JP2019013100A - Wireless power feeding system - Google Patents

Abstract

To wirelessly feed power to a wearable appliance mounted on a human body.SOLUTION: A wireless power feeding system is disclosed that comprises: a power transmitter 20 performing wireless power transmission by electromagnetic wave; a distance sensor 30 measuring distance between the power transmitter 20 and a human body H mounted with a wearable appliance 70 to which power is wirelessly fed by electromagnetic wave; and a controller 40 adjusting intensity of the electromagnetic wave to be transmitted from the power transmitter 20 to such a degree that the electromagnetic wave does not exert unnecessary physiological action on the human body H mounted with the wearable appliance 70 according to the distance between the human body H and the power transmitter 20, the wearable appliance 70 is an appliance to which the power can be fed with the intensity of electromagnetic wave equal to or less than such a degree that the electromagnetic wave does not exert unnecessary physiological action on the human body H, and the power transmitter 20 wirelessly feeds power to the wearable appliance 70 mounted on the human body H without exerting unnecessary physiological action on the human body H.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a wireless power feeding system.

  Patent Document 1 discloses a wireless power distribution system that supplies power to a wireless device such as an actuator that requires high power by an open space wireless power distribution system while complying with radio wave protection guidelines.

  The system described in Patent Document 1 transmits a small-power wave that does not affect the human body to the indoor space if there is a person in the indoor space. Waves are transmitted to the indoor space.

JP 2010-233430 A

  The system described in Patent Document 1 merely supplies power to a wireless device located at a position different from the human body while avoiding an influence on the human body. In other words, the system of Patent Document 1 is based on the idea of transmitting large power while avoiding the human body.

  On the other hand, the present disclosure is based on a novel idea of actively transmitting power toward a human body wearing a wearable device, contrary to the idea of Patent Document 1.

  One aspect of the present disclosure includes a power transmitter that wirelessly transmits power by electromagnetic waves, a distance sensor that measures a distance between a human body wearing a wearable device that is wirelessly powered by electromagnetic waves and the power transmitter, and A controller that adjusts the intensity of the electromagnetic wave transmitted from the power transmitter according to the distance between the human body and the power transmitter to such an extent that the human body wearing the wearable device does not have unnecessary biological effects. The wearable device is a device capable of supplying power with an electromagnetic wave intensity of an extent that does not exert unnecessary biological effects on the human body, and the power transmitter is an unnecessary biological body attached to the human body wearing the wearable device. A wireless power feeding system that wirelessly feeds the wearable device attached to the human body without affecting the human body. .

  Another aspect of the present disclosure includes a power transmitter that radiates electromagnetic waves in a plurality of directions to perform wireless power transmission, and a distance sensor that measures a distance between a human body and the power transmitter in a plurality of directions. The biological action unnecessary for the human body wearing the wearable device wirelessly fed by the electromagnetic wave according to the distances in a plurality of directions measured by the distance sensor, for each direction of the electromagnetic wave transmitted from the power transmitter. The wearable device is a device capable of supplying power with an electromagnetic wave intensity below the level that does not exert unnecessary biological effects on the human body, and the power transmitter is the wearable device. Wireless power feeding to the wearable device attached to the human body without causing unnecessary biological effects on the human body wearing the Iyaresu is a power supply system.

FIG. 1 is a circuit diagram of a wireless power feeding system. FIG. 2 is a graph showing the relationship between the distance from the distance sensor to the distance sensor measurement object and the output value of the distance sensor. FIG. 3A is a diagram illustrating an example of a table. FIG. 3C is a graph showing the relationship between the distance sensor output value and the transmission power setting value. FIG. 3C is a graph showing a relationship between received power and distance. FIG. 4A is a perspective view of a microphone including a wireless power feeding system. FIG. 4B is a cross-sectional view of a microphone including a wireless power feeding system. FIG. 5A is a circuit diagram illustrating a modification of the wireless power feeding system. FIG. 5B is a circuit diagram illustrating a modification of the wireless power feeding system.

