Non-contact charging module, electronic apparatus, and non-contact charging apparatus

Abstract

This non-contact charging module can be suitably used by suppressing a change of an L value of a coil that is provided in the non-contact charging module, and achieves size reduction, even in the cases where a magnet that is provided in the other non-contact charging module is used or not used. The module is characterized in that: the module is provided with a primary side coil (21a) wherein a conducting line is wound in a substantially rectangular shape, and a magnetic sheet (51) that is provided with a surface on which the primary side coil (21a) is placed; and that a substantially rectangular-shaped hollow portion of the primary side coil (21a) has the short side thereof shorter than the diameter of a circular magnet (30a), and the long side thereof longer than the diameter of the circular magnet (30a).

Description

TECHNICAL FIELD

The present invention relates to a non-contact charging module having a planar coil portion and a magnetic sheet, and an electronic device and a non-contact charging device.

BACKGROUND ART

Recently, there have been utilized a number of apparatuses with a main unit which can be charged in a non-contact manner by a charger. In such apparatuses, non-contact charging modules are respectively provided at a charger side and a main unit side and electromagnetic induction is caused between both modules so that power is transmitted from the charger side to the main unit side. It has been also proposed to apply a mobile terminal device or the like as the main unit.

There is a need for thinner and smaller main unit and charger for the mobile terminal device, or the like. To respond to such a need, as disclosed in Patent Literature 1, it is considered to provide a planar coil portion and a magnetic sheet, which serve as a transmission side non-contact charging module and a reception side non-contact charging module.

CITATION LIST

Patent Literature

• PTL 1
• Japanese Patent Application Laid-Open No. 2006-42519

SUMMARY OF INVENTION

Technical Problem

Such types of non-contact charging modules require to position a primary side non-contact charging module (transmission side non-contact charging module) and a secondary side non-contact charging module (reception side non-contact charging module) accurately to efficiently cause electromagnetic induction for power transmission.

In order to position the primary side non-contact charging module (transmission side non-contact charging module) and the secondary side non-contact charging module (reception side non-contact charging module) accurately, one method is to use a magnet, an example of which is a method shown in FIG. 11. FIG. 11 illustrates a non-contact charging module (for example, a secondary side non-contact charging module) brought into position by a magnet provided at the other non-contact charging module (for example, a primary side non-contact charging module). In this method, the primary side non-contact charging module and the secondary side non-contact charging module are positioned by a magnet provided at at least one of the modules so that the magnets provided at the both modules or the magnet provided at one module and a magnetic sheet provided at the other module attract each other.

Further, there is another method in which the primary side non-contact charging module and the secondary side non-contact charging module are positioned accurately without utilizing a magnet.

For example, there is a method in which the primary side non-contact charging module and the secondary side non-contact charging module are physically (as a shape) and forcibly positioned by fitting a protruding portion formed on a charging surface of a charger provided with the primary side non-contact charging module into a recessed portion formed at an electronic device provided with the secondary side non-contact charging module. There is still another method in which the primary side non-contact charging module detects a position of a coil of the secondary side non-contact charging module to thereby automatically move a coil of the primary side non-contact charging module to the position of the coil of the secondary side non-contact charging module. There is yet another method in which a large number of coils are provided at a charger to thereby enable charging even if a mobile device is placed at anywhere on a charging surface of the charger.

However, L values of the coils provided at the respective non-contact charging modules largely vary between a case where a magnet is used for positioning the primary side non-contact charging module and the secondary side non-contact charging module and a case where a magnet is not used. Resonant frequency of the electromagnetic induction for power transmission is determined by utilizing the L values of the coils provided at the respective non-contact charging modules.

Accordingly, there is a problem in that it is difficult to share the non-contact charging modules between a case where a magnet is used for positioning the primary side non-contact charging module and the secondary side non-contact charging module and a case where a magnet is not used.

Therefore, an object of the present invention is to provide a non-contact charging module which can suppress variation of an L value of a coil provided at the non-contact charging module in both of a case where a magnet provided at the other non-contact charging module serving as a counterpart for power transmission is used and a case where a magnet is not used for positioning a primary side non-contact charging module and a secondary side non-contact charging module, and which can be suitably used in both of a case where a magnet is used and a case where a magnet is not used, and which can realize downsizing, and also to provide an electronic device and a non-contact charging device.

