Abstract: In an image forming method, an electrostatic latent image formed on a surface of a photoreceptor is developed into a developer image with a developer, and a printing paper transported on a transfer belt is brought into contact with the surface of the photoreceptor so as to transfer the developer image onto the printing paper. The printing paper is transported in a proper transport direction, in which a projection generated in one direction on the printing paper as a result of cutting the printing paper in a printing paper manufacturing process does not face a surface of the transfer belt at a leading edge of the printing paper being transported on the transfer belt. In this way, even in the presence of the projection generated when the printing paper is cut, the printing paper naturally strips off from the surface of the photoreceptor, thereby preventing toner contamination caused by a striping claw in contact with the leading edge of the printing paper.

Abstract: In an image forming apparatus, an electrostatic latent image formed on a surface of a photoreceptor is developed into a toner image. A printing paper transported on a transport belt is brought into contact with the surface of the photoreceptor and an electric field is applied to the printing paper from a rear surface of the transport belt by a transfer roller to transfer the toner image onto the printing paper. The transfer roller applies different levels of electric field to the printing paper, so that a predetermined transfer electric field is applied to a region other than a leading edge of the printing paper being transported. An electric field weaker than the predetermined transfer electric field is applied to the leading edge. Even in the presence of a projection generated when the printing paper is cut, the printing paper naturally strips off from the surface of the photoreceptor.

Abstract: A transfer device includes a transfer device controller for controlling the whole transfer device, a storage for storing various kinds of data etc. necessary for control, an intermediate transfer unit including a primary transfer power supply and its driver, a secondary transfer unit including a secondary transfer power supply and its driver, and a PTC unit. In the transfer device, a controller communicates with a main controller that controls the whole image forming apparatus, and acquires, for example, information on the total print count or the like. When PTC radiation is determined to be needed based on the above information, the controller controls to drive the PTC unit.

Abstract: An image forming apparatus according to the present invention comprises a cylindrical photosensitive body, a transfer unit, a fixing unit and a paper guide. The photosensitive body carries an image on it. The transfer unit includes a transfer roller in compressive contact with the photosensitive body. The fixing unit includes a heating roller and a pressing roller. The paper guide is positioned between the transfer and fixing units. The photosensitive body and the transfer roller are so arranged that the nip tangent between this body and this roller inclines toward the paper guide away from a line connecting the nip between this body and this roller and the nip between the heating and pressing rollers. The paper guide has a recess formed nearer the nip between the is photosensitive body and the transfer roller than the midpoint on the line connecting the two nips.

Abstract: A feed roller assembly includes a shaft, a plurality of rollers, and a plurality of covers. The rollers are fixed to the shaft at intervals along it. The covers are positioned at both ends of the rollers and surround the shaft, without being fixed to it. Paper dust falls from the outer cylindrical surfaces of the rollers and accumulates on the covers, without coming into direct contact with the cylindrical surface of the shaft. Because the covers are not fixed to the cylindrical surface of the shaft, they rotate at a lower speed than the shaft.

Abstract: A cleaning member for cleaning the toner remaining on the outer peripheral surface of a heat roller that fixes an unfixed developer image formed on a sheet of paper onto the paper by heating under pressure, includes: a mesh portion having a predetermined mesh in the area abutting the heat roller. The mesh portion is formed of heat resistant wires.

Abstract: A charging device includes a rotatable screw gear, a motor, a support, and a protruding member. The screw gear is positioned along length of a linear electrode. The motor rotates the screw gear in forward and reverse directions. The support holds the cleaning member mounted so as to be in contact with the electrode, and is mounted unrotatably but reciprocably between a first end and a second end of the electrode. The member extends perpendicular to the length of the electrode from the support, and has a projection for being elastically fitted into a thread groove of the screw gear along a radial direction of the screw gear. The member is configured in such a manner that a distance between a starting point of elastic deformation of the member and a contact point between the projection and a thread of the screw gear differs according to whether the support is moved forward or backward.

