Abstract: A quadruple-tandem type image forming apparatus in which four units of an image forming unit are disposed, and toner images are transferred to a transfer material sequentially, wherein supposing that surface potentials of a photosensitive body in each image forming unit are V0a, V0b, V0c, V0d from upstream in a moving direction of a transfer material toward downstream, development bias voltages in each image forming unit are VBa, VBb, VBc, VBd, and electrification quantities of a toner in each developing unit in each image forming unit are qa. qb, qc, qd, the relations of V0a≧V0b≧V0c≧V0d, VBa≧VBb≧VBc≧VBd, and qa≧qb≧qc≧qd (wherein V0a>V0d, VBa>VBd, qa>qd) are fulfilled.

Abstract: Developing device and method in an image forming apparatus are provided which can make it possible maintaining stabilized image by accurately controlling a toner carry amount. A developing roller is supplied with toner from a toner feed roller to form thereon a toner layer by application of a bias voltage to a toner layer forming member which is in pressing contact with the developing roller. When the operation is started (S1), the current flowing from the toner layer forming blade is detected for a predetermined length of time (S2). Based on the detected result, the current toner carry amount is selected, through the operation of CPU and ROM of a controller, from data D which are previously written in ROM (S3). If the selected toner carry amount is determined as an acceptable level that represents a predetermined amount or more (step 4), printing operation is started as it is.

Abstract: In order to provide a compact, rapid and inexpensive image forming apparatus and method of the same having a hybrid developing apparatus wherein developing ghost and selective developing are avoided without complicating a developing apparatus and surly charged toner is supplied to a developing roll while stable quality images are obtained for a long time, an image forming apparatus and a method of the same which is characterized in that a developing roll is electrically conductive at least on its surface and a continuous plane of electrode to which a developing bias is applied in the direction of circumference at developing region by the surface is formed, and that the image forming apparatus and the method have a constitution capable of applying an alternate current bias having a duty ratio within the range from 10 to 50% and a direct current bias superposed thereon wherein the developing roll is directly confronted with a latent image bearing body through an insulative toner thin layer at the nearest region

Abstract: An image forming apparatus has developing rollers mounted to be spaced-apart from a photo-sensitive body and supplying a developing agent to the photo-sensitive body, a bias-applying part applying a predetermined bias to the developing rollers through respective current-conducting paths to the photo-sensitive body from the developing rollers, a current detection part detecting a current flowing through the developing rollers in accordance with a bias applied from the bias-applying part, and an engine control part applying a first test AC voltage having a set first frequency to the developing rollers, controlling the bias-applying part to apply a second test AC voltage having a set second frequency to the developing rollers, calculating a resistance of the developing rollers and a gap between the developing rollers and the photo-sensitive body using a current value detected from the current detection part respectively corresponding to the first and second frequencies, and setting a bias voltage of a driving co

Abstract: An image forming apparatus restricts disturbance of a potential patch in the case where a potential sensor for detecting the potential patch is provided downstream of a developing device of a multiple developing roller type so as to enable stable reproduction of a high quality image for a long period. The apparatus includes a potential sensor provided downstream in the moving direction of the image carrier relative to the developing device for detecting a potential on the image carrier, and a controller for setting the developing bias to a value restricting disturbance of a potential portion as an object for potential detection by the potential sensor by the developer when the potential portion passes across the developing device.

Abstract: The increasing ratio of development density to increase in potential difference between a photoreceptor and a development roller differs between the region where the potential difference is small and the region where the potential difference is large. The increasing ratio of development density at the region where the potential difference is small is smaller than the increasing ratio of development density at the region where the potential difference is large. Development is conducted under the developing characteristics in which the upper limit of the development density at the region where the increasing ratio of development density is small is at least 0.3.

