Watch quick-charging wireless charger

Abstract

The utility model relates to a wireless charger for quickly charging a watch. According to the quick-charging wireless charger for the watch, the radiation absorption device is arranged between the transmitting circuit and the receiving coil, and the radiation absorption device generates a negative magnetic field according to an induced parasitic magnetic field to offset the parasitic magnetic field, so that the radiation interference of EMC (Electro Magnetic Compatibility) is reduced; meanwhile, the low-frequency MOS tube is adopted to build the full-bridge switching circuit, the two ends of the transmitting coil are electrically connected with the common-mode inductors, and then the two ends of the transmitting coil are electrically connected with the capacitive filters, so that the wireless charging module adopting the low-frequency MOS tube transmitting circuit can prevent radiation interference and suppress conducted interference. Therefore, on the basis of meeting the working frequency requirement of the charging standard Qi2 and meeting the EMC requirement, the circuit setting cost is greatly reduced, and the quick charging experience requirement of a user is met.

Description

Technical Field

[0001] This utility model relates to the field of wireless charging for watches, and in particular to a fast wireless charger for watches. Background Technology

[0002] Wireless charging technology is a technology that uses electromagnetic fields to transfer energy, allowing electronic devices to charge at distances of several centimeters or even more without a physical connection. Because it eliminates the need for cables, it avoids tangled and messy charging wires, resulting in cleaner designs and improved aesthetics in home and office environments. Furthermore, the elimination of plugging and unplugging reduces the risk of cable wear and damage, enhancing charging safety. Therefore, it offers advantages such as convenience, flexibility, durability, safety, and aesthetics. This technology has been widely applied in consumer electronics, medical devices, electric vehicles, and home furnishings, particularly in consumer electronics products such as smartphones, smartwatches, and headphones.

[0003] In 2023, the Wireless Power Consortium (WPC) launched the updated wireless charging standard Qi2, which requires wireless chargers to operate at a frequency of 360kHz. To meet this operating frequency, ensure power conversion efficiency, and reduce electromagnetic interference, the switching frequency of the MOSFETs in the charging circuit must match the charger's operating frequency. For example, to achieve 5W fast charging for a smartwatch, the switching frequency of the MOSFETs used must reach 1.78MHz to meet the operating frequency requirement without causing EMC issues. EMC (Electromagnetic Compatibility) refers to the ability of electronic devices to operate normally in an electromagnetic environment without interfering with other surrounding devices, while also being unaffected by the surrounding electromagnetic environment.

[0004] However, existing low-frequency MOSFETs have a switching frequency of less than 1MHz. If a wireless charger using this MOSFET outputs 5W, the MOSFET's switching speed cannot keep up. Its parasitic capacitance causes additional charging and discharging current during the switching process. When the frequency of this charging and discharging current forms a specific ratio with the frequency of the alternating current, high-frequency harmonics are generated. These high-frequency harmonics induce parasitic magnetic fields in the alternating magnetic field, leading to increased coil radiation and failure to meet national EMC safety regulations. To avoid EMC issues, wireless chargers using this MOSFET can only reduce the charging power to 2.5W to meet the operating frequency requirements, resulting in a poor wireless charging experience. Using MOSFETs with a switching frequency higher than 1.78MHz in a wireless charger would be significantly more expensive; for example, gallium nitride MOSFETs cost several times more than low-frequency MOSFETs.

[0005] Therefore, it is evident that existing wireless chargers for watches, when using low-cost, low-frequency MOSFETs for fast charging, cannot simultaneously meet the operating frequency requirements of the Qi2 charging standard and comply with EMC requirements. Utility Model Content

[0006] Therefore, the purpose of this utility model is to provide a fast wireless charger for watches.

