JP2008251283A - Electronic devices and secondary batteries - Google Patents

Abstract

Provided is an electronic device capable of good wireless communication through a magnetic field even when an antenna is disposed around a secondary battery.
In a portable terminal, an antenna (31) for performing wireless communication via a magnetic field is disposed around a secondary battery (24) as a power source. The secondary battery 24 has a metal positive electrode current collector coated with a positive electrode active material, a metal negative electrode current collector coated with a negative electrode active material, and a charge / discharge part including an electrolyte. Seal with part. The exterior portion includes an adhesive layer and a magnetic shield, and the magnetic shield is disposed outside the adhesive layer.
[Selection] Figure 2

Description

  The present invention relates to an electronic device and a secondary battery. In particular, the present invention relates to an electronic device including a secondary battery whose surface is covered with an exterior portion having a magnetic shield, and the secondary battery.

  In electronic devices such as portable terminals, secondary batteries are often used as power supply sources. An example of the secondary battery is a lithium ion battery. A lithium ion battery generally has a positive electrode portion, a negative electrode portion, and an insulator separator disposed between them, and has a structure in which these are immersed in an electrolytic solution and sealed in a metal can case. Lithium ion batteries use a lithium compound in the positive electrode part, and are charged when lithium ions move from the positive electrode to the negative electrode through the separator, and discharged by moving from the negative electrode to the positive electrode.

  However, in such a lithium ion battery, the metal can case is used to form the exterior, so that the thickness is increased and the weight is increased. Therefore, Patent Document 1 discloses a thin battery in which a solid electrolyte such as a gel electrolyte is sandwiched between a positive electrode portion and a positive electrode portion, and sealed with an exterior material of a moisture-proof multilayer film including a synthetic resin layer and a metal foil layer. Yes.

  On the other hand, in recent years, electronic devices such as portable terminals have a data communication function that wirelessly communicates various data with an external device that is a communication target via a magnetic field. For this data communication function, for example, RFID (Radio Frequency Identification) technology is used.

One of communication methods in RFID is an electromagnetic dielectric method. In this electromagnetic dielectric system, the reader / writer device and the IC tag have an antenna coil, and the reader / writer device causes a current to flow through the antenna coil to generate a magnetic field. By coupling this magnetic field with the antenna coil of the IC tag, a current is generated in the antenna coil of the IC tag. The IC tag emits electromagnetic waves (for example, frequencies of 135 kHz and 13.56 MHz) using this current, or receives electromagnetic waves emitted from the reader / writer device. Thereby, the IC tag and the reader / writer device perform data communication.
By implementing this data communication function, an electronic device such as a portable terminal is used as a medium such as an electronic ticket or electronic money.

  On the other hand, in such wireless communication via a magnetic field, if there is an object that disturbs the magnetic field such as metal between the IC tag and the reader / writer device, good communication cannot be performed. For example, when a magnetic field enters a metal, an eddy current is generated in the metal, and this eddy current generates a reverse magnetic field opposite to the magnetic field that couples the IC tag and the reader / writer device, thereby disturbing the magnetic field. . Therefore, it is necessary to suppress such factors that disturb the distribution of the magnetic field between the IC tag and the reader / writer device.

  For example, Patent Document 2 discloses a portable information device in which an RFID is incorporated, an RFID antenna coil is disposed on a battery cover, and a magnetic sheet is disposed between the RFID antenna coil and the battery. In this portable information device, the magnetic flux radiated from the external device that is the communication object passes through the antenna coil and the inside of the magnetic sheet having a small magnetic path resistance. Due to this magnetic shielding effect, the magnetic flux does not reach the battery, so that the above-described magnetic field disturbance does not occur, and RFID communication is possible.

  In addition, electronic devices such as portable terminals are required to be thin and small. Therefore, in order to reduce the thickness and size of an electronic device while providing a data communication function such as RFID as described above, an antenna coil connected to the IC chip is used as a loop antenna, and the loop antenna is used as a power source of the electronic device. Arranging around a certain secondary battery is performed.

