WIRELESS POWER SYSTEM HAVING IDENTIFIABLE RECEIVERS

Abstract

A wireless power transmitter system for directing a high energy beam towards receivers fitted with identifying signs. One type of the identifying signs may have asymmetric shape properties, such that their mirror image cannot be matched to their actual shape, even after the image is rotated, tilted or otherwise geometrically manipulated. The system can thus determine whether a detected image of a sign is a true image received directly from said receiver, or is received after the imaged beam has undergone a reflection between the receiver and the transmission system. In the latter case, the system can prevent high power transmission from being directed to a location other than a real receiver, which could be a safety hazard. Other types of identifying signs may be located in or on the borders of different zones of a transmission space, to identify zones where transmission may be allowed or prohibited.

Claims

1. A method of safely directing a beam from a wireless power-supplying device towards at least one power-receiving device, said method comprising: (a) scanning a field of view for detection of imaging data arising from at least one sign having at least one asymmetric property, associated with at least one power-receiving device; (b) performing a sign-matching algorithm which maps onto said imaging data at least one representation of a sign obtained from a database containing representations of signs associated with at least one power-receiving device, said signs having at least one asymmetric property, wherein, said mapping is performed using a match between a representation of a sign contained in said database and a portion of said data; (c) using said mapping to confirm that a beam directed from a scan pose, at which said imaging data was obtained, did not undergo a reflection, such that a direct line of sight between said power-receiving device and said wireless power-supplying device is indicated; and (d) performing at least one of (i) directing at least one beam towards said at least one power receiving device; and (ii) modifying an operational parameter of said wireless power-supplying device.

2. The method according to claim 1 wherein said sign-matching algorithm is additionally performed by mapping at least one of: (i) a mirror image, (ii) a rotation, and (iii) a zoom operation of said detected image onto any of said representations of asymmetric signs contained in said database.

3. The method according to claim 2 wherein said modifying of operational parameters includes preventing wireless power supply if said mirror image of said detected image maps onto any representations of signs contained in said database.

4. The method according to claim 1 wherein step (d) of claim 1 is only performed if said sign-mapping algorithm determines that said detected image is not representative of a mirror image of a sign contained in said database.

5. The method according to claim 1 wherein at least one of (i) the position, (ii) the orientation, and (iii) the co-ordinates in space of the receiver is determined by at least one of said detected sign and said scan pose.

6. The method according to claim 1, wherein at least one sign is at least one of (i) attached to at least one receiver, (ii) embedded within a receiver, (iii) has a fixed position relative to at least one receiver, and (iv) contains information regarding the location of at least one receiver.

7. The method according to claim 1 wherein said scanning is performed by steering a beam emitted by said wireless power-supplying device, such that said beam reflected off said at least one sign travels in the reverse direction as that of said scanning beam, from said wireless power-receiving device to said wireless power-supplying device.

8. A system for safe wireless power supply to at least one receiver, said system comprising: (a) a transmitter adapted to emit wireless power; (b) a detector adapted to detect data in a field of view; and (c) at least one controller, said at least one controller adapted to: (i) receive signals from said detector; (ii) access a database containing one or more representations of signs associated with at least one receiver, said signs having at least one asymmetric property; (iii) execute a sign-matching algorithm which maps at least one of said representations onto said detected data; (iv) determine that at least a portion of said detected data matches at least one representation of a sign contained in said database; and (v) perform at least one of (i) instructing said transmitter to direct at least one beam towards said at least one power receiving device, and (ii) modifying an operational parameter of said wireless power-supplying device.

9. The system according to claim 8 wherein said determining by said controller indicates that a beam directed in said pose did not undergo a reflection, such that a direct line of sight between said at least one receiver and said transmitter is indicated.

10. The system according to claim 8 wherein said system further comprises a scanner adapted to scan a field of view for detection of said at least one sign.

11. The system according to claim 8 wherein said transmitter comprises a scanning mirror, such that said transmitter is adapted to scan said field of view with a beam of said wireless power, such that said beam is reflected off said at least one sign and travels in the reverse direction as that of said scanning beam.

12. A system for transmitting optical wireless power from a transmitter to at least one receiver, said system comprising: at least one transmitter adapted to emit a beam of said optical wireless power, said at least one transmitter being configured to direct said beam towards said at least one receiver, and said at least one receiver being adapted to convert said beam into electrical energy; and a sign identification system associated with said at least one transmitter, said sign-identification system adapted to identify signs associated with said at least one receiver, wherein said sign identification system is adapted to distinguish an image of at least one sign from a mirror image of said at least one sign.

