JP4128979B2 - Battery pack and battery protection device - Google Patents

Description

  The present invention relates to battery protection in a device that operates using a battery such as a portable electronic device, and in particular, a battery pack in which a predetermined number of batteries are housed in a container together with related circuits and such a battery. The present invention relates to a battery protection device provided in a device that is used by loading a pack.

  In recent years, in information processing electronic devices such as so-called OA devices, there is an increasing demand for portable electronic devices, that is, portable electronic devices. In such portable electronic devices, in most cases, the use of a commercial power source is used. The battery can be driven even in places where it cannot be done.

  In such an electronic device, a rechargeable secondary battery, that is, a nickel-cadmium battery, a nickel-hydrogen battery, or the like is used as a battery rather than a general primary battery such as a dry battery such as a manganese battery or an alkaline battery. In many cases, a plurality of them are used in combination in order to obtain required power. Therefore, in general, a predetermined number of batteries are accommodated in a container together with related circuits and integrated to form a battery pack, and this battery pack is loaded into an electronic device and used. Since the battery itself deteriorates, it is a kind of consumable item and is configured to be detachable from the electronic device.

  The battery pack is provided with a positive electrode terminal and a negative electrode terminal for connection to a device, and such a positive electrode terminal and a negative electrode terminal are often provided on the external side surface. However, since the battery pack is detachable, it is often carried around as a spare, for example, without being loaded into an electronic device, like a normal battery. In such a case, if the positive electrode terminal and the negative electrode terminal are projected from the outer surface, a short circuit between the two terminals may occur due to contact with a conductor such as metal outside. A short circuit between the positive electrode terminal and the negative electrode terminal of the battery causes deterioration of the battery, heat generation, liquid leakage, and the like.

  Therefore, in such a battery pack, it is necessary to prevent a short circuit between the positive electrode terminal and the negative electrode terminal. Conventionally, as a short circuit protection technique for a battery pack or the like, there has been a technique using a fuse or a self-recoverable switch element. That is, in the case of the fuse, when the fuse is inserted in series with the discharge path of the battery current and short-circuited, the fuse is blown by the current flowing through the discharge path or the heat generated thereby, thereby causing the discharge. Disconnect the path. In the case of the switch element, a self-recoverable switch element is inserted in series with the discharge path, and when the switch element is short-circuited, the switch element is turned off by a current flowing through the discharge path, etc. Disconnect. In this way, at the time of a short circuit, the discharge path is quickly disconnected to prevent battery heat generation and liquid leakage due to the short circuit.

  In addition, there are cases where the terminal portions such as the positive electrode terminal and the negative electrode terminal have special shapes so that they are not easily brought into contact with the outside except when attached to a dedicated connector. For example, a plurality of recesses corresponding to the number of terminals are formed on the outer surface of the battery pack, and contacts made of a conductor metal or the like of the terminal portions are provided on the bottom surfaces of the recesses, and the surrounding insulators than the contacts A barrier portion made of an insulator is formed between the contact of the positive electrode terminal and the contact of the negative electrode terminal, for example, by raising the portion, so as to deal with the danger of short circuit.

In the case of the above-described short circuit protection by the shape in the vicinity of the terminal portion, the contact of the electrode terminal is merely difficult to contact an external metal or the like, and there is a sufficient risk of contact. Therefore, if contact is made, it is needless to say that a short circuit between the positive electrode terminal and the negative electrode terminal causes problems such as sparks and heat generation.

  Even if it is possible to prevent excessive heat generation or the like by protection using a fuse, there is a problem that it takes time to replace the fuse for recovery from a blown fuse.

  When a self-recoverable switch element is used, since a time in seconds is required from when a short circuit occurs until the switch element is turned off, it causes deterioration of the battery.

  On the other hand, it is also conceivable to insert a switch circuit on the negative electrode side of the battery and to configure a short circuit protection circuit using such a switch circuit. FIG. 11 shows an example of a short circuit protection circuit including such a battery pack and its peripheral circuits.

In this case, on the device side, for example, 16 V DC power is supplied from the AC adapter to the external power supply terminal DC-IN to which the external DC power converted from the commercial AC power to DC by the AC adapter is input, It is assumed that the rated voltage of the battery BT is 3V. When the switch circuit SW is on, the potential at the terminal T is 3V or less because the voltage of the battery BT is divided by the resistor R1 and the thermistor TM. That is, the withstand voltage of the device-side element connected to the terminal T is sufficient even at about 10V. When the switch circuit SW is turned off, the positive terminal P is connected to the power supply terminal DC-IN through the resistor R1, so that the potential is 16V and the positive potential of the battery BT is 16V. Since the battery voltage is 3V, the voltage on the negative side of the battery BT is 13V of 16-3, and in this state, the voltage Vt between the negative terminal N of the terminal T is 13 to 16V.

In this case, the withstand voltage of the circuit on the device side connected to the terminal T is insufficient at 10 V, and the circuit cannot be established depending on the circuit configuration. For example, 16V DC power supplied from the AC adapter to the external power supply terminal DC-IN is also used for charging the battery BT.

  The switch circuit SW is configured using, for example, an FET (electrolytic effect transistor). A gate terminal (not shown) for turning on / off the FET is drawn out to the outside, and is turned on by short-circuiting it with the potential of the positive terminal P on the device side, and the output of the battery can be taken out to the outside. become able to.

  Secondary batteries such as nickel-cadmium batteries and nickel-hydrogen batteries have heat during charging, so the thermistor TM is provided to protect against overheating by detecting the battery temperature and stopping charging. ing.

Since the battery BT is discharged by self-discharge after the completion of charging, as a so-called trickle charge for compensating for the self-discharge, a minute charge is continuously performed from the external power supply terminal DC-IN via the resistor R2.

  In this case, when all the terminals are short-circuited externally, the gate control terminal of the switch circuit SW is short-circuited to the negative electrode terminal N and becomes the ground potential, so that the switch circuit SW is turned off and the battery positive electrode is externally connected. -The negative electrode is not short-circuited.

  In the same battery pack, when a switch circuit is provided on the positive side of the battery, the gate terminal for turning on / off the FET of the switch circuit is turned on by short-circuiting with the negative potential on the device side. .

  In that case, when all the terminals are short-circuited externally, the gate control terminal is short-circuited to the negative-electrode terminal and becomes a negative potential, so the switch circuit is turned on and the battery positive-negative electrode is short-circuited externally. There is a risk of being.

  The present invention has been made to solve such a problem, and provides a battery pack that can protect the battery itself from a short circuit even if the positive electrode terminal and the negative electrode terminal on the outer surface are short-circuited by contact. The purpose is to do.

