Abstract: A developer unit for developing a latent image recorded on an image receiving member with marking particles, to form a developed image, including: a donor member spaced from the image receiving member and adapted to transport marking particles to a development zone adjacent the image receiving member; a donor voltage supply for electrically biasing said donor member, said donor voltage supply having a donor frequency at a first phase; an electrode positioned in the development zone between the image receiving member and the donor member; an electrode voltage supply for electrically biasing said electrode during a developing operation with an alternating voltage to detach marking particles from said donor member, forming a cloud of marking particles in the development zone, and developing the latent image with marking particles from the cloud, said electrode voltage supply uses frequency generation of the donor AC and wire AC modulation frequencies by integer division of the wire AC oscillator thereby minimizi

Abstract: In a two-color image forming apparatus, correction exposure of creating an area having a potential between an image area potential and a white area potential is made for a decided white area on the periphery of the image area. A potential difference between the image area and white area is reduced to attenuate an edge effect, thereby preventing the fringe development. This is accomplished by varying the light amount for the white areas of the intermediate potential areas as a function of the following: surface potentials measured, change in the developing bias voltage and rotating speed of a developing roll, adjustment of the amount of toners by a toner sensor, changing the resistance of a developer, and/or development of raster image processing.

Abstract: An image forming apparatus using an electrophotographic process including a photoconductor, a development device, and a transfer device, a measuring device measures an electrostatic capacitance between said photoconductor and said transfer device in predetermined conditions while a standard toner image is formed. Humidity of ambient environment is also measured. Then, a controller controls image forming conditions such as a development condition or a transfer condition according to the measured electrostatic capacitance and the humidity. Alternately, a resistance of the paper is measured, and a controller controls image forming conditions according to the measured resistance. In a still different way, an amount of toner charges of a standard toner image is measured, and a controller controls image forming conditions according to the measured amount of toner charges.

Abstract: An electrophotographic image generation device such as an electrophotographic printer comprises an image bearing belt, a development section, a toner image transfer section, a toner concentration sensor, and an electrical charge control section. A latent image due to variations in electric potential is formed on the image bearing belt by irradiation of photo image light. The development section applies a liquid developing agent on the surface of the image bearing belt and thereby changes the latent image into a visible toner image. The toner image transfer section transfers the toner image on the surface of the image bearing belt to the surface of a sheet and thereby executes printing to the sheet. The toner concentration sensor detects the concentration of toner particles in the liquid developing agent.

Abstract: An image forming apparatus includes a photosensitive member and a developer carrying member spaced from the photosensitive member by a gap. The developer carrying member carries a developer containing an externally added strontium titanate. A bias voltage is applied between the photosensitive member and the developer carrying member with a substantially rectangular waveform. This bias voltage forms an oscillating electric field therebetween. The electric field provided by the difference between a jump peak voltage of the bias voltage and the potential of the photosensitive member at a portion exposed to the light is not less than 4.1 V/micron. The electric field provided by a difference between the jump peak voltage and a potential of the photosensitive member at a portion not exposed to light is not more than 3.5 V/micron.

Abstract: In an image forming apparatus, the absolute value (.vertline.VBH-VM.vertline.) of the potential difference between a first development bias electric potential (VBH) and an intermediate electric potential (VM) is set to be smaller (.vertline.VBH-VM.vertline.<.vertline.VBL-VM.vertline.) than the absolute value (.vertline.VBL-VM.vertline.) of the potential difference between a second development bias electric potential (VBL) and the intermediate electric potential (VM).

Abstract: Disclosed is a method for cleaning the contact charger of an electrophotographic apparatus including a photosensitive (photoconductive) drum, developing means, transfer means and main motor, which comprises the steps of applying a charging voltage of a specified level to the contact charger to make the surface of the photosensitive drum keep a surface potential of a given level during rotation of the main motor, cutting off the charging voltage applied to the contact charger and developing voltage applied to the developing means after a specified time so as to transfer the toner of opposite polarity attached to the contact charger to the photosensitive drum, and applying a negative transfer voltage to the transfer means so as to transfer the toner of opposite polarity transferred to the photosensitive drum to a sheet of paper.

