System for optical wireless power supply

Abstract

To provide a system and method for optical wireless power transmission to a power receiving apparatus generally situated in a mobile electronic device.SOLUTION: An optical wireless power supply system includes a transmitter 21 comprising an optical resonator with end reflectors and a gain medium 11 positioned between them, such that an optical beam 15 is generated. The frequency of the beam is selected such that it is absorbed by almost all transparent organic materials in general use. A beam steering unit positioned on the transmitter can direct the beam in any of a plurality of directions, and the beam is absorbed on a receiver 22 by means of an optical-to-electrical power converter 1, through a low reflection surface.SELECTED DRAWING: Figure 16

Description

[Technical field]

[0001] The present invention relates to the field of wireless power beaming, in particular to transmitting optical power to mobile electronic devices in a domestic environment. This invention relates to the use of a laser-based delivery system for delivering a beam to a target. [Background technology]

[0002] There has long been a need to transmit power to remote locations without the need for physical wire connections. This demand is driven by portable electronic devices that run on batteries that need to be periodically recharged. These applications have become important over the last few decades as mobile devices have become more popular. This includes phones, laptops, cars, toys, wearable devices and hearing aids. Conventional and general battery applications in intensive smartphone use The capacity status is determined by the remote control since the battery may need to be charged more than once a day. There is a growing demand for fast wireless battery recharging.

[0003] Battery technology has a long history and is still in development. Franklin describes the first battery made from a Leyden jar, the first source of electrical power and resembled the Canon battery (hence the name). In 800, Volta invented the much more portable copper-zinc battery. The lead-acid battery, a rechargeable battery, was invented in 1859 by Gaston Planté. Since then, the energy density of rechargeable batteries has increased by at least eight times. The number of different rechargeable battery chemistries is increasing, as shown in Figure 1. Energy density, both mass and volume parameters, from the first lead oxide chemistries to today's lead oxide chemistries, A tungsten-based chemistry and a zinc-air chemistry are shown. The power consumed by electronic devices is such that several full battery charges are required in a day. It reached that point.

[0004] Between 1870 and 1910, almost a century after the invention of the battery, Tesla used electromagnetic waves Since then, there have been many attempts to transmit power safely over long distances. has been implemented over distances significantly greater than the transmitting or receiving device. This effort was started in the 1980s by the Stationary High Power Plant (SHARP) h Altitude Relay Platform) project Marin Soljaci of ASA, who experienced a system similar to Tesla in 2007 Pass to c.

[0005] However, to date, only three commercially available technologies are safe and wire-free. Power can be transferred to a mobile device, i.e. Magnetic induction - typically limited in range to just a few mm. Solar cells - at normal (safe) room lighting levels available from sunlight or artificial lighting. When illuminated, a cell phone-sized light cannot generate more than 0.1 watts. Energy harvesting technology - converts RF waves into usable energy, but RF signal transmission is not good for health and FC C regulation, it is not possible to operate it above 0.01W in current practical situations. I can't do that. At the same time, the capacity of typical batteries in portable electronic devices ranges from 1 to 100 watts. t × hr and generally require daily charging, so more power transfer over longer distances will be necessary.

[0006] Therefore, over a few meters, safe and reliable power supplies, typically equipped with rechargeable batteries, are required. There is an unmet demand for delivering power to portable electronic devices.

[0007] Some attempts to transmit power in residential environments have been made using collimated or essentially This has been done using collimated electromagnetic waves. Commercial availability on the public market is currently restricted. There are a few issues that need to be resolved before the system can be released. The system developed must be secure. The system developed must be cost-effective. The system developed must be able to withstand the hazards of a typical home environment. These include contaminants such as dust, fingerprints or liquid leakage, vibration, beam interruption, defective ink This includes stalling or continually dropping to the floor.

[0008] Currently permitted public exposure levels for transmitting laser power levels are subject to complex safety considerations. There is not enough power to provide a useful amount of electricity without the entire system. Code of Federal Regulations, Title 21, Volume 8, (21 CFR Section 8), 2014 April 2013, Chapter I, Subchapter J Part 1040, specifies that optical products, including laser products, It sets performance standards for emission products. For wavelengths outside the visible range, it defines Class I and Class II. Ib and Class IV lasers (Classes II, IIa, and IIIa are 400nm to 7 10 nm for visible lasers. Class 1 is considered safe for general public use, and classes IIIb and IV are considered safe It is believed not to be the case.

[0009] Referring to Figure 2, a graph showing the MPE (maximum permissible exposure) for 7mm is shown. The pupil diameter for Class I lasers is as follows, per 21 CFR Section 8 referenced above: For example, the exposure time is 0.1 to 60 seconds. As is clear from the graph above, (i) The maximum permissible exposure level generally (but not always) varies with wavelength. increases with (ii) Persons entering the beam to meet the requirements of 21 CFR section 8. Even if the laser is turned off in about 0.1 seconds after the laser is turned on, the laser output is 1.2 times slower at wavelengths longer than 2.5μ. They cannot transmit more than 5W of light, and at shorter wavelengths the regulatory limits are even smaller. Therefore, without some sort of safety system, only a few milliwatts of laser power can be transmitted. It cannot be used for transmission, and even if it could be fully converted to electricity at this level, it would be portable. It can provide significantly less power than is needed to charge a mobile electronic device. A mobile phone, for example, requires between 1 and 12 W to charge, depending on the model. .

[0010] A safety system is required to transmit high powers that exceed those of a Class 1 laser MPE To the best of the applicant's knowledge, there are no residential areas accessible to untrained persons. Systems capable of transmitting significantly greater power levels at these boundaries are not yet commercially available.

[0011] It is difficult to build a robust and secure system. Fingerprints and dust scatter the laser light. It is known in the art that high powered light can cause a disturbance in the light and transparent surfaces can reflect or scatter it. To transmit the signal, a Class IV (or IIIb) laser is required, which is reliable. In Class IV lasers, divergent radiation from the main beam is also a hazard. 21 CFR Section 8, revised April 2014, Chapter I, Subchapter According to J Part 1040, a laser that irradiates at 400 nm to 1400 nm, Anything over .5W beam power is considered a Class IV laser for exposures longer than 0.5 seconds. It is generally considered that even scattered radiation from such lasers can be dangerous. A warning label equivalent to that shown in Figure 3 is required, including a warning for "scattered radiation." Laser users are generally required to wear safety goggles. Generally, these aspects are performed by trained professionals who are able to charge mobile electronic devices. The acceptable conditions for using domestically available laser power transmission systems for this purpose are very different.

[0012] In the prior art, the reflection is generally blocked in case it occurs. Combined with an ingenious beam blocking structure, the surface is reflective to prevent such reflections. However, the AR-coatings used in the prior art The cleaning solution is to remove dust or spilled liquids from the surface, or to remove improper cleaning. They are prone to failure due to coating wear and tear caused by leaning. Beam block solutions typically severely limit the system's field of view and are difficult to implement with modern portable devices. Large relative to the dimensions of the child device.

[0013] Therefore, in the prior art, scattering and reflection of the power beam in unwanted directions is prevented. There is a lack of reliable "small footprint" mechanisms for Such scattering and reflections can occur when a transparent surface is inadvertently placed between the transmitter and receiver. The exterior surface of the system may be made of many different transparent materials, Due to the optical properties of its transparent surface resulting from spills and fingerprints that may accumulate on the front surface of the receiver. obtain.

[0014] A third problem with the solutions suggested in the prior art is that the safety systems are generally powered. A mechanism to ensure precise alignment of the beam system is required, and the safety system must be installed on both systems. The stem is coaxial and the power beam is sufficiently divergent or sufficiently attenuated (or both) factors and any other combination of factors) exist and ensure that safety limits are not exceeded. This requires a collimated class IV or IIIb laser beam. This is extremely difficult to achieve and does not generally scale with distance, so it is not possible to The safety limit is exceeded over a distance.

[0015] One prior art principle of operation used to construct such a safety system is a beam The objective of the present invention is to detect light from a transparent surface that can be placed in the path of the beam. The transparent surfaces that can be used can be constructed from a wide variety of different transparent materials and can be coated with an anti-reflective AR. or may be positioned at an angle close to the Brewster angle so that the beam is absorbed. However, the light absorption level of each material is This difference is quite large and can be negligible, making it very difficult to configure optical systems that rely on optical absorption. The system is complex because the materials are special and many of the available materials are very large. They tend to be large and costly, and if not properly designed, can be unreliable. This is especially true when you take into account that it is a critical safety system. Relying on reflection to provide attenuation is also problematic, and the surface must be anti-reflective coated. The ion beam may be coated with a fluorine-containing coating and positioned at an angle close to the Brewster angle relative to the beam. So, for a particular location on the surface there may be a minimum of reflection.

