KR101490513B1 - Wireless charging module consisting composite magnetic sheet - Google Patents

Abstract

The present invention relates to a composite magnetic sheet unit, which is capable of simultaneously providing an NFC (near field communication) antenna function and a wireless charging antenna function to provide an integrated composite magnetic sheet capable of maximizing wireless charging efficiency while enhancing communication distance. do. To this end, the composite magnetic sheet according to the present invention can be realized with a coupling structure of magnetic sheets having different magnetic permeabilities.

Description

[0001] WIRELESS CHARGING MODULE CONSISTING COMPOSITE MAGNETIC SHEET [0002]

The present invention relates to a composite magnetic sheet structure applicable to various antennas and a wireless charging module including a composite magnetic sheet.

As NFC (Near Field Communication) function is adopted in smart phones and the like, it is widely used to exchange point-to-point (P2P) information between bill payment means, transportation card, access card and mobile phone. Since NFC uses 13.56 MHz, it is very secure from hacking and is suitable as a payment method because it is a near-short-range communication method that operates only within a distance of up to 20 cm. The basic configuration of the NFC is as shown in Figs. 1A and 1B. The NFC antenna of the mobile phone is mounted on the back of the battery or in-molding in the case behind the mobile phone considering the size. The NFC antenna 12 and the circuit 13 disposed in the module 11 on the fixed side 10 and the receiving side 20 includes an NFC antenna 22 for receiving the radio wave transmitted from the fixed side module, A processing circuit 23, a magnetic sheet 24, and a battery 21. In this case, the structure of the magnetic sheet may be composed of the structure 25 covering the antenna 22 as shown in (b).

Especially, since the case of the cell phone battery is made of metal, the electromagnetic energy generated from the NFC antenna is absorbed by the battery case serving as a parasitic coupler. Therefore, the communication sensitivity of the NFC antenna is lowered, and as a result, the communication distance becomes very short, so electromagnetic isolation between the metal battery case and the NFC antenna is required. As the isolation means, a magnetic sheet having a magnetic permeability of 1 mm or less in thickness is mainly used.

The magnetic sheet for isolation of the NFC antenna includes a sintered ferrite sheet (permeability 200-500), a half-silted ferrite sheet (permeability 200-500), a metal magnetic powder + polymer composite sheet (permeability 50-150) .

Among the above magnetic sheets, sintered ferrite is required to have a reinforcing material or a reinforcing material when it is employed in a cellular phone because of its easy breaking property. Half slitted ferrite sheets have been developed to improve the impact strength of sintered ferrites, and they have added incrustation to the ferrite surface to reinforce the strength and give some flexibility. The third metal magnetic powder + polymer composite sheet has the advantage that it has a lower magnetic permeability than ferrite but is bent and broken.

The magnetic sheet 24, 25 having high magnetic permeability in the NFC antenna can increase the communication distance by strengthening the magnetic field of the NFC antenna in one direction.

Recently, a wireless charging function of a mobile phone with an electromagnetic induction method has been developed, and employment in a smart phone has begun. In the case of the electromagnetic induction method, frequencies between several kHz and 20 MHz are used. Since the problem of human harm to alternating electromagnetic waves becomes larger as the NFC 13.56 MHz goes to the mixed frequency and high frequency bands, the wireless charging function is implemented at a frequency of 100 kHz to 6 MHz or less to be.

2A shows a configuration of a wireless charging transmitter 30 and a wireless charging transmitter 40 of a smartphone. The wireless charging and transmitting unit 30 is provided with the power transmission antenna 32 and the processing circuit 33, the permanent magnet 35 and the magnetic sheet 34 in the fixed module 31. In addition, the wireless charge receiving unit 40 includes a battery 41, a power receiving antenna 42, a processing circuit 43, a soft magnetic body 44, and a magnetic sheet 45 in the case 46 of the portable terminal do.