JP 11-31505 A JP 2004-227046 A

  However, by disposing the loop antenna around the secondary battery, the secondary battery is surrounded by a magnetic field coupled between the IC tag and the reader / writer device. Therefore, it is difficult to suppress the influence on the magnetic field by the metal part of the secondary battery by arranging the magnetic sheet in the electronic device. As a result, a magnetic field enters the secondary battery and an eddy current is generated in the metal part inside the secondary battery, and a magnetic field that couples the IC tag and the reader / writer device is generated by a new magnetic field generated by the eddy current. There is a problem that wireless communication between the IC tag and the reader / writer device is disturbed.

  Therefore, there is a demand for an electronic device that can perform good wireless communication via a magnetic field even when an antenna is disposed around the secondary battery.

  An electronic device that performs wireless communication with a communication object according to the present invention via a magnetic field is a secondary battery that supplies power to an electric circuit of the electronic device, and the wireless communication that is disposed around the secondary battery. And the secondary battery includes a metal positive electrode current collector coated with a positive electrode active material, a metal negative electrode current collector coated with a negative electrode active material, and an electrolyte; and The exterior part which seals a charging / discharging part has an adhesive layer and the magnetic shielding body which excludes the influence of the said magnetic field arrange | positioned on the outer side of the said adhesive layer.

  Preferably, the exterior part has a metal layer between the adhesive layer and the magnetic shield.

  Preferably, the exterior part has an insulating layer outside the magnetic shield.

  Further, the secondary battery of the present invention includes a charge / discharge unit including a metal positive electrode current collector coated with a positive electrode active material, a metal negative electrode current collector coated with a negative electrode active material, and an electrolyte; An exterior portion that seals the portion, and the exterior portion includes an adhesive layer and a magnetic shield disposed outside the adhesive layer.

  Preferably, in the secondary battery, the exterior portion includes a metal layer between the adhesive layer and the magnetic shield.

  Preferably, in the secondary battery, the exterior portion has an insulating layer outside the magnetic shield.

  According to the electronic device of the present invention, even when an antenna is disposed around the secondary battery, good wireless communication is possible via a magnetic field.

  Hereinafter, an electronic device and a secondary battery of the present invention will be described with reference to the accompanying drawings. Note that, as an example of the present invention, an electronic apparatus is described as a portable terminal, and wireless communication performed via a magnetic field with a communication target is described as an RFID. However, the present invention is not limited to this.

With reference to FIG. 1, the portable terminal 1 which is embodiment which concerns on this invention is described.
The portable terminal 1 is a portable terminal having a foldable structure, and FIG. 1 is a perspective view showing the inner surface side of the portable terminal 1 according to the present invention in an opened state.

A configuration of the mobile terminal 1 will be described.
The mobile terminal 1 includes an upper housing 2, a lower housing 3, and a hinge unit 4 that rotatably couples the upper housing 2 and the lower housing 3. The mobile terminal 1 has an RFID function.
The portable terminal 1 can be folded by rotating the upper housing 2 and the lower housing 3 with the hinge portion 4 as a fulcrum, and matching the sides shown in FIG. Therefore, in the present embodiment, the side shown in FIG. 1 will be described as the inner surface side of the mobile terminal 1 and the side opposite to the inner surface side will be described as the outer surface side of the mobile terminal 1.

The upper housing 2 has a rear case 10 disposed on the outer surface side and a front case 11 disposed on the inner surface side. An opening is formed on the inner surface of the front case 11, and the display 12 is accommodated by exposing the display from the opening.
Then, the rear case 10 and the front case 11 are combined, and the upper housing 2 is integrated.

  The lower housing 3 has a rear case 20 disposed on the outer surface side and a front case 21 disposed on the inner surface side. The lower housing 3 has a rechargeable battery and a substrate (not shown) arranged inside. Here, the rechargeable battery is an example of the secondary battery in the present invention. The lower housing 3 includes an IC chip (not shown) and an antenna coil that are used for RFID.

