Light source device and relay device

Abstract

To provide an optical power feeding system over a water surface for improving power feeding efficiency.SOLUTION: In an optical power feeding system 100A, a light source device 200A is used for optical power supply over a water surface 102. A sensor 220 measures a state of the water surface 102. A controller 230 controls a state of a beam BM directed to a light receiving device 300 or a relay device located on an opposite side of the water surface 102 based on a state of the water surface 102 indicated by output of the sensor 220.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to an optical power supply system. [Background technology]

[0002] Wireless power supply has been put into practical use for electronic devices such as smartphones and tablet devices. Currently, practical wireless power supply uses electromagnetic waves in the frequency band of several hundred kHz, and known methods include electromagnetic induction and magnetic resonance. Although light is essentially a type of electromagnetic wave, in this specification, the term "electromagnetic wave" refers to electromagnetic waves with wavelengths longer than that of light.

[0003] Optical wireless power transfer, which uses light instead of electromagnetic waves, has been proposed. Light has the property of being more directional than electromagnetic waves, so by using a beam with a small divergence angle, it has the advantage of being able to transmit energy highly efficiently over long distances with little attenuation. Water has low transmittance for electromagnetic waves, but high transmittance for blue to green light, making optical power transfer a promising candidate for underwater wireless power transfer. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] Japanese Patent Application Publication No. 2020-036480 Summary of the Invention [Problem to be solved by the invention]

[0005] The present disclosure has been made in this situation, and one exemplary purpose of an embodiment thereof is to improve the efficiency of an optical power supply system that operates over water. [Means for solving the problem]

[0006] One aspect of the present disclosure relates to a light source device used for optical power supply over water, which includes a sensor for measuring the state of the water surface, and a controller for controlling the state of a beam directed to a light receiving device or a relay device located on the opposite side of the water surface based on the state of the water surface indicated by the output of the sensor.

[0007] Another aspect of the present disclosure relates to a repeater used for optical power transmission over water, the repeater including a sensor for measuring the state of the water surface, an optical system for receiving a beam from a light source device or another repeater and directing it to a light receiving device or further repeater, and a controller for controlling the state of the beam from the optical system directed to the light receiving device or further repeater based on the state of the water surface indicated by the output of the sensor.

[0008] Any combination of the above components or conversion of the expressions of the present disclosure between methods, devices, etc. are also valid aspects of the present invention. Furthermore, the description in this section (Means for Solving the Problems) does not explain all essential features of the present invention, and therefore, subcombinations of the described features may also constitute the present invention. [Effects of the Invention]

[0009] According to an aspect of the present disclosure, power supply efficiency can be improved. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is a diagram illustrating an optical power supply system according to a first embodiment. [Figure 2] FIG. 1 is a diagram illustrating the refraction of light on the surface of water. [Figure 3] 1A and 1B are diagrams illustrating the influence of a wavefront on a light beam. [Figure 4] 10A and 10B are diagrams illustrating beam state control according to a first control example. [Figure 5] 10A and 10B are diagrams illustrating a modified example of beam state control according to Control Example 1. FIG. [Figure 6] 10A and 10B are diagrams illustrating beam state control according to a second control example. [Figure 7] 10A and 10B are diagrams illustrating beam state control according to a third control example. [Figure 8] FIG. 10 is a diagram illustrating an optical power supply system according to a second embodiment. [Figure 9] 10A and 10B are diagrams illustrating beam state control according to a fourth control example. [Figure 10] FIG. 10 is a diagram showing an optical power supply system according to a modified example of the second embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0011] (Outline of the embodiment) A summary of some exemplary embodiments of the present disclosure is provided. This summary is intended to provide a simplified overview of some concepts of one or more embodiments in order to provide a basic understanding of the embodiments as a prelude to the more detailed description that follows. It is not intended to limit the scope of the invention or disclosure. This summary is not an exhaustive overview of all possible embodiments, and is not intended to identify key elements of all embodiments or to delineate the scope of some or all aspects. For convenience, the term "one embodiment" may refer to one embodiment (example or variant) or multiple embodiments (examples or variants) disclosed herein.

