JPH09308131A - Electronic device and control thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To make it possible to use energy stored in a battery effectively by eliminating a memory effect of the battery. SOLUTION: Battery packs 1, 2 are connected to a circuit section through switching means 3, 4 and 5, 6 respectively. Usually, one of the switching means is turned on and power is supplied by that switching means. When a residual capacity of the battery which is supplying power is detected and the detected value is a specified level or below, the battery is changed over to the other battery and the battery which has been used is forcibly discharged. The discharging current is used for charging the other battery by a DC-DC converter 40a.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic device having a battery and an AC adapter as a power source.

[0002]

2. Description of the Related Art In a conventional electronic device having a power source such as a battery, a voltage is detected to detect a remaining capacity of the battery, and when the remaining capacity is lower than a predetermined potential, the other battery is switched to instruct charging. It was a control method of charging unconditionally when a display to indicate or an AC adapter was connected. When estimating the remaining capacity of a nickel-cadmium battery, it is difficult to accurately detect it due to its unique memory effect, and it is common to instruct the user to completely discharge the battery. It was

[0003]

If the user neglects the above complete discharge, there is a problem that the end state of the battery is displayed early although the remaining capacity is considerable. In addition, since the battery that has not been completely discharged is charged from the middle, the battery is overcharged and the battery life is shortened.

The present invention has been made to solve the above problems, and an object of the present invention is to provide an electronic device having a power source such as a battery and having a power control means such as a battery most suitable for a user. And

[0005]

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems and includes a plurality of main batteries as main power supplies and an AC.
In an electronic device that has an adapter, a power control unit that controls the main battery and the AC adapter, and a voltage detection unit that measures each voltage of the main battery, the power control unit is an electronic device that supplies power while switching the main battery. , A switching means installed corresponding to a plurality of batteries to turn on / off charging of the main battery from the AC adapter and a discharge circuit for discharging the main battery, and the main battery being supplied has a predetermined potential. The electronic device is characterized by having a control means for switching the supply source to the other main battery and discharging the electric charge on the side having a predetermined potential or less when the potential is reached.

Further, the present invention comprises a plurality of main batteries as main power sources, an AC adapter, a power control means for controlling the main battery and the AC adapter, and a voltage detecting means for measuring the voltage of the main battery. Having an electronic device that supplies electric power while switching the main battery, when the voltage of the main battery being supplied becomes equal to or lower than a predetermined potential, while switching the main battery of the supply source to the other,
A method of controlling an electronic device, comprising: fully discharging a battery having a predetermined potential or less, and starting charging by the AC adapter after the discharging is completed.

[0007]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail based on an embodiment. FIG. 1 is a schematic diagram of a handheld or laptop type small computer device as an electronic device of the present invention, which includes a battery pack 1 as a battery power source, a battery pack 2, a backup sub-battery 18, and a power control means. Battery control unit 7, sub CP
U7a, A / D converter 8 of voltage detection means, main C
Main circuit unit 9 including PU 9a and peripheral circuits, display unit 1
0, IO unit 16, RAM / RTC (random access memory / real-time clock) 17, voltage regulator 24, DC-DC converter 30, and the like. The battery control unit 7 has a sub CPU 7a and monitors the power supply even when the main circuit unit 9 is stopped.

A field effect transistor (hereinafter referred to as FET) 3, FET 4, FET 5, and FET 6 are FET switches that are a kind of switching element for turning on / off the power supply of the battery pack, and are connected in parallel with the FET. The diodes 3a, 4a, 5a, 6a that are present are F
It is a parasitic diode existing inside the ET. But FE
Diode 4 in parallel with T4 and FET6
As a and 6a, a diode having a low forward voltage and a large current capacity can be used as required. The FET can be replaced with another bipolar transistor, a relay, or the like.

When the start switch 25, which is a power switch of the apparatus, is turned on, the battery control section 7 detects this, and the battery pack 1 or the battery pack 2 passes through a predetermined FET, a voltage regulator 24, and a DC-DC converter 30. Then, electric power is supplied to each circuit and a predetermined operation can be executed.

As a power source, in addition to the batteries 1 and 2, A
A C adapter 21 is provided and connected to the battery output terminal 37 via the input terminal 21a and the diode 23 so that power can be supplied to the circuit section. AC adapter 2
When 1 is connected, a detection signal is output from the adapter detection circuit 22 and the gate circuit 26 is connected to the control terminals of the FETs 4 and 6,
An OFF signal is supplied via 27, and the power supply from the battery is cut off. This detection signal is also transmitted to the battery control unit, and the detection operation of the A / D converter corresponds to this. Reference numerals 28 and 29 denote transistors that turn on / off the current of the AC adapter 21, and are used when controlling charging of the battery packs 1 and 2.

