Abstract: An image forming unit forms a plurality of measurement images based on a plurality of process conditions. A measurement unit measures the density of each of the plurality of measurement images. A determination unit uses a first determination mode or a second determination mode. In the first determination mode, a process condition is determined from a first measurement result higher than target density and a second measurement result lower than the target density, from among a plurality of measurement results. In the second determination mode, the process condition is determined from measurement results lower than the target density.

Abstract: An image forming apparatus includes: an image bearing member; a charging device which charges the image bearing member; a developing device which develops an electrostatic image formed on the image bearing member with toner; a transferring device which transfers a toner image formed on the image bearing member by the developing device onto a recording medium; a separation charge-eliminator disposed opposite to the image bearing member, for separating the medium from the image bearing member after transfer; a current detecting device which detects a separation current flowing through the charge-eliminator; and a control device which outputs a control signal regarding the charge-eliminator based on a first current value detected by the current detecting device with a charging voltage being applied to the charging device and a second current value detected by the current detecting device with a transfer voltage being applied to the transferring device.

Abstract: An image forming apparatus includes a first image forming portion including a first photosensitive member, a first charging member to electrically charge the first photosensitive member, and a first exposure member to expose to light the charged first photosensitive member to form an electrostatic latent image, and a second image forming portion including a second photosensitive member, a second charging member to electrically charge the second photosensitive member, and a second exposure member to expose to light the charged second photosensitive member to form an electrostatic latent image.

Abstract: An image forming apparatus may include a first and second mode. In the first mode, the image forming apparatus uses a second charging member to charge toner that remains on an intermediate transfer member and then transfers the charged, remaining toner to an image carrier in a primary transfer portion. In the second mode, the image forming apparatus transfers the remaining toner adhered to the second charging member in the first mode to the intermediate transfer member. Also in a second mode, the image forming apparatus controls so that a surface potential of the image carrier that reaches the primary transfer portion at a timing at which the remaining toner transferred to the intermediate transfer member passes through the primary transfer portion has a same polarity as that of a surface potential of the image carrier in the first mode and also has an absolute value smaller than that thereof.

Abstract: An image forming apparatus includes a photosensitive drum; a charging rotatable member for charging the drum by applying a voltage comprising a DC voltage component and an AC voltage component; a current detector for detecting a current flowing when a predetermined inspecting voltage is applied to the charging rotatable member; a storing portion for storing information corresponding to a reference current; a supplying portion for supplying a signal for notifying information corresponding to a lifetime of the drum on the basis of information stored in the storing portion and an output of the current detector; and a renewing portion for renewing information stored in the storing portion in accordance with the output of the current detector.

Abstract: A system for charging a photoreceptor (3) includes a first corona charging unit (2) a first corona electrode (4), a first shell electrode (6), and a first high voltage power supply (22). The shell electrode is connected through a resistor to ground and the high voltage power supply is connected to the first corona electrode. A second corona charging unit (10) has a second corona electrode (12), and a first grid electrode (14) connected to a second shell electrode (16). A first corona current from the first high voltage power supply to the first corona electrode and a return current from the first shell electrode to ground is sensed and a voltage on the high voltage power supply is adjusted to maintain a constant difference. The first corona charging unit charges the photoreceptor to at least 63% of the desired voltage.

Abstract: A changing voltage is applied to a first charging roller. A voltage obtained by superimposing an alternating voltage on a direct voltage is applied to a second charging roller disposed on the downstream side of the first charging roller in the rotation direction of a photosensitive member. During image formation, the changing voltage applied to the first charging roller is changed so that the magnitude relationship between the potential of the photosensitive member which has been charged by using the first charging roller and which has reached a position at which the photosensitive member is charged by using the second charging roller and the direct voltage applied to the second charging roller is alternately switched.

