Lift system speed control - has photoresistor cell which varies current intensity in response to amount of incident light allowed through by operator-controlled shield

摘要

The speed regulator comprises a photoresist cell(26) which varies the current intensity for the system under control and comprises a layer (30) on an isolating base(27) between two electrodes(28, 29). The layer resistance is varied by a screen(32, 33) which is moved between a light source(31) and the resistive layer to vary the position of an orifice(40, 41). A translucid screen(42) with an opaque deposit prevents saturation of the resistive layers. This screen is coupled(14) to all-or-nothing switches to provide a modulating effect.