[0016] Thus, it overcomes at least some of the disadvantages of prior art systems and methods. Therefore, there is a need for a laser power transmission system that has built-in safety features. The disclosure of each of the publications mentioned in this and other sections of the specification is incorporated herein by reference in its entirety. Summary of the Invention

[0017] Since many of the reflective materials used domestically are plastic, the disclosed approach is The light beam used in the remote device is absorbed by the overwhelming majority of transparent organic materials. and detecting when plastic or other organic material is inserted into the beam. This is because the light emitted from plastic materials is essentially transparent at certain wavelengths. To achieve this goal, a transparent plastic object is placed in the beam. By properly inserting the laser power transmission system, it provides good protection against accidental reflection. It could be.

[0018] Measure the absorption / transmission spectra of all transparent materials to determine their optical properties It is not feasible to do so, and there are many such materials, many of which are currently being evaluated. Since we literally do not have readily available absorption spectra that can be used, A systemic approach is needed.

[0019] When placed in a beam, it is possible to determine whether an object is opaque or partially defective by measuring the attenuation of the beam. Even transparent materials can be easily detected. Some materials are nearly transparent, making it extremely difficult to detect them. There are two major groups of solid transparent materials: organic and inorganic. The number of inorganic transparent solid materials available is very limited. They are glass, the commonly used Some semiconductor materials, quartz, and some other materials such as diamond, ruby, and calcite are It is mostly composed of a few naturally occurring materials. It is possible to configure a system to detect reflections from inorganic transparent materials to cover a wide range of scenarios. It is. On the other hand, there are many different organic, transparent materials available to the public, and new transparent materials are constantly being developed. This allows the optical characterization of this group. There are huge problems with this, making it virtually impossible.

[0020] Polymers are an important group of transparent organic materials and illustrate the intent of the method of operation of the present invention. Polymers are generally made up of a series of monomers. The polymers are generally made up of either carbon or silicon chains. 4 to 9 show the chemical structure of some commonly used transparent polymers. The chemical structure of the PMMA chain is shown in Fig. 4, and that of the polycarbonate chain is shown in Fig. 5. Figure 6 shows the structure of polycarbonate, Figure 7 shows the structure of nylon 6,6 , FIG. 8 shows a polypropylene chain and FIG. 9 shows a polyethylene chain structure.

[0021] As can be seen, the chemical structures of the illustrated sample polymers are very different and The absorption spectrum of a polymer depends on many factors, including the density of the material, the amount of reagent present, and the chain length. However, all the above mentioned transparent polymers have some common chemical bonds, especially CC It is observed that there are bonds and C-H bonds. This is particularly true for the system of the present disclosure. This is true for commercial polymers that are almost entirely based on organic materials, which can be detected Alternatively, silicone, polysilane, polygermanium, etc., which can be detected by the system of the present disclosure. Semi-organosilicon-based polymers such as polyphosphorsene and polystannane, or polyphosphazene This is also true for polyphospahazenes. Apart from that, most transmission spectrum data that is not based on carbon chemistry can be easily obtained. The number of transparent materials available to the general public, consisting mostly of various types of glass available is very limited.

[0022] The laser strikes either the vibrating CH bonds in the polymer, or the equally vibrating C-C bonds. If the system is designed to excite one of the polymers, Once in place, it can be easily detected by monitoring the power drop due to the polymer. This is because absorption by C-H or C-C bonds always exists, and the laser It is assumed that the wavelength and the wavelength of interest always coincide. Rotational peaks are used for this purpose. It is possible to measure the absorption of vibrational CH absorption ( or CC absorption) is more suitable for this purpose.

[0023] See Figure 10, which shows a chart of typical absorption areas for different polymer bonds. ~3200cm -1 The CH stretching vibrations around the periphery occur in most of the polymers shown. Therefore, the change in transmission power caused by the absorption band is used to It can be used to trigger an absorption mechanism for a safety system. However, these absorption bands have two drawbacks that make them difficult to use for this purpose. (i) CH vibrational absorption lines are generally very sharp, and their exact frequencies are within one The laser can excite one polymer but not the other, so the photoinduced polarization of the polymer changes significantly from one polymer to another. However, it may not be possible to excite other polymers. If the laser is not precisely tuned to the CH vibration line, it will not be absorbed. (ii) The CH vibration peak is generally an intermediate absorption peak and is observed in material sections several mm thick. The beam attenuation due to the beam splitting is 20-50% (i.e., even trace amounts of material in a small container can be detected). can be emitted), but it has medium (20~70% attenuation per cm of material) and strong (7% per cm 0% attenuation) absorption peaks are generally easy to detect, but to build a robust system It cannot be used to

[0024] Fingerprints are a common challenge for commercial systems, as they are designed for consumer environments. In normal operation, the system can easily fail, even if there is a fingerprint on it. is not permitted, and instead the system will stop transmission if there is a risk of exceeding safety standards. To do so, any fingerprints on the receiver should be removed from the system. The system should detect something blocking the beam but not stop transmitting. Strong or Medium If absorption peaks between the receiver and the transformer are used, fingerprints or other contaminants may be present. Even if it is attached to the outer optical surface of the emitter, it will strongly absorb the beam and therefore will not transmit power. This happens because fingerprints also contain organic compounds that absorb the beam, causing uncontrollable Generally, organic material such as fingerprints on the surface of external optical components can cause system failure. The safety system is designed to operate in an environment where dust may adhere to the system. The laser beam is successfully aimed at the target while detecting dangerous transparent items inserted into the target. However, it is necessary to build a system that can pass fingerprints. If a weak absorption band is used instead of an intermediate or strong absorption band, the system continues to operate with the fingerprint and can be stopped in a controlled manner based on electronic decision making.

[0025] Returning to the CC absorption band, 800 cm -1 ~1300cm -1 The elastic band is wide Since the narrowband laser is a band, it can hardly absorb the narrowband absorption peak in this region. It cannot be detected. The peak is at 800 cm. -1 From 1300cm -1 Can be located in the range However, their typical width is very narrow and cannot be easily detected by narrowband lasers. Furthermore, as can be seen in Figure 11, which is described below, some polymers The do has disappeared, and the 800-1300 cm -1 No absorption peak was observed between the C-C bonds. There may be some polymers in which aromatic carbon-carbon bonds, i.e., C= It is replaced by C bonds and COC bonds.

[0026] Another problem arises due to the intensity of the CC absorption lines. In symmetric compounds such as polyethylene, While some compounds are nearly impossible to detect, others are so strong that they can overwhelm the receiver. Even a weak fingerprint on the surface can make the system inoperable, with most of the power going to the fingerprint. Fingerprints on optical surfaces can be absorbed by the To allow the system to operate in a way that is consistent with weak, non-uniform interactions between different polymers, However, a not too weak absorption line is required, which is found in most organic polymers and has a peak A laser tuned to that peak should be used in conjunction with a system operating around the As can be seen from FIG. 10, the commonly used polymers and the illustrated absorbent bag There is no such peak in the

[0027] According to an exemplary implementation of the system described in this disclosure, optical wireless power is transmitted to a power receiving device. A system for transmitting (a) an optical resonator having a terminal reflector and used to emit a light beam; (b) a gain medium disposed within the optical cavity, the gain medium having a first bandgap energy. a cooling system configured to amplify light passing through the gain medium; the gain medium; (c) a driver that provides power to the gain medium and controls a small signal gain of the gain medium; (d) a beam splitter configured to direct a light beam in at least one of a plurality of directions; A steering device; (e) an optoelectronic power converter configured to convert the light beam into electrical power having a voltage; the photoelectric power converter having a second bandgap energy; (f) converting the voltage of the electrical power generated by the photoelectric power converter to a different voltage. 1. An electrical voltage converter configured to: the electrical power converter having a device and a switch; (g) at least one surface associated with the photoelectric power converter, the surface being a surface optically disposed between a body and the photoelectric power converter; (h) configured to provide a signal indicative of a light beam impinging on the photoelectric power converter. A detector for detecting the (i) controlling at least one of the state of the beam steering device and the state of the driver; a controller configured to receive a control input signal from at least the detector; and a controller for controlling the (j) the at least one surface reflects a portion of light incident thereon as follows: (i) diffusely or (ii) reflects light reflected from said surface in a coherent manner. or (iii) the reflected light has a virtual focus located away from the oscillator. The optical cavity is reflected from the surface to have a real focus located at least 1 cm away from the surface. , (k) a controller responsive to a control input signal received from the detector; (ii) causing a driver to vary the small signal gain of the gain medium; and (iii) changing the power supplied by the driver; and (iv) changing the power supplied by the driver. (v) varying the scanning speed of the beam steering device; (vi) recording a scan position defining a position of said photoelectric power converter. Do one of the following: (l) The gain medium is a semiconductor device or solid-state host doped with Nd ions, Number 8, 300cm -1 From 12,500cm -1 At least one frequency in the range a filter for attenuating radiation of (m) the second band gap energy is greater than the first band gap energy; Also small, (n) the first band gap energy is in the range of 0.8 eV to 1.1 eV; (o) The closed series resistance of the switch is less than R, given by:

number

[0028] In an alternative implementation of any of the above-described systems, the photovoltaic power converter is a solar cell. In that case, the solar cell may be a III-V device. The series resistance of the photoelectric power converter may be less than 1 ohm. According to a further implementation of the above system, the inductor is measured in ohms. The measured series resistance is the fraction of the first band gap energy measured in Joules. Squared to 2 x 10 -40 and multiplied by the driver power measured in watts. In other implementations, the energy storage device is a capacitor or a rechargeable battery. It could be either Lee. Additionally, any of the above-described systems may further include a retroreflector. It can be electrically or optically pumped by a driver. The energy can be greater than 50% of the first band gap energy.

