Abstract: In an image forming apparatus in which a DC bias is applied to charge a photosensitive drum, when a charge eliminating device is in deterioration or failure, there are some cases where a proper charging is not made, and thus poor imaging occurs. A DC bias is applied to a charging member in the charge eliminating operation area of an image bearing member where the charge eliminating device makes charge eliminating operation; and based on the values of an electric current passing through the image bearing member on that occasion, a DC bias application is switched between by constant-current-control and by constant-voltage-control.

Abstract: An image forming method, includes a charging step of charging an image carrier; an image writing step of writing image data onto the image carrier; a developing step of developing a latent image area written by the image writing step on the image carrier; a transferring step of transferring a toner image developed by the developing step to a transferring member; an image writing position adjusting step of detecting a position of the image carrier where the image is written in a case where designated conditions are satisfied, and of adjusting an image writing position; and a voltage output control step of controlling voltages applied for charging, developing, and transferring in the charging step, the developing step, and the transferring step, respectively.

Abstract: The invention provides a charging device including a charging roll and a voltage application unit which is capable of applying to the charging roll a voltage in which an alternating current voltage is superimposed on a direct current voltage, the alternating current (Iac) which flows through the charging roll satisfying the following Equation (1), the charging roll satisfying the following conditions (a) to (c), and the charging roll contacting an image supporter to charge the image supporter: Iac/I(inflection)?1.2 ??Equation (1) (in the Equation (1), I(inflection) represents the flexion point of lac) (a) the fluctuation of the outside diameter is 0.1 mm or less (b) resistance (common logarithm) is 9.0 log·? or less (c) resistance variation (common logarithm) is 0.5 log·? or less.

Abstract: An image formation apparatus includes: a photoconductor that has a photoconductive layer having a surface on which an electrostatic latent image is formed; a charging roll to which a bias with an AC component superposed on a DC component is applied for charging the photoconductor at a predetermined potential; a film thickness detector that detects a film thickness of the photoconductive layer of the photoconductor without applying the AC component; an environment measuring section that measures at least one of ambient temperature and humidity; an AC component setting section that sets a value of the AC component of the bias based on detection results of the film thickness detector and the environment measuring section; and a charging controller that controls at least one of voltage and current applied to the charging roll based on the value of the AC component set by the AC component setting section.

Abstract: An image forming apparatus includes a photoreceptor having on a surface thereof a photosensitive layer, in which an electrostatic latent image is formed, a contact charging roll applied with a bias containing a direct current component having superimposed thereon an alternating current component, the contact charging roll charging the photoreceptor to a predetermined potential, a film thickness detecting unit detecting a film thickness of the photosensitive layer of the photoreceptor, an environment detecting unit detecting environment, and a contact area changing unit changing a contact area between the contact charging roll and the photoreceptor based on detected results of the film thickness detecting unit and the environment detecting unit.

Abstract: Embodiments herein comprise a charging station adjacent a photoreceptor. The charging station is adapted to charge the document zone of the photoreceptor with a first negative voltage and to charge the inter-document zone of the photoreceptor with a second negative voltage that is more negative than the first negative voltage. The second more negative voltage reduces the amount of positive charges trapped within layers of the inter-document zone of the photoreceptor. Thus, when the charging station increases the size of the document zone from a smaller size associated with a smaller printing medium to a larger size associated with a larger printing medium, by reducing the positive charges from being trapped within layers of the inter-document zone of the photoreceptor, ghosting is reduced on the larger printing medium.

Abstract: An image forming apparatus is provided with an image bearing member, a charging member with a discharge wire and a grid, and a first current supply controlling member, which controls a current supply to the discharge wire. Also provided are a second current supply controlling member, which controls a current supply to the grid, a potential setting member, which sets a potential value on the image bearing member to be charged by the charging member, and a first current supply condition selecting member, which selects a current control condition of the first current supply controlling member or the second current supply controlling member according to the set potential. In addition, a second current supply condition selecting member selects a current control condition for the other current supply controlling member based on the determined current control condition.

