| 摘要 |
PURPOSE:To improve durability and stability against environmental conditions by arranging an electrostatic image bearing body and a developer carrying body at a prescribed distance, allowing said carrying body to carry an insulating magnetic developer layer contg. a specified fine silica powder thinner than said distance, and transferring the developer to said image bearing layer to develop the image. CONSTITUTION:An electrostatic image bearing body 1 for bearing an electrostatic image on the surface, and a nonmagnetic cylinder 2 as a developer carrying body for carrying an insulating magnetic developer 6 are arranged in a prescribed distance in a developing section. A multipolar permanent magnet 3 is built in the inside of the cylinder 2, and a doctor blade 5 is arranged above the surface of the cylinder 2 to spread the developer layer uniformly and thinner than said distance on the cylinder 2, and the developer is transferred to the body 1 to develop the electrostatic image in the developing section. A fine silica powder treated with an ethylenically unsatd. amino compd. is added to the developer as an electrostatic change control component to uniformize triboelectrification against fluctuation of temp. and humidity, and to contribute to formation of a stable developer layer. As a result, the obtained image is sharp and free from deterioration of density and fog and further, good in halftone reproducibilty. |
