BATTERY FOR MOBILE ELECTRONIC DEVICE WITH WA- TERPROOFFUNCTION AND METHOD THEREOF

Technical Field

[1] The present invention relates to a battery having a waterproof function for use in a mobile electronic device, and more particularly, to a waterproof battery for mobile electronic device (mobile telecommunication terminal, etc.) for protecting its own function and function of main body from water even when it is exposed to water, and a method of waterproofing the battery. Background Art

[2] A user can freely use a mobile telecommunication terminal, such as a mobile telephone and a personal digital assistant (PDA), even during a movement without respect to place. However, most mobile telecommunication terminals do not have a waterproof function. Thus, in general, when a mobile telecommunication terminal is exposed to water, water enters a circuit in the external case of the terminal and the circuit contacts the water, thus causing the malfunctions of the circuit due to a short circuit. In the case of a battery, water which is a dielectric is filled between a charge terminal and a discharge terminal thereof, thus causing complete discharge of the battery. Therefore, the battery cannot further be used. Accordingly, there is a growing need for a method of preventing malfunctions of an internal circuit of a mobile electronic device and a battery due to sudden discharge of electricity even when the mobile electronic device is plunged into water.

[3] Furthermore, a battery for a mobile telecommunication terminal needs external connection terminals to be charged with electricity and to supply power to the mobile telecommunication terminal. More specifically, in general, a battery used to supply power to a mobile telecommunication terminal is easily attached with and detached from a main body of the mobile telecommunication terminal. Also, the battery includes a charging connection terminal and a discharging connection terminal that are electrically connected to a charger or the main body of the mobile telecommunication terminal to be charged with or discharge electricity. Each of the charging and discharging connection terminals that are electrically connected to the internal circuit of the battery, is designed to be exposed at a predetermined point of the external case of the mobile telecommunication terminal. When the charging or discharging connection terminal of the battery contacts a corresponding charge terminal of an electronic device, such as a charger or a main body of a mobile telephone, they are electrically connected to charge the battery with electricity or apply power to the main

body of the mobile telephone.

[4] Accordingly, it is impossible to completely seal the external connection terminals of the battery. Also, since the external connection terminals are kept electrically connected to an internal circuit of the electronic device, when they contact a water solution containing an electrolyte, such as seawater, electricity flows between the connection terminals, which are an anode and a cathode, due to the electrolyte. In this case, the connection terminals or the circuit connected thereto malfunctions or the battery is discharged. Further, conventionally, when a battery is inserted into a main body of a mobile electronic device, connection terminals of the battery and an internal circuit of the main body are kept electrically connected. Thus, when the battery contacts water, electricity flows between the battery and the main body, and thus, it is very probable that circuit of the main body malfunctions. Disclosure of Invention Technical Problem

[5] The present invention provides a battery for mobile electronic device that provides a waterproof function of preventing electricity from flowing when the battery or external connection terminals thereof contact a liquid solution containing an electrolyte or water, and a waterproof method thereof.

[6] The present invention also provides a waterproof battery for mobile electronic device, in which the battery is electrically connected to a main body of the mobile electronic device only when the battery is combined with the main body and power supply is disconnected from the battery otherwise, thereby protecting the battery and the circuit of the main body even when the battery contacts water, and a waterproof function thereof.

[7] The present invention also provides a waterproof battery for mobile electronic device, in which even if the battery is combined with a main body of the mobile electronic device, power supply is disconnected from the battery when the main body contacts water, thereby protecting both the battery and the circuit of the main body, and a waterproof method thereof. Technical Solution

[8] According to an aspect of the present invention, there is provided a waterproof battery for mobile electronic device, the battery including a battery cell; an internal terminal electrically connecting the battery cell to the mobile electronic device; and a discharge circuit electrically connecting the internal terminal and the battery cell when the battery is combined with the mobile electronic device, and electrically disconnecting the internal terminal from the battery cell when the battery is separated from the mobile electronic device.

[9] The discharge circuit may include a hole sensor sensing a magnetic field generated by a magnet included in the mobile electronic device, and a switching circuit electrically connecting the internal terminal and the battery cell based on the magnetic field sensed by the hole sensor.

[10] According to another aspect of the present invention, there is provided a waterproof battery for mobile electronic device, the battery including a battery cell; an internal terminal electrically connecting the battery cell and the mobile electronic device; and a discharge circuit electrically connecting the internal terminal and the battery cell when the battery does not contact water, and electrically disconnecting the internal terminal from the battery cell when the battery contacts water.

[11] The discharge circuit may include a water detection sensor sensing whether the battery contacts water; and a switching circuit electrically connecting or disconnecting the internal terminal and the battery cell, depending on whether the water detection sensor senses that the battery contacts water.

