Wireless power transmitting system, power receiving station, power transmitting station, and recording medium

A wireless power transmitting system that transmits power from a power transmitting station to a power receiving station wirelessly includes the power receiving station. The power receiving station includes a unit receiving power from the power transmitting station, a unit obtaining a level of power received through the antenna, a unit obtaining a level of power consumed by the device operating while being supplied with received power and a unit transmitting the received power level and the power consuming level to the power transmitting station wirelessly. The power transmitting station includes a unit receiving the received power level and the power consuming level from the power receiving station wirelessly, a unit controlling the level of power transmitted through the transmitting antenna based on the difference between the received power level and the received power consuming level, and a unit transmitting power to the power receiving station wirelessly.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based upon and claims the benefit of priority of the prior Japanese Patent Application No. 2009-85326, filed on Mar. 31, 2009, the entire contents of which are incorporated herein by reference.

BACKGROUND

The present embodiments discussed herein relate to a wireless power supply system. In particular, the present embodiments relate to a control apparatus to transmit power in the wireless manner.

2. Description of the Related Art

In a known wireless power transmitting system, a power transmitting apparatus transmits power in the wireless manner to a power receiving apparatus using an electromagnetic wave. The power receiving apparatus converts the received electromagnetic wave into power and supplies the resultant power to a power consuming device or circuit in the power receiving apparatus.

In a known wireless power supply system, a position and orientation detecting unit detects the position and orientation of a receiving antenna and transmits information concerning the detected position and orientation to a controller of a power transmitting apparatus. The controller determines control target values of, for example, the magnitudes, phases, and frequencies of currents flowing through transmission coils so as to optimize the intensity of a magnetic field generated or received in the position and orientation of the receiving antenna, and performs control so that currents having values equal to the control target values flow through the transmission coils via driving circuits. Thus, the receiving antenna may be supplied with power with efficiency at all times.

As a well-known wireless power transmitting system, a wireless sensor system including a wireless sensor unit and a sensor signal receiver has been known. The wireless sensor unit includes a sensor section detecting a target of detection, a sensor signal transmitting section transmitting a sensor signal output from the sensor section in a wireless manner, and a power supply section. The power supply section of the wireless sensor unit includes power generating means and a power receiving portion which receives driving power wireless-transmitted. The wireless sensor unit further includes a power supply monitoring section. When power produced by power generation is insufficient, the wireless sensor unit transmits a power shortage signal, thus allowing wireless power supply. The above-described known systems are discussed in, for example, Japanese Unexamined Patent Application Publication No. 2008-283789 and No. 2005-100164.

As another wireless power transmitting system, there has been known a capsule endoscope system including an external unit which includes a transmitting antenna, a receiving antenna for receiving power transmitted by the transmitting antenna, a capsule endoscope which includes a receiving circuit section and a capsule endoscope functioning section. In the capsule endoscope system, a capsule endoscope includes a received power detecting unit that detects power received by the receiving antenna and an imaging rate controller that changes the rate of imaging by the capsule endoscope. When received power detected by the received power detecting unit is lower than a preset threshold value, the imaging rate controller reduces the imaging rate. Consequently, the capsule endoscope may be controlled so that the endoscope does not stop operating even if the efficiency of receiving power supplied from the wireless power supply system is lowered (refer to Japanese Unexamined Patent Application Publication No. 2008-284160).

In a known intra-subject information acquiring system, a remaining-power recognizing circuit included in a capsule endoscope recognizes the amount of remaining power of the capsule endoscope and superimposes information indicating the amount of remaining power on a transmission signal. An RF transmitter in the capsule endoscope transmits the transmission signal to a receiving apparatus on the outside of a subject. A remaining-power detecting circuit included in the receiving apparatus detects the information indicating the amount of remaining power. A display unit of an external apparatus displays the detected information (refer to Japanese Unexamined Patent Application Publication No. 2007-61191).

SUMMARY

It is an aspect of the embodiments discussed herein to provide a wireless power transmitting system. The wireless power transmitting system transmits power from a power transmitting station to a power receiving station wirelessly. The power receiving station includes a unit receiving power from the power transmitting station, a unit obtaining a level of power received through the antenna, a unit obtaining a level of power consumed by the device operating while being supplied with received power and a unit transmitting the received power level and the power consuming level to the power transmitting station wirelessly. The power transmitting station includes a unit receiving the received power level and the power consuming level from the power receiving station wirelessly, a unit controlling the level of power transmitted through the transmitting antenna based on the difference between the received power level and the received power consuming level, and a unit transmitting power to the power receiving station wirelessly.

