Abstract: 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.

Abstract: An image forming apparatus includes a rotatable photosensitive member; a charging portion, an exposure portion, a developing member, a transfer unit, a contact and separation portion, a charging voltage applying portion, a detecting portion, and a controller. The controller is capable of executing an operation in an image forming mode and an operation in a detecting mode. The controller carries out control so that a charging current flowing through a charging portion during charging of the photosensitive member in the operation in the detecting mode is lower than a charging current flowing through the charging portion during charging of the photosensitive member in the operation in the image forming mode.

Abstract: An image forming apparatus includes a rotatable photosensitive member, a charging member, an exposing unit to form an electrostatic latent image by exposing the surface of the photosensitive member charged by the charging member to light and, a developing member to develop the electrostatic latent image with toner. A controller controls so that a predetermined charging voltage is charged and the light is emitted by a low light quantity to a first non-print area, which is a non-print area provided in a region including the print area and the first non-print area with respect to a main scanning direction, and controls so that a charging voltage lower than the predetermined voltage is charged and exposure is not performed on a second non-print area, which is provided in a region including only the non-print area with respect to the main scanning direction.

Abstract: An image forming apparatus includes a photosensitive member, a charging member, a charging power source, a developing member, a transfer member, a transfer power source, an acquiring portion, and a controller. The controller controls a charging voltage to be a first charging voltage when an electric resistance value of the transfer member is a first resistance value and to be a second charging voltage not less than the first charging voltage in absolute value when the electric resistance value is a second resistance value lower than the first resistance value, and so that a change amount of the charging voltage when the electric resistance value is changed from the second resistance value to a third resistance value lower than the second resistance value is greater than a change amount of the charging voltage when the electric resistance value is changed from the first resistance value to the second resistance value.

Abstract: An apparatus includes at least one memory and at least one processor functioning to reserve a sheet feeding unit of an image forming apparatus and provide information indicating that the sheet feeding unit is reserved.

Abstract: An image forming apparatus includes a first image forming portion, a second image forming portion, a belt, a charging voltage applying portion, and a transfer voltage applying portion. With respect to a movement direction of a recording material, the first image forming portion is provided upstream of the second image forming portion. In an image forming operation, a potential difference between a first transfer voltage and a potential at a first transfer portion, which is formed on a first image bearing member and does not form the image, is greater than a potential difference between a second transfer voltage and a potential at a second transfer portion, which is formed on a second image bearing member and does not form an image.

Abstract: An image forming apparatus includes an image bearing member, a developing member, a controller configured to carry out switching control between a first state in which the developing member is caused to act on the image bearing member and a second state in which the developing member is not caused to act on the image bearing member, a transfer member, and a detector configured to read density information of the recording material. The controller detects a fog density on the basis of a difference in density information between a fog non-occurrence region of a non-image region of the recording material in the second state and a fog occurable region of the non-image region of the recording material in the first state.

Abstract: An image forming apparatus includes a photosensitive member, a charging member configured to charge a surface of the photosensitive member, a power supply configured to apply the DC voltage to the charging member, a current detection unit configured to detect a current value flowing from the charging member to the photosensitive member, a calculation unit configured to calculate a first voltage value based on applied voltages with different voltage values and detected current values, and a setting unit configured to set a second voltage value to be applied to the charging member during forming of an image. The setting unit sets the second voltage value by adding the first voltage value, a target voltage value, and a correction value corresponding to a peripheral speed of the photosensitive member during forming of the image.

Abstract: An apparatus comprising a first control unit that executes density correction processing on image data and generates an image signal, an image forming unit that forms an image on a recording medium on the basis of the image signal, and a second control unit that controls the image forming unit. The first control unit includes a specifying unit that transmits specifying information relating to the density correction processing to the second control unit. The second control unit includes an acquisition unit that acquires a parameter relating to the image forming apparatus, and an estimation unit that estimates a plurality of image densities corresponding to tone levels identified by the specifying information transmitted from the first control unit on the basis of the parameter acquired by the acquisition unit and transmits the plurality of image densities to the first control unit.

Abstract: An image forming apparatus includes a first image forming portion, a second image forming portion, a belt, a charging voltage applying portion, and a transfer voltage applying portion. With respect to a movement direction of a recording material, the first image forming portion is provided upstream of the second image forming portion. In an image forming operation, a potential difference between a first transfer voltage and a potential at a first transfer portion, which is formed on a first image bearing member and does not form the image, is greater than a potential difference between a second transfer voltage and a potential at a second transfer portion, which is formed on a second image bearing member and does not form an image.

