Abstract:
A capacitive generator has a generator circuit (G) and a charge priming circuit (P) that includes variable capacitors ( 1, 2, 101, 102 ) all coupled to a mechanical transmission which acts to vary the capacitance of the capacitors and to actuate an array of switches (K). A small residual charge on the priming circuit (P) can thus be amplified and conveyed to the generating circuit (G) where it is used to generate an alternating current between the variable capacitors ( 1, 2 ) of the generating circuit. The capacitance of the generating capacitors ( 1, 2 ) is varied in antiphase in response to the movement of the transmission. An electrical energy extraction device ( 8 ) in circuit with the generator capacitors ( 1, 2 ) extracts electrical energy from the circuit in reaction to the alternating current which can then be used to power or recharge a small portable device.

Description:
This application is a National Phase entry of PCT International Application, Serial No. PCT/RU2008/000457, filed Jul. 11, 2008, which claims priority to Russian Federation (RU) Application No. 2007127122, filed Jul. 17, 2007, which are each incorporated herein by reference. 
     TECHNICAL FIELD 
     The present invention is concerned primarily with the design and operation of a low cost, miniature portable capacitive electric current generator able to generate useful amounts of electric current in response to incidental movements of a part of a device such as the flip of a cellphone. The generator is envisaged as being especially useful in supporting the power supply to portable electronic devices, such as mobile phones, personal digital assistants, global positioning systems, MP3 players, personal and/or implanted medical devices and so on. It should be understood that the application of the generator is potentially to any small, miniature device requiring an electric charge to operate and is not to be limited to the examples given above. The generator of the invention aims to serve devices with average power consumption of the order of 0.1 W to 4 W and peak consumption of 10 W may be served by the generator, however devices of larger or smaller power consumption may be served. 
     As the cost, size and performance of electronic, particularly data-processing devices improves they are becoming increasingly ubiquitous and are likely in future to appear in almost every man-made product. At present most portable scale electronic devices rely upon chemical cells of rechargeable or single use type to store and deliver electrical power on demand. However, such chemical cells or batteries require replacement from time to time, and in the case of rechargeable cells, onerously frequent recharging as well. Most forms of rechargeable cells sufficiently compact for use in small electronic devices self discharge significantly over periods of time measured in days or weeks making them ill suited for use in occasionally used devices. 
     It has previously been noted that one potential source of energy capable of supplying at least a part of the power demands of the miniature electronic devices mentioned above is human muscle power. Historically, the everyday motions of a moving wrist have been used to wind the spring of a wristwatch. Some researchers have sought to use similar mechanisms to move conductors through a magnetic field in order to generate electricity for storage in cells for electrical devices. 
     An alternative mechanism for electrical charge generation from a mechanical motion is the generation of an electric field in a capacitor which is then varied by means of a mechanical movement of part of the generator in order to induce charge to move through a conductor. An early example of such an electrostatic capacitive generator is described in the U.S. Pat. No. 4,127,804. In the generator described here two variable capacitors are mounted on a common shaft. Each plate of each capacitor is a segment of a disk. One plate of each of the variable capacitors is mounted as a rotor on the shaft while the other plate is mounted as a stator. The arrangement of each of the capacitors is such that as the shaft rotates the distance between the plates of each capacitor changes so that their respective capacitance varies in anti-phase, one rising to a maximum as the other falls to a minimum. The respective capacitor plates are electrically connected by a conductor via a load. Initially a priming charge must be loaded onto one of the capacitors. Any mechanical force causing the driveshaft to rotate will cause the capacity of the charged capacitor to fall while the capacity of the uncharged capacitor rises, charge will therefore flow reciprocally between the capacitors as an alternating current. The flow of alternating current can be used to induce a charge onto an accumulator such as a chemical storage cell for later use. 
