Optical liquid level sensor using a polytetrafluoroethylene perfluoroalkoxy material
November 15, 2009. Estimated Expiration Date is calculated based on simple USPTO term provisions. It does not account for terminal disclaimers, term adjustments, failure to pay maintenance fees, or other factors which might affect the term of a patent.Patent ReferencesOptical instrument Level monitoring methods and apparatus particularly for high-resistivity liquids Electro-optical liquid level sensor Double optical probe device for the determination of the refractive index of a liquid reduced to a predetermined reference temperature Liquid-level detection Light-transmissible foreign object sensor Particle detector for flowing liquids with the ability to distinguish bubbles via photodiodes disposed 180° apart Sensor and method for detecting the presence of air bubbles in liquid Fluid level sensing method and apparatus Fiber-optic detector for oils and solvents Patent #: 4882499 InventorAssigneeApplicationNo. 455447 filed on 11/15/1989US Classes:250/577, Volume or level73/293, With illumination250/903, With prism contacting liquid356/136Internally reflecting prismExaminersPrimary: Nelms, David C.Assistant: Allen, Stephone B. Attorney, Agent or FirmForeign Patent References
International ClassG01N 015/06AbstractAn optical liquid level sensor has an optically-transmissive body (28) provided with a frusto-conical tip end portion (32). When the tip end portion is exposed to air, the angle of incidence (θi) of light at each of three points of reflection (b,c,d) is less than the critical angle (θc) such that substantially all light transmitted through the body will be reflected internally. However, when the tip end portion is exposed to a liquid, light is refracted, and the intensity of the reflected light is reduced. The intensity of the reflected light is used to indicate whether the sensor is above or below the surface of the liquid. | |
