Abstract: An image forming apparatus includes an image carrier, a charger, an exposure device, a development device and a pressing mechanism. The developer carrier is pressed on the image carrier with a predetermined pressing force to form a nip area between the roller part and the image carrier. A roller part of the developer carrier has an Asker C hardness of 65° or more and 73° or less. When the pressing force is set to X (N) and a width of the nip area in a circumferential direction of the image carrier is set to Y (?m), 3.0?X?8.0 and 550?Y?700, and the following expressions (1) and (2) are satisfied, Y ? 31. X + 393.2 ? and , ( 1 ) Y ? 47. X + 450.1 .

Abstract: The invention relates to a screening method. The method comprises the step of providing a sample, wherein said sample comprises a sample carrier with a surface structure, as well as an object of interest. The method further comprises the step of acquiring an image of said sample. According to the disclosure, the method comprises the steps of providing information on said surface structure of said sample carrier, which may in particular comprise the step of acquiring an image of said sample carrier. In that case two images are obtained: one more sensitive to the objects of interest, and one more sensitive to the surface structure of the sample carrier. This allows manipulation of the acquired image, using said information on the surface structure of the sample carrier. With this, said manipulated image may be screened for easy and reliable detection of said object of interest.

Abstract: A controller for an image forming apparatus includes a difference calculating portion for calculating a difference between a consumption value depending on an amount of the toner consumed every predetermined unit and a reference value; and a difference integrating portion. When an integrated value of the difference is larger than a predetermined threshold, the controller executes an operation in a forced consumption mode so that the toner is consumed in an amount corresponding to a predetermined value obtained by multiplying the predetermined threshold by a coefficient of less than 1. When the operation is executed, the integrating portion sets, at a reset value, a value obtained by subtracting the predetermined value from the integrated value at that time. After the operation is executed, the controller executes the operation every time when an integrated value obtained by integrating the reset value and the difference is larger than the predetermined threshold.

Abstract: An image forming apparatus includes an image carrier, a transferer to apply a constant-current controlled bias to a transfer medium to form a transfer electric field, a constant-current source configured to apply an electrical current to the transferer, an electrical characteristic detector, an environment detector, a first corrector, a second corrector, and a third corrector. The electrical characteristic detector detects an electrical characteristic value corresponding to a resistance in a current path from the constant-current source to the transferer. The environment detector detects an environmental condition inside the image forming apparatus. The first corrector corrects the electrical current based on the electrical characteristic detection and a predetermined threshold. The second corrector corrects the electrical current based on the environment detection. The third corrector sets the threshold based on the environment detection.

Abstract: An image forming apparatus has: a photoconductive drum that rotates; a developing roller that carries toner to be charged and to which a first voltage application portion outputting an AC voltage is connected; a contact member that makes contact with the photoconductive drum to remove residual toner; a detection portion for detecting occurrence of electric discharge between the developing roller and the photoconductive drum; and a developing unit that feeds toner to the developing roller, that supports the developing roller opposite the photoconductive drum with a gap secured in between, and that feeds toner to the developing roller with prescribed timing and for a prescribed time during electric discharge detection.

Abstract: An image forming apparatus capable of avoiding positional interference between an electrical potential sensor and a developing device during the installation or separation of the developing device. The positional interference is prevented by moving the electrical potential sensor out of the movement path of the developing device in association with the opening/closing movement a cover for an access opening in the body of the image forming apparatus for the installation/separation of the developing device. A link device connects the cover and the electrical potential sensor to each other so as to cause the movement of the electrical potential sensor in linkage with the opening/closing of the cover. The link device serves as an anti-interference device that prevents the positional interference between the developing device and the electrical potential sensor.

Abstract: A method for adjusting gloss appearance of images using a printer, includes: receiving a gloss selection input; correlating the gloss selection to a toner density setpoint value; adjusting one or more actuator controls such that the printer is configured to print using the toner density setpoint value; and rendering an image on a substrate using the one or more adjusted actuator controls. A printer configured to adjust gloss appearance of images is also disclosed.

