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:
Jul. 17, 2001
Filed:
Feb. 19, 1999
Gerald C. Pham-Van-Diep, Hopkinton, MA (US);
Magdalena Andres, Narragansett, RI (US);
MPM Corporation, Franklin, MA (US);
Abstract
An apparatus for dispensing a fluid includes a dispensing chamber coupled to a dispensing orifice and a fluid reservoir. The dispensing chamber is coupled to a transducer which is adapted to change the volume of the dispensing chamber in response to a signal applied to the transducer. The signal is characterized by 1) an initial rise time RT,during which an increasing amplitude signal is applied to the transducer to gradually expand the dispensing chamber from a first volume at a first amplitude to a second volume at a second amplitude; 2) a fall time FT during which a decreasing amplitude signal is applied to the transducer to contract or compress the dispensing chamber rapidly (relative to the initial rise time RT,) to a third volume at third amplitude; 3) a final rise time RT,during which an increasing amplitude signal is applied to the transducer to gradually expand the dispensing chamber to a fourth volume at a fourth amplitude. Preferably, the first volume is less than the second volume, the second volume is substantially greater than the third volume, the third volume is less than the fourth volume, and the first volume is same as the fourth volume and both are equal to the nominal volume of the dispensing chamber. In addition, the fall time is substantially smaller than both the initial rise time and the final rise time. In the preferred embodiment, the waveform amplitude is negatively offset by its center (or nominal) to peak amplitude.