CN204441452U - For NFC antenna structure and the intelligent watch of wearable device - Google Patents

Abstract

The utility model discloses an NFC antenna structure for a wearable device and a smart watch, wherein the NFC antenna structure includes an antenna radiation body, an adjustment circuit assembly, a first power feeding part and a second power feeding part; the antenna The radiating body is a single-turn metal coil; the metal coil is provided with an opening, and the opening divides the metal coil into a non-closed ring structure; the regulating circuit assembly includes a first inductor, a second inductor, and a capacitor, and the first inductor After being connected in series with the second inductance, the whole is connected in parallel with the capacitor. The utility model increases the inductance value of the radiation body as a single-turn non-closed metal coil or metal ring through the first inductance and the second inductance connected in series, increases the capacitance value of the radiation body through capacitance, and can reduce the number of turns of the metal coil The area and volume occupied by the antenna are small, and the communication quality is reliable.

Description

NFC antenna structure for wearable devices and smart watches

technical field

The utility model relates to the technical field of antennas, in particular to an NFC antenna structure for wearable devices and a smart watch.

Background technique

In recent years, wearable devices have attracted more and more attention. As an important member of wearable devices, smart watches are developing rapidly. So far, many mobile phone manufacturers (such as Apple, Motorola, and Samsung, etc.) have started to manufacture smart watches. Of course, in order to establish a wireless connection and communication with peripheral devices (such as mobile phones, etc.), the smart watch must support a certain wireless communication protocol (such as Bluetooth, etc.). On the other hand, the increasingly popular NFC communication has become a standard feature of smartphones. NFC is a non-contact identification and interconnection technology with a working frequency of 13.56MHz, which is suitable for short-distance communication in mobile phones, civilian electronics, computers and intelligent control devices. Therefore, NFC can allow consumers to easily exchange information, access content and services. There is no doubt that smart watches should support NFC communication.

Although many NFC antenna design schemes have appeared in the prior art, most of them are only suitable for application to mobile phones. The NFC antenna structure commonly used in mobile phones usually includes two parts: 1. The antenna radiation body, specifically a 3-5 turn FPC copper coil; 2. Ferrite, which isolates the copper coil from metal objects (such as batteries and other metal objects) . Generally speaking, the NFC antenna is a loop antenna, which is usually set horizontally and fixed on the back of the mobile phone. The above-mentioned NFC antenna structure is obviously not suitable for wearable devices such as watches. This is because when people wear watches, if the NFC antenna is placed on the back of the watch according to the design of the mobile phone, it is difficult to realize NFC antenna communication at this time, which seriously affects Communication effect of NFC antenna. In other words, a suitable NFC antenna solution for a watch should allow the antenna to radiate outward from the front of the watch. Therefore, in order to meet the rapid development requirements of wearable devices such as smart watches, it is very urgent and necessary to design a dedicated NFC antenna.

Utility model content

The technical problem to be solved by the utility model is to provide an NFC antenna structure and a smart watch for wearable devices with simple structure and good communication quality.

In order to solve the above technical problems, the technical solution adopted by the utility model is to provide a NFC antenna structure for wearable devices, including the antenna radiation main body, the adjustment circuit component composed of patch inductors and capacitors, the first feeder Electric part and second power feeding part;

The antenna radiating body is a single-turn metal coil; the metal coil is provided with an opening, and the opening divides the metal coil into a non-closed ring structure;

The regulating circuit assembly includes a first inductance, a second inductance and a capacitor, one end of the first inductance is connected to the first feeder, the other end of the first inductance is connected to one end of the metal coil; the second inductance One end is connected to the second power feeding part, and the other end of the second inductance is connected to the other end of the metal coil; one end of the capacitor is connected to the junction of the first inductance and the first power feeding part, and the other end is connected to the second On the junction where the inductor is connected to the second power feeding part.

In order to solve the above technical problems, another technical solution adopted by the utility model is to provide a smart watch, including a watch cover, a frame, a chip assembly, a battery, a back cover, a PCB board, an antenna assembly, and a watch strap. , the frame and the back cover form an accommodating space, the chip assembly, the PCB board, the antenna assembly and the battery are located in the accommodating space, the watch strap is arranged on the frame, the antenna assembly is an NFC antenna assembly, and the NFC antenna The assembly includes an antenna radiating body, an adjustment circuit assembly, a first feeding part and a second feeding part;

The antenna radiating body is a single-turn metal coil surrounding the PCB board and positioned on the inner surface of the frame, the metal coil is provided with an opening, and the opening divides the metal coil into a non-closed ring structure;

The regulating circuit assembly includes a first inductance, a second inductance and a capacitor, one end of the first inductance is connected to the first feeder, the other end of the first inductance is connected to one end of the metal coil; the second inductance One end is connected to the second power feeding part, and the other end of the second inductance is connected to the other end of the metal coil; one end of the capacitor is connected to the junction of the first inductance and the first power feeding part, and the other end is connected to the second On the junction where the inductor is connected to the second power feeding part.