Abstract: A non-contact developing type image forming apparatus has Y, M, C and K developers consecutively disposed to attach color toner consecutively onto a photosensitive medium, each of the developers has a developing roller and a supply roller; a power supply to selectively supply power to each of the developing rollers and the supply rollers; and a controller to control the power supply so that a potential difference is generated between the developing rollers and the supply rollers such that the potential difference is consecutively generated at the Y, M, C and K developers. Shock caused by impact between the developers and the photosensitive medium is not generated since the toner can be consecutively attached to the photosensitive medium without moving the Y, M, C and K developers.

Abstract: An image forming apparatus includes an image bearing member; a charging member for electrically charging the image bearing member; developing means for developing with a developer an electrostatic latent image formed on the image bearing member, the developing means having a developer carrying member for carrying the developer, wherein a gap is formed between the developer carrying member and the image bearing member; bias voltage applying means for applying a bias voltage to the developer carrying member, wherein the bias applying means applies an AC bias when the electrostatic latent image is developed, wherein the developing means is capable of collecting the developer fro the image bearing member, and an amplitude of an AC bias voltage applied to the developer carrying member by the bias applying means when the the developer is collected, is larger than that when the the electrostatic latent image is developed.

Abstract: An image to be formed on paper (26) is held on the surface of photo-sensitive drum (1). This is a latent image of static electricity formed by an LED exposer (5). Then, the developing roller (7) puts toner on the surface of photo sensitive drum (1), so as to develop a toner image. Meanwhile, the toner conveying roller (9) supplies toner to the developing roller (7). In this occasion, the printer controller (17) calculates the image density of image data (18) with dot counter (13). And, it decides the first voltage impressed to developing roller (7) by developing bias source (8) as well as the second voltage impressed to toner conveying roller (9) by stretching bias source (10) according to the image density of original image.

Abstract: To provide an image forming apparatus including: an image bearing member; an electrostatic latent image forming means for forming an electrostatic latent image on the image bearing member; a developing means for developing the electrostatic latent image in a development position, the developing means developing the electrostatic latent image using a developer containing a toner and an externally added agent having a charged polarity opposite to that of the toner; a cleaning blade for cleaning the image bearing member; and a bias controlling means for controlling a bias to be applied to the developing means, in which the bias controlling means sets a bias applied to the developing means at the time when an interval area passes the development position according to information related to a length of the interval area at the time when electrostatic latent images for a plurality of pages pass the development position.

Abstract: After forming solid patch images under various patch generating conditions (E, Vb), the optical densities of the respective patch images are measured by a patch sensor, and patch generating conditions matching with a higher-density side target density (OD=1.2) are extracted as “higher-density side correlation data.” Further, line patch images are formed under various patch generating conditions (E, Vb), the optical densities of the respective line patch images are measured by the patch sensor, and patch generating conditions matching with a lower-density side target density (OD=0.2) are extracted as “lower-density side correlation data.” An optimal exposure energy and an optimal developing bias are set based on one piece of correlation data (E2, Vb(3)) belonging to said product set of the higher-density side correlation data and the lower-density side correlation data.

Abstract: The surface of an electrostatic recording member in an electrophotographic recording apparatus is charged to a standard primary charge V0s. The standard primary charge on the recording member is then modulated using a first test exposure E1 to form a first exposed test area, and using a second test exposure E2 to form a second exposed test area. A first test surface potential V1 is measured in the first exposed test area and a second test surface potential V2 is measured in the second exposed test area. A measured intrinsic sensitivity bm associated with the recording member is calculated using V1 and V2. A measured intrinsic toe dm associated with the recording member also is calculated using V1 and V2. A corrective charge parameter V0i is calculated using dm, and a corrective exposure parameter E0l is calculated using bm and dm. V0 is then adjusted to equal V0i, and E0 is adjusted to equal E0i.

