JPH08214468A - Battery charger and information processor incorporating it - Google Patents

Abstract

PURPOSE: To shorten the charging time for plurality of secondary batteries when the batteries are charged by using a single battery charger by stopping the supply of charging currents to the batteries when it is detected that the values of the charging currents supplied to the batteries have dropped from prescribed values. CONSTITUTION: A charging current supplying means 3 supplies charging currents to a plurality of batteries (for example, lithium ion batteries) 101 and 102 through a plurality of reverse-current inhibiting means (diodes) 2a and 2b. A charging current detecting means 4 detects the values of the charging currents supplied to the batteries 101 and 102. When the detecting means 4 detects that the values of the charging currents become lower than prescribed values, the supplying means 3 stops the supply of the charging currents to the batteries 101 and 102. Therefore, the charging time of the batteries 101 and 102 can be shortened when the batteries 101 and 102 are charged by using a single battery charger.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a charging device and a charging device for the same, which can reduce charging time by charging a plurality of rechargeable batteries (secondary batteries) in parallel using a single charging circuit. The present invention relates to an information processing device that operates using a battery charged by using as a power source. In a portable electronic device such as a laptop computer, a battery is mounted as a power source for the device, but due to the operating cost of the device and the instantaneous dischargeable current capacity, it is possible to use a battery such as Nicd, NiMH or Li +. Generally, a secondary battery is installed. In many cases, a charging device (charging circuit) is built in so that a secondary battery built in the device can be charged simply by connecting an AC adapter or the like to the device.

A battery pack that constitutes a secondary battery is constructed by connecting a plurality of battery cells in series in relation to the output voltage and power of the battery. The number of cells that can be connected in series depends on the battery voltage. The upper limit is defined in relation to the power supply voltage supplied from the outside. Considering that the withstand voltage of the power supply system in a general device is 16V, the maximum voltage per unit cell is about 1.7V in Nidd and NiMH, so the upper limit is 9 series connections, and Li + ( For lithium-ion batteries), the maximum voltage per cell is about 4.2 V, so the maximum limit is 3 cells connected in series.

On the other hand, the capacity per unit cell of a battery is defined by the basic capacity based on the size of the battery. Therefore, in order to increase the capacity of the battery, there is no method other than connecting a plurality of battery cells connected in series in parallel. However, the capacity of the battery can be increased by connecting a plurality of battery cells in series and parallel, but the physical size and weight of the battery pack and the device operated by the battery pack increase.

Therefore, instead of connecting the battery cells in series and parallel in one battery pack, the battery cells are connected in series in one battery pack, and a plurality of independent battery cells are connected according to the configuration of the device and the operating environment. It is more versatile to connect the battery packs in parallel.

[0005]

2. Description of the Related Art FIG. 10 is a diagram showing a conventional charging device for charging a plurality of batteries. Also, this figure 1
Reference numeral 0 indicates an information processing device such as a portable electronic device, which includes a power supply device that operates using an external power supply (for example, a power supply obtained by converting an alternating current of a commercial power supply into a direct current by an AC adapter) or a battery as a power supply. It is also something to do.

The information processing apparatus of this conventional example is equipped with two batteries (battery packs), and if there is power supply from an external power supply, it is used as the power supply, and if there is no power supply from the external power supply, then 2 It is operated by using one of the individual batteries as a power source. In FIG. 10, the secondary batteries 101 and 102 are
It is a rechargeable battery (battery pack) composed of a plurality of battery cells connected in series.

The DC connector 103 is used when the apparatus is operated by an external power source such as a commercial power source by an AC adapter or the like (not shown), or when the secondary batteries 101 and 102 incorporated in the apparatus are charged by the external power source such as an AC adapter. , A connector for receiving power supply from the outside. DC /
The DC converter 104 receives power supplied from the external power supply or the secondary battery 101 or 102 supplied via the DC connector 103, and performs voltage conversion to create a voltage required by the device.

The voltage comparator 105 detects that power is supplied from the DC connector 103, and D
The voltage of the C connector 103 is compared with the reference voltage e1 for voltage comparison, and when the voltage of the DC connector 103 is higher than the reference voltage e1, a high level is output and the charging control unit 1 described later.
06 is notified that power is being supplied from the DC connector 103. When the voltage of the DC connector 103 is lower than the reference voltage e1, a low level is output to notify the charging control unit 106 that the DC connector 103 is not supplying power.

The charging control unit 106 includes the secondary batteries 101, 10
This is a control unit for controlling the charging of the secondary battery 2, and instructs the charger 107 described later to start (on) or stop (off) charging of the secondary batteries 101 and 102. The charger 107 is a constant current power supply for generating the electric power required to charge the secondary batteries 101 and 102 when the electric power is supplied from the outside via the DC connector 103. Charger 107
Controls the charging power according to the on / off instruction from the charging control unit 106, and starts the charging operation to generate the charging power when on is instructed. Also, DC
When power is not supplied to the connector 103 or when the charging control unit 106 instructs off, the charger 107 is in a stopped state and does not generate charging power.

The resistor R11 is a secondary battery 101 or 102.
It is a sense resistor for measuring the charging current to the. The current measuring circuit 108 measures the voltage across the sense resistor R11 to measure the charging current value to the secondary battery 101 or 102, and notifies the charging control section 106 of the measured value. R12 is a sense resistor for measuring the discharge current from the secondary battery 101 or 102. The voltage drop across the resistor R12 is measured by the current measuring circuit 10
9, the charge control unit 106 receiving the measurement result obtains the remaining amount of the secondary battery 101 or 102 currently used. The obtained remaining amount is displayed on the display unit (not shown).

Diodes D11, D12 and D13
Is an AC adapter connected to the DC connector 103, but AC power is not being supplied.
It is a reverse current blocking protection diode for preventing electric power from flowing out from the secondary battery 101 or 102 when the adapter is in a non-operating state. Also, the diode D
21 and D22 are used for the secondary battery 101 in the DC / DC converter 104 when power is not supplied from the outside.
Alternatively, it is a protection diode for supplying electric power from 102 and preventing its voltage from being applied to the secondary batteries 101 and 102 when electric power is being supplied from the outside via the DC connector 103.

The transistors FET1 and FET2 are switch circuits for selecting the secondary battery to be charged, and the charging current supplied from the charger 107 is supplied to the secondary battery 1 by the switching circuit.
01 or the secondary battery 102 is controlled. Further, the transistors FET3 and FET4 supply the power of the secondary battery 101 when supplying the power of the secondary battery to the DC / DC converter 104 when the power from the AC adapter is not supplied via the DC connector 103. It is a switch circuit for controlling whether the power is supplied or the power of the secondary battery 102 is supplied. Secondary battery 101, 10
This switch circuit is not necessary if both 2 are always discharged in parallel at the same time.