Solution to Problem

A non-contact charging module according to an aspect of the present invention is configured to be positioned with another non-contact charging module using a circular magnet or without using the circular magnet for positioning, the circular magnet being provided at the other non-contact charging module, the non-contact charging module including: a planar coil portion including a conductive wire wound in a substantially rectangular shape; and a magnetic sheet provided with a surface on which the planar coil portion is placed, in which the planar coil portion includes a substantially rectangular hollow portion that has a short side shorter than a diameter of the circular magnet and a long side longer than the diameter of the circular magnet.

Advantageous Effects of Invention

According to the present invention, it is possible to provide a non-contact charging module which can suppress variation of an L value of a coil provided at the non-contact charging module in both of a case where a magnet provided at the other non-contact charging module serving as a counterpart for power transmission is used and a case where a magnet is not used for positioning a primary side non-contact charging module and a secondary side non-contact charging module, and which can be suitably used in both of a case where a magnet is used and a case where a magnet is not used, and which can realize downsizing and to provide a non-contact charging device using the non-contact charging module.

BRIEF DESCRIPTION OF DRAWINGS

FIG. 1 is a block diagram illustrating a non-contact power transmission device according to an embodiment of the present invention;

FIG. 2 illustrates a configuration of a non-contact charger according to the embodiment of the present invention;

FIG. 3 illustrates a primary side non-contact charging module according to the embodiment of the present invention;

FIGS. 4A to 4D illustrate in detail the primary side non-contact charging module according to the embodiment of the present invention;

FIG. 5 illustrates a configuration of a mobile terminal device according to the embodiment of the present invention;

FIG. 6 illustrates a secondary side non-contact charging module according to the embodiment of the present invention;

FIGS. 7A to 7D illustrate in detail the secondary side non-contact charging module according to the embodiment of the present invention;

FIGS. 8A to 8D illustrate a relationship between the primary side non-contact charging module provided with a magnet and the secondary side non-contact charging module;

FIG. 9 illustrates a relationship between a coil inner diameter and an L value of the coil;

FIGS. 10A and 10B illustrate a positional relationship between a secondary side coil wound in a rectangular shape and a secondary side coil wound in a circular shape, and a magnet provided at the primary side non-contact charging module; and

FIG. 11 illustrates a non-contact charging module (for example, the secondary side non-contact charging module) brought into position using a magnet provided at the other non-contact charging module (for example, the primary side non-contact charging module).

DESCRIPTION OF EMBODIMENTS

Embodiment

An embodiment of the present invention will be described below with reference to the accompanying drawings.

(Regarding a Non-Contact Charging System)

FIG. 1 is a block diagram illustrating a non-contact power transmission device according to an embodiment of the present invention.

The non-contact power transmission device includes primary side non-contact charging module 41 (transmission side non-contact charging module) and secondary side non-contact charging module 42 (reception side non-contact charging module), and transmits power from primary side non-contact charging module 41 to secondary side non-contact charging module 42 by utilizing the action of electromagnetic induction. This non-contact power transmission device is used for transmitting power of approximately 5 W or lower and has a frequency of power transmission between approximately 110 and 205 kHz. Primary side non-contact charging module 41 is mounted on, for example, a charger, and secondary side non-contact charging module 42 is mounted on, for example, a mobile phone, a digital camera, a PC, or the like.

Primary side non-contact charging module 41 includes primary side coil 21a, magnetic sheet 51, a resonant capacitor (not shown) and power input section 71. Power input section 71 is connected to commercial power source 300 as an external power source to receive supply of power of approximately 100 to 240V, converts the power into predetermined current A (DC 12V, 1 A) and supplies the current to primary side coil 21a. Primary side coil 21a generates a magnetic field according to its shape, the number of turns, and the supplied current. The resonant capacitor is connected to primary side coil 21a and determines a resonant frequency of the magnetic field generated from primary side coil 21a according to a relationship with primary side coil 21a. The action of electromagnetic induction from primary side non-contact charging module 41 to secondary side non-contact charging module 42 occurs by this resonant frequency.

Meanwhile, secondary side non-contact charging module 42 includes secondary side coil 21b, magnetic sheet 52, a resonant capacitor (not shown), rectifier circuit 72 and power output section 82. Secondary side coil 21b receives the magnetic field generated from primary side coil 21a, converts the magnetic field into predetermined current B by electromagnetic induction action and outputs predetermined current B to the outside of secondary side non-contact charging module 42 via rectifier circuit 72 and power output section 82. Rectifier circuit 72 rectifies predetermined current B which is an alternating current to convert the current into predetermined current C (DC 5V, 1.5 A) which is a direct current. Further, power output section 82 is a unit for outputting power to the outside of secondary side non-contact charging module 42, through which power is supplied to electronic device 200 connected to secondary side non-contact charging module 42.