The object and advantages of the embodiment discussed herein will be realized and attained by means of elements and combinations particularly pointed out in the claims.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and only are not restrictive exemplary explanatory are not restrictive of the invention, as claimed.

The above-described embodiments of the present invention are intended as examples, and all embodiments of the present invention are not limited to including the features described above.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

In a known wireless power transmitting system, a power transmitting apparatus transmits a given power to a power receiving apparatus.

The inventors have recognized that when the power consumption of the power receiving apparatus varies and decreases, part of the received power may be wasted without being consumed. The inventors have further recognized that when the distance between the power transmitting apparatus and the power receiving apparatus is shorter than an assumed distance, a part of the received power may be wasted in the power receiving apparatus.

Furthermore, the inventors have recognized that power supplied for transmitting power may be reduced by controlling transmitting power in the power transmitting apparatus in accordance with a change in power consumption in the power receiving apparatus.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory and are not intended to restrict the present invention.

An embodiment of the present invention will be described with reference to the drawings. In the drawings, the same components and elements are designated by the same reference numerals.

FIG. 1depicts a wireless power transmitting system according to an embodiment of the present invention, the system including a power transmitting station10and an information terminal or electronic apparatus20which serves as a power receiving station.

The power transmitting station10includes, for example, a controller102, a wireless power transmitter104for power supply, a memory106, a transmitter-receiver (TX/RX)160for wireless communication, and a power supply circuit180. The wireless power transmitter104includes an antenna (ANT) to transmit power wireless. The transmitter-receiver160is connected to an antenna (ANT) to communicate in the wireless manner. The power transmitting station10may be, for example, a wireless LAN base station (AP) including the transmitter-receiver160.

The information terminal20includes, for example, a controller202, a wireless power receiver204for receiving power, a received power measuring device206, a power converter208that converts alternating current (AC) to direct current (DC), a power consumption measuring device210, a margin determining unit220, a deciding unit230, a plurality of devices (components, or elements) or circuits250which use or consume received power, and a transmitter-receiver (TX/RX)260for communication. The elements204,206,208, and210may constitute a power receiver28which serves as a device. The information terminal20may be, for example, a personal computer or a personal digital assistant (PDA). The wireless power receiver204includes an antenna (ANT) to receive power. The transmitter-receiver260is connected to an antenna (ANT) to communicate in the wireless manner. The devices250may include devices (elements), such as a central processing unit (CPU), a hard disk drive (HDD), an optical disk drive (ODD), an audio device, and a USB port. The controller202, the margin determining unit220, and the deciding unit230may be some of functions realized by the CPU.

The controller102supplies a control signal CTL to an element, for example, the wireless power transmitter104and the transmitter-receiver160in the power transmitting station10. The controller102controls transmitting power pt to be transmitted by the wireless power transmitter104in accordance with a result of determination received from the information terminal20, feedback information, or a control signal. The controller102or the transmitter-receiver160may control power-on/off of the wireless power transmitter104.

The wireless power transmitter104, which is powered on by the controller102or the transmitter-receiver160, transmits or supplies, through the antenna, power based on an un-modulated electromagnetic wave in a frequency band of, for example, 0.3 GHz to 100 GHz controlled in accordance with the control signal CTL of the controller102. A maximum transmitting power output from the wireless power transmitter104is, for example, 60 W. The transmitter-receiver160transmits and receives RF signals, carrying necessary information, to and from the transmitter-receiver260with one or two transmitting and receiving radio frequencies (e.g., 13.56 MHz or/and 2.4 GHz) different from the frequency using transmitting power of the wireless power transmitter104in accordance with a short-range communication standard, such as Wireless LAN Standard, Bluetooth Standard, or Near Field Communication (NFC) Standard.

The controller202supplies a control signal CTL to an element, for example, the wireless power receiver204, the received power measuring device206, the power converter208, the power consumption measuring device210, the deciding unit230, the devices250, and the transmitter-receiver260in the information terminal20. The controller202or the transmitter-receiver260may control power-on/off of the wireless power receiver204.

The transmitter-receiver160in the power transmitting station10transmits an RF signal carrying information indicating a transmitting power level Pt supplied from the controller102.

