JP7549996B2 - Non-contact power supply system - Google Patents

Description

The present invention relates to a non-contact power supply system that can transmit power wirelessly.

A method using electromagnetic induction, as disclosed in Patent Document 1, is known as a contactless power supply system. The electromagnetic induction method is based on Faraday's law of electromagnetic induction, and by bringing a secondary coil (power receiving coil) close to a primary coil (power transmitting coil) to which a voltage is applied, power can be generated in the secondary coil. This electromagnetic induction power supply system has a simple structure and can be manufactured at low cost. For this reason, electromagnetic induction power supply systems have become popular in recent years in various fields, such as charging various electronic devices such as electric shavers and smartphones, and supplying power to electric vehicles.

However, with the electromagnetic induction method, power can only be transmitted over a distance of about a few centimeters, so even though it is non-contact, it is only suitable for short-distance power supply. In addition, to transmit power, the secondary coil must be placed stationary in an accurate position relative to the primary coil. For this reason, electromagnetic induction power supply systems are not suitable for supplying power to moving objects or devices installed on moving objects.

JP 2013-093429 A

The present invention was made in consideration of the above-mentioned circumstances, and its purpose is to provide a power supply system capable of contactlessly supplying power to a mobile body or to equipment installed on a mobile body.

In order to achieve the above object, a power supply system according to the present invention comprises:
a power transmission device having a power transmission unit that transmits energy waves to the outside;
a power receiving device having a power receiving unit that receives the energy wave supplied from the power transmitting unit in a non-contact manner and converts the energy wave into electrical energy,
The power transmitting unit has at least one power transmitting side vibrator that vibrates elastically at a first natural frequency,
The power receiving unit has at least one power receiving side vibrator that is induced by the energy wave generated by the elastic wave vibration of the power transmitting side vibrator to elastically vibrate at a second natural frequency.

The power supply system according to the present invention described above is a mechanism for transmitting power contactlessly by using the resonance of elastic wave vibrations that occur between the power transmitting unit and the power receiving unit. This power supply system that uses the resonance of elastic wave vibrations is capable of transmitting power over medium to long distances (close distances to several meters). Therefore, the power supply system according to the present invention can be suitably used for supplying power to a mobile object and to equipment installed on the mobile object.

In addition, in the power supply system according to the present invention, the power transmitting side vibrator, which is the smallest unit that supplies energy waves to the power receiving unit, can be made to be 1 mm square or less in size. Similarly, the power receiving side vibrator, which is the smallest unit that converts the energy waves supplied from the power transmitting unit into electrical energy, can also be made to be 1 mm square or less in size. Therefore, in the power supply system according to the present invention, it is easy to miniaturize the power transmitting device and the power receiving device, and even if they are miniaturized, power transmission over medium to long distances can be achieved.

In addition, in the above, the energy wave supplied from the power transmission unit can be an electromagnetic wave or an alternating magnetic field.

Preferably, the second natural frequency of the power receiving vibrator is substantially the same as the first natural frequency of the power transmitting vibrator. In this way, by matching the natural frequency of the power transmitting vibrator with the natural frequency of the power receiving vibrator, the efficiency of power transmission can be improved.

Preferably, the power transmitting side vibrator has a piezoelectric layer and a magnetostrictive layer, and the power receiving side vibrator has a piezoelectric layer and a magnetostrictive layer. And, preferably, the piezoelectric layer of the power transmitting side vibrator and the piezoelectric layer of the power receiving side vibrator are made of substantially the same material, and the magnetostrictive layer of the power transmitting side vibrator and the magnetostrictive layer of the power receiving side vibrator are made of substantially the same material.

Preferably, the power transmitting unit includes a power transmitting antenna element having a plurality of the power transmitting side vibrators. The presence of a plurality of power transmitting side vibrators makes it possible to increase the power transmitted from the power transmitting unit to the power receiving unit. Also, preferably, the power receiving unit has a power receiving antenna element having a plurality of the power receiving side vibrators. The presence of a plurality of power receiving side vibrators makes it possible to increase the output power generated in the power receiving unit. For example, in the above power receiving antenna element, when a plurality of power receiving side vibrators are arranged in series, the output current can be increased. On the other hand, in the above power receiving antenna element, when a plurality of power receiving side vibrators are arranged in parallel, the output voltage can be increased.

In addition, as described above, in the power supply system according to the present invention, it is possible to adjust the magnitude of the transmitted power by adjusting the number of extremely small oscillators (power transmitting oscillators and power receiving oscillators). In other words, in the power supply system according to the present invention, the transmitted power can be easily increased by adjusting the number of extremely small oscillators without making the power receiving unit or the power transmitting unit more complex or larger.

Preferably, the power transmitting device has directivity control means for controlling the directivity of the energy wave transmitted from the power transmitting unit. By controlling the directivity of the energy wave by the directivity control means, it is possible to further improve the efficiency of power transmission.
In addition, preferably, the power transmitting device has a phase shifter for controlling the phase of the power transmitting unit as the directivity control means. When the power transmitting device has the above configuration, in the power supply system according to the present invention, the directivity of the energy wave can be more effectively controlled by beamforming using the phase shifter, and the efficiency of power transmission can be further improved.

Preferably, the elastic wave vibration of the power transmitting side vibrator and the elastic wave vibration of the power receiving side vibrator are both bulk elastic waves.
Preferably, the vibration mode of the elastic wave vibration in the power transmitting side vibrator and the vibration mode of the elastic wave vibration in the power receiving side vibrator are both in-plane stretching vibrations.
By each of the vibrators (the power transmitting side vibrator and the power receiving side vibrator) having the vibration mode described above, the efficiency of power transmission can be further improved.

In the power supply system according to the present invention, the power receiving device incorporated in the object to be powered can be easily miniaturized. Therefore, the power supply system according to the present invention is particularly suitable for use in power supply to a wearable terminal attached to the human body (a type of moving object) or for power supply to electronic devices attached inside the human body. Examples of electronic devices incorporating the power receiving device of the present invention include hearable devices such as earphones and hearing aids, smart watches, smart glasses, smart contact lenses, wearable thermometers, wearable pulse wave sensors, and other wearable terminals, as well as artificial cochleas and cardiac pacemakers attached inside the human body, electrical stimulation devices for muscles and the brain, neuro-RFID, and microrobots.

FIG. 1 is a block diagram showing a power supply system according to an embodiment of the present invention. FIG. 2 is a block diagram showing a directivity control means in one embodiment of the present invention. FIG. 3 is a schematic plan view showing an antenna element in one embodiment of the present invention. FIG. 4 is an enlarged plan view of region IV shown in FIG. FIG. 5 is a cross-sectional view taken along line VV shown in FIG. FIG. 6 is a cross-sectional view taken along the line VI-VI shown in FIG. FIG. 7 is a graph showing the frequency characteristics of the vibrator. FIG. 8 is a schematic diagram showing a usage form of the power supply system shown in FIG. FIG. 9 is a plan view showing a modified example of the vibrator. FIG. 10 is a plan view showing a modified example of the vibrator. FIG. 11 is a schematic cross-sectional view showing a modified example of the vibrator.

The present invention will now be described in detail with reference to the embodiments shown in the drawings.

As shown in Fig . 1 , a power supply system 1000 according to an embodiment of the present invention includes a power transmission device 300, an electronic device 200 that is a power supply target, and a power receiving device 100 mounted inside the electronic device. The power transmission device 300 is installed at a location away from the electronic device 200, and a power transmission unit 310 that transmits energy waves E to the outside is mounted inside the power transmission device 300. Meanwhile, a power receiving unit 110 is mounted inside the power receiving device 100, and this power receiving unit 110 receives the energy waves E supplied from the power transmission unit 310 in a non-contact manner and converts the energy waves E into electrical energy.

In the power supply system 1000 of this embodiment, the resonance of the elastic wave vibration occurring between the power transmission unit 310 and the power receiving unit 110 transmits power to the electronic device 200, which is the power supply target, in a non-contact manner. Each component of the power supply system 1000 will be described below.

In addition to the power transmission unit 310, the power transmission device 300 has a power source 320, which supplies the power required for emitting the energy wave E to the power transmission unit 310. The power source 320 may be a primary battery such as a manganese dry battery or a nickel-manganese dry battery, but is preferably a rechargeable secondary battery such as a Ni-metal hydride battery, a lithium-ion battery, or an all-solid-state battery.

As shown in FIG. 1, the power transmission section 310 of the power transmission device 300 is composed of at least one power transmission antenna element 10a. This power transmission antenna element 10a has a plate shape that is approximately rectangular in plan view. However, the shape of the power transmission antenna element 10a is not particularly limited, and may have a circular, elliptical, or other polygonal shape in plan view.

In FIG. 1, the power transmission unit 310 has multiple power transmission antenna elements 10a, and the multiple power transmission antenna elements 10a are arranged along two planar axis directions on the same plane. However, the arrangement of the power transmission antenna elements 10a is not limited to the form shown in FIG. 1, and the multiple power transmission antenna elements 10a may be arranged along one planar axis direction on the same plane, or may be arranged so as to be stacked along the thickness direction of the power transmission antenna elements 10a. As described above, the power transmission antenna element 10a constituting the power transmission unit 310 may be a single element, and the number of elements 10a is not particularly limited.

As shown in FIG. 3, the power transmission antenna element 10a has a substrate 6 and a plurality of power transmission side vibrators 4a formed on the substrate 6. The substrate 6 has a plane including the X-axis and the Y-axis, and a plurality of openings 61 are formed on the same plane (X-Y plane) on the substrate 6. The power transmission side vibrators 4a are formed above each opening 61. More specifically, the openings 61 are holes that penetrate the substrate 6 along the thickness direction (Z-axis direction) of the substrate 6, and have a substantially rectangular shape in plan view. The power transmission side vibrators 4a are located above the openings 61, bridging both ends of the openings 61 in the X-axis direction. In FIG. 3, the X-axis, Y-axis, and Z-axis are substantially perpendicular to each other.

The substrate 6 is also provided with electrodes 8, 9 that can be connected to a power source 320, and wiring 80, 90 that connects the electrodes 8, 9 to each of the power transmission side vibrators 4a. In the power transmission antenna element 10a shown in FIG. 3, the multiple power transmission side vibrators 4a are connected in parallel via the wiring 80, 90. The multiple power transmission side vibrators 4a can also be wired in series. However, in the power transmission antenna element 10a, it is preferable to connect the multiple power transmission side vibrators 4a in parallel in order to equalize the voltage applied to each power transmission side vibrator 4a.