Abstract: This invention relates to an image forming apparatus including an image forming unit which forms an image on a medium for each page, and a notification unit which, when image formation start instructions cannot be successively issued to the image forming unit for successive pages to be formed on media, notifies the image forming unit of the interval between the instructions. The image forming unit shifts to a stop state when the notified interval exceeds a predetermined time.

Abstract: An image formation apparatus is provided and includes: a photoconductor; a charging section that applies a bias voltage having an AC voltage superposed on a DC voltage to the photoconductor so as to charge the photoconductor; a controller that controls at least one of the AC voltage and an AC current in response to a fluctuation amount of a DC current flowing between the photoconductor and the charging section when an AC voltage is applied; and a detector that detects the DC current.

Abstract: An image formation apparatus includes: a photoconductor; a charging section that applies a bias voltage having an AC voltage superposed on a DC voltage and charges the photoconductor; a controller that controls at least one of the AC voltage and an AC current applied by the charging section; and a detector that detects an amount of discharge occurring between the photoconductor and the charging section. The controller controls at least one of the AC voltage and the AC current so that the amount of discharge detected by the detector falls within a predetermined range containing a singularity in change of the amount of discharge.

Abstract: An image forming apparatus is provided in which on-surface potential unevenness of an image carrier can be suppressed, and with which an output image having excellent on-surface uniformity of color or the like can be obtained. The image forming apparatus includes: a photoconductive image carrier; charger which charges the image carrier; image exposing unit which exposes an image on a surface of the image carrier after the charging to form a latent electrostatic image; developing unit which develops the latent electrostatic image by adhering toner to the latent electrostatic image to form a toner image; and transfer charger which transfers the obtained toner image to a final supporting member such as plain paper.

Abstract: When image forming is performed by the photosensitive drum according to operating conditions corresponding to an image forming mode selected out of a predetermined plurality of candidates, the actual cumulative number of printed sheets Pi is corrected and recorded based on the image forming mode (monochrome mode or color mode; low-temperature and low humidity ambience mode or other ambience mode) selected at the time of each image forming (S7) and an adjustment volume (ko×Pia) of the charging applied voltage Ey is calculated and the charging applied voltage Ey is set based on the corrected cumulative number of printed sheets Pia (S5). As a result, the applied voltage Ey to a charging unit is changed according to the cumulative number of printed sheets and at the same time, a pace of change thereof is adjusted based on the image forming mode.

Abstract: An image forming apparatus includes a photosensitive member, a charging device, a developing device, a thickness detecting unit and a parameter setting unit. A photosensitive layer is formed on a surface of the photosensitive member. The charging device charges the photosensitive member. The developing device forms a toner image on the surface of the photosensitive member. The thickness detecting unit detects a thickness of the photosensitive layer on a basis of a value of a current supplied to the charging device. When the thickness detecting unit detects the thickness of the photosensitive layer, the parameter setting unit sets at least one of a charge parameter for the charging device and a development parameter to be different from that used in forming an image on a recording medium by transferring a toner image formed on the surface of the photosensitive member onto the recording medium.

Abstract: A method of operating an electrostatographic printing apparatus, the apparatus including a charge-retentive member defining an imaging surface and a charging device for placing a charge on the imaging surface, a gap existing between the imaging surface and the charging device, including applying an electrical bias to the charge-retentive member by generating a burst modulated waveform.

Abstract: An image forming apparatus operating in a double-sided print mode, includes a charger for charging an image carrier, a charge voltage loader for applying a charge voltage to the charger, an image forming device for forming an image on a recording material, and a controller for controlling the charge voltage applied by the charge voltage loader to the charger. When an image is formed on both sides of a plurality of recording materials, the controller changes the charge voltage applied by the charge voltage loader from a first to a second voltage when an image is formed on first and second sides of the recording material in a period in which an image is formed on the recording sheet, and does not change the charge voltage during an interval between a first recording material and a second recording material to the second charge voltage.