The front case 21 is provided with an operation portion 22 on the inner surface. The operation unit 22 can perform operations such as a call, mail, and the Internet by key input, and a display corresponding to the operation is displayed on the display 12.
The rechargeable battery is a rechargeable battery that supplies power to the electric circuit of the portable terminal 1, and is, for example, a lithium ion battery.
The operation at the operation unit 22 and the supply of electric power from the rechargeable battery are controlled by an electric circuit provided on the substrate.
Then, the rear case 20 and the front case 21 are combined, and the lower housing 3 is integrated.
The IC chip and antenna coil will be described later.

  The hinge part 4 couple | bonds the upper housing | casing 2 and the lower housing | casing 3 rotatably. The portable terminal 1 is folded by rotating the upper housing 2 and the lower housing 3 with the hinge portion 4 as a fulcrum until their inner surfaces come into contact with each other. On the other hand, the portable terminal 1 is opened to a position where the inner surface of the upper housing 2 contacts the outer surface of the lower housing 3 with the hinge portion 4 as a fulcrum.

The inside of the lower housing 3 will be described with reference to FIG.
FIG. 2 is an internal exploded view of the lower housing 3. In FIG. 3, some of the components provided in the lower housing 3 are omitted.
FIG. 2 shows the rear case 20, the substrate 23, the rechargeable battery 24, the rechargeable battery cover 25, and the main antenna 26. Further, a loop antenna 31 and an IC chip 32 are shown as the RFID unit 30 that performs the RFID operation.

The rear case 20 will be described.
In FIG. 2, the rear case 20 has an upper end (end on the upper housing 2 side) at the upper left side of the paper and a lower end at the lower right side. The upper side of the drawing is the inner surface, and the lower side of the drawing is the outer surface. The rear case 20 is formed in a shape that can accommodate components therein by the flat surface portion 20a and the side surface portion 20b.
A hinge fixing portion 20 c that fixes the hinge portion 4 is formed at the upper end of the rear case 20.
The rear case 20 is formed with a rechargeable battery storage portion 20d. The rechargeable battery storage portion 20d includes an opening 20e formed near the lower end of the flat portion 20a, and a frame 20f that surrounds the opening 20e and is provided inside the flat portion 20a, and is surrounded by the frame 20f. The rechargeable battery 24 is stored in the space.

The substrate 23 will be described.
The substrate 23 is provided inside the rear case 20 so as to cover the inside of the rechargeable battery storage unit 20 d in the rear case 20. Various electronic components are mounted on the substrate 23, and the operation of the operation unit 22 and the display 12 are controlled.

The rechargeable battery 24 will be described.
The rechargeable battery 24 is a secondary battery in the present invention. A lithium ion battery is used for the rechargeable battery 24. Since the lithium ion battery has a higher energy density than other secondary batteries, it can be reduced in size and weight, and since the operating voltage is high and the number of rechargeable batteries used is reduced, the mobile terminal 1 Can be reduced in size and weight.
The rechargeable battery 24 is stored in the rechargeable battery storage unit 20 d from the outer surface side of the rear case 20. The stored rechargeable battery 24 is electrically connected to the substrate 23 and supplies power to the electric circuit of the portable terminal 1. The details of the rechargeable battery 24 will be described later.

The rechargeable battery cover 25 will be described.
The rechargeable battery cover 25 is a component that holds the rechargeable battery 24 stored in the rechargeable battery storage section 20 d inside the rear case 20 by covering the opening 20 e of the rechargeable battery storage section 20 d on the outer surface of the rear case 20. It is.

The main antenna 26 will be described.
The main antenna 26 communicates with an external device in a frequency band used for data communication such as telephone calls, mails, and the Internet. As this use frequency band, a frequency band different from the use frequency band of RFID, such as 800 MHz, is used. The main antenna 26 is provided between the lower end of the rear case 20 and the frame 20f of the rechargeable battery storage unit 20d. The main antenna 26 is connected to the substrate 23, transmits the received signal to the substrate 23, demodulates it, and transmits the signal modulated by the substrate 23 to an external device.

