JP2000050512A - Charger for portable telephone - Google Patents

Abstract

PROBLEM TO BE SOLVED: To charge a portable telephone without a power source by providing an induction coil for inducing an electromotive force from a magnetic field generated by an electromagnetic wave, and a charging circuit for converting the electromotive force of an AC generated by the coil into a DC to supply the DC to a secondary cell. SOLUTION: When a power drop of a secondary cell of the portable telephone T is informed, the telephone T is installed, for example, near an electromagnetic wave generation source such as a personal computer 12 or the like. Since the telephone T receives the wave generated by the computer 12, a magnetic flux ϕin the field W passing through the coil is changed so that an electromotive force (e) is induced. Since the force (e) is an AC, it is transformed via a transformer in a converter, similarly rectified by a rectifier, and converted into a DC current. The DC current thus generated is supplied to the cell while being controlled in the charging circuit to charge the cell.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a portable telephone capable of charging a secondary battery without a power source.

[0002]

2. Description of the Related Art A portable telephone is equipped with a secondary battery as a power source. If the secondary battery is discharged and the power is reduced, use of the mobile phone is hindered, and it is extremely difficult to continue using the mobile phone as it is. Usually,
When the secondary battery of the mobile phone is discharged, the secondary battery is charged by a separate charger. FIG. 9 shows a conventional charger 51. This charger 51 is operated by a commercial 100 V AC power supply. The frame 1 of the mobile phone is mounted on the mobile phone mounting section 52 of the charger 51.
The mobile phone mounting portion 52 is provided with a charging terminal (not shown), and the charging terminal (not shown) is brought into contact with the charging terminal (not shown) of the mobile phone so that the secondary terminal built in the mobile phone is contacted. The battery is charged.

However, the use of this charger 51 requires a commercial 100 V AC power supply, which not only impairs the mobility of the mobile phone but also makes the mobile phone bulky. When carrying with you,
Its portability is significantly impaired. For this reason, there is a mobile phone having a configuration in which a commercially available DC battery or the like is used as an auxiliary power supply in response to a power drop in a mobile phone in an emergency. Also, a portable charger using a commercially available DC battery or the like is known. However, these are all separate from the mobile phone, which impairs the portability of the mobile phone.

In order to charge a secondary battery of a mobile phone,
It is necessary to provide an external terminal for making the mobile phone contact with a charging terminal of a charger. This external terminal is always exposed to the outside. For this reason, the design of the mobile phone is restricted.

[0005]

SUMMARY OF THE INVENTION In view of the above-mentioned problems, the present invention allows a secondary battery of a mobile phone to be charged by using electromagnetic waves, and allows charging without a power source without impairing the portability of the mobile phone. The task is to be able to

[0006]

According to the present invention, there is provided a charging device provided in a portable telephone, comprising: an induction coil for inducing an electromotive force from a magnetic field generated by an electromagnetic wave; And a charging circuit for converting an AC electromotive force generated by the induction coil into a DC and flowing the DC into a secondary battery.

When the power of the secondary battery of the mobile phone decreases, the mobile phone is installed near an electromagnetic wave generation source.
Since the magnetic flux of the induction coil installed in the mobile phone changes due to the electromagnetic waves emitted from the electromagnetic wave generation source,
An electromotive force is induced. Since this electromotive force is AC, it is converted into DC by the charging circuit. Then, a DC current flows into the secondary battery via the charging circuit, and the secondary battery is charged. Since the electromagnetic wave generation source exists in almost all places indoors and outdoors, the secondary battery can be charged without a power source simply by installing a mobile phone near the electromagnetic wave generation source.

[0008]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be described in more detail by way of examples. FIG. 1 is a schematic configuration diagram of a mobile phone T according to the present invention. As shown in FIG. 1, the charging device for a mobile phone according to the present invention includes an induction coil C for inducing an electromotive force from a magnetic field W (see FIG. 8) generated by an electromagnetic wave, and an induction coil C induced by the induction coil C. And a charging circuit E for converting the AC electromotive force e into a DC current and flowing it into the secondary battery B. The above-described induction coil C and charging circuit E are housed in the frame 1 of the mobile phone T.

First, the induction coil C will be described.
The induction coil C is obtained by winding a very thin conductive wire 3 around a cylindrical iron core 2 many times. When the induction coil C receives an external electromagnetic wave, its magnetic flux changes in accordance with Lenz's law, and an electromotive force e is induced. A method for obtaining the electromotive force e induced in the induction coil C disposed in the magnetic field W will be described. The magnetic flux φ passing through the N-turn induction coil C is
When it changes by Δφ (Wb) during the minute time Δt (sec), the electromotive force e (V) induced in the induction coil C
Is determined by e = − (N × Δφ) / Δt.