[0007] A wireless fast charger for watches, comprising:

[0008] A shell frame;

[0009] and the circuit board mounted on the housing frame;

[0010] A wireless charging module includes a transmitting coil mounted on a housing frame and a transmitting circuit mounted on a circuit board. The transmitting coil is electrically connected to the transmitting circuit. The transmitting circuit includes a DC power input terminal electrically connected to the power supply terminal of the circuit board, a full-bridge switching circuit electrically connected to the DC power input terminal, and a common-mode inductor and capacitor filter electrically connected to the full-bridge switching circuit. The common-mode inductor is electrically connected to both ends of the transmitting coil, and the capacitor filter is electrically connected to both ends of the transmitting coil.

[0011] A radiation absorption device is mounted on the emitting surface of the emitting coil and connected to the grounding terminal.

[0012] Furthermore, the radiation absorbing device includes a connecting region and a patterned absorbing region connected to one end of the connecting region; the other end of the connecting region is connected to a ground terminal; the patterned area of ​​the patterned absorbing region can cover the emitting surface of the emitting coil.

[0013] Furthermore, the graphic absorption area includes several parallel and spaced absorption stripes, one end of each absorption stripe being connected to the connecting area.

[0014] Furthermore, the number of the connecting regions is set to multiple, and each connecting region is connected to several absorption stripes at one end.

[0015] Further, the width of the connecting area ranges from 0.5mm to 2.0mm; and / or, the width of the absorption stripes ranges from 0.1mm to 0.5mm; and / or, the spacing between the absorption stripes ranges from 0.1mm to 0.5mm.

[0016] Furthermore, the connecting area and the pattern absorption area are made of any one of copper, gold, silver, or aluminum.

[0017] Furthermore, it also includes a housing that covers the housing frame, and the radiation absorbing device is attached to the inner or outer wall of the housing, with the attachment position facing the emitting surface of the emitting coil.

[0018] Furthermore, the full-bridge switching circuit includes a first half-bridge and a second half-bridge, which are electrically connected to the DC power input terminal; the first half-bridge includes a first low-frequency MOSFET and a second low-frequency MOSFET connected in sequence, and the second half-bridge includes a third low-frequency MOSFET and a fourth low-frequency MOSFET connected in sequence, wherein the first low-frequency MOSFET, the second low-frequency MOSFET, the third low-frequency MOSFET and the fourth low-frequency MOSFET are N-type MOSFETs.

[0019] Furthermore, the switching frequencies of the first low-frequency MOSFET, the second low-frequency MOSFET, the third low-frequency MOSFET, and the fourth low-frequency MOSFET are less than or equal to 1MHz.

[0020] Furthermore, the common-mode inductor includes a first coil and a second coil; one end of the first coil is electrically connected to the source of the first low-frequency MOSFET and the drain of the second low-frequency MOSFET, and the other end of the first coil is electrically connected to one end of the transmitting coil; one end of the second coil is electrically connected to the source of the third low-frequency MOSFET and the drain of the fourth low-frequency MOSFET, and the other end of the second coil is electrically connected to the other end of the transmitting coil.

[0021] The capacitor filter includes a first filter capacitor and a second filter capacitor. The two ends of the transmitting coil are electrically connected to one end of the first filter capacitor and one end of the second filter capacitor, respectively. The other ends of the first filter capacitor and the second filter capacitor are both grounded.

[0022] Furthermore, the first coil and the second coil are symmetrically wound on a toroidal magnetic core.

[0023] Furthermore, the transmitting circuit also includes a resonant capacitor, one end of the second coil is electrically connected to one end of the resonant capacitor, and the other end of the resonant capacitor is electrically connected to the source of the third low-frequency MOS transistor and the drain of the fourth low-frequency MOS transistor.

[0024] Compared to existing technologies, this invention provides a wireless fast charger for watches that reduces EMC interference by: 1) incorporating a radiation absorption device between the transmitting circuit and the receiving coil; 2) generating a negative magnetic field to cancel out the induced parasitic magnetic field; and 3) employing a low-frequency MOSFET to build a full-bridge switching circuit, connecting a common-mode inductor to both ends of the transmitting coil, and then connecting a capacitor filter to both ends of the transmitting coil. This allows the wireless charging module using the low-frequency MOSFET transmitting circuit to both prevent radiation interference and suppress conducted interference. This enables the wireless fast charger for watches to significantly reduce circuit setup costs while meeting the operating frequency requirements of the Qi2 charging standard and complying with EMC requirements, and simultaneously satisfying users' demands for a fast charging experience.

