| 摘要 |
<p>A photoelectric smoke detecting apparatus capable of generating analogue data indicating accurately a smoke density regardless of presence or absence of contamination. A control unit for outputting the analogue data corresponding to the smoke density on the basis of a detection value derived from the output of a smoke sensor is comprised of a smoke density arithmetic module having a characteristic function for converting the detection value to a smoke density value, a zero-density detection value storage device for storing a detection value at a time point when the smoke density is zero as a zero-density detection value, a change rate arithmetic module designed for determining arithmetically a rate of change of the zero-density detection value, and a compensation arithmetic module designed for compensating conversion characteristic for converting the detection value to the smoke density value in dependence on the rate of change, wherein the compensation arithmetic module is so designed as to cause the smoke density arithmetic module to generate the smoke density value in such a manner that change of output characteristic of the detection value for the smoke density, which change bears dependency on the rate of change, can be canceled out. A self- or auto-compensation function against aged deterioration of the detection value due to contamination is realized. <IMAGE></p> |