  Furthermore, the present invention provides a battery protection device that enables control of switches inside the battery pack from the device side without adversely affecting other circuits even when a battery pack incorporating a protective switch is used. The purpose is that.

A first battery pack according to the present invention includes a battery having a positive electrode and a negative electrode, a positive electrode terminal for device connection, a negative electrode terminal for device connection, connected to the negative electrode of the battery, and the positive electrode terminal When the potential drops to be approximately equal to the negative electrode of the battery, the positive electrode terminal and the positive electrode of the battery are disconnected, and at other times, the positive electrode terminal and the positive electrode of the battery are electrically connected. Switch means.
The above configuration of the first battery pack according to the present invention may be applied to a battery protection circuit built in the battery pack.

The switch means includes a first switch that turns on and off between the positive electrode terminal and the positive electrode of the battery, and a positive electrode of the battery unless the positive electrode terminal and the negative electrode terminal are short-circuited externally. And is controlled to be turned on by lowering the positive terminal to a potential substantially equal to the negative electrode of the battery, thereby applying a control voltage to the first switch to turn off the first switch. And a second switch.
The configuration of the switch means may be applied to switch means in a battery protection circuit built in the battery pack.

  A second battery pack according to the present invention includes a battery having a positive electrode and a negative electrode, a positive electrode terminal for device connection, a negative electrode terminal connected to the negative electrode of the battery, and a device for device connection. When the potential of the control terminal and the control terminal is lowered to be substantially equal to the negative electrode of the battery, the positive terminal and the positive electrode of the battery are electrically connected, and otherwise the positive terminal and the battery Switch means for disconnecting from the positive electrode.

  The switch means includes a first switch for turning on / off between the positive electrode terminal and the positive electrode of the battery, and the control terminal is enabled in an on state so that the control terminal has a potential substantially equal to the negative electrode of the battery. A second switch that enables on-control of the first switch by lowering and disconnects the control terminal in an off state to forcibly turn off the first switch; and the positive terminal, If the control terminal and the negative electrode terminal are not short-circuited externally, the on-control is performed by the positive electrode potential of the battery, and the positive terminal is lowered to a potential substantially equal to the negative electrode of the battery, thereby The third switch is turned off by the potential of the negative electrode of the battery, and the second switch is turned off by the potential of the positive electrode of the battery. It may be provided with a switch.

  A third battery pack according to the present invention includes a battery having a positive electrode and a negative electrode, a positive terminal for device connection, a negative electrode terminal connected to the negative electrode of the battery, and a device for device connection. A control terminal for connecting a device, a voltage sense terminal to which a potential is supplied from a positive electrode of the battery, and the control terminal when the voltage sense terminal and the control terminal are short-circuited externally. Switch means for conducting between the positive electrode terminal and the positive electrode of the battery according to a given potential of the positive electrode of the battery and disconnecting between the positive electrode terminal and the positive electrode of the battery at other times; is doing.

The switch means is controlled by a first switch for turning on / off between the positive electrode terminal and the positive electrode of the battery, and a potential of the control terminal, and the control terminal is connected to a positive electrode potential of the battery. A second switch that is turned on to control the first switch; otherwise, is turned off by the potential of the negative electrode of the battery to turn off the first switch. May be.

  A first battery protection device according to the present invention includes a battery having a positive electrode and a negative electrode, a positive electrode terminal, a negative electrode terminal connected to the negative electrode of the battery, a control terminal, and a potential of the control terminal of the battery. First switch means for conducting between the positive electrode terminal and the positive electrode of the battery when lowered to be approximately equal to the negative electrode, and disconnecting between the positive electrode terminal and the positive electrode of the battery at other times; Load means that operates with power supplied from the positive electrode terminal and the negative electrode terminal of the battery pack, and the control terminal of the battery pack that is provided in association with the load means and that is supplied from the load means side And a second switch means for short-circuiting and separating between the negative electrode terminal and the negative electrode terminal.

  A second battery protection device according to the present invention is supplied with a potential from a battery having a positive electrode and a negative electrode, a positive electrode terminal, a negative electrode terminal connected to the negative electrode of the battery, a control terminal, and a positive electrode of the battery. A voltage sense terminal, and between the positive electrode terminal and the positive electrode of the battery due to the potential of the positive electrode of the battery applied to the control terminal when the voltage sense terminal and the control terminal are short-circuited externally. , And a load that operates with power supplied from the positive terminal and the negative terminal of the battery pack having first switch means for disconnecting between the positive terminal and the positive electrode of the battery at other times And a short circuit between the control terminal and the sense terminal of the battery pack by a control signal provided in association with the load means and supplied from the load means side And and a second switching means for performing disconnection.

  The first battery pack of the present invention disconnects the positive electrode terminal and the positive electrode of the battery when the potential of the positive electrode terminal is lowered to be approximately equal to the negative electrode of the battery by the switch, and otherwise By conducting between the positive electrode terminal and the positive electrode of the battery, even if the positive electrode terminal and the negative electrode terminal on the outer surface are short-circuited by contact, the battery itself can be protected from the short circuit.

  In addition, the second battery pack of the present invention has a control terminal, and when the potential of the control terminal is lowered by the switch so as to be substantially equal to the negative electrode of the battery, the positive terminal of the battery and the positive electrode of the battery In other cases, the positive electrode terminal and the positive electrode of the battery can be disconnected.

  The third battery pack of the present invention has a voltage sense terminal and a control terminal, and is given to the control terminal when the voltage sense terminal and the control terminal are short-circuited externally by a switch. The positive electrode terminal and the positive electrode of the battery are electrically connected by the potential of the positive electrode of the battery, and the positive electrode terminal and the positive electrode of the battery can be disconnected at other times.

  The first battery protection device of the present invention electrically connects the positive terminal and the positive electrode of the battery when the potential of the control terminal and the control terminal decreases to be substantially equal to the negative electrode of the battery. Sometimes a load is operated with power supplied from the positive terminal and the negative terminal of a battery pack having a first switch for disconnecting between the positive terminal and the positive electrode of the battery, and related to the load The second switch provided may adversely affect other circuits by short-circuiting or disconnecting between the control terminal and the negative terminal of the battery pack in response to a control signal supplied from the load side. In addition, the switch inside the battery pack can be controlled from the device side.

