Developing device, process cartridge, and image forming apparatus including an entrance seal which contacts an image bearer

A developing device comprising:

• a developer bearer rotatable in a rotation direction and forming a developing range to develop a latent image on an image bearer;
• a holder including:
• a facing face which faces a portion of the developer bearer upstream from the developing range in the rotation direction of the developer bearer;
• a support face defining a part of an outer face of the developing device;
• and
• a relay face extending from one end of the support face to one end of the relay face connected to the facing face to form an acute tip portion, the acute tip portion closer to the developing range than the one end of the support face;
• and
• an entrance seal including a free end projecting along a length of the entrance seal from the one end of the support face as a cantilever,
• wherein:
• a first length of the entrance seal from a tip of the free end of the entrance seal to the one end of the support face is shorter than a second length of the relay face from the acute tip portion to the one end of the support face at least at a part of a center portion of the entrance seal in a longitudinal direction of the entrance seal,
• a side of the entrance seal which extends along the length of the entrance seal contacting the image bearer at a point of contact, and
• the entrance seal being substantially tangent to the image bearer at the point of contact,
• the developing device further comprising:
• a side seal supported by the support face of the holder and covering a longitudinal end of the developer bearer in an axial direction of the developer bearer;
• and
• an elastic seal covering a part of a longitudinal end of the facing face in the axial direction and a longitudinal end of the relay face in the axial direction.