In order to solve the above technical problems, another technical solution adopted by the utility model is to provide a smart watch, including a watch cover, a frame, a chip assembly, a battery, a back cover, a PCB board, an antenna assembly, and a watch strap. , the frame and the back cover form an accommodating space, the chip assembly, the PCB board and the battery are located in the accommodating space, the watch strap is arranged on the frame, and also includes a metal ring surrounding and closely attached to the outer surface of the frame, so The antenna assembly is an NFC antenna assembly, and the NFC antenna assembly includes an antenna radiation body, an adjustment circuit assembly, a first feeder and a second feeder;

The radiating body of the antenna is a metal ring, the metal ring is provided with an opening, and the opening divides the metal ring into a non-closed ring structure;

The regulating circuit assembly includes a first inductance, a second inductance and a capacitor, one end of the first inductance is connected to the first feeder, the other end of the first inductance is connected to one end of the metal ring; the second inductance One end is connected to the second power feeding part, and the other end of the second inductance is connected to the other end of the metal ring; one end of the capacitor is connected to the junction of the first inductance and the first power feeding part, and the other end is connected to the second On the junction where the inductor is connected to the second power feeding part.

The beneficial effects of the utility model are: different from the problem in the prior art that the NFC antenna communication is difficult to realize if the NFC antenna is located on the back of the watch according to the design scheme of the mobile phone, the utility model provides a wearable device The unique NFC antenna structure does not need to add ferrite, which can simplify the antenna structure; and the antenna radiation body adopts a single non-closed metal coil or metal ring design, the structure is simpler, the occupied area and space are small, and it is conducive to thinner and miniaturized Design; the first inductance and the second inductance connected in series can increase the inductance value of the radiator as a single non-closed metal coil or metal ring, and the capacitance value of the radiator can be increased through the capacitor, and the number of turns of the metal coil can be reduced to a single turns, the area and volume occupied by the antenna are smaller, the structure is simpler, and the communication quality is reliable.

Description of drawings

Fig. 1 is the utility model NFC antenna structural representation;

Fig. 2 is the magnetic field distribution schematic diagram of the utility model NFC antenna structure;

Fig. 3 is the equivalent circuit diagram of typical NFC antenna;

Fig. 4 is the Smith diagram of the NFC antenna that does not add inductance and capacitance in the utility model;

Fig. 5 is the Smith curve diagram of the NFC antenna after only adding two inductances in the utility model;

Fig. 6 is the Smith curve of the NFC antenna after adding two inductors and capacitors in the utility model;

Fig. 7 is a schematic structural diagram of an embodiment of the smart watch of the present invention;

Fig. 8 is a schematic structural view of another embodiment of the smart watch of the present invention;

FIG. 9 is a schematic diagram of the internal structure of the NFC antenna shown in FIG. 8 .

Label description:

1. Metal coil/metal ring; 2. PCB board; 3. Frame; 4. Cover;

5. Chip components; 6. Back cover; 7. Watch strap; 8. Switch button;

9. Magnetic field; 11. First feeder; 12. Second feeder; 13. First inductance;

14. Second inductance; 15. Capacitance; 16. Opening.

Detailed ways

In order to describe the technical content, the achieved purpose and the effect of the present utility model in detail, the following will be described in conjunction with the embodiments and accompanying drawings.

The most critical idea of the utility model is that: the antenna radiation body of the NFC antenna assembly adopts a single-turn non-closed metal coil or metal ring design, the structure is simpler, the occupied area and space are small, and it is beneficial to the thinner and miniaturized design; The first inductance and the second inductance connected can increase the inductance value of the antenna radiator as a single-turn non-closed metal coil or metal ring, and the capacitance value of the antenna radiator can be increased through the capacitance, and the number of turns of the metal coil can be reduced to a single turn , the area and volume occupied by the antenna are smaller, the structure is simpler, and it is suitable for wearable devices such as smart watches, and the communication quality is reliable.

