Patent ID: 6583404
Filing Date: 2003-06-24
Classification: G08B

Abstract:
A photoelectric smoke detection apparatus comprising:a smoke sensor comprising a labyrinth inner wall, a chamber enclosed by said labyrinth inner wall, a light emitting element disposed within said labyrinth inner wall and operable to emit light and a light receiving element disposed within said labyrinth inner wall so as to receive at least a portion of the light and operable to output a detection signal indicative of a detection value corresponding to a smoke density prevailing within said chamber enclosed by said labyrinth inner wall; and a controller operable to output a smoke density value, as analog data, corresponding to the smoke density prevailing within said chamber, said controller comprising a smoke density arithmetic module operable to convert the detection value to a first smoke density value via a characteristic function located therein, a zero-density detection value storage unit operable to store a zero-density detection value that corresponds to zero smoke density prevailing within said chamber, a change ratio arithmetic module operable to arithmetically determine a ratio of change representing a change of the zero-density detection value and a compensation arithmetic module operable to provide a compensating value based on the ratio of change to said smoke density arithmetic module, wherein said smoke density arithmetic module is further operable to change the characteristic function, based on the compensating value, such that said smoke density arithmetic module is operable to convert the detection value into the smoke density value.