13. The system according to claim 12 wherein said mirror image is distinguishable from an image of said sign even after at least one of (i) rotation of any magnitude about an axis perpendicular to the plane of the sign, (ii) rotation of less than 90° about an axis in the plane of the sign, (iii) magnification or reduction of said image, (iv) rotation of said image, and (v) after a zoom operation on said image.

14. The system according to claim 12, wherein said sign identification system comprises at least one sensor essentially aligned to said beam.

15. The system according to claim 12 wherein at least one sign is at least one of (i) attached to at least one receiver, (ii) embedded within a receiver, (iii) has a fixed position relative to at least one receiver, or (iv) contains information regarding the location of at least one receiver.

16. The system according to claim 12, wherein said sign-identification system is adapted to execute a sign-matching algorithm which maps at least one item from a database containing one or more representations of signs onto said at least one detected sign, said signs being associated with at least one power-receiving device and having at least one asymmetric property.

17. A system for providing information to a wireless power supply system, comprising: a sign having symmetry properties such that an image of said sign generated by either (i) a direct reflection from said sign to said wireless power supply system or (ii) a direct emission from said sign to said wireless power supply system, is distinguishable from a mirror image of said sign, wherein said wireless power system comprises at least one sensor for detecting said sign, such that said system can determine whether said detected sign was acquired through a direct line of sight from said optical sign or whether said detected sign was obtained by a reflection in the laser beam path.

18. The system according to claim 17 wherein said wireless power supply system is provided with instructions to adjust its operational parameters according to the information provided by said detection of said optical sign.

19. The system according to claim 18 wherein said provision of instructions comprises pre-encoded instructions, instructions received from a database, instructions received over a network, or instructions received through a wired connection.

20. The system according to claim 17 wherein said sign is at least one of optical, electric, or electromagnetic.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0136] The present invention will be understood and appreciated more fully from the following detailed description, taken in conjunction with the drawings in which:

[0137] FIG. 1A shows a schematic illustration of a prior art power transmission system with a beam impinging on a reflective surface and being detected by the sensor system;

[0138] FIG. 1B shows a schematic illustration of the situation shown in FIG. 1A, but incorporating a system according to the current disclosure, differentiating between an image of a receiver being displayed by a reflective surface and an image of an actual receiver viewed directly;

[0139] FIG. 2 shows a typical layout of a room with a transmitter covering the entire room, with several zones marked in the room, including the corners of zones, for defining, for instance, areas to which transmission is allowed, or prohibited;

[0140] FIGS. 3A to 3C show a number of examples of signs which are symmetric, and thus not useable for the novel systems of the present disclosure;

[0141] FIGS. 3D shows an asymmetric sign, used, to determine whether an image received of the sign, is an image directly received, or a mirror image of the sign, received after a reflection;

[0142] FIGS. 3E to 3J show various images of the letter F, as an example, to illustrate the concept of a mirror image of an object;

[0143] FIG. 4 illustrates a single sign showing the position of more than one receiver, or more than one target on a single receiver;

[0144] FIG. 5 shows a transmitter equipped with a number of sensors for detection and identification of signs such as those shown hereinabove;

[0145] FIG. 6 shows a sign which is an integral part of a receiver, is asymmetric, embedded into the receiver and is at a fixed position relative to the photovoltaic cell:

[0146] FIG. 7 shows a bar code, which is one example of a high contrast sign which may encode information; and

[0147] FIG. 8 illustrates a typical structure of the systems described in this disclosure.

DETAILED DESCRIPTION

[0148] Reference is first made to FIG. 1A, which schematically illustrates an exemplary prior art system for transmitting optical power to a hand-held portable device, in which the transmitter can mistakenly identify an incorrect receiver location because of a reflection of the beam in a reflective surface, such as a mirror or a window, increasing the risk of damage to people or sensitive equipment.

[0149] In FIG. 1A, a receiver 10 held by the user 14 is located within the transmitter's 11 field of view. However, the transmitter 11 has located an image 16 of the receiver 10 from the reflection of the receiver itself 10 in the window 13, and has thus been given permission by the system to transmit a power beam 12 to the supposedly identified “receiver” 16, believing it to be the real receiver. As the window transmits over 90% of the incident beam, this high power travels beyond the window 15, and may cause damage to a person 15 passing by, or to sensitive equipment situated along the beam path outside of the window 13.

