Abstract: A developer apparatus includes a developer carrying member, for carrying a developer to a developing portion, the developer carrying member including an electroconductive base and a resistance layer provided thereon; a developer feeding member for being supplied with a voltage to supply the developer to the developer carrying member; wherein a surface moving speed of the developer carrying member Vp [mm/sec], a resistance R1 (?) of the developer carrying member when an electric current applied the developer carrying member is 0.04 Vp [?A], and a resistance R2 (?) or the developer carrying member when the electric current applied to the developer carrying member is 4 Vp [?A], satisfy: r1/R2<15.

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.

Abstract: A developing device having a plurality of sleeves is provided for high-speed development and the prevention of an abnormal image, for example, thinning of a line image. An AC bias is effectively applied, so that the base contamination is suppressed to obtain a smooth image without obvious grains. Among the plural sleeves, a bias towards the photoreceptor side is applied to an upstream-side sleeve, and a bias in the reverse direction is applied to a downstream-side sleeve. Alternatively, an AC bias with a low frequency is applied to the upstream-side sleeve and an AC bias with a high frequency is applied to the downstream-side sleeve. In addition, an AC bias with a large amplitude is applied to the upstream-side sleeve, and an AC bias with a small amplitude is applied to the downstream-side sleeve.

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 color image forming apparatus includes a photoreceptor medium, an exposing unit, a plurality of developer units, and a power supply. The exposing unit scans light onto the photoreceptor drum to form a latent electrostatic image. The plurality of developer units include developer rollers supplying toner to the latent electrostatic image to develop the latent electrostatic image into a toner image. Each developer unit contains toner of a different color, and the developer units are arranged around the photoreceptor medium so that the developer rollers are separated by a development gap from the photoreceptor medium. The power supply selectively applies a first bias allowing toner to be supplied through the development gap to the photoreceptor medium on which the latent electrostatic image is formed and a second bias preventing toner from passing through the development gap.

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 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. A controller circuit sets a voltage level based on the amount of toner and a biasing circuit impresses the voltage to a developing roller, a supply roller and a regulating blade.

Abstract: A duplex electro-photographic developing machine including a printing medium tray loading a printing medium, a tray open/closed detecting unit detecting whether the printing medium tray has been opened and closed, a transferring roller transferring a toner image onto the printing medium, a resistance measuring unit measuring a resistance value of the printing medium passing the transferring roller, and a concentration controlling unit controlling a concentration of the toner image according to the measured resistance value measured by the resistance measuring unit in response to the printing medium tray having changed from an open state to a close state.

Abstract: An image forming apparatus includes an image bearing drum, a developing roller, a toner-supplying roller, and a controller. The developing roller deposits toner to an electrostatic latent image formed on the image bearing drum. The toner-supplying roller is spaced a distance in the range of 0.05 to 1.0 mm from the developing roller and supplies toner to the developing roller. The controller applies a first voltage to the developing roller and a second voltage to the toner-supplying roller. The difference between the first voltage and the second voltage is greater than 130 volts and lower than a voltage above which electrical discharge occurs across the developing member and the toner-supplying roller. The toner-supplying roller has a surface with ridges and valleys formed therein, which extend in a longitudinal direction of the toner-supplying roller. The ridges have a height in the range of 10 to 1000 ?m.

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 developing device including a latent image supporter. Powder is adhered on the latent image supporter to develop a latent image on the latent image supporter and a transporting member is arranged opposite to the latent image supporter. A plurality of electrodes are formed in the transporting member for generating a traveling-wave electric field to move the powder, and n-phase voltages are applied to the electrodes of the transporting member to form an electric field in a first direction so that the powder moves towards the latent image supporter at an image portion of the latent image and in a second direction so that the powder moves in a direction opposite to the latent image supporter at a non-image portion of the latent image.