In such a structure, the DC connector 1
When an electric power is supplied from the outside by connecting an AC adapter or the like to 03, the external power is supplied to the DC / DC converter 104 via the diode D11, and accordingly the DC / DC converter 104 operates as a device. Create the required voltage of. At this time, the external power is blocked by the diodes D21 and D22 and the secondary battery 10
1, 102 is not applied.

On the other hand, when the power is supplied from the outside, the power is supplied to the secondary battery 101 or 102 to perform charging, that is, the voltage comparison circuit 105 is supplied with the power from the outside. Is detected and the voltage comparison circuit 105
This is only when the charger 107 is producing electric power for charging in response to a charging instruction from the charging control unit 106 that has received the notification from. When the charger 107 is stopped, the circuit inside the charger is cut off and power is not supplied to the secondary battery 101 or 102. Then, the charge control unit 106 informs the voltage comparison circuit 10 that the power supply from the outside is interrupted.
5, the transistors FET3 and FE are notified.
The ON / OFF of T4 is controlled, and the power of the secondary battery is supplied to the DC / DC converter 104 via the diode D21 or D22, and the DC / DC converter 104 generates the voltage required by the device in response to this. . At this time,
The electric power is not blocked by the diodes D1, D21 or D22 and does not flow out.

The charger 10 is powered by electric power supplied from the outside.
The electric power generated by the operation of 7 charges the secondary battery 101 or the secondary battery 102 via the transistor FET1 or FET2. When the secondary battery 101 is charged, the charging control unit 106 turns on the transistor FET1 to close the current path to the secondary battery 101 to perform charging. At this time, since the charge control unit 106 turns off the transistor FET2, all the current generated by the charger 107 is used to charge the secondary battery 101. Here, since the voltage input from the DC connector 103 is higher than the voltage of the charger 107, the diode D
21 is in the reverse bias state, the secondary battery 101
Charging current to the DC / DC converter 104 does not leak to the secondary battery 102 side.

On the other hand, when the secondary battery 102 is charged, the charging control unit 106 turns on the transistor FET2 to close the current path to the secondary battery 102, thereby performing charging. At this time, the transistor FET1 is turned off.
Since the F state is set, all the current generated by the charger 107 is used to charge the secondary battery 102. Where D
Since the voltage input from the C connector 103 is higher than the voltage of the charger 107 and the diode D22 is in the reverse bias state, the charging current to the secondary battery 102 is DC.
/ DC converter 104 side leakage, secondary battery 101
It does not leak to the side.

As described above, conventionally, when a plurality of secondary batteries (battery packs) are charged by one charger, they are charged separately in order. . Japanese Patent Laid-Open No. 6-303729 is a conventional technique for parallel charging batteries.

The technology disclosed in Japanese Patent Application Laid-Open No. 6-303729 discloses a method of connecting a plurality of lithium-ion batteries to one lithium-ion battery according to claim 1 of the publication. When the battery is charged for a predetermined period of time, the next lithium ion battery is charged for a predetermined period of time, and after charging all of the plurality of lithium ion batteries for a predetermined period of time, all of the plurality of lithium ion batteries are simultaneously charged. And a means for controlling the supply of the charging current to the plurality of lithium ion batteries and a means for detecting the current value of the charging current. The charging current supply is switched from the one lithium-ion battery to the next lithium-ion battery when the charging current falls below a predetermined value. 1 charging apparatus according. "Claim 3
"When the charging currents to the plurality of lithium ion batteries are all less than or equal to the predetermined value, the charging currents are supplied in parallel to all of the plurality of lithium ion batteries. 2. The charging device according to claim 2, wherein the length of the period for supplying the charging current to all of the plurality of lithium ion batteries in parallel is regulated by the timer means. Item 3. The charging device according to item 3.

A specific configuration for realizing the above technique is as follows.
The publication is described on page 3, left column, line 11 to page 4, right column, line 5 and the description of the embodiment and FIG. 1 used for the description. FIG. 1 of this Japanese Patent Laid-Open No. 6-303729 is shown in FIG.
As shown. As described on page 21, left column, lines 21 to 28 of this publication, the output terminal C of the main charger 100 is
The terminals 2 of the charging device 200 connected to C are p
Through the emitters and collectors of the np-type transistors 3 ₁ , 3 ₂ , 3 ₃ , lithium-ion batteries BA ₁ , BA ₂ , B
Is connected to the contact A 4 ₁ one to be mounted in the _3, 4 _2, 4 _3, battery BA _1, BA _2, other contact 5 ₁ mounted in BA _3, 5 _2, 5 ₃ are connected to each other, This connection midpoint is connected to the terminal 7 of the charging device 200, which is connected to the ground terminal GND through the resistor 6.

Further, as described on the same page at the same column, lines 36 to 39, the detection terminal I of the control microcomputer 9 is connected to the middle point of connection of the other contacts 5 ₁ , 5 ₂ , 5 _3. Then, the voltage drop of the resistor 6 caused by the charging current is measured by the control microcomputer 9. Then, the charging of the plurality of lithium ion batteries BA ₁ , BA ₂ , BA ₃ by the charging device 200 is performed as follows.

First, as described on page 3, right column, lines 3 to 34, the control microcomputer 9 turns on the transistor 3 ₁ to start rapid charging of the battery BA ₁ and When the voltage drop of 6 is measured and the charging current becomes 350 mA or less, the transistor 3 ₁ is turned off and the battery BA ₁
To stop charging. Then, the transistor 3 ₂ is turned on to start charging the battery BA _2, and the voltage drop of the resistor 6 was measured, and the charging current was 350 mA or less, as in the case of charging the battery BA ₁ . When transistor 3
₂ is turned off to stop charging the battery BA ₂ . Similar to the batteries BA ₁ and BA ₂ , the battery BA ₃ is charged until the charging current becomes 350 mA or less. In this way, the batteries are switched and charged until the charging current to each of the batteries BA ₁ , BA ₂ , BA ₃ reaches a predetermined value.

As mentioned above, each battery BA₁, BA₂, B
A₃After charging the battery, page 34, right column, line 34, geno
Each transistor 3 as described in line 43₁,
Three₂, 3 ₃Turn on (in the publication, the output port CH₁, C
H₂, CH₃Is described as high level), battery B
A₁, BA₂, BA₃Put all in the charging state. That is,
Battery BA₁, BA₂, BA₃Parallel charging is performed.

