Abstract: A method and apparatus for image forming includes a hybrid developing apparatus that supplies surly charged toner to a developing roll. The apparatus includes a developing roll that is electrically conductive at least on its surface. The image forming apparatus and the method have a constitution capable of applying an alternating current bias having a duty ratio in the range of 10 to 50% and a direct current bias superposed thereon. The developing roll is directly confronted with a latent image bearing body through an insulative toner thin layer at the nearest region of the developing roll and the latent image bearing body. An independent bias is applied to each of the developing roll and the magnetic roll, and the toner is refreshed by the varying duty ratio of the alternate current bias and the direct current bias after developing.

Abstract: The retainer of the present invention is made of a composite material having a body made from a polymer, a layer of solid lubricant formed over the body by chemically coating the body with a porous layer of solid lubricant and impregnating the solid lubricant with another lubricant using conventional methods such as vacuum impregnation. The retainer is placed between an outer raceway and an inner raceway to form a self-lubricating bearing. The bearing made in this manner has high lubrication tolerance (i.e. it performs well in the absence of external lubrication). Because of its high lubrication tolerance, the bearing is suitable for use in various applications such as dental/medical hand pieces that are periodically sterilized and other applications which occasionally experience periods of lubrication starvation.