Patent Description:
In recent years, wireless power supply systems have been developed, which can charge batteries wirelessly. Such wireless power supply systems may be referred to as non-contact battery chargers or the like. It is known that, in wireless power transmission, alignment of antennas or coils on a power receiving side and a power transmitting side is important to achieve efficient power transmission. For example, in a system where a moving object having a power receiving coil is charged, it is necessary to precisely locate the moving object at a predetermined position where a power transmitting coil is installed.

Such a wireless power supply system is used for charging an electronic device mounted on a shopping cart operated by a customer. As described above, to charge the electronic device, it is necessary to locate the shopping cart at a predetermined stop position such that the power receiving unit of the electronic device aligns with an antenna of a power transmitting unit. However, a shopping cart is usually designed to be easily moved around on a shopping floor for customers' convenience. Thus, such design makes it difficult for the shopping cart to stop and stay at a predetermined position for wireless power transmission. <CIT> and <CIT> describe a non-contact power supply system for a shopping cart.

For this reason, there has been proposed a system including a guide rail and roller stoppers arranged along the rail, which guides and stops a shopping cart at a predetermined position so that the power receiving coil of the electronic device aligns with the power transmission coil. However, such a system tends to become complicated when several shopping carts are nested and stored at a designated location.

One or more embodiment provide a wireless power supply system and a power transmission device capable of precisely guiding several shopping carts to a location in which power transmission can be performed.

According to an embodiment, a wireless power supply system includes a power receiving device disposed on a bottom surface of a cart, a guide rail extending along a first direction for guiding wheels of carts, and a plurality of power transmission devices configured to wirelessly transmit power to the power receiving device. The power transmission devices being arranged along the guide rail at predetermined intervals. The guide rail having a plurality of engagement means arranged at the predetermined intervals such that one of the power transmission devices faces the power receiving device when a wheel of the cart is engaged with the engagement means. The guide rail has pairs of bumps as the engagement means.

The wireless power supply system further comprises a groove between adjacent transmission devices and extending perpendicular to the traveling direction, wherein a first brush is on the bottom surface of the cart, the first brush configured to contact an upper surface of each of the power transmission devices but not a bottom surface of the groove when the cart is moved along the guide rail.

Preferably, the guide rail includes two rails arranged parallel to each other, and the power transmission devices are between the rails.

Preferably, the wireless power supply system according to claim <NUM>, further comprises a second brush on the bottom surface of the cart, the second brush spaced from the first brush in the travelling direction of the cart.

Preferably, the power transmission devices wirelessly transmit power by magnetic field coupling.

Preferably, the wireless power supply system further comprises a battery on the cart, wherein the power receiving device is configured to charge the battery.

Preferably, the wireless power supply system further comprises a display device connected to the battery.

Preferably, the guide rail is configured to permit a plurality of carts to be arranged in a nested manner.

Preferably, each of the power transmission devices includes a display for indicating an operation status of the power transmission device.

Preferably, the power receiving device includes a display for indicating an operation status of the power receiving device.

In a configuration example not part of the claimed invention, the guide rail has a plurality of recesses as engagement means.

In another exemplary embodiment, there is also provided a wireless power transmission device, comprising a guide rail extending along a first direction and configured to guide wheels of a cart; and a plurality of power transmitters configured to wirelessly transmit power to a power receiver of a cart, the power transmitters being spaced at predetermined intervals along the first direction, wherein the guide rail has a plurality of engagement means arranged at the predetermined intervals, and each of the power transmitters is positioned to face the power receiver of the cart when a wheel of the cart is engaged with the engagement means.

Preferably, the guide rail includes two rails arranged parallel to each other, and the power transmitters are between the rails.

Preferably, the wireless power transmission device further comprises a groove between adjacent power transmitters, the groove extending perpendicular to the first direction, wherein an upper surface of each of the power transmitters is higher than a bottom surface of the groove.

Hereinafter, a wireless power supply system according to an embodiment will be described with reference to the drawings. As illustrated in <FIG> is a perspective view illustrating a shopping cart <NUM> on which a wireless power supply system according to an embodiment is mounted. The wireless power supply system includes a system on a power transmission side for wirelessly transmitting power (hereinafter called the "power transmission system") and a system on a power reception side for wirelessly receiving power that has been transmitted from the power transmission system (hereinafter called the "power receiving system").