     The device described in U.S. Pat. No. 4,127,804 suffers from unsatisfactory overall and volumetric efficiency and suffers a serious flaw in that the priming charge will, over a fairly brief time discharge. For the avoidance of doubt “volumetric efficiency” is an expression relating the useful energy output by a generator to the energy input and the volume of the generator. Once discharged, the priming charge must be replaced or the generator will not work at all. 
     U.S. Pat. No. 4,897,592 discloses a device in principle similar to that of U.S. Pat. No. 4,127,804 which also has unsatisfactory volumetric and overall efficiency, but addresses the problem of the priming charge discharging by the somewhat unsatisfactory suggestion that the electrostatic priming charge be applied to the capacitor plates of the generator by an external energy source such as a battery. 
     In an effort to circumvent the priming charge problem more recent development has focused on electret based device. One example of an electret based device is described in US 2004/0207369. Such devices are different from capacitance-based devices in that the electret is a component formed of a material which permanently stores an electrostatic charge applied to it during the production process. This charge cannot leave the electret but is used to induce a movement of charge by moving the electret relative to two nearby electrodes. Thus electret-based generators overcome one of the principal disadvantage of capacitance-based generators. Unfortunately electrets are prohibitively expensive and so uneconomic for most applications. Furthermore, the charge density of electret generators is significantly less good than that for capacitor based generators so that electret based generators cannot achieve similar high overall or volumetric efficiencies. 
     According to a first aspect of the present invention there is provided a capacitive electric current generator wherein: 
     a capacitive generating circuit is arranged to be responsive to a force from a transmission to generate an electric current; and, 
     a priming charge circuit comprising at least two priming capacitors coupled with the transmission so that their capacitance varies and electrically connected to the capacitive generating circuit to generate and deliver a priming charge to the capacitive generating circuit. 
     According to a second aspect of the present invention there is provided a generator having: 
     at least two variable capacitors, each of said capacitors comprise a pair of conductive layers separated by a variable dielectric, 
     an electrical energy extraction device connected between a conductive layer of one capacitor plate of one of said variable capacitors and a conductive layer of the other of said capacitors, 
     a transmission coupled to vary the capacity of each capacitor, in response to a force from an external source, so that, as one capacitance increases the other decreases, with a constant distance between the conductive layers, whereby, 
     when a priming electric charge is stored on the capacitors the priming charge is conducted through the electrical energy extraction device to extract electrical energy. 
     According to a third aspect of the present invention there is provided a generator having: 
     at least two variable capacitors, each comprising a mobile plate and a stator plate, 
     each plate comprises a conductive layer and a dielectric layer lying between the confronting faces of the plates, 
     one of the conductive layers of each of said capacitors is electrically connected to an electrical energy extraction device, 
     each capacitor is coupled to a mechanical transmission which varies the capacity of each capacitor, in response to a motivating force from an external source, by moving the mobile plates of each capacitor relative to the stator plates whereby, 
     when a priming electric charge is stored on the capacitors the priming charge is conducted through the electrical energy extraction device to extract electrical energy characterized in that the shape of the layers of each capacitor is such that the dielectric between the plates varies to change the capacitance when the mobile plate is moved with respect to the stator plate. 
     According to a fourth aspect of the present invention there is provided a variable capacitor for use in a generator comprising a pair of opposing conductive layers fixed such that the distance between the conductive layers is constant and separated by a dielectric layer having a permittivity which can be varied in response to a force. 
     The permittivity of the dielectric may be varied by having at least two overlying layers of dielectric, each formed of regions of dielectric of different permittivity arranged across their confronting surfaces. One dielectric is mounted to be displaced relative to the other so that regions of high permittivity coincide on each plate in one position and regions of high and low permittivity on opposing plates coincide in another position. Thus the overall value of permittivity of the dielectric can change from a high value to a low value, so changing the capacitance of the capacitor. Relative movement of the dielectric layer can readily be achieved by a transmission which may displace the dielectric linearly or rotationally. Displacement is preferably parallel to or tangential to the layer. Preferably the displacement is achieved without changing the volume of the capacitor. 