[0025] To better understand and implement this invention, the following detailed description is provided in conjunction with the accompanying drawings. Attached Figure Description

[0026] Figure 1 A schematic diagram of the appearance of a wireless fast charger for a watch, according to one embodiment;

[0027] Figure 2 A schematic diagram of a wireless fast charger for a smartwatch, according to one embodiment;

[0028] Figure 3 for Figure 2 The diagram shows the relative positions of the radiation absorption device and the wireless charging module.

[0029] Figure 4 A circuit diagram of a transmitting circuit according to one embodiment;

[0030] Figure 5 This is a schematic diagram of the structure of a radiation absorption device according to an embodiment. Detailed Implementation

[0031] To address the issue that existing wireless chargers for watches, which use low-cost, low-frequency MOSFETs for fast charging, cannot simultaneously meet the operating frequency requirements of the Qi2 charging standard and comply with EMC requirements, this invention proposes a wireless fast charger for watches. This wireless fast charger includes a wireless charging module and a radiation absorption device disposed on the charging area corresponding to the wireless charging module. The wireless charging module includes a transmitting circuit, which uses four low-frequency MOSFETs to form a full-bridge circuit. A common-mode inductor is electrically connected across the transmitting coil, and a capacitor filter is electrically connected across the transmitting coil. Through the designed transmitting circuit and radiation absorption device, this wireless charger for watches, using low-cost, low-frequency MOSFETs, can simultaneously meet the operating frequency requirements of the Qi2 charging standard and comply with EMC requirements during fast charging, effectively balancing the production cost of the wireless charger with the user's wireless fast charging experience.

[0032] Please see Figure 1 and Figure 2 The watch fast charging wireless charger of this utility model includes a shell 100, a shell frame 1 disposed inside the shell 100, a circuit board 2 and a wireless charging module 3 disposed on the shell frame 1, a radiation absorption device 4 disposed on the charging area corresponding to the wireless charging module 3, and a power supply terminal 5 disposed on the circuit board 2; the wireless charging module 3 is electrically connected to the power supply terminal 5, and the radiation absorption device 4 is connected to the ground terminal of the circuit board 2.

[0033] The wireless charging module 3 includes a transmitting coil 31 mounted on the housing frame 1, and a transmitting circuit 32, a signal module (not shown), and a control module (not shown) mounted on the circuit board 2 and electrically connected to the transmitting coil 31. The transmitting circuit 32 converts direct current into high-frequency alternating current to supply the transmitting coil 31, causing the transmitting coil 31 to perform electromagnetic conversion and generate an alternating magnetic field. The signal module uses ASK modulation technology to enable communication between the wireless charger and the watch to be charged. The control module is used to control the driving of the transmitting circuit 32 according to the information transmitted by the signal module.

[0034] Please see Figure 3 The transmitting coil 31 is configured as a ring winding structure and is installed inside a circular housing 311, which provides physical protection and stability for the transmitting coil 31. The transmitting coil 31 has a transmitting surface that faces the charging area and is opposite to the receiving surface of the receiving coil of the device to be charged. The radiation absorption device 4 is installed on the transmitting surface of the transmitting coil 31.

[0035] Please see Figure 3 and Figure 4 The transmitting circuit 32 of this invention includes a DC power input terminal 321 electrically connected to the power supply terminal 5, a full-bridge switching circuit 322, a resonant capacitor 324, a common-mode inductor 325, and a capacitor filter 326. The full-bridge switching circuit 322 receives an external DC voltage signal through the DC power input terminal 321 and controls the conduction and cutoff of a low-frequency switch according to a drive signal to output an alternating voltage signal of a specific frequency, thereby driving the transmitting coil 31 to operate at the resonant frequency. This causes the inductor coil to generate an alternating magnetic field, achieving wireless energy transmission. The common-mode inductor 325 suppresses high-frequency harmonic voltage or current generated by the full-bridge switching circuit 322 from being input to the transmitting coil 31. The capacitor filter 326 filters out common-mode noise. The common-mode inductor 325 and the capacitor filter 326 work together to suppress the conducted interference of high-frequency harmonics, reducing radiated interference to EMC. The resonant capacitor 324 is used to adjust the resonant frequency of the circuit.