The shopping cart <NUM> has an electronic device than can be powered or charged by a wireless power supply system. The power receiving system is mounted on the shopping cart <NUM> and wirelessly receives power. For example, the power receiving system charges a battery of the electronic device mounted on the shopping cart <NUM> using power wirelessly received. The power transmission system transmits power that can be received by a power receiving system mounted on a shopping cart <NUM>. For example, the power transmission system is installed at a location where the shopping cart <NUM> is stored.

The electronic device mounted on the shopping cart <NUM> operates using power supplied by the battery charged by the wireless power supply system. For example, the battery charged by the wireless power supply system may be installed in the shopping cart <NUM> separately from the electronic device, and may supply power to the electronic device via a wire or the like.

In the configuration example illustrated in <FIG>, the shopping cart <NUM> includes an electronic device <NUM>, a battery <NUM>, and a power receiver <NUM>, which are attached to a cart body <NUM> for storing a commodity sold at a store. The electronic device <NUM> is a device for providing information and services to a user. The battery <NUM> is a power supply device for operating the electronic device <NUM>. The power receiver <NUM> receives electric power transmitted from the power transmission system. The power receiver <NUM> charges the battery <NUM> with the received electric power.

In one embodiment, the battery <NUM> may be installed inside the electronic device <NUM>. In such a case, the battery <NUM> includes at least a battery cell and a charging circuit for charging the battery cell using the electric power received by the power receiver <NUM>. The electric power stored in the battery cell is then supplied to the electronic device <NUM>.

The cart body <NUM> has a basket <NUM> for storing commodities. The basket <NUM> is supported by a frame <NUM> provided with four casters <NUM> (15Fr, 15Fl, 15Rr, and 15Rl). The four casters <NUM> are provided at four corners of the lower portion of the frame <NUM>. The casters <NUM> (15Fr, 15Fl, 15Rr, 15Rl) respectively include front wheels 13Fr, 13Fl and rear wheels 13Rr, 13Rl, that rotate in the moving direction. The cart body <NUM> moves by the wheels <NUM> of the casters <NUM> rotating on the floor surface. Further, each of the casters <NUM> rotates about the vertical axis so that the user can freely change the moving direction.

A handle <NUM> is provided on a near side of the basket <NUM> in the frame <NUM>. The handle <NUM> can be gripped by a user. The user grips the handle <NUM> and moves the cart body <NUM>. In this disclosure, a direction from the handle <NUM> toward the basket <NUM> is called the "forward direction. " The front wheels 13Fr and 13Fl are guided by guide rails <NUM> and guide bases <NUM>, which will be described later.

Further, the lower portions of the frame <NUM> in which the four casters <NUM> are provided at four corners are narrower on the front side and wider on the rear side in the forward direction. For this reason, the width between the casters 15Fr and 15Fl that support the front wheels 13Fr and 13Fl is a smaller than the width of the casters 15Rr and 15Rl that support the rear wheels 13Rr and 13Rl. Thereby, a plurality of shopping carts are stored in a nested manner such that the frame of the rear shopping cart is stored along the frame of the front shopping cart.

In addition, the handle <NUM> side of the shopping cart <NUM> is referred to as the "near side" and the opposite side is referred to as the "leading side" with respect to the basket <NUM>. The basket <NUM> has an open/close surface 12a, the lower end of which opens and closes in the forward direction. Further, the basket <NUM> has a smaller surface on the leading side than the open/close surface 12a. Accordingly, when a plurality of shopping carts are stored in a nested manner, the rear shopping cart pushes up the open/close surface 12a of the front shopping cart, and those baskets <NUM> are overlapped each other.

The electronic device <NUM> is attached to the cart body <NUM>. In the configuration example illustrated in <FIG>, the electronic device <NUM> is attached to the handle <NUM> of the shopping cart <NUM>. The electronic device <NUM> is driven by the electric power supplied from the battery <NUM>. For example, the electronic device <NUM> is an information terminal such as a tablet terminal for providing information to a user or a commodity reader for acquiring information of a commodity selected by the user. Further, the electronic device <NUM> may be a charging device for charging a mobile terminal (such as, a mobile phone, a smartphone, a digital camera, or the like) carried by the user using the power supplied from the battery <NUM>.

