JP7210000B2 - Receiver module and optical power supply system - Google Patents

Description

The present invention relates to an optical power feeding system.

Wireless power supply to electronic devices such as smartphones and tablet terminals has been put into practical use. Wireless power supply currently in practical use uses electromagnetic waves in a frequency band of several hundreds of kHz, and known methods include an electromagnetic induction method and a magnetic resonance method. Although light is essentially a kind of electromagnetic wave, simply referring to electromagnetic wave in this specification means an electromagnetic wave having a longer wavelength than light.

Optical power supply using light instead of electromagnetic waves has been proposed. Light has a characteristic of having strong directivity compared to electromagnetic waves. Therefore, by using a beam with a small divergence angle, there is an advantage that energy can be efficiently propagated over a long distance with little attenuation.

The light receiving module has photoelectric conversion elements such as solar cells. The present inventor has studied the light receiving module and has come to recognize the following problems.

FIGS. 1(a) and 1(b) are diagrams showing the positional relationship between the solar cell 2 and the light beam 4 incident thereon, and the intensity distribution (cross-sectional profile) of the light beam 4. FIG. A dashed line 5 indicates a range irradiated with the light beam 4 . The solar cell 2 is generally rectangular (square here) because it is manufactured using a semiconductor manufacturing process. On the other hand, the light beam 4 incident on the solar cell 2 often has a circular profile due to limitations of the optical system.

In FIG. 1( a ), the diameter of the light beam 4 is equal to or smaller than the side of the solar cell 2 . In this case, the area (hatched) of the solar cell 2 which is not irradiated with the light beam 4 does not contribute to power generation and is wasted.

In FIG. 1( b ) the diameter of the light beam 4 is longer than the diagonal of the solar cell 2 . In this case, the entire surface of the solar cell 2 is irradiated with the light beam 4, but part of the end of the light beam 4 is wasted. In addition, in the case of FIGS. 1(a) and 1(b), the center of the light beam 4 does not necessarily coincide with the solar cell 2, and if the irradiation position of the light beam 4 is shifted, the light beam is further wasted. .

The open-circuit voltage per cell of the solar cell 2 is 0.5 to 0.6 V in the case of silicon, making it difficult to use depending on the application. For applications requiring an open-circuit voltage of several volts, a solar cell module 2A in which a plurality of cells are electrically connected in series to increase the open-circuit voltage is used. 2A and 2B are diagrams showing a solar cell module 2A including a plurality of cells 6. FIG. As shown in FIG. 2(a), for example, a plurality of cells 6_1 to 6_n are arranged along one direction (x direction in the figure) of the module. FIG. 2(b) shows an equivalent circuit diagram of the solar cell module 2A.

In order to fully demonstrate the performance of the solar cell module 2A, all of the plurality of cells 6_1 to 6_n must be irradiated with light, and the entire light receiving surface of the module must be uniformly irradiated with light beams. There is

Thus, conventionally, it is difficult to say that the solar cell (or solar cell module) has not been able to exhibit all of its performance, or that all of the energy of the incident beam has been effectively utilized. In other words, there is still room for improvement in the performance of the receiver module.

The present invention has been made in this context, and one exemplary object of certain aspects thereof is to improve the performance of a light receiving module.

One aspect of the present invention relates to a light receiving module. The light receiving module receives the light beam from the light source module. The light receiving module includes a photoelectric conversion element and an optical system including a pair of fly-eye lenses and an imaging lens provided on the path of the light beam incident on the photoelectric conversion element.

According to this aspect, the entire surface of the photoelectric conversion element can be irradiated with a uniform light beam, and the performance of the light receiving module can be improved.

A photoelectric conversion element may include a plurality of cells connected in series. In this case, since a plurality of cells can be uniformly irradiated with light beams, the performance of the photoelectric conversion element can be exhibited.

The shape of the lens element forming the fly-eye lens may be substantially the same as the shape of the light receiving region of the photoelectric conversion element. This makes it possible to irradiate the entire light-receiving region of the photoelectric conversion element with the beam.

The optical system may further include a first reflector that surrounds the space sandwiched between the imaging lens and the photoelectric conversion element. When a light beam is incident on the incident surface of the light-receiving module at a large incident angle, the light passing through the imaging lens attempts to form an image at a position deviated from the light-receiving surface of the photoelectric conversion element. By providing the plate, the light that has passed through the imaging lens can be returned onto the light receiving surface.

The optical system may further include a second reflector covering a space sandwiched between the pair of fly-eye lenses on the incident surface side and the imaging lens. This makes it possible to confine light that tends to dissipate.

