An image forming apparatus has a photoconductive member and a cleaning member arranged to face the photoconductive member at a cleaning position and configured to be applied with a cleaning bias to collect residual developing agent on the photoconductive member after the developed image is transferred. A controller of the image forming apparatus controls a transferring bias so that a transferring current representing a current flowing between the photoconductive member and a transferring member is controlled to become a target current value. Further, the controller calculates a cleaning position potential representing a surface potential of the photoconductive member at the facing position based on the transferring current and a charge potential representing a surface potential of the photoconductive member immediately after being charged by the charging device, and controls the cleaning bias based on the cleaning position potential as calculated.

An image forming apparatus includes an image bearing member, an intermediary transfer belt, a primary transfer roller provided so that a contact region between the roller and the belt and a contact region between the image bearing member and the belt are in a non-overlapping state with each other with respect to a movement direction of the belt, a primary transfer voltage source, a current detecting portion, an executing portion configured to acquire information on a discharge start voltage on the basis of a detection result of the detecting portion in a period other than a period of primary transfer by applying the voltage to the roller; and a setting portion configured to set, on the basis of an execution result of the executing portion, a primary transfer voltage applied to the roller by the primary transfer voltage source in the period of the primary transfer.

An image forming apparatus includes an image carrier, a charging device, a developing device, a developing power source, a current measuring device, and a processor. On a surface of the image carrier, an electrostatic latent image is formed. The charging device electrically charges the image carrier. The developing device forms a toner image, by supplying toner to the image carrier and developing the electrostatic latent image formed on the image carrier. The developing power source applies a predetermined bias voltage to the developing device. The current measuring device measures a developing current flowing in the developing device. The processor acts, by executing a control program, as a calculator that calculates a surface potential of the image carrier, on a basis of the developing current measured by the measuring device.

An image forming apparatus includes an image carrier, a charging device, an exposure device, a development device, a transferring part, a development bias applying part, an electric current detection part, a density detection part and a bias condition determination part. The bias condition determination part performs a DC voltage determination mode (a DC calibration) determining a reference DC voltage serving as a reference of a DC voltage of a development bias applied to a development roller and a peak-to-peak voltage determination mode (an AC calibration) determining a reference peak-to-peak voltage serving as a reference of a peak-to-peak voltage of an AC voltage of the development bias. When a difference between the reference DC voltages determined the successive DC voltage determination modes exceeds a predetermined threshold value, the bias condition determination part performs the peak-to-peak determination mode.

An image forming apparatus includes an image bearer, an image forming device to form a toner image on the image bearer with toner, a power source to output a bias to transfer the toner image onto a recording medium, and control circuitry. The circuitry controls the power source to decrease a peak-to-peak voltage of the bias in response to increase in at least one of temperature and humidity, when a time-averaged voltage of the bias is on a transfer side of transferring the toner to the recording medium, from a median value of maximum and minimum voltages of the bias. The circuitry controls the power source to increase the peak-to-peak voltage of the bias in response to increase in at least one of temperature and humidity, when the time-averaged voltage of the bias is on a return side of returning the toner to the image bearer, from the median value.

An image forming apparatus includes a high voltage generating circuit, a voltage controller, a current detector, and a recovery process controller. If two inflection points (O and P) exist, which exist on a characteristic curve indicating a relationship between the voltage value and the current value when the frequency of the AC voltage is set as a first frequency or when a photosensitive drum is rotated at a first linear speed, the recovery process is performed if a potential difference between a first inter-inflection-point voltage (OP) between inflection points and a second inter-inflection-point voltage (OP′) between inflection points (O′ and P′) when setting a second frequency different from the first frequency, or a potential difference between the first voltage and a third inter-inflection-point voltage (OP″) between inflection points (O″ and P″) when setting a second linear speed different from the first linear speed becomes a predetermined value or less.

A volt meter and a current meter may measure a voltage and a current for the calculation of power consumption. A controller may calculate the power consumption when a heating element is activated and when the heating element is deactivated. Based on the power consumptions when the heating element is activated or deactivated, a failure condition may be determined.

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.

In a first image formation mode, an image is formed with a first development contrast C1 and a specific dot pattern is formed with a second development contrast C2, which is lower than the first development contrast C1; in a second image formation mode, an image is formed with a third development contrast C3 and a specific dot pattern is formed with a fourth development contrast C4, which is lower than the third development contrast C3; and when ΔC1 (=C2/C1) denotes a ratio between the second development contrast C2 and the first development contrast C1, and ΔC2 (=C4/C3) denotes a ratio between the fourth development contrast C4 and the third development contrast C3, ΔC2<ΔC1 is satisfied.

There is provided an image forming apparatus including: an intermediate transfer belt; a photosensitive drum; a primary transfer member; a secondary transfer member; a first backup member; a first power supply electrically connected to the primary transfer member and to the secondary transfer member; and a first resistor electrically connected to the first power supply and to the primary transfer member. A first current route, in which the first resistor, the primary transfer member, and the photosensitive drum are connected in series in that order, is connected to the first power supply and to a basis potential. A second current route, in which the secondary transfer member and the first backup member are connected in series, is connected to the first power supply and to the basis potential. The first current route is connected in parallel to the second current route.