A developing device includes an agitating member, a magnetic roller, a lower housing, an upper housing and a blade member. The lower housing includes a first housing part including a first edge having a first contact face and a first facing surface at a blade member's side. The upper housing includes a second housing part including a second edge having a second contact face contact with the first contact face and a second facing surface facing to the first facing surface. The blade member is attached to the upper housing and arranged at a gap to the lower housing. Between the first and second facing surfaces, a width at a blade member's side is broader than a width at a first contact face's side. The first and second facing surfaces are bonded by an adhesive agent. The gap is sealed by the adhesive agent.

Disclosed is a development cartridge detachable from a main body of an image forming apparatus. The development cartridge includes a lateral waste toner sealing member contacting an end portion of a photosensitive drum in a lengthwise direction of the photosensitive drum to prevent a waste toner from leaking through the end portion of the photosensitive drum, and a photosensitive frame including a waste toner container to contain the waste toner, a first attachment surface, to which the lateral waste toner sealing member is attached, and a side wall to form a boundary at an upstream side of the first attachment surface with respect to a rotation direction of the photosensitive drum. The lateral waste toner sealing member includes an opposite surface facing the side wall, and a protrusion protruding towards the side wall is provided on the opposite surface.

A seal member includes a first seal portion abutting an end portion of a rotating body to seal a gap between a storage container and the end portion, and a second seal portion abutting an end portion of a blade to seal a gap between the storage container and the end portion. The second seal portion has a tip contacting portion to contact a tip portion of the blade and a non-tip contacting portion to contact a portion of the blade except for the tip portion. The non-tip contacting portion is recessed to form a step between the non-tip contacting portion and the tip contacting portion. The tip contacting portion includes a base portion to contact with the storage container, an abutting portion configured to abut the blade, and a connecting portion which connects the base portion and the abutting portion to each other.

A toner sealing system is described including a seal having first and second alignment features. The seal is selectably installable on one of a first toner container of a first type and a second toner container of a second type. The first alignment feature is matable with a first corresponding alignment feature on the first toner container when the seal is installed on the first toner container for aligning the seal to the first toner container. The second alignment feature is matable with a second corresponding alignment feature on the second toner container when the seal is installed on the second toner container for aligning the seal to the second toner container. Embodiments include those wherein the first alignment feature does not align the seal to the second toner container, and the second alignment feature does not align the seal to the first toner container.

A process cartridge includes a first unit including an image bearing member to bear a developing agent image, a second unit including a development frame member in which a developing agent bearing member to bear a developing agent to be supplied to the image bearing member is supported, and a coupling portion that can couple the first and second units such that the second unit is swingable with the coupling portion as a rotation center. The development frame member includes a replenishing opening for the developing agent, and an elastically-deformable sealing member that seals the supply portion and the replenishing opening. As viewed along a compression direction of the sealing member, in a section orthogonal to a longitudinal direction of the process cartridge, the rotation center is disposed at a position overlapping with the sealing member.

A developing device includes an agitating member, a magnetic roller, a lower housing, an upper housing and a blade member. The lower housing includes a first housing part including a first edge having a first contact face and a first facing surface at a blade member's side. The upper housing includes a second housing part including a second edge having a second contact face contact with the first contact face and a second facing surface facing to the first facing surface. The blade member is attached to the upper housing and arranged at a gap to the lower housing. Between the first and second facing surfaces, a width at a blade member's side is broader than a width at a first contact face's side. The first and second facing surfaces are bonded by an adhesive agent. The gap is sealed by the adhesive agent.

A development device includes a layer thickness regulating blade including a support sheet metal, a blade rubber section, and a side edge seal, the support sheet metal having a first end portion, a second end portion, and a center portion between the first end portion and the second end portion, in an axial direction of a development roller. In a width direction of the support sheet metal, the first end portion of the support sheet metal in the axial direction is shorter than the center portion of the support sheet metal in the axial direction. In the width direction, a distal-end edge of the first end portion of the support sheet metal is closer to a base end portion of the support sheet metal than a distal-end edge of the blade rubber section.

A developing device may include a housing to accommodate a developing agent, a developing roller to convey the developing agent adhered to an outer periphery of the developing roller to an outside of the housing, a regulation member positioned apart from the developing roller and having a circular cross-sectional shape to regulate a thickness of the developing agent adhered to the developing roller, and a sealing member between the regulation member and the housing to prevent leakage of the developing agent. A diameter of a central portion of the regulation member may be different from diameters of both end portions of the regulation member.

Disclosed is a development cartridge detachable from a main body of an image forming apparatus. The development cartridge includes a lateral waste toner sealing member contacting an end portion of a photosensitive drum in a lengthwise direction of the photosensitive drum to prevent a waste toner from leaking through the end portion of the photosensitive drum, and a photosensitive frame including a waste toner container to contain the waste toner, a first attachment surface, to which the lateral waste toner sealing member is attached, and a side wall to form a boundary at an upstream side of the first attachment surface with respect to a rotation direction of the photosensitive drum. The lateral waste toner sealing member includes an opposite surface facing the side wall, and a protrusion protruding towards the side wall is provided on the opposite surface.

A developing device includes a developer carrying member, a developing frame, and a regulating member. The regulating member includes a curved surface portion contactable to a surface of the developer carrying member, and satisfies the following relationships: 200 MPaHM1100 MPa, and 0.08 mmRb0.3 mm, where HM is a Martens hardness of toner contained in the developer under a maximum load of 2.010.sup.4 N, and Rb is a radius of curvature of the curved surface portion.