Patent ID: 8412079

Claim:
A toner cartridge comprising a container body having a toner containing space for containing a toner, and a screw conveyer section provided in the toner containing space of the container body, for conveying the toner toward a toner discharge part for discharging the toner, the screw conveyor section facing the toner discharge part, the screw conveyer section comprising a rotation shaft having a rotation axis in parallel with a conveying direction of a toner, and a spiral toner conveying blade provided on the rotation shaft, the rotation shaft including a first rotation shaft portion, and a second rotation shaft portion concentrically continuing from the first rotation shaft portion and having a diameter smaller than that of the first rotation shaft portion, the first rotation shaft portion being provided only at a position facing the toner discharge part, the toner conveying blade including a first blade portion formed on the first rotation shaft portion, and a second blade portion formed on the second rotation shaft portion, a pitch of the second blade portion winding around the second rotation shaft portion of the rotation shaft being smaller than a pitch of the first blade portion winding around the first rotation shaft portion of the rotation shaft, an effective screw cross-sectional area S 1 of the first rotation shaft portion in the screw conveyor section being represented by the following expression (1), S ⁢ ⁢ 1 = ( R 2 ) 2 ⁢ π - ( r ⁢ ⁢ 1 2 ) 2 ⁢ π , ( 1 ) an effective screw cross-sectional area S 2 of the second rotation shaft portion in the screw conveyor section being represented by the following expression (2), S ⁢ ⁢ 2 = ( R 2 ) 2 ⁢ π - ( r ⁢ ⁢ 2 2 ) 2 ⁢ π , ⁢ and ( 2 ) S 1 , S 2 , P 1 and P 2 satisfying the following expression (3), P 1 ×S 1 =P 2 ×S 2 (3), wherein R denotes an outer diameter of the screw conveyor section, r 1 denotes a shaft diameter of the first rotation shaft portion, r 2 denotes a shaft diameter of the second rotation shaft portion, P 1 denotes the pitch of the first blade portion and P 2 denotes the pitch of the second blade portion.