The transmitter-receiver260in the information terminal20receives the RF signal carrying the information indicating the transmitting power level Pt from the power transmitting station10and supplies the transmitting power level Pt to the deciding unit230. The wireless power receiver204receives power based on the un-modulated electromagnetic wave from the wireless power transmitter104through the antenna and supplies the power, indicated at pr, received through the antenna to the received power measuring device206. The received power measuring device206measures the intensity of the received power pr supplied from the wireless power receiver204and supplies a received power level Pr indicating the intensity of the received power pr to the deciding unit230. The power converter208rectifies and smoothes alternating current (AC) supplied through the received power measuring device206from the wireless power transmitter104to produce direct current (DC) power and supplies the power, indicated pd, to the devices250.

The power consumption measuring device210measures the present power consumption pd of the devices250and supplies a level Pd of the measured power consumption pd to the deciding unit230. Here, the power consumption pd measured by the power consumption measuring device210indicates an average power consumption of the devices250for a short time. The devices250are supplied with the DC power pd from the power converter208through the power consumption measuring device210. The margin determining unit220determines a margin power level (value) Pm indicating a variable margin of the power consumption pd based on with operating modes of the devices250with reference to a table representing the relationship between the operating modes of the devices (elements)250and margin power levels Pm and supplies the determined margin power level Pm to the deciding unit230. In this case, the term “margin” means an extra amount of power for accommodating a variation in power consumption of the devices250.

The deciding unit230calculates a necessary variation (difference) or increase or decrease ΔPt in the transmitting power level Pt in the power transmitting station10based on the received power level Pr, the power consuming level Pd, the margin power level Pm, and a power transmitting efficiency Etr (or the transmitting power level Pt) and supplies the variation ΔPt to the transmitter-receiver260. The transmitter-receiver260transmits information indicating the necessary variation ΔPt in the transmitting power level Pt as feedback information to the power transmitting station10.

A memory area of the transmitter-receiver260or a memory device (250) holds authenticating information or identifying information (e.g., ID and password). The transmitter-receiver260transmits the authenticating information together with necessary information to the power transmitting station10.

FIG. 2depicts an exemplary configuration of the margin determining unit220.FIG. 3represents an example of the relationship between the devices (elements) which are in operation and the margin power levels Pm. The margin power levels Pm represented inFIG. 3denote margin power levels for devices other than the CPU. The margin power for the CPU is set to, for example, 10 W, irrespective of the operating modes of the other devices.

The margin determining unit220includes a device operation detecting section222and a determining section224. The device operation detecting section222detects an operating mode of each of the devices (250) and supplies information regarding the types of the devices in operation to the determining section224. The determining section224determines or calculates a margin power level Pm in accordance with the information regarding the devices in operation based on the table representing the relationship between the operating modes of the devices and the margin power levels Pm.

FIG. 4illustrates an example of the margin power level Pm according to the operating modes of some devices of the devices250. The margin power level Pm illustrated inFIG. 4is equal to margin power of the devices excluding the CPU. The margin power for the CPU is, for example, 10 W irrespective of the operating modes of the other devices.

As illustrated on the left ofFIG. 4, when only the CPU of the devices250operates, the devices250require margin power of 10 W for the CPU and the margin power of 0.1 W for the other devices, namely, require total margin power of 10.1 W (Pm=10.1 W). As illustrated on the right ofFIG. 4, while the hard disk drive (HDD) and the audio device of the devices250are in operation in addition to the CPU, the devices250require margin power of 10 W for the CPU and margin power of 2 W for the hard disk drive and the audio device, namely, total margin power of 12 W (Pm=12 W).

FIG. 5represents an example of a procedure for transmission, reception, and processing between the power transmitting station10and the information terminal20inFIG. 1.

The procedure represented inFIG. 5is started when the controller102of the power transmitting station10is activated in response to, for example, power-on by a user. First, the controller102of the power transmitting station10activates or enables the transmitter-receiver160. In the operation502, the controller102or the transmitter-receiver160activates and initializes the wireless power transmitter104and controls the wireless power transmitter104to transmit minimum transmitting power ptmin (in the operation502). The wireless power transmitter104first transmits power for minimum power supply necessary to operate the transmitter-receiver260in the information terminal20. On the other hand, in the information terminal20, the received power measuring device206, the power converter208, the power consumption measuring device210, and the transmitter-receiver260are operable at any time. The wireless power receiver204first receives the minimum transmitting power ptmin necessary to be transmitted and received by the transmitter-receiver260from the power transmitting station10and keeps its operation using the received power pr. Alternatively, the controller202or the transmitter-receiver260in the information terminal20may first be supplied with power from a rechargeable battery (not illustrated) of the devices250in response to power-on by the user and be activated.