Abstract: Methods and apparatus for detecting a low toner condition in a color laser printer are disclosed. The invention generally includes at least one energy detector which can detect relative intensity of electromagnetic energy reflected from at least one toner area. A variation in the intensity of reflected energy, either from a reference value, or within a single toner area, or between two toner areas, can indicate toner fade due to a low toner condition. Apparatus in accordance with the present invention can also include a movable support surface which can support at least one toner area. Apparatus can also include at least one of various configurations of energy sources which can be configured to produce electromagnetic energy and direct the energy toward the toner area. A method in accordance with the present invention can include detecting intensity of electromagnetic energy reflected from at least one toner area.

Abstract: An electrophotographic imaging process includes the steps of (a) providing an organophotoreceptor belt having a photoconductive element on an electrically conductive substrate and a seam; (b) providing an imaging apparatus comprising a developer roll; (c) mounting the organophotoreceptor belt on the imaging apparatus; (d) applying a first voltage to the photoconductive element; (e) applying a second voltage to the developer roll when the seam is at a distance less than 10% of the circumference of the organophotoreceptor belt from the developer roll, otherwise applying a third voltage; (f) applying a fourth voltage to the electrically conductive substrate; (g) moving the organophotoreceptor belt; (h) imagewise exposing the surface of the organophotoreceptor belt to radiation to reduce voltage in selected areas and thereby form a pattern of high voltage and low voltage areas on the surface; (i) contacting the surface with a liquid ink comprising colorant particles in an organic liquid to create an imag

Abstract: An image forming device includes a storage device that stores toner, an agitator that agitates the toner in the storage device, a detector that detects an amount of toner in the storage device, and a controller that prohibits an operation of the agitator when the detected amount of toner is equal to or more than a prescribed amount, and permits the operation of the agitator when the amount of toner is less than the prescribed amount.

Abstract: An image forming apparatus is free of spots on reverse side of a sheet due to the accumulation of toner fog in a non-image-forming area (between sheets, initial rotation, post-rotation) of a photosensitive drum.

Abstract: A method of compensating for image quality controls a tone reproduction curve (TRC). The toner reproduction curve TRC &phgr;(k) measured by a color toner density sensor is compared with a target TRC &phgr;R to obtain a deviation &Dgr;&phgr;. A variation &Dgr;VB of a developer bias VB is calculated from a Jacobian matrix (JB) of a measured developer bias VB to calculate a new developer bias VBN and determining a measured grid voltage VG as a new grid voltage VGN if the deviation (&Dgr;&phgr;) is greater than a tolerance &Dgr;&phgr;T. A backplating vector VBP is obtained from the grid voltage VGN and the developer bias VBN. The backplating vector VBP is compared with a critical value VT to set control parameters VGN and VBN and control the TRC &phgr;. Thus, noise effects on the image quality are minimized to provide an output image closest to an input image quality so as to improve the image quality.

Abstract: An image forming apparatus for and a method of compensating for development mass per area includes a photosensitive body on which an electrostatic latent image for an image is formed, a charger charging the photosensitive body, a developing unit developing the electrostatic latent image of the photosensitive body, a measuring unit measuring a charge current flowing through the photosensitive body from the charger, a comparator comparing the charge current with a reference current, and a controller controlling a developing unit control variable so as to compensate for a variation in a thickness of the photosensitive body according to an output of the comparator. A time indicator of a display informs a user whether the photosensitive body has to be replaced, and deterioration of an image quality caused by a decrease in the thickness of the photosensitive body can be prevented when a potential of the developing unit is controlled.

Abstract: In a printer with an electrically chargeable image drum, such as a laser or a LED printer, for imprinting a medium by transferring toner to the medium, including, arranged around the image drum, a charging unit, a writing unit and a toner unit, the toner unit is disposed at a predetermined angular distance from the charging unit and a sensor is disposed at essentially the same angular distance from the charging unit to determine the charge of the image unit at the toner location for adjusting the voltage of at least one of the charging unit and the toner unit depending on the charge voltage of the image drum as determined by the sensor.

