JP2003143768A - Power supply circuit and information processor with the power supply circuit built in - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve the problem, that, when a plurality of batteries are connected in parallel to a power supply circuit to be discharged in parallel with each other, voltages of the respective batteries may different. SOLUTION: When a plurality of batteries are connected in parallel with each other with switching means corresponding to the respective batteries and an information processor is made to operate by discharge currents of the batteries charged by a charging current supply means, the voltages of the plurality of batteries are compared with each other by a comparison means, and if the voltage of one battery is lower than the voltage of the other battery by a prescribed value or more, a control means turns off the switching means corresponding to the other battery and cuts off the parallel connection.

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 notebook 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,
In general, a secondary battery such as Nicd, NiMH, Li +, etc. is mounted. 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. The battery pack that constitutes the secondary battery is configured by connecting a plurality of battery cells in series in relation to the output voltage and power of the battery, but the number of cells that can be connected in series is
The upper limit is defined by the relationship between the battery voltage and the power supply voltage supplied from the outside. The withstand voltage of the power supply system in a general device is 16V
Considering that, in Nidd and NiMH, the maximum voltage per unit cell is about 1.7 V, so the upper limit is 9 series connections, and in Li + (lithium ion battery), the voltage per unit cell is Since the maximum is about 4.2V, the upper limit is 3 series connections. On the other hand, the capacity per unit cell of the 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 are increased. To do. Therefore, instead of connecting the battery cells in series in parallel in one battery pack, the battery cells are connected in series in one battery pack, and a plurality of independent battery packs are formed depending on the configuration of the device and the operating environment. It is more versatile to connect in parallel.

[0004]

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 uses power supplied from an external power source as power source, and two batteries when no power source is supplied from the external power source. One of these is used as a power source.

In FIG. 10, the secondary batteries 101, 102
Is a rechargeable battery (battery pack) composed of a plurality of battery cells connected in series. DC connector 103
Is an external power supply when the device 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 device are charged by the external power source such as the AC adapter. Is a connector for receiving.

The DC / DC converter 104 is an external power source or a secondary battery 1 supplied via the DC connector 103.
The power is supplied from 01 or 102, and voltage conversion is performed to create a voltage required by the device. The voltage comparator 105 detects that power is being supplied from the DC connector 103, compares the voltage of the DC connector 103 with the reference voltage e1 for voltage comparison, and the voltage of the DC connector 103 is the reference voltage e1. When it is higher, a high level is output to notify the charging control unit 106, which will be described later, that power is being supplied from the DC connector 103. Further, the voltage of the DC connector 103 is the reference voltage e.
When it is lower than 1, a low level is output and the charging control unit 106
Is notified that power is not supplied from the DC connector 103. The charging control unit 106 includes the secondary batteries 101 and 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 receives the secondary battery 101, when the power is supplied from the outside through the DC connector 103.
It is a constant current power supply for generating the electric power required to charge 102. The charger 107 controls the charging power according to the on / off instruction from the charging control unit 106,
When on is instructed, the charging operation is started to generate charging power. In addition, the power is not supplied to the DC connector 103, or the charge control unit 106 turns off the power.
Is instructed, the charger 107 is stopped and does not generate charging power. The resistor R11 is the secondary battery 101.
Or a sense resistor for measuring the charging current to 102. In addition, the current measuring circuit 108 uses the sense resistor R1.
1 measures the voltage across both ends of the secondary battery 101 or 102.
To measure the charging current value to the charging control unit 106.

