Image forming apparatus

An image forming apparatus comprising:

• a transfer unit configured to transfer a toner image onto a sheet;
• a fusing unit configured to fuse the toner image on the sheet;
• an external member forming a first opening portion to discharge the sheet passed through the fusing unit and a second opening portion to expose part of the sheet outward in reversing a conveying direction of the sheet, wherein, in a case where the toner image is fused on the sheet, the sheet includes an image fused on a first face;
• a discharging roller configured to discharge the sheet from the first opening portion;
• a first guide member provided on a downstream side with respect to the fusing unit and on an upstream side with respect to the first opening portion in the conveying direction of the sheet, wherein the first guide member includes a first through-hole at a conveying surface and is configured to guide the sheet to the first opening portion;
• a second guide member provided downstream of the fusing unit and upstream of the second opening portion in the conveying direction of the sheet, wherein the second guide member includes a second through-hole at a conveying surface and is configured to guide the sheet to the second opening portion;
• a switching member provided at a branch portion between the first guide member and the second guide member, wherein the switching member is configured to move such that the sheet is conveyed to the first guide member or the second guide member;
• a first Helmholtz resonator having a first cavity portion and a first communicating portion through which the first cavity portion is configured to be in communication with an outside area that is exterior to the first Helmholtz resonator;
• and
• a second Helmholtz resonator having a second cavity portion and a second communicating portion through which the second cavity portion is configured to be in communication with an outside area that is exterior to the second Helmholtz resonator,
• wherein the first Helmholtz resonator and a conveying path of the sheet guided by the first guide member are connected through the first through-hole,
• wherein the second Helmholtz resonator and a conveying path of the sheet guided by the second guide member are connected through the second through-hole,
• wherein the first Helmholtz resonator and the second Helmholtz resonator are disposed on the downstream side with respect to the fusing unit and on an upstream side with respect to the external member in the conveying direction of the sheet, and
• wherein the first Helmholtz resonator is disposed such that the first communicating portion faces the first guide member, and the second Helmholtz resonator is disposed such that the second communicating portion faces the second guide member.