Abstract: An image forming apparatus using a two-component developer includes a sensor mechanism, an image forming mechanism, a toner supply controller, a memory, an estimation mechanism, and a correction mechanism. The sensor mechanism detects a toner density of the developer. The image forming mechanism produces a toner image at one of at least two selectable process linear speeds. The toner supply controller controls a toner amount based on a result by the sensor mechanism. The memory stores data of an external input voltage for adjusting a variation in an output voltage of the sensor mechanism. The estimation mechanism estimates a difference between output voltages of the sensor mechanism before and after a speed selection of the at least two linear speeds is changed. The correction mechanism corrects the output voltage of the sensor mechanism when a speed selection of the at least two selectable process linear speeds is changed.

Abstract: A first container is operable to accommodate a liquid toner, and provided with a window. A reflector is disposed in the first container. A light emitter is operable to emit light to the reflector through the window and the liquid toner. A light receiver is operable to receive the light reflected by the reflector through the liquid toner and the window. A detector is operable to detect a concentration of the liquid toner based on the light received by the light receiver.

Abstract: A developing device for an electrographic printing apparatus provided has stable performance and improved printing quality.

Abstract: Provided are a light-emitting portion 101 having a light-emitting member 104 and a light emergence surface 112a through which light from the light-emitting member 104 emerges, and a light-receiving portion 102 having a light incidence surface 122a through which the light from the light-emitting member 104 enters and a light-receiving member 105 that detects the light entering through the light incidence surface 122a. The light-emitting portion 101 and the light-receiving portion 102 can make relative movement between a measurement position in which the light emergence surface 112a and the light incidence surface 122a make contact with each other and a waiting position in which the light emergence surface 112a is away from the light incidence surface 122a. The light emergence surface 112a is a spherical surface protruding outward, and the light incidence surface 122a is planar in shape.

Abstract: An image forming apparatus includes an image carrying member, a development unit, a first driving unit, a second driving unit, and a cleaning blade. The image carrying member forms a latent image thereon. The development unit develops the latent image formed on the image carrying member. The first driving unit drives the image carrying member. The second driving unit drives the development unit. The cleaning blade, contactable against the image carrying member, removes materials including toner remaining on the image carrying member. When an agent-empty development unit is filled with a developing agent, the second driving unit is activated to start a driving of the development unit, and the first driving unit is activated to start a driving of the image carrying member after starting a developing agent filling operation to the development unit.

Abstract: An image forming apparatus has a developer container containing a developer and a developer carrying member for carrying the developer and adapted to switch an AC voltage to be applied to the developer carrying member. The apparatus includes a detecting member for detecting the amount of developer in the developer container and a processing portion for determining the amount of developer in the developer container according to the value output by the detecting member when the AC voltage is applied to the developer carrying member. The processing portion is adapted to determine the amount of developer by executing a process that corresponds to the operation of switching the AC voltage.

Abstract: An amount of toner consumption accompanying development of an image corresponding to the image data is calculated based on image data, and a corrected consumption amount is calculated by multiplying the calculated amount of toner consumption by a predetermined correction ratio that is less than 1. Further, toner is supplied based on the calculated corrected consumption amount. As a result, it is possible to prevent excessive supply of toner, and to supply toner without time delay.

Abstract: An image forming apparatus includes a latent image carrier, a latent image forming unit, a developing unit, a toner supplier, a toner concentration detector, a prediction calculator, and a toner supply controller. The toner supplier includes a single driving source and supplies toner to a two-component developer at a predetermined supply position by driving a toner supply member with the driving source. The toner concentration detector detects a toner concentration in the developer at a predetermined detection position located upstream of the supply position. The prediction calculator predicts changes in the toner concentration in the developer over time at a prediction position located at the supply position or downstream of the supply position and upstream of a developer feed position to the developer carrier when toner is not supplied, based on a result of the toner concentration detection. The toner supply controller adjusts an amount of the toner supplied based on the prediction.

Abstract: In a method and system for setting toner concentration of a toner particle-carrier particle mixture in a developer station for development of a latent charge image on a carrier, a sensor is arranged in the developer station measuring the toner concentration. Toner feed in the developer station is adjusted. A current consumption value is determined for toner particles. From the toner concentration measured with the sensor and from the toner consumption value, a toner concentration is calculated at a location in the developer station at which the toner is extracted. A calculated toner concentration at the toner extraction location is input as a control variable used to adjust toner feed so that the calculated toner concentration approaches a desired value.