[1. Overview of wireless power supply system]

(1) A wireless power feeding system according to an embodiment includes a power transmitter that performs wireless power transmission using electromagnetic waves. Wireless power transmission is a method for transmitting power in a contactless manner. The power transmitter radiates electromagnetic waves for power transmission. The frequency of the electromagnetic wave is not particularly limited, but is, for example, a frequency within a range of 300 MHz to 3 THz. The frequency from 300 MHz to 3 THz is called microwave.

  The wireless power feeding system according to the embodiment includes a distance sensor. The distance sensor measures a distance between a human body wearing a wearable device that is wirelessly powered by electromagnetic waves and the power transmitter. The distance sensor, for example, emits ultrasonic waves, radio waves, or light, and measures the distance based on reflection from an object for distance measurement. The distance measurement method may be a triangulation method, or a method for obtaining a distance by the time until the emitted light is reflected and returned. In addition, the distance sensor may calculate a distance between the human body and the power transmitter from an image obtained by photographing the human body and the power transmitter, for example. Thus, the method for measuring the distance is not particularly limited, and any method may be used as long as the distance can be measured.

  The distance between the human body and the power transmitter may be measured as the distance between the wearable device attached to the human body and the power transmitter. The distance sensor may be provided in the vicinity of the power transmitter, or may be provided apart from the power transmitter. The distance sensor may be provided on the human body, may be provided in the vicinity of the human body, or may be provided apart from the human body. The distance sensor may be provided at a position away from either the human body or the power transmitter.

  When the distance sensor includes a transmitting element such as an ultrasonic wave, radio wave, or light and a receiving element that receives ultrasonic wave, radio wave, light, or the like, one of the transmitting element and the receiving element is a human body (or wearable device). ) Side, and the other side may be provided on the power transmitter side.

  A wearable device refers to a device worn on the human body. The wearable device is not particularly limited as long as the wearable device operates with wirelessly powered power. The wearable device may be worn outside the human body or may be worn inside the human body. The wearable device may be attached to any part of the human body, and may be any of hands, feet, torso, and head, for example.

  The wireless power supply system according to the embodiment includes a controller. The controller is configured by a computer that executes a computer program, for example. The controller may operate with hardware logic.

  The controller adjusts the intensity of the electromagnetic wave transmitted from the power transmitter. The power transmitter radiates electromagnetic waves to the wearable device attached to the human body, but the intensity of the electromagnetic waves causes unnecessary biological effects on the human body wearing the wearable device according to the distance between the human body and the power transmitter. It is adjusted to the extent that it does not reach. Therefore, even if electromagnetic waves are irradiated toward the human body, it is possible to prevent unnecessary biological effects from being exerted on the human body. In addition, the intensity | strength of the electromagnetic waves transmitted from a power transmitter is represented by the magnitude | size [W] of transmission power, for example. The electromagnetic wave transmitted from the power transmitter attenuates in proportion to the square of the propagation distance of the electromagnetic wave. Therefore, for example, by adjusting the transmission power so that the electromagnetic wave that has attenuated during propagation and reaches the human body has such a magnitude that it does not affect the biological action unnecessary for the human body, the influence of the electromagnetic wave on the human body is avoided. be able to.

  “To the extent that no unwanted biological effects are exerted on the human body” means a range in which safety to the human body is recognized by regulations and standards for electromagnetic wave protection. The human body in “a degree that does not exert unnecessary biological effects on the human body” is, for example, a human body of a healthy person. The human body in the “degree that does not exert unnecessary biological effects on the human body” does not include the human body of a person who is placed in a special situation such as a pacemaker user.

  Regulations / standards for electromagnetic wave protection are established for each country / region. However, there are regulations / standards in the country / region where the wireless power supply system according to the embodiment is used or the country / region where use is expected. Applied.

