Abstract: A power source includes a voltage setting unit configured to set an output voltage, a voltage generation unit configured to output the set voltage to a load, a feedback unit configured to detect the output voltage and feed back the detected voltage to the voltage setting unit, a current detection unit configured to detect a current value which is a sum of a current value flowing in the feedback unit and a current value flowing in the load when the set voltage is output to the load, and a control unit configured to switch between a constant current control which controls the set voltage so that the detected current value becomes a constant current, and a constant voltage control which controls the set voltage so that the voltage output to the load becomes a constant voltage based on the voltage value that is fed back by the feedback unit.

Abstract: An image forming apparatus includes a power supply unit supplying power to a plurality of components, the power supply unit including a first power mode and a second power mode, the second power mode supplying less power than the first power mode, a control unit controlling which power mode the power supply unit uses, an authentication unit performing a user authentication when power is supplied from the power supply unit in the second power mode and an authentication request received in the second power mode, and a sending unit sending a request signal requesting the control unit to shift the power supply unit to the first power mode when the authentication unit succeeds in the user authentication, wherein the control unit controls the power supply unit to shift from the second power mode to the first power mode upon receipt of the request signal.

Abstract: An image forming apparatus includes a image bearing member (drum); a developing device; a first charging member; a second charging member provided downstream of the first charging member and upstream of the developing device with respect to a rotational direction of the drum; a first power source for applying a DC voltage to the first charging member; a second power source for applying an oscillating voltage, in the form of a DC voltage biased with an AC voltage, to the second charging member; a detecting device for detecting a DC current passing through the second charging member; and a controller for controlling, when the oscillating voltage is applied to the second charging member while the DC voltage is applied to the first charging member, the DC voltage applied to the first charging member so that the detected DC current falls within a predetermined range including zero.

Abstract: A charging device includes a charging roll, a voltage application member and a confronting potential varying unit. The charging roll is disposed so as to be in contact with an image holding body on whose surface an electrostatic latent image is to be formed, and charges the image holding body. The voltage application member is disposed so as to be in contact with the charging roll, and applies a voltage to a surface of the charging roll. The confronting potential varying unit varies a surface potential profile of the charging roll in its axial direction in a contact region between the charging roll and the image holding body according to both the number of image-formed sheets and a wear situation of the image holding body so that a surface potential of the image holding body becomes approximately constant in an axial direction of the image holding body.

Abstract: A disclosed image forming apparatus performs communications in a non-contact manner with a mobile terminal device storing print information. The image forming apparatus stores, in association with each other, identification information for identifying a reading unit configured to read the print information, function information indicating a function of processing the print information, and function setting information indicating process contents of the function; reads the print information stored in the mobile terminal device with a reading unit disposed in the image forming apparatus at a position according to the function information and the function setting information; acquires the stored function information and function setting information associated with the identification information held by the reading unit that has read the print information; and processes the print information based on the acquired function information and function setting information.

Abstract: A switching power supply device includes a switching power supply integrated circuit that includes a dead time generating unit that generates high-side and low-side drive signals having a dead time based on a PWM signal, a drive signal generating unit that generates first and second PWM signals based on the drive signals and a voltage of an output terminal, and a driver that includes high-side and low-side switch elements driven by the PWM signals; a filter that is connected to the output terminal; a first diode having a cathode connected to the source of the high-side switch element and an anode connected to the output terminal; and a second diode having a cathode connected to the source of the low-side switch element and an anode connected to the output terminal. The first and second diodes are arranged outside the switching power supply integrated circuit.

Abstract: A charging device includes a charging member in contact with or adjacent to a charged body, a charge housing that holds the charging member, bearing members that rotatably support the charging member, at least one of the bearing members being a conductive bearing member, pressing members that press the bearing members toward the charged body, at least the pressing member for the conductive bearing member being formed of a conductive material, a platelike power supply member in contact with the pressing member for the conductive bearing member, and positioning mechanisms that position the bearing members. The power supply member has a platelike extending portion. The positioning mechanism provided on a power supplied side of the charging member includes a positioning portion provided in the conductive bearing member, and a positioned portion provided in the extending portion. The positioned portion engages with the positioning portion when the extending portion elastically deforms.