Abstract: An image formation apparatus including a toner cartridge for holding toner, an image supporting unit, on which an electrostatic latent image corresponding to a toner image is formed, a toner development unit for developing the latent image into the toner image with the toner, a detecting unit for detecting toner concentration of the toner image, and a control unit for controlling an amount of toner adhering to the latent image by adjusting a development bias voltage based on an output of the detecting unit. If control by the control unit based on the detection output of the detecting unit is insufficient, and consumption of the toner is out of a predetermined normal range, the control is carried out by estimating one of toner consumption amount and toner recovery amount in a direction that departs from the predetermined normal range.

Abstract: A toner supply device is equipped with a coupling that has a toner supply opening on the side wall, a partition wall provided in this coupling integrally with a specific space provided on the inner wall and a hole larger than a toner supply opening on the side wall. A toner bottle containing toner is provided in the coupling with its cap portion inserted airtight into the partition wall detachably and an opening provided on its cap portion opposing to the hole on the partition wall for replenishing toner to a developing device from this opening through the hole and a toner supply opening.

Abstract: An image forming apparatus is provided which is capable of forming higher-quality images by detecting a toner concentration with higher accuracy to attain appropriate toner supply and image density. A value obtained by adding a correction value based on a temperature, humidity, a print coverage, or the like to a developer concentration adjustment value is set as a control voltage value Vc which is to be inputted to a toner concentration sensor, and an output value of the toner concentration sensor is detected for each of process speeds. A difference between the output value detected and a value at reference process speed is calculated and based on the difference, a correction value is further calculated. Such another calculation of the correction value with use of the output value detected allows for highly accurate correction.

Abstract: The image forming apparatus according to the present invention detects the amount of remaining toner by using (i) the result of calculation carried out by a toner supply amount calculation section based on an accumulated rotational time measurement section in a region where the amount of remaining toner is not less than a predetermined amount and toner supply is stabilized, (ii) the result of calculation carried out by a pixel count section in a region where the amount of remaining toner gets small and the amount of toner supply gets uneven, and (iii) the result of ATC carried out by a toner density control section. As a result, it is possible to exactly detect the amount of remaining toner without providing a special remaining toner detection device.

Abstract: To provide a technology capable of realizing high-accuracy detection of toner density. A developing apparatus includes: a partition plate provided within the developing apparatus for partitioning an interior of the developing apparatus into a plurality of space; plural transport mixers each provided in the space within the developing apparatus partitioned by the partition plate and rotating for stirring and transporting a developer including toner and carrier; a density sensor provided in a transport path of the developer in one space of the plurality of space partitioned by the partition plate for detecting toner density of the stirred and transported developer; and retracting part for retracting an amount of the developer more than a predetermined amount into another space than the space in which the toner density is detected by the density sensor so that the amount of developer is constantly equal to or less than the predetermined amount near a toner density detection position by the density sensor.

Abstract: A control device executes toner concentration control that controls an operation of a developing device such that a value of detection output detected by a concentration detecting device falls within a predetermined range. Moreover, when controlling drive of a first driving device, which drives at least an image carrier, and drive of a second driving device, which drives at least a fuser device, the control device executes operation control that starts the drive of the first driving device before the drive of the second driving device.

Abstract: An image forming apparatus includes: an image carrier on which an electrostatic latent image is to be formed; a rotary development unit having a plurality of developer carriers that carry a developer used for developing the electrostatic latent image, the developer including toner, the plurality of the developer carriers being sequentially moved to a development position opposing to the image carrier, to switch a development color; and a toner concentration detection unit that detects the concentration of toner of the developer carried by one of the developer carriers located at the development position.

Abstract: An image forming apparatus is provided with an apparatus main body having a casing structure and adapted to perform an image forming operation, a window provided on a casing of the apparatus main body for enabling the interior of the apparatus main body to be seen, and an indicator provided in the apparatus main body for displaying specified indication information. The indicator is arranged at such a position as to face the window.

Abstract: A developer cartridge is configured to be detachably mounted in an apparatus main body and to accommodate developer. The developer cartridge includes a drive member and a display portion. The drive member is configured to be driven to move by a driving force when the developer cartridge is mounted in the apparatus main body. The display portion is configured to move together with the drive member. The display portion displays identification information relating to the developer cartridge in an optically readable manner. A detecting portion optically detects the identification information when the display portion is in a first position, and optically detects presence or absence of the developer in the developer cartridge when the display portion is in a second position different from the first position. An information determining portion determines information on the developer cartridge based on the identification information detected by the detecting portion.

