Abstract: A hydraulic hammering device enables an auto-stroke mode and an idle strike prevention mode to coexist with a simple circuit configuration. A first control valve controls advancing and retracting movements of a piston and a second control valve select either the auto-stroke mode and the idle strike prevention mode. To the second control valve, a shared spool is slidably fitted and a mode selection means is disposed. When the mode selection means allows supply of pressurized oil to an auto-stroke setting portion of the shared spool and prohibits discharge of pressurized oil from an idle strike prevention setting portion, the auto-stroke mode is selected. When prohibiting supply of pressurized oil to the auto-stroke setting portion and allowing discharge of pressurized oil from the idle strike prevention setting portion, the idle strike prevention mode is selected.

Abstract: A hydraulic hammering device enables an auto-stroke mechanism and an idle strike prevention mechanism to coexist with a simple circuit configuration. The device includes a first control valve to control advancing and retracting movements of a piston, an auto-stroke mechanism and an idle strike prevention mechanism, and a second control valve to select either of the auto-stroke mechanism and the idle strike prevention mechanism. To the second control valve, a shared spool is slidably fitted and a mode selection means is disposed. When the mode selection means allows supply of pressurized oil to an auto-stroke setting portion of the shared spool and prohibits discharge of pressurized oil from an idle strike prevention setting portion, the auto-stroke mechanism is selected. When prohibiting supply of pressurized oil to the auto-stroke setting portion and allowing discharge of pressurized oil from the idle strike prevention setting portion, the idle strike prevention mechanism is selected.

Abstract: A hydraulic hammering device enables an auto-stroke mechanism and an idle strike prevention mechanism to coexist with a simple circuit configuration. The device includes a first control valve to control advancing and retracting movements of a piston, an auto-stroke mechanism and an idle strike prevention mechanism, and a second control valve to select either of the auto-stroke mechanism and the idle strike prevention mechanism. To the second control valve, a shared spool is slidably fitted and a mode selection means is disposed. When the mode selection means allows supply of pressurized oil to an auto-stroke setting portion of the shared spool and prohibits discharge of pressurized oil from an idle strike prevention setting portion, the auto-stroke mechanism is selected. When prohibiting supply of pressurized oil to the auto-stroke setting portion and allowing discharge of pressurized oil from the idle strike prevention setting portion, the idle strike prevention mechanism is selected.

Abstract: A hydraulic hammering device that uses a scheme in which a front chamber is switched into communication with a low-pressure circuit when a piston advances, wherein occurrences of “galling” to the piston at a sliding contact portion with a front-chamber liner is reduced. The front chamber has the front-chamber liner fitted to an inner surface of a cylinder. A hydraulic chamber space communicating with the front chamber and filled with hydraulic oil is formed as a cushion chamber on the inner peripheral surface of a rear portion of the front-chamber liner. The cushion chamber has a second drain circuit (from first end face grooves to slits to second end face grooves), which is provided separately from a drain circuit that guides the hydraulic fluid passing through a liner bearing of the front-chamber liner to the low-pressure circuit.

Abstract: A hydraulic hammering device that uses a scheme in which a front chamber is switched into communication with a low-pressure circuit when a piston advances, wherein occurrences of “galling” to the piston at a sliding contact portion with a front-chamber liner is reduced. The front chamber has the front-chamber liner fitted to an inner surface of a cylinder. A hydraulic chamber space communicating with the front chamber and filled with hydraulic oil is formed as a cushion chamber on the inner peripheral surface of a rear portion of the front-chamber liner. The cushion chamber has a second drain circuit (from first end face grooves to slits to second end face grooves, which is provided separately from a drain circuit that guides the hydraulic fluid passing through a liner bearing of the front-chamber liner to the low-pressure circuit.

Abstract: A recording material conveying device includes a stripping claw being in contact with one rotary body of a first pair of rotary bodies, and a supporting member supporting a recording material curved when a jam occurs. The supporting member includes a supporting section located more away from the stripping claw than an imaginary straight line (C) passing a nip portion of the first pair of rotary bodies and a surface on a conveying path's side of the stripping claw, and the supporting section supports the recording material curved when the jam occurs. The recording material conveying device further includes a conveyance guide that is disposed on the downstream side from the supporting member and is displaced toward a pressed direction by a pressing force acting when the curved recording material comes into contact with the conveyance guide.