     The capacitance of the capacitors may be varied synchronously and/or in antiphase to effect the change in capacitance. 
     The mechanical transmission may be coupled to structures of the portable device such as a push button, sliding cover or flip open cover, a hinge or a squeezable handle, so that the muscular effort of, for example, opening the device for use, drives the generator. The generator may be implemented as a stand alone device for delivering charge to other devices. The generator may be implemented into the a shoe to recover power from the action of a wearer walking. 
     Additional preferred and optional features of the present invention are described in the dependent claims. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       An embodiment of a generator constructed in accordance with the present invention, will now be described, by way of example only, with reference to the accompanying drawings, in which: 
         FIG. 1  it is a circuit diagram illustrating the electrical connections of a generator including a generator circuit and a priming circuit, 
         FIG. 2A  is an exploded perspective diagram illustrating a first embodiment of the generator, 
         FIG. 2B  is a perspective cutaway assembly drawing of the generator of  FIG. 2A , 
         FIG. 2C  is a further perspective cutaway drawing showing further internal details of the first embodiment, 
         FIG. 2D  is a side elevation of the first embodiment, 
         FIG. 3A  is a plan view of the first embodiment, 
         FIG. 3B  is a diagrammatic plan view of a stator plate of one variable capacitor of the generator of  FIG. 2A  viewed as on the line IIIB-IIIB, 
         FIG. 3C  is a plan view of a rotor plate of one variable capacitor of the generator of  FIG. 2A  viewed as on the line IIIC-IIIC, 
         FIG. 4A  is a diagrammatic sectional side elevation on the line IV(A)-IV(A) viewed in the direction of the arrows in  FIG. 3A  showing a segment of a generator of the first embodiment in an initial primed state, 
         FIG. 4B  is a circuit diagram of the generator of  FIG. 4A  showing the charge condition of the capacitors in the initial primed state, 
         FIG. 5A  is a diagrammatic sectional side elevation on the line IV(A)-IV(A) of  FIG. 3A  showing the segment of the variable capacitor in a charge displacement phase approximately 90 degrees through the cycle, 
         FIG. 5B  is a circuit diagram illustrating the charge states of the capacitors in the charge displacement phase of  FIG. 5A , 
         FIG. 6A  is a diagrammatic sectional side elevation on the line IV(A)-IV(A) of  FIG. 3A  showing the segment of a variable capacitor at the end of one charge displacement phase, that is to say 180° through the process cycle, 
         FIG. 6B  is a circuit diagram illustrating the charge state of the capacitors in  FIG. 6A , 
         FIG. 7A  is a perspective view of the generator from above showing an initial showing an initial state of the priming capacitors, 
         FIG. 7B  is a circuit diagram of the generator showing the charge states and switch conditions of the priming capacitor circuit in the initial phase of  FIG. 7A , 
         FIG. 8A  is a view as for  FIG. 7A  illustrating a second phase switching step in the operation of the self priming circuit, 
         FIG. 8B  is a circuit diagram illustrating the charge states of the second phase of the self priming circuit of  FIG. 8A , 
         FIG. 9A , is a view as for  FIG. 7A  illustrating at the priming capacitors at a third phase, 
         FIG. 9B  is a circuit diagram illustrating the charge states of the third phase, 
         FIG. 10A  is a view as for  FIG. 7A  illustrating a fourth phase, 
         FIG. 10B  is a circuit diagram showing the charge and switching states of the components of the self priming circuit in the fourth phase. 
