MULTIPLE BEAM WIRELESS POWER TRANSMISSION SYSTEM

Abstract

A system for transmitting wireless power from multiple sources to multiple receivers, in which the safety of the system is maintained in spite of the possibility that two beams may intersect in the transmission space, thereby generating power or power density levels which exceed those at which the safety mechanisms of the system were designed to operate. The paths of the beams are known from the transmission positions and directions, and from the positions and orientations of the receivers, as measured by positioning devices on them. When an intersection, or near intersection of beams is determined, the system is triggered to reduce the safety risk by attenuating or turning off, or by diverting, one or more of the beams. In addition, since a reflected beam's path may not be readily discernable, the system can ascertain if one of the beams has undergone a reflection, by looking for displayed mirror images.

Claims

1. A method of ensuring safety in a multiple beam wireless power transmission system comprising beam sources and multiple targets, said method comprising the steps of: (a) determining if any points on trajectories of at least two beams come closer to each other than a predefined safe distance, and if so, either performing at least one of (i) attenuating at least one beam, (ii) turning off at least one beam, and (iii) diverting at least one beam; or sending data associated with said determining to a controller, said controller being adapted to perform at least one of (i) attenuating at least one beam, (ii) turning off at least one beam, and (iii) diverting at least one beam, based on analysis of said data, and (b) detecting if there is a reflective surface in the path of any beam by receiving at said transmission system, image data of a pattern on a target, and determining if an image generated from said image data has a mirror-imaged form compared to that of said pattern on said target, and if so, either performing at least one of (i) attenuating, (ii) turning off, and (iii) diverting at least the beam directed at that target whose image data of a pattern thereon has a mirror-imaged form; or sending data associated with said determining to a controller, said controller being adapted to perform at least one of (i) attenuating, (ii) turning off, and (iii) diverting at least the beam directed at that target whose image data of a pattern thereon has a mirror-imaged form, based on analysis of said data.

2. The method according to claim 1 wherein said image data is electronic image data.

3. The method according to claim 1, wherein said image data is obtained by scanning said target with a beam.

4. The method according to claim 1, wherein said image data is accumulated by collection of electronic data transmitted from said target.

5. The method according to claim 1, wherein said image data is accumulated by use of a camera.

6. The method according to claim 1, further comprising the step of issuing an alert if either of the determinations of steps (a) and (b) are positive.

7. The method according to claim 1, wherein at least one of said beams is a transmitted beam from a beam source.

8. The method according to claim 1, wherein at least one of said beams is a beam reflected from a target.

9. The method according to claim 1, wherein said attenuating of a beam is performed by adjustment of the beam source.

10. The method according to claim 1, wherein said turning off of a beam is performed at its beam source or by use of a shutter.

11. The method according to claim 1, wherein said diverting of at least one beam is performed by use of a beam scanning device.

12. The method according to claim 1, wherein a trajectory of a beam transmitted by a beam source is determined by use of the known position of said beam source, and the known orientation and position of a beam scanner device used to direct said beam in space.

13. The method according to claim 8, wherein said position and orientation of a reflected beam is determined by ascertaining the trajectory of a transmitted beam impinging on said target, and the position and orientation of said target.

14. The method according to claim 13, where the position and orientation of said target is determined by using at least one of an accelerometer and a compass mounted in a known position relative to said target.

15. The method according to claim 13, where the position and orientation of said target is received from a device mechanically connected to said target.

16. The method according to claim 13, where the position and orientation of said target is calculated by analyzing an image of said target or a pattern on said target.

17. The method according to claim 1, wherein said determining if any points on trajectories of at least two beams come closer to each other than a predefined safe distance, comprises: (i) determining the position and orientation of a first beam and a second beam; (ii) calculating at least one plane including said first beam, each of said planes comprising the trajectory of said first beam; (iii) determining at least one point where said second beam crosses one of said at least one plane; and (iv) measuring the distance between each of said at least one point from said trajectory of said first beam.

18. The method according to claim 1, wherein, if any points on trajectories of at least two beams come closer to each other than said predefined safe distance, said analysis further comprises determining if said expected combined power level of said at least two beams is greater than a predetermined safe level.