[0029] Yet another implementation provides a method for transferring power from a transmitter to a receiver. The method comprises: (a) The first power is about 6940 cm -1 The first and second overtones of CH absorption located at and converting the electromagnetic wave into an electromagnetic wave having a frequency between Both are 8kW / m 2 / steradian, and the converting step includes an optical resonance having a terminating reflector. and a gain medium coupled to a laser driver receiving a first power; The gain medium has a first band gap energy between 0.8 eV and 1.1 eV, Located inside the optical cavity, it is thermally bonded to a cooling system and acts to amplify the electromagnetic waves passing through it. A process configured as follows: (b) using a beam steering device controlled by a control unit to steer said electromagnetic waves in at least one of a plurality of directions; (c) detecting the impact of the beam on a target having a partially transparent surface, using a control unit to (i) vary the small signal gain of the gain medium upon occurrence of a collision; (ii) varying the radiance of the electromagnetic beam; and (iii) varying the first power. (iv) varying the scanning speed of the beam steering device; and (v) adjusting the scanning speed of the beam steering device. (vi) changing the scanning position of the steering device; recording the location; (d) a second band gap energy smaller than the first band gap energy; and converting the electromagnetic wave into a second power having a voltage using a photoelectric power converter having a The process and (e) converting the voltage to a different voltage using an electrical voltage converter; The electrical voltage converter comprises an inductor, an energy storage device, and a having a switch with a closed series resistance less than the R obtained.

number

number

[0030] where f is the switching frequency measured in Hz. 利得 is the gain medium is the band gap of the 出力 is the output of the voltage converter is the power voltage, measured in volts, and P レーザドライバ is measured in watts The power is determined by pumping the gain medium with a laser driver. Furthermore, the detection of the beam impingement on the target is achieved by tracing the retroreflected irradiance from the target. The transmitter detects the target illumination, or the receiver sensor detects the target illumination. This can be done by: Furthermore, in any of the above methods, the second band gap energy is The band gap energy can exceed 50%.

[0031] The present invention will be more fully understood from the following detailed description taken in conjunction with the drawings, in which: It will be possible to do so. Figures 4-9 show examples of the chemical composition of various commonly used transparent polymers. [Brief description of the drawings]

[0032] [Figure 1]FIG. 1 illustrates the energy density of various battery chemistries. [Diagram 2] Shows the maximum allowable exposure values ​​for lasers according to US Code of Federal Regulations, Title 21, Volume 8, (21CFR Section 8), revised April 2014, Chapter I, Subchapter J Part 1040, for various exposure times. [Diagram 3] Illustrates examples of warning signs for Class IV laser products. [Figure 4] Polymethylmethacrylate (PMMA) chains are shown. [Diagram 5] The structure of polycarbonate is shown. [Figure 6] The structure of polystyrene 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] The IR absorption bands for common organic chemical bonds are shown. [Figure 11] 1 shows an IR absorption spectrum of polyethylene. [Figure 12] Overtone absorption bands for some common organic chemical bonds are shown. [Figure 13A] 1 illustrates different electronic circuit configurations for converting the output voltage of a solar cell to different voltages. [Figure 13B] 1 illustrates different electronic circuit configurations for converting the output voltage of a solar cell to different voltages. [Figure 14] The power reflected per square meter by a mirror as a function of the numerical aperture when a beam of radiance 8 kW / m2 / steradian is incident on the mirror. [Figure 15A] 1 shows a schematic diagram of an exemplary apparatus according to the present disclosure for avoiding unsafe reflections from a receiver front surface illuminated by a transmitter of the present disclosure. [Figure 15B]1 shows a schematic diagram of an exemplary apparatus according to the present disclosure for avoiding unsafe reflections from a receiver front surface illuminated by a transmitter of the present disclosure. [Figure 15C] 1 shows a schematic diagram of an exemplary apparatus according to the present disclosure for avoiding unsafe reflections from a receiver front surface illuminated by a transmitter of the present disclosure. [Figure 16] FIG. 2 is a schematic diagram showing a more detailed description of the complete optical wireless power supply system of the present disclosure. [Figure 17] 17 is a graph showing the variation of power transfer in the system of FIG. 16 versus the tilt angle of the beam steering mirror. [Figure 18] FIG. 17 shows a schematic diagram of a cooling system for the gain medium of the system of FIG. 16. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0033] From the above considerations, in one exemplary implementation of the optical wireless power supply system of the present disclosure, 0cm -1 The first overtone of CH absorption at 8130cm -1 Second overtone of CH absorption at The harmonic band in question is a lesser known band. It does not contain much chemical information, and is essentially a forbidden quantum mechanical transition. are caused by and permitted only by complex mechanisms. It provides a wide, weak absorption band, which is quite suitable for this application, but is not suitable for analytical chemistry. It turns out that it doesn't really matter. The broad nature of the bands allows for a variety of different Although polymeric compositions can be detected, the weak absorption makes the system vulnerable to organic stains and fingerprints. This makes these lines unsuitable for general use in absorption measurements. Although not very useful, they are ideal for the present invention. Another useful point about these lines is that they are There are no common absorption lines directly in the waveband, so the chemical composition of the material can be changed. The measurement results are not significantly affected by the amount of noise. The diagram is shown in the figure.

[0034] Possibly both diode lasers and diode-pumped, solid-state (DPSS) lasers. These frequencies are extremely inefficient, so electro-optical components that operate in these bands are rare. Lasers with the desired power at the desired frequency are expensive and difficult to source, and only low-power lasers are currently commercially available. Lasers with these parameters are not currently available, so a new laser suitable for this use has been designed. The resonator and gain medium also need to be designed. The frequency and frequency selection are sufficient to form a collimated or nearly collimated beam. A laser with a high radiance value and a good collimation of the beam must be constructed. To achieve this, the radiance must be at least 8 kW / m 2 / steradian is needed, and and an additional 800kW / m for high power systems for efficient power transmission. 2 / Ste Radians may be needed. For small systems operating at large distances, a similar principle can be used Higher radiance (10GW / m 2 / steradian) may be designed in the future. Receivers used with radiances smaller than those of the transmitter must be very large, but this is due to the This makes the system difficult to use.

[0035] Different mirror setups are used for the resonator, especially the high quality metallic mirrors are gold. These are made of silver or aluminum, which significantly reduce the efficiency of laser oscillation. It has been found that better results can be achieved with a dielectric material mirror. Alternatively, Fresnel mirrors have the advantage of being low cost. The mirror is a Bragg mirror (which can be a dielectric). Stable or nearly The mirrors must be positioned to form a stable cavity, where the inside of the laser Photons are confined in space by a barrier (such as in a fiber or diode laser). and a gain medium is disposed within the cavity between the mirrors, at which point the gain medium is disposed within the cavity. The beam can be amplified to resonate at 1000 Hz and has a radiance of at least 8 kW / m 2 / Stellasia It is.

[0036] If the gain medium can be traced over a distance greater than one wavelength, the dielectric mirror will Alternatively, the filter can be selected to limit the racing frequency to a specific value. It can be used for fixing.

[0037] In particular, Miller is 6940cm -1 The first overtone of CH absorption at 8130cm -1 In It is advisable to have high reflectance at at least one wavelength between the second overtone of the CH absorption.

