Optical detector circuit for photometric instrument
US4688017A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | May 20, 1986 |
| Grant date | Aug 18, 1987 |
| Priority date | — |
| Expiry date | May 20, 2006 |
Classification
- Technology area (CPC H)Electricity
- CPC primaryH03M1/52
- WIPO fieldBasic communication processes
- WIPO sectorElectrical engineering
Abstract
An optical detector circuit for a photometric instrument for providing a high precision, low cost A/D conversion of a detected optical signal. A sampled signal is integrated in a sample signal integrator while a reference signal integrator is integrated in a reference signal integrator. Using dual slope techniques, the integrated reference signal is provided as an input signal to the sample signal integrator during a de-integration cycle to provide a ratio of the detected signal to the reference signal, useful in nephelometers. An inverted blanking signal may also be integrated in the sample integrator prior to an integration of the sample signal to improve the accuracy of the dual slope integration. The period of integration is selected as a multiple of the primary sources of interfering noise such as power line and flourescent light frequencies.
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.