In the operation504, the transmitter-receiver160of the power transmitting station10modulates an RF carrier with data to request authenticating information or identifying information of a power receiving station in accordance with a request from the controller102, and periodically transmits an RF signal carrying the authenticating information request. The transmitter-receiver260of the information terminal20receives and demodulates the RF signal carrying the authenticating information request. The transmitter-receiver260may supply the request to the controller202. In the operation536, the transmitter-receiver260of the information terminal20transmits an RF signal carrying the authenticating information or identifying information (e.g., ID) of the information terminal20under the control of the controller202in response to the request. The transmitter-receiver160of the power transmitting station10receives and demodulates the RF signal carrying the authenticating information and then supplies the received authenticating information to the controller102. The controller102compares the authenticating information with authenticating information stored in the memory106or compares the identifying information with identifying information stored in the memory106, thus authenticating the information terminal20.

When the information terminal20is successfully authenticated, in the operation508, the controller102controls the wireless power transmitter104to transmit maximum transmitting power ptmax in an initial control state. The wireless power receiver204receives the maximum transmitting power from the power transmitting station10and operates the devices250using the received power pr.

Whereas, if the authentication of the information terminal20is unsuccessful, information received from the information terminal20is ignored and is not processed. As described above, the power transmitting station10controls the wireless power transmitter104in accordance with the result of authentication of the information terminal20. Consequently, the power transmitting station10may be prevented from being illegally controlled by an unauthorized apparatus.

In the operation510, the controller102of the power transmitting station10supplies information concerning the present transmitting power level Pt of the wireless power transmitter104to the transmitter-receiver160. The transmitter-receiver160transmits an RF signal carrying the information concerning the present transmitting power level Pt of the wireless power transmitter104to the information terminal20. The transmitter-receiver260of the information terminal20receives and demodulates the RF signal carrying the information concerning the transmitting power level Pt of the wireless power transmitter104and then supplies the information concerning the transmitting power level Pt to the deciding unit230.

In the operation542, the deciding unit230of the information terminal20determines a necessary power level (Pd+Pm) in the information terminal20based on the power consuming level Pd of the devices250supplied from the power consumption measuring device210and the margin power level Pm supplied from the margin determining unit220. Subsequently, the deciding unit230determines a necessary variation or increase/decrease in the transmitting power level Pt of the wireless power transmitter104based on the received power level Pr of the received power measuring device206, the necessary power level (Pd+Pm) in the information terminal20, the received transmitting power level Pt of the wireless power transmitter104, and the power transmitting efficiency Etr. In this case, the transmitting efficiency Etr is a value obtained by dividing the received power level Pr by the transmitting power level Pt and is expressed by the equation of Etr=Pr/Pt. For example, in a case where the distance between the information terminal20and the power transmitting station10ranges from 1 to 2 m, the efficiency Etr ranges from 0.5 to 0.33. Thus, the deciding unit230determines a value of the necessary variation ΔPt. The necessary variation ΔPt is given by the equation of ΔPt=(Pd+Pm−Pr)/Etr. The variation ΔPt has a positive or negative value or a value of 0. Then, the deciding unit230supplies the determined necessary variation ΔPt as the result of determination or a control signal to the adaptive signal processor60.

In the operation546, the transmitter-receiver260of the information terminal20transmits an RF signal carrying the necessary variation ΔPt, which serves as feedback information or the result of determination, to the power transmitting station10. The transmitter-receiver160of the power transmitting station10receives and demodulates the RF signal carrying the necessary variation ΔPt as the result of determination and then supplies the variation ΔPt to the controller102.

In the operation518, the controller102of the power transmitting station10controls, or increases or decreases the transmitting power pt of the wireless power transmitter104in accordance with the necessary variation ΔPt.

In the operation520, the wireless power transmitter104of the power transmitting station10transmits the transmitting power pt in accordance with the controlled transmitting power level Pt. In the operation522, the controller102supplies information concerning the present transmitting power level Pt to the transmitter-receiver160. The transmitter-receiver160transmits an RF signal carrying the information concerning the present transmitting power level Pt of the wireless power transmitter104to the information terminal20.

