Developing apparatus using one-component toner

Abstract

To prevent scattering of toner when an image forming operation is started and ended in a developing process using one-component toner, a rotatable developing roller in contact with a photosensitive member carrying a static latent image, which is used to carry and feed one-component toner, is provided in a developing tank containing one-component toner. Initially, toner is fed to a feed roller, then passed through a toner restricting member which is pressed against the developing roller to restrict the amount of toner to be fed, so that a layer of toner is formed at a fixed thickness and fed into a developing area in contact with the photosensitive member. Thus a static latent image is produced on the developing roller. In this process, a developing bias voltage Va is supplied to the developing roller, a restricting voltage Vb is supplied to the toner restricting member so as to fix the thickness of the toner layer, and a supply voltage Vc is supplied to the feed roller to control the supply of toner. Specifically, the developing bias voltage Va, restricting voltage Vb, and supply voltage Vc are applied to their respective objects before the developing roller begins rotating, thereby minimizing or preventing the scattering or blowing out of toner. Additionally, supply of those voltages Va, Vo, and Vc are stopped after the developing roller stops, which also helps to prevent excess scattering of toner.