In the configuration example illustrated in <FIG>, a tablet terminal 21A and an information reader 21B are shown as an example of the electronic device <NUM>. The tablet terminal 21A is a computer having a display unit on which a touch panel is provided. The tablet terminal 21A is installed with the display unit facing the user located on the handle <NUM> side. For example, the tablet terminal 21A displays information on a commodity read by the information reader 21B. Further, the tablet terminal 21A may be configured to perform settlement processing for commodities that have been registered by the information reader 21B.

The information reader 21B is a device for reading information about a commodity. The information reader 21B may include a display unit that displays the information on the read commodity. For example, the information reader 21B is an RFID (radiofrequency identification) tag reader that reads an RFID tag or the like attached to a commodity that is taken in or out of the basket <NUM>. Alternatively, the information reader 21B may be a scanner that reads commodity identification information such as a barcode attached to a commodity.

As the electronic device <NUM>, an interface device for connecting a mobile terminal (a smartphone, a tablet terminal, or the like) carried by a user may be provided in place of the tablet terminal 21A. The mobile terminal connected to the interface device operates as the electronic device <NUM> and performs the same processing as that of the tablet terminal 21A described above. Further, the interface device as the electronic device <NUM> may charge the mobile terminal. An interface device may incorporate the battery <NUM>, or may be installed separately from the battery <NUM>.

The power receiver <NUM> is attached to a bottom surface of the cart body <NUM>. The power receiver <NUM> receives power wirelessly transmitted from the power transmission system, and supplies the received power to the electronic device <NUM> or the battery <NUM>. The power receiver <NUM> includes a power receiving coil <NUM>, a control circuit, and the like. The power receiver <NUM> is installed on the bottom surface of the cart body <NUM> so that a power receiving surface for receiving power by the power receiving coil <NUM> is parallel to the floor surface on which a power transmitting coil of the power transmission system is disposed. The configuration of the control system of the power receiver <NUM> will be described later in detail.

The power receiver <NUM> is installed on the bottom surface of the cart body <NUM> so as to receive power transmitted from below the cart body <NUM>. According to the configuration shown in <FIG>, the power receiver <NUM> can receive electric power output from a power transmission coil <NUM> installed on an upper surface of a power transmission base <NUM>. The position at which the power receiver <NUM> is provided may be designed in accordance with the arrangement of a power transmitter <NUM> including the power transmission coil <NUM> disposed so as to face the power receiver coil <NUM>.

As discussed later with reference to <FIG>, a brush <NUM> is attached to an end face in the forward direction of the power receiver <NUM>. The lower end of the brush <NUM> slides on an upper surface of the guide base <NUM>.

Next, a configuration of the wireless power supply system for charging the battery <NUM> mounted on the shopping cart <NUM> will be described.

<FIG> is a perspective view illustrating shopping carts 1A-1D that are stored in a nested manner. As shown in <FIG>, each shopping cart 1A, 1B, 1C, and 1D on which the battery <NUM> is mounted is stored in a nested manner at a predetermined storage position.

In the storage position, the power transmission base <NUM> installed on the floor surface is disposed. The power transmission base <NUM> includes two guide rails <NUM> (31Fl, 31Fr) for guiding the left and right front wheels 13Fl, 13Fr and the guide base <NUM> between the two guide rails <NUM>. The guide rails <NUM> guide each shopping cart <NUM> to the storage position.

As shown in <FIG>, the guide base <NUM> guides the left front wheel 13Fl along a guide path <NUM> formed between the guide rail 31fl and the guide base <NUM>, and guides the right front wheel 13fr along a guide path <NUM> formed between the guide rail 31fr and the guide base <NUM>. Each of the guide paths <NUM> and <NUM> may be a groove formed on the floor surface.

The guide path <NUM> has a plurality of recesses 33a at predetermined pitches P. The guide path <NUM> has a plurality of recesses 34a at predetermined pitches. The front wheels 13Fl are engaged with the recesses 33a, and the front wheels 13Fr are engaged with the recesses 34a. The positions at which the recesses 33a and 34a are set will be described later.

As shown in <FIG> and <FIG>, a power transmitter <NUM> is embedded in the guide base <NUM> at a predetermined pitch P. Furthermore, the guide base <NUM> has grooves <NUM> spaced from each other along the traveling direction of the shopping cart <NUM> each groove <NUM> extending perpendicular to the traveling direction.

