CN204966678U

CN204966678U - NFC antenna structure based on metal backshell

Info

Publication number: CN204966678U
Application number: CN201520719258.7U
Authority: CN
Inventors: 赵安平; 陈浩; 毕晔海; 刘健
Original assignee: Shenzhen Sunway Communication Co Ltd
Current assignee: Shenzhen Sunway Communication Co Ltd
Priority date: 2015-09-16
Filing date: 2015-09-16
Publication date: 2016-01-13
Anticipated expiration: 2025-09-16

Abstract

The utility model discloses a NFC antenna structure based on metal backshell, including a metal backshell and an antenna coil, antenna coil sets up the metal backshell is inboard, antenna coil includes first coil and lower half coil, first coil includes first coil and first coil of second, first first coil extends the metal backshell and does not overlap with the metal backshell, first coil of second overlaps with the metal backshell, just be equipped with a ferrite between first coil of second and the metal backshell. Through setting up the ferrite, weaken the negative effects that first coil pair of second NFC antenna itself produced, improve antenna performance, simultaneously, can reduce NFC antenna shared space in the headroom region effectively, have model simple structure, characteristics such as superior performance.

Description

Based on the NFC antenna structure of metal back cover

Technical field

The utility model relates to a kind of antenna structure, particularly relates to a kind of NFC antenna structure based on metal back cover.

Background technology

Along with the development of present stage mobile device near field communication (NFC) function, NFC (NearFieldCommunication near field communication (NFC)) function will be configured in more handheld device, and then impel the research to NFC antenna designs more and more to be paid attention to.In the application of traditional NFC antenna, generally select FPC, namely NFC antenna radiant body is placed on above battery.The bonnet that above-mentioned NFC antenna design is only suitable for handheld device is the situation of non-metallic material.But in the recent period along with the favor of consumer, the mobile device with metal back cover comes into vogue, this brings larger difficulty to the design of NFC antenna.Because when NFC antenna coil is located completely inside complete metal shell, not only metal back cover will produce and the completely reverse eddy current of NFC antenna electric current, and the NFC antenna be placed on inside metal-back cannot be detected outside metal back cover due to the shielding action of metal back cover to electromagnetic field.

After carrying out some suitable process to metal back cover, what such as field, village proposed at patent CN102405556B opens a through hole and one from through hole to the gap at metal back cover edge on metal back cover.This gap " has cut off " original completely reverse eddy current produced on metal back cover, and this eddy current is become and antenna current effective eddy current antenna being had to positive effect in the same way.This due to cracked gap cause in the same way effectively eddy current overcome above-mentioned metal back cover to the shielding action of NFC antenna, NFC antenna can be detected in the outside of metal back cover.Although solve the shielding action of metal back cover to NFC antenna by the method opening hole and gap, but the through hole opened and gap still have impact on the integrality of metal back cover, this destruction to metal back cover integrality have impact on aesthetic feeling and the intensity of metal fuselage equipment undoubtedly.

Research so far for the feasible NFC antenna aspect based on metal back cover that can keep metal back cover integrality is also considerably less.The mode adopted at present is usually that the shielding action of metal back cover to NFC antenna is solved or eliminated in the outside by the part of NFC antenna coil at least half being displaced to metal back cover, as shown in Figure 1, the outside of metal back cover mentioned here generally refers to the space for other principal antenna of handheld device retains, also namely usually said principal antenna headroom district.For handheld device as mobile phone, the appearance design person of equipment expects to go to reduce the space shared by headroom district as far as possible.But in above-mentioned NFC antenna design, in order to ensure to eliminate metal back cover to the shielding action of NFC antenna, NFC antenna coil has to invade in headroom district narrow and small already for principal antenna and other element.In addition, the intrusion of NFC antenna coil not only can have influence on the performance of principal antenna but also can increase the design difficulty of principal antenna, and therefore, optimal scheme reduces NFC antenna space shared in headroom district as far as possible.

Obviously, simply and directly reducing NFC antenna coil is that NFC antenna coil is moved down from headroom district in the method that headroom district takes up space, and it is inner that the some antennas coil by the first half moves to metal back cover.Such as, as shown in Figure 2, if aerial coil is 8 circles, 4 circle coils of the coil first half are moved to metal back cover inner.The electric current of antenna itself is counterclockwise, according to near-field coupling principle, all will produce its corresponding eddy current loop on metal back cover with the aerial coil of metal back cover close contact.To be the Eddy Distribution figure produced on metal back cover by the coil of antenna Lower Half, Fig. 4 be Fig. 3 by the Eddy Distribution figure produced on metal back cover with the coil of metal back cover close contact of the antenna first half.According to the right-hand rule, direction, the eddy current loop effect that also namely the performance of antenna had to enhancing identical with the sense of current of NFC antenna coil in Fig. 3, and direction, the eddy current loop effect that also namely the performance of antenna had to weakening contrary to the sense of current of NFC antenna coil in Fig. 4.Although little by the intensity of the forward eddy current in the reverse swirl ratio Fig. 3 in Fig. 4, different eddy current loops produce in other words the effect of magnetic flux superposition remains forward, and the eddy current loop be reversed is weakened by the performance of NFC antenna entirety undoubtedly.