         FIG. 11  is a perspective view of a flip phone with the generator of the first embodiment installed in a hinge structure, 
         FIGS. 12A and 12B  are sectional elevations through a segment of an alternative capacitor structure for use in a second embodiment of the invention, 
         FIG. 13A  is a plan view of a capacitor plate of a third embodiment of the invention 
         FIG. 13B  is an elevation of a generator using the capacitor structure of  FIG. 13A , 
         FIG. 13C  is a section on the line A-A in  FIG. 13A , 
         FIGS. 14A ,  14 B and  14 C is a fourth possible embodiment of the present invention. 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
       FIG. 1  is the electric circuit diagram for a generator of the present invention, this consists of a variable first capacitor  1  and a variable second capacitor  2 . As can best be seen in  FIG. 2A  the generator consists of three discs A, B and C coaxially mounted around a driveshaft  18 . 
     Disc B is mounted between discs A and B coupled to the driveshaft  18  for rotation, while the upper and lower discs A and C are irrotatably mounted in relation to the driveshaft and the disc B. 
     It can be seen from  FIG. 2A  that each disc is divided into an inner annulus marked as G, and an outer annulus marked P. Rings R electrically isolate the annuli. As will be described below the inner region provides the generating circuit G, while the outer annular regions of the discs provide a self priming circuit P. 
       FIG. 3A  is a plan view of the assembled generator from above in  FIG. 2A . The lower face of discs A and the upper face of disc B are similar. 
       FIG. 3B  shows the upper face of disc C in plan.  FIG. 3C  illustrate the lower face of the disc B which is obscured in  FIG. 2A . 
     As shown structurally in  FIGS. 2A to 2D  and more functionally in  FIGS. 4A ,  5 A and  6 A the variable capacitors  1 ,  2  each comprise two opposing annular plates. The first capacitor  1  comprises opposing plates  3  and  5  while the second capacitor  2  comprises opposing plates  4  and  6 . The plate  3  is provided on the disc A in  FIG. 2  the plates  4  and  5  on the disc B and the plate  6  on the disc C. Each of the opposing plates  3 ,  4 ,  5 ,  6  consists of a layer of electrical conductor  9 ,  10 ,  11 ,  12  and a dielectric layer  13 ,  14 ,  13   a ,  14   a  is bonded one each to each conductive layer  9 ,  10 ,  11 ,  12  to prevent electrical charge from crossing the gap separating the plates while remaining to some degree pervious to the electric field. 
     Each dielectric layer  13 ,  13   a ,  14 ,  14   a  is divided into regions  15  (shown in crosshatch) having a low dielectric permittivity and regions  16  (shown clear) having high dielectric permittivity. As can be seen from  FIGS. 3B and 3C  the regions of high and low permittivity extend radially, as segments of similar size, from an inner annulus near the centre of the disk to an annulus toward the rim of the disc. It will be noted that the regions of high and low permittivity on plate  4  are rotated relative to the other plates  3 ,  5  and  6  which all resemble  FIG. 3B . 
     Because the variable capacitor uses confronting layers of dielectric material, the maximum dielectric permittivity of the layer can be very high by comparison with air. actual values will depend on the dielectric selected. 
     Each of the plates  3 ,  4 ,  5 ,  6  is mounted coaxially around a transmission provided by the driveshaft  18 . 
     Rotor plates, one each for each capacitor are provided by mounting one of the plates  5 ,  4  of each capacitor  1 ,  2  on the driveshaft  18  to be relatively rotatable with respect to each of the stator plates  3 ,  6 . It can be readily understood from this arrangement that as the rotor plates  4 , 5  turn the regions of high dielectric permittivity  15  of the opposing plates of each capacitor  1 ,  2  alternately align themselves in opposition, as shown in the capacitor  1  of  FIG. 4A  and then adjacent as shown in the capacitor  2 . The alignment of the rotor plates of the capacitors  1 ,  2  is as shown in  FIG. 4A  such that when one rotor plate has its dielectric regions fully aligned in opposition, the other has its dielectric regions fully adjacent. The result of this arrangement is that the permittivity of the dielectric layers between the conductor layers of each capacitor varies cyclically from a maximum to a minimum value as the plates  4 ,  5  are rotated. The maximum value of permittivity being achieved when regions of similar dielectric permittivity are in opposition. By virtue of this arrangement the capacitance of each capacitor  1 ,  2  varies in antiphase. 