According to the second battery protection device of the present invention, when the voltage sense terminal and the control terminal are short-circuited externally, the positive terminal of the battery and the positive terminal of the battery are supplied by the potential of the positive electrode of the battery. Loaded with power supplied from the positive terminal and the negative terminal of the battery pack having a first switch for conducting between the positive electrode and otherwise disconnecting the positive terminal from the positive electrode of the battery And short-circuiting / disconnecting between the control terminal and the sense terminal of the battery pack in response to a control signal supplied from the load side by a second switch provided in association with the load. Can do.

  According to the present invention, the positive electrode terminal and the negative electrode terminal on the outer surface are separated by, for example, disconnecting the positive electrode terminal and the positive electrode of the battery by a switch when the potential of the positive electrode terminal decreases to be approximately equal to the negative electrode of the battery. Even if the battery is short-circuited by contact, a battery pack that can protect the battery itself from the short-circuit can be provided.

  Further, according to the present invention, when the potential of the control terminal decreases to be approximately equal to the negative electrode of the battery, the positive electrode terminal and the positive electrode of the battery are electrically connected, and otherwise, the positive electrode terminal and the battery are electrically connected. A battery pack having a first switch that disconnects the positive electrode of the battery pack from a positive electrode terminal and a negative electrode terminal. The second switch provided in association with the load causes the load to operate In response to a control signal supplied from the battery pack, the battery pack control terminal and the negative electrode terminal are short-circuited and disconnected, and so on, without adversely affecting other circuits. It is possible to provide a battery protection device that can control the above.

  Embodiments of a battery pack and a battery protection device according to the present invention will be described below with reference to the drawings.

[Embodiment 1] FIG. 1 shows the basic configuration of a battery pack according to a first embodiment of the present invention.

  The battery pack in FIG. 1 includes a battery 11, a positive terminal 12, a negative terminal 13, and a switch circuit 14. The battery 11 includes a predetermined number of batteries, for example, rechargeable secondary batteries such as nickel-hydrogen batteries, and is connected between a positive electrode and a negative electrode so as to obtain a required voltage.

  The positive electrode terminal 12 and the negative electrode terminal 13 are terminals for connecting the output of the battery 11 to the outside of the battery pack, that is, a device serving as a load. The switch circuit 14 is inserted between the positive electrode of the battery 11 and the positive electrode terminal 12, and is turned on / off in response to the potential of the positive electrode terminal 12, and between the positive electrode and the positive electrode terminal 12 of the battery 11. Connect / disconnect. The switch circuit 14 is turned off when the potential of the positive terminal 12 drops to a potential substantially equal to the potential of the negative electrode of the battery 11, and is turned on otherwise.

  The battery pack of FIG. 1 is configured to be detachable from the device. In this battery pack, the switch circuit 14 provided on the positive electrode side of the battery 11 operates in response to the potential of the positive electrode terminal 12. In other words, the switch circuit 14 is normally turned on in the removed state, and when the positive electrode terminal 12 and the negative electrode terminal 13 are short-circuited due to some external conductor contacting the outside. The switch circuit 14 is turned off because the potential of the positive terminal 12 is lowered. Therefore, the battery 11 is protected from a short circuit between the positive electrode and the negative electrode.

[Embodiment 2] FIG. 2 shows the structure of a battery pack according to a second embodiment of the present invention. FIG. 2 shows an example of a specific configuration based on the principle of the first embodiment of the present invention shown in FIG.

  The battery pack of FIG. 2 includes a positive terminal 12, a negative terminal 13, a battery BT, a first transistor TR11, a second transistor TR12, a first resistor R11, and a second resistor R12.

  The positive terminal 12 and the negative terminal 13 are exactly the same as in the case of FIG. The battery BT is formed by combining a plurality of batteries, for example, and is substantially the same as the battery 11 of FIG.

  The transistors TR11 and TR12 are switching elements, and in this case, are constituted by FETs (field effect transistors) whose source / drain are controlled to be turned on / off by a gate potential. The transistor TR11 has a source connected to the positive electrode of the battery BT, a drain connected to the positive electrode terminal 12, and a gate connected to one end of the resistor R12. The other end of the resistor R12 is connected to the negative electrode terminal 13, that is, the negative electrode of the battery BT. The transistor TR12 has a source connected to the source of the transistor TR11, a drain connected to the gate of the transistor TR11, and a gate connected to the positive electrode of the battery BT, that is, the source of the transistor TR11 via the resistor R11.

  A diode indicated by a broken line in FIG. 2 is a parasitic diode of the FET. These transistors TR11 and TR12 and resistors R11 and R12 constitute a switch circuit corresponding to the switch circuit 14 of FIG.

  In the battery pack of FIG. 2, normally, the gate of the transistor TR12 is connected to the positive electrode of the battery BT via the resistor R11, so that the source and gate of the transistor TR12 have the same potential, and the transistor TR12 is off. . Since the gate of the transistor TR11 is connected to the negative electrode of the battery BT via the resistor R2, the voltage is 0 V (ground potential) lower than the source potential. The power of the battery BT can be output.

  When a short circuit occurs between the positive electrode terminal 12 and the negative electrode terminal 13 in contact with a conductor, the gate of the transistor TR12 becomes a potential corresponding to the negative electrode terminal 13, that is, 0 V, and the transistor TR12 is turned on. When the transistor TR12 is turned on, the source and the gate of the transistor TR11 have the same potential, and the transistor TR11 is turned off.

  When this battery pack is used, since a load is applied between the positive electrode terminal 12 and the negative electrode terminal 13, a resistance is introduced, and the transistor TR11 is turned off unless the potential of the positive electrode terminal 12 is extremely lowered. Don't be. That is, the transistor TR11 is switched by checking whether the potential of the positive terminal 12 is extremely low.

[Embodiment 3] FIG. 3 shows the basic configuration of a battery pack according to a third embodiment of the present invention.

The battery pack 1 of FIG. 3 includes a control terminal 21 and a switch circuit 22 in addition to the battery 11, the positive terminal 12 and the negative terminal 13 similar to those in FIG. 3 also shows a positive terminal 23, a negative terminal 24, a control terminal 25, and the like on the device 2 side where the battery pack 1 is mounted.

As in the case of FIG. 1, the battery 11 comprises a predetermined number of batteries, for example, rechargeable secondary batteries such as nickel-hydrogen batteries, and is connected to obtain a required voltage between the positive electrode and the negative electrode. ing. The positive electrode terminal 12 and the negative electrode terminal 13 are terminals for connecting the output of the battery 11 to the outside of the battery pack, that is, a device serving as a load.