The RFID unit 30 will be described.
The RFID unit 30 includes a loop antenna 31 and an IC chip 32.
In the loop antenna 31, a coil is wound in a spiral shape around a rectangular frame member having an opening 30a. The material of the frame material of the loop antenna 31 is, for example, PET (polyethylene terephthalate).
The opening 31a of the loop antenna 31 is formed in a size that fits on the outer peripheral surface of the frame 20f in the rechargeable battery storage 20d. Thereby, the loop antenna 31 is provided in the outer periphery of the frame 20f in the rechargeable battery storage part 20d, and is arrange | positioned around the rechargeable battery 24 stored in the rechargeable battery storage part 20d.

  The IC chip 32 is disposed at a position facing the loop antenna 31 on the substrate 23 and is connected to the loop antenna 31.

The RFID unit 30 will be further described with reference to FIG.
FIG. 3 is a functional block diagram showing functions of the RFID unit 30.
The RFID unit 30 includes a loop antenna 31 and an IC chip 32. The loop antenna 31 is coupled to the antenna coil of the reader / writer device 37, which is a communication object, via a magnetic field.

Since the loop antenna 31 is as described above, the description thereof is omitted.
The IC chip 32 includes a power supply circuit 33, an RF circuit 34, a CPU 35, and a memory 36. The power supply circuit 33 is connected to the loop antenna 31, the RF circuit 34, the CPU 35, and the memory 36. In addition, the RF circuit 34 is connected to the loop antenna 31 and the CPU 35. In addition, the CPU 35 is connected to the memory 36.

The operation of the RFID with the above configuration will be described.
In the reader / writer device 37, a magnetic field is generated by passing a current through the antenna coil. When the loop antenna 31 of the RFID unit 30 approaches the reader / writer device 37, it couples with the magnetic field generated by the reader / writer device 37, and an electromotive force is generated by electromagnetic induction.

  The power supply circuit 33 creates a predetermined power supply voltage from the electromotive force generated by the electromagnetic induction action, and supplies power to the RF circuit 34, the CPU 35, and the memory 36. The RF circuit 34, the CPU 35, and the memory 36 shift from the stopped state to the activated state when power is supplied from the power supply circuit 33.

  The RF circuit 34 receives the electromagnetic wave signal received by the loop antenna 31 from the reader / writer device 37, performs signal processing such as demodulation, and supplies the processed signal to the CPU 35.

  The CPU 35 writes data to the memory 36 or reads data from the memory 36 based on the signal supplied from the RF circuit 34. When reading data from the memory 36, the CPU 35 supplies this data to the RF circuit 34. The RF circuit 34 performs signal processing such as modulation on the data read from the memory 36, and then transmits the signal processed data via the loop antenna 31 to the reader / writer device 37 by electromagnetic waves.

The rechargeable battery 24 will be described with reference to FIGS. As an example of the rechargeable battery 24, the rechargeable battery 24 will be described as a lithium ion battery.
FIG. 4A is a perspective view of the rechargeable battery 24. FIG. 4B is a diagram schematically showing the internal structure of the rechargeable battery 24. In FIG. 4B, electrode terminals 41c and 42c are shown at the left and right ends of the figure for easy understanding of the figure. About the some same member in FIG.4 (B), a code | symbol is attached | subjected only to some members, and the code | symbol of another member is abbreviate | omitted.

The configuration of the rechargeable battery 24 will be described.
The rechargeable battery 24 has a structure in which the charge / discharge part 40 is sealed with an exterior part 50.
The charge / discharge part 40 includes a positive electrode part 41, a negative electrode part 42, a solid electrolyte 43, and a separator 44. Here, the solid electrolyte 43 is an example of an electrolyte in the present invention. The plate-like positive electrode part 41 and the negative electrode part 42 are alternately arranged in the vertical direction with the solid electrolyte 43 interposed therebetween and facing the plane. A separator 44 is disposed between the positive electrode part 41 and the negative electrode part 42.