[0150] Furthermore, damage to the partially reflective window surface 13 may occur, as it may not be able to handle such a large power level, and may therefore be damaged, causing diffused scattering of the power beam, or may even break, though in that case, the reflected beam back to the sensor would disappear, causing cessation of power transmission and a return to the scanning mode. The transmitter may also mistakenly direct a beam at a reflective flammable surface, increasing the risk of fire-related damage.

[0151] Furthermore, in systems where multiple transmitters are used, a reflected beam may intersect a beam emitted by a different transmitter, even in systems where direct intersection would be prevented. This may have unintended and even dangerous consequences, as the combined beam may be more powerful than safety requirements allow. Furthermore, should a beam mistakenly be directed onto an unintended surface, the surface may diffuse the beam, causing the beam to be scattered around the room. Alternatively, a surface may split the beam into random directions, causing unintended damage to sensitive objects or equipment.

[0152] Thus, any reflective surface, whether fully reflective or only partially reflective, such as mirrors, irises of humans, animals and cameras, glass surfaces, metallic surface and sensitive equipment, among other examples, could present a hazardous situation should a beam be mistakenly directed onto them.

[0153] Reference is now made to FIG. 1B, which illustrates schematically an advantageous exemplary system in which a transmitter is able to correctly distinguish between light reflected or received from an actual receiver location, from light received from a virtual image of the receiver, generating false receiver locations.

[0154] In the embodiment shown in FIG. 1B, receiver 10 is equipped with sign 17a, which has an asymmetric shape, which makes it distinguishable from its mirror image, regardless of how the image of the shape is rotated, tilted, magnified, reduced, or cropped. When transmitter 11 detects an image of the reflection of sign 17a, shown as shape 17b in the reflective window pane 13, the image processing routines of the system determine that the image 17b being detected, cannot be matched to any of the acceptable image shapes expected from a real receiver, and correctly identifies that no actual receiver is located in that position. The system may do so by comparing the identified image with a database of signs, rotating and/or magnifying and/or tilting, and/or cropping the image received.

[0155] Alternatively, the transmitter may calculate the hash or another representation of the received image, based on a pre-determined algorithm. A database may contain representations of signs, in the form of digital signatures, hashes, numeric values associated with co-ordinates or other data representing geometric properties of the signs. If the image received by the transmitter is an image of a sign which has been reflected, then no match would be found by the sign-matching algorithm, as the sign is asymmetric, and thus a representation of its mirror image would not be present in a database of safe signs.

[0156] The transmitter thus ignores the reflected image of the sign 17b, preventing unsafe transmission to the image 17b from the reflective surface 13. The transmitter should correctly identify sign 17a as an actual location of a receiver, having a direct line of sight with the transmitter 11, and thus may direct beam 12 directly onto receiver 10.

[0157] Reference is now made to FIG. 2 which illustrates how recognizable signs may be used to delineate areas being preferred or forbidden for power transmission. FIG. 2 shows a typical plan layout of a room with a transmitter 23 intended to cover the entire room. Several different zones are marked in the room. In this example, there are shown two charging zones, 22B, 22C, and one non-charging zone 22A, each zone of which may be marked with one or more signs, either within the area of the zone or to define its extremities, borders or corners.

[0158] Thus, zone 22A is shown having sign 24A located in the center of the zone. Zone 22A is a non-charging zone, which may represent a sleeping area, a storage area, or an area in which receivers are not usually located, among other examples. The transmitter may identify the area of a zone by identification of a sign, and/or the extent or perimeter of a zone may be associated with the sign, thus signifying to the transmitter that on detecting such a sign, it should modify its transmission accordingly.

[0159] Zone 22B illustrates a charging zone, in which all four corners are identifiable to the transmitter using signs 24B, 25B, 26B and 27B. This is to illustrate an embodiment in which the transmitter identifies a zone by obtaining an image of more than one sign associated with a single zone, and thus can compute the area of that zone, or delineate the parameters and perimeter of the zone based on the location of these signs.

[0160] Zone 22C is shown as a charging zone, which may represent a conference room, office, dining room, or a room in which receivers are often located. Signs may represent the anticipated frequency of receivers located within the room, and/or the expected pattern or set-up in which receivers may be positioned within the zone. For example, a sign may represent a conference room with information regarding where expected receivers will be situated, for example at specific places at a table.