Then, the timer means is measured, and when a predetermined time such as 2 hours elapses, all the circuits are turned off and the charging of all the batteries BA ₁ , BA ₂ , BA ₃ is completed. By such charging, each battery BA ₁ , BA ₂ ,
It takes about 1 hour each to bring the charge amount of BA ₃ to 70%, and then about 2 hours to simultaneously charge the batteries BA ₁ , BA ₂ and BA ₃ to about 100%. The charging of all three batteries is completed in about 5 hours in total.

[0024]

As described above, when a plurality of secondary batteries (battery packs) are charged by one charger, the secondary batteries to be charged from the plurality of secondary batteries are charged. A switch circuit such as a transistor for controlling the current path from the charger to the secondary battery to be charged is required.

Further, since a plurality of secondary batteries are charged in sequence, the charging time required to charge all the secondary batteries is double the number of secondary batteries, and the charging time increases. I will end up. For example, when one lithium-ion (Li +) secondary battery is charged with a current of 1.0 C, it is about 2.0-2.
It takes 5 hours and 2 when charging 2 rechargeable batteries
It took twice as long, i.e. about 4.0-5.0 hours.

Further, in Japanese Patent Application Laid-Open No. 6-303729, after charging a plurality of batteries individually while switching a plurality of batteries until the charging current becomes a predetermined value or less, when all the charged amounts of all the batteries reach a predetermined value, all are charged. The batteries are charged in parallel and the charging is completed when a predetermined time has elapsed from the start of the parallel charging. Therefore, as in the case of the above-mentioned charging, when individually charging, a switch circuit such as a transistor for selecting the battery to be charged and controlling the current path from the main charger to the battery to be charged is necessary.

Furthermore, when a battery is removed from the charging device during parallel charging of a plurality of batteries and another battery having a small amount of charge is attached, the charging is completed after a predetermined time has elapsed from the start of parallel charging. Before all the batteries attached to the battery are fully charged, all the batteries will be charged. Therefore, the operating time of the device using the battery may be shortened.

The present invention has been made in view of the above circumstances, and provides a charging device and hardware for reducing the charging time when charging a plurality of secondary batteries using a single charger. To provide a charging device that charges a plurality of secondary batteries with a simple circuit, a charging device that ensures a full charge to a plurality of secondary batteries, and a charge to a plurality of secondary batteries. An object is to provide an efficient charging device. Further, another object of the present invention is to provide an information processing device having an extended operating time when a secondary battery charged by using the above charging device is operated as a power source.

[0029]

FIG. 1 is a diagram showing the first principle of the present invention. In FIG. 1, 1 is a charging device. Two
Reference numerals a and 2b denote backflow preventing means, which are provided corresponding to the plurality of batteries 101 and 102 to be charged and are connected in parallel.

Reference numeral 3 is a charging current supply means, and the plurality of batteries 10 are connected through the plurality of backflow prevention means 2a and 2b.
A charging current is supplied to 1, 102. Further, the charging current detecting means 4 to be described later detects that each charging current value has become equal to or less than a predetermined value and stops supplying the charging current. Reference numeral 4 denotes a charging current detecting means, which detects each charging current value supplied to the plurality of batteries 101, 102.

The batteries 101 and 102 are lithium ion batteries. Further, each of the backflow prevention means 2
Let a and 2b be diodes. Reference numeral 10 denotes an information processing device, which incorporates the above-mentioned charging device 1 and uses as a power source a discharge current output in parallel from each of the plurality of batteries charged by the charging device 1.

FIG. 2 is a second principle diagram of the present invention. Figure 2
In, 1 is a charging device. Reference numeral 101 is a so-called secondary battery, which is a rechargeable battery built in the device. Also, 102
A and 102N are rechargeable batteries (secondary batteries) having a backflow prevention means, and are additional batteries that can be installed according to the user's needs. Battery 102 having this backflow prevention means
A and 102N are connected in parallel, and are connected in parallel to one terminal of the device.

Reference numeral 2a is a backflow prevention means, which is provided corresponding to the battery 101 to be charged. 3 is a charging current supply means, which supplies the charging current to the battery 101 via the backflow prevention means 2a and to the batteries 102A and 102N in parallel via one terminal. Further, the charging current detecting means 4 to be described later detects that each charging current value has become equal to or less than a predetermined value and stops supplying the charging current.

Reference numeral 4 denotes a charging current detecting means, which is the battery 1
The charging current value to 01 and the charging current values supplied to the batteries 102A and 102N are detected. FIG. 3 is a third principle diagram of the present invention. In FIG. 3, reference numeral 1 is a charging device. 3 is a charging current supply means, and the plurality of batteries 101, 1 via the plurality of backflow prevention means 2a, 2b.
02 to supply a charging current.

Switching means 5a and 5b are provided corresponding to each of the plurality of batteries 101 and 102 and are connected in parallel. Reference numeral 6 is a comparison means for comparing the battery voltage between the plurality of batteries 101 and 102. Reference numeral 7 is a control means for turning off the switching means corresponding to a battery having a low battery voltage based on the comparison result by the comparison means 6.

[0036]

In the first aspect of the invention, the backflow prevention means 2a, 2b for each of the plurality of batteries 101, 102 are connected in parallel,
The charging current supply means 3 supplies the charging current via the backflow prevention means 2a and 2b, and detects the charging current value supplied to each battery.

Backflow prevention means 2 is provided for each of such batteries.
By providing a and 2b, each battery is separated, and even if the battery voltage is unbalanced due to the difference in the remaining amount of the battery,
Current does not flow from a battery with a large remaining amount to a battery with a small remaining amount, and it becomes possible to charge a plurality of batteries in parallel. Then, when each charging current value becomes equal to or less than a predetermined value, the charging current supply means 3 stops supplying the charging current.

According to the configuration of the present invention as described above, even if the charging current value for judging the completion of charging of the battery is different due to the difference in manufacturers of the batteries or the like, the charging current value for judging completion of charging is set to the individual charging current value. If it is set to be compatible with batteries, it is possible to reliably detect the completion of charging without causing overcharging. The above battery is a lithium ion battery. This lithium-ion battery has the characteristics that when it is charged, it becomes constant after a predetermined battery voltage value and the charging current value decreases.

Utilizing this characteristic, the completion of charging is detected by detecting that the charging current value for each lithium-ion battery has fallen below a predetermined value. In addition, since diodes are used as the backflow prevention means 2a and 2b for charging current to the battery,
It does not require complicated circuits and special controls to prevent the reverse charging current.