Abstract: An image forming apparatus, comprising: an attachment unit to which a load for image formation is attached; an applying circuit configured to apply an applying voltage to the load; a voltage detection circuit configured to detect the applying voltage; a current detection unit configured to detect a load current; and a control device, wherein the control device is configured to: subject the applying circuit to constant current control in accordance with a detected value of the current detection unit so that the load current becomes a target current; and switch to a constant voltage control by which the applying voltage is controlled to become a target voltage when an absolute value of the load current is smaller than a determination value and an absolute value of the applying voltage is larger than or equal to a threshold during execution of the constant current control.

Abstract: An image forming device, comprising: at least one photosensitive body; scorotron chargers that charge the at least one photosensitive body; a charge voltage applying circuit to which the scorotron chargers are commonly connected, the charge voltage applying circuit being configured to apply a voltage to the scorotron chargers; wires respectively provided for the scorotron chargers; grid electrodes respectively provided for the scorotron chargers; a current detection unit configured to detect a grid current of each of the grid electrodes; and a grid current control unit configured to execute a constant-current control for a maximum grid current which is a maximum of grid currents flowing through the grid electrodes so that the maximum grid current is kept at a first threshold larger than or equal to a reference value by adjusting an output of the charge voltage applying circuit.

Abstract: An image forming apparatus includes: a first image forming unit for a monochrome printing including a first photosensitive member for black, a first charging member and a first collection member; a second image forming unit for a multi-color printing including a second photosensitive member for a color, a second charging member and a second collection member; and a control device configured to, at the color printing mode, apply a first charging bias to the second charging member and apply a first bias having a reverse polarity to a charged polarity of developer to the first and second collection members, and at the monochrome printing mode, apply a second charging bias to the second charging member, apply a second bias having the reverse polarity to the first collection member and apply a third bias to the second collection member.

Abstract: An image-forming apparatus includes a first image-forming portion; a second image-forming portion; an executing portion for executing an operation in a first mode in which an image is formed on a recording material by the first and second image-forming portions or a second mode in which an image is formed by the second image-forming portion; an AC-voltage source; a first DC-voltage source; a second DC-voltage source; and a controller for controlling the first and second DC-voltage sources and the AC-voltage source. In the first mode, application of the AC voltage by the AC-voltage source and the DC voltages by the first and second DC-voltage sources are performed, and in the second mode, application of the DC voltage by the second DC-voltage source is performed, and application of the AC voltage by the AC-voltage source and the DC voltage by the first DC-voltage source are stopped.

Abstract: In an image forming apparatus, a plurality of cartridges each of which includes a photoconductor and a charger configured to charge the photoconductor is detachably installable in a main body housing. Chargers are connected in parallel to a voltage application unit configured to apply a voltage to the chargers. A cartridge installation determination unit is configured to determine whether or not each of the cartridges is installed. Control over the voltage application unit exercised by a controller includes a constant-voltage control and a constant-current control. The controller is configured to execute the constant-voltage control upon startup of an initial operation for preparation of printing and to switch from the constant-voltage control to the constant-current control if the cartridge installation determination unit determines that all the cartridges are installed.

Abstract: An image forming apparatus includes: a photosensitive member; a scorotron charger; a developing device; a voltage application circuit; a constant-voltage circuit; a first control device; a deboost circuit; and a second control device, wherein the deboost circuit has a circuit configuration in which a resistor and a control transistor are connected in series with each other, and deboosts the grid voltage by a voltage drop of the resistor to generate the developing voltage, and the second control device provides a control signal to the control transistor to control a current flowing in the resistor, thereby controlling the level of the developing voltage.

Abstract: An image forming apparatus capable of suppressing deterioration of a charger although an amount of use of the charger is actually small is provided. For that purpose, the image forming apparatus executes simple control of discharge current control in which at least one charging bias smaller in number than number of kinds of test biases in full control of the discharge current control is applied to the charger after a power source is turned on and before an image formation start signal is inputted, and on the basis of a current detected by the detector when the charging bias is applied, selects one from a plurality of modes including a first mode in which a charging bias is set by executing the full control of the discharge current control and including a second member in which the charging bias determined by full control of discharge current control without executing the full control of the discharge current control.

