| US 7,502,579 B2 | ||
| Developing device using developer of particular properties suitable therefore | ||
| Hiroyuki Mabuchi, Hitachinaka (Japan); Masayoshi Nakayama, Hitachinaka (Japan); and Hirobumi Ooyoshi, Hitachinaka (Japan) | ||
| Assigned to Ricoh Company, Ltd., Tokyo (Japan) | ||
| Filed on Aug. 26, 2005, as Appl. No. 11/211,742. | ||
| Claims priority of application No. P2004-251590 (JP), filed on Aug. 31, 2004. | ||
| Prior Publication US 2006/0045575 A1, Mar. 02, 2006 | ||
| Int. Cl. G03G 15/09 (2006.01) | ||
| U.S. Cl. 399—267 [399/269; 399/274; 399/276] | 9 Claims |
| 1. An electrostatic recording device, comprising:
a substantially cylindrical recording member, having a rotational axis and arranged to be rotatable about the rotational axis,
having a peripheral surface on which an electrostatic latent image is formed and developer is deposited;
a charging unit for charging the recording member;
an exposing unit for irradiating light onto the charged recording member;
a developing device for supplying toner to the recording member to form a toner image thereon; and
a transferring unit for transferring the toner image onto a recording medium,
wherein the developing device comprises:
a developer-accommodating vessel for accommodating developer having a toner and a carrier as primary components;
a developer conveying member disposed in the developer accommodating vessel to convey the developer in a direction along the
rotational axis; and
a developing roller opposing at one side the recording member and at another side the developer conveying member and having
an axis, the developing roller comprising a cylindrical part having a peripheral surface and a plurality of magnets of differing
polarity, and a sleeve roller disposed on the peripheral surface of the cylindrical part and capable of rotating about the
axis for supplying the developer from the developer conveying member to the recording member,
wherein the carrier has an average particle size of not greater than 65 μm and a saturation magnetization of not less than
70 emu/g,
wherein the surface of the sleeve roller has a roughness of not less than 0.45 times the average particle size of the carrier,
wherein one of the magnets is disposed in opposition to the recording member in the cylindrical part, the one of the magnets
having a maximum magnetic-flux density of not less than 0.07 T and,
wherein a relationship 10*V(cm/s)*L(cm)*M(g/cm2)<W(g/s)<40*V(cm/s)*L(cm)*M(g/cm2) is met,
where W is a flow rate of developer conveyed along the rotational axis of the developer conveying member,
V is a circumferential velocity of the peripheral surface of the rotating recording member,
L is a width of developer on the developing roller with respect to an axial direction of the developing roller, and
M is an amount of toner on the recording member.
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