In the second aspect of the invention, each of the plurality of additional batteries 102A, 102N to be charged has a built-in backflow blocking means, and the backflow blocking means of the additional battery is connected in parallel to one terminal. ing. Then, the charging supply means 3 supplies a charging current to the backflow prevention means 2a corresponding to the built-in battery and the terminal.

The charging current detecting means 4 detects the charging current value supplied to the built-in battery and the charging current value supplied to the terminal, and the charging supply means 3 detects each charging current value detected by the charging current detecting means 4. Is detected to be less than or equal to a predetermined value, the supply of charging current is stopped. In this way, the charging currents to the plurality of additional batteries 102A and 102N additionally installed by the user are not individually detected, but the additional batteries 1
Since only the charging current to one terminal to which the backflow prevention means of each of 02A and 102N is connected is detected, the circuit for detecting the charging current to each additional battery and its control signal can be reduced.

In the third invention, a plurality of batteries 10 are provided.
Switching means 5a, 5b for each of 1, 102
Are connected in parallel, and when the information processing apparatus is operated by using the discharge currents of the batteries 101 and 102 charged by the charge supply means 3a, the comparison means 6 compares the battery voltages of the batteries 101 and 102. , For example, when the battery voltage of the battery 101 is a predetermined value or less than the battery voltage of the battery 102,
The control means 7 turns off the switching means 5a corresponding to the battery 101 to disconnect the parallel connection of the switching means 5a and the switching means 5b.

As described above, by disconnecting the switching means to which the battery having the low battery voltage is connected, it is possible to prevent the inflow of current from the battery having the high battery voltage to the switching means.

[0044]

FIG. 4 shows the first embodiment of the present invention. In the configuration of FIG. 4, the same reference numbers are assigned to the same configurations as those of FIG. 10 of the prior art. In FIG. 4, the secondary batteries 101 and 102 are rechargeable batteries each composed of a plurality of battery cells connected in series, and are lithium-ion secondary batteries. The secondary battery may be built in an information processing device such as a portable electronic device or may be detachable from the device. The secondary battery is a so-called battery pack in which a plurality of battery cells connected in series are housed in one housing. The secondary batteries 101 and 102 are shown in FIG.
Compatible with multiple secondary batteries.

The DC connector 103 is supplied from the outside when the apparatus is operated by an external power source such as a commercial power source by an AC adapter (not shown) or when the secondary batteries 101 and 102 are charged by the external power source such as an AC adapter. Is a connector for receiving the power supply of. The DC / DC converter 104 receives a power supply from the external power supply supplied via the DC connector 103 or the secondary batteries 101 and 102, and performs voltage conversion to create a voltage required by the device. .

The voltage comparator 105 detects that power is being supplied from the outside via the DC connector 103, compares the voltage of the DC connector 103 with the reference voltage e1 for voltage comparison, and outputs DC. When the voltage of the connector 103 is higher than the reference voltage e1, it outputs a high level to notify the charging control unit 11 described later that power is being supplied from the DC connector 103. Further, when the voltage of the DC connector 103 is lower than the reference voltage e1, a low level is output to notify the charging control unit 11 that the DC connector 103 is not supplying power.

Diodes D1, D2 and D3 are DC
AC adapter is connected to connector 103, but AC
When the AC adapter is in a non-operating state due to the fact that power is not supplied, the secondary battery 101 or 102
This is a back-flow blocking protection diode for preventing power from flowing out from the outside. Further, the diodes D4 and D5 are connected to the DC when the power is not supplied from the outside.
The secondary battery 101 or 102 in the DC / DC converter 104
It is a protection diode for supplying the electric power from the secondary battery 101 and 102, while supplying the electric power from the external power source via the DC connector 103. The diodes D2 and D3 correspond to the backflow prevention means 2a and 2b in FIG.

The resistors R1 and R2 are sense resistors for measuring the charging current. The resistor R1 is for the secondary battery 101 and the resistor R2 is for the secondary battery 102. The current measuring circuits 13 and 14 measure the voltages across the sense resistors R1 and R2, respectively, and charge the secondary batteries 101 and 102 at the time of charging, and discharge the current values of the secondary batteries 101 and 102 at the time of discharging. The charging control unit 11 measures the measured value.
Notify to The current measuring circuits 13 and 14 have the same configuration.

FIG. 5 shows the configuration of the current measuring circuits 13 and 14. The resistance R is a resistance that is a current measurement target, and is the resistance 1 or the resistance 2 in FIG. As shown in FIG. 5, resistors Ra and R
The voltage divided by b is connected to be input to the positive terminal of the operational amplifier CMP1, and the voltage divided by the resistors Rc and Rd is connected to be input to the positive terminal of the operational amplifier CMP2. . Also, the operational amplifier C
The output of MP1 is connected so as to be input to the negative terminal of the operational amplifier CMP1 via the resistor Rf, and the operational amplifier CM is connected.
The output of P2 is connected via a resistor Rg so as to be input to the negative terminal of the operational amplifier CMP2, and each of them constitutes a differential amplifier.

The output from the operational amplifier CMP1 is connected so as to be input to the positive electrode side terminal of the operational amplifier CMP3 via the resistor Rh, and the output of the operational amplifier CMP2 is connected to the negative electrode side of the operational amplifier CMP3 via the resistor Ri. Connected to input to the terminal. In addition, the operational amplifier CMP
The output of 3 is also connected so as to be input to the negative terminal of the operational amplifier CMP3 via the resistor Rj, and constitutes a differential amplifier.

Since the voltage value V output from the operational amplifier CMP3 has a value corresponding to the voltage drop caused by the current I flowing through the resistor R, the current value I is I = voltage V ÷ (resistor R × these values. Amplification value by the circuit). The calculation of the current value I by the above equation is performed by the charge control unit 11 using the voltage value output from the current measuring circuit.

The charging control unit 11 includes the secondary batteries 101 and 102.
Is a control unit for controlling the charging of the secondary batteries 101, 102 to the charger 12, which will be described later, based on the measured value of the charging current by the current measuring circuits 13, 14. Instruct to stop. The resistors R1 and R2, the current measuring circuits 13 and 14, and the charging control unit 11 that calculates the charging current from the outputs of the current measuring circuits 13 and 14 correspond to the charging current detecting unit 4 in FIG.

The charger 12 receives the power from the outside through the DC connector 103, and when the secondary battery 101, 1
It is a constant current power supply for creating the power required to charge 02. The charger 12 turns on / off by the charging control unit 11.
The charging power is controlled according to the off instruction, and when on is instructed, the charging operation is started to generate the charging power. Further, when the DC connector 103 is not supplied with power or the charging control unit 11 instructs it to be off, the charger 12 is in a stopped state and does not generate charging power. The charger 12 corresponds to the charging current supply unit 3 of FIG. 1 and is the charging current detection unit 4 which is the charging control unit 1.
In accordance with the charge control instruction by 1, the power for charging is created and stopped.

