Abstract:

Car door keypads have traditionally comprised of micro-switches that directly carry the motor currents used to operate windows and mirrors. Although this type of circuit has to handle currents of over an amp, the requirement to drive multiple motors in both directions from more than one switch makes them quite complex (e.g. the control of the front passenger window from both front doors). This included versatility will restrict the possibility of causing a short if two keys are operated at the same time in different directions. In the case of electrically operated folding mirrors, a single multiple contact switch unit controls six motors in both directions. This complexity combined with the high currents resultes in a heavy, expensive, and difficult to install wiring harness, especially in the driver's door. The amount of copper at the hinge where the harness interfaces with the main body wiring can also pose a difficult design compromise between durability and ease of use.