Abstract: A toner current measuring device able to measure a toner current. The toner current measuring device having provided therein a toner deposit capacitor c1 including an electrode 11 and an electrode 12 disposed in opposition, a reference capacitor c2 having a mechanism for adjusting a capacitance thereof; a power supply unit 4; and a measuring unit 10 for measuring, when a voltage is applied to both capacitors to cause a transfer, between the opposing electrodes, of charged toner deposited on the electrode 11, a difference between currents flowing in the toner deposit capacitor c1 and the reference capacitor c2, the difference being measured as a toner current generated as a result of the transfer of the charged toner.

Abstract: A developing device 2a, which is provided with: a developer tank 16 that houses a developer 24 containing a toner, a carrier for charging the toner and reverse polarity particles that are charged with a polarity reversed to the electrostatic charge polarity of the toner by the carrier; a developer-supporting member 11 that supports the developer supplied from the developer tank on the surface thereof, and transports the developer; and a separating mechanism 22 that separates the toner or the reverse polarity particles from the developer supported on the developer-supporting member, and the reverse polarity particles are collected into the developer tank, is provided, and an image-forming apparatus having such a developing device and an image-forming method applied thereto are also provided.

Abstract: A contact charger for charging a charging target (e.g., a photosensitive member) includes a charging brush to be in contact with the charging target, and auxiliary charging particles to be interposed between the brush and the charging target. The auxiliary charging particle takes an acicular form having an aspect ratio from 2 to 10000, and satisfies a relationship of (L2/T?200) between a length L (?m) of a long axis of the particle and a thickness of T (deniers) of a brush fiber of the brush.

Abstract: A toner current measuring device able to measure a toner current. The toner current measuring device having provided therein a toner deposit capacitor c1 including an electrode 11 and an electrode 12 disposed in opposition, a reference capacitor c2 having a mechanism for adjusting a capacitance thereof; a power supply unit 4; and a measuring unit 10 for measuring, when a voltage is applied to both capacitors to cause a transfer, between the opposing electrodes, of charged toner deposited on the electrode 11, a difference between currents flowing in the toner deposit capacitor c1 and the reference capacitor c2, the difference being measured as a toner current generated as a result of the transfer of the charged toner.

Abstract: A contact charger for charging a charging target (e.g., a photosensitive member) includes a brush to be in contact with the charging target, and auxiliary charging particles to be interposed between the brush and the charging target. Fibers of the brush have a volume resistivity from 1×101 ?·cm to 1×108 ?·cm, a primary particle diameter of the auxiliary charging particles is in a range from 0.01 ?m to 10 ?m, and a push-in amount of the brush with respect to the charging target is in a range from 0.1 mm to 2.0 mm. The brush moves relatively to the charging target for charging the charging target. An image forming apparatus includes a photosensitive member to be charged by the charger.

Abstract: A contact charger for charging a charging target (e.g., a photosensitive member) includes a charging brush to be in contact with the charging target, and auxiliary charging particles to be interposed between the brush and the charging target. The auxiliary charging particle takes an acicular form having an aspect ratio from 2 to 10000, and satisfies a relationship of (L2/T?200) between a length L (?m) of a long axis of the particle and a thickness of T (deniers) of a brush fiber of the brush.

Abstract: A contact charger for charging a charging target (e.g., a photosensitive member) includes a brush to be in contact with the charging target, and auxiliary charging particles to be interposed between the brush and the charging target. Fibers of the brush have a volume resistivity from 1×101 ?·cm to 1×108 ?·cm, a primary particle diameter of the auxiliary charging particles is in a range from 0.01 ?m to 10 ?m, and a push-in amount of the brush with respect to the charging target is in a range from 0.1 mm to 2.0 mm. The brush moves relatively to the charging target for charging the charging target. An image forming apparatus includes a photosensitive member to be charged by the charger.

Abstract: An image forming apparatus which reduces abrasion of a photosensitive drum caused by a rotary brush such as an charging brush for electrically charging the surface of a photosensitive drum or a cleaning brush for cleaning the surface of a photosensitive drum. The rotary brush is in contact with the photosensitive drum. During the period of charging the photosensitive drum or cleaning its surface, the rotary brush is rotated in a first mode in which the brush rotates rubbing and sliding the surface of the photosensitive drum, and during other periods, in a second mode in which the brush is rotated passively as driven by rotation of the photosensitive drum. Abrasion of the photosensitive drum is reduced by properly controlling the width of contact between the rotary brush and photosensitive drum and the amount of push for pressing the brush against the photosensitive drum.