Conveying device and image forming apparatus incorporating the conveying device

1. A conveying device comprising:

a conveying body having an elastic material and configured to convey one of toner and developer; and

a conveyance passage, including the conveying body therein, to convey the one of toner and developer in a conveying direction as the conveying body rotates,

the conveying passage including an inlet portion, formed at an upstream side of the conveyance passage, and configured to pass the one of toner and developer into the conveyance passage,

the conveying body including an exposed portion, exposed through the inlet portion and exposed inside the conveyance passage, and

a portion of the exposed portion of the conveying body including a high rigidity portion having rigidity relatively greater than a rigidity of a non-high rigidity portion of the conveying body, wherein M represents an opening width of the inlet portion in the conveying direction and N represents a length of the high rigidity portion of the conveying body in the conveying direction, and wherein M>N.

2. The conveying device according to claim 1 ,

wherein the high rigidity portion is disposed at an upstream side of the inlet portion in the conveying direction.

3. The conveying device according to claim 1 ,

wherein the conveying body is a conveying screw.

4. The conveying device according to claim 3 ,

wherein M represents an opening width of the inlet portion in the conveying direction, N represents a length of the high rigidity portion of the conveying screw in the conveying direction, and H represents a screw pitch of the conveying screw, and wherein M>N+¼×H.

5. The conveying device according to claim 3 ,

wherein the conveying screw includes a screw portion and a shaft around which the screw portion is wound in a spiral,

wherein an outer diameter of the shaft of the conveying screw at the high rigidity portion is relatively greater than an outer diameter of the shaft of the conveying screw at the non-high rigidity portion, and

wherein a screw diameter of the screw portion of the conveying screw at the high rigidity portion is equal to a screw diameter of the screw portion of the conveying screw at the non-high rigidity portion.

6. The conveying device according to claim 5 ,

wherein the outer diameter of the shaft of the conveying screw at the high rigidity portion gradually decreases toward an downstream side in the conveying direction, and

wherein the outer diameter of the shaft of the conveying screw at the high rigidity portion is equal to the outer diameter of the shaft of the conveying screw at the non-high rigidity portion at a downstream end of the conveying screw in the conveying direction.

7. The conveying device according to claim 1 ,

wherein the conveying body includes a drive shaft adjacent to the high rigidity portion and rotatably held by a housing of the conveying device via a bearing and, a drive gear being mounted on the drive shaft,

wherein the conveyance passage includes a straight conveyance passage and a curved conveyance passage and wherein the conveyance passage includes an outlet portion configured to pass the one of toner and developer, and

wherein the inlet portion is formed in the straight conveyance passage.

8. An image forming apparatus comprising the conveying device according to claim 1 .

9. A conveying device comprising:

a conveying screw having an elastic material and configured to convey one of toner and developer;

a conveyance passage including the conveying screw therein, to convey the one of toner and developer in a conveying direction as the conveying screw rotates,

the conveying passage including an inlet portion, formed at an upstream side of the conveyance passage, and configured to pass the one of toner and developer into the conveyance passage,

the conveying screw including a screw portion and a shaft around which the screw portion is wound in a spiral, and including a first shaft portion and a second shaft portion, an outer diameter of the first shaft portion of the conveying screw being relatively greater than an outer diameter of the second shaft portion of the conveying screw, and a screw diameter of the screw portion of the first shaft portion of the conveying screw being equal to a screw diameter of the second shaft portion of the conveying screw, wherein M represents an opening width of the inlet portion in the conveying direction, N represents a length of the first shaft portion of the conveying screw in the conveying direction, and H represents a screw pitch of the conveying screw, and wherein M>N+¼×H.

10. The conveying device according to claim 9 ,

wherein the outer diameter of the first shaft portion of the conveying screw gradually decreases toward an downstream side in the conveying direction, and

wherein the outer diameter of the first shaft portion of the conveying screw is equal to the outer diameter of the second shaft portion of the conveying screw at a downstream end of the conveying screw in the conveying direction.

11. The conveying device according to claim 9 ,

wherein the conveying screw includes a drive shaft adjacent to the first shaft portion and rotatably held by a housing of the conveying device via a bearing, a drive gear being mounted on the drive shaft,

wherein the conveyance passage includes a straight conveyance passage and a curved conveyance passage and wherein the conveyance passage includes an outlet portion configured to pass the one of toner and developer, and

wherein the inlet portion is formed in the straight conveyance passage.

12. An image forming apparatus comprising the conveying device according to claim 9 .

13. The conveying device of claim 9 , wherein M represents an opening width of the inlet portion in the conveying direction and N represents a length of the first shaft portion of the conveying screw in the conveying direction, and wherein M>N.

14. An image forming apparatus comprising the conveying device according to claim 13 .

15. A conveying device comprising:

a conveying screw having an elastic material and configured to convey one of toner and developer; and

a conveyance passage, including the conveying screw therein, to convey the one of toner and developer in a conveying direction as the conveying screw rotates,

the conveying passage including an inlet portion, formed at an upstream side of the conveyance passage, and configured to pass the one of toner and developer into the conveyance passage,

the conveying screw including an exposed portion, exposed through the inlet portion and exposed inside the conveyance passage, and

a portion of the exposed portion of the conveying screw including a high rigidity portion having rigidity relatively greater than a rigidity of a non-high rigidity portion of the conveying screw, wherein M represents an opening width of the inlet portion in the conveying direction, N represents a length of the high rigidity portion of the conveying screw in the conveying direction, and H represents a screw pitch of the conveying screw, and wherein M>N+¼×H.

16. The conveying device according to claim 15 ,

wherein the conveying screw includes a screw portion and a shaft around which the screw portion is wound in a spiral,

wherein an outer diameter of the shaft of the conveying screw at the high rigidity portion is relatively greater than an outer diameter of the shaft of the conveying screw at the non-high rigidity portion, and

wherein a screw diameter of the screw portion of the conveying screw at the high rigidity portion is equal to a screw diameter of the screw portion of the conveying screw at the non-high rigidity portion.

17. The conveying device according to claim 16 ,

wherein the outer diameter of the shaft of the conveying screw at the high rigidity portion gradually decreases toward an downstream side in the conveying direction, and

wherein the outer diameter of the shaft of the conveying screw at the high rigidity portion is equal to the outer diameter of the shaft of the conveying screw at the non-high rigidity portion at a downstream end of the conveying screw in the conveying direction.