System for wireless power transmission - Patents.com

Abstract

To provide a laser-based transmission system for beaming optical power to a mobile electronic device in a home environment.SOLUTION: An optical power transmission system to a receiver 22 incorporating a safety system 31 includes an optical cavity (rear mirror 10 and output coupler 9) with multiple end reflectors 14 and gain medium 11, a driver 12 that supplies power to the gain medium to control its small-signal gain, a beam steering device 14, and a controller 13 that controls at least the beam steering device and the driver. The controller outputs a command to change at least some of the small-signal gain of the gain medium, the radiance of a light beam, the power supplied by the driver, the scan speed or scan direction and position of the beam steering device or a command to register scan poses that define the placement of an optical / power converter, thereby responding to safety risks. The controller also ensures high radiance efficiency and warns that the target receiver does not receive transmitted power.SELECTED DRAWING: Figure 19

Description

[Technical field]

[0001] The present invention relates to the field of wireless power beaming, particularly as it applies in the domestic environment. US201002233633A1 - Use of a laser-based transmission system to beam optical power to a mobile electronic device - Google Patents Regarding. [Background technology]

[0002] The long-standing goal of transmitting power to remote locations without the need for a physical wired connection There is a compelling need to develop new ways to power electronic devices that operate with batteries that require periodic recharging. This has become important over the past few decades as portable electronic devices that support wireless connectivity have become more common. Such mobile applications include mobile phones, laptops, cars, toys, Currently, the capacity of state-of-the-art batteries and smart Typical battery usage in a smartphone would require charging the battery once a day. Therefore, the need for remote wireless battery recharging becomes important.

[0003] Battery technology has a long history and is still in development. Ranklin was the inventor of the first battery, the first electric cell, made from a Leyden jar. This was similar to a cannon battery (hence the battery In the late 1800s, Volta invented the copper-zinc battery, which The first rechargeable batteries, the lead acid batteries, were produced in the 18 It was invented by Gaston Plante in 1959. Since then, the energy of rechargeable batteries has The increase in density is due to the variety of chemistries from the original lead-acid chemistry to the current lithium-based and zinc-air chemistries. The energy density of a rechargeable battery is expressed in terms of both gravimetric and volumetric parameters. As can be seen in Figure 1, the increase in power consumption by portable electronic / electrical devices is less than 8 times. The power consumed has reached a point where several full battery charges need to be replenished each day. There are.

[0004] Almost a century after the invention of the battery, between 1870 and 1910, Attempts were made to transmit power over long distances using electromagnetic waves. can be safely transmitted to a remote location that may be characterized as spanning a significantly greater distance than the receiving device. Many attempts have been made to transmit power, beginning with the SHARP (Static Power Amplifier) ​​in the 1980s. Stationary High Altitude Relay Platform From NASA, which led the Relay Platform project, in 2007 The research ranges from Marin Soljacic, who experimented with a system similar to Tesla's do.

[0005] Still, so far there are few technologies that allow wireless power transfer to mobile devices. There are only three commercially available technologies that can achieve this: Magnetic induction...this is typically limited to a range of just a few mm. Photovoltaic cells: This is the level available in sunlight or in a room with normal (safe) lighting. When illuminated by any of the following artificial light sources, for sizes relevant to mobile phones, the It cannot generate more than 1 watt of power. Energy harvesting technology: This converts RF waves into usable energy. , in current practical situations, it cannot operate above 0.01 W. RF signal transmissions are limited due to health and Federal Communications Commission (FCC) regulations. On the other hand, a typical battery in a portable electronic device has a capacity of 1 to 100 watt-hours, providing daily Typically they require charging, hence the fairly high power transfer over a fairly long range. Delivery is required.

[0006] Thus, the broader perspective extends to portable electronic devices, which typically include rechargeable batteries. The unmet need to safely transfer power over fields and ranges greater than a few meters There is a need for

[0007] Using collimated or essentially collimated electromagnetic waves, especially laser beams There have been some attempts to transfer power in residential environments. The mass market commercial availability of such products is currently limited. Before a commercial system can be launched, several issues need to be resolved: A secure system should be developed. A cost-effective system should be developed. Contamination such as dust and fingerprints or liquid spills, vibration, beam obstruction, non-professional installation A system that can withstand normal household hazards, including placement on the floor and occasional drops to the floor. The system should be developed to

[0008] Currently permitted transmit laser power levels are such that useful amounts of power can be produced without complex safety systems. For example, in the United States, the April 2014 revised Federal Regulations 21 CFR Part 8, Chapter I, Subchapter J Part 1040 deals with performance standards for light emitting products, including laser products. There are Class I, Class III-b and Class IV lasers (Class II, II IIIa and IIIa are lasers of 400 nm to 710 nm, for example visible lasers. For lasers outside the range, Class 1 is considered safe for general public use, while Class IIIb and IV are considered dangerous.

[0009] Reference is now made to Figure 2, which shows the results for exposures from 0.1 to 60 seconds in accordance with 21 CFR section 14. Maximum Permissible Exposure (MPE) for Class I lasers according to the 8th Amplification Standard for a pupil diameter of 7 mm A graph showing the actual permissible exposure value (IPR) From the above graph, we can see that: (i) the maximum permissible exposure level is generally (but (ii) increases with wavelength, as provided for in 21 CFR sec. 8; To meet the requirements set forth in the IEC 61010-1, the laser is turned off 0.1 seconds after a person enters the beam. At wavelengths longer than 2.5μ, no more than 1.25W of light can be transmitted. That is, without some kind of safety system, the limit is only a few millimeters. Watts of laser power can be transmitted, which, even if fully converted back to electricity, is almost This provides significantly less power than is required to charge a portable electronic device. For example, cellular phones require between 1 and 12 W to charge, depending on the model.

[0010] Transmitting powers higher than the Class 1 laser MPE requires a safety system. Transmitting significant levels of power in residential environments accessible to untrained persons To the applicant's knowledge, it has not yet been commercially released.

[0011] It is difficult to build a transmission system with a robust safety system. The detection level is very small compared to the power that needs to be transmitted and the system will operate The environment is not controlled and many unpredictable scenarios can occur during operation.

[0012] Fingerprints and dust scatter laser light, and transparent surfaces reflect or scatter that light. It is well known in the industry that when high power is transferred, a reliable safety system must be in place. A Class IV (or IIIb) laser is required. For Class IV lasers: Even scattered radiation from the main beam can be dangerous. 21 CFR revised in April 2014 According to Section 8, Chapter I, Subchapter J, Part 1040, the 0.5W beam Laser radiation from 400 nm to 1400 nm, exceeding the laser output, is typically used for exposures longer than 0.5 seconds. are considered Class IV lasers and even scattered radiation from such lasers can be dangerous. Such lasers should have a locking key and warning signs similar to those shown in FIG. Here, the warning also relates to "scattered radiation" and users of the laser should They must always wear safety goggles and are typically trained professionals. All of these aspects are part of a laser power transmission system that can be used in the home to charge mobile electronic devices. This is very far from acceptable conditions for stem use.

[0013] The prior art typically provides anti-reflection coatings on surfaces that prevent such reflections. However, in the unlikely event that reflection does occur, a film is installed to prevent such reflection. However, in the prior art, The AR film solution used may be damaged by dust or spilled liquids that accumulate on its surface, or They are prone to failure due to wear and tear, for example due to improper cleaning. Well, beam-blocking solutions typically severely limit the system's field of view, making them incompatible with modern mobile devices. However, it is bulky compared to the dimensions of conventional electronic devices.

[0014] Thus, the prior art does not provide a method for preventing the power beam from scattering and reflecting in undesired directions. There is a lack of a reliable "small footprint" mechanism to prevent such scattering and Reflections can be caused by a transparent surface inadvertently placed between the transmitter and receiver. Since the optical characteristics of the transparent surface can be influenced by a huge number of different transparent materials, Liquid spills and fingerprints that may accumulate on the external surfaces of the system, typically the front of the receiver. It can be affected.

[0015] A third problem with the solutions proposed in the prior art is that such safety systems generally: The need for a mechanism to ensure good alignment of the power beam system with the safety system Both systems are then powered so that safety limits are no longer exceeded. The force beam is sufficiently dissipated or sufficiently attenuated (or these and any other factors combined). Combination) are aimed on the same axis. This means that the distance is almost Collimated clusters typically do not provide sufficient coverage and therefore exceed safety limits even at very long distances. This is extremely difficult to achieve for Class IV or IIIb laser beams.

[0016] One operating principle of the prior art used to build such a safety system is The objective of the present invention is to optically detect a transparent surface that can be positioned in the path of the beam. Transparent surfaces that can enter the road are made from a huge number of different transparent materials and have anti-reflective AR coatings. Almost for optical systems unless the material is coated or absorbs the beam. They are placed at angles close to Brewster's angle so that they are invisible. However, Since the light absorption levels of materials are different and can even be neglected, optical systems that rely on light absorption Constructing a 3D 3D stencil is highly material-specific, and the number of materials available is extremely large. Therefore, such systems tend to be complex, large, expensive, and difficult to design properly. As far as possible, especially considering that it is intended to be a critical safety system, Relying on reflections to provide detectable attenuation of the beam is also problematic. The surface is coated with an anti-reflection coating or is at a near Brewster angle to the beam. When placed, reflections may be minimal for that particular location on the surface. be.

[0017] Another limitation of the prior art systems is the requirement for good beam quality (low m) to obtain high efficiency. 2 value) is large The use of a laser combined with a large optical system (for example, Patent Documents 1 and 2 disclose While the use of a wide aperture for the laser beam is typical, Patent Document 3 uses a small Uses 0.8μm wavelength to accommodate optics and reduce cost and size of optical systems do.

[0018] Accordingly, a combination is provided that overcomes at least some of the disadvantages of prior art systems and methods. A need exists for a laser power transmission system with built-in safety features.

[0019] The disclosure of each of the publications referred to in this and other sections of this specification is incorporated herein by reference. No. 6,399,433, which is incorporated herein by reference in its entirety. [Prior art documents] [Patent documents]

[0020] [Patent Document 1] U.S. Patent No. 6,407,535(B1) [Patent Document 2] US Patent No. 6534705 (B2) [Patent Document 3] U.S. Pat. No. 5,260,639 Summary of the Invention

[0021] One of the main challenges of wireless power transmission is to develop a system that is safe, low-cost, small, and powerful. By constructing transmitters and receivers that are capable of transmitting significant levels of power, To enable powerful yet small transmitters and receivers, the radiance of the beam must be should be kept as high as possible throughout the entire optical path, but especially at the output of the transmitter. Every component in the light path incurs a certain radiance loss. In this specification, the term radiant efficiency is used several times. Its usual meaning in this context is the amount of radiance going out of an optical component relative to that component. The ratio of the beam entering the component to the incident radiance. For each component, for example a mirror, can be tilted at different angles. There may be different radiation efficiencies for the

[0022] In general, the system as a whole should have as high a radiation efficiency as possible, with 60% being the minimum. One should strive to obtain typical values ​​of radiation efficiency exceeding 90% or even 95%.

[0023] The radiation efficiency of the transmitter is generally much more important than that of the receiver. There are two main factors that reduce radiance: the laser system and the transmission. Besides these factors, other small factors also have an effect.

[0024] Lasers with high radiance values ​​are generally large and complex, while lasers with low radiance are generally large and complex. Lasers that perform these functions are typically small and simple. Current systems offer improved safety features. Laser radiance is limited because they typically use rare wavelengths that allow Small, low-cost, high-radiance lasers at unconventional wavelengths are not as commonly available. These techniques tend to increase the cost of the system rather than improve its functionality.

[0025] Prior art systems such as those disclosed in US Pat. Nos. 5,993,333 and 5,943,633 allow compact transmitters and receivers. To accommodate this, shorter wavelengths (0.8 μm or 0.532 μm) are used. Because the system utilizes longer wavelengths, different methods are needed to reduce the size of the system. must be used.

[0026] The longer wavelengths used by current systems are disclosed in commonly owned U.S. patent application Ser. As explained in 14 / 811,260, virtually all plastic materials By using specifically absorbed wavelengths, transparent plastics in the path of the beam This allows detection of the problem.