Abstract: An image forming apparatus includes devises for performing a detection method which detects an image characteristic of an image formed on an image bearing member; a first control method which controls a toner concentration in a developer, based on a detection result by the detection method, of an image characteristic of a first reference image for a first control for controlling the toner concentration; a second control method which controls an image parameter, different from the toner concentration, thereby controlling an image density, based on a detection result of an image characteristic of a second reference image for a second control, different from the first reference image; and a correction method which receives detection results of both image characteristics of the first and second reference images, and which, based on the detection result of the image characteristic of either of the reference images for the first and second controls, corrects the other control.

Abstract: Systems and methods are provided for using a sensor to determine a charge-to-mass ratio, and a concentration, of a mixture including a first component and a second component. A base resonance frequency of the sensor in an unloaded state is measured. A surface of a vibrating element of the sensor is loaded with the mixture. A first resonance frequency, of the loaded sensor is measured and a mass of the mixture is calculated. A first component is attracted to, and a second component is removed from, the vibrating element of the sensor. A second resonance frequency, and a first charge, of the sensor are measured. The first component is removed and a second charge is measured. A mass and charge of the first component are calculated. Charge to mass ratio, and the concentration, of the first component are then derived from the calculated values.

Abstract: An image forming apparatus includes an image carrying member, a developing unit, an image density detector, a toner concentration detector, a toner concentration controller, and an output adjustment unit. The image carrying member forms a reference latent image pattern. The developing unit develops the reference latent image pattern as a reference image pattern with a two-component developer. The image density detector detects an image density of the reference image pattern. The toner concentration detector detects a toner concentration in the two-component developer. The toner concentration controller controls the toner concentration based on the image density detected by the image density detector. The output adjustment unit adjusts a toner concentration sensing level of the toner concentration detector with a sensor control voltage. The toner concentration is controlled by a target voltage with reference to the image density. The toner concentration range is changed by changing the sensor control voltage.

Abstract: A controller determines the degree of acuteness of the resonant oscillation of a piezoelectric oscillator, based on the developer's fluidity detection data detected by the piezoelectric oscillator. The toner density output data detected by a toner density sensor is modified to a correct value, based on the degree of acuteness, and a supply roller is controlled based on this corrected value so as to implement the necessary toner supply.

Abstract: A digital color copier includes: a toner concentration storage which, as to a multiple number of developer blocks into which the developer that circulates in the developer device is virtually divided across the image forming width, stores the detected toner concentration of each developer block, detected by the toner concentration detector, separately for every developer block; a toner consumption predictor for predicting the first predicted toner consumption of the toner that is expected to be consumed and/or was consumed from the developer of every developer block during the first circulation, based on the developer's speed of conveyance in the developing device and the print processing speed; a toner concentration estimator for estimating, for every developer block, the toner supply point estimate as the toner concentration at the point where toner is supplied, by subtracting the first predicted toner consumption from the associated detected toner concentration and setting up a toner supply target value of

Abstract: Forced supply of toner(s) from toner hopper(s) to developer storage container(s) is executed while interrupting and/or prohibiting image forming operation(s) so as to prevent consumption of toner(s), toner level(s) within toner hopper(s) being determined to be low and low toner level condition(s) being reported to user(s) when temporal change(s) in value(s) detected by toner sensor(s) is/are small.

Abstract: A toner replenishing device of a toner consumption calculating portion calculates a toner consumption using a gray scale value of each pixel in a multiple-value image inputted from an image data input portion. The calculated toner consumption is corrected by a corrected consumption calculating portion, and is then accumulated by a cumulative consumption calculating portion, and thereby a cumulative toner consumption is calculated. A main replenishing amount control portion controls a replenishing roller driving motor so as to replenish a predetermined first replenishing amount of a toner to a developing tank when the cumulative toner consumption reaches a reference consumption or more. Further, an auxiliary replenishing amount control portion controls the replenishing roller driving motor so as to start to replenish a predetermined second replenishing amount of a toner to the developing tank when a toner concentration obtained by a toner concentration obtaining portion reaches less than a start concentration.

Abstract: In an image forming apparatus of a type wherein toner is replenished to a developing unit by turning or rotating a toner bottle, a phenomenon that a toner replenishment amount per turn of the bottle (replenishing rate) is decreased as the toner remaining quantity in the bottle is decreased, is utilized to provide a method and an apparatus for easily and reliably determining a toner near empty state when a number of the turns measured by counting a number of detection of an object to be sensed formed on an outer surface of the toner bottle.