The optical system may further include a third reflector surrounding a space on the light source module side of the pair of fly-eye lenses on the incident surface side. Thereby, the light beam irradiated outside the fly-eye lens can be forced to enter the fly-eye lens.

Another aspect of the invention relates to an optical feeding system. The optical feeding system may comprise a light source module for emitting a light beam and a light receiving module.

Arbitrary combinations of the above constituent elements, or conversions of the expressions of the present invention between methods, apparatuses, and the like are also effective as embodiments of the present invention.

Furthermore, the description in this section (Summary of the Invention) does not describe all the essential features of the invention, and thus subcombinations of those described features can also be the invention. .

According to one aspect of the invention, the performance of the receiver module can be improved.

FIGS. 1(a) and 1(b) are diagrams showing a solar cell, the positional relationship of light beams incident thereon, and the intensity distribution (cross-sectional profile) of the light beams. FIGS. 2(a) and 2(b) are diagrams showing a solar cell module including a plurality of cells. 1 is a diagram showing an optical power supply system according to an embodiment; FIG. FIG. 4 is an optical path diagram of the optical feeding system of FIG. 3; FIGS. 5(a) to 5(c) are diagrams for explaining the homogenization of the intensity distribution of the beam. FIGS. 6A to 6C are diagrams explaining another example of homogenization of the beam intensity distribution. 7A and 7B are diagrams for explaining the offset of the incident light beam. 4 is a diagram illustrating what happens when an incident light beam is incident on the receiver module of FIG. 3 at a non-zero angle of incidence; FIG. It is a figure which shows the light receiving module which concerns on a 1st modification. FIGS. 10A to 10C are diagrams for explaining the functions of the first reflector, the second reflector, and the third reflector.

BEST MODE FOR CARRYING OUT THE INVENTION The present invention will be described below based on preferred embodiments with reference to the drawings. The same or equivalent constituent elements, members, and processes shown in each drawing are denoted by the same reference numerals, and duplication of description will be omitted as appropriate. Moreover, the embodiments are illustrative rather than limiting the invention, and not all features and combinations thereof described in the embodiments are necessarily essential to the invention.

FIG. 3 is a diagram showing an optical power feeding system 100 according to an embodiment. The optical power feeding system 100 includes a light source module 200 and a light receiving module 300 .

The light source module 200 irradiates the light receiving module 300 with the incident light beam L1. The light receiving module 300 receives the incident light beam L1 from the light source module 200 and converts it into an electrical signal. The positional relationship between the light source module 200 and the light receiving module 300 is indefinite, and therefore the position and angle of incidence of the incident light beam L1 incident on the light receiving module 300 are not always ideal.

A light receiving module 300 includes a solar cell 310 and an optical system 320 . The solar cell 310 is a photoelectric conversion element that converts incident light into an electrical signal. Solar cell 310 may consist of a single cell, but may preferably include multiple cells connected in series. A plurality of cells may be arranged in a row and connected in series, arranged in two rows and connected in series by folding back, or arranged in three or more rows and connected in a meandering manner. and the connection is not limited.

The optical system 320 is provided on the path of the incident light beam L1 incident on the solar cell 310, homogenizes the incident light beam L1, and irradiates the entire light receiving surface 312 of the solar cell 310 with it.

Optical system 320 includes a pair of fly-eye lenses 322 and 324 and an imaging lens 326 . Each of the fly-eye lenses 322 and 324 is an array of a plurality of plano-convex lens elements LE arranged in a matrix, and the two fly-eye lenses 322 and 324 are arranged to face each other. The configuration of the fly-eye lens is not limited to this, and may be biconvex. Alternatively, a gradient index lens having a flat surface on both sides may be used to provide a lens function by controlling the refractive index distribution in the lens material. The focal length of each lens element LE is equal.

The fly-eye lens 322 on the light source module 200 side is called a first fly-eye lens, and the fly-eye lens 324 on the solar cell 310 side is called a second fly-eye lens for distinction. The space between the first fly-eye lens 322 and the second fly-eye lens 324 may be filled with glass, so the pair of fly-eye lenses 322 and 324 may be integrally molded.

The first fly-eye lens 322 splits the light beam (luminous flux) from the light source module 200 . The first fly-eye lens 322 functions as a plurality of secondary light sources. A second fly-eye lens 324 is arranged at the focal point of the first fly-eye lens 322 . The imaging lens 326 magnifies and forms an image of each lens element LE of the first fly-eye lens 322 on the light receiving surface 312 of the solar cell 310 . Therefore, the shape of the beam irradiated onto the light receiving surface of the solar cell 310 is defined by the shape of each lens element LE. For this reason, the shape of each lens element LE is substantially the same as the shape of the solar cell 310, and the magnification is determined so that the image of the lens element LE is enlarged and projected onto the entire solar cell 310. It becomes possible to irradiate the beam over the entire area, and the light utilization efficiency can be improved. In the present embodiment, since the solar cell 310 is rectangular, a fly-eye lens having a rectangular lens element LE may be employed. If the light-receiving area of the solar cell 310 is hexagonal, a fly-eye lens having hexagonal lens elements LE may be employed.

