Importance

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Abstract

A vessel for storing fluid and a device for detecting remaining fluid in the vessel is provided. The vessel is maintained at a pressure less than atmospheric, but in a range not sufficient to overcome the surface tension of fluid remaining in a nozzle. This prevents fluid from escaping out from the nozzle when the tank is maintained at a height equal to or higher than the nozzle orifice. The tank may be formed from an elastic material or may include a biasing member for maintaining the negative pressure. An ink jet printer including an ink tank maintained at a pressure less than atmospheric main include a device for detecting ink remaining in the tank. Opposing walls of the tank may be conductive and upon consumption of ink therein collapse causing a circuit to short for indicating lack of ink in the tank. Alternatively, the device for detecting the remaining ink may include a conductive member mounted on the periphery of the tank which is displaced as the tank collapses. Further, a photosensitive device may be disposed above and below an ink tank formed of a transparent material which indicates lack of ink remaining when light penetrates the ink tank. In another embodiment a second ink chamber is formed inside the ink tank for providing a signal by means of a different color ink which is printed upon consumption of the ink from the main ink tank.

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First Claim