Abstract: An image forming apparatus includes an image carrier, a charging member, a transfer member, a cleaning member and a control device configured to switch a first mode and a second mode. When executing the second mode, the control device applies a second charging bias having the same polarity as a first charging bias and having an absolute value smaller than the first charging bias to the charging member, applies a second transfer bias having the same polarity as a first transfer bias and having an absolute value smaller than the first transfer bias to the transfer member, and applies a second cleaning bias having the same polarity as the charged polarity of the toner to the cleaning member and sets a potential difference between a surface potential of the image carrier and the second cleaning bias within a predetermined range.

Abstract: An image forming apparatus includes a latent image carrier, a charging device, a latent image forming device, a developing device, a transfer device, a toner amount detector, and a control circuit to execute an imaging condition determination process. The control circuit obtains a linear approximation formula of a developing potential and an amount of toner according to an exposure potential of the patch pattern and a detected amount of toner to calculate a developing gamma and a developing start voltage according to a gradient of the linear approximation formula, determines target charging potential, exposure potential and developing bias according to the developing gamma and the developing start voltage, determines an amount of a background potential to be corrected according to a difference between the developing start voltage and a target developing start voltage obtained according to environmental information, and corrects the target charging potential.

Abstract: An image forming apparatus includes an image bearing member that bears a developer image, a transfer apparatus that transfers the developer image, a charge apparatus, an exposure apparatus that exposes the surface of the image bearing member with light to form a latent image, and a developing apparatus that collects and supplies the developer to the latent image to form the developer image, in which an image formation area is divided into an image part and a non-image part where the developer image is not formed, the exposure apparatus exposes the non-image part with light at an exposure amount lower than an exposure amount with respect to the image part, and the charging apparatus charges the image bearing member and the exposure apparatus exposes the image part and the non-image part with light in a state in which the developer remains on the image bearing member.

Abstract: A mode in which a toner image formed on an intermediate transfer belt passes through a primary transfer portion without a toner image being transferred from a photosensitive drum onto the intermediate transfer belt is provided. In the mode, an area of the photosensitive drum that passes through the primary transfer portion while the toner image is passing through the primary transfer portion is defined as a first area. When the first area passes through a charging position, a charging bias is adjusted so that the occurrence of an image defect is prevented.

Abstract: A reference value of an electric current flowing through each charging member is determined and recorded in a memory unit at a predetermined time by a reference value recording unit. A voltage application unit is caused to start applying a voltage to the charging members upon startup of an image forming apparatus, and a measurement value of an electric current flowing through each charging member is determined by a measurement unit. A charging member of which the measurement value is such that an absolute value of a difference between the reference value and the measurement value is not smaller than a predetermined value is marked by a determination unit. If there is at least one marked charging member and at least one not-marked charging member, a notification produced by a messaging unit is given through a notification unit.

Abstract: A PWM generating unit may include a base duty setting register configured to store a base duty value that is set thereto, and a PWM generator to obtain a corrected duty value by correcting the base duty value based on first correction data and second correction data, and to generate a PWM signal according to the corrected duty value. The first correction data may be computed from a rotation period of a first rotational body, and the second correction data may be computed from a rotation period of a second rotational body.

Abstract: An image forming apparatus has a photoconductive member and a cleaning member arranged to face the photoconductive member at a cleaning position and configured be applied with a cleaning bias to collect the developing agent residual on the photoconductive member after the developed image is transferred. A controller of the image forming apparatus controls a transferring bias so that a transferring current representing a current flowing between the photoconductive member and a transferring member is controlled to become a target current value. Further, the controller calculates a cleaning position potential representing a surface potential of the photoconductive member at the facing position based on the transferring current and a charge potential representing a surface potential of the photoconductive member immediately after charged by the charging device, and controls the cleaning bias based on the cleaning position potential as calculated.