In the storage position, the wheels <NUM> of the shopping carts <NUM> move along the guide rails <NUM>, and the shopping carts <NUM> are stored such that the adjacent shopping carts are nested. On the near side, the basket <NUM> of the shopping cart <NUM> has the open/close surface 12a, the lower end of which can open and close. Further, on the leading side, the basket <NUM> has the surface smaller than the open/close surface 12a. As a result, when the leading side of the basket <NUM> of the rear shopping cart 1B is pushed against the open/close surface 12a of the front shopping cart 1A, the open/close surface 12a of the front shopping cart opens toward the forward direction. When the rear shopping cart 1B further is pushed towards the forward direction, the leading side of the basket <NUM> of the rear shopping cart 1B reaches the center of the basket <NUM> of the front shopping cart 1A, and those two shopping carts are stored in a nested manner.

Further, the frame <NUM> of each shopping cart <NUM> is formed so that the near side is wider and the leading side is narrower. For this reason, the width between the casters 15Fr, 15Fl that support the front wheels 13Fr, 13Fl of the shopping cart <NUM> is smaller than the width between the casters 15Rr, 15Rl that support the rear wheels 13Rr, 13Rl. Accordingly, at the storage position, the frame <NUM> of the rear shopping cart 1B overlaps with the frame <NUM> of the front shopping cart 1A, and thus two or more shopping carts are stored in a nested manner.

The power transmitter <NUM> wirelessly transmits power that can be received by the power receiver <NUM>. The power transmitter <NUM> includes the power transmission coil <NUM> for power transmission, a circuit for power transmission, and the like. The power transmitter <NUM> is installed toward the bottom surface of the shopping cart body <NUM> such that a power transmission surface (a surface facing the power receiving coil <NUM> of the power receiver) for outputting power from the power transmission coil <NUM> is parallel to the floor surface.

Furthermore, the power transmitter <NUM> is provided at a position facing the power receiver <NUM> of each shopping cart <NUM> stored in the storage position. In the configuration example shown in <FIG>, the power receivers <NUM> of the shopping carts <NUM> stored in the storage position are arranged at predetermined pitches P along the guide rails <NUM>. Therefore, the power transmitters <NUM> are arranged at the predetermined pitches P along the guide rail <NUM> so as to face the power receivers <NUM> of the shopping carts <NUM>. The pitch P is the same as the pitch P at which the recesses 33a and 34a are provided. That is, when the power transmitter <NUM> and the power receiver <NUM> face each other, the front wheels 13Fl are engaged with the recesses 33a and the front wheels 13Fr are engaged with the recesses 34a.

In general, a nested state of shopping carts depends on the shapes of the frame and the basket. However, the distances between the shopping carts is not always identical. According to the above-described structure, the front wheels 13Fl and 13Fr of the shopping cart <NUM> are engaged with the recesses 33a and 34a, and the front and rear shopping carts are stored in a nested manner, and thus the interval between the front and rear shopping carts <NUM> becomes a predetermined distance. That is, in the storage position, the power receiver <NUM> of each shopping cart <NUM> will be correctly positioned to face the power transmitter <NUM>.

Next, the configuration of the control system of the wireless power supply system will be described.

The wireless power supply system includes the power receiving system including the power receiver <NUM> installed in the shopping cart <NUM>, and the power transmission system including the power transmitter <NUM> installed corresponding to the storage position of the shopping cart <NUM>. That is, in the wireless power supply system, the power transmitter <NUM> is installed in correspondence with the position of the shopping cart in the storage position, and wirelessly transmits power to the power receiver <NUM> installed in the shopping cart. In the wireless power supply system, the power transmitter <NUM> of the power transmission system wirelessly transmits power without being physically and electrically connected to the power receiver <NUM> of the power receiving system. The transmission method is, for example, a magnetic field resonance method, which is a magnetic field coupling method and in which power transmission can be performed at about <NUM> to <NUM> between the power transmitter <NUM> and the power receiver <NUM>.

<FIG> is a hardware block diagram of a wireless power supply system.

The wireless power supply system wirelessly transmits power and includes a system on a power transmission side (i.e., the power transmission system) and a system on a power reception side (i.e., the power receiving system). The power transmission system is a system for wirelessly transmitting power to the power receiver <NUM> mounted in the shopping cart <NUM> stored in the storage position. The power receiving system is a system in which the power receiver <NUM> wirelessly receives power and charges the battery <NUM> with the received power.

