Abstract: A belt unit used for an image forming apparatus is provided. The belt unit includes a rotatable endless belt, a plurality of stretching members configured to stretch the belt, an urging member, and a contact and separation unit configured to be able to switch a position of the stretching member urged by the urging member. In moving the stretching member urged by the urging member from the separation position to the contact position, the contact and separation unit makes one end side of the stretching member urged by the urging member in a longitudinal direction coming into contact with the inner surface of the belt faster than the other end side, and temporarily decreases the movement speeds of the both ends of the stretching member in the longitudinal direction respectively before arriving at the contact position.

Abstract: An electrophotographic image forming apparatus to which a cartridge is detachably mountable to form an image on a recording medium, the electrophotographic image forming apparatus including: a mounting portion to which the cartridge is detachably mountable; a cartridge holding member which holds the cartridge to move the cartridge to the mounting portion; a lock member which releasably locks the cartridge to the cartridge holding member; and a lock releasing member which releases the lock of the cartridge to the cartridge holding member by the lock member after the cartridge holding member moves the cartridge to the mounting portion.

Abstract: A belt unit used for an image forming apparatus is provided. The belt unit includes a rotatable endless belt, a plurality of stretching members configured to stretch the belt, an urging member, and a contact and separation unit configured to be able to switch a position of the stretching member urged by the urging member. In moving the stretching member urged by the urging member from the separation position to the contact position, the contact and separation unit makes one end side of the stretching member urged by the urging member in a longitudinal direction coming into contact with the inner surface of the belt faster than the other end side, and temporarily decreases the movement speeds of the both ends of the stretching member in the longitudinal direction respectively before arriving at the contact position.

Abstract: An electrophotographic image forming apparatus which allows a locking operation to be easily performed even when a lock mechanism for a developing cartridge is provided at a position hard of access for a user. The electrophotographic image forming apparatus includes a cartridge door opening and closing an opening portion for allowing mounting and detachment of the developing cartridge, a lock member which locks the developing cartridge mounted to a mounting portion so that the developing cartridge may not be detached from the mounting portion and which is rotatable to release the lock, and a link member which abuts the lock member and which can rotate to effect switching between the lock and lock releasing of the lock member, with an end portion of the link member being situated in the vicinity of the opening portion.

Abstract: An over-stack protective portion is provided on a stopper member. When a sheet feeding device is in a standby position, the over-stack protective portion is held in a position in which the over-stack protective portion is in pressure contact with sheets having the maximum stacking height capable of being fed and supported by a sheet supporting portion. Also, when the sheets are to be fed, the pressure contact of the over-stack protective portion with the sheets having the maximum stacking height is released.

Abstract: An image forming apparatus includes a substantially horizontally arranged image bearing member; a developing unit, including a plurality of developing devices and supporting the developing devices rotatably relative to the image bearing member; a movable intermediate transfer belt supported by first and second rotation members and facing the developing unit; a primary transfer member forming, together with the image bearing member, a primary transfer portion located near the first rotation member in a moving direction of the intermediate transfer belt, through the intermediate transfer belt; and a secondary transfer member forming, together with the second rotation member, a secondary transfer portion through the intermediate transfer belt. A toner image formed on the image bearing member by the developing unit is transferred on the intermediate transfer belt at the primary transfer portion, and is transferred on a recording material at the secondary transfer portion.

Abstract: A cartridge that can be accurately positioned and stably held with respect to a main body of an electrophotographic image forming apparatus without causing a deterioration in operability for mounting and detaching the cartridge from the apparatus main body even if a reduction in cost and a reduction in size of the apparatus main body are realized and an electrophotographic image forming apparatus including such cartridge. The cartridge is a drum cartridge that has an electrophotographic photosensitive drum and is detachably mountable to the apparatus main body. The drum cartridge has lock portions that lock on both side plates of the apparatus main body at both ends in a longitudinal direction of the drum cartridge such that the apparatus main body follows the drum cartridge mounted on the apparatus main body.

Abstract: An over-stack protective portion is provided on a stopper member. When a sheet feeding device is in a standby position, the over-stack protective portion is held in a position in which the over-stack protective portion is in pressure contact with sheets having the maximum stacking height capable of being fed and supported by a sheet supporting portion. Also, when the sheets are to be fed, the pressure contact of the over-stack protective portion with the sheets having the maximum stacking height is released.

Abstract: An over-stack protective portion is provided on a stopper member. When a sheet feeding device is in a standby position, the over-stack protective portion is held in a position in which the over-stack protective portion is in pressure contact with sheets having the maximum stacking height capable of being fed and supported by a sheet supporting portion. Also, when the sheets are to be fed, the pressure contact of the over-stack protective portion with the sheets having the maximum stacking height is released.