[0036] The DC power input terminal 321 provides power to the entire transmitting circuit 32. It includes a positive terminal A and a negative terminal B. The positive terminal A represents the positive terminal of the DC power supply and is used to connect to the positive terminal of the power supply terminal 5. The negative terminal B represents the negative terminal of the DC power supply and is used to connect to the negative terminal of the power supply terminal 5.

[0037] The full-bridge switching circuit 322 includes four low-frequency MOSFETs, namely the first low-frequency MOSFET 3221, the second low-frequency MOSFET 3222, the third low-frequency MOSFET 3223 and the fourth low-frequency MOSFET 3224. The four low-frequency MOSFETs are connected in a full-bridge configuration and alternately turn on and off to generate a high-frequency pulse width modulation signal.

[0038] Specifically, the first low-frequency MOSFET 3221 and the second low-frequency MOSFET 3222 are electrically connected to form a first half-bridge, and the third low-frequency MOSFET 123 and the fourth low-frequency MOSFET are electrically connected to form a second half-bridge. The first low-frequency MOSFET 121, the second low-frequency MOSFET 122, the third low-frequency MOSFET 123 and the fourth low-frequency MOSFET 124 are N-type MOSFETs, and preferably N-type MOSFETs with a switching frequency of less than or equal to 1MHz.

[0039] The electrical connections of the first half-bridge are as follows.

[0040] The drain of the first low-frequency MOSFET 3221 is electrically connected to the positive terminal A, its source is electrically connected to the drain of the second low-frequency MOSFET 3222, and its gate is electrically connected to its drain; the source of the second low-frequency MOSFET 3222 is electrically connected to the negative terminal B, and its gate is electrically connected to its drain.

[0041] The electrical connections of the second half-bridge are as follows.

[0042] The drain of the third low-frequency MOSFET 3223 is electrically connected to the positive terminal A, its source is electrically connected to the drain of the fourth low-frequency MOSFET 3224, and its gate is electrically connected to its drain; the source of the fourth low-frequency MOSFET 3224 is electrically connected to the negative terminal B, and its gate is electrically connected to its drain.

[0043] The common-mode inductor 325 includes a first coil 3251 and a second coil 3252. The first coil 3251 and the second coil 3252 are symmetrically wound on a toroidal magnetic core. The symmetrical winding of the coils can enhance the suppression of common-mode current and reduce the influence on differential-mode signals.

[0044] Specifically, one coil is connected between the transmitting coil 31 and the resonant capacitor 324, and the corresponding other coil is connected between the transmitting coil 31 and the full-bridge switching circuit 322.

[0045] In one embodiment, the electrical connections of the first coil 3251 and the second coil 3252 with the full-bridge switching circuit 322, the transmitting coil 31, and the resonant capacitor 324 are as follows:

[0046] One end of the first coil 3251 is electrically connected to the source of the first low-frequency MOSFET 3221 and the drain of the second low-frequency MOSFET 3222. The other end of the first coil 3251 is electrically connected to one end of the transmitting coil 31. One end of the second coil 3252 is electrically connected to the other end of the transmitting coil 31. The other end of the second coil 3252 is electrically connected to one end of the resonant capacitor 324 and indirectly connected to the source of the third low-frequency MOSFET 3223 and the drain of the fourth low-frequency MOSFET 3224 through the resonant capacitor 324.

