Konica Corporation

Sachie Hosogoezawa

Kunio Shigeta

Satoshi Haneda

Hiroyuki Nomori

Masakazu Fukuchi

Masahiro Onodera

In an magnetic brush charging apparatus, a following relation is satisfied, .rho..ltoreq.M/H.ltoreq.1.6 .rho., wherein H is a minimum gap distance (cm) between a cylinder and an image carrying member, .rho. is a density (g/cm.sup.3) of magnetic particles and M is an amount (g/cm.sup.2) of magnetic particles existing in a nip region coming in contact with the image carrying member.

Magnetic brush type charging device

An image forming apparatus uses a contact-type charger to charge a photoreceptor. The D.C. current supplied to the charger is measured while the output value of the A.C. voltage is changed within a predetermined range, and the output value of the A.C. voltage is set in accordance with the measurement result.

Charging unit with variable AC voltage

An image forming apparatus such as an electrophotographic copier and an electrophotographic printer. The image forming apparatus includes: a photoreceptor for forming a toner image on its surface; a charger for charging the surface with a bias voltage, including a DC component and a AC component, through a magnetic brush member which is in contact with the surface; a driving unit for moving both of the surface of the photoreceptor and the magnetic brush member in synchronism; a laser unit for imagewisely exposing a predetermined image area of the surface, which is charged by the charger, so that a latent image is formed on the surface; and a discharge lamp for exposing the surface with light so that the surface is discharged. In such the image forming apparatus, the discharge lamp starts exposing the surface with the light and the bias voltage, with which the surface is charged, is set at substantially 0 volt before the driving starts moving the surface and the magnetic brush member; and the predetermined image area of the surface is charged with the bias voltage, including the DC component and the AC component, after the driving starts moving the surface and the magnetic brush member.

Growing community of inventors

Hachioji, Japan

Sachie Hosogoezawa