Abstract: A switching element and a protective resistance are connected between a developing roller and a developing bias source. A switching element switches on and off a connection between the developing roller and the developing bias source. A protective resistance is connected to the switching element in series. There is a controller and a bias stabilizer. The controller switches on the switching element when a developing bias voltage is to be applied to the developing roller and switches off the switching element when the developing roller is caused to be in an electrically floating state without applying the developing bias voltage, and which bias stabilizer is disposed between the developing roller and a ground and maintains a predetermined stable voltage only when the switching element is switched on. The structure enables a high-quality image to be formed with a low power consumption.

Abstract: A digital copying machine develops an electrostatic latent image formed on a photosensitive drum with toner, and transfers the developed image onto a sheet. In forming images on the photosensitive drum successively, three types of test patterns are formed in order in intro-image areas between image forming areas, and AIDC is made. The first test pattern is a low-density pattern, the second test pattern is an intermediate-density pattern, and the third test pattern is a high-density pattern.

Abstract: This invention relates to a image forming apparatus comprising an image carrier, charging means, image exposing measuring means, surface correction toner image forming means for forming a toner image extending in parallel to a direction of a rotation axis of the image carrier at a non-image area on the surface of the image carrier and a controller for changing a formation condition of the surface correction toner image formed parallel to the direction of the rotation axis of the image carrier at the non-image area on the surface of the image carrier by the surface correction toner image forming means, according to the surface roughness or the physical property value reflecting the surface roughness of the image carrier measured by the measuring means.

Abstract: Operation of a developer so as to achieve reduced scavenging and reduced direct contamination when using a hybrid developer. A hybrid developer is operated in three modes. The first mode is normal operation in which the developer operates as in the prior art. The second mode is an unloaded standby mode wherein toner is not on the developer's donor roll and wherein the developer's bias potentials are selected to reduce scavenging. The third mode is a loaded standby mode wherein toner is on the developer's donor roll and wherein the developer's bias potentials are selected to reduce direct contamination.

Abstract: An electrophotographic reproduction machine including an image bearing member, latent image devices for forming on the image bearing member electrostatic latent images having a first relative polarity, and a hybrid development unit for applying to the latent images correct-sign toner particles having a second polarity relatively opposite to the first polarity. A detecting apparatus adjacent the image bearing member for sensing toner particles developed into non-image regions. The development unit includes a first biasing means including a DC power supply for biasing a magnetic roll mounted within the housing of the hybrid development unit. A second biasing means includes a second DC power for biasing a donor roll mounted which forms a toner transfer nip with the magnetic roll. The DC power supplies is adjusted so that "wrong sign" toner of said first polarity are attracted to the donor roll from the magnetic brush within the housing of the hybrid development unit.

Abstract: An image forming apparatus including, an image bearing member capable of having a latent image formed thereon, and a developer bearing member that bears a developer comprising a toner and a carrier, wherein a latent image formed on the image bearing member is developed by a non-contacting method under application of a vibrating electric field, so that the toner is transferred from the developer bearing member toward the image bearing member, and wherein the following relation holds:1.0.times.10.sup.-4 <t.sub.1.sup.2 /L.sub.T <1.0.times.10.sup.-3 (sec.sup.2 /m),where t.sub.1 represents a phase period during which a toner particle of the toner is transferred from the toner bearing member to the latent image during application of the vibrating electric field and L.sub.T represents a weight average particle diameter of the toner particles.

Abstract: In order to control development condition and/or transfer condition for stable image forming, toner patterns of the same density are formed on a photoconductor and are transferred onto a paper or the like while changing the transfer current. Then, the transfer efficiencies of the toner patterns are measured. Other characteristics such as the resistance of the paper and charge of toners may also be monitored. Then, the development condition and/or transfer condition is controlled according to the detected data.

