Abstract: A developing unit includes a developer bearing member that rotates and bears a developer including a toner and a carrier. A controller switches between a first mode and a second mode based on information which influences a toner charging amount. In the first mode, the developer bearing member rotates during a predetermined operation period from a command of an image forming operation until start of forming the electrostatic latent image. Meanwhile, in the second mode, a total number of rotations of the developer bearing member during the predetermined operation period is smaller than that in the first mode.

Abstract: A developing device includes a developer bearing member for bearing a developer so as to develop an electrostatic image, a restricting member for restricting the amount of developer born on the developer bearing member, a detector for detecting information on the amount of developer existing between the developer bearing member and the restricting member, and a controller which can change a value of a voltage to be applied to the restricting member during image formation based on a result detected by the detector.

Abstract: A developing unit develops a latent image with a developing agent. A supply unit supplies, to the developing unit, a developing alternating current bias voltage with a waveform having a pulse period during which a rectangular wave is output and a blank period during which no rectangular wave is output. An input signal generation unit generates, as an input signal be supplied to a primary side of a transforming unit that forms the developing alternating current bias voltage, an input signal obtained by adding an additional pulse smaller in width than the rectangular wave in the pulse period at a timing to transit from the pulse period to the blank period.

Abstract: An image forming apparatus includes a photoreceptor, a developing apparatus, a developing bias supply power source, a control section for controlling a developing bias, a density sensor, and an arithmetic section. When an image density adjustment operation is performed, the arithmetic section determines a print-time developing bias in accordance with a detection result obtained by detecting, by the density sensor, a plurality of image density adjustment toner images formed by changing a developing bias. The print-time developing bias is set by the control section when printing is performed. also, In a case where a previous print-time developing bias falls within at least a low range of a predetermined range of the developing bias, the arithmetic section determines the print-time developing bias to a value between a reference developing bias for a target image density and the previous print-time developing bias.

Abstract: An image forming apparatus includes a developing device that uses a developer carrier to advance to an image carrier a developer including a toner and a carrier and supplies the toner to the image carrier by applying a developing bias between the developer carrier and the image carrier. In the image forming apparatus, the following operation is performed before the developer in the developing device is taken out. The toner is supplied to the image carrier by applying the developing bias between the developer carrier and the image carrier, the developing bias increased in a direction to supply the toner to the image carrier. The toner supplied onto the image carrier is not transferred to a transfer receiving material but is advanced into a toner recovery device for recovery. The recovered toner is prevented from being returned to the developing device.

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: An image forming apparatus includes: a photoconductive drum; a developing roller carrying toner; a DC voltage application portion outputting a DC voltage to be applied to the developing roller, and receiving a feedback voltage; an AC voltage application portion applying an AC voltage to be applied to the developing roller; a detection portion detecting occurrence of electric discharge; a first resistor portion generating a feedback voltage that is fed to the DC voltage application portion; a second resistor portion connected between the DC voltage application portion and the AC voltage application portion, and having a switching portion with which conducting on and off are switchable; and a control portion controlling the switching portion, at the time of printing, to bring the second resistor portion into a conducting state and, at the time of electric discharge detection, to bring the second resistor portion into a non-conducting state.

Abstract: The present invention provides a method and apparatus for forming an image. A controller manages a charger and a developing bias voltage to increase an absolute value of the charging voltage to an image-bearing member and an absolute value of a developing bias voltage to a developer-bearing member to predetermined values in a plurality of steps. The controller controls the developing bias voltage applied to the developer-bearing member; wherein the following relation holds in each of the plurality of steps: |VD|>|Vi|, where VD represents a developing bias voltage applied to the developer-bearing member and Vi represents a charged potential of the image-bearing member. This invention is especially useful for mono-component development using DC voltage as a development driving mechanism.

Abstract: An image forming apparatus includes a power supply supplying a plurality of developing devices with a first voltage to develop toners on an image carrier, and a voltage divider supplying some of the developing devices not connected to the power supply with the first voltage or a second voltage.