  For example, in Japan, the Ministry of Internal Affairs and Communications (formerly the Ministry of Posts and Telecommunications) issued an advisory No. 38 “Guidelines for Protection of Human Body in Use of Radio Waves” from the Telecommunications Technology Council on June 25, 1990 regarding the effects of radio waves on the human body. We have received a report on (consultation on June 27, 1988). In this report, a guideline value of radio wave intensity that does not affect the human body (radio wave protection guideline) is shown. The radio wave protection guideline is a recommended guideline because it is a safe situation where an electromagnetic field does not exert unnecessary biological effects on the human body when the human body is exposed to an electromagnetic field in the use of radio waves. The radio wave protection guideline targets radio waves having a frequency from 10 kHz to 300 GHz.

  The management guidelines in the radio wave protection guidelines cover conditions P for situations where the main points of the protection guidelines are utilized and the electromagnetic environment is managed, and situations where the protection guidelines and the status of radio wave usage are not recognized. It is divided into the condition G to perform. The guide value of the electromagnetic field strength (average value for 6 minutes) when the condition G is satisfied is, for example, an effective value of the electric field strength of 61.4 [V / m] at a frequency of 1.5 GHz to 300 GHz.

  In the embodiment, the wearable device is a device that can supply power with an electromagnetic wave intensity that is less than or equal to an extent that does not exert unnecessary biological effects on the human body. Therefore, even when a small amount of electric power below the extent that does not cause unnecessary biological effects on the human body is transmitted from the power transmitter, the wearable device can operate by receiving power supply.

  In the embodiment, the power transmitter wirelessly supplies power to the wearable device attached to the human body without causing unnecessary biological effects on the human body wearing the wearable device.

(2) The distance sensor is preferably disposed in the vicinity of the power transmitter. The distance sensor is preferably provided so as to measure the distance in the radiation direction of the electromagnetic wave by the power transmitter. The distance sensor measures the distance in the radiation direction of electromagnetic waves by the power transmitter, so that the measured distance can be treated as the distance between the human body and the power transmitter, and the distance measurement accuracy is Rise.

(3) The power transmitter is preferably provided in a device used in the vicinity of a person. In this case, since the power transmitter can be installed in the vicinity of a person, the transmitted power can be reduced. The distance sensor can also be provided in a device used in the vicinity of a person. A device used in the vicinity of a person is, for example, a microphone, a speaker, a display, lighting, a smartphone, a tablet, a computer, or other electric / electronic devices. A device used in the vicinity of a person may be a mechanical device or a tool used by a person such as furniture. Note that at least one of the power transmission device and the distance sensor may be attached to a building or vehicle component such as a wall, ceiling, floor, or window.

(4) The device used in the vicinity of a person is preferably a microphone. Since the user of the microphone is generated close to the microphone, if the power transmitter is provided in the microphone, the power transmitter can be arranged close to a person. The microphone may be a handheld hand microphone or a microphone supported by a microphone stand, for example.

  Moreover, it is preferable that the apparatus provided with a power transmitter is an apparatus used toward a person like a microphone. By setting the radiation direction of the radio wave by the power transmitter in accordance with the direction directed to the person in the device used for the person, the radio wave can be reliably radiated toward the human body. Examples of devices used for people include lighting, speakers, displays, smartphones, and tablets.

(5) The microphone preferably has sound collection directivity in a specific direction. The power transmitter is preferably provided to radiate electromagnetic waves in the specific direction. Since the direction in which the microphone is directed to collect sound is generally the direction in which the person is present, by emitting electromagnetic waves in a specific direction in which the microphone is directed to collect sound, the human body (particularly, the head of the human body). ) The power transmission efficiency to wearable devices attached to is increased.

  It is preferable that the distance sensor is provided in the microphone and is provided so as to measure the distance in the specific direction. In this case, the distance to the human body (particularly the head of the human body) can be accurately measured.

(6) It is preferable that the power transmitter includes a ground body disposed so as to oppose the human body, and a monopole antenna that is erected from the ground body and bent so that the tip is directed to the side. By using a monopole antenna, for example, the antenna size can be reduced compared to a dipole antenna. A monopole antenna radiates radio waves in the outward direction of the pole-shaped antenna element, but by bending it, radio waves radiated in the direction opposite to the human body are reflected by the ground body and directed toward the human body. Can do. As a result, power transmission efficiency is increased.

