Developing device and image forming apparatus

An image forming apparatus comprising:

• a latent image bearer on which a latent image is formed;
• and
• a developing device to develop with developer the latent image,
• a developer bearer to transport by rotation developer carried on a surface thereof to a development range to supply developer to the latent image bearer;
• a development casing in which a developer conveyance channel is formed, the developer conveyance channel facing the developer bearer through a communicating area inside the development casing;
• a developer supply member disposed in the developer conveyance channel to transport developer in an axial direction of the developer bearer and supply developer to the developer bearer;
• a developer regulator disposed facing a lower portion of the developer bearer to adjust an amount of developer carried on the developer bearer;
• a sheet member removably installed to seal the communicating area between the developer bearer and the developer conveyance channel so as to pass through a gap between the developer regulator and the developer bearer and an opening formed in the development casing, wherein a first end of the sheet member is retained downstream from the gap in a direction of rotation of the developer bearer, wherein the sheet member is fixed to the development casing at a position across the communicating area from the first end thereof with a second end of the sheet member opposite the first end positioned outside the development casing;
• a developer collecting member to axially transport developer received from the developer bearer at a position downstream from the development range in the direction of rotation of the developer bearer;
• and
• a partition to divide the developer conveyance channel into a supply channel in which the developer supply member is disposed and a collecting channel in which the developer collecting member is disposed;
• wherein the communicating area includes a first communicating opening where the developer bearer faces the supply channel and a second communicating opening where the developer bearer faces the collecting channel;
• wherein the sheet member seals both the first communicating opening and the second communicating opening;
• wherein a guide face to guide the sheet member is provided at either end of the development casing in the axial direction of the developer bearer;
• wherein an end face of the partition facing the developer bearer is continuous with the guide faces at the respective ends in the axial direction;
• wherein, in the direction of rotation of the developer bearer, the guide face extends from the end face of the partition to the developer regulator;
• and
• wherein a distance between the guide face and the surface of the developer bearer is identical to a distance between the end face of the partition and the surface of the developer bearer.

A developing device comprising:

• a developer bearer to transport by rotation developer carried on a surface thereof to a development range to supply developer to a latent image bearer;
• a development casing in which a developer conveyance channel is formed, the developer conveyance channel facing the developer bearer through a communicating area inside the development casing;
• a developer supply member disposed in the developer conveyance channel to transport developer in an axial direction of the developer bearer and supply developer to the developer bearer;
• a developer regulator disposed facing a lower portion of the developer bearer in a gravity direction, and to adjust an amount of developer carried on the developer bearer;
• and
• a sheet member removably installed in the development casing to seal the communicating area so as to pass through a gap between the developer regulator and the developer bearer and an opening formed in the development casing;
• wherein a first end of the sheet member is retained downstream from the gap in a direction of rotation of the developer bearer at a first location, and a second end of the sheet member is attached to an outside of the development casing at a second location;
• wherein a virtual straight line connecting the first location and the second location of the sheet member is diagonal with respect to the gravity direction, wherein the virtual straight line intersects the developer bearer disposed inside the development casing, and wherein the first location and the second location are on opposite sides of the developer bearer in a horizontal direction that is perpendicular to the gravity direction such that a range of the sheet member contacting around the developer bearer is less than half of one cycle of the surface in a rotational direction of the developer bearer;
• wherein the opening is formed in an upper portion of the development casing;
• and
• wherein the second end of the sheet member is attached on an outer surface of the upper portion, and pulled in removal of the sheet member from the developing device.