Abstract: A drive transmission device first and second gears. Each tooth of the first gear includes, between tooth top and bottom, one tooth surface and the other tooth surface on an opposite side. Each tooth of the second gear includes, between tooth top and bottom thereof, one tooth surface and the other tooth surface of the second gear on an opposite side. The one surfaces of the first and second gears engage to each other, and the other surfaces of the first and second gears are not. The one surface extends along respective involute curves. For at least one of the first gear and the second gear, the other surface extends from a tooth top side to a tooth bottom side along a linear line inside a plane which is symmetrical with the one surface with respect to a line connecting the tooth top and the tooth bottom.

Abstract: A sheet conveyance device includes a driving rotation device, a driven rotation device, and a supporting device including first and second restriction surfaces and supporting the driven rotation device. The driving rotation device rotates by receiving rotational driving force and drives the driven rotation device to rotate at a position facing the driving rotation device. The driven rotation device includes a driven rotation member contacting the driving rotation device, a cylindrical shaft having a cylindrical shape that rotatably supports the driven rotation member, and a restriction member that is at least partially inserted in an inner circumference side of the cylindrical shaft. A position of the cylindrical shaft is restricted in a width direction crossing the sheet conveyance direction by the restriction member contacting the first restriction surface, and movement of the cylindrical shaft in a rotational direction is restricted by the restriction member contacting the second restriction surface.

Abstract: A sheet conveyance device includes a driving rotation device, a driven rotation device, and a supporting device including first and second restriction surfaces and supporting the driven rotation device. The driving rotation device rotates by receiving rotational driving force and drives the driven rotation device to rotate at a position facing the driving rotation device. The driven rotation device includes a driven rotation member contacting the driving rotation device, a cylindrical shaft having a cylindrical shape that rotatably supports the driven rotation member, and a restriction member that is at least partially inserted in an inner circumference side of the cylindrical shaft. A position of the cylindrical shaft is restricted in a width direction crossing the sheet conveyance direction by the restriction member contacting the first restriction surface, and movement of the cylindrical shaft in a rotational direction is restricted by the restriction member contacting the second restriction surface.

Abstract: An image forming apparatus detachably mounts a cartridge and forms an image on a recording material. The apparatus includes a cartridge positioning portion, a movable member movable between a first position for positioning the cartridge to the positioning portion when the cartridge is mounted to a main assembly of the apparatus, and a retracted position, for permitting cartridge main-assembly mounting in a cartridge longitudinal direction. The movable member has an urging member urging the cartridge to the positioning portion when the movable member takes the first position. Also provided is a guiding member movable relative to the movable member to take a guide position guiding the cartridge when the movable member takes the retracted position and a position retracted from the guide position away from the cartridge when the movable member takes the first position.

Abstract: The image forming apparatus including an exposure unit that exposes an image bearing member by a laser beam, a first side plate and a second side plate facing with each other, and a first support member, a second support member, and a third support member connecting the first side plate and the second side plate to each other, wherein the first side plate and the second side plate and the first support member, the second support member, and the third support member form a substantially closed space, with said exposure unit being arranged in the closed space, and wherein a section of the closed space on a plane parallel to the first side plate and the second side plate has a substantially triangular shape. It achieves preventing the displacement of an optical component attributable to an increase in size of the image forming apparatus main body and twisting of side plates.

Abstract: An image forming apparatus includes first and second image forming units having, respectively, first and second image bearing members, detachably mountable to a main assembly of the image forming apparatus. The apparatus also includes a transfer device transferring toner images formed on the first and second image bearing members onto a transfer medium, an opening through which the first and second image forming units are passable during mounting and demounting operations, an openable member, and a guide for guiding, during mounting and demounting, the first and/or second image forming units when the openable member is in the open position. At least a part of the guide enters a space between the first and second image forming units when the openable member is in the close position.

Abstract: An image forming apparatus detachably mounts a cartridge and forms an image on a recording material. The apparatus includes a cartridge positioning portion, a movable member movable between a first position for positioning the cartridge to the positioning portion when the cartridge is mounted to a main assembly of the apparatus, and a retracted position, for permitting cartridge main-assembly mounting in a cartridge longitudinal direction. The movable member has an urging member urging the cartridge to the positioning portion when the movable member takes the first position. Also provided is a guiding member movable relative to the movable member to take a guide position guiding the cartridge when the movable member takes the retracted position and a position retracted from the guide position away from the cartridge when the movable member takes the first position.