(7) If the distance between the human body and the power transmitter is greater than a predetermined value or if the human body cannot be detected, the controller adjusts the intensity of the electromagnetic wave transmitted from the power transmitter to a predetermined value or less. Alternatively, it is preferable to stop wireless power transmission from the power transmitter. In this case, useless power transmission can be prevented.

(8) The wireless power feeding system may further include a proximity preventing body that prevents a human body from approaching the power transmitter. In this case, it is possible to prevent the human body from getting too close to the power transmitter.

(9) The proximity preventer can be provided such that the distance between the human body and the power transmitter does not become less than the lower limit value of the setting range in which the intensity of the electromagnetic wave transmitted from the power transmitter is adjusted. In this case, the proximity preventer can prevent the distance between the human body and the power transmitter from being less than the lower limit value of the setting range.

(10) The proximity preventer can be provided so that the distance between the human body and the power transmitter does not become less than the lower limit in the measurement range of the distance sensor. In this case, the proximity preventer can prevent the distance between the human body and the power transmitter from being less than the lower limit value of the measurement range of the distance sensor.

(11) A wireless transmission system according to another embodiment includes a power transmitter that radiates electromagnetic waves in a plurality of directions to perform wireless power transmission, and a distance between the human body and the power transmitter in the plurality of directions. A wearable device that is wirelessly powered by electromagnetic waves is mounted with a distance sensor that measures the intensity of each direction of the electromagnetic waves transmitted from the power transmitter according to the distances in a plurality of directions measured by the distance sensor. And a controller for adjusting to such an extent that unnecessary biological effects are not exerted on the human body. The wearable device is a device that can supply power with an electromagnetic wave intensity that is less than or equal to an extent that does not exert unnecessary biological effects on the human body. The power transmitter wirelessly supplies power to the wearable device attached to the human body without exerting an unnecessary biological action on the human body wearing the wearable device. In this case, the intensity of the electromagnetic wave transmitted from the power transmitter is adjusted according to the direction.

[2. Example of wireless power supply system]

  A wireless power supply system 10 illustrated in FIG. 1 wirelessly supplies power to a wearable device 70 attached to a human body H using a microwave. In the embodiment, the wearable device 70 is an mW class wearable device. An mW class wearable device is a device that operates with a received power of 1 mW or more and less than 1 W. The mW class wearable device may be a device that operates with a received power of 100 mW or less. A device that operates with a received power of 100 mW or less is, for example, an LED. Some LEDs can operate (light up) even with power of 100 mW or less. In addition, many wearable devices such as watches can operate with power of 100 mW or less. The mW class wearable device may be a device that operates with a received power of 10 mW or less. Many semiconductor integrated circuits can operate with such low power.

  The wireless power supply system 10 includes a wireless power transmitter 20. Hereinafter, the wireless power transmitter 20 is simply referred to as a transmitter 20. The transmitter 20 transmits a microwave (for example, a frequency of 2.45 GHz). The transmitter 20 is for relatively low power transmission. The transmission power of the transmitter 20 is, for example, 50 dBm (100 W) or less, more preferably 45 dBm or less, and further preferably 40 dBm (10 W) or less. Since the transmitted power is small, the transmitter 20 can be installed in the vicinity of the human body H.

  The transmitter 20 includes, for example, an oscillator 21, amplifiers 22 and 23, and an antenna 24. In the embodiment, the amplifiers 22 and 23 include a preamplifier 22 and a power amplifier 23. The output of the power amplifier 23 is connected to the antenna 24. The antenna 24 radiates radio waves for power transmission. In the illustrated example, the frequency of radio waves is 2.45 GHz.