Abstract: A memory medium is provided to a cartridge detachably mountable to an image forming apparatus. Into the memory medium, as information for performing charge control, information on the amount of usage of an image-bearing member and information on a charging alternating voltage (a threshold value for selection control of a charging peak-to-peak voltage Vpp) are written. The image forming apparatus includes a charging-bias power-supply circuit, on its body side, including AC oscillation output circuit capable of outputting two or more species of alternating peak-to-peak voltages and an AC detector for detecting an alternating current passing through the image-bearing member. Charge control is performed on the basis of a detected value detected by the AC detector and memory information for the cartridge, whereby good charge control space saving, and cost reduction of the power-supply circuit are compatibly realized.

Abstract: An output of a DC high voltage source is supplied as a bias to a heat fixing apparatus. An output of the DC high voltage source is divided by resistors, and a divided output is supplied as a DC bias to a charging apparatus. A feedback circuit generates a feedback signal corresponding to a difference between the divided output and a reference voltage, for supply to the DC high voltage source thereby controlling the divided output voltage at a desired value. Such structure allows a supply of a bias voltage to the heat fixing apparatus higher than the bias voltage to the charging apparatus, thereby eliminating defects in the fixing apparatus such as a fixation tailing or an offset phenomenon. Also the charging apparatus can be given an exactly controlled bias voltage, thereby avoiding a halftone density unevenness resulting from an uneven charging.

Abstract: A charging device including: a first charger which charges a member to be charged, the first charger having conducting particles which come into contact with the member to be charged; a second charger which charges the member to be charged in a same polarity as charging polarity of the first charger on an upstream side of the first charger in a moving direction of the member to be charged; and a controller which controls application of a charging voltage to the first charger, in which the controller turns a charging voltage on or off in an area of the member to be charged which is not subjected to charging by the second charger.

Abstract: The white vector—the voltage difference between white areas of a latent image on a photoconductive unit and a developer roller—may be independently adjusted at each photoconductive unit, allowing multiple image forming units to be driven from a shared power supply. The photoconductive unit is charged to a high voltage level relative to the developer roller, and selectively optically discharged to the desired white vector. The voltage of the discharged area may be measured, or may be calculated by increasing the developer roller voltage a predetermined amount, discharging the photoconductive unit until toner is sensed in white image areas, and then reducing the developer roller voltage. The white areas may be discharged using a lower optical power from the writing light source or a different light source, such as a laser, LED or electroluminescent source. A second laser may be of a different wavelength than a writing laser.

Abstract: After an application of a first AC voltage for selecting a peak-to-peak voltage of a charging AC voltage for charging an image forming area of an image bearing member and before an application of a charging AC voltage, there is applied a second AC voltage having a peak-to-peak voltage larger than a peak-to-peak voltage of the first AC voltage.

Abstract: The image forming apparatus includes a rotatable image bearing member, a charging member that is contactably provided to the image bearing member and that charges the image bearing member with a voltage containing an AC component and a DC component; and a control device that makes selection on whether a mode, in which a rotation time of the image bearing member is prolonged and in which a voltage is applied to the charging member in the prolonged rotation time, is performed or not. As a result, the image forming apparatus is provided which performs charging with high stability.

Abstract: An image forming device is provided that is capable of easily preventing occurrence of stripe-like image noise that may be caused by intimate contact between a contact electrifying member and an image carrier even when an image forming operation is stopped for a while. In the image forming device having an electrifying roller in contact with a photoconductor, AC voltage is applied to the electrifying roller before the image carrier and the electrifying roller start rotating.

