A device for detecting the presence or absence of a liquid, which is installed on an ink-jet recording apparatus, is configured to determine the presence or absence of ink in the ink flow path by detecting the reflection of light from a light transmission portion by irradiating light thereon. The light...http://www.google.com/patents/US7438369?utm_source=gb-gplus-sharePatent US7438369 - Recording apparatus having a device for detecting the presence or absence of a liquid