[0047] In another embodiment, the electrical connections of the first coil 3251 and the second coil 3252 with the full-bridge switching circuit 322, the transmitting coil 31, and the resonant capacitor 324 are as follows:

[0048] One end of the first coil 3251 is connected to one end of the resonant capacitor 324, and indirectly connected to the source of the first low-frequency MOSFET 3221 and the drain of the second low-frequency MOSFET 3222 through the resonant capacitor 324. The other end of the first coil 3251 is connected to one end of the transmitting coil 31. One end of the second coil 3252 is connected to the other end of the transmitting coil 31, and the other end of the second coil 3252 is connected to the source of the third low-frequency MOSFET 3223 and the drain of the fourth low-frequency MOSFET 3224.

[0049] The capacitor filter 326 includes a first filter capacitor 3261 and a second filter capacitor 3262, which are connected in parallel across the two ends of the transmitting coil 31.

[0050] Specifically, one end of the first filter capacitor 3261 is electrically connected to one end of the transmitting coil 31, and the other end of the first filter capacitor 3261 is electrically connected to the negative terminal B; one end of the second filter capacitor 3262 is electrically connected to the other end of the transmitting coil 31, and the other end of the second filter capacitor 3262 is electrically connected to the negative terminal B. To obtain better filtering effect, the first filter capacitor 3261 and the second filter capacitor 3262 are grounded, such as by being electrically connected to the ground terminal of the circuit board.

[0051] The first half-bridge and the second half-bridge are electrically connected to the transmitting coil 31, the resonant capacitor 324 and the common mode inductor 325 to form an H-type full-bridge connection. According to the driving signal, when the first low-frequency MOSFET 3221 and the fourth low-frequency MOSFET 3224 are turned on, the second low-frequency MOSFET 3222 and the third low-frequency MOSFET 3223 are turned off. The current flows from the DC power supply through the first low-frequency MOSFET 3221 to the transmitting coil 31, the resonant capacitor 324 and the common-mode inductor 325, and then returns to the DC power supply through the fourth low-frequency MOSFET 3224, forming a closed loop. At this time, the transmitting coil 31 generates a forward current. When the second low-frequency MOSFET 3222 and the third low-frequency MOSFET 3223 are turned on, the first low-frequency MOSFET 3221 and the fourth low-frequency MOSFET 3224 are turned off. The current flows from the DC power supply through the third low-frequency MOSFET 3223 to the transmitting coil 31, the resonant capacitor 324 and the common-mode inductor 325, and then returns to the DC power supply through the second low-frequency MOSFET 3222, forming a closed loop. At this time, the transmitting coil 31 generates a reverse current.

[0052] Please see Figure 3 and Figure 5 The radiation absorption device 4 is installed on the charging area corresponding to the transmitting coil 31 and covers the transmitting coil 31. The radiation absorption device 4 generates a negative magnetic field based on the induced parasitic magnetic field to cancel the parasitic magnetic field, further reducing EMC radiation interference. In specific implementation, the radiation absorption device 4 can be set on the circular outer shell of the transmitting coil 31, or it can be set on the inner or outer wall of the charging area corresponding to the outer shell 100. The setting method can be pasted or integrally formed on the outer shell 100. As long as the radiation absorption device 4 is located between the transmitting coil 31 and the receiving coil, this application does not impose any restrictions.

[0053] Please see Figure 5 The radiation absorbing device 4 includes a connecting region 41 and a patterned absorption region 42 connected to one end of the connecting region 41. The patterned absorption region 42 includes a plurality of parallel and spaced absorption stripes 422, one end of each absorption stripe 422 being connected to the connecting region 41.

[0054] The radiation absorption device 4 is preferably in the form of an FPC (Flexible Printed Circuit). The FPC is preferably attached to the outer surface of the transmitting coil 31, but it can also be attached to the inner or outer side of the corresponding charging area of ​​the watch fast charging wireless charger housing 100, or fixed to the inner side of the corresponding charging area of ​​the watch fast charging wireless charger housing 100. When the radiation absorption device 4 covers the transmitting coil 31, a parasitic induced current is generated in the pattern absorption area under the action of the parasitic magnetic field. This parasitic induced current generates a negative magnetic field around the pattern absorption area, which cancels out the parasitic magnetic field. That is, the radiation energy generated by the parasitic magnetic field is converted into electrical energy and absorbed in the pattern absorption area, further reducing EMC radiation interference.