Abstract: A latent image is formed on a photoreceptor. Each of a plurality of toner carriers carries toner of a single color to be transferred onto the photoreceptor to make the latent image visible. Each of the toner carriers is fixed at a predetermined distance from a surface of the photoreceptor. A first bias supplier supplies a first bias required to transfer the toner to the photoreceptor to one of the toner carriers which is subjected to a developing operation. A second bias supplier supplies a second bias which is not enough to transfer the toner to the photoreceptor to the other toner carriers which are not subjected to the developing operation.

Abstract: An electrophotographic cluster printing system for performing printing by using a plurality of electrophotographic recording apparatuses such as printers, facsimile machines or copying machines each capable of manifesting an image by using colored particles such as toner. The electrophotographic cluster printing system includes a plurality of electrophotograhic recording apparatuses each including a photoconductor, a charger, an exposure device, a developing device, and an image quality controller for detecting a factor concerning image quality and controlling image quality of an output image on the basis of information of the detected factor. In the system, at least two of the electrophotograhic recording apparatuses is used for printing one job and image quality of any one of the electrophotograhic recording apparatuses is controlled on the basis of detected information of the other electrophotograhic recording apparatuses.

Abstract: A developing apparatus includes a developer carrying member for carrying a developer to develop an electrostatic image formed on an image bearing member with the developer; a developer regulating member for regulating an amount of the developer carried on the developer carrying member; and control means for controlling a potential difference between the developer carrying member and the developer regulating member such that the potential difference is larger in at least a part of non-developing operation than in a developing operation when the developer carrying member carries the developer control means for controlling a potential difference between the developer carrying member and the developer regulating member such that the potential difference is larger in at least a part of non-developing operation than in a developing operation when the developer carrying member carries the developer.

Abstract: The present invention employs a thickness detecting mechanism including a system for emitting polarized light and a reception system for receiving reflected light and generating electric signals. By use of this thickness detecting mechanism, the thickness of a toner layer attached to a latent image is measured. Developing conditions are controlled in relation to the measured thickness.

Abstract: In an image forming apparatus, an electrostatic latent image is reverse-developed by a developing device with a development bias applied, through conveying a two-component developer layer containing toner particles having a volume-average particle diameter of 3 to 5 &mgr;m by a developer carrying member rotatably provided, a developed toner image is transferred onto a recording medium or an intermediate transfer body, and untransferred toner particles remaining on an image forming body having passed a transfer region are removed by a cleaning member provided in pressure contact with the surface of the image forming body. The length in an axis direction of the image forming body of an useless toner image formed on the image forming body at the starting time and the ending time of an image formation sequence denoted by L, the total charge quantity of the toner particles making up the useless toner image is 0.04L &mgr;C or less.

Abstract: An image formation apparatus has a photoreceptor 1, a charger 2, a latent image write unit 3, a developing device 4, and a performance maintaining controller 5, wherein the performance maintaining controller 5 executes a performance maintaining initial sequence A for agitating and charging a developer G uniformly to such a degree that aggregating of the developer G in the developing device 4 is at least eliminated under the condition that the image formation apparatus is first used and also executes a performance maintaining sequence B for uniformly agitating and charging the developer G in the developing device 4 at least based on elapsed time since the immediately preceding image formation mode.

Abstract: A developing apparatus includes a toner carrying member for carrying toner to a developing zone where the developing apparatus faces to an image bearing member; bias voltage applying means for applying to the toner carrying member a developing bias voltage for developing an electrostatic latent image formed on the image bearing member, wherein the developing bias voltage is in the form of a DC voltage biased with an AC voltage the; wherein when a developing operation stops, rotation of the toner carrying member is stopped while rotating the image bearing member electrically charged, and then, the AC voltage is applied to the toner carrying member for a predetermined period, and thereafter, the AC voltage is stopped in a condition in which regular-charge toner is being urged from the toner carrying member toward the image bearing member.

