Abstract: A developer supply device for supplying developer contained in a developer container toward a developing device in an apparatus body of an image forming apparatus includes a conveyance passage, a developer receiving portion, a sub-hopper, and a conveying tube. The conveyance passage delivers the developer discharged from the developer container. The developer receiving portion is detachable and attachable with respect to the developer container. The sub-hopper is detachable and attachable with respect to the developing device and stores the developer discharged toward the developing device. The flexible conveying tube has a first end portion coupled to the developer receiving portion and a second end portion coupled to the sub-hopper, and conveys the developer from the developer receiving portion to the sub-hopper. The developer supply device is detachable from and attachable to the apparatus body with a connection among the developer receiving portion, the sub-hopper, and the conveying tube being maintained.

Abstract: A snap ring is set to a set portion of a shaft of a rotator from a direction orthogonal to an axial direction of the shaft. The snap ring includes a first arcuate portion and a second arcuate portion facing each other, being elastically deformable in directions away from each other, holding the set portion by elastic deformation restoring force. One ends of the first and second arcuate portions are away from each other to form an insertion portion to insert the set portion. When the snap ring is not used, the first arcuate portion has a same radius of curvature as the second arcuate portion and the set portion, and a center of curvature closer to the second arcuate portion than the first arcuate portion, and the second arcuate portion has a center of curvature closer to the first arcuate portion than the second arcuate portion.

Abstract: A snap ring is set to a set portion of a shaft of a rotator from a direction orthogonal to an axial direction of the shaft. The snap ring includes a first arcuate portion and a second arcuate portion facing each other, being elastically deformable in directions away from each other, holding the set portion by elastic deformation restoring force. One ends of the first and second arcuate portions are away from each other to form an insertion portion to insert the set portion. When the snap ring is not used, the first arcuate portion has a same radius of curvature as the second arcuate portion and the set portion, and a center of curvature closer to the second arcuate portion than the first arcuate portion, and the second arcuate portion has a center of curvature closer to the first arcuate portion than the second arcuate portion.

Abstract: A cam drive device includes a cam to rotate; a displacement body to be displaced in response to a change in a rotation position of the cam in contact with the displacement body; a motor to rotate the cam; and a power source to output an electric current to be supplied to the motor. An electric current to cause a stall torque to the motor being a stop state is changed in response to a change in a rotation stop position of the cam.

Abstract: An image forming apparatus includes an apparatus body, a plurality of image bearers, an endless belt, a contact and separation mechanism to generate a first trajectory and a second trajectory of the endless belt, a sensor to detect an object on a surface of the endless belt, and a positioning mechanism to enable the sensor to detect the object in the first trajectory and the second trajectory of the endless belt. The positioning mechanism includes a stay to support the sensor, a first bracket, a second bracket, a first positioning portion attached to the apparatus body to position the sensor in a direction of rotation of the first bracket and the second bracket at a time of the first trajectory, and a second positioning portion attached to the second bracket to position the sensor in the direction of rotation of the first bracket at a time of the second trajectory.

Abstract: An image forming apparatus includes an apparatus body, a plurality of image bearers, an endless belt, a contact and separation mechanism to generate a first trajectory and a second trajectory of the endless belt, a sensor to detect an object on a surface of the endless belt, and a positioning mechanism to enable the sensor to detect the object in the first trajectory and the second trajectory of the endless belt. The positioning mechanism includes a stay to support the sensor, a first bracket, a second bracket, a first positioning portion attached to the apparatus body to position the sensor in a direction of rotation of the first bracket and the second bracket at a time of the first trajectory, and a second positioning portion attached to the second bracket to position the sensor in the direction of rotation of the first bracket at a time of the second trajectory.

Abstract: A cam drive device includes a cam to rotate; a displacement body to be displaced in response to a change in a rotation position of the cam in contact with the displacement body; a motor to rotate the cam; and a power source to output an electric current to be supplied to the motor. An electric current to cause a stall torque to the motor being a stop state is changed in response to a change in a rotation stop position of the cam.

Abstract: An image forming apparatus includes an image bearer, a nip forming device, a contact-and-separation device, a thickness information retrieving device, and a controller. The contact-and-separation device moves the image bearer and the nip forming device to contact and separate from each other. The controller controls the contact-and-separation device based on information on a thickness of a recording medium obtained by the thickness information retrieving device such that in a case in which a thickness of a preceding recording medium and a thickness of a successive recording medium are different in continuous printing in which a plurality of recording media is printed out continuously, the contact-and-separation device adjusts a space between the image bearer and the nip forming device when the preceding recording medium exits the transfer nip to a preset size corresponding to the thickness of the successive recording medium that enters the transfer nip.

Abstract: An image forming apparatus includes an image carrier that carries a toner image; a transfer member that forms a transfer nip between the transfer member and the image carrier; and a power supply capable of outputting a superimposed transfer bias in which an alternating current component is superimposed onto a direct current component. The toner image on the image carrier is transferred onto a recording medium in the transfer nip by the superimposed transfer bias or a direct current bias consisting of the direct current component output by the power supply. The apparatus also includes a controller that controls the power supply so that an output target value of the direct current component when the direct current component rises up is larger than an output target value of the direct current component when the toner image is transferred onto the recording medium.

Abstract: The transfer assembly includes a belt, a transfer device, a contact-and-separation device including a retainer, and a first vibration absorber. The transfer device contacts an image bearer via the belt to form a transfer nip portion between the image bearer and the belt and to transfer the toner image onto one of a surface of the belt and a recording medium carried on the surface of the belt. The contact-and-separation device moves the transfer device to contact and separate from the image bearer. The retainer is pivotally supported by a swingable shaft and movable in a first direction in which the transfer device approaches the image bearer and in a second direction opposite to the first direction in which the transfer device separates from the image bearer, to hold the transfer device. The first vibration absorber absorbs vibration transmitted from the swingable shaft to the transfer device via the retainer.

Abstract: An image forming apparatus includes an image bearer, a nip forming device, a contact-and-separation device, a thickness information retrieving device, and a controller. The contact-and-separation device moves the image bearer and the nip forming device to contact and separate from each other. The controller controls the contact-and-separation device based on information on a thickness of a recording medium obtained by the thickness information retrieving device such that in a case in which a thickness of a preceding recording medium and a thickness of a successive recording medium are different in continuous printing in which a plurality of recording media is printed out continuously, the contact-and-separation device adjusts a space between the image bearer and the nip forming device when the preceding recording medium exits the transfer nip to a preset size corresponding to the thickness of the successive recording medium that enters the transfer nip.

Abstract: An image forming apparatus includes an image carrier that carries a toner image; a transfer member that forms a transfer nip between the transfer member and the image carrier; and a power supply capable of outputting a superimposed transfer bias in which an alternating current component is superimposed onto a direct current component. The toner image on the image carrier is transferred onto a recording medium in the transfer nip by the superimposed transfer bias or a direct current bias consisting of the direct current component output by the power supply. The apparatus also includes a controller that controls the power supply so that an output target value of the direct current component when the direct current component rises up is larger than an output target value of the direct current component when the toner image is transferred onto the recording medium.