In addition, FIG. 3 illustrates an example in which there are multiple power transmission side vibrators 4a in the power transmission antenna element 10a, but the number of power transmission side vibrators 4a included in one power transmission antenna element 10a may be one, and is not particularly limited.

In the power transmission unit 310, the total number of power transmission side vibrators 4a depends on the number of vibrators 4a included in one power transmission antenna element 10a and the number of power transmission antenna elements 10a. In the present embodiment, in Figs. 1 and 3, there are multiple power transmission side vibrators 4a in the power transmission unit 310, but it is sufficient that the power transmission unit 310 includes at least one power transmission side vibrator 4a. The power transmission side vibrator 4a is the smallest unit that generates the energy wave E to be supplied to the power receiving unit 110, and the more the number of power transmission side vibrators 4a is increased, the more the amount of power transmitted from the power transmission unit 310 to the power receiving unit 110 can be increased.

Figure 4 is an enlarged plan view of the main part of region IV in Figure 3, and is a plan view of the power transmission side vibrator 4a. As shown in Figure 4, the power transmission side vibrator 4a has a vibration part 41 located above the opening surface of the opening 61 at approximately the center in the X-axis direction, two fixed parts 42a, 42b located at both ends in the X-axis direction, and two support parts 43 connecting the vibration part 41 and the fixed parts 42a, 42b.

As shown in Figures 4 to 6, the vibration section 41 of the power transmission side vibrator 4a includes, as functional films, a piezoelectric layer 14 having piezoelectric properties and a magnetostrictive layer 16 having magnetostrictive properties. The piezoelectric layer 14 and magnetostrictive layer 16 are substantially parallel to the X-Y plane including the X-axis and Y-axis, and are laminated along a direction approximately perpendicular to the X-Y plane (i.e., the Z-axis direction). Note that "substantially parallel" means that most parts are parallel, but there may be some parts that are not parallel, and the piezoelectric layer 14 and magnetostrictive layer 16 may be slightly uneven or tilted.

In this embodiment, the power transmission side vibrator 4a (particularly the vibration section 41) is an elastic wave vibrator having a natural frequency Ft. When an electrical signal is supplied from the power source 320 and a voltage is applied to the power transmission side vibrator 4a, distortion occurs in the piezoelectric layer 14 of the power transmission side vibrator 4a due to the inverse piezoelectric effect. In the vibration section 41 of the power transmission side vibrator 4a, elastic wave vibrations of the natural frequency Ft are induced in response to the distortion of the piezoelectric layer 14.

On the other hand, in the magnetostrictive layer 16 of the power transmission side vibrator 4a, an inverse magnetostrictive effect occurs due to elastic wave vibration. In the power transmission side vibrator 4a, an electromagnetic wave or an AC magnetic field is generated due to the inverse magnetostrictive effect of the magnetostrictive layer 16, and this electromagnetic wave or AC magnetic field is radiated to the power receiving device 100 as an energy wave E. In other words, the power transmission side vibrator 4a converts the electrical energy supplied from the power source 320 into an energy wave E such as an electromagnetic wave or an AC magnetic field based on the inverse piezoelectric effect of the piezoelectric layer 14 and the inverse magnetostrictive effect of the magnetostrictive layer 16.

In the above, the natural frequency of the vibrator is the frequency at which the response output is maximum. In the case of the power transmitting vibrator 4a, the "response output" means the amplitude of the radiated energy wave E, and in the case of the power receiving vibrator 4b described below, the "response output" means the output power.

In this embodiment, the power transmission unit 310 may include a plurality of power transmission side vibrators 4a. In this case, it is preferable that the natural frequencies Ft of the power transmission side vibrators 4a are all approximately the same value. Specifically, it is preferable that the variation in the natural frequencies Ft of the power transmission side vibrators 4a is less than ±1%. The "variation in the natural frequency Ft" means the deviation when the average value of the natural frequencies Ft is used as a reference. In other words, when the average value of the natural frequencies Ft is Ft _A , it is preferable that the natural frequencies Ft of the power transmission side vibrators 4a are each within a range of less than Ft _A ±1%. In order to match the natural frequencies Ft of the plurality of power transmission side vibrators 4a, for example, it is sufficient to align the shapes of the power transmission side vibrators 4a to reduce the dimensional error.

In this way, by aligning the natural frequencies Ft of each power transmitting vibrator 4a, the amplitude of the radiated energy wave E can be increased, and the amount of power transmitted from the power transmitting unit 310 to the power receiving unit 110 can be increased.

As described above, in consideration of power transmission efficiency, it is preferable to make the natural frequencies Ft of the multiple power transmission side vibrators 4a uniform. However, the power transmission unit 310 may be configured with multiple power transmission side vibrators 4a with different natural frequencies Ft. In this case, it is possible to make the natural frequencies Ft of a single power transmission antenna element 10a uniform, and set different natural frequencies Ft between the multiple power transmission antenna elements 10a. It is also possible that a single power transmission antenna element 10a has power transmission side vibrators 4a with different natural frequencies Ft. For example, if the power transmission unit 310 has a group of vibrators with a natural frequency Ft1 and a group of vibrators with a natural frequency Ft2, such a power transmission device can transmit power to two types of power supply objects with different natural frequencies.

In addition, in this embodiment, the power transmission device 300 preferably has a directivity control means for controlling the directivity of the energy wave E supplied from the power transmission unit 310. This directivity control means is a means for concentrating the radiation of the energy wave E, such as an electromagnetic wave or an AC magnetic field, supplied from the power transmission antenna element 10a in a specific direction (i.e., in the direction in which the electronic device 200, which is the power supply target, is located). The energy wave E generated by the power transmission side vibrator 4a is usually radiated in all directions, so that a portion of the radiated energy wave E is lost during the power transmission process. By transmitting the energy wave E in a concentrating manner in a specific direction using the above-mentioned directivity control means, the loss of the energy wave E during the power transmission process is suppressed, and the power transmission efficiency is improved. In addition, it becomes possible to radiate the energy wave E further, and the transmission distance can be extended.

Directivity control means includes, for example, a method of adjusting the orientation of the power transmission antenna element 10a. The electromagnetic waves or AC magnetic fields generated by the power transmission side vibrator 4a are radiated in all directions, but the electric flux density or magnetic flux density tends to be highest in the direction perpendicular to the planar direction of the vibration part 41 (Z-axis direction). Therefore, the directivity of the electromagnetic waves or AC magnetic field can be improved by orienting the plane of the power transmission antenna element 10a (X-Y plane in FIG. 3) toward the direction of the object to be fed. The orientation of the power transmission antenna element 10a can be controlled simply by adjusting the installation position of the power transmission device 300. It is also possible to electrically change the orientation of the power transmission antenna element 10a after determining the position of the object to be fed by the position information search means.

As another example of the directivity control means, there is a beamforming directivity control means 330 as shown in FIG. 2. In this beamforming directivity control means 330, a phase shifter 331 is interposed in the circuit between the power source 320 and each power transmitting antenna element 10a, and this phase shifter 331 adjusts the phase of the energy wave E transmitted from the power transmitting antenna element 10a. In other words, the directivity control means 330 generates a phase difference between each power transmitting antenna element 10a, and adjusts the signal input to each power transmitting antenna element 10a so that the phases are reinforced only in a specific direction.

In addition, in the directivity control means 330, a control circuit 332 that manages each phase shifter 331 may be incorporated in the circuit between the power source 320 and each phase shifter 331. Furthermore, this control circuit 332 may incorporate a location information exploration means (for example, a means for sending a test signal to the object to be powered) for grasping the location information of the object to be powered. In addition to the phase shifter 331, an amplitude control means 333 such as a power amplifier for amplifying the amplitude of the energy wave E may be interposed in the circuit between the control circuit 332 and each power transmitting antenna element 10a.

Next, the power receiving device 100 will be described. The power receiving device 100 is configured by connecting and integrating a power receiving unit 110, a power management IC (PMIC) 120 equipped with a rectifier circuit, etc., and a capacitor 130. In addition to the above, the power receiving device 100 may also be equipped with a small secondary battery, such as a lithium polymer battery or an all-solid-state battery, as an auxiliary power source.

In the power receiving device 100 having the above configuration, the power receiving unit 110 receives the energy wave E in a non-contact manner and converts the energy wave E into electrical energy. The converted electrical energy is sent to the capacitor 130 via the PMIC 120 and stored in the capacitor 130. The electrical energy stored in the capacitor 130 is then sent from the capacitor 130 via the PMIC 120 to the components 210 of the electronic device 200, and consumed by each of the components 210. The components 210 of the electronic device 200 are parts that consume electrical energy and contribute to driving the electronic device 200. For example, if the electronic device 200 is an external ear canal-type earphone, the components 210 include a piezoelectric speaker, a piezoelectric microphone, a pressure sensor, an audio IC including an amplifier, and a memory device.

As shown in FIG. 1, the power receiving section 110 of the power receiving device 100 is composed of at least one power receiving antenna element 10b. Like the power transmitting antenna element 10a, this power receiving antenna element 10b has a plate shape that is approximately rectangular in plan view. However, the shape of the power receiving antenna element 10b is not limited to the above. Also, in FIG. 1, multiple power receiving antenna elements 10b are present in the power receiving section 110, but the number of power receiving antenna elements 10b may be single, and there is no particular limit to the number. Furthermore, when there are multiple power receiving antenna elements 10b, the arrangement method is not particularly limited, and they may be arranged on the same plane or stacked along the thickness direction of the element.

In this embodiment, the power receiving antenna element 10b can have a different shape from the power transmitting antenna element 10a, but it is preferable to use an antenna element having a shape similar to that of the power transmitting antenna element 10a. By configuring the power transmitting antenna element 10a and the power receiving antenna element 10b with antenna elements of the same shape, it becomes easier to adjust the natural frequency, which will be described later. In this embodiment, for the sake of simplicity, the antenna element shown in Figures 3 and 4, which is the same as the power transmitting antenna element 10a, is used as the power receiving antenna element 10b.