[0027] Opaque or partially opaque materials, when placed in the beam, also However, some The materials are transparent or nearly transparent, making them significantly more difficult to detect. There are two main groups of solid transparent materials: organic and inorganic. The number of inorganic transparent solid materials available to the general public is quite limited. Glass, some commonly used semiconductor materials, quartz, as well as diamond, ruby, It is therefore made up of inorganic transparent materials and some naturally occurring minerals such as quartz and calcite. A detection system for reflections can be built to cover all similar scenarios. .

[0028] On the other hand, the availability to the general public of different organic transparent materials is enormous. Transparent materials are being added to the list all the time. This is a major issue. This is because it becomes virtually impossible to characterize scientifically.

[0029] Polymers are an important group of transparent organic materials with which the present invention is intended to operate. These polymers are typically used as a sample group to help illustrate the aspects of They consist of long chain monomers. The backbone of such polymers is typically either carbon or silicon. Figures 4 to 9 show the chemical structures of some commonly used transparent polymers. Figure 4 shows a polymethyl methacrylate (PMMA) chain. Figure 5 shows the structure of polycarbonate. Figure 6 shows the structure of polystyrene. Figure 7 shows the structure of nylon 6,6. Figure 8 shows the structure of polypropylene. Figure 9 shows the polyethylene chain structure.

[0030] As can be observed, the chemical structures of the sample polymers shown are very different. The absorption spectrum of a polymer can determine many things, including the density of the material, trace amounts of reagents, and chain length. Nevertheless, all of the above transparent polymers have some common In particular, the C—C and C—H bonds are present in the commercially available For almost entirely organic polymers that may be detected by the disclosed system, Silicones, polysilanes, polygermanes that may be detected by the disclosed system and semi-organosilicon-based polymers such as polystannanes or polyphosphazenes. This applies to:

[0031] Separately, there are transparent materials available to the general public that are not based on carbon chemistry (most of them are The number of optical fibers (made of various glasses) is quite limited. Most of them have has readily available data on

[0032] Either the vibrational CH or possibly the C-C bonds in the polymer are excited by the laser. If the system is designed to be activated, one of these polymers can be inserted into the beam. Monitoring the power drop caused by the polymer when positioning This makes it easy to detect because there is always absorption of a CH or CC bond. It is assumed that the wavelength will match the laser wavelength. Rotational peaks are also used for this purpose. can be used, but rotational peaks are unreliable in polymers and should not be used for this purpose. For this purpose, vibrational CH (or CC) absorption is well suited.

[0033] Reference is now made to FIG. 10, which shows a chart of typical absorption areas for different polymer linkages. Almost all of the polymers shown have a peak at 2900-3200 cm -1 CH stretch vibration near It is observed that the transmission power variation obtained from the absorption band appears. However, it can be used to trigger an absorption mechanism for a safety system that uses There are two problems with these absorption bands that prevent them from being useful for this purpose. do.

[0034] (i) CH vibrational absorption lines are typically very steep and their exact frequencies are unknown in polymers. The laser excites one polymer without exciting the other. That is, the laser can be precisely tuned to the specific CH vibration line of the polymer. It will not be absorbed unless it is absorbed. (ii) Such CH vibration peaks are generally limited by the thickness of the beam due to the material section being several mm thick. Attenuation is 20-50% (i.e. even trace amounts of material in small containers can be detected) It is a moderate absorption peak, which means that it is possible to The absorption peaks in intensity (>70% attenuation per cm) and intensity (>70% attenuation per cm) are generally quite Being easily detected, these absorption peaks can be used to create a robust system. It cannot be used.

[0035] Fingerprints are a common problem in commercial systems designed for consumer environments. In normal operation, the system should not fail simply because of the deposition of a fingerprint. Instead, the system shuts down transmissions if there is a risk of exceeding safety limits. To do this, the system should detect the blocking of the beam, but , the receiver should not stop transmitting due to any fingerprints deposited on it. If an absorption peak of this order is used, in the unlikely event that fingerprints or other marks are present on the external optical surfaces of the receiver or transmitter, If any other contamination were to accumulate, the beam would be significantly absorbed, causing failure of power transmission. This occurs because the fingerprint absorbs the beam and causes uncontrolled system failure. This is because organic matter, such as fingerprints, typically contains organic compounds that are To enable the system to operate in an environment where deposition may occur on the surfaces of optical components. While the laser beam successfully traverses the fingerprint, there are also dangerous penetrating holes that can be inserted into the beam. It is necessary to construct a system in which the transparent object is detected by the safety system. If the system utilizes weak absorption bands instead of moderate or strong absorption bands, the system The system should also work with a fingerprint and shut off based on an electronic decision. Therefore, this does not result in poor control.

[0036] 800cm -1 From 1300cm -1 Looking at the CC absorption band that extends to is broad enough that a narrowband laser will almost certainly miss the narrowband absorption peak in this region. The peak is at 800 cm -1 ~1300cm -1 While it is located within the The typical width is so small that it is easily missed by a narrowband laser. In addition, as can be seen in Figure 11 below, this band is In this case, it disappears at 800 to 1300 cm -1 There is no visible absorption peak at C -C bonds are absent, and aromatic carbon-carbon bonds or C=C and COC bonds are present. There are several polymers that are substituted.

[0037] A further problem arises from the absorption strength of the CC lines. For some compounds, detection can be nearly impossible, while for other compounds, detection can be nearly impossible on the surface of the receiver. Even a weak fingerprint can be strong enough to render a system inoperable, so a significant portion of the power The fingerprint is absorbed and renders the device unusable. To enable the system to function, most organic A weak, but not too weak, absorption line found in polymers is required. Use a laser tuned to the peak with a system operating near that peak. As can be seen from Figure 10, commonly used polymers have There is no such peak in

[0038] A system for optical wireless power transmission to a power receiving device, comprising: (a) an optical resonator having end reflectors and adapted to emit a light beam; (b) a gain medium positioned within the optical cavity and having a first bandgap energy; a body thermally attached to a cooling system so as to amplify the light passing through it; A gain medium comprising: (c) a collimator lens that reduces the divergence of the light and has a high radiation efficiency (greater than 50%); (d) a driver that provides power to the gain medium to control the small signal gain of the gain medium; (e) a light source configured to direct a light beam in at least one of a plurality of directions, typically a high-emission a beam steering device having a beam efficiency (typically greater than 50%); (f) a second bandgap amplifier configured to convert the light beam into electrical power having a voltage; A light-to-electrical converter having a thickness that acts as an energy and an absorbing layer (typically a semiconductor). and, (g) converting one voltage of the power generated by the optical / electrical converter to a different voltage; a voltage converter adapted to the (h) a gain medium associated with the optical-to-electrical power converter and connected between the gain medium and the optical-to-electrical power converter; At least one optically arranged surface; (i) configured to provide a signal indicating that the light beam has impinged on the light-to-electrical power converter; a detector having a (j) A safety system that evaluates potential safety violations; and (k) controlling at least one of the status of the beam steering device and the driver; and a controller adapted to receive a control input signal from at least the detector. Including, (l) the at least one surface is: (i) in more than one direction; or (ii) the reflected light is: to have a virtual focus positioned remotely from the optical cavity relative to the surface. or (iii) the reflected light is at least 1 cm away from the surface in the direction of the optical cavity. and having the property of reflecting a small portion of incident light so as to have a real focal point located at (m) the controller (i) causes the driver to vary a small signal gain of the gain medium; (ii) modifying the radiance of the light beam; and (iii) by the driver. (iv) changing the scan speed of the beam steering device. (v) changing a scan position of the beam steering device; and (vi) adjusting the optical axis of the beam steering device. / recording a scan position that defines the position of the power converter; configured to respond to a control input signal received from the detector; (n) The gain medium is a semiconductor device or a solid-state host doped with Nd ions. 8,300cm -1 From 12,500cm -1 at least a filter for attenuating radiation for one frequency; (o) The thickness of the active semiconductor layer of the optical-to-electrical converter is such that it can absorb most of the optical beam. The quantum efficiency of the semiconductor layer should be reduced significantly, but not so large that the quantum efficiency of the semiconductor layer is significantly reduced. Selected, (p) the second band gap energy is less than the first band gap energy; (q) the first band gap energy is 0.8 eV to 1.1 eV; (r) the switch is of the formula

number

[0039] In any such system, the different voltages are generated by an optical / electrical converter. In addition, the status of the beam steering device may be higher than the voltage that is being This can be either or both of the rudder aiming direction and the scan rate.

[0040] Additionally, in any of the above systems, the light beam has a power of at least 800 kW / m 2 radiance of 1 / steradian.

[0041] Another implementation is where each one of the end reflectors of the cavity is either (i) a dielectric mirror or (ii) a black mirror. (iii) a Fresnel reflector; or (iv) a dielectric or other reflector having different refractive indices. may include any of the above systems, such as a mirror made of alternating layers of semiconductor material. In addition, the gain medium is a transparent solid host material or a semiconductor doped with Nd ions. In such a case, the system may further include a -1 Greater than If the gain medium is a semiconductor, the gain medium may include a filter for extracting radiation having a certain wave number. A dot gain medium may be advantageous.

[0042] In a further exemplary implementation of the above system, the cooling system includes a heat sink, a pel It can be at least one of a che diode and a liquid cooling plate. It is equipped with a fan. In addition, the gain medium may be a solder layer having a thermal resistance of less than 200 degrees Kelvin / Watt. Either way, the cooling system can be The thermal resistance between the medium and the surrounding air can be made to be less than 200 degrees Kelvin / Watt. .

[0043] In an alternative implementation of any of the above systems, the light-to-electrical power converter may be a photovoltaic cell. In such a case, the photovoltaic cell may be a III-V device. The series resistance of the force transducer should be less than 1 ohm.

[0044] The optical / electrical power converter typically has a conductor thereon. The conductor has a thickness of at least 0.02 / μ 10 where μ 10 is the decimal damping coefficient measured in 1 / m It is a number.

[0045] Such conductors should have a resistance of at least (0.01*Pρ) / (V 2 *χ) meters thick where P is the transmittance measured in watts absorbed by the photovoltaic cell. is the power, ρ is the specific electrical resistivity of the conductor, and V is the maximum current that can be generated by the photovoltaic cell. is the voltage emitted at the point of force, and χ is the fraction of the area of ​​the absorbing layer that is covered by the conductor. do.

[0046] According to a further implementation of the above system, the inductor has a series resistance measured in ohms. Resistance is measured in watts as the square of the first band gap energy measured in Joules. 2×10 of the specified driver power -40 The value should be less than the value divided by the factor.

[0047] In other implementations, the energy storage device is either a capacitor or a rechargeable battery. It could be either.

[0048] According to a further implementation of the above system, inputs from various sensors and monitors are provided The invention includes at least one safety system that estimates the probability of a safety violation by using the above-mentioned method. Like the radar system in Reference 1, it gives only the actual measurement data without showing the probability of error. This system is different from prior art systems that rely on a system of warnings, as opposed to actual detected safety violations. This differs from the conventional method in that it provides a signal indicating the probability of a safety violation. This provides several significant advantages: First, the system is able to tolerate low signal / noise or signal interruptions that are evident. Distinguishing between high-risk and low-risk situations that may be potentially problematic You can respond differently to each situation because you are more responsive. For example, low risk caused by misalignment or similar events, e.g. due to dirty openings The situation may be, for example, a high probability of beam penetration or an unreasonable beam charge, whether high or low. Second, the system can be adequately To achieve a high detection accuracy, we combined the probabilities from different safety systems into a unified probability. For example, a typical rate of 10% per hour in a changing environment can be -9 Breakdown of failure If a system is designed to have a high degree of accuracy, it will be able to provide such reliable measurements without failure. There is no single safety system that can be used to achieve this. However, Such data, when combined with the probability of error, can have a good probability of failure. and the statistical correlation of errors from both safety systems is known or estimated If the data from the two systems are closely matched, there is a significant probability that the data Such reliable data can be combined in a way that, inter alia, From noise, from component temperature, based on measurements on the same or similar devices From preloaded data, uploaded or used by manufacturers or sellers The time can be estimated from the user input information provided by the user.

[0049] According to a further implementation of the above system, the output beam of the laser resonator is irradiated using a lens. The light is collimated (or nearly collimated) in at least one axis using a lens. A lens with a high numerical aperture (NA) is used. The LEDs must have a high radiance efficiency (typically greater than 50%) to be illuminated.

[0050] Further implementations of the above system have demonstrated that the beam deflection mechanism can be further improved by over 50%. The center of rotation must be such that the weighted average of the beam is Close to the point, or at the maximum intensity point of the beam or 50% of the beam. It should be positioned close to the center of the degree line or 90% strength line.