[0055] To prevent the current generated in the pattern absorption area from forming eddy currents and causing overheating, in some embodiments, the other end of the connection area 41 that is not connected to the pattern absorption area 42 is grounded to conduct away the parasitic induced current.

[0056] To improve the reliability of the radiation absorption device, in some embodiments, the number of connection areas 41 can be set to multiple as needed, and each connection area 41 can be connected to several absorption stripes 422 at one end, and multiple connection areas 41 are grounded.

[0057] To avoid changes in the magnetic field caused by sudden changes in current, in some embodiments, the connecting region 41 is preferably of a uniform shape with a width ranging from 0.5 mm to 2.0 mm, preferably 1.0 mm; furthermore, the width of the plurality of absorption stripes 422 is consistent, with the width ranging from 0.1 mm to 0.5 mm, preferably 0.2 mm.

[0058] To avoid short circuits and eddy currents caused by small spacing between several patterned absorption areas, in some embodiments, the spacing between two adjacent absorption stripes 422 is in the range of 0.1mm-0.5mm, preferably 0.2mm.

[0059] To avoid mutual interference between the magnetic fields generated by two adjacent pattern absorption regions, in some embodiments, the width and spacing of two adjacent absorption stripes 422 are equal.

[0060] Since the parasitic magnetic field is generated by high-frequency harmonics, even if the connection region 41 conducts away the parasitic induced current, the pattern absorption region 42 itself will still generate a certain amount of eddy current. To further prevent the formation of eddy currents and the resulting heat generation, in some embodiments, to control the volume of the pattern absorption region 42, the shielding coverage area of ​​the pattern absorption region 42 is matched with the area of ​​the transmitting coil 31. Preferably, the area of ​​the pattern absorption region 42 is greater than or equal to the area of ​​the transmitting coil 31. When the diameter of the transmitting coil in the watch wireless charger is 24mm, the diameter of the pattern absorption region 42 is set between 24mm and 26mm, and the corresponding diameter of the radiation absorption device 4 is between 25mm and 28mm.

[0061] Since the parasitic magnetic field is generated by high-frequency harmonics, if the conductivity of the pattern absorption region 42 is high, the pattern absorption region 42 is a conductor for the parasitic magnetic field and an insulator for the alternating magnetic field. Therefore, in some embodiments, the pattern absorption region 42 is made of a material with extremely high conductivity to achieve the effect of not affecting the passage of the alternating magnetic field and not affecting wireless charging. For example, metals such as copper, gold, silver, and aluminum are used to make the pattern absorption region 42 and the connection region 41.

[0062] To reduce losses, in some embodiments, the absorption stripes 422 are preferably set as parallel straight line segments; the shape of the absorption stripes 422 can also be non-straight line segments, such as arc-shaped line segments or wavy line segments.

[0063] The power supply terminal 5 can be an electrical connector directly mounted on the circuit board 2, or it can be a charging cable electrically connected to the circuit board 2.

[0064] The terminology used in the embodiments of this application is for the purpose of describing particular embodiments only and is not intended to limit the embodiments of this application. The singular forms “a,” “the,” and “the” used in the embodiments and claims of this application are also intended to include the plural forms, unless the context clearly indicates otherwise. It should also be understood that, unless otherwise stated, “a plurality” and “several” refer to two or more; “and / or” refers to and includes any or all possible combinations of one or more associated listed items; “first,” “second,” “third,” etc., are used only to distinguish and not to describe a particular order or sequence, nor should they be construed as indicating or implying relative importance. When the above description relates to drawings, unless otherwise indicated, the same numbers in different drawings represent the same or similar elements. In the description of this application, those skilled in the art can understand the specific meaning of the above terms in this application according to the specific circumstances.

[0065] The embodiments described above are merely examples of several implementations of this utility model, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the utility model patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this utility model, and this utility model also intends to include these modifications and variations.

