Process control system
US5674194A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Oct 25, 1995 |
| Grant date | Oct 7, 1997 |
| Priority date | — |
| Expiry date | Oct 25, 2015 |
Classification
- Technology area (CPC A)Human Necessities
- CPC primaryA61M2210/0612
- WIPO fieldMedical technology
- WIPO sectorInstruments
Abstract
A process control system according to the present invention uses analog control circuitry in which a differential amplifier stage is incorporated into the feedback path rather that the feedforward path to enable the control of highly non-linear processes that may also exhibit high levels of hysteresis. Such processes often have superior performance characteristics that conventional control circuitry cannot exploit. The present invention additionally incorporates an automatic control circuit which varies the gain of various stages the control circuitry when the output of the process is within a predetermined range. An embodiment of the present invention is used to control a nonlinear proportional valve with severe hysteresis. The valve regulates the pressure within pressure-driven ophthalmic surgical instruments, which must be controlled extremely precisely to enable successful eye surgery.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.