Developing device provided with sealing members assembled to thickness-regulation member

A process unit comprising:

• a photosensitive member having a circumferential surface on which an electrostatic latent image is formed;
• and
• a developing device for supplying developer to the electrostatic latent image, the developing device comprising:
• a casing having an opening extending in a first direction;
• a developing roller positioned adjacent to the opening and configured to rotate about an axis extending in the first direction, the developing roller having an outer circumferential surface on which developer is carried;
• a thickness-regulation member comprising:
• a thin-plate member extending in the first direction along the opening and having a base end portion fixed to the casing and extending in the first direction and a free end portion, the thin-plate member having a lateral end extending in a second direction crossing the first direction;
• and
• a regulating portion extending in the first direction and fixed to the free end portion, the regulating portion being in contact with the outer circumferential surface of the developing roller via the developer for regulating thickness of the developer on the outer circumferential surface, the regulating portion having an end face extending in a direction crossing the first direction;
• an engagement portion fixed on the thin-plate member and positioned closer to tie lateral end than the end face is to the lateral end to provide a groove between the engagement portion and the end face, the groove having a length in the first direction;
• and
• a sealing member fitted in the groove for suppressing leakage of the developer from the casing, the sealing member having a length in the first direction longer than the length of the groove prior to assembly of the sealing member into the groove.

An image forming device comprising:

• a process unit comprising:
• a photosensitive member having a circumferential surface on which an electrostatic latent image is formed;
• and
• a developing device for supplying developer to the electrostatic latent image to form a developer image, the developing device comprising:
• a casing having an opening extending in a first direction;
• a developing roller positioned adjacent to the opening and configured to rotate about an axis extending in the first direction, the developing roller having an outer circumferential surface on which developer is carried;
• a thickness-regulation member comprising:
• a thin-plate member extending in the first direction along the opening and having a base end portion fixed to the casing and extending in the first direction and a free end portion, the thin-plate member having a lateral end extending in a second direction crossing the first direction;
• and
• a regulating portion extending in the first direction and fixed to the free end portion, the regulating portion being in contact with the outer circumferential surface of the developing roller via the developer for regulating thickness of the developer on the outer circumferential surface, the regulating portion having an end face extending in a direction crossing the first direction;
• an engagement portion fixed on the thin-plate member and positioned closer to the lateral end than the end face is to the lateral end to provide a groove between the engagement portion and the end face, the groove having a length in the first direction;
• and
• a sealing member fitted in the groove for suppressing leakage of the developer from the casing, the sealing member having a length in the first direction longer than the length of the groove prior to assembly of the sealing member into the groove;
• an exposure unit that exposes a scanned light to the photosensitive member;
• a transfer unit that transfers a developer image formed in the process unit to a sheet;
• and
• a fixing unit that fixes the developer image to the sheet.