  The control terminal 21 is a terminal for supplying a control signal from the device 2 side to the switch circuit 22. The switch circuit 22 is inserted between the positive electrode and the positive electrode terminal 12 of the battery 11, and is turned on / off in response to the potentials of the positive electrode terminal 12 and the control terminal 21. Connect / disconnect to / from 12. In the switch circuit 22, the control terminal 21 and the negative electrode terminal 13 are short-circuited via the control terminal 25 and the negative electrode terminal 24 on the device 2 side, and the potential of the control terminal 21 becomes substantially equal to the potential of the negative electrode of the battery 11. Turns on when it drops, otherwise it turns off. Further, the switch circuit 22 is substantially the same as the switch circuit 14 of FIG. 1, even if the control terminal 21 and the negative electrode terminal 13 are short-circuited, the potential of the positive electrode terminal 12 is substantially equal to the negative electrode potential of the battery 11. It turns off when it drops to.

  The positive terminal 23, the negative terminal 24 and the control terminal 25 of the device 2 are connected to the positive terminal 12, the negative terminal 13 and the control terminal 21 of the battery pack 1 when the battery pack 1 is attached to the device 2, respectively. The control terminal 25 and the negative electrode terminal 24 of the device 2 are short-circuited on the device 2 side.

  The battery pack 1 of FIG. 3 is configured to be detachable from the device, and the switch circuit 22 provided on the positive electrode side of the battery 11 operates in response to the potential of the control terminal 21. In the battery pack 1 of FIG. 3, the switch circuit 22 is turned on when the control signal of the control terminal 21 is set to a substantially negative potential, and the switch circuit 22 is turned off otherwise. When the terminal 12 is almost at the negative potential, it is turned off.

  That is, the switch circuit 22 is normally off when the battery pack 1 is removed from the device 2, and the battery pack 1 is attached to the device 2, and the switch circuit 22 is between the control terminal 21 and the negative electrode terminal 13. Is turned on by being short-circuited, and a voltage is supplied from the positive terminal 12 through the positive terminal 23 into the device 2.

  When the control terminal 21 is not connected to the negative potential, the switch circuit 22 is turned off. Therefore, even if the positive electrode terminal 12 and the negative electrode terminal 13 are short-circuited, the battery 11 is not short-circuited. When the control terminal 21 is connected to the negative potential and the switch circuit 22 is on, the potential of the positive terminal 12 decreases when the positive terminal 12 and the negative terminal 13 are short-circuited. Turn off. Therefore, the battery 11 is protected from a short circuit between the positive electrode and the negative electrode.

[Embodiment 4] FIG. 4 shows the structure of a battery pack according to a fourth embodiment of the present invention. FIG. 4 shows an example of a specific configuration based on the principle of the third embodiment according to the present invention shown in FIG.

  The battery pack of FIG. 4 includes a positive terminal 12, a negative terminal 13, a control terminal 21, a battery BT, a first transistor TR21, a second transistor TR22, a third transistor TR23, a first resistor R21, and a second resistor. R22 and a third resistor R23 are provided.

  The positive terminal 12, the negative terminal 13, and the control terminal 21 are exactly the same as in FIG. As in the case of FIG. 2, the battery BT is formed by combining, for example, a plurality of batteries, and is substantially the same as the battery 11 of FIG.

  Transistors TR21, TR22, and TR23 are switching elements, and in this case, are constituted by FETs whose source-drain are controlled to be turned on / off by a gate potential.

  The transistor TR21 has a source connected to the positive electrode of the battery BT, a drain connected to the positive electrode terminal 12, and a gate connected to the source via a resistor R23. The transistor TR22 has a source connected to the gate of the transistor TR21, a drain connected to the control terminal 21, and a gate connected to the positive electrode of the battery BT, that is, the source of the transistor TR21 via the resistor R22. The transistor TR23 has a drain connected to the gate of the transistor TR22, a source connected to the negative electrode and the negative electrode terminal 13 of the battery BT, and a gate connected to the positive electrode of the battery BT, that is, the source of the transistor TR21 via the resistor R21. . The gate of the transistor TR23 is also connected to the drain of the transistor TR21, that is, the positive terminal 12.

  Transistors TR21, TR22 and TR23 and resistors R21, R22 and R23 constitute a switch circuit corresponding to the switch circuit 22 of FIG.

  In the battery pack of FIG. 4, since the gate of the transistor TR12 is normally connected to the source of the transistor TR12 via the resistor R23, the transistor TR12 is turned off, and power is output from the positive terminal 12. Can not. Since the gate of the transistor TR23 is connected to the positive electrode of the battery BT via the resistor R21, the transistor TR23 is turned on. Therefore, since the gate of the transistor TR22 is connected to the negative electrode of the battery BT and the source of the transistor TR22 is connected to the positive electrode of the battery BT through the resistor R23, the transistor TR22 is turned on. For this reason, when the control terminal 21 and the negative terminal 13 are short-circuited, the gate voltage of the transistor TR21 becomes 0 V, the transistor TR21 is turned on, and the power of the battery BT can be output from the positive terminal 12. become.

  In this state, when the positive electrode terminal 12 and the negative electrode terminal 13 are short-circuited, the gate voltage of the transistor TR23 becomes 0 V, the same potential as the source of the transistor TR23, and the transistor TR23 is turned off. Then, since the gate of the transistor TR22 is connected to the positive electrode of the battery BT via the resistor R22, the gate potential becomes equal to or higher than the source potential of the transistor TR22, and the transistor TR22 is turned off. When the transistor TR22 is turned off, the gate of the transistor TR21 is disconnected from the control terminal 21, so that the gate potential of the transistor TR21 is the same as the source potential of the transistor TR21, and the transistor TR21 is turned off.

  In this way, when the transistor TR22 is turned off, the gate of the transistor TR21 is disconnected from the control terminal and connected to the positive electrode of the battery BT via the resistor R23, and the transistor TR21 is turned off, so that the battery BT is short-circuited. Protected from.

[Embodiment 5] FIG. 5 shows the basic structure of a battery pack according to a fifth embodiment of the present invention.

The battery pack 3 in FIG. 5 includes a battery 11, a positive terminal 12, a negative terminal 13 and a control terminal 21 similar to those in FIG.
It has. FIG. 5 also shows the positive terminal 23, the negative terminal 24, the control terminal 25, the voltage sense terminal 34, and the like on the device 4 side where the battery pack 3 is mounted.