19. The method according to claim 1, wherein said analysis of said data resulting from said step of determining if any points on trajectories of at least two beams come closer to each other than said predefined safe distance, further comprises calculating an overall risk associated with two or more beams by considering both a probability of intersection of said beams, and a probability that the combined power levels of the beams will exceed said predetermined safe level.

20. The method according to claim 1, wherein at least some of said targets are mounted on mobile telephone devices.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0124] The invention will be understood and appreciated more fully from the following detailed description, taken in conjunction with the drawings in which:

[0125] FIG. 1 is a schematic illustration of a multi beam transmitter, emitting three distinct beams towards a pair of receivers;

[0126] FIG. 2 shows an exemplary multi beam transmitter and a single beam transmitter;

[0127] FIG. 3 which shows an exemplary receiver having two targets for receiving at least two beams;

[0128] FIG. 4 shows the generation of beam intersection points in such a multi beam transmission system as shown in FIG. 2, and the hazards thereby generated;

[0129] FIG. 5 illustrates a flow chart of a method of managing the multi beam transmission in accordance with the methods of the present application, to ensure proper control of beam intersections;

[0130] FIG. 6 illustrates how the system determines if any mirror surface is disposed within the passage of any beam from transmitter to target;

[0131] FIG. 7 illustrates schematically a purely electronic method of determining the symmetry of the images target markings;

[0132] FIG. 8 illustrates schematically how the relative position of two beam sources and their targets may be determined by vector subtraction of the known positions of the beam sources relative to the targets in the receiver; and

[0133] FIG. 9 is a flow chart describing the steps taken according to one exemplary procedure, to ascertain if two beams intersect, or at least pass within a predetermined minimal distance from each other.

DETAILED DESCRIPTION

[0134] Reference is now made to FIG. 1, which illustrates schematically a multi beam transmitter 1, emitting three distinct beams 2, 3, 4 towards receivers 6 and 7, and incorporating a controller 12 for controlling the relevant operation of the system, as described in the Summary Section hereinabove. Although the control system is shown installed in a transmitter unit in FIG. 1, it is to be understood that it can, as described in the Summary Section hereinabove, be disposed elsewhere or even distributed over several systems and locations in the vicinity.

[0135] Receiver 6 includes a single target 5, at which beam 2 is aimed. The power of beam 2 is converted by receiver 6 into electrical power at a stabilized voltage that is supplied to a client device (such as a phone, not shown in the drawing) through power connector 10, which could be integral to the receiver.

[0136] Both beams 3 and 4 are used to deliver power to multi target receiver 7. Beam 3 is aimed at target 8 and beam 4 is aimed at target 9. Receiver 7 converts the optical power from both beam 3 and 4 into electrical power, sums up the power from both beams and delivered it to the device to be charged.

[0137] Receiver 6 responds and transmits data when it detects beam 2. Receiver 7 responds and transmits data when it detects either beam 3 and/or beam 4.

[0138] The method of data transmission is not shown, it is typically achieved through RF, IR, or through an internet connection and is typically received by the transmitter for data analysis.

[0139] The transmissions typically include receiver ID, beam or beams ID, power received, whether total and per each beam, and orientation information, but it may include other data or just a portion of the data.

[0140] Beams 2, 3, and 4 are not shown as crossing each other and are not on the same plane and reflections from the receivers also do not cross each other and do not cross the incident beams.

[0141] Reference is now made to FIG. 2, which shows a multi beam transmitter 21 and a single beam transmitter 22. Multi beam transmitter 21 includes a first beam module composed of laser 23 and steering mirror SM1 and has a field of view limited by the maximal capabilities of steering mirror SM1 to tilt the beam. The field of view FOV1 extends up to the line passing through steering mirror SM1 and point p4 at one extent of the field of view, and the line passing through steering mirror 5M1 and point p1 at the other extent of the field of view. It is to be understood that this description is given a 2-dimensional explanation, due to the nature of the 20 drawing, but the real field of view is typically a 30 rotation of such a 20 representation.

[0142] Transmitter 21 also includes a second beam module composed of laser 26 and steering mirror 5M2 and has a field of view limited by the maximal capabilities of steering mirror 5M2 to tilt the beam, the field of view FOV2 extending up to the line passing through steering mirror 5M2 and point p5 on the one end, and the line passing through steering mirror 5M2 and point p2. It is to be understood that such a description is 2-dimensional due to the nature of this 20 drawing and the real field of view is typically a 30 rotation of such a 20 representation.