Abstract: A pixel count section calculates a coverage rate corresponding to toner consumption. A control coefficient value setting section determines, based on the coverage rate, a stop threshold value representing reference concentration for toner replenishment and replenishment extension time. A magnetic permeability sensor measures permeability representing toner concentration in a housing portion. A toner concentration control section starts toner replenishment when an output value from the magnetic permeability sensor varies from a value less than a start threshold value to the start threshold value or above, and stops toner replenishment after lapse of replenishment extension time from the time at which an output value varied from a value greater than the stop threshold value to the stop threshold value.

Abstract: A developing device including a developer bearing member configured to configured to bear thereon a developer including a toner and a magnetic carrier to develop an electrostatic image on an image bearing member with the developer; a developer container configured to contain and feed the developer to the developer bearing member; a toner concentration sensor configured to detect a concentration of the toner in the developer in the developer container and output a signal depending on the detected toner concentration; and a characteristic information storage device configured to store a characteristic of the toner concentration sensor, wherein the sensor information storage device is separated from the toner concentration sensor. A process unit including an image bearing member and the developing device. An image forming apparatus including an image bearing member, the developing device and a controller.

Abstract: An image forming apparatus including a latent image bearing member; a developing device configured to develop a latent image on the image bearing member with a two-component developer; a development potential forming device configured to form a development potential; a toner replenishing device configured to supply the toner to the developing device; a toner concentration detecting device configured to detect and output the concentration of the toner in the developer; a toner concentration controlling device configured to compare the toner concentration output with a toner concentration target to control the toner concentration; an information detecting device configured to obtain information to determine the replacement amount of the toner in the developing device in a predetermined period of time; and a development potential correcting device configured to adjust the development potential on the basis of the information obtained by the information detecting device.

Abstract: A power supply control system for a fuser assembly in an electrophotographic apparatus includes a power supply and a fuser assembly. The power supply includes a first electrical path designated for a fuser assembly that operates at a first voltage and a second electrical path designated for a fuser assembly that operates at a second voltage. The fuser assembly is configured to operate at a select one of the first voltage or the second voltage and is connected to the first electrical path if the fuser assembly operates at the first voltage, and the fuser assembly is connected to the second electrical path if the fuser assembly operates at the second voltage. The first and second electrical paths allow different device features including power limiting devices such as fuses, switches, relays, etc., to be placed in each path.

Abstract: A developer agitation screw is provided with a blade to gather developer onto the sensor surface of a toner concentration sensor. A toner concentration control unit detects the maximum value of the output of the toner concentration sensor within each predetermined period of time, the predetermined period of time being longer than the period in which developer is gathered on the sensor surface of the toner concentration sensor by the blade. The obtained maximum value is used as a characteristic value to control the toner concentration.

Abstract: In case of a developing density correction based on a test image (patch image) density, normally, the developing density is carried out in a short period of time by correction (? correction) of a developing bias and a grid voltage (S11). When a correction amount of the ? correction exceeds an ordinary range, the ? correction (S11) and adjustment of toner concentration (magnetic permeability reference value) (S5) are carried out in combination. Furthermore, when the toner concentration is changed, the setting of a correction reference of the ? correction (? correction TBL) and correction timing of the ? correction are accordingly changed (S6, S7). Therefore, in the developing density correction based on the test image density in the developing device using binary developer, it is possible to carry out the developing density correction, which is carried out in a short time, and whose correction width is wide, while maintaining the accuracy of a developing density adjustment.

Abstract: A closed-loop toner concentration adjustment system extends xerographic process control performance with a system and method including a first controller to adjust toner concentration (TC) in a developer of the imaging device to alter a DMA level of the imaging device, the TC being adjusted based on a TC target value; a second controller to adjust an electrostatic development field to alter the DMA level; and an adjustment logic device to adjust the TC target value based on adjustments made to the electrostatic development field. The first controller outputs a dispense amount to the developer based on a difference between a measurement of the actual TC and the TC target value, thereby adjusting the TC based on the dispense amount to the developer. The second controller adjusts the electrostatic development field based on a difference between a measurement of the actual DMA level and a DMA target value.