[0012] A light source device according to one embodiment is used for optical power transmission over the water surface. The light source device includes a sensor for measuring the state of the water surface, and a controller for controlling the state of a beam directed to a light receiving device or a relay device based on the state of the water surface indicated by the output of the sensor.

[0013] When the water surface is choppy, the incident angle of the beam to the water surface changes from moment to moment, and the optical energy reaching the light receiving device or repeater is greatly affected by the state of the water surface. Therefore, by monitoring the state of the water surface and controlling the beam spatially and / or temporally, it is possible to reduce losses and improve power supply efficiency.

[0014] In one embodiment, the period of the unevenness on the water surface may be greater than the diameter of the beam. The controller may control the on / off of the beam.

[0015] In one embodiment, the period of the unevenness on the water surface may be smaller than the diameter of the beam. The controller may control the intensity distribution of the beam. The light source device may include a plurality of light-emitting elements that can be individually controlled to be turned on and off, and the controller may control the on and off of each of the plurality of light-emitting elements.

[0016] In one embodiment, the period of the unevenness on the water surface may be smaller than the diameter of the beam. The light source device may include a plurality of light-emitting elements each having an emission angle that can be individually controlled, and the controller may control the emission angle of each of the plurality of light-emitting elements.

[0017] In one embodiment, a repeater is used for optical power transmission over the water surface, and includes a sensor for measuring the state of the water surface, an optical system for receiving a beam from a light source or another repeater and directing it to a light receiving device or another repeater, and a controller for controlling the state of the beam from the optical system directed to the light receiving device or another repeater based on the state of the water surface indicated by the output of the sensor.

[0018] When the water surface is choppy, the incident angle of the beam on the water surface changes from moment to moment, and the optical energy reaching the receiver or another repeater is significantly affected by the water surface condition. Therefore, by monitoring the water surface condition and controlling the beam spatially and / or temporally, losses can be reduced and power supply efficiency can be improved.

[0019] In one embodiment, the period of the unevenness on the water surface is smaller than the diameter of the beam, and the controller may control the angle of incidence of each of the multiple portions of the beam with respect to the water surface.

[0020] (Embodiment) Preferred embodiments will be described below with reference to the drawings. The same or equivalent components, parts, and processes shown in each drawing will be designated by the same reference numerals, and redundant descriptions will be omitted where appropriate. Furthermore, the embodiments are merely examples and do not limit the invention, and all features and combinations thereof described in the embodiments are not necessarily essential to the invention.

[0021] (Embodiment 1) FIG. 1 is a diagram illustrating an optical power supply system 100A according to a first embodiment. The optical power supply system 100A includes a light source device 200A and a light receiving device 300. In the figure, 102 represents the water surface. In this embodiment, the light source device 200A is located in the air, and the light receiving device 300 is located underwater, specifically, in the ocean, a lake, or a river. The light receiving device 300 may be a device installed on the bottom of the ocean, lake, or river, or may be a device that moves underwater.

[0022] Furthermore, the light source device 200A may be mounted on a ship, an airplane, a drone, or the like, or in the case of a river or lake, may be infrastructure installed on the riverbank or lakeshore.

[0023] The positional relationship between the light source device 200A and the light receiving device 300 is not limited to that shown in FIG. 1, and the positions of the light source device 200A and the light receiving device 300 can be interchanged.

[0024] The light source device 200A is an optical transmitter, and irradiates an incident light beam L1 toward the light receiving device 300. The light receiving device 300 receives the light beam L1 from the light source device 200A and converts the light energy into electrical energy.

[0025] The light receiving device 300 includes a light receiving element 310 such as a solar cell, and an optical system 320. The optical system 320 shapes the light beam L1 so as to increase the efficiency at the light receiving element 310. The light receiving device 300 may be configured using the technology described in Patent Document 1.

