The power supply apparatus includes an inductor; a switching element, which is connected in series to the inductor, and is configured to be driven in accordance with an input pulse signal; and a booster circuit, which is connected to both ends of the inductor, and includes a plurality of rectification units each including a diode and a capacitor, wherein the power supply apparatus is configured to repeat an operation of successively driving the switching element in accordance with the input pulse signal in a cycle that is longer than a cycle in which the switching element is successively driven.

An image forming apparatus includes a photosensitive member, a charging roller, an exposure device, a developing device, a transfer member, a fixing device, a voltage source for output the charging voltage, an executing portion for forming a test chart including a plurality of adjusting images in setting of peak-to-peak voltage values of AC voltages at a plurality of different values, a first inputting portion through which an instruction of execution of forming the test chart is inputted, and a second inputting portion through which an instruction of setting a value of peak-to-peak voltage values of the AC voltage during image formation is inputted.

Provided is an electrophotographic apparatus including: an electrophotographic photosensitive member; a voltage application unit configured to cause discharge from an electroconductive member to the electrophotographic photosensitive member; a charge transfer amount detection unit configured to detect a charge transfer amount per unit time resulting from the discharge from the electroconductive member to the electrophotographic photosensitive member; and a charging potential control unit, wherein V.sub.1 and V.sub.2 defined by specific procedures for the electrophotographic photosensitive member satisfy a relationship represented by the following expression (E-4): 100V.sub.1<V.sub.2?V.sub.1 (E-4), and wherein the charging potential control unit is configured to control the charging potential of the electrophotographic photosensitive member at the time of image formation.

A charged positive toner having a positive polarity that attaches to a charge roller is moved from the charge roller to a photosensitive drum, and the positive toner is transferred to an intermediate transfer belt at a primary transfer portion at which a primary-transfer power supply forms an electric potential having a negative polarity. The primary-transfer power supply forms an electric potential having the positive polarity at the primary transfer portion, and the positive toner transferred to the intermediate transfer belt is moved together with the intermediate transfer belt and is collected by the charge roller in contact with a downstream photosensitive drum.

An electrophotographic image forming apparatus includes: an image carrier that carries and conveys a toner image; a charging member arranged in contact with or close to the image carrier; a charging power supply that charges the image carrier; an exposurer that forms a latent image on the charged image carrier; a developing member arranged close to the image carrier; a developing power supply that develops the latent image and forms a toner image on the image carrier; a transfer member that transfers the toner image to a medium; and a hardware processor that controls the image forming apparatus, wherein the hardware processor obtains a potential of an exposure part and a non-exposure part, on the image carrier after the toner image has been transferred to the medium, determines a charging bias based on a difference between the obtained potentials, and determines a developing bias based on the determined charging bias.

A power supply apparatus including a transformer, a first rectifier smoothing unit, a separation unit, a second rectifier smoothing unit, a resistor, and a rectifier unit. The first rectifier smoothing unit is configured to rectify and smooth an alternating-current voltage generated in a secondary coil of the transformer. The separation unit configured to use the alternating-current voltage generated in the secondary coil of the transformer as an input and generate an alternating-current voltage, from which alternating-current components are separated, as an output. The second rectifier smoothing unit is configured to rectify and smooth the output of the separation unit. The resistor is connected to a line branched from a line that connects the separation unit to the second rectifier smoothing unit. The rectifier unit is connected in series between the resistor and a reference potential.

An image forming apparatus includes a charger, a photoconductor, a charging high-voltage power supply, and circuitry. The charging high-voltage power supply supplies a charging bias to the charger and generates an output value feedback voltage representing a voltage value corresponding to an output current value from the charger to the photoconductor. The circuitry extracts a minimum value of the output value feedback voltage based on the output value feedback voltage generated in a given time. The circuitry calculates a maximum gap value between the charger and the photoconductor based on the minimum value. The circuitry calculates an AC voltage value based on the maximum gap value. The circuitry adds the AC voltage value to a DC voltage value to generate and transmit an output value control signal to the charging high-voltage power supply, to cause the charging high-voltage power supply to adjust the charging bias.

In an example, a method of controlling voltage applied to a print blanket within a printing device includes printing a print job. During the printing, a null cycle trigger is received. In response to the trigger, a print blanket bias voltage is reduced from a print bias level to a null bias level.

A feeding apparatus includes a feeding unit, an ion generating unit and a controller. The ion generating unit irradiates the sheet fed by the feeding unit with the ion. The controller acquires an information on the fed sheet and to controls the ion generating unit. The controller operates the ion generating unit in a case that the information of the sheet is a first information, and does not operate the ion generating unit in a case that the information of the sheet is a second information.

An image forming apparatus according to this disclosure includes: a charging roller that charges a surface of a photoconductor drum; a development unit that forms a toner image on the surface of the photoconductor drum; an image density sensor that detects density of the formed toner image; a charge power supply that applies a bias voltage to the charging roller; a development power supply that applies a bias voltage to the development unit; and a controller. The controller causes the charge and development power supplies to output respective predetermined bias voltages for predetermined time, and is capable of executing a contact and separation determination mode in which a contact and separation state of the charging roller is determined based on whether or not an image is detected by the image density sensor after output of the respective bias voltages.