Abstract: In an image forming apparatus of the present invention, an idle roller once stops rotating when a front edge of a sheet conveyed reaches the idle roller. The idle roller restarts rotating at such a timing that a front edge of a toner image on a photoreceptor and a front edge of an image writing position on the sheet are aligned with each other. Then, even if a rear edge of the sheet is still in the idle roller, the idle roller stops rotating when the front edge of the sheet is sandwiched between a transfer roller and the photoreceptor. By carrying out such operations, it is possible to avoid by a very simple way an occurrence of a slip phenomenon that is a phenomenon of slipping of the sheet with respect to the photoreceptor while suppressing a reduction in image quality as much as possible. In addition, it is also possible to surely secure a blank space formed at a rear edge portion of the sheet.

Abstract: An image forming apparatus and a maintenance method thereof are provided to enable rotation and replacement of a peeling claw at a suitable timing before the peeling claw is deformed or damaged. Several peeling members are disposed in a width direction of a drum-shaped photoreceptor. Each peeling member is disposed with a peeling claw and a collision sensor detecting that the peeling claw collides with a sheet. A collision history value of each peeling claw is stored and managed based on a collision detection signal from the collision sensor; if the peeling claw reaching a preset rotation request value exists in the read collision history values of the peeling claws, a rotation request of the relevant peeling claw is reported; the collision history value of the rotated peeling claw is rewritten; and if the peeling claw reaching the rotation request value does not exist, a print process is performed.

Abstract: A transfer mechanism includes: a transfer unit having a transfer belt; and a belt contact and separation assembly for bringing the transfer belt into, and separating it away from, an electrostatic latent image support by shifting the position of the transfer unit. The belt contact and separation assembly includes: a multiple number of transfer unit shifters that abut the transfer unit and shift the position of the transfer unit; a multiple number of linkage members that link with the plural transfer unit shifters, correspondingly; an elastic member for coupling the plural linkage members; and a driver for actuating the transfer unit shifters through the linkage members.

Abstract: A charging device includes a long electrode, a cleaning member, a timing device, a drive source, a load measuring device, and a control device. The drive source moves the cleaning member in the outward direction for a first time period after the outward passage time and then reverses the cleaning member in the homeward position. The load measuring device measures driving load imposed on the drive source while the cleaning member is being moved. The control device controls motion of the drive source to turn the cleaning member from the outward direction to the homeward direction at a predetermined objective point near the second end, based on sum of driving loads imposed on the drive source while the cleaning member is being moved from the first point to a second point located along the outward direction.

Abstract: An intermediate transfer belt cleaning unit includes a cleaning blade put in sliding contact with the surface of a circulating intermediate transfer belt and a blade holder for holding the blade, the cleaning blade having a length extending across the width of the intermediate transfer belt, the blade holder being formed along the full length of the cleaning blade, for cleaning the surface of the intermediate transfer belt by means of the cleaning blade. In this cleaning unit, the contact pressure of the cleaning blade against the intermediate transfer belt is adjusted so that the contact pressure around both the side edges of the intermediate transfer belt is higher than the contact pressure in the remaining part.

Abstract: In an image forming apparatus of the present invention, a scorotron charging device has a meshed grid electrode which is meshed more coarsely in a high-speed apparatus than a meshed grid electrode in a low-speed apparatus according to a circumferential velocity of a photoreceptor. With this arrangement, it is possible to charge the photoreceptor at a predetermined potential in the high-speed apparatus, without increase of the amount of ozone generation and upsizing of the image forming apparatus.