The positive electrode portion 41 is a portion formed in a flat plate shape so that the positive electrode active material 41a and the positive electrode current collector 41b can be energized.
The positive electrode active material 41a is a powder of several microns, and is applied to one or both surfaces of the positive electrode current collector 41b so as to face a negative electrode active material 42a described later. In the lithium ion battery, a lithium compound such as lithium cobaltate, lithium manganate, or lithium nickelate is used as the positive electrode active material 41a.

  The positive electrode current collector 41b is a metal foil that extracts electricity from the applied positive electrode active material 41a. In lithium ion batteries, aluminum foil is used. One end of the positive electrode current collector 41b protrudes from the positive electrode active material 41a, and the protruding portions are overlapped to attach the conductive electrode terminal 41c. The electrode terminal 41c functions as a positive battery electrode.

The negative electrode portion 42 is a portion formed in a flat plate shape so that the negative electrode active material 42a and the negative electrode current collector 42b can be energized.
The negative electrode active material 42a is applied to one side or both sides of the negative electrode current collector 42b so as to face the positive electrode active material 41a described above. In the lithium ion battery, a carbon material such as graphite or coke is used as the negative electrode active material 42a.

  The negative electrode current collector 42b is a metal foil that extracts electricity from the applied negative electrode active material 42a. In lithium ion batteries, copper foil is used. One end of the negative electrode current collector 42b protrudes from the negative electrode active material 42a, and the protruding portions are overlapped to attach the conductive electrode terminal 42c. The electrode terminal 42c functions as a negative battery electrode.

The solid electrolyte 43 is, for example, a gel gel electrolyte. The gel electrolyte is a mixture of an organic polymer and a liquid electrolyte. In a lithium ion battery, the liquid electrolyte is an organic solvent in which a lithium salt is dissolved. The polymer used for the gel electrolyte is, for example, polyethylene oxide, polyacrylonitrile, polyvinylidene fluoride, and polymethyl methacrylate, and an organic solvent or the like is added as a plasticizer.
When the solid electrolyte 43 is a gel electrolyte, the gel electrolyte is applied to the positive electrode active material 41a and the negative electrode active material 42a, and the gel electrolytes are overlapped so that the gel electrolytes face each other. 42.

The separator 44 is a polymer porous film that allows ions moving between the positive electrode active material 41 a and the negative electrode active material 42 a to pass through. The positive electrode portion 41 and the negative electrode portion 42 are separated by separating the positive electrode portion 41 and the negative electrode portion 42. To prevent short circuiting due to contact.
In addition, when the solid electrolyte 43 has sufficient strength and there is no possibility that the positive electrode portion 41 and the negative electrode portion 42 come into contact with each other and short-circuit, the separator 44 may not be provided.

The operation of the rechargeable battery 24 will be described.
When the rechargeable battery 24 is charged, lithium ions move from the positive electrode active material 41a through the separator to the negative electrode active material 42a. Thereby, since the negative electrode current collector 42b takes out electricity from the negative electrode active material 42a and sends it to the positive electrode current collector 41b, a charging current flows and the rechargeable battery 24 is charged.
When the rechargeable battery 24 is discharged, lithium ions move from the negative electrode active material 42a through the separator to the positive electrode active material 41a. Accordingly, since the positive electrode current collector 41b takes out electricity from the positive electrode active material 41a and sends it to the negative electrode current collector 42b, a discharge current flows and power is supplied from the rechargeable battery 24 to the electric circuit of the portable terminal 1. .

The exterior part 50 will be described with reference to FIG.
FIG. 5 is a cross-sectional view of the exterior portion 50.
The exterior portion 50 includes an adhesive layer 51, a metal foil layer 52, a magnetic layer 53, and an insulating layer 54, and these layers are integrally laminated in this order. The exterior part 50 is sealed by arranging the adhesive layer 51 side on the inside and the insulating layer 54 side on the outside to cover the charging / discharging part 40 of the rechargeable battery 24 and bonding the adhesive layers 51 together.