In the operation524, the transmitter-receiver160of the power transmitting station10periodically transmits an RF signal carrying a request for authenticating information of a power receiving station in accordance with a request from the controller102. In the operation548, the transmitter-receiver260of the information terminal20receives and demodulates the RF signal carrying the authenticating information request and then transmits an RF signal carrying the authenticating information of the information terminal20in response to the request. The transmitter-receiver160of the power transmitting station10receives and demodulates the RF signal carrying the authenticating information and then supplies the received authenticating information to the controller102. The controller102compares the authenticating information with authenticating information stored in the memory106, thus authenticating the information terminal20.

In the operation556, the controller202or the transmitter-receiver260of the information terminal20determines whether an authenticating information request has been received. If it is determined that an authenticating information request has been received, the process returns to the operation542. In the operation526, the controller102of the power transmitting station10determines whether authenticating information has been received. If it is determined that authenticating information has been received, the process returns to the operation546. That is, the controller102is in standby mode ready to receive a variation ΔPt.

The power transmitting station10repeats the operations518to526inFIG. 5and the information terminal20repeats the operations542to556.

If it is determined in the operation526that authenticating information has not been received, in the operation528, the controller102or the transmitter-receiver160of the power transmitting station10initializes the wireless power transmitter104and controls the wireless power transmitter104to transmit the minimum transmitting power ptmin. In the operation530, the wireless power transmitter104transmits the minimum transmitting power ptmin necessary for transmission and reception of the transmitter-receiver260of the information terminal20.

In the operation532, the transmitter-receiver160of the power transmitting station10periodically transmits an RF signal carrying an authenticating information request of a power receiving station in accordance with a request from the controller102.

FIG. 6represents an operation chart of a process, performed by the deciding unit230, to determine a variation or increase/decrease ΔPt in transmitting power level Pt.

Referring toFIG. 6, in the operation S602, the deciding unit230calculates a variation or increase/decrease ΔPt in transmitting power level Pt of the wireless power transmitter104using the following equations.
Variation ΔPt=(Power consuming level Pd+Margin power level Pm−Received power level Pr)/Efficiency Etr
Efficiency Etr=Received power level Pr/Transmitting power level Pt

In the operation S604, the deciding unit230determines whether the variation ΔPt is a positive value (ΔPt>0). If it is determined that it is not a positive value, the deciding unit230determines in the operation S606whether the variation ΔPt is a negative value (ΔPt<0) or is less than a negative tolerance Δ (ΔPt<−Δ).

When it is determined in the operation S604that the variation ΔPt is a positive value, the deciding unit230determines in the operation S612that the variation ΔPt in the transmitting power level Pt is an increase. When it is determined in the operation S606that the variation ΔPt is a negative value or is less than the negative tolerance −Δ, the deciding unit230determines in the operation S614that the variation ΔPt in the transmitting power level Pt is a decrease. A tolerance Δ is used to avoid unnecessary, often change of the transmitting power level Pt and is, for example, 0.1 W. When it is determined in the operation S606that the variation ΔPt is not a negative value or is not less than the negative tolerance −Δ, the deciding unit230determines in the operation S616that there is no variation ΔPt in the transmitting power level Pt (ΔPt=0).

FIG. 7depicts a modification of the wireless power transmitting system ofFIG. 1and depicts a wireless power transmitting system according to another embodiment of the present invention, the system including a power transmitting station12and an information terminal or electronic apparatus22that serves as a power receiving station.

Referring toFIG. 7, the power transmitting station12includes a deciding unit130in addition to the elements102to106,160, and180inFIG. 1. The information terminal22includes the elements202to220,250, and260. In this embodiment, the information terminal22does not include the deciding unit230. The deciding unit130makes a determination in a manner similar to the deciding unit230.

The transmitter-receiver260of the information terminal22receives information indicating a received power level Pr, information indicating a power consuming level Pd, and information indicating a margin power level Pm from the received power measuring device206, the power consumption measuring device210, and the margin determining unit220, respectively, and transmits an RF signal carrying the information to the power transmitting station12. The transmitter-receiver160of the power transmitting station12receives and demodulates the RF signal and supplies the information indicating the received power level Pr, the power consuming level Pd, and the margin power level Pm to the deciding unit130. The deciding unit130receives information indicating a transmitting power level Pt from the controller102.