2B is a conceptual diagram showing the flow of magnetic flux during wireless charging. It should be noted that the permanent magnet 35 is disposed in the wireless charging transmitter 30 and the soft magnetic body 44 corresponding to the permanent magnet 35 is also configured in the wireless charging receiver 40. [ These permanent magnets and soft magnetic bodies exist for the purpose of easily aligning the center of the transmitting antenna and the center of the receiving antenna during a wireless charging operation. If the positions of the antennas are not matched, the flow of the magnetic flux is out of order, and the leakage magnetic flux increases and the charging efficiency decreases.

Figures 3A and 3B show the flow of magnetic flux in the structure of Figure 2B.

3A, the center permanent magnet 35 of the primary coil (transmission antenna) 32 using two separate magnetic materials is positioned, and a change in magnetic flux (arrow) is generated as shown in FIG. The magnetic flux generated by the permanent magnetic flux (center arrow) and the magnetic flux generated by the current flowing through the antenna at the time of charging operation (outer arrow) are simultaneously formed on the right side.

Here, since the blue magnetic flux of the permanent magnet 35 and the red magnetic flux of the antenna 32 are opposite to each other, there exists a part P to be canceled. As the permanent magnet, an Nd-bonded magnet having a (BH) max of about 10 MGOe is mainly used. The higher the magnetic permeability of the magnetic sheet on the side of the wireless receiving antenna, the more the magnetic flux of the permanent magnet is more affected. That is, since the magnetic flux of the permanent magnet 32 fixes the spin direction of the magnetic sheet on one side, the behavior of the material having low magnetic permeability is actually shown. Also, since the direction of the arranged spins is opposite to the direction of the magnetic flux of the antenna, the magnetic field is canceled, and the inductance of the receiving antenna is lowered as the magnetic sheet having a high magnetic permeability is used.

The functions of the NFC and the electromagnetic induction type wireless charging antenna will be applied to a portable terminal such as a smart phone in the future. In this case, the NFC antenna and the wireless charging antenna are included in the portable terminal case and occupy most of the area. However, in such a case, when the permeability is high or low using a single magnetic material, the characteristics of the two antennas can not be satisfied at the same time.

Embodiments of the present invention have been devised to solve the above-described problems. In the embodiment of the present invention, the NFC (near field communication) antenna function and the wireless charging antenna function are simultaneously complemented to maximize the wireless charging efficiency while enhancing the communication distance And to provide a wireless charging module including the composite magnetic sheet.

As a means for solving the above-mentioned problems, in an embodiment of the present invention, there is provided a wireless tag antenna, comprising: a wireless charger antenna unit; an NFC antenna unit spaced apart from the wireless charger antenna unit; a first magnetic sheet including the wireless charger antenna unit; And a second magnetic sheet adjacent to the second magnetic sheet.

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According to the embodiment of the present invention, it is possible to provide an integrated composite magnetic sheet capable of maximizing the wireless charging efficiency while enhancing the communication distance by complementing the NFC (near field communication) antenna function and the wireless charging antenna function simultaneously, There is an effect of providing a wireless charging module including a magnetic sheet.

In addition, the composite magnetic sheet according to the embodiment of the present invention can incorporate an NFC antenna, a wireless charging antenna, a main antenna, and other sub antennas in a rear case of a portable terminal in a complex manner. The antenna frequency tuning becomes unnecessary for each model, and the antenna can be made flat.

1A and 1B show a structure using a general NFC (near field communication) antenna.
2A is a conceptual diagram showing a configuration of a wireless charging transmitter and a wireless charging transmitter of a smartphone.
2B is a conceptual diagram showing the flow of magnetic flux during wireless charging.
Figures 3A and 3B show the flow of magnetic flux in the structure of Figure 2B.
4A and 4B are conceptual diagrams for explaining the function and structure of the composite magnetic sheet unit according to the present invention.
5 is a graph showing the numerical value of the maximum permeability that can be obtained with respect to the operating frequency.
FIGS. 6A and 6B are conceptual diagrams of experimental examples according to the material constituting the composite magnetic sheet unit according to the present invention, and the results are shown in FIG. 7 as a table.
8 shows the results of measurement of effective permeability value when FeSiAl powder having an average particle size of 25 mu was mixed with Silicone.
9 shows the results of measurement of the efficiency and inductance under the Test 2 condition.
FIG. 10 is a graph of effective permeability for each antenna, and FIG. 11 is a conceptual diagram of the arrangement of magnetic sheets according to the magnetic permeability in the cellular phone rear case.