Abstract: An electrophotographic image forming apparatus includes a developer reservoir for accommodating a single-component mixed developer including two types of toner having a generally identical hue and different reflection densities. A magnetic substance is added to one of the two types of toner. The apparatus also includes a detector for detecting a magnetic permeability of the developer in the developer reservoir and a unit for determining a mixture ratio of the two types of toner based on the magnetic permeability of the developer detected by the detector.

Abstract: An image forming device includes a developer container sectioned into a plurality of chambers, an image forming unit which forms an image by using a developer supplied from the developer container, sensors which are respectively provided in at least two of the chambers of the developer container and detect the remaining amount of the developer in the chambers, and a determining unit which determines a status of the developer in the developer container in accordance with the remaining amount of the developer detected by the sensors.

Abstract: The present invention generally relates to a digital imaging system or a light lens based imaging system. More specifically, the present invention provides an improved method and apparatus for calculating toner age and, additionally, carrier age using a toner concentration sensor and the amount of material dispensed. Both of these quantities can be used to ensure image quality by anticipating or diagnosing problems in image quality, which may be caused by toner age or carrier age.

Abstract: An encoder of a process unit encodes an identification code output by the CPU of a main unit, thereby obtaining a response code. The response code is returned to the main unit. The logic of the encoder is changeable. At shipment, a first logic is set in the encoder. After use, a second logic determined on the basis of a predetermined rule is set to the encoder under control of the CPU. The main unit stores the second logic set in the encoder of the process unit. The identification code is encoded by the encoder of the main unit individually with the first logic and the stored second logic, with the result that normal codes are obtained. The normal codes are collated with the response code by a collator. The CPU identifies the status of the process unit based on the result of the collation by the collator.

Abstract: In adjustment control of a developing device, the number of printed sheets and the toner consumption amount per sheet are calculated. If the accumulated toner consumption amount is smaller than a predetermined amount when a predetermined number of sheets are printed, the developing device is caused to supply a developer in a predetermined amount corresponding to the difference, thereby performing development adjustment of the developing device.

Abstract: An image forming apparatus includes a toner concentration detector for detecting the toner concentration within a two-component developing unit, a toner supply unit for supplying a toner into the developing unit, a storage unit for sequentially holding and updating a history of a toner supply operation for a certain period of time, and a toner concentration control unit for determining the time of the toner supply operation by the toner supply unit, based on information stored in the storage unit and a difference between an output value of the toner concentration detector and a reference value, and maintaining the toner concentration constant.

Abstract: A printing device is capable of externally detecting: (a) a toner concentration in a developing unit; and (b) a reduction in the usable amount of toner. This eliminates the conventional need of disposing the toner concentration sensor in a narrow developing unit or the need of disposing the toner remaining amount detection sensor in the toner supply unit. Further, it is possible to detect reduction in the amount of toner every time the toner in the developing unit is out, thereby detecting reduction in the usable amount of toner stepwise and issuing an adequate warning whose level is changed depending on the detection result. Thus, the printing device meets the need for miniaturization and is capable of favorably performing printing operation and maintenance work.

Abstract: When shortage of a toner residual quantity is detected during printing, toner redetection is performed immediately after completion of printing. This toner redetection is carried out by stopping supply of a high-voltage power to, e.g., a transfer charger and supply of a power to a motor such as a paper carriage motor in order to avoid generation of noise. As a result, a toner sensor can correctly detect the toner residual quantity, and the toner can be appropriately supplied.

Abstract: In order to prevent a toner residual amount from being erroneously judged as “toner present” after the toner residual amount has been judged to be insufficient, a toner residual amount detection apparatus includes a developing device for developing an electrostatic image formed on an image bearing member by a toner, the developing device being provided for movement relative to an apparatus main body, a sensor for outputting information corresponding to the toner residual amount in the developing device, a judging device for comparing the output of the sensor with a reference value to thereby judge the toner residual amount, wherein image forming is inhibited via a predetermined number of times of image forming after the toner residual amount is judged to be not sufficient, and a changing device for changing the reference value to a smaller value with the judgement that the toner residual amount is not sufficient.

Abstract: A cartridge is set in a printer main unit, and has a remaining toner measurer which measures toner in a toner chamber upon setting of the cartridge. A cartridge memory stores information of a remaining toner amount measured previously. CPU compares the remaining toner amount measured newly with the remaining toner amount measured previously and read from the cartridge memory. If there is an increase in the toner, the cartridge is determined as improper cartridge reloaded with the toner. An alarm signal is generated. Also, printing is inhibited. In another preferred embodiment, shortage information is assigned to the cartridge upon using up the toner. The cartridge, if it has the shortage information, is determined as improper. If a characteristic of the toner is not within a reference range, the cartridge is determined improper. In another preferred embodiment, an upper limit of the number of times of toner reloading is predetermined.