Abstract: In an image forming apparatus employing a two-component developing system, there are provided printed-sheet number counting means; developing-device drive time integrating means for integrating time during which a developing device drives; and a toner replenishing motor drive time integrating means for integrating time during which a toner replenishing motor drives. Integrated drive time of the developing device and integrated drive time of the toner replenishing motor every fixed printed-sheet number, and the toner consuming quantity per drive time of the developing device is calculated from the extracted data. The toner charge quantity in a developer is predicted on the basis of the calculated data, and a developing bias voltage applied to the developing device is changed to thereby revise an image density.

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 and a method of controlling a development voltage include a photosensitive body, a charger which charges the photosensitive body, a laser scanning unit (LSU) which forms an electrostatic latent image by radiating light onto the photosensitive body, a developing unit which develops the electrostatic latent image by supplying a developing agent to the photosensitive body to form an image, a transfer unit which transfers the developed image onto a sheet of paper, a surface potential measuring unit disposed on the surface of the photosensitive body between the developing unit and the transfer unit to measure a surface potential of the photosensitive body, a comparator which compares the surface potential of the photosensitive body before a development voltage is supplied to the developing unit, with the surface potential of the photosensitive body after the development voltage is supplied to the developing unit, to calculate a deviation, and a controller which sets a new development vol

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: The charging method is arranged so as to charge the toner on a developing roller by electrons as generated by the photoelectric effect from a photo-electric surface of a toner layer regulating/charging blade. An electric bias is applied across a toner layer thickness regulating/charging blade and a developing roller, and an amount of electrons discharged indicated by current flowing across the toner layer thickness regulating/charging blade and the developing roller is measured by an amplifier. When the amount of electrons discharged is detected to be 1/t of an initial amount, the amount of light to be received by the photo-electric surface of an ultraviolet ray luminescent is increased by t times to be the initial amount. According to the foregoing method, such event that the photoelectric effect is weakened due to the deterioration of the photoelectric surface can be detected with ease, and thus desirable charged state of toner can be maintained with ease.

Abstract: An electrophotographic image forming apparatus having a photosensitive member 1, a charging roller 2 and a developing roller 31, and including an output variable power source 8 common to the charging and the developing rollers 2 and 31 for applying voltages to the charging and developing rollers 2 and 31, respectively, a power source output control portion 9, and a voltage changing device (Zener diode D1) interposed between the developing roller 31 and the power source 8, wherein, when the voltages applied to the charging and developing rollers 2 and 31 are raised to and lowered from voltages required for image formation, respectively, the control portion 9 controls an output of the power source 8 to perform the raising and lowering of the applied voltages for a predetermined time while keeping a potential difference for suppressing movement of developer onto the photosensitive member 1 between the voltages applied to the charging and developing rollers 2 and 31.

Abstract: A development device includes a developing gap detection function. The development device also includes an organic photoconductive body, a developer conveying body, a DC power supply, an AC power supply, a discharge start voltage detection portion, and a controller. The discharge start voltage detection portion detects a discharge start voltage occurring between the developer conveying body and the organic photoconductive body when a voltage is supplied from the power supply unit in increments at predetermined intervals. The controller obtains a developing gap between the organic photoconductive body and the developer conveying body based on the discharge start voltage detected by the discharge start voltage detection portion, and outputs a developing voltage suitable for the obtained developing gap.

Abstract: An image forming device includes an image forming unit that includes a photoconductive drum which carries an electrostatic latent image, a developing roller which forms a developing nip by contacting the photoconductive drum and develops the latent image by using toner, and a transfer roller that forms a transferring nip by contacting the photoconductive drum and transfers a toner image onto a recording paper. A transferring voltage impressing circuit impresses to the transfer roller, a voltage of an opposite polarity to a polarity of a transfer process, for a prescribed period of time during a period when the recording paper is absent in the transferring nip. A developing voltage impressing circuit impresses to the developing roller, a voltage of a same polarity as a developing process and lower than the developing process when a field impressed with the voltage of the opposite polarity by the transferring voltage impressing circuit passes the developing nip.