[0051] The overall radiant efficiency of 30% for the transmit / receive / convert process is This is the desired level for energy efficiency, but it depends on the available components. It should be understood that the scope of application is limited by resource constraints and environmental conditions, and that the It should be understood that levels below 30% are also operable, such as:

[0052] In addition, any of the above systems may include a retroreflector. The second band gap energy can be electrically or optically pumped by a driver. , may be greater than 50% of the first band gap energy.

[0053] Yet another implementation performs a method of transmitting power from a transmitter to a receiver, the method comprising: (a) The first power is approximately 6940 cm -1 Approximately the first overtone of the CH absorption located at 8130cm -1 Electromagnetic waves with frequencies between the second overtone of CH absorption located at and the electromagnetic waves are at least 8 kW / m 2 / steradian radiance the conversion includes an optical resonator having end reflectors and a laser driver receiving a first power. This is accomplished by using a gain medium connected to a gain transformer, the gain medium being between 0.8 eV and A first band gap energy of 1.1 eV is disposed inside the optical cavity, and a cooling a thermally attached to the system and configured to amplify electromagnetic waves passing therethrough; And, (b) The electromagnetic waves are steered in multiple directions using a beam steering device controlled by a control unit. and directing the light beam in at least one of the directions. (c) detecting the impact of the beam on a target having an associated partially transparent surface; wherein the collision-related indication is provided by the control unit detecting (i) a small signal (ii) causing a change in the radiance of the electromagnetic beam. (iii) causing a change in a first power; and (iv) causing a change in the first power of the beam steering device. (v) varying the scan speed; and (v) varying the scan position of the beam steering device. and (vi) recording a scan position that defines the location of the target. It is used by carrying out (d) light having a second band gap energy smaller than the first band gap energy; / By using a power converter, the electromagnetic wave is converted into a second power having a certain voltage. And, (e) Inductors, energy storage devices, and equations

number

[0054] In such methods, the switch has the formula

number

[0055] In addition, detection of the beam striking a target is based on detection of retroreflected illumination from that target. Either for use in a transmitter for output or for detection of target illumination using a receiver sensor. This can be done depending on the circumstances.

[0056] Further, in any of the above methods, the second band gap energy is This can exceed 50% of the total energy consumed.

[0057] A system for optical wireless power transmission to at least one power receiving device, the system comprising: The stem is (i) an optical resonator having a plurality of end reflectors and adapted to emit a light beam; (ii) 8,300 cm -1 From 12,500cm -1 At least one having a wave number in the range Neodymium ions are used in optical communication with a filter that attenuates radiation at a single frequency. The gain medium comprises either (a) a semiconductor device or (b) a solid-state host. a first band gap energy located within the optical cavity; A thermally attached cooling system is configured to amplify light passing through the thermally attached cooling system. Acquired media and (iii) a power supply configured to supply power to the gain medium, the power supply configured to supply power to the gain medium, A driver that enables control; (iv) a beam steering device configured to direct the light beam in at least one of a plurality of directions; The steering gear; (v) a power receiving device disposed within the at least one power receiving device for transmitting the light beam at a voltage a second bandgap energy converter configured to convert a second bandgap energy an optical / electrical converter having an energy; (vi) configured to provide a signal indicating that the light beam impinges on the light-to-electrical power converter; a detector formed by the (vii) controlling at least one of the beam steering device and the status of the driver; a controller adapted to receive a control input signal from at least the detector; Controller and Including, The light beam has a power of at least 8 kW / m 2 1 / steradian radiance, and the transmitter and the at least one power receiving device, the overall radiance efficiency of the transmission between It is 20%.

[0058] In such a system, the entire transmission between the transmitter and at least one power receiving device The overall radiant efficiency should be at least 30%.

[0059] Additionally, any of the above systems may include a voltage converter connected to the output of the optical / electrical power converter. In such a case, the voltage converter may further include a control circuit for controlling the maximum power point of the light-to-electrical power converter. In addition, the voltage converter may be a DC / DC boost voltage converter. That's fine.

[0060] Yet another implementation may include one of the systems described above, wherein the resonator comprises at least one inductor. Includes dielectric mirrors.

[0061] Alternatively, the light to power converter may be a photovoltaic cell, in which case the photovoltaic cell is a II The semiconductor material may include a Class IV semiconductor material.

[0062] Further implementations may include a system as described above, with a capacitor or rechargeable battery. It may further include an energy storage device, which may be a pond.

[0063] Yet another advantageous implementation may be a system such as the one described above, with the inductor In such a situation, the inductor may further include:

number

number

[0064] Yet another system of the present disclosure may be as described above, the system comprising: The device is configured to receive information from a receiving device, the information including battery status, device This may include at least one of an identification, a required power, a required voltage, and a key.

[0065] Additionally, any of the above-described systems may further include a sensor for determining the temperature of the light-to-power converter. The sensor may then be configured to change the light beam in response to a change in temperature of the light to power converter. The output of the temperature sensor may be received by the controller. It should be.

[0066] According to yet another implementation described in this disclosure, any such system may include a photovoltaic light source. The optical window may further include an optical window positioned between the power converter and the beam steering device. In the latter case, the window may have a refractive index of at least 1.5, or even at least 1.6, It may be coated with an anti-reflection coating.

[0067] In addition, in such a system, the second band gap energy is It should be smaller than the energy.

[0068] The controller further controls the beam steering device to direct the light beam to the at least one power receiving device. It should be adapted so that

[0069] According to yet another implementation of the system described in the present disclosure, at least one power receiving device A system for optical wireless power transmission to a device is provided, the system comprising: (i) an optical resonator having a plurality of end reflectors and adapted to emit a light beam; (ii) 8,300 cm -1 From 12,500cm -1 At least one having a wave number in the range Neodymium ions are used in optical communication with a filter that attenuates radiation at a single frequency. The gain medium comprises either (a) a semiconductor device or (b) a solid-state host. a first band gap energy located within the optical cavity; A thermally attached cooling system is configured to amplify light passing through the thermally attached cooling system. Acquired media and (iii) a power supply configured to supply power to the gain medium, the power supply configured to supply power to the gain medium, A driver that enables control; (iv) a beam steering device configured to direct the light beam in at least one of a plurality of directions; The steering gear; (v) a power receiving device disposed within the at least one power receiving device for transmitting the light beam at a voltage a second bandgap energy converter configured to convert a second bandgap energy an optical / electrical converter having an energy; (vi) configured to provide a signal indicating that the light beam impinges on the light-to-electrical power converter; a detector formed by the (vii) controlling at least one of the beam steering device and the status of the driver; a controller adapted to receive a control input signal from at least the detector; Controller and Including, The controller includes: (a) causing the driver to vary a small signal gain of the gain medium; (b) modifying the radiance of said light beam; and (c) varying the power supplied by the driver; and (d) varying the scan rate of said beam steering device; and (e) changing the attitude of the beam steering device; and (f) recording a scan pose that defines a location of the optical / power converter; By outputting a command that brings about at least one of the above, the stability caused in the system is It is configured to respond to an indication of total risk.

[0070] The term attitude refers to both the position and angular orientation at which the beam steerer points the beam. It is further understood that the driver configured to provide power to the gain medium is Also, varying the pump power input to the gain medium or turning the driver on or off completely can be performed. It will be appreciated that the small signal gain of the gain medium can be controlled by turning off or on the gain medium.

[0071] In such a system, the indication of the safety risk posed by the system is at least the optical beam. a detector configured to provide a signal indicative of a light impinging on the light / power converter; and at least one power receiving device. The level is obtained from the signal generated by the level received at the amplifier.

[0072] Each of the latter systems includes a voltage converter connected to the output of the optical / electrical converter. The voltage converter may further include a voltage converter adapted to track the maximum power point of the light-to-electrical power converter. In addition, the voltage converter should be configured as a DC / DC boost voltage converter. stomach.

[0073] According to a further implementation of such a system, the resonator includes at least one dielectric mirror. Further, the light / electrical power converter may be a photovoltaic cell, and such a photovoltaic cell may be a II The semiconductor material may include a Class IV semiconductor material.

[0074] Yet another implementation of such a system is to use an energy storage device, which can be a capacitor or a rechargeable battery. In addition, they may further include an inductor. Such an inductor has the following characteristics:

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[0075] Additionally, any such system may receive information from at least one power receiving device. Such information may be configured to include battery status, device identification, power requirements, It may include at least one of a required voltage and a key.

[0076] The system may further include a sensor for determining the temperature of the light / power converter. The system is configured to modify the power of the light beam in response to a change in temperature of the light-to-power converter. To do this, the output of the temperature sensor should be received by the controller.

[0077] Additional examples of such systems further include a photovoltaic light-to-electrical power converter and a beam steering device. The optical window may include a positioned optical window. Such a window may have a refractive index of at least 1.5. The optical element may have a refractive index of less than or at least 1.6 and may further be coated with an anti-reflective coating. It is okay to do this.

[0078] Finally, in any of the above systems, the second band gap energy is It should be smaller than the gap energy.

[0079] In many situations, the maximum power that can be radiated by a system is limited by the safety requirements of that system. from the engineering requirements of the system, from the power requirements of the receiver (which may change dynamically), ), or other considerations, to prevent certain maximum values ​​being exceeded. In such a case, if the light beam exceeds a certain power, the system This reduces the small signal gain of the gain medium, resulting in a reduction in the radiance emitted by the system. It is possible to do so.

[0080] Thus, according to yet a further implementation, such a system further comprises at least one to provide a signal indicative of the power carried by the light beam before it impinges on the power receiving device of the In such a situation, the driver may include a power sensor disposed The gain medium can be configured to reduce the small signal gain when the indication exceeds a threshold. Cut.

[0081] In addition, one important indication of safety risk is "loss of power" i.e. is an estimate of the unaccounted for power that may be lost to the system. However, it can also be a loss to the radiation of power in a risky manner. Once detected, the system must take various actions to ensure safe operation. The operation of the beam involves reducing the power of the beam, reducing the small signal gain, reducing the radiance of the system, This may include deflecting the camera or informing the user. The power receiving device also provides a signal indicative of the power received. In this case, a minimum of a safety indication is provided. At least one of the power sensors is connected to the power receiving device. This may result from a difference in the power indicated by the detector in one of the two. may result from the difference exceeding a threshold value.

[0082] Other safety hazard indications come from beam penetration sensors which can be optical or system System components such as watchdogs, interlocks, and thermistors that can indicate that the system is unsafe In such a case, the system may detect a power drop in the beam. reduce, reduce small signal gain, reduce system radiance, deflect beam, or notify user Such a safety operation can be performed.

[0083] Thus, a further implementation of the above system is to detect unwanted objects entering the light beam. The beam intrusion sensor may include a beam intrusion sensor adapted to detect when an unwanted object intrudes. constitutes an indication of a safety risk. Alternatively and additionally, such a system may further The enclosure integrity sensor may include a closure integrity sensor, where the enclosure integrity sensor may include a closure integrity sensor. A warning that the integrity of the system has been lost indicates a safety risk. A detection device for detecting deviations in at least one critical subsystem in the system. Deviation behaviour constitutes an indication of a safety risk. [Brief description of the drawings]

[0084] The present invention will be more fully understood and appreciated from the following detailed description taken in conjunction with the drawings, in which: can be.