The above is the configuration of the optical power supply system 100 . FIG. 4 is an optical path diagram of the optical feeding system 100 of FIG. The X section is shown here. Let h be the height of the lens element LE of each of the first fly-eye lens 322 and the second fly-eye lens 324 , f be the focal length, and F be the focal length of the imaging lens 326 .

At this time, the width ΔX of the beam projected onto the light receiving surface 312 is given by Equation (1).
ΔX=F/f・h
The optical system 320 of the light receiving module 300 is designed so that ΔX is substantially the same as the size (horizontal width) of the light receiving surface 312 of the solar cell 310 .

Note that the light receiving module 300 may be configured with an anamorphic optical system having different optical characteristics with respect to the X axis and the Y axis. When the intensity distribution in the X direction of the light flux incident on each lens element LE of the first fly-eye lens 322 can be regarded as uniform, the intensity distribution within the width ΔX on the light receiving surface 312 is uniform.

FIGS. 5(a) to 5(c) are diagrams for explaining the homogenization of the intensity distribution of the beam. FIG. 5(a) shows the intensity distribution of the incident light beam L1. Although the intensity distribution is schematically shown by linear approximation, it may be Gaussian distribution or other distributions. An incident light beam L1 is incident on a plurality of lens elements LE1-LE4. FIG. 5(b) shows the intensity distribution on the light receiving surface 312 of light that has passed through each of the plurality of lens elements LE1 to LE4. The light-receiving surface 312 is irradiated with these four lights superimposed. FIG. 5(c) shows the intensity distribution on the light receiving surface 312 obtained by superimposing the four beams.

FIGS. 6A to 6C are diagrams explaining another example of homogenization of the beam intensity distribution. FIG. 6A shows another intensity distribution example of the incident light beam L1. In this example, the intensity is uneven, but the intensity distribution can be regarded as uniform within one lens element LE.

FIG. 6B shows the intensity distribution on the light receiving surface 312 of light that has passed through each of the lens elements LE1 to LE4. The light-receiving surface 312 is irradiated with these four lights superimposed. FIG. 6C shows the intensity distribution on the light receiving surface 312 obtained by superimposing the four beams.

As described above, according to the light receiving module 300 , the incident light beam L<b>1 having a non-uniform intensity distribution can be made uniform and radiated onto the light receiving surface 312 of the solar cell 310 . In particular, when the solar cell 310 is a series connection of a plurality of cells, all the cells can be effectively generated by uniform irradiation, and the power generation capacity of the solar cell 310 can be maximized.

In addition, since the incident light beam L1 may be non-uniform, the structure of the light source module 200 can be simplified, and the cost of the light source module 200 can be reduced.

According to the light-receiving module 300, even when the incident light beam L1 is offset and incident, the light-receiving surface 312 of the solar cell 310 can be irradiated with a uniform beam, as described below. FIGS. 7A and 7B are diagrams for explaining the offset of the incident light beam L1. The light source module 200 includes multiple light sources 202 and multiple collimating lenses 204 . The light source 202 may be a laser light source such as a vertical cavity surface emitting laser (VCSEL), or another semiconductor light source such as an LED (light emitting diode). Alternatively, the light source may be of a type other than a semiconductor light source, such as a halogen lamp or a discharge tube. If the divergence angle of the beam of the light source 202 is not so large, the collimating lens 204 can be omitted.

In FIG. 7A, the incident light beam L1 is incident on the center of the optical system 320. In FIG. In FIG. 7B, the incident light beam L1 is incident on the upper side of the optical system 320 with an offset. In either case, the light receiving surface 312 of the solar cell 310 is irradiated with a uniform beam.

(Modification)
FIG. 8 shows what happens when the incident light beam L1 is incident on the receiver module 300 of FIG. 3 at a non-zero angle of incidence. The optical system 320 of the light receiving module 300 has an allowable incident angle θ that satisfies Equation (2).
tan θ _MAX =h/2f
When the incident angle θ of the incident light beam L1 exceeds the allowable incident angle θ _max , the light emitted from the imaging lens 326 is irradiated onto an area ΔX′ shifted in the X direction by ΔX from the original irradiation area ΔX. Since the region ΔX′ is outside the light receiving surface 312 of the solar cell 310, it can be said that the light receiving module 300 of FIG. 3 has a limited angle of incidence. This problem is solved by the first variant.

