| 摘要 |
An optical detector employs either a plurality of transmitters, with a single light sensor, a plurality of light sensors with a single transmitter, or both a plurality of transmitters and sensors with the components being arranged at different angles to each other to provide a broad spectrum (particle size) of detection. In one system employing two transmitters and one receiver the line of sight of field of view of the receiver is disposed, for example, at 90 DEG and 150 DEG , respectively, to the lines of sight of the transmitter. Efficiency can be improved by arranging the light emitting diodes in series and operating them either concurrently or alternatively. In one embodiment a pair of receivers are used in association with a pair of transmitters while in still another embodiment a pair of transmitters are associated with a single receiver having a relatively large sensitivity area preferably of curved or parabolic shape. A combination optical and ionization detector is also provided employing a comparator wherein the output of the ionization detector is used to alter the threshold level of the comparator with the main input of the comparator being coupled from the optical detector. Alternatively, a combination detector of this type can be used wherein the optical detector is used to change the threshold level and the main input to the comparator is from the output of the ionization detector. In another arrangement the gain of an optical detector may be altered by the output from an ionization detector and vice versa. A summing circuit may also be employed wherein the outputs of the optical and ionization detectors are additive. |