[0085] [Figure 1] 1 shows the energy density of various battery chemistries. [Diagram 2] Shows maximum allowable laser exposure values ​​for various exposure times according to 21 CFR Part 1040, Chapter I, Subchapter J, Title 8 of the Code of Federal Regulations, as amended in April 2014. [Diagram 3] An example of a warning sign for a Class IV laser product is shown below. [Figure 4] Figures 4-9 show examples of the chemical composition of various commonly used transparent polymers: Figure 4 shows a polymethyl methacrylate (PMMA) chain. [Diagram 5] The structure of polycarbonate is shown. [Figure 6] The polystyrene structure is shown. [Figure 7] The structure of nylon 6,6 is shown. [Figure 8] The polypropylene chain structure is shown. [Figure 9] The polyethylene chain structure is shown. [Figure 10] IR absorption bands for common organic chemical bonds are shown. [Figure 11] 1 shows an IR absorption spectrum of polyethylene. [Figure 12] The overtone absorption bands of some common organic chemical bonds are shown. [Figure 13] Figures 13a and 13b show different electronic configurations for converting the output voltage of a photovoltaic cell to a different voltage. [Figure 14] The power per square meter reflected by a focused mirror for a beam of radiance 8 kW / m2 / steradian is shown as a function of the numerical aperture. [Figure 15] 15A-15C show schematic diagrams of an exemplary apparatus according to the present disclosure for avoiding dangerous reflections from the front face of a receiver illuminated by a transmitter of the present disclosure. [Figure 16] FIG. 1 shows a schematic diagram illustrating a detailed description of the optical wireless power supply system of the present disclosure. [Figure 17] 17 is a graph showing the change in power transmission of the system of FIG. 16 as a function of the tilt angle of the beam steering mirror. [Figure 18] 17 shows a schematic representation of a cooling system for the gain medium of the system of FIG. 16; [Figure 19] FIG. 17 shows a detailed description of the system of FIG. 16, but in a schematic diagram further incorporating a safety system. [Figure 20] FIG. 20 is a schematic diagram of an optical / power converter of the system shown in FIGS. 16 and 19. [Figure 21] FIG. 20 shows a block diagram of the safety system of FIG. [Figure 22] 20 shows the output laser beam of the system of FIG. 19 being deflected by a mirror rotating about a gimbal axis or multiple gimbal axes. [Diagram 23] 23 shows the mirror of FIG. 22 rotated so that the beam is deflected by a larger angle than the beam shown in FIG. [Figure 24] 1 shows a schematic representation of the intensity profile of a typical deflected beam. [Diagram 25] FIG. 1 shows a side view of a laser diode from a direction perpendicular to the fast axis of the laser and lenses for steering the beam. [Figure 26] A block diagram of the complete laser protector is shown. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0086] In view of the above considerations, one exemplary implementation of the optical wireless power supply system of the present disclosure is 6940 cm -1 The first overtone of CH absorption at 8130cm -1 The second overtone of CH absorption in Such a harmonic band can be a system tuned to operate between It is not a well-known band, does not contain much chemical information, and is essentially forbidden. They arise from blocked quantum mechanical transitions and are only tolerated due to complex mechanisms. Thus, the overtone band provides a wide and weak absorption band which is precisely what is desired for this application. However, it has not proven of significant use in analytical chemistry due to its broad band nature. While this allows for the detection of a variety of different polymer compositions, the weak absorption can cause system The system can continue to operate even in the presence of organic dirt and fingerprints. Therefore, these lines are not very useful for typical absorption measurement applications, but Another advantage of these lines is that they are directly aligned on the same frequency. The advantage of this method is that there are no general absorption lines that can be detected by the material, and therefore the measurement results remain the same even if the chemical composition of the material changes. Many such harmonic bands are not significantly altered in the chart of Figure 12. Illustrated.

[0087] Electro-optical components that operate in that band are scarce and difficult to source. Perhaps the most important applications of diode lasers and diode-pumped solid-state lasers are Both the 1000MHz and 1000MHz d-State (DPSS) lasers are not very efficient at that frequency. Only low power lasers are currently commercially available, and no Since lasers with the desired parameters in this range are not currently available, A laser suitable for this purpose must be designed from scratch. The resonator and the gain medium must be designed. A sufficient selection must be made to encourage a roughly collimated or nearly collimated beam. It is necessary to build a laser with a selected frequency and radiance value. At least 8kW / m to achieve full transformation 2 Need radiance in steradians and 800kW / m for high power systems for efficient power transmission. 2 / steradian If a similar principle were followed for small systems operating over long distances, Currently, the radiance is quite high (10GW / m 2 / steradian) can be designed Receivers used below that level of radiance would be so large that the system would become unwieldy. It has no choice but to become

[0088] Different mirror configurations for the resonator were used: gold, silver or aluminum. Good quality metallic mirrors made from 1000 nm were used. These significantly improved the lasing efficiency. It has been found that dielectric material mirrors achieve fairly good results. Alternatively, Fresnel mirrors have one advantage in that they are low cost. The other mirror is a Bragg mirror (which may be a dielectric). The mirror is stable or nearly A stable resonator, or photons inside a laser (such as a fiber or diode laser) The electrodes are positioned to form a cavity that is confined to a certain space by a barrier at the center (such as a The gain medium must amplify the beam and resonate it within the cavity. At least 8 kW / m between mirrors in positions where it is permitted 2 / steradian It must be placed in the cavity so as to have a radiance.

[0089] If the gain medium is capable of lasing at more than one wavelength, the dielectric mirrors , can be chosen to restrict the wavelengths of interest to a unique value. Alternatively, a filter can be used It is also possible to fix the laser oscillation frequency by using a

[0090] Specifically, 6940 cm -1 The first overtone of CH absorption at 8130cm -1 To The mirror has high reflectivity for at least one wavelength between the second overtone of CH absorption in It is better if the saturation voltage is 100 V.

[0091] Three different approaches can be used for the gain medium.

[0092] 1.DPSS design

[0093] In a DPSS design, the gain medium can be a Nd-doped YAG crystal. And YVO 4 Crystal, GGG crystal and glass are also options for the transparent host. Neodymium is best for operation between the first overtone of the CH band and the second overtone of the CH band. Nd is approximately 7450 cm -1 This is because Nd ions have a transition near The ion is typically excited by absorbing radiation from an 808 nm laser diode. However, other wavelengths can be used. Nd-based gain media are 0cm -1 Unless a filter is added inside the resonator to block nearby transitions, or Unless these unwanted emissions are extracted, they tend to lase at fairly high frequencies. When such a filter is added, the 7440-7480 cm -1 Laser oscillation occurs at Such filtering can be achieved by using a prism or grating instead of a filter. or by appropriate chromatic design of the laser cavity.

[0094] 2. Semiconductor laser

[0095] Alternatively, a semiconductor-based design can be proposed. The wavelength of the semiconductor laser can be adjusted to the wavelength of the light used. This can be tuned by modifying the lasing band gap of the semiconductor Semiconductors, specifically those of the III-V type, with a band gap of the order of 1 eV. of the quantum dot type, and more particularly, but not exclusively, of the quantum dot type. 0cm -1 ~8200cm -1 Specifically, the light is emitted at a desired frequency of 0.8e A band gap of V~1.1 eV gives good results and is, at least in part, commonly used. It is absorbed by virtually all of the polymers used.

[0096] 3. Various alternative designs may include, for example, Bragg mirrors and / or fiber loop mirrors Nd-doped fiber lasers can also be used in the systems described in this disclosure. Alternatively, a Raman shifted fiber laser can be used.

[0097] During operation, the gain medium heats up and must be cooled to prevent wavelength shifts and efficiency degradation. If the gain medium is properly cooled, it should be at least 8 kW / m 2 / steradian It has a radiance of 6900 cm -1 ~8200cm -1 A beam with a frequency of The excitation power or current can be increased all the way until the beam is It can be collimated and is attenuated by most organic materials, including polymers, allowing detection. Nevertheless, it is not strongly absorbed by contaminants such as fingerprints.

[0098] Laser gain media are typically constructed to operate at temperatures below 150 degrees Celsius. Once the temperature exceeds a certain level, typically around 250 degrees Celsius, a certain number of problems can occur. do.

[0099] First, low-level excited states tend to cluster together, especially in three- and four-level lasers. This, in turn, leads to a significant decrease in luminous efficiency due to the thermal recombination of charge carriers in the semiconductor. It can be lowered.

[0100] Second, the soldering of the gain medium may be damaged if such a thermal attachment method is used. may be received.

[0101] Third, thermal aberrations can occur which cause beam degradation.

[0102] Fourth, the thermal expansion of the laser gain medium may differ from that of its surroundings, resulting in increased mechanical stress. This can cause stress, or distortion and fracture of the gain medium.

[0103] For these reasons, among others, the gain medium must be thermally attached to a cooling system. Typically, the gain medium dissipates 0.1 to 100 W of heat within a 1 mm 2 ~40mm 2 from the surface of The cooling system for the gain medium is designed to keep the temperature of the gain medium below 150 degrees. , the thermal resistance must be less than 200 Kelvin per watt. For systems that transmit the high power typically encountered, thermal resistance needs to be significantly lower. In many cases, a thermal resistance of less than 0.05 Kelvin / Watt is required.

[0104] The attachment of the cooling system surface to the gain medium is determined by the expansion coefficient of the gain medium itself and the cooling system. The expansion coefficient of the front surface of the system must match that of the solder or This is done using a third material, such as an adhesive.

[0105] Such cooling systems typically include passive heat sinks, heat sinks with fans, and fans. Either a Peltier element connected to a heat sink with or without, or a liquid-cooled cooling system Alternatively, it can be by active circulation based on a circulation pump or based on heat pipes. A stand-alone liquid circulation cooling system with passive circulation based on a liquid source may also be used.

[0106] If the cooling system includes a heat sink with a fan, its thermal resistance is 0.1 degrees Kelvin. It must be less than every watt.

[0107] If the cooling system is a passive heat sink, its thermal resistance is less than 0.3 degrees Kelvin per watt. must be full.

[0108] If the cooling system is a Peltier element, it must generate a temperature difference ΔT of at least 5 degrees. do.

[0109] If the cooling system is an active liquid cooling system, it will cover the entire range of thermal resistances mentioned here. It must be possible to do so.

[0110] Passive heat sinks are preferred in systems designed for low cost and quiet operation. While liquid cooling systems are preferred for high power systems, fan-assisted heating is preferred. A typical system in which the power sink or fluid pump has an electrical output of more than 1 W; and It is used for transmitters having small volumes, such as approximately less than one liter.

[0111] The gain medium is typically driven by a driver, which provides power to the gain medium. However, that power is given as electrical power in the case of some semiconductor gain media, or as a Semiconductor gain media or DPSS systems, or chemical or other forms of energy The amount of power provided by the driver depends on the operating conditions and the level. The saturation gain of the gain medium, on the other hand, generally determines the small signal gain achieved, which determines the laser radiation. is a function of the material selected for the gain medium and ultimately the radiation emitted by the laser. However, this does not necessarily follow a simple linear pattern. The driver may have two or more operating states: one is used for power transmission and the other is for target It is used for other functions of the system such as discovery, setup and information transmission. The advantage is that the laser driver is able to provide the same output power and beam parameters under both operating conditions. The first is to produce stable radiation. However, stable operation during power transmission is more important. do.

[0112] To convert the light beam back into electricity so that useful power can be transmitted, a light-to-electrical converter, typically Typically, photovoltaic cells must be used. As with lasers, the frequency of the beam used Suitable photovoltaic cells in a number of custom sizes are commonly available as off-the-shelf components. This is not the case, so a custom battery is required. The band gap of photovoltaic semiconductors is The bandwidth of the gain medium used must be such that the beam frequency is efficiently absorbed by the semiconductor. The gap must be slightly smaller than the gap, otherwise the conversion efficiency will be very poor. On the other hand, if too small a band gap is used, a less efficient system is achieved. Also, the conductors on the photovoltaic cells must be tailored to the radiance of the beam used. Yes, the higher the radiance, the thicker the conductor needed.

[0113] The band gap of the laser gain medium must be in the range of 0.8-1.1 eV. The band gap of the photovoltaic cell to be used must be lower than that. Power cells typically have about 60-80% of the band gap energy divided by the electron charge. % voltage, a single junction cell tailored to the laser frequency of interest would be sufficient for practical systems. Assuming a few watts of output power is required for the system, this is typically very low, around 0.3 to 0.8 V. This produces a voltage and typically a high current. A conductor on the semiconductor carries the generated current (e.g. It must be thick enough to be transported without significant loss (e.g., more than 5%). Typically , the series resistance of the conductors should be less than 1 ohm, or better still, less than 0.1 ohm; The heat generated must be extracted efficiently from the photovoltaic cells. This efficiency is generally determined by the temperature It decreases with

[0114] This combination of low voltage and high power is typical of the devices needed to charge portable devices. It is not easy to convert it to a high voltage of 3.3 or 5V. Some systems require voltages such as -48V, 12V or 3.8V. The system obtains a stable voltage at a level higher than the expected output voltage from the photovoltaic cell. A typical method for increasing the voltage of a photovoltaic cell is to directly For example, a photovoltaic series array including P / N cells and N / P cells is connected in a row. U.S. Patent No. 3,370,986 to MFAmsterdam et al. entitled “ This is described in the IEEE International Conference on Industrial Automation and Systems (ICISA) Annual 2017 (ICISA) Annual Meeting, which is a non-profit organization dedicated to the advancement of industrial automation and systems engineering. This is while utilizing roughly the same amount of semiconductors and without any additional components. , which shows a typical configuration that results in high voltages and is therefore typically the solution of choice.

