Sensor-driven lighting units monitor a characteristic of the environment with a sensor and utilize the sensor data to control the light source of the lighting unit. The most common example of sensor-driven lighting units are systems that monitor light levels using integrated photocells that measure ambient light levels. For example, night lights use ambient light to turn on when ambient light levels decrease and to turn off when ambient light levels increase. Similarly, smart street lighting uses detected ambient light to determine when to turn the light source on and off. Most often, the light level is monitored by a photocell directed towards the sky to observe the ambient light conditions. In which direction the photocell is directed, or which surface or area is utilized for light level monitoring, is driven primarily by product design. In most devices there is no relationship between the surface or area from which the ambient light level is monitored and the target surface to be illuminated.
For a wide variety of reasons, it is important that sensor-driven lighting units and systems have the most accurate estimate possible for the contribution of ambient light for advanced light control. State-of-the-art lighting systems and luminaires, for example, have embedded sensors with lux-metering functionality to estimate the overall ambient light in order to enable their integrated illumination and/or sensing systems. These sensors however, do not consider the source or various contributors of the ambient light. For example, outdoor lighting systems such as streetlights and other units do not separate the contribution of daylight from neighboring light sources or other light sources, and certainly do not do so while taking the overall ambient light into consideration.
Accordingly, there is a continued need in the art for methods and systems that measure and characterize the various contributors of ambient light in a sensor-driven lighting unit, in order to provide advanced light control.