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:
Dec. 30, 1997
Filed:
Jul. 17, 1996
Hiroyuki Horiguchi, Yokohama, JP;
Yoshinobu Nakayama, Kawasaki, JP;
Ricoh Company, Ltd., Tokyo, JP;
Ricoh Elemex Corporation, Nagoya, JP;
Ricoh Seiki Company, Ltd., Tokyo, JP;
Abstract
A thermally-sensitive type flow meter measures a flow rate with a high accuracy by eliminating a noise generated in a source voltage. The flow meter includes a sensor chip comprising a substrate carrying sensing elements. First and second resistors are provided on first and second bridges formed over a depression formed on the substrate. The first bridge is positioned on an upstream side and the second bridge is positioned on a downstream side. The first and second resistors generate a heat by the same voltage source. First and second temperature measuring resistors are provided adjacent to the first and second resistors, respectively, to measure a temperature of the first and second resistors. Third and fourth temperature measuring resistors are provided for measuring the temperature of the fluid. A temperature control unit, including the first, second, third and fourth temperature measuring resistors, controls a temperature of each of the first and second resistors to be constant. A flow rate of the fluid is determined based on a voltage difference between a first voltage applied to the first resistor and a second voltage applied to the second resistor.