Fluorescent Lamp with Integral Proximity Sensor


Integral proximity sensors coupled with fluorescent lamps have applications in energy conservation, lighting, and security.

Problem Addressed

Current occupancy detection systems primarily use motion sensors. The primary disadvantages of motion sensors are their occupancy measurements and their installation. Motion sensors' occupancy measurements are based on movement rather than on presence and the sensors require custom installation in addition to the installation of luminaires. However, fluorescent lamps with integral proximity sensors provide detection of motion and presence in ranges of up to 11ft or more. In addition, proximity sensors reduce installation and hardware costs because they can be retrofitted as a drop-in replacement and require only replacing the old lamp ballast with a lamp sensor ballast and adding two wires.


This invention proposes a proximity sensor that can be integrated with a fluorescent lamp ballast. The sensor measures disturbances in the electric field  between two electrodes mounted in the lamp cover. The sensor's output voltage deviates from zero as the occupant approaches the center of the lamp, enabling fine-grain occupancy measurements in spaces without requiring a motion or thermal signature. There are two detection schemes: one uses dimmed sensing to dim the lamp ballasts, the other uses sparse sensing to take advantage of the wide angle of detection of the sensors, requiring fewer lamp sensors. The electronics do not contribute significantly to the noise floor of the lamp sensor. The output sensitivity is affected by electrode spacing, depth and bulb power.


  • Reduces energy, installation, and hardware costs
  • Reduces energy consumption
  • Presence and motion based occupancy detection