Please refer to FIG. 1 to FIG. 2, a NFC antenna structure for wearable devices, including a PCB board 2 and an NFC antenna assembly, the NFC antenna assembly includes an antenna radiation body, an adjustment for changing the inductance value and capacitance value of the radiation body circuit components, the first power feeding part 11 and the second power feeding part 12;

The antenna radiating body is a single-turn metal coil 1; the metal coil 1 is provided with an opening 16, and the opening 16 divides the metal coil 1 into a non-closed ring structure;

The regulating circuit assembly includes a first inductance 13, a second inductance 14 and a capacitor 15, one end of the first inductance 13 is connected to the first feeder 11, and the other end of the first inductance 13 is connected to one end of the metal coil 1 ; One end of the second inductance 14 is connected to the second feeder 12, and the other end of the second inductance 14 is connected to the other end of the metal coil 1; one end of the capacitor 15 is connected between the first inductance 13 and the first feeder. The contact point where the electrical part 11 is connected, and the other end is connected to the contact point where the second inductor 14 is connected to the second power feeding part 12 . The inductors and capacitors mentioned above are chip inductors and capacitors.

In addition, the first inductance and the second inductance are only to increase the inductance value of the NFC antenna based on a single-turn metal coil, and the form of connecting the inductance is to distribute the first inductance and the second inductance in a balanced manner at both ends of the metal ring feed. However, it should be pointed out that the connection mode of the inductance is not unique. For example, an inductance equivalent to the sum of the first inductance and the second inductance can also be added to one end of the feed (at this time, the inductance of the feed end without the inductance will be determined by A part of the metal coil conductor is replaced), and the connection method of the capacitor remains unchanged, or across the two feed points.

Referring to FIG. 2, FIG. 2 is a schematic diagram of the electromagnetic distribution of the NFC antenna structure. It can be seen from FIG. 2 that the magnetic field 9 generated by the antenna radiation body in the NFC antenna assembly surrounds the metal coil.

All NFC antennas can be equivalent to the circuit diagram shown in FIG. 3 , the circuit diagram includes a capacitor Ca, a resistor Ra and an inductor La, and the resistor Ra and the inductor La are connected in series and then connected in parallel with the capacitor Ca. According to the requirements of the NFC antenna, the values of the inductance La, the capacitance Ca and the resistance Ra are 0.3-3uH, 3-30pF and 0.3-8Ω respectively. Because the NFC antenna can be replaced by the equivalent circuit shown in Figure 3, when the inductance and capacitance of the NFC antenna itself are too small to meet the above inductance and capacitance requirements, we can add additional inductance and capacitance to the NFC antenna , and this is also one of the main principles that the utility model can be realized. In addition, the inherent self-resonant frequency of the antenna itself determined by the capacitance and inductance should be greater than twice the operating frequency (13.56MHz) of the NFC antenna. In order to meet the requirements of the inductance, the length of the antenna must be long enough, because the inductance is proportional to the length of the antenna. Limited by the size of portable devices, the size of a general NFC antenna is 40mm*40mm. The copper coil in a traditional NFC antenna needs to be wound 3-5 times, and it is mostly used in mobile phones and is not suitable for wearable devices. The NFC antenna structure of this solution can realize the communication of wearable devices with only one coil of copper coil.

It can be seen from the above description that the beneficial effect of the utility model is that it is different from the problem in the prior art that the NFC antenna communication is difficult to realize if the NFC antenna is located on the back of the watch according to the design scheme of the mobile phone. The NFC antenna structure for wearable devices does not need to add ferrite, which can simplify the antenna structure; and the antenna radiation body is designed with a single-turn non-closed metal coil or metal ring, which has a simpler structure and occupies less area and space, which is beneficial Thinner and miniaturized design; the inductance and capacitance generated by a single coil generally cannot meet the requirements of the NFC antenna, but the insufficiency of the inductance and capacitance can be corrected by the adjustment circuit, specifically using the first inductance 13 connected in series and the second inductance 14 to increase the inductance value of the radiator as a single-turn non-closed metal coil or metal ring, and increase the capacitance value of the radiator through capacitance, so the number of turns of the metal coil can be reduced to a single turn, and the antenna occupies The area and volume are smaller, the structure is simpler, and the communication quality is reliable.

Further, the metal coil 1 is made of copper. Of course, in addition to copper, it can also be other metals (such as silver, nickel, etc.) or other alloy metals.

