JP2002320333A - Electronic apparatus having charging function - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an electronic apparatus having a charging function wherein generation of automatic discharge is comparatively little after charge of a secondary battery is finished, and an external power source having large capacity is not used when an electronic apparatus is operated in the state of connection with an external power source. SOLUTION: A load constituting an electronic apparatus is divided into a first load 7 and a second load (e.g. power amplifier 13). The first load 7 is connected with an external power source 2 side of a switching means 4 for charge, and the second load 13 is connected with a secondary battery 1 side of the switching means 4.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a portable telephone, an information terminal, and other electronic equipment having a charging function provided with a rechargeable secondary battery.

[0002]

2. Description of the Related Art Generally, electronic devices such as mobile phones and information terminals use a secondary battery as a power source and have a charging function.

FIG. 4 is a block diagram of a conventional mobile phone having a conventional charging function. In FIG. 4, when the secondary battery 1 is charged, an external power supply obtained by a known power supply adapter, charging stand, in-vehicle connector, or the like (not shown) is connected to the input terminal 2 of the external power supply.

When an external power supply is connected to the input terminal 2, a charging current flows from the external power supply to the secondary battery 1 via the diode 3, the switch means 4, and the current detection means 5, and the charging of the secondary battery 1 is started. You. That is, the switch means 4 is controlled by the control means 8 and is initially in the ON state. Therefore, when an external power supply is connected, a charging current flows from the external power supply to the secondary battery 1 via the switch means 4 and the current detection means 5, and charging of the secondary battery 1 is started. During charging of the secondary battery 1, the current detecting means 5 detects the charging current,
The output causes the control means 8 to operate so that the switch means 4 is kept ON.

When the charging of the secondary battery 1 is completed, it is detected by the current detecting means 4 and the switch means 4 is turned off.
Thereafter, only the charged voltage of the charged secondary battery 1 is used as a power source for the load 7 and the control circuit 8 constituting the electronic device via the regulator 6.

As described above, even in a conventional electronic device having a charging function, the secondary battery 1 is charged by connecting an external power supply to the input terminal 2, and the load 7, which constitutes the electronic device using the charging voltage, is used. The control means 8 and the like can be operated.

[0007]

However, in the above-described conventional electronic device with a charging function, the switching device 4 is connected to the secondary battery 1 side, that is, the connection point between the current detecting device 5 and the secondary battery 1 via the regulator 6. The power is supplied to the load 7 and the control means 8. Therefore, even if the secondary battery 1 is charged and the switch means 4 is completely turned off, the secondary battery 1 is directly passed through the regulator 6. The secondary battery 1 is connected to the load 7 and the control means 8 and starts discharging immediately after charging.

[0008] Therefore, these electronic devices have a problem that, even after charging is completed, discharging starts immediately thereafter, and after a certain period of time, only a certain voltage is applied, and charging is required again.

This is the same even when the external power supply is kept connected to the input terminal 2. Therefore, in this case, charging and discharging are repeated at regular intervals as described above. Even if the device has been charged for a long time on a charging stand, the device may have been discharged considerably depending on the timing when removing the device from the charging stand. Is not always the case).

For this reason, as shown in FIG. 5, a power supply for the load 7 and the control means 8 has been invented from the external power supply 2 side of the switch means 4.

According to the present invention, when the charging is completed and the switch means 4 is turned off, the secondary battery 1 is no longer separated from the load 7 and the control means 8 and the secondary battery 1 is disconnected when the external power supply 2 is connected. The secondary battery 1 is rarely inadvertently discharged, and has an advantage that the secondary battery 1 is almost fully charged even when the secondary battery 1 is disconnected from the external power source 2 after charging is completed.

However, in the above invention, since all the loads 7 constituting the electronic equipment are connected to the external power supply 2 side of the switch means 4, for example, when the electronic equipment is a portable telephone, the transmission circuit and the reception circuit , A memory circuit, a display circuit, a power amplifier, a transmitter, a receiver, and many other circuits. Therefore, when the electronic device is operated while the external power supply 2 is connected, it is equivalent to the external power supply 2. It is necessary to receive a large amount of power supply, and the charger as the external power supply 2 also needs to have a large equivalent capacity. When heat generation and the like are taken into consideration, there is a problem that the size becomes considerably large.

The present invention solves the above-mentioned conventional problems. It is relatively unlikely that the battery is automatically discharged after charging is completed, and furthermore, the electronic device is connected to an external power supply. It is an object of the present invention to provide an excellent electronic device with a charging function that does not use a device having such a large capacity as an external power supply even when the device operates.

