| 摘要 |
PROBLEM TO BE SOLVED: To provide a suspended particle detecting device capable of being miniaturized and thinned, and reducing the stray light caused by the irradiation light from a light emitting element. SOLUTION: This suspended particle detecting device comprises the light emitting element 2 for applying the light to a detection space, a light receiving element 3 for receiving the scattered light by the suspended particle, in the light emitted from the light emitting element, a circuit board 4 for mounting at least a circuit part for driving the light emitting element 2, with the light emitting element 2, and a case 5 provided with the detection space to which the suspended particles is introduced, inside thereof, and optical axes A2, A3 of each of the light emitting element 2 and the light receiving element 3 are arranged at predetermined angles in the detection space as parallel optical axes in parallel to the circuit board 4. The light emitting element 2 is mounted on the circuit board 4 in a state that the optical axis A1 is approximately vertical to the circuit board 4, an aperture 6 is mounted on an upper part of the light emitting element 2 for intercepting a peripheral edge of the irradiation area, and a prism member 7 is mounted to bend the vertical optical axis A2' to be the parallel optical axis.
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