As in the case of FIG. 3, the battery 11 includes a predetermined number of batteries, for example, rechargeable secondary batteries such as nickel-hydrogen batteries, and is connected so as to obtain a required voltage between the positive electrode and the negative electrode. ing. The positive electrode terminal 12 and the negative electrode terminal 13 are terminals for connecting the output of the battery 11 to the outside of the battery pack, that is, a device serving as a load. The control terminal 21 is connected to the switch circuit 3
2 is a terminal for controlling 2 from the device 4 side.

  The voltage sense terminal 31 is a terminal for enabling the voltage of the battery 11 to be detected from the device 4 side even when the switch circuit 32 is off. The switch circuit 32 is inserted between the positive electrode of the battery 11 and the positive electrode terminal 12, and is turned on / off in response to the potential of the control terminal 21, and between the positive electrode and the positive electrode terminal 12 of the battery 11. Connect / disconnect. In the switch circuit 32, the control terminal 21 and the voltage sense terminal 31 are short-circuited via the control terminal 25 and the voltage sense terminal 34 on the device 4 side, and the potential of the control terminal 21 is substantially equal to the potential of the positive electrode of the battery 11. Turns on when the potential is reached, and turns off otherwise. Further, in the switch circuit 32, the potential of the positive terminal 12 is substantially equal to the potential of the negative electrode of the battery 11 even when the control terminal 21 and the voltage sense terminal 31 are short-circuited, as in the switch circuit 22 of FIG. Turns off when the potential drops.

  The positive terminal 23, the negative terminal 24, the control terminal 25, and the voltage sense terminal 34 of the device 4 are respectively connected to the positive terminal 12, the negative terminal 13, and the control terminal 21 of the battery pack 3 when the battery pack 3 is attached to the device 4. And connected to the voltage sense terminal 31. The control terminal 25 and the voltage sense terminal 34 of the device 4 are short-circuited on the device 4 side.

  The battery pack 3 of FIG. 5 is configured to be detachable from the device, and the switch circuit 22 provided on the positive electrode side of the battery 11 operates in response to the potential of the control terminal 21. In the battery pack 3 of FIG. 5, the switch circuit 32 is turned on when the control signal of the control terminal 21 is set to a substantially positive potential, and the switch circuit 32 is turned off otherwise. When the terminal 12 is almost at the negative potential, it is turned off.

  That is, the switch circuit 32 is normally turned off when the battery pack 3 is detached from the device 4, and the battery pack 3 is attached to the device 4, and the control terminal 21 and the voltage sense terminal 31 are connected. When the space is short-circuited, the power is turned on, and a voltage is supplied from the positive terminal 12 to the device 2 through the positive terminal 23.

  When the control terminal 21 is not connected to the positive electrode potential, the switch circuit 32 is turned off. Therefore, even if the positive electrode terminal 12 and the negative electrode terminal 13 are short-circuited, the battery 11 is not short-circuited. When the control terminal 21 is connected to the positive electrode potential and the switch circuit 32 is on, the potential of the positive electrode terminal 12 decreases when the positive electrode terminal 12 and the negative electrode terminal 13 are short-circuited. Turn off. Therefore, the battery 11 is protected from a short circuit between the positive electrode and the negative electrode.

[Embodiment 6] FIG. 6 shows a structure of a battery pack according to a sixth embodiment of the present invention. FIG. 6 shows an example of a specific configuration based on the principle of the fifth embodiment according to the present invention shown in FIG.

  6 includes a positive terminal 12, a negative terminal 13, a control terminal 21, a voltage sense terminal 31, a battery BT, a first transistor TR31, a second transistor TR32, a first resistor R31, and a second resistor R32. And a third resistor R33.

  The positive terminal 12, the negative terminal 13, the control terminal 21, and the voltage sense terminal 31 are exactly the same as in the case of FIG. As in the case of FIG. 2, the battery BT is formed by combining, for example, a plurality of batteries, and is substantially the same as the battery 11 of FIG.

  The transistors TR31 and TR32 are switching elements, and in this case, are constituted by FETs whose source-drain are controlled to be turned on / off by the gate potential.

  The transistor TR31 has a source connected to the positive electrode of the battery BT, a drain connected to the positive electrode terminal 12, and a gate connected to the source via a resistor R32. Transistor TR32 has a source connected to the negative electrode and negative electrode terminal 13 of battery BT, a drain connected to the gate of transistor TR31, and a gate connected to the negative electrode of battery BT, that is, negative electrode terminal 13 via resistor R33. Further, the gate of the transistor TR32 is directly connected to the control terminal 21 and is connected to the drain of the transistor TR31, that is, the positive terminal 12 through the diode D31 having the polarity shown in the figure. The voltage sense terminal 31 is connected to the positive electrode of the battery BT, that is, the source of the transistor TR31 via the resistor R31.

  Transistors TR31, TR32 and TR33 and resistors R31, R32 and R33 constitute a switch circuit corresponding to the switch circuit 32 of FIG. The resistor R31 corresponds to the resistor 33 in FIG.

  In the battery pack of FIG. 6, the transistor TR32 is normally turned off because the gate of the transistor TR32 is connected to the source of the transistor TR32 via the resistor R33. Since the gate of the transistor TR31 is connected to the source of the transistor TR31 via the resistor R32, the transistor TR31 is off, and the power of the battery BT cannot be output from the positive terminal 12. When the control terminal 21 is connected to the voltage sense terminal 31, the gate voltage of the transistor TR32 becomes a voltage obtained by dividing the voltage of the battery BT by the resistor R31 and the resistor R33. If the resistance values of the resistors R31 and R33 are set in advance so that the voltage can turn on the transistor TR32, the transistor TR32 is turned on and the gate voltage of the transistor TR31 becomes 0V. The transistor TR31 is turned on, and the power of the battery BT can be output from the positive electrode terminal 12.

  Although this seems to be a rare case, when the positive terminal 12 and the negative terminal 13 are short-circuited in this state, a current flows through the diode D31, and the potential of the gate of the transistor TR32 decreases. Therefore, the transistor TR32 is turned off, the gate potential of the transistor TR31 is the same as the source potential, and the transistor TR31 is turned off.

[Embodiment 7] FIG. 7 shows the structure of a basic battery protection apparatus according to a seventh embodiment of the present invention. FIG. 7 shows a battery protection device including the battery pack 1 having the configuration shown in FIG. 3 and the device 5 to which the battery pack 1 is attached.

As shown in FIG. 3, the battery pack 1 includes a battery 11, a positive terminal 12, a negative terminal 13, a control terminal 21, and a first switch circuit 22. The battery 11 includes a predetermined number of batteries, for example, rechargeable secondary batteries such as nickel-hydrogen batteries, and is connected between a positive electrode and a negative electrode so as to obtain a required voltage. The positive electrode terminal 12 and the negative electrode terminal 13 are terminals for connecting the output of the battery 11 to the outside of the battery pack 1, that is, to a device serving as a load.