[0115] However, this solution requires 8kW / m 2 High radiance of up to 1 / steradian This is not appropriate for the system described herein where a laser is used. Lasers typically do not have uniformly shaped beams. can vary over time, so pointing accuracy may be less than optimally desired. In such a situation, a compact and efficient LED that illuminates all cells evenly is required. It is virtually impossible to design a system that works like this. Photovoltaic cells connected in series In such a case, the light sources will not be uniformly illuminated and will not generate the same current. In fact, the voltage is increased to the desired level, but the current is increased to the minimum current The current drawn by the cell that provides the current, typically the least illuminated cell, drops to the current produced by the cell that provides the current, typically the cell that is least illuminated. In such a situation, the efficiency is very poor. Therefore, an improved alternative to increasing the voltage is A method is needed.

[0116] One way to increase the voltage of a single cell is to charge the capacitors in parallel and then This method works well for low currents, but can be problematic for large currents. When the current increases beyond a certain level, the switching time increases to a certain level, which affects efficiency. Efficiency degrades with increasing switching time.

[0117] Energy is converted to AC using a fast, low resistance switching mechanism In this case, the AC current is amplified using the coupled inductance and then converted back to AC. The increased voltage AC is converted into a current by a diode bridge and a capacitor or a battery. Such a system can be used to convert the current to DC using a suitable energy storage device. This has advantages when the voltage needs to be increased by more than 20 times the photocell voltage. Another advantage of this system is that the switching can be done from the transmitter using a laser, so the receiver Such a system reduces the voltage by a factor of less than ten and reduces the cost and complexity of the device. When you need to increase capacity or size and volume limitations are important for your application If so, there is a disadvantage.

[0118] Reference is now made to FIG. 13A, which shows an efficient and simple method for voltage conversion. In order to increase the voltage of a photovoltaic cell, a single inductor is connected to a low resistance switch It can be used with a power steering mechanism and an energy storage device. In this figure, the square on the left is a photovoltaic cell, and the switch S can be a MOSFET, a JFET, or A low resistance switch such as a BJT, IGBT or pHEMT, with an inductance L of 1000 Ω. Connected to the output of the electromotive force cell is a capacitor C which acts as an energy storage device.

[0119] The following description assumes the use of zero resistance components for simplicity. Taking this into account introduces some computational complexity and will be explained in a later section of this disclosure. The switching mechanism divides the inductor into two primary operating phases: charging and discharging. During the charging phase, the inductor is cycled between the two phases by closing switch S. During this phase, the inductor is connected in parallel with the photovoltaic cell by It is charged by the energy converted by the power cell. In addition,

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[0120] During the discharge phase, the inductor is turned on by opening switch S. During this phase, the inductor supplies the output energy to the output storage device. The energy delivered to the device is the reduction of the inductor energy.

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[0121] The energy transferred from the photovoltaic cell to the inductor during that phase is

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[0122] In steady state operation, the energy in the inductor at the end of the cycle is It was brought to the beginning of Ikuru

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[0123] However, in this system, the parasitic characteristics and other aspects of the components are transformed. may have a significant effect on the operation and efficiency of the system, Care must be taken in selecting and using the correct components to meet these requirements. We consider the elements one by one below.

[0124] Inductors

[0125] 1. The inductance of an inductor defines the rate of change of the inductor current due to an applied voltage. This is given by dI / dt=V / L, where dI / dt is the change in current. is the capacitance, V is the voltage applied across the inductor, and L is the inductance. In the context of a current system, V is determined by the gain medium at the transmitter. By selecting a gain medium that is different from the gain medium, a change in the photon energy is induced, which This governs the subsequent change in the photovoltaic band gap and therefore the change in the photovoltaic voltage. This requires different inductors and / or switching frequencies. The speed is determined by the response of the inductor current to changes in the incident power from the transmitter through the optical-to-electrical converter. It must be fast enough to be able to operate the device while also taking into account power dissipation, input voltage ripple and output voltage must be slow enough to avoid high amplitude current ripple contributing to voltage ripple. The optimum inductor value is one that provides a ripple current that is 20% to 40% of the maximum expected input current. Although the system should be able to operate at 10% to 60%. A careful analysis reveals that to achieve this goal, the inductor value, measured in henries, should be L is the limit

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[0126] For an inductor to be successfully integrated into a mobile client, the inductance is typically This should be less than 10mH, as required for charging mobile clients. An inductor suitable for the current being carried, with a suitable body for portable applications. Inductors with product limits are typically well below this value. An inductor with too small an inductance, such as H, can cause the switch in the system to These require high switching frequencies that severely limit the availability of other components such as The switching losses caused by such high frequencies are can be higher than the amount of power delivered by

[0127] 2. Series resistance of the inductor, R parasitic is designed to minimize conduction power losses. Typically, a value is chosen that results in less than 10% efficiency loss. and the series resistance of the inductor, measured in ohms, is

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[0128] 3. In a typical system, the inductor series resistance is less than 10 Ω. The saturation current is typically chosen to be higher than the expected inductor peak current,

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[0129] 4. For reliable operation, the inductor should be rated for a voltage higher than the maximum expected input current. Rated for currents of 10 mW or more for extracting power from a single junction photovoltaic cell. The inductor current rating must be higher than 10mW / 0.8v=12.5mA.

[0130] Switching Mechanism

[0131] 1. A switching mechanism is usually made up of two or more devices. The first device, the media When the in-switch is conductive, it sets the inductor in the charging phase. During the discharge phase, a load or an output energy storage device is connected to the inductor. A diode (FIG. 13A) or switch (FIG. 13B) is used to disconnect the It can be either

[0132] 2. The switching mechanism has a low switch current to minimize switching losses. Capacitance

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[0133] 3. In a typical system, the switch node capacitance is less than 100 nF and It exceeds 10pF.

[0134] 4. Connect the inductor to ground or the optical / power converter to the inductor at the switch node. The series resistance of the main switch connected to the ductor is

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[0135] Energy Storage Devices

[0136] 1. The energy storage device may be either a capacitor or a battery, or both. .

[0137] 2. The energy storage device is in the charging phase when the inductor is disconnected from the output. The capacitance of the storage device is required to maintain the output voltage during switching. Based on the switching frequency, laser power, and desired output ripple voltage,

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[0138] 3. The energy storage device also provides power to the load during temporary interruptions in the optical path. For the purpose of uninterrupted power supply, the energy storage device can Also, the minimum operating output power (P OUT_MIN ) with interruption time interval (T INT ) multiplied

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[0139] In some cases, the capacitor provides energy storage for the client application. In this case, the client application acts as a Secondary energy storage devices (batteries traditionally used in mobile devices) ) can be designed without the energy storage device of the system described herein. is sufficient to provide the client device with the power it needs until the next charging event. In such a case, it is necessary to store at least 0.5F and 10F. In other cases, a supercapacitor with a capacitance greater than 1000 kV can be used. i.e., if the client device has low power requirements or if the device has internal If the device has an independent energy storage device such as a battery, or if the device If it does not need to operate without a supply, the capacitor used is typically 1F, which is sufficient. If a rechargeable battery is used as the energy storage device, the above capacity This is similar to the logic of the Pacita, where the battery is used only as a voltage regulator, but between charging events If not used as a means to maintain power to client devices between The energy capacity of a battery is the energy delivered during 100 cycles of the switch (typically It is advantageous to limit the maximum capacity to 100 times the capacity of the battery (typically less than 0.1 Wh). On the other hand, if the battery is not able to charge between charging events, it is determined based on the capacity budget and cost efficiency. If it is also used to power an Android device, its capacity should be at least 1000mA. The energy required by the client device between events (such as a cellular phone) The battery must be large enough to store a large amount of power (typically more than 0.1 Wh in some cases). Batteries also have volume limitations depending on the product in which they are intended to be used. When a battery in a product with a V is installed outside a device, it typically The voltage is limited to a few times the volume of the device, i.e., 3V. A battery used to power a 300cc cellular phone typically has a volume of 300cc. Such batteries are typically limited to a capacity of less than 300Wh due to the above limitations. Has quantity.

[0140] The circuit in FIG. 13A is not the only possible topology. FIG. 13B shows a different design that can achieve similar performance characteristics. The component roles, constraints, and expectations are the same as those listed for the circuit in FIG. 13A. The primary difference is that the positive and negative terminals of the output voltage are inverted.

[0141] In some applications, an energy storage device converts the received power into It is preferable to place it inside the device in which it is intended to be used. In particular, applications where short periods of operation are expected and do not require a regulated voltage. In some applications, even the energy storage device may be eliminated.

[0142] Key points for adjustment

[0143] The power output of a photovoltaic cell depends on the incident light power and the load applied to it. The control mechanism of the voltage converter is determined as the load conditions result in maximum output power from the photovoltaic cells. The system needs to adjust the load point. The control mechanism is suitable for most conditions. Is it designed to maintain a constant voltage across the cell terminals, known as the maximum power operating point? Alternatively, the optimum cell voltage can be found by measuring the cell output power under any operating condition. The first approach is simple: The second approach is more power efficient.

[0144] The generated laser beam must be directed towards the receiver. In order to achieve this, a beam steering device must be used. There are several beam steering sub-systems that can be used: The system includes a moving mirror, a moving lens, an electrical / optical modulator, a magnetic / optical modulator, and a transmitter system. A set of motors that move the entire system in one or more directions, or any other suitable beam deflection device. Includes chair.

[0145] The beam steering device is most conveniently used by a controller to control a laser driver. It must be controlled by the same controller that is used.

[0146] The beam steering device is 8kW / m 2 / A beam exceeding steradian is focused in one of a certain number of directions. It is configured to be directed to both.

[0147] The damage threshold of the beam steering device must be such that it can withstand the radiance of the beam. It is necessary.

[0148] For example, if a beam is focused onto a mirror using a focusing mechanism with a numerical aperture of 0.5, then The mirror has a power of 8kW / m 2 At least 6.7kW / m for a beam of 1.0 steradian 2 When high radiance beams are used, the mirrors must be able to withstand high power densities. should be chosen to have a correspondingly high damage threshold.

[0149] Figure 14 shows the 8kW / m 2 per square meter when a beam of steradian is focused The power reflected by the mirror is shown as a function of the numerical aperture. When used, the power reflected by the mirror increases correspondingly in a linear manner.

[0150] The beam is far from uniform, sometimes resulting in a radiance ten times higher than the beam average. In this way, "hot spots" can be created.

[0151] Therefore, the mirror is dependent on the actual beam radiance and numerical aperture of the focusing mechanism on the mirror. 14. The combined scale is at least as large as that shown in FIG. 14, and preferably less. Both should have a damage threshold ten times higher.

[0152] Typically, the receiver includes a receiver located near the photovoltaic cell and between the photovoltaic cell and the transmitter. There is a determined optical front through which the beam enters the receiver, and this optical front is These are required to protect the typically delicate structures of photovoltaic cells and are often The front is made of Corning Gorilla Glass. The material has a scratch-protecting coating, such as PTFE (registered trademark), or is highly scratch-resistant. The front surface is also treated to resist contamination such as fingerprints and dust that may become etched. Light that is treated or reflected to reduce noise or optical effects The front surface of the photovoltaic cell may also be coated with an anti-reflective coating that reduces the level of reflection. In some cases, the front surface may be part of the structure of the photovoltaic cell itself, or is coated onto the photovoltaic cell.

[0153] In some circumstances, the amount of reflection from a surface can be reduced by choosing an anti-reflective coating with very low reflectance. In the unlikely event of a spill or finger contact, Such anti-reflective coatings reduce the amount of reflection when the coating becomes contaminated or covered by any of the fingerprints. This reduces the effectiveness of the reflector and typically results in 3-4% of the incoming light being reflected in an uncontrolled direction. If the reflected light is reflected in a divergent manner, the power density will soon drop to a safe level. However, if the reflection were to become focused, the power density could increase to dangerous levels. For this reason, the ROC (Radius of Curvature) of such surfaces is It is important to ensure that at no point does re) fall below a specified value. Generally, it is intended that only a small portion of the incident light is reflected from the surface. , of any useful surface, regardless of the nature or shape of the curvature of that surface. The risk of unintended beam reflection is reduced. The level of reflected light can be variable. This Even with a reflection of approximately 4% from an untreated glass surface, a layer of foreign contaminants on the surface This is because it can be increased if it results in increased reflectance. Reflectance is not expected to exceed 20%, with reflectance of 0.1% or significantly less. is essentially 4% of untreated glass, as is the case with typical AR-coated glass. Therefore, a surface can be considered to have the property of reflecting a small portion of the incident light. As described in the disclosure and as claimed in the claims, the present specification is generally used to mean less than 4% of untreated glass.

