Patent ID: 8157365

Claim:
An ink circulation system for use in a drop on demand ink jet printing apparatus, the ink circulation system comprising: an ink jet print head; a supply subtank arranged to contain a supply of ink to be ejected by the ink jet print head; a return subtank arranged to contain a return of the ink not ejected by the ink jet print head; a print circulation path arranged to couple the supply subtank with the ink jet print head and the return subtank and arranged to provide a print flow of the ink from the supply subtank to the ink jet print head, then to the return subtank, and then back to the supply subtank; a through-flow degassing unit arranged to degas the ink; and a degas circulation path arranged to couple the supply subtank with the through-flow degassing unit and arranged to provide a degassed flow of the ink from the supply subtank to the through-flow degassing unit and then back to the supply subtank.