Abstract: An image It is formed as a patch image which includes a header image portion Ih of a solid image having a length of a circumferential length of a developing roller or more, and a gradation image portion Ig progressively varied in the tone level thereof from the maximum level to the minimum level. The densities of the patch image on an intermediate transfer belt are sampled. However, the sampling results contain errors resulting from noises or variations and hence, are subjected to a noise removal process, a periodical variation correction process and a reverse correction process. The results detected on the intermediate transfer belt do not always coincide with image densities (OD values) on a recording material. Therefore, the detection results are converted into the OD values, based on which tone characteristics of an apparatus is estimated. Then a tone correction table is updated in a manner to compensate for the tone characteristics.

Abstract: In a density control technique wherein a density of a toner image formed as a patch image is detected for performing density control based on the detected result, detection errors are decreased so as to properly set a density control factor. The density control factor is optimized based on a variation rate of the patch image densities against a varied density control factor. The detected results of the patch image densities are corrected based on information on an image carrier acquired before the formation of the patch images.

Abstract: A condition controlling process is executed when parameters expressing a state of toner within a developer reaches predetermined threshold values. On each one of two parameters, namely, a dot count value which is indicative of a toner consumption amount (an integrated value of the number of dots formed using an exposure beam) and a developer roller rotating time which is indicative of the degree of toner fatigue, a threshold value (denoted at the dotted lines) which triggers execution of the condition controlling process is set. At the time that the path d of dots which are expressed as combinations of these parameters intersects each dotted line (the intersections (1) through (6)), the condition controlling process is executed.

Abstract: Output signals Vp from a density sensor are sampled for plural positions on an intermediate transfer belt and an amount of toner adhesion is determined based on the results of sampling. Since these sample data pieces may contain noises, each predetermined number of data pieces of higher order and of lower order are removed from the resultant sample data string. The removed data pieces are each replaced by an average value Vpavg of the other sample data pieces. The amount of toner adhesion is calculated based on the data string thus replaced.

Abstract: For optimization of a direct current developing bias Vavg, a patch image Ivn is formed whose length is longer than a circumferential length L0 of a photosensitive member. From an average value of sensor outputs sampled over the length L0 of the patch image, a toner density of the patch image Ivn is calculated and a value corresponding to an average value ODavg of optical densities OD is accordingly found. This cancels an influence of density variations appearing in association with rotating cycles of the photosensitive member exerted over a patch image.

Abstract: Optimization of a density control factor accompanying formation of a patch image is executed every time a predetermined period of time elapses since the end of a preceding image forming operation. Since an image is formed at regular intervals in this manner, it is possible to suppress a density variation which is created as toner carried on a developer roller is left unused for long. This effect further improves when the developer roller is rotated idle prior to formation of a patch image or regularly at predetermined timing.

Abstract: After forming solid patch images under various patch generating conditions (E, Vb), the optical densities of the respective patch images are measured by a patch sensor, and patch generating conditions matching with a higher-density side target density (OD=1.2) are extracted as “higher-density side correlation data.” Further, line patch images are formed under various patch generating conditions (E, Vb), the optical densities of the respective line patch images are measured by the patch sensor, and patch generating conditions matching with a lower-density side target density (OD=0.2) are extracted as “lower-density side correlation data.” An optimal exposure energy and an optimal developing bias are set based on one piece of correlation data (E2, Vb(3)) belonging to said product set of the higher-density side correlation data and the lower-density side correlation data.

Abstract: An OPC 2, a charger 9, a cleaner 10 for cleaning the charger 9, a holder 11 for holding the charger 9, a support frame 12 for supporting the holder 11, a pair of springs 13 and 14 and a driver 15 for driving the holder are accommodated in a single process cartridge 8. The cleaner 10 can be brought into contact with the charger 9 and separated from the same. The driver 15 moves the cleaner 10 between a position of contact at which the cleaner 10 is brought into contact with the charger 9 and a position of separation at which the cleaner 10 is separated from the charger 9. The charger 9 has a wettability that is lower than that of a photosensitive member on which an electrostatic latent image is formed.

Abstract: After forming solid patch images under various patch generating conditions (E, Vb), the optical densities of the respective patch images are measured by a patch sensor, and patch generating conditions matching with a higher-density side target density (OD=1.2) are extracted as “higher-density side correlation data.” Further, line patch images are formed under various patch generating conditions (E, Vb), the optical densities of the respective line patch images are measured by the patch sensor, and patch generating conditions matching with a lower-density side target density (OD=0.2) are extracted as “lower-density side correlation data.” An optimal exposure energy and an optimal developing bias are set based on one piece of correlation data (E2, Vb(3)) belonging to said product set of the higher-density side correlation data and the lower-density side correlation data.

Abstract: An OPC 2, a charger 9, a cleaner 10 for cleaning the charger 9, a holder 11 for holding the charger 9, a support frame 12 for supporting the holder 11, a pair of springs 13 and 14 and a driver 15 for driving the holder are accommodated in a single process cartridge 8. The cleaner 10 can be brought into contact with the charger 9 and separated from the same. The driver 15 moves the cleaner 10 between a position of contact at which the cleaner 10 is brought into contact with the charger 9 and a position of separation at which the cleaner 10 is separated from the charger 9.

Abstract: An OPC 2, a charger 9, a cleaner 10 for cleaning the charger 9, a holder 11 for holding the charger 9, a support frame 12 for supporting the holder 11, a pair of springs 13 and 14 and a driver 15 for driving the holder are accommodated in a single process cartridge 8. The cleaner 10 can be brought into contact with the charger 9 and separated from the same. The driver 15 moves the cleaner 10 between a position of contact at which the cleaner 10 is brought into contact with the charger 9 and a position of separation at which the cleaner 10 is separated from the charger 9.