Abstract: A connector to electrically connect a rotary body having a shaft, the connector includes a connecting terminal, electrically connected to either a power supply or ground, to contact the shaft of the rotary body either at least two points or along a line; and a posture adjuster to hold the connecting terminal to adjust the posture of one of the connecting terminal and the rotary body to maintain contact between the connecting terminal and the shaft of the rotary body.

Abstract: An image forming apparatus includes a photosensitive drum chargeable by a charging device; a developing device for developing an electrostatic image formed on the drum, wherein the developing device includes a carrying member for carrying and conveying toner to a position where the toner opposes the drum and a screw; a transfer device for transferring a toner image formed on the drum; an exposure device for lowering a potential of the drum by exposing the drum to light; and a controller for effecting, in a period in which the screw is rotated to supply the toner to a portion of the carrying member where the toner is not carried, such a control that the toner is not moved from the carrying member to the drum by electrically charging the drum and that an exposure amount of the drum is smaller than an exposure amount during image formation.

Abstract: An image forming apparatus that can prevent image deletion in carrying out image formation upon turning-on of power supply after main power supply is turned off before the image forming apparatus goes into a sleep state. A movable member is moved between a shielding position at which it shields a photosensitive drum from a charger and a retracting position at which the photosensitive drum and the charger are opened to each other. When power supply is turned on, a time period for which the photosensitive drum is rotated by a driving unit is controlled according to the position of the movable member detected by a movable member sensor.

Abstract: An image processing apparatus is provided that includes plural devices, a device control unit associated with each of the devices for controlling a power status of each of the devices according to a relevant power mode, and power mode setting unit for setting the relevant power mode to the device control unit.

Abstract: An image forming apparatus includes: a first photosensitive member; a second photosensitive member; a third photosensitive member; a first scorotron-type charger that is configured to charge the first photosensitive member; a second scorotron-type charger that is configured to charge the second photosensitive member; a third scorotron-type charger that is configured to charge the third photosensitive member; a first voltage applying circuit, which is connected to the first scorotron-type charger, and which is configured to apply a voltage to the first scorotron-type charger; and a second voltage applying circuit, which is commonly connected to the second scorotron-type charger and the third scorotron-type charger, and which is configured to apply a voltage to the second scorotron-type charger and the third scorotron-type charger.

Abstract: An image forming apparatus includes: a photoconductor; a charger configured to charge the photoconductor, the charger including a discharge wire and a grid; a voltage applying circuit configured to generate charge voltage and apply the charge voltage to the discharge wire of the charger; a grid-current detector configured to detect a grid current passing through the grid; a controller configured to control the voltage applying circuit on the basis of a detection value detected by the grid-current detector so that the grid current is constant; an abnormal-discharge detector configured to detect an abnormal discharge occurring in the charger; and a suppression resistor configured to suppress abnormal discharge energy. The suppression resistor includes a first terminal and a second terminal. The first terminal is connected to the grid. The second terminal is connected to at least one of the grid-current detector and the abnormal-discharge detector.

Abstract: Embodiments of the present invention include an image bearing member arranged to bear an electrostatic latent image, a charging member contacting the image bearing member to charge a surface of the image bearing member with application of a DC voltage to the charging member, a current detection unit arranged to detect a DC current flowing in the charging member, and a control unit configured to control the voltage applied to the charging member, wherein a plurality of different DC voltages are successively applied to the charging member during a period of no image formation until a change amount of change in the DC current with respect to change in the DC voltage becomes not larger than a predetermined value, and the control unit controls a DC voltage applied to the charging member during a period of image formation based on a result detected by the current detection unit.

