there's a panasonic blu-ray player that has a capacitive sensor that works up to 3 or 4 inches away, or maybe even more. it appears to connect to the player main board through a USB or SPI port. i've never tried to see what the detection range on it is, as i always check the player's menu to make sure the feature is turned off. when they first came out our shop started getting them in for repair with the complaint "disk drawer opens and closes at random" because somebody had the feature enabled, and stacked another piece of equipment on top of the unit, or had something else near the top of the unit that would set off the sensor.