[0014]

According to the present invention, in order to achieve the above object, according to the first aspect of the present invention, loads constituting an electronic device are divided into first and second loads, and the first load is The second load is connected to the external power supply side of the charging switch means, and the second load is connected to the secondary battery side of the charging switch means.

According to the second aspect of the present invention, a detecting means for detecting a current flowing in the secondary battery during charging is provided, and when the completion of charging of the secondary battery is detected based on an output of the detecting means, The charging switch is turned off.

Further, according to the present invention, there is provided an external energization detecting means for detecting the energization of the external power supply, and when the energization detecting means detects that there is no energization by the external power supply, the switch means is forcibly activated. It is configured to be turned ON.

Therefore, according to the first aspect of the present invention, when the charging is completed and the switch is turned off, the secondary battery is hardly automatically discharged thereafter through the first load, the control means and the like. . Therefore, when charging is completed and the apparatus is connected to an external power supply as it is, it can be used at any time in a sufficiently charged state.

According to the first aspect of the present invention, the secondary battery is discharged through the second load. If the secondary battery is not operated, the discharge current is extremely small. It is slight and practically makes it possible to hardly discharge. Therefore, the discharge due to the second load can be almost ignored. Even if it cannot be neglected, as a whole, the discharge of the secondary battery can be extremely reduced as compared with the conventional case, and even when the battery is connected to an external power supply in a state where the charging is completed, almost at any time, It can be kept fully charged.

According to the first aspect of the present invention, even when the electronic device is operated with the external power supply connected and a relatively large current needs to flow to the second load, the current is supplied to the secondary battery. 1, it is sufficient to supply a smaller amount of current from the external power supply than before.
That's why a small capacity, small,
It has the effect that the weight can be reduced.

According to the second aspect of the present invention, it is possible to accurately detect the completion of charging by the output of the detecting means for detecting the current flowing to the secondary battery at the time of charging, correctly complete the charging, and stop the charging. it can.

Further, according to the third aspect of the present invention, when the external power supply detecting means detects that no power is supplied from the external power supply, the switch means is forcibly turned on. When disconnected, the switch means is always turned on, and the secondary battery is used as a power supply to accurately supply power to the load and control means constituting the electronic device.

[0022]

Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is a schematic electrical connection diagram showing a first embodiment of the present invention, and FIG. 2 is an explanatory diagram of the operation of each unit shown in the first embodiment.

In FIG. 1, the input terminal 2 of the external power supply is
It is configured to be connected to the secondary battery 1 via a diode 3 for backflow prevention, a switch means 4, and a current detection means 5. And the external power supply side of the switch means 4, that is,
A regulator 6 is connected to a connection point between the diode 3 and the switch means 4, and a voltage stabilized by the regulator 6 is supplied as power to a first load 7 and a control means 8 constituting an electronic device. Have been.

The second load 13 is directly connected to the secondary battery 1 and is configured to receive power directly from the secondary battery 1. When the external power supply 2 is connected and charging is in progress, the power supply from the secondary battery 1 is insufficient. In this case, it goes without saying that the external power supply 2 receives the shortage. is there.

As the second load 13, a power amplifier, such as a power amplifier, which consumes a relatively large amount of power when the second load 13 is activated is selected. Assuming that a mobile phone is used as the electronic device, the power consumption of the entire load is about 900 mA in the current general mobile phone in the operating state, whereas the power amplifier alone consumes about 600 mA. It is desirable to use a circuit including at least a power amplifier as the second load.

Next, the output of the current detection means 5 is supplied to the control means 8, and the output of the control means 8 is supplied to one input terminal of the NOR circuit 12. Further, a diode 9 is connected to the input terminal 2 of the external power supply.
, An external power supply detection means 10 is connected thereto, and its output is supplied to the other input terminal of the NOR circuit 12 via an inverter 11.

The switch means 4 is composed of a MOS-FET, a diode, and the like, and is configured to be switched to three stages of ON, half ON, and OFF by the output signal of the NOR circuit 12.

Further, the current detecting means 5 includes the switch means 4
It comprises a relatively small-valued resistor connected between the battery and the secondary battery 1 and means for monitoring the voltage across the resistor.

In the above embodiment, when an external power supply is connected to the input terminal 2 of the external power supply, a charging current flows from the input terminal 2 to the secondary battery 1 via the diode 3, the switch means 4, and the current detection means 5. . At this time, the switch means 4 is controlled as follows under the control of the control means 8.

It is assumed that a lithium ion battery is used as the secondary battery 1 and is charged. In this case, an external power supply applied to the input terminal 2 is usually 5.8 V or more. However, for the secondary battery 1, it is necessary to prevent the battery voltage from exceeding 4.2V.
It is necessary that the charging current does not exceed 700 mA. Therefore, the switch means 4 is also controlled to be in a half-ON state so as to satisfy such a condition.

