US 7,890,026 B2Granted

Development apparatus and image forming apparatus

AssigneeCanon Kabushiki Kaisha

InventorShoji Naruge

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Abstract

When dynamic torques are Ts, Ti, and T2, respectively, and rotation angle speeds are Rs, R1, and R2, respectively, at the time of rotations of the developing sleeve 40 and the screws 41 and 42, the mass of the developer housed in the second agitating chamber 902 is M2, the mass of the developer which is present in the space of the side of the developing sleeve when a space formed by the developing chamber 900 and the first agitating chamber 901 is divided is Ms, the mass of the developer which is present in the space of the side of the screw 41 is M1, gravitational acceleration is G, each load on the developer by rotations of the developing sleeve and the screws is defined as Wds (mW/g)=Rs×Ts×G/Ms, Wd1(mW/g)=R1×T1×G/M1, and Wd2 (mW/g)=R2×T2×G/M2, respectively, relationships of 0.5<Wds/(Wd1+Wd2)≦7.0, 12.5≦Wds≦57.5, and Wd1<Wd2 are satisfied.

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/(Wd1+Wd2)7.0,
12.5Wds≦57.5, and
Wd1<Wd2
where Wds, Wd1, and Wd2 are defined, as follows:
Wds(W/kg)=Rs×Ts×G/Ms,
Wd1 (W/kg)=R1×T1×G/M1, and
Wd2 (W/kg)=R2×T2G/M2,
Ts is a dynamic torque (kgf·m) of the developer bearing member,
T1 is a dynamic torque (kg·fm) of the first conveying member,
T2 is a dynamic torque (kg·fm) of the second conveying member,
Rs is a rotation angle speed (rad/s) of the developer bearing member,
R1 is a rotation angle speed (rad/s) of the first conveying member,
R2 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,
M1 is a mass (kg) of the developer which is present in a space of a side of the first conveying member,
M2 is a mass (kg) of the developer housed in the second chamber, and
1 (kgf)=G×1 (N).

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Abstract

Claims3