Patent ID: 7445168

Claim:
A drip irrigation emitter having a housing containing an inlet opening for receiving water from a supply tube and an outlet opening for emitting water at a pressureless drip rate; a labyrinth between the inlet opening and the outlet opening for receiving water from the supply tube through the inlet opening and reducing its pressure for emitting the water at said drip rate from the outlet opening of the housing; a flexible pressure-compensating diaphragm inside the housing, the diaphragm disposed in the housing to flex elastically under pressure changes of water entering in the inlet opening from the supply tube to control the flow of water from the outlet opening; and a raised structured surface positioned between the inlet opening and the diaphragm, the raised structured surface comprising a raised rim surrounding the inlet opening and positioned for contact with the diaphragm when water pressure in the supply tube is shut off, the raised rim having a small slit or hole therein to provide a bypass path through the structured surface to act as a choke against air flow, allowing air to be drawn back slowly through the emitter thereby reducing blockage at the outlet opening caused by soil ingestion.