| 摘要 |
A tire pressure indicator comprises a set of pressure gauges respectively installed in the tires of a vehicle, and receiver circuit means installed in the vehicle adjacent to the tires. Each pressure gauge includes a power supplying device, a pressure-sensing unit, and a transmitter circuit. The power-supplying device has a self-generating voltage unit formed by a piezoelectric element, a spring element, and a weight. The spring element is vibrated when the tires of the vehicle are in motion, thereby causing the piezoelectric element to generate power supply. The pressure-sensing unit includes a capacitor means formed by a motion member, a conductive member, and a converting circuit. The motion member is made of electrically conductive material and is moved relative to the conductive member subject to the air pressure of the respective tire, so as to change the capacity of the capacitor means, enabling the converting circuit to output a first signal to the transmitter circuit subject to RC oscillation waveform detected. The transmitter transmits a second signal into the air by radio upon receipt of the first signal.
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