Coupling structure for a developing roller of an image forming apparatus

A development cartridge, comprising:

• a photoconductor;
• and
• a developing roller, to supply a printing material to the photoconductor, the developing roller including:
• a roller body, and
• a shaft to pass through a central axis of the roller body, an end part of the shaft including a coupling structure movable from a first position to a second position, the coupling structure including a first coupling piece, and a second coupling piece connected to the first coupling piece, and
• positions of the first coupling piece and the second coupling piece are maintained with respect to one another by a static frictional force between surfaces of the first coupling piece and the second coupling piece so as to hold the coupling structure in the first position, and
• when a predetermined force sufficient to overcome the static frictional force is applied to the coupling structure, the first coupling piece and the second coupling piece disengage from one another to allow the coupling structure to move from the first position to the second position.

An image forming apparatus, comprising:

• a main body;
• and
• a development cartridge installable to the main body and detachable from the main body, the development cartridge including:
• a photoconductor, and
• a developing roller, to supply a printing material to the photoconductor, the developing roller including:
• a roller body, and
• a shaft to pass through a central axis of the roller body, an end part of the shaft including a coupling structure movable from a first position to a second position, the coupling structure including a first coupling piece, and a second coupling piece connected to the first coupling piece, and
• when the development cartridge is inserted into the main body during installation of the development cartridge to the main body, positions of the first coupling piece and the second coupling piece are maintained with respect to one another by a static frictional force between surfaces of the first coupling piece and the second coupling piece so as to hold the coupling structure in the first position, and
• when a predetermined force is applied to rotate the development cartridge within the main body after installation of the development cartridge to the main body, the static frictional force between surfaces of the first coupling piece and the second coupling piece is overcome such that the first coupling piece and the second coupling piece disengage from one another to allow the coupling structure to move from the first position to the second position.