Abstract: An image formation apparatus comprises an image bearing member, developing means for developing by use of toner the electrostatic image formed on the image bearing member, transfer charging means for transferring the toner image from the image bearing member to a transfer material in the transfer position, and separation means for de-electrifying the transfer material for separating the transfer material from the image bearing member. Then, after the toner image formed on the transfer material for the first time is fixed, the toner image is formed on the same transfer material for the second time. For this apparatus, modifying means is further provided for modifying the development conditions of the first toner image and the second toner image formed on the transfer material, and modifying the adhesive amount of fogging toner adhering to the image background of the toner image on the image bearing member.

Abstract: An image forming apparatus wherein a developer remaining on a photosensitive member after an image transfer process is removed by developing means, the apparatus includes an electrophotographic photosensitive member; a contact charging means including an electrode contacted to the photosensitive member to electrically charge the photosensitive member, the contact charging means being supplied with a bias voltage form a charging bias voltage source; exposure means for exposing the photosensitive member to form an electrostatic latent image thereon after the photosensitive member is electrically charged by the charging means; developing means for supplying the developer from a developer carrying member to a latent image portion of the photosensitive member to develop the photosensitive member and simultaneously removing the developer remaining on the photosensitive member after the transfer process and conveyed to a downstream of the contact charging means on the photosensitive member, to the developer carrying

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 improved method for controlling the optical density of an image printed by an electrostatic printer is provided. The method compensates for optical density drift over the useful life of a toner receptacle by adjusting the voltage vector between the photoconductive belt and the toner particles. The method calculates an overall toner usage amount and adjusts the voltage vector when the amount reaches one or more predetermined values. In this manner, the present method controls the optical density of a printed image over the useful life of the toner receptacle.

Abstract: An image forming apparatus of the present invention is capable of forming an oscillation electric field in a developing region on the basis of the particle size of toner and the particle size of magnetic carrier. Assume that the oscillation electric field includes a phase for causing the toner to move toward a latent image and having a duration t.sub.1, that the electric field has a period T, that the toner has a weight-average particle size of L.sub.t, and that the carrier has a weight-average particle size of L.sub.c. Then, there hold a relation of 1.0.times.10.sup.-4 <t.sub.1.sup.2 /L.sub.t <1.0.times.10.sup.-3 ?sec.sup.2 /m! and a relation of T.sup.2 /L.sub.c <0.005 ?sec.sup.2 /m!. The apparatus insures images with uniform dots and including a minimum of noise.

Abstract: An apparatus in which the developability and interactivity of electrostatically charged particles in a mixture of particulate material is measured. The sensor apparatus includes a transparent member positioned closely adjacent to a developer roller of an electrophotographic printing machine. Electrostatically charged particles are attracted from the particulate mixture being transported by the developer roller to the member. A beam of energy is transmitted through the member. The intensity of the internally reflected beam is detected and a signal generated indicative of the quantity of charged particles adhering to the member. A cleaning field bias is applied, to determine if a signal indicative of the charge particles being removed (interactivity) from the member is generated.

Abstract: A development system including a developer transport adapted for depositing developer material on an imaging surface having an electrostatic latent image thereon, including a housing defining a chamber storing a supply of developer material including toner. A donor member is mounted partially in said chamber and spaced from the imaging surface, for transporting toner on an outer surface thereof to a region opposed from the imaging surface. The toner donor member has a magnetic assembly which includes a plurality of poles and a sleeve, enclosing said magnetic assembly and rotating about said magnetic assembly. A sensor measures a magnetic field of said donor roll at a predefined position on said donor roll. A control system generates an electric field continuously optimize the development of toner regardless of the ever changing height of the developer bed.

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

Abstract: The development of the edges of discharged areas on a photoconductor drum in an electrophotographic printing system is controlled by the ratio of the DC component of the developer bias to the magnitude of the difference between the DC component of the developer bias and the DC component of the bias supplied to the photoconductor charge roller. A development system using a developer, a photoconductor charge roller, a high voltage power supply, an optical density sensor, and a controller for controlling the high voltage power supply optimizes the electrophotographic edge development. The optical density sensor is used in a calibration process to determine the value of the DC component of the developer bias necessary to ensure the optical density of developed areas will meet the minimum specified optical density.