Abstract: An image forming apparatus includes an image bearing member, a toner image forming member, an intermediary transfer member for forming a primary transfer portion, and a primary transfer member supplied with a transfer voltage. The apparatus also has a voltage source for supplying, to the primary transfer member, a transfer voltage and a voltage of a polarity opposite to the transfer voltage, an image bearing member cleaning apparatus for removing toner from the image bearing member, a secondary transferring member, and an intermediary transfer member cleaning apparatus for electrostatically removing toner from the intermediary transfer member. The apparatus further has a voltage source control apparatus for controlling the voltage source so as to apply, to the primary transfer member, a voltage having an absolute value larger than a discharge threshold and having the polarity opposite to the transfer voltage, when a non-recording toner pattern passes through the primary transfer portion.

Abstract: An image forming apparatus includes an image bearing member having a photosensitive layer; toner image forming means for forming a detection toner image not to be formed on a recording material on the image bearing member; detecting means for optically detecting the detection toner image; control means for controlling a toner image forming condition of the toner image forming means on the basis of a result of detection of the detecting means; a transfer member for electrostatically transferring a toner image from the image bearing member onto a transfer material at a transfer region; constant voltage control means for providing a constant voltage applied to the transfer member; and voltage applying means for applying to the transfer member, when the detection toner image passes the transfer region, a predetermined voltage, controlled by the voltage control means, which has the same polarity as a charge polarity of toner.

Abstract: An image forming apparatus includes a photoconductive medium electrified by an electrifying apparatus to a predetermined electric potential, a plurality of color developing apparatuses which are fixed around the photoconductive medium, each color developing apparatus having a developing roller to adhere a predetermined color toner to an electrostatic latent image formed on the photoconductive medium by a laser scanning unit, and a supplying roller to supply a toner to the developing roller, a voltage supplying apparatus to apply a predetermined bias voltage to the developing roller and the supplying roller, and a controlling apparatus to control a degree and a timing of applying the bias voltages to the developing roller and the supplying roller to control a movement state of the toner between the supplying roller and the developing roller.

Abstract: The image forming apparatus includes image forming parts, a developing device and a cleaner to clean at least the intermediate transfer material or the transfer device, wherein at the image forming operation starting time, in each image forming part, after starting the charging, the application of the developing bias is started before the top end of the charging portion of the image bearing member surface reaches a developing area in which the image bearing member and the developer bearing member are set against each other, and from among the areas on the image bearing member in which the charging is not yet performed in each image forming part, in case each area having passed the developing area when the developing bias is applied is brought into contact with the intermediate transfer member, the contact area with each area in the intermediate transfer member is controlled without superposing on the intermediate transfer member.

Abstract: A high developing voltage supply apparatus includes solenoid power switches, and a high developing voltage driver selectively outputting a solenoid driving signal to close one of the solenoid power switches to electrically close a corresponding mechanical contact, applying a high developing voltage to one of color development rollers corresponding to the mechanical contact closed and Kased on an image to be printed. A high developing voltage supply supplies the high developing voltage to developing roll shafts of the other color development rollers to stabilize potentials of the developing roll shafts, or, in the alternative, the high developing voltage supply apparatus may include a voltage supply supplying a self-biased voltage to the other color development rollers using the high developing voltage formed with a DC voltage VDC and an AC voltage VAC superimposed.

Abstract: A multi color image forming apparatus includes a plurality of stations arranged side by side for forming unique mono-color toner images using mono-color developers each having a different mono-color toner. Each of the plurality of stations includes an image bearing member for bearing a latent image, and a developing device for visualizing the latent image into the mono-color toner image. A conveying device is provided to convey a transfer medium. A transfer device is provided to transfer the mono-color toner images from the image bearing members to the transfer medium. Charge ability of prescribed mono-color toner included in the mono-color developer used in the upstream station is smaller than that used in the downstream station.