Abstract: An example image forming apparatus includes a photoconductor, a driving unit to rotate the photoconductor, a charging device, a power unit to apply a charging voltage to the charging device, a current measuring unit to measure a current flowing through the charging device and the photoconductor, and a processor. The processor may determine a charging voltage by controlling the driving unit to rotate the photoconductor at a plurality of different rotational speeds, controlling the power unit to apply at least one test charging voltage to the charging device at each of the plurality of different rotational speeds, and determining a charging voltage based on a current measured at each of the at least one test charging voltage through the current measuring unit, and control the charging voltage according to states of the photoconductor and the charging device, based on a result of the performing of the charging voltage determination process.

Abstract: A charge removing unit emits light onto a surface of an image bearing member for removing charge on the surface. The charge removing unit includes a light source configured to emit the light, and a light guide that is configured to guide the light to irradiate the surface of the image bearing member with the light and has a cylindrical shape extending in an axial direction of the image bearing member. At both ends in a longitudinal direction of the light guide, one end portion and another end portion are respectively provided. The light is introduced to the one end portion. The another end portion includes an inclined surface inclining in a direction from the one end portion to the another end portion, toward a central axis of a circumference of the light guide.

Abstract: An image forming apparatus includes a photosensitive drum, a transfer unit, a voltage supply circuit, and a controller. The transfer unit is configured to transfer developer onto a printing medium from the photosensitive drum. The voltage supply circuit is configured to supply voltage to the transfer unit. The controller is electrically connected to the voltage supply circuit. The controller is configured to: calculate a cumulative voltage value, the cumulative voltage value being a total of supplied voltage to the transfer unit from the voltage supply circuit after using the transfer unit is started; and determine how long a lifetime of the transfer unit remains based on the calculated cumulative voltage value.

Abstract: An image forming apparatus includes: a development device which develops an electrostatic latent image formed on a photosensitive drum into a toner image; a charger which charges the photosensitive drum; a development power supply which applies a bias voltage to the development device; a calculating section which calculates a surface potential of the photosensitive drum based on a development current flowing in the development device; and an estimating section which estimates a fogging toner amount. The fogging toner amount is an amount of toner moved due to fogging. When the fogging toner amount estimated by the estimating section is less than a prescribed threshold, the calculating section calculates a value of the bias voltage at which the development current stops flowing as the surface potential.

Abstract: An image forming apparatus includes an image carrier, a charger, an exposure device, a development device and a pressing mechanism. When a developer carrier and the image carrier are rotated in a state where a film is held in a development nip area and then a pulling force of the film is measured, a maximum value MAX, a minimum value MIN, and an average value X of the pulling force satisfy the expressions (1) and (2). When a development voltage applied to the developer carrier is set to Vdc, the surface potential of the image carrier is set to V0, and the surface potential of the image carrier after exposure is set to VL, the expressions (3) and (4) are satisfied. X?MAX?1.5X??(1), 0.5X?MIN?X??(2), V0?Vdc?2(Vdc?VL)??(3) and Vdc?VL?100??(4).

Abstract: An image forming apparatus includes an image carrier, an exposure device, a developing device, a primary transfer device, a secondary transfer device, and a control unit. The exposure device exposes the image carrier to form an electrostatic latent image on the image carrier. The developing device forms a toner image by developing the electrostatic latent image using toner. The primary transfer device primarily transfers the toner image to a transfer body. The secondary transfer device applies a transfer bias to secondarily transfer the toner image to a recording medium. The control unit applies a cleaning bias to the secondary transfer device to remove residual toner after the secondary transfer. When the control unit determines that the toner image based on the exposed electrostatic latent image is not secondarily transferred at a predetermined timing, the first cleaning processing is performed until the subsequent processing is started.

Abstract: An image forming device includes a first control circuit, a second control circuit, a high-voltage substrate, and a polygon motor. The high-voltage substrate applies a voltage with a frequency of an application signal to a toner image forming member. The first control circuit generates a first clock signal, counts the number of the first clock signal, and generates a motor drive signal. The first control circuit counts the first clock signal and generates an adjustment signal. The second control circuit counts the number of actual measurements which is a count value of the second clock signal during one cycle of the adjustment signal. The second control circuit counts the second clock signal by a set value. A setting circuit in the second control circuit sets the set value in accordance with the difference between the number of actual measurements and a theoretical number of times.