[0026] In this embodiment, optical power supply is performed through the water surface 102. Because water and air have different refractive indices, the light beam L1 is refracted and reflected at the water surface 102. If the water surface 102 is wavy, the angle of incidence of the beam with respect to the water surface 102 changes from moment to moment, so the optical energy reaching the light receiving device 300 is significantly affected by the state of the water surface 102, and in some cases, the power supply efficiency may decrease significantly.

[0027] Figure 2 is a diagram illustrating the refraction of light on the water surface. Figure 2 shows a light ray L1 entering water from air. The angle between a tangent 104 at an incident point p on the water surface 102 and a horizontal plane 106 is θ. When the incident light ray is directed vertically, the angle of incidence is θ.

[0028] Reference numeral 120 schematically represents the effective light receiving surface of the light receiving device 300. The incident light ray L1 is emitted at an emission angle Ψ that corresponds to the inclination of the wavefront. When θ = 0°, the emission angle Ψ is also 0°, and the light travels vertically even underwater until it reaches the light receiving device 300. However, as the inclination θ of the wavefront increases, the incident angle θ also increases, and the light ray L1 is refracted at the water surface and deviates from the light receiving surface 120 of the light receiving device 300. The effect of refraction at the water surface becomes more pronounced as the depth d of the light receiving device 300 from the water surface increases.

[0029] Figure 3 is a diagram explaining the effect of a wavefront on a light beam. Here, we consider a case where the diameter of the beam (light beam) is longer than the wavelength. The horizontal axis x represents the horizontal position, and the vertical axis y represents the vertical position, both shown in arbitrary units. The water surface 102 is located at y=30, the wavelength λ is 1, and the instantaneous state is shown. The left diagram shows incidence from air into water, and (i) shows the intensity distribution at y=0. The right diagram shows incidence from water into air, and (ii) shows the intensity distribution at y=60. We can see that the beam spreads significantly due to the effect of refraction on the wavefront, and that the spread is greater when it goes from water into air.

[0030] If power is always supplied using the same beam regardless of the wavefront state, some or all of the optical energy will not reach the light receiving element, resulting in significant loss. In order to receive all of the optical energy, some measure is required on the light receiving device 300 side, such as increasing the area of ​​the light receiving element 310 or increasing the entrance aperture of the optical system 320.

[0031] In this embodiment, highly efficient power supply is achieved by performing beam control in accordance with the wavefront in the light source device 200A.

[0032] Returning to FIG. 1, the light source device 200A includes a light source 210, a sensor 220, and a controller 230. The light source 210 emits a beam BM toward a light receiving device 300 or a relay device located on the opposite side of the water surface 102. The light source 210 is configured to be able to control the state of the beam BM. The state of the beam BM can be the on / off state of the entire beam BM, the emission direction of the beam BM, the intensity distribution of the beam BM, the divergence angle of the beam BM, etc. Examples of the intensity distribution of the beam BM include the position of the peak, partial on / off state of the beam, the number of peaks, the beam diameter, and the type of beam profile.

[0033] The sensor 220 measures the state of the water surface 102. The state of the water surface 102 may include the geometric shape of the water surface and / or its changes over time. The sensor 220 may be a monocular camera or various three-dimensional sensors. Examples of three-dimensional sensors include a stereo camera, a pattern projection camera, a ranging sensor such as a LiDAR (Light Detection and Ranging) or a ToF camera, and a radar.

[0034] The controller 230 controls the light source 210 to change the state of the beam BM based on the state of the water surface 102 indicated by the output of the sensor 220 .

[0035] The above is the configuration of light source device 200A. When water surface 102 is rippling, the angle of incidence of the beam with respect to water surface 102 changes from moment to moment, and the optical energy reaching light receiving device 300 or the relay device is greatly affected by the state of water surface 102. Therefore, by monitoring the state of water surface 102 and controlling the beam spatially and / or temporally, it is possible to reduce losses and increase power supply efficiency.

[0036] Next, the state control of the beam BM by the controller 230 based on the state of the water surface 102 will be described based on several control examples.