     The difference in permittivity of the regions  15 ,  16  can be achieved either by the deposition of materials of different permittivity onto the conductive layer, or by different treatment of a single dielectric layer over the regions to induce a desired change in the dielectric properties. The plates of the capacitor may thus be fabricated by known processes such as printing or plasma deposition onto a suitable substrate. 
     A spacer or bearing member  17   a ,  17   b  may be provided between the opposing faces of the dielectric layers. 
     Each the conductive layer  10 ,  11  of each stator plate  3 , 6  communicates via a conductor  7 ,  7   a  with the conductive layer  9 ,  12  of the rotor plate  5 ,  4  of the other of the capacitors. Thus the conductor layer  11  of the plate  3  communicates with the conductive layer  12  of the rotor plate  4  via conductor  7  while the conductive layer  9  communicates with the conductive layer  10  via the conductor  6 A. 
     As shown in  FIG. 4B  when a charge is loaded onto the first generator capacitor  1  so that, in this case, the plate  5  achieves a relatively positive charge, the opposing plate  3  achieves a corresponding negative charge. When a torque, is applied to rotate the driveshaft  18 , the rotor plates  3  and  4  rotate altering the relative alignment of the dielectric regions  15  and  16  of each respective opposing plate. In consequence the capacitance of the capacitor  1  falls from its maximum value while the capacitance of the capacitor  2  rises from its minimum value. As illustrated in  FIGS. 5A and 5B  the consequence is that the charge is displaced from the capacitor  1  through the conductor  7   a  towards the capacitor  2  through an energy extraction device  8  as current I. 
     The energy extraction device is a load, for example a transformer. 
     As the current flows through the energy extraction device  8  electrical energy is drawn off, without discharging the priming charge Q, and may then be used as desired. For example, the energy may charge a chemical cell or some other form of accumulator. 
     It will be readily appreciated that if the process is continued the relative alignment of the regions  15 ,  16  illustrated in  FIGS. 6A and 6B  will be reached where a maximum charge is stored on the second capacitor  2  and a minimum on the first capacitor  1 . This can be regarded as 180 degrees through the generation cycle. Continued rotation in either direction will cause the charge transfer to reverse towards the phase condition of the capacitors in  FIGS. 4A and 4B  inducing the charge to travel back through the conductor  7  to the capacitor  1  so that the energy extraction device  8  will see an alternating current. 
     It will be appreciated that the capacitance of each capacitor is varied without altering the distance between the conductive plates  9 ,  11  of the first capacitor or  10  and  12  of the second capacitor  2 . The use of a dielectric layer between the conductive plates of each capacitor which has a variable permittivity allows the capacitors to store a large charge at high-voltage allowing a high energy density and correspondingly relatively higher power generation performance than hitherto possible with similar devices. The volumetric efficiency can be enhanced by polishing the confronting surfaces of the dielectric layers to a high degree and minimising the gap, which may be an air gap between them.
     Capacitance is C=C 0 /[1+∈(δ/d)]   Where   C 0  is capacitance of variable capacitor with no air gap between dielectric layers;   ∈—dielectric permittivity   d is thickness of dielectric layers;   δ is equal to (t−d)—air gap between dielectric layers;   t—total gap between conducting plates;   This formula is true for the condition of δ&lt;&lt;d. From this formula the acceptable air gap that does not bring about crucial reduction of capacitance should be ∈ times less than thickness of dielectric.   

       17  refers to a rotor substrate on to which the rotor plates  4  and  5  are formed and provides electrical insulation and structural strength between the plates  4  and  5 . Similar insulating and reinforcing members may be provided around the other generator components but have not been illustrated to avoid unnecessary complication. 
     The design of the capacitors allows the generator to be manufactured at low cost while exhibiting high performance and a high degree of reliability. 