Abstract: This invention relates to an image forming apparatus including an image forming unit which forms an image on a medium for each page, and a notification unit which, when image formation start instructions cannot be successively issued to the image forming unit for successive pages to be formed on media, notifies the image forming unit of the interval between the instructions. The image forming unit shifts to a stop state when the notified interval exceeds a predetermined time.

Abstract: A charging apparatus includes a charging section supplied with an AC voltage and for electrically charging a member to be charged; a current measuring section for measuring a current flowing between the charging section and the member to be charged when the AC voltage is supplied to the charging section; and a particular current extraction section for extracting from the current a particular current having a particular frequency.

Abstract: There is disclosed in an IOI system which predicts surface potentials of a photosensitive drum positioned in developing positions of individual developing devices from detection results of the surface potentials by two surface potential sensors per developing device, disposed before/after the developing device of each of the plurality of image forming units before/after expose and which controls a charging device in such a manner that a predicted value of the surface potential before the expose indicates a defined developing reference value and which controls an exposing device in such a manner that the predicted value of the surface potential after the expose indicates a defined expose reference value. The image forming units of second and subsequent colors, a charging amount by the charging device is controlled in consideration of charging histories by the charging devices of previous colors.

Abstract: An image forming apparatus has a charging member opposed to an outer circumferential surface of a rotating object to be charged. The image forming apparatus has a voltage applying section for applying a pulsating voltage Vsp between the charging member and the object to be charged. The pulsating voltage Vsp is obtained by superimposing a voltage component of a direct current on a voltage component that periodically changes. The image forming apparatus is made to satisfy a relation of Vpp?|Vth|, where Vpp is a peak-to-peak voltage value of the pulsating voltage Vsp and Vth is a charging start voltage value of the object to be charged. The relation prevents opposite charge from being imparted to residual toner on the object to be charged.

Abstract: A method of maintaining a surface charge on a photoreceptor within a predetermined voltage range is provided, comprising the steps of providing a charging device adjacent to a surface of the photoreceptor, determining a reference voltage to be applied by the charging device to the photoreceptor surface to establish a first photoreceptor surface voltage, and applying the reference voltage to the surface of the moving photoreceptor with the charging device while measuring a first photoreceptor current. The method further comprises comparing the first photoreceptor current to predetermined characteristics of the photoreceptor to calculate a first output value, comparing the first output value to predetermined characteristics of the photoreceptor and calculating a first correction voltage, and applying the first correction voltage to the photoreceptor surface with the charging device to obtain a surface voltage on the photoreceptor that is within the predetermined operational voltage range.

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: A method of operating an electrostatographic printing apparatus, the apparatus including a charge-retentive member defining an imaging surface and a charging device for placing a charge on the imaging surface, including the steps of: providing a power supply to apply a bias to the bias charging roll; and applying a bias to the bias charging roll, the applying includes applying a burst modulated waveform to the bias charging roll.

Abstract: An electrophotographic image-forming apparatus and a charging voltage control method therefor. The electrophotographic image-forming apparatus has a charging roller applying a predetermined voltage to a photosensitive medium, a developing roller for developing with a developing agent an electrostatic latent image formed on the photosensitive medium by a laser scanning unit, a transfer roller transferring onto a sheet of recording paper the image developed by the developing agent, and a high voltage power supply (HVPS) applying predefined voltages to the respective rollers.

Abstract: A memory medium is provided to a cartridge detachably mountable to an image forming apparatus. Into the memory medium, as information for performing charge control, information on the amount of usage of an image-bearing member and information on a charging alternating voltage (a threshold value for selection control of a charging peak-to-peak voltage Vpp) are written. The image forming apparatus includes a charging-bias power-supply circuit, on its body side, including AC oscillation output circuit capable of outputting two or more species of alternating peak-to-peak voltages and an AC detector for detecting an alternating current passing through the image-bearing member. Charge control is performed on the basis of a detected value detected by the AC detector and memory information for the cartridge, whereby good charge control space saving, and cost reduction of the power-supply circuit are compatibly realized.

