US Patent 9188906 Cartridge, developing cartridge, process cartridge and image forming apparatus

A cartridge includes: a toner chamber, provided with an opening, for accommodating a toner; and a seal member including a sealing portion, elongated in a longitudinal direction of the cartridge, for unsealably sealing the opening and a mounting portion for being mounted on an unsealing member to unseal the opening. The sealing portion includes a first sealing portion located at a longitudinal end portion and a second sealing portion located at a longitudinal central portion. With respect to a direction crossing the longitudinal direction, a length between the first sealing portion and the mounting portion of the seal member is shorter than a length between the second sealing portion and the mounting portion.