Abstract: Developing bias is set as follows. An electric field intensity between a developing roller and a photoconductor is set to cause normally-charged toner to fly in an image area and not to cause the toner to fly in a background area. Thus, the normally-charged toner does not fly in the background area. The normally-charged toner caused to fly is therefore unlikely to flick low-charged toner and oppositely-charged toner. The low-charged toner and the oppositely-charged toner will not adhere to the background area and cause image fogging. Accordingly, an image forming apparatus can be provided to prevent the low-charged toner and the oppositely-charged toner from adhering to the background area of an electrostatic latent image on the photoconductor and to avoid the occurrence of image fogging in the background area on a printed material.

Abstract: In an image forming apparatus, an image forming contrast potential for obtaining the maximum density is set by reading a specific pattern transferred and formed on a sheet. A photosensor detects the density of a specific pattern formed on an image carrier at the image forming contrast potential, and the detection result is stored. A correction amount for the image forming contrast potential is calculated on the basis of the relationship between the stored detected density, and the density, detected by the optical sensor, of the specific pattern formed on the image carrier at a predetermined timing. The image forming contrast potential is adjusted by the correction amount.

Abstract: An image forming apparatus capable of suppressing occurrences of image defects and maintaining the image density constant while improving the development ability. The image forming apparatus includes a photosensitive drum on which an electrostatic latent image is carried, a developing sleeve on which developer is carried, an AC high-voltage drive circuit, an AC transformer, a DC high-voltage circuit, a p-p voltage detection circuit, and a CPU. The p-p voltage detection circuit converts a peak-to-peak voltage across a capacitor into a DC voltage which is taken out as a capacity detection signal. Based on the capacity detection signal output from the p-p voltage detection circuit, the CPU changes an image formation condition, e.g., a set value of a developing bias voltage.

Abstract: An image forming apparatus includes an image holder, a latent image forming unit, and a developing unit, the developing unit including a developer holder that is disposed to face the image holder and holds developer. Also included is a developer container, replenishing unit that replenishes new developer to the developing unit, a discharge unit that discharges the developer, a calculation unit that calculates an image area coverage of a toner image formed on the image holder, an obtaining unit that obtains a potential difference between the developer holder and the image portion on the image holder, and a controller that increases a discharge amount of the developer, when the image area coverage calculated by the calculation unit is smaller than a predetermined reference image area coverage, and the potential difference obtained by the obtaining unit is larger than a predetermined reference potential difference.

Abstract: A systems and methods for providing an image forming machine capable of monitoring the absolute charge to mass ratio of toner and dielectric thickness of a photoconductor layer on a photoconductor in an image forming device, and for providing warnings, alerts and process controls when the absolute charge to mass ratio of toner in an image forming device or the dielectric thickness of a photoconductor layer falls outside a predetermined range.

Abstract: In an embodiment in which an electrostatic latent image formed on the surface of a photoreceptor is developed with a toner by applying an oscillating bias voltage in which a development-side electrical potential and an opposite development-side electrical potential alternate with each other, between a development sleeve of a development roller and the photoreceptor, the development-side electrical potential is applied in two stages, and, in the two-staged development-side electrical potential, the absolute value of a first electrical potential V1 that is initially applied is larger than the absolute value of a second electrical potential V2 that is subsequently applied.

Abstract: In a development device which develops an electrostatic image formed on a rotating photosensitive drum by applying a development bias to a development sleeve bearing a two-component developer, the development device includes a specific pattern determination portion which determines whether or not the electrostatic image includes a specific pattern. When the development device develops the specific pattern electrostatic image determined by the specific pattern determination portion, a potential difference between a development sleeve and a first non-image part of a predetermined range which is adjacent to the specific pattern electrostatic image and located on an upstream side in a photosensitive drum rotating direction is set smaller than a potential difference between the development sleeve and a second non-image part which is different from the first non-image part.

