Safety device for a movable barrier system

A safety device for a movable barrier system comprising a barrier movable between an open position and a closed position along a guide track, the safety device comprising:

• a position sensor mountable, in use, to or adjacent to the guide track;
• a target mountable, in use, to the barrier, such that movement of the barrier causes relative movement between the position sensor and the target;
• a controller, in use, in communication with the position sensor;
• wherein the position sensor is configured to detect movement of the target relative to the position sensor and provide an output signal to the controller,
• wherein the position sensor comprises a linear array of sensors arranged, in use, along a length of the guide track in a direction of movement of the barrier, each of the sensors being configured to output a sensor signal when the target is within a detection range of the respective sensor, such that the output signal is or comprises a sequence of signal pulses;
• wherein the array of sensors are part of a sensor circuit of the position sensor, the sensor circuit further comprising a control element configured to control current supplied to a group of two or more sensors in the array such that, the current supplied to each sensor in the group is repeatedly modulated between an operating current for an ON period of time and zero current for an OFF period of time, and wherein the ON period of time for each respective sensor in the group is shifted in time such that only one sensor in the group is ON at any given time;
• and
• wherein the controller is configured, in use, to:
• receive the output signal from the position sensor;
• determine one or more signal characteristics from the output signal;
• and
• compare the one or more determined signal characteristics with one or more predetermined signal characteristics to determine if the relative movement between the target and the position sensor is within a predefined range.