JP2000175366A - Charging system, battery pack, and charger - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a charging system capable of fully charging a constant- voltage charging battery at all times while a short circuit of the charging battery caused by a connection between input terminals of the battery pack is prevented surely. SOLUTION: A battery pack 1 used in a charging system includes a circuit breaker 20 for opening or closing a charging path between a lithium battery 10 and an input terminal 13. An operation switch 22 for closing a charging path is provided, and when a voltage is applied to the input terminals 12 and 13, the circuit breaker 20 is operated so that a base current of the circuit breaker 20 is made to flow and the charging path is closed. When the battery pack 1 is not connected to a charger 5, the charging path is cut off by the circuit breaker 20, so the lithium battery 10 is not short-circuited even if a metallic member and the like is put in contact with the input terminals 12 and 13. In addition, when the battery pack 1 is connected to the charger 5, the lithium battery 10 is not damaged by an overcurrent, and full charge is always carried out because a transistor with a small drop in voltage is used as the circuit breaker 20.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a charging system in which a battery pack is mounted on a charger to charge a constant-voltage rechargeable battery built in the battery pack, and a battery pack and a charger used in the charging system. .

[0002]

2. Description of the Related Art Conventionally, a battery pack has been used as a power source for a small portable device such as a mobile phone and a bar code reader. As a charging system for charging the battery pack, a system for charging the battery pack together with the portable device together with the portable device so as to be able to charge without removing the battery pack from the portable device body is generally adopted. .

[0003] As shown in FIG. 6, a battery pack P1 used in such a charging system has a built-in rechargeable battery P10, and the power discharged from the rechargeable battery P10 (hereinafter referred to as "discharge power"). Consumer equipment P3 to consume
(For example, the above-mentioned small portable device), a pair of output terminals P14, P15, and the output terminals P14, P15.
15 and a pair of input terminals P12 and P13 connected to a charger P5 that supplies electric power for charging the rechargeable battery P10 (hereinafter referred to as “charging power”). Further, in the battery pack P1, a metal piece or the like is brought into contact between the poly switch PS made of a high resistance element for adjusting the current value of the discharge power output from the rechargeable battery P10 and the input terminals P12 and P13, A diode P20 for preventing the rechargeable battery P10 from being short-circuited. One input terminal P12 is directly connected to the negative electrode of the rechargeable battery P10, and the other input terminal P13 is connected to the positive electrode of the rechargeable battery P10 via the diode P20. One output terminal P14 is connected to the negative electrode of the rechargeable battery P10 via the polyswitch PS, and the other output terminal P15 is directly connected to the rechargeable battery P10.
It is connected to ten positive electrodes. The diode P20 is connected such that the direction from the input terminal P13 to the positive electrode of the rechargeable battery P10 is a forward direction.

[0004] The battery pack P1 constructed as described above.
Are connected to the input terminals P12 and P13 when attached to the charger P5.
And the supply terminal P50 of the charger P5 conducts, and
The direction in which the charging current flows, that is, the direction from the input terminal P13 to the input terminal P12 via the rechargeable battery P10 is
Since the direction coincides with the forward direction of the diode P20, charging power is supplied from the charger P5 to the rechargeable battery P10, and charging is performed. On the other hand, when the battery pack P1 is detached from the charger P5, for example, a metal piece or the like is connected to the input terminal P12,
The direction in which the short-circuit current flows even when contact is made between P13, that is, from the positive electrode of the rechargeable battery P10 to the input terminal P1
3. Since the direction toward the negative electrode of the rechargeable battery P10 via the metal piece and the input terminal P12 does not coincide with the forward direction of the diode P20, the rechargeable battery P10 does not short-circuit.

Therefore, by using this charging system, the rechargeable battery P10 can be charged simply by mounting the battery pack P1 on the charger P5, and even if the battery pack P1 is removed from the charger P5, the charging is performed. The short circuit of the battery P10 can be prevented.

As the rechargeable battery P10 built in the battery pack P1, in recent years, from the viewpoint of portability, many lithium ion batteries (hereinafter, referred to as "lithium batteries") having a light weight and a large charge capacity have been used. Used. This lithium battery is a so-called constant voltage type rechargeable battery that charges at a constant inter-electrode voltage applied between both electrodes of the battery for charging. That is, when a lithium battery is charged beyond the charge capacity determined at the time of manufacture, the performance of the battery is greatly deteriorated. That)
Must be reliably prevented from exceeding.