[0143] Transmitter 22 includes a third beam module composed of laser 28 and steering mirror 5M3 and has a field of view limited by the maximal capabilities of steering mirror 5M3 to tilt the beam, the field of view FOV3 extending up to the line passing through steering mirror 5M3 and point p6 on the one end, and the line passing through steering mirror 5M3 and point p3. It is to be understood that this description is 2-dimensional due to the nature of this 20 drawing and the real field of view is typically a 30 rotation of such a 20 representation.

[0144] Receiver 24 is inside FOV1 and FOV2 and outside of FOV3

[0145] Receiver 25 is inside FOV3 and FOV2 and outside of FOV1

[0146] Receiver 24 can therefore be powered using laser 23 or using laser

[0147] Receiver 25 can therefore be powered using laser 26 or using laser

[0148] Receivers 24 and 25 detect which of the beams, if any, are powering them, typically by decoding information encoded on the beam(s) itself. Each receiver measures the received power of the beam powering it, and transmits receiver 10, receiver orientation, detected beam 10, received power per beam, capabilities, and other data, which is received by both transmitter 21 and by transmitter 22 and potentially by other receivers and system components.

[0149] Transmitter 21 is aware of the relative starting points and directions of lasers 23 and 26, since the position in space and the orientation of the steering mirror is known, as is the position of the receivers, and transmitter 21 can thus direct the beams to avoid intersecting each other. When both laser beams are in the same plane, and are converging, transmitter 21 calculates their intersection point (if any) and should they intersect, estimates the risk from both beams, in order to decide if an overall risk exists.

[0150] When receiving the data from receivers 24 and 25, transmitter 21 calculates, based on the model ID and on the tilt (usually calculated relative to the gravitational vertical and the magnetic north) and on the range of each receiver the directions of the reflections from each receiver and preforms an assessment of where potential crossing points, if any, are located.

[0151] Receiver 25 is in the field of view of both transmitters 21 and 22, so that it may detect a beam sent by each transmitter and report it. The transmitter that did not send the beam receives the report transmission and begins a procedure to locate and communicate with the other transmitter sharing the same field of view.

[0152] After a communication channel between both transmitters 21 and 22 is established, information about the direction of beams and reflections is exchanged.

[0153] Reference is now made to FIG. 3 which shows an exemplary receiver 31 having two targets 32 and 34 for receiving at least two beams 33 and 35, converting the power in the beams into electrical power and supplying it through conductor 36 to a system utilizing it.

[0154] Beams 33 and 35 have a size and shape allowing them to be almost fully absorbed by receiver 31 both in target 32 and 34.

[0155] Beam 33 is aimed at target 32 and is completely surrounded by the boundaries of target 32 while beam 35, aimed at target 34 slightly extends from it. It is possible to use the scanning feature of the beam source to image the target at low power and to ensure that a beam such as beam 35 is centered on the target, before allowing the beam source to raise its power output to that necessary for power transmission to the target.

[0156] Receiver 31 has a front surface which may generate a reflection of small portions, typically between 0.1% and 4%, but occasionally up to 25%, of either beam 33 or 35. The extent of the reflection may be dependent on contamination on the surface, and on the angle of incidence.

[0157] Receiver 31 is equipped with a detector for detecting its spatial orientation, such as a camera, a compass, a gyroscope, an accelerometer, a compass, a GPS device, a triangulation device, or an electronic connection to a device capable of determining its relative orientation, as well as a data transmitter to communicate that information to the transmitters. A common and inexpensive orientation and position detection system can be readily achieved by use of accelerometers as gravity direction detectors, in conjunction with compasses. Such devices are widely available as MEMS-based chips. The transmitter sources must also be equipped with similar components, so that the coordinate system of the receivers can be directly related to those of the sources.

[0158] Triangulation devices can be in either the transmitter or in the receiver, by measuring the distance or echoes (sound, light, radio) from the other device.

[0159] Beam 35 is shown slightly off target, which typically causes receiver 36 to report either a “not on target message” or lower power received measurements.