[0161] Zones may be marked by a single sign indicating a center of a circular, elliptic or square zone, of specific size or angular size. It should be noted that signs may represent corners, such as sign 24C, but also other types of closed shapes. Another implementation disclosed may be of two or more signs used to delineate the perimeter or area of a charging zone. When discussing polygons in the context of this disclosure, any other closed shaped in 2- or 3-dimensions may be used, such as shapes with various types of rounded corners or other non-sharp corners and bends. Similarly, when the word corner is used, it may refer to a rounded corner or any other distinct bend in the periphery of the shape.

[0162] Reference is now made to FIGS. 3A-3J, showing exemplary geometric properties of signs.

[0163] A sign shaped like a circle, as a simplified example, shown in FIG. 3A would provide the transmitter with one unit of size (its diameter) and one dimension of angular position in space, which is the direction perpendicular to its surface, shown as a black arrow.

[0164] A sign shaped like an arrow, as another simplified example, shown in FIG. 3B, would provide the transmitter with units of size (length, width, size of the tip) and typically two or three directions, shown as black arrow heads in FIG. 3B.

[0165] A simplified arrow, shown in FIG. 3C, consisting of lines but not surfaces, may be another useful implementation of such signs, although such a shape usually has low detection visibility, limiting its usefulness.

[0166] Such shapes allow the identification of the position of the target, relative to the sign. However, none of the above shapes shown in FIGS. 3A, 3B and 3C are asymmetric, since a circle is indistinguishable from its mirror image, and an arrow is indistinguishable from its rotated mirror image. Therefore, a transmitter would be unable to distinguish the mirror image of these signs received after the beam has undergone a reflection, from an image received directly from such a sign.

[0167] Reference is now made to FIG. 3D, which illustrates an exemplary asymmetric sign 33 disposed on a receiver, and indicating by its position and direction, where the photocell 31 is situated on the receiver. The asymmetric sign 33 is distinguishable from its mirror image. Such a sign allows the system to determine whether the sign is being viewed directly, or after reflection in a mirror.

[0168] With regard to asymmetrically shapes, it should be noted that many two-dimensional shapes, including the shape shown in FIG. 3D, if rotated in up to three dimensions, may be identical to their mirror image, depending on the direction from which they are viewed. This would be so if the shape were viewed from the opposite side of the plane of the drawing of FIG. 3D, i.e. if viewed through the material which comprises the sign. However, since such shapes, in the practical implementations of this disclosure, where the signs are typically affixed to a surface such that there is no access to the back-side of the sign, and in which the signs are viewed using a camera or a sensing system having a fixed field of view, which images the sign from only one side of the plane in which the sign is situated, shapes such as FIG. 3D, can be considered to be fully asymmetric within the context of this disclosure. The type of asymmetric sign shown in FIG. 3D could be used by the system to determine whether an image received of it is an image directly received from the sign, or a mirror image of the sign.

[0169] Reference is now made to FIGS. 3E to 3J, which show various images of the letter F, as an example, to illustrate the concept of a mirror image of a sign, as used and as claimed in the present disclosure.

[0170] The original, non-reflected image of the sign is the shape of an upright capital letter “F”, as shown in FIG. 3E. The comparison of a received image with a representation of the original sign, object or pattern being imaged, may need to be performed after first executing any or all of rotations, tilts and magnification operations on the image as required, before comparison with a direct image of the original sign pattern, or a cropped direct image of the original sign pattern. The rotations can be performed in one or more of the three co-ordinate axes of the three dimensional image.

[0171] An image of a sign detected may need a simple 90° rotation round the axis projecting out of the plane of the image to bring the image into the correct rotational orientation in a 2-dimensional field of view. In addition, only lateral magnification may be needed to attain the original upright letter “F”, i.e. the original sign pattern.

[0172] In FIG. 3F, tilt, rotation, and magnification would be required to match the image to its original pattern. Thus, the image may need to be tilted until it appears on a plane parallel to the compared source image of the letter F, then rotated till it is upright, then increased in size until its dimensions match the pattern, during the comparison procedure with the original upright letter “F”, i.e. the original sign pattern shown in FIG. 3E.