The control terminal 21 is a terminal for controlling the first switch circuit 22 from the device 5 side. The first switch circuit 22 is inserted between the positive electrode of the battery 11 and the positive electrode terminal 12, and is turned on / off in response to the potentials of the positive electrode terminal 12 and the control terminal 21. And disconnection from the positive terminal 12. The switch circuit 22 is turned on when the control terminal 21 and the negative electrode terminal 13 are short-circuited, and the potential of the control terminal 21 drops to a potential substantially equal to the potential of the negative electrode of the battery 11, and is turned off otherwise. Further, even if the control terminal 21 and the negative electrode terminal 13 are short-circuited, the switch circuit 22 is turned off when the potential of the positive electrode terminal 12 drops to a potential substantially equal to the negative electrode potential of the battery 11.

  The device 5 has the same positive electrode terminal 23, negative electrode terminal 24 and control terminal 25 as those of the device 2 shown in FIG. 3, and further includes a second switch circuit 41. The second switch circuit 41 turns on / off between the control terminal 25 on the device 5 side and the negative terminal 24 in response to a control signal inside the device 5.

  The battery pack 1 of FIG. 7 is configured to be detachable from the device 5, and the first switch circuit 22 provided on the positive electrode side of the battery 11 operates in response to the potential of the control terminal 21. In the battery pack 1, the switch circuit 22 is turned on when the potential of the control terminal 21 is set to a substantially negative potential, and the switch circuit 22 is turned off otherwise. It turns off when the potential is negative.

  That is, the switch circuit 22 is normally turned off when the battery pack 1 is removed from the device 5, the battery pack 1 is attached to the device 5, and the switch circuit 41 is controlled by an internal control signal. It is turned on when the control terminal 21 and the negative terminal 13 are short-circuited, and a voltage is supplied from the positive terminal 12 to the device 5 through the positive terminal 23. That is, the switch circuit 22 is short-circuited between the control terminal 21 and the negative terminal 13 if the switch circuit 41 is turned off by an internal control signal even when the battery pack 1 is mounted on the device 5. In other words, the switch circuit 22 is off, and there is no power supply from the positive terminal 12 into the device 5.

  In this way, even when the battery pack 1 similar to that shown in FIG. 3 is attached to the device 5, the switch circuit 41 is turned on / off by the control signal inside the device 5, thereby turning the switch circuit 22 on / off. Can be made.

[Embodiment 8] FIG. 8 shows a structure of a battery pack according to an eighth embodiment of the present invention. FIG. 8 shows an example of a specific configuration based on the principle of the seventh embodiment according to the present invention shown in FIG.

  FIG. 8 shows a battery protection device including a battery pack 6 having a configuration substantially similar to that in FIG. 4 and a device 7 to which the battery pack 6 is attached. The battery pack 6 of FIG. 8 includes a positive terminal 12, a negative terminal 13, a control terminal 21, a sense terminal 42, a battery BT, a first transistor TR21, a second transistor TR22, a third transistor TR23, and a first resistor R21. , A second resistor R22, a third resistor R23, and a fourth resistor R24.

  The transistors TR21 to TR23 are switching elements, and in this case, are constituted by FETs whose source-drain are controlled to be turned on / off by the gate potential. The transistor TR21 has a source connected to the positive electrode of the battery BT, a drain connected to the positive electrode terminal 12, and a gate connected to the source via a resistor R23. The transistor TR22 has a source connected to the gate of the transistor TR21, a drain connected to the control terminal 21, and a gate connected to the positive electrode of the battery BT, that is, the source of the transistor TR21 via the resistor R22. The transistor TR23 has a drain connected to the gate of the transistor TR22, a source connected to the negative electrode and the negative electrode terminal 13 of the battery BT, and a gate connected to the positive electrode of the battery BT, that is, the source of the transistor TR21 via the resistor R21. . The gate of the transistor TR23 is also connected to the drain of the transistor TR21, that is, the positive terminal 12. The sense terminal 42 is connected to the positive electrode of the battery BT, that is, the source of the transistor TR21 via the resistor R24.

  The device 7 includes a positive terminal 23, a negative terminal 24, a control terminal 25, a sense terminal 43, a fourth transistor TR24, a fifth transistor TR25, a sixth transistor TR26, a fifth resistor R25, a sixth resistor R26, A seventh resistor R27 and an eighth resistor R28 are provided.

  The transistors TR24 to TR26 are switch elements, and in this case, are constituted by FETs whose source-drain are controlled to be turned on / off by the gate potential. The transistor TR24 has a source connected to the negative terminal 24, a drain connected to the control terminal 25, and a gate connected to the positive terminal 23 via a resistor R28. The gate of the transistor TR24 is also connected to a negative potential (ground) having the same potential as that of the negative terminal 24 via a resistor R25. The transistor TR25 has a source connected to the sense terminal 43, a drain connected to the gate of the transistor TR24, and a gate connected to the positive terminal 23. The gate of the transistor TR25 is also connected to the negative potential through the resistor R27. The transistor TR26 has a source connected to the negative potential, a drain connected to the gate of the transistor TR24, and a gate connected to the negative potential via the resistor R26. A control signal inside the device 7 is given to the gate of the transistor TR26.

  The transistors TR21 to TR26 are switching elements, and in this case, are constituted by FETs whose source-drain are controlled to be turned on / off by the gate potential. The positive terminal 23, the negative terminal 24, the control terminal 25, and the sense terminal 43 of the device 7 are the positive terminal 12, the negative terminal 13, the control terminal 21, and the sense of the battery pack 6 when the battery pack 6 is attached to the device 7. Each is connected to a terminal 42.

  When the battery pack 6 of FIG. 8 has just been attached to the device 7, the transistor TR21 is turned off, so that power cannot be supplied from the positive terminal 12 to the device. Since the source of the transistor TR25 is charged with the battery voltage from the positive electrode of the battery BT via the resistor R24, and the gate of the transistor TR25 is connected to the negative electrode potential via the resistor R27, the transistor TR25 is turned on. The gate voltage of the transistor TR24 is a voltage obtained by dividing the output voltage of the battery BT by the resistor R24 and the resistor R25, and both resistance values are set in advance so that this voltage becomes a voltage for turning on the transistor TR24. As a result, the transistor TR24 is turned on. When the transistor TR24 is turned on, the control terminal 25 and the negative electrode terminal 24 are connected, that is, between the control terminal 21 and the negative electrode terminal 13, so that the power of the battery BT is output from the positive electrode terminal 12.