The adhesive layer 51 is, for example, a heat-sealable resin, and is fused by bringing the adhesive layers 51 into contact with each other and heating the contact portion. As the heat-fusible resin, polyolefin resins such as polyethylene and polypropylene, polyamide resins, vinyl acetate resins, acrylic resins, and epoxy resins can be used.
Note that an adhesive resin having adhesiveness can be used as the adhesive layer 51.

The metal foil layer 52 is an example of a metal layer in the present invention. The metal foil layer 52 is provided to make the rechargeable battery 24 light-shielding and moisture-proof so as to suppress the deterioration of the rechargeable battery 24 and to ensure the strength of the rechargeable battery 24.
That is, by providing the metal foil layer 52, the durability of the rechargeable battery 24 can be improved due to the light shielding property and moisture proof property, and the strength against an external force such as an impact load can be improved.
The metal foil layer 52 is preferably an aluminum foil. According to this, since it has light-shielding property, moisture-proof property, and strength, a thin foil is obtained, and the price of aluminum is also low, it is possible to obtain a rechargeable battery 24 that is light and thin and inexpensive to produce.

  The magnetic layer 53 is an example of a magnetic shield in the present invention. The magnetic layer 53 is a layer that is magnetized by a magnetic field. For example, it can be formed by mixing a magnetic material such as ferrite in powder form with an adhesive and applying it to a synthetic resin such as PET. According to this, the magnetic layer 53 having a relative permeability of about 40 can be obtained.

The insulating layer 54 is formed of a material having electrical insulation, and is a layer that electrically insulates the rechargeable battery 24 and the portable terminal 1 from other than the electrode terminals 41c and 42c (see FIG. 4A).
That is, by providing the insulating layer 54, the electrical insulation of the rechargeable battery 24 can be ensured.
As the insulating layer 54, it is preferable to use PET or polyamide resin. According to this, since the strength is high, in addition to electrical insulation, the breakage resistance of the rechargeable battery 24 against a force such as an external impact can be improved.

  In addition, when the magnetic layer 53 fulfills the function of the metal foil layer 52 by being light-shielding, moisture-proof, and strong, the metal foil layer 52 may not be provided in the exterior portion 50. Further, when the magnetic layer 53 fulfills the function of the insulating layer 54 by having electrical insulation, the insulating layer 54 may not be provided in the exterior portion 50.

With reference to FIG. 4 (A) and FIG. 6 (A), (B), the sealing by the exterior part 50 of the charging / discharging part 40 in the rechargeable battery 24 is described.
FIG. 6A is an example of a method for sealing the charging / discharging unit 40 by the exterior unit 50 in the rechargeable battery 24. FIG. 6B is another example of the sealing method of the charge / discharge part 40 by the exterior part 50 in the rechargeable battery 24.

  In sealing the charging / discharging part 40 by the exterior part 50, the adhesive layer 51 side of the exterior part 50 is disposed on the inner side, and the insulating layer 54 side is disposed on the outer side. As shown in FIG. The end portions are bonded together to form an adhesive portion 50a. Thereby, since the exterior part 50 becomes cylindrical, the charging / discharging part 40 is accommodated in this cylindrical inside. Adhesive portions 50b and 50c are formed by bonding the adhesive layer 51 and bonding the open end of the exterior portion 50. Thereby, the charging / discharging part 40 can be accommodated in the inside and the exterior part 50 can be sealed.

  Further, the adhesive layer 51 side of the exterior part 50 is disposed on the inner side and the insulating layer 54 side is disposed on the outer side, and the charge / discharge part 40 is sandwiched between the two exterior parts 50 as shown in FIG. The charge / discharge part 40 can be accommodated in the interior and the exterior part 50 can be sealed also by combining 51 and adhering the four sides of the exterior part 50.

  Furthermore, the adhesive layer 51 side of the exterior part 50 is arranged on the inner side and the insulating layer 54 side is arranged on the outer side. As shown in FIG. The charge / discharge part 40 is sandwiched between the adhesive layers 51 and the three sides of the exterior part 50 are adhered to each other, so that the charge / discharge part 40 can be accommodated inside and the exterior part 50 can be sealed. .