R12 is the secondary battery 101 or 10
2 is a sense resistor for measuring the discharge current from 2.
The current measuring circuit 109 measures the voltage drop of the resistor R12, and 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). The diodes D11, D12 and D13 are connected to the DC connector 103.
In order to prevent the power from flowing out from the secondary battery 101 or 102 to the outside when the AC adapter is in a non-operating state because the AC adapter is connected but the AC power is not supplied. It is a reverse-flow blocking protection diode. Further, the diodes D21 and D22 supply electric power from the secondary battery 101 or 102 to the DC / DC converter 104 and electric power from the outside via the DC connector 103 when the electric power is not supplied from the outside. When the voltage is
This is a protection diode for preventing application to 01 and 102. The transistors FET1 and FET2 are
A switch circuit for selecting a secondary battery to be charged, and the charging current supplied from the charger 107 is supplied to the secondary battery 1
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 configuration, D
When power is supplied from the outside by connecting an AC adapter or the like to the C connector 103, the diode D
The external power is supplied to the DC / DC converter 10 via 11
4 to the DC / DC converter 10
4 creates the voltage required by the device. At this time, the external power is not blocked by the diodes D21 and D22 and applied to the secondary batteries 101 and 102. 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, because the voltage comparison circuit 105 detects that the power is supplied from the outside. 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 the voltage comparison circuit 105. Charger 107
When the battery is stopped, the circuit inside the charger is cut off and power is not supplied to the secondary battery 101 or 102. Then, when the charging control unit 106 is notified by the voltage comparison circuit 105 that the power supply from the outside has been interrupted,
The ON / OFF of the transistors FET3 and FET4 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 responds to the voltage required by the device. To create. At this time, the power is not blocked by the diodes D1, D21 or D22 and does not flow out. Charger 1 with power supplied from the outside
The electric power generated by the operation of 07 is the transistor FET1.
Alternatively, the secondary battery 101 or the secondary battery 102 is charged via the 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, thereby performing charging. At this time, the charging control unit 106 causes the transistor FE to
Since T2 is turned off, 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 and the diode D21 is in the reverse bias state, the charging current to the secondary battery 101 leaks to the DC / DC converter 104 side. And 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, since the transistor FET1 is turned off, the charger 1
All the current generated by 07 is used to charge the secondary battery 102. Since the voltage input from the DC 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 leaks to the DC / DC converter 104 side. Or leak to the secondary battery 101 side. As described above, conventionally, when a plurality of secondary batteries (battery packs) are charged by a single charger, they are charged separately in order.

As a conventional technique for parallel charging batteries, there is JP-A-6-303729. The technique disclosed in Japanese Patent Application Laid-Open No. 6-303729 is disclosed in claim 1 as described in the claims of the publication.
`` When a plurality of lithium ion batteries are connected and one lithium ion 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, A charging device, characterized in that all of the plurality of lithium ion batteries are charged at the same time. "," Means for controlling supply of charging current to the plurality of lithium ion batteries, "and And means for detecting the current value of the charging current,
2. The charging device according to claim 1, wherein when the charging current becomes less than or equal to a predetermined value, the supply of the charging current from the one lithium ion battery to the next lithium ion battery is switched. According to claim 3, "when the charging currents to the plurality of lithium ion batteries are all equal to or less than the predetermined value, the charging currents are supplied in parallel to all of the plurality of lithium ion batteries. 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. The charging device according to claim 3, characterized in that. A specific configuration for implementing the above technique is described in the description of the embodiment of page 3, left column, line 11 to page 4, right column, line 5 and FIG. 1 used for the description in the publication.
FIG. 1 of JP-A-6-303729 is shown in FIG.

As described in the left column, lines 21 to 28, page 3, of this publication, the output terminal C of the main charger 100 is used.
The terminals 2 of the charging device 200 connected to C are p
Through the emitters and collectors of the np type transistors 31, 32, and 33, lithium ion batteries BA1, BA2, and B
A3 is connected to one of the contacts 41, 42, 43, and the other contacts 51, 52, 53 of the batteries BA1, BA2, BA3 are connected to each other, and the middle point of the connection is grounded through the resistor 6. It is connected to the terminal 7 of the charging device 200 which is connected to the terminal GND. Also, the same page, same column, No. 3
As described in lines 6 to 39, the connection midpoint of the other contacts 51, 52, 53 described above is connected to the detection terminal I of the control microcomputer 9, whereby the resistance 6 of the resistor 6 generated by the charging current is connected. The voltage drop is measured by the control microcomputer 9.