[12] According to another aspect of the present invention, there is provided a method of waterproofing a battery for a mobile electronic device, the method including (a) sensing whether the battery is combined with the mobile electronic device; (b) when it is determined in (a) that the battery is combined with the mobile electronic device, forming a discharge path from a battery cell to an internal terminal, the discharge path via which electricity is supplied to the mobile electronic device; and (c) when it is determined in (a) that the battery is not combined with the mobile electronic device, blocking the discharge path from the battery cell to the internal terminal.

[13] The method may further include (d) determining whether the battery contacts water; and (e) when it is determined in (d) that the battery contacts water, blocking the discharge path.

Advantageous Effects

[14] According to the present invention, a battery is electrically connected to a main body of a mobile electronic device only when the battery is combined with the main body, and power supply is disconnected from the battery otherwise, thereby protecting the battery and the main body even when the battery contacts water.

[15] Also, according to the present invention, whether the battery contacts water is sensed, and when the battery contacts water, a path, i.e., a discharge path, via which power is supplied from the battery to the main body, is blocked, thereby protecting the battery and the internal circuit of the main body even when they contact water. Brief Description of the Drawings

[16] FIGS. 1 and 2 illustrate the relationship between a battery and a main body of a mobile electronic device according to an embodiment of the present invention;

[17] FIG. 3 is a block diagram illustrating the internal construction of a battery according to an embodiment of the present invention;

[18] FIG. 4 is a circuit diagram illustrating a discharge circuit according to an embodiment of the present invention;

[19] FIG. 5 is a circuit diagram illustrating a discharge circuit according to another embodiment of the present invention;

[20] FIG. 6 is a circuit diagram illustrating a discharge circuit according to another embodiment of the present invention; and

[21] FIG. 7 is a flowchart illustrating a method of waterproofing a battery according to an embodiment of the present invention. Best Mode for Carrying Out the Invention

[22] Hereinafter, exemplary embodiments of the present invention will be described in greater detail with reference to the accompanying drawings.

[23] FIGS. 1 and 2 illustrate the relationship between a battery 200 and a main body 100 of a mobile electronic device according to an embodiment of the present invention. Referring to FIGS. 1 and 2, the battery 200 can be easily attached to and detached from the main body 100. Referring to FIG. 2, a magnet 110 is included in the main body 100, and a hole sensor 310 is included in the battery 200. The hole sensor 310 senses a magnetic field generated by the magnet 110, allows the battery 200 to provide power to the main body 100 when the magnetic field is sensed, and does not allow the battery 200 to provide power to the main body 100 otherwise.

[24] Since the magnet 110 is built in the main body 100 and the hole sensor 310 is built in the battery 200, the hole sensor 310 can sense a magnetic field only when the battery 200 is combined with the main body 100.

[25] FIG. 3 is a schematic block diagram illustrating the internal construction of the battery 200 according to an embodiment of the present invention. Referring to FIG. 3, the battery 200 includes a charge circuit 210, a battery cell 220, and a discharge circuit 300. The battery 200 further includes a charge terminal 230 via which electricity is supplied from an external charger 700, and an internal terminal 240 via which electricity stored in the battery cell 220 is supplied to a main body 100 of a mobile electronic device.

[26] Electricity supplied from the charger 700 is stored in the battery cell 220. The charge circuit 210 allows the battery cell 220 to be charged with electricity from the charger 700, and disconnects supply of electricity to the battery cell 220 when the charging of the battery cell 220 with electricity is completed, thereby preventing the battery cell 220 from being excessively charged with electricity.

[27] The discharge circuit 300 supplies the electricity stored in the battery cell 220 to the

main body 100 via the internal terminal 240.

[28] Conventionally, a discharge circuit is constructed such that a battery cell is kept connected to an internal terminal. That is, a discharge path is formed from the battery cell to the internal terminal. Thus, when the battery is combined with a main body of an electronic device, electricity from the battery cell is supplied to the main body via the internal terminal. Also, even if the battery is not combined with the main body, the electricity is discharged from the battery cell when the internal terminal contacts water or a conductor.

[29] To solve this problem, in the present embodiment, the discharge circuit 300 is constructed such that the internal terminal 240 is electrically connected to the battery cell 220 when the battery cell 220 is inserted into the main body 100, and is electrically disconnected from the battery cell 220 when the battery cell 220 is separated from the main body 100.

[30] FIG. 4 is a circuit diagram illustrating the discharge circuit 300 according to an embodiment of the present invention. Referring to FIG. 4, the discharge circuit 300 includes a hole sensor 310, a switching circuit 320, and a resistor Rl.