Abstract: Provided is an image forming apparatus having a charge brush for charging a transfer residual toner remaining on an intermediate transfer member. A toner is adhered to the charge brush. While a charge voltage is applied to the charge brush, the toner adhered to the charge brush is attracted by an electric field onto the charge brush. However, when the charge voltage is not applied to the charge brush, the toner adhered to the charge brush is moved to the intermediate transfer member. When a subsequent toner image is formed on the toner adhered to the intermediate transfer member, the quality of the subsequent image is deteriorated. Accordingly, the charge voltage is applied to the charge brush when an intermediate transfer area to which the toner image is transferred onto the intermediate transfer member immediately afterward faces the charge brush.

Abstract: A charging device is provided. The charging device includes a shield, a discharging part disposed inside the shield, a grid formed at an open end of the shield. The charging device further includes a power supply unit supplying charging power while maintaining the voltage difference between the discharging part and the grid at a predetermined level.

Abstract: An image formation device is provided with an image formation unit configured to form an image on a recording sheet, a first frame arranged to support the image formation unit, a second frame connected to the first frame, flexure rigidity of the second frame being smaller than flexure rigidity of the first frame, an electric substrate electrically connected with the image formation unit. With the above configuration, the electric substrate is arranged to extend from the first frame to the second frame and is secured onto the first frame with the position on the first frame being adjusted.

Abstract: A process cartridge includes a photosensitive member, a charger, which charges the photo sensitive member, and a process frame, which supports the photo sensitive member and the charger. The charger includes a charged wire, a grid that is interposed between the charged wire and the photosensitive member, a wire-side connecting portion that applies a voltage to the charged wire, and a grid-side connecting portion that applies a voltage to the charged wire. The process frame comprises an exposure opening that faces the photosensitive member, the exposure opening being provided between the wire-side connecting portion and the grid-side connecting portion when viewed from a first direction in which the charged wire is stretched.

Abstract: A printing apparatus includes a detection signal receiving device that receives a detection signal from a computer; where a printable condition determining device subsequently determines whether a predetermined printable condition is satisfied; where a power-ON device subsequently turns-ON the main power supply of the printing apparatus; and where a control device subsequently executes print preparation processing; wherein when the power-ON device turns-ON the main power supply of the printing apparatus, the printing apparatus is in sleep mode or energy saving mode in which electric power is supplied only to the control device and the detection signal receiving device; and the printing apparatus includes a power supply portion equipped with a battery, and when a power supply is started, first, the printing apparatus turns into sleep mode or energy saving mode in which electric power is supplied only to the control device and the detection signal receiving device.

Abstract: A control apparatus connected to the plurality of image processing apparatuses by way of a network judges whether to apply current to a data processing unit held by the image processing apparatus based on a predetermined current application judging rule and transmits a result of judgment to the image processing apparatus. Each image processing apparatus, in the case of receiving the result of judgment of whether to apply current to the data processing unit through a NIC from the control apparatus, controls a current application state of the data processing unit based on the result of judgment. The data processing unit is divided in a plurality of functional blocks, and the current application to the data processing unit is controlled, functional block by functional block.

Abstract: An image forming apparatus, including: a fixing device having: a first heat generator for generating heat for a fixing processing, the first heat generator using electric power supplied by a commercial power source; and a second heat generator for generating heat for the fixing processing, the second heat generator using electric power supplied by the auxiliary power source device; a heat generation controller for allowing the first heat generator and the second heat generator to generate heat; a sheet jam detector for detecting a sheet jam of a recording sheet which occurs in the image forming section having the fixing device and a conveyance path of a recording sheet; and a charge controller for allowing charging of the auxiliary power source device to start when the sheet jam detector detects a sheet jam, and the charged capacity detector detects no full charge of the auxiliary power source device.