Abstract: An image forming device includes an image forming unit that includes an image carrier which carries an electrostatic latent image, a developing unit which forms a developing nip by contacting with the image carrier and develops the latent image by using toner, a transfer unit which forms a transferring nip by contacting with the image carrier and transfers a toner image onto a recording paper, and a first driving unit which rotates the image carrier, the developing unit and the transfer unit. The image forming device also includes a laser scanner unit that includes a polygon mirror and a second driving unit which rotates the polygon mirror.

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: 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 device includes a development section which has a blade for applying electrons generated in its photoelectric surface due to a photoelectric effect to a toner so as to charge the toner; an ultraviolet irradiator for irradiating the photoelectric surface with light; a development roller for holding the toner thus charged, and performing carriage of the toner to a photoconductive drum having an electrostatic latent image on a surface; wherein the electrostatic latent image on the photoconductive drum is developed by the charged toner. The development section further includes a control section for performing control of application of a voltage to the ultraviolet irradiator, application of a voltage to the photoelectric surface, application of a voltage to the development roller, and beginning of the carriage of the toner by the development roller, at predetermined timings, respectively.

Abstract: A method and apparatus for image forming includes a hybrid developing apparatus that supplies surly charged toner to a developing roll. The apparatus includes a developing roll that is electrically conductive at least on its surface. The image forming apparatus and the method have a constitution capable of applying an alternating current bias having a duty ratio in the range of 10 to 50% and a direct current bias superposed thereon. The developing roll is directly confronted with a latent image bearing body through an insulative toner thin layer at the nearest region of the developing roll and the latent image bearing body. An independent bias is applied to each of the developing roll and the magnetic roll, and the toner is refreshed by the varying duty ratio of the alternate current bias and the direct current bias after developing.

Abstract: An image forming section includes an image bearing body that bears an electrostatic latent. An operation status detecting section detects at least one of an operation status in which the image forming section operates and an environmental condition in which the image forming section operates. The operation status includes, for example, the number of printed pages, the density of toner image, and the amount of toner consumed. A print condition setting section sets preliminary print conditions. The preliminary print condition includes a developing voltage, the amount of light emitted from an exposing unit, and a charging voltage. A limit setting section sets a limit value based on the environmental conditions. A print controller compares the preliminary print condition with the limit value to determine an ultimate print condition so that the ultimate print condition is within a predetermined range.

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: An image forming apparatus of an electrophotography system, in which 10<PS/|Hz1−Hz2| is satisfied where Hz1 indicates a frequency of charging bias, Hz2 indicates a frequency of developing bias, and PS indicates a peripheral speed of a photosensitive member, whereby preventing density unevenness in an image.

Abstract: A developer apparatus includes a developer carrying member, for carrying a developer to a developing portion, the developer carrying member including an electroconductive base and a resistance layer provided thereon; a developer feeding member for being supplied with a voltage to supply the developer to the developer carrying member; wherein a surface moving speed of the developer carrying member Vp [mm/sec], a resistance R1 (&OHgr;) of the developer carrying member when an electric current applied the developer carrying member is 0.

Abstract: In an image forming apparatus employing a two-component developing system, there are provided printed-sheet number counting means; developing-device drive time integrating means for integrating time during which a developing device drives; and a toner replenishing motor drive time integrating means for integrating time during which a toner replenishing motor drives. Integrated drive time of the developing device and integrated drive time of the toner replenishing motor every fixed printed-sheet number, and the toner consuming quantity per drive time of the developing device is calculated from the extracted data. The toner charge quantity in a developer is predicted on the basis of the calculated data, and a developing bias voltage applied to the developing device is changed to thereby revise an image density.