Hereinafter, the configuration and operation according to the present invention will be described in detail with reference to the accompanying drawings. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS In the following description with reference to the accompanying drawings, the same reference numerals denote the same elements regardless of the reference numerals, and redundant description thereof will be omitted. The terms first, second, etc. may be used to describe various components, but the components should not be limited by the terms. The terms are used only for the purpose of distinguishing one component from another.

4A and 4B are conceptual diagrams for explaining the function and structure of the composite magnetic sheet unit according to the present invention. FIG. 4A is a conceptual view of an antenna arrangement structure of a portable terminal to which the composite magnetic sheet unit according to the present invention is applied, FIG. 4A is a conceptual view showing a cross section taken along the line X-X 'in FIG. Hereinafter, a composite magnetic sheet unit is a concept including a structure in which a plurality of magnetic sheets are disposed adjacent to each other, and a structure implemented with a coil or a separate subsidiary structure. Hereinafter, a wireless charging module will be described as an embodiment do.

4A and 4B, the composite magnetic sheet unit according to the present invention may include a first magnetic sheet and a second magnetic sheet having a higher magnetic permeability than the first magnetic sheet. That is, a structure in which magnetic sheets having mutually different magnetic permeabilities are bonded. The first magnetic sheet may be coupled to the second magnetic sheet with an area relatively narrower than that of the second magnetic sheet or the second magnetic sheet may be disposed outside the first magnetic sheet. Particularly, in the embodiment of the present invention, it is possible to provide a composite magnetic sheet unit having a structure in which the first magnetic sheet and the second magnetic sheet having mutually different permeabilities are disposed adjacent to each other. In this case, A structure in which the first magnetic sheet is closely arranged on the side surface of the sheet or is spaced apart from the side surface of the sheet, or a structure in which the first magnetic sheet is in close contact with or spaced from the top or bottom. In this case, the composite magnetic sheet unit can implement a wireless charging module with a structure including a coil for wireless charging or NFC. As described below, the composite magnetic sheet unit according to the embodiment of the present invention is applied to a wireless charging module in which sheets having mutually different permeabilities are disposed adjacent to each other. In this case, an NFC antenna The wireless charging module may include a first magnetic sheet including the wireless charging antenna unit and a second magnetic sheet adjacent to the first magnetic sheet. That is, the first magnetic sheet may include a coil for wireless charging. In addition, the first magnetic sheet or the second magnetic sheet may be disposed adjacent to each other, and the second magnetic sheet may be in contact with one surface or side surface of the first magnetic sheet with respect to the first magnetic sheet including the coil of the radio- Or may be disposed so as to be spaced apart from one surface or side surface of the first magnetic sheet. In addition, in the embodiment of the present invention, a plurality of compound magnetic sheets may be provided in a number, but in the wireless charging module, only the first magnetic sheet or the second magnetic sheet having a different magnetic permeability is used, And the third magnetic sheet may include a coil portion for an NFC function or another function, a coil portion for an NFC antenna portion or an auxiliary antenna portion in the present invention, It should be understood that the present invention is not limited thereto.

The composite magnetic sheet unit in the present invention is defined as a concept including a plurality of sheet structures, and as an embodiment of the composite magnetic sheet unit described above, a structure that is stacked on the plurality of antennas shown in FIG. I will explain.

4A shows an arrangement of a plurality of antennas formed in a rear case of a portable terminal, and includes a wireless charging antenna unit 210 and an NFC antenna unit 220, A main antenna unit 230, and a sub-antenna unit 240, as shown in FIG. The composite magnetic sheet according to the present invention can be used in the form of being laminated on the above-mentioned antenna portion.