The charging of the plurality of lithium ion batteries BA1, BA2, BA3 by the charging device 200 is performed as follows. First, as described on page 3, right column, lines 3 to 34 of the publication, the control microcomputer 9 turns on the transistor 31 to start the rapid charging of the battery BA1 to reduce the voltage drop of the resistor 6. The measured charging current is 350m
When the voltage becomes lower than A, the transistor 31 is turned off to stop charging the battery BA1. Then transistor 32
To turn on the battery BA2 to start charging the battery BA2.
Similarly to the case of charging to 1, the voltage drop of the resistor 6 is measured, and when the charging current becomes 350 mA or less, the transistor 32 is turned off and the charging of the battery BA2 is stopped. Like the batteries BA1 and BA2, the charging current is 350 mA.
Charge the battery BA3 until it becomes the following. In this way, the batteries are switched and charged until the charging currents to the batteries BA1, BA2, BA3 reach a predetermined value. As described above, when the charging of the batteries BA1, BA2, BA3 is completed, the transistors 31, 32, 33 are turned on as described in the right column, lines 34 to 43 of page 3 of the publication ( In the publication, it is described that the output ports CH1, CH2, CH3 are set to high level), and the batteries BA1, BA2, BA3 are all charged. That is, the batteries BA1, BA2, BA3 are charged in parallel. And the timer means is measured,
For example, when a predetermined time such as 2 hours has passed, all the circuits are turned off and the charging of all the batteries BA1, BA2, BA3 is completed.

By such charging, each battery BA1, B1
Approximately one hour each for the amount of charge of A2 and BA3 to reach 70%, and then each battery BA1, BA2, BA3
The charging time for all the three batteries is completed in about 5 hours at the time of simultaneous charging for about 100% in the charging amount of about 100%.

[0014]

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. In addition, since a plurality of secondary batteries are sequentially charged, the charging time required to charge all the secondary batteries is double the number of secondary batteries, and the charging time increases.

For example, one lithium ion (Li
+) When charging the secondary battery with a current of 1.0C, about 2.
It takes 0 to 2.5 hours, and when charging two secondary batteries, it takes twice as long, that is, about 4.0 to 5.0 hours. Further, in Japanese Patent 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 batteries reach a predetermined value, all the batteries are charged. On the other hand, charging is performed 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-described charging, a transistor for selecting the battery to be charged and controlling the current path from the main charger to the battery to be charged when individually charging, etc. Switch circuit is required. Furthermore, when parallel charging for multiple batteries, the battery is removed from the charging device, and another battery with a low charge amount is installed,
Since the charging is completed after a lapse of a predetermined time from the start of parallel charging, the charging of all the batteries is completed before the newly installed battery is fully 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 a hardware that reduce the charging time when charging a plurality of secondary batteries using a single charger. A charging device that charges multiple secondary batteries with a simple and simple circuit, a charging device that ensures full charging of multiple secondary batteries, and efficient charging of multiple secondary batteries The purpose is to provide a charging device to perform. 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.

[0017]

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

In FIG. 1, reference numeral 1 is a charging device.

Reference numerals 2a and 2b denote backflow prevention means, which are provided corresponding to each of the plurality of batteries 101 and 102 to be charged and are connected in parallel. 3 is a charging current supply means, which supplies a charging current to the plurality of batteries 101, 102 via the plurality of backflow prevention means 2a, 2b. 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. Further, each of the batteries 101 and 102 is a lithium ion battery.

Further, each of the backflow prevention means 2a and 2b is a diode.

Reference numeral 10 denotes an information processing device, which incorporates the above-mentioned charging device 1 and uses as a power source the 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.

In FIG. 2, reference numeral 1 is a charging device.

Reference numeral 101 denotes a so-called secondary battery, which is a battery having a built-in rechargeable device. Further, 102A and 102N are rechargeable batteries (secondary batteries) having backflow prevention means,
It is an additional battery that can be installed according to the needs of the user. The batteries 102A and 102N having the backflow prevention means are connected in parallel, and are connected in parallel to one terminal of the device. Two
Reference numeral a is a backflow prevention means, which is provided corresponding to the battery 101 to be charged.

Numeral 3 is a charging current supply means, which is connected to the battery 101, the battery 102A, and the battery 102A via the backflow prevention means 2a.
The charging current is supplied to 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 detects the charging current value to the battery 101 and each charging current value supplied to the batteries 102A and 102N.

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

In FIG. 3, reference numeral 1 is a charging device.

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. 5a, 5
Reference numeral b is a switching means, which includes a plurality of batteries 101, 10
2 are provided corresponding to each of the two, and are connected in parallel.

Reference numeral 6 is a comparison means, and the plurality of batteries 10 are provided.
The battery voltage between 1 and 102 is compared.

Reference numeral 7 is a control means for turning off the switching means corresponding to the battery having a low battery voltage based on the comparison result by the comparison means 6.