Abstract: In some examples, a controller can generate operational profiles of printing device components by determining an electrical measurement of a component of a printing device, generate an operational profile of the electrical measurement, compare the operational profile against a baseline operational profile the component, and generate an alert based on the comparison.

Abstract: An image forming apparatus includes a photoconductor, a charger, a charge remover, and control circuitry. The charger is configured to charge the photoconductor. The charge remover is configured to remove charge from a surface of the photoconductor by light and electric discharge. The control circuitry is configured to: estimate a surface potential that the photoconductor has after the photoconductor is charged by the charger, based on a characteristic value of the photoconductor and a value of a current flowing through the charger after the charge remover removes charge from the photoconductor; and control a charging bias applied to the charger, based on the surface potential estimated.

Abstract: An image forming apparatus includes: a photoconductor; a charging roller; an exposure device; a developing device that is provided on a downstream side of the charging roller in a rotation direction of the photoconductor, and forms a toner image by supplying toner to a latent image; a cleaning blade that is provided between a transfer part of a surface of the photoconductor located on a downstream side of the developing device in the rotation direction of the photoconductor and the charging roller, and removes residual toner adhering to a part of the surface of the photoconductor on a downstream side of the transfer part; a lubricant supplier that supplies a lubricant to the surface of the photoconductor; and a voltage controller that controls a charging voltage to be applied to the charging roller.

Abstract: In an image forming apparatus, an image bearing member and a cleaning member are in contact with each other to form a collection nip. A conveyance member is in contact with the image bearing member to form a conveyance nip. The controller executes a maintenance mode including a toner supply process, an output process, and a sheet feeding process. The toner supply process supplies at least part of the image bearing member with a predetermined amount of toner. The output process controls a circuit to output the cleaning voltage to the cleaning member. The sheet feeding process controls the feeding member to start feeding the sheet so that the sheet passes the conveyance nip in coincidence with the at least part of the image bearing member passing the conveyance nip after the at least part of the image bearing member has once passed the collection nip.

Abstract: A charging device includes: a first charging unit that contacts a unit to be charged to charge the unit to be charged to a first charging potential; and a second charging unit that contacts the unit to be charged on a side upstream of the first charging unit in a direction of movement of the unit to be charged to charge the unit to be charged to a second charging potential that is lower than the first charging potential.

Abstract: In an image forming apparatus, a bias controller varies one, while keeping the other fixed, of a charging alternating-current frequency, which is the frequency of the charging alternating-current voltage, and a developing alternating-current frequency, which is the frequency of the developing alternating-current voltage. Specifically, in a case where interference fringes appear in a developed image due to interference between the charging and developing alternating-current frequencies, when the recognizable minimum pitch of the interference fringes is A1 (mm), the width of the variation region of the other frequency is B1 (Hz), the rotation speed of an image carrying member is C1 (mm/sec), and the variation speed of the other frequency in the variation region is D1 (Hz/sec), the bias controller varies the other frequency at a variation speed D1 that fulfills |D1|>B1/(A1/C1).

Abstract: An image forming apparatus includes: a plurality of image holding units that include first and second image holding units and on which toner images are formed through developing while the image holding units rotate; a plurality of developing units that respectively face the plurality of image holding units and develop an electrostatic latent image on each of the plurality of image holding units with toner under a developing bias voltage applied to each developing unit; a power supply unit that applies a developing bias voltage to the plurality of developing units, and is common to the plurality of image holding units; an intermediate transfer unit that receives transfer of a toner image from the plurality of image holding units and transfers the toner image to a transfer receiver while circulating in a circulation path including a moving path along the plurality of image holding units, the intermediate transfer unit having first and second modes, wherein in the first mode, the intermediate transfer unit recei

Abstract: In an image forming apparatus of a direct transfer system, when in a region where a transfer nip portion of a photosensitive drum is formed, a region in which the toner image can be formed is defined as a first region, and a region where the recording medium does not pass while the recording medium is conveyed by the transfer nip portion is defined as a second region, in forming the toner image on the recording medium, the photosensitive drum enters the transfer nip portion in a state where the second region of the photosensitive drum includes a region in which an absolute value of a surface potential is smaller than an absolute value of a surface potential of a region in which the toner image is not formed in the first region.