[0160] Reference is now made to FIG. 4, which shows the generation of beam intersection points in such a multi beam transmission system as shown in FIG. 2, and the hazards thereby generated.

[0161] In such an exemplary system, transmitters or beam generating modules 41 and 42 are transmitting beams 43 and 44 towards receivers 45 and 46 respectively. A portion of beam 44 is reflected from the front surface of receiver 45, as reflection 40. A portion of beam 43 is reflected off the surface of receiver 46 as reflection 39. [0162] Beam 44 crosses beam 43 at point 47 [0163] Reflection 40 crosses reflection 39 at point 49 [0164] Beam 43 crosses reflection 40 at point 48

[0165] It is to be understood that image of FIG. 4 is a 2D image, used to explain a 3D situation, and differences between it and a 3D reality are expected.

[0166] It is also to be understood that beams and reflections in the real 3D world have widths, and any situation where beams are close to each other, typically within a distance of 1 to 10 mm, and sometimes even at 50 mm distances, may have similar consequences.

[0167] A person or an object at points 47, 48, 49 may be exposed to levels of radiance, power, energy, energy averaged over a circular area having a diameter of 1 mm, 3.5 mm, 7 mm, 50 mm or 10 mm. hotspots, hotspots created as a result of coherent or incoherent effects, that are above acceptable levels or are another general risk from the system. This risk can arise from various aspects of exposure. Skin burn risk arises from “hotspots”, eye damage from averaging the power over the area of the pupil. Fire hazard from a small particle from “hotspots”, fire hazard from a larger particle depends on total energy absorbed, the risk for a person looking at the system through a telescope may be measured by averaging the power over the lens of the telescope (50 mm). The system has to evaluate the various risks.

[0168] To prevent such exposure above allowed levels at such hazardous intersection points, the system either alters the parameters of one or both beams—such as power or direction—or terminates one beam, typically replacing it with another.

[0169] Effects such as coherence between the beams, mechanical instability, optical and pointing instability, uncertainty in direction and noise in the system may significantly increase the distance which is considered to be hazardous, between beams/reflections.

[0170] The points 47, 48, 49 are considered “hazardous points” and require the special attention of the safety system. Specifically, for other portions of the beams, a safety system does not need to take into account the other beams in the vicinity, but at such “hazardous points” the safety system is required to consider parameters from both beams, or to avoid such a situation.

[0171] Reference is now made to FIG. 5, which illustrates a flow chart of a method of managing the multi beam transmission in accordance with the methods of the present application, which will ensure proper control of beam intersections. During transmission the following method is implemented continuously.

[0172] In step 51 the system verifies if any beam is transmitting along a path impinging on a mirror. If a beam is found to be transmitting via a mirror, then in step 52, that beam is either attenuated or typically turned off.

[0173] If no beam is found to be transmitted via a mirror, the system checks 53 if the beams are in the same plane. Beams that are in the same plane are checked to see if they are diverging or converging in step 54. Steps 54 and 53 may be performed in any order. For beams in the same plane that are not converging, the range and the direction of reflection vectors are determined in steps 55 and 56 (again order is not important) and then in step 57, it is estimated if any two or more reflections are in the same plane. If none are found, then in step 58, it is estimated whether any reflections are in the same plane as a beam. If none are found, then the system continues transmission, typically performing some or all of these actions iteratively in step 60.

[0174] If in step 54, beams are found to be converging and in the same plane, then in step 59, either the data from the two relevant safety systems is combined into a unified risk assessment for the two beams, raising the safety threshold by so doing, or at least one of the beams is either attenuated or diverted.

[0175] Likewise, in either of steps 57 and 58, if beams/reflections are found to be just in the same plane, even without determining the likelihood of an intersection, then the method also proceeds to step 59, with the same actions performed there.

[0176] Reference is now made to FIG. 6, which illustrates how the system determines if any mirror surface is disposed within the passage of any beam from transmitter to target. Receiver 61 has an asymmetrical pattern 62 on it. When scanned or viewed through a mirror, receiver 61 will appear as image 65 with asymmetrical pattern 66 on it. Since pattern 66 differs from pattern 62 in all types of rotation, the system detects that image 65 is viewed through a mirror and responds to it by turning the beam off.