[31] The hole sensor 310 senses a magnetic field generated by the magnet 110 installed in a mobile electronic device. When the hole sensor 310 senses the magnetic field, the switching circuit 320 electrically connects the internal terminal 240 to the battery cell 220 so that electricity is supplied to the main body 100 via the internal terminal 240. The switching circuit 320 includes a switching device PMl. Various switching devices, such as a relay switch and a transistor, may be used as the switching device PMl. However, the relay switch is larger than the transistor, and thus, the transistor is preferably used as the switching device PMl. In the present embodiment, a P-channel metal-oxide semiconductor field-effect transistor (P-channel MOSFET) (hereinafter referred to as "PMOS transistor") is used as the switching device PMl.

[32] When the battery 200 is combined with the main body 100 and the hole sensor 310 senses a magnetic field, having a value greater than a predetermined reference value, which is generated by the magnet 110, the transistor in the hole sensor 310 is turned on to allow current supplied via the resistor Rl to flow through the transistor of the hole sensor 310. Therefore, an electric potential at a first node Nl approximates 0 V, thus turning on the PMOS transistor PMl. Then, the battery cell 220 and the internal terminal 240 are electrically connected via the turned-on PMOS transistor PMl. Accordingly, a discharge path is formed from the battery cell 220 to the internal terminal 240.

[33] In contrast, when the battery 200 is not combined with the main body 100, the hole sensor 310 senses no magnetic field or a magnetic field having a value less than the predetermined reference value, and thus, the transistor of the hole sensor 310 is

maintained at a turn-off state. Therefore, the electric potential at the first node Nl goes high, thereby turning off the PMOS transistor PMl. When the PMOS transistor PMl is turned off, a path between the battery cell 220 and the internal terminal 240 is open, thereby preventing a discharge cell from being formed between the battery cell 220 and the internal terminal 240.

[34] As described above, in the discharge circuit 300 illustrated in FIG. 4, only when the battery 200 is combined with the main body 100, the discharge path of the battery cell 220 is formed, thus supplying power from the battery 200 to the main body 100. When the battery 200 is not combined with the main body 100, the discharge path of the battery cell 220 is not formed. In this case, even if the battery 200 is plunged into or contacts water, the discharge path of the battery cell 220 is not formed, thereby preventing damage to a battery circuit due to a closed-loop.

[35] Referring back to FIG. 4, power supplied from the charger 700 is stored in the battery cell 220 via a diode 250 and the switching circuit 320. The diode 250 and the switching circuit 320 of FIG. 4 are elements that constitute the charge circuit 210 shown in FIG. 3. In the embodiment illustrated in FIG. 4, the switching circuit 320 constitutes not only the discharge circuit 300 but also the charge circuit 210, but the present invention is not limited to this construction. For instance, an output of the diode 250 may be connected directly to a "+" terminal of the battery cell 220 without the switching circuit 320, or a switching circuit different from the switching circuit 320 may be inserted between the output of the diode 250 and the "+" terminal of the battery cell 220.

[36] The diode 250 of FIG. 4 allows flow of current to the battery cell 220 from the charger 700, more particularly, a charge terminal (the charge terminal 230 of FIG. 3) via which power is supplied from the charger 700, but doe not allow flow of current from the battery cell 220 to the charger 700. Accordingly, as illustrated in FIG. 4, since the diode 250 is installed between the charger 700 (or the charge terminal 230) and the battery cell 220, preferably, right after the charge terminal 230, the battery cell 220 can be charged with electricity from the charger 700 but discharging of electricity from the battery cell 220 via the charge terminal is not permitted. That is, the charge terminal 230 can be kept open owing to the diode 250, except during a charging operation. Therefore, since the charge terminal 230 is kept open except during the charging operation, current does not flow even if the charger terminal 230 contacts or is plunged into water, thereby preventing damage to the internal circuit and discharging via the charge terminal 230.

[37] FIG. 5 is a circuit diagram illustrating a discharge circuit 400 according to another embodiment of the present invention. Referring to FIG. 5, the discharge circuit 400 includes a water detection sensor 410, a switching circuit 420, and resistors R2 and R3.

[38] The water detection sensor 410 determines whether the battery 200 contacts water, and when it is determined that the battery 200 contacts water, the inner state of the water detection sensor 410 is changed or the water detection sensor 410 generates a signal indicating this fact.

[39] In the present embodiment, the battery 200 may further include a water detection terminal (not shown) connected thereto in order to determine whether the battery 200 contacts water. The water detection terminal may be installed next to the charge terminal 230 so that it can be exposed to the outside of the battery 200.

[40] In the present embodiment, a resistance in the water detection sensor 410 is changed when the battery 200 or the water detection terminal contacts water. When the water detection sensor 410 senses that the battery 200 or the water detection terminal contacts water, the switching circuit 420 electrically disconnects the internal terminal from the battery cell 220 so that electricity is not supplied to the main body 100 via the internal terminal 240. The switching circuit 420 includes a switching device PM2. As described above with reference to FIG. 4, various switching devices may be used as the switching device PM2, but a transistor is preferably used as the switching device PM2. In the present embodiment, a PMOS transistor is used as the switching device PM2.