The following is an NFC antenna model of a smart watch (the diameter of the watch is 40mm) as a specific example to illustrate the performance of this solution. In order to meet the NFC antenna design specifications, two 560nH inductors and a 5.6pF capacitor need to be used. In particular, the above-mentioned inductance uses an inductor of the type LQW18CNR56J00D provided by Murata Electronics (Murata), and the DC resistance (0.48Ω) of the inductor is very small. Figure 4 is the Smith curve of the antenna without adding inductance and capacitance. It can be seen from Figure 4 that the equivalent inductance value La recorded by the antenna at a frequency of 1MHz is 126.33nH, which is too small to meet the NFC antenna specification. FIG. 5 is a Smith curve of the antenna after adding only two inductors, and FIG. 6 is a Smith curve of the antenna after adding two inductors and a capacitor. It can be seen from Figure 5 and Figure 6 that as long as two inductors are added, the equivalent inductance value La recorded by the antenna at a frequency of 1MHz is 1.37uH, which can meet the NFC antenna specification. In addition, after adding the capacitor, the self-resonant frequency of the antenna is reduced from 96MHz to 52.4MHz. In this design, the equivalent capacitance value calculated using NXP's NFC design guidance formula is 6.72pF, and the equivalent resistance value Ra is 3.3Ω, which can better meet the NFC antenna specification. In card mode or tag mode, the sensing distance of the NFC antenna scheme is 30mm, which fully meets the requirements of the watch design scheme.

Referring to Fig. 7, a smart watch includes a cover 4, a frame 3, a chip assembly 5, a battery (not shown), a back cover 6, a PCB board 2, an antenna assembly and a strap 7, the cover 4, the frame 3 and the back cover 6 form an accommodating space, the chip assembly 5, the PCB board 2, the antenna assembly and the battery are located in the accommodating space, the watch strap 7 is arranged on the frame 3, and the antenna assembly is located on the PCB board 2 , the antenna assembly is an NFC antenna assembly, and the NFC antenna assembly includes an antenna radiation body, an adjustment circuit assembly, a first feeder 11 and a second feeder 12;

The antenna radiating body is a single-turn metal coil 1 surrounding the PCB board 2 and located on the inner surface of the frame 3, the metal coil 1 is provided with an opening 16, and the opening 16 divides the metal coil 1 into a non-closed ring structure;

The regulating circuit assembly includes a first inductance 13, a second inductance 14 and a capacitor 15, one end of the first inductance 13 is connected to the first feeder 11, and the other end of the first inductance 13 is connected to one end of the metal coil 1 ; One end of the second inductance 14 is connected to the second feeder 12, and the other end of the second inductance 14 is connected to the other end of the metal coil 1; one end of the capacitor 15 is connected between the first inductance 13 and the first feeder. The contact point where the electrical part 11 is connected, and the other end is connected to the contact point where the second inductor 14 is connected to the second power feeding part 12 .

Further, the diameter of the metal coil 1 is larger than that of the PCB board 2, and there is a gap between the metal coil 1 and the PCB board 2, and the energy of the metal coil 1 is radiated from the gap (as shown in FIG. 2 ). In particular, the structure does not need to use ferrite, which can simplify the antenna structure and save production cost.

Further, the metal coil 1 is made of copper. Of course, in addition to copper, it can also be other metals (such as silver, nickel, etc.) or other alloy metals.

The above-mentioned NFC antenna design scheme can also be extended to a smart watch with a decorative metal ring.

Referring to Fig. 8 and Fig. 9, a smart watch includes a watch cover 4, a frame 3, a chip assembly 5, a battery, a back cover 6, a PCB board 2, an antenna assembly and a strap 7, the watch cover 4, the frame 3 and The back cover 6 encloses an accommodating space, the chip assembly 5, the PCB board 2 and the battery are located in the accommodating space, the watch strap 7 is arranged on the frame 3, the antenna assembly is an NFC antenna assembly, and also includes a surrounding and The metal ring 1 that is closely attached to the outer surface of the frame 3, the NFC antenna assembly includes an antenna radiation body, an adjustment circuit assembly, a first feeder 11 and a second feeder 12;

The antenna radiating body is a metal ring 1, and the metal ring 1 is provided with an opening 16, and the opening 16 divides the metal ring 1 into a non-closed ring structure;

The regulating circuit assembly includes a first inductance 13, a second inductance 14 and a capacitor 15, one end of the first inductance 13 is connected to the first feeder 11, and the other end of the first inductance 13 is connected to one end of the metal ring 1 One end of the second inductance 14 is connected to the second feeder 12, and the other end of the second inductance 14 is connected to the other end of the metal ring 1; one end of the capacitor 15 is connected between the first inductance 13 and the first feeder. The contact point where the electrical part 11 is connected, and the other end is connected to the contact point where the second inductor 14 is connected to the second power feeding part 12 .

Further, a switch button 8 is also included, and the switch button 8 is located at the opening 16 .

