A developing device includes a frame, a cylindrical developer carrying member rotatably supported by the frame and configured to carry a developer containing toner particles, and a regulating member fixed to the frame at one end thereof and including a contact portion which contacts the developer carrying member at the other end of the regulating member and which forms a contact nip between the regulating member and the developer carrying member. When a position of the contact portion where a maximum of a pressure distribution of the contact portion to the developer carrying member with respect to a rotational direction of the developer carrying member is indicated is a reference position, the contact portion includes a first surface portion positioned upstream of the reference position and a second surface portion positioned downstream of the reference position with respect to the rotational direction.

A developing device includes a development casing, a developer carrying member, a regulating blade, a pair of pressing members, and a blade seal member. The development casing has an opening part. The developer carrying member has a developing area. The blade seal member includes a first layer material and a second layer material. The development casing has facing surfaces. The second layer material has positioning protrusions protruding from the first layer material in a rotation axis direction at positions inside both ends of the first layer material in the rotation axis direction, so as to contact the facing surfaces and be positioned in the rotation axis direction. When the second layer material is positioned in the rotation axis direction, the first layer material is pressed in contact with the pressing members in the rotation axis direction.

A developing device includes a frame, a cylindrical developer carrying member rotatably supported by the frame and configured to carry a developer containing toner particles, and a regulating member fixed to the frame at one end thereof and including a contact portion which contacts the developer carrying member at the other end of the regulating member and which forms a contact nip between the regulating member and the developer carrying member. When a position of the contact portion where a maximum of a pressure distribution of the contact portion to the developer carrying member with respect to a rotational direction of the developer carrying member is indicated is a reference position, the contact portion includes a first surface portion positioned upstream of the reference position and a second surface portion positioned downstream of the reference position with respect to the rotational direction.

The developing device includes a development container, a developer carrier, and a restricting blade. The development container has an opening. The developer carrier has a development area. The development container includes a pair of side frames, and a pair of side wall portions. In each of the pair of side wall portions, a seal member insertion hole extending through in the rotation-axial direction is formed at a position facing an end edge of the restricting blade in the rotation-axial direction. The developing device includes a blade-side side seal inserted in the seal member insertion hole to block a gap between the restricting blade and the side wall portion.

A restricting member includes a blade portion and a supporting portion. A contact portion is provided at the blade portion, and, in a cross section orthogonal to a longitudinal direction, the contact portion includes a first portion extending in a first direction and a second portion extending toward a free end from an end of the first portion and extending in a second direction. When a region demarcated by connecting an intersection point, the end of the first portion, and an end of the second portion by a straight line is defined as a first region, the intersection point being where an imaginary line intersects an extension line of the first portion in the first direction, an area of the first region is smaller on a longitudinal end portion than on a longitudinal central portion of the blade portion.

A developing device includes a development casing, a developer carrying member, a regulating blade, a pair of pressing members, and a blade seal member. The development casing has an opening part. The developer carrying member has a developing area. The blade seal member includes a first layer material and a second layer material. The development casing has facing surfaces. The second layer material has positioning protrusions protruding from the first layer material in a rotation axis direction at positions inside both ends of the first layer material in the rotation axis direction, so as to contact the facing surfaces and be positioned in the rotation axis direction. When the second layer material is positioned in the rotation axis direction, the first layer material is pressed in contact with the pressing members in the rotation axis direction.

A developing device includes a development casing, a developer carrying member, and a regulating blade. The development casing has an opening part. The developer carrying member has a developing area. The development casing has a blade facing part. The regulating blade includes a fixed part and a regulating part, and a space between the regulating part and the blade facing part is larger than a space between the fixed part and the blade facing part. The developing device further includes a blade seal member. The blade seal member is disposed between the regulating blade and the blade facing part, and is glued to an upstream side surface of the regulating part in the rotation direction, so as to seal a gap between the regulating blade and the blade facing part.

The developing device includes a development container, a developer carrier, and a restricting blade. The development container has an opening. The developer carrier has a development area. The development container includes a pair of side frames, and a pair of side wall portions. In each of the pair of side wall portions, a seal member insertion hole extending through in the rotation-axial direction is formed at a position facing an end edge of the restricting blade in the rotation-axial direction. The developing device includes a blade-side side seal inserted in the seal member insertion hole to block a gap between the restricting blade and the side wall portion.

A developing device includes a regulating member fixed to a frame at one end thereof and including a contact portion which contacts a developer carrying member. The contact portion includes a first region positioned upstream of a reference position and a second region positioned downstream of the reference position in a rotational direction of the developer carrying member. A length of the second region is longer than a length of the first region in a position corresponding to a contact nip with respect to a direction from a fixed end of the regulating member toward the other end as a free end of the regulating member, and the contact portion has a surface roughness smaller in the first region than in the second region, with the surface roughness in the second region being 20% or less of an average particle size of toner particles contained in a developer.

A developing device includes a development casing, a developer carrying member, and a regulating blade. The development casing has an opening part. The developer carrying member has a developing area. The development casing has a blade facing part. The regulating blade includes a fixed part and a regulating part, and a space between the regulating part and the blade facing part is larger than a space between the fixed part and the blade facing part. The developing device further includes a blade seal member. The blade seal member is disposed between the regulating blade and the blade facing part, and is glued to an upstream side surface of the regulating part in the rotation direction, so as to seal a gap between the regulating blade and the blade facing part.