FIG. 6 shows the structure of the charger 12. In FIG. 6, the main transistor TR1 performs a switching operation under the control of the control unit 1A and is a P-type MOSF.
ET. The choke coil L stores energy when the main transistor TR1 is on and discharges energy when the main transistor TR1 is off to smooth the intermittent current generated by the main transistor TR1.

The smoothing capacitor C smoothes the output of the main transistor TR1. The flywheel diode D causes the energy stored in the choke coil L while the main transistor TR1 is on to flow a clockwise current to the flyback circuit of the L-C-D during the off period of the main transistor TR1 to generate a secondary current. The power is supplied to the battery.

The resistors RA and RB divide the voltage on the current inflow side of the resistor RE, and the resistors RC and RD include the resistor RE.
The voltage on the current outflow side of is divided. Control unit 1A
Receives the power supply from the DC connector 103 and further receives inputs from the input terminals I1, I2 and I3, and controls the main transistor TR1. Further, the charging power is generated in response to a charging start instruction from the charging control unit 11 (not shown), and the generation of charging power is stopped in response to a charging stop instruction.

The power supply terminal of the control section 1A and the source of the main transistor TR1 are connected so that power from the DC connector 103 is supplied. The drain of the main transistor TR1 is grounded via the flywheel diode D connected in the reverse direction, and the smoothing capacitor C and the resistor RA are connected via the choke coil L.
It is connected to one terminal of RC and the resistor RE. Further, the control output from the control unit 1A is connected to the collector.

The other terminal of the resistor RA is grounded via the resistor RB and is connected to the input terminal I1 of the control section 1A. Similarly, the other terminal of the resistor RC is grounded via the resistor RD and is connected to the input terminals I2 and I3 of the control section 1A. The control unit 1A includes an input terminal I1 and an input terminal I
The input voltage input to 2 is compared, and the resistance RE
The voltage drop of is detected and the current flowing through the resistor RE is measured.

If the measured value is larger than a predetermined specified value, the main transistor TR1 is turned off, and if it is smaller than the specified value, it is turned on to stabilize the charging current. Further, the charging voltage is detected by the divided voltage of the resistors RC and RD input to the input terminal I3, and when the charging voltage is lower than a specified value, a control voltage for turning on the main transistor TR1 is applied to the collector of the main transistor TR1. When the output voltage is higher than the specified value, the control voltage for turning off the main transistor TR1 is output.

Under the control of the control section 1A, the current flowing while the main transistor TR1 is on is accumulated in the choke coil L, and the clockwise current flows to the flyback circuit L-C-D while the main transistor TR1 is off. Flows, and the voltage generated at that time is applied to the secondary battery.
In this way, the main transistor TR1 is controlled to stabilize the charging current and the output voltage.

Next, the secondary battery 101 having the structure shown in FIG.
The operation of charging 102 will be described. Voltage comparison unit 10
Reference numeral 5 compares the external voltage supplied via the DC connector 103 with the reference voltage e1 and outputs the result to the charging control unit 11. The charge control unit 11 has a voltage comparison unit 105.
When it is detected that the power is supplied from the outside by the output from, the charging start instruction is output to the charger 12.

The charger 12 instructed to start charging is
A charging current is created by external power supplied via the C connector 103, and the created charging current is supplied to the secondary batteries 101 and 102 via the diodes D2 and D3. The current measuring circuits 13 and 14 measure the charging currents to the secondary batteries 101 and 102, and output the measured values to the charging control unit 11.

When the measured value from the measured current values 13 and 14 becomes less than or equal to a predetermined specified value, the charge control section 11
An instruction to stop charging is output to the charger 12. The charger 12 stops the generation of the charging current and completes the charging in response to the charging stop instruction from the charging control unit 11. Furthermore, FIG.
The voltage and charging current of the secondary battery during charging by the charger 12 will be described using.

FIG. 7 shows the relationship between the battery voltage and the charging current when a lithium ion (Li +) secondary battery is charged using the charging device of the present invention. In FIG.
The solid line shows the charging characteristics when there is one secondary battery (battery pack), and the broken line shows the charging characteristics when there are two secondary batteries. The horizontal axis of the graph represents charging time, the upper axis of the vertical axis represents battery voltage during charging, and the lower axis represents charging current value.

When the battery voltage of the secondary battery is 2.5 V, the battery is emptied, and in FIG. 7, charging of the secondary battery is started from this empty state. First, charging with one secondary battery will be described. The voltage of the secondary battery at the start of charging is 2.5V
Then, 1.0C (a battery with a capacity of 1280mAH is 1300m
When you start charging with A), the first 24
The battery is charged with a current of 1300 mA for a minute, and the battery voltage rises accordingly. This area is called a constant current charging area.

When charging is continued, the battery voltage is 4.2V.
When the battery voltage reaches 4.2V, the charging current gradually decreases with the battery voltage kept at 4.2V, and the charging current value decreases to 0.5C (a battery having a capacity of 1280mAH is charged at 650mA) after about 18 minutes. This area is called a constant voltage charging area. If the battery is charged further, the charging current value will continue to drop with the battery voltage remaining at 4.2V, and the charging current value will decrease to 1 in about 1 hour and 18 minutes.
The charging current drops to 00 mA.

The lithium-ion secondary battery is charged at a constant voltage and a constant current, and when the charging current value is 100 mA or less, the charging is completed. Therefore, the charging is completed at this point. Therefore, the total time required to charge one lithium-ion secondary battery is 24 minutes in the constant current charging area and 18 minutes in the constant voltage charging area.
The total time of minutes and 1 hour and 18 minutes is about 2 hours.

Next, parallel charging of two secondary batteries will be described. The figure shows the case where the two secondary batteries are charged from an empty state. Charger 107
Charges with a charging current of 1300 mA regardless of the number of secondary batteries to be charged.

Since the battery voltage when both of the secondary batteries 101 and 102 are empty is balanced, the charging current value to each secondary battery is half of 1300 mA, which is 0.5 C (650 mA for a battery having a capacity of 1280 mAH). Charging will start with. When charging is started, charging is performed with a current of 650 mA for 1 hour and 8 minutes from the start of charging, and the battery voltage rises accordingly. (Constant Current Charging Region) When charging is continued, when the battery voltage reaches 4.2V, the charging current gradually decreases while the battery voltage remains 4.2V.