Abstract: An image forming apparatus includes a main power unit that outputs a first DC power and an auxiliary power unit that outputs a second DC power to the components of the image forming apparatus. The auxiliary power unit includes a rechargeable capacitor. A measuring unit measures performance of the capacitor and a determining unit determines performance insufficiency of the capacitor based on the measured performance and the system configuration of the image forming apparatus. The performance is, for example, changes in a capacitance of the capacitor with time. When the determining unit determines performance insufficiency of the capacitor, a control unit adjusts, for example, a use range of the capacitor.

Abstract: An image forming apparatus includes a photosensitive member, an exposure unit configured to expose the photosensitive member corresponding to an image, a developing unit configured to develop, using a toner, an electrostatic latent image formed on the exposed photosensitive member, a generation unit configured to generate a waveform signal for the developing unit, a parallel-to-serial conversion unit configured to apply, at a predetermined sampling period, parallel-to-serial conversion to a plurality of signals including the generated waveform signal, a serial-to-parallel conversion unit configured to apply, at the predetermined sampling period, serial-to-parallel conversion to the signals output from the parallel-to-serial conversion unit, and a voltage applying unit configured to apply to the developing unit a voltage composed of a direct-current voltage and an alternating-current voltage superimposed thereon based on the waveform signal among signals output from the serial-to-parallel conversion unit.

Abstract: The high-voltage output apparatus includes a voltage application part that applies a DC voltage to the charge member; a current detection part that detects a value of a current flowing in the image bearing member when the DC voltage is applied to the charge member; and a control part that calculates a plurality of discharge start voltages for the image bearing member, based on a plurality of current values detected by the current detection part as a result of the voltage application part applying a plurality of different DC voltages to the charge member, and controls the DC voltage applied to the charge member, using the plurality of calculated discharge start voltages. Consequently, a high-quality image can be formed by maintaining a potential on a photosensitive drum to be constant irrespective of the states of the circumstances and/or the drum layer thickness.

Abstract: The image forming apparatus including: a photoconductor provided with a charge generation layer and an overcoat layer; a first charging unit charging the photoconductor when an image is formed; an exposure unit irradiating the photoconductor with light having a wavelength to which a relative sensitivity of the charge generation layer is larger than a relative sensitivity of the overcoat layer; a development unit developing an electrostatic latent image formed on the photoconductor by the first charging unit and the exposure unit with toner; a transfer unit transferring an image developed on the photoconductor to a medium; a light irradiation unit irradiating the photoconductor with light having a wavelength to which the relative sensitivity of the overcoat layer is larger than the relative sensitivity of the charge generation layer; and an erasing unit erasing a charge from the photoconductor irradiated with light by the light irradiation unit.

Abstract: A multiple-output power supply unit includes: a first voltage generation circuit that generates a first voltage applied to a first load; a first output terminal that outputs a second voltage corresponding to the first voltage to a second load; a first constant voltage element that is connected to the first output terminal; a second constant voltage element that is provided between the first constant voltage element and a ground; and a second output terminal that is connected between the first constant voltage element and the second constant voltage element so as to output a third voltage having a predetermined potential difference from the second voltage to a third load that is provided in a state of being electrically connected to the second load.

Abstract: An output system having an output device that performs output based on output data so that the output device performs the output after having acquired authentication. In the system, an operating state controlling unit outputs a power-save-cancel command for causing a power-saving state to be changed into an active state to a power-save switching unit after a device having an output data storing unit acquires the output data, and a transition-to-power-save command for causing the state to be changed from the active state to the power-saving state is outputted to the power-save switching unit when the output process of the output data is completed by an output process completion detecting unit.

Abstract: In a high voltage power supplying apparatus, a pulse generation unit generates a pulse signal with a predetermined frequency. A piezoelectric transformer outputs a voltage in accordance with the frequency of the pulse signal. A detection unit detects an output voltage of the piezoelectric transformer. A control unit controls the pulse generation unit to change the frequency of the pulse signal by a predetermined value towards a frequency corresponding to a target voltage until the output voltage becomes equal to the target voltage. A storage unit stores data indicating the frequency when the output voltage reaches the target voltage. The control unit controls the output voltage to be equal to the target voltage by variably controlling the frequency of the pulse signal by a value smaller than the predetermined frequency from the frequency corresponding to the data stored in the storage unit.