In this embodiment, the power receiving antenna element 10b has a power receiving side vibrator 4b, which is an elastic wave vibrator having a natural frequency Fr. When an energy wave E is radiated from the power transmitting side vibrator 4a of the power transmitting unit 310 to the power receiving unit 110, the power receiving side vibrator 4b (particularly the vibrating unit 41) is excited by the energy wave E and vibrates elastically. More specifically, when the vibrating unit 41 of the power receiving side vibrator 4b receives the energy wave E, distortion occurs in the magnetostrictive layer 16 of the vibrating unit 41 due to the magnetostrictive effect. In the vibrating unit 41 of the power receiving side vibrator 4b, elastic wave vibration of the natural frequency Fr is induced in response to the distortion of the magnetostrictive layer 16. In other words, in the power receiving unit 110, the power receiving side vibrator 4b resonates and vibrates elastically due to the elastic wave vibration of the power transmitting side vibrator 4a that generates the energy wave E.

When elastic wave vibrations are induced in the power receiving vibrator 4b, a piezoelectric effect is generated in the piezoelectric layer 14 of the power receiving vibrator 4b by the elastic wave vibrations. In the power receiving vibrator 4b, an electric charge is generated on the surface of the piezoelectric layer 14 due to the piezoelectric effect of the piezoelectric layer 14, and this electric charge can be extracted as electrical energy. In other words, the power receiving vibrator 4b converts the energy wave E supplied from the power transmitting device 300 into electrical energy by the magnetostrictive effect of the magnetostrictive layer 16 and the piezoelectric effect of the piezoelectric layer 14.

As described above, in the power receiving antenna element 10b of the power receiving unit 110, the power receiving vibrator 4b is the smallest unit that converts the energy wave E into electrical energy. The power receiving unit 110 may include at least one power receiving vibrator 4b, but it is preferable that there are multiple power receiving vibrators. The more the number of power receiving vibrators 4b is increased, the more electrical energy can be obtained and the power transmission efficiency is improved. In addition, when there are multiple power receiving vibrators 4b in the power receiving antenna element 10b, the power receiving vibrators 4b may be arranged in parallel or in series. When multiple power receiving vibrators 4b are connected in parallel, the output voltage can be increased, and when connected in series, the output current can be increased.

In this embodiment, the natural frequency Fr of the power receiving side vibrator 4b is preferably substantially the same as the natural frequency Ft of the power transmitting side vibrator 4a. By matching the natural frequency Fr of the power receiving side vibrator 4b with the natural frequency Ft of the power transmitting side vibrator 4a, it is possible to improve the power transmission efficiency. Here, "natural frequencies are substantially the same" means that the deviation D between the natural frequency Fr and the natural frequency Ft, expressed by the following formula (1), is less than 1%.
D=|Ft-Fr|/Ft×100(%)...(1)

When the power transmitting unit 310 includes a plurality of power transmitting side vibrators 4a and the natural frequencies Ft of the power transmitting side vibrators 4a are set to approximately the same value, the deviation D in the above formula (1) may be calculated based on the average value Ft _A of the natural frequencies Ft. In other words, each power receiving side vibrator 4b in the power receiving unit 110 may be designed so that the deviation D of the natural frequency Fr from the average value Ft _A is less than 1%. In addition, when the power transmitting unit 310 includes a plurality of power transmitting side vibrators 4a with different natural frequencies Ft, each power receiving side vibrator 4b in the power receiving unit 110 may be designed so that the natural frequency is substantially the same as any one of the plurality of power transmitting side vibrators 4a included in the power transmitting unit 310.

In order to match the natural frequencies between the power receiving side vibrator 4b of the power receiving unit 110 and the power transmitting side vibrator 4a of the power transmitting unit 310, it is preferable to match the shape of the power receiving antenna element 10b with the shape of the power transmitting antenna element 10a. In other words, it is preferable to use the same antenna element in each of the power receiving unit 110 and the power transmitting unit 310. The natural frequency of the elastic wave vibrator is determined not only by the shape and dimensions of the vibrator, but also by the characteristics of the functional membrane that constitutes the vibrator and the vibration form of the vibrator. Therefore, even if the shapes of the antenna elements are different, it is possible to match the natural frequency Ft and the natural frequency Fr. However, as described above, the method of using the same antenna element in the power receiving unit 110 and the power transmitting unit 310 is the simplest and has high manufacturing efficiency.

Also, although this overlaps with the above, when the power receiving unit 110 has a plurality of power receiving side vibrators 4b, it is preferable that the natural frequencies Fr of the power receiving side vibrators 4b are all approximately the same value. Specifically, when the average value _FrA of the natural frequencies Fr is used as a reference, it is preferable that the variation in the natural frequencies Fr of the power receiving side vibrators 4b is less than ±1%. By matching the natural frequencies Fr of the power receiving side vibrators 4b in this way, a larger electric energy can be obtained, and the power transmission efficiency is improved.

As described above, in consideration of power transmission efficiency, it is preferable to make the natural frequencies Fr of the multiple power receiving vibrators 4b uniform, but the power receiving unit 110 may include multiple power receiving vibrators 4b with different natural frequencies Fr. In this case, the frequency band to which the power receiving unit 110 can respond can be expanded. For example, if the power receiving unit has a vibrator with a natural frequency Fr1 and a vibrator with a natural frequency Fr2, the power receiving unit can receive and convert energy waves E1 with the same frequency as the natural frequency Fr1, and can also receive and convert energy waves E2 with the same frequency as the natural frequency Fr2.

In addition, in this embodiment, it is preferable that both the power transmitting side vibrator 4a and the power receiving side vibrator 4b have the characteristics described below. In the following paragraphs, in describing the characteristics common to the power transmitting side vibrator 4a and the power receiving side vibrator 4b, the power transmitting side vibrator 4a and the power receiving side vibrator 4b will be collectively referred to as "vibrator 4".

First, in this embodiment, the vibration part 41 of the vibrator 4 that vibrates in an elastic wave preferably has a Q value (no unit) of 100 or more, and more preferably 1000 or more. The Q value is a measure that indicates the sharpness of a peak in the frequency characteristics.

Here, the frequency characteristics of the vibration unit 41 will be described with reference to Fig. 7. In the graph shown in Fig. 7, the horizontal axis is frequency and the vertical axis is output voltage. As described above, at the natural frequency F, the output voltage is maximum (maximum output _V0 ), and the natural frequency F is the peak top. If the frequency at which an output voltage 1/√2 times the maximum output voltage _V0 ((1/√2) x _V0 ) is obtained on the high frequency side is _f1 , and the frequency at which an output voltage is (1/√2) x _V0 on the low frequency side is _f2 , the Q value is expressed by the following formula.
Q=F/(f ₁ - _{f 2} )

Conventionally, resonators that resonate with mechanical vibrations generated by automobiles, industrial machines, and the like have been known, and in order for such resonators to receive a wide signal (vibration), it was necessary to set the Q value low. In contrast, in the power supply system 1000 of this embodiment, the Q value of the vibrating unit 41 is set high, at 100 or more, thereby making it possible to further improve power transmission efficiency. The higher the Q value of the vibrating unit 41, the better, and the upper limit of the Q value is not particularly limited, but can be set to, for example, 50,000 or less, and preferably 10,000 or less.

In addition, in the frequency characteristic of the vibrator 4 shown in FIG. 7, the frequency shifted from the natural frequency F by F×(1/100) to the high frequency side is f _a (i.e., f _a =F+F×(1/100)), the frequency shifted from the natural frequency F by F×(1/100) to the low frequency side is f _b (i.e., f _b =F−F×(1/100)), and the outputs at the frequencies f _a and f _b are V _a and V _b , respectively. In this case, it is preferable to design the vibration unit 41 so that the maximum output V ₀ is twice or more the output V _a or V _b (i.e., V ₀ >2V _a , V ₀ >2V _b ). By the vibrator 4 having a frequency characteristic that satisfies the above conditions, the energy conversion efficiency of the vibrator 4 is improved, and the power transmission efficiency can also be improved.

In addition, in this embodiment, it is preferable that the vibrator 4 is a bulk acoustic wave vibrator that vibrates with bulk acoustic waves (BAW: Bulk Acoustic Wave) rather than surface acoustic waves (SAW: Surface Acoustic Wave). A surface acoustic wave vibrator utilizes waves (vibrations) that propagate to the surface of an object, whereas a bulk acoustic wave vibrator utilizes the vibration of the object itself, not the surface. In the power supply system of this embodiment, power transmission efficiency can be improved by using a bulk acoustic wave vibrator for the vibrator 4.

In addition, it is preferable that the vibration mode of the elastic wave vibration generated by the vibrator 4 is an in-plane stretching vibration rather than an out-of-plane vibration. Here, out-of-plane vibration means that the vibrator vibrates in a dynamic state without volume change such as rotation or bending. In the case of a vibrator that vibrates out-of-plane (especially in the case of a vibrator that vibrates bending), the natural frequency F of the vibrator tends to be a low frequency of 100 kHz or less. On the other hand, in-plane stretching vibration means that the vibrator vibrates by stretching along the X-Y plane or a plane including the Z axis. In this embodiment, the in-plane stretching vibration that stretches along the X-Y plane is called the spreading vibration, and the in-plane stretching vibration that stretches along the plane including the Z axis is called the thickness-extension vibration. In a vibrator that vibrates in-plane stretching vibration, the natural frequency F tends to be in a higher frequency band than a vibrator that vibrates out-of-plane, and between spreading vibration and thickness-extension vibration, the natural frequency F of the thickness-extension vibration tends to be in a higher frequency band. In the power supply system of this embodiment, the vibrator 4 is a bulk acoustic wave vibrator with in-plane stretching vibration, which can further improve power transmission efficiency.

The natural frequency F, Q value, frequency characteristics, and vibration mode of the vibrator 4 as described above can be measured using an impedance analyzer. The vibration mode of the vibrator 4 is determined by the material of the functional film (piezoelectric layer 14, magnetostrictive layer 16, etc.), the thickness of the functional film, the crystal orientation of the functional film, and the shape and dimensions of the vibrator 4.

(How the power supply system is used)
The power supply system 1000 according to the present embodiment is a mechanism for transmitting power contactlessly by the resonance of an elastic wave vibrator. The power supply system 1000 utilizing the resonance of this elastic wave vibration is capable of transmitting power not only over short distances of a few centimeters, but also over medium- to long-distances up to about 10 meters. Therefore, the power supply system 1000 according to the present embodiment can be suitably used for supplying power to a mobile body and to devices and the like installed on the mobile body.

