Image forming apparatus

1. An image forming apparatus comprising:

a main body casing having an opening and a slot extending in from the opening toward an inside of the main body casing along a first direction;

a drum cartridge including a photosensitive drum rotatable about a first axis extending in the first direction, the drum cartridge being removably insertable into the slot through the opening in the first direction; and

a developing cartridge including a developing roller rotatable about a second axis extending in the first direction, the developing cartridge being removably insertable into the slot through the opening in the first direction,

wherein the drum cartridge and the developing cartridge are arranged in a second direction intersecting the first direction in a state where the drum cartridge and the developing cartridge are attached to the slot,

wherein the main body casing includes a developing guide groove configured to guide movement of the developing cartridge, and the developing guide groove extends in the first direction,

wherein the developing cartridge includes a developing protrusion configured to be engaged with the developing guide groove, and the developing protrusion extends in the first direction, and

wherein a width of the developing guide groove in the second direction is decreased toward the inside of the main body casing from the opening.

2. The image forming apparatus, according to claim 1 , wherein the developing guide groove has a tapered shape.

3. The image forming apparatus, according to claim 1 , wherein a width of the developing protrusion in the second direction is decreased toward the inside of the main body casing from the opening in a state where the developing cartridge is attached to the slot.

4. The image forming apparatus, according to claim 3 , wherein the developing protrusion has a tapered shape.

5. The image forming apparatus, according to claim 1 ,

wherein the main body casing includes a drum guide groove configured to guide movement of the drum cartridge, and the drum guide groove extends in the first direction, and

wherein the drum guide groove has a tapered shape.

6. The image forming apparatus, according to claim 1 ,

wherein the main body casing includes a drum guide groove configured to guide movement of the drum cartridge, and the drum guide groove extends in the first direction,

wherein the drum cartridge includes a drum protrusion configured to be engaged with the drum guide groove, and the drum protrusion extends in the first direction, and

wherein a width of the drum protrusion in the second direction is decreased toward the inside of the main body casing from the opening in a state where the drum cartridge is attached to the slot.

7. The image forming apparatus, according to claim 6 , wherein the drum protrusion has a tapered shape.

8. The image forming apparatus, according to claim 1 ,

wherein the main body casing includes a drum guide groove configured to guide movement of the drum cartridge, and the drum guide groove extends in the first direction,

wherein the drum cartridge includes a first drum cartridge and a second drum cartridge,

wherein the drum guide groove includes a first drum guide groove and the second drum guide groove, the first drum guide groove is configured to guide movement of the first drum cartridge, the first drum guide groove extends in the first direction, the second drum guide groove is configured to guide movement of the second drum cartridge, and the second drum guide groove extends in the first direction, and

wherein a first width of the first drum guide groove in the second direction is same as a second width of the second drum guide groove in the second direction.

9. The image forming apparatus, according to claim 1 ,

wherein the developing cartridge includes a first developing cartridge storing a first color developer and a second developing cartridge storing a second color developer, and

wherein the developing guide groove includes a first developing guide groove and the second developing guide groove, the first developing guide groove is configured to guide movement of the first developing cartridge, the first developing guide groove extends in the first direction, the second developing guide groove is configured to guide movement of the second developing cartridge, and the second developing guide groove extends in the first direction, and

wherein a first width of the first developing guide groove in the second direction is different from a second width of the second developing guide groove in the second direction.

10. The image forming apparatus, according to claim 1 , further comprising:

a cover movable between an open position in which the cover does not cover the opening and a closed position in which the cover covers the opening,

wherein the main body casing includes a sidewall spaced from the cover in a state where the cover is the closed position,

wherein the sidewall includes a first hole,

wherein the drum cartridge includes a drum sidewall protrusion configured to engage the first hole in a state where the drum cartridge is attached to the slot.

11. The image forming apparatus, according to claim 10 ,

wherein the drum cartridge includes a first drum sidewall and a second drum sidewall, the first drum sidewall and the second drum sidewall facing each other in the first direction, the first drum sidewall being positioned closer to the opening than the second drum sidewall in the first direction in a state where the drum cartridge is attached to the slot, and

wherein the drum sidewall protrusion is positioned at the second drum sidewall.

12. The image forming apparatus, according to claim 10 ,

wherein the sidewall includes a second hole,

wherein the developing cartridge includes a developing sidewall protrusion configured to engage the second hole in a state where the developing cartridge is attached to the slot.

13. The image forming apparatus, according to claim 12 ,

wherein the developing cartridge includes a first developing sidewall and a second developing sidewall, the first developing sidewall and the second developing sidewall facing each other in the first direction, the first developing sidewall being positioned closer to the opening than the second developing sidewall in the first direction in a state where the developing cartridge is attached to the slot,

wherein the developing sidewall protrusion is positioned at the second developing sidewall.

14. The image forming apparatus, according to claim 1 , further comprising:

an intermediate transfer belt positioned above the drum cartridge and the developing cartridge in a state where the drum cartridge and the developing cartridge are attached to the slot.

15. The image forming apparatus, according to claim 1 , further comprising a discharge unit including a discharge roller configured to convey a sheet, the discharge unit being positioned above the intermediate transfer belt.

16. The image forming apparatus, according to claim 1 ,

wherein the second direction is intersecting to an up-down direction.

17. The image forming apparatus, according to claim 16 ,

wherein the second direction is perpendicular to the first direction and the up-down direction.

18. The image forming apparatus, according to claim 1 ,

wherein the width of the developing guide groove decreases in the second direction along the entire length of the developing guide groove from the opening to an opposite side of the main body casing.