Abstract: A power supply unit includes a switching circuit that drives a switching device by a duty ratio corresponding to a target voltage output value and outputs an alternating current signal; a coupling capacitance element provided in a subsequent stage with respect to the switching circuit; a voltage transformation unit that increases a voltage of the alternating current signal input by using the switching circuit, and outputs a high-voltage alternating current voltage to an electrifying unit; a charging unit that charges the coupling capacitance element in response to a power supply voltage being turned on; and a control unit that controls driving of the switching device to cause the coupling capacitance element to be charged to a predetermined charged amount before the switching circuit starts outputting the alternating current signal.

Abstract: A high voltage power controlling apparatus of an image forming apparatus including a DC (direct current) power controller to convert and output a first PWM (pulse width modulation) signal provided from an engine controller into a switching waveform signal, a first voltage transformer to transform the switching waveform signal output from the DC power controller, a rectifier to rectify output power transformed by the first voltage transformer into DC power, first through N(where N is a positive integer greater than one) DC supplies to adjust and output the DC power rectified by the rectifier such that the DC power is adjusted to a predetermined level, first through N AC (alternating current) power controllers to convert and output a second PWM signal provided from the engine controller into switching waveform signals, and second through N+1 voltage transformer to transform the switching waveform signals output from the first through N AC power controllers, to overlap the transformed powers with the DC powers h

Abstract: A power supply device supplies power to an image forming apparatus. The image forming apparatus includes a load and a control unit. The load requires power, and is controlled by the control unit. The power supply includes a capacitor and a power-supply unit. The capacitor is charged by an external power source, and dischargably stores therein power. The power-supply unit provides power supply from the capacitor to the load and the control unit before voltage of the external power source drops below a threshold level where malfunction of the image forming apparatus occurs. After the voltage recovers to the threshold level, the power-supply unit stops the power supply from the capacitor.

Abstract: An image forming device includes: a high voltage generating circuit for applying an oscillating voltage to a charging member disposed in contact with or proximity to an image carrier, the oscillating voltage having a DC voltage Vdc and an AC voltage Vac superimposed thereon; a current detecting portion for detecting the value of a DC current Idc between the image carrier and the charging member; an AC voltage control portion for controlling the value of the AC voltage Vac so as to secure the detected value of the DC current Idc within a target current range; and an aging control portion for performing rotation driving of the image carrier while securing the AC voltage Vac and the DC voltage Vdc at preset voltage values and setting the frequency of the AC voltage Vac at a frequency different from a frequency during an image forming operation.

Abstract: A high-voltage power supply comprises the following components. A piezoelectric transformer outputs a voltage in accordance with a supplied drive frequency. A rectification part is connected to an output side of the piezoelectric transformer. A drive frequency generating part generates the drive frequency supplied to the piezoelectric transformer. A voltage detection part detects an output voltage of the piezoelectric transformer or the rectification part. A control part controls the drive frequency generating part such that a drive frequency corresponding to the output voltage detected by the voltage detecting part is generated. A first time constant, which is a time constant of the control part, is smaller than a second time constant, which is a time constant of a control target including the piezoelectric transformer and the rectification part. A third time constant, which is a time constant of the voltage detecting part, is smaller than the second time constant.

Abstract: An image forming apparatus capable of maintaining cleaning performance of a cleaning brush and downsizing the apparatus main body. Transfer residual toner accumulated on the cleaning brush is transferred onto a photoreceptor by an electrostatic force, hence the cleaning brush becomes clean and the cleaning performance thereof improves. Therefore, the photoreceptor and a charging roller can be cleaned well by the cleaning brush over a long period of time, and the photoreceptor can be charged well by the charging roller over a long period of time. Moreover, because the transfer residual toner that is transferred from the cleaning brush onto the photoreceptor is recovered by a developing device, it is not necessary to provide the apparatus main body with a toner recovery portion that is specially designed for recovering the transfer residual toner, hence the apparatus main body can be downsized.