A discharge circuit 40 has a DC-DC converter 40a and switches 41 and 42 built therein. This DC
The DC converter 40a and the switches 41 and 42 are controlled by the battery control unit 7, and are used for discharging the electric charge of the battery pack 1 or the battery pack 2 and charging the other battery pack. The output potential of the discharge circuit is set so that an output slightly higher than the potential when the battery packs 1 and 2 are fully charged is obtained.

Battery output terminal 37 and sub-battery 18
Are connected via diodes 34 and 35, and from this connection point 36, the battery control unit 7, A / D converter 8 and R
Power is supplied to each circuit such as the AM / RTC 17. During the operation of the device, the electric potential is not high on the output terminal side 37, so that no power is supplied from the sub-battery. When the normal operation of the device is stopped, electric power is supplied to each circuit such as the battery control unit 7, the A / D converter 8 and the RAM / RTC 17, and the voltage check and the start switch ON monitoring are being performed. The current consumption is much lower than during normal operation. The A / D converter 8 is connected to the output terminals of the batteries 1 and 2 and is configured to be able to individually measure the respective potentials. The A / D converter 8 is often configured as a one-chip CPU integrally with the sub CPU 7a.

When the battery pack 1 and the battery pack 2 are removed and the supply of the main power is stopped, the operation of the sub CPU 7a is also stopped, and the sub battery 18 can hold the data in the RAM / RTC 17. At this time, generally, the sub CPU 7a is in the suspend mode. Reference numeral 20 is a voltage comparison circuit for monitoring the power supply of the device, separately from the A / D converter 8, and the potentials at the voltage dividing points of the resistors 31, 32 are compared with each other with reference to the potential generated by the Zener diode 33. Output of comparator 2
0a.

Reference numeral 11 denotes a buzzer that sounds various alarms, and 1
Reference numerals 2 and 13 denote LEDs provided at portions corresponding to the battery packs 1 and 2, and reference numerals 14 and 15 denote lid detection switches that engage with the lids of the battery storage portions and detect the open / closed state of the lids.

Field effect transistors (hereinafter referred to as FET) 3, FET 4, FET 5, and FET 6 are FET switches which are a kind of switching elements for turning on / off the power supply of the battery pack, and are connected in parallel with the FETs. The diodes 3a, 4a, 5a, 6a that are present are F
It is a parasitic diode existing inside the ET. But FE
Diode 4 in parallel with T4 and FET6
As a and 6a, a diode having a low forward voltage and a large current capacity can be used as required.

The FETs 3 and 4 are connected in series and are connected to the output terminal of the battery pack 1, and the FETs 5 and 6 are similarly connected to the output terminal of the battery pack 2.

These four FETs have a gate terminal which is a control terminal and can be turned on / off independently by the battery control unit 7. The FET can be replaced with another bipolar transistor, a relay, or the like.

Since a FET normally contains a parasitic diode, a current flows from the anode of the parasitic diode to the cathode through the parasitic diode even when the FET is turned off. Therefore, in order to prevent this, when using an FET as a switching element, it is often the case that two parasitic diodes of the FET are connected in series so that their anodes or cathodes face each other to realize a complete switching function. However, in this case, two FETs connected in series are controlled to be turned on or off at the same time.
However, in the embodiment of the present invention, since each FET can be turned on and off independently, if the FET 3 or 5 is turned on and the FET 4 or 6 is turned off, the FET 3 or 5 passes through the diode 4a or 6a. The power is supplied, and if both are off, the power supply from the battery is completely stopped, and it is possible to flexibly cope with various power supply modes.

When the AC adapter 21 is connected, a detection signal is output from the adapter detection circuit 22, an OFF signal is supplied to the control terminals of the FETs 4 and 6 via the gate circuits 26 and 27, and the power supply from the battery is cut off. To be done. This detection signal is also transmitted to the battery control unit, and the detection operation of the A / D converter corresponds to this.