[0038] Three different approaches may be used for the gain medium. 1.DPSS design In DPSS designs, the gain medium is YVO 4 Crystals, GGG crystals and glasses are also available upon request. A clear host may be used, but Nd-doped YAG crystals may also be used. Nd is about 7450 cm -1 Since it has a transition near the first overtone of the CH band and CH Neodymium is best suited for operation between the second overtone of the band. Nd ions are commonly used. must be excited by absorbing radiation from an 808 nm laser diode, Other wavelengths may also be used. -1 A filter that blocks surrounding transitions is a resonator. If no additional radiation is added to the cavity or if no unwanted radiation is extracted from the cavity, Nd Ni-based gain media tend to be available for lasers at higher frequencies. If a filter is added, the lacing is 7440-7480 cm -1 Start with Such a filtering action can be achieved either in place of a filter or by appropriate chromatic design of the laser cavity. This can be achieved using prisms or diffraction gratings. 2. Semiconductor laser As an alternative, a semiconductor-based design may be proposed. It is possible to tune the wavelength of a semiconductor laser by changing the band gap. Semiconductors with a band gap of 1 eV, particularly III-V group semiconductors, Although not limited to this, quantum dot types have a wavelength of 6900 cm -1 ~8200cm -1 Between The band gap between 0.8 eV and 1.1 eV is particularly good. The results are consistent with essentially all commonly used polymers, at least in part. is absorbed effectively. 3. Nd-doped fiber, which may include a Bragg mirror and / or a fiber loop mirror. Various alternative designs, such as a bar laser, may also be used in the systems described in this disclosure. Alternatively, a Raman shifted fiber laser can be used.

[0039] During operation, the gain medium heats up and must be cooled to avoid wavelength shifts and loss of efficiency. If the gain medium is properly cooled, the 6900 cm -1 ~8200cm - 1 At least 8 kW / m for frequencies between 2 A beam with a radiance of 1 / steradian is emitted. The excitation power or current can be increased until the beam is almost completely focused. It is collimated by the light and attenuated by most organic materials, including polymers, making it detectable. However, it is not strongly absorbed by contaminants such as fingerprints.

[0040] Laser gain media are typically constructed to operate at temperatures below 150 degrees Celsius. When that temperature rises to levels typically above 250 degrees Celsius, a number of problems arise. First, the increase in low-level excited states, especially in three- and four-level lasers, and in semiconductor Thermal recombination of charge carriers can also significantly reduce the luminous efficiency. Second, the soldering of the gain medium is lossy if such a thermal attachment method is used. May be injured. Third, thermal aberrations can occur that can degrade the beam. Fourth, it creates a thermal expansion of the laser gain medium that is different from the thermal expansion of the surroundings, which causes mechanical stress. This can cause the gain medium to warp or even fracture.

[0041] For these reasons, among others, the gain medium must be thermally attached to a cooling system. Generally, the gain medium is 1 mm 2 ~40mm 2 Between 0.1 and 100 from the surface The gain medium is cooled to keep the temperature below 150 degrees. The system must have a thermal resistance of less than 200 Kelvin / Watt, typically 10W. For systems transmitting high power due to power inputs exceeding 1000 Hz, the thermal resistance must be significantly lower. In many cases, a thermal resistance of less than 0.05 Kelvin / Watt is required.

[0042] The cooling system surface is attached to the gain medium and is typically made of a third material such as solder or adhesive. A material is used that is dependent on both the expansion coefficient of the gain medium itself and the expansion coefficient of the front surface of the cooling system. The expansion coefficient must be compatible.

[0043] Common cooling systems include passive heat sinks, heat sinks with fans, and fanless heat sinks. A Peltier element connected to a heat sink with or without a fan, or cooled by a fluid. Alternatively, it may be a circulation pump-based actively circulating or or a heat pipe-based passively circulating stand-alone fluid circulation cooling system. may be used.

[0044] If the cooling system consists of a heat sink with a fan, its thermal resistance is 0. It should be less than 1° Kelvin / Watt. If the cooling system is a passive heat sink, its thermal resistance is 0.3°K / It should be less than a watt. If the cooling system is a Peltier component, generate a temperature difference ΔT of at least 5 degrees It is necessary. If the cooling system is an active fluid cooled cooling system, the cooling system described herein It is necessary to be able to cover the entire range of thermal resistance that can be achieved.

[0045] Passive heat sinks are preferred in systems designed for low cost and quiet operation. For high power systems, a fluid cooled system is preferred. For systems with transmitters that exceed 1000W and have a small volume, such as less than about 1 liter Typically, a heat sink with a fan or a fluid pump is used.

[0046] Typically the gain medium is driven by a driver that provides power and is some type of semiconductor gain medium. In some systems, it is supplied as electrical power, or in other semiconductor gain media or DPSS systems, it is supplied as optical power. It can be supplied as electricity, or as chemical or other forms of energy. The amount of power delivered by the driver determines the small signal gain achieved, which is the laser gain. However, the saturation gain of the gain medium is usually determined by the gain medium. It is a function of the materials chosen, but not necessarily a simple linear function, and ultimately, the laser Such a laser driver has two or more operating states. one for power transfer and the other for target scanning, setup, and and other functions of the system, such as information transmission. More importantly, the laser driver must be It is important to generate a stable radiation (regarding

[0047] To convert the light beam back into electricity to transmit useful power, a light-to-electrical converter is used. The power converter is generally a solar cell. As with lasers, Suitable solar cells tuned to the frequency of the beam being received are readily available off-the-shelf components. Since it is not commercially available as such, a custom cell is required. To be efficiently absorbed by the conductor, the band gap of the photovoltaic semiconductor must be as large as the The band gap must be slightly smaller than the band gap of the receiving medium. Otherwise, the conversion efficiency will be low. On the other hand, if too small a band gap is used, then The conductors on the solar cells also reduce the radiation of the beams that are used for high radiance. It needs to be matched to the radiance, requiring a thicker conductor.

[0048] The band gap of the laser gain medium should be in the range of 0.8-1.1 eV. The band gap of the solar cell to be used must be smaller than that, and single junction solar cells is typically 60-80% of the band gap energy divided by the electron charge Therefore, a single junction cell tuned to the laser frequency requires a very low voltage, typically It generates 0.3 to 0.8 V and has an output power of several watts, as required by practical systems. Assuming that they typically generate high currents, they will have serious losses (e.g. >5%) of the generated current. The semiconductor conductor must be thick enough to transmit light without interference. In general, the series resistance of a conductor is 1 ohm. It is necessary that the impedance is less than 0.1 ohms, and more preferably less than 0.1 ohms. Typically, this decreases with increasing temperature, so the heat generated is efficiently removed from the solar cell. It should be.

[0049] This combination of low voltage and high power provides the power you need to easily charge your portable devices. It is not possible to convert the required high voltages, typically 3.3V or 5V. In addition, some systems, such as communication systems, use voltages such as -48V, 12V or 3.8V. The system requires a stable voltage and the expected output voltage from the solar cell. A common method for increasing the voltage of a solar cell is to The method is to connect them in series, as described in, for example, U.S. Pat. No. 3,370,986. .F.Amsterdam et al., “Photovoltaic Series Array comprising P / N and N / P Cells” There is shown a general configuration for generating high voltages, in which almost identical amounts of It uses semiconductors and no additional components, so it is the solution of choice. do.

[0050] However, this is particularly true since lasers generally do not have uniformly shaped beams. The solution is to use a laser with a radiance of 8kW / m 2 / Used at high brightness up to steradian In addition, the beam shape is not suitable for systems such as those described in this application. The optical characteristics may change over time, and the pointing accuracy may be less than is optically desired. In these circumstances, it is important to design a compact and efficient system that uniformly illuminates all cells. is virtually impossible. If the solar cells connected in series are not uniformly illuminated, they In that case the voltage is actually boosted to the desired level, but the current is generated by the cell that produces the least current, which is usually the least illuminated cell. In this situation, the efficiency is very poor. Alternative methods for boosting pressure need to be improved.

[0051] One method to boost the voltage of a single cell is to charge a capacitor connected in parallel. This can be achieved by charging two resistors in series and then discharging them in series. gives good results, but as the current increases beyond a certain level, the switching frequency becomes the dominant factor and affects efficiency, and as the number of switching times increases, the efficiency Deteriorate.

[0052] If energy is converted to alternating current using a fast, low-resistance, switching mechanism, The AC current can be amplified using coupled inductance and then converted back to AC. The boosted AC voltage can be fed to a diode bridge and a capacitor or It can be converted to DC using an energy storage device such as a battery. The system is advantageous when the voltage needs to be boosted to more than 20 times the normal voltage. Another advantage of the system is that switching can be done from the transmitter using a laser. The advantage of this is that it reduces receiver cost and complexity because the voltage is 10 times lower. If pressure needs to be boosted by a factor or if volume limitations are critical for the application, Such a system is at a disadvantage.