[0031]

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. By providing the backflow prevention means 2a and 2b for each battery as described above, the batteries are separated from each other, and even if the battery voltage is unbalanced due to the difference in the battery residual amount, the battery with the large residual amount remains. It is possible to charge a plurality of batteries in parallel because current does not flow to the battery having a small amount.

The charging current supply means 3 stops the supply of the charging current when each charging current value becomes equal to or less than a predetermined value. With the configuration of the present invention as described above, even if the charging current value for determining the completion of battery charging may differ due to the difference in manufacturers of batteries, the charging current value for determining completion of charging can be applied to individual batteries. If set, charging completion can be detected reliably 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, each lithium
Detecting that the charging current value for the ion battery has dropped below a predetermined value, the charging is completed.

Further, a backflow prevention means 2 for charging current to the battery 2
Since the diodes are used as a and 2b, a complicated circuit and a special control for blocking the reverse flow of the charging current are not required. In the second aspect of the invention, each of the plurality of additional batteries 102A and 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.

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 detection 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 determines that each charging current value detected by the charging current detection means 4 is a predetermined value. Detects the following and stops supplying charging current.

As described above, 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 102A and 102N are individually detected.
Since only the charging current for one terminal to which the backflow preventing means of each N 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, the switching means 5 for each of the plurality of batteries 101, 102
When the information processing apparatus is operated by using the discharge currents of the batteries 101 and 102 charged by the charge supply unit 3a, the comparing unit 6 connects the a and 5b in parallel.
01 and the battery voltage of the battery 102 are compared, for example, the battery 1
When the battery voltage of 01 is less than the battery voltage of the battery 102 by a predetermined value or less, 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. There is. Thus, 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.

[0037]

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, 102
Is a rechargeable battery composed of a plurality of battery cells connected in series, and is a lithium-ion secondary battery. 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 correspond to the plurality of secondary batteries in FIG. The DC connector 103 is an AC (not shown).
This is a connector for receiving power supply from the outside when the device is operated by an external power source such as a commercial power source by an adapter or the like, or when the secondary batteries 101 and 102 are charged by the external power source such as an AC adapter.

The DC / DC converter 104 is an external power source or a secondary battery 1 supplied via the DC connector 103.
The electric power is supplied from 01 and 102, 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 of the DC connector 103 is equal to the reference voltage e1.
When it is higher, it outputs a high level and the charging control unit 1 described later
1 is notified 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, the charge controller 1 outputs a low level.
1 is notified that power is not supplied from the DC connector 103. The diodes D1, D2 and D3 are
AC adapter is connected to C connector 103
The secondary battery 101 or 10 when the AC adapter is in a non-operating state due to the fact that the C power is not supplied.
It is a backflow blocking protection diode for preventing power from flowing out from the outside. Further, the diodes D4 and D5 are connected to D when the power is not supplied from the outside.
The C / DC converter 104 includes a secondary battery 101 or 10
The power from the DC connector 103
This is a protection diode for preventing the voltage from being applied to the secondary batteries 101 and 102 when power is supplied from the outside via the outside. This diode D2, D3
Corresponds to the backflow prevention means 2a, 2b in FIG. Resistance R
Reference numerals 1 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 is notified of the measured value. 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 the resistance whose current is to be measured,
These are the resistors 1 and 2 in FIG.

As shown in FIG. 5, the voltage divided by the resistors Ra and Rb 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 the operational amplifier CMP2. Is connected so as to be input to the positive electrode side terminal. The output of the operational amplifier CMP1 is connected to be input to the negative terminal of the operational amplifier CMP1 via the resistor Rf, and the output of the operational amplifier CMP2 is input to the negative terminal of the operational amplifier CMP2 via the resistor Rg. Are connected so that each constitutes a differential amplifier. The output from the operational amplifier CMP1 is connected to be input to the positive terminal of the operational amplifier CMP3 via the resistor Rh, and the output of the operational amplifier CMP2 is input to the negative terminal of the operational amplifier CMP3 via the resistor Ri. Are connected to each other.

The output of the operational amplifier CMP3 is also a resistor R.
The differential amplifier is connected so as to be input to the negative terminal of the operational amplifier CMP3 via j. Since the voltage value V output from the operational amplifier CMP3 becomes 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 × amplification by these circuits. Value).