[0173] In FIG. 3G, rotation, tilt and also possibly magnification may be required to fit the original upright letter “F”, i.e. the original sign pattern.

[0174] In FIG. 3H, besides the three operations previously described, cropping of the original pattern from the database may be required during the comparison procedure.

[0175] All of the above representations of the letter F may result in an exact match to the original pattern of the source upright letter “F”.

[0176] On the other hand, with regard to the images shown in FIGS. 3I and 3J, it is clear that no rotation, tilt or magnification performed on those images would give the original upright letter “F” as the images in FIGS. 3I and 3J are mirror images of the original letter F, and therefore the image would need to be reversed in order to attain the original upright letter “F”.

[0177] A sign may consist of an asymmetric pattern that may be found in proximity to the target to be illuminated. The sign may also comprise a symmetric pattern that differs from its mirror image, such as a Friese pattern or other repetitive patterns. The direction and distance from a point on the sign to the receiver, or more specifically, to the PV cell located within the receiver, should be known to the transmitter, either from an external source, or it may be encoded on the pattern itself, most conveniently by using a barcode.

[0178] The sign typically allows the transmitter to determine at least one, and preferably more than one, direction and size that allows the transmitter to estimate the location of the receiver. The sign typically allows the transmitter to determine at least one, and preferably more than one, direction and distance that allow the transmitter to determine the location of the receiver with which the sign is associated. For example, a sign may indicate that a target is 30 mm from it, and in a certain predefined direction. The system may also determine the expected size for a sign of this shape, for instance, 5×5 mm, in order to confirm identification and distance from the transmitter. This information may be found, for example, by looking it up in a database, or by encoding data from the sign itself. The sign may be viewed by the transmitter from different ranges, resulting in different sizes of the sign on the transmitter's imaging device. However, the exact position of the target may be calculated by determining the coordinate system of the sign i.e. its forward, left/right, and up/down directions, which may be performed by determining the amount of tilt requires to decode the image, and its size, which may be determined by the amount of zoom required to decode the image. Then, once the direction of the sign is known, and the extent and direction of the correct step to take to reach the target on the receiver is known, the position of the target may be easily calculated.

[0179] According to another implementation, as shown in FIG. 4, a single sign 43 may represent the position of more than one receiver 41 and 42, or more than one photocell on a single receiver. One transmitter may accordingly direct two beams towards the receivers, which are at known distances from the sign, or two transmitters may be used to emit two beams to the receivers associated with such a sign. It should be clear that a sign may represent multiple receivers and their locations, or signs may represent just a single receiver.

[0180] Signs may include other types of information such as:

[0181] The make and model of the receivers, power capabilities, power needs, identification, contact address and other types of information.

[0182] Reference is now made to FIG. 5 which shows a transmitter 51 equipped with a number of sensors 53 for detection and identification of such signs 55. Each one of such sensors may identify at least a portion of the data encoded within the sign 55, and typically transfers it to a controller 52, or CPU which interprets the data and may act accordingly.

[0183] One sensor may be enough in most applications, however, having more than one sensor reduces the chances of false detection and generally improves detectability of the signs. Alternatively, each sensor may detect the same portion of a sign and compare results for redundancy.

[0184] Sensors are part of the wireless power supply system, and may be connected to the transmitter by being embedded within it, or with a wireless or a hard-wire connection, and/or both having a common controller or other device.

[0185] The receiver sign area must be at least

[00003]$\frac{10^{-8}{\mathrm{meter}}^2}{\mathrm{number}\mathrm{of}\mathrm{Tx}\mathrm{sensors}}$

and hence increasing the number of sensors allows a reduction in the required size of the sign associated with a receiver or increased detectability. Good detectability is typically achieved, if the area of the sign is increased, to be, for instance, greater than

[00004]$\frac{10^{-8}{\mathrm{meter}}^2}{\mathrm{number}\mathrm{of}\mathrm{Tx}\mathrm{sensors}}$

[0186] or even greater than

[00005]$\frac{10^{-8}{\mathrm{meter}}^2}{\mathrm{number}\mathrm{of}\mathrm{Tx}\mathrm{sensors}}$

in some extreme cases.

[0187] Use of the larger sized signs enables the scan time to be reduced significantly, and facilitates the application of the signs in applications where the user applies them, such as to mark the boundaries of a region to which power transmission is forbidden, such as for instance, a baby's crib. In mobile devices, such as cellular telephones, the design can be made such that the smaller sized signs can be used.

