AN OCCUPANCY SENSOR

摘要

An occupancy sensor (S) includes: - a sensing probe (101) to detect occupancy (P) of a space monitored by the sensor (S) and produce a corresponding sensing signal, - a comparator (104) including a voltage divider (RA, RB, R1, R2, R3, RC) defining a comparison value (A, B) against which the sensing signal is compared to detect occupancy, and - a voltage sensing means (105) to sense a feed voltage (Vbattery) applied to the sensor (S), wherein changes in the feed voltage (Vbattery) to the sensor induce a change in the comparison value (A, B). The voltage divider (RA, RB, R1, R2, R3, RC) includes one or more resistors (R1, R2, R3) selectively switcheable (Q1, Q2, Q3) to counter changes induced in said comparison value (A, B) by changes in the feed voltage (Vbattery) ° For instance, the voltage divider (RA, RB, R1, R2, R3, RC) may define a comparison window for the sensing signal with a width between an upper threshold (A) and a lower threshold (B), and may include one or more resistors (R1, R2, R3) selectively switcheable (Q1, Q2, Q3) to counter changes in the width of the comparison window (A, B) induced by changes in the feed voltage ( Vbattery) °