Abstract: In an image forming apparatus employing a two-component developing system, there are provided print-sheet number counting means; developing-device drive time integrating means for integrating time during which a developing device drives; and a toner replenishing motor drive time integrated drive time integrating means for integrating time during which a toner replenishing motor drives. Integrated drive time of the developing device and integrated drive time of the motor toner replenishing motor every fixed printed-sheet number, and the toner consuming quantity per drive time of the developing device is calculated from the extracted data. The toner charge quantity in a developer is predicted on the basis of the calculated data, and a developing bias voltage applied to the developing device is changed to thereby revised an image density.

Abstract: An image forming apparatus including a photoconductive medium, a laser scanning unit to scan a laser beam to the photoconductive medium to form an electrostatic latent image, and a plurality of developing apparatuses each including a developing roller to adhere toner to the electrostatic latent image, and a supplying roller to supply the toner. The apparatus further includes a transferring unit to transfer a toner image formed on the photoconductive medium to a paper, a voltage supplying apparatus to supply a bias voltage to the developing rollers and the supplying rollers of the respective developing apparatuses to enable the developing apparatus to perform the developing operation, and a controlling apparatus to control the voltage supplying apparatus such that the developing apparatuses perform the developing operations one by one with respect to the respective electrostatic latent images which are formed on the photoconductive medium.

Abstract: An image forming apparatus, includes an image bearing device for bearing an image to be formed on a transferring material; a charger; an exposing device; a developing device; a transferring device, which transfers a developed image formed on the image bearing device to a transferring material; a current detector, which detects a transferring current flowing through the transferring device; and a controller. A voltage set in the developing device for an image forming area of the image bearing device is different from a voltage set in the developing device for the non-image-forming area of the image bearing device. The controller controls the voltage set in the developing portion, wherein a voltage for the non-image-forming area is controlled based on an output of the current detector.

Abstract: An image forming device which is provided with a developing unit for image visualizing an electrostatic latent image formed on an image carrying body by utilizing two components developing agent containing toners and carriers, transfers a toner image on a recording medium and fixes the toner image transferred on the recording medium on another recording medium to obtain a record image, which is further provided with a patch sensor for detecting an image density of the record image and controls toner density stabilization control and adjustment value and bias voltage in the developing unit according to a value detected by the patch sensor and a value of current flowing in the image carrying body from the developing unit.

Abstract: During printing on a thick paper, a Scorotron charger disposed upstream of a developing roller in a drum rotational direction charges a photosensitive drum to about 1000 V. Then a transfer roller disposed downstream of the developing roller lowers the potential to about 80 V. The transfer bias is turned off at the end of printing at T1 and does not lower the surface potential after this. When the surface of the drum opposite the transfer roller reaches a position opposite the Scorotron charger at T2, a DC motor and a charging bias are turned off. The surface potential of the drum that passes opposite the developing roller remains at about 400 V and is higher than developing roller potential until the photosensitive drum comes to a complete stop after idling at T3. This prevents the developing agent from adhering to the photosensitive drum.

Abstract: An image forming apparatus includes a plurality of developing devices, each of which includes a developer carrying member for carrying a developer to develop an electrostatic image formed on an image bearing member with a developer, and a developer regulating member for regulating the developer carried on the developer carrying member; common voltage applying means for applying voltages to the developer regulating members, wherein the voltages applied to the developer carrying members are variable independently from each other, and when at least one of the voltages varies, the voltage applied by said voltage applying means is capable of being changed.

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: A color image forming apparatus includes a plurality of image carriers for at least one color, a plurality of developing devices, each developing a toner image onto each image carrier, a plurality of charging devices, each charging the each image carrier, a first power source, connected to the developing devices in common, a second power source, connected to the charging devices in common, and a controller, changing a process control of at least one of the charging devices and the developing devices in accordance with a color image forming operation and a monochrome image forming operation.

