Image forming apparatus including a controller configured to regulate a potential difference between a photoconductor and a developing member

摘要

An image forming apparatus includes a rotatable photoconductor, a charging unit, an exposure unit to expose the photoconductor to reduce an electrical potential at the photoconductor, a developing unit to charge the toner held on a toner bearing member with friction and attract the toner to the exposed portion on the photoconductor by supplying a development voltage from a first power source and using an electrical potential difference between the toner bearing member and the photoconductor in the development area, a reverse development voltage controller to supply a reverse development voltage while a non-charged portion on the photoconductor passes the development area, and a developer reducing potential applier to supply a development restraining potential and an absolute value smaller than a target charging potential to the photoconductor while the reverse development voltage is supplied.

主权项

1. An image forming apparatus for transferring an image to which toner is attracted onto a recording medium, the image forming apparatus comprising:
a rotatable photoconductor configured to carry an electrostatic latent image on an outer surface thereof; a charging unit, connected to a first power source, configured to charge the surface of the photoconductor to a target charging potential having the same polarity as the toner; an exposure unit configured to expose a portion of the charged surface of the photoconductor based on image data such that an electric potential at the exposed portion of the surface of the photoconductor is reduced; developing unit including a toner bearing member and a layer thickness regulator, the developing unit connected to a second power source configured to output a development voltage having the same polarity as that of the toner bearing member, the toner bearing member configured to carry the toner on a surface thereof for developing the latent image on the photoconductor with the toner to form a toner image, and the layer thickness regulator configured to regulate a thickness of layer of the toner carried on the surface of the toner bearing member, the developing unit configured to: charge the toner with friction by slidably contacting the surface of the toner bearing member and conveying the charged toner along with movement of the surface of the toner bearing member to a development area where the toner faces the latent image on the surface of the photoconductor, and attract the toner on the toner bearing member to the exposed portion on the surface of the photoconductor with the second power source using a difference in potential between the surface of the toner bearing member and the exposed portion of the surface of the photoconductor in the development area; and a controller configured to, cause the second power source to supply a reverse development voltage to the toner bearing member while a uncharged portion on the surface of the photoconductor passes the development area, the reverse development voltage having a polarity opposite a polarity of the development voltage, and cause the first power source to supply a development restraining voltage to the charging unit such that the charging unit produces a development restraining potential on the surface of the photoconductor that passes the development area while the reverse development voltage is supplied from the second power source to the toner bearing member, the development restraining voltage having a constant level while the reverse development voltage is supplied to the toner bearing member, a same polarity as the toner and an absolute value smaller than the target charging potential, the reverse development voltage being continuously constant from when the uncharged portion on the surface of the photoconductor passes the development area through when the development restraining voltage is supplied to the charging unit.