It should be noted that, as shown in FIG. 1, it is not necessary that both of primary side coil 21a of primary side non-contact charging module 41 and secondary side coil 21b of secondary side non-contact charging module 42 be a planar coil wound in a substantially rectangular shape. That is, though described in detail later, because the present invention is intended to stabilize transmission efficiency whether a magnet is provided or not provided at a counterpart (secondary side non-contact charging module 42 for primary side non-contact charging module 41, and primary side non-contact charging module 41 for secondary side non-contact charging module 42), a substantially rectangular coil may be used in only one of the non-contact charging modules.

[Regarding a Non-Contact Charger and a Primary Side Non-Contact Charging Module]

A case where primary side non-contact charging module 41 is mounted on a non-contact charger will be described.

FIG. 2 illustrates a configuration of a non-contact charger according to the embodiment of the present invention. It should be noted that FIG. 2 illustrates the configuration so that the inside of the non-contact charger can be seen.

Non-contact charger 400 which transmits power by utilizing the action of electromagnetic induction has primary side non-contact charging module 41 in a casing that forms the exterior of non-contact charger 400.

Non-contact charger 400 has a plug 401 which is inserted into outlet 301 of commercial power source 300 provided indoors or outdoors. Non-contact charger 400 can receive power supply from commercial power source 300 by plug 401 being inserted into outlet 301.

Non-contact charger 400 is provided on table 501, and primary side non-contact charging module 41 is arranged near surface 402 of non-contact charger 400 which is an opposite side of a surface of the table. A primary flat surface of primary side coil 21a in primary side non-contact charging module 41 is arranged parallel to surface 402 of non-contact charger 400 which is an opposite side of the surface of the table. This configuration makes it possible to secure an area for power reception operation of the electronic device provided with secondary side non-contact charging module 42. It should be noted that non-contact charger 400 may be provided on a wall surface, in which case non-contact charger 400 is arranged near a surface which is an opposite side of the wall surface.

Further, primary side non-contact charging module 41 may have magnet 30a to be used for performing positioning with secondary side non-contact charging module 42, in which case magnet 30a is arranged in a hollow portion positioned in a central area of primary side coil 21a.

Primary side non-contact charging module 41 will be described.

FIG. 3 illustrates a primary side non-contact charging module according to the embodiment of the present invention and illustrates a case where a primary side coil is a substantially rectangular coil.

Primary side non-contact charging module 41 includes primary side coil 21a which is a conductive wire wound in a spiral manner to form a substantially rectangular shape, and magnetic sheet 51 provided to face a surface of primary side coil 21a.

As shown in FIG. 3, a planar coil portion of primary side non-contact charging module 41 includes primary side coil 21a which is a conductor wound toward an outer direction in a spiral manner so as to form a substantially rectangular shape on the surface, and terminals 22a and 23a which are provided at both ends of primary side coil 21a as current supply portions. That is, terminals 22a and 23a which are current supply portions supply a current from commercial power source 300 which is an external power source to primary side coil 21a. Primary side coil 21a is formed of a conductive wire wound on a plane in a parallel manner, and a surface formed by the coil is referred to as a coil surface. It should be noted that a thickness direction is a direction in which primary side coil 21a and magnetic sheet 51 are stacked.

Magnetic sheet 51 includes flat portion 31a on which primary side coil 21a is mounted, central portion 32a which is located at a center of flat portion 31a and which corresponds to a hollow area of primary side coil 21a, and linear recessed portion 33a into which part of a drawn wire of primary side coil 21a is inserted. Central portion 32a may take any form among a protruding shape, a flat shape, a recessed shape and a through hole relative to flat portion 31a. If central portion 32a has a protruding shape, it is possible to strengthen a magnetic flux of primary side coil 21a. If central portion 32a is flat, central portion 32a can be easily manufactured, and primary side coil 21a can be easily mounted thereon, and it is possible to maintain a well-balanced relationship between the influence of a magnet for positioning and an L value of primary side coil 21a, which will be described later. If central portion 32a has a recessed shape or is a through hole, it is possible to suppress the influence of a magnet for positioning. That is, it is possible to physically keep a distance between magnet 30b provided at secondary side non-contact charging module 42 and magnetic sheet 51, so that it is possible to prevent reduction of magnetic permeability as a result of magnetic sheet 51 being saturated by magnet 30b. Accordingly, it is possible to prevent an L value of primary side coil 21a from varying according to the presence or absence of magnet 30b. Further, the recessed portion, the protruding portion or the through hole may be formed in the same shape and to have the same size as the hollow portion, or may be formed in a different shape and may be smaller than the hollow portion.