Abstract: The present invention provides an image forming apparatus that suffers less toner particles scattering and a narrower variation in image density. In this image forming apparatus, a decrease of a contrast potential difference can be compensated by means of a developing bias voltage generator circuit and a grid bias voltage generator circuit, so that the image density can be kept constant. The apparatus includes a developing mechanism in which the respective average particle diameters of carrier members and toner particles, toner concentration, and the diameter and peripheral speed of a developing roller are optimized. Although the diameter of the developing roller is small, therefore, a high image density can be secured, and the value of toner particles scattering can be lowered.

Abstract: When an electrophotographic printer is manufactured, the initial electrical resistance of its transfer roller is measured and a corresponding value is stored in a memory device in the printer. During operation, the printer's control program estimates the resistance of the transfer roller from the stored value, taking aging into account, then measures the actual resistance of the transfer roller, and infers ambient conditions from the difference between the estimated and actual resistance values. The electrophotographic printer is controlled according to the inferred ambient conditions.

Abstract: In an electrophotographic image forming apparatus, in order to control image forming conditions, first and second toner images are formed. The first standard toner image has toners of a uniform density, and the second standard toner image has a plurality of dots made of toners with predetermined spaces between them. A light scattered from the first standard toner image and a light normally reflected from the second standard toner image are detected, and image forming conditions are controlled according to the detected lights before an image is formed according to image data. Further, in an image forming apparatus where area gradation is used for forming an image, a plurality of second standard toner images having different area ratios is formed, and gradation can be changed by controlling the image forming conditions according to the lights reflected from the standard toner images.

Abstract: A method for achieving adjusted toner concentration of printed image on a recording medium in an image forming apparatus using an electrophotographic developing process including a photosensitive drum for forming a latent image on its negatively charged photoconductive insulating surface exposed to light according to an image pattern and a developing roller charged with a negative developing voltage to charge by rubbing a toner supplied from a toner supplier with a negative voltage.

Abstract: Cleaning effectiveness is improved, and inadequate charging of the photosensitive member due to soiling of the charging brush as well as image noise such as background fog are suppressed by a developing device capable of recovering residual toner regardless of the toner charge polarity. In an image forming apparatus provided with a developing device including a developing sleeve for developing an electrostatic latent image on photosensitive member via toner and recovering residual toner from the surface of photosensitive member, a power unit is provided for forming a direct current electric field between photosensitive member and developing sleeve during developing, and forming alternating current electric fields between photosensitive member and developing sleeve 16 during cleaning of residual toners.

Abstract: An image forming apparatus including a photoconductive drum, a charger which charges the photoconductive drum, an exposing device which irradiates light to the charged photoconductive drum for forming an electrostatic latent image on the photoconductive drum, a developing device which has two component developer which includes magnetic toner and magnetic carriers and a transfer charger to transfer the developed image to a sheet of paper. The bias voltages of the charger, the developing device and the transfer charger are applied from a common high voltage power source. A developing starting voltage of the developing device is higher than a residual voltage of the photoconductive drum.

Abstract: A developing apparatus is so adapted that in performing development upon converting a developer to a developing area opposite to an image carrying member by a developer carrying member with the developer held on the surface of the developer carrying member as well as alternately repeating an exertion period during which an AC electric field is exerted between the developer carrying member and the image carrying member and a stop period during which no AC electric field is exerted, the AC electric field is exerted in such a manner that the directions of the first and last electric field portions of the AC electric field in one exertion period are the same, and the direction of the last electric field portion of the AC electric field in the exertion period and the direction of the first electric field portion of the AC electric field in the subsequent exertion period after an elapse of the stop period are the same.