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, 1
02 is a control unit for controlling the charging of the secondary battery 101 and 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 and 14 (on). , Instruct to stop (off).

The resistors R1 and R2 and the current measuring circuit 1 described above.
The charging control unit 11 which calculates the charging current from the outputs of the current measuring circuits 13 and 14 corresponds to the charging current detecting means 4 of FIG. The charger 12 receives the secondary battery 10 when power is externally supplied via the DC connector 103.
It is a constant current power supply for generating the electric power required to charge 1,102. The charger 12 controls the charging power according to the on / off instruction from the charging control unit 11,
When on is instructed, the charging operation is started to generate 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 in FIG. 1, and creates and stops charging power in accordance with a charging control instruction from the charging control unit 11 that is the charging current detection unit 4. FIG. 6 shows the configuration of the charger 12.

In FIG. 6, the main transistor TR1
Is a P-type MOSFET that performs a switching operation under the control of the control unit 1A.

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 is
The output of the main transistor TR1 is smoothed.

The flywheel diode D causes the energy accumulated in the choke coil L while the main transistor TR1 is on to flow a clockwise current to the flyback circuit L-C-D while the main transistor TR1 is off. The power is supplied to the secondary battery. The resistors RA and RB divide the voltage of the resistor RE on the current inflow side, and the resistors RC and RD divide the voltage of the resistor RE on the current outflow side.

The control unit 1A receives power from the DC connector 103 and 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 unit 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 a flywheel diode D connected in the reverse direction, and is connected to a smoothing capacitor C and one terminals of resistors RA and RC and a resistor RE via a choke coil L. It 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 has an input terminal I1 and an input terminal I
The input voltage input to 2 is compared, and the resistance RE is calculated from the potential difference.
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 resistance RC input to the input terminal I3
The charge voltage is detected by the divided voltage of RD and RD. When the charge voltage is lower than a specified value, a control voltage for turning on the main transistor TR1 is output to the collector of the main transistor TR1. A control voltage for turning off the transistor TR1 is output. By the control by the control unit 1A, the current flowing while the main transistor TR1 is on is accumulated in the choke coil L, and the clockwise current flows through the flyback circuit of LCD while the main transistor TR1 is off, 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 batteries 101 and 102 having the configuration of FIG.
The charging operation for charging will be described.

The voltage comparison section 105 includes a DC connector 103.
The reference voltage e1 is compared with the voltage supplied from the outside through the output, and the result is output to the charge control unit 11.

When the charging control unit 11 detects from the output from the voltage comparison unit 105 that electric 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, and the secondary batteries 101, 1 are connected through the diodes D2, D3.
The charging current created in 02 is supplied.

The current measuring circuits 13 and 14 are used for the secondary batteries 10 respectively.
The charging current to 1, 102 is measured, and the measured value is output to the charging control unit 11. The charging control unit 11 measures the measured current values 13, 1
When the measured value from 4 becomes 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.

Further, the voltage and charging current of the secondary battery during charging by the charger 12 will be described with reference to FIG. 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. 7, 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 when there is one secondary battery will be described.

The voltage of the secondary battery at the start of charging is 2.5 V
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 continues, when the battery voltage reaches 4.2V, the charging current gradually decreases while the battery voltage remains 4.2V, and after about 18 minutes, the charging current value becomes 0.5.
C (battery having a capacity of 1280 mAH is charged at 650 mA). This area is called a constant voltage charging area.

When the battery is further charged, the battery voltage becomes 4.
The charging current value continues to drop at 2V and continues for about 1 hour 18
The charging current drops to 100 mA in a minute. lithium·
The ion secondary battery is charged at a constant voltage and a constant current, and when the charging current value is 100 mA or less is in the charging completed state, the charging is completed at this point.

Therefore, the total time required for charging one lithium ion secondary battery is 24 minutes in the constant current charging area and 18 minutes and 1 hour 18 minutes in the constant voltage charging area. The total time 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 the empty state.

The charger 107 charges with a charging current of 1300 mA regardless of the number of secondary batteries to be charged. Since the battery voltages when both the secondary batteries 101 and 102 are empty are balanced, the charging current value to each secondary battery is 1
It becomes half of 300mA, 0.5C (capacity 1280mA
The H battery is charged at 650 mA) to start charging.