  Since the gate voltage of the transistor TR25 is the voltage of the battery BT, the transistor TR25 is turned off. However, the gate voltage of the transistor TR24 is a voltage obtained by dividing the output voltage of the battery BT by the resistor R28 and the resistor R25. By setting both resistance values in advance so that the voltage becomes a voltage that turns on the transistor TR24, the transistor TR24 remains on.

  When a voltage that can turn on the transistor TR26 is applied to the gate of the transistor TR26 as a control signal from the inside of the device 7, the transistor TR26 is turned on, the gate voltage of the transistor TR24 becomes 0V, and the transistor TR24. Is turned off, and the transistor TR21 in the battery pack 6 can be turned off. By setting the control signal to high impedance or 0 V, the transistor TR26 is turned off and the transistor TR24 is turned on, so that the transistor TR21 can be turned back on.

[Embodiment 9] FIG. 9 shows the structure of a basic battery protection apparatus according to a ninth embodiment of the present invention.

FIG. 9 shows a battery protection device including the battery pack 3 having the configuration shown in FIG. 5 and the device 8 to which the battery pack 3 is attached. As shown in FIG. 5, the battery pack 3 includes a battery 11, a positive terminal 12, a negative terminal 13, a control terminal 21, a voltage sense terminal 31, a first switch circuit 32, and a resistor 33.

  The battery 11 includes a predetermined number of batteries, for example, rechargeable secondary batteries such as nickel-hydrogen batteries, and is connected between a positive electrode and a negative electrode so as to obtain a required voltage. The positive electrode terminal 12 and the negative electrode terminal 13 are terminals for connecting the output of the battery 11 to the outside of the battery pack 3, that is, a device serving as a load.

  The control terminal 21 is a terminal for controlling the first switch circuit 32 from the device 8 side. The voltage sense terminal 31 is a terminal for enabling the voltage of the battery 11 to be detected from the device 4 side even when the switch circuit 32 is off.

  The first switch circuit 32 is inserted between the positive electrode of the battery 11 and the positive electrode terminal 12, and is turned on / off in response to the potential of the control terminal 21. Connect / disconnect to / from. The switch circuit 32 is turned on when the control terminal 21 and the voltage sense terminal 31 are short-circuited, and the potential of the control terminal 21 becomes substantially equal to the potential of the positive electrode of the battery 11, and is turned off otherwise. Further, even if the control terminal 21 and the voltage sense terminal 31 are short-circuited, the switch circuit 32 is turned off when the potential of the positive terminal 12 drops to a potential substantially equal to the potential of the negative electrode of the battery 11.

  The device 8 has the same positive electrode terminal 23, negative electrode terminal 24, control terminal 25 and voltage sense terminal 34 as those of the device 4 shown in FIG. 5, and further includes a second switch circuit 51.

  The second switch circuit 51 turns on / off between the control terminal 25 on the device 8 side and the voltage sense terminal 34 in response to a control signal inside the device 8. The battery pack 3 of FIG. 9 is configured to be detachable from the device 8, and the first switch circuit 22 provided on the positive electrode side of the battery 11 operates in response to the potential of the control terminal 21. In the battery pack 3, the switch circuit 32 is turned on when the potential of the control terminal 21 is set to a substantially positive potential, and the switch circuit 32 is turned off in other cases. It turns off when the potential is negative.

  That is, the switch circuit 32 is normally off when the battery pack 3 is removed from the device 8, the battery pack 3 is attached to the device 8, and the switch circuit 51 is further controlled by an internal control signal. It is turned on by short-circuiting between the control terminal 21 and the voltage sense terminal 31, and a voltage is supplied from the positive terminal 12 through the positive terminal 23 into the device 8. That is, the switch circuit 32 is short-circuited between the control terminal 21 and the voltage sense terminal 31 if the switch circuit 51 is turned off by an internal control signal even when the battery pack 3 is attached to the device 8. In other words, the switch circuit 32 is off, and no power is supplied from the positive terminal 12 into the device 8.

  In this way, even when the battery pack 3 similar to that shown in FIG. 5 is mounted on the device 8, the switch circuit 51 is turned on / off by the control signal inside the device 8, thereby turning the switch circuit 32 on / off. Can be made.

[Embodiment 10] FIG. 10 shows a structure of a battery pack according to a tenth embodiment of the present invention. FIG. 10 shows an example of a specific configuration based on the principle of the ninth embodiment of the present invention shown in FIG.

  FIG. 10 shows a battery protection device including a battery pack 9 having substantially the same configuration as FIG. 6 and a device 10 to which the battery pack 9 is attached. 10 includes a positive terminal 12, a negative terminal 13, a control terminal 21, a voltage sense terminal 31, a battery BT, a first transistor TR31, a second transistor TR32, a first resistor R31, and a second resistor. R32 and a third resistor R33 are provided.

  The transistors TR31 and TR32 are switching elements, and in this case, are constituted by FETs whose source-drain are controlled to be turned on / off by the gate potential.

  The transistor TR31 has a source connected to the positive electrode of the battery BT, a drain connected to the positive electrode terminal 12, and a gate connected to the source via a resistor R32. Transistor TR32 has a source connected to the negative electrode and negative electrode terminal 13 of battery BT, a drain connected to the gate of transistor TR31, and a gate connected to the negative electrode of battery BT, that is, negative electrode terminal 13 via resistor R33. Further, the gate of the transistor TR32 is directly connected to the control terminal 21 and is connected to the drain of the transistor TR31, that is, the positive terminal 12 through the diode D31 having the polarity shown in the figure. The voltage sense terminal 31 is connected to the positive electrode of the battery BT, that is, the source of the transistor TR31 via the resistor R31.

  The device 10 includes a positive terminal 23, a negative terminal 24, a control terminal 25, a voltage sense terminal 34, a third transistor TR33, a fourth transistor TR34, a fourth resistor R34, a fifth resistor R35, and a sixth resistor R36. It has.

  Transistors TR33 and TR34 are switching elements, and in this case, are constituted by FETs whose source-drain are controlled to be turned on / off by the gate potential.

  The transistor TR33 has a source connected to the negative terminal 24, a drain connected to the control terminal 25, and a gate connected to a negative potential via a resistor R35. A resistor R34 is connected between the positive terminal 23 and the voltage control terminal 25. The transistor TR 34 has a source connected to the voltage sense terminal 34, a drain connected to the control terminal 25, and a gate connected to the positive terminal 23. The gate of the transistor TR34 is also connected to the negative potential through the resistor R36. A control signal inside the device 10 is given to the gate of the transistor TR33.