Here, in order to simplify the calculation, an induction coil is used.
The number of turns N of the conductive wire 3 in the cable C is 1. From Equation 1, an example
For example, if the magnetic flux φ is weakened by 1 Wb per second,
The electromotive force e induced in the coil C is e = − ｛1 × (−
1)｝ / 1 = 1 (V). Δt is the magnetic field in the magnetic field W
Since the ratio of the time during which the bundle φ changes, the frequency of the magnetic field W
Is higher, the wave needs to travel one cycle
Time is shortened. As a result, the magnetic flux generated within a unit time
As the rate of change of φ increases, the induced electromotive force e
growing. When the frequency of the magnetic field W is 60 Hz, FIG.
As shown in Fig. 2, the wave travels 120 times per second
Change. Area P₁Induction (between 0 and 1/240 seconds)
The generated electromotive force₁, Area P_Two(1/240 to 1/120 second
The electromotive force induced during_Two, Area P_Three (1/12
0 to 1/80 second)_Three , Territory
Area P_FourElectromotive force induced during (1/80 to 1/60 second)
To e_FourThen, each area P₁~ P_FourIs induced in
Electromotive force e₁~ E_FourIs obtained by the following equations. e₁= E
_Four= -1 / (1/240) =-240 (V), e_Two= E
_Three = -1 / {-(1/240)} = 240 (V)

When this is shown in time, a graph as shown in FIG. 3 is obtained. Next, the conductor 3 in the induction coil C
If the number of turns N is 1,000, how much magnetic flux φ is required to induce an electromotive force e of 240 V is calculated. Substituting each value into Equation 1 and calculating: Δφ =
0.001 (Wb). That is, in the case of the frequency of 60 Hz, the electromotive force e of 240 V is applied to the induction coil C of 1000 turns.
Requires a magnetic field W for generating a magnetic flux φ of 0.001 Wb.

Since the electromotive force e induced in this manner is an alternating current, it is converted into a direct current by the charging circuit E. As shown in FIG. 4, the charging circuit E includes a transformer 4, a rectifier 5, a capacitor 6, a resistor 7, a transistor 8, and a constant voltage diode 9. The voltage input to the primary side (the induction coil C side) of the transformer 4 is V ₁ , the current is I ₁ , the voltage output to the secondary side of the transformer 4 is V ₂ , and the current is I ₂ , Assuming that the efficiency of the transformer 4 is μ, the following equation is established. μ = (V ₂ × I ₂ ) /
(V ₁ × I ₁ )

When the electromotive force e is input to the primary side of the transformer 4, a voltage V ₂ is output to the secondary side. This voltage V ₂ is rectified by the rectifier 5 and the pulsating voltage V ₂ ′ shown in FIG. 5 is output. The pulsating voltage V ₂ ′ is stored in the capacitor 6 (see FIG. 4), smoothed and converted to DC, and a DC voltage V ₂ "is output. A DC current generated from this voltage V ₂ " I ₂ flows into the secondary battery B of the mobile phone T via the charging circuit E. Thus, the secondary battery B of the mobile phone T is charged.

Next, a case where the above-described principle of charging is applied to the secondary battery B of the mobile phone T will be described. The voltage of the secondary battery B of the mobile phone T is usually 3.6 V,
A lithium ion battery having a capacity of 400 mAh is used. That is, this lithium ion battery has a capacity capable of continuously flowing a current of 400 mA for one hour. When this lithium ion battery is charged by ordinary charging for 8 to 15 hours, constant current and constant voltage charging of 0.2 CmA to 4.1 V is performed. Here, “C” is a charge / discharge coefficient, and a current for charging or discharging the storage battery in one hour is 1 CA. Therefore, to normally charge the lithium ion battery, 400 × 0.2 = 8
A current of 0 (mA) is required.

[0015]

[Table 1]

Recently, various types of electrical equipment have been used in homes, and these electrical equipment emit electromagnetic waves during operation. Table 1 shows the intensity of electromagnetic waves emitted from main electric devices. Since 1 mG = 10 ⁻⁷ Wb, an electromagnetic wave of about 200 mG = about 2 × 10 ⁻⁵ Wb is emitted from, for example, a microwave oven. 1 in the magnetic field W due to this electromagnetic wave
When the 0000-turn induction coil C is installed, the electromotive force e induced in the induction coil C is calculated. The frequency is 60 Hz. e = − (10000 × 2 × 10 ⁻⁵ )
/ (1/240) =-48 (V)

Incidentally, it is technically possible to form the induction coil C in a state where the conductor 3 (see FIG. 1) is wound 10,000 times, and a method thereof will be described. As shown in FIG. 6, a thin conductive wire 3 is attached to a thin insulating sheet 11 in a spiral manner. Then, as shown in FIG. 7, the insulating sheets 11 are overlapped. At this time, the starting end 3a of the conductive wire 3 in one insulating sheet 11
And the terminal portion 3b of another insulating sheet 11 to be overlapped. The number of turns of the conductive wire 3 in one insulating sheet 11 is equivalent to several thousand turns. By laminating a predetermined number of insulating sheets 11 in this manner, an induction coil C having 10,000 turns is obtained. In this case, the induction coil C has a sheet shape. Instead of attaching the conductive wire 3 to the insulating sheet 11 in a spiral shape, a metal foil formed in a spiral shape by a method such as etching or plating may be attached.