Abstract: An image forming apparatus includes a rotatable photosensitive member, and a charging member for electrically charging the photosensitive member in contact or proximity to the photosensitive member. The charging member forms an upstream gap and a downstream gap between the photosensitive member and itself. In addition, a power source applies a DC voltage to the charging member, an irradiation unit irradiates with light a surface of the photosensitive member in the upstream gap, and a controller controls the irradiation of the light by the irradiation unit. The photosensitive member is movable at a first speed and a second speed slower than the first speed, and wherein the irradiation of the light is effected when the photosensitive member is moved at the first speed to effect image formation, and is not effected when the photosensitive member is moved at the second speed to effect the image formation.

Abstract: An image forming apparatus, includes: at least one photosensitive element; a plurality of chargers configured to charge the at least one photosensitive element; a voltage applying circuit commonly connected to the plurality of chargers and configured to apply a voltage to the plurality of chargers; a current detecting unit configured to detect a current sum of current that flows to the plurality of chargers from the voltage applying circuit; and a control device configured to control the voltage applying circuit so that the current sum detected by the current detecting unit becomes equal to or larger than a reference value.

Abstract: An image forming apparatus has an image carrying body, a first electrically conductive member, a bias application device, and a controller. The first electrically conductive member makes contact with the photosensitive layer of the image carrying body The bias application device applies a bias containing an AC bias to the first electrically conductive member. The controller controls the bias application device. The image forming apparatus can execute, while no image formation is being performed, a temperature raising mode in which, with the first electrically conductive member in contact with the image carrying body outside the image formation region, an AC bias having a peak-to-peak value twice as high as the discharge start voltage between the first electrically conductive member and the image carrying body is applied to the first electrically conductive member to raise the temperature of the surface of the image carrying body.

Abstract: An image forming apparatus includes an image bearing member, a first conductive member, a bias application device, and a control portion, and performs image formation on a surface of the image bearing member while making the image bearing member rotate. The image forming apparatus is capable of executing a heating-up mode in which, at the time of non-image formation, in a state where the image bearing member is made to rotate at a velocity lower than that used at the time of image formation, an alternating current bias having a frequency higher than that used at the time of image formation and a peak-to-peak value twice or more as large as a discharge start voltage between the first conductive member and the image bearing member is applied to the first conductive member to cause a surface of the image bearing member to be heated up.

Abstract: An image forming apparatus having; image supporting members provided for a plurality of colors; chargers to be impressed with charging biases to charge the respective image supporting members; developing devices to be impressed with developing biases to develop latent images formed on the image supporting members; a charging bias power supply, including high-voltage DC power supply circuits and an AC power supply circuit, for applying the charging biases, which are generated by superposition of direct-current voltages and an alternate-current voltage, to the chargers; and a control circuit that performs stop processing to stop applications of the charging biases and the developing biases.

Abstract: An image forming apparatus includes a photosensitive member, a charging device for electrically charging the photosensitive member, an electrostatic image forming portion for forming an electrostatic image on the photosensitive member, and a developing device including a toner carrying member and a screw. In addition, a charging power source applies a charge potential to the charging device, a developing power source applies a developing potential to the developing device, a transfer device transfers a toner image formed on the photosensitive member, and an exposure device electrically discharges a surface of the photosensitive member by exposing it to light.

Abstract: An image forming apparatus and a control method thereof are provided that determine a final contrast potential taking into consideration not only the relationship between the contrast potential of an electrostatic latent image and the density value of a developed image but also a toner charge amount for developing the electrostatic latent image. To accomplish this, the image forming apparatus of the present invention predicts, in advance, the contrast potential of the electrostatic latent image and the density of the toner image at the contrast potential for a predetermined toner charge amount. Furthermore, the image forming apparatus forms an image by adjusting the relationship between the contrast potential and density measured in advance based on a current toner charge amount and a saturation toner charge amount when forming the image.