[0037] (Control example 1) Fig. 4 is a diagram illustrating state control of the beam BM according to Control Example 1. This control example is effective when the period (wavelength) λ of the unevenness of the water surface 102 is larger than the diameter φ of the beam BM. Fig. 4 shows a state in which a traveling wave is generated on the water surface 102. The vertical axis represents time, and the horizontal axis represents horizontal position.

[0038] In this example, the incident position, emission direction, and intensity distribution of the beam BM are assumed to be constant. The controller 230 controls the on / off of the beam BM. Specifically, when the beam BM passes through the water surface 102 and reaches the light receiving device 300, the beam BM is turned on, and when the beam BM deviates from the light receiving device 300, the beam BM is turned off.

[0039] In this example, the light source device 200A is located directly above the light receiving device 300, and the beam BM is turned on during the period when the beam BM is incident at the incident point P substantially perpendicular to the wavefront, i.e., during the period when the peak or valley of the traveling wave is located at the incident point P.

[0040] 5 is a diagram illustrating a modified example of the state control of the beam BM according to Control Example 1. The period (phase) during which the beam BM should be turned on is determined according to the relative positions of the light source device 200A and the light receiving device 300.

[0041] (Control example 2) 6 is a diagram illustrating state control of the beam BM according to Control Example 2. This control example is effective when the period (wavelength) λ of the unevenness of the water surface 102 is smaller than the diameter φ of the beam BM.

[0042] In Control Example 2, the intensity distribution of beam BM is controlled. For example, light source 210 of light source device 200A may include a plurality of light-emitting elements 212 arranged in a matrix and each of which can be independently controlled to be turned on and off. The intensity distribution is controlled by a combination of the on and off states of the plurality of light-emitting elements 212.

[0043] The controller 230 adaptively switches on and off each of the plurality of light emitting elements 212 depending on the state of the water surface 102. For each light emitting element 212, the control described in the control example 1 can be applied.

[0044] (Control example 3) 7 is a diagram illustrating state control of the beam BM according to Control Example 3. This control example is effective when the period (wavelength) λ of the unevenness of the water surface 102 is smaller than the diameter φ of the beam BM.

[0045] In Control Example 3, light source 210 of light source device 200A can include a plurality of light emitting elements 212 arranged in a matrix, the emission direction α of which can be controlled independently.

[0046] The controller 230 adaptively controls the emission direction of each of the plurality of light-emitting elements 212 according to the state of the water surface 102. The angle α is controlled so that the light beam emitted from each light-emitting element 212 reaches the light-receiving device 300.

[0047] Control examples 1 to 3 can be combined in any manner.

[0048] (Embodiment 2) 8 is a diagram showing an optical power supply system 100B according to embodiment 2. The optical power supply system 100B includes a light source device 200, a relay device 400B, and a light receiving device 300. The light source device 200 and the light receiving device 300 perform power supply over the water surface.

[0049] The repeater 400B receives the light beam from the light source device 200 and repeats it to the light receiving device 300. In FIG. 8, the repeater 400B is provided on the same side of the water surface as the light source device 200, but on the opposite side of the water surface from the light receiving device 300. In other words, the water surface 102 is located between the repeater 400B and the light receiving device 300. In this embodiment, the light source device 200 and the repeater 400B are located in the air, and the light receiving device 300 is located underwater. Alternatively, the light receiving device 300 may be located in the air, and the light source device 200 and the repeater 400B may be located underwater.

[0050] The relay device 400B includes an optical system 410, a sensor 420, and a controller 430.

[0051] The sensor 420 measures the state of the water surface 102. The sensor 420 corresponds to the sensor 220 in the first embodiment.

[0052] The optical system 410 receives the beam BM1 from the light source device 200 or another relay device and directs it to the light receiving device 300 or another relay device (not shown) located on the other side of the water surface 102. The optical system 410 may be a reflective optical system, a transmissive optical system, or a combination thereof. For example, the optical system 410 may be an array of mirror elements whose tilt angles are independently controllable.