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: In an image forming apparatus having a reverse development system and using a two-component developer, respective potentials applied when charging an image bearing member and when applying a development bias to a developer bearing member are attenuated when the image bearing member is driven for an operation other than an image forming operation, compared to respective level of potentials applied when the image bearing member is driven for the image forming operation. Thus, an occurrence of an adhesion of a carrier to an image bearing member is reduced to produce a high quality image, when a power switch of the apparatus is turned off or when a door of the apparatus is opened while the image bearing member is driven for an operation other than the image forming operation, or when the apparatus is activated again after the power switch is turned off.

Abstract: A developing device, includes; a developing roller supporting and conveying mono component toner to a photoreceptor having a static latent image; a supplying roller pressed against the developing roller and rotated so as to supply the toner to the developing roller. In order to perform beneficial supply of the toner to the developing roller, bias voltages are applied so as to generate an electric field which will cause the toner between the developing roller and the supplying roller to be attracted to the developing roller. At a predetermined time before completion of development, the bias voltage applied to the supplying roller is switched so as to create an electric field which will cause the toner to be attracted to the supplying roller. Thus the toner residing between the developing roller and supplying roller after development is removed, whereby it is possible to prevent toner from sticking to that area on the developing roller, after development.

Abstract: An image forming apparatus includes a plurality of image forming units each including a single image carrier, a single writing device and a plurality of developing means each including a single developing roller for developing a latent image formed on the image carrier by the writing device with a developer to thereby produce a toner image. The image forming units are spaced by a preselected distance along the same surface of an intermediate image transfer belt to which the toner image is to be transferred from the image carrier. A selecting device causes the developing means to selectively perform development. A single bias power source applies a bias voltage for development to the developing means. A bias switching device applies the bias voltage output from the bias power source to one of the developing means selected by the selecting device according to the outputs of sensors respectively included in the image forming units.

Abstract: In a developing apparatus of the present invention, a voltage applying circuit applies a developing bias voltage obtained by superimposing a DC component on an AC component to the developer carrying member. A bias voltage controller controls the voltage of the DC component based on at least one of a voltage range between the highest and lowest voltages of a waveform of the developing bias voltage and the ratio of time during which the waveform has a value higher or lower than a reference voltage to one period of the AC component. The reference voltage is set so that an area occupied by a portion of the waveform of the developing bias voltage in which the developing bias voltage has a value higher than the reference voltage is equal to an area occupied by a portion of the waveform in which the developing bias voltage has a value lower than the reference voltage.

Abstract: An image forming apparatus includes an image bearing member for bearing an electrostatic latent image; a first developing device for developing the electrostatic latent image on the image bearing member; a second developing device, faced to the image bearing member and having a movable developer carrying member for carrying toner and carrier, for effecting development after a first developed image provided by the first developing device passes through a position where the developer carrying member is faced to the image bearing member; and a preventing device for forming an alternating electric field between the developer carrying member and the image bearing member, while the second developing device is at reset to prevent the carrier of the second developing device from rubbing the first developed image.

Abstract: An image forming apparatus includes an image support which supports an electrostatic latent image on a surface of the image support. A developing unit has a developing agent support which retains a developing agent, including a toner and carriers, contained in the developing unit. The developing unit converts the latent image on the image support into a toner image by causing the toner to adhere to the surface of the image support. A developing bias supplying unit supplies a developing bias voltage to the developing agent support of the developing unit, the developing bias voltage being one of a DC bias voltage and an AC bias voltage. A timer measures a non-driven period of the developing agent in the developing unit.

Abstract: An electrophotographic image forming apparatus prevents the formation of a background image. The apparatus includes a photosensitive drum with a ground plate, and a power supply for applying a negative voltage to the ground plate in the case where the apparatus is powered on after a long time in the power-off state, or where the apparatus is powered on for many hours without forming an image. The applied negative voltage has a potential lower than a critical potential where the toner deposited on a developing roller can move to the photosensitive drum. Further, the negative voltage is applied to the ground plate, only while the charge location on the photosensitive drum rotates to reach a developing position.