[0154] Here, even for a small portion of the incident light that can be reflected from the surface, the above-mentioned dangerous reflections are prevented. 15A to 15C are schematic diagrams illustrating a method of avoiding this. FIG. 15B shows the situation where the surface is a convex surface, and FIG. 15C shows the situation where the surface is a diffusive surface. In FIG. 15A, at least 8 kW / m 2 / steradian radiance An incident beam 110 is directed towards a photovoltaic cell 112, which may be the front surface of the photovoltaic cell. The beam penetrates the front surface 111, which reflects a certain amount of the beam 110 away from the surface. It produces a focused beam 113 having a focal point 114 at a distance. The curvature of the surface 111 is adjusted to ensure that it does not pose any danger to the skin or other objects. The radius (ROC) is set so that the beam is focused with a low numerical aperture, as in FIG. 15A. or as in FIG. 15B, defocused, or as in FIG. It must be spread as in 15C to achieve these limits. In order to achieve this, the surface is concave when viewed from the transmitter towards the photovoltaic cell as in FIG. 15A. In this case, the ROC must be greater than 1 cm and typically exceeds 0.5 W. If optical high power systems are used, they must be greater than 5 cm. In addition, the ROC of the surface can be negative, as in FIG. 15B, but the ROC is always 0. These limitations ensure that the reflected light beam does not The point is associated with a virtual, i.e. divergent, reflected beam, or the focus is at least As a result, the focal point-induced refraction is The surface also has a small diameter which results in a diffuse surface as in FIG. This can result in numerous areas of small curvatures, which can lead to risk of dangerous foci. In such a case, the curvature ratio of each subsection of the surface is The diameter can be less than 1 cm without producing a focus. Furthermore, the surface is divided into multiple zones. When divided, each zone may have a small curvature.

[0155] To operate safely, the system also ensures that the power beam is not blocked by the photovoltaic cells and that no The power beam can be directed to the photovoltaic cell so that it is not directed into the dangerous area. To achieve this, the detector must provide an indication of beam impingement to the receiver. Such a detector must be positioned so that it can see the light. Typically, such a detector is positioned at the receiver. However, it is also possible for such a detector to be located at the transmitter. It is necessary to respond to phenomena that arise due to the impact of the beam on the receiver. The system captures images and receives beams from the barcode printed on the receiver. This may involve processing light information such as the reflection of the illumination pattern of the bar code. A single or multiple retroreflectors or an array or pattern thereof can be used to detect Reflections from the antenna are then directed to a receiver, where they can be used for image processing, back reflection measurements, or other purposes. It can be detected at the transmitter by either coherence effect measurement of reflection. The detector may be a current or voltage sensor located at the receiver, a current sensor located at the receiver or a voltage sensor located at the transmitter. A photodiode or imaging device that can be present in either the transmitter or receiver A retroreflector in the vicinity of the photovoltaic cell may also be used to reflect the reflected light from the transmitter. It can be used in combination with an additional detector to detect light reflected from the retroreflector. .

[0156] When the detector detects a beam of light impinging on the photovoltaic cell, it detects the If a detector is present at the receiver, such signaling can be RF, IR, or visible. Wireless using communication channels that can be optical, UV, beam modulation, TCP / IP, or sound The system controller is usually located in the transmitter, but The signals may be located in a main control unit which may also be on a computer network. Upon receiving the signal, the controller responds by doing at least one of the following: (a) detecting a laser (b) the direction in which the beam is pointed, and the speed at which such direction is changed; Change the operating characteristics of the beam steering device, such as the beam angle.

[0157] Reference is now made to FIG. 16, which is a schematic diagram showing a detailed description of the complete system. The system includes a transmitter 21 and a receiver 22. In general, the transmitter and receiver are remote from each other. In FIG. 16, the beams are shown as being close to each other for convenience. System 15 transfers power from transmitter 21 to receiver 22 .

[0158] At the receiver 22, the front surface 7 reflects a small portion of the incident beam 15 as a reflected beam 16. Alternatively, the beam may be diverged or a virtual focus may be placed behind the front surface 7 or at the surface 7. The objective of the present invention is to provide a real focus at least 1 cm in front of the object through an at least partially transparent surface 7. After transmission through the optical fiber 15 , the beam 15 impinges on the optical / electrical power converter 1 .

[0159] The light / power converter 1 is enclosed in a package that may have a front window, which may be a surface 7 or a separate window. This can also be done by interfacing the air or the surrounding adhesive or glass. The membrane may be coated to have an exterior surface adapted to function as a membrane. In construction, the optical / electrical converter 1 is typically a junction of semiconductor layers on which conductors are deposited. In many embodiments, surface 7 is coated with one of these semiconductor layers. or the exterior surface of one of them.

[0160] A signaling detector 8 indicates that the beam 15 is impinging on the photovoltaic cell 1 and The information is transmitted to the controller 13, which in this example system is located at the transmitter 21. The control signal is transmitted by link 23 to a detector 24 at the transmitter.

[0161] The power converter 1 has a bandgap E8 and typically has a voltage of 0.35 to 1.1 V. However, the use of multi-junction photovoltaic cells leads to even higher voltages. flows from the photovoltaic cell 1 through the conductors 2a and 2b having low resistance to the inductor 3. The inductor 3 stores a portion of the energy flowing through it in the magnetic field.

[0162] The automatic switch 4 is typically a MOSFET connected to a control circuit (not shown in FIG. 16). A transistor that switches between alternating states so that the current flows through it during the first part of the time. is allowed to flow through inductor 3 to ground during a second portion of the time. The inductor emits its stored magnetic energy as a current with a higher voltage than the photovoltaic cell. The current passes through diode 5, after which the power is available. The load flows to 6.

[0163] The automatic switch 4 can be fixed frequency or controlled from the transmitter or client load. Operates at variable frequency and / or duty cycle and / or waveform controlled by or based on the current, voltage or temperature at the load, or on the current at the automatic switch 4, based on voltage or temperature, or based on current, voltage or temperature emitted by the light / power converter 1 The system status may be based on the state of the system, or on some other indicator.

[0164] The receiver can be connected directly to a load 6 as shown in FIG. The load 6 may be external to the receiver or may be connected to another device such as a cell phone or other power consuming device. This device supports USB / Micro USB / Lightning / USB Type-C You can connect using sockets like in C.

[0165] In most cases, an energy storage device such as a capacitor or battery is connected in parallel with the load 6. Alternatively, the load 6 may include an energy storage device such as a capacitor or a battery. The device may include:

[0166] The transmitter 21 generates and directs a beam 15 to the receiver 22. In a first mode of operation The transmitter 21 searches for the presence of the receiver 22 using a scanning beam and detects the receiver using a communication means such as RF, light, IR light, UV light or sound By using a retroreflector or a retroreflective structure, a bar code, a high contrast pattern, A camera is used to detect a visual indicator of the receiver, such as a camera lens or other visual indicator. Once a rough location is found, the beam 15 is typically at low power and During such scanning, the beam 15 is When the beam 15 strikes the photovoltaic cell 1, the detector 8 detects it. and sends a signal to the controller 13 accordingly.

[0167] A controller 13 commands the laser driver 12 to vary the power P input to the gain medium 11. and / or command mirror 14 to alter either its scan speed or direction. change the position, steer or hold the beam in that position, and change the scan step rate The gain medium 11 responds to such signals by either or both of providing different powers P. When received from the laser power supply 12, the small signal gain, i.e., a single photon passes through the gain medium. The gain experienced when traversing a gain medium without other photons traversing the gain medium at the same time , changes. Photons directed between the rear mirror 10 and the output coupler 9 enter the gain medium When it passes through 11, more photons are emitted in the same direction as the beam 15, Optical resonance occurs between the laser 10 and the output coupler 9.

[0168] The output coupler 9 partially transmits the 6940 cm -1 In The first overtone of CH absorption and 8130cm -1 The space between the second overtone of CH absorption in The reflective surface operates at least in part at a wavelength of 100 nm, typically with alternating layers of different refractive index materials. The gain medium 11 may be made of glass, plastic, or a multi-layer dielectric or Alternatively, Fresnel reflection can be used if the gain medium provides a small enough signal gain. It can be used if it has a sufficiently high refractive index. Metal mirrors can also be used. If the gain medium is a semiconductor or fiber amplifier, A reflector may also be used. The output coupler 9 may also transmit a portion of the light. By using a diffractive optical filter, another portion of the light is extracted from the wave traveling forward inside the resonator, typically The third part is also a semitransparent optical component extracted from the wave propagating backward inside the resonator. The reflector may consist of a highly reflective mirror combined with a beam extractor such as a reflector component.

[0169] The back reflector 10 should be a highly reflective mirror, but a small amount of light will leak back and be obscured by the monitor. Used for rings or other purposes 6940cm -1 The first overtone of CH absorption and 81 30cm -1 At least a portion of the spectrum between the second overtone of the CH absorption at Typically, the material is deposited on a substrate, which is usually glass, metal or plastic. Alternatively, if the gain medium is small enough, Fresnel reflection can also be used if it provides sufficient signal gain. Metallic mirrors can also be used. If the gain medium is a semiconductor or fiber amplifier , Bragg reflectors can also be used.

[0170] The gain medium 11 has a wavelength of 6940 cm -1 The first overtone of CH absorption at 8130cm -1 However, this spectrum is not necessarily This is because the laser driver 12 is excited with power P In this case, it is possible to deliver a small signal gain larger than the loss caused by the output coupler 9. The area, field of view and damage threshold are at least 8 kW / m 2 / steradian / (1 -R), where R is the output coupler 9 This is 0.8-1.1 times the reflectance of the transparent host material doped with Nd ions. Semiconductor materials with bandgaps of 100 eV or simulating radiation in that spectral range The gain medium 11 is a reflective optical fiber that is rotatable from the back reflector 10. 3. Positioned in the optical line of sight to the force coupler 9 and thus reflected by the back reflector 10 The radiation is allowed to resonate between the back reflector 10 and the output coupler 9 via the gain medium 11. do.

[0171] A typical implementation in which the gain medium 11 is a semiconductor with a band gap of 0.8-1.1 eV. For this purpose, a heat extraction device is preferably attached and the laser driver 12 It can be electrically or optically excited.

[0172] The gain medium 11 is YAG or YVO4 doped with Nd ions. 4 , GGG, or glass In a typical implementation, the host is a transparent material such as a semiconductor or ceramic. The medium 11 is 9400 cm from the resonance between the rear mirror 10 and the output coupler 9. -1 Nearby It is preferably in optical communication with a filter to extract the radiation.

[0173] Beam steering device 14 is shown controlled by controller 13. This is 15 can be deflected in multiple directions. Its area is tilted up to the maximum operating tilt angle. The beam 15 must be large enough to contain substantially most of the beam 15 even when the beam is No. Here is a simple 2D example. A beam 15 is collimated into a 5 mm diameter (1 / e 2 The beam is a Gaussian beam with a diameter of 100 mm, and the beam steering device is a single beam centered on the center of the beam. If the mirror is a rounded gimbal mirror, and the maximum tilt required for the mirror is 30 degrees, , and assuming that the beam steering device 14 has no other apertures, the mirror If the beam has a similar 5mm diameter, then at normal incidence of the beam, it will be approximately At a tilt angle of 60 degrees, the loss is approximately 60%. This power loss is illustrated in the graph of FIG.

