Process for manufacturing liquid level control structure
US5277754A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Nov 19, 1992 |
| Grant date | Jan 11, 1994 |
| Priority date | — |
| Expiry date | Nov 19, 2012 |
Classification
- Technology area (CPC B)Performing Operations; Transporting
- CPC primaryB41J2002/14387
- WIPO fieldTextile and paper machines
- WIPO sectorMechanical engineering
Abstract
A liquid level control structure and a method for its production. The controller is comprised of a plate having substantially flat top and bottom surfaces and an hourglass-shaped aperture containing a marking fluid. Protruding a known amount and at a known angle from opposite sides of the aperture waist are knife-edged lips that interact with the fluid's surface tension to control the location of an unbounded surface of the fluid. The method for producing the liquid level control structure uses semiconductor fabrication techniques. The aperture is formed in a semiconductor wafer using several etching steps, some of which act along the crystalline planes of the wafer. The lips are formed from etch stop layers deposited between etching steps, while the knife-edges are formed on the ends of the lips during an etching step. Beneficially, the location of the knife-edges relative to one surface of the wafer is independent of small variations in the thickness of the water.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.