Illumination device for small object using RF inductive coupling - has mains powered RF generator placed below surface to excite coil driving lamp in object such as drinking glass

摘要

The energy supply for the lamp is by magnetic induction between the lamp and a radio frequency generator operating in the low frequency range 20-100 kHz. The radio frequency generator is powered from ac mains and its electromagnetic emissions induce an emf in a coil mounted in the base of the lamp whenever the lamp is within the emitted field. The generator rectifies (18,21) and filters (3) the AC mains (AB) and uses a split inductor (16,17) oscillator circuit built around a pentode thermionic valve (5). A small or medium sized object such as a drinking glass has a coil wound in its base which also houses the lamp. When the object is placed on a surface above the generator the object is illuminated.