Referring to FIG. 4B, which is a cross-sectional view taken along the line X-X 'in FIG. 4A, a first charging unit 210, which is stacked on and connected to a wireless charging antenna unit 210 formed in a rear case 250 of a portable terminal incorporating a battery B, And a second magnetic sheet 120 stacked on the magnetic sheet 110 and the NFC antenna unit 220 formed on the rim of the wireless charging antenna unit 210. The first magnetic sheet and the second magnetic sheet are coated with a magnetic material on respective antenna portions and are pressed by lamination or the like. The interface between the first magnetic sheet and the second magnetic sheet is in contact with the antenna portion and has a predetermined curvature (for example, .

That is, the composite magnetic sheet unit according to the present invention includes the first magnetic sheet and the second magnetic sheet having mutual permeability different from each other, and the first magnetic sheet 110 and the second magnetic sheet 120 are shown And may be disposed at corresponding positions on the NFC antenna unit 220 formed on the rim of the wireless rechargeable antenna unit 210 as shown in FIG.

In this case, in the case of the magnetic sheet used for the wireless rechargeable antenna unit, the electromagnetic induction type magnetic sheet is used. As a problem described in Fig. 3, due to the interference with the permanent magnets included in the antenna unit for transmitting the charging power, The inductance of the receiving antenna is lowered as the magnetic sheet having a high magnetic permeability is used, and the magnetic permeability of the first magnetic sheet 110, which can minimize the inductance of the receiving antenna, is in the range of 20 to 50 .

That is, preferably, the first magnetic sheet 110 according to the present invention preferably has a permeability of 20 to 50, and the second magnetic sheet 120 preferably has a permeability of 100 to 550 . At the same time, when the magnetic sheet having a high magnetic permeability is used in the case of the NFC antenna unit 120, the size of the NFC antenna is reduced and the recognition distance is increased. That is, since the maximum magnetic permeability obtainable with respect to the operating frequency is determined by Snoek's limit, it can be calculated by the following equation.

{1}

5, assuming that Ms (maximum magnetization) of the Mn-Zn ferrite is 5 kG, the magnetic permeability is about 620 at the self-resonant frequency Fr of 13.56 MHz. Therefore, considering the effects of damping by magnetic domain rotation and damping by magnetic spin rotation, the permeability of about 500 ~ 550 is the maximum limit of permeability that can be generally realized in the NFC frequency band.

In this case, the first magnetic sheet includes a composite material of a metal-based magnetic powder and a polymer composed of one or a combination of two or more elements selected from among Fe, Ni, Co, Mo, Si, . Here, the polymer includes various polymer materials such as silicon, polyimide, nylon, teflon, and epoxy.

Alternatively, the first magnetic sheet may include a composite material of a polymer and a ferrite powder composed of a combination of two or more elements selected from Fe, Ni, Mn, Zn, Co, Cu and Ca .

Further, the second magnetic sheet may be a ferrite sintered body composed of a combination of two or more elements selected from Fe, Ni, Mn, Zn, Co, Cu, and Ca, or may be a ferrite sintered body composed of a ferrite- And may further include a structure in which half slitting is implemented.

Hereinafter, experimental examples of materials constituting the composite magnetic sheet unit according to the present invention will be described with reference to FIGS. 6A, 6B and 7.

6A and 6B show a state in which the configuration of the wireless charging antenna is the same, one side is a state in which the permanent magnet 315 is removed and one side is a permanent magnet (actually, a permanent magnet is inserted into the product, 6a) and Test2 (FIG. 6b), it can be determined that the difference in the efficiency of the experimental example is not the greatest.) In the experimental example using the composite magnetic sheet unit according to the present invention, Test1 (FIG. 6A) and Test 2 (FIG. 6B) are shown in FIG. Type 1 is sintered ferrite (Ni-Zn type), No. 2 to No. 5 is half slited ferrite (Mn-Zn type), No. 6 is amorphous ribbon (FeSiB) Respectively.