Abstract: An image forming apparatus includes a plurality of developing devices each including a developer carrying member for carrying a developer to develop an electrostatic latent image formed on an image bearing member, and a developer regulating member for regulating the developer carried on the developer carrying member; common voltage applying means for applying a common voltage to the plurality of develop our regulating members, wherein a first one of the developer carrying members is rotating, and a second one of the developer carrying members is not rotating, a potential difference between the second developer carrying member and the common voltage is smaller than a voltage difference between the first developer carrying member and the common voltage.

Abstract: A developing device used with an electrophotographic image forming apparatus and developing method thereof includes a power supplying unit which applies a first electric field to a toner transfer body and a supplying member so that the toner is supplied to the toner transfer body when a development operation is performed, and applies a second electric field to the toner transfer body and the supplying member so that the toner is removed from the toner transfer body when the development operation is not performed, by varying a developing bias and a supplying bias.

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: 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 regulates an amount of the developer carried on the developer carrying member; and a controller 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: An image forming apparatus operates in such a way that when the conditions of toner changes due to changes in environmental conditions, changes with age, and replacement of an EP cartridge, the bias voltages for a charging roller, a developing roller, and a toner-supplying roller are set appropriately. An electrostatic latent image can be formed on a photoconductive body. The developing roller causes developer to adhere to the electrostatic latent image to develop the electrostatic latent image. The toner-supplying roller supplies the developer to the developing roller. The current measuring section measures a current flowing through at least one of the developing roller and the toner-supplying roller. An voltage-setting section sets at least one of the developing roller and the toner-supplying roller to a corresponding one of first voltages, the first voltages being set in timed relation with development of the electrostatic latent image.

Abstract: An image forming apparatus includes an image bearing drum, a developing roller, a toner-supplying roller, and a controller. The developing roller deposits toner to an electrostatic latent image formed on the image bearing drum. The toner-supplying roller is spaced a distance in the range of 0.05 to 1.0 mm from the developing roller and supplies toner to the developing roller. The controller applies a first voltage to the developing roller and a second voltage to the toner-supplying roller. The difference between the first voltage and the second voltage is greater than 130 volts and lower than a voltage above which electrical discharge occurs across the developing member and the toner-supplying roller. The toner-supplying roller has a surface with ridges and valleys formed therein, which extend in a longitudinal direction of the toner-supplying roller. The ridges have a height in the range of 10 to 1000 &mgr;m.

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 high image quality electrophotographic image forming apparatus is provided without increasing the size and cost, and reducing the life thereof. The potential difference (contrast potential) between a photoreceptor and a development roller for supplying toner to the photoreceptor by the use of a carrier is set to be smaller in the non-image area irrelevant to the printing operation, and set to be larger in the image area relevant to the printing operation. In this manner, the damage to the photoreceptor caused by the adhesion of the carrier is reduced in the non-image area irrelevant to the printing operation, and the fog is reduced in the image area relevant to the printing operation.

Abstract: An electrophotographic print engine has a variable primary charger and toning bias which places the machine in abnormal reproduction modes in order to provide service and diagnostic information to troubleshoot subsystems involved in the electrophotographic process.

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 developing apparatus includes a developer container for containing a developer containing toner and carrier particles having a volume resistivity of 106-1010 &OHgr;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 &OHgr;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 &OHgr;cm.

Abstract: An image forming apparatus and a method of controlling a development voltage include a photosensitive body, a charger which charges the photosensitive body, a laser scanning unit (LSU) which forms an electrostatic latent image by radiating light onto the photosensitive body, a developing unit which develops the electrostatic latent image by supplying a developing agent to the photosensitive body to form an image, a transfer unit which transfers the developed image onto a sheet of paper, a surface potential measuring unit disposed on the surface of the photosensitive body between the developing unit and the transfer unit to measure a surface potential of the photosensitive body, a comparator which compares the surface potential of the photosensitive body before a development voltage is supplied to the developing unit, with the surface potential of the photosensitive body after the development voltage is supplied to the developing unit, to calculate a deviation, and a controller which sets a new development vol