In primary side non-contact charging module 41 in this embodiment, primary side coil 21a is wound toward outside from a substantially rectangular hollow portion of approximately 12 mm×18 mm, and its outer end forms a rectangle of approximately 18 mm×23 mm. That is, primary side coil 21a is wound in a substantially rectangular doughnut shape. It should be noted that “substantially rectangular” refers to a rectangle that may include R (curved portion) at four corners.

Further, by winding the conductive wire so as to keep space from each other, floating capacitance between an upper stage conductive wire and a lower stage conductive wire becomes small, so that it is possible to suppress alternating-current resistance of primary side coil 21a. Further, by winding the conductive wire so as to reduce space, it is possible to reduce the thickness of primary side coil 21a.

Further, primary side non-contact charging module 41 may have magnet 30a to be used for performing positioning with secondary side non-contact charging module 42. It is defined by the standards (WPC) that magnet 30a should have a circular shape and should have a diameter of 15.5 mm or less and so on. Magnet 30a has a coin shape and has to be arranged so that its center matches a central winding axis of primary side coil 21a in order to reduce influence of magnet 30a on primary side coil 21a. When magnet 30a is provided, it is preferable to provide a hollow portion larger than magnet 30a.

When primary side non-contact charging module 41 has magnet 30a, as the first method for arranging magnet 30a, there is a method in which magnet 30a is arranged on an upper surface of central portion 32a of magnetic sheet 51. Further, as the second method for arranging magnet 30a, there is a method in which magnet 30a is arranged in place of central portion 32a of magnetic sheet 51. In the second method, because magnet 30a is arranged in a hollow area of primary side coil 21a, it is possible to make primary side non-contact charging module 41 smaller.

When a magnet is not utilized for positioning primary side non-contact charging module 41 and secondary side non-contact charging module 42, magnet 30a shown in FIG. 3 is not required.

Influence of a magnet on power transmission efficiency of the non-contact charging module will be described. Generally, a magnet is provided inside a hollow portion of built-in primary side coil 21a or secondary side coil 21b in at least one of the primary side non-contact charging module and the secondary side non-contact charging module. By this means, it is possible to bring the magnet and the magnet or to bring the magnet and magnetic sheet 51 as close as possible to each other and it is possible to bring the primary side coil and the secondary side coil close to each other. The magnet has a circular shape. In this embodiment, the magnet has a diameter of approximately 15.5 mm (approximately 10 mm to 20 mm), and a thickness of approximately 1.5 to 2 mm. Further, a neodymium magnet is used, and strength may be approximately 75 mT to 150 mT. In this embodiment, because there is an interval of approximately 2 to 5 mm between the coil of primary side non-contact charging module and the coil of secondary side non-contact charging module, it is possible to position the non-contact charging modules with a magnet having such a degree of strength.

When a magnetic flux is generated between primary side coil 21a and secondary side coil 21b to transmit power, if a magnet exists between or around primary side coil 21a and secondary side coil 21b, the magnetic flux extends while avoiding the magnet. Alternatively, a magnetic flux which penetrates inside the magnet causes an eddy current or heat inside the magnet, which becomes a loss. Further, as a result of the magnet being arranged near the magnetic sheet, magnetic permeability of the magnetic sheet near the magnet is lowered. Accordingly, magnet 30a provided at primary side non-contact charging module 41 reduces L values of both primary side coil 21a and secondary side coil 21b. As a result, transmission efficiency between the non-contact charging modules is reduced.

FIGS. 4A to 4D illustrate in detail the primary side non-contact charging module according to the embodiment of the present invention. FIG. 4A illustrates an upper surface of the primary side non-contact charging module, FIG. 4B illustrates a cross-section taken along A-A of the primary side non-contact charging module in FIG. 4A, FIG. 4C illustrates a cross-section taken along B-B of the primary side non-contact charging module in FIG. 4A when a linear recessed portion is provided, and FIG. 4D illustrates a cross-section taken along B-B of the primary side non-contact charging module in FIG. 4A when a slit is provided. It should be noted that FIG. 4A and FIG. 4B illustrate a case where magnet 30a is not provided, and if a magnet is provided, magnet 30a indicated by the dotted line is provided.