In this embodiment, when the A / C adapter is not connected, ON / OFF of the FET is controlled by the following combinations. To supply power from the battery pack 1 to the circuit, turn on FET3 and FET4 and turn FET5 and FET6 on.
Turn off. (This is called a single coupling mode.) When supplying power from the battery pack 2 to the circuit, the FET is used.
3. Turn off FET4 and turn on FET5 and FET6.
In order to supply electric power to the circuit from the battery pack 1 and the battery pack 2 by the diode OR, FET3, F
ET5 is turned on and FET4 and FET6 are turned off. (This is referred to as a parallel coupling mode.) These three kinds of states can be realized by controlling four FETs independently, and the actual operation will be described in detail below.

When the start switch 25 is pressed to start the device, the battery control unit 7 first turns on the FETs 3 and 5 to supply electric power from a plurality of main batteries, and the FETs 4 and 4,
Turn off 6 to OR the battery. This is for the following reasons.

That is, if the batteries 1 and 2 are removed, the sub CPU 9a is in the suspended state. For this reason, when the start switch releases this to activate the battery control unit, it is not known which battery can supply the electric power, and therefore, the electric power is supplied from both the batteries by the OR coupling to start the operation.

With this configuration, it is not necessary to constantly supply electric power to the battery control unit to maintain the operating state, it is possible to stand by in the suspended state, and the electric power of the backup battery is used immediately after the power is turned on. Immediately after the power supply is started immediately, the A / D converter and the like are operated and the check program is executed. As a result, the backup battery can have a capacity as small as possible without driving the A / D converter, and a battery with a small current consumption can be selected.

Next, the battery to be used is determined by the following procedure. When both battery packs are attached and both battery pack lids are closed, the battery control unit 7 turns on FET3 and FET4 to supply electric power from the battery pack 1 to the circuit, and turns on FET5 and FE.
Turn off T6. Also, when the battery pack lid is closed and only one of the battery packs is installed, the two FETs for supplying power to the circuit from the installed battery pack are turned on and the other battery pack is turned on. The FET is turned off to power the circuit from the FET.

Similarly, when the battery pack lid is closed and two battery packs are mounted together, but when one of the battery packs is not fully charged, power is supplied to the circuit from the charged battery pack. Supply. For example, when supplying power from the battery pack 1 to the circuit, FET
3. Turn on FET4 and turn off FET5 and FET6.
On the contrary, when power is supplied from the battery pack 2 to the circuit, FET3 and FET4 are turned off and FET5 and FET6 are turned on. Whether the battery is mounted or not is sufficiently charged is determined by measuring the terminal voltage of the battery pack by the A / D converter 8 and reading the A / D converted value by the battery control unit 7. The battery control unit 7 compares both potentials, selects the one with the higher potential, and supplies it to the main circuit unit. At this time, if the potential of the battery not selected is already lower than the predetermined potential,
This is transmitted to the main circuit section, and the user is notified by means such as display or warning. Since it is clear that the battery not selected cannot be used unless it is charged, the DC-DC converter 40a of the discharge circuit 40 is turned on, and the input side switch 41 is connected to the battery pack used. The discharge side switch 42 is connected to the battery on the selection side to start discharging, and this discharge current becomes a charging current to the other battery pack.

If the non-selected batteries have a relatively high potential and still have sufficient capacity, then no discharge will occur.

In this way, the battery to be used is determined, and this power is supplied to the main circuit section 9, the display section 10 and the IO section 16.
Etc. and the device operates.

Next, the battery switching operation will be described. When two battery packs are installed,
It is assumed that the FET 3 and FET 4 are turned on, the FET 5 and FET 6 are turned off, the battery pack 1 is selected, and power is supplied from the battery pack 1 to the circuit. During operation of the device, the battery control unit 7 regularly checks the use state of the battery pack such as electric potential or attachment / detachment. The main circuit unit 9 receives the operating state of the battery pack and the voltage of the battery pack from the battery control unit 7, and displays the state on the display unit 10. There are two types of information displayed on the display unit 10. The first information is which one of the two battery packs supplies the voltage to the circuit, and the second information is how much the voltage of each battery pack is. In this method, as shown in FIG. 2, the physical position of each battery pack and the position of the display of the operating state of the battery pack correspond to each other, and the user can easily determine which display represents the state of which battery pack. I understand.

As an example of the display, the display showing the operation is shown in FIG.
Is displayed on the LCD as the operation display 50, 51 of
The voltage of the battery is displayed by bar graphs 52 and 53 in five stages. Further, triangular marks 54 and 55 indicate whether or not discharging is in progress. When the first selected battery pack 1 supplies power to the device, the voltage of the battery pack gradually decreases. Here, the operating state of the battery is displayed on the display unit 10 of the LCD, but it is also possible to display the battery state using a device such as an LED.