Abstract: An image forming apparatus includes a control unit configured to execute a stop mode in which, after image forming operation is stopped, a developer bearing member is rotated for a predetermined time with a potential difference between a film forming electrode and a developer bearing member set to zero or smaller than that during image formation, and thereafter, the rotation of the developer bearing member is stopped.

Abstract: An image forming apparatus includes an image carrier that carries an image to be transferred onto a recording medium, a charging member in contact with the image carrier, the charging member that charges the image carrier, an erase unit that erases charge on the image carrier, a current detector that detects a current flowing to the charging member; a forming unit that forms a charged region on a surface of the image carrier, and forms an erased region on the surface of the image carrier using the erase unit, and a state acquisition unit that acquires a deterioration state of the charging member based on (i) a first current flowing in response to applying a voltage from the charging member to the erased region and (ii) a second current flowing in response to applying a voltage from the charging member to the charged region.

Abstract: An image forming apparatus includes a photosensitive member unit, a charging member, an exposing unit, a developing unit, an information storage portion, and a setting portion. The information storage portion stores information on an attenuation amount of a surface potential of the photosensitive member by which the surface potential is attenuating until the photosensitive member rotates from a contact position of the photosensitive member to a development position of the photosensitive member. If the attenuation amount is a first attenuation amount, the setting portion sets an applying voltage to be applied to the charging member at the time of image formation to a first voltage. If the attenuation amount is a second attenuation amount greater than the first attenuation amount, the setting portion sets an applying voltage to be applied to the charging member at the time of image formation to a second voltage higher than the first voltage.

Abstract: An image forming apparatus includes a connecting device to which a charging apparatus is connected, an image forming device, an operating device, and a control device. The control device functions as an operation accepter, a controller, a charging processor, and a notifier. The notifier performs a processing for giving a first notice; the first notice is for asking a user whether or not to donate all of or part of a remaining money which is remaining, posterior to charging for a print job, in an inserted amount of money. After the notifier has performed the processing for giving the first notice, when the operation accepter accepts an instruction of execution of the donation, the charging processor performs a charging processing by subtracting, from the inserted amount of money, a charging amount for the print job and an amount of donation indicated by the instruction of execution of the donation.

Abstract: A color imaging device includes a plurality of developer rolls with a common operating point, such as a common operating voltage. To determine the operating point, an acceptable range of color density is determined for each toner, the range being lighter and darker than an optimum color density for that toner. A search range is devised such that values within the range are examined relative to deviations from the optimum color density per each toner. The common operating point is selected as that having the lowest deviation per all toners. Also, if the common operating point corresponds to a color density darker than the acceptable range of color density for any toner, additional halftoning occurs compared to traditional halftoning, such as for continuous tones or solids. In this way, four color developer rolls can be operated from a single power supply, yet still provide acceptable color images.

Abstract: An image forming apparatus includes a photosensitive member, a first charging roller, a first cleaning member, a second charging roller, and a second cleaning member. The following relationship is satisfied: (X×L0+L1+L2)?(Y×L3+L4)?0 where L0 represents a length of a whole circumference of the first charging roller, L1 represents a length between a first contact area and a first contact position of the first charging roller and the photosensitive member, L3 represents a length of a whole circumference of the second charging roller, L4 represents a length between a second contact area and a second contact position, L2 represents a length between the first contact position and the second contact position, X represents an integer in a range of 0?X?40, and Y represents an integer in a range of 0?Y?40.

Abstract: In an image forming apparatus, a charging process of a photosensitive member is performed by forming a combined surface potential Vd(U+L) by superimposing, on a first charge potential Vd(U) formed on a surface of the photosensitive member by a first corona charger, a second charge potential Vd(L) provided by a second corona charger. The apparatus includes a controller for executing an adjusting operation in which a superimposition start voltage Vg(L)A, which is the second voltage Vg(L) at which formation of the combined surface potential Vd(U+L) is started, is acquired by changing the second voltage Vg(L) applied to a grid electrode of the second corona charger in a state that the first charge potential Vd(U) is formed on the surface of the photosensitive member and in which setting of the second voltage Vg(L) during the charging process is adjusted on the basis of the superimposition start voltage Vg(L).