When the charging is further continued, the charging current value continues to drop, and the charging current drops to 100 mA in about 1 hour and 18 minutes. As described above, since the lithium-ion secondary battery is in the charging completed state when the charging current value is 100 mA or less, the charging is completed in this state.

Therefore, the total time required for charging two secondary batteries is the total of the charging time of 1 hour and 8 minutes in the constant current charging area and the charging time of 1 hour and 18 minutes in the constant voltage charging area. It will be about 2 hours and 26 minutes. In the charging control described above, the charging current value is increased in order to shorten the charging time, and the charging current value is set to, for example, 1.3 C (capacity of 1280 mAH,
When charged with a current of 700 mAH), the charging time in the constant current charging region is about 14 minutes, and then the constant voltage charging region is entered. Since the charging time in the constant voltage charging area is the same as the charging time in 1.0 C described above, the charging time in the constant current charging area is reduced from 24 minutes to 14 minutes. Charging time of 2 hours is about 1 hour 5
It only shortens to 0 minutes and remains almost unchanged.

As described above, according to the present invention, the two lithium ion secondary battery packs 101 and 102 are connected to the diode D1.
By connecting in parallel via D2 and performing parallel charging at the same time, it takes about 2 hours 2
It can be reduced to 6 minutes. The present invention also provides the first
The present invention is not limited to the case where the number of battery packs is two as in the above embodiment, and the present invention can be applied to two or more battery packs. It suffices to connect as many diodes as the number of battery packs to be connected in parallel and perform parallel charging simultaneously. By the way, when three lithium-ion secondary battery packs are connected in parallel via a diode as in the first embodiment and parallel charging is performed at the same time, the charging time is about 3 hours and 12 minutes. Conventionally, the time required to charge one battery pack was 8 hours (2 hours × 4 pieces = 8 hours), but when the present invention is applied, all battery packs are charged in about 4 hours, which is half the time. it can.

This is because the charger side has a charging capacity of 1300 mA, but the battery pack is charged at 1300 mA because the total charging time is 2 hours 26 when charging the two battery packs. Only 24 minutes of the minute. Furthermore, during 1 hour and 18 minutes of the total charging time of 2 hours and 26 minutes, the battery is charged with a current of 650 mA or less. That is, since the charger has the ability to charge two battery packs at the same time for 1 hour and 18 minutes of the 2 hours of the charging time, even if the charging is performed at the same time, the charging time is not affected. This is because it is not given.

Next, a second embodiment of the present invention will be described.
FIG. 8 is a diagram showing a second embodiment of the present invention, and the same reference numerals as those in FIG. 2 are given to the same configurations as those of the first embodiment. In FIG. 8, the secondary batteries 111, 11
Numerals 2 and 113 are rechargeable batteries each composed of a plurality of battery cells connected in series. This battery is the same battery pack as that of the first embodiment, the secondary battery 111 is built in the device, and the secondary batteries 112 and 113 are additionally installed by the user for the purpose of extending the operating time of the device. It was done.

The DC connector 103 is used when the apparatus is operated by an external power source such as a commercial power source by an AC adapter (not shown) or when the secondary batteries 101, 102 incorporated in the apparatus are charged by the external power source such as an AC adapter. , A connector for receiving power supply from the outside. DC /
The DC converter 104 receives power supplied from the external power supply or the secondary battery 101 or 102 supplied via the DC connector 103, and performs voltage conversion to create a voltage required by the device.

The voltage comparator 105 detects that power is being supplied from the outside via the DC connector 103, compares the voltage of the DC connector 103 with the reference voltage e1 for voltage comparison, and outputs DC. When the voltage of the connector 103 is higher than the reference voltage e1, it outputs a high level to notify the charging control unit 11 to be described later that power is being supplied from the DC connector 103. In addition, the DC connector 103
When the voltage is lower than the reference voltage e1, a low level is output to notify the charging control unit 12 that power is not supplied from the DC connector 103.

The diodes D1 and D7 are connected to the DC connector 1
The power from the secondary batteries 111, 112, 113 is prevented from flowing out to the outside when the AC adapter is in a non-operating state because the AC adapter is connected to the 03 but the AC power is not supplied. It is a protective diode for preventing reverse current for preventing. Further, the diode D6 supplies electric power from the secondary battery 111 to the DC / DC converter 104 when electric power is not supplied from the outside, and when electric power is supplied from the outside via the DC connector 103. , A protection diode for preventing the voltage from being applied to the built-in secondary battery 111.

Further, the secondary batteries for expansion 112, 1
A diode D8 is connected to 13 on the charging terminal side of each secondary battery. This diode D8 has an additional secondary battery 112, when the AC adapter is connected to the DC connector 103, but when the DC connector 103 is not supplied with power due to the AC power being not supplied or the like.
This is a reverse-flow blocking protection diode for preventing electric power from flowing out from 113. Similarly, a diode D9 is connected to the discharge terminal side of each secondary battery. The diode D9 is provided in the DC-DC converter 104 when the secondary battery 112, 1 is not supplied with electric power from the outside.
It is a protection diode for supplying electric power from 13 and preventing the electric power from being applied to the secondary batteries 112 and 113 when the electric power is supplied from the outside.

The resistor R3 is a sense resistor for measuring the charging current to the built-in secondary battery 111 and the discharging current from the secondary battery 111. Resistor R4 is an additional secondary battery 1
Sense resistor for measuring the charging current to 12,113. Further, the resistor R5 is an additional secondary battery 112, 11
3 is a sense resistor for measuring the discharge current from 3.

The current measuring circuit 15 measures the voltage across the resistor R3 to measure the charging current value to the secondary battery 111 during charging and the discharging current value from the secondary battery 111 during discharging. The measured value is notified to the charging control unit 11. The configuration of the current measuring circuit 15 is similar to that shown in FIG. The current measuring circuit 16 measures the voltage across the resistor R4 to measure the charging current value to the secondary batteries 112 and 113, and measures the voltage across the resistor R5 to discharge the secondary batteries 112 and 113. The current value is measured.
The current measuring circuit 16 has two circuits having the configuration shown in FIG. 5 for measuring the resistance R4 and for measuring the resistance R5.

The charging control unit 11 uses the secondary batteries 101 and 102.
Is a control unit for controlling the charging of the secondary batteries 101 and 102, and instructs the charger 107 (described later) to start (on) and stop (off) the charging of the secondary batteries 101 and 102. Further, the charging control unit 11 notified of the charging current value or the discharging current value obtains the remaining amount of the secondary batteries 101 and 102 from the current value, and controls the display unit (not shown) to display the remaining amount.

