| 摘要 |
A scattered light type smoke detector wherein a light source and a photo-cell are so disposed that light from the light source does not directly enter the photo-cell and the photo-cell is adapted to receive light from the light source scattered by intervening smoke to detect the presence of smoke. The photo-cell is accommodated in a cylindrical recess formed in a smoke detecting holder. The inner face of the cylindrical recess and the surface of the smoke detecting holder extending along the optical axis of the photo-cell has light traps formed in sawteeth configuration in section for reflecting light other than the scattered light to be detected into a direction not towards the photo-cell. |