[0177] Image 63 with asymmetrical pattern 64 is a view of receiver 61 and pattern 62. By rotating pattern 64 it can be overlapped with pattern 62 and it is therefore clear to the system that pattern 64 is not viewed or scanned through a mirror.

[0178] On the other hand, the pattern 68 on image 67 of receiver 61 cannot be overlapped with pattern 62, which is known to the transmitter. Thus the system can deduce that pattern 68 is being viewed or scanned through a mirror reflection.

[0179] If the system detects a receiver and determines that it is being viewed through a mirror, then it refrains from transmitting power to it via the mirror. It may further record the position for further use, which may include refraining from scanning the same position again, or lowering the frequency of such scans

[0180] Calculation of the mirror's position, which requires detection of the real object as well as detection of the “mirror image” of it, may be done by solving the paired equations:

V1=V2+V3

V4=V2−V2*|V.sup.3|/|V.sup.2|

|V2|+|V3|=|V1|

|V1|=|V4| [0181] where V1 is the vector to the real object, [0182] V4 is the vector from the beam source to the “mirror image”, [0183] |Vn| is the length of the vector |Vn|,

[0184] V2 is the vector to the point on the mirror the beam impinges on the mirror, and

[0185] V3 is the vector from that point to the mirror image of the receiver.

[0186] There may be many variations of this scheme of vectorial calculation.

[0187] The mirror is found at V2 and its direction can be found from splitting the angle between V2 and V3.

[0188] The mirror's position may be further used to simplify the location of the real receiver, instead of the mirror image, when another “mirror image” of a receiver is found at a point which appears to be reflected by the same mirror, the real position of the receiver viewed through the mirror may be estimated to assist in locating it.

[0189] The asymmetrical image may preferably be a 2D barcode, allowing identification of the receiver, its type, make, capabilities, and limitations. This data may then be further used for other applications such as billing, quality of service, as well as many other uses.

[0190] Reference is now made to FIG. 7, which illustrates schematically a purely electronic method of determining the symmetry of the images target markings.

[0191] PV1, PV2, PV3 . . . PV6 are all beam targets equally spaced and aligned to the edges of a degenerated hexagon.

[0192] Such a pattern is optically symmetric since its mirror image appears optically identical to the original pattern, but as a rotation of the original pattern.

[0193] However, in the context of a receiver capable of reacting differently to illumination of different parts of the pattern, such a pattern may become asymmetric, as the system may electronically identify each target.

[0194] For example, if a beam is aimed at target PV3 (as opposed to the mirror image of PV3, which may be PV4), the system should be in possession of this information. In order to verify that the beam has not undergone a mirror reflection, the beam is then aimed at the target located a single or more target steps clockwise or counterclockwise. If the beam is aimed one or more target steps forward clockwise and reaches target shape PV4 (as opposed to PV2), then it is not being viewed through a mirror. If it were being viewed through a mirror, it would reach target shape PV2 (and not PV4). Thus, the presence of a mirror reflection in the beam trajectory being monitored, can be determined electronically, and without the need of any imaging step, by observing which target shape is imaged after a known beam movement has been performed.

[0195] A similar algorithm may be performed using multiple beams, or use can be made of a pattern consisting of optical as well as electronic markers.

[0196] Reference is now made to FIG. 8, which illustrates schematically how the relative position of two beam sources and their targets may be determined by vector subtraction of the known positions of the beam sources relative to the targets in the receiver, the vector relationship between the two targets being known since they are both built into a single receiver.

[0197] Beam module 81 and beam module 82, whose comparative positions are sought, are both aimed at power receiver 83 which includes two targets 84 and 85.

[0198] In order to determine the relative distance and direction of beam module 82 with reference to beam module 81, i.e. vector 86, beam module 81 uses vector 87, which is the position of target 84 in receiver 83 which it knows by transmitting a beam to it.

[0199] It also uses vector 89, which is reported by receiver 83, which is the direction and distance between target 84 and target 85

[0200] It also uses vector 88, which may be reported by beam module 82, by an external server or by receiver 83 Vectors 87+89−88 must equal Vector 86 which is the position of beam module 82 relative to beam module 81.