The power transmission system includes the power transmission base <NUM> installed on the floor surface. The power transmission base <NUM> includes the power transmitters <NUM> installed along the guide rails <NUM> in the storage position for the shopping carts <NUM>. The power transmitter <NUM> is powered by DC power supplied from, for example, an AC adaptor connected to a commercial power supply. The power transmitter <NUM> operates in one of a power transmission state in which power is supplied to the power receiver <NUM> and a standby state in which power is not supplied to the power receiver <NUM>.

In the configuration illustrated in <FIG>, each power transmitter <NUM> included in the power transmission system includes a power supply circuit <NUM>, a power transmission circuit <NUM>, a power transmission coil <NUM>, a controller <NUM>, a display unit <NUM>, a resonance capacitor <NUM>, and the like. The power transmission coil <NUM> and the resonance capacitor <NUM> are connected in series or in parallel.

The power supply circuit <NUM> converts the voltage of the DC power supply from the outside into a voltage suitable for the operation of each circuit. The power supply circuit <NUM> generates power and supplies the power to the power transmission circuit <NUM>. Further, the power supply circuit <NUM> generates power and supplies the power to the controller <NUM>.

The power transmission circuit <NUM> generates transmission power for transmitting power from the power transmission coil <NUM>. The power transmission circuit <NUM> supplies the generated power transmission power to the power transmission coil <NUM>. For example, based on the control of the controller <NUM>, the power transmission circuit <NUM> generates AC power as the transmission power by switching the DC power supplied from the power supply circuit <NUM>.

The power transmission coil <NUM> outputs the power that can be received by the power receiver <NUM> in accordance with the power transmitted from the power transmission circuit <NUM>. The power transmission coil <NUM> is formed in a planar shape with a power transmission surface for transmitting electric power. The power transmission surface of the power transmission coil <NUM> is disposed so as to face the power receiving surface of the power receiving coil <NUM> of the power receiver <NUM> in a state of being parallel to the floor surface.

For example, the power transmission coil <NUM> operates as a power transmission resonance circuit by being connected in series or in parallel to the resonance capacitor <NUM>. When the AC power is supplied from the power transmission circuit <NUM>, the power transmission coil <NUM> as the power transmission resonance circuit generates a magnetic field corresponding to the supplied AC power. The power transmission coil <NUM> may have a winding structure in which an insulated wire is wound, or may be a coil pattern formed on a printed circuit board.

The display unit <NUM> is an indicator that indicates a state of the power transmitter <NUM>. The display unit <NUM> switches the display in accordance with the control of the controller <NUM>. For example, the display unit <NUM> switches the display color in accordance with the operation state of the power transmitter <NUM>. Further, the display unit <NUM> may display a message indicating the operation state.

The controller <NUM> controls the operation of the power transmission circuit <NUM> and the display unit <NUM>. The controller <NUM> includes a processor and a memory. The processor executes an arithmetic processing. The processor performs various types of processing according to a program(s) stored in the memory. The memory stores data used by the processor executing the program(s). The controller <NUM> may be a microcomputer, an oscillation circuit, and the like.

For example, the controller <NUM> switches the display of the display unit <NUM> in accordance with the state of the power transmitter <NUM>. Further, the controller <NUM> controls the frequency of the AC power output from the power transmission circuit <NUM> and the ON/OFF of the operation of the power transmission circuit <NUM>. For example, the controller <NUM> controls the power transmission circuit <NUM> to switch between a state in which the power transmission coil <NUM> generates a magnetic field (i.e., the power transmission state) and a state in which a magnetic field is not generated in the power transmission coil <NUM> (i.e., the standby state). Further, the controller <NUM> may control the power transmission circuit <NUM> to intermittently generate a magnetic field in the power transmission coil <NUM> in order to change the power to be transmitted.

The power transmitter <NUM> may have a wireless communication circuit for performing wireless communication. For example, the wireless communication circuit is a circuit that performs wireless communication at a frequency different from the frequency of the power transmission. The controller <NUM> may control each unit by performing wireless communication with the power receiver <NUM> via the wireless communication circuit. The wireless communication circuit may perform wireless communication at the same frequency as the frequency of the power transmission by utilizing a known load modulation technique.