     A problem arising with any form of capacitor-based generator is the gradual loss of the priming charge. To address this problem the generator of the present invention is provided with a self priming circuit  101  which as a consequence of movement conveyed by the transmission  18  will generate or restore the priming charge on the generator capacitors, as illustrated in  FIG. 1 . This circuit  101  consists of two variable priming capacitors  102 ,  103  of design similar to that of the generator capacitors  1  and  2 . A structural drawing of the self priming capacitors is provided by  FIGS. 2A ,  2 B and  2 C.  FIG. 7A  illustrates the phase alignment of the capacitor plates.  FIG. 7B  is a circuit diagram illustrating the charge condition of each component in a first phase illustrated in  FIGS. 7A and 7B . 
     The priming capacitors  102 ,  103  each consist of a pair of annular plates  104 ,  105 ,  106 ,  107 . The plate  107  is provided on the outer annulus of stator disc C. Plates  106  and  105  are provided in back to back relation on the rotor disc B and plate  104  on the stator disc A. 
     Each plate  104 ,  105 ,  106 ,  107  is formed from a respective conductive layer  104   a ,  105   a ,  106   a ,  107   a  on which is deposited a dielectric layers  103   b ,  104   b ,  105   b ,  106   b  respectively. In particular the conductive layers of the priming capacitors are separated from the conductive layers of the generator capacitors, on the same disc, by the electrically isolating rings R. The dielectric layers of the priming capacitors  102 ,  103  are separated into alternating radially extending regions of high dielectric permittivity  115  (the crosshatched segments in the drawings) and low dielectric permittivity  116  (the clear segments). arranged to vary in phase as the plates are displaced by the transmission shaft  18  as can be discerned from  FIGS. 3B and 3C  as well as  FIGS. 8-11 . 
     A switch system  108  is driven synchronously with the change in capacitance induced by relative displacement of the plates  104 - 107 . The switch system consists of three switches K 1 , K 2  and K 3  respectively. The switch K 1  is arranged to electrically isolate or communicate between the plate  104  of the first priming capacitor  102  and the plate  106  of the second priming capacitor  103 . The switch K 2  is arranged to electrically communicate or isolate the plate  106  with the plate  105  of the first priming capacitor  102 . The switch K 3  is arranged to electrically communicate or isolate the plate  105  with the plate  107  of the second priming capacitor  103 . 
     The self priming circuit may rely on the presence of at least a small residual charge on the generator capacitors  1 ,  2 . A residual charge is one much less than the priming charge, for example 10% or 1% or 0.1%. Its actual value will depend on the conditions of operation as well as the construction of the priming capacitors. This can be ensured by careful selection of the material from which the capacitors are constructed. Preferred materials include Barium Titanate, Barium Strontium Niobate because of their high dielectric permittivity. Such materials retain at least a small electric charge indefinitely. 
     Other dielectric materials exist which will generate small electric charges simply by the action of friction as the opposing capacitor plates move. Friction may be caused by the action of the rotating dielectric pressing against a spacer  102   a ,  103   a  interposed between the opposing dielectric layers. This may be sufficient to initiate the self priming process described below. 
     The residual charge (Q) is illustrated as being present on the generator capacitor  2  arranged to communicate with the plates  104  and  107  as shown in  FIG. 1  when read with  FIG. 8A . In the initial state the switches of K 1 , K 2  and K 3  are all open and there is no charge on any of the priming capacitor plates. 
       FIGS. 8A and 8B  show the second phase of the self priming process where rotation of the rotor B causes the switches to set K 1  and K 3  open and, K 2  closed the residual charge source initially communicates with the priming capacitor plates  104  and  107  raising the charge on those plates to +q and −q respectively. In consequence an equal and opposite charge is induced on the opposing plates  105 ,  106 . It will be noted that at this stage the dielectric regions are aligned to maximum permittivity in both capacitors  102  and  103 . The charge on the generator capacitor plates changes to +(Q−q) and (Q−q). 
