Abstract: A developing unit in an electro-photographic apparatus such as a printer, a facsimile and a copier for actualizing an image employing colored particles such as toner, and more particularly to a developing unit for forming a toner image on the surface of a photosensitive body. The developing unit includes a plurality of developing rollers each having a core and a sleeve. The sleeve accommodates the core. The plurality of developing rollers include a first developing roller and a second developing roller. The sleeve for the first developing roller is rotated to move in the same direction as a moving direction of the surface of the photosensitive body. The sleeve for the second developing roller is rotated to move in an opposite direction to the moving direction of the surface of the photosensitive body. The core of only one of the plurality of developing rollers is driven in rotation while the other core is fixed.

Abstract: In an electrophotographic recording device, a multicolor toner image is formed by images in each color superimposed on one another. In order to detect image misalignment, image-forming units form a color registration detection pattern, and sensors detect the pattern and output detection signals. A control unit detects the position of the patterns based on only portions of the detection signals corresponding to leading edges of the patterns.

Abstract: A transfer flow-in current which flows from a transferring device into an image carrier, a separation flow-in current which flows from a separating device into the image carrier, an aperture width in the recording member transporting direction of an aperture of the transferring device, and an aperture width in the recording member transporting direction of an aperture of the separating device are set so as to have the relationship: separation flow-in current=transfer flow-in current×(transfer aperture width/separation aperture width).

Abstract: An electrophotographic cluster printing system for performing printing by using a plurality of electrophotographic recording apparatuses such as printers, facsimile machines or copying machines each capable of manifesting an image by using colored particles such as toner. The electrophotographic cluster printing system includes a plurality of electrophotograhic recording apparatuses each including a photoconductor, a charger, an exposure device, a developing device, and an image quality controller for detecting a factor concerning image quality and controlling image quality of an output image on the basis of information of the detected factor. In the system, at least two of the electrophotograhic recording apparatuses is used for printing one job and image quality of any one of the electrophotograhic recording apparatuses is controlled on the basis of detected information of the other electrophotograhic recording apparatuses.

Abstract: In order to provide a miniature full-color recorder having an excellent color reproducibility and to provide a full-color recorder having a wider color reproduction range beyond the range of subtraction color mixing of three primary colors, first and second potential split developing processes are continuously arranged for one recording medium.

Abstract: A print control method of an electrophotograph in an image formation apparatus including at least a photoconductor, a charger, a light exposure unit, and a developing device for forming a background area and an image area on the photoconductor using the charger and the light exposure unit and detecting a potential of the image area after transfer and controlling a developing electric field, thereby printing an electrophotograph, includes lowering the percentage of toner covering the image area on the photoconductor when the potential is detected.

Abstract: A transfer member transporting section is disposed so as to bring a tip end of a transfer member into contact with a peripheral face of a transfer rotary member before the tip end of the transfer member enters a nip area. A bias power supply has a polarity inverting function of, during a period from a timing when the tip end of the transfer member is brought into contact with the transfer rotary member by the transfer member transporting section, to that when the tip end of the transfer member enters the nip area, applying a voltage of a polarity which is identical with that of a toner, to the transfer rotary member, and after the tip end of the transfer member enters the nip area, applying a voltage of a polarity which is opposite to that of the toner, to the transfer rotary member.

Abstract: An image formation apparatus for keeping secularly stable image quality for all image patterns if change in the charge amount of a developer caused by environment variation or over time or change in the photoconductor characteristic occurs in electrophotographic record apparatus. A test patch image formed on a photoconductor by a parallel electric field is detected by an image density sensor, the developing bias and the photoconductor surface potential are controlled so that the density detected by the image density sensor becomes constant, a test patch image formed on the photoconductor by a peripheral electric field is detected by the image density sensor with the control condition of the image density sensor maintained, and the light application amount in which an image area of a several-dot width adjacent a blank paper part is exposed to light is controlled so that the density detected by the image density sensor becomes constant.

Abstract: An image forming apparatus restricts disturbance of a potential patch in the case where a potential sensor for detecting the potential patch is provided downstream of a developing device of a multiple developing roller type so as to enable stable reproduction of a high quality image for a long period. The apparatus includes a potential sensor provided downstream in the moving direction of the image carrier relative to the developing device for detecting a potential on the image carrier, and a controller for setting the developing bias to a value restricting disturbance of a potential portion as an object for potential detection by the potential sensor by the developer when the potential portion passes across the developing device.

Abstract: A cooling device used in an electrophotographic image forming device includes a cooling roller, which is a heat roller, and a backup roller pressed against the cooling roller to form a nip portion therebetween. After discharged from a fixing device that thermally fixes a toner image onto a recording sheet, the recording sheet passes through the nip portion, whereby the cooling roller cools the recording sheet. The cooling roller is maintained at 100° C. or greater.

Abstract: A developing unit in an electro-photographic apparatus such as a printer, a facsimile and a copier for actualizing an image employing colored particles such as toner, and more particularly to a developing unit for forming a toner image on the surface of a photosensitive body. The developing unit includes a plurality of developing rollers each having a core and a sleeve. The sleeve accommodates the core. The plurality of developing rollers include a first developing roller and a second developing roller. The sleeve for the first developing roller is rotated to move in the same direction as a moving direction of the surface of the photosensitive body. The sleeve for the second developing roller is rotated to move in an opposite direction to the moving direction of the surface of the photosensitive body. The core for at least one of the plurality of developing rollers is driven in rotation.