The deciding unit130calculates a necessary variation ΔPt in transmitting power level Pt of the power transmitting station12based on the received power level Pr, the power consuming level Pd, and the margin power level Pm, and a power transmitting efficiency Etr (or the transmitting power level Pt), and supplies the variation ΔPt as a result of determination, feedback information, or a control signal to the controller102. The controller102controls transmitting power pt of the wireless power transmitter104based on the variation ΔPt received from the deciding unit130.

The other elements inFIG. 7and their operations are the same as those inFIG. 1.

FIG. 8represents a modification of the procedure ofFIG. 5and represents an example of a procedure for transmission, reception, and processing between the power transmitting station12and the information terminal22inFIG. 7.

Referring toFIG. 8, the operations502to508,520,524,536, and548are the same as those inFIG. 5. In the procedure represented inFIG. 8, the operations510,522, and546inFIG. 5may be omitted.

In the operation543, the transmitter-receiver260of the information terminal22receives a received power level Pr, a power consuming level Pd, and a margin power level Pm from the received power measuring device206, the power consumption measuring device210, and the margin determining unit220, respectively, and determines such received information as transmitting information.

In the operation544, the transmitter-receiver260of the information terminal22transmits an RF signal carrying the information indicating the received power level Pr, the power consuming level Pd, and the margin power level Pm to the power transmitting station12. The transmitter-receiver160of the power transmitting station12receives and demodulates the RF signal carrying the information and then supplies the information to the deciding unit130.

In the operation519, the deciding unit130of the power transmitting station12determines a necessary variation in the transmitting power level Pt of the wireless power transmitter104based on the power consuming level Pd, the margin power level Pm, the received power level Pr, the transmitting power level Pt, and the power transmitting efficiency Etr, thus determining a necessary variation ΔPt. The necessary variation ΔPt is given by the equation of ΔPt=(Pd+Pm−Pr)/Etr. Subsequently, the deciding unit130supplies the determined necessary variation ΔPt as a result of determination or a control signal to the controller102. The controller102controls, increases or decreases transmitting power of the wireless power transmitter104based on the variation ΔPt.

The operations526to532and the operation556inFIG. 8are the same as those inFIG. 5.

The power transmitting station12repeats the operations519to526inFIG. 8and the information terminal22repeats the operations543to556.

In a case where the power consumption of the devices250of each of the information terminals20and22inFIGS. 1 and 7relatively gently varies and a variation is absorbed by a margin, the transmitting power of each of the power transmitting stations10and12is controlled in a power saving manner in each of the embodiments inFIGS. 1 and 7.

Each of the information terminals20and22may include a small-capacity rechargeable battery. When the power consumption pd of the circuits250instantaneously increases sharply, alternatively, when a supply voltage of the power converter208is instantaneously lower than a threshold value, supply power pb of the battery may compensate for the instantaneous power shortage or voltage drop. For example, even when the power consuming level Pd of the devices250of the information terminal20or22sharply significantly varies to such extent that the power transmitting station10or12may not follow a variation ΔPt in transmitting power level, the devices250of the information terminal20or22may be prevented from malfunctioning.

The process illustrated by the operation chart inFIG. 6is also performed by the deciding unit130.

FIG. 9depicts another modification of the wireless power transmitting system ofFIG. 1and depicts a wireless power transmitting system according to further another embodiment of the present invention, the system including the power transmitting station10and an information terminal or electronic apparatus24that serves as a power receiving station.

Referring toFIG. 9, the information terminal24includes a charging and discharging circuit272, a remaining power detector274, and a rechargeable battery276in addition to the elements202to260inFIG. 1. The rechargeable battery276may be a small-capacity battery. The remaining power detector274detects a remaining power level Pbl of the battery276based on an output voltage of the battery. The charging and discharging circuit272receives information concerning a received power level Pr from the received power measuring device206, receives information concerning a power consuming level Pd from the power consumption measuring device210, and receives information concerning the remaining power level Pbl of the battery276from the remaining power detector274. The charging and discharging circuit272controls charging power pc or current supply to the battery276in accordance with the information, thus controlling the supply of DC power pb from the battery276to the devices250.

Accordingly, even if the difference (Pr−Pd) between the received power level Pr and the power consuming level Pd is less than or equal to a threshold value or is equal to zero such that the power consumption pd of the devices250is not instantaneously compensated by the received power pr of the wireless power receiver204, the power consumption may be instantaneously compensated by the power pb supplied from the battery276.