Abstract: An image forming apparatus including: an image forming section for forming an image, the image forming section including a photoconductor, a charging unit, a developing unit, a toner supply unit which supplies a toner to said developing unit, and a developing bias power supply section which supplies a developing bias voltage to said developing unit; and a controller that activates said image forming section, determines a target value of a charging potential of said photoconductor and/or a developing bias voltage, for forming the image, and controls the charging unit and/or the developing bias power supply section in accordance with a determined result, wherein when an absolute value of the determined target value of the charging potential or an absolute value of the determined developing bias voltage is larger than a prescribed value, said controller controls replacement of a prescribed amount of a toner in the developing unit.

Abstract: A method for producing a color conversion table by which a color image signal to be handled in an image input system is converted to a N bit color image signal to be handled in an image output system, comprising the step of producing a color conversion table from which a N+? bit color output value, exceeding a color gamut of the color image signal to be handled in the image output system can be read out corresponding to a color input value of the color image signal to be handled in the input system.

Abstract: An image forming apparatus having a developing apparatus using a development system in which toner is moved by means of a traveling wave electric field. The image forming apparatus comprises a plurality of developing apparatuses having toner conveyance members which convey toner by means of a phase-shift electric field created by voltages of n phases applied to a plurality of electrodes, to a region opposing an image carrier on which an electrostatic latent image is formed; and a voltage application device which applies a voltage having an average potential value between the potential of the image portions of the latent image on the image carrier and the non-image portions of same, to the electrodes of the toner conveyance members of the respective developing apparatuses.

Abstract: An image forming apparatus capable of suppressing occurrences of image defects and maintaining the image density constant while improving the development ability. The image forming apparatus includes a photosensitive drum on which an electrostatic latent image is carried, a developing sleeve on which developer is carried, an AC high-voltage drive circuit, an AC transformer, a DC high-voltage circuit, a p-p voltage detection circuit, and a CPU. The p-p voltage detection circuit converts a peak-to-peak voltage across a capacitor into a DC voltage which is taken out as a capacity detection signal. Based on the capacity detection signal output from the p-p voltage detection circuit, the CPU changes an image formation condition, e.g., a set value of a developing bias voltage.

Abstract: A reference developing image is formed on a photoreceptor drum under an image forming condition measured in advance, and the density of this reference developing image is detected. A development bias voltage is corrected based on the detection result, and when a correction value of the development bias voltage exceeds a predetermined range, a reference output voltage of an ATC sensor for detecting the density of toner in a developing device is corrected based on the detected value of humidity around the developing device, the frequency of use of the apparatus, and the agitation stress of developer.

Abstract: Related is an image forming apparatus by electrophotography having a function of performing adjustment of image quality when performing image formation. The image forming apparatus includes a detection portion for detecting a fixing temperature of a fixing apparatus; a storage portion for storing an application history of a development bias; a count portion for counting a reposed time from a point when an operation of image formation is ended; a determination portion for determining a change range of the development bias immediately before the end of the operation of image formation; and an execution portion for executing adjustment of image quality by setting the development bias based on a determination result from the determination portion when the reposed time or the fixing temperature exceeds a predetermined value.

Abstract: An image forming device includes an image carrier having a surface onto which an electrostatic latent image is formed, a development station including a case made of a conductive body and one or more developer rollers, which supply toner housed in the case to the surface of the image carrier, and develop the electrostatic latent image formed on the surface of the image carrier as a toner image, a unit, which forms a standard concentration toner image of on the surface of the image carrier, a detector, which detects a toner adhesion amount of the standard concentration toner image formed on the surface of the image carrier by the standard concentration toner image-forming unit, and a voltage controller, which controls a bias voltage to be applied to the case according to a detected result of the toner adhesion amount of the standard concentration toner image by the detector.

