GB2583437A

GB2583437A - Wireless charging apparatus

Info

Publication number: GB2583437A
Application number: GB1819790.5A
Authority: GB
Inventors: Mhand Mohamed Cheikh; Ren Daqian
Original assignee: Planck Ltd
Current assignee: Planck Ltd
Priority date: 2018-12-04
Filing date: 2018-12-04
Publication date: 2020-11-04
Also published as: GB201819790D0

Abstract

Wireless charging apparatus 2 including a removable case for holding an electronic device 4, the removable case having a holding portion 6 for holding the electronic device and comprising a control circuit, an antenna portion 8 containing a wireless charging antenna, the antenna portion being movably mounted on the removable case so that it is movable between a standby position and a wireless charging position where the antenna is positioned at a transverse angle to the plane of the holding portion, the wireless charging antenna being electrically connected to the control circuit, an external power connector electrically connected to the control circuit, a battery electrically connected to the control circuit, and an internal power connector electrically connected to the control circuit and electrically connectable, in use, to the electronic device. Also disclosed is a method for use of the apparatus to wirelessly charge a portable electronic device, for example, a smart phone.

Description

Wireless Charging Apparatus The present invention relates to wireless charging apparatus for use with electronic devices, especially mobile electronic devices. The invention also relates to use of such apparatus for wirelessly charging electronic devices.

Wireless power transmission uses a transmitter device to generate and transmit an electromagnetic signal through space to a receiver that extracts electrical power from the signal. Wireless power transmission is useful where physical connections are inconvenient or difficult.

Wireless power transmission may be radiative or non-radiative. Radiative wireless power transmission may be used over relatively long distances. In near field or non-radiative wireless power transmission, power is transferred over short distances by magnetic fields using inductive coupling or by electric fields using capacitive coupling. In 1894, Nikola Tesla used resonant inductive coupling to wirelessly light incandescent lamps. Tesla developed a high-voltage, resonant transformer known as a Tesla coil.

Inductive coupling is currently the more widely used wireless power transmission method and is used in inductive heating including in electric hobs and industrial heaters and to wirelessly charge mobile electronic devices including mobile telephones, implantable medical devices and electric vehicles.

A number of wireless charging methods and devices have been described.

US-B-10 027 180 discloses a wireless power receiver including an antenna to receive radio frequency (RF) waves via a plurality of slots defined by a metal plate. Each slot comprises at least two continuous segments that are orthogonally positioned relative to each other.

WO-A-2009/018 568 discloses a deployable antenna to be used in a mobile device. The antenna can be folded into a stowed position in which it is coplanar with the housing. It can also be unfolded and used to receive wireless power from at least 6 inches (15 cm) away.

US-A-2011/175 461 discloses an energy harvesting circuit including one or more broadband or narrow band antennas to detect WIFI (wireless fidelity) or other RF (radio frequency) signals. The signals are rectified and voltage multiplied, and the resultant DC voltage is provided to a power management circuit.

US-A-2004/142 733 discloses a conductor-less charging and power system for electronic appliances and a method for communicating power to a power receiver employing wireless energy transmission. The remote charging system includes a power receiver system that may be incorporated in an appliance and includes an energy receptor capable of receiving the wireless power beam and transferring the energy from the beam io to an energy storage device included in the appliance.

Wireless power transfer using inductive coupling between wire coils has a relatively short range, with the power transmitted decreasing exponentially with distance and depends on the size and shape of the antennas. More sophisticated methods of inductive coupling using resonance increase power transfer and useable range between the transmitter and receiver antennas.

Wireless charging of mobile electronic devices may use a number of standards including the Qi standard, an open interface standard developed by the Wireless Power Consortium. The Qi system uses a charging pad transmitter and a compatible device with a receiver coil, which is placed on top of the pad, charging vice inductive coupling. Power may pass between the transmitter and receiver coil placed closely together, usually only separated by the outer casing of the two devices (< 10 mm). The coils must be aligned to make the connection. Resonant inductive coupling charges at greater distance (up to 45mm).