Abstract: An aspect of the invention provides a charging control device of a color image forming apparatus, and the charging control device can properly control a charging potential of an image bearing body such that fog and uneven density are not generated even in a low-temperature environment. The image forming apparatus includes a high-voltage generation circuit 91 which applies an oscillating voltage to the charging member 42 disposed in contact with an image bearing body 41, a direct-current voltage and an alternating-current voltage being superimposed to form the oscillating voltage; a current detection unit 92 which detects a direct current value passed from the charging member 42 to the image bearing body 41; and a voltage control unit 96 which controls the alternating-current voltage such that the detected direct-current value is maintained in a target current range. The image forming apparatus also includes an aging control unit 95 to perform running-in.

Abstract: A voltage converting unit converts a first voltage of an auxiliary power supply unit into a second voltage. A voltage determining unit determines whether the second voltage exceeds a predetermined threshold. A first switch, which is arranged between the voltage converting unit and a load, switches on and off a supply of an electric power of the second voltage to the load. When it is determined that the second voltage exceeds the predetermined threshold, a voltage-conversion control unit controls the voltage converting unit to stop converting the voltage, and then a switching control unit controls the first switch to supply the electric power of the second voltage to the load.

Abstract: A transfer unit, which transfers a toner image formed on at least one image support to a printing medium, and an image forming apparatus employing the same. The transfer unit includes: an intermediate transfer body to the toner image from the image support, which has a curved transfer surface and an ASKER-A hardness of from about 25° to 40°; a transfer member, which has an ASKER-C hardness of from about 45° to 70°, and which contacts the intermediate transfer body, with a printing medium being interposed therebetween, and transfers the toner image from the intermediate transfer body to the printing medium. The transfer unit may further include: a de-electrifying member having a DC power and an AC power concurrently applied thereto, to de-electrify the printing.

Abstract: An image forming apparatus includes a voltage applying unit for applying a voltage to an electric load; a sub control unit for controlling the voltage applying unit; a restarting unit for restarting the sub control unit in response to receipt of a restart signal; a determining unit for determining whether or not restart of the sub control unit is abnormal restart; and a main control unit. The main control unit generates a control start signal for allowing the voltage applying unit to start generation of the voltage, and the restart signal. When the determining unit determines that restart of the sub control unit is abnormal restart, the main control unit sends again the control start signal to the sub control unit.

Abstract: An image forming apparatus includes, an image forming unit, an irradiating unit, a first low voltage power supply which generates a first low voltage, a first low voltage power supply line, a first switching element, a first high voltage generating unit including a first transformer, a second low voltage power supply, and a control unit. The image forming apparatus further includes an cover which can be opened and closed, wherein the image forming unit detects the opening and closing of the cover; and an interlock switch which interlocks with the opening/closing of the cover and includes a first contact point connected to the first low voltage power supply and a second contact point connected to the first low voltage power supply line, wherein the interlock switch is opened to disconnect the first contact point from the second contact point when the cover is opened.

Abstract: A charging apparatus includes a charging member to charge a surface of a photoconductive medium, a power unit to supply an electric power as a bias voltage to the charging member, and a resistor unit to reduce a ripple on the surface of the charging member. Accordingly, a stability of the charging apparatus is secured without using a separate power device.

Abstract: An image forming apparatus includes a photosensitive body to be developed by a conductive toner, a charger which charges a surface of the photosensitive body with a surface potential, a power supply which supplies one of a normal charging power to perform a normal charging operation and a compensation charging power, having a different absolute value than the normal charging power and having the same polarity as the normal charging power, to the charger, and a controller which controls the power supply to supply the normal charging power and the compensation charging power to the charger, respectively, before and after a charging time at which a rear end contact surface of the photosensitive body contacting a rear end of a printing medium is charged by the charger.

