Abstract: An image forming apparatus includes an image bearing member for bearing a toner image, a movable endless transfer belt for transferring the toner image from the image bearing member onto a transfer material, and a transfer device for transferring the toner image from the image bearing member toward the transfer belt. The transfer device includes a transfer member for sliding on an inner surface of the transfer belt in contact with the inner surface, a supporting member for supporting the transfer member, and an urging member for urging the supporting member toward the transfer belt, wherein the transfer member contacts the inner surface of the transfer belt at a contact surface thereof without rotation relative to the supporting member during movement of the transfer belt. The supporting member is rotatable about a center axis during movement of the transfer belt, and the contact surface is convex with predetermined curvature toward the transfer belt.

Abstract: An image forming apparatus includes an exposure device configured to expose image bearing members charged by charging devices to form latent images on the image bearing members, and a control unit configured to, in ether one or both of an image forming unit A and an image forming unit B, adjust an amount of exposure by which the image bearing member is exposed and a charging voltage based on information about the image bearing members of the image forming units A and B. The control unit is configured to make the charging voltage and the amount of exposure in the image forming unit A different from the charging voltage and the amount of exposure in the image forming unit B.

Abstract: An image forming apparatus includes: an image bearing member, an intermediary transfer belt containing an ion conductive agent, a secondary transfer member, and a charging device. With respect to the intermediary transfer belt, when a difference in number of digits between resistivity measured by using a metal probe and resistivity measured by using a sputtering electrode is ?M, a difference in number of digits between resistivity in a first environment and resistivity in a second environment higher than the first environment in temperature or humidity is ?E, a length of the secondary transfer portion with respect to the movement direction of the intermediary transfer belt is La, and a distance from the charging portion to the primary transfer portion with respect to the movement direction is Lb, the following relationship is satisfied: ?M??E?log(Lb/La).

Abstract: An image forming apparatus includes a rotatable member-to-be-cleaned having elasticity; a cleaning member, having elasticity, for removing a deposited matter deposited on the member-to-be-cleaned; and a supporting portion for supporting the cleaning member so that the cleaning member swings around a swing fulcrum. The swing fulcrum of the supporting portion is provided so that a force exerted from the member-to-be-cleaned onto the cleaning member with respect to a direction along a tangential line where the cleaning member and the member-to-be-cleaned contact each other during movement of the member-to-be-cleaned has a vector component in a direction in which the cleaning member is moved away from the member-to-be-cleaned.

Abstract: An image forming apparatus configured to form a toner image on a recording material, includes: an image forming unit configured to form a unfixed toner image on the recording material; a fixing unit configured to heat the recording material where the unfixed toner image is formed while conveying the recording material using a nip portion, and to fix the unfixed toner image on the recording material; and a control unit configured to perform control so that temperature of the fixing unit is maintained in target temperature, with the target temperature (Tn) of a n'th page in consecutive printing being set to the highest temperature of the target temperatures (Tn to Tn+k) according to each of image densities (Dn to Dn+k) at (n to (n+k))'th pages, where integer k21.

Abstract: An image forming apparatus includes a rotatable image carrying member, a rotatable transfer member cooperative with the image carrying member, and a fixing unit having a fixing nip for nipping and feeding the recording material discharged from the transfer nip while fixing the toner image. In addition, a bowing amount measuring unit measures a bowing amount of the recording material, a storing portion stores a target bowing amount, and a speed controller controls a feeding speed of the recording material. The storing portion stores a plurality of target bowing amounts, which are selectable depending on kinds of the recording material, and the speed controller controls the feeding speed in the fixing nip, and then controls the feeding speed so that the bowing amount is substantially zero at the time when a trailing edge of the recording material leaves the transfer nip.