Utility model content

Technical problem to be solved in the utility model is: provide a kind of be applicable to metal shell take the little and high performance NFC antenna structure of empty regions.

In order to solve the problems of the technologies described above, the technical solution adopted in the utility model is: a kind of NFC antenna structure based on metal back cover, comprise a metal back cover and an aerial coil, described aerial coil is arranged on inside described metal back cover, described aerial coil comprises first half coil and Lower Half coil, described first half coil comprises the first first half coil and the second first half coil, described first first half coil extends metal back cover and not overlapping with metal back cover, described second first half coil is overlapping with metal back cover, and be provided with a ferrite between described second first half coil and metal back cover.

Further, the equal turn numbers of described first first half coil and the second first half coil.

Further, the number of turn of described first first half coil is greater than the number of turn of the second first half coil.

Further, the area equation of described ferritic size and described second first half coil.

Further, described ferritic size is less than the half of the area of described aerial coil.

The beneficial effects of the utility model are: by arranging ferrite, weaken the negative effect that the second first half coil produces NFC antenna itself, improve antenna performance, simultaneously, without the need to opening any through hole and gap on metal back cover, ensure that the integrality of metal back cover, metal back cover is one-body molded, and processing technology is simple.

Accompanying drawing explanation

Fig. 1 is that tradition is based on complete metal back cover NFC antenna structural representation;

Fig. 2 for NFC antenna in empty regions the antenna structure view after being reduced that takes up space;

Fig. 3 is the Eddy Distribution figure that in Fig. 2, NFC antenna Lower Half coil produces on metal back cover;

Fig. 4 is the Eddy Distribution figure that coil that in Fig. 2, the NFC antenna first half is overlapping with metal back cover produces on metal back cover;

Fig. 5 is the NFC antenna structure chart one of the utility model embodiment one;

Fig. 6 is the NFC antenna structure chart two of the utility model embodiment one;

Fig. 7 is the Distribution of Magnetic Field figure at NFC antenna 25 millimeters of places outside distance metal back cover in Fig. 2;

Fig. 8 is the Distribution of Magnetic Field figure at NFC antenna 25 millimeters of places outside distance metal back cover in Fig. 5.

Label declaration: 1, aerial coil; 2, metal back cover; 3, empty regions; 4, the first first half coil; 5, the second first half coil; 6, ferrite.

Embodiment

By describing technology contents of the present utility model in detail, realized object and effect, accompanying drawing is coordinated to be explained in detail below in conjunction with execution mode.

The design of the utility model most critical is: by arranging one deck ferrite between the second first half coil and metal back cover, weaken the negative effect that the second first half coil produces NFC antenna itself.

Refer to Fig. 5 and Fig. 6, a kind of NFC antenna structure based on metal back cover, comprise metal back cover 2 and an aerial coil 1, described aerial coil 1 is arranged on inside described metal back cover 2, described aerial coil 1 comprises first half coil and Lower Half coil, described first half coil comprises the first first half coil 4 and the second first half coil 5, described first first half coil 4 extends metal back cover 2 and not overlapping with metal back cover 2, described second first half coil 5 is overlapping with metal back cover 2, and be provided with a ferrite 6 between described second first half coil 5 and metal back cover 2.

From foregoing description, the beneficial effects of the utility model are: by arranging ferrite 6, weaken the negative effect that the second first half coil 5 pairs of NFC antenna itself produce, improve antenna performance, have model structure simple, the features such as superior performance.

Further, the equal turn numbers of described first first half coil 4 and the second first half coil 5.

Further, the number of turn of described first first half coil 4 is greater than the number of turn of the second first half coil 5.

Further, the size of described ferrite 6 and the area equation of described second first half coil 5.

Further, the size of described ferrite 6 is less than the half of the area of described aerial coil 1.

From foregoing description, the beneficial effects of the utility model are: take empty regions 3 little, reduce the impact on principal antenna performance and design difficulty.