  The wireless power supply system 10 includes a controller 40. The controller 40 is connected to the preamplifier 22 via the digital / analog converter 60. The controller 40 adjusts the transmission power of the radio wave radiated from the antenna 24 by controlling the bias voltage of the preamplifier 22. The controller 40 may adjust the transmission power by controlling the bias voltage of the power amplifier 23.

  The controller 40 has a computer including a processor 41 and a memory 42. The processor 41 executes a computer program 44 stored in the memory 42. The computer program 44 is for causing the computer to function as the controller 40.

  The wireless power supply system 10 includes a distance sensor 30. The illustrated distance sensor 30 optically measures the distance. The distance sensor 30 includes a light source 31 that irradiates light toward a human body H that is a distance measurement target, and a light receiving element 32 that receives light reflected from the human body H. The light receiving element outputs an output value corresponding to the distance D from the distance sensor 30 to the human body H. The output value is given to the controller 40 via the analog / digital converter 50.

  In the embodiment, the distance sensor 30 is installed in the vicinity of the transmitter 20 so that the distance D to the human body H measured by the distance sensor 30 is substantially equal to the distance between the human body H and the transmitter 20. Yes. Therefore, the controller 40 can handle the distance D measured by the distance sensor 30 as the distance between the human body H and the transmitter 20. When the distance sensor 30 and the transmitter 20 are at different positions, the transmission from the human body H is performed based on the distance between the distance sensor 30 and the transmitter 20 and the distance D to the human body measured by the distance sensor 30. What is necessary is just to obtain | require the distance between the containers 20. FIG.

  FIG. 2 shows the magnitude of the output of the distance sensor 40 according to the actual measurement distance D. In the embodiment, the output of the distance sensor 40 decreases as the distance D increases. Therefore, the distance D can be obtained based on the output of the distance sensor 40. However, the distance sensor 40 has a measurement range, and the output value from the distance sensor 40 is not reliable in a range (outside the measurement range) E2 that is smaller than the lower limit value D1 in the measurement range. Therefore, even if the distance D is obtained from the output of the distance sensor 40 when the actual distance D is smaller than the lower limit value D1, a correct distance cannot be obtained. Note that the lower limit value D1 is, for example, 5 cm.

  A table 43 is stored in the memory 42 of the controller 40. The controller 43 refers to the table 43 based on the distance sensor output (distance D), and determines the transmission power of the transmitter 20 according to the distance sensor output (distance D). FIG. 3A shows an example of the table 43. The table 43 shows that the output value of the distance sensor is in the range from 0.5 [V] (distance D is equivalent to about 60 cm) to 3.0 [V] (distance D is equivalent to about 7 cm). A power set value (a bias voltage of the amplifier 22) is set. In the table 43, the transmission set power setting value increases and the transmission power increases as the distance D increases, and the transmission power setting value decreases and the transmission power decreases as the distance D decreases.

  In the embodiment, the controller 40 determines that the distance sensor output (distance D) has a setting range E1 (3.0 [V] (about 7 cm) to 0.5 [V] (about 60 cm)) set in the table 43. When it is outside, the transmission power is set to 0 (transmission from the transmitter 20 is stopped). Note that the controller 40 may adjust the transmission power to a relatively small predetermined value or less when the distance D is outside the setting range E2, E3. In the range E2 that is lower than the lower limit D2 of the setting range E1, the influence on the human body can be suppressed by reducing the transmission power to 0 or relatively small. On the other hand, as the distance D increases, power attenuation increases, and power reception by the wearable device 70 becomes difficult. Therefore, even in the range E3 exceeding the upper limit D3 of the setting range E1, wasteful power transmission can be prevented by reducing the transmission power to 0 or relatively small.

  As shown in FIG. 3B, the controller 40 adjusts the transmission power within a range of, for example, 18 dBm to 38 dBm in accordance with the distance D indicated by the distance sensor output within the setting range E1. The transmission power adjustment range may be, for example, a range of 10 dBm (10 mW) to 50 dBm (100 W). The lower limit of the transmission power adjustment range may be 15 dBm or 20 dBm. The upper limit of the transmission power adjustment range may be 45 dBm or 40 dBm.