Abstract: A transfer device is configured to include a drive roller, a driven roller and a transfer belt supported between these rollers and provided with first and second guide ribs extending circumferentially at both side edges on the undersurface thereof and a drive roller, so as to prevent the transfer belt from skewing by making the drive roller and driven roller abut at both ends against first and second inner circumferential surfaces of the first and second guide ribs. The drive roller and the driven roller are specified to have a length approximately equal to each other and shorter than the spacing between the first and second inner circumferential surfaces and arranged such that the first spacing between a first end of the drive roller on the drive gear side and the first guide rib is wider than the second spacing between a second end of the driven roller on the drive gear side and the first guide rib.

Abstract: An image forming apparatus carries out an image processing with respect to a sheet size and image information based on a print request to obtain a write image on a photoreceptor. On the basis of a printing ratio of the write image, the apparatus predicts occurrence of an image elongation. If the apparatus predicts that the image elongation occurs, the apparatus calculates a bending amount of a bended portion based on the difference between peripheral velocities of a photoreceptor and the idle roller, and the apparatus variably controls the peripheral velocity of an idle roller so that the bending amount is adjusted so as not to cause a slip phenomenon. It is possible to avoid the occurrence of a phenomenon of slipping of a sheet with respect to the photoreceptor without lowering image quality, and to surely secure a blank space formed at a rear edge portion of the sheet.

Abstract: An image forming apparatus is provided. When a user inputs a print request, life count values stored in a life management section are read out. A table of correlation between the life count values and a rotating speed of a driving roller is looked up, a rotating speed of the driving roller corresponding to the life count values read out is determined at which the driving roller is set to rotate. With the driving roller rotating at the set rotating speed, a printing process is performed so that a transfer belt turns at a constant running speed. Following the printing process, the life count values are updated based on the latest total number of printed copies and the latest revolving speed of the transfer belt.

Abstract: There is provided an image forming apparatus that is capable of reducing work burdens imposed on a user in terms of toner cartridge replacement. When a cartridge detection sensor detects that at least one of toner cartridges is emptied, a specified amount of toner is forcibly supplied from another toner cartridge than the toner cartridge subjected to detection to an intermediate hopper. After that, the amount of the toner within the another toner cartridge is detected. When an empty toner cartridge is newly detected, a request for replacement is issued as to both of the newly detected empty toner cartridge and the previously detected empty toner cartridge.

Abstract: A belt carrying device includes supporting rollers, an endless belt supported by the supporting rollers, and guiding members provided on the endless belt. The endless belt is rotated by rotation of the supporting rollers. An outer peripheral surface of the endless belt is in contact with a cleaning member. The guiding members are provided on those projecting areas of the endless belt, which project in an axial direction of the supporting rollers from both end surfaces of the supporting roller. A guiding member suppresses meandering of the endless belt by coming into contact with an end surface of the supporting roller. Formed on the end surfaces of at least one of the supporting rollers are projecting sections and groove sections, which are rotated around a rotation axis of the at least one of the supporting rollers in response to rotation of the at least one of the supporting rollers.

Abstract: A transfer device includes a transfer device controller for controlling the whole transfer device, a storage for storing various kinds of data etc. necessary for control, an intermediate transfer unit including a primary transfer power supply and its driver, a secondary transfer unit including a secondary transfer power supply and its driver, and a PTC unit. In the transfer device, a controller communicates with a main controller that controls the whole image forming apparatus, and acquires, for example, information on the total print count or the like. When PTC radiation is determined to be needed based on the above information, the controller controls to drive the PTC unit.

Abstract: An image forming apparatus of the present invention carries out an image processing with respect to image information which is to be printed. The image forming apparatus predicts the occurrence of an image elongation which may occur due to slippage of a recording material with respect to the electrostatic image drum, and specifies an image elongation occurring area on the basis of a printing ratio of the image information. If the occurrence of slippage, and thus image elongation is predicted, the amount of the image elongation occurring area to be shortened is calculated. The image information is then modified to obtain write image information that is shortened based on the calculated shortening amount. This write image information is then used to form the electrostatic latent image that is developed and transferred to a recording material. Thus, even slippage does occur, it is possible to accurately form the desired image on the recording material.