Abstract: A drive transmission device includes a rotation shaft, a drive transmitter attached to the rotation shaft to slide in an axial direction and including an engaging portion extending in the axial direction, and a coil spring to bias the drive transmitter to one side in the axial direction, and a shaft-side drive transmitter disposed on the rotation shaft. The coil spring includes a sparse portion and a dense portion. The shaft-side drive transmitter engages the engaging portion to prevent the drive transmitter from disengaging from the rotation shaft. The coil spring and the engaging portion satisfy C>A?B where A represents a length of the coil spring in a state in which the shaft-side drive transmitter retains the drive transmitter, B represents a compressed height of the coil spring, and C represents a length of the coil spring in the axial direction.

Abstract: A power transmission device includes coaxially a first rotary body including a first gear on a drive source side, a second rotary body including a second gear on a driven side, a third rotary body including a third gear movably held to transmit a driving force, and a guide member disposed at one of the first gear, the second gear, and the third gear to contact a first end surface of a gear tooth of another of the first gear, the second gear, and the third gear, serving as a mating gear, to guide the first end surface between teeth of the one of the first gear, the second gear, and the third gear. The guide member extends toward the mating gear and a tip of the guide member is placed at a distance from an end of the one of the gears in the axial direction.

Abstract: An image forming apparatus includes a drive device including a first drive transmission passage through which a driving force of a drive source is transmitted to a developer bearer via a first joint and a second drive transmission passage through which the driving force is transmitted to a rotary body via a second joint. The first drive transmission passage and the second drive transmission passage are defined such that one of a first drive transmission ratio to the first joint of the first drive transmission passage and a second drive transmission ratio to the second joint of the second drive transmission passage is an integral multiple of the other of the first drive transmission ratio from the drive source to the first joint of the first drive transmission passage and the second drive transmission ratio from the drive source to the second joint of the second drive transmission passage.

Abstract: A transfer device includes a belt image bearer; a driving roller that rotates the belt image bearer; a transfer member; first and second driving motors that respectively rotate the driving roller and the transfer member; first and second speed detecting units that respectively detect rotational speeds of the belt image bearer and the transfer member; and a control unit that implements control such that the belt image bearer and the transfer member are rotated at rotational speeds corresponding to a relative speed at which a variation amount is less than a predetermined variation amount, the variation amount being the variation of values of driving torques of the first and second driving motors in a state where the belt image bearer and the transfer member are in contact, with respect to these values in a state where the belt image bearer and the transfer member are separated.

Abstract: A rotary drive device includes a drive motor and drive transmission portion, which transmits a rotational drive force of the motor to a driven rotor and includes three or more drive transmission members. A high stiffness member is attached to a low-stiffness drive transmission member, which is one, lower in stiffness, of two of the drive transmission members, to increase stiffness of the low-stiffness drive transmission member. The two form a drive transmission point corresponding to a resonant point of a lowest resonance frequency among frequencies at a plurality of resonance points in frequency response characteristics derived from rotation information. One drive transmission point, which is on either a drive-transmission input side or output side, other than the drive transmission point corresponding to the resonant point of the lowest resonance frequency, of the low-stiffness drive transmission member is configured to transmit the rotational drive force through the high stiffness member.

Abstract: A drive transmission device includes a rotation shaft, a drive transmitter attached to the rotation shaft to slide in an axial direction and including an engaging portion extending in the axial direction, and a coil spring to bias the drive transmitter to one side in the axial direction, and a shaft-side drive transmitter disposed on the rotation shaft. The coil spring includes a sparse portion and a dense portion. The shaft-side drive transmitter engages the engaging portion to prevent the drive transmitter from disengaging from the rotation shaft. The coil spring and the engaging portion satisfy C>A?B where A represents a length of the coil spring in a state in which the shaft-side drive transmitter retains the drive transmitter, B represents a compressed height of the coil spring, and C represents a length of the coil spring in the axial direction.

Abstract: A driving force transmission device that transmits a driving force to a rotation body includes a flange member provided in the rotation body, a through shaft that is connected to the flange member to transmit the driving force to the rotation body via the flange member, and an intermediate transmission member that is provided in the through shaft to transmit the driving force to the flange member from the through shaft.

Abstract: A rotary drive device includes a drive motor and drive transmission portion, which transmits a rotational drive force of the motor to a driven rotor and includes three or more drive transmission members. A high stiffness member is attached to a low-stiffness drive transmission member, which is one, lower in stiffness, of two of the drive transmission members, to increase stiffness of the low-stiffness drive transmission member. The two form a drive transmission point corresponding to a resonant point of a lowest resonance frequency among frequencies at a plurality of resonance points in frequency response characteristics derived from rotation information. One drive transmission point, which is on either a drive-transmission input side or output side, other than the drive transmission point corresponding to the resonant point of the lowest resonance frequency, of the low-stiffness drive transmission member is configured to transmit the rotational drive force through the high stiffness member.

Abstract: A driving force transmission device that transmits a driving force to a rotation body includes a flange member provided in the rotation body, a through shaft that is connected to the flange member to transmit the driving force to the rotation body via the flange member, and an intermediate transmission member that is provided in the through shaft to transmit the driving force to the flange member from the through shaft.

Abstract: A transfer device includes a belt image bearer; a driving roller that rotates the belt image bearer; a transfer member; first and second driving motors that respectively rotate the driving roller and the transfer member; first and second speed detecting units that respectively detect rotational speeds of the belt image bearer and the transfer member; and a control unit that implements control such that the belt image bearer and the transfer member are rotated at rotational speeds corresponding to a relative speed at which a variation amount is less than a predetermined variation amount, the variation amount being the variation of values of driving torques of the first and second driving motors in a state where the belt image bearer and the transfer member are in contact, with respect to these values in a state where the belt image bearer and the transfer member are separated.