When charging is started, 1 hour 8 after the start of charging
The battery is charged with a current of 650 mA, 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 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, the lithium-ion secondary battery is in the charging completed state when the charging current value is 100 mA or less, and thus the charging is completed in this state. Therefore, the total time required for charging with two secondary batteries is a total time of 1 hour and 8 minutes in the constant current charging area and 1 hour and 18 minutes in the constant voltage charging area. It will be 26 minutes.

In the charging control described above, the charging current value is increased to shorten the charging time, for example, 1.
When the battery is charged with a current of 3 C (battery having a capacity of 1280 mAH is charged with 1700 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. The charging time of 2 hours is shortened to about 1 hour and 50 minutes, which is almost unchanged. As described above, according to the present invention, the two lithium ion secondary battery packs 101 and 102 are connected in parallel via the diodes D1 and D2, and the parallel charging is performed at the same time. The time can be reduced to 26 minutes.

The present invention is not limited to the case where there are two battery packs as in the first embodiment, but the present invention can be applied to two or more battery packs. As in the first embodiment, diodes as many as the battery packs to be charged may be connected in parallel, and parallel charging may be performed at the same time. 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, while the battery pack is charged at 1300 mA as described in 2 above.
When charging one battery pack, the total charging time is 2 hours 26
Only 24 minutes of the minute. Furthermore, 650m for 1 hour and 18 minutes of the total charging time of 2 hours and 26 minutes
It means that the battery is charged with a current of A 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. The same components as those in the first embodiment are designated by the same reference numerals as in FIG.

In FIG. 8, the secondary batteries 111, 112,
Reference numeral 113 is a rechargeable battery 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 device is operated by an external power source such as a commercial power source by an AC adapter (not shown) or the like.
Alternatively, it is a connector for receiving a power supply from the outside when the secondary batteries 101, 102 incorporated in the apparatus are charged by an external power source such as an AC adapter.

The DC / DC converter 104 is an external power source or secondary battery 1 supplied via the DC connector 103.
The power is supplied from 01 or 102, and voltage conversion is performed to create a voltage required by the device. The voltage comparator 105 detects that electric 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 the voltage of the DC connector 103. When the voltage is higher than the reference voltage e1, a high level is output to notify the charging control unit 11 to be 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 12 that no power is being supplied from the DC connector 103. The diodes D1 and D7 are the secondary batteries 111, 112, and 11 when the AC adapter is in a non-operating state because the AC adapter is connected to the DC connector 103 but the AC power is not supplied.
3 is a reverse current blocking protection diode for preventing the power from 3 from flowing out. Also, the diode D6
Is DC / D when power is not supplied from the outside.
While the power from the secondary battery 111 is supplied to the C converter 104, and when the power is supplied from the outside via the DC connector 103, the voltage thereof is stored in the internal secondary battery 11
It is a protection diode for preventing the voltage from being applied to the device 1. Further, a diode D8 is connected to the charging terminals of the secondary batteries 112 and 113 which are secondary batteries for expansion. This diode D8 is a DC adapter
If the DC connector 103 is connected to the connector 103 but the AC power is not supplied, and the DC connector 103 is not supplied with power, the additional secondary batteries 112 and 113 are added.
This is a back-flow blocking protection diode for preventing power from flowing out from the outside. Similarly, a diode D9 is connected to the discharge terminal side of each secondary battery. This diode D9 is D when power is not supplied from the outside.
Protection for supplying electric power from the secondary batteries 112 and 113 to the C-DC converter 104 and preventing the electric power from being applied to the secondary batteries 112 and 113 when the electric power is supplied from the outside. It is a diode. Resistance R
Reference numeral 3 is a sense resistor for measuring a charging current to the built-in secondary battery 111 and a discharging current from the secondary battery 111. The resistor R4 is a sense resistor for measuring the charging current to the additional secondary batteries 112 and 113. The resistor R5 is a sense resistor for measuring the discharge current from the additional secondary batteries 112 and 113. 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. Notify 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 the voltage across the resistor R5 to measure the secondary battery 112,113. The discharge current value of 113 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 is a control unit for controlling charging of the secondary batteries 101 and 102, and starts (on) and stops (of) charging of the secondary batteries 101 and 102 by a charger 107, which will be described later.
Indicate f). Further, the charging control unit 11 notified of the charging current value or the discharging current value determines the secondary battery 1 from the current value.
The remaining amounts of 01 and 102 are obtained, and the remaining amount is controlled to be displayed on a display unit (not shown). The charger 12 is a constant current power supply for generating the electric power required to charge the secondary batteries 111, 112, 113 when the electric power is supplied from the outside via the DC connector 103. 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. 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. This charger 12
The operation of is similar to that of FIG.