The charger 12 receives the power from the outside via the DC connector 103 when the secondary batteries 111, 1
It is a constant current power supply for creating the electric power required to charge 12,113. The charger 12 controls the charging power according to the on / off instruction from the charging control unit 11, and when the on instruction is given, starts the charging operation to generate the charging power. In addition, the power is not supplied to the DC connector 103, or the charging control unit 11 turns off.
When f is instructed, the charger 12 is in the stopped state and does not generate charging power.

The operation of the charger 12 is the same as that described with reference to FIG. Secondary battery 11 having such a configuration
The operation of charging 1,112,113 will be described with reference to FIG. The voltage comparison unit 105 uses the reference voltage e1 and the external voltage supplied via the DC connector 103.
And the result is output to the charging control unit 11.

When the charging control unit 11 detects from the output from the voltage comparison unit 105 that power is being supplied from the outside, it outputs a charging start instruction to the charger 12.
The charger 12 instructed to start charging is the DC connector 1
A charging current is generated by external power supplied via 03, the charging current is supplied to the built-in secondary battery 111 via the diode D7, and the additional secondary batteries 112 and 113 are charged via the diode D8. Supply current.

The current measuring circuit 15 measures the charging current to the secondary battery 111, and the current measuring circuit 16 measures the secondary battery 112,
The charging current to 113 is measured, and the measured value is output to the charging control unit 11. The charge control unit 11 measures the current value 1
When the measured values from 5 and 16 are less than or equal to a predetermined specified value, an instruction to stop charging is output to the charger 12. The charger 12 stops the generation of the charging current and completes the charging in response to the charging stop instruction from the charging control unit 11.

In this structure, the charging control unit 11 charges the secondary batteries 111, 112, 113 by the same control as described above. However, since the current measuring circuit 16 measures the charging current to the two secondary batteries 112 and 113,
The charge control unit 11 is less than or equal to twice the charging current value that is determined to be the completion of charging the built-in secondary battery 111 (for example, 200 mA or less when charging is completed at a charging current value of 100 mA or less as described above). Charge control is performed with the specified value as.

When the device is operated by using the secondary batteries 111, 112 and 113, the discharge current of the secondary battery 111 is measured by measuring the voltage drop due to the resistor R3 by the current measuring circuit 15. , The total discharge current of the secondary batteries 112 and 113 is measured by measuring the voltage drop due to the resistor R5 by the current measuring circuit 16.

The charge controller 11 receives the measured discharge current values and receives the remaining amount of the secondary battery 111 and the secondary battery 11
The combined residual amounts of 2 and 113 are calculated, and the calculated residual amount is controlled to be displayed on the display unit (not shown). As described above, by providing the reverse current blocking protection diode D8 on the charging terminal side and the charging prevention protection diode D9 on the discharging terminal side in the additional secondary batteries 112, 113,
When 113 is directly paralleled to the charging terminal of the device 10, the connection configuration is the same as that of the first embodiment. With such a connection configuration, the built-in battery 111 and the additional batteries 112 and 113 are all connected in parallel via the diode, so that charging can be performed under the same control as in the first embodiment.

Next, the third embodiment will be described. FIG. 9 is a diagram showing a third embodiment. In FIG. 9, the secondary batteries 211 and 212 are rechargeable batteries each composed of a plurality of battery cells connected in series, and are lithium-ion secondary batteries. The DC connector 103 supplies power from the outside when the device is operated by an external power source such as a commercial power source by an AC adapter (not shown) or when the secondary batteries 211 and 212 are charged by the external power source such as an AC adapter. Is a connector for receiving.

The DC / DC converter 104 is an external power source or a secondary battery 2 supplied via the DC connector 103.
The power is supplied from the power supply circuits 11 and 212, and voltage conversion is performed to create a voltage required by the device.
The voltage comparator 105 detects that power is being supplied from outside via the DC connector 103,
Reference voltage e1 for voltage comparison with the voltage of the DC connector 103
And the voltage comparator IC1 to compare the DC connector 10
When the voltage of 3 is higher than the reference voltage e1, it outputs a high level. Further, the voltage of the DC connector 103 is the reference voltage e1.
Outputs low level when lower. The NOT circuit NOT is for inverting the output of the voltage comparator IC1.

The diodes D1, Da, Db are connected to the DC connector 103 by an AC adapter, but the AC power is not supplied to the AC adapter, or the like.
When the adapter becomes inactive, the secondary batteries 211 and 211
It is a backflow blocking protection diode for preventing power from flowing out from the outside. Transistor FET5
The FET 6 is connected to the discharge terminals of the secondary batteries 211 and 212, respectively, and is DC when the power is not supplied from the outside.
-When the power from the secondary batteries 211 and 212 is supplied to the DC converter 104 and the power is supplied via the DC connector 103, the power is supplied to the secondary battery 21.
This is a switch circuit for protection for preventing the voltage from being applied to 1 and 212.

The voltage comparator IC2 is for comparing the voltages of the secondary battery 211 and the secondary battery 212, and e2 is a comparison reference for comparing the voltage of the secondary battery 211 with the voltage of the secondary battery 212. It is a reference voltage for The voltage comparator IC2 constantly compares the voltages of the secondary battery 211 and the secondary battery 212, and the voltage of the secondary battery 211 is compared with the secondary battery 212.
When it is lower than the reference voltage e2 by the reference voltage e2 or more, a low level is output, and when it is not, a high level is output.

Similarly, the voltage comparator IC3 is also the secondary battery 21.
2 and the voltage of the secondary battery 211 are compared, the low level is output when the voltage of the secondary battery 212 is lower than the voltage of the secondary battery 211 by the reference voltage e2 or more, and the high level is output otherwise. Output. NAND circuit NAND
1 outputs a low level to turn on the transistor FET5 when both the voltage comparator IC2 and the NOT circuit NOT output a high level, and either the voltage comparator IC2 or the NOT circuit NOT outputs a low level. While doing so, the transistor FET5 is turned off.

The NAND circuit NAND2 outputs a low level and outputs a low level when both the NOT circuit NOT and the voltage comparator IC3 output a high level.
When T6 is turned on and either the NOT circuit NOT or the voltage comparator IC3 outputs a low level, the transistor FET6 is turned off. The negative circuit NOT outputs the high level when the voltage comparator IC1 of the voltage comparison unit 105 outputs the low level, which is when the external power is not supplied via the DC connector 103. . Further, the voltage comparator IC2 outputs the high level when the voltage of the secondary battery 211 is higher than the reference voltage value e2 as compared with the voltage of the secondary battery 212, and the voltage comparator IC3 outputs the high level. This is done when the voltage of the secondary battery 212 is higher than the reference voltage value e2 as compared with the voltage of the secondary battery 211.