Abstract: A developing device includes a supply member disposed to rotate in contact with a developer carrier to supply developer layer having a predetermined thickness to the developer carrier surface. A layer forming member is disposed to abut against the developer carrier to regulate the layer thickness of the developer so as to form a thin developer layer on the developer carrier. A bias application unit applies an AC-superimposed bias voltage to the developer carrier. A latent image on a latent image carrier is developed with the thin developer layer formed on the developer carrier by the layer forming member. The minimum value of the AC-superimposed bias voltage may be lower than the exposure potential of the latent image carrier, and a maximum value of the bias voltage is to be lower then the charge potential. However, the polarities of the two voltages may be identical.

Abstract: In a developing apparatus having the configuration of charging toner on the developing roller with the toner charging roller, toner charging roller contacts to the developing roller. Since toner adheres onto the toner charging roller by applying the voltage higher than a starting voltage in the developing apparatus, electrifying property of the toner charging roller drops. This causes low image quality since stable charges cannot be given to the toner on the developing roller. Therefore, they are provided, a developing apparatus and an image forming apparatus that can always offer good image quality by preventing adhesion of a developing material to a developer-charging member and always giving stable charges to a developer bearing body and developer.

Abstract: An image forming apparatus including image forming means for forming an image on a recording material, wherein at least a part of the image forming means is in the form of a unit which is detachably mountable to a main assembly of the apparatus, said apparatus includes memory, wherein said memory is mounted to said unit, wherein said memory stores information relating to timing at which a driving parameter of said image forming means.

Abstract: An image forming apparatus including image forming means for forming an image on a recording material, wherein at least a part of the image forming means is in the form of a unit which is detachably mountable to a main assembly of the apparatus, said apparatus includes memory, wherein said memory is mounted to said unit, wherein said memory stores information relating to timing at which a driving parameter of said image forming means.

Abstract: A medium thickness detecting apparatus detects the thickness of a recording medium. A displacement section is disposed in a transport path through which a recording medium passes. When the recording medium passes the displacement section, the displacement section displaces in a direction substantially normal to the surface of a recording medium. An amplifying section amplifies a displacement of the displacement section by a predetermined factor. A thickness determining section outputs a signal representative of an amplified value of the displacement. The displacement section may be one of two rollers between which the recording medium passes, and displaces upward when the recording medium passes between the two rollers. Alternatively, the displacement section my be positioned to sit on a stage provided in the transport path such that the displacement section is pushed away from the stage when the recording medium passes between the displacement section and the surface.

Abstract: An image formation apparatus for keeping secularly stable image quality for all image patterns if change in the charge amount of a developer caused by environment variation or over time or change in the photoconductor characteristic occurs in electrophotographic record apparatus. A test patch image formed on a photoconductor by a parallel electric field is detected by an image density sensor, the developing bias and the photoconductor surface potential are controlled so that the density detected by the image density sensor becomes constant, a test patch image formed on the photoconductor by a peripheral electric field is detected by the image density sensor with the control condition of the image density sensor maintained, and the light application amount in which an image area of a several-dot width adjacent a blank paper part is exposed to light is controlled so that the density detected by the image density sensor becomes constant.

Abstract: An image forming apparatus includes a developing device including plural developer supporters provided opposite to a photoconductor, a development bias applying unit for applying a development bias voltage generated by superimposing an AC voltage on a DC voltage to each of the developer supporters, and a phase shifter for shifting a phase of the AC voltage in the development bias voltage in each of the developer supporters.

Abstract: An image forming apparatus of the present invention includes an image carrier made up of a conductive base and photoconductive layer and a toner carrier to which a bias for development is applied. The toner carrier conveys toner deposited thereon to a developing position where the toner carrier faces the image carrier, thereby developing a latent image formed on the image carrier. The apparatus effects low-voltage development that protects the image carrier from electrostatic fatigue, obviates background contamination, and realizes image density as high as 0.5 ×10−3 g/cm2 or above in terms of the amount of toner deposition. Further, the apparatus implements faithful development of the latent image by reducing the edge effect. An image forming process unit removable from the apparatus is also disclosed.