[0053] Referring to FIG. 13A, an efficient and simple method for voltage conversion is shown. In the configuration of FIG. To boost the voltage of the solar cell, a single inductor is used as a low-resistance switching mechanism. In FIG. 13A, the rectangular shape on the left is the sun. is the battery, and the switch S is a MOSFET, JFET, BJT, IGBT or pHEMT The inductance L is connected to the output of the solar cell, and the capacitor -C acts as an energy storage device.

[0054] In the following description, we will assume that the resistance is zero to simplify the use of the components. Considering losses complicates the calculations and is explained in a later section of this disclosure. The switching mechanism is inductively coupled between the two main operating phases: charging and discharging. During the charging phase, the inductor is turned on by closing switch S. During this phase, the inductor is transformed by the solar cell. The inductor energy is charged by the energy that is transferred to it. ΔE L_CH =Vpv×I L ×T CH where Vpv is the output voltage of the solar cell, I L is the average inductor current, T CHは This is the time for the charging phase.

[0055] During the discharge phase, the inductor is connected between the solar cell and the load by opening switch S. During this phase, the energy delivered from the inductor to the output energy storage device The energy is provided by the reduction of inductor energy. ΔE C =V O ×I L ×T DIS , where V O is the voltage of the energy storage device, which is typically very close to the desired output voltage of the device. and therefore may approach the output voltage of the system. I L is the average inductor current, T DIS is the time of the discharge phase.

[0056] The energy transferred from the solar cell to the inductor during that phase is given by . ΔE L_DIS =Vpv×I L ×T DIS . The change in inductor energy during that period is the difference between the input energy and the output energy. do. ΔE L_DIS =Vpv×I L ×T DIS -V O ×I L ×T DIS .

[0057] In steady state operation, the energy in the inductor at the end of the cycle is regenerated at the beginning of the cycle. Return to the same value ΔE L_CH = -ΔE L_DIS , This is the value after the assignment. V O = Vpv × (1 + T CH / T DIS ). Therefore, the energy storage device voltage is the same as the solar cell voltage during the charging and discharging phases. It is determined by the ratio between

[0058] However, in this system, parasitic and other characteristics of the components affect conversion performance and efficiency. The selection and use of proper components is essential for efficient system operation. Care must be taken when using these factors.

[0059] Inductor 1. The inductance of an inductor is determined by the rate of change of the inductor current relative to the applied voltage. It is defined as dI / dt=V / L, where dI / dt is the rate of change of current and , V is the voltage applied across the inductor and L is the inductance. In this system, V is determined by the gain medium of the transmitter. The selection results in a change in the photon energy, which in turn changes the photovoltaic band gap. This results in a change in the photovoltaic voltage. Or the switching frequency must be selected. The switching speed depends on the inductor current. to respond to changes in input power from the transmitter via an opto-electrical power converter. must be fast enough to withstand high power dissipation, input voltage ripple and output voltage ripple. The inductor must be slow enough to avoid high value current ripple that can cause inductor pull-up. The optimum value of the converter produces a ripple current that is between 20% and 40% of the maximum expected input current. However, the system may be operational between 10% and 60%. Analysis shows that to achieve this desired value of inductor L, measured in henries, In order to achieve this, the limit must be within the following equation:

number

[0060] To successfully integrate Inductor with a mobile client, the mobile client must An inductor with limits appropriate for the current required for portable charging and suitable for portable applications. Since the actuators are typically much smaller than this value, the inductance is typically less than 10mH. Also, the inductance must be smaller than 10 nH. The actuators are subject to high switching frequencies that severely limit the availability of other components in the system, such as switches. The switching losses caused by this high frequency are transmitted by the solar cell. is greater than the amount of power that can be achieved. 2. The series resistance of the inductor, R parasitic can minimize the transmission power loss. Generally, it should be as small as possible to reduce efficiency by less than 10%. The series resistance of an inductor, measured in ohms, is given by the following formula: Must be full

number

[0061] Switching Mechanism 1. A switching mechanism is usually two or more devices. The first device, the main The first switch conducts current and sets the inductor in the charging phase. The second device It can be a diode (as shown in FIG. 13A) or a switch, the function of which is to discharge the During the phase, the inductor is connected to a load or output to an energy storage device. ,The inductor is removed from the load during the charging phase. 2. The switching mechanism uses low switch noise to minimize switching losses. A high capacitance is required. P SW2 =0.5×Csw×V O 2 ×f. To extract more than 50% of the laser power, the switch node capacitance should be It must be less than the following:

number

number

[0062] Energy Storage Devices 1. The energy storage device can be a capacitor or a battery or both. do. 2. During the charging phase when the inductor is disconnected from the output, the energy storage device is required to maintain the output voltage. The capacitance of the storage device is The selection is based on frequency, laser power and desired output ripple voltage. C OUT >P LASER_DRIVER / (f × V O ×ΔV O ) Here, ΔV O is the desired output ripple voltage. 3. During temporary interruptions in the optical path, the energy storage device can provide power to the load. To provide uninterrupted power, the energy storage device must be in a minimum operating state. Output power (P OUT_MIN ) with interruption time interval (T INT ) multiplied by At the very least, we must conserve energy. E OUT_MIN ≧P OUT_MIN ×T INT . When a capacitor is used as an energy storage device, the capacitance is formula C OUT ≧2×E OUT / V OUT 2 It needs to be greater than. Uninterrupted operation with a minimum operating output power exceeding 10 mW and an interruption time interval exceeding 100 ms. To achieve this, the stored energy must exceed 1mJ and the capacitance must be 80 μF (V OUT = 5V).

[0063] In some cases, the capacitor acts as an energy storage device for the client application. In that case, the client application may act as any secondary Energy storage devices (conventionally used in mobile devices) The energy of the systems described herein may be designed not to use a The energy storage device provides the client device with the necessary power until the next charging event. In this case, it is necessary to store enough energy to Additionally, supercapacitors with capacitances of 10F or more may be used. In some cases, the power requirements of the client device are low, or the If the vehicle has a separate energy storage device, such as a battery, that is If the device does not need to operate without power, the controller used The densities are generally well above 1 F. Rechargeable batteries are used as energy storage devices. If a battery is used, it is similar to the capacitor logic described above, but is used only as a means to regulate voltage and not to the client device during a charging event. If not used as a means to maintain the power supply, the battery energy The capacity is advantageously 10 times that of the energy delivered during 100 cycles of the switch. 0 times (typically less than 0.1Wh), this level is based on the battery production budget. On the other hand, the battery is not charged during the charging event. If the device is also used to power a client device, the The energy required for an Android device is generally 0.1Wh or more for a mobile phone. The capacity must be large enough to store at least 10 ... There are also volume restrictions depending on the product in which the battery is intended to be used. If the battery of a product having a volume V is installed outside the device, Generally, it is limited to a few times the device voltage, i.e., 3V. According to this rule of thumb, The volume of the battery used to power a 100cc mobile phone is generally 3 Generally, the capacity of the battery is limited to less than 1000cc due to the above restrictions. Therefore, it is less than 300Wh.

[0064] The circuit of Figure 13A is not the only possible technique. Figure 13B shows a different technique that can achieve similar performance characteristics. The components roles, constraints and expected values ​​of Figure 13B are shown in Figure 13A. The main difference is that the positive and negative terminals of the output voltage are inverted. And so.

[0065] In some applications, the energy storage device is used to power the device that is going to use the received power. In other applications, particularly those where short periods of operation are anticipated, In applications where regulated voltage is not required, the energy storage device is omitted. This is also fine.

[0066] Regulation Points The power output of a solar cell depends on the optical power input and the load applied to it. Therefore, the voltage converter produces the maximum output power of the solar cell at the optimal load condition. The control mechanism must regulate the load point. The operation of maintaining a constant voltage across the cell terminals, often known as the maximum power operating point. Or measure the cell output power and search for the optimum cell voltage under all operating conditions. The first approach is to design the system so that it can track the maximum power operating point by The switch is simpler and the second approach is more power efficient.

[0067] The generated laser beam must be directed towards a receiver. A beam steering device is used to direct the beam toward the target. The beam steering subsystem includes a moving mirror, a moving lens, an electro-optic modulator, and an electromagnetic A set of motors that move the light modulator and all transmitter systems in one or more directions , or any other suitable beam deflection device. The beam steering devices are controlled by a controller and, in the most convenient case, are the same. The controller is used to control the laser driver. The beam steering device is 8kW / m 2 / Multiple beams in multiple directions It is configured so that it can be directed in any direction. The damage threshold of the beam steering device needs to be able to withstand the radiance of the beam. For example, a focusing mechanism with a numerical aperture of 0.5 is used to focus the beam onto a mirror. When focused, 8kW / m 2 For a beam of / steradian, the mirror is at least 6.7kW / m 2 must withstand power densities of up to 1000 times higher. Higher radiance beams are used. In this case, the mirror must be selected to have a correspondingly higher damage threshold. do.