Abstract: A contact charging device includes: a member to be charged rotatably provided; a conductive member having a soft endless thin film shape, for charging or discharging the member to be charged such that the conductive member is electrostatically attracted to the member to be charged as the member rotates; and a supporting member, disposed apart from the member to be charged, for holding the conductive member while resisting the electrostatic attracting force such that the conductive member is stretched, to allow the conductive member to rotate together with the member to be charged.

Abstract: A charger capable of reliably and uniformly maintaining a discharging gap formed in the vicinity of a contact portion between a charging member and a photosensitive member. A charging member 101 is arranged by supporting and fixing both ends of a flexible film 102 by means of support members 103 to 105. The film 102 forms a flexible portion oriented downwardly from fixed ends S1, S2. The film 102 is brought into contact with the member 110 to be charged in a state in which an unsupported side of the film 102 is oriented toward the downstream side in the rotating direction of the member 110 to be charged. Then, the film 102 is brought into contact with the member 110 to be charged in a contact area N, and the radius of curvature of the film 102 in a zone P2 located downstream of that zone N in the rotating direction of the member 110 to be charged becomes smaller than the radius of curvature of the film 102 in an upstream zone P1.

Abstract: A contact charge supply device for externally controlling the charges, which are supplied to a member to be charged by bringing a contact member appled with an external voltage into contact with the member to be charged, which at least includes an underlayer, and holds the following inequalitylog (R).gtoreq.log {Rp.times.(Va-Vt)/Vt}+(.alpha.-.beta.).times.log(S/s)+.gamma..times.log (i/I)where .vertline.Va.vertline..gtoreq..vertline.Vt.vertline.,Va (V): voltage applied to a contact member in contact with the member to be charged; I (.mu.A): current flowing from the contact member to the member to be charged; S (cm.sup.2): contact area of the member to be charged and the contact member; R (.OMEGA.): resistance of the contact member when current I (.mu.A) is fed to an area corresponding to the contact area S (cm.sup.2) of the contact member; .gamma.: current dependency of the resistance of the contact member; 1-.beta.: area dependency of the resistance of the contact member; s (cm.sup.

Abstract: A method and apparatus for replenishing depleted portions of an ink layer of an ink sheet formed with a conductive ink layer disposed on an insulating layer from which ink has been transferred, without unintentionally supplying ink to undepleted portions of the ink layer are provided. Electrically conductive replacement ink is charged and supplied onto an intermediate transfer roller having a dielectric layer disposed on an electrically conductive layer. Charge is supplied to the insulating layer side of the ink sheet and replacement ink on the intermediate roller contacting the ink sheet at depleted regions of the ink sheet is transferred from the intermediate roller to the depleted portions by electrostatic attraction and not to undepleted portions. The method and apparatus are adaptable for multi-color ink sheets and can be employed in connection with a printer or image forming device.

Abstract: An electrophotographic image forming member for forming color images including an organic photosensitive layer sandwiched between a dielectric layer and a conductive layer. The photoconductive layer includes a first charge generation layer adjacent to the conductive layer, a charge transfer layer on the first charge generation layer and a second charge generation layer on the charge transfer layer. During exposure, resistance of the photosensitive layer is reduced so that charges can flow through the photosensitive layer to create oppositely charged portions of the image forming member corresponding to a desired image of each color. Appropriately charged color toner adheres to the surface of the image forming member in the form of the desired image. After each color toner image is formed, the completed color image is transferred to a transfer medium.

Abstract: A method and apparatus for replenishing depleted portions of an ink sheet including a conductive ink layer on a dielectric layer wherein portions of ink have been transferred to a transfer medium. Conductive replacement ink material is supplied to the ink sheet and an electric charge is induced in the replacement ink and opposite charges are induced at an electrode on the opposite side of the dielectric layer. Replacement ink contacting the dielectric layer at the voids will adhere to the ink sheet, but charges in the replacement ink contacting the non-transcribed ink regions will flow to the conductive ink layer and will not adhere to the ink sheet.

Abstract: An electrophotographic image forming member for forming color images including an organic photosensitive layer sandwiched between a dielectric layer and a conductive layer. The photoconductive layer includes a first charge generation layer adjacent to the conductive layer, a charge transfer layer on the first charge generation layer and a second charge generation layer on the charge transfer layer. During exposure, resistance of the photosensitive layer is reduced so that charges can flow through the photosensitive layer to create oppositely charged portions of the image forming member corresponding to a desired image of each color. Appropriately charged color toner adheres to the surface of the image forming member in the form of the desired image. After each color toner image is formed, the completed color image is transferred to a transfer medium.

Abstract: A combination toner for xerographic image formation having conductive portions and insulating portions is provided. The conductive portions function to accumulate a charge in the toner particles and the insulating portions function to lengthen the period of discharge of the accumulated charge. The toner can be either magnetic or non-magnetic and improves image formation and transfer.

Abstract: A method for replenishing depleted portions of an ink sheet including a conductive ink layer on a dielectric layer wherein portions of ink have been transferred to a transfer medium. Conductive replacement ink material is supplied to the ink sheet and an electric charge is induced in the replacement ink and opposite charges are induced at an electrode on the opposite side of the dielectric layer. Replacement ink contacting the dielectric layer at the voids will adhere to the ink sheet, but charges in the replacement ink contacting the non-transcribed ink regions will flow to the conductive ink layer and will not adhere to the ink sheet.