Controller for resistive heating element
US4523084A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Sep 2, 1981 |
| Grant date | Jun 11, 1985 |
| Priority date | — |
| Expiry date | Sep 2, 2001 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG05D23/2401
- WIPO fieldControl
- WIPO sectorInstruments
Abstract
The controller of the present invention regulates the flow of current through a resistive heating element by computing the predicted resistance R.sub.hot of the heating element at the desired temperature and then adjusting the voltage drop across and current flow through the resistive heating element until the relationship V=IR.sub.hot is satisfied. In an analog embodiment of the present invention, measurement of the voltage drop is obtained from a voltage amplifying circuit connected across the resistive heating element, while a measure of the current flow through the resistive heating element is obtained from a current amplifying circuit connected across a current measuring resistor in series with the resistive heating element. The output of the current amplifying circuit is multiplied by first and second variable gain amplifier circuits to produce a signal output representing the product of the current flow and the predicted resistance at the desired temperature. The signal from the voltage amplifying circuit and the product-representative signal from the two variable gain amplifier circuits are balanced in a control amplifier to produce a control signal having a value which var…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.