The power receiving system includes the power receiver <NUM> and the battery <NUM> mounted on each shopping cart <NUM>. The power receiver <NUM> includes a power receiving coil <NUM>, a power receiving circuit <NUM>, a controller <NUM>, and a display unit <NUM>. The battery <NUM> also includes a charging circuit <NUM> and at least one battery cell <NUM>. Additionally, the power receiver <NUM> may include an output terminal for supplying power to the electronic device <NUM>. In such a case, the battery <NUM> may be charged by electric power supplied through the electronic device <NUM>.

The power receiving coil <NUM> receives the power transmitted from the power transmission coil <NUM>, and supplies the received power to the power receiving circuit <NUM>. The power receiving coil <NUM> has a planar shape in which a power receiving surface for receiving power is formed. The power receiving surface of the power receiving coil <NUM> is installed on the bottom surface of the cart body <NUM> in a state parallel to the floor surface.

For example, the power receiving coil <NUM> operates as a power receiving resonance circuit by being connected in series or in parallel to the resonance capacitor <NUM> for power reception. When the power receiving coil <NUM> as the power receiving resonance circuit is moved close to the power transmission coil <NUM> of the power transmitter <NUM>, the power receiving coil <NUM> is electromagnetically coupled to the power transmission coil <NUM>. The power receiving coil <NUM> generates an induced current by the magnetic field output from the power transmission coil <NUM> of the power transmitter <NUM>. The power receiving coil <NUM> may have a winding structure in which an insulated wire is wound, or may be a coil pattern formed on a printed circuit board.

The power receiving coil <NUM> serving as the power receiving resonance circuit supplies the received AC power to the power receiving circuit <NUM>. In other words, the power receiving coil <NUM> functions as an AC power supply when receiving the AC power from the power transmitter <NUM>. In addition, when the magnetic field resonance method is used for power transmission, the self-resonance frequency of the power reception resonance circuit (i.e., the power reception coil <NUM>) is substantially the same as the frequency transmitted by the power transmitter <NUM>. As a result, the power transmission efficiency in the case where the power receiving coil <NUM> and the power transmission coil <NUM> are electromagnetically coupled to each other is improved.

The power receiving circuit <NUM> converts the received power supplied from the power receiving coil <NUM> into power that can be supplied to the battery <NUM> or the electronic device <NUM>. For example, the power receiving circuit <NUM> rectifies the received power supplied from the power receiving coil <NUM>, and converts the rectified power into a direct current. The power receiving circuit <NUM> is, for example, a circuit including a rectifying bridge including a plurality of diodes. In such a case, a pair of input terminals of the rectifying bridge is connected to the power reception resonance circuit including the power reception coil <NUM> and the resonance capacitor <NUM>. The power receiving circuit <NUM> performs full-wave rectification of the received power supplied from the power receiving coil <NUM>, and outputs DC power from the pair of output terminals.

The display unit <NUM> is a display device that displays various kinds of information. For example, the display unit <NUM> is an indicator that indicates a state of the power receiver <NUM>. The display unit <NUM> switches the display in accordance with the control of the controller <NUM>. For example, the display unit <NUM> switches the display color in accordance with the operation state of the power receiver <NUM>. Further, the display unit <NUM> may display a message indicating the operation state.

The controller <NUM> controls the operation of the power receiving circuit <NUM> and the display unit <NUM>. The controller <NUM> includes a processor and a memory. The processor executes an arithmetic processing. The processor performs various types of processing according to a program(s) stored in the memory. The memory stores data used by the processor executing the program(s). The controller <NUM> may be a microcomputer, an oscillation circuit, and the like. For example, the controller <NUM> switches the display of the display unit <NUM> in accordance with the state of the power receiver <NUM>.

The power receiver <NUM> may have a wireless communication circuit for performing wireless communication with the corresponding power transmitter <NUM>. For example, the wireless communication circuit is a circuit that performs wireless communication at a frequency different from the frequency of the power transmission. The controller <NUM> may control each unit by wirelessly communicating with the power transmitter <NUM> via the wireless communication circuit. The wireless communication circuit may perform wireless communication at the same frequency as the frequency of the power transmission by utilizing a known load modulation technique.