Abstract: The image forming apparatus including an exposure unit that exposes an image bearing member by a laser beam, a first side plate and a second side plate facing with each other, and a first support member, a second support member, and a third support member connecting the first side plate and the second side plate to each other, wherein the first side plate and the second side plate and the first support member, the second support member, and the third support member form a substantially closed space, with said exposure unit being arranged in the closed space, and wherein a section of the closed space on a plane parallel to the first side plate and the second side plate has a substantially triangular shape. It achieves preventing the displacement of an optical component attributable to an increase in size of the image forming apparatus main body and twisting of side plates.

Abstract: An image forming apparatus includes a first image forming unit, comprising a first image bearing member, detachably mountable to a main assembly of the image forming apparatus; a second image forming unit, comprising a second image bearing member, detachably mountable to the apparatus main assembly; a transfer device for transferring a toner image formed on the first image bearing member and a toner image formed on the second image bearing member onto a transfer medium; an opening through which the first image forming unit and the second image forming unit are passable during mounting and demounting operations; an openable member movable to an open position and a close position; and a guide portion for guiding at least one of the first image forming unit and the second image forming unit to be mounted in and demounted from the apparatus main assembly when the openable member is located in the open position.

Abstract: A plurality of process cartridges are detachably mountable to an electrophotographic image forming apparatus along a substantially vertical line. The cartridges each have an electrophotographic photosensitive drum, process means actable on the drum, and a drum shutter movable between first and second positions. The apparatus includes mounting portions for detachably mounting the cartridges, an opening for permitting passage of the cartridges into the apparatus, a covering member for covering the opening, and a pressing member for moving the shutter to the second position thereof when the covering member moves from an open position to a closed position. An angle of rotation of the shutter rotated from the first to the second position in the bottommost cartridge is larger than an angle of rotation of the shutter rotated from the first position to the second position in another one of said process cartridges.

Abstract: The image forming apparatus includes an opening and closing device that can be opened or closed with respect to a main body of an image forming apparatus, a plurality of image forming devices, a recording material containing device which contains a recording material and which can be detachably mounted on the main body, and a positioning device which positions the opening and closing device in an open state. By this arrangement, the ability to detach the image forming devices is improved without increasing the dimensions of the apparatus.

Abstract: A plurality of process cartridges are detachably mountable to an electrophotographic image forming apparatus along a substantially vertical line. The cartridges each have an electrophotographic photosensitive drum, process means actable on the drum, and a drum shutter movable between first and second positions. The apparatus includes mounting portions for detachably mounting the cartridges, an opening for permitting passage of the cartridges into the apparatus, a covering member for covering the opening, and a pressing member for moving the shutter to the second position thereof when the covering member moves from an open position to a closed position. An angle of rotation of the shutter rotated from the first to the second position in the bottommost cartridge is larger than an angle of rotation of the shutter rotated from the first position to the second position in another one of said process cartridges.

Abstract: An image heating apparatus includes a first rotatable member, a second rotatable member contacting the first rotatable member, wherein a recording material passes between the first rotatable member and the second rotatable member, and a heating unit for heating the first rotatable member and having a third rotatable member contacting a surface of the first rotatable member, wherein releasability of a surface of the third rotatable member is higher than releasability of a surface of the second rotatable member. Thus, the image heating apparatus heats an image forming on a recording material without contaminating an external heating apparatus.

Abstract: The image forming apparatus includes an opening and closing device that can be opened from or closed to a main body of the image forming apparatus, a plural of image forming devices, a recording material containing device which contains a recording material and which can be detachably mounted on the main body, and a positioning device which positions the opening and closing device in an open state. The image forming apparatus is capable of improving operability of detachable image forming device without increasing the dimension of the apparatus.

Abstract: An image heating apparatus includes a first rotatable member, a second rotatable member contacting the first rotatable member, wherein a recording material passes between the first rotatable member and the second rotatable member, and a heating unit for heating the first rotatable member and having a third rotatable member contacting a surface of the first rotatable member, wherein releasability of a surface of the third rotatable member is higher than releasability of a surface of the second rotatable member. Thus, the image heating apparatus heats an image forming on a recording material without contaminating an external heating apparatus.