FIG. 2 shows this state. At first, the switch means 4 is in the ON state, and a large charging current flows through the secondary battery 1. When the charging progresses and the battery is charged to a certain voltage, the switch means 4 is in a half ON state, and further charging is performed in this state. As charging proceeds, the voltage across the secondary battery 1 gradually increases, and the charging current flowing through the secondary battery gradually decreases.

The charging current flowing through the secondary battery 1 is detected by the charging current detecting means 5 and applied to the control means 8. Here, 0.15 is used as the resistance constituting the charging current detecting means 5.
If a Ω resistor is used, the voltage across it is 150m
If it is V, it means that a charging current of 1 A flows.

Therefore, by detecting the voltage across the resistor, the charging current flowing through the secondary battery 1 can be easily and accurately known. The control means 8, in this way monitors the charging current flowing in the secondary battery 1, when the charging current is a certain value I _0, for example, was lowered to 50 mA, OFF switch means 4 detects it To control the state.

When the charging is completed in this way and the switch means 4 is turned off, the charging current no longer flows,
The external power supply and the secondary battery 1 are completely separated. Accordingly, in this state, the electric charge charged in the secondary battery 1 is transferred to the first load 7 and the control unit 8 via the switch unit 4 and the regulator 6.
On the other hand, if an external power supply is still connected to the input terminal 2 in this state, the first load 7 and the control means 8 are supplied with necessary power from the external power supply as it is. Will be.

In the above embodiment, the second load 13
Are connected directly to the secondary battery 1, and immediately after the completion of charging, a necessary current flows from the secondary battery 1 to the second load 13, and the secondary battery 1 is discharged. If the load 13 does not enter the operating state, a very small discharge current is selected, so that substantially no discharge can occur in the non-operating state.

For this reason, the discharge caused by the second load 13 in the non-operation state can be almost ignored.
The discharge from the battery is extremely small, and the secondary battery 1 can be kept almost fully charged at any time, even when the battery is connected to an external power supply in a state where the charging is completed.

When operating an electronic device such as making a call or receiving a call while an external power supply is connected, a relatively large current needs to flow through the second load 13. However, in this case, the current is
Therefore, it is sufficient to supply a smaller amount of current from the external power supply than in the past, and accordingly, a charger or the like as the external power supply can be reduced in capacity, size, and weight.

It should be noted that, as described above, the switch means 4
Although it is composed of an OS-FET, a diode and the like, it may not be possible to obtain a completely OFF state, but even in such a case, when an external power supply is connected to the input terminal 2, the input of the regulator 6 The side potential cannot be lower than the potential of the secondary battery 1. Therefore, even in this state, the electric charge charged in the secondary battery 1 passes through the switching means 4, the regulator 6, the first load 7, the control means 8, the necessary current is supplied only from the external power supply. Therefore, the secondary battery can be fully charged at any timing until the electronic device is removed from the charging stand or the like and disconnected from the external power supply.

When the electronic device is detached from the charging stand or the like and disconnected from the external power supply, this is detected by the external power supply detecting means 11, and its output is output via the inverter 12 to the NOR circuit.
Since the voltage is applied to the other input terminal of the NOR circuit 12, the switch means 4 is forcibly turned ON regardless of the control signal applied from the control means 8 to one input terminal of the NOR circuit 12, and the secondary The electric charge charged in the battery 1 is applied as power to the load 7 and the control means 8 via the switch means 4 and the regulator 6.

In the above embodiment, a lithium ion battery is used as the secondary battery.
The same can be applied to other secondary batteries. Also,
Although the current detecting means 5 is provided on the secondary battery 1 side of the switch means 4, it may be provided on the external power supply side. In short,
It is sufficient to provide it at a position where the charging current to the secondary battery 1 flows.

In the above-described embodiment, a circuit including a power amplifier is selected as the second load. However, the power amplifier, the transmission circuit, the reception circuit, and other circuits are independently selected, or a combination thereof is used. It is needless to say that the user may select one of them.

Further, in the above embodiment, when the external power supply is not applied, the external power supply detecting means 11 is separately provided to detect the external power supply. It is also possible to provide means for detecting the state.

That is, as shown in FIG. 3, a diode 14 is connected to the external power supply 2 and its output side is connected to the control means 8, and the control means 8 detects connection or disconnection of the external power supply. Then, based on the result, the switch means 4 may be turned on under the control of the control means 8 when an external power supply is not connected.

