An imaging apparatus includes a transfer belt, a transfer roller, a conductive roller, and a power source. The transfer roller includes a metal shaft electrically floating during an imaging operation. The conductive roller has an electrical resistance lower than an electrical resistance of the transfer roller. The power source is electrically connected to the conductive roller, and the power source includes a first supply path to supply a first electrical bias to the conductive roller during an imaging operation and a second supply path to supply a second electrical bias to the transfer roller during a cleaning operation.

An image forming apparatus that includes an image bearing member which can bear a toner image, a transfer member used to transfer a toner image onto a recording material from the image bearing member, and a reading device which reads density information of images on recording material disposed on the platen. The image forming apparatus forms a first chart on a first recording material and a second chart on a second recording material by sequentially transferring a plurality of test images while applying a plurality of test voltages to the transfer member. The two charts are read by the reading device and the transfer voltage is adjusted based on the reading result.

An image forming apparatus includes a controller and a transfer power supply portion configured to output a transfer voltage to a transfer portion so as to transfer the toner image onto the recording material. The transfer power supply portion superimposes a voltage output from a first power supply portion and a voltage output from a second power supply portion to output a superimposed voltage to the transfer portion. The first power supply portion includes a transformer including a primary coil and a secondary coil, and a rectifier circuit portion. The rectifier circuit portion includes a plurality of diodes and a plurality of capacitors. A capacitance of a predetermined capacitor to be charged by a half-wave rectified voltage of an AC voltage generated in the secondary coil is larger than a capacitance of a capacitor to be charged by a voltage higher than the half-wave rectified voltage.

An image forming apparatus includes: a transfer cylinder that rotates; a rotating member that is coaxial with the transfer cylinder and rotates integrally with the transfer cylinder; a circulating member that is provided with a holding part that holds a front end portion of a recording medium, is suspended around the rotating member, and transports the recording medium by circulating as the rotating member rotates; an image forming part that forms an image; and a transfer unit having a transfer belt onto which the image is transferred from the image forming part at a contact position with the image forming part and that transfers the image onto the recording medium transported by the circulating member by sandwiching the recording medium together with the transfer cylinder at a nip position. A product of mass of the transfer cylinder and a distance from a center of mass of the transfer unit to the nip position is smaller than a product of mass of the image forming part and a distance from the center of mass to the contact position.

An image forming apparatus includes a sensing portion configured to sense a current that flows through a secondary transfer member, or a voltage that has been applied; and a controller configured to perform an operation to determine a transfer voltage to be applied to the secondary transfer member in secondary transfer, on a basis of a result of sensing performed by the sensing portion at a time when a test voltage has been applied to the secondary transfer member in non-image formation, and the controller performs, in the operation, controlling a first application portion and a second application portion not to apply the voltage to a primary transfer member during a period of applying the test voltage to the secondary transfer member.

An apparatus for use in a selective toner electrophotographic process (STEP) additive manufacturing system, the apparatus includes a radiant heat source configured to emit radiation of a first band of wavelengths in the region of a transfuse roller nip; and a pyrometer configured to receive and measure radiation emitted from the region of the transfuse roller nip; wherein the radiation measured by the pyrometer comprises a second band of wavelengths different from the first band of wavelengths emitted by the radiant heat source. The radiant heat source is typically one or more laser light emitters.

A transfer device includes a transfer roller, a power source and a switch device. The transfer roller may transfer an image formed on an image carrier to a transfer medium in an imaging apparatus. The transfer roller includes a rotation shaft including a conductive material, and a ion conductive member disposed around the rotation shaft. The power source may generates a transfer voltage. The switching device may selectively connect, during rotation of the transfer roller, a power-feed path from the power source to the transfer roller, among a plurality of power-feed paths based on whether the image is being transferred or not being transferred, to thereby reverse the direction of an electric field applied by the transfer voltage to the ion conductive member.

An image forming apparatus includes a main body, a drum cartridge removably attached to the main body, and a belt unit removably attached to the main body. The main body includes a drum power supply, a belt power supply, and a controller configured to start supplying power from the drum power supply to a drum memory of the drum cartridge, start supplying power from the belt power supply to a belt memory of the belt unit, stop supplying the power from the drum power supply to the drum memory after starting supplying the power from the drum power supply to the drum memory, and stop supplying the power from the belt power supply to the belt memory after starting supplying the power from the belt power supply to the belt memory.

A power supply device includes: a DC power supply that generates a DC voltage of a variable value and outputs the DC voltage; an AC power supply that generates an AC voltage of a variable value, and superimposes the AC voltage and the DC voltage to generate a superimposed voltage for output; and a control circuit. The control circuit start giving the DC power supply an instruction to output the DC voltage, and start giving the AC power supply an instruction to output the AC voltage for restricting output of the DC voltage. The control circuit controls an absolute value of the superimposed voltage to be smaller than or equal to a predetermined value in a predetermined period from a time when the giving of the instruction to output the AC voltage is started to a time when the restricting of the output of the DC voltage is started.

An image forming apparatus includes a main body, a drum cartridge removably attached to the main body, and a belt unit removably attached to the main body. The main body includes a drum power supply, a belt power supply, and a controller configured to start supplying power from the drum power supply to a drum memory of the drum cartridge, start supplying power from the belt power supply to a belt memory of the belt unit, stop supplying the power from the drum power supply to the drum memory after starting supplying the power from the drum power supply to the drum memory, and stop supplying the power from the belt power supply to the belt memory after starting supplying the power from the belt power supply to the belt memory.