Temperature-compensated apparatus for monitoring current having controlled sensitivity to supply voltage
US5095274A · kind A · utility
Assignee
Inventor
Key dates
| Filing date | Sep 22, 1989 |
| Grant date | Mar 10, 1992 |
| Priority date | — |
| Expiry date | Sep 22, 2009 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01R19/32
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
An apparatus for monitoring current through a lamp circuit that uses a series resistance shunt in the circuit with one end being connected to a current source and the second end being connected to the lamp. The circuitry includes a comparator that is connected across the shunt and has a threshold switching voltage such that a voltage across the shunt that is larger than the threshold voltage will switch the comparator on (as in the case where the lamp is not functioning) and a voltage across the shunt that is smaller than the threshold voltage (as in the case where the lamp is in the circuit and functioning) will switch the comparator off. In a preferred embodiment, the shunt is actually a portion of the printed circuit board trace. In order to compensate for changes in resistance in the shunt that occur as the temperature of the printed circuit board trace changes, temperature compensation circuitry is included to maintain the threshold switching voltage in a fixed relationship with the temperature of the shunt. The apparatus incorporates additional circuitry connected to the comparator in order to decrease the sensitivity of the comparator to changes in the circuit supply voltage…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.