  As shown in FIGS. 6A and 6B, between the exterior portion 50 and the electrode terminals 41c and 42c, a metal is melted so as to cover the electrode terminals 41c and 42c at the end of the exterior portion 50. It is preferable to provide a synthetic resin 55 that is easy to wear. Synthetic resin is usually used for the adhesive layer 51, and since it is generally difficult to bond the synthetic resin and the metal, the rechargeable battery 24 has insufficient adhesion between the exterior portion 50 and the electrode terminals 41c and 42c. There is a case. However, by doing so, the exterior portion 50 and the electrode terminals 41c and 42c are securely bonded to each other, so that the charge / discharge portion 40 is sealed and the positive electrode terminal 41c and the negative electrode terminal 42c are in contact with each other. Thus, the rechargeable battery 24 can be prevented from being short-circuited.

With reference to FIG. 7, the formation of a magnetic field in the RFID will be described.
FIG. 7 is a diagram illustrating a magnetic field formation state in the RFID. FIG. 7 schematically shows the positional relationship among the reader / writer device 37, the rechargeable battery 24, and the loop antenna 31 that are communication objects.

  In the RFID, the magnetic field radiated from the reader / writer device 37 is coupled to the loop antenna 31 disposed around the rechargeable battery 24 through the rechargeable battery cover 25 as the magnetic field 61a. Thereby, an electromotive force is generated in the IC chip 32 (see FIG. 2) connected to the loop antenna 31, and wireless communication is performed between the reader / writer device 37 and the IC chip 32.

A part of the magnetic field formed by the reader / writer device 37 enters the exterior portion 50 of the rechargeable battery 24 like the magnetic field 61b. The magnetic field 61 b passes through the insulating layer 54 of the exterior part 50 and enters the magnetic layer 53. As described above, the relative permeability of the magnetic layer 53 is as large as about 40 when a ferrite-based magnetic material is used, for example. On the other hand, the relative magnetic permeability of the metal foil layer 52 disposed inside the magnetic layer 53 is about 1 for an aluminum foil, for example. Since the magnetic field does not easily enter the material having a low relative permeability through the material having a high relative permeability, the magnetic field 61b does not enter the metal foil layer 52 from the magnetic layer 53, and the rechargeable battery 24 travels around the magnetic layer 53. To the outside.
Thus, according to the rechargeable battery 24 of the present invention, the magnetic field 61b is such as the metal foil layer 52 in the exterior part 50 of the rechargeable battery 24 and the positive electrode current collector 41b and the negative electrode current collector 42b in the charge / discharge part 40. Since it is difficult to enter the metal portion, it is possible to suppress the generation of eddy current in the rechargeable battery 24.
Therefore, the mobile terminal 1 according to the present invention can perform good wireless communication via a magnetic field.

  Further, in the mobile terminal 1 according to the present invention, as shown in FIG. 7, the magnetic field 61 b passing through the magnetic layer 53 to the outside reaches the loop antenna 31, thereby improving the magnetic field gain and improving the wireless communication characteristics. Can be improved.

Further, a part of the magnetic field formed by the reader / writer device 37 and entering the exterior portion 50 of the rechargeable battery 24 passes through the magnetic layer 53 of the exterior portion 50 as the magnetic field 61c, and the metal foil layer 52 and the rechargeable battery 24. Intrude inside. The magnetic field 61c penetrates into a metal member such as the metal foil layer 52 in the exterior part 50 of the rechargeable battery 24 and the positive electrode current collector 41b and the negative electrode current collector 42b in the charge / discharge part 40 to generate an eddy current 70, The eddy current 70 generates a new magnetic field 71.
However, since the magnetic layer 53 is disposed between the new magnetic field 71 generated by the eddy current 70 and the loop antenna 31 and the outside is covered with the insulating layer 54 and the hollow whose relative permeability is lower than that of the magnetic layer 53, It does not reach the loop antenna 31 but flows in the magnetic layer 53. Therefore, the influence on the loop antenna 31 by the new magnetic field 71 generated by the eddy current 70 is reduced. Accordingly, since the disturbance of the magnetic field coupled to the loop antenna 31 and the reader / writer device 37 due to the new magnetic field 71 is suppressed, the mobile terminal 1 can perform good wireless communication via the magnetic field.

