Vehicle horn and control function switch with compensation and method of operation

摘要

A vehicle horn and control function switch that has compensation for wide temperature variations and preloads from surrounding material due to manufacturing processes and material aging. Due to the very thin physical thickness of the force sensor, the switch is useful when the sensors are mounted on the hub of a vehicle steering wheel adjacent to an airbag assembly. The switch comprises a force sensor and a temperature sensor mounted in the hub of a steering wheel. The force sensor is connected to the input of an operational amplifier that has an offsetting input network and an amplifying feedback network that are controlled from a programmable microcontroller. The output of the operational amplifier and the temperature sensor are connected to the programmable microcontroller. In operation, the programmable microcontroller reads a temperature signal from the temperature sensor and a quiescent force signal from the output of the operational amplifier and compensates the offsetting and amplifying of the operational amplifier for temperature variations and effects of preload conditions, respectively. When an actuating force signal applied to the force sensor, the force signal at an input to the programmable microcontroller exceeds a predetermined threshold and the programmable microcontroller activates an output, causing a horn or other control function to actuate.