Provided is an electrostatic energy harvester Including a lower electrode; a ferroelectric material layer which is disposed on the lower electrode and formed of a poled ferroelectric material; a friction-charged body which is adapted to be repeatedly contacted with and separated from the ferroelectric material layer and has an electric susceptibility different from an electric susceptibility of the ferroelectric material layer; and an upper electrode provided on the friction-charged body.

Provided is an electrostatic energy harvester Including a lower electrode; a ferroelectric material layer which is disposed on the lower electrode and formed of a poled ferroelectric material; a friction-charged body which is adapted to be repeatedly contacted with and separated from the ferroelectric material layer and has an electric susceptibility different from an electric susceptibility of the ferroelectric material layer; and an upper electrode provided on the friction-charged body.

A rolling bearing according to an embodiment includes a stationary ring having a first facing surface, a rotating ring having a second facing surface facing the first facing surface, and rotating relative to the stationary ring, rolling elements arranged between the first facing surface and the second facing surface, a cage that retains the rolling elements, first electrodes and second electrodes fixed in position relative to the stationary ring and arranged in a bearing space between the stationary ring and the rotating ring, third electrodes fixed in position relative to the rotating ring, position relative to the rolling elements, or position relative to the cage and arranged in the bearing space, and an insulating film formed on surfaces of the first electrodes and the second electrodes or surfaces of the third electrodes.

A power generating element 1 according to an embodiment includes a displacement member 10, a displacement member 20, and a fixed member 30. The displacement member 10 and the displacement member 20 are connected via an elastic deformation body 41. The displacement member 10 is connected to an attachment section 51 via an elastic deformation body 42. The displacement member 10 and/or the displacement member 20 includes a first power generation surface. The fixed member 30 includes a second power generation surface opposed to the first power generation surface. An electret material layer is provided on one surface of the first power generation surface and the second power generation surface. A counter electrode layer is provided on the other surface.

Power generated by a vibration power generator utilizing an electret is efficiently supplied to a power supply load. A vibration power generator includes a first substrate and a second substrate configured to be moved relative to each other by external vibration while remaining opposite each other, a group of a plurality of electrets arranged in the relative movement direction on one surface side of the first substrate, and a group of electrodes arranged in the relative movement direction on a surface side of the second substrate opposite to the group of electrets, and including a first current collecting electrode and a second current collecting electrode. A power supply load to which power generated by the external vibration is supplied and which has an impedance lower than an internal impedance of the vibration power generator is electrically connected to each of the first and second current collecting electrodes.

Power generated by a vibration power generator utilizing an electret is efficiently supplied to a power supply load. A vibration power generator includes a first substrate and a second substrate configured to be moved relative to each other by external vibration while remaining opposite each other, a group of a plurality of electrets arranged in the relative movement direction on one surface side of the first substrate, and a group of electrodes arranged in the relative movement direction on a surface side of the second substrate opposite to the group of electrets, and including a first current collecting electrode and a second current collecting electrode. A power supply load to which power generated by the external vibration is supplied and which has an impedance lower than an internal impedance of the vibration power generator is electrically connected to each of the first and second current collecting electrodes.

A novel motor drive system has been described for use in electrostatic generator/motor systems based on the time variation of capacity of a rotating condenser comprised of segmented rotor and stator elements. It takes advantage of the fact that the motor action of such a system depends only on the rms value of the drive pulses, which therefore can be formed simply by periodically interrupting a high-frequency ac wave train. This new circuitry simplifies the drive system and takes advantage of recent developments of devices used in the art of inversion of dc voltages to high-frequency (tens of kiloHz) ac.

The invention provides an energy generation and/or conversion system and method wherein an electrical power generator is controlled to periodically alternate between a contact-mode, during which elements of the generator are brought into contact to induce a state of charging, and a non-contact mode, during which plates of the generator are separated from one another and electrical energy is generated through electrostatic induction. Timing and duration of contact and non-contact modes are controlled by a controller, or by user commands, in dependence on a charge state of the elements of the generator: In this way elements are controlled to come into contact only when surface charge has fallen below a certain level, and re-charging is necessary; contact time between the elements may hence be minimisedthereby minimising incurred noise and surface wearwhilst still maintaining a given desired threshold power output.

The invention provides an energy generation and/or conversion system and method wherein an electrical power generator is controlled to periodically alternate between a contact-mode, during which elements of the generator are brought into contact to induce a state of charging, and a non-contact mode, during which plates of the generator are separated from one another and electrical energy is generated through electrostatic induction. Timing and duration of contact and non-contact modes are controlled by a controller, or by user commands, in dependence on a charge state of the elements of the generator: In this way elements are controlled to come into contact only when surface charge has fallen below a certain level, and re-charging is necessary; contact time between the elements may hence be minimisedthereby minimising incurred noise and surface wearwhilst still maintaining a given desired threshold power output.

An electret element includes: an Si layer, an SiO.sub.2 layer formed at a surface of the Si layer; and an electret formed at the SiO.sub.2 layer near an interface of the SiO.sub.2 layer and the Si layer.