Patent ID: 8025356

Claim:
An image forming apparatus comprising: a liquid ejection head unit including a liquid ejection head that has a nozzle surface provided with plural nozzles through which a liquid droplet is ejected, and a liquid droplet detection unit that detects the liquid droplet ejected from the liquid ejection head; and a maintenance and recovery mechanism including a capping unit, wherein the liquid droplet detection unit has a light-emitting unit that emits a light beam, a light-receiving unit that receives the light beam emitted from the light-emitting unit, and a light path forming unit that causes the light beam emitted from the light-emitting unit to pass through along the nozzle surface from outside of an area, of the nozzle surface, capped by the capping unit and that causes the light beam to be incident on the light-receiving unit provided outside of the area, and wherein the light beam from the light-emitting unit scans a light path on the plural nozzles along a longitudinal direction of the liquid ejection head unit, the light-emitting unit and the light-receiving unit are arranged at respective different ends in the longitudinal direction of the liquid ejection head unit, and grooves are provided at said respective different ends in the longitudinal direction of the liquid ejection head unit, and each of the grooves is arranged in an area that is outside the capped area of the liquid ejection head unit and outside the nozzle surface of the liquid ejection head, that is between (i) an outer side of the capped area and (ii) any one of the light-emitting unit and the light-receiving unit, and that is between plural parts of the light path forming unit.