A power supply system that uses magnetic resonance is also known as a medium-distance contactless power supply method. However, in a magnetic resonance power supply system, the amount of power that can be transmitted and the distance over which power can be transmitted depend on the diameter of the coil and the number of turns of the conductor in the coil. Therefore, in order to ensure sufficient transmission efficiency over medium distances in the magnetic resonance method, the dimensions of the primary coil and secondary coil become large, making it difficult to reduce the size.

In contrast, in the power supply system 1000 according to the present embodiment, the power transmission antenna element 10a and the power reception antenna element 10b can be manufactured by microfabrication technology such as that used in semiconductor manufacturing processes. The vibrator 4, which is the smallest unit of energy conversion, can be made to be 1 mm square or less in size. Therefore, in the power supply system 1000 according to the present embodiment, it is easier to miniaturize the power transmission device 300 and the power reception device 100 than in a power supply system using a magnetic field resonance method. Furthermore, in the power supply system 1000 according to the present embodiment, the transmission distance can be easily extended by increasing the number of the power transmission side vibrators 4a and/or the number of the power reception side vibrators 4b, and the amount of power to be transmitted can also be increased. Therefore, in the power supply system 1000 according to the present embodiment, even if the power transmission device 300 and the power reception device 100 (particularly the power reception device) are miniaturized, power transmission over medium to long distances can be realized.

8 is a schematic diagram showing an example of use of the power supply system 1000. Specifically, FIG. 8(a) shows an example of use in which the power receiving device 100 of this embodiment is incorporated into an earphone that is attached to the outer ear of the human body. FIG. 8(b) shows an example of use in which the power receiving device 100 of this embodiment is incorporated into a cardiac pacemaker that is attached to the human body. As shown in the examples of use in FIGS. 8(a) and 8(b), the power receiving device 100 can be incorporated into a wearable terminal that is attached to a person's arm or head, or a medical device that is attached to the human body. It is desirable for these electronic devices 200, such as wearable terminals and medical devices, to be small and lightweight. In the power receiving device 100 of this embodiment, the minimum unit of energy conversion is the very small power receiving side vibrator 4b, so that it is easy to reduce the size according to the specifications of the electronic device by appropriately adjusting the number of power receiving side vibrators 4b or the number of power receiving antenna elements 10b.

On the other hand, the power transmission device 300 is fixed to a belt located on the person's torso in FIG. 8(a), and is placed in a handbag in FIG. 8(b). As described above, the power supply system 1000 is capable of medium- to long-distance power transmission, so that when the power supply system 1000 is operated, the power transmission device 300 can be installed in a more stable location than the electronic device 200, such as the torso of a person who moves relatively little, a bag, or a carrying tool. Therefore, the power transmission device 300 can be made larger in size than the power receiving device 100, and the power transmission device 300 can be equipped with a power source 320 with a large volume. In addition, in the power receiving unit 310, it is easy to increase the number of power transmission side vibrators 4a and the number of power transmission antenna elements 10a, and the amount of power transmitted from the power transmission unit 310 to the power receiving unit 110 can be increased.

In this embodiment, the type of electronic device 200 to be supplied with power is not particularly limited. Examples of electronic devices 200 include the above-mentioned earphones and cardiac pacemakers, as well as hearable devices such as hearing aids, smart watches, smart glasses, smart contact lenses, wearable thermometers, wearable pulse wave sensors, artificial cochlea, electrical stimulation devices for muscles and the brain, neuro-RFID, and microrobots.

Second embodiment In the second embodiment, the case where the vibrator 4 (the power transmitting side vibrator 4a and the power receiving side vibrator 4b) is a bulk acoustic wave vibrator with in-plane stretching vibration is illustrated, and the optimal configuration for obtaining the bulk acoustic wave vibration with in-plane stretching vibration is described. In the second embodiment, the power transmitting antenna element 10a and the power receiving antenna element 10b are both configured with the same antenna element 10, and the power transmitting side vibrator 4a and the power receiving side vibrator 4b have the same configuration. Note that in the second embodiment, referring to Figures 3 to 6, the same symbols are used for the configurations common to the first embodiment.

First, we will describe in detail the morphological characteristics of the vibrator 4 in the antenna element 10.

As shown in FIG. 3, the bottom layer of the antenna element 10 in the Z-axis direction is a substrate 6 having an outer edge shape of a substantially rectangular shape in a plan view. The plan view shape of the substrate 6 is not particularly limited, and may be a circle, an ellipse, a rectangle with rounded corners, or another polygon. The thickness of the substrate 6 is also not particularly limited, and may be a thickness that ensures sufficient strength. The substrate 6 has a plurality of openings 61 in the X-Y plane, and a vibrator 4 is formed above each opening 61 in the Z-axis direction. In other words, the vibration part 41 of the vibrator 4 is disposed opposite the opening 61 of the substrate 6. The shape and dimensions of the opening 61 in a plan view are determined according to the shape and dimensions of the vibration part 41 in the vibrator 4. In the second embodiment, the opening 61 has a substantially rectangular shape in a plan view.

The vibrator 4 is a laminated structure in which functional films are laminated, and the vibrator 4 in the second embodiment includes at least the lower electrode layer 12, the piezoelectric layer 14, and the magnetostrictive layer 16 described above. The lower electrode layer 12 is located above the Z axis of the substrate 6, and the piezoelectric layer 14 is laminated on the lower electrode layer 12, and the magnetostrictive layer 16 is laminated on the piezoelectric layer 14. The configuration of each functional film will be described in detail later.

As shown in FIG. 5, the vibrator 4 is located above the substrate 6 in the Z-axis direction, bridging the upper opening surface of the opening 61 in the X-axis direction. One end of the vibrator 4 in the X-axis direction faces and is connected to the surface of the substrate 6, forming the fixed part 42a. The other end of the vibrator 4 in the X-axis direction also faces and is connected to the surface of the substrate 6, forming the fixed part 42b.

In the fixed portion 42a, the extraction electrode 18a is electrically connected to the lower electrode layer 12, and an external circuit (not shown) can be connected via this extraction electrode 18a. On the other hand, in the fixed portion 42b, there is an extraction electrode 18b electrically connected to the magnetostrictive layer 16, and an external circuit (not shown) can be connected via this extraction electrode 18b. In addition, in the fixed portion 42b, an insulating layer 20 is interposed between the extraction electrode 18b and the lower electrode layer 12, and this insulating layer 20 insulates the extraction electrode 18b and the lower electrode layer 12 from each other so as not to short circuit. In the following paragraphs, the fixed portion 42a and the fixed portion 42b may be collectively referred to as "fixed portion 42".

The vibration part 41 of the vibrator 4 has a generally rectangular shape in plan view that is smaller than the upper opening surface of the opening 61, and has edges parallel to the X-axis and edges parallel to the Y-axis. In the second embodiment, the X-axis direction is the longitudinal direction of the vibration part 41, and the Y-axis direction is the lateral direction of the vibration part 41. As described above, the vibration part 41 is located above the opening 61, and in the cross section shown in FIG. 6, the vibration part 41 appears to be floating above the Z-axis of the opening 61. As shown in FIG. 6, it is preferable that the upper and lower surfaces of the vibration part 41 parallel to the X-Y plane are non-constrained surfaces that are not in direct contact with the substrate 6. The upper and lower surfaces of the vibration part 41 are surfaces that face the opening 61. The cross section shown in FIG. 6 is a cross section along the VI-VI line shown in FIG. 4, and is an X-Z cross section that does not include the support part 43.

The vibrating part 41 of the power generator 4 is integrally connected to each of the fixed parts 42a, 42b via a pair of support parts 43. In other words, the vibrating part 41 is connected to the substrate 6 via the support parts 43. In the second embodiment, the direction in which the vibrating part 41 and the fixed part 42 are connected by the support parts 43 is referred to as the connection direction (the X-axis direction in Figures 1 to 3).

As shown in FIG. 4 and FIG. 6, the outer peripheral edge of the vibration part 41 and the inner peripheral edge of the opening 61 are not in contact with each other, and a gap 46 exists between the outer peripheral edge of the vibration part 41 and the inner peripheral edge of the opening 61. Here, the "outer peripheral edge of the vibration part 41" in the above means the outer peripheral edge of the lower electrode layer 12 in the vibration part 41, and more specifically, the outer peripheral edge of the lower electrode layer 12 excluding the connection part with the support part 43 in the vibration part 41. In the second embodiment, the average width Wg of the gap 46 is preferably 1 μm to 500 μm. In the second embodiment, the gap 46 is a space in which the functional films 12 to 16 and the substrate 6 are not present. In addition, the width Wg of the gap 46 means the distance from the outer peripheral edge of the lower electrode layer 12 to the inner peripheral edge of the opening 61 in a plan view.

In addition, in the vibration section 41, the width Wvy in the direction perpendicular to the connection direction (width in the Y-axis direction in Figures 4 to 6) is preferably 1/100 times or less, and more preferably 1/200 times or less, of the wavelength of an electromagnetic wave with the same frequency as the natural frequency F. The lower limit of the width Wvy in the direction perpendicular to the connection direction is not particularly limited, but is preferably 1/200,000 times or more of the wavelength of an electromagnetic wave with the same frequency as the natural frequency F. In the above, the "wavelength of an electromagnetic wave" means the wavelength of an electromagnetic wave in a medium (e.g., air) that serves as a transmission path. For example, in the power generation element 1 of the second embodiment, if the width Wvy is widened without changing the configuration other than the width Wvy, the natural frequency F of the vibrator 4 tends to be lower. Conversely, if the width Wvy is narrowed, the natural frequency F of the vibrator 4 tends to be higher.

On the other hand, the width Wvx in the connection direction of the vibrating part 41 is not particularly limited and can be narrower than the above-mentioned width Wvx, but is preferably wider than the width Wvy.

The average thickness Tv of the vibration part 41 depends on the thickness of each functional film and is not particularly limited, but is preferably, for example, 0.5 μm to 30 μm.