[0053] Based on the state of the water surface 102 indicated by the output of the sensor 420, the controller 430 controls the state of the beam BM2 directed from the optical system 410 to the light receiving device 300 or to another relay device (not shown) so that all or most of the beam BM2 is received by the light receiving device 300.

[0054] 9 is a diagram illustrating state control of beam BM1 according to Control Example 4. Optical system 410 is a mirror array and includes multiple mirror elements 412 whose tilt angles can be controlled independently. Controller 430 controls the tilt angle of each mirror element 412 according to the state of water surface 102. This control is similar to that described in Control Example 3 in Embodiment 1.

[0055] As a modification of the second embodiment, the optical system 410 may control the spread angle (divergence angle) of the beam BM2 depending on the state of the water surface 102.

[0056] 10 is a diagram illustrating an optical power supply system 100C according to a modification of the second embodiment. The optical power supply system 100C includes a light source device 200, a repeater device 400C, and a light receiving device 300. In this modification, the repeater device 400B is provided on the opposite side of the water surface from the light source device 200 and on the same side as the light receiving device 300. In other words, the water surface 102 is located between the light source device 200 and the repeater device 400C. In this modification, the light source device 200 is located in the air, and the repeater device 400C and the light receiving device 300 are located underwater. In yet another modification, the light receiving device 300 and the repeater device 400C may be located in the air, and the light source device 200 may be located underwater.

[0057] The relay device 400C includes an optical system 410, a sensor 420, and a controller 430.

[0058] The sensor 420 measures the state of the water surface 102. The optical system 410 receives the beam BM1 from the light source device 200 or another relay device through the water surface 102 and directs it to the light receiving device 300 or another relay device (not shown). The optical system 410 may be a reflective optical system, a transmissive optical system, or a combination thereof. For example, the optical system 410 may be an array of mirror elements whose tilt angles are independently controllable.

[0059] Based on the state of the water surface 102 indicated by the output of the sensor 420, the controller 430 controls the state of the beam BM2 directed from the optical system 410 to the light receiving device 300 or to another relay device (not shown) so that all or most of the beam BM2 is received by the light receiving device 300.

[0060] The present disclosure has been described using specific terms based on the embodiments, but the embodiments merely illustrate the principles and applications of the present disclosure, and many modifications and changes in arrangement are permitted to the embodiments as long as they do not deviate from the concept of the present invention defined in the claims. [Explanation of symbols]

[0061] 100...optical power supply system, 102...water surface, 200A...light source device, 210...light source, 220...sensor, 230...controller, 300...light receiving device, 310...light receiving element, 320...optical system, L1...light beam, 400B...relay device, 400C...relay device, 410...optical system, 420...sensor, 430...controller.

Claims

1. A light source device used for optical power supply over water, a sensor for measuring the state of the water surface; a controller that controls the state of a beam directed to a light receiving device or a relay device located on the opposite side of the water surface based on the state of the water surface indicated by the output of the sensor; A light source device comprising:

2. the period of the irregularities on the water surface is greater than the diameter of the beam; 2. The light source device according to claim 1, wherein the controller controls turning on and off of the beam.

3. The period of the irregularities on the water surface is smaller than the diameter of the beam, 2. The light source device according to claim 1, wherein the controller controls the intensity distribution of the beam.

4. The period of the irregularities on the water surface is smaller than the diameter of the beam, 2. The light source device according to claim 1, wherein the controller controls the angle of incidence of each of the plurality of beam portions with respect to the water surface.

5. A repeater device used for optical power supply over water, a sensor for measuring the state of the water surface; an optical system for receiving a beam from a light source device or another relay device and directing it to a light receiving device or yet another relay device; a controller that controls the state of a beam from the optical system toward the light receiving device or the further relay device based on the state of the water surface indicated by the output of the sensor; A relay device comprising:

6. The period of the irregularities on the water surface is smaller than the diameter of the beam, 6. The relay device according to claim 5, wherein the controller controls the angle of incidence of each of the beam portions with respect to the water surface.

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