The battery <NUM> has the charging circuit <NUM> that supplies the power supplied from the power receiving circuit <NUM> of the power receiver <NUM> to the battery cell <NUM> as the charging power. For example, the charging circuit <NUM> converts the supplied power from the power receiving circuit <NUM> into a direct current used for charging of the battery cell <NUM>. That is, the charging circuit <NUM> converts the power from the power receiving circuit <NUM> into the charging power of the predetermined current value having a voltage value suitable for charging the battery cell <NUM>, and supplies the converted power to the battery cell <NUM>.

The battery cell <NUM> is charged by the charging power supplied from the charging circuit <NUM>. The battery cell <NUM> is connected to the electronic device <NUM>, and supplies electric power to the electronic device <NUM>. Next, a positional relationship between a guide device for guiding the shopping cart <NUM> to the storage position, the power receiver <NUM> installed in the shopping cart <NUM>, and the power transmitter <NUM> will be described.

Since the power transmitter <NUM> and the power receiver <NUM> wirelessly transmit power, the power transmission coil <NUM> and the power receiver coil <NUM> need to be opposed to each other such that the distance of the center positions thereof is about <NUM> to <NUM>. In the wireless power transmission, appropriate alignment of the power transmission coil <NUM> and the power reception coil <NUM> improves the power transmission efficiency. For example, the power transmission coil <NUM> (i.e., the power transmitting antenna) wirelessly transmits power to the power receiving coil <NUM> by using magnetic field coupling such as electromagnetic induction or magnetic field resonance. In wireless power transmission using such magnetic field coupling, when the position of the power transmission coil and the position of the power reception coil are not aligned with each other, power cannot be efficiently transmitted.

The wireless power supply system according to an embodiment is configured such that the power transmitter <NUM> transmits power to the power receiver <NUM> provided in the shopping cart <NUM> stored in the storage position. Therefore, the power transmitter <NUM> is disposed at the position where the power receiver <NUM> provided on the bottom surface of the shopping cart <NUM> is located when the shopping cart <NUM> is stored in the storage position. <FIG> illustrates the power transmitters <NUM> arranged at positions facing the power receivers <NUM> of the shopping carts <NUM> stored in the storage position. As explained above, the power receivers <NUM> are provided on the bottom surface of the shopping carts <NUM>.

In the storage position, the shopping cart <NUM> is stored with a previously stored shopping cart in a nested manner. The first shopping cart <NUM> stored in the storage position engages with the recesses 33a and 34a, provided along the guide rails <NUM> and <NUM>, and stops. The shopping cart <NUM> is not fixed in the stopped state, but is movable when pushed by strong force.

The second and subsequent shopping carts <NUM> engage with the second and subsequent recesses 33a and 34a on the guide rails <NUM> and <NUM>. Accordingly, the interval between the front and rear shopping carts <NUM> becomes a predetermined interval, and the power receivers <NUM> of the shopping carts <NUM> stored in the storage position are also arranged at predetermined intervals. Correspondingly, the power transmitters <NUM> are arranged on the floor surface at an interval corresponding to the interval of each shopping cart stored in the storage position. Accordingly, the power transmitters <NUM> can transmit power toward the power receivers <NUM> installed on the bottom surfaces of the shopping carts <NUM>.

That is, in each shopping cart <NUM> on which the battery <NUM> is mounted, the power receiver <NUM> including the power receiving coil <NUM> is provided on the bottom surface of each shopping cart body <NUM> so that the power receiving surface is parallel to the floor surface. In addition, the power transmitter <NUM> is installed so that the power transmission coil <NUM> is positioned parallel to the power receiving coil <NUM> of each shopping cart <NUM> stored in the storage position.

As shown in <FIG>, the brush <NUM> is attached to the power receiver <NUM> and slides on the upper surface of the guide base <NUM>. Thus, even in a case where dust E accumulates on the power transmission surface of the power transmission coil <NUM>, the brush <NUM> guides the dust E to the groove <NUM> as shown in <FIG>.

With such a configuration, as shown in <FIG> and <FIG>, even in a case where the dust E accumulates on the power transmission surface of the power transmitter <NUM>, the dust E is guided to the groove <NUM>, and thus, the power supply is less likely to be performed in a state where the dust E exists between the power receiving coil <NUM> and the power transmission coil <NUM>. As a result, it is possible to provide a wireless power supply system capable of safely performing power transmission by wireless without generating heat generation or the like caused by dust containing metal.