As described above, the vibration part 41 has a plate-like shape along a plane including the X-axis and the Y-axis, and it is preferable that this plate-like vibration part 41 is as smooth as possible. For example, it is preferable that the flatness of the vibration part 41 is smaller than the width Wvy. It is also preferable that the surface roughness of the upper and lower surfaces of the vibration part 41 parallel to the X-Y plane is 1 μm or less in arithmetic mean roughness (Ra) or root mean square roughness (Rq: old RMS). Alternatively, it is preferable that the surface roughness of the upper surface (Ra or Rq) and the surface roughness of the lower surface (Ra or Rq) of the vibration part 41 are 1/10 times or less compared to the wavelength of the elastic wave vibration of the vibration part 41. By smoothing the vibration part 41 in this way, the amplitude of the bulk elastic wave vibration of the vibrator 4 can be increased.

The flatness may be measured by contact or non-contact. For example, the flatness can be measured by a CNC image measuring device or a laser microscope. The surface roughness Ra and Rq may also be measured by contact or non-contact, and may be measured in accordance with JIS-B0601.

The support part 43 of the power generating unit 4 connects the end of the vibration part 41 in the X-axis direction to the fixed part 42 along the X-axis direction, and in the second embodiment, two support parts 43 are formed according to the number of fixed parts 42. It is preferable that the support part 43 is formed in a manner that has a lower rigidity than the vibration part 41 so as not to interfere with the elastic wave vibration of the vibration part 41.

For example, in the support section 43, the width Wsy in the direction perpendicular to the connection direction (Y-axis direction) is preferably narrower than the width Wvy of the vibration section 41. More specifically, the ratio of the width Wsy of the support section 43 to the width Wvy of the vibration section 41 (Wsy/Wvy) is preferably 10% to 90%. Alternatively, the average thickness Ts of the support section 43 in the Z-axis direction is preferably thinner than the average thickness Tv of the vibration section 41 in the Z-axis direction. More specifically, the ratio of the average thickness Ts of the support section 43 to the average thickness Tv of the vibration section 41 (Ts/Tv) is preferably 50% to 95%.

Furthermore, in the support portion 43, the product of the average thickness Ts and the width Wsy (Ts x Wsy) is preferably 90% or less, and more preferably 75% or less, of the product of the average thickness Tv and the width Wvy in the vibration portion 41. By controlling the average thickness Ts and width Wsy in the support portion 43 within the range of the above conditions, the amplitude of the bulk acoustic wave vibration of the vibrator 4 can be increased, and the energy conversion efficiency of the antenna element 10 can be further improved.

Furthermore, it is preferable that the length Wsx of the support portion 43 in the connection direction (X-axis) is within a range of approximately 1/10 to 1/2 times the wavelength of the elastic wave vibration of the vibration portion 41. By setting the length Wsx of the support portion 43 within the above range, the vibration energy of the elastic wave vibration can be efficiently confined in the vibration portion 41, and the output of the antenna element 10 can be increased. Furthermore, in an antenna element 10 having multiple vibrators 4, mutual interference between the multiple vibrators 4 can be suppressed by setting the length Wsx of the support portion 43 within the above range.

Next, we will describe in detail the characteristics of the substrate 6 and each functional film that makes up the vibrator 4.

(Substrate 6)
In the second embodiment, the substrate 6 may be an insulating material capable of supporting at least the vibrator 4, but is preferably a single crystal substrate. Examples of single crystal substrates include Si, MgO, strontium titanate (SrTiO3), and lithium niobate (LiNbO3). In the second embodiment, it is particularly preferable to use a silicon substrate whose surface is a single crystal of the Si(100) plane. The single crystal of the Si(100) plane means that the cubic (100) plane of the silicon substrate is oriented substantially parallel to the thickness direction.

(Piezoelectric layer 14)
The piezoelectric layer 14 is a single-layer thin film extending from one fixed portion 42a to the other fixed portion 42b. As shown in Fig. 4, the planar shape of the piezoelectric layer 14 matches the shapes of the respective portions 41 to 43 of the vibrator 4, and the dimensions in the XY plane are smaller than the planar dimensions of the lower electrode layer 12 described below. The average thickness of the piezoelectric layer 14 is preferably within a range of 0.4 µm to 10 µm, and more preferably 0.4 µm to 2 µm. The variation in thickness of the piezoelectric layer 14 is preferably ±5% or less.

The average thickness of the piezoelectric layer 14 can be determined, for example, by observing the X-Z cross section or Y-Z cross section with a scanning electron microscope (SEM) or a scanning transmission electron microscope (STEM) and performing image analysis on the cross-sectional photograph obtained. At this time, measurements are taken at at least three or more points in the in-plane direction, and the average value is calculated.

The piezoelectric layer 14 is made of a piezoelectric material and exhibits a piezoelectric effect or an inverse piezoelectric effect. Examples of the piezoelectric material that constitutes the piezoelectric layer 14 include quartz crystal, lithium niobate, aluminum nitride (AlN), zinc oxide (ZnO), lead zirconate titanate (PZT: Pb(Zr,Ti) _O3 ), potassium sodium niobate (KNN: (K,Na) _NbO3 ), barium calcium zirconate titanate (BCZT: (Ba,Ca)(Zr,Ti) _O3 ), and the like.

In the second embodiment, among the above piezoelectric materials, it is particularly preferable to use piezoelectric materials having a perovskite structure, such as PZT, KNN, and BCZT. Since piezoelectric materials with a perovskite structure have excellent piezoelectric properties, constructing the piezoelectric layer 14 from these materials further improves the piezoelectric response of the vibrator 4. Note that other elements or compounds may be appropriately added to the above piezoelectric materials that constitute the piezoelectric layer 14 in order to further improve the piezoelectric properties.

In addition, when using a piezoelectric material with a perovskite structure, it is more preferable that the piezoelectric layer 14 is an epitaxially grown film. Here, epitaxial growth refers to the crystals of the film growing while being aligned in the thickness direction (Z-axis direction) and the planar direction (X-axis and Y-axis direction) in a form that matches the crystal lattice of the underlying material during film formation. Therefore, in a more preferable embodiment, the crystals of the piezoelectric layer 14 are aligned in all three directions of the X-axis direction, Y-axis direction, and Z-axis direction (triaxial orientation) in a high-temperature state during film formation. The more the crystal axes in the piezoelectric layer 14 are aligned to improve the orientation, the higher the Q value of the vibration part 41 tends to be. In addition, by making the piezoelectric layer 14 an epitaxially grown film, the vibrator 4 is more likely to vibrate elastically with in-plane stretching vibration.

Whether or not epitaxial growth has occurred so as to orient along three axes can be confirmed by performing reflection high energy electron diffraction (RHEED) evaluation during the thin film formation process. If there is a disturbance in the crystal orientation on the film surface during film formation, the RHEED image will show an extended ring-shaped pattern. On the other hand, if epitaxial growth has occurred as described above, the RHEED image will show a sharp spot-like or streak-like pattern. The above-mentioned RHEED image is observed only at high temperatures during film formation.

Furthermore, when epitaxially grown, the piezoelectric layer 14 has a crystal structure close to single crystal (not completely single crystal) at room temperature after film formation with almost no grain boundaries formed. More specifically, the crystal structure of the piezoelectric layer 14 after film formation is preferably three-axially oriented and has multiple crystal phases, and preferably has a domain structure including at least three types of domains. The domain structure of the piezoelectric layer 14 further improves the piezoelectric properties and increases the piezoelectric responsiveness to vibration.

When the piezoelectric layer 14 has a domain structure, the specific configuration of the domain structure varies depending on the piezoelectric material used. For example, when the piezoelectric layer 14 is an epitaxially grown film of PZT, it can have at least two crystal phases, tetragonal and rhombohedral. In this case, the tetragonal crystal has a domain in which the c-axis (the longitudinal axis of the rectangular parallelepiped (crystal lattice)) faces the film thickness direction, and a domain in which the c-axis faces the in-plane direction. The rhombohedral crystal phase is oriented so that the (100) plane is parallel to the film thickness direction. In other words, when the piezoelectric layer 14 is an epitaxially grown film of PZT, it is preferable that it contains a total of three domains, two tetragonal domains and a rhombohedral domain.

On the other hand, when the piezoelectric layer 14 is an epitaxially grown film of KNN, it is preferable to have two types of orthorhombic domains and one type of monoclinic domain (three types of domains in total). In the above case, the two types of orthorhombic domains may be a domain (a domain) in which the (001) plane of the orthorhombic crystal is oriented approximately parallel to the film thickness direction, and a domain (c domain) in which the (010) plane of the orthorhombic crystal is oriented approximately parallel to the film thickness direction. In addition, in the monoclinic domain, it is preferable that the (100) plane or the (010) plane is approximately parallel to the film thickness direction.

In addition, when the piezoelectric layer 14 is an epitaxially grown film of BCZT, it preferably has two tetragonal domains and two orthorhombic domains (four domains in total).

The multiple domains described above are adjacent to each other across a common domain boundary, so the orientation of the crystal axis of each domain may deviate from the film thickness direction or in-plane direction by a few degrees (specifically, up to about ±3 degrees). Furthermore, the multiple domains described above are equivalent domains oriented in the same direction in the same crystal system, at least in the high temperature state during film formation, and are formed by transitioning to a more stable crystal phase or domain during the process of cooling to room temperature or the operating temperature after film formation. The presence of multiple domains mixed together can be confirmed by analyzing the piezoelectric layer 14 using electron diffraction with a STEM or transmission electron microscope (TEM), X-ray diffraction (XRD), or the like.

(Lower electrode layer 12)
The lower electrode layer 12 is a single-layer thin film extending from one fixed portion 42a to the other fixed portion 42b, similar to the piezoelectric layer 14. The lower electrode layer 12 is an electrode for recovering and extracting the charge generated in the piezoelectric layer 14, and one end of the lower electrode layer 12 in the X-axis direction is electrically connected to the extraction electrode 18a. The average thickness of the lower electrode layer 12 is preferably 3 nm to 200 nm.