Therefore, in a conventional charging system, a battery pack P including this lithium battery is used as a rechargeable battery P10.
In order to supply the charging power to the rechargeable battery P10, the charging of the input terminal P12,
The terminal voltage applied to P13 was set.

[0008]

However, in the conventional charging system, the forward voltage of the diode P20 changes due to the heat generated by the diode P20 and the like, room temperature, and the like.
There is a problem that it is difficult to grasp the voltage drop at the diode P20. For this reason, if the voltage between terminals is set to a large value in anticipation of a large voltage drop in the diode P20, when the charging current of the rechargeable battery P10 approaches full charge and the charging current decreases, the voltage between the electrodes exceeds the upper limit voltage. There was a problem that the battery was damaged. Also, the rechargeable battery P1
0 is set so that the voltage between the electrodes does not exceed the upper limit voltage, when the charging current of the rechargeable battery P10 approaches full charge and the charging current decreases, the voltage between the electrodes increases. There has been a problem that P10 falls below a voltage value (hereinafter referred to as “lower limit voltage”) at which the performance of the battery can be sufficiently exhibited.

Therefore, it is conceivable to charge the rechargeable battery P10 by constantly monitoring the inter-electrode voltage, adjusting the inter-terminal voltage based on this monitoring, and always maintaining the inter-electrode voltage at an optimum voltage value. The configuration for this is shown in FIG.
As shown in FIG. 5, input terminals P12, P
13, a detection terminal P for detecting the voltage between electrodes
And a lithium battery P10 from the detection terminal P18 via a high resistance P19 for reducing short-circuit current.
To the positive electrode of With this configuration, on the charger P5 side, the detection terminal P18 and the input terminal P
The voltage between terminals 12, i.e., the voltage between the electrodes, is detected, and the voltage between the terminals is changed.

However, in this case, the voltage between the electrodes is detected, and
A charger having a function of adjusting the voltage between terminals must be prepared, and there is a problem that the cost of the entire charging system increases. In addition, although the detection terminal P18 and the input terminal P12 are connected, the short circuit of the lithium battery P10 cannot be effectively prevented even though the detection terminal P18 is connected via the high resistance P19. Further, the number of terminals is increased, which is not preferable in design.

In view of the above, the present invention provides a charging system which can reliably prevent a short circuit of a rechargeable battery due to connection between input terminals of a battery pack and can always fully charge a constant voltage rechargeable battery. It is an object to provide a battery pack and a charger used for the system.

[0012]

According to a first aspect of the present invention, there is provided a charging system, comprising: a charging / discharging circuit for connecting and disconnecting a charging circuit on a charging circuit of a battery pack connecting an input terminal and a constant voltage type rechargeable battery; Only when it is detected that the battery pack is attached to the charger, the operating means closes the switch, so that when the constant voltage type rechargeable battery is charged, the charging circuit is connected, Otherwise, the charging circuit is disconnected.

That is, in the charging system according to the first aspect, the short circuit is prevented by a simple method of closing the charging circuit during charging and opening the charging circuit during non-charging. On the other hand, when charging the constant voltage type rechargeable battery, even if the state of charge changes, for example, the constant voltage type rechargeable battery approaches full charge, the fluctuation of the inter-electrode voltage with respect to the inter-terminal voltage is so small that it can be ignored. Therefore, when the charging system according to claim 1 is used, when charging the constant-voltage rechargeable battery, an inter-electrode voltage exceeding the upper limit voltage is applied, and the constant-voltage rechargeable battery is damaged or falls below the lower limit voltage. The possibility that the battery cannot be fully charged by applying the voltage between the electrodes becomes extremely small.

Therefore, with the use of the charging system according to the first aspect of the present invention, when charging the constant voltage rechargeable battery, it is possible to always fully charge the rechargeable battery, and when the battery pack is not equipped with a charger. In addition, it is possible to reliably prevent the constant voltage type rechargeable battery from being short-circuited by connecting the input terminals with a metal piece or the like. In addition, when the charging system according to the first aspect is used, only two terminals are provided on the surface of the battery pack, which is preferable in terms of design.

In addition, as a method of detecting that the operating means is mounted on the charger, a switch is detected by detecting that a voltage is applied between the input terminals as in the charging system according to the second aspect. May be closed, or
As in the charging system according to claim 3, the charger includes:
The battery pack may include a notification unit that notifies the approach of the charger, and the fact that the battery pack approaches the charger may be detected by the notification from the notification unit. As means for notifying the approach, an electromagnet, a magnet, or the like may be used, or a laser or the like may be used.

