Abstract: A developing device in an image forming apparatus which having a developing sleeve disposed in face-to-face relationship with a photoreceptor drum, a magnetic roller disposed inside the developing sleeve for forming a magnetic brush of developing material on an outer peripheral surface of the developing sleeve for the developing of a latent image on the photoreceptor drum, and a casing enclosing the developing sleeve and having a portion which is held in contact with the magnetic brush. Portions of the casing are formed of or with a toner adherence preventive material of a type capable of being charged to the same polarity as that of the toner particles when held in frictional contact with the material used to charge the toner particles.

Abstract: A copying apparatus in which a developing bias voltage to be applied to a developing sleeve by a power source is changed to adjust the density of a reproduced image, while the electric potential difference between the developing sleeve and a toner supply roller is kept constant. As a result, a density of toner on the developing sleeve is kept constant. Therefore, a development is effected under the condition in which the density of the toner is constant, so that the tone of the image of an original document is reproduced in a desired density.

Abstract: By utilizing an electrophotographic image forming process, a reversal image can be obtained in the following manner:charging a photosensitive member;forming an electrostatic latent image in a charged surface of the photosensitive member;developing the electrostatic latent image formed on the photosensitive member by using white toner;charging the photosensitive member again;developing the surface of the photosensitive member by using other toner different in color from the white toner; andtransferring the toner image formed on the photosensitive member onto a paper sheet.

Abstract: An image editing method utilizing an electrophotographic process, which method includes a first charging step of charging a photosensitive medium; a step of projecting an image onto the charged photosensitive medium to form an electrostatic latent image; a first developing step of developing the electrostatic latent image into a first powder image by the use of a first toner material having the same polarity as the charged polarity; a first transferring step of transferring the powder image onto a copying paper; a second charging step of again charging the photosensitive medium to a polarity the same as that of the charge established during the first charging step; a step of radiating rays of light to the charged photosensitive medium to remove the electrostatic charge at a specificed area of the photosensitive medium; a second developing step of developing the specified area of the photosensitive medium by the use of a second toner material different in color from the first toner material to form a second po

Abstract: A first developing device is provided in a demountable manner near a photoconductor drum of an electrophotographic copying apparatus. There is further provided a second developing device most downstream along a direction of rotation of the photoconductor drum. Developer containing color toner is stored in the first developing device and developer containing black toner is stored in the second developing device. An outline image forming unit for forming an outline image can be installed in place of the first developing device. When the first developing device is installed, development of a copy image is effected by either the first developing device or the second developing device. When the outline image forming unit is installed in place of the first developing device, an outline image formed by the outline image forming unit is developed by the second developing device.

Abstract: The present invention relates to a method for forming an outline of an image. By this method, at first, an electrostatic latent image bearing member is charged and then irradiated to a negative image to form an electrostatic latent image. Thereafter, the irradiated member is re-charged with a scorotron charger while applying a voltage to a grid, said voltage being lower than the surface potential of the non-image portion of the latent image, being higher than the potential of the image portion of the latent image and being of the same porality as that of the charging. By this re-charging, in one embodiment, the outline portion of the image has lower potential than the other portion. Then, the outline portion of the image with lower potential is visualized with a reversal development by using a toner charged to a polarity same as the polarity of charging.Or in another embodiment, the outline portion of the image has higher potential than the other portion.

Abstract: An improved electrophotographic copier is proposed which includes a first static charger; an image exposure unit; a second charger provided with a grid; and a developer having a developing electrode, all being arranged around a photosensitive rotatable drum.The second charger is impressed selectively with an a.c. voltage or a d.c. voltage which has an opposite polarity to that applied to the first charger. The voltage impressed to the grid has same polarity with that which is applied to the first charger. The developing agent contained in the developer includes such statically charged toner as having an opposite polarity to that of static latent images formed on the drum surface. The copier operates selectively in standard copy mode or in marginal image outline formation mode. The developing service is nevertheless carried out in the normal manner, thus employing no reverse development mode.

Abstract: A method for forming an outline of an image. In this method, at first, an electrostatic latent image bearing member is charged and then irradiated to a positive image to form an electrostatic latent image. Thereafter, the irradiated member is re-charged with a scorotron charger while applying a voltage to a grid, the voltage being lower than the surface potential of the image portion of the latent image, being slightly higher than the background potential of the latent image and being of the same polarity as that of the original charging. By this re-charging, the outline portion of the image is given higher potential than the other portion. Then, the outline portion of the image with higher potential is subjected to a normal development by using a toner charged to a polarity opposite to the polarity of the recharged portions.

Abstract: A method for forming an outline of an image. By this method, at first, an electrostatic latent image bearing member is charged and then irradiated to form an electrostatic latent image. Thereafter, the irradiated member is re-charged with a scorotron charger while applying a voltage to the scorotron grid, the voltage being slightly lower than the surface potential of the image portion of the latent image, and being substantially higher than the background potential of the latent image and being of the same polarity as that of the charging. By this re-charging, the outline portion of the image is given lower potential than the other portion. Then, the outline portion of the image with the lower potential is developed by a reversal development by using a toner charged to a polarity the same as the polarity of charging of the latent image bearing member.

Abstract: An electrophotographic copying apparatus is capable of forming outline images. It comprises a first charging device, an exposing device, a second charging device and a developing device along a moving direction of a photoconductor. A sensor detects an amount of toner adhering to a reference image formed on the surface of the photoconductor. Supply of toner is controlled based on the detected amount. In an outline image forming mode, an amount of toner to be supplied is set to a value smaller than an amount in a standard image forming mode.

Abstract: A developing apparatus which includes a developing sleeve rotatably provided to confront an object to be developed, a magnet roller incorporated within the developing sleeve so as to be driven for rotation in the same direction as the developing sleeve, and a supply device for supplying developing material onto the peripheral surface of the developing sleeve. The developing apparatus is so arranged as to satisfy such conditions asD.multidot..pi..multidot.Wsl>d1.multidot.p.multidot.WmgwhereD: developing sleeve diameter (mm)Wsl: developing sleeve revolutions (rpm)d1: the closest distance between the sleeve surface and the object to be developedp: number of poles of the magnet rollerWmg: revolutions of the magnet roller (rpm).

Abstract: The copier machine of the present invention comprises a second charger having a grid and is capable of executing a mode wherein a toner is deposited onto the latent image exclusive of the outline portion thereof to visualize.When this mode is designated, the grid is applied with the voltage which is lower than the surface potential at the image portion of the latent image and higher than the surface potential at the non-image portion of the latent image.