Abstract: A potential measuring device for measuring a potential of a measurement object, includes a detection electrode that faces the measurement object, a reference electrode disposed in a vicinity of the detection electrode that is electrostatically shielded by an electrostatic shield structure with respect to the measurement object, and capacitance modulator for modulating an electrostatic coupled capacitance between the detection electrode and the measurement object to measure a potential of the measurement object by using an electric signal generated on the detection electrode and an electric signal generated on the reference electrode.

Abstract: An image forming apparatus for developing an electrostatic image formed on a photosensitive drum 1 with a developer, so as to form an image includes: a rotatable developing sleeve 44; a developing blade 46 for restricting a layer of a developer borne on the developing sleeve 44; developing means for developing the electrostatic image formed on the photosensitive drum 1 with the developer; vibrating means 50 for vibrating the developing blade 46; and control means for controlling a drive condition of the vibrating means 50 according to a printing ratio of the image formed.

Abstract: An image forming apparatus including (a) a ? conversion unit having a ? conversion table ??i of a first one Vcont? of a designation development contrast in a case that a development contrast correction amount ?Vcont1 is a first value, and a ? conversion table ??i, different from the ? conversion table ??i, of a second one Vcont?, different from the first one Vcont?, of the designation development contrast in a case that the development contrast correction amount ?Vcont1 is a second value different from the first value, and (b) an arithmetic operation unit for calculating a ? conversion table ?Nowi of a third one VcontNow of the designation development contrast in a case that the development contrast correction amount ?Vcont1 is a third value, based on a formula: ?Nowi=??i+(??i???i)×(Vcont??VcontNow/(Vcont??Vcont?), wherein the subscript i is a value of an output density signal in the ? conversion table.

Abstract: In an image forming apparatus, temporary constant voltages are not by using three voltage-current data obtained by applying voltages at three levels to a primary transfer roller to detect currents corresponding to the voltages, respectively. A surface potential of a photosensitive drum is detected by a potential sensor by changing an exposure intensity of an exposure device at three levels in a state in which the temporary constant voltage is applied to the primary transfer roller. A constant voltage during image formation is determined by correcting the temporary constant voltage by using three voltage-current data obtained by detecting currents when surfaces different in potential by light exposure pass through a primary transfer portion.

Abstract: In a development device which develops an electrostatic image formed on a rotating photosensitive drum by applying a development bias to a development sleeve bearing a two-component developer, the development device includes a specific pattern determination portion which determines whether or not the electrostatic image includes a specific pattern. When the development device develops the specific pattern electrostatic image determined by the specific pattern determination portion, a potential difference between a development sleeve and a first non-image part of a predetermined range which is adjacent to the specific pattern electrostatic image and located on an upstream side in a photosensitive drum rotating direction is set smaller than a potential difference between the development sleeve and a second non-image part which is different from the first non-image part.

Abstract: An image forming apparatus has a pair of spacedly opposed first and second bearing members, in which a powder developer material is moved from the first bearing member to the second bearing member. The apparatus also has an electric field generator. The generator forms an electric field between the first and second bearing members and outputs a first voltage and a second voltage alternately. The first voltage generates, between the first and second bearing members, a first electric field electrically forcing the developer material from the first bearing member toward the second bearing member. The second voltage generates between the first and second bearing members a second electric field electrically forcing the developer material from the second bearing member toward the first bearing member.

Abstract: An image forming apparatus, wherein the following formulae are satisfied: 0.22 ? ( M / S ) L ? 0.4 , ? ( Q M ) L = Vc ( Lt 2 ? ? 0 ? ? t + Ld ? 0 ? ? d ) × ( M S ) L ( Dt ? ? max - Dt 0.1 ) { ? × ( M S ) L - 0.1 } ? ( Lt 2 ? ? 0 ? ? t + Ld ? 0 ? ? d ) × ( M S ) L 500 ? ?? ? ( Dt ? ? max - Dt 0.1 ) { ? × ( M S ) L - 0.1 } ? ( Lt 2 ? ? 0 ? ? t + Ld ? 0 ? ? d ) × ( M S ) L 150 ?? ? ( Dt ? ? max - Dt 0.1 ) { ? × ( M S ) L - 0.