[0174] At the start of operation, the controller 13 commands the laser driver 12 and the mirror 14 to perform a seek operation. This is because the laser driver 12 operates in the first state to command the receiver 22 to This is done by pointing the beam 15 in the general direction in which a target is likely to be found. For example, if the transmitter is mounted in a corner of the ceiling of a room, the scan will be directed downward and into the room. The beam 15 is directed to a receiver 22 that includes an optical / electrical converter 1. If a hit occurs, the detector 8 sends a signal, for example to the controller 13. Unless such a signal is received, The controller 13 instructs the beam steering unit 14 to steer the beam 15 in another direction to search for a receiver. When such a signal is received from the detector 8, the controller 13 commands the beam steering. The rudder 14 is commanded to stop or slow down scanning and lock onto the receiver. Alternatively, the controller 13 may instruct the laser driver 12 to increase the power emission. It is also possible to recognize the location of vessel 22 and return to it at a later stage.

[0175] As the laser driver 12 increases its power emission, the small signal gain of the gain medium 11 increases. As a result, the beam 15 carries a lot of power and power transmission begins. Upon detecting a power loss greater than the threshold, the controller 13 typically instructs the laser driver 12 to The state of the power supply is changed by reducing the power to maintain the required safety level. The threshold is either predetermined or dynamically set and is typically equal to the maximum allowable exposure. The level is representative of a significant portion of the noise level and is typically larger than the system noise figure. These conditions are not necessarily consistent with the fact that the beam 15 is no longer aimed precisely at the optical / electrical power converter 1. or that an object had entered the path of the beam or that a malfunction had occurred. Other indications of safe operation, e.g., displayed through the user interface or API, may be used. An indication from the user regarding the safety of the transmission that may be transmitted or a safety action from a second safety system. If an indication is present, the controller increases power to the laser to compensate for the power loss. The controller 13 can also command the beam steering assembly 14 to It can also command the device to perform a search operation.

[0176] There are two distinct stages in the exploration behavior. First, the robot searches for visual patterns. Using a camera capable of detecting retroreflectors, a high-contrast image is obtained and transmitted to the receiver. or other indications from the scanning features of the beam steering unit 14. A coarse search is then performed using the potential A list of positions can be generated. The second stage is the fine search. The steering mirror 14 transmits a signal to the detector 8 that the beam 15 is impinging on the light-to-electrical converter 1. The beam 15 is directed at a small area until the

[0177] We now refer to FIG. 18, which shows an example of a cooling system for the gain medium 11 of the system of FIG. Although the reflectors 9, 10 are shown as separate optical elements, one or both of them may be It should be understood that the coating may be applied directly to the gain medium end facets to simplify the system. The gain medium 11 converts the power it receives from the laser driver 12 into both heat and photons. When the gain medium heats up above a certain temperature, system performance typically deteriorates. For this reason, the gain medium 11 is preferably bonded with a thermally conductive solder having a low thermal resistance. The heat sink 34 is attached to the substrate 32 using a bonding agent 33. The bonding agent 33 acts as a conductive adhesive. The binder 33 may be a material having a thermal expansion coefficient that is in agreement with that of the gain medium 11 and the heat sink 34. The heat sink 34 is typically a metallic, low thermal resistance heat sink. It may be a fin to increase the surface area, or a fan or liquid pump 35. An external fluid pumping system is provided.

[0178] Reference is now made to Figure 19, which shows a detailed description of the system of Figure 16, but in accordance with the present application. The present invention further incorporates a safety system 31 constructed and operable in accordance with the methods and systems described herein. FIG. 19 shows the inputs as separate modules to illustrate the additional inputs that are provided. Although shown as a safety system, the safety system may be incorporated into the controller 13, which is generally described. As described above, the system includes a transmitter 21 and a receiver 22. Typically, the transmitter and receiver are located remotely from each other, but for convenience, As shown in Figure 19, the beam 15 is directed from the transmitter 21 to the receiver 22. Transfer power.

[0179] At the receiver 22, the front surface 7 reflects a small portion of the incident beam 15 as a reflected beam 16. Alternatively, the beam may be diverged or a virtual focus may be placed behind the front surface 7 or at the surface 7. The objective of the present invention is to provide a real focus at least 1 cm in front of the object through an at least partially transparent surface 7. After transmission through the ion beam 15, the beam 15 has a thickness T and a constant absorption coefficient for the light beam 15. The light impinges on the light-to-electrical converter 1, which has a semiconductor layer that is Depending on the design wavelength of the beam, as further detailed in FIG. 20 below, the semiconductor layer The absorption coefficient of the light beam at the wavelength of 100 nm should be 0.02 times the reciprocal of the absorption coefficient of the light beam at the wavelength of 100 nm.

[0180] The light / power converter 1 is enclosed in a package that may have a front window, which may be a surface 7 or a separate window. This can also be done by interfacing the air or the surrounding adhesive or glass. The membrane may be coated to have an exterior surface adapted to function as a membrane. In the configuration, the light / electrical power converter 1 is typically a junction of semiconductor layers on which conductors are deposited. In many embodiments, surface 7 is coated with one of these semiconductor layers. or the exterior surface of one of them.

[0181] A signaling detector 8 indicates that the beam 15 is impinging on the photovoltaic cell 1 and This information is sent to the controller 13 and often includes the received power, the received optical power, and the identification information. , temperature and photovoltaic power of the receiver, and control information from the client device. It also transmits other data such as relayed information. In this example, the system controller 13 The control signal is provided to the link 2 3 to a detector 24 in the transmitter.

[0182] The safety system 31 receives information from various sources, which are detailed below in FIG. In particular, from a small portion of the combined beam 15 from the beam combiner 32 and from the signal The information is transmitted from the power detector 8, typically via a data channel between the power receiver and the power transmitter. The safety system 31 outputs a safety indication to the control unit 13.

[0183] The power converter 1 has a bandgap E8 and typically has a voltage of 0.35 to 1.1 V. However, the use of multi-junction photovoltaic cells leads to even higher voltages. flows from the photovoltaic cell 1 through the conductors 2a and 2b having low resistance to the inductor 3. The inductor 3 stores a portion of the energy flowing through it in the magnetic field.

[0184] The automatic switch 4 is typically a MOSFET connected to a control circuit (not shown in FIG. 19). A transistor that switches between alternating states so that the current flows through it during the first part of the time. is allowed to flow through inductor 3 to ground during a second portion of the time. The inductor emits its stored magnetic energy as a current with a higher voltage than the photovoltaic cell. The current passes through diode 5, after which the power is available. The load flows to 6.

[0185] The automatic switch 4 can be fixed frequency or controlled from the transmitter or client load. and based on the current, voltage or temperature at the load, or based on the current, voltage or temperature at the automatic switch based on temperature, or based on a current, voltage or temperature emitted by the light / power converter 1, or may be based on some other indicator of the state of the system.

[0186] The receiver can be connected directly to a load 6 as shown in FIG. The load 6 may be external to the receiver or may be connected to another device such as a cell phone or other power consuming device. This device supports USB / Micro USB / Lightning / USB Type-C A receiver can typically connect to the receiving It further includes a load ballast used to dissipate excess energy from the device. is not required by the client.

[0187] In most cases, an energy storage device such as a capacitor or battery is connected in parallel with the load 6. Alternatively, the load 6 may include an energy storage device such as a capacitor or a battery. The device may include:

[0188] The transmitter 21 generates and directs a beam 15 to the receiver 22. In a first mode of operation The transmitter 21 searches for the presence of the receiver 22 using a scanning beam and detects the receiver using a communication means such as RF, light, IR light, UV light or sound By using a retroreflector or a retroreflective structure, a bar code, a high contrast pattern, A camera is used to detect a visual indicator of the receiver, such as a camera lens or other visual indicator. Once a rough location is found, the beam 15 is typically at low power and During such scanning, the beam 15 is When the beam 15 strikes the photovoltaic cell 1, the detector 8 detects It detects this and sends a signal to the controller 13 accordingly.

[0189] A controller 13 commands the laser driver 12 to vary the power P input to the gain medium 11. and / or command mirror 14 to alter either its scan speed or direction. change the position, steer or hold the beam in that position, and change the scan step rate The gain medium 11 responds to such signals by either or both of providing different powers P. When received from the laser power supply 12, the small signal gain, i.e., a single photon passes through the gain medium. The gain experienced when traversing the gain medium, without other photons traversing the gain medium at the same time. , changes. Photons directed between the rear mirror 10 and the output coupler 9 enter the gain medium When it passes through 11, more photons are emitted in the same direction as the beam 15, Optical resonance occurs between the laser 10 and the output coupler 9.

[0190] The output coupler 9 partially transmits the 6940 cm -1 In The first overtone of CH absorption and 8130cm -1 The space between the second overtone of CH absorption in The reflective surface operates at least in part at a wavelength of 100 nm, typically with alternating layers of different refractive index materials. The gain medium 11 may be made of glass, plastic, or a multi-layer dielectric or Alternatively, Fresnel reflection can be used if the gain medium provides a small enough signal gain. It can be used if it has a sufficiently high refractive index. Metal mirrors can also be used. If the gain medium is a semiconductor or fiber amplifier, A reflector may also be used. The output coupler 9 may also transmit a portion of the light. By using a diffractive optical filter, another portion of the light is extracted from the wave traveling forward inside the resonator, typically The third part is also a semitransparent optical component extracted from the wave propagating backward inside the resonator. The reflector may consist of a highly reflective mirror combined with a beam extractor such as a reflector component.

[0191] The back reflector 10 should be a highly reflective mirror, but with a small amount of light leaking back through it. These optical sensors are permitted to be used for monitoring or other purposes. The characteristic is 6940cm -1 The first overtone of CH absorption at 8130cm -1 C in It is necessary to operate in at least the part of the spectrum that lies between the -H absorption and the second overtone. Typically, different refractive index films are deposited on a substrate, which is usually glass, metal or plastic. It can be constructed from alternating layers of material. Alternatively, the gain medium can provide a small enough signal gain that it can be Fresnel reflection can also be used if it is possible to achieve this. Standard metallic mirrors can also be used. If the gain medium is a semiconductor or fiber amplifier, a Bragg reflector can be used. can also be used.

[0192] The gain medium 11 has a wavelength of 6940 cm -1 The first overtone of CH absorption at 8130cm -1 However, this spectrum is not necessarily This is because the laser driver 12 is excited with power P In this case, it is possible to deliver a small signal gain larger than the loss caused by the output coupler 9. The area, field of view and damage threshold are at least 8 kW / m2 / steradian / (1 -R), where R is the output coupler 9 This is 0.8-1.1 times the reflectance of the transparent host material doped with Nd ions. Semiconductor materials with bandgaps of 100 eV or simulating radiation in that spectral range The gain medium 11 is a reflective optical fiber that is rotatable from the back reflector 10. 3. Positioned in the optical line of sight to the force coupler 9 and thus reflected by the back reflector 10 The radiation is allowed to resonate between the back reflector 10 and the output coupler 9 via the gain medium 11. do.

[0193] A typical implementation in which the gain medium 11 is a semiconductor with a band gap of 0.8-1.1 eV. For this purpose, a heat extraction device is preferably attached and the laser driver 12 It can be electrically or optically excited.

[0194] The gain medium 11 is YAG or YVO4 doped with Nd ions. 4 , GGG, or glass In a typical implementation, the host is a transparent material such as a semiconductor or ceramic. The medium 11 is 9400 cm from the radiation resonating between the rear mirror 10 and the output coupler 9. -1 It is preferably in optical communication with a filter to extract nearby radiation.

[0195] Beam steering device 14 is shown controlled by controller 13. This is 15 can be deflected in multiple directions. Its area is tilted up to the maximum operating tilt angle. The beam 15 must be large enough to contain substantially most of the beam 15 even when the beam is No. Here is a simple 2D example. A beam 15 is collimated into a 5 mm diameter (1 / e 2 The beam is a Gaussian beam with a diameter of 100 mm, and the beam steering device is a single beam centered on the center of the beam. If the mirror is a rounded gimbal mirror, and the maximum tilt required for the mirror is 30 degrees, , and assuming that the beam steering device 14 has no other apertures, the mirror If the beam has a similar 5mm diameter, then at normal incidence of the beam, it will be approximately At a tilt angle of 60 degrees, the loss is approximately 60%. This power loss is shown in the graph of Figure 17 and in Figure 2 below. 2 and 23.