[0068] Figure 14 shows the 2 / Aperture when a steradian beam is focused on a mirror It shows the power reflected per square meter of the mirror as a function of the number. When a high radiance beam is used, the power reflected by the mirror is correspondingly linear. gradually increases. The beam may not be uniform at all, so there may be a 10 times larger radiation loss compared to the beam average. "Hot spots" that may have illuminance may be created. Therefore, the actual beam irradiance and the aperture of the focusing mechanism on the mirror In accordance with the numbers, the mirrors should preferably have a damage threshold at least 10 times higher than that shown in FIG. It should have a value.

[0069] Generally, the receiver has an optical front that is close to the solar cell and is connected to the solar cell. The beam passes through the receiver and is reflected by the solar cell. These are necessary to protect potentially fragile structures and often incorporate power receivers. The front is made of Corning Gori To protect against scratches caused by materials such as Ila Glass® or similar It may have a coating to improve its scratch resistance or be treated to improve scratch resistance. To reduce the level of contaminants such as fingerprints and dust that may accumulate on it. or to reduce the effect of light reflected from it. The front surface of the solar cell may also be coated with an anti-reflective coating to reduce reflections. In some cases, the front surface may be part of the structure of the solar cell itself or may be coated with a It can be coated onto a solar cell.

[0070] In some situations, anti-reflective coatings are chosen that have very low reflectance. This may reduce the amount of reflection from the surface below a safe threshold, but the coating If the reflector becomes contaminated with foreign matter or is covered with spilled fluid or fingerprints, the reflector may not function properly. Antireflection coatings are less effective at reducing reflection, typically at 3-4% of the incident light. is reflected in uncontrollable directions. If the reflection is divergent, the power density The radiation quickly drops to a safe level. However, when it is reflected into a focus, the power density The degree of curvature may increase to unsafe levels. For this reason, the ROC (radius of curvature) of the surface is It is important that no point above that is less than a predefined value. Generally, if it is intended that only a small fraction of the light incident on the surface is reflected, , any significant beam, whatever the surface curvature, whatever the shape or characteristics. The risk of reflections is also reduced. Even with an increase in reflection of about 4% from the untreated glass surface, However, if a layer of extraneous contaminant material on the surface increases the reflectivity, the reflected light The level may be variable; however, such reflections are not expected to exceed 20%. Generally, the reflectance is practically 0.1% or less. In the case of coated glass, the reflection ratio is less than 4% of that of untreated glass. The surface is described and claimed in this disclosure and has the reflective properties. represents less than 20% of the incident light, and generally less than 4% of untreated glass. Used for.

[0071] 15A to 15C, they show that a portion of the incident light is reflected from the surface. FIG. 15A shows a schematic diagram of a method for avoiding the above-mentioned unsafe reflections even when the FIG. 15B shows the situation where the surface is convex, and FIG. 15C shows the situation where the surface is concave. In Figure 15A, the surface is diffusive, and the surface is at least 8 kW / m 2 / steradian An incident beam 110 having radiance passes through a front surface 111, which may be the front surface of a solar cell. Thus, the front surface 111 is directed toward the solar cell 112. Reflecting some of the beam 110 to produce a focused beam 113 that reaches a focal point 114 at a distance. The focal point 114 does not present any danger to the eyes or skin, or to other objects. To ensure that the surface 111 is oriented in a circular arc, the radius of curvature (ROC) of the surface 111 is set to 100 mm, as shown in FIG. 15A. The beam can be focused with a low numerical aperture as shown in Figure 15B, or defocused as shown in Figure 15B. or as shown in Figure 15C. In order to achieve this, the surface is concave in the direction from the transmitter to the solar cell as shown in FIG. If so, the ROC must be greater than 1 cm, typically 0.5 W. If a high power system with more than 5000 ohms is used, the distance must be greater than 5 cm. Alternatively, the surface ROC is negative and the ROC is between 0 and 1 cm, as shown in FIG. According to these limitations, the focus of the reflected beam of light is a virtual focus, i.e. by a diverging reflected beam or by a visible light beam at a distance of at least 1 cm in front of said surface. This ensures that the surface is free from any defects and the risk of focal spots is significantly reduced. There are also many regions with small curvatures to form a diffusive surface, as shown in Fig. 15C. This can significantly reduce the risk of forming a dangerous focus. The radius of curvature of each subsection of the surface may be less than 1 cm so as not to form a focus. Furthermore, if the surface is divided into multiple regions, each region has a smaller curvature. do.

[0072] For safe operation, the solar panel must be blocked and directed into unsafe areas. The system also needs to be able to direct a beam of power onto the solar cells to prevent this. To achieve this, detectors are positioned to indicate the impingement of the beam on the receiver. The detector is generally located in the receiver, but it is also possible for the detector to be located in the transmitter. A configuration in which the detector is located inside the receiver is also possible, in which case the detector detects the impact of the beam on the receiver. It is necessary to respond to phenomena caused by collisions. The system requires that the receiver be equipped with a transmitter that can detect the illumination pattern of the bar code. An image of optical information received from a receiver, such as a beam reflection from a printed bar code Collection and processing may be required. A retroreflector or multiple retroreflectors or an array or The reflected light from these patterns can be placed on a receiver, and the reflected light can be can be detected by the emitter, which can be image processed and used to measure the back reflection. or by measuring reflected coherence effects. current or voltage sensor located in the receiver or transmitter, Imaging devices that may be in the transmitter or receiver. A retro-reflector adjacent to the solar cell may be used, and the In combination with an additional detector, the light reflected from the retroreflector is detected.

[0073] The detector detects the light beam hitting the solar cell and sends a signal to the system controller accordingly. If a detector is present in the receiver, it transmits RF, IR, visible, UV The transmission is carried out using a communication channel, which may be modulation of the beam, TCP / IP, or sound. The communication can be performed wirelessly. The system controller is usually located in the transmitter, but The control unit may be located in the main control unit or may be connected to a computer network from the transmitter. Upon receiving the signal, the controller performs at least one of the following: Respond by running (a) Changing the state of the laser driver. (b) Beam steering, such as the direction in which the beam is pointed or the speed at which the direction is changed. Altering the operating characteristics of a device.

[0074] Referring to FIG. 16, a schematic diagram shows a detailed description of the complete system. The transmitter 21 and the receiver 22 are generally Although they are spaced apart, they are not shown in FIG. 16 and are shown to be close to each other for convenience. System 15 transmits power from transmitter 21 to receiver 22 .

[0075] At the receiver 22, the front surface 7 reflects a portion of the incident beam 15 as a reflected beam 16, It can be diffused to form a virtual focus behind the front surface 7, or it can be realized at a distance of at least 1 cm in front of the surface 7. After at least a portion of the beam 15 has been transmitted through the transparent surface 7, it is focused into a photoelectric Collision with power converter 1.

[0076] The photoelectric power converter 1 is fitted with a front window, which can be a surface 7 or a separate window. It may be surrounded by a package that may have a coating, air surrounding it, or an adhesive. or have an external surface applied to act as an interface with the glass. In a typical configuration, the photoelectric power converter 1 is made of a semiconductor layer In many embodiments, surface 7 is a conductor that is typically deposited on the surface. It may be coated or be the outer surface of one of these semiconductor layers.

[0077] The signaling detector 8 controls the information while the beam 15 strikes the solar cell 1. In this example system, the signal is transmitted to the camera 13 located in the transmitter 21. The control signal is transmitted by link 23 to a detector 24 in the transmitter.

[0078] The electrical power converter 1 has a bandgap E8 and typically operates between 0.35 and 1.1 V. The power can be generated from the sun, and higher voltages can be generated using multi-junction solar cells. A part of the energy passing through the conductors 2a and 2b, which have low resistance, from the battery 1. The magnetic field flows through an inductor 3 which stores the magnetic field.

[0079] The automatic switch 4 is typically a MOS FE connected to a control circuit (not shown in FIG. 16). T transistor, which switches between alternating states and during the first time A current is passed from inductor 3 to ground, and during the second time portion, the inductor The magnetic energy stored in this is converted into a current at a higher voltage than the solar cell, and the diode 5 is The current flows to the load 6 via the power supply 10 so that it can be used as power.

