| 摘要 |
PURPOSE:To detect stress change over a wide range of a part safely and sharply, by a method wherein plural elongated piezo-electric operative parts formed from electrodes are flatly arranged on both surfaces of a high molecular piezo- electric film at predetermined intervals and the variation in potential between both electrodes is detected. CONSTITUTION:Plural elongated unit piezo-electric operative parts 14a, 14b,... are arranged flatly on both surfaces of a high molecular piezo-electric film 11 at predetermined intervals from earth electrodes 12a, 12b,... and output electrodes 13a, 13b,... to constitute a staress detector 15. A conductors 16, 17 are formed in a state crossing each earth electrodes and output electrodes to be connected to an alarm circuit 18. This sheet shaped stress detector 15 is held between a substrate sheet 21 and a surface coated sheet 22. If an invader rides this sheet, a piezo-electric signal is obtained to operate the alarm apparatus. Because the sum of the areas of the piezo-electric operative parts can be made small as compared to the all area, enormous charge is not accumulated. |
