Geometrical instruments – Indicator of direction of force traversing natural media – Level or plumb – terrestrial gravitation responsive
Reexamination Certificate
2000-11-03
2003-02-11
Gutierrez, Diego (Department: 2859)
Geometrical instruments
Indicator of direction of force traversing natural media
Level or plumb, terrestrial gravitation responsive
C033S366110, C033S366180, C033S366220
Reexamination Certificate
active
06516527
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to inclinometers.
There are a number of inclinometers and level detectors disclosed in the prior art. Prior art devices were met with several limitations to obtaining accurate, and repeatable performance over 360 degrees of rotation, thus necessitating elaborate compensation to overcome non-linearity, and environmental variation for each device.
Prior art devices utilizing liquid electrolytes suffer non-linearity due to a fringe effect, limited angle of rotation, and temperature effects. Capacitive inclinometers utilizing liquids and dielectric media between driving and sensing electrodes suffer stray capacitive and non-linear capacitive variation, thus requiring table look up non-linearity compensation unique to each individual sensor. Matching sensors to inclinometer read-out units adds complexity to the manufacturing process and adds complexity for sensor interchangeability. Optical disks with pendulum often limit resolution due to a finite number of optical windows in the wheel and mechanical friction and wear associated with the shaft.
SUMMARY OF THE INVENTION
In accordance with the invention, an inclinometer is provided that includes a sealed enclosure cavity partially filled with a conductive liquid, a driver electrode placed concentrically within the cavity and plural sensing electrodes on a non-conductive structure placed concentrically within the cavity.
Accordingly, it is an object of the present invention to provide an improved inclinometer able to achieve a high resolution, precise, continuous 360-degree inclination angle measurement, overcoming the necessity for linearity correction, look-up table and correction for each individual inclinometer.
It is a further object of the present invention to provide an improved inclinometer that overcomes liquid electrolytic variance due to liquid fill level variation, liquid meniscus effect, concentration, temperature effects, and aging effects changing the conductivity of the liquid.
It is yet another object of the present invention to provide an improved inclinometer that allows true sensor interchangeability at the manufacturing stage, field, or customer options.
Yet a further objective of the invention is to achieve improved inclinometer sensors able to be miniaturized by scaling down without suffering non-linearity, environmental changes, and calibration or complex correction circuitry requirements.
Yet another objective of the invention is to achieve improved inclinometers with multiplexable multi-axis 3-D gravity sensing without requiring complex circuitry associated with each axis.
The subject matter of the present invention is particularly pointed out and distinctly claimed in the concluding portion of this specification. However, both the organization and method of operation, together with further advantages and objects thereof, may best be understood by reference to the following description taken in connection with accompanying drawings wherein like reference characters refer to like elements.
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Dellett & Walters
Gutierrez Diego
Reis Travis
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