By the way, a transistor generally has a switching characteristic because a voltage characteristic between a collector and an emitter hardly fluctuates due to room temperature, heat generated by the transistor itself, and the like, and a falling voltage value is small as compared with a diode. Used as an element.

Therefore, as in the charging system according to the fourth aspect, it is preferable to use a transistor as the switch. This is because, even if a voltage obtained by adding a voltage obtained by adding a voltage dropped by a transistor to a voltage between electrodes as a voltage between terminals is set, the transistor has the above-described property,
When the constant voltage rechargeable battery approaches full charge, there is little possibility that the voltage between the electrodes exceeds the upper limit voltage or falls below the lower limit voltage, so that the constant voltage rechargeable battery can always be fully charged and short-circuited. Is reliably prevented.

As the battery pack used in the charging system, those described in claims 5 to 7 and claim 9 are preferable. Among them, the charger according to claim 7 is preferable as the charger suitable for the battery pack according to claim 6.

[0019]

DESCRIPTION OF THE PREFERRED EMBODIMENTS One embodiment of the present invention will be described below. Here, FIG. 1 is a front perspective view and a rear perspective view of a bar code reader to which the charging system of the present embodiment is applied, and FIG. 2 is a front view and a rear view of a battery pack to which the charging system of the present embodiment is applied. It is.

The bar code reader 3 to which the charging system of this embodiment is applied is provided with a plurality of buttons 32 for operating the bar code reader on the surface as shown in FIG.
As shown in FIG. 1B, a fixing place 34 for mounting and fixing the battery pack 1 serving as a power source of the barcode reader 3 is provided. The fixing place 34 is provided at the fixing place 34 as shown by an arrow in FIG. Is inserted and fixed. As shown in FIG. 1, the barcode reader 3 is configured such that when the battery pack 1 is attached, the barcode reader 3 and the battery pack 1 are externally integrated.

The battery pack 1 used as a power source for the bar code reader 3 has a structure as shown in FIG.
A pair of input terminals 12 and 13 for inputting electric power for charging the battery pack 1 (hereinafter referred to as “charging electric power”) are provided on the front surface, and as shown in FIG. A pair of output terminals 14 and 15 for outputting power (hereinafter, referred to as “discharge power”) supplied from the battery pack 1 to the barcode reader 1 are provided. When the battery pack 1 is mounted on the barcode reader 1, the back surface on which the output terminals 14 and 15 of the battery pack 1 are provided is inserted into the fixed place 34 so as to face the barcode reader 3. Then, when the battery pack 1 is fixed to the fixing place 34, the output terminals 14, 1 are attached to the bar code reader 3.
Since the power receiving terminal 30 (see FIG. 3) is provided to face the power receiving terminal 5, the output terminals 14 and 15 come into electrical contact with the power receiving terminal 30. Then, the barcode reader 3 receives supply of discharge power from the rechargeable battery via the power receiving terminal 30.

The bar code reader 3 is connected to the battery pack 1
A power receiving terminal 30 for inputting discharge power discharged from the lithium battery 10 is provided at a position facing the output terminals 14 and 15 provided on the barcode reader main body 3. 15 and power receiving terminal 30
Are conducted, and charging power is supplied from the battery pack 1 to the barcode reader main body 3.

The charger 5 is provided with a mounting place (not shown) in which the battery pack 1 can be mounted while the battery pack 1 is fixed to the bar code reader main body 3. When the battery pack 1 is mounted in this mounting place, A pair of supply terminals 50 (see FIG. 3) are provided so as to face the input terminals 12 and 13, and when the battery pack 1 is attached to the charger 5, the input terminals 12 and 13 are provided.
13 and the supply terminal 50 are electrically connected, and charging power is supplied from the charger 5 to the battery pack 1. The terminal voltage, which is the voltage applied between the input terminals 12 and 13 by the charger 5, is set to a voltage value obtained by adding the voltage dropped by the switch 20 to the upper limit voltage of the lithium battery 10. .

Next, the battery pack 1 will be described in detail. Here, FIG. 3 is a circuit diagram of the battery pack 1. Battery pack 1 to which the charging system of the present embodiment is applied
As shown in FIG. 3, a polyswitch PS including a lithium-ion battery (hereinafter referred to as “lithium battery”) 10 and a high-resistance element for limiting the current value of the discharge power output from the lithium battery 10 And a switch 20 composed of a PNP transistor for interrupting a charging circuit connecting the positive electrode of the lithium battery 10 and the input terminal 13. One input terminal 12 is directly connected to the negative electrode of the lithium battery 10, and the other input terminal 13 is connected to the positive electrode of the lithium battery 10 via the switch 20 as described above. Have been. Further, one output terminal 14 is connected to the negative electrode of the lithium battery 10 via the polyswitch PS, and the other output terminal 15 is directly connected to the positive electrode of the lithium battery 10.