As described above, in the mobile terminal device 1, even when the loop antenna 31 is arranged around the rechargeable battery 24, good wireless communication can be performed via the magnetic field.
In the above embodiment, the loop antenna 31 is provided so as to surround the rechargeable battery 24, but the present invention is not limited to this. For example, even when the loop antenna 31 or an antenna having another shape is disposed around the rechargeable battery 24 by being disposed in another place that does not surround the rechargeable battery 24, the portable terminal of the present invention. 1, good wireless communication is possible via a magnetic field.

  In the above embodiment, the electronic device has been described as the portable terminal 1, but the present invention is not limited to this, and for example, other electronic devices such as PAD (Personal Digital Assistant) that performs wireless communication via a magnetic field. Is also applicable.

FIG. 1 is a perspective view showing an inner surface side of a portable terminal according to the present invention in an opened state. FIG. 2 is an internal exploded view of a lower housing in the portable terminal according to the present invention. FIG. 3 is a functional block diagram illustrating functions of the RFID unit. 4A is a perspective view of the rechargeable battery, and FIG. 4B is a diagram schematically illustrating the internal structure of the rechargeable battery. FIG. 5 is a cross-sectional view of the exterior portion. FIG. 6A is an example of a method for sealing a charge / discharge part by an exterior part in the rechargeable battery, and FIG. 6B is another example of a method for sealing the charge / discharge part by the exterior part in the rechargeable battery. FIG. 7 is a diagram illustrating a magnetic field formation state in the RFID.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Portable terminal device 2 ... Upper housing | casing 3 ... Lower housing | casing 4 ... Hinge part 24 ... Rechargeable battery 30 ... RFID part, 31 ... Loop antenna, 32 ... IC chip 37 ... Reader / writer apparatus 41 ... Positive electrode part 41a ... positive electrode active material, 41b ... positive electrode current collector, 41c ... electrode terminal 42 ... negative electrode part, 42a ... negative electrode active material, 42b ... negative electrode current collector, 42c ... electrode terminal 43 ... fixed electrolyte, 44 ... separator 50 ... Exterior part, 51 ... adhesive layer, 52 ... metal foil layer, 53 ... magnetic layer, 54 ... insulating layer

Claims (6)

An electronic device that performs wireless communication with a communication object via a magnetic field,
A secondary battery for supplying power to an electric circuit of the electronic device;
An antenna for the wireless communication disposed around the secondary battery,
The secondary battery is
A charge / discharge unit comprising a metal positive electrode current collector coated with a positive electrode active material, a metal negative electrode current collector coated with a negative electrode active material, and an electrolyte;
An exterior part that seals the charge / discharge part,
The exterior part is
An adhesive layer;
An electronic apparatus comprising: a magnetic shield that eliminates the influence of the magnetic field disposed outside the adhesive layer. The electronic device according to claim 1, wherein the exterior portion includes a metal layer between the adhesive layer and the magnetic shield. The electronic device according to claim 1, wherein the exterior portion includes an insulating layer outside the magnetic shield. A charge / discharge unit comprising a metal positive electrode current collector coated with a positive electrode active material, a metal negative electrode current collector coated with a negative electrode active material, and an electrolyte;
An exterior part that seals the charge / discharge part,
The exterior part is
An adhesive layer;
A secondary battery comprising: a magnetic shield disposed outside the adhesive layer. The secondary battery according to claim 4, wherein the exterior portion includes a metal layer between the adhesive layer and the magnetic shield. The secondary battery according to claim 4, wherein the exterior portion has an insulating layer outside the magnetic shield.

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