The lower electrode layer 12 is made of a conductive material such as a metal or an oxide conductor. In particular, when the piezoelectric layer 14 is an epitaxially grown film, it is preferable that the lower electrode layer 12 is also an epitaxially grown film. In this case, the lower electrode layer 12 is preferably a metal thin film having a face-centered cubic structure such as platinum (Pt), iridium (Ir), or gold (Au), or an oxide conductor thin film such as strontium ruthenate (SrRuO3: hereinafter abbreviated as SRO) or lithium nickel oxide (LiNiO3). Such metal thin films and oxide conductor thin films can be epitaxially grown on a single crystal substrate. When an epitaxially grown film is used, it is preferable that the (001) plane of the lower electrode layer 12 is oriented in the film thickness direction (Z-axis direction). Additionally, in the in-plane direction (X-axis or Y-axis direction), it is preferable that the (100) plane of the piezoelectric layer 14 and the (100) plane of the lower electrode layer 12 are approximately parallel to each other.

When the lower electrode layer 12 is also an epitaxially grown film, the lower electrode layer 12 may be formed by laminating the above-mentioned metal thin film and the above-mentioned oxide conductor thin film. In that case, it is preferable to laminate a metal thin film on the lower side (i.e., the substrate 6 side) of the lower electrode layer 12, and laminate an oxide conductor thin film on the metal thin film.

(Magnetostrictive layer 16)
As shown in FIG. 4, in the second embodiment, the magnetostrictive layer 16 is a single-layer thin film laminated on the vibrating portion 41, and the magnetostrictive layer 16 is not formed on the fixed portion 42 and the support portion 43. In this way, the magnetostrictive layer 16 only needs to be laminated on the vibrating portion 41, and does not necessarily need to be laminated on the fixed portion 42 or the support portion 43. However, the magnetostrictive layer 16 may be present on the support portion 43 or a part of the fixed portion 42. In addition, in FIG. 4, the magnetostrictive layer 16 has a substantially rectangular shape in plan view. It is preferable that the planar dimensions of the magnetostrictive layer 16 are smaller than the planar dimensions of the piezoelectric layer 14 on the vibrating portion 41. In other words, it is preferable that the outer periphery of the magnetostrictive layer 16 is located inside the outer periphery of the piezoelectric layer 14 in the XY plane. By controlling the planar dimensions of the magnetostrictive layer 16 as described above, the durability of the vibrator 4 can be improved.

The average thickness of the magnetostrictive layer 16 is preferably in the range of 0.1 μm to 5 μm, and more preferably 0.1 μm to 1 μm. The ratio of the average thickness of the magnetostrictive layer 16 to the average thickness of the piezoelectric layer 14 is preferably in the range of 1/10 to 10, and more preferably 1/10 or more and less than 1. The variation in thickness of the magnetostrictive layer 16 is preferably ±5% or less, as in the case of the piezoelectric layer 14. The average thickness of the magnetostrictive layer 16 can be measured in the same manner as the piezoelectric layer 14.

The magnetostrictive layer 16 is made of a ferromagnetic material having magnetostrictive properties. The ferromagnetic material may be a pure metal such as iron (Fe), cobalt (Co), or nickel (Ni), or an alloy containing at least one of the above metal elements (for example, an Fe-Co, Fe-Ni, Fe-Si, Fe-Dy-Tb, Fe-Ga, or Fe-Si-Al alloy), or an oxide magnetic material containing an oxide of the above metal elements. The magnetostrictive layer 16 may be a single film containing the above ferromagnetic material, or a multilayer film consisting of multiple layers, or a laminated film of a ferromagnetic material and an antiferromagnetic material.

Among the above ferromagnetic thin films, the magnetostrictive layer 16 is preferably a soft magnetic high magnetostrictive film. In the second embodiment, the soft magnetic high magnetostrictive film means a film made of a soft magnetic material having a low coercive force H _C and a low threshold magnetic field H _TH (preferably H _C is less than 2500 A/m and H _TH is less than 500 A/m) and having a saturation magnetostriction λ _MAX of 5 ppm or more. Specifically, the magnetostrictive layer 16 of the soft magnetic high magnetostrictive film is exemplified by an alloy film mainly composed of Fe-Si-B alloy, Fe-Cr-Si-B alloy, Fe-Ni-Mo-B alloy, Fe-Co-B alloy, Fe-Ni-B alloy, Fe-Al-Si-B alloy, or Fe-Co-Si-B alloy. Many ferromagnetic materials exhibit the magnetostrictive effect, but when the magnetostrictive layer 16 is made of the soft magnetic, highly magnetostrictive film described above, it is possible to generate elastic wave vibrations with a larger amplitude.

The crystal structure of the magnetostrictive layer 16 may be amorphous or polycrystalline, but if the magnetostrictive layer 16 is a soft magnetic highly magnetostrictive film, it is preferable that the layer has a mixture of amorphous and crystalline phases. By having the ferromagnetic thin film 16 have a mixture of amorphous and crystalline phases, the responsiveness to input signals can be improved and the magnetostrictive change rate (dλ/dH) can be increased.

In addition, alloys containing Fe are usually crystallized in a body-centered cubic structure. In the second embodiment, when the magnetostrictive layer 16 has an amorphous phase and a crystalline phase, it is preferable that most of the crystalline phase contained in the magnetostrictive layer 16 has a face-centered cubic structure. By having the magnetostrictive layer 16 have the above-mentioned crystalline structure, the energy conversion efficiency of the antenna element 10 can be further improved.

The crystal structure of the magnetostrictive layer 16 can be confirmed by analysis using TEM electron beam diffraction or XRD, as with the piezoelectric layer 14. For example, if the magnetostrictive layer 16 is composed only of an amorphous phase, when θ-2θ measurement is performed using XRD with Cu-Kα radiation, only a broad, wide halo pattern is detected. On the other hand, if the magnetostrictive layer 16 is composed only of a crystalline phase, only an extremely sharp reflection peak with a narrow half-width is detected. Also, if the magnetostrictive layer 16 has a mixture of amorphous and crystalline phases, a reflection peak is detected that has both a broad raised (halo) portion indicating the presence of an amorphous phase and a sharp peak portion indicating the presence of a crystalline phase.

The ratio of the amorphous phase to the crystalline phase can be confirmed by performing profile fitting on the reflection peak obtained by electron beam diffraction or XRD and calculating the crystallinity. Specifically, fitting is performed on the crystalline phase portion (peak portion) and the amorphous phase portion (halo portion), and the integrated intensity (area) of each portion is measured. The crystallinity (%) is expressed as the ratio (Ic/(Ic+Ia)×100) of the integrated intensity (Ic) of the crystalline phase portion to the sum of the integrated intensity (Ic) of the crystalline phase portion and the integrated intensity (Ia) of the amorphous phase portion (i.e., the total peak area). In the second embodiment, when the magnetostrictive layer 16 has a mixture of the amorphous phase and the crystalline phase, the crystallinity is preferably 1% to 50%, and more preferably 5% to 20%.

As described above, the magnetostrictive layer 16 contributes to the generation of the energy wave E and the generation of elastic wave vibration. In the case of the vibrator 4 shown in Figures 4 to 6, the magnetostrictive layer 16 also functions as an electrode for recovering and extracting the electric charge generated in the piezoelectric layer 14.

(Extraction electrode 18)
The extraction electrode 18 is not particularly limited in material or size as long as it is conductive. For example, the extraction electrode 18 may contain a conductive metal such as Pt, Ag, Cu, Au, or Al, and may contain a glass component in addition to the conductive metal. Although the extraction electrode 18 is a thin-film electrode in Fig. 4 and Fig. 5, it may be a via-hole electrode.

(Insulating layer 20)
There are no particular limitations on the material or thickness of the insulating layer 20 as long as it has electrical insulation properties. For example, the insulating layer 20 can be made of SiO ₂ , Al ₂ O ₃ , polyimide, or the like.

(Other functional membranes)
Although not shown in FIGS. 4 to 6, the vibrator 4 may include other functional films in addition to the lower electrode layer 12, the piezoelectric layer 14, and the magnetostrictive layer 16 described above.

For example, a buffer layer for controlling the crystallinity of the lower electrode layer 12 and the crystallinity of the piezoelectric layer 14 may be formed in the lowest layer in the Z-axis direction of the vibrator 4 (i.e., below the lower electrode layer 12). In particular, when the piezoelectric layer 14 is an epitaxially grown film, it is preferable to form a buffer layer. The buffer layer is preferably mainly composed of zirconium oxide ( _ZrO2 ) or zirconium oxide stabilized with rare earth elements (including Sc and Y) (stabilized zirconia).

This buffer layer is also preferably a film that has been epitaxially grown with crystals aligned in the thickness direction (Z-axis direction) and in-plane directions (X-axis and Y-axis directions) in a manner that matches the crystal lattice of the deposition substrate. As with the lower electrode layer 12, the buffer layer is preferably oriented with its (001) plane in the thickness direction, and more preferably, the (100) plane of the piezoelectric layer 14, the (100) plane of the lower electrode layer 12, and the (100) plane of the buffer layer are approximately parallel to each other in the in-plane direction (X-axis or Y-axis direction). Specifically, when the buffer layer is _ZrO2 , the lower electrode layer 12 is Pt, and the piezoelectric layer 14 is PZT, the preferred orientation relationship of each layer is _ZrO2 (001)//Pt(001)//PZT(001) in the film thickness direction and _ZrO2 (100)//Pt(100)//PZT(100) in the in-plane direction.

The formation of the buffer layer facilitates epitaxial growth of the lower electrode layer 12 and the piezoelectric layer 14, improving the crystallinity of these layers 12, 14. The buffer layer also functions as an etching stopper layer when forming the opening 61 by etching. When forming a buffer layer, it is preferable that the average thickness of the buffer layer is 5 nm to 100 nm.

An upper electrode layer may be formed between the piezoelectric layer 14 and the magnetostrictive layer 16. By forming the upper electrode layer, the charge generated in the piezoelectric layer 14 can be extracted more efficiently. The upper electrode layer can have the same configuration (thickness and material) as the lower electrode layer 12. When the piezoelectric layer 14 is an epitaxially grown film, it is preferable that the lower electrode layer 12 is also an epitaxially grown film, but the upper electrode layer does not necessarily have to be epitaxially grown. On the other hand, when the magnetostrictive layer 16 has a mixture of amorphous and crystalline phases, it is preferable that the crystal structure of the upper electrode layer is a face-centered cubic polycrystalline structure or a crystal structure in which an amorphous phase and a face-centered cubic crystalline phase are mixed.