[0201] Beam module 82 either performs a similar calculation or receives the information from beam module 81 or from a central control point, as can beam module 81. These situations can occur if there are many beam modules in the room, and the location of some of the beam modules positions are already known. Then, if a new beam module is found, it may receive the positioning information and does not need to compute it. There is need just to locate the new beam module relative to only one other beam module.

[0202] As described in this disclosure hereinabove, in the Summary section, a novel method is presented of determining if two beams have an intersection point, or at least get close to an intersection point. A set of planes are incrementally rotated around the trajectory of one beam, which is thus located at the common axis of rotation of the incrementally rotated planes. It is then determined whether the second beam passes through any of these incrementally rotated planes within a predetermined minimum distance from the first beam. If so, then those beams are considered to have an intersection point, or a close-to-intersection point, and in order to ensure laser safety, appropriate action must be taken to reduce the risk, such as by shutting down or reducing the laser power of at least one of the beams, or by diverting one of the beams. In practice, this method may be performed by calculating the plane formed by a first beam and at least one point on a second beam.

[0203] This point may typically be the beam origin or its target, since these points are best known and easiest to calculate. Then if another point on the second beam is close to the first beam axis, typically, within a few mm, or within a few radii of the beam, then intersection is likely and further action to alleviate the hazard of such an intersection, as described above, may be needed. On the other hand, if the closest point to the plane on the second beam is far from it, typically, more than a few mm, more than the calculation error margin, or more than a few beam radii, then the initial risk potential is lower.

[0204] Reference is now made to FIG. 9, which describes the steps taken according to one exemplary procedure, to ascertain if two beams intersect, or at least pass within a predetermined minimal distance from each other.

[0205] In step 91, the beams are delineated in three-dimensional geometrical coordinates, using the information regarding the settings of the beam scanners in the beam transmitters, and the location and orientation of the receivers, as described hereinabove.

[0206] In step 92, one of the beam trajectories is selected, and a reference plane is defined containing that beam line.

[0207] In step 93, the intersection of the second beam with the reference plane is determined.

[0208] In step 94, the closest distance in the reference plane between the first beam path, and the point of intersection of the second beam with the reference plane is calculated, by stretching a line from that point of intersection to the first beam path, that makes a right angle with the path of the first beam.

[0209] In step 95, that closest distance is recorded and related to the angle of the reference plane in which the previous steps have been performed.

[0210] Then, in step 96, the reference plane containing the first beam path representation, is rotated around the line of the first beam path, by a predetermined incremental angle, typically less than 50, and step 93 is again performed, to determine the new intersection of the second beam with the reference plane.

[0211] Steps 94 and 95 are then performed at this new position of rotation, and the closest distance is recorded for the new angle of the reference plane.

[0212] This procedure is repeated for additional incremental rotations until in step 97, it is determined that the reference plane has been rotated through 1800, and the procedure proceeds to step 98.

[0213] In step 98, from all of the recorded closest distances, the minimum distance is selected, this defining the closest that beam 2 will come to beam 1. This result is then used to decide whether those 2 beams are considered to have an intersection point, or a close-to intersection point, and in order to ensure laser safety, to initiate appropriate action to reduce the risk engendered by the increased power that may exist at such an intersection of beams.

[0214] There are other methods for determining the nearest distance between two beams, which may involve algebraic calculations such as follows. [0215] If beam 1 is defined as P.sub.1=t.sub.2d.sub.2+r.sub.1 [0216] where t is the free variable, d is the direction vector and r is the origin, [0217] and beam 2 is defined as P2=t.sub.2d.sub.2+r.sub.2 [0218] then the minimal distance between the lines is given by:

[00001]$\frac{d_1{\mathrm{Xd}}_2*\left(r_1-r_2\right)}{.Math.d_1{\mathrm{Xd}}_2.Math.}$

[0219] Other methods of calculating the same nearest distance may alternatively be used.

[0220] It is appreciated by persons skilled in the art that the present invention is not limited by what has been particularly shown and described hereinabove. Rather the scope of the present invention includes both combinations and sub-combinations of various features described hereinabove as well as variations and modifications thereto which would occur to a person of skill in the art upon reading the above description and which are not in the prior art.