Masanori Horike, Yokohama (Japan); Yohichiroh Miyaguchi, Yokohama (Japan); Nobuaki Kondoh, Yokohama (Japan); and Yoshinori Nakagawa, Yokohama (Japan) | ||
| Assigned to Ricoh Company, Ltd., Tokyo (Japan) | ||
| Filed on Mar. 08, 2006, as Appl. No. 11/370,057. | ||
| Claims priority of application No. 2005-074172 (JP), filed on Mar. 16, 2005; and application No. 2005-214828 (JP), filed on Jul. 25, 2005. | ||
| Prior Publication US 2006/0216071 A1, Sep. 28, 2006 | ||
| Int. Cl. G03G 15/08 (2006.01) | ||
| U.S. Cl. 399—279 [399/283] | 16 Claims |
| 1. A development device developing a latent image on an image bearing member of an image forming apparatus, the development
device comprising:
an electrostatic conveyance device having an electrostatic conveyance surface and configured to move toner particles on the
electrostatic conveyance surface in a toner conveyance direction by a phase-shifting electric field, the electrostatic conveyance
surface having an upstream side end where the phase-shifting electric field starts and a downstream side end where the phase-shifting
electric field ends;
a supply device arranged to oppose the upstream side end of the electrostatic conveyance surface of the electrostatic conveyance
device to supply the toner particles onto the electrostatic conveyance surface of the electrostatic conveyance device, the
toner particles supplied by the supply device onto the electrostatic conveyance surface of the electrostatic conveyance device
being moved on the electrostatic conveyance surface by the phase-shifting electric field to a development area of the electrostatic
conveyance device opposing the image bearing member for development of the latent image on the latent image bearing member;
and
a collection device arranged to oppose the downstream side end of the electrostatic conveyance surface of the electrostatic
conveyance device and configured to collect the toner particles moved on the electrostatic conveyance surface to a downstream
side of the development area of the electrostatic conveyance device in the toner conveyance direction without contributing
to the development of the latent image in the development area,
wherein the toner particles collected by the collection device are returned to the supply device and wherein the electrostatic
conveyance device is circularly formed with the upstream side end and the downstream side end of the electrostatic conveyance
surface thereof separated from each other,
wherein the electrostatic conveyance device has a second electrostatic conveyance surface between the upstream side end and
the downstream side end of the electrostatic conveyance surface thereof and is configured to form the phase-shifting electric
field in the second electrostatic conveyance surface in a predetermined timing other than when an image is formed, and
wherein the collection device includes a conductive collection member, and a collection electric field is formed between the
collection member and the electrostatic conveyance surface of the electrostatic conveyance device and wherein the collection
member of the collection device is a conductive plate to which bias voltage of a polarity opposite to that of the toner particles
is applied.
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