Constant current-pulse led drive circuit
US4001667A · kind A · utility
19Cited by
4References
2Claims
0Family size
Assignee
Inventor
Key dates
| Filing date | May 2, 1975 |
| Grant date | Jan 4, 1977 |
| Priority date | — |
| Expiry date | May 2, 1995 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG01N21/255
- WIPO fieldMeasurement
- WIPO sectorInstruments
Abstract
A circuit for use with an oximeter system which provides constant current pulses to light-emitting diodes in a sequential and cyclical manner. The circuit maintains magnitudes of pulses in the pulse train equal to certain other pulses in the pulse train over extremes of temperature variation, voltage variation, and time duration. Each diode is energized by a series of pulses having the same magnitude, although pulse magnitudes will vary from diode to diode. Therefore, light output from one light-emitting diode remains proportional to light output from the others.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.