  Transistors TR33 and TR34 are switching elements, and in this case, are constituted by FETs whose source-drain are controlled to be turned on / off by the gate potential.

  The positive terminal 23, the negative terminal 24, the control terminal 25, and the voltage sense terminal 34 of the device 10 are the positive terminal 12, the negative terminal 13, the control terminal 21, and the control terminal 21 of the battery pack 9 when the battery pack 9 is attached to the device 10. Each is connected to a voltage sense terminal 31.

When the battery pack 9 of FIG. 10 has just been attached to the device 10, the transistor TR 31 is off, so that power cannot be supplied from the positive terminal 12 to the device 10. Since the voltage of the battery BT is applied to the source of the transistor TR34 by the resistor R34, and the gate of the transistor 34 is connected to the negative potential through the resistor R36, the transistor TR34 is turned on. Therefore, since the control terminal 21 and the voltage sense terminal 31 are connected via the control terminal 25 and the voltage sense terminal 34, respectively, electric power is supplied from the positive electrode terminal 12. Since the gate voltage of the transistor TR34 becomes the voltage of the battery BT, the transistor TR34 is turned off, but the control terminal 25 is connected to the positive terminal 23 via the resistor R34, and the gate voltage of the transistor TR32 is A voltage obtained by dividing the voltage of the battery BT by the resistor R34 and the resistor R33 is set in advance so that this voltage becomes a voltage for turning on the transistor TR32. Thus, the transistor TR32 remains turned on. .

  When a voltage capable of turning on the transistor TR33 is applied as a control signal, the transistor TR33 is turned on and the voltage of the control terminal 21 becomes 0V. Therefore, the transistor TR32 can be turned off and the transistor TR31 can be turned off. By setting the control signal to high impedance or 0 V, the transistor TR33 is turned off and the transistor TR32 is turned on, so that the transistor TR31 can be turned back on.

  In addition, the present invention is not limited only to battery packs and battery protection devices using rechargeable secondary batteries, and battery packs using primary batteries such as dry batteries can be similarly protected. Is possible.

It is a block diagram which shows the structure of the fundamental battery pack by the 1st Embodiment of this invention. It is a block diagram which shows the structure of the battery pack by the 2nd Embodiment of this invention. It is a block diagram which shows the structure of the fundamental battery pack by the 3rd Embodiment of this invention. It is a block diagram which shows the structure of the battery pack by the 4th Embodiment of this invention. It is a block diagram which shows the structure of the fundamental battery pack by the 5th Embodiment of this invention. It is a block diagram which shows the structure of the battery pack by the 6th Embodiment of this invention. It is a block diagram which shows the structure of the fundamental battery protection apparatus by the 7th Embodiment of this invention. It is a block diagram which shows the structure of the battery protection apparatus by the 8th Embodiment of this invention. It is a block diagram which shows the structure of the fundamental battery protection apparatus by the 9th Embodiment of this invention. It is a block diagram which shows the structure of the battery protection apparatus by the 10th Embodiment of this invention. It is a block diagram for demonstrating the structure of the conventional battery pack.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 3, 6, 9 ... Battery pack 2, 4, 5, 8, 7, 10 ... Device 11, BT ... Battery 12, 23 ... Positive electrode terminal 13, 24 ... Negative electrode terminal 14, 22, 32, 41, 51 ... Switch circuits 21, 25 ... Control terminals 31, 34 ... Voltage sense terminals 33, R11, R12, R21-R28, R31-R36 ... Resistors 42, 43 ... Sense terminals TR11, TR12, TR21-TR26, TR31-TR34 ... Transistor D31 …diode

Claims (6)

A battery having a positive electrode and a negative electrode;
A positive terminal for device connection;
A negative terminal connected to the negative electrode of the battery for connecting the device;
When it is detected that the positive electrode terminal and the negative electrode terminal are short-circuited externally because the potential of the positive electrode terminal is lower than the positive electrode of the battery, the positive electrode terminal and the positive electrode of the battery are connected. A battery pack comprising: switch means for separating and connecting between the positive electrode terminal and the positive electrode of the battery at other times. The switch means includes
A first switch for turning on and off between the positive electrode of the battery and the positive terminal,
Unless it is shorted by an external between the negative terminal and the positive terminal is off-controlled by the potential of the positive electrode of the battery, and if between the positive terminal and the negative terminal is short-circuited by an external to be on-controlled, battery pack according to claim 1, characterized by comprising a second switch for turning off the first of the first switch provides a control voltage to the switch. In a battery protection circuit built in a battery pack comprising a battery having a positive electrode and a negative electrode, a positive electrode terminal for device connection, and a negative electrode terminal for device connection and connected to the negative electrode of the battery,
When it is detected that the positive electrode terminal and the negative electrode terminal are short-circuited externally because the potential of the positive electrode terminal is lower than the positive electrode of the battery, the positive electrode terminal and the positive electrode of the battery are connected. A battery protection circuit comprising switch means for disconnecting and otherwise connecting between the positive terminal and the positive electrode of the battery. The switch means includes
A first switch for turning on and off between the positive terminal and the positive electrode of the battery;
Unless it is shorted by an external between the negative terminal and the positive terminal is off-controlled by the potential of the positive electrode of the battery, and if between the positive terminal and the negative terminal is short-circuited by an external to be on-controlled, battery protection circuit according to claim 3, characterized by comprising a second switch for the switch first off giving a control voltage to said first switch. A battery pack comprising a battery having a positive electrode and a negative electrode, a positive electrode terminal for device connection, a negative electrode terminal for device connection and connected to the negative electrode of the battery, and a device to which the battery pack is detachable In an electronic device having
The battery pack is
When it is detected that the positive electrode terminal and the negative electrode terminal are short-circuited externally because the potential of the positive electrode terminal is lower than the positive electrode of the battery, the positive electrode terminal and the positive electrode of the battery are connected. Switch means for disconnecting and otherwise conducting between the positive electrode terminal and the positive electrode of the battery
An electronic device comprising: The switch means includes
A first switch for turning on and off between the positive terminal and the positive electrode of the battery;
When the positive electrode terminal and the negative electrode terminal are not short-circuited externally, the battery is turned off by the positive electrode potential, and the positive electrode terminal and the negative electrode terminal are externally short-circuited A second switch that is on-controlled to apply a control voltage to the first switch to turn off the first switch;
The electronic apparatus according to claim 5, further comprising:

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