Abstract: A color imaging device includes a plurality of developer rolls with a common operating point, such as a common operating voltage. To determine the operating point, an acceptable range of color density is determined for each toner, the range being lighter and darker than an optimum color density for that toner. A search range is devised such that values within the range are examined relative to deviations from the optimum color density per each toner. The common operating point is selected as that having the lowest deviation per all toners. Also, if the common operating point corresponds to a color density darker than the acceptable range of color density for any toner, additional halftoning occurs compared to traditional halftoning, such as for continuous tones or solids. In this way, four color developer rolls can be operated from a single power supply, yet still provide acceptable color images.

Abstract: An image forming apparatus includes an image bearer, a charger, and a power source to apply to the charger a charging bias obtained by superimposing an AC voltage on a DC voltage. The power source includes a peak detection circuit to detect positive and negative peak values of a voltage of an AC component of the charging bias; and control circuitry to compare an absolute value of the positive peak value with an absolute value of the negative peak value, correct the AC voltage to cause the absolute value of the negative peak value to coincide with the absolute value of the positive peak value when the absolute value of the positive peak value is smaller, and to cause the absolute value of the positive peak value to coincide with the absolute value of the negative peak value when the absolute value of the negative peak value is smaller.

Abstract: An imaging device includes a photoconductive drum charged by a charge roll and opposed by a transfer roll to transfer an image from the drum. The drum becomes biased to a negative voltage by setting charges of negative voltage on both the charge roll and transfer roll. A controller switches the bias of the transfer roll to a positive voltage from the negative voltage and a delta or difference in a charge of the drum is determined from before and after the switching. Based on the delta, the voltage on the charge roll is boosted by a boost voltage to improve the charge on the drum. In this way, deteriorating or defective charge rolls can be still used to charge the drum to a proper voltage for imaging. Techniques for determining the delta, the boost and the magnitude of voltage charges are further embodiments.

Abstract: 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.

Abstract: An image forming apparatus includes a movable photosensitive member, first and second corona chargers, an adjusting mechanism, a developing device, a detecting member configured to detect a surface potential of the photosensitive member at a plurality of positions with respect to the widthwise direction of the photosensitive member, an input portion, and a display portion. In accordance with input of an instruction to the input portion, the detecting portion detects at least two surface potentials of three surface potentials including the surface potential of the photosensitive member after being charged by the first and second corona chargers, the surface potential of the photosensitive member after being charged by the first corona charger, and the surface potential of the photosensitive member after being charged by the second corona charger. A detection result of the detecting member is displayed at the display portion.

Abstract: An image forming apparatus including: a charging member configured to charge a photosensitive member at a charging portion by a charging voltage in which an alternate-current voltage is superimposed on a direct-current voltage; a transfer member configured to transfer a toner image formed on the photosensitive member to a recording material at a transfer portion; and a controller configured to control the charging voltage, a predetermined area of the photosensitive member passing through the transfer portion during a trailing edge of the recording material passing through the transfer portion, wherein the controller controls a value of a peak-to-peak voltage of the alternate-current voltage when the predetermined area passes through the charging portion to be larger than a value of a peak-to-peak voltage when an area that becomes the image area other than the predetermined area passes through the charging portion.

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

Abstract: A fixing device includes a rotatable fixing member, a rotatable pressuring member and an electric charge supplying device. The fixing member contacts a recording medium having a toner image and heats the recording medium. The pressuring member pressures the recording medium between the fixing member and the pressuring member. The electric charge supplying device electrically discharges electric charges with same polarity as toner and supplies the electric charges to the fixing member. An output current value electrically discharged by the electric charge supplying device is adjusted on the basis of a toner charged amount of the toner image. When the toner charged amount is equal to or more than a threshold value, the output current value is set to a normal current value. When the toner charged amount is less than the threshold value, the output current value is set to a current value higher than the normal current value.

Abstract: An image forming apparatus includes an image bearing member; a toner image forming device; an image transferring device; a transfer bias applying device; an image fixing device; a sensor for detecting light reflected by the toner image fixed on the sheet; a controller for controlling a leading portion bias applied to the leading portion of the sheet with respect to a sheet feeding direction and a central portion bias applied to the central area of the sheet. The controller forms first and second test images on the leading and central portions, respectively, and sets conditions of the leading and central portion biases on the basis of an output of the sensor, in correlation with a kind of the sheet. A toner deposition amount per unit area of the first test image is smaller than that of the second test image.

Abstract: An image forming apparatus includes a rotatable image carrier that carries an image, a charging unit having a rotatable charging member that charges the image carrier, a developing unit that supplies a developer including at least toner to the charged image carrier, and a cleaning unit having a cleaning member that cleans a surface of the image carrier. At least when the image forming apparatus is not performing image formation, the charging member on which the toner from the image carrier is carried is caused to rotate at a peripheral velocity different from a peripheral velocity at which the image carrier rotates.