In addition, even if a special route directly connected to the external power supply is not provided, the same operation as described above can be performed only by closely monitoring the change in the power supply voltage applied to the control means 8. Is also possible.

That is, even if there is no special route as described above, the power supply applied to the control means 8 is controlled by the input terminal 2 from the diode 3 and the regulator 6 when the external power supply is connected. When a sufficient power supply voltage is applied via the power supply and no external power supply is connected, the secondary battery 1
, Its voltage is slightly lower than when an external power supply is connected,
By detecting this difference, it is possible to easily detect whether or not the external power supply is connected.

Therefore, according to the detection result, when an external power supply is connected, the output of the current detecting means 5 causes the control means 8 to switch the switch means 4 from ON to half ON as described above. , OFF, and when the external power supply is no longer connected, the control means 8
May be configured so that the switch means 4 is automatically turned on.

Further, in the above embodiment, the current detecting means 5 is constituted by the resistance and the means for detecting the voltage between both ends of the resistor.
However, when an external power supply is not connected, both ends of the current detecting means 5 may be automatically short-circuited.

In this configuration, when the external power supply is not connected, the voltage of the secondary battery 1 is not dropped by the resistor constituting the current detecting means, and the switching means 4 and the regulator 6 Efficiently through the load 7,
It will be applied to the control means 8.

[0050]

As described above, according to the first aspect of the present invention, the secondary battery is connected to the external power supply via the charging switch means, and the first load constituting the electronic device is connected to the external power supply. Since the external power supply side of the charging switch means and the second load are connected to the secondary battery side of the switch means, if charging is completed and the switch means is turned off, thereafter, while the external power supply is connected, The secondary battery is rarely inadvertently discharged through the first load, the control means, and the like, and even when discharged through the second load, it is extremely small in the non-operating state. A fully charged state can be maintained forever.

When the electronic device is operated while the external power supply is connected, a large current flows as a whole, but the second load is supplied from the secondary battery, and the second load has a large current. The current supply from the external power supply is smaller than in the past, and there is no need to use a large capacity external power supply. This has the advantage that the weight can be reduced.

According to the second aspect of the present invention, there is provided a detecting means for detecting a current flowing through the secondary battery during charging, and a detection of completion of charging of the secondary battery based on an output of the detecting means. Since the control means for controlling the charging switch means is provided so as to turn off the charging switch means, the completion of charging can be accurately detected by the output of the detecting means for detecting the current flowing to the secondary battery during charging. , Charging can be stopped.

According to the third aspect of the present invention, the external power supply detecting means for detecting the power supply of the external power supply, and the switch means is forcibly activated when the detection means detects that there is no power supply by the external power supply. When the electronic device is disconnected from the external power supply, the switch is forcibly turned on when the external power supply detection unit detects that there is no power supply from the external power supply. The switch means is always turned on, and the load of the electronic device and the control means are always accurately energized by using the secondary battery as a power supply.

[Brief description of the drawings]

FIG. 1 is a schematic electrical connection diagram showing a first embodiment of an electronic device with a charging function according to the present invention;

FIG. 2 is a diagram for explaining the operation of each unit shown in FIG. 1;

FIG. 3 is a schematic electrical connection diagram showing a second embodiment of the electronic device with a charging function of the present invention;

FIG. 4 is a schematic electrical connection diagram of a conventional electronic device with a charging function;

FIG. 5 is a schematic electrical connection diagram of an electronic device with a charging function previously invented by the inventor.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Secondary battery 2 External power input terminal 3, 9, 14 Backflow prevention diode 4 Switching means 5 Current detection means 6 Regulator 7 First load 8 Control means 10 External conduction detection circuit 11 Inverter 12 NOR circuit 13 Power amplifier

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 5G003 AA01 BA01 CA04 CA14 DA07 DA13 GA01 5H030 AA06 BB01 DD06 FF43

Claims (4)

[Claims] 1. A secondary battery is configured to be connected to an external power supply via a charging switch means, a first load constituting an electronic device is connected to the external power supply side of the switch means, An electronic device with a charging function, wherein a second load, such as a power amplifier, consuming a large amount of power during operation is connected to the secondary battery side of the switch means. 2. A detecting means for detecting a current flowing through the secondary battery during charging, and a switch means for turning off the switch means when completion of charging of the secondary battery is detected based on an output of the detecting means. 2. An electronic device with a charging function according to claim 1, further comprising control means for controlling said switch means. 3. An external power supply detecting means for detecting power supply of an external power supply, and means for forcibly turning on the switch means when the power supply from the external power supply is detected by the detection means. The electronic device with a charging function according to claim 2. 4. The electronic device with a charging function according to claim 3, wherein said control means includes means for forcibly turning on said switch means.