Abstract: A wet electrophotographic image forming machine that informs a user of a timing for replacing development cartridges. The image forming machine comprises a control section for sensing the condition of the developer stored in one or more developer housings on the basis of a measured electric current flowing between one or more developer feeding members and one or more developer application members via the developer provided therebetween, and a display section for externally displaying the developer condition according to a signal from the control section. The control section evaluates the magnitude of the electric current and provides a signal to the control section for display if there is a developer amount or concentration deficiency.

Abstract: An image forming apparatus includes a latent image forming portion for forming an electrostatic latent image corresponding to image information on an image bearing member, a developing portion, having a developer container for accommodating a developer containing a toner and a carrier, for developing the electrostatic latent image with the toner, and a toner density detecting portion for detecting a toner density in the developer container, a toner replenishment amount to the developer container being controlled in accordance with a result of detection by the toner density detecting portion, wherein a toner replenishment amount target value used for controlling the toner replenishment is controlled to fall within a restriction range, and the restriction range can be changed according to the image information.

Abstract: Informing the user when consumables and/or customer replaceable units will have to be resupplied, changed and/or replaced, relative to the jobs sent to the image forming system, is a beneficial way to avoid unnecessary printing delays. When a job is added to a job queue or repositioned within the job queue, a warning can be associated with that job, and displayed to the user. With this information, the user can pre-emptively add a consumable and/or to replace a customer replaceable unit to avoid delays and maintain productivity. Alternatively, if such a system fault would occur prior to an urgent job reaching the top of the job queue, the user can manipulate the order and/or presence of the various jobs in the queue to ensure the high-priority job is completed before the consumable is fully exhausted and/or the customer replaceable unit reaches the end of its useful life.

Abstract: A developing device includes a developer including toner having a coloring agent dispersed in a binder resin, and carrier having a core material, and a coating layer covering the core material and containing a binder resin and a powder. A toner density detecting device detects a toner density of the developer by use of a bulk density sensor, and a control device controls the toner density based on a detection result of the toner density detecting device. The toner density is controlled such that ratio (D/h) of an average particle diameter (D) of the powder to a thickness of the coating layer is greater than 1 and less than 10.

Abstract: Provided are an image forming apparatus and method of controlling same in which when toner replenishment from a toner accommodating unit has been performed satisfactorily, a no-toner indication can be cancelled without taking more time than necessary, and in which the status of the toner accommodating unit can be reported to the user earlier even if a toner accommodating unit that has no toner or that has malfunctioned has been installed. Whether a toner accommodating unit (5) has toner is determined based upon a detection signal from a toner density sensor (46) that detects the toner density of a developer in a developing unit (4). If it is determined that there is no toner in the toner accommodating unit (5) and the toner accommodating unit (5) is replaced, this is detected and a toner density restoration sequence for restoring the density of toner in the developing unit (4) is executed.

Abstract: A printer, printer control method, and medium for storing the control method meter and store cumulative values relating to the operation of replaceable units (parts or devices) in the printer to make maintenance easier and more reliable, and enable more accurate analysis of part or device failure. The printing processor of the printer prints text or graphics, and a holder holds a replaceable part or device that operates or a consumable that is used in conjunction with the printing operation of the printing processor. A counting processor meters operation or use of the replaceable part or device, and a detection processor detects when the part or device in the holder has been replaced or newly installed. Values indicative of the operation or use metered by the counting processor are stored in nonvolatile memory.

Abstract: An electrophotographic image-forming apparatus and method using a two-component developer comprises a charging roller for charging a surface of a photosensitive medium at a predetermined potential; a developing unit for developing an electrostatic latent image formed on the photosensitive medium; a control unit for determining a developing bias voltage to be applied to a developing roller in relation to a print density level selected by a predetermined selection unit out of a plurality of print density levels set in varying degrees, calculating a surface potential of the photosensitive medium charged by the charging roller, and controlling a charging voltage to be applied to the charging roller in order that an absolute value of a potential difference between the determined developing bias voltage and calculated surface potential becomes higher than a predetermined potential; and a charging voltage adjustment unit for variably adjusting the charging voltage to be applied to the charging roller.