When the voltage of the battery pack 2 drops and it is compared with a predetermined reference voltage Vref2 in the same manner, and it becomes dangerous to continue the operation of the apparatus any more, the main circuit unit 9 causes the battery control unit 7 to operate. Based on the information, the fact that the battery pack 1 and the battery pack 2 have insufficient voltage is displayed on the display unit 10. If the voltage is not sufficient, for example, no square element of the bar graph of FIG. 2 is displayed. In order to more strongly warn of insufficient voltage, control such as blinking the right half or the left half of the display unit 10 corresponding to the position of the battery pack may be performed.
The reference voltages Vref1 and Vref2 may be the same when the battery 1 and the battery 2 have similar capacities and types,
If they are of different types, different reference voltages may be used accordingly. The normal operation of the battery control described above will be described with a flowchart. In FIG. 3, when the battery pack is first attached and the operation is started, the battery control unit 7 is initialized and the FET is first set in step S10.
3, the FET 5 is turned on, the FET 4 is turned off, and the FET 6 is turned off to execute a parallel coupling mode in which two battery packs are diode-OR coupled. In the initial state, it is unknown which battery is attached or which voltage is present in which battery, so that diode OR coupling is performed and power is supplied from both battery packs. Subsequently, the battery control unit 7 sets the voltage of the battery pack 1 to A / D in step S12.
Measure using converter 8. If battery pack 1
If the voltage of the
3, FET4 is turned on and FET5, FET6 are turned off to execute a single coupling mode for supplying power from the battery pack 1 to the circuit.

In step S12, the battery pack 1
If the voltage is insufficient, then the voltage of the battery pack 2 is measured in step S14. If the voltage of the battery pack 2 is sufficient, the FET3 and FET4 are turned off and the FET5 and FET6 are turned on as in step S18, and the battery pack 2 is turned on.
Power the circuit from. If the voltage of both battery packs is not sufficient, the same parallel coupling mode as set in step S10 is maintained to prevent the device from operating. However, since the charged battery pack is eventually inserted, the process returns to step S12 and the voltage of the battery pack is constantly measured even when the voltage of both battery packs is not sufficient. When the voltage is supplied to the circuit from one of the battery packs in steps S20 and S18, the device becomes operable. In step S22, the voltage of the currently selected battery is measured.

Next, when the voltage of the battery pack drops in step S24, the voltages of other battery packs are checked next. If the voltage of the other battery pack is sufficient, the battery pack is switched in step 26. The original battery pack switched in step S26 is started to be discharged by the discharging circuit 40. Since the discharge circuit 40 inputs the discharge current to the other as described above, the drivable time of the other battery pack is extended, and the electric power can be used more efficiently than being simply consumed by the resistor or the like and discharged. After that, the process continuously returns to step S22 to measure the voltage of the selected battery pack. Step S
If the voltage of the other battery pack is not sufficient at 24, the device cannot continue to operate. If the device is operating in step S28, the user is notified that the voltage of the battery is not sufficient, and then the operation of the device is stopped. Step S
If the device is stopped at 28, the process skips step S30 of stopping the operation of the device and proceeds to step S32. In step S32, since the voltage of both battery packs is not sufficient, FET3 and FET5 are turned on, FET4 and FET6 are turned off, and the output of the battery pack is diode-OR coupled,
The power supply mode 2 is executed. And again step S1
Return to 2 and check the voltage of the battery pack.

By supplying power from a plurality of batteries at the same time at the start of the normal operation of the apparatus such as turning on the power, the start reliability is ensured. That is, at the time of start, the detection function or the calculation function of the CPU is stopped, and first, a predetermined initialization process is always required, and at this time, power is supplied to all or a plurality of batteries by the OR circuit. Is extremely effective.

On the other hand, the flow chart shown in FIG. 4 shows a discharge check method. This routine is executed within the step S22 of the main routine of FIG. As well as checking the battery currently being used, the potential of the battery being discharged is also
The following steps are checked. In step 50, it is checked whether or not discharging is in progress. If not, the process returns. In step 51, if discharging is in progress, the level is checked, and if the potential becomes equal to or lower than a predetermined potential, it is determined that the discharging has ended. When the discharge circuit is stopped and the discharge is completed in step 52, the corresponding marks of the triangular marks 54 and 55 on the display section are blinked and displayed in step 53 to notify the completion of the discharge. Upon receipt of this, the user must either attach the AC adapter or take it out and replace it with another battery. Which side is the battery discharged in step 54 is stored in the memory. The battery control unit 7 constantly monitors the state of the battery to see if this battery has been taken out.
Optimal operation is performed depending on whether the AC adapter is attached.