[0080] Auto Switch 4 can be used with fixed or variable frequency and / or duty cycle and / or waveform shapes that can be controlled by the transmitter; and can be controlled by the client load and based on the current, voltage, or temperature at the load. , or automatically switches 4 based on current, voltage or temperature to photoelectric power converter 1 based on the current, voltage or temperature generated by the The display information can be used for control.

[0081] The receiver may be directly connected to the load 6 as shown in FIG. 16, or the load 6 may be connected to the receiver. The load may be external to the receiver, or may be a mobile phone or other power consuming device. It can be another device, USB / Micro USB / Lightning / USB It may be possible to connect using a socket such as Type C.

[0082] In most cases, the load 6 is connected in parallel with an energy source such as a capacitor or battery. The load 6 has an energy storage device, such as a capacitor or battery. The device may include a ghee storage device.

[0083] The transmitter 21 generates a beam 15 and directs it to the receiver 22. In this mode, the transmitter 21 uses a scanning beam, i.e., to detect the receiver. The receivers 22 detect the presence of a signal by detecting RF, light, IR light, UV light, or A retro-reflector, or a retro-reflective structure, a barcode, or other communication means is used to transmit the signal. A visual identifier on the receiver, such as a card, high contrast pattern, or other visual identifier. This is done using a camera that detects the location of the target. Once the approximate location is known, the beam 15 is aligned Typically at low power, the general area around the receiver 22 is scanned. The beam 15 strikes the solar cell 1. When the beam 15 strikes the solar cell 1, the detector 8 detects it. The sensor 12 detects this and sends a signal to the controller 13 accordingly. In response to the signal, the controller 13 controls the laser driver 12 to perform one or both of the following: By varying the power P input to the gain medium 11 and the mirror 14, Varying the scanning speed or velocity at which the beam is directed or maintaining its position; The gain medium 11 receives different powers P from the laser power supply 12. When a photon is received, its small signal gain - the gain obtained when one photon traverses the gain medium - is calculated. The gain is changed so that no other photons cross the gain medium at the same time. When a photon directed in the direction between the power coupler 9 passes through the gain medium 11, a number of photons are generated. are emitted in the same direction, and the beam 15 is between the rearview mirror 10 and the output coupler 9. Generate optical resonance at

[0084] The output coupler 9 is a semitransparent mirror with reflectivity R and a wavelength of 6940 cm -1 In C- The first overtone of H absorption and 8130cm -1 Spectrum between the second overtone of CH absorption at They operate at least in part on the In this case, alternating layers of materials with different refractive indexes are deposited on a substrate, which is typically a glass substrate. The surface of the gain medium 11 may be glass, plastic, or the like. Alternatively, the gain medium may be sufficiently small. Fresnel reflection may be used if it provides signal gain or has a high enough refractive index. Or, a common metal mirror can be used. If the gain medium is a semiconductor or fiber In the case of a 1-phase amplifier, a Bragg reflector may be used. It may consist of a highly reflective mirror combined with an extractor, The tractor is a component, such as a translucent optical component, that transmits a portion of the light from the forward wave in the resonator. Another part of the light is extracted by mixing it with the ion beam, but typically a third part is extracted from the backward propagating wave in the resonator. It is also a minute.

[0085] The back reflector 10 is a highly reflective mirror, but some of the light may leak backwards and become a target. It can be used for filtration or other purposes, and can be used for up to 6940cm -1 The first CH absorption 1 overtone and 8130 cm -1 At least the spectrum between the second overtone of CH absorption at Generally it works by interfacing with a surface, which is usually glass, metal or plastic. It may be constructed of alternating layers of different refractive index materials deposited on top of one another. Alternatively, if the gain medium is sufficiently Fresnel reflection can be used if it can provide small signal gain to the If the gain medium is a semiconductor or fiber amplifier, a blanking A light reflector may also be used.

[0086] The gain medium 11 has a wavelength of 6940 cm -1 The first overtone of CH absorption at 8130cm -1 in amplifying the radiation between the second overtone of the CH absorption and not necessarily the entirety of this spectral range. No amplification is required. This is because when pumped with the power P of the laser driver 12, the output coupler This provides a small signal gain that is greater than the loss due to the 9. Damage threshold is at least 8kW / m 2 / steradian / (1-R) ​​beam can be maintained where R is the reflectivity of the output coupler 9. A semiconductor material having a band gap of 0.8 to 1.1 eV or a transparent host material or another structure capable of stimulated emission in that spectral range. is located on the optical axis between the back reflector 10 and the output coupler 9, 0 is coupled to the gain medium 11 via the back reflector 10 and the output coupler 9 It resonates between.

[0087] In an exemplary embodiment, the gain medium 11 is a semiconductor having a band gap between 0.8 and 1.1 eV. In the installed form, it is preferably attached to a heat removal device and is powered by a laser driver 12. The laser may be electrically or optically excited.

[0088] The gain medium 11 is YAG or YVO4 doped with Nd ions. 4 , GGG, or Gala In an exemplary implementation, the gain medium 11 is a transparent host, such as glass or ceramic. The 9400 cm resonance between the output coupler 10 and the output coupler 9 -1 Extracting ambient radiation It is preferable that the optical connection with the filter is made optically.

[0089] A beam steering device 14 is shown and is controlled by a controller 13. The beam 15 can be deflected in multiple directions. The area is tilted to the maximum operating tilt angle. Basically, the radiated beam must be large enough to contain most of the beam 15. To illustrate the two-dimensional case, let’s assume that beam 15 is 5 mm in diameter (1 / e 2 diameter) of Gauss bee The beam is collimated into a single round gyroscope with the optical axis at the center of the beam. The mirror is a ball-type mirror, and the maximum required tilt angle is 30 degrees. If there are no other apertures in the guiding device 14, the mirror should have a diameter of 5 mm, the same as the diameter of the beam. , the loss is about 13% for a normal incidence beam, but about 60% at a 60 degree tilt angle. This will seriously damage the system performance. This power loss is shown in the graph in Figure 17. As shown in the figure.

[0090] At the beginning of the operation, the controller 13 causes the laser driver 12 and the mirror 14 to perform a seek operation. This causes the laser driver 12 operating in a first state to This can be done by pointing the receiver 22 in the general direction in which it is likely to be found. For example, If the transmitter is mounted in a corner between the ceiling and the room, scanning will The beam 15 is a light-to-electrical power converter. When the light strikes the receiver 22 containing the data 1, the detector 8 sends a signal to the controller 13, etc. If no such signal is received, the controller 13 will notify the beam steering 14. The signal is then sent to detector 8. When a signal is received from the controller 13, the controller 13 controls the beam steering to lock onto the receiver. 14 to stop or slow down its scanning, and Alternatively, the controller 13 may command the receiver 22 to increase its power emission. The location can be stored and returned to at a later stage.

[0091] When 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 transfer begins. The detector 8 detects the power loss. When it is detected that the loss exceeds a threshold, the threshold may be predetermined or dynamically set. This level generally represents a significant portion of the maximum permissible exposure level and is generally These conditions are met to transmit the beam 15 to the photoelectric power converter 1 in a manner that is greater than the noise figure of the optical fiber. not properly pointed or any object is in the path of the beam or malfunctions This indicates that a fault has occurred and typically causes the controller 13 to reduce power and reach the required safety level. This command instructs the laser driver 12 to change state to maintain the laser pulse width. If there is another indicator that something is wrong, e.g. in the user interface or API, A user instruction regarding a safety transmission that may be instructed by the second safety system or When a safe operation is indicated, the controller will increase power to the laser to compensate for the power loss. The controller 13 can command the beam steering assembly 14 to reseat the beam. It may also command the execution of a king operation.

[0092] There are two different states that a seek operation can have. The first operation is to use the camera for coarse seek. A visual pattern search can be implemented using retroreflectors, High contrast image, search for a response signal from a receiver or another indicator, i.e. By using the scanning characteristics of the beam steering 14, the receiver can be found. A list of positions with a certain number of positions can be generated in this way. The second stage is the fine seek. until the detector 8 signals that the beam 15 has impinged on the photoelectric power converter 1. A beam steering mirror 14 directs the beam 15 onto a small area.

[0093] Referring now to FIG. 18, an exemplary cooling system for the system gain medium 11 of FIG. The reflectors 9, 10 are shown as separate optical components, but are not shown to simplify the system. It will be appreciated that one or both of these may be coated directly onto the end surfaces of the gain medium. The gain medium 11 converts the power received from the laser driver 12 into both heat and photons for use. Heating the medium above a certain temperature generally degrades system performance. For this purpose, the gain medium 11 is preferably provided with a bonding material, such as a solder, which is thermally conductive and has a low thermal resistance. 33 is used to attach the heat sink 34. The bonding agent 33 may be a conductive adhesive. The thermal expansion coefficient of the binder 33 may be between that of the gain medium 11 and the heat sink 34. The heat sink 34 may be a low thermal resistance heat sink typically made of metal, the surface of which may be Fins to increase area or an external fluid pump such as a fan or fluid pump 35 A processing system may be provided.

