Image forming apparatus

1. An image forming apparatus comprising:

a fixing unit that includes a heating roller that heats a non-fixed image formed on a sheet, and a pressure roller that nips the sheet between the pressure roller and the heating roller to press the sheet, and fixes the non-fixed image to the sheet;

a housing that contains the fixing unit;

an exterior cover that is openably and closably provided for the housing, and forms an exterior of the image forming apparatus with the exterior cover closed;

a sheet guide member that is provided in the exterior cover, is openable and closable relative to the housing with the exterior cover opened, and occupies a close position where the sheet guide member is closed to guide a sheet that has passed through the fixing unit downstream in a sheet conveyance direction, and an open position where the sheet guide member is opened to allow access of a worker to the fixing unit;

a lock lever that is provided for the sheet guide member, and engages with the housing to lock the sheet guide member at the close position;

an operation lever that is provided for the sheet guide member under the lock lever in a vertical direction, moves the pressure roller at a first pressing position where the pressure roller presses the heating roller with a first pressing force, to a second pressing position where the pressure roller presses the heating roller with a second pressing force smaller than the first pressing force, rotates relative to the sheet guide member, is in a first orientation when the pressure roller is at the first pressing position, and is in a second orientation when the pressure roller is at the second pressing position, and rotates from the second orientation to the first orientation according to movement of the sheet guide member from the close position to the open position;

a first protrusion that protrudes from the sheet guide member between the lock lever and the operation lever, toward an exterior cover side; and

a second protrusion that is at a position on the first protrusion closer to a front end of the first protrusion than a portion of the housing where the first protrusion is formed, and protrudes from an operation lever side of the first protrusion toward the operation lever side.

2. The image forming apparatus according to claim 1 , wherein the first protrusion and the operation lever are arranged in such a manner that the first protrusion and the operation lever overlap each other when the first protrusion is seen along the vertical direction.

3. The image forming apparatus according to claim 1 , wherein the portion of the housing where the first protrusion is formed is separated from the second protrusion.

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

a support member that supports the pressure roller rotatably, and swings on one end side of the support member as a swing center; and

a spring that is provided for the support member on another end side of the support member, and applies a force to the support member to allow the pressure roller to press the heating roller,

wherein the operation lever presses the support member against a returning force of the spring to move the pressure roller from the first pressing position to the second pressing position.

5. The image forming apparatus according to claim 4 , wherein the pressure roller is under the heating roller in the vertical direction.

6. The image forming apparatus according to claim 4 , wherein the spring is more compressed when the pressure roller is at the first pressing position than when the pressure roller is at the second pressing position.

7. The image forming apparatus according to claim 1 , wherein the second protrusion and a front end of the operation lever are at overlapping positions when the second protrusion is seen along a direction perpendicular to both the vertical direction and a rotational axis direction of the pressure roller, with the sheet guide member at the close position, and with the pressure roller at the first pressing position.

8. The image forming apparatus according to claim 1 , wherein a front end of the operation lever extends toward an outside of the image forming apparatus in a rotational axis direction of the pressure roller.

9. The image forming apparatus according to claim 8 , wherein the front end of the operation lever protrudes at least 10 mm from the second protrusion.