[0188] The transmitter typically collects information from the sign for a time period t, that is at least:

[00006]$t>\frac{4*\left(\mathrm{sensor}\mathrm{rise}\mathrm{time}+s\mathrm{ensor}\mathrm{fall}\mathrm{time}\right)}{\left[\mathrm{Number}\mathrm{of}\mathrm{sensors}\right]*{\log }_2\left(1+\frac{\mathrm{RMS}{\mathrm{signal}}_{\mathrm{on}\mathrm{sign}}}{\mathrm{RMS}{\mathrm{signal}}_{\mathrm{not}\mathrm{on}\mathrm{sign}}}\right)}$

[0189] or in an equivalent expression using log10 values or, in its log10 form

[00007]$t>\frac{1.2*\left(\mathrm{sensor}\mathrm{rise}\mathrm{time}+s\mathrm{ensor}\mathrm{fall}\mathrm{time}\right)}{\left[\mathrm{Number}\mathrm{of}\mathrm{sensors}\right]*{\log }_2\left(1+\frac{\mathrm{RMS}{\mathrm{signal}}_{\mathrm{on}\mathrm{sign}}}{\mathrm{RMS}{\mathrm{signal}}_{\mathrm{not}\mathrm{on}\mathrm{sign}}}\right)}$

[0190] where the sensor rise time is the shortest time the output of any of the sensors change by at least 20%, and preferably 50-90%, between the output value generated when the system is not aimed on a sign, and the output value generated when the system is aimed at a sign.

[0191] The sensor fall time is the shortest time the output of any of the sensors change by at least 20%, and preferably 50-90%, between the output value generated when the system is aimed on a sign, and the output value generated when the system is not aimed at a sign.

[0192] The value [RMS signal.sub.on sign] is the maximal RMS of the signal, generated by any sensor, when the system is aimed at a sign, or at a portion of it.

[0193] The value [RMS signal.sub.not on sign] is the minimal RMS of the signal, generated by any sensor, when the system is not aimed on a sign (typically averaged over an environment).

[0194] After the signal is integrated and collected over that time t or more, the transmitter is configured to decide if a sign is an instruction or an information sign and to interpret its content, or if it is an invalid sign.

[0195] Reference is now made to FIG. 6 which shows a sign 63, the sign being asymmetric and embedded into the receiver 61. The sign is at a fixed position relative to the photovoltaic cell, which may be the target for the beam emitted by the transmitter. Such a sign allows for positive identification of the receiver as a valid receiver.

[0196] Reference is now made to FIG. 7, which shows a bar code, which is one example of a high contrast sign which may encode information. According to one typical convention used in this disclosure, the term high contrast is understood to mean that the RMS signal when the sensor views a portion of the sign, is at least 1.3X greater than the RMS signal when the sensor views “no sign”.

[0197] The term [RMS signal.sub.on the sign] is the maximal RMS of the signal, generated by any sensor, when the system is aimed at a sign or a portion of it.

[0198] The term [RMS signal.sub.not on the sign] is the minimal RMS of the signal, sign, generated by any sensor, when the system is aimed not on a sign (typically averaged over an environment)

[0199] Reference is now made to FIG. 8 which shows a typical exemplary structure of the systems of the type described in this disclosure. A beam emitter 82 emits a beam 85 that is directed towards a receiver 86 using a beam steering device 80. A sign 87 is located either on/in the receiver, or associated with the position of the receiver. The source of the sign, or the sign itself may consist of an RF emitter, a light emitter, a light reflector, a light retro reflector, or an ultrasound emitter.

[0200] In the case where the transmitter scans the room with a beam 85 to identify receivers, a signal emitted 88 from the sign 87, or an image of the sign caused by the incident beam reflecting off the sign, travels in the reverse direction 88 as the search beam, from the receiver 86 to the transmitter 81, where it is typically separated from the transmitted beam using a beam splitter 83, and is then directed towards a detector or detectors 84. The signal is designed to enable identification of the position of the receiver, and to confirm that the receiver is a valid receiver. The transmitter should first identify the signal emitted by the sign positively, before emitting a beam to begin wireless power supply. After positive identification of a sign, the risk of lasing towards a sensitive object is significantly reduced. In some instances, the transmitter may then direct a beam towards an identified receiver and thus safe wireless power transmission is ensured.

[0201] 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 subcombinations 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.