Primary side coil 21a is formed to have two stages in a thickness direction from a winding start portion positioned in the central area of primary side coil 21a to terminal 23a and to have one stage in the remaining area in order to realize thinner non-contact charger 400 on which primary side non-contact charging module 41 is mounted. In addition, the conductive wire is wound so as to keep space between the upper stage conductive wire and the lower stage conductive wire, thereby reducing floating capacitance between the upper stage conductive wire and the lower stage conductive wire, so that it is possible to suppress alternating-current resistance of primary side coil 21a.

When conductive wires are stacked to extend primary side coil 21a in a thickness direction of primary side non-contact charging module 41, it is possible to increase a current flowing through primary side coil 21a by increasing the number of turns of primary side coil 21a. When the conductive wires are stacked, by winding the conductive wire so as to reduce space between the upper stage conductive wire and the lower stage conductive wire, it is possible to increase a current flowing through primary side coil 21a while suppressing the thickness of primary side coil 21a. Further, by stacking the conductive wire in the thickness direction, because magnetic sheet 51 is positioned away from secondary side non-contact charging module 42 though primary side coil 21a is positioned close to secondary side non-contact charging module 42, it is possible to suppress influence of magnet 30b when magnet 30b is provided at secondary side non-contact charging module 42. Further, this can be applied to a relationship between magnet 30a of primary side non-contact charging module 41, and secondary side coil 21b and magnetic sheet 52. Influence of magnets 30a and 30b will be described later.

While in this embodiment, primary side coil 21a is formed using a conductive wire having a circular cross section, it is also possible to use a conductive wire having a rectangular or polygonal cross section. When a conductive wire having a circular cross section is used, because a gap occurs between adjacent parts of the conductive wire, floating capacitance between the parts of the conductive wire becomes small, so that it is possible to suppress alternating-current resistance of primary side coil 21a.

Further, compared to a case where the conductive wire of primary side coil 21a is wound in two stages in a thickness direction, alternating-current resistance of primary side coil 21a becomes lower and transmission efficiency can increase when the conductive wire is wound in one stage. This is because, when the conductive wire is wound in two stages, floating capacitance occurs between the upper stage conductive wire and the lower stage conductive wire. Accordingly, it is preferable to wind the conductive wire in one stage in as large portion as possible rather than to wind the conductive wire in two stages in the whole primary side coil 21a. Further, by winding the conductive wire in one stage, it is possible to make primary side non-contact charging module 41 thinner. Further, when planar coil portion 2 includes two conductive wires, because the two conductive wires are electrically connected by a solder, or the like, at the portions of terminals 22a and 23a, the two conductive wires may be formed as if it were one thick conductive wire. The two conductive wires may be wound side by side in parallel to a coil surface or may be wound side by side vertically with respect to the coil surface. That is, when the conductive wires are wound in parallel to the coil surface, the two conductive wires are wound around the same central axis in a planar shape, and one conductive wire is put between the other conductive wires in a radial direction. By electrically bonding the two conductive wires at the portions of terminals 22a and 23a in this way so that the two conductive wires function as if it were one conductive wire, it is possible to suppress the thickness while maintaining the same cross-sectional area. That is, it is possible to obtain a cross-sectional area of a conductive wire having a diameter of 0.25 mm with two conductive wires having a diameter of 0.18 mm, for example. Accordingly, while if one conductive wire having a diameter of 0.25 mm is used, the thickness of one turn of primary side coil 21a is 0.25 mm and the width of primary side coil 21a in a radial direction is 0.25 mm, if two conductive wires having a diameter of 0.18 mm are used, the thickness of one turn of primary side coil 21a is 0.18 mm and the width in a radial direction is 0.36 mm. It should be noted that the thickness direction is a direction in which primary side coil 21a and magnetic sheet 51 are stacked. Further, the conductive wires are overlapped in two stages in the thickness direction at only part at the central side of primary side coil 21a, and the conductive wires may be formed in one stage at the remaining outer portion. Further, if the conductive wires are wound vertically with respect to the coil surface, while the thickness of primary side non-contact charging module 41 increases, because the cross-sectional area of the conductive wires virtually increases, it is possible to increase a current flowing through primary side coil 21a and to easily secure a sufficient number of turns. It should be noted that in this embodiment, primary side coil 21a includes conductive wires of approximately 0.18 to 0.4 mm, and among them, it is preferable to use a conductive wire of 0.25 to 0.35 mm for primary side coil 21a of primary side non-contact charging module 41.

Because the alternating-current resistance of primary side coil 21a is low, it is possible to prevent a loss at primary side coil 21a, and by increasing an L value, it is possible to improve power transmission efficiency of primary side non-contact charging module 41 which depends on the L value.