That is, when the discharging is completed, the discharged side is stored in a predetermined storage section of the RAM, so that when the AC adapter is subsequently mounted, the transistors 28, 2
The charging switch on the discharged side of 9 is turned on to start charging. The charge potential is also monitored by the A / D converter 8, and when it is fully charged, the battery pack to be charged is switched, and similarly, charging is executed until it is fully charged.

When it is determined that the battery on the discharged side has been removed, the above-mentioned information on the stored discharge is erased.

As described above, since the battery is completely discharged when the charge level is equal to or lower than the predetermined potential, there is no so-called memory effect, that is, there is no battery capacity even though the remaining capacity is sufficient. It is possible to prevent erroneous judgment. Moreover, it is extremely convenient because an electronic device equipped with a battery automatically executes the battery even if the user does not completely discharge the battery.

If the remaining voltages of both batteries are not sufficient, the user must promptly stop the operation or attach an AC adapter. Otherwise, the voltage supplied to the circuit will drop and the device will malfunction or RAM / RTC1
7 data may be destroyed.

As a countermeasure, the following control is executed. First, the two battery packs are discharged and the user is informed of the occurrence of the state on the display unit 10. Then, the user stops the operation of the apparatus even after a certain time (for example, 1 minute) has elapsed. If not, the main circuit unit 9 executes a predetermined data saving process or the like to stop the operation of the circuit and enters the suspend mode. When the operation of the circuit is stopped, the current consumption of the device is much smaller than that during operation, and the device continues the suspended state of the main CPU for a predetermined period. The discharge is continued and the potential gradually decreases thereafter. In this state, the minimum operation of the battery control unit 7, for example, the opening of the lid and the check of the attachment / detachment of the battery are executed. When the detection voltage is determined by the Zener diode 33 and the resistors 31 and 32, the output of the comparator 20 is inverted from the H level to the L level, so that the sub CPU is also in the suspending state and the FETs 3, 4, 5, And 6
Is turned off, the power supply from the batteries 1 and 2 is stopped, and the power supply is switched to the backup battery 18. In this state, the backup battery power is consumed to back up the RAM / RTC 17.

When the user recognizes that both batteries have a low remaining voltage and operates the power switch, the main circuit section 9 performs a predetermined data saving process or the like based on whether or not the resume function is set. Stop working stop. At this time, if the remaining voltage of the battery pack that has been supplying power to the circuit during the operation up to then is sufficient, power is continuously supplied from the battery pack to the battery control unit even when the operation is stopped. In this case, the reference voltage when power supply is stopped may be lower than the reference voltage during normal operation. During normal operation, a relatively high potential is required for supplying a constant voltage to the main circuit unit 9 by a DC-DC converter or the like, but 3V is required for the operation of the battery control unit and the backup of the RAM / RTC 17. This is because a low potential may be supplied.

The above process will be described below with reference to the battery supply control. When the battery 1 used at the beginning is not at a level higher than the predetermined reference voltage Vref3, it is determined that the voltages of both batteries are not sufficient, and F
ET3 and FET3, 5 are turned on, FET4, 6 are turned off, and the output of the two battery packs is FET4 and FET.
The parasitic diode of 6 is used to output by the diode OR. When the outputs of the battery pack 1 and the battery pack 2 are OR-coupled by the diodes in parallel with the FET 4 and the FET 6, these diodes supply power to the circuit from the higher voltage of the two battery packs.

Since the reference voltage Vref3 is used to check whether the other battery is charged and recovered, it is set higher than the level for checking the remaining voltage.

For example, if the voltage of the battery pack 1 drops while the device is operating with the battery pack 1, the battery control unit 7 cuts off the power supply from the battery pack 1 to the circuit and supplies the power from the battery pack 2 to the circuit. The main circuit unit 9 receives this state change from the battery control unit 7, and the information that the battery pack 2 is supplying power because the voltage of the battery pack 1 has dropped to the display unit 10 and that the discharge of the battery pack 1 has started. Is displayed.
Further, when the discharge is started and becomes a complete discharge, this is also displayed. The user sees these pieces of information and waits until the battery pack 1 is completely discharged before replacing the battery pack.