Further, the battery pack 1 has an operation switch 22 composed of an NPN transistor for closing the switch 20 by detecting that a terminal voltage is applied between the input terminals 12 and 13; The switch includes a pair of voltage detection resistors 24 and 25 for detecting a voltage between terminals, and an adjustment resistor 26 for adjusting a base current of the switch 20.
The operation switch 22 has a collector connected to the adjustment resistor 26.
Is connected to the base of the switch 20, and the emitter is connected to the input terminal 12, and the base is connected to the input terminal 12 via one voltage detection resistor 24 and to the input terminal 13 via the other voltage detection resistor 25. Have been. The voltage detecting resistors 24 and 25 divide the voltage between the input terminals 12 and 13 when the voltage between the terminals is applied to the input terminals 12 and 13,
The trigger voltage required to close the activation switch 22 is
The operation switch 22 is combined so as to be applied between the base and the emitter.

In the battery pack 1 configured as described above, when a terminal voltage is applied to the input terminals 12 and 13,
First, the voltage between the terminals is divided into the voltage detection resistors 24 and 25 according to the respective resistance values, and a trigger voltage is applied between the base and the emitter of the operation switch 22 so that the operation switch 2
2 operates, and the collector-emitter of the operation switch 22 conducts. Then, the base current of the switch 20 flows through the operation switch 22, the collector-emitter of the switch 20 conducts, the charging circuit connecting the lithium battery 10 and the input terminal 13 is connected, and the charging power is reduced. It is supplied to.

On the other hand, when the supply of the charging power to the input terminals 12 and 13 is stopped, the trigger voltage is not applied to the operation switch 22, so that the base current of the switch 20 flowing between the emitter and the collector of the operation switch 22 is reduced. Shut off,
Since there is no conduction between the collector and the emitter of the switch 20,
The charging circuit is interrupted. Therefore, at this time, the input terminal 1
The lithium battery 10 does not short-circuit even if a metal contacts so as to pass between 2 and 13.

When the lithium battery 10 is charged, the adjusting resistor 26 controls the charging current passing through the switch 20 according to the generally known current characteristics of the base current and the value of the current flowing between the collector and the emitter. The current value is limited so that an excessive charging current does not flow into the lithium battery 10.

As described above, in the charging system according to the present embodiment, the switch 20 for connecting and disconnecting the charging circuit by the operation switch 22 is provided on the charging circuit of the battery pack 1 connecting the input terminal 13 and the lithium battery 10. Provided, input terminal 1
The operation switch 22 closes the switch 20 only when the terminal voltage is applied between the terminals 2 and 13, that is, when it is detected that the battery pack 1 is attached to the charger 5. When 10 is charged, the charging circuit is connected; otherwise, the charging circuit is disconnected.

That is, in the charging system according to the present embodiment, the charging circuit is closed during charging and the charging circuit is opened during non-charging to prevent a short circuit, and a switch 20 for interrupting the charging circuit is provided. Since a transistor having a voltage characteristic as described above in the section of the solution is used,
Unlike the conventional charging system, when the lithium battery 10 is charged, even if the state of charge changes, for example, the lithium battery 10 approaches full charge, the voltage between terminals applied between the input terminals 12 and 13 cannot be changed. The fluctuation of the voltage between the electrodes applied between the electrodes of the battery 10 is small. Therefore, it is extremely unlikely that the inter-electrode voltage becomes higher than the upper limit voltage or lower than the lower limit voltage as described above, and becomes a voltage at which the lithium battery 10 cannot be fully charged. Therefore, when the lithium battery 10 is charged using the charging system of the present embodiment, the lithium battery 10 may be damaged by applying an inter-electrode voltage too much, or may be fully charged because the voltage applied with the inter-electrode voltage is too small. The possibility of disappearance is extremely small.

Therefore, by using the charging system of the present embodiment, the lithium battery 10 can always be fully charged when charging, and when the battery pack 1 is not mounted with the charger 5, the input terminal Short-circuiting of the lithium battery 10 due to, for example, a connection between the terminals 12 and 13 by a metal piece or the like can be reliably prevented. In addition, when the charging system of this embodiment is used, only two terminals (input terminals 12 and 13) are provided on the surface of the battery pack 1, which is preferable in terms of design. Further, since the adjusting resistor 26 is provided to limit the current value of the charging current passing through the switch 20, if the resistance value of the adjusting resistor 26 is set in accordance with the charging characteristics of the lithium battery 10, Charging more suitable for the conditions for charging the lithium battery 10 can be performed, and the life of the lithium battery 10 can be prolonged.