In summary, the NFC antenna structure for wearable devices provided by the utility model, the antenna radiation body of the NFC antenna assembly adopts a single-turn non-closed metal coil or metal ring design, the structure is simpler, and the occupied area and space are small. It is conducive to thinner and miniaturized design; the first inductance and the second inductance connected in series can increase the inductance value of the radiator as a single-turn non-closed metal coil or metal ring, and the capacitance value of the radiator can be increased through capacitance. The main advantages are as follows:

1. This solution is the first simple NFC antenna design suitable for smart watches;

2. This solution does not need to add ferrite, which can reduce production costs and simplify the structure;

3. This scheme is easy to implement, and the copper coil as the antenna radiation body only needs one turn;

4. In this solution, the inductance and capacitance in the circuit are adjusted to meet the requirements of the NFC antenna for inductance and capacitance;

5. This solution is also applicable to a smart watch with a non-closed metal ring. At this time, the non-closed metal ring serves as the only antenna radiation body of the NFC antenna.

6. In addition to the watch of this solution, the NFC antenna structure can also be applied to other wearable devices.

The above is only an embodiment of the utility model, and does not limit the patent scope of the utility model. All equivalent transformations made by using the utility model specification and accompanying drawings, or directly or indirectly used in related technical fields, are all the same. The theory is included in the patent protection scope of the present utility model.

Claims (5)

1. A kind of NFC antenna structure for wearable device, it is characterized in that, comprise antenna radiation main body, adjustment circuit assembly, first feeder and second feeder; The radiating body of the antenna is a single metal coil; the metal coil is provided with an opening, and the opening divides the metal coil into a non-closed ring structure; The regulating circuit assembly includes a first inductance, a second inductance and a capacitor, one end of the first inductance is connected to the first feeder, the other end of the first inductance is connected to one end of the metal coil; the second inductance One end is connected to the second power feeding part, and the other end of the second inductance is connected to the other end of the metal coil; one end of the capacitor is connected to the junction of the first inductance and the first power feeding part, and the other end is connected to the second On the junction where the inductor is connected to the second power feeding part. 2. A smart watch, comprising a watch cover, a frame, a chip assembly, a battery, a back cover, a PCB board, an antenna assembly and a strap, the watch cover, the frame and the back cover enclosing an accommodating space, the chip assembly, The PCB board, the antenna assembly and the battery are located in the accommodation space, and the watch strap is arranged on the frame. It is characterized in that the antenna assembly is an NFC antenna assembly, and the NFC antenna assembly includes an antenna radiation body, an adjustment circuit assembly, a first a power feeding part and a second power feeding part; The antenna radiating body is a single-turn metal coil surrounding the PCB board and positioned on the inner surface of the frame, the metal coil is provided with an opening, and the opening divides the metal coil into a non-closed ring structure; The regulating circuit assembly includes a first inductance, a second inductance and a capacitor, one end of the first inductance is connected to the first feeder, the other end of the first inductance is connected to one end of the metal coil; the second inductance One end is connected to the second power feeding part, and the other end of the second inductance is connected to the other end of the metal coil; one end of the capacitor is connected to the junction of the first inductance and the first power feeding part, and the other end is connected to the second On the junction where the inductor is connected to the second power feeding part. 3. The smart watch according to claim 2, wherein the diameter of the metal coil is larger than that of the PCB board, and there is a gap between the metal coil and the PCB board, and the energy of the metal coil is radiated from the gap. 4. A smart watch, comprising a watch cover, a frame, a chip assembly, a battery, a back cover, a PCB board, an antenna assembly and a strap, the watch cover, the frame and the back cover enclosing an accommodating space, the chip assembly, The PCB board and the battery are located in the accommodating space, the watch strap is arranged on the frame, and it is characterized in that it also includes a metal ring surrounding and closely attached to the outer surface of the frame, the antenna assembly is an NFC antenna assembly, and the NFC antenna The assembly includes an antenna radiating body, an adjustment circuit assembly, a first feeding part and a second feeding part; The radiating body of the antenna is a metal ring, the metal ring is provided with an opening, and the opening divides the metal ring into a non-closed ring structure; The regulating circuit assembly includes a first inductance, a second inductance and a capacitor, one end of the first inductance is connected to the first feeder, the other end of the first inductance is connected to one end of the metal ring; the second inductance One end is connected to the second power feeding part, and the other end of the second inductance is connected to the other end of the metal ring; one end of the capacitor is connected to the junction of the first inductance and the first power feeding part, and the other end is connected to the second On the junction where the inductor is connected to the second power feeding part. 5. The smart watch according to claim 4, further comprising a switch button, the switch button is located at the opening.