Abstract: The image forming apparatus includes an endless and movable transfer material bearing belt, a transfer member, an opposing member and a belt guide member, wherein a conveyance direction of the transfer material in a first area is substantially the same as a conveyance direction of the transfer material in a second area, the first area corresponding to a nip area formed by the opposing member and the transfer member and the second area corresponding to an area in which the belt guide member bringing the transfer material bearing belt and the image bearing belt come into contact with each other. By the virtue of the present invention, a transfer material is restrained from scraping off the leading end of a toner image before the leading end of the toner image enters a transfer nip portion, while suppressing spattering of the toner image on the upstream of the transfer nip portion.

Abstract: An image forming apparatus includes an image bearing member; a rotatable endless belt; a first driving member for driving the belt in contact to an inner surface of the belt; a second driving member for driving the belt in contact to an outer surface of the belt; a tension detecting unit for detecting a state of tension of the belt; and a controller for controlling a rotational speed of the second driving member. A driving force applied from the second driving member to the belt is smaller than a driving force applied from the first driving member to the belt. The controller controls, on the basis of a detection result of the tension detecting unit, the rotational speed of the second driving member so that the state of tension of the belt is a predetermined state.

Abstract: A circumferential length of a belt is measured within a short period of time. A plurality of marks is provided on a belt. Distances between the marks are set to be all different from each other. The distance between the marks is set to allow the mark to be identified by measuring a period of time between the detection of one mark and that of the next mark even if the length of the belt is changed to some degree by the expansion of the belt or the like. Then, a period of time between the identified mark and the next mark is accurately measured. The total circumferential length of the belt is measured based on the results of measurement.

Abstract: An image forming apparatus includes a image carrying member; a transfer member forming a transfer nip for nipping and feeding a sheet while transferring the toner image onto the sheet; a fixing unit having a fixing nip for nipping and feeding the sheet discharged from the transfer nip while fixing the toner image; a bowing amount measuring unit for measuring a bowing amount of the sheet which is fed while being nipped by the transfer nip and fixing nip; and a sheet feeding speed controller, wherein the controller is capable of controlling the feeding speed of the fixing nip on the basis of a result detection of the measuring unit such that the bowing amount is substantially zero at the time when a trailing end of the sheet goes out of the transfer nip.

Abstract: An image forming apparatus includes a rotatable member-to-be-cleaned having elasticity; a cleaning member, having elasticity, for removing a deposited matter deposited on the member-to-be-cleaned; and a supporting portion for supporting the cleaning member so that the cleaning member swings around a swing fulcrum. The swing fulcrum of the supporting portion is provided so that a force exerted from the member-to-be-cleaned onto the cleaning member with respect to a direction along a tangential line where the cleaning member and the member-to-be-cleaned contact each other during movement of the member-to-be-cleaned has a vector component in a direction in which the cleaning member is moved away from the member-to-be-cleaned.

Abstract: The image forming apparatus has a configuration in which a secondary transfer roller guides a leading end of a recording material which enters a secondary transfer nip to be led to the secondary transfer nip and the leading end of the recording material is prevented from coming into contact with a toner image on an intermediate transferring member before the recording material enters the secondary transfer nip. Further, in the image forming apparatus, a surface of a transfer roller is smoothened so that the leading end of the recording material is guided to the secondary transfer nip without being caught. As a result, the present invention is intended to prevent the leading end of the recording material which enters the secondary transfer nip from distorting the toner image on the intermediate transferring member.

Abstract: A circumferential length of a belt is measured within a short period of time. A plurality of marks is provided on a belt. Distances between the marks are set to be all different from each other. The distance between the marks is set to allow the mark to be identified by measuring a period of time between the detection of one mark and that of the next mark even if the length of the belt is changed to some degree by the expansion of the belt or the like. Then, a period of time between the identified mark and the next mark is accurately measured. The total circumferential length of the belt is measured based on the results of measurement.

Abstract: A circumferential length of a belt is measured within a short period of time. A plurality of marks is provided on a belt. Distances between the marks are set to be all different from each other. The distance between the marks is set to allow the mark to be identified by measuring a period of time between the detection of one mark and that of the next mark even if the length of the belt is changed to some degree by the expansion of the belt or the like. Then, a period of time between the identified mark and the next mark is accurately measured. The total circumferential length of the belt is measured based on the results of measurement.