Abstract: A Transfer device (10) includes an intermediate transfer belt (41), a plurality of intermediate transfer roller (34A-34D) and a transfer member moving mechanism (20). The transfer member moving mechanism moves the intermediate transfer rollers (34A-34D) between pressing positions causing the intermediate transfer belt (41) to be pressed against respective photoreceptor drums (31A-31D) and separate positions causing the intermediate transfer belt (41) to be separate from the respective photoreceptor drums (31A-31D). The transfer member moving mechanism (20) causes a second pressing position of the intermediate transfer roller for monochrome (34A) in monochromatic image forming to be different from a first pressing position of the intermediate transfer roller for monochrome (34A) in full-color image forming so that an amount of pressing of the intermediate transfer belt (41) by the intermediate transfer roller for monochrome (34A) becomes greater in monochromatic image forming than in full-color image forming.

Abstract: An image forming apparatus determines the amount of cleaning toner that is supplied to each of an intermediate transfer belt 31 and a secondary transfer belt 42 based on the number of sheets that have been fed with the pick-up side of the sheet opposed to the intermediate transfer belt 31 and the number of sheets that have been fed with the pick-up side of the sheet opposed to the secondary transfer belt 42; integrally forms on the intermediate transfer belt 31 cleaning toner images that are supplied to each of the intermediate transfer belt 31 and the secondary transfer belt 42; and switches the application and the stop application of the transfer voltage for transferring the toner image from the intermediate transfer belt 31 to the secondary transfer roller 41 at a timing corresponding to the determined amount of toner.

Abstract: A recording material conveying device includes a stripping claw being in contact with one rotary body of a first pair of rotary bodies, and a supporting member supporting a recording material curved when a jam occurs. The supporting member includes a supporting section located more away from the stripping claw than an imaginary straight line (C) passing a nip portion of the first pair of rotary bodies and a surface on a conveying path's side of the stripping claw, and the supporting section supports the recording material curved when the jam occurs. The recording material conveying device further includes a conveyance guide that is disposed on the downstream side from the supporting member and is displaced toward a pressed direction by a pressing force acting when the curved recording material comes into contact with the conveyance guide.

Abstract: An image forming apparatus includes: a transfer portion that transfers a toner image from a first image forming element to a second image forming element when transfer voltage is applied; and a control portion, at time of cleaning the plurality of image forming elements, after integrally forming a cleaning toner image to be supplied to the first image forming element and the second image forming element on the surface of the photoreceptor along a revolving direction, that controls the application of the transfer voltage to the transfer portion to transfer the toner image in a manner such that the toner image is divided into at least four sections along the revolving direction, out of which at least two sections that are not adjacent to each other are transferred from the first image forming element to the second image forming element.

Abstract: A Transfer device (10) includes an intermediate transfer belt (41), a plurality of intermediate transfer roller (34A-34D) and a transfer member moving mechanism (20). The transfer member moving mechanism moves the intermediate transfer rollers (34A-34D) between pressing positions causing the intermediate transfer belt (41) to be pressed against respective photoreceptor drums (31A-31D) and separate positions causing the intermediate transfer belt (41) to be separate from the respective photoreceptor drums (31A-31D). The transfer member moving mechanism (20) causes a second pressing position of the intermediate transfer roller for monochrome (34A) in monochromatic image forming to be different from a first pressing position of the intermediate transfer roller for monochrome (34A) in full-color image forming so that an amount of pressing of the intermediate transfer belt (41) by the intermediate transfer roller for monochrome (34A) becomes greater in monochromatic image forming than in full-color image forming.

Abstract: A recording material conveying device includes a stripping claw being in contact with one rotary body of a first pair of rotary bodies, and a supporting member supporting a recording material curved when a jam occurs. The supporting member includes a supporting section located more away from the stripping claw than an imaginary straight line (C) passing a nip portion of the first pair of rotary bodies and a surface on a conveying path's side of the stripping claw, and the supporting section supports the recording material curved when the jam occurs. The recording material conveying device further includes a conveyance guide that is disposed on the downstream side from the supporting member and is displaced toward a pressed direction by a pressing force acting when the curved recording material comes into contact with the conveyance guide.

Abstract: An image forming apparatus includes: a transfer portion that transfers a toner image from a first image forming element to a second image forming element when transfer voltage is applied; and a control portion, at time of cleaning the plurality of image forming elements, after integrally forming a cleaning toner image to be supplied to the first image forming element and the second image forming element on the surface of the photoreceptor along a revolving direction, that controls the application of the transfer voltage to the transfer portion to transfer the toner image in a manner such that the toner image is divided into at least four sections along the revolving direction, out of which at least two sections that are not adjacent to each other are transferred from the first image forming element to the second image forming element.