While terminals 22a and 23a may be provided close to each other or separate from each other, primary side non-contact charging module 41 can be easily mounted if terminals 22a and 23a are provided separate from each other.

Magnetic sheet 51 which is provided to improve power transmission efficiency of non-contact charging utilizing electromagnetic induction action, includes planar portion 31a, central portion 32a which is a center of coil 21, and linear recessed portion 33a. Further, if magnet 30a for positioning primary side non-contact charging module 41 and secondary side non-contact charging module 42 is provided, magnet 30a may be provided above central portion 32a or may be provided in place of central portion 32a.

Further, it is possible to use a Ni—Zn ferrite sheet, a Mn—Zn ferrite sheet, a Mg—Zn ferrite sheet, or the like as magnetic sheet 51. Magnetic sheet 51 may be formed as a single layer structure or as a structure in which a plurality of layers of the same material are laminated in a thickness direction, or may be formed by laminating a plurality of layers of different magnetic sheets 51 in the thickness direction. It is preferable to use magnetic sheet 51 having at least magnetic permeability of 250 or higher and saturation magnetic flux density of 350 mT or higher.

Further, it is possible to use an amorphous metal as magnetic sheet 51. When a ferrite sheet is used as magnetic sheet 51, the alternating-current resistance of primary side coil 21a is advantageously reduced, while, when an amorphous metal is used as the magnetic sheet, it is possible to make primary side coil 21a thinner.

Magnetic sheet 51 to be used for primary side non-contact charging module 41 has a size within approximately 50×50 mm, and has a thickness of approximately 3 mm or less. In this embodiment, magnetic sheet 51 is a substantially rectangle of approximately 20 mm×25 mm. It is preferable that magnetic sheet 51 is formed so as to have about the same size as or larger than the outer circumference end of primary side coil 21a. Further, the shape of magnetic sheet 51 may be a circle, a rectangle, a polygon, or a rectangle or a polygon having large curves at four corners.

Linear recessed portion 33a or slit 34a store the conductive wire from a coil winding start portion (innermost portion of the coil) to a terminal. By this means, it is possible to prevent the conductive wire from the coil winding start portion to the terminal from overlapping in the thickness direction of primary side coil 21a and suppress the thickness of primary side non-contact charging module 41. Further, by setting the size of linear recessed portion 33a or slit 34a to a minimum size which can store the conductive wire from the coil winding start portion to the terminal, it is possible to suppress occurrence of a leakage flux. Further, as shown in FIG. 3, linear recessed portion 33a or slit 34a does not have to be extended in parallel to a long side direction of primary side coil 21a, but may be parallel to a short side direction. Further, the cross-sectional shape of linear recessed portion 33a does not have to be a rectangle, but may be an arc or a round.

Linear recessed portion 33a or slit 34a is formed so as to be substantially perpendicular to an end of magnetic sheet 51 which intersects with an end of linear recessed portion 33a or slit 34a, and so as to overlap with an outline (sides of a substantially rectangular hollow portion) of the hollow portion. By forming linear recessed portion 33a or slit 34a in this way, it is possible to form terminals 22a and 23a without bending the conductive wire at the winding start portion. The length of linear recessed portion 33a or slit 34a depends on the size of the hollow portion of coil 21 and, in this embodiment, is approximately 5 mm to 15 mm.

Further, linear recessed portion 33a or slit 34a may be formed at a portion where the end of magnetic sheet 51 comes closest to the winding start portion of primary side coil 21a located at the end of the hollow portion. By this means, it is possible to minimize the area for forming linear recessed portion 33a or slit 34a and improve transmission efficiency of the non-contact power transmission device. In this case, the length of linear recessed portion 33a or slit 34a is approximately 5 mm to 10 mm. An inner end of linear recessed portion 33a or slit 34a is connected to central portion 32a for either arrangement.

Further, linear recessed portion 33a or slit 34a may be arranged in other manners. That is, because it is preferable to form primary side coil 21a to have a single stage structure, it is conceivable to adopt an arrangement where all the turns in a radial direction of primary side coil 21a are formed in one stage structure, or an arrangement where part of the turns is formed in a single stage structure and the other part is formed in a two-stage structure. Accordingly, while it is possible to draw one of terminals 22a and 23a from an outer periphery of primary side coil 21a, the other terminal has to be drawn from the inside. If a portion where primary side coil 21a is wound certainly overlaps with a portion from winding end of primary side coil 21a to terminal 22a or 23a in a thickness direction, linear recessed portion 33a or slit 34a may be provided at the overlapped portion.