  When the distance D decreases with the same transmitted power, the received power at the position of the human body H (wearable device 70) increases, and the electric field protection guidelines are safe electric field strengths that do not exert unnecessary biological effects on the human body. There is a risk of exceeding 61.4 [V / m]. On the other hand, when the distance D increases, the received power decreases in inverse proportion to the square of the distance D. Therefore, even if there is no influence on the human body, there is a possibility that the power necessary for the wearable device 70 to operate cannot be obtained. is there.

  Therefore, the controller 40 determines the transmission power according to the distance D so that the transmission power increases as the distance D increases and the transmission power decreases as the distance D decreases. The determined transmitted power takes into account the attenuation of the radio field intensity due to the distance D, and is a safe electric field intensity that does not exert unnecessary biological effects in the human body H, and the received power necessary for the wearable device 70 to operate. It is the size which becomes.

  FIG. 3B shows the magnitude of the transmission power adjusted according to the table 43 of FIG. 3A. Within the setting range E1, the transmission power is weakened by decreasing the distance D, thereby suppressing the influence on the human body, and the transmission power is increased as the distance D increases. However, when the distance D becomes larger than the upper limit (predetermined value) D3 of the setting range E1, the transmission power becomes zero. Also, when the distance D becomes smaller than the lower limit D2 of the setting range E1, the transmission power becomes zero.

  FIG. 3C shows the power value of the transmitted power from the transmitter 20 received by the dipole antenna at a distance D from the transmitter 20. In FIG. 3, “with power control” indicates a case where the transmission power is adjusted according to the table 43, and “without power control” indicates a case where the transmission power is not adjusted. In the case of “without power control”, the received power increases as the distance D decreases, whereas in the case of “with power control”, the received power is 3 dBm regardless of the distance. The guide value 61.4 [V / m] of the electromagnetic field strength defined in the radio wave protection guide corresponds to about 3 dBm as the power when the power is received by the dipole antenna. In this way, by adjusting the transmitted power, the received power can be suppressed to a level that does not cause unnecessary biological effects on the human body according to the protection guidelines.

  The controller 40 may determine the transmission power based on a calculation formula for calculating the transmission power from the distance sensor output without using the table 43.

  4A and 4B show the microphone 100 including the wireless power feeding system 10. Since the microphone 100 is a device that is used toward a person and is a device that is installed in the vicinity of a person, the microphone 100 can efficiently transmit power.

  The illustrated microphone 100 is a hand microphone, and includes a sound collection head 110 provided on an upper portion of a microphone main body that is a hand-held portion. The sound collection head 110 has an elliptical shape that is long in the longitudinal direction L of the microphone body. FIG. 4B shows a direction L along the longitudinal direction of the microphone body in the microphone 100. In the following, along this direction L, the direction on the sound collecting head 110 side is referred to as “upward”, and the opposite direction is referred to as “downward”.

  Since the microphone 100 is directed toward a person, the microphone 100 has sound collection directivity centered on the upper side. The sound collection head 110 includes a sound collection unit 120 having upward directivity. The sound collection unit 120 has an element for converting sound into an electrical signal.

  The sound collection head 110 has a plate-like ground body 112 therein. One surface of the ground body 112 faces upward and opposes the human body H. The sound collection unit 120 is provided below the ground body 112 in the sound collection head 110.

  A monopole antenna 24 is provided in the sound collection head 110 so as to stand upward from the ground body 112. The antenna 24 is bent so as to face sideways in the middle in the longitudinal direction. Here, the side does not need to be a direction completely orthogonal to the direction L, and includes a slightly upward direction and a slightly downward direction with respect to the direction completely orthogonal to the direction L. The radio wave radiated from the monopole antenna 24 includes the radio wave M2 that travels downward in addition to the radio wave M1 that travels upward. The radio wave M2 that travels downward can be reflected upward by the ground body 112. Therefore, the radio wave radiated from the transmitter 20 has upward directivity and can efficiently transmit power to the upper human body H. Further, by bending the monopole antenna 24, the antenna 24 can be accommodated in the sound collection head 110 while suppressing an increase in size of the sound collection head 110.

