Clay Morton, from Virginia, USA, received his master's degree from Virginia Tech. His research topic is a kind of lamp made of light-emitting diodes, named "Gravia". In fact, it is a cylinder made of acrylic material, and its height is slightly more than 4 feet (about 1.2 1 m). The luminous principle of this lamp is that the heavy objects on the lamp drive the rotor to rotate when it falls slowly, and the electric energy generated by the rotation will electrify the lamp and make it shine.
The luminous flux of this lamp is 600 to 800 lumens (equivalent to the brightness of 12 watt fluorescent lamp) for 4 hours. To turn on the lamp, the operator only needs to move the weight on the lamp from the bottom to the top and put it in the groove at the top. It only takes a few seconds for the weight to slowly descend, and the LED light will be on.
Clay Morton said that operating this light is certainly more troublesome than pressing the switch, but it is still acceptable and more interesting, just like winding a classical clock or leisurely making a delicious cup of coffee. Morton estimated that the service life of Gravia lamps can reach more than 200 years. This lamp named "Gravia" has been applied for and patented.