[0196] At the start of operation, the controller 13 commands the laser driver 12 and the mirror 14 to perform a seek operation. This is because the laser driver 12 operates in the first state to command the receiver 22 to This is done by pointing the beam 15 in the general direction in which a target is likely to be found. For example, if the transmitter is mounted in a corner of the ceiling of a room, the scan will be directed downward and The beam is transmitted to a receiver 22, which includes an optical / electrical converter 1, between two adjacent walls of a room. If 15 is hit, the detector 8 sends a signal, for example to the controller 13. If no such signal is received, In so far as this is the case, the controller 13 will instruct the beam steering unit 14 to steer the beam 15 in another direction to steer the receiver. When such a signal is received from the detector 8, the controller 13 starts the beam Command the steering unit 14 to stop or slow down scanning and lock onto the receiver. The controller 13 then indicates that the safety system 31 is safe to operate. and waits to generate a safety signal once such a safety signal is received from the safety system 31. , the controller 13 instructs the laser driver 12 to increase its power emission. Alternatively, the controller 13 may know the location of the receiver 22 and determine its location at a later stage. This can be done even without the safety signal being present.

[0197] As the laser driver 12 increases its power emission, the small signal gain of the gain medium 11 increases. As a result, the beam 15 carries more power and power transmission begins. Upon detecting a power loss greater than this threshold, the safety system 31 takes control of the situation. The controller 31 can then report its status to the laser driver 12. Command the change by reducing power to maintain the required safety level. Such power loss thresholds may be predetermined or dynamically set, and are typically At a level that represents a significant portion of the maximum permissible exposure level, typically the system noise figure Such a condition occurs when the beam 15 is no longer correctly directed to the optical / electrical power converter 1. that the equipment is not working properly, that any object has entered the path of the beam, or that a malfunction has occurred. Other indications of safe operation, e.g. through a user interface or API, may be provided. An indication from the user regarding the security of the transmission that may be displayed by the second security system or a security indication from a second security system. If there is an indication of full operation, the controller will increase power to the laser to compensate for the power loss. The controller 13 can also command the beam steering assembly 14 to It is also possible to instruct the search operation to be performed again.

[0198] There are two distinct stages in the exploration behavior. First, the robot searches for visual patterns. Using a camera capable of detecting retroreflectors, a high-contrast image is obtained, and (LED or other indication from the receiver (such as a flashing light from a A coarse search is first performed or the coarse search is performed by scanning features of the beam steering unit 14. This may be done by using a list of potential locations where the receiver may be found. The second stage is a fine search. Here, the beam steering mirror The laser 14 continues to receive the signal until the detector 8 signals that the beam 15 is impinging on the light-to-power converter 1. , all the while directing beam 15 onto a small area.

[0199] Now, in the schematic diagram of the optical / electrical power converter labeled as element 1 in Figs. 20, the beam 15 is a photovoltaic power source thermally connected to a heat removal system 107. The beam 15 strikes the force cell 106. The beam 15 is absorbed in the absorbing layer 108, causing a current to flow in the conductor 111. The current is typically collected by a bus. The absorbed optical power is typically converted to electrical power and heat. Most of the heat energy is transferred through the electrodes, while most of the heat energy is removed through the cooling system 107. The conductor 111 casts a shadow on the absorbing layer 108, reducing its efficiency. Therefore, the conductor 111 is 3×10 -6 As materials with specific electrical resistivity less than ohm*meter Such conductors must be made of highly conductive materials with thicknesses in the order of meters, i.e. At least (0.034*Pρ) / (V 2 *χ)m thickness. where P is the power absorbed by the photovoltaic element measured in watts. where ρ is the specific electrical resistivity of the conductor. V is the amount of current emitted by the photovoltaic cell at the maximum power point. is the voltage delivered and χ is the fraction of the area of ​​the absorbing layer that is covered by the conductor.

[0200] The absorbing layer must also be thick enough to absorb most of the beam 15 that impinges on it. To do this, the thickness, measured in meters, of the absorbing layer 108 is at least 0. .02 / μ 10 Here, μ 10 is a decimal number measured in 1 / m is the damping coefficient.

[0201] Reference is now made to FIG. 21, which shows a block diagram of the safety system 31 of FIG. The safety system 31 may be used in situations where the safety system is not an integral part of the controller 13 or where the safety system If the system is in an external control unit, inputs from various sensors and subsystems The safety system 13 also receives forces and transmits outputs to the controller 13. The system may also receive inputs from sensors and subsystems at times. Such inputs may include Required to primarily monitor wavelengths and estimate safety limits associated with the beam This can also be the shape, M 2 , Symmetry, polarity, power, divergence, coherence, and other parameters related to the beam and the above parameters. Information from the beam analyzer (401) that monitors the characteristics of the beam, among other information This also typically receives information measured by an external subsystem. , and is received via RF link 402. Various components in the transmitter, receiver and surrounding area A measurement of the temperature of the component can be provided by a temperature sensor 403. The image from the camera 404, which can be visual, thermal, IR or UV, or the power of the beam is varied In many cases, the image can be received from a power meter 406 that measures the power at the power station. , a primary sensor connected to a safety system 31 is moved across the beam path or its periphery. Or it may be an intrusion sensor (405) that monitors the beam for approaching foreign objects. It also receives inputs from other sensors such as current, voltage, smoke, humidity and other environmental sensors. Upon receiving these inputs, or at pre-scheduled times, The safety system 31 evaluates the potential for a safety violation and, if the evaluation exceeds a predetermined threshold, A notification is sent to the controller 13.

[0202] FIG. 1 shows a beam deflected by a mirror rotating on one or more gimbal axes. 22. The beam 15 strikes a mirror 332 that rotates about two axes in two dimensions. The beam 15 forms a spot 333 on the mirror 332 and is deflected in different directions. The importance of choosing the proper center of rotation and mirror dimensions can be seen in Figure 23. In FIG. 23, the mirror 332 is now rotated to The arm 15 is now deflected through a larger angle compared to FIG. 22. Thus, spot 333 now projects a longer length onto the mirror 332 than the effective length of the mirror. As a result, a significant portion of beam 15, i.e., labeled as 333A, is formed on the surface. The portion of the mirror 332 that is in contact with the surface of the mirror 332 overflows. This overflow reduces the brightness of the beam 15 to that of the mirror 332. This is achieved by both reducing power and by clipping the edges. In most cases, the beam quality in the far field is degraded. Typically, the beam diameter is If it is reduced in the near field close to the mirror or in the near field image, it will be increased in the far field. To achieve a minimum dimension system that operates with relatively high efficiency, the highest possible It is important to maintain a high level of brightness across all angles within the system field of view. This can be achieved by reducing the brightness loss experienced by the beam 15 during the rotation of the mirror. The center is the weighted average of the beam intensity, the cross-sectional diameter of the beam at constant intensity, and the ellipse through which the beam passes. The mirror is positioned so that it is substantially close to the center of the beam measured by either the center of the circular aperture. Note that, as opposed to the projection of the length, the beam on the mirror The width of the projection does not change with impact angle.

[0203] Figure 24 shows a schematic representation of the intensity profile of a typical beam. Contour 1 is at 90° of maximum intensity. Contour 1 marks the 80% maximum intensity line, contour 2 marks the 80% maximum intensity line, and contour 3 marks the FWHM (full width at half maximum) intensity line. Contour 4 is labeled with a 1 / e degree line, and contour 5 is labeled with a 1 / e intensity line. 2 Labeling the intensity lines and contours 6 is 1 / e 4 The intensity line is labeled. Point 231 is approximately the weighted average point of the beam. point 232 is at the center of the first contour, point 233 is at the center of the sixth contour. These are all valid points for locating the center of rotation of the mirror. Therefore, in order to set the center of rotation beyond that point, the gimbal mirror must be high enough A large mirror is required to maintain radiance efficiency.

[0204] It is also important to maintain high radiance efficiency relative to other components. The gimbal mirror and first lens that track the laser typically have limited radiance efficiency. It is a constant component.

[0205] FIG. 25 shows a schematic side view of a laser diode taken perpendicular to the fast axis of the laser. Also shown is a lens 242 which is typically used for steering and generally collimates the fast axis. In most cases, lens 242 is a compound lens that contains several optical elements. Laser 241 is connected to heat sink 243 and emits beam 15 onto interface layer 244 . The interface layer 244 has a refractive index n for the wavelength associated with the beam 15. The value of n is , 1.000293 for the air interface at 532 nm and 1.000293 for oil or optical cement. The beam 15 has a divergence in at least one direction. The FWHM contour of the beam 15 in front of the The lens has a diameter d defined as the maximum distance between the lens and the sphere. 42 is at least one for the emitter of the laser 241

number

[0206] If a lens with a small numerical aperture is used, the radiance of the beam is This reduces the signal quality and results in poor system efficiency or large receivers. Using a small NA can also result in heating of the lens holder. This causes two detrimental effects. First, thermal expansion causes the lens to move away from its optimum Secondly, a force is applied to the lens, causing it to distort. This reduces its optical quality and, as a result, the radiance of the beam. Additionally, a small NA can also result in reflections back towards the laser, which can interfere with the laser mode. This can further reduce the radiance of the original beam. The light emitted from the edge of the lens is harmful to the radiance of the lens. If used, other parts of the system, e.g., beam monitors, tracking sensors in the system may interfere with the operation of the laser, the laser beam or other optical elements, or may affect other parts of the system. This can cause excessive heating which can interfere with the operation of the

[0207] Reference is now made to FIG. 26, which shows a block diagram of the laser protector 251. As mentioned above, The safety system 31 evaluates the potential for a safety violation and, if such potential exceeds a threshold, The controller 13 then notifies the laser driver 12 of the beam 1 The laser may be a laser that emits 5 or may be used to excite a gain medium that is used to generate the beam 15. 2. Command to stop or reduce the power supplied to the laser 252 that may be the laser causing the Such a cutoff of power must be very fast. When the power supplied to the laser driver is suddenly turned off or reduced, a negative charge is generated in the conductor carrying the laser driver current. Pressure can develop (if it is an electrical conductor) and damage the laser 252. To prevent such damage, a laser protector 251 is provided between the laser driver 12 and the laser 25. 2, typically near the laser 252. The laser protector 251 is typically Generally, diodes or equivalent circuits / components, e.g. Zener diodes, ballast or a circuit designed to quickly drain such excess negative voltage between current conductors. By connecting the conductors together, the laser 252 is protected from negative voltages. current flows through a protection diode or equivalent circuit, The laser protector 251 also detects over-temperature or over-current conditions. By attenuating the power sent to the laser 252 when a flow is detected, the laser It can also be used to protect against overheating or against electrical current surges.

[0208] It will be appreciated by those skilled in the art that the present invention is not limited to that particularly shown and described above. Rather, the scope of the present invention encompasses any and all combinations and subcomponents of the various features described above. Both of these combinations, as well as those which would occur to one of ordinary skill in the art upon reading the above description, exist in the prior art. This invention includes variations and modifications thereof.

Claims

1. 1. A system for secure wireless power transmission to at least one receiver, comprising: A transmitter is included. The transmitter includes: Approximately 6940 cm －１ Approximately 8130 cm －１ a laser resonator for emitting a laser beam having a wavelength between a beam steering device adapted to direct the laser beam towards a receiver; a controller adapted to receive a signal from the receiver and to control one of a beam power of the laser cavity and a direction of the beam steering device in response to the received signal; Including, The receiver includes: a light to power converter that produces a current at a first voltage; a voltage conversion circuit for converting a current at the first voltage into a current at a second voltage; a sensor for determining a temperature of the light-to-power converter; a signaling element adapted to transmit to the transmitter information indicating that the laser beam is impinging on the optical / power converter as well as information regarding a temperature of the optical / power converter; Including, The system, wherein the controller is adapted to increase safety of the system by modifying the power of the laser beam in response to information being transmitted indicating that the laser beam is impinging on the optical / power converter and information regarding the temperature of the optical / power converter.

2. the signaling element is further adapted to transmit information regarding an identity of the receiver to the transmitter; The system of claim 1 , wherein the controller is adapted to modify a power of the laser beam in response to an identity of the receiver.

3. The system of claim 1 or 2, wherein the signaling element transmits the information to the transmitter over a communication channel.

4. The system of claim 3 , wherein the communication channel uses any of RF, IR, visible light, UV, modulated beam, TCP / IP, or sound.

5. 5. The system of claim 1, wherein the controller is configured to reduce the power of the laser beam in response to an increase in temperature of the light-to-power converter.

6. The system of claim 5 , wherein the reduction in power of the laser beam by the controller enables an increase in conversion efficiency of the light-to-electrical power converter to be achieved.

7. The laser beam is 800 kW / m ２ 7. The system of claim 1 having a radiance of 1 / steradian.

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