A high-voltage power supply includes: a first high-voltage output circuit having a first output connected to a first load, and a second output, and capable of outputting a first voltage having a first polarity to the first load; a voltage clamping element connected to the second output and configured to clamp a voltage at the second output to a second voltage having a second polarity opposite to the first polarity; a second high-voltage output circuit having a third output connected to the second output and a fourth output, and capable of outputting a third voltage having the first polarity; and an output circuit connected to the fourth output and a second load, and configured to produce a voltage having the first polarity and a voltage having the second polarity using the third voltage and a voltage derived from the second voltage and output the produced voltages to the second load.

An image forming apparatus includes an image bearing member and a charging member that electrostatically charges a surface of the image bearing member. Control is performed for increasing a voltage to be applied to the charging member in a stepwise manner so that the voltage becomes higher than when the image bearing member passes through a region where the image bearing member faces the charging member in a previous rotation, the control being performed as the image bearing member rotates while a single image region worth of image is being formed in an image region that is longer than a length equivalent to one rotation of the image bearing member in a rotational direction of the image bearing member.

A control unit performs control to satisfy T.sub.Va<T T.sub.Vb, where T is a time from a point when irradiation with light by a pre-exposure member is started to a point when a predetermined portion of the photosensitive member which is located at the pre-exposure position when the irradiation is started reaches a charging position, T.sub.Va is a time from the point when the irradiation is started to a point when application of a first voltage is started, and T.sub.Vb is a time from the point when the irradiation is started to a point when application of the second voltage is started.

Provided is an image forming apparatus capable of appropriately setting a range of a charging voltage for electrically charging an image bearing member. A charging roller (2) and a charging power source (S1) are configured to apply a voltage between the charging roller (2) and a photosensitive drum (1) to electrically charge the photosensitive drum (1). A control circuit (13) is configured to set a voltage for obtaining a predetermined discharge current by the charging roller (2) with the photosensitive drum (1). The control circuit (13) is configured to determine, depending on a state of a resistance acting on an electric current flowing between the charging roller (2) and the photosensitive drum (1), at least one of an upper limit or a lower limit of the voltage set by the control circuit (13).

A contact point end portion of a second ring connected to a first ring portion on a power reception portion side protrudes further in the direction of a power reception portion than a contact point end portion of the first ring connected to a spring portion on a power reception portion side.

A coil spring includes a resilient portion having a first diameter defined by a first central axis that is hypothetical and an end coil abutting on one end of the resilient portion in an axial direction of the resilient portion. The end coil has a second diameter defined by a second central axis that is hypothetical and shifted from the first central axis of the resilient portion in parallelism with the first central axis of the resilient portion by a predetermined shift amount. A coupler has a first width that is smaller than the first diameter of the resilient portion and greater than a second width obtained by subtracting the predetermined shift amount from the first diameter of the resilient portion. The coupler is inserted into the end coil to secure the end coil to the coupler.

An image forming apparatus provides a configuration capable of suppressing an increase in the resistance of an intermediate transfer belt. The image forming apparatus includes an electrification unit for electrifying an intermediate transfer belt to suppress an increase in resistance of the intermediate transfer belt.

An image forming apparatus includes a high-voltage power supply that supplies high-voltage electric power, a charging device that is charged by the electric power supplied from the high-voltage power supply, a photoconductor that carries an image to be formed on a recording medium, with the electric power supplied from the charging device, a temperature sensor disposed at a distant from the photoconductor that detects temperature inside the image forming apparatus, a humidity sensor disposed at a distant from the photoconductor that detects inside the image forming apparatus, and circuitry that outputs a signal for commanding an electric power value to the high-voltage power supply to cause the high-voltage power supply to supply the electric power with the electric power value, and controls supply of the electric power based on an electric power value feedback signal from the high-voltage power supply.

An image forming apparatus includes a photoconductor, a charger that charges the photoconductor, a transfer unit that transfers a toner image formed on the photoconductor to a transfer device, a charging power supply that outputs AC voltage for applying a charging bias to the charger, a transfer power supply that outputs DC voltage or DC current for applying a transfer bias to the transfer unit, an output detector that detects an output value of the DC voltage or the DC current, and a controller that calculates load impedance of the photoconductor based on the detected output value of the DC voltage or DC current detected by the output detector while modifying the output of the AC voltage by the charging power supply and sets the output of the AC voltage that the load impedance starts converging into a predetermined value as an adjusted AC output to the charging power supply.

An image forming apparatus includes: a first power source that supplies a charging voltage to a charger; a second power source that supplies a developing voltage to a developer; a first current detector that detects a current in the charger; a second current detector that detects a current in the developer; an OR circuit to which a first detection signal of the first current detector and a second detection signal of the second current detector are input; and a controller that determines an error related to the first power source or the photoreceptor or an error related to the second power source or the developer on the basis of an output signal of the OR circuit, which is output correspondingly to a level of the first detection signal or a level of the second detection signal.