Abstract: In an image forming apparatus, the charging bias supply circuit generates a second charging bias voltage that causes no positive discharge between the charging unit and the photoreceptor drum, during a recovery mode, the charging unit charges the surface of the photoreceptor drum upon application of the second charging bias voltage during the recovery mode, and the cleaning unit rubs the surface of the photoreceptor drum charged by the second charging bias voltage, during the recovery mode.

Abstract: In case new and old toners may be mixed, a developing bias is set as follows. The time is first clocked. The number of times toner is replenished from a hopper into a buffer for a clocked period is counted. If a replenishment amount per clock time is a threshold value or higher, considering that new and old toners are mixed, the setting of the developing bias is changed. An electric field intensity between a developing roller and a photoconductor is set to cause normally-charged toner to fly in an image area but not to fly in a background area. No image fogging is therefore generated in the background area. Thus, an image forming apparatus and method capable of preventing low-charged toner and oppositely-charged toner generated by mixing of new and old toners from adhering to the background area of an electrostatic latent image on the photoconductor, thereby avoiding generation of image fogging.

Abstract: In case new and old toners may be mixed, a developing bias is set as follows. The time is first clocked. The number of times toner is replenished from a hopper into a buffer for a clocked period is counted. If a replenishment amount per clock time is a threshold value or higher, considering that new and old toners are mixed, the setting of the developing bias is changed. An electric field intensity between a developing roller and a photoconductor is set to cause normally-charged toner to fly in an image area but not to fly in a background area. No image fogging is therefore generated in the background area. Thus, an image forming apparatus and method capable of preventing low-charged toner and oppositely-charged toner generated by mixing of new and old toners from adhering to the background area of an electrostatic latent image on the photoconductor, thereby avoiding generation of image fogging.

Abstract: A color printer including, a conductive brush roller to contact a photosensitive drum at a position downstream of a transferring apparatus and upstream of a charging apparatus, wherein at least part of residual toner is collected after temporarily transferring on the photosensitive drum, and the collected toner is expelled onto the photosensitive drum, a charge electrode facing the brush roller at a position other than the contact position of the photosensitive drum and the brush roller, and a power source to apply voltage to the charge electrode, wherein the polarity of the voltage applied from the power source to the charge electrode with respect to the average voltage of the surface of the photosensitive drum after transferring is the same as a charging polarity of the toner at developing.

Abstract: An image forming apparatus comprises: an image carrier driven into rotation; a charger for electrically charging a surface of the image carrier; a latent image forming unit for forming an electrostatic latent image on the charged image carrier surface; a developing unit for forming a toner image by supplying a toner to an area of the electrostatic latent image formed on the image carrier surface; a transferring unit for transferring the toner image formed on the image carrier surface to a transfer medium; and a non-rotary type polishing member employing a foamed elastic material, the polishing member contacted against the surface of the image carrier at place downstream from the transferring unit in a moving direction of the image carrier and between the transferring unit and the charger, and reciprocally moved in a direction intersecting with the moving direction of the image carrier.

Abstract: It is intended to provide an image forming apparatus capable of conducting charge adjustment of post-transfer residual toner appropriately by securing a contact area of a temporarily-collecting member and an electrode, without applying excessive deformation load to the temporarily-collecting member. There are arranged a brush roller for temporarily collecting post-transfer residual toner, and an electrode of which inwardly-curved face being in contact with the brush roller in a toner charge apparatus. Thereby, charged-in-opposite-polarity toner, out of post-transfer residual toner, is collected by the brush roller, polarity of the toner is reversed to original polarity, and then, returned to a photosensitive drum. The inner face of the electrode, i.e., a contact face of the electrode and the brush roller is formed in an inwardly-curved face. Thereby, a large contact area and light pushing force of the electrode to the brush roller can go together.

Abstract: It is intended to provide an image forming apparatus capable of conducting charge adjustment of post-transfer residual toner appropriately by securing a contact area of a temporarily-collecting member and an electrode, without applying excessive deformation load to the temporarily-collecting member. There are arranged a brush roller for temporarily collecting post-transfer residual toner, and an electrode of which inwardly-curved face being in contact with the brush roller in a toner charge apparatus. Thereby, charged-in-opposite-polarity toner, out of post-transfer residual toner, is collected by the brush roller, polarity of the toner is reversed to original polarity, and then, returned to a photosensitive drum. The inner face of the electrode, i.e., a contact face of the electrode and the brush roller is formed in an inwardly-curved face. Thereby, a large contact area and light pushing force of the electrode to the brush roller can go together.

Abstract: The color printer of the invention comprises a conductive brush roller contacting with a photosensitive drum at a position downstream of a transferring apparatus and upstream of a charging apparatus, collecting at least part of residual toner after transferring on the photosensitive drum temporarily, and expelling the collected toner onto the photosensitive drum, a charge electrode facing the brush roller at a position other than the contact position of the photosensitive drum and brush roller, and a power source for applying voltage to the charge electrode. The polarity of the voltage applied from the power source to the charge electrode with respect to the average voltage of the surface of the photosensitive drum after transferring is the same as a charging polarity of the toner at developing.