     In the third phase illustrated in  FIGS. 9A and 9B  all the switches are open, the rotor plates  104 ,  106  are displaced to minimise the permittivity of the dielectric layers between the capacitors  102 ,  103  and so the charge on the generator capacitor  2  returns to +Q and −Q. 
     In the fourth phase illustrated by  FIGS. 10A and 10B  the switches K 1  and K 3  are closed and K 2  is open to communicate the plates  104  with  106  and  105  with  107  while the dielectric layers remain aligned to produce a minimum permittivity. The result is that the charge on the generator capacitor  2  rises to Q+q. Repeating the self priming process steps by returning the self priming circuit to the first phase results in Q being set equal to Q+q for the next cycle of self priming which can be repeated indefinitely until Q reaches a maximum determined by the limiting capacity of the generator capacitors  1 ,  2  so amplifying the priming charge to a maximum. 
     As illustrated in  FIGS. 2 and 3  the design of the self priming circuit can advantageously be implemented in a rotary generator by constructing the priming capacitor plates  104 - 107  on annuli of the same structural discs forming the generator capacitors. 
     The switches K 1 , K 2 , K 3  may conveniently be provided on the outer surfaces of the stator discs A and C to be actuated by the rotation of the shaft relative to the stator disc. Alternatively the switches may be fabricated into the portions of the rotor and stator discs A, B, C not serving as capacitors so that the relative rotation of the rotor disc and stator discs actuates the priming circuit switches. 
     It will be readily apparent to the skilled person that the same effects can be achieved where the generator is implemented as linearly moving capacitor plates. 
     As illustrated in  FIG. 11  the discs A, B, C and shaft  18  may form part of the hinge structure coupling the parts  21 A,  21 B of a flip phone  21 . In this application of the generator disks A and C may be mounted to the part  21 A while the disc B is mounted to the part  21 B, thus when the phone is flipped open the disc B rotates relative to the discs A and C. Gearing (not shown for the sake of clarity) may be provided to one of the stator discs A and C or the rotor disc B so that the action of opening the flip phone causes several relative rotations of the discs. Further the generators may be banked as shown in  FIG. 11  so that a plurality of generators provide the hinge structure. 
       FIGS. 12A and 12B  show a second embodiment of the capacitor structure for use as variable generator or priming capacitors. Each capacitor  1 ,  2  is similar and so only one will be described. The capacitor comprises a first mobile plate  201  and a second static plate  202 . Which of the plates is movable is purely a matter of design selection, the important feature being that like the first embodiment the capacitor plates are relatively displaceable in a direction lying in a plane parallel to their confronting surfaces. The first and second plates have conductive layers  203 ,  204  respectively. The conductive plates  203 ,  204  are provided with confronting surfaces  205 ,  206  which are shaped as rib formations  207 ,  208  providing projections which are separated by adjacent troughs  209 ,  210  the whole of each confronting surface of  205 ,  206  is coated with a uniform thickness layer of Bastron to provide a dielectric layer. Bastron in this case is simply an example of a suitable material. The rib formations may be created by copper tape fastened to the conductive layer  203 ,  204  although more sophisticated production techniques could be used in manufacture. The plates  203 ,  204  are supported so that the smallest possible gap separates the proximal ends of the ribs  207 ,  208  when they are aligned in opposition as shown in  FIG. 12A . As the mobile plate  201  is displaced in the direction of the arrow A the confronting ribs  207 ,  208  on the plates move from the opposed alignment shown in  FIG. 12A  to the adjacent alignment shown in  FIG. 12B . This alters the permittivity of the dielectric between the plates so changing the capacitance of the capacitor between minimum and maximum values. It will be noted that the troughs separating the rib formations on the plate  201  are and integer multiple of the width of the troughs separating the ribs on the plate  202 . In this example the integer is three. 