Furthermore, a protective layer may be formed on the outermost layer of the vibrator 4 except for the lower surface. Examples of the protective layer include a protective layer containing a metal such as Ti, Ta, or Pt, and an insulating protective layer made of SiO ₂ , Al ₂ O ₃ , polyimide, etc., and both a metallic protective layer and an insulating protective layer may be formed. The average thickness of the protective layer is not particularly limited and can be, for example, 5 nm to 50 nm.

The vibrator 4 shown in Figures 4 to 6 has the internal structure (the configuration of each functional film) as described above, and has the morphological characteristics (such as the shape and dimensions of each part of the vibrator 4) as described above, so that the vibrating part 41 becomes a bulk acoustic wave vibrator with in-plane stretching vibration. In particular, when the internal structure and morphological characteristics satisfy the preferable conditions as described above, the vibration mode of the vibrating part 41 tends to be an expansion vibration.

The antenna element 10 of the second embodiment can be manufactured using microfabrication techniques such as those used in semiconductor processes. For example, first, each functional film is formed on the substrate 6 by a method such as deposition, sputtering, sol-gel, CVD, or PLD (preferably sputtering). Then, each functional film is patterned using various microfabrication techniques such as photoetching, laser dry etching, or lift-off to form multiple vibrators 4 on the substrate 6. Finally, parts of the substrate 6 are removed by various etching methods such as dry etching such as Deep-RIE or anisotropic wet etching to form multiple openings 61 in the substrate 6. The above steps result in the antenna element 10 shown in Figures 3 to 6.

(Modification of the transducer 4)
The form of the vibrator 4 is not limited to the forms shown in Figures 4 to 6, but may be, for example, forms as shown in Figures 9 and 10. Modified examples of the vibrator 4 will now be described.

In FIG. 9, an opening 61b that is circular in plan view is formed in the substrate 6. Furthermore, the vibration part 41b of the vibrator 4 has a circular cross-sectional shape. Note that in FIG. 9, the vibration part 41b is also located above the opening 61b, and the upper and lower surfaces of the vibration part 41b are non-constrained surfaces. Furthermore, a gap 46 exists between the outer periphery of the vibration part 41b and the inner periphery of the opening 61b.

In the case of a disk-shaped vibration section 41b as shown in FIG. 9, by optimizing the crystallinity of each functional film (particularly the piezoelectric layer 14 and magnetostrictive layer 16), it is possible to generate bulk elastic wave vibration in thickness-extension vibration (in-plane expansion and contraction). Bulk elastic wave vibrators with thickness-extension vibration tend to have a higher natural frequency F than bulk elastic wave vibrators with expansion vibration.

On the other hand, in FIG. 10, the vibration part 41c of the vibrator 4 has a cantilever-type structure. Specifically, the vibrator 4 in FIG. 10 is fixed to the substrate 6 at only one end in the X-axis direction, and the other end in the X-axis direction of the vibrator 4 (i.e., the tip of the vibration part 41c) is a free end. Also, in the vibrator 4 in FIG. 10, the width in the Y-axis direction of the support part 43c is approximately the same as the width in the Y-axis direction of the vibration part 41c.

In the case of such a cantilever-type vibrating part 41c, it is easy to generate bulk acoustic wave vibration with bending vibration (out-of-plane vibration). When the vibrating part 41c of the vibrator 4 is a bending vibration, it is preferable to fill the inside of the power transmitting part 310 or the power receiving part 110 on which the antenna element 10 is mounted with a low-viscosity gas. Alternatively, it is preferable to increase the degree of vacuum of the power transmitting part 310 or the power receiving part 110 (reduce the internal pressure of the container). In this way, by controlling the atmosphere around the element, it is possible to reduce the air resistance on the vibrating part 41c and improve the energy conversion efficiency.

The vibration mode of the vibrator 4, which is an elastic wave vibrator, is not determined solely by the shape of the vibrating part, but is also influenced by other factors such as the thickness of the vibrator 4, the shape of the support part, and the configuration of each functional film. Therefore, even with the shape of the vibrating part shown in Figure 10, it may be possible to generate bulk elastic wave vibration of in-plane stretching vibration. Similarly, even with the shapes of the vibrating parts shown in Figures 4 to 6 and the shape of the vibrating part shown in Figure 9, it may be possible for the vibration mode to be an out-of-plane vibration such as bending vibration.

Although the embodiment of the present invention has been described above, the present invention is not limited to the above-mentioned embodiment, and various modifications can be made within the scope of the present invention. For example, in the above-mentioned embodiment, the piezoelectric layer 14 and the magnetostrictive layer 16 are laminated in the vibration part 41, but the functional film may be made of a material having both piezoelectric properties and magnetostrictive properties. Examples of such materials having both piezoelectric properties and magnetostrictive properties include BiFeO ₃ and (Bi, La)FeO ₃ in which part of Bi is replaced with other elements such as La.

In the above embodiment (particularly the second embodiment), a single crystal silicon substrate is exemplified as the substrate 6, but an SOI base material 60 (Silicon on Insulator) as shown in FIG. 11(a) may be used as the substrate 6. The SOI base material 60 is composed of a single crystal Si layer 60α oriented so that the surface is a Si (100) surface, an insulating layer 60β made of SiO ₂ , and a substrate 6d made of Si, and the single crystal Si layer 60α is laminated on the surface of the substrate 6d via the insulating layer 60β. The average thickness of the Si layer 60α and the average thickness of the insulating layer 60β are not particularly limited, but can be, for example, about 1 μm to 10 μm. The average thickness of the substrate 6d in the SOI base material 60 is also not particularly limited, but can be, for example, about 100 μm to 700 μm.

When this SOI substrate 60 is used, the fixing portion 42 of the vibrator 4 is connected to the top of the substrate 6d via the Si layer 60α and the insulating layer 60β. When the antenna element 10 is manufactured using the SOI substrate 60, a vibrator 4 having a structure as shown in FIG. 11(b) may be obtained. FIG. 11(b) is a cross-sectional view showing a portion similar to FIG. 6. As described in the second embodiment, the opening 61 is formed by etching the substrate to remove a portion of the substrate. When the SOI substrate 60 is used, the Si layer 60α and the insulating layer 60β may remain on the lower surface of the vibrating portion 41 after etching. In this case, the Si layer 60α and the insulating layer 60β may remain on the entire lower surface of the vibrating portion 41, or may remain partially on a portion of the lower surface.

However, as shown in FIG. 11(b), it is preferable that the Si layer 60α and the insulating layer 60β are also removed in the gap 46, and the lower and upper surfaces of the vibrating part 41 facing the opening 61 are unconstrained surfaces that are not constrained by the substrate 6d. In other words, even when an SOI substrate 60 is used, it is preferable that the outer peripheral edge of the vibrating part 41 and the inner peripheral edge of the opening 61 are not in contact with each other in a planar view from the Z-axis direction. Note that even if the Si layer 60α and the insulating layer 60β remain on the lower surface of the vibrating part 41, the outer peripheral edge of the vibrating part 41 is determined based on the outer peripheral edge of the lower electrode layer 12 in a planar view.

When an SOI substrate 60 is used, even if the Si layer 60α and the insulating layer 60β remain, the thickness of these remaining layers is about a few μm, and they do not impede the elastic wave vibration of the vibrating part 41. Therefore, even in the antenna element shown in FIG. 11(b), the vibrating part 41 functions as a bulk elastic wave vibrator that vibrates elastically by in-plane expansion and contraction.

The present invention will be described in more detail below using examples. However, the present invention is not limited to the following examples.

Example 1
In Example 1, an antenna element having a plurality of vibrators having the shape shown in FIG. 4 was produced. The plurality of vibrators included in the antenna element all had the same shape, and in each vibrator, the width Wvx in the connection direction of the vibrating part was set to 500 μm, and the width Wvy in the direction perpendicular to the connection direction of the vibrating part was set to 120 μm. In addition, a piezoelectric layer made of PZT formed by epitaxial growth and a magnetostrictive layer made of an Fe-Co-Si-B alloy having a crystalline phase and an amorphous phase were laminated on the vibrating part of each vibrator. The average thickness of the laminated piezoelectric layer was 1 μm, and the average thickness of the magnetostrictive layer was 0.5 μm.

A total of 45 vibrators 4 were formed in one antenna element. As shown in Figure 3, these vibrators were arranged along two axial directions on the same plane and wired in parallel. The dimensions of the resulting antenna element were 1 cm x 1 cm.

The vibration characteristics of each vibrator included in the antenna element were measured using an impedance analyzer. As a result, it was confirmed that each vibrator has a natural frequency F of 14 MHz and is a bulk acoustic wave vibrator that vibrates elastically with spreading vibration.

Next, a power transmitting device and a power receiving device were fabricated using the above antenna element.

The power transmission device 300 was obtained by connecting and integrating a power transmission unit including multiple antenna elements and a power source via a rectifier circuit. In Example 1, the power transmission unit was configured by arranging a total of 100 antenna elements along two axial directions on the same plane and wiring them in parallel. In other words, the size of the board with multiple antenna elements arranged was 10 cm x 10 cm. In Example 1, AA-type nickel-metal hydride batteries (1.2 V, 1900 mAh) were used as the power source, and a total of four of these nickel-metal hydride batteries were installed.

On the other hand, the power receiving device was obtained by integrating a PMIC including a rectifier circuit and a capacitor with a power receiving section that is composed of the same antenna element as the power transmitting device. In Example 1, the power receiving section was equipped with one antenna element.

(Evaluation of Example 1)
Next, it was confirmed whether or not contactless power supply to an electronic device is possible using the above-mentioned power transmitting device and power receiving device. In this evaluation, the power receiving device was mounted on an external ear canal type earphone and connected to each component (such as an audio IC, a storage device, and a piezoelectric speaker) in the earphone. Meanwhile, the power transmitting device was installed at a position about 0.6 m away from the earphone, which is the object to be powered. At this time, the orientation of the power transmitting device was adjusted so that the plane of each antenna element included in the power transmitting unit intersects with the direction of the earphone, which is the object to be powered. In other words, the Z-axis direction (thickness direction of the antenna element 10) in FIG. 3 was made to coincide with the orientation connecting the power transmitting device and the earphone.

After arranging each device as described above, we turned on the power supply in the power transmission device and confirmed whether the earphones would work. As a result, we were able to confirm that an AC magnetic field with a frequency of 14 MHz was generated from the power transmission device. We were also able to confirm that the earphones received this AC magnetic field, generating power in the power receiving section, and that this power was able to work the earphones.

