Abstract: An inkjet printer having an array of nozzles from which ink drops are emitted further includes a mechanism adapted to detect fluid levels in an ink supply tank to the inkjet printer while the printer is in idle mode, and shut down the printer when ink usage exceeds a predetermined volume.

Abstract: The present invention relates to ink output in ink jet printing systems. A refractometer is used to control the concentration of inks used in continuous ink jet printers. A concentration detector measures the total amount of light reflected from a surface. Changes in the ink cause a definite change in sensor output. As the refractive index is changed, shifting the critical angle for internal reflection, more or less light is reflected to the sensor. The index of refraction can be determined from the sensor once corrections are made to account for temperature dependencies of the sensor and light source and baseline measurement of reflected light amplitude. These dependencies are carried out in the refractometer.

Abstract: The method for shutting down an ink jet printhead and an ink jet printing station, wherein the method includes maintaining a constant positive pressure at the drop generator by closing the cross flush valve or ensuring that the cross flush valve is closed, thereby closing off the fluid return line to create a constant positive pressure through the drop generator and the orifice into the fluid line. The shutdown continues by stopping the flow of fluid from the fluid supply line and circulating cleaning fluid through at least one filter, into the drop generator, out through the orifice structure, into the fluid line, and into a reservoir. The shutdown ends by flowing pressurized air, which is preferably clean of particulates, through the filter, drop generator, orifice structure, and fluid line to displace substantially all the cleaning fluid from the filter, drop generator, and orifice structure.