Method for applying respective colour toner images on light responsive medium - enabling distance or gap between e.g. photosensitive drum and development roller of respective development to be selectively determined

摘要

A specified voltage is applied between the light responsive drum (1) and the developer roller (2d) of at least one of several developing units. A range for this current flowing between the drum and the roller is determined, between a value which represents an initial contact position (P), in which merely the tips of the magnetic brush (4c) are in contact with the light responsive drum (1) and a predetermined value. The latter value represents a position, in which the magnetic brush (4c) is in complete contact with the drum (1), whilst the degree of contact of the magnetic brush with the drum is altered. A selection is then made of gap (G) between the drum and the developer roller, such that the current (Id) lies in the determined range. ADVANTAGE - Maintains uniform and improved quality of multi-colour image. Degree of contact between light responsive drum and magnetic brush is exactly determined and gap between drum and developer roller is selected according to determined degree of contact.