  The distance sensor 30 is provided in the sound collection head 110 so as to measure a distance from a human body located above. As shown in FIG. 4A, the ground body 112 has two through holes 112a and 112b for the distance sensor 30 formed therein. One through-hole 112a is for the light emitted from the light source 31 to be transmitted upward, and the other through-hole 112b is for the light reflected from the upper human body H to reach the light receiving element 32. It is. By providing the light source 31 and the light receiving element 32 below the ground body 112, the influence on the radiation of radio waves can be suppressed.

  At least the upper side of the sound collecting head 110 above the ground body 112 is a dielectric, and is covered with a cover 111 made of a light transmissive material. The cover 111 is made of, for example, a transparent or translucent resin. Since the cover 111 is made of a dielectric, it is possible to avoid the influence on the emission of radio waves, and it is transparent or semi-transparent so that transmission of light from the distance sensor 30 and reflected light can be allowed. Note that the cover 111 may have a through hole in order to facilitate the passage of sound. The cover 111 is formed such that the upper end 111a thereof is located at a position greater than the distance D2 or D2 from the distance sensor 30. For this reason, even if the human body H comes close to contact with the microphone 100, the distance from the distance sensor 30 in the direction L does not become D2 or less. Thus, the cover 111 is a proximity preventing body that prevents the human body H from approaching the distance sensor 30.

  Since the distance D2 is larger than the lower limit D1 of the measurement range of the distance sensor 30, the distance between the human body H and the transmitter 20 is reduced by the cover (proximity prevention body) 111 at the position of the distance D2. It is prevented that the measurement range is less than the lower limit D1. When the distance D is less than the lower limit D1 of the measurement range of the distance sensor 30, the output of the distance sensor 30 becomes unreliable, but according to the embodiment, it is possible to prevent an unreliable value from being output from the distance sensor 30.

  Further, since the distance D2 is also a lower limit value of the setting range E1 in which the intensity of transmitted power is adjusted, a distance sensor is provided by the cover (proximity prevention body) 111 at the position of the distance D2 (or a position larger than the distance D2). The distance D output from 30 is prevented from becoming less than the lower limit value D2 of the setting range E1.

  When the microphone 100 shown in FIGS. 4A and 4B is installed for collecting a human voice, the sound collection head 110 is necessarily directed to the human body (particularly, the head) H. The transmitter 20 provided in the head 110 can efficiently transmit power to a wearable device attached to the head of a human body. The distance sensor 30 provided in the sound collection head 111 can measure the distance to the human head.

[3. Modified example of wireless power supply system]

  5A and 5B show a modification of the wireless power supply system 10. In the wireless power feeding system 10 according to the modification, the power transmitter 20 includes a plurality of antennas 24a, 24b, 24c, and 24d directed in a plurality of directions X1, X2, Y1, and Y2. Each of the antennas 24a, 24b, 24c, and 24d has directivity in the Y1, X2, Y2, and X1 directions, and can radiate radio waves in the respective directions Y1, X2, Y2, and X1.

  In the wireless power feeding system 10 according to the modification, the distance sensor includes a plurality of sensor elements 30a, 30b, 20c, and 30d that measure the distance D from the human body H in each of the Y1, X2, Y2, and X1 directions. Prepare.

  As shown in FIG. 5B, the controller 40 is provided with each sensor element 30a, 30b, 20c, 30d. The controller 40 specifies the direction in which the human body H exists and the distance D based on the sensor element output. The controller 40 controls the preamplifiers 22a, 22b, 22c, and 22d to adjust the power (amplitude) of the transmitted radio waves and, if necessary, adjust the phase of the radio waves, thereby adjusting the antennas 24a, 24b, The directivity of radio waves radiated from 24c and 24d and the transmission power are adjusted. The controller 40 performs the control based on the azimuth in which the human body H exists and the distance D, so that the radio wave radiation direction and the transmission power are appropriate according to the azimuth in which the human body H exists and the distance D. be able to.