Abstract: A corona generating device for charging a surface including, a housing; the housing including spaced generally parallel side panels; members for holding a corona generating electrode in an operable position within the housing; and system for adjusting the height spacing of the corona generating electrode relative to the surface the adjusting system includes a first bridge member adjacent to the inboard wire mount and a second bridge member adjacent to the outboard wire mount, the first bridge member and second bridge member contacts the wire to change the distance of the wire relative to the surface.

Abstract: An image formation apparatus that includes a photoconductor, a charging section that applies a bias voltage having an AC voltage superposed on a DC voltage and charges the photoconductor, a controller that controls at least one of the AC voltage and an AC current applied by the charging section, and a detector that detects an amount of discharge occurring between the photoconductor and the charging section. The controller controls at least one of the AC voltage and the AC current so that the amount of discharge detected by the detector falls within a predetermined range containing a singularity in change of the amount of discharge.

Abstract: An image data processing apparatus shifting to a power saving mode depending on whether a particular process is in progress on an image processing apparatus. A controller examines processes of host computers through a network, and controls a state of supplying power to blocks functioning for an image forming process, the blocks including a rasterizer, a memory, a printer engine, and a compressor/expander.

Abstract: In an image forming apparatus in which a DC bias is applied to charge a photosensitive drum, when a charge eliminating device is in deterioration or failure, there are some cases where a proper charging is not made, and thus poor imaging occurs. A DC bias is applied to a charging member in the charge eliminating operation area of an image bearing member where the charge eliminating device makes charge eliminating operation; and based on the values of an electric current passing through the image bearing member on that occasion, a DC bias application is switched between by constant-current-control and by constant-voltage-control.

Abstract: A charging device is provided. The charging device includes a shield, a discharging part disposed inside the shield, a grid formed at an open end of the shield. The charging device further includes a power supply unit supplying charging power while maintaining the voltage difference between the discharging part and the grid at a predetermined level.

Abstract: An image forming apparatus includes a plurality of image forming stations. In each image forming station an electrostatic latent image carrier and a charging member are arranged to face each other with a specified gap therebetween. A charging failure caused by an abnormal discharge in the gap is detected based on a current detection result by a current sensor, and an image forming station having an abnormality is reliably specified.

Abstract: An image forming apparatus comprising an image bearing member, a transfer mechanism that transfers a developer image formed on the image bearing member, a charger that charges the image bearing member, a first high voltage power supply substrate that applies a first voltage to the transfer mechanism, and a second high voltage power supply substrate that applies a second voltage to the charger, wherein the second voltage has a polarity opposite to the first voltage.

Abstract: A charging device includes a charging member that charges a body to be charged; a detector that detects an AC component of a current flowing through the charging member; an integration section that integrates the AC component of the current detected by the detector; a controller that controls the current flowing through the charging member, according to a result of integration executed by the integration section; a periodic signal generating section that generates a periodic signal having a cycle period corresponding to a cycle period of the AC component; and an integration period adjusting section that adjusts a period of integration executed by the integration section, with reference to the periodic signal.

Abstract: A tandem image forming device includes: a high voltage generating circuit for applying an oscillating voltage to a charging member disposed in contact with or proximity to an image carrier, the oscillating voltage having a DC voltage and an AC voltage superimposed thereon; a voltage control portion for controlling the peak-to-peak voltage of the AC voltage at a target voltage, the image forming device changing by switching a process speed depending on monochrome image formation and color image formation; a current detecting portion for detecting the value of a DC current between the image carrier and the charging member; and a frequency switching portion for switching the frequency of the AC voltage between frequencies according to the process speed. The voltage control portion includes an initial voltage adjusting portion for adjusting the target voltage on the basis of the value of the DC current detected by the current detecting portion.