Wireless charging standards tends to be based on relatively low frequency signals (of the order of kHz to MHz) and despite the theoretical possibility of greater charging ranges tend to work well at very short range and are highly sensitive to the positioning or orientation of the receiver coil/antenna. Furthermore, current charging systems may cause heating of metallic parts (e.g. smartphone frames) and have some health risks resulting from concerns over electromagnetic field exposure and inductive heating especially if the user holds or uses the device during charging or has metallic medical implants (e.g. pacemakers). Higher frequency wireless charging (in the range of 3 to 30 MHz) has some advantages including a greater effective charging distance, but also has disadvantages including a higher sensitivity to metallic parts including frames in the device (e.g. metallic frames in smartphones) and sensitivity to the form and structure of the device.

There is, therefore, a need for improved wireless charging apparatus and methods.

It is an aim of the present invention to address this need.

The present invention accordingly provides, in a first aspect, a wireless charging apparatus, the apparatus comprising a removable case for holding an electronic device, the removable case having a holding portion for holding the electronic device and comprising a) a control circuit, b) an antenna portion containing a wireless charging antenna, the antenna portion being mounted on the removable case so that it is movable between a standby position and a wireless charging position where the antenna is positioned at a transverse angle to the (optionally, plane of the) holding portion, the wireless charging antenna being electrically connected to the control circuit, c) an external power connector electrically connected to the control circuit, d) a battery electrically connected to the control circuit, and e) an internal power connector electrically connected to the control circuit and electrically connectable, in use, to the electronic device.

Such an apparatus is advantageous because it provides for a removable case that is adaptable and suitable for wireless charging and reduces or eliminates heating and interference problems with metallic frames inside electronic devices (e.g. smartphones) that may be held in the removable case. A wireless charging apparatus comprising a removable case as in the present invention is beneficial because it may be used with many different types of electronic device of different shapes and configurations. Furthermore, because of the moveable antenna portion, the wireless charging apparatus may provide charging at greater distances than conventional apparatus which further improves safety for users.

In previously known devices, the charging range and efficiency of wireless power transfer tend to be limited by two main parameters: the "quality factor" of the antenna and the "impedance matching". The present invention is greatly advantageous because it provides for much improved quality factor and consistent impedance matching despite differences in the devices (e.g. different smartphones).

Furthermore, the use of a battery incorporated in the wireless charging apparatus is advantageous because it allows use of the battery either for receiving power from the wireless charging antenna when the electronic device is fully charged, and/or as an auxiliary power supply to the electronic device when wired or wireless charging is not available.

In use the apparatus may further comprise an electronic device in the removable case, and if so preferably the internal power connector is electrically connected to the electronic device.

The electronic device will usually be a mobile electronic device, optionally selected from a smartphone, a tablet computer, and a laptop computer.

The control circuit preferably controls the power management of the apparatus and switching of the wireless charging antenna, the external power connector, the battery, and the internal power connector.

Furthermore, preferably, the control circuit controls the charging priority management of the apparatus. Usually, the charging priority of the apparatus may be in the standby mode when the antenna portion is in the standby position and may be in the wireless charging mode when the antenna portion is in the wireless charging position.

When the apparatus is in standby mode, the charging priority of the control circuit may provide external power to the internal power connector, and when the internal power connector indicates the electronic device is fully charged, external power to the battery.

When the apparatus is in wireless charging mode, the charging priority of the apparatus may be external power to the internal power connector, and when there is no external power supply, wireless charging from the wireless charging antenna to the internal power connector, and when the internal power connector indicates the electronic device is fully charged, wireless charging from the wireless charging antenna to the batten*.

The wireless charging antenna may comprise a 2D or 3D antenna.

The antenna portion may be pivotably mounted on a pivot on the removable case so that it is able to pivot between a standby position and a wireless charging position where the antenna is positioned at a transverse angle to the holding portion.

Moving the antenna portion advantageously allows the wireless charging antenna to conform to a transverse angle that improves charging efficiency and range and helps to protect the electronic device itself (as well as the user) from the received varying electromagnetic field of the charging station.

