Toner cartridge

1. A toner cartridge comprising:

a toner storing container of a rectangular shape having a toner feeding opening in an angular portion thereof; and

a stirring conveying member that is rotatably disposed inside the toner storing container in a predetermined rotation direction and that stirs and conveys toner toward the toner feeding opening in the toner storing container,

wherein compression ratio defined by the following equation (1) of the toner stored in the toner storing container is 0.25 to 0.38,

Compression ratio=( P−A )/ P   (1)

(Provided that in the equation (1), P represents a packed bulk density of toner and A represents an aerated bulk density of toner),

wherein the stirring conveying member has an insertion portion insertable to the toner feeding opening at the tip side of the stirring conveying portion and a sliding portion that is disposed adjacent to the insertion portion, the sliding portion having a length from the rotation center longer than the insertion portion and sliding on the inside wall of the toner storing container.

2. The toner cartridge according to claim 1 , wherein the toner has a shape factor (SF) defined by the following equation (2) of not less than 140

SF= 100×(π/4)×(ML 2 / S )  (2)

(Provided that in the equation (2), ML represents the absolute maximum length of toner particles and S represents a projected area of toner particles).

3. The toner cartridge according to claim 1 , wherein the toner is a pulverized toner or a molten and pulverized toner.

4. The toner cartridge according to claim 1 , wherein the toner feeding opening is disposed on the angular portion at one side of the toner storing container of the rectangular shape in a longitudinal direction.

5. The toner cartridge according to claim 1 , wherein the toner storing container has a toner-feeding-side area that is disposed inside of the toner storing container and that is formed in a circular arc shape along the longitudinal direction of the side where the toner feeding opening is located.

6. The toner cartridge according to claim 1 , wherein the toner storing container is equipped with a curvature portion that is disposed inside the toner storing container and that is formed in a corner portion located on an upper side of the toner feeding opening in a state similar to the attachment state of the toner storing container to an image forming apparatus, the curvature portion having a bump raised upward from a changing point at the downstream side in the rotation direction of the stirring conveying member.

7. The toner cartridge according to claim 1 , wherein

the stirring conveying member comprises an axis portion rotatably supported in the toner storing container and a stirring conveying portion having a flexibility of being distorted by the pressure applied by the toner stored in the toner storing container and disposed on the axis portion,

the axis portion comprises a plurality of protrusions that are disposed in the longitudinal direction of the axis portion and that protrude toward the outside from a rotation center, and

the stirring conveying portion has a length such that a tip side away from the rotation center of the stirring conveying portion is able to slide on the inside wall of the toner storing container.

8. The toner cartridge according to claim 1 , wherein the stirring conveying member has a plurality of slits that are formed at a portion corresponding to the toner-feeding-side area of the stirring conveying portion and have a predetermined oblique angle.