When the remaining power level Pbl of the battery276is less than or equal to a threshold value Pbth, the charging and discharging circuit272determines a charging power level Pc necessary for charging the battery276and supplies information concerning the charging power level Pc to the deciding unit230.

The deciding unit230calculates a necessary variation ΔPt in transmitting power level Pt in the power transmitting station10based on the received power level Pr, the power consuming level Pd, a margin power level Pm, the charging power level Pc, and a power transmitting efficiency Etr (or a transmitting power level Pt). The necessary variation ΔPt is given by the equation of ΔPt=(Pd+Pm+Pc−Pr)/Etr. The deciding unit230supplies the variation ΔPt to the transmitter-receiver260. The transmitter-receiver260transmits information indicating the necessary variation ΔPt in the transmitting power level Pt as feedback information to the power transmitting station10.

The charging and discharging circuit272determines a variation ΔPr in the received power level Pr. When determining that the variation ΔPr is an increase and the charging power level Pc may be ensured based on of the received power level Pr and the charging power level Pc (Pr−Pd>Pc), the charging and discharging circuit272starts charging the battery276. When the amount of power charged in the battery276detected by the remaining power detector274is full or not less than the necessary charging power level Pc (the difference between the received power level Pr from the received power measuring device206and the power consuming level Pd from the power consumption measuring device210) is less than or equal to a threshold value Pcth, the charging and discharging circuit272stops charging the battery276.

The other elements inFIG. 9and the operations thereof are the same as those elements inFIG. 1.

FIG. 10represents a process, performed by the charging and discharging circuit272, to control the charge of the battery276.

Referring toFIG. 10, in the operation S702, the charging and discharging circuit272determines whether a remaining power level Pbl of the battery276detected by the remaining power detector274is less than or equal to the threshold value Pbth. The operation S702is repeated until it is determined that the level is less than or equal to the threshold value.

When determining in the operation S702that the remaining power level Pbl is less than or equal to the threshold value, in the operation S704, the charging and discharging circuit272supplies a charging power level Pc necessary for charging the battery276to the deciding unit230.

In the operation S706, the charging and discharging circuit272determines, based on the difference between a received power level Pr from the received power measuring device206and a power consuming level Pd from the power consumption measuring device210, whether a charging power level Pc necessary to charge the battery276is ensured (Pr−Pd>Pc). The operation S706is repeated until it is determined that the necessary charging power level Pc is ensured.

When it is determined in the operation S706that the necessary charging power level Pc is ensured, in the operation S708, the charging and discharging circuit272starts to charge the battery276and stops the supply of the charging power level Pc to the deciding unit230during charging. The power consuming level Pd of the devices250and the battery276is measured by the power consumption measuring device210.

In the operation S710, the charging and discharging circuit272determines, based on the difference between the received power level Pr from the received power measuring device206and the power consuming level Pd from the power consumption measuring device210, whether the charging power level Pc necessary to charge the battery276is ensured. When the difference (Pr−Pd) between the received power level Pr and the power consuming level Pd is less than or equal to the threshold value or is equal to zero, it is determined that the necessary charging power level Pc is not ensured. When it is determined that the necessary charging power level Pc is not ensured, the process proceeds to the operation S714.

When it is determined in the operation S710that the necessary charging power level Pc is ensured, in the operation S712, the charging and discharging circuit272determines, based on a remaining power level Pbl of the battery276detected by the remaining power detector274, whether the power remaining level Pbl of the battery276indicates full. If it is determined that the power remaining level does not indicate full, the process returns to the operation S710. If it is determined that the power remaining level indicates full, the process goes to the operation S714. The operations S710and S712are repeated until the necessary charging power level Pc is not ensured, alternatively, until the remaining power level Pbl of the battery276indicates full.

In the operation S714, the charging and discharging circuit272stops charging the battery276. After that, the process returns to the operation S702.

As described above, when the power consuming level Pd of the devices250instantaneously increases, alternatively, when a supply voltage pd of the power converter208instantaneously falls below a threshold value, the instantaneous power shortage may be compensated for by the supply power pb of the battery276, thus preventing malfunction of the devices250in the information terminal24.

The process ofFIG. 5is also used in the wireless power transmitting system ofFIG. 9.

