Patent ID: 8682228

Claim:
A developer apparatus, comprising: a cylindrical two-component developer carrying body which carries a two-component developer comprising a toner composed of a magnetic toner containing magnetic powder, and a magnetic carrier; a cylindrical toner carrying body opposing the two-component developer carrying body, the cylindrical toner carrying body receiving the toner from the two-component developer carrying body and carrying the toner; an image carrying body for developing an electrostatic latent image by means of the toner carried on the toner carrying body, and a restricting mechanism that suppresses scattering of the magnetic toner from the toner carrying body and suppresses an increased thickness of a layer of the magnetic toner on the toner carrying body, wherein the restricting mechanism includes a first magnetic member provided inside the two-component developer carrying body at a position opposing a surface of the toner carrying body, the first magnetic member creating a retaining force to retain the magnetic toner on a circumferential surface of the cylindrical two-component developer carrying body, and a second magnetic member inside the toner carrying body at a position opposing the surface of the two-component developer carrying body and magnetized to a polarity opposite the first magnetic member, the second magnetic member creating a retaining force to the magnetic toner on a circumferential surface of the cylindrical toner carrying body, the first magnetic member is magnetized to generate a magnetic force on the surface of the two-component developer carrying body in a range of 80 mT to 100 mT in a direction perpendicular to the surface of the two-component developer carrying body, the second magnetic member generates a magnetic force at least on the surface of the toner carrying body in a range of 25 mT to 40 mT in the direction perpendicular to the surface of the toner carrying body, and the magnetic toner yields a saturated magnetization value in a range of 0.9 to 10 emu/g in a state where a magnetic field having a magnetic field intensity of 1 kOe is applied.