Allen-bradley Company, LLC

Detector Electronics Corporation

Kenneth C Cormier

The linearity of a photoresistive device at varying levels of radiant signal is improved by masking the sensitive area of the photoresistive device so that only a portion of the sensitive area is illuminated. The masking prevents exposure of the entire surface area of the cell, which increases the dynamic range, allowing a more linear, small signal sensitivity over wide variations in brightness.

Method and apparatus for linearizing photoresistive optical sensors with

The presence of a flame from a burner is determined by analyzing the signal produced by a radiation sensor aimed at a burner. Specifically, a Fourier transformation is applied to the signal producing amplitude values for a spectrum of component frequencies produced by changes in the power of the flame over time. A logarithmic value is derived for each of the amplitude values. The degree of linearity of the distribution of the component frequency logarithmic amplitude values provides an indication of the flame presence. Several parameters, including integrated linear error, linearity regression correlation and slope difference, provide an indication of the degree of linearity. A plurality of values for each of these parameters are produced during an interval of time. When a given percentage of the parameter values are above their respective thresholds the flame is determined to be present, whereas when another given percentage of the parameter values are below their respective threshold the flame is determined to be extinguished.

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Billerica, MA, United States of America

Kenneth C Cormier