Abstract: A technique for controlling a developing voltage of an image forming device, which is capable of properly controlling the developing voltage according to thickness of the printing paper includes: setting a specific printing paper flag according to a key input generated by selection of specific printing paper by a user; checking whether or not the specific printing paper flag is set; and, upon determining that the specific printing paper flag has been set, controlling the developing voltage so as to be a developing voltage value corresponding to the proper amount of toner during forming an image on the specific printing paper.

Abstract: The developing unit of an electrostatic printer is designed to avoid under-development of the bottom part of a dark latent image due to a reduction in recycled toner. This can be accomplished by providing the developing unit with one developing roller and at least two supply rollers. Alternatively, the developing unit has just one supply roller, but the rate at which toner is transferred from the supply roller to the developing roller can be switched. As another alternative, the supply roller and developing roller are designed to turn slowly enough that development of an entire page is completely developed before reaching the point where under-development would begin.

Abstract: In a developing apparatus, a developing roller has a toner layer formed on a surface thereof, which toner layer is brought into contact with a photoconductor. A magnetic conveying roller having a magnet body is arranged rotatively close to the photoconductor. A regulating plate is provided at an outer periphery of the conveying roller.

Abstract: An image forming apparatus of the present invention includes a toner carrier, a counter electrode, and a control electrode, which have the same potential as a ground potential of the image forming apparatus during a non-operational period while a flight electric field-use operational voltage and control voltages are not applied. During an operational period while the operational voltage and the control voltages are applied, a flight suppressing voltage for suppressing flight of the toner in the control voltages is first applied to the control voltage, and thereafter the operational voltage is applied to the counter electrode. When the application of the operational voltage and the control voltage are suspended, the flight suppressing voltage is first applied as the control voltage, then the application of the operational voltage is suspended, and thereafter the application of the flight suppressing voltage is suspended.

Abstract: A nonmagnetic single component developing device comprises a developing roller having an outer surface on which a layer of a nonmagnetic single component developer composed of nonmagnetic toner is formed, a toner supply roller arranged in rear of the developing roller and made into contact therewith, for agitating and supplying the toner, a toner regulating blade arranged above the developing roller and made into press-contact therewith, for regulating a volume of the toner. The toner supply roller is electroconductive, and is applied thereto with an a.c. voltage so as to prevent lowering of the density in the leading and trailing end parts of an image so as to obtain a uniform image characteristic.

Abstract: A voltage that has a difference in potential in the polarity direction opposite to the charge of the developer relative to the voltage applied to the sleeve by power supply 34 is applied to the control member by power supply 36. By this use of power supply 36, when the amount of remaining developer has fallen to a prescribed level, the conveyance of the developer to the photosensitive member by the sleeve is prevented, preventing image formation. Therefore, the image formation operation does not continue where the amount of remaining developer is small, which in turn eliminates the scattering of developer and maintains the cleanliness of the interior of the apparatus.

Abstract: An image forming apparatus performs a stable developing characteristic for an electrostatic latent image including a halftone image expressed by a binary manner. The apparatus includes a photoreceptor having a surface and an electrostatic image forming device for forming an electrostatic latent image on the surface of the photoreceptor, the electrostatic latent image including a digitally-reproduced binary latent image. The apparatus further includes a developing device for developing the electrostatic latent image. The developing device includes a two-component developer including magnetic carrier particles and toner particles. The apparatus also includes a bias applying device for applying a bias voltage between the developing device and the photoreceptor for defining a relatively high contrast potential of the digitally-reproduced binary latent image to be developed.

Abstract: A technique for controlling the developing voltage of an electrophotographic apparatus to accommodate environmental conditions includes: measuring the developing current varying with environmental conditions, and adjusting the high voltage supplied to the developer according to the measured developing current.

