A system for detecting proper usage of a seatbelt in a vehicle by an operator of the vehicle is provided. The substrate can include a thin film transistor arranged on one surface of the substrate and the deformation preventing layer, arranged on the another surface of the substrate, and including at least one layer. The bottom cushioning piece includes a cushioning bottom board, two cushioning side boards mounted to the cushioning bottom board and arranged at two ends of the cushioning bottom board, and three positioning boards mounted to the cushioning bottom board and arranged, in a spaced manner, between the two cushioning side boards. The active substance is released upon action of the stomach-intestinal juices.