7 showing the results of the performance test, the efficiency difference between Test 1 (FIG. 6A: no permanent magnet) and Test 2 (FIG. 6B: permanent magnet) It can be judged that the performance is excellent. 6A: no permanent magnet), Test 2 (FIG. 6B: when there is a permanent magnet), and the like. And thus it can not be used as an appropriate material.

When the magnetic sheet has conductivity, the inductance of the receiving antenna increases, but the transmission efficiency is reduced because the battery case acts as an electrode of the parasitic capacitor or is electrically short-circuited. As a result, Test1 efficiency of the amorphous ribbon, which is a metal type, was relatively poor.

When the magnetic permeability of the magnetic sheet was high, there was a large inductance difference between Test 1 and Test 2. As a result, the transmission efficiency decreased, and the resistance of Test2 was measured higher than that of Test1. This is due to the influence of the magnetoresistance generated when the inductance of the coil is disturbed by the permanent magnet.

The results showed that the composite sheet of Sendust (FeSiAl) and polymeric Silicone, the metal magnetic powders, showed the best results. Sintered Ni-Zn ferrite also showed good results, but its use may be limited due to its weak impact resistance properties. Composite materials can easily be made by uniformly mixing a certain amount of FeSiAl powder with Silicone and curing at 120 to 150 ° C. FIG. 8 shows the result of measuring the effective permeability value when FeSiAl powder having an average particle size of 25 .mu.m is mixed with Silicone. In this case, the effective permeability for the mixing of the FeSiAl powder is given by the following formula.

{Equation 2}

_{e μ: effective permeability (an effective permeability), δ pores between particles (gap between particles), D: particle diameter _{(particle 'diameter), f filler} : the volume of the magnetic filler index (a volume fraction of magnetic filler) }

The efficiency and inductance of the Sendust-Silicone composite sheet having the respective effective permeabilities were measured under the Test 2 conditions using the above-described Equation 2, and the results are shown in FIG. As shown in Fig. 9, in order to obtain a wireless charging efficiency or more, the magnetic sheet is most preferably in the range of 20 to 50 effective permeability.

Referring to FIG. 10, the highest frequency of the main antenna or the sub-antenna corresponding to the GHz antenna is 2.5 GHz. According to the Snoek limit, assuming that Hexaferrite has 3 kG, 2.2 at 2.5 GHz is the maximum permeability value. However, since hexaferrite has a very high magnetic anisotropy energy, it has self-resonant frequency slightly higher than Snoek's limit. Therefore, the actual maximum permittivity value is about 2.5 ~ 3.0, but considering the magnetic damping, the value of 2.2 ~ 2.5 is the practical maximum permeability value for the antenna. And the upper limit of the permeability rate is about 8 at 700 MHz which is the lower limit band of the US LTE.

Referring to FIG. 11, there is shown an arrangement of a composite magnetic sheet according to the present invention, which is disposed at a corresponding position in FIG. 5a.

5A and 11, the NFC antenna 13.56 MHz has an upper limit of permeability of 550, the wireless charging antenna has a permeability of 20 to 50, the 2.5 GHz antenna has 2.5 and the 900 MHz has a permeability upper limit of 6.0 .

Therefore, the first magnetic sheet according to the present invention may have a permeability of 20 to 50 and a second magnetic sheet of 100 to 550. In addition, in FIG. 4A, the composite magnetic sheet unit according to the present invention may further comprise a third magnetic sheet having a different magnetic permeability in addition to the first magnetic sheet and the second magnetic sheet. For example, a magnetic sheet structure having a magnetic permeability different from that of the first magnetic sheet or the second magnetic sheet may be used as the above-described main antenna or auxiliary antenna, or a third magnetic sheet applied to support a coil for NFC function And the like. For example, the third magnetic sheet may be applied with a magnetic sheet having a magnetic permeability of 1.1 to 2.5 for gigahertz (GHz). In this case, as shown in FIG. 4A and FIG. 11, the third magnetic sheet is disposed apart from the first and second magnetic sheets, and is selected from Fe, Co, Ba, Sr, Zn, And a ferrite sintered body composed of a combination of two or more elements. Or a ferrite-based powder composed of a combination of two or more elements selected from Fe, Ni, Mn, Zn, Co, Cu, Ca, Li, Ba, Sr, .

