Patent ID: 8680694

Claim:
A vibration energy harvester for converting mechanical vibrational energy into electrical energy, the vibration energy harvester comprising: a device for generating electrical energy when subjected to mechanical vibration; and a current control circuit electrically connected to the device for providing a substantially constant output current at an electrical output of the vibration energy harvester, the current control circuit having: a first controllable variable resistance connected to the electrical output of the vibration energy harvester, the current control circuit adapted to control the first controllable variable resistance to maintain a predetermined input voltage and adapted to control a device output voltage at the electrical output of the vibration energy harvester so that the output voltage does not exceed a predetermined threshold voltage, a second controllable variable resistance connected to the electrical output of the vibration energy harvester, the second controllable variable resistance comprising a shunt resistance between a power line and a ground line of the device, and a reference voltage generator for generating a preset reference voltage, and an error amplifier for comparing the input voltage from the device with the reference voltage for generating a first control signal for selectively adjusting the first-controllable variable resistance when the input voltage is different from the reference voltage.