In this case, in the operation542inFIG. 5, the deciding unit230of the information terminal24determines a necessary power level (Pd+Pm+Pc) in the information terminal24based on the power consuming level Pd of the devices250including the battery276, the margin power level Pm, and the necessary charging power level Pc supplied from the charging and discharging circuit272. Subsequently, the deciding unit230determines a necessary variation or increase/decrease in the transmitting power level Pt of the wireless power transmitter104based on the received power level Pr, the necessary power level (Pd+Pm+Pc) in the information terminal24, the transmitting power level Pt of the wireless power transmitter104, and the power transmitting efficiency Etr. Then, the deciding unit230supplies the determined variation ΔPt as the result of determination to the transmitter-receiver260.

The process illustrated by the operation chart ofFIG. 6is also performed by the deciding unit230.

In this case, in the operation S602inFIG. 6, the deciding unit230calculates a variation or increase/decrease ΔPt in the transmitting power level Pt of the wireless power transmitter104using the following equations.
Variation ΔPt=(Power consuming level Pd+Margin power level Pm+Charging power level Pc−Received power level Pr)/Efficiency Etr
Efficiency Etr=Received power level Pr/Transmitting power level Pt

FIG. 11depicts a modification of the wireless power transmitting system ofFIG. 9and depicts an example of a wireless power transmitting system according to further another embodiment of the present invention, the system including a power transmitting station16and an information terminal or electronic apparatus26that serves as a power receiving station.

Referring toFIG. 11, the power transmitting station16includes the deciding unit130in addition to the elements102to106,160, and180inFIG. 1. The information terminal26includes the elements202to220and250to276inFIG. 9. In this embodiment, the information terminal26does not include the deciding unit230. The deciding unit130makes a determination in a manner similar to the deciding unit230inFIG. 9.

The transmitter-receiver260of the information terminal26receives information indicating a received power level Pr from the received power measuring device206, information indicating a power consuming level Pd from the power consumption measuring device210, information indicating a margin power level Pm from the margin determining unit220, and information indicating a necessary charging power level Pc from the charging and discharging circuit272, and then transmits an RF signal carrying the information to the power transmitting station16. The transmitter-receiver160of the power transmitting station16receives and demodulates the RF signal and then supplies the information indicating the received power level Pr, the power consuming level Pd, the margin power level Pm, and the necessary charging power level Pc to the deciding unit130. The deciding unit130further receives information indicating a transmitting power level Pt from the controller102.

The deciding unit130calculates a necessary variation ΔPt in the transmitting power level Pt in the power transmitting station16based on the received power level Pr, the power consuming level Pd, the margin power level Pm, the charging power level Pc, and a power transmitting efficiency Etr (or the transmitting power level Pt), and supplies the variation ΔPt to the controller102. The controller102controls, or increases or decreases transmitting power pt of the wireless power transmitter104based on the variation ΔPt.

The other elements inFIG. 11and the operations thereof are the same as those inFIG. 7or9.

The process ofFIG. 8is also used in the wireless power transmitting system ofFIG. 11.

In this case, in the operation543inFIG. 8, the transmitter-receiver260of the information terminal26receives information indicating a received power level Pr from the received power measuring device206, information indicating a power consuming level Pd from the power consumption measuring device210, information indicating a margin power level Pm from the margin determining unit220, and information indicating a necessary charging power level Pc from the charging and discharging circuit272, and determines the information as transmitting information.

In the operation544, the transmitter-receiver260of the information terminal26transmits an RF signal carrying the information indicating the received power level Pr, the power consuming level Pd, the margin power level Pm, and the necessary charging power level Pc to the power transmitting station16.

In the operation519, the deciding unit130of the power transmitting station16decides a variation or increase/decrease in transmitting power level Pt of the wireless power transmitter104based on the received power level Pr, the power consuming level Pd, the margin power level Pm, the necessary charging power level Pc from the charging and discharging circuit272, and the transmitting power level Pt of the wireless power transmitter104, thus determining a variation ΔPt. Subsequently, the deciding unit230supplies information indicating the determined variation ΔPt as the result of determination to the transmitter-receiver260. The controller102controls, increases or decreases transmitting power of the wireless power transmitter104based on the variation ΔPt.

The process illustrated by the operation chart ofFIG. 6is also performed by the deciding unit130.

As described above, even when a variation in power consumption of the devices250of each of the information terminal24inFIG. 9and the information terminal26inFIG. 11relatively sharply varies and the variation is not absorbed by a margin, the transmitting power of each of the power transmitting stations10and16is controlled in a power-saving manner in each of the embodiments depicted inFIGS. 9 and 11.

Further, according to an aspect of the embodiments, any combinations of the described features, functions and/or operations may be provided.