| 摘要 |
PURPOSE:To accurately detect the seismic intensity of an earthquake, by such a simple apparatus constituted so that a container storing a liquid is irradiated with a light source and the reflected light from the liquid surface is received to be converted to an electric signal which is, in turn, compared with a threshold value. CONSTITUTION:The bottom of a container 31 is sealed with a liquid 32 and a light emitting element 34 is driven by a power source 33 to irradiate the surface of the liquid 32. The change in the reflected light by the shaking of the surface of the liquid generated by an earthquake is photoelectrically converted by a light receiving element 35 to output a signal 20a. The signal 20a is inputted to a plurality of comparators while amplified by the amplifying circuit not shown in the drawing and compared with the different threshold values of the comparators and seismic intensity is judged on the basis of the output from the comparator having a corresponding number. As the liquid to be used, oil, which is flat at 0-5Hz but shows a falling characteristic at 5Hz or more and has a frequency characteristic coincided with that of a seismic wave, is used. By this method, up- and-down movement or horizontal movement can be detected by a simple apparatus. |