Claims

1. A wireless fast charger for watches, characterized in that, include: A shell frame; and the circuit board mounted on the housing frame; A wireless charging module includes a transmitting coil mounted on a housing frame and a transmitting circuit mounted on a circuit board. The transmitting coil is electrically connected to the transmitting circuit. The transmitting circuit includes a DC power input terminal electrically connected to the power supply terminal of the circuit board, a full-bridge switching circuit electrically connected to the DC power input terminal, and a common-mode inductor and capacitor filter electrically connected to the full-bridge switching circuit. The common-mode inductor is electrically connected to both ends of the transmitting coil, and the capacitor filter is electrically connected to both ends of the transmitting coil. A radiation absorption device is mounted on the emitting surface of the emitting coil and connected to the grounding terminal.

2. The wireless fast charger for watches according to claim 1, characterized in that: The radiation absorption device includes a connecting region and a patterned absorption region connected to one end of the connecting region; the other end of the connecting region is connected to a ground terminal; the patterned area of ​​the patterned absorption region can cover the emitting surface of the emitting coil.

3. The wireless fast charger for watches according to claim 2, characterized in that: The graphic absorption area includes several parallel and spaced absorption stripes, one end of each absorption stripe being connected to the connecting area.

4. The wireless fast charger for watches according to claim 3, characterized in that: The number of connection regions is set to multiple, and each connection region is connected to several absorption stripes at one end.

5. The wireless fast charger for watches according to claim 3, characterized in that: The width of the connecting area is 0.5mm-2.0mm; and / or the width of the absorption stripes is 0.1mm-0.5mm; and / or the spacing between the absorption stripes is 0.1mm-0.5mm.

6. The wireless fast charger for watches according to claim 2, characterized in that: The connecting area and the graphic absorption area are made of any one of copper, gold, silver, or aluminum.

7. The wireless fast charger for watches according to claim 1, characterized in that: It also includes a housing that covers the housing frame, and the radiation absorbing device is attached to the inner or outer wall of the housing, with the attachment position facing the emitting surface of the emitting coil.

8. The wireless fast charger for watches according to any one of claims 1-7, characterized in that: The full-bridge switching circuit includes a first half-bridge and a second half-bridge, which are electrically connected to the DC power input terminal. The first half-bridge includes a first low-frequency MOSFET and a second low-frequency MOSFET connected in sequence, and the second half-bridge includes a third low-frequency MOSFET and a fourth low-frequency MOSFET connected in sequence. The first low-frequency MOSFET, the second low-frequency MOSFET, the third low-frequency MOSFET, and the fourth low-frequency MOSFET are N-type MOSFETs.

9. The wireless fast charger for watches according to claim 8, characterized in that: The switching frequencies of the first, second, third, and fourth low-frequency MOSFETs are less than or equal to 1MHz.

10. The wireless fast charger for watches according to claim 8, characterized in that: The common-mode inductor includes a first coil and a second coil; one end of the first coil is electrically connected to the source of the first low-frequency MOSFET and the drain of the second low-frequency MOSFET, and the other end of the first coil is electrically connected to one end of the transmitting coil; one end of the second coil is electrically connected to the source of the third low-frequency MOSFET and the drain of the fourth low-frequency MOSFET, and the other end of the second coil is electrically connected to the other end of the transmitting coil. The capacitor filter includes a first filter capacitor and a second filter capacitor. The two ends of the transmitting coil are electrically connected to one end of the first filter capacitor and one end of the second filter capacitor, respectively. The other ends of the first filter capacitor and the second filter capacitor are both grounded.

11. The wireless fast charger for watches according to claim 10, characterized in that: The first and second coils are symmetrically wound on a toroidal magnetic core.

12. The wireless fast charger for watches according to claim 10, characterized in that: The transmitting circuit also includes a resonant capacitor. One end of the second coil is electrically connected to one end of the resonant capacitor, and the other end of the resonant capacitor is electrically connected to the source of the third low-frequency MOS transistor and the drain of the fourth low-frequency MOS transistor.

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