FIG. 9 is a diagram showing a light receiving module 300A according to the first modified example. An optical system 320A of the light receiving module 300A includes a first reflector 330, a second reflector 332, and a third reflector 334 in addition to the optical system 320 of FIG.

The first reflector 330 surrounds the space sandwiched between the imaging lens 326 and the solar cell 310 .

The second reflector 332 surrounds the space sandwiched between the first fly-eye lens 322 and the imaging lens 326 .

The third reflector 334 surrounds the space on the light source module 200 side of the first fly-eye lens 322 .

In the first modified example, the shape of the first fly-eye lens 322 and the second fly-eye lens 324, the shape of the light receiving area, and the shape of the lens element are preferably substantially the same. Furthermore, these shapes may be substantially the same as the shape of the light beam incident on the receiver module 300 .

In practice, the first to third reflectors 330 to 334 are cylindrical and include a plurality of reflecting surfaces surrounding corresponding spaces, but only two reflecting surfaces are shown in FIG. If the fly-eye lens or the like is N-sided, each of the first to third reflectors 330 to 334 can include N reflecting surfaces forming a cylinder.

10A to 10C are diagrams for explaining the functions of the first reflector 330, the second reflector 332, and the third reflector 334. FIG. The function of the first reflector 330 will be described with reference to FIG. 10(a). As described above, when the incident angle θ of the incident light beam L1 is large, the light L2 that has passed through the imaging lens 326 is emitted toward the area ΔX'. This light L2 is reflected by one reflecting surface of the first reflecting plate 330 and is irradiated onto the light receiving surface 312 of the solar cell 310 .

The function of the second reflector 332 will be described with reference to FIG. 10(b). A portion L3 of the light beam that has passed through the first fly-eye lens 322 can be emitted outside the range of the second fly-eye lens 324 . A portion L4 of the light beam that has passed through the second fly-eye lens 324 can be emitted outside the range of the imaging lens 326. FIG. The second reflector 332 can reflect a portion L3 of these rays to enter the second fly-eye lens 324, and can reflect a portion L4 of the rays to enter the imaging lens 326. can.

The function of the third reflector 334 will be described with reference to FIG. 10(c). A part (or all) L5 of the incident light beam L1 from the light source module 200 (not shown) may be incident outside the first fly-eye lens 322 . By providing the third reflector 334 , it is possible to reflect this light ray L<b>5 and make it enter the first fly-eye lens 322 .

By providing the first reflecting plate 330, the second reflecting plate 332, and the third reflecting plate 334 in this way, the light utilization efficiency can be further increased.

Although the present invention has been described using specific terms based on the embodiments, the embodiments merely show the principles and applications of the present invention, and the embodiments are defined in the scope of claims. Many modifications and changes in arrangement are permitted without departing from the spirit of the present invention.

REFERENCE SIGNS LIST 100 optical feeding system 200 light source module 202 light source 204 collimating lens 300 light receiving module 310 solar cell 312 light receiving surface 320 optical system 322 first fly eye lens 324 second fly eye lens LE lens element 326 imaging lens 330 first reflector 332 second 2 Reflector 334 Third Reflector L1 Incident light beam

Claims (6)

A light receiving module for receiving a light beam from a light source module,
a photoelectric conversion element;
a pair of fly-eye lenses and an imaging lens provided on a path of the light beam incident on the photoelectric conversion element; and a first reflector covering a space sandwiched between the imaging lens and the photoelectric conversion element. an optical system including,
with
The shape of the pair of fly-eye lenses, the shape of the lens elements constituting the fly-eye lenses, and the shape of the light receiving area of the photoelectric conversion element are N-sided. A light receiving module comprising a reflective surface . 2. The light receiving module according to claim 1, wherein said photoelectric conversion element includes a plurality of cells connected in series. 3. The optical system according to claim 1 , wherein the optical system further includes a lens on the incident surface side of the pair of fly-eye lenses, and a second reflector covering a space sandwiched between the imaging lenses. receiver module. 4. The optical system according to any one of claims 1 to 3 , wherein the optical system further includes a third reflector surrounding a space closer to the light source module than the lenses on the incident surface side of the pair of fly-eye lenses. A light receiving module as described. The shape of the pair of fly-eye lenses, the shape of the lens elements constituting the fly-eye lenses, and the shape of the light receiving area of the photoelectric conversion element are substantially the same as the shape of the light beam from the light source module. 5. The light receiving module according to any one of claims 1 to 4 , characterized by: a light source module for emitting a light beam;
a light receiving module according to any one of claims 1 to 5 ;
An optical power supply system comprising:

Images