As shown in <FIG>, as a structure for engaging the front wheels 13F1 and 13Fr, bumps 33b and 34b are used.

Next, a modified example of a power transmission system for a wireless power supply system will be described.

As a configuration for preventing the dust E from accumulating between the power receiving coil <NUM> and the power transmission coil <NUM>, as shown in <FIG>, in addition to the brush <NUM>, a rear brush <NUM> may be attached to the power receiver <NUM>. Accordingly, the rear brush <NUM> of the power receiver <NUM> can prevent the dust E from entering into a gap between the power receiving coil <NUM> of the preceding shopping cart <NUM> and the power transmission coil <NUM>.

As described above, the wireless power supply system according to embodiments can cause the power receiver <NUM> and the power transmitter <NUM> to face each other when a user or a store clerk pushes the shopping cart <NUM> to the storage position without special effort to align the shopping cart <NUM>. As a result, power is efficiently supplied from the power transmitter to the battery <NUM> mounted on the shopping cart <NUM>. If a battery <NUM> is not mounted on the shopping cart <NUM>, it is possible to supply electric power directly to the electronic device <NUM>. Since a shopping cart <NUM> that has been stored longest is more likely to have been fully charged, the shopping cart <NUM> can be taken out from the leading side in the forward direction from the storage location and used.

In the above-described embodiments, the charge level of the battery <NUM> may be displayed on the display unit <NUM> by measuring the current value of the power transmission circuit <NUM> of the power transmitter <NUM>. However, the current value of the power receiving circuit <NUM> of the power receiver <NUM> may also be measured, and the value of the current value may be transmitted to the controller <NUM> of the power transmitter <NUM> through a wireless communication circuit, and the power reception amount of the battery <NUM> may be displayed on the display unit <NUM>.

As a power transmission method, a magnetic field resonance method has been exemplified, but a magnetic field coupling method including any electromagnetic induction method may instead be used, and, in general, the power transmission method is not limited as long as the method is capable of providing power in a wireless manner.

In the above-described embodiments, each guide rail of the guide device forms a groove for guiding the wheel of the shopping cart <NUM> along the forward direction. <FIG> illustrates an example of a configuration in which each guide rail of the guide device includes a pair of guide members for sandwiching both side surfaces of the wheel. However, the guide device according to the embodiments does not necessarily have to be formed of a groove for guiding the wheel in this manner. For example, the guide device may be configured such that some portions of the guide rails guide only one side of the wheels rather than both.

In the above-described embodiments, the previously stored shopping cart <NUM> is taken out from the leading side, but in other examples a wheel stopper may be provided at the leading end of the groove formed by the guide rail 31Fr. The wheel stopper is arranged along the groove of the guide rail 31Fr, and stops the front wheel 13Fr of the shopping cart <NUM> that has been stored first in the storage position. The stopper can be formed as a wall surface or the like that stops the distal end portion of the cart body <NUM> at a predetermined position. In such a case, a shopping cart <NUM> which is stored last is taken out first.

The above-described embodiments are described referring to a shopping cart used in a store. However, the shopping cart may be any type of cart, e.g., a picking cart or the like used in a warehouse or the like.

The novel embodiments described herein may be embodied in a variety of other forms; furthermore, various omissions, substitutions and changes in the form of the embodiments described herein may be made without departing from the scope of the appended claims.

Claim 1:
A wireless power supply system, comprising:
a power receiving device (<NUM>) on a bottom surface of a cart (<NUM>);
a guide rail (<NUM>) extending along a first direction for guiding wheels (<NUM>) of carts; and
a plurality of power transmission devices (<NUM>) configured to wirelessly transmit power to the power receiving device and arranged along the guide rail at predetermined intervals, characterized in that:
the guide rail has a plurality of engagement means arranged at the predetermined intervals such that one of the power transmission devices faces the power receiving device when a wheel of the cart is engaged with the engagement means,
the wireless power supply system further comprises a groove (<NUM>) between adjacent power transmission devices and extending perpendicular to the traveling direction, and
a first brush (<NUM>) is on the bottom surface of the cart, the first brush configured to contact an upper surface of each of the power transmission devices but not a bottom surface of the groove when the cart is moved along the guide rail, wherein:
the guide rail has pairs of bumps (33b, 34b) as the engagement means.