Obstacle detection system for automatically controlled elevator doors

Abstract

Capacitively sensitive antennas are located at the closing edges of automatically controlled elevator doors to generate error signals by way of differential amplifiers if capacitively influenced by an obstacle or a disturbance. A door travel detector and pulse generator divide the entire door region into incremental travel distances of, for instance, one centimeter steps to control a compensator which consists of a threshold value detector, a forward/reverse counter and a digital/analog converter. Every error signal is subjected to compensation at every door movement for the associated travel distance increment and floor and the determined compensation value is stored for use in the next compensation cycle. The compensation maximally attainable pertravel distance increment is chosen in such a manner, that it is not significant for rapidly variable obstacle error signals caused by persons or objects, while slowly variable disturbance error signals, due to, for instance, mechanical tolerances or temperature variations, are reduced to a minimal residual amplitude. For this reason, obstacle signals will prevent, stop or reverse a door closing movement by way of an error signal evaluating circuit and door circuits, while disturbance signals remain ineffective with regard to door control.

Dependencies are inferred from the claim text.