Patent ID: 8779670

Claim:
A lighting device, comprising: a pyroelectric sensor configured to detect a change in infrared radiation; a shutter configured to keep the infrared radiation out of the pyroelectric sensor; a lighting control unit configured to control a lighting load; and a shutter control unit configured, when the lighting load is turned on, to control the shutter per the passage of first time period so that the shutter closes and then opens for a second time period shorter than the first time period, wherein the lighting control unit is configured: (a), when the lighting load is turned off, to turn the lighting load on if the pyroelectric sensor detects a change in infrared radiation; and (b), when the lighting load is turned on, to turn the lighting load off if a repetition count or time of the first time period reaches a specified count or time, respectively, with no change in infrared radiation detected through the pyroelectric sensor within each first time period per the passage of first time period.