     The examples of the generator given rely on relative rotary motion of the plates which presents certain advantages in efficiency and mechanics. However, it is within the scope of this invention that the plates may be relatively reciprocally moved either rotationally or linearly. 
     The fabrication of the capacitors can be conveniently achieved using layer by layer laser sintering by intermittent laser impulse or one time laser sintering by a single laser impulse of one layer. Dielectrics may be deposited on to a substrate using sputtering. 
       FIGS. 13A-13C  show another embodiment of the invention. This embodiment is presented in the priority application RU2007127122/06(029591). A capacitive generator of electric current comprises two electric capacitors  301 ,  302  of alternating capacitance, provided that each of the capacitors has capacitance that can be changed between a minimum and a maximum, the capacitors are connected by an electric circuit; the capacitors are connected mechanically in anti-phase so that when one capacitor has minimum capacitance, the other capacitor has maximum capacitance; when the capacitors are manufactured, direct potential is applied to the electrodes of capacitors. 
     Each of the capacitors is formed from a ferroelectric plates  303  (electrets) the outermost surface of which is coated with a conducting layer. Opposing surfaces have tooth elements  303  the ridges of which are oriented perpendicular to the direction of relative displacement. Both electrodes can have forward movement or rotational movement one in regards to the other so that the electrodes move in a plane parallel to their major axis and the electrodes remain at a constant distance from each other. An electric circuit  306  contains elements, which provide for a regime of charge self-excitation to provide a priming charge to the generator capacitors  301 ,  302   
     When one ferroelectric plate (electrets) is rotated as regards the other, tooth elements are displaced ones as regards the others. The air gap between the plates changes from minimum value when ridges of teeth face each other to maximum value when ridges of tooth elements of one plate are above cavities of tooth elements of another plate. Such modulation of air gap brings about alteration of capacitance of the capacitor, alteration of potential difference on the electrodes. This change is registered by voltmeter  6 . Rotation of ferroelectric plates (electrets) requires application of mechanical energy that is converted into electrical energy. The best embodiment of the device says that during one mechanical rotation the capacitor is charged and recharged with the frequency that is equal to the number of tooth elements covering the span of displacement of the gear. 
       FIG. 14  illustrates an advantage of the invention that the generator may be configured in many shapes. In this case the generator is formed from two concentric tubes. The generator comprises two axially spaced tubular generator capacitors  401 ,  402 . These consist of an inner tube providing two axially spaced tubular generator capacitor plates  404 , of which only one shows in the drawings. Opposing generator capacitor plates are provided as parts of the outer tube shown at  406  and  403 . Each plate is electrically isolated from the adjacent plates by rings R. 
     Each inner plate  404  comprises a inner layer of conductor and each outer plate comprises an outermost layer of conductor  403   a ,  406   a . each inner tube has an outermost layer of dielectric material, while each outer tube is provided with an inner layer of dielectric material. The layers of dielectric material are divided into longitudinally extending regions  415  of low permittivity, represented by the dark regions and high permittivity  416  represented by the light regions. As with the previous embodiments one of the layers of dielectric of one of the capacitors has the regions offset so that, when one tube is rotated relative to the other, the dielectric permittivity of one capacitor rises while that of the other falls. 
     A circuit similar to that described with reference to the first embodiment connects the two described generator capacitors so that a charge loaded onto the capacitors will travel back and forth between them when one tube is rotated relative to the next. 
     Priming capacitors  402 ′,  403  are provided by similar tubular capacitors provided by outer and inner layers of conductor  404   a ,  405   a  on which are provided, respectively confronting layers of dielectric  404 ,  405  at the axial ends of the generator. The layers of dielectric material are provided with regions of high and low dielectric permittivity which extend longitudinally and are radially alternated. As with previous examples of the priming capacitors these regions are similarly arranged in each priming capacitor so that the capacitance thereof changes in phase. The priming capacitors  402 ′,  403  are connected in a priming circuit  101  as described for the first embodiment.