From the above calculation results, when the induction coil C having 10,000 turns is arranged in the magnetic field W of 2 × 10 ⁻⁵ Wb at a frequency of 60 Hz, an electromotive force e of 48 V is induced. At the same time, the current I ₁ of a predetermined amount occurs. This current I ₁
By adjusting the resistance or the like of the induction coil C, the value can be adjusted. Therefore, assuming that the efficiency μ of the transformer 4 is 0.8, the current I ₁ input to the primary side of the transformer 4 is
Is 0.01 A, and the voltage V ₂ generated on the secondary side is 4.1 A.
When V is V, the current I ₂ generated on the secondary side is
I ₂ = 0.8 × 48 × 0.01 / 4.1 = 0.0936
(A). That is, a current of about 94 mA is generated.

The current I ₂ is sent to the charging circuit E, and the lithium ion battery is charged while being controlled by the charging circuit E. Since the current I ₂ is larger than the current (80 mA) required to charge the lithium ion battery, the lithium ion battery can be charged.

The operation of the portable telephone T will be described with reference to FIGS. When notified that the power of the secondary battery B of the mobile phone T has dropped, the mobile phone T is installed near an electromagnetic wave generation source such as an electric device.
FIG. 8 shows a case where the mobile phone T is installed near a personal computer 12 which is an example of an electromagnetic wave generation source. Since the mobile phone T receives the electromagnetic waves generated by the personal computer 12, the magnetic flux φ in the magnetic field W passing through the induction coil C changes, and the electromotive force e is induced. Since the electromotive force e is an alternating current, it is transformed by the transformer 4 in the conversion circuit D, rectified by the rectifier 5 and converted into a DC current I ₂ . The DC current I ₂ thus generated flows into the secondary battery B while being controlled in the charging circuit E, and the secondary battery B is charged.

In the above-described embodiment, the portable telephone T is installed in the magnetic field W formed by the electromagnetic waves emitted from the personal computer 12, but the source of the electromagnetic waves may be any. For example, a high voltage electric wire or a railway overhead wire may be used outdoors. Further, in this specification, the case where the secondary battery B is a lithium ion battery has been described. However, another secondary battery, for example, a nickel-cadmium battery or a nickel-metal hydride battery may be used. Further, the charging device according to the present invention can be mounted on a conventional mobile phone.

The charging structure for a mobile phone according to the present invention is not limited to use in a mobile phone, but may be used in portable information equipment such as a notebook computer and a video camera. .

[0023]

The portable telephone according to the present invention induces an electromotive force only by being installed in a magnetic field generated mainly by electromagnetic waves emitted from home electric appliances. This electromotive force is converted into a DC current through a charging circuit, and is charged by flowing into a secondary battery. Therefore, the following effects can be obtained. (1) The secondary battery can be charged without a power source only by installing the mobile phone near the electromagnetic wave generation source. Moreover, the electromagnetic wave source is
Since it exists in almost any place, indoors and outdoors, it can be charged anywhere. As a result, AC power supply equipment and a charger are unnecessary. In addition, even if the circuits necessary for charging are installed, the overall weight and size of the circuits are not significantly changed, so that the portability of the mobile phone is significantly improved without impairing its portability. (2) It is not necessary to provide an external terminal for charging in the mobile phone. Therefore, the shape of the frame of the mobile phone can be made free, and the design is improved.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a mobile phone T according to the present invention.

FIG. 2 is a graph showing a change in magnetic flux φ at a frequency of 60 Hz.

FIG. 3 shows an electromotive force e induced in each of the regions P _{1 to} P ₄ .
It is a graph showing a ₁ to e _4.

FIG. 4 is an electric circuit diagram of a charging circuit E.

FIG. 5 is a graph showing a voltage V ₂ ″ rectified by a charging circuit E;

FIG. 6 is a plan view showing a state in which a conductive wire 3 is spirally attached to an insulating sheet 11;

FIG. 7 is a perspective view of a state in which the insulating sheets 11 are stacked.

FIG. 8 is an operation explanatory view of the mobile phone T;

FIG. 9 is a perspective view showing a state in which a secondary battery of a mobile phone is charged by a conventional charger 51.

[Explanation of symbols]

B: secondary battery C: induction coil E: charging circuit e, e _{1 to} e ₄ : electromotive force I ₁ , I ₂ : current T: mobile phone W: magnetic field

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5G003 AA08 BA01 DA18 GB08 5K027 AA11 GG04 5K067 AA43 BB04 EE02 KK06 KK17

Claims (1)

[Claims] 1. A charging device provided in a mobile phone, comprising: an induction coil for inducing an electromotive force from a magnetic field generated by an electromagnetic wave; and an AC electromotive force generated by the induction coil, which is converted into a direct current. And a charging circuit for flowing the battery into the secondary battery.