Abstract: An image forming apparatus is capable of continuously forming images with proper density without reducing the image forming speed and, retrains toner consumption. A CPU for calculating an image forming condition by a density sensor is provided. The image forming operation is conducted in basis of a calculated new image forming condition and a current image forming condition used prior to the calculation of a new image forming condition in the image forming operation so as to determine an available image forming condition.

Abstract: A first embodiment of a measurement system provides an indication of performance of an electrophotographic process. The first embodiment includes a charge measurement device coupled to a developing device and a high voltage power supply. The charge measurement device generates a signal corresponding to the net charge transferred between the high voltage power supply and the developing device during an imaging operation. The measured charge transfer is compared to an estimated charge transfer to determine if the electrophotographic process is operating correctly. The estimated charge transfer is determined by multiplying an estimate of the mass of the toner transferred during an imaging operation by an average value of toner charge to mass ratio. A sufficiently large difference in the magnitude between the measured charge transfer and the estimated charge transferred indicates that the electrophotographic process is not operating correctly.

Abstract: A method of calibrating a multi-color electrophotographic machine having an image bearing surface includes forming toner patches of cyan, magenta, and yellow solid areas individually and in superimposed combination to form a series of single layer and multi-layer test patches. Light is emitted onto these single and multi-layer test patches. The amount of light that is reflected off of each test patch is measured. Light is also emitted onto a bare section of the image-bearing surface. The bare section has substantially no toner thereon. An amount of light that is reflected off of the bare section is measured. The step of measuring an amount of light reflected off single layer solid area test patches is repeated for a series of laser power and developer bias conditions. A laser power and/or a developer bias is adjusted dependent upon each of the three measuring steps.

Abstract: Toner which is made adjacent to a surface of a photosensitive body by a toner carrier is charged, by charge injection from the toner carrier, to have the same polarity as that of a third potential a potential of the toner carrier. A first potential which is a potential of a base material of the photosensitive body, a second potential which is an apparent potential of the photosensitive body, and the third potential of the toner carrier are set such that in the absolute values, first potential>third potential>second potential. As a result, the relation exposed part potential>toner carrier potential>non-exposed part potential, is established. Therefore, the toner is selectively adsorbed only to non-exposed parts.

Abstract: A developing apparatus includes developer carrying member for carrying a developer; wherein the developer carrying member is supplied with a developing voltage comprising a superimposed DC voltage component and AC voltage component to develop an electrostatic latent image formed on an image bearing member; switching means for switching an image density of a developed image on the image bearing member; wherein when the image density of the developed image is made higher than a predetermined image density in accordance with an output of the switching means, the frequency of the AC voltage component is made higher than a predetermined frequency.

Abstract: An image forming apparatus including a unit detachably mountable on the image forming apparatus, the unit having a developing device for developing a latent image formed on an image bearing member, a developing bias setter for setting a developing bias so that an image developed by the developing device maintains a predetermined density, and a life determiner for determining a life of the unit in accordance with a developing bias set by the developing bias setter and a reference bias. The reference bias is set in accordance with data relating to a used amount of the unit.

Abstract: An image forming apparatus of the present invention includes a bias power supply for applying a bias VB to a developer carrier on which a developer is deposited. A charge potential deposited on an image carrier, which faces the developer carrier for forming a latent image thereon, is 400 V or below in absolute value.

Abstract: A developing device and a developing method are provided which are capable of steadily supplying sufficiently charged toner to an image bearing member over a long period and always giving a high image quality.

Abstract: After forming solid patch images under various patch generating conditions (E, Vb), the optical densities of the respective patch images are measured by a patch sensor, and patch generating conditions matching with a higher-density side target density (OD=1.2) are extracted as “higher-density side correlation data.” Further, line patch images are formed under various patch generating conditions (E, Vb), the optical densities of the respective line patch images are measured by the patch sensor, and patch generating conditions matching with a lower-density side target density (OD=0.2) are extracted as “lower-density side correlation data.” An optimal exposure energy and an optimal developing bias are set based on one piece of correlation data (E2, Vb(3)) belonging to said product set of the higher-density side correlation data and the lower-density side correlation data.