Therefore, when power is supplied from the outside via the DC connector 103, the NAND circuit N
AND1 and NAND2 are transistor FETs, respectively
5, FET 6 is turned off to prevent external power from being applied to the secondary batteries 211 and 212. In addition, the secondary battery 2
When the voltage of 11 is higher than the voltage of the secondary battery 212, the reference voltage e
When it is lower than 2, the NAND circuit NAND1 turns off the transistor FET5 to turn the secondary battery 211 into the secondary battery 2.
The discharge current from 12 is prevented from flowing in, and at other times, the transistor 5 is turned on to discharge the secondary battery 211.

Similarly, when the voltage of the secondary battery 212 is lower than the voltage of the secondary battery 211 by the reference voltage e2 or more, the NAND circuit NAND2 turns off the transistor FET6 to cause the secondary battery 212 to operate. Prevents the discharge current from flowing in from 211, and at other times, the transistor 6
Is turned on to discharge the secondary battery 212. That is, when the device is operated by discharging the secondary batteries 211 and 212 without external power supply, the transistor FET5,
The FET 6 is controlled to prevent the discharge current from flowing into the secondary battery having a low battery voltage, and the power loss is prevented by using the transistor.

With such a configuration, it is possible to reduce the power loss due to the backflow prevention means from the secondary battery at the time of discharging, and it is possible to extend the operating time when the device is operated using the charged battery. It will be possible. In FIG. 9, the case where the number of secondary batteries is two has been described, but the present invention is not limited to this, and the present invention can be applied to the case where more secondary batteries are used. In such a case, the results of comparing the battery voltages between the secondary batteries may be further compared, and finally, the secondary battery having the lowest battery voltage may be disconnected from the parallel connection.

[0098]

As described above, according to the present invention,
Each battery is separated by the backflow prevention means provided for each battery, and even if the battery voltage is unbalanced due to the difference in the battery remaining amount, the current flows from the battery with a large amount to the battery with a small amount. Does not flow, it becomes possible to charge a plurality of batteries in parallel, and the charging time to the batteries can be shortened. Further, since the diode is used as the reverse current blocking means connected in parallel, it is not necessary to provide a complicated circuit for control, and the hardware can be reduced.

When the battery built in the device and the battery for expansion are used, the above-mentioned backflow prevention means is built in the battery for expansion.
Since the reverse current blocking means of each extension battery was connected in parallel so that the discharge current from a plurality of extension batteries could be input to one input terminal of the device, measurement of the charging current for charging the battery via that terminal Can be done with one current measuring circuit. Therefore, since it is not necessary to provide a current measuring circuit for each additional battery, hardware and its control signal can be reduced.

In the charging operation, when each charging current value becomes equal to or less than the predetermined value, the supply of the charging current is stopped. Therefore, it is judged that the charging of the battery is completed due to the difference in manufacturers of the batteries. Even if there are cases where the charging current value differs, the charging completion value can be reliably detected without causing overcharging by setting the charging current value that determines that charging is completed for each battery. .

Further, when operating the information processing apparatus by using the parallel output of the charged batteries, the low battery voltage is disconnected from the parallel connection by the transistor to reduce the power loss due to the discharge current and reduce the operating time. It becomes possible to use the information processing device efficiently by extending the above.

[Brief description of drawings]

FIG. 1 is a first principle diagram of the present invention.

FIG. 2 is a second principle diagram of the present invention.

FIG. 3 is a third principle diagram of the present invention.

FIG. 4 is a diagram showing a first embodiment of the present invention.

FIG. 5 is a diagram showing a configuration of a current measuring circuit.

FIG. 6 is a diagram showing a configuration of a charger.

FIG. 7 is a diagram showing a relationship between a secondary battery voltage and a charging current during charging by a charger.

FIG. 8 is a diagram showing a second embodiment of the present invention.

FIG. 9 is a diagram showing a third embodiment of the present invention.

FIG. 10 is a diagram showing a conventional charging device.

FIG. 11 is a diagram showing another conventional charging device.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Charging device 101, 102 Battery 102A, 102N Expansion battery 2a, 2b Reverse current blocking means 3 Charging current supplying means 4 Charging current detecting means 5a, 5b Switching means 6 Comparing means 7 Control means 10 Information processing device

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[Procedure amendment]

[Submission date] February 8, 1995

[Procedure Amendment 1]

[Document name to be corrected] Drawing

[Correction target item name] All drawings

[Correction method] Change

[Correction content]

FIG.

[Fig. 2]

[Figure 3]

[Figure 5]

[Figure 6]

[Figure 4]

[Figure 7]

[Figure 8]

[Figure 9]

[Figure 10]

FIG. 11

 ─────────────────────────────────────────────────── ─── Continuation of the front page (72) Nobuo Tanaka, No. 1015 Kamiodanaka, Nakahara-ku, Kawasaki-shi, Kanagawa 1015 Ueda, Fujitsu Limited 72) Inventor Hidekiyo Ozawa 1015 Kamiodanaka, Nakahara-ku, Kawasaki City, Kanagawa Prefecture, Fujitsu Limited

Claims (6)

[Claims] 1. A charging device for charging a plurality of rechargeable batteries, comprising: a plurality of backflow blocking means provided corresponding to the plurality of batteries, connected in parallel; and a plurality of the backflow blocking means via the plurality of backflow blocking means. A charging current supply unit that supplies a charging current to the battery, and a charging current detection unit that detects each charging current value supplied to the plurality of batteries, the charging current supply unit, by the charging current detection unit A charging device, characterized in that the supply of charging current is stopped by detecting that each detected charging current value has become a predetermined value or less. 2. The charging device according to claim 1, wherein each of the batteries is a lithium ion battery. 3. The charging device according to claim 1, wherein each of the reverse current blocking means is a diode. 4. A charging device according to any one of claims 1 to 3 is built-in, and a discharge current output in parallel from each of the plurality of batteries charged by the charging device is used as a power source. Information processing device. 5. The plurality of batteries comprises a plurality of extension batteries each having a built-in battery and a backflow prevention means, and the backflow of the plurality of extension batteries is made to one terminal for inputting a discharge current from the extension battery. The information processing apparatus according to claim 4, wherein the blocking means are connected in parallel. 6. A plurality of switching means provided corresponding to the plurality of batteries and connected in parallel, a comparing means for comparing battery voltages between the plurality of batteries, and a comparison result by the comparing means, The information processing apparatus according to claim 4, further comprising: a control unit that turns off a switching unit corresponding to a battery having a low battery voltage.