Abstract: The image forming apparatus includes an endless and movable transfer material bearing belt, a transfer member, an opposing member and a belt guide member, wherein a conveyance direction of the transfer material in a first area is substantially the same as a conveyance direction of the transfer material in a second area, the first area corresponding to a nip area formed by the opposing member and the transfer member and the second area corresponding to an area in which the belt guide member bringing the transfer material bearing belt and the image bearing belt come into contact with each other. By the virtue of the present invention, a transfer material is restrained from scraping off the leading end of a toner image before the leading end of the toner image enters a transfer nip portion, while suppressing spattering of the toner image on the upstream of the transfer nip portion.

Abstract: An image forming apparatus includes an image bearing member for bearing a toner image; a movable endless transfer belt for transferring the toner image from the image bearing member onto a transfer material; and a transfer device for transferring the toner image from the image bearing member toward the transfer belt. The transfer device includes a transfer member for sliding on an inner surface of the transfer belt in contact with the inner surface, a supporting member for supporting the transfer member and an urging member for urging the supporting member toward the transfer belt. The transfer member is contacted to the inner surface of the transfer belt at a contact surface thereof without rotation relative to the supporting member during movement of the transfer belt. The supporting member is rotatable about a center axis thereof so as to be moved in a direction perpendicular to a movement direction of the transfer belt. The contact surface is convex with predetermined curvature toward the transfer belt.

Abstract: An image forming apparatus is provided, which prevents occurrence of conveying malfunction or image failure due to variation of conveying speed caused by endurance of a fixing unit or a conveying unit, variation of using environment, or a type of a recording material. The image forming apparatus includes: a fixing unit for heating and fixing a toner image on a recording sheet (P); a secondary transferring portion for conveying the recording sheet (P) to the fixing unit; a loop sensor for detecting a degree of a loop of the recording sheet (P) generated according to a speed difference between a conveying speed of the fixing unit and a conveying speed of the secondary transferring portion; a CPU for controlling the conveying speed of the fixing unit; a fixing deliver sensor for detecting a used amount of the fixing unit; and an EEPROM for storing information on the used amount of the fixing unit detected by the fixing deliver sensor.

Abstract: An image forming apparatus is provided, which prevents occurrence of conveying malfunction or image failure due to variation of conveying speed caused by endurance of a fixing unit or a conveying unit, variation of using environment, or a type of a recording material. The image forming apparatus includes: a fixing unit for heating and fixing a toner image on a recording sheet (P); a secondary transferring portion for conveying the recording sheet (P) to the fixing unit; a loop sensor for detecting a degree of a loop of the recording sheet (P) generated according to a speed difference between a conveying speed of the fixing unit and a conveying speed of the secondary transferring portion; a CPU for controlling the conveying speed of the fixing unit; a fixing deliver sensor for detecting a used amount of the fixing unit; and an EEPROM for storing information on the used amount of the fixing unit detected by the fixing deliver sensor.

Abstract: A circumferential length of a belt is measured within a short period of time. A plurality of marks is provided on a belt. Distances between the marks are set to be all different from each other. The distance between the marks is set to allow the mark to be identified by measuring a period of time between the detection of one mark and that of the next mark even if the length of the belt is changed to some degree by the expansion of the belt or the like. Then, a period of time between the identified mark and the next mark is accurately measured. The total circumferential length of the belt is measured based on the results of measurement.

Abstract: The image forming apparatus has a configuration in which a secondary transfer roller guides a leading end of a recording material which enters a secondary transfer nip to be led to the secondary transfer nip and the leading end of the recording material is prevented from coming into contact with a toner image on an intermediate transferring member before the recording material enters the secondary transfer nip. Further, in the image forming apparatus, a surface of a transfer roller is smoothened so that the leading end of the recording material is guided to the secondary transfer nip without being caught. As a result, the present invention is intended to prevent the leading end of the recording material which enters the secondary transfer nip from distorting the toner image on the intermediate transferring member.