Abstract: Systems and methods for setting up grid voltage for a tandem pin charging device for charging a photoreceptor in a xerographic printing machine. A charge-generating emitter ratio of a first charging unit is determined and a first grid voltage is set based on the charge-generating emitter ratio of the first charging unit. A charge-generating emitter ratio of a offset voltage is then determined and a second grid voltage is set, based on the determined charge-generating emitter ratio of the offset voltage. A final voltage of a photoreceptor is then compared with a final target voltage.

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: A charger charges a body with a voltage in which an AC voltage is superimposed on a DC voltage. The charger and the body have a small gap therebetween. A sensor measures a humidity in the gap between the charger and the body. A magnitude of the AC voltage to be superimposed on the DC voltage is determined based on the humidity detected.

Abstract: The present invention is a charging device that electrically charges an object that is charged while being moved in a predetermined direction and an image forming device having such a charging device. The charging device has: a charging member that electrically charges the charged object; a power source that supplies electric power to the charging member in order to electrically charge the charged object; a contact member arranged downstream relative to the charging member as viewed in the moving direction of the charged object and adapted to contact the charged object directly or by way of a predetermined intermediary medium; an ammeter that gauges an electric current caused to flow through the contact member due to an electric charge on the charged object electrically charged by the charging member; and a power source control section that controls the power source based on the electric current gauged by the ammeter.

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: This invention provides an image forming apparatus where the useful life of the image carrier does not become significantly short. This system has a charging unit, a charge voltage loading unit, an exposure unit, a development unit, an image transfer unit and a control unit, wherein, when the transport interval of the plural recording materials is shorter than a predetermined time the AC charge voltage applied to the image carrier during the transport interval being a first AC charge voltage, and when the transport interval is longer than the predetermined time the ac charge voltage applied to the image carrier during the transport interval being a second AC charge voltage, the control unit makes the current running in the charging unit to which the second charge voltage is applied lower than the current running in the charging unit to which the first AC charge voltage is applied.

Abstract: Provided is an image forming apparatus including a unit for controlling each voltage value of peak-to-peak voltages of DC and AC voltages applied to a charging unit for charging an image bearing member, in which a residual charge eliminating unit conducts charge elimination on a surface of the image bearing member while at least the charging unit undergoes an application of the AC voltage including the peak-to-peak voltage that is, in the case of setting at Vth a discharge start voltage to the image bearing member when applying the DC voltage to the charging unit, twice or smaller than this discharge start voltage Vth.

Abstract: An image forming apparatus includes an image bearing member capable of being rotated, a first charging unit, an electrostatic image forming unit, a developing unit, and a second charging unit. The first charging unit is capable of being rotated in the same direction as a rotational direction of the image bearing member with being in contact with the image bearing member, and is capable of charging the image bearing member and toner on the image bearing member. The electrostatic image forming unit is capable of forming an electrostatic image on the image bearing member charged by the first charging unit. The developing unit is capable of collecting the toner on the image bearing member and visualizing the electrostatic image.

Abstract: An image forming apparatus includes a charging unit for charging an image bearing member, an image forming unit for forming a toner image on the image bearing member that has been charged, and a cleaning unit for contacting the image bearing member to clean the surface of the image bearing member. In the apparatus, a ratio of a period wherein the image bearing member is moved without being charged to a period wherein the image bearing member is moved while being charged, is controlled to be a predetermined value or greater.

Abstract: The invention relates to a method for operating an electrophotographic printing device (10). A multilevel character generator (22) is used in said printing device (10). Correction parameters (K1, K2, K3) are determined for light coding values (1, 2 and 3) such that a high-quality printed image can he obtained also in the instance of modified printing conditions.