When the user intends to replace the battery pack when the voltage of the battery pack supplying power to the device is sufficient and the voltage of the other battery pack is low (in the most probable situation) Yes, if the battery with the lower voltage is replaced, the battery pack can be replaced while the device is operating. By repeating this operation, the battery pack can be replaced without interrupting the operation of the device.

Further, in the above description, the battery control unit 7 is the A / D
The converter 8 is used to measure the voltage of the battery pack 1 or the battery pack 2, and the measurement result is used as the main circuit section 9
Referred to and received and displayed on the display unit 10. In this embodiment, a nickel cadmium secondary battery is used as the battery pack. For the secondary battery, it is possible to measure the open circuit voltage of the battery pack and calculate the remaining amount of the battery by the voltage, or obtain the open circuit voltage from the discharge current and the internal resistance. However, when measuring the terminal voltage of the operating battery pack, it is necessary to limit the measurement to an operation mode in which the discharge current is a constant value.

The voltage of the battery pack 1 measured by the battery control unit 7 is sent to the main circuit unit 9, and the accurate voltage of the battery pack is estimated from the discharge current and the internal resistance of the battery pack based on this, and this value is used as the basis. The remaining amount can be displayed on. In addition, at the timing of measuring the battery voltage, AC
When the AC adapter detection circuit 22 detects that the adapter is attached, the transistors 28 and 29 of the corresponding battery are turned off, charging is stopped, and the open circuit voltage is measured.

In the above embodiments, the case where the number of battery packs is two has been described, but the case where the number of battery packs is three or more can be realized with the same configuration.

[0048]

As described above, according to the present invention, an electronic device having a battery has a control means for discharging the used battery when the battery is switched, so that an erroneous judgment due to a memory effect can be prevented and the battery can be prevented. Can be effectively used, and it is possible to prevent overcharging due to erroneous determination.

Further, since the discharge is not simply consumed by the resistor, unnecessary heat generation and useless power consumption can be suppressed, and the charging energy of the battery can be effectively used to the end, so that the battery can be used for a long time. This is a very useful usage, such as a significant extension.

[Brief description of drawings]

FIG. 1 is a schematic diagram of an electronic device having a battery control circuit of one embodiment of the present invention.

FIG. 2 is a diagram showing a display unit of the apparatus of the embodiment.

FIG. 3 is a flowchart showing control during normal operation of an embodiment of the electronic device of the present invention.

FIG. 4 is a flowchart of a discharge check of the electronic device of the present invention.

[Explanation of symbols]

 1, 2: Battery pack 28, 29: Transistor 7: Battery control unit 8: A / D converter 9: Main circuit unit 10: Display unit 16: IO unit 17: RAM / RTC 18: Backup battery 40: Discharge DC -DC converter

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁶ Identification number Office reference number FI technical display location H02J 7/34 G06F 1/00 333C

Claims (6)

[Claims] 1. A plurality of main batteries as a main power source;
An electronic device that includes a C adapter, a power control unit that controls a main battery and an AC adapter, and a voltage detection unit that measures an individual voltage of the main battery, and supplies power while switching the main battery. The control means turns on the charging of the main battery from the AC adapter.
When a potential of the main battery being supplied reaches a predetermined potential, the other main battery has a switch unit that is turned off and is installed corresponding to a plurality of batteries, and a discharge circuit that discharges the main battery. An electronic device comprising: a control unit that switches a supply source and discharges a charge on a side of a predetermined potential or lower. 2. The electronic device according to claim 1, wherein
The electronic device is characterized in that the discharge circuit has a DC-DC converter, and has control means for making the discharge current the charging current of the other main battery. 3. The electronic device according to claim 1, wherein
An electronic device, wherein the main battery is a nickel-cadmium battery. 4. The electronic device according to claim 1, wherein
An electronic device, characterized in that after the main battery is discharged, the AC adapter is connected to a corresponding main battery for charging. 5. A plurality of main batteries as main power sources, and A
An electronic device having a C adapter, power control means for controlling the main battery and AC adapter, and voltage detection means for measuring the voltage of the main battery, and supplying power while switching the main battery. When the voltage of the main battery inside becomes equal to or lower than the predetermined potential, the main battery of the supply source is switched to the other, and the battery that becomes equal to or lower than the predetermined potential is sufficiently discharged, and after the discharge is completed,
A method of controlling an electronic device, comprising: starting charging by the AC adapter. 6. The method of controlling an electronic device according to claim 5, wherein the main battery is a nickel-cadmium battery.