Wafer level vacuum packaging creates first non-contact MEMS thermal sensor for human presence sensors
MEMS non-contact thermal sensors measure temperature by converting infrared energy radiated from target objects into heat with MEMS thermopiles and then measuring the thermoelectromotive force resulting from temperature differences that occur across the contact points of two different types of metal. However, up till now it has not been possible to create large temperature differences across the metal contact points because much of the heat generated by the thermopiles dissipates into the surrounding air, meaning that the resulting thermoelectromotive force is reduced thereby limiting sensitivity. Omron has solved this heat dissipation problem by vacuum sealing the thermopiles inside the chip – the first time this has been achieved. The reduction in heat dissipation leads to a greater temperature difference across the metal contacts thereby increasing sensitivity.
In recent years the demand for human presence sensors has been growing in tandem with the demand for energy-efficient "smart home" and "smart office" environments in which lighting and heating is automatically controlled according to where people are positioned. As conventional pyroelectric motion sensor are only able to detect people when they are in motion, they are not as suitable for detecting the number of people in a certain space or their relative positions as Omron’s new thermal sensor which has a 90 degree field of view and 4 frame per second detection to detect people moving at 1m/s.
Omron will now also work on commercializing stand-alone human presence sensor modules by combining non-contact thermal sensors with algorithms that can accurately distinguish the number of people and their positions within a detected space. Shipping of test samples will start in October 2013.
www.omron.com
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