Abstract: An image forming apparatus includes a charging bias output device, a developing bias output device, a transfer bias output device, and a controller. The controller controls the transfer bias output device to supply a transfer bias from a time at which a first position of a photosensitive member arrives at a transfer position after the charging bias output device starts supplying a charging bias. An initial value of the transfer bias is controlled to be smaller than a normal set value for a predetermined time period (Tc) which is a time after the transfer bias starts to be supplied and within a time corresponding to a rise time (Ta) during which a surface potential of the photosensitive member reaches a predetermined potential after the charging bias starts to be output. The first position of the photosensitive member is a position at which the charging device start charging the photosensitive member.

Abstract: An image forming apparatus includes a rotatable image bearing member; a first charging member for electrically charging the image bearing member; a second charging member, provided downstream of the first charging member with respect to a rotational direction of the image bearing member, for electrically charging the image bearing member; an applying device for applying a voltage to the first charging member and the second charging member; a detecting device for a DC current passing through the second charging member; and a controller for controlling, when an AC voltage and a DC voltage are applied to the second charging member while a DC voltage is applied to the first charging member, the DC voltage applied to the second charging member so that an absolute value of the DC current detected by the detecting device is within a predetermined range.

Abstract: An image forming apparatus includes an image bearing member to bear a toner image, a transfer device to transfer the toner image onto a recording medium, and a moving device controller to control a moving device that moves the transfer device such that the moving device moves the transfer device to contact the image bearing member during transfer of the toner image on the image bearing member to the recording medium; separates the transfer device from the image bearing member as a toner patch on the image bearing member passes through the transfer area; and maintains the transfer device in contact with the image bearing member from a preceding transfer of a toner image to a succeeding transfer of a toner image during continuous printing, as at least one of areas between successive toner images on the image bearing member without the toner patch passes through the transfer area.

Abstract: An image forming apparatus includes photosensitive drums, electrostatic latent image forming units, developing sleeves, patch detection sensors which detect image densities of the toner images formed by the electrostatic latent image forming units, and toner replenishment units which replenish the developing sleeves with the toner based on the detection results of the patch detection sensors. Further, controllers are provided to control the rotation speeds of the developing sleeves at the time of forming the reference toner image to be higher than the rotation speeds of the developing sleeves at the time of forming a normal image.

Abstract: An image forming apparatus includes photosensitive drums; drum charging members, an AC voltage source for outputting an AC voltage commonly to at least two of the charging members; AC voltage control devices for the charging members; variable resistors connected between the AC voltage source and the at least two charging members, respectively; a use situation detecting unit for detecting use situations of the drums, respectively; and an adjusting unit for adjusting electric resistances of the variable resistors, respectively. The adjusting unit adjusts the electric resistances of the resistors in accordance with the detection results of the use situation detecting unit such that the discharge currents applied to the at least two charging members are within predetermined ranges, respectively.

Abstract: An image forming apparatus includes: including: an image forming unit; and a controller. The image forming unit includes: an image bearing member; a charging member; a transfer member; and a cleaning member. The controller selectively applies first and second transfer biases to the transfer member. A first transfer current flows between the image bearing member and the transfer member upon application of the first transfer bias. A second transfer current flows therebetween upon application of the second transfer bias. The controller selectively applies first and second charging biases to the charging member. The image bearing member has a first surface potential upon application of the first charging bias, and a second surface potential upon application of the second charging bias. The controller applies the first charging bias when applying the first transfer bias, and applies the second charging bias when applying the second transfer bias.

Abstract: An image forming apparatus including a rotatable photosensitive member, a first charging member for electrically charging the photosensitive member at a first charging portion by applying thereto a first DC voltage, and a second charging member, provided downstream of the first charging portion with respect to a rotational direction of the photosensitive member, for electrically charging the photosensitive member charged by the first charging member, at a second charging portion by applying thereto an oscillating voltage in the form of a second DC voltage superposed with an AC voltage.