Abstract: An AC voltage from a power generating circuit is applied to a charge roller. CPU controls the power generating circuit so as to flow a constant current according to a control value through a current path from the power generating circuit to the charge roller. CPU produces an information according to an peak value of the AC voltage applied to the charge roller. CPU produces an information according to the AC voltage applied to the charge roller when the AC voltage is in a predetermined phase.

Abstract: Systems and methods for measuring and setting grid voltages in an image forming device may include setting a first charging device of a first image forming station to a first voltage level and setting a second charging device of the first image forming station to be off; charging a charge-retentive surface with the first charging device set at the first voltage level; measuring and the charge imparted to the charge-retentive surface by the first charging device; storing the measured charge value. Systems and methods may further include repeating the setting, charging, measuring and storing steps for the first charging device for at least one additional voltage level; and determining at least one parameter of the first charging device based on the stored measured charge values for the first charging device for each voltage level.

Abstract: An image forming apparatus to which a process cartridge is detachably mountable, the process cartridge including an image bearing member, a charging member for electrically charging the image bearing member, and a memory medium having a memory area for storing information relating to a charging current for a non-image-formation period; the apparatus including a control unit for switching a voltage to be applied to the charging member in accordance with the information stored in the memory medium.

Abstract: An image forming apparatus which can prevent the electric discharge when the trailing edge of a recording material passes a transferring position, and yet can stabilize the surface potential of a photosensitive drum. A controller changes a transfer bias voltage Vt during the supply of paper to 0 V before the trailing edge of recording paper arrives at a transferring nip part, changes it to a transfer bias voltage V0 during the non-supply of paper after the trailing edge of the recording paper has passed the transferring nip part, and changes a charging bias voltage to a charging bias voltage smaller than a normal charging bias voltage when an area on the photosensitive drum to which 0 V has been applied passes a charging nip portion. The transfer bias voltage V0 during the non-supply of paper is smaller than the transfer bias voltage Vt during the supply of paper.

Abstract: An image forming apparatus includes an image bearing member; a charging member, contactable to the image bearing member, for electrically charging the image bearing member at a charging position; developing means for developing an electrostatic image formed on the image bearing member with a developer; wherein when a first area on the image bearing member which is going to be an image formation area is at the charging position, the charging member moves with a peripheral speed difference relative to the image bearing member, and when a second area on the image bearing member which is a part of an area which is going to be a non-image formation area is at the charging position, the charging member moves substantially without a peripheral speed difference relative to the image bearing member, and wherein a collecting electric field is formed for collecting the developer from the second area to the developing means.

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: In a case where a rotating speed of an intermediate transfer member is reduced during the process of image formation, carriers may adhere to a photosensitive member before the rotating speed of the intermediate transfer member stabilizes. To cope therewith, in changing an image formation speed in accordance with a conveying speed of a recording material on completion of primary transfer, a developing rotary is rotated so as to keep any developing device off a developing position. Consequently, a situation in which the carriers adhere to an image bearing member can be avoided. At the same time, stopping a charging operation of a charger enables a longer service life of the image bearing member.

Abstract: According to the present invention, in an image-forming apparatus having at least two chargers for charging a rotating image carrier, in accordance with change in bias applied to a second charger disposed on the downstream side in a rotational direction of the image carrier, the bias applied to a first charger disposed on the upstream side is changed. Thereby, the electric power required for the charging is reduced.

Abstract: A charging voltage controller of an image forming apparatus includes a charging roller charging a photoconductive drum with a predetermined charging voltage, a high voltage supply unit supplying the predetermined charging voltage to the charging roller, an electric current detecting unit detecting an electrical current flowing the charging roller, and a control unit supplying first and second test voltages of different degrees to the charging roller, determining a first reference voltage to be applied to the charging roller based on data from the electric]current detecting unit outputted in response to the first test voltage, calculating slope data based on the electrical current data detected from the electric current detecting unit in response to the first and second test voltages, and determining the charging voltage to be applied to the charging roller as a sum of the first reference voltage and a preset offset voltage that corresponds to the slope data.