Abstract: In one example, an electrostatic printer includes: a photoconductor member; a charging unit to charge the photoconductor member to a charged voltage; an imaging unit to generate a latent electrostatic image on the photoconductor member by discharging areas of the charged photoconductor member; a developer unit to develop a toner image on the photoconductor member using a developer voltage; and a controller to change the developer voltage and to change the charged voltage dependent on the change of the developer voltage to keep the difference between the developer voltage and the charged voltage constant.

Abstract: An image forming apparatus includes a photosensitive member, a charging roller, a voltage source, a current detecting member, and a setting portion configured to set the DC voltage applied to the charging roller in an image forming period on the basis of a detection result of the detecting member when a DC voltage less than a discharge start voltage is applied from the voltage source to the charging roller in a period other than the image forming period, wherein the setting portion sets the DC voltage so that an absolute value of the DC voltage when an absolute value of the detected current is a first value is larger than an absolute value of the DC voltage when the absolute value of the detected current is a second value smaller than the first value.

Abstract: At least one partial measurement region is set in the longitudinal direction in a printable region of a photosensitive drum. After the photosensitive drum has been charged to a constant potential with a charging roller, different potentials are set in the partial measurement region and a region excluding the partial measurement region with a laser scanner, partial discharge information of the partial measurement region is detected by a discharge information detection unit, and a bias voltage in image formation that is applied to the charging roller is corrected on the basis of the value of the partial discharge information.

Abstract: A charging device having contactless transmission of electrical energy in order to supply energy to a wireless hand-held device. An electronic circuit for feeding an inductive energy transmitter is designed to adapt energy fed to the inductive energy transmitter in accordance with energy drawn from the inductive energy transmitter. A hand-held device is designed to interrupt the supply of a load when energy is fed into the hand-held device by means of the inductive energy transmitter.

Abstract: In an image forming apparatus, a control unit performs a control for determining a surface potential A to determine a first voltage to be applied to a charge roller by a charge voltage application circuit so that a surface potential of a photosensitive drum becomes a first potential. The charge voltage application circuit thereafter applies the first voltage to the charge roller to charge the photosensitive drum. In such a state, the control unit performs a second control to determine a light amount of a laser light source, so that the surface potential of the photosensitive drum becomes a second potential. In such a manner, a potential of a photosensitive drum surface is detected with high accuracy. Moreover, a time taken to detect the potential of the photosensitive drum surface is shortened.

Abstract: A high voltage generation apparatus that supplies a DC voltage to a load includes a current detection circuit that detects a DC flowing through the load. The current detection circuit includes an operational amplifier, and the current detection circuit detects the DC flowing through the load, as a voltage generated in a current detection resistor. The high voltage generation apparatus further includes a voltage detection circuit that detects a DC voltage supplied from a rectification circuit to the load. The current detection circuit includes a bypass circuit that causes a current to flow from a connection portion between the voltage detection circuit and a first input terminal of the operational amplifier to an output terminal of the operational amplifier in a case where the detected value of the DC that flows through the load drops below a predetermined value.

Abstract: An image forming apparatus includes an intermediary transfer member, a first image forming portion including a first photosensitive member, a first charging member, a first developing device, a first transfer portion, and a first pre-exposure device, a second image forming portion including a second photosensitive member, a second charging member, a second developing device, a second transfer portion, and a second pre-exposure device, a current detecting portion, and an adjusting portion for adjusting an exposure amount of the first photosensitive member by the first pre-exposure device on the basis of a detection result of the detecting portion in a region on the first photosensitive member having contacted a toner band formed in a maximum amount per unit area on the intermediary transfer member by the second image forming portion in a state in which a transfer current is supplied.

Abstract: An image forming apparatus includes an image-bearing member, which is charged by a charge voltage in which direct and alternating-current voltages are superposed on each other. A toner image is formed on the charged image-bearing member. A current flowing through the charging member is detected when the charge voltage is applied to the charging member. A current, in a frequency band including a discharge current component, is extracted from the detected current. The alternating-current voltage is adjusted based on the current extracted by an extraction unit. Environmental information is acquired. Based on the environmental information acquired by an acquisition unit, a frequency band for extraction performed by the extraction unit is set.