Abstract: An image forming device, in accordance with the present invention, stores the correction factors produced during calibration cycles for future analysis. The correction factors, or alternatively, the new printer control parameters, which incorporate the correction factors, may be adjusted for current environmental conditions. During the calibration cycle, the correction factors produced during the current calibration cycle and old correction factors produced during prior calibration cycles are analyzed to determine if the printer control parameters are within desired degradation limits, which indicate that the print quality of the imaging forming device will degrade beyond acceptable limits prior to the next calibration cycle. Thus, a statistical analysis of the historical data produced during calibration cycles can be used to predict when the image quality of the image printing device will degrade beyond acceptable limits.

Abstract: A developing apparatus has a developer carrying body provided to face an image bearing body. The developer carrying body carries and conveys a developer having toner and carrier to a developing region. A bias applying device applies a developing bias to the developer carrying body, wherein the bias applying device applies to the developer carrying body the developing bias having periodically a voltage portion having alternately a first voltage to generate an electric field to direct toner from the developer carrying body to the image bearing body and a second voltage to generate an electric field to direct the toner from the image bearing body to the developer carrying body and a pause portion to pause applying the alternate voltage, wherein T1 and T2 have a relationship of T1>T2, where T1 is as an applying time period of the first voltage and T2 is an applying time period of the second voltage.

Abstract: The image forming apparatus has charging device, developing device, transfer-charging device, and control device for controlling a charging bias applied to the charging device. In the image forming apparatus, the transferring material to which the developer image is transferred is separated from the photosensitive body by the transfer-charging device, and the control device reduces the charging bias such that a surface potential of the photosensitive body in the case where the developer image is formed on the transferring material having low rigidity is lower than the surface potential of the photosensitive body in the case where the developer image is formed on the transferring material having high rigidity.

Abstract: In a print control method of an electrophotograph and an image formation apparatus thereof, a surface potential sensor is placed in a post-transfer area and at the position, the potential on the photoconductor drum surface at the developing point is detected. When the potential on the photoconductor drum surface is detected, the developing bias is avoided at the optimum timing and the potential is detected at the position after transfer. The correction potential amount grasped based on the in-machine humidity and the photoconductor drum film thickness previously measured is added to the detected potential and the potential on the photoconductor drum surface at the developing point is reproduced. Feedback control is applied to the potential on the photoconductor drum surface, whereby the developing potential on the photoconductor drum surface is kept stable.

Abstract: An image forming apparatus restricts disturbance of a potential patch in the case where a potential sensor for detecting the potential patch is provided downstream side of a developing device of a multiple developing roller type to enable stable reproduction of a high quality image for a long period. The apparatus includes a potential sensor provided downstream side of moving direction of the image carrier relative to the developing means for detecting a potential on the image carrier, and controller setting the developing bias to a value restricting disturbance of a potential portion as an object for potential detection by the potential sensor by the developer when the potential portion passes across the developing means.

Abstract: An image forming apparatus includes an image-forming unit having a charging section and a developing section that are rotated together with a photoconductor in an idling manner. The charging section and developing section receive voltages while rotating. The apparatus includes a toner sensor and a controller. The toner sensor outputs a detection signal indicating that the toner has been replenished in the image-forming unit. In accordance with the detection signal, the controller changes the voltages, a time length during which the photoconductor, charging section, and developing section are rotated, or speeds at which the photoconductor, charging section, and developing section are rotated. The time length is extended or speeds are increased when the image-forming unit has been replaced.

Abstract: In an electrostatographic development system wherein toner is conveyed from a donor member over a development gap to a charge receptor by a development field in the development gap, a method including the step of: monitoring at least a first parameter of the system to detect an arcing condition within the development gap; and if an arcing condition is detected, tuning a duty cycle to avoid the arcing condition.