If linear recessed portion 33a is used, because a through hole or a slit is not provided at magnetic sheet 51, it is possible to prevent leakage of a magnetic flux and improve power transmission efficiency of primary side non-contact charging module 41. Meanwhile, when slit 34a is used, magnetic sheet 51 can be easily formed. If linear recessed portion 33a is used, the cross-sectional shape is not limited to a rectangle, but may be an arc or a round.

Then, an influence of a magnet on primary side non-contact charging module 41 and secondary side non-contact charging module 42 which will be described later will be described. Secondary side coil 21b inside secondary side non-contact charging module 42 receives a magnetic field generated by primary side non-contact charging module 41 to perform power transmission. If a magnet is arranged around primary side coil 21a and secondary side coil 21b, the magnetic field may be generated while avoiding the magnet or the magnetic field which tries to pass through the magnet may disappear. Further, magnetic permeability at a portion close to the magnet of magnetic sheet 51 is reduced. That is, the magnetic field is weakened by the magnet. Accordingly, in order to minimize the magnetic field weakened by the magnet, it is necessary to take some measures such as separating primary side coil 21a and secondary side coil 21b and the magnet or providing magnetic sheet 51 which is less likely to be influenced by the magnet.

Because primary side non-contact charging module 41 is used at a fixed terminal which is a power supply transmission side, there is extra space which can be occupied by primary side non-contact charging module 41 in the fixed terminal. Further, because a current flowing through primary side coil 21a of primary side non-contact charging module 41 is large, insulation property of magnetic sheet 51 is important. If magnetic sheet 51 is a conductive sheet, a large current flowing through primary side coil 21a may be transmitted to other parts via magnetic sheet 51.

In consideration of the above, magnetic sheet 51 mounted on primary side non-contact charging module 41 is preferably a (insulation) Ni—Zn ferrite sheet having a thickness of 400 μm or greater (preferably, 600 μm to 1 mm), magnetic characteristic of magnetic permeability of 250 or higher, and saturation magnetic flux density of 350 mT or higher. However, it is also possible to use a (conductive) Mn—Zn ferrite sheet if being subject to sufficient insulation processing, in place of the Ni—Zn ferrite sheet.

Further, in primary side non-contact charging module 41, the L value of primary side coil 21a of primary side non-contact charging module 41 largely varies between a case where magnet 30a is used for positioning and a case where magnet 30a is not used. That is, the presence of magnet 30a in primary side non-contact charging module 41 or the presence of a similar magnet in secondary side non-contact charging module 42 inhibits the magnetic flux between the primary side and the secondary side non-contact charging modules, and largely reduces the L value of primary side coil 21a of primary side non-contact charging module 41 by the presence of the magnet. In order to suppress the influence of this magnet 30a, magnetic sheet 51 is preferably formed with a high saturation magnetic flux density material (having saturation magnetic flux density of 350 mT or higher). Because the high saturation magnetic flux density material has property that a magnetic flux is less likely to be saturated even if the magnetic field becomes strong, it is possible to reduce influence of magnet 30a and improve the L value of coil 21 when magnet 30a is used. Accordingly, it is possible to make magnetic sheet 51 thinner.

However, if the magnetic permeability of magnetic sheet 51 becomes too low, the L value of primary side coil 21a is significantly lowered. As a result, the efficiency of primary side non-contact charging module 41 may be degraded. Accordingly, the magnetic permeability of magnetic sheet 51 is preferably at least 250 or higher, more preferably, 350 or higher. Further, while the L value also depends on the thickness of magnetic sheet 51, the thickness of the ferrite sheet may be 400 μm or greater. While the ferrite sheet can reduce the alternating-current resistance of coil 21 compared to the magnetic sheet of the amorphous metal, it is also possible to use the amorphous metal. By using such magnetic sheet 51, even if at least one of primary side non-contact charging module 41 and secondary side non-contact charging module 42 includes a magnet, primary side non-contact charging module 41 can reduce the influence of the magnet.

Further, by using the Mn—Zn ferrite sheet as the ferrite sheet, it is possible to make magnetic sheet 51 even further thinner. That is, a frequency of electromagnetic induction is defined by the standards (WPC) to be approximately 100 kHz to 200 kHz (for example, 120 kHz). In such a low frequency band, the Mn—Zn ferrite sheet exhibits high efficiency. The Ni—Zn ferrite sheet exhibits high efficiency in high frequency.