The secondary batteries 111, 1 having such a configuration
The charging operation to 12, 113 will be described with reference to FIG.

The voltage comparison section 105 includes a DC connector 103.
The reference voltage e1 is compared with the voltage supplied from the outside through the output, and the result is output to the charge control unit 11. When the charging control unit 11 detects from the output from the voltage comparison unit 105 that electric power is being supplied from the outside, it outputs a charging start instruction to the charger 12.

When the charger 12 is instructed to start charging, the D
A charging current is created by external power supplied via the C connector 103, the created charging current is supplied to the built-in secondary battery 111 via the diode D7, and additional secondary batteries 112 and 113 are created via the diode D8. Supply the charging current to. The current measuring circuit 15 measures the charging current to the secondary battery 111, and the current measuring circuit 16 measures the charging current to the secondary batteries 112 and 113.
Charging current to the charging controller 1
Output to 1.

When the measured value from the measured current values 15 and 16 becomes less than or equal to a predetermined specified value, the charge control unit 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. In this configuration, the charging control unit 11 charges the secondary batteries 111, 112, 113 by the control similar to that described above. However, since the current measuring circuit 16 measures the charging current to the two secondary batteries 112 and 113, the charging control unit 11 determines the charging current value of the charging current value determined to be the completion of charging the built-in secondary battery 111. Two
Charging control is performed with a specified value that is equal to or less than twice (for example, 200 mA or less when charging is completed at a charging current value of 100 mA or less as described above). In addition, the secondary batteries 111, 1
When the device is operated using 12, 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 control unit 11 receives the measured discharge current values and calculates the remaining amount of the secondary battery 111 and the combined remaining amount of the secondary batteries 112 and 113, and displays the calculated remaining amount on the display unit (not shown). Control to display.

In this way, the additional secondary batteries 112, 113
By providing the backflow prevention protection diode D8 on the charging terminal side and the protection diode D9 for preventing charging on the discharging terminal side, when the additional batteries 112 and 113 are directly parallel to the charging terminal of the device 10, The connection configuration is the same as that shown in the 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, a third embodiment will be described.

FIG. 9 is a diagram showing a third embodiment.

In FIG. 9, the secondary batteries 211 and 212
Is a rechargeable battery composed of a plurality of battery cells connected in series, and is a lithium-ion secondary battery.

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 211 and 212 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 the power supply from the external power supply or the secondary batteries 211 and 212 supplied via the DC connector 103, and performs voltage conversion to create the voltage required by the device. .

The voltage comparator 105 detects that power is being supplied from the outside via the DC connector 103, and the voltage of the DC connector 103, the reference voltage e1 for voltage comparison, and the voltage comparator IC1 are used. Compare and DC
When the voltage of the connector 103 is higher than the reference voltage e1, it outputs a high level. Further, when the voltage of the DC connector 103 is lower than the reference voltage e1, it outputs a low level. The NOT circuit NOT is for inverting the output of the voltage comparator IC1. The diodes D1, Da, and Db have an AC adapter connected to the DC connector 103, but the AC power is not supplied to the AC adapter because of the reason such as AC power supply.
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.

The transistors FET5 and FET6 are respectively
When connected to the discharge terminals of the secondary batteries 211 and 212 and not supplied with electric power from the outside, the DC-DC converter 104 is supplied with electric power from the secondary batteries 211 and 212 and also via the DC connector 103. This is a protective switch circuit for preventing the power from being applied to the secondary batteries 211 and 212 when the power is supplied. The voltage comparator IC2 includes a secondary battery 211 and a secondary battery 21.
2 for comparing the voltages of the secondary battery 211 and e2.
Is a reference voltage for defining a comparison reference when comparing the voltage of 2 with the voltage of the secondary battery 212. This voltage comparator I
C2 constantly compares the voltages of the secondary battery 211 and the secondary battery 212, and outputs a low level when the voltage of the secondary battery 211 is lower than the voltage of the secondary battery 212 by the reference voltage e2 or more,
Otherwise it outputs high level. Similarly, the voltage comparator IC3 also compares the voltages of the secondary battery 212 and the secondary battery 211, and is low 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. Is output, and a high level is output otherwise.