Please refer to Fig. 5 and Fig. 6, embodiment one of the present utility model is: a kind of NFC antenna structure based on metal back cover, be applicable to the mobile devices such as mobile phone, palmtop PC, MP3 player, comprise metal back cover 2 and an aerial coil 1, be empty regions 3 above described metal back cover 2, described aerial coil 1 comprises first half coil and Lower Half coil, described first half coil and Lower Half coil can be completely equal, also can not wait, such as when aerial coil 1 is rectangle, described first half coil only can comprise the coil of the top edge portion of rectangle; Described first half coil comprises again the first first half coil 4 and the second first half coil 5; Alternatively, the number of turn of described first first half coil 4 can be more than or equal to the number of turn of the second first half coil 5, that is, if aerial coil 1 is altogether 8 circles, first first half coil 4 and the second first half coil 5 are 4 circles, and as shown in Figure 5, or the first first half coil 4 is 5 circles, second first half coil 5 is 3 circles, by that analogy.The number of turn of the second first half coil 5 is less, and the performance of antenna is better.Described aerial coil 1 is arranged on inside described metal back cover 2, but described first first half coil 4 extends metal back cover 2 and not overlapping with metal back cover 2, and described second first half coil 5 is still overlapping with metal back cover 2, and be provided with a ferrite 6 between described second first half coil 5 and metal back cover 2, ferrite 6 corresponding with the edge of metal back cover 2; The size of described ferrite 6 is less than the half of the area of aerial coil 1, such as, the size of ferrite 6 can be as shown in Figure 5, also can be as shown in Figure 6, that is, ferrite 6 will isolate the coil of the second Lower Half coil 5 horizontal direction, but can not isolate the coil in Lower Half previous level direction, namely isolated antennas coil 1 Lower Half can not produce the coiler part of effective eddy current; Alternatively, the size of ferrite 6 can equal the area of described second first half coil 5.

Ferrite 6 effectively can weaken being coupled of coil and metal back cover 2, and coil is played to the effect of isolation, therefore effectively can weaken the intensity that the second first half coil 5 produces eddy current on metal back cover 2, ferrite 6 is larger, and antenna performance is better.

Please refer to Fig. 7 and Fig. 8, Fig. 7 is for NFC antenna in the structure shown in Fig. 2 is at the Distribution of Magnetic Field figure apart from the outer 25 millimeters of places of metal back cover 2, Fig. 8 Distribution of Magnetic Field figure for the 25 millimeters of places outside distance metal back cover 2 of NFC antenna in the structure shown in Fig. 5.NFC antenna communication distance, namely also the evaluation index of the performance of antenna is determined by the size of the magnetic flux in the coil be coupled with this NFC antenna coil, and the peak value size of the magnetic field of the large young pathbreaker of this magnetic flux and NFC antenna at the coil place be coupled with it and width relevant; That is only can not evaluate the performance quality of this NFC antenna in the peak value size at this place with the magnetic field of NFC antenna.As can be seen from the field intensity map in Fig. 7 and Fig. 8, be no matter that the peak value of which kind of situation NFC antenna only has one, that is NFC antenna only has a pattern.

Although the number of turn of the second first half coil 5 is less, the performance of antenna is better, the number of turn of the second first half coil 5 is more, and after arranging ferrite, antenna performance is more obvious by the effect promoted.Experimental result shows, compared with the antenna structure shown in Fig. 2, the antenna distance of the antenna structure shown in Fig. 5 improves 23.5%.

In sum, the NFC antenna structure based on metal back cover that the utility model provides, by arranging ferrite, effectively can reduce the space that NFC antenna is shared in empty regions, making the little headroom NFC antenna of high-performance based on complete metal back cover become possibility.

The foregoing is only embodiment of the present utility model; not thereby the scope of the claims of the present utility model is limited; every equivalents utilizing the utility model specification and accompanying drawing content to do; or be directly or indirectly used in relevant technical field, be all in like manner included in scope of patent protection of the present utility model.

Claims

1. the NFC antenna structure based on metal back cover, comprise a metal back cover and an aerial coil, described aerial coil is arranged on inside described metal back cover, it is characterized in that: described aerial coil comprises first half coil and Lower Half coil, described first half coil comprises the first first half coil and the second first half coil, described first first half coil extends metal back cover and not overlapping with metal back cover, described second first half coil is overlapping with metal back cover, and is provided with a ferrite between described second first half coil and metal back cover.

2. NFC antenna structure according to claim 1, is characterized in that: the equal turn numbers of described first first half coil and the second first half coil.

3. NFC antenna structure according to claim 1, is characterized in that: the number of turn of described first first half coil is greater than the number of turn of the second first half coil.

4. NFC antenna structure according to claim 1, is characterized in that: the area equation of described ferritic size and described second first half coil.

5. NFC antenna structure according to claim 1, is characterized in that: described ferritic size is less than the half of the area of described aerial coil.