In this embodiment, an NPN transistor is used as the operating means of the present invention. However, as shown in FIG. 4, it is assumed that the battery pack 1 is mounted on the charger 5 as shown in FIG. By providing a notification coil 52 composed of an electromagnet for notification, attaching a reed switch 90 that closes when the notification coil 52 is excited to the battery pack 1, and connecting the base of the switch 20 to the reed switch 90,
When the battery pack 1 approaches the charger, the reed switch 90
May be operated to close the switch 20, so that the switch 20 can be charged.

Alternatively, as shown in FIG. 5, the reed switch 92 is directly mounted on the charging circuit, and when the battery pack 1 is mounted on the charger 5, the reed switch 92 is closed.
Charging power may be supplied to the lithium battery 10 via the reed switch 92.

The operation switch 22 and the reed switch 90 of this embodiment correspond to the operation means of the present invention, and the reed switch 92 corresponds to the operation means and the switch of the present invention. Further, the notification coil 52 of the present embodiment corresponds to the notification means of the present invention.

[Brief description of the drawings]

FIG. 1 is a circuit diagram of a battery pack, a charger, and a main body of a barcode reader used in a charging system according to an embodiment.

FIG. 2 is a front view and a back view of a battery pack used in the charging system of the present embodiment.

FIG. 3 is a front perspective view and a rear perspective view of a barcode reader used in the charging system of the present embodiment.

FIG. 4 is a circuit diagram of a modification of the embodiment.

FIG. 5 is a circuit diagram of a modification of the present embodiment.

FIG. 6 is a circuit diagram of a battery pack, a charger, and a main body of a barcode reader used in a conventional charging system.

FIG. 7 is a circuit diagram of a battery pack, a charger, and a main body of a barcode reader used in a conventional charging system.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Battery pack, 3 ... Bar code reader main body, 5 ... Charger, 10 ... Lithium battery, 12, 13 ... Input terminal, 1
4, 15 output terminal, 20 switch, 22 operation switch, 24, 25 voltage detection resistor, 26 adjustment resistor, 30
... power receiving terminal, 50 ... supply terminal, 52 ... notification coil, 90
... Reed switch, 92 ... Reed switch, PS ... Poly switch

Claims (9)

[Claims] 1. A battery pack having a built-in constant-voltage rechargeable battery for charging at a constant voltage and having a pair of input terminals electrically connected to respective electrodes of the constant-voltage rechargeable battery, and the battery. A charger provided with a supply terminal that contacts the input terminal when the pack is mounted, and a charger that supplies charging power for charging the constant-voltage rechargeable battery to the battery pack via the supply terminal; In a charging system in which a battery pack is mounted on the charger to charge the constant voltage type rechargeable battery, the battery pack is provided on a charging circuit connecting the constant voltage type rechargeable battery and the input terminal. A charging system comprising: a switch for intermittently connecting a charging circuit; and operating means for closing the switch when detecting attachment to the charger and connecting the charging circuit. 2. The charging system according to claim 1, wherein the operating unit detects that a voltage is applied between the input terminals.
A charging system, wherein the switch is closed. 3. The charging system according to claim 1, wherein the charger includes a notifying unit that detects approach of the battery pack and notifies the operating unit of the battery pack, and the operating unit receives a notification from the notifying unit. A charging system for closing the switch. 4. The charging system according to claim 1, wherein the switch is a transistor. 5. A battery pack including a constant-voltage rechargeable battery for charging at a constant voltage and having a pair of input terminals electrically connected to respective electrodes of the constant-voltage rechargeable battery. A switch provided on a charging circuit connecting the voltage-type rechargeable battery and the input terminal and intermittently connecting the charging circuit, and a charger for supplying charging power for charging the constant-voltage rechargeable battery to the battery pack. Operating means for closing the switch when detecting that the charging is performed, and connecting the charging circuit. 6. The battery pack according to claim 5, wherein the operating unit detects that a voltage is applied between the input terminals.
A battery pack wherein the switch is closed. 7. The battery pack according to claim 5, wherein the operation means closes the switch when detecting that the battery pack approaches the charger. 8. A charger comprising: a notifying unit that notifies the operating unit that the battery pack according to claim 7 is approaching the charger. 9. The charging pack according to claim 5, wherein the switch is a transistor.