Abstract: An image forming apparatus of the present invention includes an intermediate image transfer belt to which a toner image is to be transferred from an image carrier, an image transferring device for transferring the toner image from the intermediate image transfer belt to a sheet, and a fixing device for fixing the toner image on the sheet. When the length of the sheet in the direction of conveyance is smaller than a distance between the image transferring device and the fixing device, a matching circuit varies only the speeds of the image transferring device and fixing device, but does not vary the speed of a device that executes a step preceding the image transfer step. The matching device then sets an interval between consecutive sheets matching with the varied speeds of the image transferring device and fixing device, thereby matching opposite sides with respect to the image transfer step to each other as to the number of sheets to be conveyed.

Abstract: A transfer device that transfers color visual images of different colors from image carriers to each of first and second sides of a recording medium. The transfer device includes a transfer element that holds and moves the recording medium, transfer bias applying devices that apply transfer biases to the recording medium by the transfer element to transfer the color visual images from the image carriers to the recording medium, respectively, and an adsorbing bias applying device that applies an adsorbing bias to the recording medium to adsorb the recording medium to the transfer element. A polarity of the adsorbing bias applied to the second side of the recording medium is opposite to that of electric charge given to the recording medium due to electric discharge generated when the recording medium is separated from the image carriers after passing through transfer nip parts formed between the image carriers and the transfer bias applying devices.

Abstract: A charge roller that includes a metal core, an elastic member configured wrapped around the metal core, and film members is disclosed. Each of the film members is wrapped around each end of the elastic member in a circumferential direction of the metal core such that at least a part of each of the film members exists at every position around the ends of the elastic member in an axial direction of the metal core. Portions of the film members do not overlap each other in an radial direction of the metal core.

Abstract: A charge roller that includes a metal core, an elastic member configured wrapped around the metal core, and film members is disclosed. Each of the film members is wrapped around each end of the elastic member in a circumferential direction of the metal core such that at least a part of each of the film members exists at every position around the ends of the elastic member in an axial direction of the metal core. Portions of the film members do not overlap each other in an radial direction of the metal core.

Abstract: An image forming apparatus of the present invention includes a plurality of image carriers sequentially arranged in a direction of paper conveyance. Developing devices each form a toner image of particular color on one image carrier associated therewith. Cleaning devices each remove residual toner left on the surface of the associated image carriers after the transfer of the toner image to the recording medium. A toner recycling device is provided between the cleaning device located at the most upstream position in the direction of paper conveyance and the developing device associated therewith, but not provided between the cleaning device located at the most downstream position the developing device assigned therewith. With this configuration, the apparatus obviates troubles ascribable to the mixture of toner of different colors occurring in the most downstream developing device.

Abstract: An image forming apparatus includes an image bearing member on which an electrostatic latent image is formed, the image bearing member including a protective layer on a surface thereof, a developing device configured to develop the electrostatic latent image with toner to which an external additive is added to form a toner image, and a toner replenishing device configured to contain the toner and to supply air to the toner to replenish the developing device with the toner.

Abstract: To prevent deterioration of charge performance, which is caused by wear of a gap control member that keeps a charge roller into non-contact with the image carrier, the charge roller is brought into contact with a surface of a photosensitive drum via a pair of tape members as the gap control member that contacts with a coat and non-charge portion of the photosensitive drum. A gap G can be formed between an effective charge width portion of the charge roller and the surface of the photosensitive drum.

Abstract: A charging apparatus includes a charging member arranged to be adjacent to a photoconductive member with a gap having a tolerance in a charging region relative to the photoconductive member and applied with a voltage including a direct current voltage under a constant voltage control including an alternating current element to apply a charge to the photoconductive member. The alternating current element has a peak-to-peak voltage at least twice as great as a charge-start voltage to be applied to the charging member at a maximum gap within a range of the gap having the tolerance.

Abstract: To prevent deterioration of charge performance, which is caused by wear of a gap control member that keeps a charge roller into non-contact with the image carrier, the charge roller is brought into contact with a surface of a photosensitive drum via a pair of tape members as the gap control member that contacts with a coat and non-charge portion of the photosensitive drum. A gap G can be formed between an effective charge width portion of the charge roller and the surface of the photosensitive drum.

Abstract: An image forming apparatus includes an image bearing member on which an electrostatic latent image is formed, the image bearing member including a protective layer on a surface thereof, a developing device configured to develop the electrostatic latent image with toner to which an external additive is added to form a toner image, and a toner replenishing device configured to contain the toner and to supply air to the toner to replenish the developing device with the toner.

Abstract: A charge roller that includes a metal core, an elastic member configured wrapped around the metal core, and film members is disclosed. Each of the film members is wrapped around each end of the elastic member in a circumferential direction of the metal core such that at least a part of each of the film members exists at every position around the ends of the elastic member in an axial direction of the metal core. Portions of the film members do not overlap each other in an radial direction of the metal core.

Abstract: A charging device, an image forming apparatus including the charging device, an image carrier unit including the charging device and a charging roller, which faces a body to be charged and is applied with a voltage, are disclosed. The charging roller includes a metallic core and an elastic member covering the core. Films are respectively wrapped around and adhered to the opposite end portions of the elastic member. Springs press the charging roller toward a body to be charged, causing the elastic member to deform due to compression. The maximum deformation of the films, which deform along the outer periphery of the elastic member, is selected to be smaller than the thickness of each film in the radial direction of the charge roller. A gap is therefore formed between the elastic member and the body to be charged. This prevents the portion of the elastic member, which corresponds to an image forming region, other than opposite end portions from contacting the surface of the body to be charged.

Abstract: An image transferring device for image forming equipment and capable of insuring desirable image transfer by obviating premature image transfer, print, and the leak of transfer bias. A belt causes a toner image to be transferred from an image carrier to a transfer medium while conveying it. A bias member applies a charge to the belt. A feedback current from the belt flows through a feedback electrode. A constant current control device executes constant current control such that the difference between a current to flow from the bias member to the belt and the feedback current to flow from the belt to the feedback electrode remains constant. The constant current control is based on PWM having a spatial frequency of either lower than 0.5 cycles/mm or higher than 1.5 cycles/mm.

Abstract: In an image forming apparatus, a toner image is formed on an image carrier and the toner image thus formed is transferred onto a transfer material. The image forming apparatus solves troublesome matters of image quality and a transfer material conveying quality due to temperature and/or humidity variations without employing a separate temperature/humidity sensor. The transfer conveying belt includes at least two layers which are, a first layer having a surface resistance rate of 1-10.sup.10 .about.1-10.sup.16 and a second layer having a surface resistance rate of 1-10.sup.7 .about.1-10.sup.11, and the second layer is constructed with a rubber material having a temperature/humidity variation of electric resistance which is larger than a temperature/humidity variation of electric resistance of the first layer. Such a transfer conveying belt itself is then used as a temperature/humidity sensor.

Abstract: An image forming apparatus capable of producing pure and clear-cut bicolor images stably over a long period of time. After a photoconductive element has been uniformly charged by a first charger, a first latent image is formed on the element by first exposure. The first latent image is developed by a black toner stored in a first developing unit. Subsequently, after the photoconductive element has been charged by a second charger implemented by a scorotron charger, a second latent image is formed on the element by second exposure. The second latent image is developed by a red toner stored in a second developing unit by reversal development. The resulting two toner images are transferred to a recording medium. The grid voltage of the second charger is selected to be lower than the potential deposited on the photoconductive element by the first charger.