Example 2
In Example 2, an antenna element having a plurality of disc-shaped vibrators shown in FIG. 9 was produced. In Example 2, as in Example 1, a piezoelectric layer made of PZT formed by epitaxial growth and a magnetostrictive layer made of an Fe-Co-Si-B alloy having a crystalline phase and an amorphous phase were laminated in the vibrating part of the vibrator. However, in Example 2, the average thickness of each layer was changed from Example 1, and the average thickness of the piezoelectric layer was set to 0.4 μm and the average thickness of the magnetostrictive layer was set to 0.2 μm. In addition, the diameter of the vibrating part was set to 500 μm. In Example 2, the configuration other than the above was the same as in Example 1, and an antenna element according to Example 2 was obtained.

The vibration characteristics of each transducer in the antenna element of Example 2 were confirmed in the same manner as in Example 1. As a result, it was confirmed that each transducer in Example 2 has a natural frequency F of 2.5 GHz and is a bulk acoustic wave transducer that vibrates in a thickness-extensional manner.

Next, a power transmitting device and a power receiving device were fabricated using the antenna element of Example 2. In Example 2, when fabricating the power transmitting device, a beamforming type directivity control means 330 shown in FIG. 2 was installed in the power transmitting device. Aside from the installation of the directivity control means 330, the power transmitting device of Example 2 was obtained in the same manner as Example 1. The power receiving device was also configured in the same manner as Example 1, and was obtained by connecting and integrating a PMIC and a capacitor to a power receiving section including the antenna element of Example 2.

(Evaluation of Example 2)
In Example 2, it was confirmed whether or not contactless power supply to earphones is possible using the power transmitting device and power receiving device of Example 2 in the same manner as in Example 1. In Example 2, the orientation of the power transmitting device was not adjusted in the above evaluation, and the directivity of the AC magnetic field irradiated from the power transmitting unit was controlled by beamforming based on the directivity control means 330.

As a result of the evaluation, it was confirmed that an AC magnetic field with a frequency of 2.5 GHz was generated from the power transmission device of Example 2. It was also confirmed that the phase of the generated AC magnetic field was strengthened in the direction connecting the power transmission device and the earphones, and that the phase was weakened in other directions other than the above. It was also confirmed that in Example 2, power was generated in the power receiving unit in response to the AC magnetic field supplied from the power transmission unit, and that the earphones were driven by this power.

Example 3
In Example 3, similarly to Example 2, an antenna element having a plurality of disc-shaped vibrators as shown in FIG. 9 was fabricated. However, in Example 3, the material of the piezoelectric layer was changed, and a piezoelectric layer made of aluminum nitride (AlN) was laminated on the vibrating part. This AlN piezoelectric layer was also formed by epitaxial growth. At this time, the orientation relationship in the film thickness direction of each layer was ZrO ₂ (111) // Pt (111) // AlN (001). In Example 3, the material of the magnetostrictive layer was the same as in Example 2, but the average thickness of the magnetostrictive layer was changed to 0.5 μm. In Example 3, the configuration other than the above was the same as in Example 2, and an antenna element according to Example 3 was obtained.

The vibration characteristics of each transducer in the antenna element of Example 3 were confirmed in the same manner as in Examples 1 and 2. As a result, it was confirmed that each transducer in Example 3 has a natural frequency F of 2.5 GHz and is a bulk acoustic wave transducer that vibrates in a thickness-extensional manner.

(Evaluation of Example 3)
In Example 3, similarly to Example 2, a power transmitting device and a power receiving device were fabricated, and then it was confirmed whether or not wireless power supply to earphones was possible using the power transmitting device and the power receiving device of Example 3.

As a result, it was confirmed that the power transmission device of Example 3 generates an AC magnetic field with a frequency of 2.5 GHz and high directivity. It was also confirmed that, in Example 3, the power receiving unit receives the AC magnetic field supplied from the power transmission unit, generates electric power, and the earphones are driven by this electric power.

1000 ... power supply system 200 ... electronic device 210 ... component 100 ... power receiving device 110 ... power receiving unit 120 ... power management IC (PMIC)
REFERENCE SIGNS LIST 130: Capacitor 300: Power transmitting device 310: Power transmitting section 320: Power source 330: Directivity control means 331: Phase shifter 332: Control circuit 333: Amplitude control means 10: Antenna element 10a: Power transmitting antenna element 10b: Power receiving antenna element 4: Transducer 4a: Power transmitting side transducer 4b: Power receiving side transducer 41, 41b, 41c: Vibration section 12: Lower electrode layer 14: Piezoelectric layer 16: Magnetostrictive layer 18, 18a, 18b: Extraction electrode 20: Insulating layer 42, 42a, 42b: Fixed section 43: Support section 46: Gap 6: Substrate 61: Opening 8, 9: Electrode 80, 90: Wiring

Claims (21)

a power transmission device having a power transmission unit that transmits energy waves to the outside;
a power receiving device having a power receiving unit that receives the energy wave supplied from the power transmitting unit in a non-contact manner and converts the energy wave into electrical energy,
The power transmitting unit has at least one power transmitting side vibrator that vibrates elastically at a first natural frequency,
the power receiving unit has at least one power receiving side vibrator that is induced by the energy wave generated by the elastic wave vibration of the power transmitting side vibrator to elastically vibrate at a second natural frequency,
the power transmitting vibrator has a piezoelectric layer and a magnetostrictive layer,
The power-receiving-side vibrator includes a piezoelectric layer and a magnetostrictive layer. The piezoelectric layer of the power transmitting side vibrator and the piezoelectric layer of the power receiving side vibrator are made of substantially the same material,
2. The power supply system according to claim 1 , wherein the magnetostrictive layer of the power transmitting vibrator and the magnetostrictive layer of the power receiving vibrator are made of substantially the same material. a power transmission device having a power transmission unit that transmits energy waves to the outside;
a power receiving device having a power receiving unit that receives the energy wave supplied from the power transmitting unit in a non-contact manner and converts the energy wave into electrical energy,
The power transmitting unit has at least one power transmitting side vibrator that vibrates elastically at a first natural frequency,
the power receiving unit has at least one power receiving side vibrator that is induced by the energy wave generated by the elastic wave vibration of the power transmitting side vibrator to elastically vibrate at a second natural frequency,
The power supply system, wherein the elastic wave vibration of the power transmitting side vibrator and the elastic wave vibration of the power receiving side vibrator are both bulk elastic wave vibrations. a power transmission device having a power transmission unit that transmits energy waves to the outside;
a power receiving device having a power receiving unit that receives the energy wave supplied from the power transmitting unit in a non-contact manner and converts the energy wave into electrical energy,
The power transmitting unit has at least one power transmitting side vibrator that vibrates elastically at a first natural frequency,
the power receiving unit has at least one power receiving side vibrator that is induced by the energy wave generated by the elastic wave vibration of the power transmitting side vibrator to elastically vibrate at a second natural frequency,
A power supply system in which the vibration mode of the elastic wave vibration in the power transmitting side vibrator and the vibration mode of the elastic wave vibration in the power receiving side vibrator are both in-plane stretching vibrations. The power supply system according to claim 1 , wherein the second natural frequency of the power receiving side vibrator is substantially the same as the first natural frequency of the power transmitting side vibrator. The power supply system according to any one of claims 1 to 5 , wherein the power transmission section includes a power transmission antenna element having a plurality of the power transmission side vibrators. The power supply system according to any one of claims 1 to 6 , wherein the power transmitting device has directivity control means for controlling the directivity of the energy wave transmitted from the power transmitting section. The power supply system according to claim 7 , wherein the power transmitting device includes a phase shifter for controlling a phase of the power transmitting section as the directivity control means. The power supply system according to any one of claims 1 to 8 , wherein the power receiving section includes a power receiving antenna element having a plurality of the power receiving side vibrators. 5. The power supply system according to claim 1, wherein the elastic wave vibration of the power transmitting vibrator and the elastic wave vibration of the power receiving vibrator are both bulk elastic wave vibrations . 3. The power supply system according to claim 1, wherein a vibration mode of the elastic wave vibration in the power transmitting side vibrator and a vibration mode of the elastic wave vibration in the power receiving side vibrator are both in-plane stretching vibrations. The power supply system according to any one of claims 1 to 11 , wherein the energy wave transmitted from the power transmission unit is an electromagnetic wave or an alternating magnetic field. The power supply system according to any one of claims 1 to 12 , wherein the power receiving device is present inside an electronic device attached to a mobile object. A power transmitting device that is applied to the power supply system according to any one of claims 1 to 13. A power receiving device that is applied to the power supply system according to any one of claims 1 to 13. A power transmission unit that transmits the energy wave to the outside,
The power transmitting unit has at least one power transmitting side vibrator that vibrates elastically at a natural frequency,
The power transmitting device, wherein the power transmitting side vibrator has a piezoelectric layer and a magnetostrictive layer. A power receiving unit converts the energy wave into electrical energy,
the power receiving unit has at least one power receiving side vibrator that is induced by the energy wave to vibrate elastically at a natural frequency;
The power receiving device, wherein the power receiving side vibrator has a piezoelectric layer and a magnetostrictive layer. A power transmission unit that transmits the energy wave to the outside,
The power transmitting unit has at least one power transmitting side vibrator that vibrates elastically at a natural frequency,
The power transmitting device, wherein the elastic wave vibration of the power transmitting vibrator is a bulk elastic wave vibration. A power receiving unit converts the energy wave into electrical energy,
the power receiving unit has at least one power receiving side vibrator that is induced by the energy wave to vibrate elastically at a natural frequency;
The power receiving device, wherein the elastic wave vibration of the power receiving side vibrator is a bulk elastic wave vibration. A power transmission unit that transmits the energy wave to the outside,
The power transmitting unit has at least one power transmitting side vibrator that vibrates elastically at a natural frequency,
A power transmitting device in which the vibration mode of the elastic wave vibration in the power transmitting side vibrator is an in-plane stretching vibration. A power receiving unit converts the energy wave into electrical energy,
the power receiving unit has at least one power receiving side vibrator that is induced by the energy wave to vibrate elastically at a natural frequency;
A power receiving device in which the vibration mode of the elastic wave vibration in the power receiving side vibrator is an in-plane stretching vibration.

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