Abstract: In an embodiment in which an electrostatic latent image formed on the surface of a photoreceptor is developed with a toner by applying an oscillating bias voltage in which a development-side electrical potential and an opposite development-side electrical potential alternate with each other, between a development sleeve of a development roller and the photoreceptor, the development-side electrical potential is applied in two stages, and, in the two-staged development-side electrical potential, the absolute value of a first electrical potential V1 that is initially applied is larger than the absolute value of a second electrical potential V2 that is subsequently applied.

Abstract: The present invention provides an image forming apparatus that suppresses the increase of the potential of a toner attached to a developing roller, which occurs right after an image drum unit is started, to prevent the toner from moving from the developing roller to a photosensitive drum irrespectively of an electrostatic latent image, thereby preventing recording paper from being smeared. The image forming apparatus of the present invention controls a voltage applied to the developing member with a voltage application control unit or controls the rotational speed of the image carrier with a speed control unit to suppress the increase of the potential of the developer on the developing roller.

Abstract: A surface-potential distribution measuring apparatus includes an electron gun, an electron-beam optical system, an electron-emission panel, a detector, and a control system. The electron-beam optical system is located between the electron gun and a sample, and focuses a beam of electrons emitted from the electron gun to the surface of the sample. The electron-emission panel is located near the sample to be collided with at least part of the electrons via the sample, and emits secondary electrons corresponding to the number of collided electrons. The detector detects at least part of the secondary electrons. The control system obtains potential distribution on the surface of the sample based on a detection result obtained by the detector.

Abstract: The invention provides an image forming apparatus and an image forming method, capable of providing an image with little deterioration, even in case the image contrast has to be adjusted not for the purpose of image adjustment, such as for reducing the toner consumption amount or for preventing the leak in the charging device.

Abstract: A technique capable of preventing deterioration of image quality resulting from a band-shaped toner image created on a photosensitive surface in order to prevent so-called carrier attraction is provided.

Abstract: An image forming apparatus includes an image bearing body which can bear an electrostatic image; a bias member to which a predetermined bias is applied from a bias applying device; and a surface potential detection device which detects a surface potential at the image bearing body. The surface potential detection device includes a detector portion which generates a signal corresponding to the surface potential at the image bearing body and a potential detection portion which detects the surface potential by the signal from the detector portion. In the image forming apparatus, the potential detection portion is also used for detection of a bias value which the bias applying device applies to the bias member, the bias applying device is controlled based on the detection result of the bias which the bias applying device applies, and the bias detection result is obtained by the potential detection unit.

Abstract: An image forming apparatus having an image carrier, a charging unit for charging the image carrier and residual toner on the image carrier, a charging bias applying unit, an electrostatic image forming unit, a developing unit for collecting the residual toner on the image carrier and visualizing the electrostatic image, and a developing bias regulating unit. The apparatus further comprises an image ratio calculating unit for calculating an image ratio on the basis of the electrostatic image, and a regulating unit for regulating a contrast potential between the developing unit collecting the residual toner and the image carrier on the basis of a calculated image ratio. In the apparatus, an occurrence of the problem of adhesion of toner to a non-image area is prevented by fully collecting transfer residual toner also in forming an image having a high image ratio.

Abstract: A developing apparatus includes a developer container for containing a developer containing toner and carrier particles having a volume resistivity of 106-1010 ?cm; a developer carrying member for carrying the developer contained in the developer container; a voltage applying means for applying a developing bias voltage having a DC component and an AC component to the developer carrying member when an electrostatic image formed on an image hearing member including a surface layer having a volume resistivity of 109-1014 ?cm is developed by contacting the developer carried on the developer carrying member to the electrostatic image, wherein a volume resistivity of the developer carrying member is 1×10?1-1×102 ?cm.