Preferably, the transverse angle is in the range 10° to 350°, preferably in the range 45° to 315°, or 50° to 280°, more preferably in the range 85° to 275°, most preferably 90° to 270°, most preferably 115° to 245°. The most preferred angle is around 135° (or 225°) because this results in an angle of the wireless charging antenna to the electromagnetic field of the charging station of around 45° which provides good efficiency of charging.

Usually, the wireless antenna is of size in the range 10 mm to 55 mm.

In the standby position the antenna portion may be substantially co-planar with the holding portion The removable case may have a long edge and a short edge and the pivot may be substantially parallel to the long edge of the removable case.

Alternatively, the removable case may have a long edge and a short edge and the pivot may be substantially parallel to the short edge of the removable case.

The pivot may be located in the edge portion of the removable case, or the pivot may be located inward of the edge portion of the removable case.

Wireless charging apparatus of the present invention allows more efficient safe and convenient wireless charging of electronic devices.

Thus, in a second aspect, the present invention provides, a method for wireless charging of an electronic device, the method comprising, providing an electronic device held by a wireless charging apparatus according to the first aspect, ensuring that the antenna portion of the wireless charging apparatus is in the wireless charging position, placing the electronic device in a varying electromagnetic field whereby the wireless charging apparatus receives power from the electromagnetic field and charges the electronic device.

Embodiments of the present invention will now be described with reference to the following figures, in which: FIG. 1 shows side views of a wireless charging apparatus of the invention in the form of a removable case holding a smart phone, with a wireless charging antenna in the standby and charging modes.

FIG. 2 is a schematic side view showing the wireless charging apparatus of FIG. I in charging mode and illustrating how a user's hand is remote from the varying electromagnetic field used to wirelessly charge the device.

FIG. 3 is a schematic side and bottom plan view of the wireless charging apparatus of FIGs 1 and 2.

FIG. 4 shows side and bottom views of another embodiment of a wireless charging apparatus according to the invention attached to a smartphone.

FIG. 5 shows side and bottom views of a further embodiment of a wireless charging apparatus according to the invention attached to a smartphone.

FIG. 6 shows a schematic side view of antenna positions of a wireless charging apparatus according to the invention and a bar graph of antenna quality factor vs rotation angle.

FIG. 7 shows in (a) a schematic side view of antenna positions of a wireless charging apparatus according to the invention, in (b) a graph of impedance variation using different smartphone types at antenna position PO (standby position), and in (c) a graph of impedance variation using different smartphone types at position P3 (preferred wireless charging position).

FIG. 8 is a flow chart illustrating operation of a wireless charging apparatus according to the invention.

Figure 1 illustrates a wireless charging apparatus 2 of the invention in the form of a removable case holding an electronic device, in this case a smart phone 4. The removable case comprises a holding portion 6 for holding the smartphone 4 and an antenna portion containing a wireless charging antenna 8. The wireless charging apparatus 2 is shown in standby mode (upper drawing) and charging mode (lower drawing).

The holding portion 6 contains charging electronic and switching circuits, an external battery 14 and an internal power connector electrically connected to the control circuit and electrically connectable, in use, to the smart phone 4.

The charging antenna 8 of the antenna portion is connected to the holding portion 6 by an antenna pivot mount 10, with a rotation axis substantially parallel to, and located at the edge portion of, the short edge of the removable case. In standby mode (when the smart phone 4 is charged or using power from the external battery 14 of the removable case), the charging antenna 8 is located in the plane of the removable case and holding portion 6 and substantially flush with the removable case and the back of the smart phone 4. When in wireless charging mode, the charging antenna 8 may be pivoted away from the holding portion 6 to an angle of around 135° to the holding portion 6 / back of the smart phone 4. This angle results in an angle of the antenna portion and wireless charging antenna 8 of about 45° to the varying electromagnetic field of the charging station which provides excellent charging efficiency. The wireless charging apparatus 2 may be switched from the standby mode to the wireless charging mode by use of switching button 12.

