Developing cartridge capable of reducing size of image forming apparatus

1. A developing cartridge comprising:

a casing configured to accommodate developer therein, and extending in a first direction;

a coupling rotatable about a first axis extending in the first direction, and being positioned at one side of the casing in the first direction;

a detection gear rotatable about a second axis extending in the first direction, and being positioned at another side of the casing in the first direction opposite the one side; and

a cover mounted at the one side of the casing in the first direction, the cover cooperating with the casing to form a chamber configured to receive a circuit chip holder.

2. The developing cartridge of claim 1 , wherein the cover includes a through-hole in a wall spaced apart from and opposed to the one side.

3. The developing cartridge of claim 2 , further comprising a circuit chip holder positioned within the chamber, the circuit chip holder including a boss extending through the through-hole.

4. The developing cartridge of claim 3 , wherein the circuit chip holder is movable relative to the cover and the casing in a second direction different from the first direction.

5. The developing cartridge of claim 4 , wherein the second direction is perpendicular to the first direction.

6. The developing cartridge of claim 4 , further comprising a circuit chip having an electric contact surface mounted to the circuit chip holder and oriented in the second direction.

7. The developing cartridge of claim 6 , wherein the circuit chip is positioned at the one side of the casing in the first direction.

8. The developing cartridge of claim 1 , wherein the detection gear is rotatable with the coupling.

9. The developing cartridge of claim 8 , further comprising:

a first shaft extending in the first direction, and being rotatable with the coupling,

wherein the detection gear is rotatable with the first shaft.

10. The developing cartridge according to claim 9 , further comprising:

an agitator including the first shaft,

wherein the detection gear is rotatable with the agitator.

11. The developing cartridge according to claim 10 ,

wherein the detection gear is positioned at one side of the first shaft in a second direction perpendicular to the first direction, and

wherein the coupling is positioned at the one side of the first shaft in the second direction.

12. The developing cartridge according to claim 10 ,

wherein the coupling further includes:

a coupling gear rotatable with the coupling,

wherein the agitator further includes:

a first agitator gear mounted to the first shaft, and being rotatable with the first shaft and positioned at one side of the casing in the first direction, and

wherein the coupling gear meshes with the first agitator gear.

13. The developing cartridge according to claim 10 , further comprising:

a first idle gear positioned at the one side of the casing in the first direction,

wherein the coupling further includes:

a coupling gear rotatable with the coupling, and the coupling gear meshing with the first idle gear, and

wherein the agitator further includes:

a first agitator gear mounted to the first shaft, and being rotatable with the first shaft, positioned at the one side of the casing in the first direction, and meshing with the first idle gear.

14. The developing cartridge according to claim 10 ,

wherein the agitator further includes:

a second agitator gear mounted to the first shaft, being rotatable with the first shaft and positioned at the other side of the casing in the first direction, and

wherein the second agitator gear meshes with the detection gear.

15. The developing cartridge according to claim 10 , further comprising:

a second idle gear positioned at the other side of the casing in the first direction, and the second idle gear meshing with the detection gear;

wherein the agitator further includes:

a second agitator gear mounted to the first shaft, being rotatable with the first shaft and being positioned at the other side of the casing in the first direction and meshing with the second idle gear.

16. The developing cartridge according to claim 1 , further comprising:

a developing roller rotatable about a rotational axis extending in the first direction, the developing roller including a roller shaft extending in the first direction; and

an electrode being electrically connected to the roller shaft, and being positioned to the other side of the casing in the first direction.

17. The developing cartridge according to claim 1 , wherein the coupling includes a recessed portion configured to receive a driving force.

18. The developing cartridge according to claim 1 , wherein the coupling includes a concave portion configured to receive a driving force.

19. The developing cartridge according to claim 1 , wherein the detection gear has a shape representing information regarding a specification of the developing cartridge.

20. The developing cartridge according to claim 19 , wherein the specification represents a number of pages printable by the developing cartridge.

21. The developing cartridge according to claim 1 , wherein the detection gear is rotatable between a first position representing the developing cartridge in an unused state and a second position representing the developing cartridge in a used state.

22. The developing cartridge according to claim 1 , wherein the detection gear includes a plurality of gear teeth provided on a portion of an outer peripheral surface of the detection gear.

23. The developing cartridge according to claim 1 , wherein the detection gear includes a protrusion extending in the first direction.

24. The developing cartridge according to claim 23 , wherein the detection gear includes a plurality of the protrusions.