An image formation apparatus includes a first electrode portion including a contact electrode and a counter electrode, a second electrode portion arranged as not being in contact with a recording medium, a first sensing unit configured to sense a first current which flows to the first electrode portion as a result of application of a voltage across the contact electrode and the counter electrode while the recording medium lies between the contact electrode and the counter electrode, a second sensing unit configured to sense a second current which flows from the charged recording medium to the second electrode portion, and a control unit. The control unit sets a transfer condition for transferring a toner image to the recording medium based on the first current sensed by the first sensing unit and the second current sensed by the second sensing unit.

An image forming apparatus includes an exhaust duct to guide air inside the image forming apparatus to an outside of the image forming apparatus. A positive ion generator emits a positive ion into the exhaust duct. A negative ion generator emits a negative ion into the exhaust duct. The negative ion generator is shifted from the positive ion generator in one of an air flow direction of the air moving inside the exhaust duct and a direction perpendicular to the air flow direction.

An image forming apparatus includes a photosensitive member charged to a predetermined polarity, an intermediary transfer belt, a primary transfer member forming a primary transfer portion, an electrode member in contact with the inner peripheral surface of the photosensitive member on a downstream side, first and second detecting portion to detect a current flowing through or a voltage applied to the primary transfer member and the electrode member, respectively, and a control portion, during non-image formation, to execute a setting operation in which the transfer bias to be set during image formation is set. In executing the setting operation, the control portion sets the transfer bias based on a first detecting result detected by the first detecting portion while a voltage is applied to the primary transfer member and a second detecting result detected by the second detecting portion while the voltage is applied to the primary transfer member.

In an image forming apparatus (10), a seal member (436) is a non-conductive, flexible member supported by a developing device (43). The seal member (436) is formed to project from an edge part (43b) of the developing device (43) that faces an image carrying member (41), along a longitudinal direction (D1) of the image carrying member (41). The seal member (436) fills a part of a gap between the developing device (43) and an outer circumferential surface of the image carrying member (41). An electrode film (437) is adhered to a surface of the seal member (436). The electrode film (437) is a conductive film. A potential detecting device (642) detects a potential of the electrode film (437). A charging controller (8b) controls a charging voltage based on a result of comparison between a predetermined reference potential and the potential detected by the potential detecting device (642).

At least one partial measurement region is set in the longitudinal direction in a printable region of a photosensitive drum. After the photosensitive drum has been charged to a constant potential with a charging roller, different potentials are set in the partial measurement region and a region excluding the partial measurement region with a laser scanner, partial discharge information of the partial measurement region is detected by a discharge information detection unit, and a bias voltage in image formation that is applied to the charging roller is corrected on the basis of the value of the partial discharge information.

Provided is an image formation device including a photoreceptor configured to carry a toner image and a developer configured to form the toner image on a surface of the photoreceptor and configured such that the developer is a replaceable development unit, the image formation device including: a development bias application section configured to apply a development bias to between the photoreceptor and the developer; a stabilization control section configured to perform image stabilization control of determining a development bias value to be used in future by changing the development bias while measuring a density of the toner image formed by the developer, thereby obtaining the toner image with a target density; and a life determination section configured to determine expiration of use of the development unit when the development bias value determined by the stabilization control falls outside a preset acceptable range.

An image forming apparatus includes: an image former having parts provided in a replaceable manner to be used for image formation; a sensing part that detects a characteristic value of the parts; and a controller that determines whether the characteristic value of the parts, which fluctuates immediately after manufacture, is in a stable state based on a comparison between information regarding the characteristic value of the parts based on a detection result of the sensing part and a threshold value and sets a process condition for the image former based on the detected characteristic value when determining that the characteristic value of the parts is not in the stable state.

An image forming apparatus has a photosensitive member, a charging member, an exposing device, a developing device, a transfer member, a polishing member, a driving device, a voltage applying device, a torque detector, and a control portion. The photosensitive member has a photosensitive layer and a surface protection layer formed on the surface of the photosensitive layer. The polishing member has an elastic layer on its circumferential surface, and rotates with a linear velocity difference from that of the photosensitive member. The torque detector detects the torque of the driving device. The control portion estimates an attachment condition of discharge products to the surface of the photosensitive member based on the torque of the driving device detected by the torque detector. When the torque is equal to or higher than a predetermined value, the control portion performs an image degradation suppression process.

An image forming apparatus has an image carrying member, a charging member, an exposing device, a destaticizer, a high-voltage generation circuit, a current detector, and a controller. The controller is configured to execute a contamination state check mode having a potential saturation step where the surface potential of the image carrying member is saturated by applying a DC voltage alone to the charging member, an exposure step where the image carrying member of which the surface potential is saturated is exposed to light in an exposure pattern extending continuously over its entire area in the main scanning direction while being displaced at a constant rate in the sub-scanning direction by the exposing device, and a current detection step where the charging current that passes while the exposure pattern formed on the surface of the image carrying member passes through the charging member is detected by the current detector.

An image forming apparatus includes a developing roller, a voltage applying part, a direct current correcting part and a correction switching part. The developing roller supplies a toner to an image carrier. The voltage applying part applies a superimposed voltage of an alternating current voltage and a direct current voltage to the developing roller. The direct current correcting part corrects the direct current voltage on the basis of variation of an alternating current flowing between the voltage applying part and the developing roller. The correction switching part switches the direct current voltage correcting part between an operating state and a non-operating state.