Figure 2 illustrates schematically the wireless charging apparatus 2 in wireless charging mode showing that the rotated charging antenna 8 in charging mode acts to shield the hand of the user 22 from the varying electromagnetic charging field 16 generated by the wireless charging transmitter antenna 18 and transmitter base unit 20. Such shielding results in much improved safety.

Figure 3 shows a schematic side view of the wireless charging apparatus 2 as in the previous figures with a bottom plan view of the apparatus with the charging antenna 8 in extended wireless charging mode.

Figure 4 shows side and bottom views of another embodiment of a wireless charging apparatus 102 according to the invention attached to a smartphone 104 by holding portion 106. In this embodiment, the antenna pivot mount 110 and hence rotation axis is substantially parallel to the long edge of the smartphone 104 but the antenna pivot mount 110 is somewhat away from the long edge, inward of the edge. This allow the charging antenna 108, when in charging mode (whether or not wireless charging is actually occurring) to act as a stand for the smart phone 104. In this embodiment, the antenna pivot mount 110 extends only partly across the holding portion 106 and smartphone 104. The charging antenna 108 in charging mode (and when acting as a stand) acts to shield the user from the varying electromagnetic charging field of the charging station generated by the wireless charging transmitter antenna 18 and transmitter base unit 20. Such shielding results in much improved safety.

Figure 5 shows side and bottom views of a further embodiment of a wireless charging apparatus 202 according to the invention attached to a smartphone 204 by holding portion 206. In this embodiment (as in the embodiment of Figure 4), the antenna pivot mount 210 and hence rotation axis is substantially parallel to the long edge of the smartphone 204 with the antenna pivot mount 110 being somewhat away from the long edge, inward of the edge. This allow the charging antenna 208, when in charging mode (whether or not wireless charging is actually occurring) to act as a stand for the smart phone 204. In this embodiment, the antenna pivot mount 210 extends fully across the holding portion 206 and smartphone 204. The charging antenna 208 in charging mode (and when acting as a stand) acts to shield the user from the varying electromagnetic charging field of the charging station generated by the wireless charging transmitter antenna 18 and transmitter base unit 20. Such shielding results in much improved safety.

Figure 6 shows a schematic side view of antenna rotation angles at positions PO (standby mode, approximately 0° to the metal frame 26 of the smartphone case), P1 (approximately 45° to the metal frame 26 of the smartphone case), P2 (approximately perpendicular to the metal frame 26 of the smartphone case), P3 ( approximately 135° to the metal frame 26 of the smartphone case, thus approximately 45° to the electromagnetic field of the wireless charging transmitter (not shown), and P4 (approximately 180° to the metal frame 26 of the smartphone case) against antenna quality factor vs rotation angle. A higher quality factor means lower power losses at the antenna level and higher charging efficiency. The quality factor of the antenna is very sensitive to the metal frame. The magnetic field of the antenna generates important power losses on the metallic frames and decreases the overall system efficiency.

Figure 7 shows in (a) a schematic side view of antenna positions of a wireless charging apparatus according to the invention, in (b) a graph of impedance variation using different smartphone types at antenna position PO (standby position), and in (c) a graph of impedance variation using different smartphone types at position P3 (preferred wireless charging position). The impedance matching depends on the surrounding antenna environment (mainly the Smartphone type). Thus, a generic matching circuit cannot be used for all smartphones to obtain the same charging performance. The figure shows the expected impedance variation using different smartphones at PO and P3. A generic electronic circuit could be used at P3 (low impedance variation). However, at PO a specific matching circuit for each smartphone type is needed in order to achieve an acceptable system efficiency.

Figure 9 is a flow chart illustrating the charging protocol for the wireless charging apparatus.

Reference Numerals 2 wireless charging apparatus 4 smartphone 6 holding portion 8 charging antenna 10 antenna pivot mount 12 switching button 14 battery

16 electromagnetic charging field

18 transmitter antenna transmitter base unit 22 user's hand 24 antenna positions 26 metal frame 102 wireless charging apparatus 104 smartphone 106 holding portion 108 charging antenna antenna pivot mount 202 wireless charging apparatus 204 smartphone 206 holding portion 208 charging antenna 210 antenna pivot mount.