Abstract: A toner depletion detection system in an electrophotographic printer uses an optical density sensor to detect the depletion of toner. The optical density sensor is used by the electrophotographic printer to maintain the developed optical density at an optimum value by adjusting a DC offset voltage supplied to a developer to compensate for changes in the developed optical density. Additionally, the optical density sensor is used in a calibration which linearizes the relationship between the optical density of a developed halftone pattern and increments of the laser pulse width. In a first embodiment of the toner depletion detection system, the magnitude of the DC offset voltage supplied to the developer to compensate for changes in the developed optical density is monitored. When the magnitude of this DC offset voltage exceeds an empirically determined threshold value, the toner depletion condition is indicated.

Abstract: An electrophotographic image forming apparatus is disclosed that enables both photosensitive member and developer to be used to the full limit of their service lives. The image forming apparatus selectively adjusts one or another of either a surface potential setting of the photosensitive member or a developing bias voltage in accordance with a condition of the photosensitive member and the developer which is determined based on a fog appearance in output image and value of charged potential of the photosensitive member surface.

Abstract: An electrophotographic recording apparatus including a photosensitive drum, a charging section, an exposure section, a developing section, and a transfer section. The charging section is used for recharging the photosensitive drum. In the electrophotographic recording apparatus, the photosensitive drum is recharged after a developed image is transferred to a transfer sheet. Thus, after the transfer section is stopped, the charging and developing sections remain active for at least a rotation of the photosensitive drum. Accordingly, the electric voltage level of the photosensitive drum is uniform.

Abstract: In an image forming apparatus wherein plural developing devices 3 have alternating electric field applying mechanisms 4, the alternating electric field applying mechanisms 4 have alternating electric field changing mechanisms 7 for reducing the degree of the action of the alternating electric field on at least one of the developing devices 3 which are later in development order, to a level which is lower than that in the preceding step. As required, at least one of the transferring devices 5 which are later in transfer order has a transfer force changing mechanism 8 for increasing the force of transfer to a transfer medium 6 applied to a color-component toner image on an image carrier 1, to a level which is higher than that in the preceding step. Furthermore, an operation condition judging mechanism 9 may judge whether preset transfer failure conditions are satisfied or not, or environmental conditions may be considered by an environmental condition adjusting device 10.

Abstract: A toner discharging member is in contact with a developing sleeve at a position downstream to a developing region at which the developing sleeve (developer carrying member) confronts an electrostatic latent image carrier, extra toner returning to a toner supply region after the development is brought into contact with the discharging member and moves between the discharging member and the developing sleeve, a discharging bias voltage is applied to the toner discharging member, and the discharging bias voltage thus applied is controlled based on a toner charged state, an adhesion state of toner onto the electrostatic latent image carrier, a current flowing through a toner discharging member and others.

Abstract: In an electrophotographic image forming apparatus, the resistance of an transfer material is detected to which a toner image is transferred. The amount of adhered toners of a standard image is detected, and the development bias voltage is controlled according to the detected amount of adhered toners. Then, the transfer voltage is controlled by taking into account the resistance of the transfer material, the charges of adhered toners and the development bias voltage. Thus, the transfer efficiency is stabilized so that a stable image is formed with reproducible colors and densities. For a dot image, an area ratio of a standard dot toner image is detected, and at least one of an amount of charges for charging the photoconductor uniformly, an intensity of the light beam for exposing the photoconductor and the development bias voltage is controlled according to the detected area ratio.

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

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

Abstract: An electrophotographic recording apparatus that removes reverse-charged toner that is charged with a polarity opposite to a polarity of a normal-charged toner. The apparatus includes a carrier belt; a transfer roller for carrying the toner adhering to the surface of the photosensitive body toward the carrier belt; a transfer power supply for applying to the transfer roller a first voltage that causes the normal-charged toner adhering to the surface of the photosensitive body to be transferred to the recording medium on the carrier belt, and a second voltage, of opposite polarity to the first voltage, that causes the reverse-charged toner adhering to the surface of the photosensitive body to be transferred to the carrier belt; and a carrier belt cleaning blade.

Abstract: In a color image forming apparatus, a test pattern is formed by a color toner and provided with multiple tones by a dither method. The toner density of the test pattern is accurately read by a simple structure and faithfully corresponds to the actual toner density.