Abstract: Certain embodiments provide an image forming apparatus including: an image carrier; a latent image forming unit; a developing unit; a fixing unit; a toner cartridge; a battery in the toner cartridge; a temperature sensor in the toner cartridge driven by the battery; a first controller which causes the temperature sensor to measure an ambient temperature periodically in the toner cartridge and be supplied with power from the battery; a recording medium which is provided in the toner cartridge and records a result of measurement by the temperature sensor in timing controlled by the first controller; and a second controller which reads out information recorded in the recording medium, and changes an operating condition of the latent image forming unit, the developing unit and the fixing unit according to a state of preservation of the supply of toner, based on the information.

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 plurality of photoconductor drums; a plurality of exposure members; a drum supporting member having a pair of side walls disposed opposite to each other in an axial direction of the photoconductor drum and configured to support the photoconductor drums and the exposure members between the side walls; a belt disposed below and opposite to the photoconductor drums; a pair of guide members configured to support the drum supporting member while allowing rectilinear movement of the drum supporting member; and a main body circuit board provided in the main body and connected to the exposure members via a cable. The main body circuit board is arranged below the belt, and the cable passes a region outside the belt in the axial direction of the photoconductor drum and is connected to the main body circuit board.

Abstract: An image forming apparatus includes a latent image forming unit that forms a latent image on an image bearing member, a developing unit that develops the latent image to obtain a developer image, and a transfer unit that transfers the developer image to a recording medium. A first supply unit supplies a voltage to a charging unit and the transfer unit, with the first supply unit including a transformer, and a second supply unit supplies a voltage to the transfer unit, with the second supply unit including a transformer and supplying a voltage supplied opposite in polarity to the voltage supplied from the first supply unit. In addition, a detection unit detects current flowing through the transfer unit, and a control unit is configured to control power supply.

Abstract: An image forming apparatus includes: a first photosensitive drum for a monochrome printing mode; second and third photosensitive drums for a color printing mode; a moving unit moving a medium from the first photosensitive drum via the second photosensitive drum to the third photosensitive drum; charger devices for charging the photosensitive drums; transfer devices for transferring developer images on the photosensitive drums to the medium; and a control unit configured to control charging biases of the charger devices and transfer biases of the transfer devices. The control unit executes, in the monochrome printing mode, an energy saving control in which an absolute value of a charging bias applied to the charger device for the third photosensitive drum is smaller than an absolute value of a charging bias applied to the charger device corresponding to the second photosensitive drum.

Abstract: An image forming apparatus includes a plurality of photosensitive drums, and a controller for executing, when an absolute value of a set point of a charged potential is not higher than a predetermined threshold, an operation in a first mode in which charging bias voltages and transfer biases are applied to image regions of the drums, and the charging bias voltages are further applied, and thereafter, image exposures are carried out by exposure members, respectively, and for executing, when the absolute value of the set point of the charged potential is higher than the predetermined threshold, an operation in a second mode in which timings of start of applications of the transfer bias voltages to the transfer members are delayed as compared with those in the first mode, respectively.

Abstract: A method of charging a photoreceptor (3) includes a first corona charging unit (2) a first corona electrode (4), a first shell electrode (6), and a first high voltage power supply (22). The shell electrode is connected through a resistor to ground and the high voltage power supply is connected to the first corona electrode. A second corona charging unit (10) has a second corona electrode (12), and a first grid electrode (14) connected to a second shell electrode (16). A first corona current from the first high voltage power supply to the first corona electrode and a return current from the first shell electrode to ground is sensed and a voltage on the first high voltage power supply is adjusted to maintain a constant difference. The first corona charging unit charges the photoreceptor to at least 63% of the desired voltage.

Abstract: An image forming apparatus including: a photosensitive member; a charging device; an exposure device; and a developer carrying member, wherein, when it is assumed that an image forming area, a printing portion and a non-printing portion are an area on the photosensitive member on which an image to be transferred onto a recording material is formed, an area in the image forming area to which the developer adhere and an area in the image forming area to which the developer does not adhere, respectively, the exposure device exposes the printing portion at a first laser power, exposes the non-printing portion at a second laser power smaller than the first laser power, and exposes a non-image forming area on the photosensitive member between two adjacent image forming areas at no laser power or a third laser power smaller than the second laser power.