Abstract: An image forming apparatus includes a substantially horizontally arranged image bearing member; a developing unit, including a plurality of developing devices and supporting the developing devices rotatably relative to the image bearing member; a movable intermediate transfer belt supported by first and second rotation members and facing the developing unit; a primary transfer member forming, together with the image bearing member, a primary transfer portion located near the first rotation member in a moving direction of the intermediate transfer belt, through the intermediate transfer belt; and a secondary transfer member forming, together with the second rotation member, a secondary transfer portion through the intermediate transfer belt. A toner image formed on the image bearing member by the developing unit is transferred on the intermediate transfer belt at the primary transfer portion, and is transferred on a recording material at the secondary transfer portion.

Abstract: A cartridge that can be accurately positioned and stably held with respect to a main body of an electrophotographic image forming apparatus without deteriorating operability for mounting and detaching the cartridge from the apparatus main body even if a reduction in cost and a reduction in size of the apparatus main body are realized and an electrophotographic image forming apparatus including the cartridge. The cartridge is a drum cartridge that has an electrophotographic photosensitive drum and is detachably mountable to the apparatus main body. The drum cartridge has lock portions that lock on both side plates of the apparatus main body at both ends in a longitudinal direction of the drum cartridge such that the apparatus main body follows the drum cartridge mounted on the apparatus main body.

Abstract: An electrophotographic image forming apparatus to which a cartridge is detachably mountable to form an image on a recording medium, the electrophotographic image forming apparatus including: a mounting portion to which the cartridge is detachably mountable; a cartridge holding member which holds the cartridge to move the cartridge to the mounting portion; a lock member which releasably locks the cartridge to the cartridge holding member; and a lock releasing member which releases the lock of the cartridge to the cartridge holding member by the lock member after the cartridge holding member moves the cartridge to the mounting portion.

Abstract: An electrophotographic image forming apparatus which allows a locking operation to be easily performed even when a lock mechanism for a developing cartridge is provided at a position hard of access for a user. The electrophotographic image forming apparatus includes a cartridge door opening and closing an opening portion for allowing mounting and detachment of the developing cartridge, a lock member which locks the developing cartridge mounted to a mounting portion so that the developing cartridge may not be detached from the mounting portion and which is rotatable to release the lock, and a link member which abuts the lock member and which can rotate to effect switching between the lock and lock releasing of the lock member, with an end portion of the link member being situated in the vicinity of the opening portion.

Abstract: An image-forming apparatus includes a movable lever which functions as a recording medium detector for detecting the passage of a recording medium and a temperature detecting portion provided on the movable lever. The temperature of the recording medium is detected without providing an additional space for a sensor for detecting the temperature of the recording medium.

Abstract: An over-stack protective portion is provided on a stopper member. When a sheet feeding device is in a standby position, the over-stack protective portion is held in a position in which the over-stack protective portion is in pressure contact with sheets having the maximum stacking height capable of being fed and supported by a sheet supporting portion. Also, when the sheets are to be fed, the pressure contact of the over-stack protective portion with the sheets having the maximum stacking height is released.

Abstract: According to the present invention, a temperature sensing part of temperature sensing means is arranged to come into contact with the surface opposite to the image surface of a recording material at the time of one-sided printing without providing such an opposed member that comes into contact with the image surface of the recording material at least in a position corresponding to the position of the temperature sensing part that is in contact with the recording material.

Abstract: A sheet which is again conveyed to an image forming section passes through a re-feeding passage. A reference member is provided on one end of the re-feeding passage which is perpendicular to a sheet-conveying direction, and is provided with a plurality of reference surfaces in a stepwise manner. Side ends of sheets having different sizes and passing through the re-feeding passage abut against the reference surfaces to adjust positions of the sheets in widthwise direction. The re-feeding passage is provided with obliquely conveying means which obliquely conveys the sheets having different sizes while pushing the sheets against the reference surfaces. A support member which is provided upstream of the obliquely conveying means supports the sheet such that one end of the sheet supported by the support surface extending from lower ends of the reference surfaces substantially horizontally and the other end of the sheet have substantially the same heights.

Abstract: A sheet transport apparatus that re-transports a sheet having an image formed by an image forming portion on a first surface of the sheet, to the image forming portion in order to form an image on a second surface of the sheet on a side opposite to the first surface, the sheet transport apparatus including: a re-transport path through which the sheet is re-transported to the image forming portion again; a cooling unit for blowing air into the re-transport path in order to cool the sheet passing through the re-transport path; and an electrical substrate, in which the air having been blown to the sheet from the cooling unit to cool the sheet is prevented from striking the electrical substrate.

Abstract: An image-forming apparatus includes a movable lever which functions as a recording medium detector for detecting the passage of a recording medium and a temperature detecting portion provided on the movable lever. The temperature of the recording medium is detected without providing an additional space for a sensor for detecting the temperature of the recording medium.

Abstract: According to the present invention, a temperature sensing part of temperature sensing means is arranged to come into contact with the surface opposite to the image surface of a recording material at the time of one-sided printing without providing such an opposed member that comes into contact with the image surface of the recording material at least in a position corresponding to the position of the temperature sensing part that is in contact with the recording material.