A control portion executes: a step of calculating a surface potential of an image bearing member charged by a charging member, to which a predetermined voltage is applied, and exposed to light by a predetermined exposure amount on the basis of a discharge start voltage between a measurement member and the image bearing member and calculating a correction value from a difference between a target value and calculated surface potential of the image bearing member; a step of correcting calculated surface potential of the image bearing member on the basis of the correction value; and a step of controlling at least one of the voltage applied to the charging member and an exposure amount of the exposure apparatus on the basis of the corrected surface potential of the image bearing member so that the surface potential of the image bearing member reaches the target value.

An image forming apparatus includes an image carrier that is capable of holding an image on a surface thereof while rotating, an image forming unit that forms the image on the image carrier, a transfer unit that transfers the image from the image carrier to a medium while rotating, a transport unit that circulates as the transfer unit rotates and that transports the medium to a transfer region while holding the medium, and a control unit that changes a timing at which the image forming unit forms the image in accordance with variation in a ratio of a rotation velocity of the transfer unit to a rotation velocity of the image carrier.

An image forming apparatus includes a photoconductive drum, a developing roller, a humidity sensor configured to detect a humidity, and a controller configured to execute a single-side printing, a first-double-side printing and a second double-side printing. The controller is configured to execute the first double-side printing in which images are printed at a first developing-bias voltage on both the first surface and the second surface of the sheet when the humidity detected by the humidity sensor is greater than a threshold value. The controller is configured to execute the second double-side printing in which an image is printed at a second developing-bias voltage, which is less than the first developing-bias voltage, on the second surface of the sheet when the humidity detected by the humidity sensor is equal to or less than the threshold value.

A server apparatus including a first communication device and a first computing device. The first communication device communicates with an image forming apparatus via a network. The first computing device includes a processor, and acts as a data acquirer, a dimension reduction processor, and a residual service life calculator, when the processor executes a first control program. The data acquirer acquires observation data of a first number of dimensions from the image forming apparatus, via the first communication device. The dimension reduction processor converts the observation data of the first number of dimensions into characteristic data of a second number of dimensions fewer than the first number of dimensions. The residual service life calculator calculates a residual service life of a replaceable unit in the image forming apparatus, on a basis of the characteristic data.

An image forming apparatus includes a first air suction port sucking an air containing ozone, a second air suction port sucking an air containing the scattered toner, and a duct unit partitioned into a first duct passing through the air containing ozone and a second duct passing through the air containing toner. The duct includes a first fan generating a first air flow inside the first duct to suck the air from the first air suction port and a second fan generating a second air flow inside the second duct to suck the air from the second air suction port. An ozone filter is detachably provided to both the first and second ducts, disposed straddling the first and second ducts, and filters the ozone contained in the first and second air flows.

An image forming apparatus includes an image forming device, a driving device, an external temperature detector, an internal temperature detector, a work amount detector, and control circuitry. When a temperature detected by the external temperature detector is lower than a temperature threshold, the circuitry shifts to a first restriction state based on a work amount and temporarily stops drive of the image forming device for a period every time the amount reaches a threshold. When the temperature is not lower than the temperature threshold, the circuitry shifts to a second restriction state based on an internal temperature. In the second state, in a case where the internal temperature is higher than a first threshold, the circuitry performs an intermittent operation of repeating a pause state and a printing state, until the internal temperature falls to be equal to or lower than a second threshold being lower than the first threshold.

An image forming apparatus includes an image forming device, a driving device, an external temperature detector, an internal temperature detector, a work amount detector, and control circuitry. When a temperature detected by the external temperature detector is lower than a temperature threshold, the circuitry shifts to a first restriction state based on a work amount and temporarily stops drive of the image forming device for a period every time the amount reaches a threshold. When the temperature is not lower than the temperature threshold, the circuitry shifts to a second restriction state based on an internal temperature. In the second state, in a case where the internal temperature is higher than a first threshold, the circuitry performs an intermittent operation of repeating a pause state and a printing state, until the internal temperature falls to be equal to or lower than a second threshold being lower than the first threshold.

An exhaust device includes: a flow path section through which gas containing ozone generated inside a device body flows; a joint section connected to the flow path section with an inlet opening where hot gas generated inside the device body flows, and where gas containing ozone and hot gas are joined internally; a first air flow generator that generates an air flow which causes the gas containing ozone to flow through the flow path section and to the joint section; and a second air flow generator that causes the gas containing ozone and the hot gas to be joined and discharged from the joint section to outside the device body so that a flow rate of the joint gas discharged from the joint section to outside the device body is higher than a flow rate of the gas containing ozone to the joint section by the first air flow generator.

A first guide member guides a sheet from a sending roller pair to a discharge port. A second guide member is disposed above the first guide member such that an upstream end of the second guide member in a sheet discharge direction overlaps the first guide member, and forms an upper partition of a discharge path in an area extending from a position above an end of the first guide member to a position of a discharge roller pair. The second guide member guides the sheet to the discharge roller pair. A cooling fan blows air from below the discharge path toward a lower surface of the second guide member. The lower surface of the second guide member is formed convexly curved upward when viewed in a width direction intersecting the sheet discharge direction. The lower surface of the second guide member guides air toward the first guide member.

An image forming apparatus includes an image forming unit, a fixing unit, a heating portion and a removal unit to remove a particulate dust generated due to vaporization of a parting agent by heat in the fixing unit. The removal unit includes a sheet-like filter provided with a base layer and a collecting layer laminated on the base layer for collecting dust. The removal unit includes a holding unit to hold the filter in a cylindrical shape with the base layer outside and the collecting layer inside. The removal unit includes a fan connected to one of opening end sides of the filter held in the cylindrical shape and generates an air flow inside of the cylindrical shape which causes air passing from outside of the filter to inside to flow toward the one of the opening end sides.