Claims

Claims 1. Wireless charging apparatus, the apparatus comprising a removable case for holding an electronic device, the removable case having a holding portion for holding the electronic device and comprising: a) a control circuit, b) an antenna portion containing a wireless charging antenna, the antenna portion being movably mounted on the removable case so that it is movable between a standby position and a wireless charging position where the antenna is positioned to at a transverse angle to the holding portion, the wireless charging antenna being electrically connected to the control circuit, c) an external power connector electrically connected to the control circuit, d) a battery electrically connected to the control circuit, and e) an internal power connector electrically connected to the control circuit and electrically connectable, in use, to the electronic device.
2. Wireless charging apparatus as claimed in claim I, further comprising an electronic device in the removable case, the internal power connector being electrically connected to the electronic device.
3. Wireless charging apparatus as claimed in either claim I or claim 2, wherein the electronic device is a mobile electronic device, optionally selected from a smartphone, a tablet computer, and a laptop computer.
4. Wireless charging apparatus as claimed in any one of the preceding claims, wherein the control circuit controls the power management of the apparatus and switching of the wireless charging antenna, the external power connector, the battery, and the internal power connector.
5. Wireless charging apparatus as claimed in any one of the preceding claims, wherein the control circuit controls the charging priority management of the apparatus.
6. Wireless charging apparatus as claimed in claim 5, wherein the charging priority of the apparatus is in the standby mode when the antenna portion is in the standby position and is in the wireless charging mode when the antenna portion is in the wireless charging position.
7. Wireless charging apparatus as claimed in claim 6, wherein the charging priority of the apparatus in standby mode is external power to the internal power connector, and when the internal power connector indicates the electronic device is fully charged, external power to the battery.
8. Wireless charging apparatus as claimed in claim 6, wherein the charging priority of the apparatus in wireless charging mode is external power to the internal power connector, and when there is no external power supply, wireless charging from the wireless charging antenna to the internal power connector, and when the internal power connector indicates the electronic device is fully charged, wireless charging from the wireless charging antenna to the battery.
9. Wireless charging apparatus as claimed in any one of the preceding claims, wherein the wireless charging antenna comprises a 2D or 3D antenna.
10. Wireless charging apparatus as claimed in any one of the preceding claims, wherein the antenna portion is pivotably mounted on a pivot on the removable case so that it is able to pivot between a standby position and a wireless charging position where the antenna is positioned at a transverse angle, preferably at an oblique angle, to the holding portion.
11. Wireless charging apparatus as claimed in any one of the preceding claims, wherein the transverse angle is in the range 10° to 350°, preferably in the range 45° to 315°, more preferably in the range 85° to 275°, most preferably 90° to 270°.
12. Wireless charging apparatus as claimed in any one of the preceding claims, wherein the wireless antenna is of size in the range 10 mm to 55 mm.
13. Wireless charging apparatus as claimed in any one of the preceding claims, wherein in the standby position the antenna portion is substantially co-planar with the holding portion
14. Wireless charging apparatus as claimed in any one of the preceding claims 10 to 13, wherein the removable case has a long edge and a short edge and the pivot is substantially parallel to the long edge of the removable case.
15. Wireless charging apparatus as claimed in any one of the preceding claims 10 to 13, wherein the removable case has a long edge and a short edge and the pivot is substantially parallel to the short edge of the removable case.
16. Wireless charging apparatus as claimed in any one of the preceding claims 10 to 15, wherein the pivot is located in the edge portion of the removable case.
17. Wireless charging apparatus as claimed in any one of the preceding claims 10 to 15, wherein the pivot is located inward of the edge portion of the removable case.
18. A method for wireless charging of an electronic device, the method comprising, providing an electronic device held by a wireless charging apparatus as claimed in any one of claims 1 to 17, ensuring that the antenna portion of the wireless charging apparatus is in the wireless charging position, placing the electronic device in a varying electromagnetic field whereby the wireless charging apparatus receives power from the electromagnetic field and charges the electronic device.