[0094] It will be apparent to those skilled in the art that the present invention is not limited to the specific forms illustrated above. Rather, it is not intended that the scope of the present invention encompass any combination, subcombination or modification of the various features described above. Not only does it include both the above-mentioned combinations, but also the above-mentioned specification, the above-mentioned specification, the above-mentioned combinations ... This also includes variations and modifications that are not in the prior art.

Claims

1. A system for transmitting wireless power by light to a power receiving device, comprising: an optical resonator having a terminal reflector and used to emit a light beam; a gain medium disposed within the optical cavity and having a first band gap energy; and a cooling system configured to amplify light passing through the gain medium. said gain medium; a driver for providing power to the gain medium and controlling the small signal gain of the gain medium; A beam steerer configured to direct the light beam in at least one of a plurality of directions. A scanning device, an optical-to-electrical power converter configured to convert the light beam into electrical power having a voltage; the photoelectric power converter having a second bandgap energy; Converting the voltage of the electrical power generated by the photoelectric power converter to a different voltage.

1. An electrical voltage converter configured to: the electrical voltage converter having a device and a switch; At least one surface of the photoelectric power converter is provided with a surface that is in contact with the gain medium and the photoelectric the surface being optically exposed between the electrochemical power converters; providing a signal indicative of said light beam impinging on said photoelectric power converter; A detector comprising: to control at least one of the beam steering device and the driver state. a controller configured to at least, prior to receiving a control input signal from the detector, The controller includes: The at least one surface is configured to: (i) Diffusely, or (ii) a virtual focus at which the reflected light is directed away from the optical cavity relative to the surface; or (iii) the reflected light is located at least 1 cm from the surface toward the optical cavity; and the light has a reflecting property so as to have a real focal point located at the position of the light source. The controller is responsive to the control input signal received from the detector to perform the following steps: and configured to perform at least one of causing the driver to vary the small signal gain of the gain medium; Varying the radiance of the light beam; Varying the power supplied by the driver; Varying the scanning speed of the beam steering device; Varying the scanning position of the beam steering device; recording a scan position defining a position of the opto-electrical power converter; The gain medium is a semiconductor device or a solid-state host doped with Nd ions, The number is 8, 300 cm －１ From 12,500 cm －１ At least one frequency in the range a filter for attenuating radiation of The second band gap energy is smaller than the first band gap energy. fence, the first band gap energy is between 0.8 eV and 1.1 eV; The closed series resistance of the switch is less than R, given by: [0010] where R is measured in ohms, E 利得 is the first band gap energy, measured in joules; the law of nature, P レーザドライバ is the power supplied from a laser driver to the gain medium, The unit used is watts, The radiance of the light beam is at least 8 kW / m ２ / steradian, and the frequency is about 6940cm －１ A system between the first and second overtones of C-H absorption located at 。

2. 2. The system of claim 1, wherein the different voltages are generated by the photoelectric power converter. The system is a voltage higher than the voltage generated by the

3. 3. A system according to claim 1 or 2, wherein the state of the beam steering device is at least one of the aiming direction or the scanning speed of the beam steering device. Hmm.

4. In a system according to any one of claims 1 to 3, the radiance of the light beam is low. At least 800kW / m ２ / A system that is a steradian.

5. 5. The system according to claim 1, wherein the end reflection of the optical resonator is Each of the bodies is (i) a dielectric mirror, (ii) a Bragg mirror, and (iii) a Fresnel reflector. or (iv) alternating layers of dielectric or semiconducting materials having different refractive indices. A system that is either a mirror consisting of layers.

6. 6. The system according to claim 1, wherein the gain medium is a Nd ion A system that is a doped transparent solid host material or semiconductor.

7. 7. The system of claim 6, wherein the wave number is 8300 cm －１ Extract radiation greater than The system further includes a filter for filtering the filtered signal.

8. 7. The system of claim 6, wherein the gain medium, when a semiconductor, is a quantum dot. A system in which the gain medium is a saturation gain medium.

9. In the system according to any one of claims 1 to 8, the cooling system comprises a heat sink. the system being at least one of a heat sink, a Peltier diode, and a fluid cooling plate.

10. 10. The system according to claim 1, wherein the cooling system also includes a fan. A system that provides.

11. 10. The system of claim 9, wherein said gain medium has a thermal resistance of 200° Kelvin / Watt. The system is attached to the cooling system using a solder layer smaller than 100 mm.

12. 10. The system of claim 9, wherein the cooling system is a cooling system for cooling the gain medium and the ambient air. A system having a thermal resistance between less than 200° Kelvin / Watt.

13. A system according to any one of claims 1 to 12, wherein the photoelectric power converter is a solar cell system.

14. A system according to any one of claims 1 to 13, wherein the photoelectric power converter The series resistance of the system is less than 1 ohm.

15. 14. The system of claim 13, wherein the solar cell is a III-V device. Stem.

16. 16. The system according to claim 1, wherein the inductor has an ohmic The series resistance measured in units of joules is the first band The square of the gap energy is 2×10 －４０ The dryer is measured in watts. system is less than the power of the power supply divided by the power of the power supply multiplied by the power of the power supply.

17. 17. The system according to claim 1, wherein the energy storage device The power source is either a capacitor or a rechargeable battery.

18. A system according to any one of claims 1 to 17, further comprising a retroreflector. system.

19. 19. The system according to claim 1, wherein the gain medium is A system that is electrically or optically excited by a power source.

20. 20. The system according to claim 1, wherein the second band gap The energy of the system is greater than 50% of the first band gap energy.

21. 1. A method for transferring power from a transmitter to a receiver, comprising: The first power is about 6940 cm －１ The first and second overtones of C-H absorption located at and converting the electromagnetic wave into an electromagnetic wave having a frequency between 1000 and 10000 Hz, the radiance of the electromagnetic wave being at least 8kW / m ２ / steradian, and the converting step includes using an optical resonator having a terminal reflector. a gain medium coupled to a laser driver receiving the first power; the gain medium has a first band gap energy between 0.8 eV and 1.1 eV; A cooling system is disposed within the optical cavity and thermally bonded to the cooling system, amplifying the electromagnetic waves passing therethrough. and A beam steering device controlled by a control unit is used to steer the electromagnetic waves. orienting the light beam in at least one of a number of directions; Detecting the impact of the beam on a target having a partially transparent surface, The control unit is caused to perform at least one of the following steps in response to the instruction corresponding to the collision: The process includes the steps of: varying the small signal gain of the gain medium; causing a change in the radiance of an electromagnetic beam; causing a change in the first power; causing a change in the scanning speed of the beam steering device; causing a change in a scan position of the beam steering device; recording scan positions defining the location of the target; A second band gap energy smaller than the first band gap energy. and converting the electromagnetic wave into a second electrical power having a voltage using a photoelectric power converter having a And a process of Converting the voltage to a different voltage using an electrical voltage converter. An electrical voltage converter consists of an inductor, an energy storage device, and a resistor R given by a switch having a closed series resistance smaller than [0025] where R is measured in ohms, E 利得 is the first band gap energy, measured in joules; the law of nature, P レーザ＿ドライバ is the first power measured in watts, The surface may divide a portion of the electromagnetic wave incident on the surface by: (i) Diffusely, or (ii) a virtual focus of the reflected light is located away from the optical cavity with respect to the surface; or (iii) the reflected light is at least 1 mm in the direction of the optical cavity relative to the surface; a reflector designed to have a real focal point located at cm; The gain medium can be either a semiconductor device doped with Nd ions, or a solid-state host. The wave number is 8,300 cm －１ From 12,500 cm －１ At least in the range of Also, the method includes a filter that attenuates radiation for one frequency.

22. 22. The method of claim 21, wherein the switch is switched at a frequency determined by the formula: It is queried, [0030] where f is the switching frequency measured in Hz, E 利得 is the bandgap of the gain medium, measured in Joules; V 出力 is the output voltage of the voltage converter, measured in volts, P レーザ＿ドライバ is the power pumped into the gain medium by the laser driver. A method of measurement in units of bits.

23. 23. The method of claim 21 or 22, further comprising detecting the impact of the beam on the target. The start is, By detecting the retroreflected irradiance at the target with the transmitter, Or The method is carried out by detecting the illumination of the target using a receiver sensor. Law.

24. The method according to any one of claims 21 to 23, wherein the second band gap energy The band gap energy is greater than 50% of the first band gap energy.

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