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. Assume that the potential of the image carrier is lowered to VL after exposure, that a development potential is |VB?VL|, that the maximum set value of the development potential for development is |VB?VL|max, and that the development potential varies in a range satisfying relations: |VB?VL|?|VB?VL|max+|VB?VL|max×0.2 |VB?VL|?|VB?VL|max?|VB?VL|max×0.2 |VB?VL|max?300 V Then image density varies by a width of 10% of image density corresponding to the maximum set value of the development potential or less.

Abstract: A print control method of an electrophotograph in an image formation apparatus including at least a photoconductor, a charger, a light exposure unit, and a developing device for forming a background area and an image area on the photoconductor using the charger and the light exposure unit and detecting a potential of the image area after transfer and controlling a developing electric field, thereby printing an electrophotograph, includes lowering the percentage of toner covering the image area on the photoconductor when the potential is detected.

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. Assume that the potential of the image carrier is lowered to VL after exposure, that a development potential is |VB−VL|, that the maximum set value of the development potential for development is |VB−VL|max, and that the development potential varies in a range satisfying relations: |VB−VL|≦|VB−VL|max+|VB−VL|max×0.2 |VB−VL|≧|VB−VL|max−|VB−VL|max×0.

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: 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: A high quality image forming apparatus capable of outputting a quality image at a high speed is provided, with which no unevenness is generated on an image and a fog or a change in density is less likely to occur. An exposing unit is operated by an over-filled scanner method for exposure by a rotational polygon mirror that reflects lights on a surface narrower than an incident beam width, and forms an electrostatic latent image by back area exposure for exposing a non-image part.

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: 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 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 high quality image forming apparatus capable of outputting a quality image at a high speed is provided, with which no unevenness is generated on an image and a fog or a change in density is less likely to occur. An exposing unit is operated by an over-filled scanner method for exposure by a rotational polygon mirror that reflects lights on a surface narrower than an incident beam width, and forms an electrostatic latent image by back area exposure for exposing a non-image part.

Abstract: In an image forming apparatus, the developing unit includes two developing rollers whose rotational directions are different from each other, and a bias potential of the developing roller (first developing roller) located upstream in the rotational direction of the photosensitive member is selected to be a potential, which is in value between a bias potential of the developing roller (second developing roller) located downstream in the same direction and a background potential.

Abstract: In an electrophotographic image forming apparatus, the density of a dot image is stabilized by detecting the toner density of a first standard toner image having toners of a uniform density formed on a photoconductor, adjusting the development bias voltage applied to a development device according to the detected toner density. The adjusted development bias voltage is used to form on the photoconductor a second standard toner image having toners of dots with predetermined spaces there between. Then, an area ratio of dot area to unit area of the second standard toner image is detected and is used to control the image forming conditions of the image forming apparatus to stabilize the density of a dot image.

Abstract: An electrophotographic process and arrangement for generates a macro-charge zone inkable by toner applicators and delimited by an inking limit (EG) having an adjustable contour on a photoconductor of a printing or copying machine, using at least one exposure-variable and position-variable controllable light source (LED), such as an LED comb or laser. By controlling the exposure of the light source and its radiation position on the photoconductor and by controlling a bias voltage (UB) which can be applied between photoconductor and toner applicator, an electrostatic potential relief (UR) made up of individual adjacent micro-charge zones (UM) of exposure-dependent size is generated on the photoconductor and the inking limit (EG) is defined, the contour of the inking limit being determined by the bias voltage level (UB) on the potential relief (UR).

Abstract: A method and a device for supplying a developing bias voltage capable of minimizing toner consumption by reducing wasted toner during a printing operation in the image forming apparatus. The image forming apparatus comprises a photosensitive drum for forming an electrostatic latent image, a charger for providing a predetermined charging voltage to the photosensitive drum such that different bias voltages are supplied to image and non-image areas, an exposure unit for forming the electrostatic latent image on the photosensitive drum by providing image data, a developing unit for developing the electrostatic latent image formed on the photosensitive drum by toner, a transfer unit for transferring the developed toner to a printing paper, and a developing bias controller.