Power window switch which incorporates express up/down and window motor speed control features using a force sensitive resistor or capacitor

摘要

A system for enabling a vehicle operator to control the speed or rate of raising and lowering of a powered lift window. The actuator or switch includes a pressure responsive variable impedance device comprising a variable resistance in one embodiment and a variable capacitance in another embodiment. Increasing force directly on the variable impedance device by the user's finger or an actuator decreases the impedance which is sensed by a voltage divider which outputs a voltage which increases with increasing force. This latter voltage is compared with the output of a triangle wave oscillator and the output of the comparator is a pulse width modulated signal with pulse-width proportional to applied force. The pulses are applied to a power device (Mosfet) which modulates the duty cycle (%) of the current to the window lift mechanism drive motor to give variable motor speed.