Patent ID: 7890026

Claim:
A development apparatus which develops an electrostatic image formed on an image bearing member with a developer comprising: a developing container having a first chamber and a second chamber which communicates with the first chamber and to which a developer to be fed is supplied; a developer bearing member which is rotatably provided in the first chamber and feeds the developer to the image bearing member; a regulation member disposed against the developer bearing member, for regulating a layer thickness of the developer on the developer bearing member; a first conveying member which is rotatably provided in the first chamber and conveys the developer in the first chamber; and a second conveying member which is rotatably provided in the second chamber and conveys the developer in the second chamber to the first chamber, wherein a frame of the developing container having the first chamber and the second chamber is formed so as to satisfy the following relationships: 0.5 <Wds /( Wd 1 +Wd 2)7.0, 12.5Wds≦57.5, and Wd1<Wd2 where Wds, Wd 1 , and Wd 2 are defined, as follows: Wds ( W/kg )= Rs×Ts×G/Ms, Wd 1 ( W/kg )=R1 ×T 1 ×G/M 1, and Wd 2 ( W/kg )=R2 ×T 2 G/M 2, Ts is a dynamic torque (kgf·m) of the developer bearing member, T 1 is a dynamic torque (kg·fm) of the first conveying member, T 2 is a dynamic torque (kg·fm) of the second conveying member, Rs is a rotation angle speed (rad/s) of the developer bearing member, R 1 is a rotation angle speed (rad/s) of the first conveying member, R 2 is a rotation angle speed (rad/s) of the second conveying member, and wherein when the first chamber is divided by a perpendicular bisector which bisects a line connecting the most nearest points of the developer bearing member and the first conveying member: Ms is a mass (kg) of the developer which is present in a space of a side of the developer bearing member, M 1 is a mass (kg) of the developer which is present in a space of a side of the first conveying member, M 2 is a mass (kg) of the developer housed in the second chamber, and 1 (kgf)=G×1 (N).