[Regarding a Mobile Terminal and a Secondary Side Non-Contact Charging Module]

A case where secondary side non-contact charging module 42 is mounted on a mobile terminal device will be described.

FIG. 5 illustrates a configuration of a mobile terminal device according to the embodiment of the present invention, and is a perspective view which illustrates a decomposed mobile terminal device.

Mobile terminal device 520 is composed of liquid crystal panel 521, operation button 522, 5010n table 501 Table

520 Mobile terminal device

521 Liquid crystal panel

522 Operation button

523 Substrate circuit board

524 Battery pack (power holding section)

525, 526 Chassis

Claims

1. A system comprising:

a mobile terminal that includes a rectangular-shaped housing; a circuit board and a battery included in the housing, the circuit board controlling operation of the mobile terminal and supplied with power from the battery; and a first non-contact charging module configured to perform power transmission with included in the housing; and

a second non-contact charging module by electromagnetic induction including a circular magnet and configured to be positioned with the second relative to the first non-contact charging module using a in reference to the circular magnet or without using the circular magnet for positioning, the circular magnet being provided at the second non-contact charging module,

wherein the first non-contact charging module comprising includes:

a planar coil portion including a conductive wire wound in a rectangular shape; and

a magnetic sheet provided with a surface on which the planar coil portion is placed, wherein

the planar coil portion includes a rectangular-shaped hollow portion that has a plurality of short sides shorter than a diameter of the circular magnet and a plurality of long sides longer than the diameter of the circular magnet,

the rectangular-shaped hollow portion of the planar coil portion has an outline in which every short side and long side of the outline is longer than the diameter of the circular magnet, the long side of the outline is in parallel to a long side of the rectangular-shaped housing, and a distance from the long side of the outline to the closest long side of the rectangular-shaped hollow portion defines a width of the planar coil portion that is longer than the short side of the rectangular-shaped hollow portion, and

the circular magnet is positioned on top of the planar coil portion, and

wherein the first non-contact charging module overlaps with the battery and with the circuit board in the housing.

2. A first non-contact charging device comprising the non-contact charging module according to claim 1.

3. The first non-contact charging module system according to claim 1, wherein the rectangular-shaped hollow portion includes a plurality of corner portions, and the circular magnet does not overlap with either the plurality of short sides of the rectangular-shaped hollow portion or the plurality of corner portions of the rectangular-shaped hollow portion.

4. A system comprising:

a mobile terminal that includes a rectangular-shaped housing; a circuit board and a battery included in the housing, the circuit board controlling operation of the mobile terminal and supplied with power from the battery; and a first non-contact charging module configured to perform power transmission with included in the housing; and

a second non-contact charging module by electromagnetic induction including a circular magnet and configured to be positioned with the second relative to the first non-contact charging module using a in reference to the circular magnet or without using the circular magnet for positioning, the circular magnet having a diameter of 15.5 mm at maximum and being provided at the second non-contact charging module,

wherein the first non-contact charging module comprising includes:

a planar coil portion including a conductive wire wound in a rectangular shape; and

a magnetic sheet provided with a surface on which the planar coil portion is placed, wherein

the planar coil portion includes a rectangular-shaped hollow portion that has a short side shorter than 15.5 mm and a long side longer than 15.5 mm,

the rectangular-shaped hollow portion of the planar coil portion has an outline in which every short side and long side of the outline is longer than the diameter of the circular magnet, the long side of the outline is in parallel to a long side of the rectangular-shaped housing, and a distance from the long side of the outline to the closest long side of the rectangular-shaped hollow portion defines a width of the planar coil portion that is longer than the short side of the rectangular-shaped hollow portion, and

the circular magnet is positioned on top of the planar coil portion, and

wherein the first non-contact charging module overlaps with the battery and with the circuit board in the housing.

5. The first non-contact charging module system according to claim 4, wherein the rectangular-shaped hollow portion includes a plurality of corner portions, and each corner portion of the plurality of corner portions includes a curved shape that starts to curve at a distance equal to 30% or less of a corresponding long side and 30% or less of a corresponding short side of the rectangular-shaped hollow portion.

6. The first non-contact charging module system according to claim 5, wherein the diameter of the circular magnet is greater than half a distance of a difference between a length of the long side of the rectangular-shaped hollow portion and the diameter of the circular magnet.

7. The system according to claim 4, wherein a diameter of the conductive wire of the planar coil portion is approximately 0.18 to 0.30 mm.

8. The system according to claim 1, wherein a diameter of the conductive wire of the planar coil portion is approximately 0.18 to 0.30 mm.