[41] When the battery 200 or the water detection terminal does not contact water, the resistance in the water detection sensor 410 is greater than that of the resistor R2. In this case, an electric potential at a second node N2 goes low, and thus, an electric potential at a gate node N3 of the PMOS transistors PM2 goes low, thus turning on the PMOS transistor PM2. Then, the battery cell 220 and the internal terminal 240 are electrically connected via the turned-on PMOS transistor PM2. Thus, a discharge path is formed from the battery cell 220 to the internal terminal 240.

[42] On the other hand, when the battery 200 or the water detection terminal contacts water, the resistance in the water detection sensor 410 is lowered. In this case, the electric potential at the second node N2 goes high, and thus, the electric potential at the gate node N3 of the PMOS transistor PM2 goes high, thus turning off the PMOS transistor PM2. Then, the discharge path from the battery cell 220 to the internal terminal 240 is blocked.

[43] As described above, in the discharge circuit 420 of FIG. 5, only when the battery

200 does not contact water, the discharge path of the battery cell 220 is formed, thus allowing supply of power from the battery 200 to the main body 100. However, when the battery 200 contacts water, the water detection sensor 410 senses this fact and blocks the discharge path of the battery cell 220. Therefore, when the battery 200 combined with the main body 100 is plunged into or contacts water, the discharge path of the battery cell 220 is not formed, thus preventing damage to the internal circuit of the main body 100 or the battery 200.

[44] FIG. 6 is a circuit diagram illustrating a discharge circuit 500 according to another embodiment of the present invention. Referring to FIG. 6, the discharge circuit 500 includes a hole sensor 310, a water detection sensor 410, a first switching circuit 320, and a second switching circuit 420.

[45] The discharge circuit 500 is a combination of the discharge circuit 300 of FIG. 4 and the discharge circuit 400 of FIG. 5. In the case of the discharge circuit 300 of FIG. 4, a discharge path is formed from the battery cell 220 to the main body 100 of the mobile electronic device when the battery 200 is combined with the main body 100, and is blocked when the battery 200 is separated from the main body 100. In the case of the discharge circuit 400 of FIG. 5, a discharge path is formed from the battery cell 220 to the main body 100 when the battery 200 does not contact water, and is blocked when the battery 200 contacts water.

[46] Therefore, in the discharge circuit 500, of FIG. 6, which is a combination of the discharge circuit 300 of FIG. 4 and the discharge circuit 400 of FIG. 5, a discharge path is formed from the battery cell 220 to the main body 100 when the battery 200 combined with the main body 100 and the battery 200 does not contact water, and is blocked when the battery 200 is separated from the main body 100 or contacts water.

[47] Specifically, referring to FIG. 6, in the discharge circuit 500, the first and second switching circuits 320 and 420 are connected in series between the battery cell 220 and the internal terminal 240.

[48] The first and second switching circuits 320 and 420 are respectively similar to the switching circuit 320 of FIG. 4 and the switching circuit 420 of FIG. 5, and thus, a detailed description thereof will be omitted here. The PMOS transistor PMl used as a switching device of the first switching circuit 320 is turned on or off, depending on whether the hole sensor 310 senses a magnetic field. The operations of the hole sensor 310 and the resistor Rl have been described above with reference to FIG. 4.

[49] The PMOS transistor PM2 used as a switching device of the second switching circuit 420 is turned on or off, depending on whether the water detection sensor 410 senses that the battery 200 contacts water. The water detection sensor 410 and the resistors R2 and R3 have also been described above with reference to FIG. 5.

[50] FIG. 7 is a flowchart illustrating a method of waterproofing a battery according to an embodiment of the present invention. Referring to FIG. 7, it is determined whether a battery is combined with a main body of a mobile electronic device (S610), and a discharge path is blocked when the battery is not combined with the main body (S640). When it is determined that the battery is combined with the main body, it is determined whether the battery contacts water (S620). When it is determined in operation S620 that the battery or the main body contacts water, the discharge path is blocked (S640), and the discharge path is formed otherwise (S630).

[51] In the present embodiment, whether the battery or the main body contacts water is determined (S620) after whether the battery is combined with the main body is determined (S 610), but the present invention is not limited to the order of operations S610 and S620. Also, as described above, forming of the discharge path may be controlled based on a result of determining whether the battery is combined with the main body or whether the battery contacts water. Industrial Applicability

[52] According to the present invention, when a battery is not combined with a main body of a mobile electronic device or contacts water, a discharge path from the battery to the main body is blocked so that the internal circuit of the battery or the main body can be protected, thereby increasing the reliability of the mobile electronic device.