When, in a state where a developer borne by a developer bearing member is sandwiched by an opposing portion of an image bearing member and the developer bearing member, C denotes capacitance between the image bearing member and the developer bearing member, ΔV denotes a development contrast, Q/S denotes a charge amount per unit area of the developer borne by the developer bearing member, and Δv denotes a peripheral velocity ratio which is a ratio of a peripheral velocity of the developer bearing member to a peripheral velocity of the image bearing member, a first peripheral velocity ratio is set so that |Q/S×Δv|≦|C×ΔV| is satisfied, and a second peripheral velocity ratio which is larger than the first peripheral velocity ratio is set so that |Q/S×Δv|>|C×ΔV| is satisfied.

An image forming device includes: a charging unit configured to apply charging bias voltage to a charging member and charge a surface of an image carrying body; an exposure unit configured to expose the surface of the image carrying body, and form an electrostatic latent image; a developing unit configured to apply developing bias voltage to a developer carrying body, and develop the electrostatic latent image; and a control unit configured to control timing to start applying the developing bias voltage relative to timing to start applying the charging bias voltage, wherein the control unit performs control such that the larger an absolute value of the charging bias voltage is, the shorter an interval from timing to start applying the charging bias voltage to timing to start applying the developing bias voltage becomes, and such that the smaller the absolute value is, the longer the interval becomes.

An image forming apparatus includes an image forming unit that forms an image by forming an electrostatic latent image on an image carrier, which is charged by a charging member to which a normal voltage is applied, on the basis of image information and by supplying a developer to the image carrier; an application unit that applies a special alternating-current voltage to the charging member, the special alternating-current voltage at least having an amplitude that is greater than that of an alternating-current voltage that is applied when forming the image; and an instruction unit that instructs the application unit to apply the special alternating-current voltage at a specific time in a period other than an image forming period during which the image forming unit forms the image.

An image formation apparatus includes: a first image formation unit including a first image carrier and a first charging member that charges the first image carrier, the first image formation unit using a first developer and; a second image formation unit including a second image carrier and a second charging member that charges the second image carrier, the second image formation unit using a second developer; and a controller that determines a first charging voltage correction amount for correcting a charging voltage to be applied to the first charging member according to an amount of usage of the first image carrier, and determines a second charging voltage correction amount for correcting a charging voltage to be applied to the second charging member according to an amount of usage of the second image carrier. The second charging voltage correction amount is larger than the first charging voltage correction amount.

An image forming apparatus includes an image carrier, a cleaning member that cleans the image carrier, an image forming unit that forms an image on a recording material, and a controller that controls the image forming unit based on at least one of physical property information and dimension information of the cleaning member.

An optical scanning apparatus according to one aspect of this invention includes a light source that outputs a light beam having a light power based on a supplied driving current, a detection unit that detects the light power of the light beam, and a voltage holding unit that holds a charged voltage used to control the driving current. The optical scanning apparatus further includes a control unit that controls a charging unit so that the voltage holding unit is charged in a state where the driving current is not supplied to the light source, and controls the charging unit based on a detection result of the detection unit so that the voltage held in the voltage holding unit is controlled from the voltage of the voltage holding unit charged in the state where the driving current is not supplied to the light source.

An image forming apparatus includes an image bearing member, a charging member, a developing member, a transfer unit, a pre-charging exposure unit, a voltage receiving member, a measuring portion, and a controller for determining a light quantity of the pre-charging exposure unit during image formation. The controller includes, a light quantity controller for controlling the light quantity so that the image bearing member charged by applying a first potential to the charging member is exposed to light at a first light quantity by the pre-charging exposure unit, and an acquiring portion for acquiring an output of the measuring portion when the image bearing member exposed to light at the first light quantity is charged by applying a second potential of an opposite polarity to a polarity of the first potential to the voltage receiving member.

An image forming apparatus includes a potential applier, a cleaning device and a hardware processor. The cleaning device includes an abutting member abutting a surface of the image carrier and removes residual toner on the surface of the image carrier by means of the abutting member after a toner image formed on the surface of the image carrier is transferred to a transfer material. In a cleaning mode for removing a foreign matter attached to the abutting member of the cleaning device, the hardware processor controls the potential applier to alternately apply a first potential and a second potential which is lower than the first potential to the image carrier so as to periodically change a potential of the abutting member without causing saturation.

Fluctuations in chargeability in an initial state are expected to be small. If a charging member is new, an image forming apparatus performs a supply operation for supplying a developer or a lubricant prior to an image forming operation in such a manner that the developer or the lubricant adheres to a surface of the charging member.

An image forming apparatus includes a rotatable photosensitive member (drum), a first corona charger, a second corona charger, an image forming portion, a voltage applying portion, a surface potential detecting portion, a controller. The controller determines a condition of voltages applied to the first and second corona chargers during image formation, by setting a first voltage condition for the first corona charger so that the surface potential of the drum is a second potential lower in absolute value than the first potential in a state in which the first corona charger operates, and the second corona charger does not operates, and then by setting a second voltage condition for the second corona charger so that the surface potential of the drum is the first potential in a state in which the first corona charger operates under the first voltage condition, and the second corona charger operates.