Capacitor sensors for measuring stress forces within materials are generally well known. Such sensors comprise metallic plates typically formed of a suitable material such as brass. The metallic plates are spaced apart by an air gap and are retained at a predisposed relationship. The metallic plates deflect responsive to stress force within a material and the air gap between the plates varies accordingly. As the air gap varies, the capacitance between the capacitor plates also varies. A signal is directed into the device from a remote source and the capacitance between the metallic sheets is detected by a remote antenna and reader to measure the level of stress force within the material.
While such capacitor sensors work well and have been well accepted in the industry, several shortcomings in their manufacture and use remain. Existing capacitor stress sensors are relatively complicated to manufacture and assemble, resulting in a greater than optimal cost to the end user. In addition, existing sensors are prone to misalignment resulting in measurement inaccuracy. Still further, existing sensors tend to be susceptible to horizontal and vertical slippage between the capacitor plates when vulcanized into rubber compounds such as a tire. Such slippage distorts the configuration of the sensor and may dislocate the sensor from its optimal, intended location within the material, resulting in a potential for measurement error.
USPTO Backgrounds
USPTO Backgrounds