  That is, the wireless power feeding system 10 according to the modification can also wirelessly power the wearable device 70 attached to the human body H without exerting unnecessary biological effects on the human body H wearing the wearable device.

  The present invention is not limited to the above embodiment, and various modifications can be made.

DESCRIPTION OF SYMBOLS 10 Wireless power supply system 20 Wireless power transmitter 21 Oscillator 22 Preamplifier 23 Power amplifier 24 Antenna 30 Distance sensor 31 Light source 32 Light receiving element 40 Controller 41 Processor 42 Memory 43 Table 44 Program 50 ADC
60 DAZC
100 Microphone 110 Sound collecting head 111 Cover 112 Ground body 112a Through hole 112b Through hole

Claims (11)

A power transmitter for wireless power transmission using electromagnetic waves;
A distance sensor that measures a distance between a human body wearing a wearable device that is wirelessly powered by electromagnetic waves and the power transmitter;
A controller that adjusts the intensity of electromagnetic waves transmitted from the power transmitter according to the distance between the human body and the power transmitter to such an extent that the human body wearing the wearable device does not have unnecessary biological effects. And comprising
The wearable device is a device that can supply power with an electromagnetic wave intensity of the following level that does not exert unnecessary biological effects on the human body,
The power transmission device wirelessly feeds power to the wearable device attached to the human body without exerting an unnecessary biological action on the human body wearing the wearable device. The wireless power feeding system according to claim 1, wherein the distance sensor is disposed in the vicinity of the power transmitter and is configured to measure a distance in a radiation direction of an electromagnetic wave by the power transmitter. The wireless power feeding system according to claim 1, wherein the power transmitter is provided in a device used in the vicinity of a person. The wireless power feeding system according to claim 3, wherein the device used in the vicinity of the person is a microphone. The microphone has sound collection directivity in a specific direction,
The power transmitter is provided to radiate electromagnetic waves in the specific direction,
The wireless power feeding system according to claim 4, wherein the distance sensor is provided in the microphone so as to measure a distance in the specific direction. The power transmitter includes: a ground body disposed so as to oppose the human body; and a monopole antenna that is erected from the ground body and bent so that a distal end faces sideways. The wireless power feeding system according to any one of the above. The controller adjusts the intensity of the electromagnetic wave transmitted from the power transmitter to a predetermined value or less when a distance between the human body and the power transmitter is larger than a predetermined value or when the human body cannot be detected. The wireless power feeding system according to claim 1, wherein wireless power transmission from the power transmitter is stopped. The wireless power feeding system according to claim 1, further comprising a proximity preventing body that prevents the human body from approaching the power transmitter. The proximity preventing body is provided such that a distance between the human body and the power transmitter does not become less than a lower limit value of a setting range in which the intensity of electromagnetic waves transmitted from the power transmitter is adjusted. 9. The wireless power feeding system according to 8. The wireless power feeding system according to claim 8 or 9, wherein the proximity preventing body is provided such that a distance between the human body and the power transmitter does not become less than a lower limit value in a measurement range of the distance sensor. A power transmitter that radiates electromagnetic waves in multiple directions and performs wireless power transmission;
A distance sensor for measuring a distance between a human body and the power transmitter in a plurality of directions;
According to the distances in a plurality of directions measured by the distance sensor, the strength of each direction of the electromagnetic wave transmitted from the power transmitter is reduced to an unnecessary biological action on a human body wearing a wearable device that is wirelessly powered by the electromagnetic wave. A controller that adjusts to the extent that it does not reach,
The wearable device is a device that can supply power with an electromagnetic wave intensity of the following level that does not exert unnecessary biological effects on the human body,
The power transmission device wirelessly feeds power to the wearable device attached to the human body without exerting an unnecessary biological action on the human body wearing the wearable device.

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