Abstract: A Transfer device (10) includes an intermediate transfer belt (41), a plurality of intermediate transfer roller (34A-34D) and a transfer member moving mechanism (20). The transfer member moving mechanism moves the intermediate transfer rollers (34A-34D) between pressing positions causing the intermediate transfer belt (41) to be pressed against respective photoreceptor drums (31A-31D) and separate positions causing the intermediate transfer belt (41) to be separate from the respective photoreceptor drums (31A-31D). The transfer member moving mechanism (20) causes a second pressing position of the intermediate transfer roller for monochrome (34A) in monochromatic image forming to be different from a first pressing position of the intermediate transfer roller for monochrome (34A) in full-color image forming so that an amount of pressing of the intermediate transfer belt (41) by the intermediate transfer roller for monochrome (34A) becomes greater in monochromatic image forming than in full-color image forming.

Abstract: A fixing device of the present invention includes: an external heating belt which is to contact with a surface of a fixing roller so as to heat up the fixing roller; and a cleaning member (a scraper and/or cleaning pad) which is to contact with the external heating belt. The cleaning pad which is impregnated with silicone oil is to contact with a surface of the external heating belt, thereby applying the silicone oil (release agent) to the surface of the external heating belt. This makes it possible to prevent generation of an offset.

Abstract: In a fixing device including (i) an external heat belt which abuts against a surface of a fixing roller so as to heat the fixing roller and (ii) a cleaning member which abuts against the external heat belt, a fixing temperature, which is a surface temperature of the fixing roller during a fixing process, is set per group into which recording media to be subjected to the fixing process are divided according to their widths in a direction of a rotary axis of the fixing roller, in such a way that the fixing temperature is set to a lower temperature for a group of narrower widths. This makes it possible to prevent a reduction in releasability of the fixing roller caused by a material, which is scraped off from the external heat belt by the cleaning member and then adhered to the fixing roller, thereby preventing the high-temperature offset.

Abstract: A sheet separation mechanism includes a separation claw holder, a separation claw, a first coil spring and a second coil spring. The separation claw holder can be provided at a predetermined place in the image forming apparatus. The separation claw includes a separation claw base pivotally supported by the separation claw holder and a separation claw front-end pivotally supported by the separation claw base. The first coil spring is configured to apply a force to rotate the separation claw base toward an intermediate transfer belt. The second coil spring is configured to apply a force to rotate the separation claw front-end toward the intermediate transfer belt.

Abstract: A sheet separation mechanism includes a separation claw holder, a separation claw, a first coil spring and a second coil spring. The separation claw holder can be provided at a predetermined place in the image forming apparatus. The separation claw includes a separation claw base pivotally supported by the separation claw holder and a separation claw front-end pivotally supported by the separation claw base. The first coil spring is configured to apply a force to rotate the separation claw base toward an intermediate transfer belt. The second coil spring is configured to apply a force to rotate the separation claw front-end toward the intermediate transfer belt.

Abstract: An image forming apparatus includes a transfer belt unit which has an intermediate transfer belt for supporting toner images and primary transfer rollers for pressing the intermediate transfer belt against corresponding photoreceptor drums and moves the intermediate transfer belt along the surface of each photoreceptor drum to transfer the toner images to the intermediate transfer belt. The intermediate transfer belt is formed so as to be 30 ?m to 50 ?m in average thickness, each primary transfer roller is arranged at a position, along the moving direction of the intermediate transfer belt, which is deviated downstream with respect to the moving direction from the position where the intermediate transfer belt is in contact with the photoreceptor and which is projected toward the photoreceptor drum side so as to press the intermediate transfer belt against photoreceptor with a nip pressure ranging from 10 gf/cm2 to 40 gf/cm2.

Abstract: An intermediate transfer unit mounting and dismounting mechanism for an image forming apparatus including a transfer belt unit that is provided as a separate structure from the apparatus body and can be mounted to and dismounted from the apparatus body, includes: a coupling/decoupling manipulator disposed at the coupling portion between the intermediate transfer unit and the apparatus body for coupling/decoupling. The coupling/decoupling manipulator includes a threaded portion to fasten the intermediate transfer unit and the apparatus body and a drive gear for transferring driving force for conveying the intermediate transfer belt. While the threaded portion is rotated to release the fastening between the transfer belt unit and the housing, the transfer belt is conveyed by the drive gear that rotates in linkage with the rotation of the threaded portion.