Abstract: In an electrophotographic image recording apparatus of the type using a single-ingredient type developer, i.e., toner, a latent image is electrostatically formed on a photoconductive drum or similar image carrier. A developing unit has a developing roller for conveying the toner deposited thereon, and an intermediate roller for conveying the toner transferred thereto from the developing roller and depositing it on the latent image to thereby produce a corresponding toner image. An image transfer unit transfers the toner image to a cut sheet. During the development of an area of the image carrier other than a latent image area, at least one of biases assigned to the developing roller and intermediate roller, respectively, is switched over to thereby form an electric field different in direction from an electric field assigned to the formation of the toner image between the two rollers. As a result, the toner existing on the intermediate roller is collected by the developing roller.

Abstract: A method and apparatus for eliminating undesirable development of background charge potentials in a multicolor electrostatographic system is disclosed, wherein the application of a developer bias at a given development station is selectively controlled to be substantially equal to or greater than the background image voltage of the image generated by a preceding imaging station such that the voltage differential between toner particles at the development station and the background areas including the previous image areas is substantially zero and the electrostatic forces acting on the toner particles are insufficient to attract the toner particles to the residual image.

Abstract: An image forming device includes a plurality of developing devices and a photosensitive drum. Each of the developing devices includes a developer carrying roller. One of the developing devices is moved to a developing position confronting the photosensitive drum which is formed with a latent image. A first developing bias including a d.c. component and an a.c. component is applied to the developer carrying roller and developer on the developer carrying roller is rendered in contact with the latent image on the photosensitive drum so that the latent image is developed. On the other hand, when the developer on the developer carrying roller comes in contact with and separates from the photosensitive drum due to the movement of the developing device, a second developing bias is applied to the developer carrying roller.

Abstract: In an electrophotographic recording apparatus of the type using a single-ingredient type developer, i.e., toner, a developing device has a developing roller for conveying the toner deposited thereon, and an intermediate roller for conveying the toner transferred theretofrom the developing roller and depositing it on a latent image electrostatically formed on an image carrier to thereby produce a corresponding toner image. During the development of an area of the image carrier other than a latent image area, a bias assigned to the developing roller is switched over to thereby form an electric field different in direction from an electric field assigned to the formation of the toner image between the two rollers. Further, before the rotation of the image carrier is stopped, the bias assigned to the developing roller is again switched in order to form the electric field for the formation of the toner image between the rollers. As a result, a toner layer is formed on the intermediate roller.

Abstract: A voltage application timing control unit is connected to a DC component applying unit and an AC component applying unit in a developing bias applying unit. The voltage application timing control unit independently controls the DC component applying unit and the AC component applying unit so as to independently control the timing of applying a DC voltage from the DC component applying unit to the related member and the timing of applying an AC voltage from the AC component applying unit to the same.

Abstract: In an image forming apparatus using a corona discharge type charging device and a contact type image transferring device, a toner deposited on a photoconductive element in the form of a black stripe is prevented from being transferred to the image transferring device; otherwise, the toner would be transferred from the image transferring device to the rear of the following recording medium. Because the toner forming the black stripe is limited to the toner charged to a polarity opposite to an expected polarity, toner consumption ascribable to the stripe is reduced.

Abstract: An image forming device includes a plurality of developing devices and a photosensitive drum. Each of the developing devices includes a developer carrying roller. One of the developing devices is moved to a developing position confronting the photosensitive drum which is formed with a latent image. A first developing bias including a d.c. component and an a.c. component is applied to the developer carrying roller and developer on the developer carrying roller is rendered in contact with the latent image on the photosensitive drum so that the latent image is developed. On the other hand, when the developer on the developer carrying roller comes in contact with and separates from the photosensitive drum due to the movement of the developing device, a second developing bias is applied to the developer carrying roller.

Abstract: An apparatus for supporting wires in a wire module for use in a scavengeless development system using wire maintaining members that longitudinally support the wires. The tops of the wire maintaining members have grooves that positively position the wires and set a desired wire to wire spacing. The wire maintaining members are integral with the wire module and are part of a wire tensioning system. The wire maintaining members are part of an assembly that allow the wires to be pretensioned to the operable development tension prior to the wire module being mounted to the developer housing. The wire maintaining members also have a unique mounting system which allows the wire module to be rotatably mounted to the developer housing.