The NAND circuit NAND1 has a voltage comparator I
When both C2 and NOT circuit NOT output a high level, a low level is output and the transistor FET
5 is turned on, and when either the voltage comparator IC2 or the NOT circuit NOT outputs a low level, the transistor F
Turn off ET5. Further, the NAND circuit NAND2
When both the NOT circuit NOT and the voltage comparator IC3 output a high level, the transistor FET6 is turned on by outputting a low level, and the NOT circuit NOT and the voltage comparator I are output.
When any of C3 outputs a low level, the transistor FET6 is turned off.

The NOT circuit NOT outputs a high level when the voltage comparator IC1 of the voltage comparison section 105 outputs a low level, which is not supplied with power from the outside via the DC connector 103. It's time. 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 externally supplied via the DC connector 103, the NAND circuit NAND
1 and NAND2 are transistor FET5 and FE, respectively
T6 is turned off to prevent external power from being applied to the secondary batteries 211 and 212. Further, when the voltage of the secondary battery 211 is lower than the voltage of the secondary battery 212 by the reference voltage e2 or more, the NAND circuit NAND1 operates as the transistor FE.
The discharge current from the secondary battery 212 is prevented from flowing into the secondary battery 211 by turning off T5, and the transistor 5 is turned on at other times 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 receive the voltage from the secondary battery 211. The discharge current is prevented from flowing in, and at other times, the transistor 6 is turned on to discharge the secondary battery 212.

That is, when the apparatus is operated by discharging the secondary batteries 211 and 212 without supplying power from the outside,
The transistors FET5 and FET6 are 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. .

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.

[0084]

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. Further, when using the battery built in the device and the battery for the expansion, each of the expansion batteries is equipped with the above-mentioned backflow prevention means so that the discharge current from the plurality of the expansion batteries is inputted to one input terminal of the device. Since the backflow prevention means of the battery for use is connected in parallel, the charging current for charging the battery through the terminal can be measured by 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. Then, 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. Even if the values differ, if the charging current value for determining the completion of charging is set for each battery, the completion of charging can be reliably detected without causing overcharging. Furthermore, when operating the information processing device using the parallel output of the charged battery, by disconnecting the low battery voltage from the parallel connection with the transistor, the power loss due to the discharge current is reduced and the operating time is extended. The information processing device can be used efficiently.

[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]

1 charger 101,102 batteries 102A, 102N additional battery with built-in backflow prevention means 2a, 2b Backflow prevention means 3 Charging current supply means 4 Charge current detection means 5a, 5b switching means 6 comparison means 7 Control means 10 Information processing equipment

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Nobuo Tanaka             1015 Kamiodanaka, Nakahara-ku, Kawasaki City, Kanagawa Prefecture             Within Fujitsu Limited (72) Inventor Tsutomu Suzui             1015 Kamiodanaka, Nakahara-ku, Kawasaki City, Kanagawa Prefecture             Within Fujitsu Limited (72) Inventor Hideyoshi Ozawa             1015 Kamiodanaka, Nakahara-ku, Kawasaki City, Kanagawa Prefecture             Within Fujitsu Limited F term (reference) 5G003 AA01 BA04 CA11 CC02 DA02                       DA04 DA13 EA06                 5H030 AS14 BB01 BB27 FF43

Claims (4)

[Claims] 1. A plurality of switching means provided corresponding to a plurality of batteries and connected in parallel, a comparison means for comparing battery voltages between the plurality of batteries, and a comparison result obtained by the comparison means. A power supply circuit comprising: a control unit that disconnects a switching unit that corresponds to a battery having a voltage lower than a predetermined value by a predetermined value among the plurality of batteries. 2. The power supply circuit according to claim 1, wherein each of the batteries is a lithium ion battery. 3. The power supply circuit according to claim 1, wherein each of the reverse current blocking means is a diode. 4. An information processing apparatus comprising the power supply circuit according to any one of claims 1 to 3 as a power source, and a discharge current output in parallel from each of the plurality of batteries is used as a power source.