The patent badge is an abbreviated version of the USPTO patent document. The patent badge does contain a link to the full patent document.
The patent badge is an abbreviated version of the USPTO patent document. The patent badge covers the following: Patent number, Date patent was issued, Date patent was filed, Title of the patent, Applicant, Inventor, Assignee, Attorney firm, Primary examiner, Assistant examiner, CPCs, and Abstract. The patent badge does contain a link to the full patent document (in Adobe Acrobat format, aka pdf). To download or print any patent click here.
Patent No.:
Date of Patent:
Jan. 31, 1995
Filed:
Apr. 26, 1993
Ted E Deur, Hillsboro, OR (US);
Clark W Crawford, Wilsonville, OR (US);
Brian J Wood, Portland, OR (US);
Richard Marantz, Portland, OR (US);
James D Buehler, Troutdale, OR (US);
Tektronix, Inc., Wilsonville, OR (US);
Abstract
A discrete ink level sensing system according to the present invention includes a level sensing probe (130) with at least first and second level sensing pads (178, 180) that is placed in an ink reservoir (28). The level sensing system uses electrical conductivity of the ink to detect when the upper surface level of the ink is lower than the lowest points of the level sensing pads. The upper and lower level sensing pads are electrically connected by a sense resistor (182). A voltage sensor (174) detects across the sense resistor a voltage that depends on the ink conductivity and the position of an upper surface level of the ink with respect to the lowest points of the first and second level pads. The value of the voltage is sent to a CPU (154) that signals a user that a predetermined amount of ink should be added to the reservoir.