Abstract: An image forming apparatus includes an exposure device configured to expose image bearing members charged by charging devices to form latent images on the image bearing members, and a control unit configured to, in ether one or both of an image forming unit A and an image forming unit B, adjust an amount of exposure by which the image bearing member is exposed and a charging voltage based on information about the image bearing members of the image forming units A and B. The control unit is configured to make the charging voltage and the amount of exposure in the image forming unit A different from the charging voltage and the amount of exposure in the image forming unit B.

Abstract: An image forming apparatus including: a plurality of image forming stations; and a control portion configured to control an image forming operation, each of the image forming stations includes: an image bearing member configured to form a toner image on a surface thereof; and a charging device configured to charge the image bearing member, wherein the toner images formed on the image bearing members of the image forming stations are sequentially transferred to a transfer incurring member to be superimposed, wherein the control portion sets a voltage applied to the charging device in forming an image in an image forming station which performs the transfer later based on image density information of the toner image transferred to the transfer incurring member by an image forming station which performs the transfer earlier in a sequence of the image forming operations.

Abstract: When printing, an image forming apparatus determines, based on a threshold voltage corresponding to a print speed during printing, whether or not a corona wire of a charger needs to be cleaned. On the basis of whether or not a monitoring voltage corresponding to a current value of a charged bias, which is applied to the corona wire by a charged-bias high-voltage power supply, is equal to or more than a predetermined threshold voltage corresponding to the print speed during printing, the image forming apparatus determines whether or not the corona wire needs to be cleaned.

Abstract: Provided is an apparatus and method for supplying a charge voltage to an organic photoconductor (OPC) drum. The apparatus includes a storage unit for storing first service life information of the OPC drum according to a first supplying method, and second service life information of the OPC drum according to a second supplying method, a sensor unit for measuring information about conditions surrounding the apparatus, a control unit for selecting one of the first and second supplying methods according to the measured information and determining a charge voltage corresponding to the service life information according to the selected method, and a voltage supplying unit using the selected method to supply the determined charge voltage to the OPC drum.

Abstract: An image forming apparatus includes image forming portion, toner-disposal container, conveying portion, driving portion, load detection portion, image formation control portion, and image forming condition adjustment portion. The image forming condition adjustment portion corrects, when image forming condition does not conform to predetermined condition, the image forming condition. In a case where a drive load detected by the load detection portion becomes greater than first threshold value while the conveying portion is driven by the driving portion and the image forming operation is executed, the image formation control portion temporarily stops the image forming operation, and causes the image forming condition adjustment portion to check and correct the image forming condition.

Abstract: An image forming apparatus having a photosensitive member, a charging member that charges the photosensitive member to form a charged surface on a surface of the photosensitive member, an applying unit that applies to the charging member a charging bias composed of a direct voltage superimposed with an alternating voltage, and a toner image forming unit that forms a toner image on the charged surface. A current flowing through the charging member when the charging bias is applied to the charging member is detected by a current detection unit, and currents of different predetermined frequency components are respectively extracted from the detected current by extraction units. Based on the extracted currents, the alternating voltage of the charging bias is adjusted by an adjustment unit.

Abstract: An image forming apparatus including: photosensitive members; charging devices to which a common charging power source applies a charging voltage to charge the photosensitive members; an exposure device configured to expose the photosensitive members; developing devices to form developer images on the photosensitive members; a transfer device to transfer the developer images onto a transfer medium; and a control portion configured to set a lower limit value of the charging voltage for each photosensitive member, apply the charging voltage having a magnitude not less than any lower limit value from the charging power source to the charging devices, control the output of the laser power for each photosensitive member individually, and set, based on the image density of the developer image transferred onto the transfer medium earlier, the lower limit value for a photosensitive member on which a developer image to be transferred onto the transfer medium later is formed.