4A, 4B and 11, the composite magnetic sheet unit according to the present invention comprises a wireless charging antenna unit disposed at a position corresponding to the first magnetic sheet and being in close contact with the second magnetic sheet And an NFC antenna unit disposed at a position where the NFC antenna unit is in close contact with the rear case. In this case, the wireless recharging antenna unit and the NFC antenna unit may be closely contacted with the first and second magnetic sheets through a fluorine-based or polyimide-based high heat-resistant adhesive material. That is, the adhesive can be bonded using a fluorine-based or polyimide-based high-heat-resistant adhesive material which is stable at a temperature of 200 degrees or more to in-mold the rear case of the cellular phone.

A plurality of magnetic sheets to be applied to the composite magnetic sheet unit according to the embodiment of the present invention can be integrated with an NFC antenna, a wireless charging antenna, a main antenna, and other sub-antennas (GPS, Wi-Fi, In this case, too, it is less influenced by the active environment of the cellular phone main board, so antenna frequency tuning is unnecessary for each model, and the antenna can be made flat.

In the foregoing detailed description of the present invention, specific examples have been described. However, various modifications are possible within the scope of the present invention. The technical idea of the present invention should not be limited to the embodiments of the present invention but should be determined by the equivalents of the claims and the claims.

110: first magnetic sheet
120: second magnetic sheet
210: Wireless charging antenna unit
220: NFC antenna section
230: Main antenna part
240: Sub-
250: Cell phone rear case

Claims (23)

A wireless charging antenna unit;
An NFC antenna unit adjacent to the wireless charging antenna unit;
A first magnetic sheet having a first face in a first direction and a second face in a second direction opposite to the first face, the wireless fill antenna portion being disposed on the first face; And
And a second magnetic sheet disposed adjacent to the first magnetic sheet and having a first surface in a first direction and a second surface in a second direction opposite to the first surface, ;
And a lowermost surface of the first surface of the first magnetic sheet is disposed higher than a lowermost surface of the second surface of the second magnetic sheet.
The method according to claim 1,
Wherein the first magnetic sheet and the second magnetic sheet have different magnetic permeability.
The method of claim 2,
Wherein the first magnetic sheet and the second magnetic sheet are made of different materials.
The method according to any one of claims 1 to 3,
Wherein the first magnetic sheet
And a composite material of a metal-based magnetic powder and a polymer composed of one or more elements selected from the group consisting of Fe, Ni, Co, Mo, Si, Al and B, or a combination of two or more elements.
The method according to any one of claims 1 to 3,
Wherein the first magnetic sheet
And a ferrite-based powder comprising a combination of two or more elements selected from Fe, Ni, Mn, Zn, Co, Cu, and Ca.
The method according to any one of claims 1 to 3,
Wherein the second magnetic sheet
Wherein the second magnetic sheet comprises a ferrite sintered body formed of a combination of two or more elements selected from Fe, Ni, Mn, Zn, Co, Cu, and Ca.
The method according to claim 1,
Wherein the areas of the first magnetic sheet and the second magnetic sheet are different.
The method according to claim 1,
Wherein the thickness of the first magnetic sheet is 0.5 mm to 0.7 mm.
The method according to claim 1 or 8,
And the thickness of the second magnetic sheet is 0.5 mm to 0.7 mm.
The method according to any one of claims 1 to 3, claim 7 and claim 8,
Wherein the second magnetic sheet
Contacting the side surface of the first magnetic sheet,
Or the side of the first magnetic sheet.
The method of claim 10,
Wherein the NFC antenna portion is disposed at an outer periphery of the wireless rechargeable antenna portion.
The method of claim 11,
Wherein the surface of the second magnetic sheet further comprises a half-slit structure. delete delete delete delete delete delete delete delete delete delete delete

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