Abstract: An electrophotographic cluster printing system for performing printing by using a plurality of electrophotographic recording apparatuses such as printers, facsimile machines or copying machines each capable of manifesting an image by using colored particles such as toner. The electrophotographic cluster printing system includes a plurality of electrophotograhic recording apparatuses each including a photoconductor, a charger, an exposure device, a developing device, and an image quality controller for detecting a factor concerning image quality and controlling image quality of an output image on the basis of information of the detected factor. In the system, at least two of the electrophotograhic recording apparatuses is used for printing one job and image quality of any one of the electrophotograhic recording apparatuses is controlled on the basis of detected information of the other electrophotograhic recording apparatuses.

Abstract: In an electrophotographic apparatus, regions having at least three different potential levels Vc, Vw, and Vr are formed on a photosensitive member by using an exposing device, and developing processes respectively using colored particles of different kinds are performed by normal development and reversal development on two potential levels Vc and Vr excluding the intermediate potential level Vw. The apparatus has an auxiliary exposing unit for forming a fringe development preventing potential in an edge of an image forming region in order to prevent fringe development from occurring. The auxiliary exposing unit sets an auxiliary exposure amount by performing pulse-width modulation on a laser driver.

Abstract: A printing system is provided which ensures easy formation of a plate and regeneration of the plate for continued use. The press plate used in a the printing system to form an image using a water-based ink is characterized in that, (I) prior to formation of a latent image, the surface forming the latent image exhibits extra ink-repellency to the ink to be used; (2) the press plate allows a water soluble material forming the latent image to be deposited thereon; (3) the latent image can be formed by allowing the water soluble material to be deposited on the press plate surface; and (4) the press plate can be regenerated as a plate which allows a new latent image to be formed by washing the press plate with water and drying it, upon completion of ensuing processes of development and transfer.

Abstract: A transfer flow-in current which flows from a transferring device into an image carrier, a separation flow-in current which flows from a separating device into the image carrier, an aperture width in the recording member transporting direction of an aperture of the transferring device, and an aperture width in the recording member transporting direction of an aperture of the separating device are set so as to have the relationship: separation flow-in current=transfer flow-in current×(transfer aperture width/separation aperture width).

Abstract: An image formation apparatus for keeping secularly stable image quality for all image patterns if change in the charge amount of a developer caused by environment variation or over time or change in the photoconductor characteristic occurs in electrophotographic record apparatus. A test patch image formed on a photoconductor by a parallel electric field is detected by an image density sensor, the developing bias and the photoconductor surface potential are controlled so that the density detected by the image density sensor becomes constant, a test patch image formed on the photoconductor by a peripheral electric field is detected by the image density sensor with the control condition of the image density sensor maintained, and the light application amount in which an image area of a several-dot width adjacent a blank paper part is exposed to light is controlled so that the density detected by the image density sensor becomes constant.

Abstract: In an image forming apparatus for charging a photosensitive body, changing the light exposure amount in at least three levels at exposure to light, thereby forming an electrostatic image made up of a high-potential part, a low-potential part, and an intermediate-potential part therebetween on the photosensitive body, and normally developing and inversely developing the electrostatic image using toners different in charge polarity for forming two types of toner images on the photosensitive body, a first developer used with a first toner image developing unit has electric resistance changed within 10% in the change range of applied voltage to the developer as the difference between a surface potential of the photosensitive body and a developing bias voltage.

Abstract: In order to provide a miniature full-color recorder excellent in color reproducibility and provides a full-color recorder having a wider color reproduction range beyond the range of subtraction color mixing of the three primary colors, the first and second potential split developing processes are continuously arranged for one recording medium.

Abstract: In an image forming method, when viewed from the moving direction of a photosensitive body 1, there is disposed, on the upstream side, a first developing roller 61 opposed to and adjacent to the photosensitive body 1 and rotatable in the opposite direction to the photosensitive body 1, while the peripheral speed ratio of the roller 61 to the photosensitive body 1 ranges from 0.8 to 2.0; on the downstream side of the roller 61, there is disposed a second developing roller 62 rotatable in the same direction to the photosensitive body 1, while the peripheral speed ratio of the roller 62 to the photosensitive body 1 ranges from 1.05 to 2.0; and the shape coefficient SF1 of the toners of two-component developing agent ranges from 120 to 170, while the shape coefficient SF2 ranges from 110 to 130.

Abstract: An image forming apparatus restricts disturbance of a potential patch in the case where a potential sensor for detecting the potential patch is provided downstream side of a developing device of a multiple developing roller type to enable stable reproduction of a high quality image for a long period. The apparatus includes a potential sensor provided downstream side of moving direction of the image carrier relative to the developing means for detecting a potential on the image carrier, and controller setting the developing bias to a value restricting disturbance of a potential portion as an object for potential detection by the potential sensor by the developer when the potential portion passes across the developing means.