Abstract: A power transmission device includes a drive coupling, a driven coupling, and an intermediate transmission member. The drive coupling receives power from a drive source and rotates. The driven coupling is disposed coaxially on a first rotary shaft of the drive coupling and detachably attachable relative to the main body of the image forming apparatus. The intermediate transmission member meshes with the drive coupling and the driven coupling and is held by one of the drive coupling and the driven coupling in a state in which the driven coupling is disengaged from the main body. One of the drive coupling and the driven coupling, whichever holds the intermediate transmission member, constitutes a retaining coupling including an attachment member attached to one of a drive-side device and a driven-side device, and a stopper assembly facing the intermediate transmission member in an axial direction of the first rotary shaft.

Abstract: A transfer device includes at least one pair of lateral plates, an intermediate transfer belt, a plurality of rollers, and a dynamic vibration absorber. The intermediate transfer belt is formed into an endless loop and is entrained about the plurality of rollers. The dynamic vibration absorber is disposed on at least one of the plurality of rollers and includes an inertial body. The inertial body is disposed inside the endless loop of the intermediate transfer belt, and both ends of the inertial body in an axial direction of the inertial body are rotatably supported by the at least one pair of lateral plates via shaft bearings.

Abstract: A power transmission device includes coaxially a first rotary body including a first gear on a drive source side, a second rotary body including a second gear on a driven side, a third rotary body including a third gear movably held to transmit a driving force, and a guide member disposed at one of the first gear, the second gear, and the third gear to contact a first end surface of a gear tooth of another of the first gear, the second gear, and the third gear, serving as a mating gear, to guide the first end surface between teeth of the one of the first gear, the second gear, and the third gear. The guide member extends toward the mating gear and a tip of the guide member is placed at a distance from an end of the one of the gears in the axial direction.

Abstract: A power transmission device includes a drive coupling, a driven coupling, and an intermediate transmission member. The drive coupling receives power from a drive source and rotates. The driven coupling is disposed coaxially on a first rotary shaft of the drive coupling and detachably attachable relative to the main body of the image forming apparatus. The intermediate transmission member meshes with the drive coupling and the driven coupling and is held by one of the drive coupling and the driven coupling in a state in which the driven coupling is disengaged from the main body. One of the drive coupling and the driven coupling, whichever holds the intermediate transmission member, constitutes a retaining coupling including an attachment member attached to one of a drive-side device and a driven-side device, and a stopper assembly facing the intermediate transmission member in an axial direction of the first rotary shaft.

Abstract: A rotator driving system for driving a rotator with a motor includes a dynamic vibration absorber attached to a rotary shaft of the rotator. The dynamic vibration absorber includes an inertia body, a viscosity-providing component to provide a viscosity, and a torsion spring unit to function as a torsion spring that includes a boss fixed to the rotary shaft. Multiple spokes extend radially outward from the boss. Multiple seats are provided at respective tips of the multiple spokes to fix the inertia body. The torsion spring unit is fixed by both the rotary shaft of the rotator and the boss fixed to the rotary shaft therebetween. The viscosity-providing component supports the inertia body via the multiple seats provided at the respective tips of the multiple spokes.

Abstract: A drive transmission device that transmits rotation from a drive source of an image forming apparatus to a rotary body detachably attachable relative to a main body thereof in an axial direction includes two external gears, a cylindrical member, and an intermediate-body retainer. The two external gears include teeth on an outer circumferential surface thereof extending in an axial direction. The cylindrical member includes an internal gear formed on an inner circumferential surface thereof to mesh with the external gears, and a flange on a portion of an outer circumferential surface of the cylindrical member, the flange including a projection. The intermediate-body retainer includes a depression to fit with the projection of the flange to prevent the cylindrical member from getting disengaged from the external gears. The external gears constitute a two-stage spline joint that meshes with the internal gear of the cylindrical member.

Abstract: A drive transmitter, including a first rotational axis transmitting a drive force of a drive source to a first rotator, a second rotational axis transmitting a drive force of the drive source to a second rotator, and an idler gear configured to transmit a drive force to the second rotational axis; wherein the first rotational axis penetrates the idler gear with a gap therebetween.

Abstract: A synchronized drive unit, including a drive member including a pulley; a driven member including a pulley; a relay member including to transmit a power; and timing belts hung around the drive and driven members through the relay member with tension and rotates the drive and driven members in synchronization, wherein each of the timing belts is formed of plural narrow timing belts parallely placed in a rotational axis direction of the pulley and the narrow timing belts are located on the driven member so as to counteract their eccentric components each other.

Abstract: An image forming apparatus includes a primary transfer device that primarily transfers a first image from a first image bearer onto a first belt unit at a primary transfer position, a secondary transfer device that secondarily transfers the first image from the first belt unit onto a printing medium at a secondary transfer position, and a direct transfer device that directly transfers a second image from a second image bearer onto the printing medium at a direct transfer position. A second belt unit is rotatably suspended by plural second rollers and carries and conveys the printing medium through the direct transfer position and the secondary transfer position. An interval between the direct transfer position and the secondary transfer position is prescribed natural number times of a circumference of one of the plural second rollers, which fluctuates a velocity of the second belt unit.

Abstract: A synchronized drive unit, including a drive member including a pulley; a driven member including a pulley; a relay member including to transmit a power; and timing belts hung around the drive and driven members through the relay member with tension and rotates the drive and driven members in synchronization, wherein each of the timing belts is formed of plural narrow timing belts parallely placed in a rotational axis direction of the pulley and the narrow timing belts are located on the driven member so as to counteract their eccentric components each other.