JP5047506B2 - Electronic device and charging method thereof - Google Patents

Description

  The present invention relates to an electronic device and a charging method thereof.

For example, Patent Literature 1 below discloses a battery that can change a charging voltage according to temperature by the battery itself, can extend the life and prevent an internal short circuit, and an electronic device having the battery. This technology is a battery including a temperature sensor that measures the temperature of a secondary battery cell or a temperature in the vicinity of the secondary battery cell, a voltage control unit that controls a charging voltage when charging the secondary battery cell, and the like. The voltage control unit controls the charging voltage of the secondary battery cell according to the temperature detected by the temperature sensor, thereby preventing an internal short circuit.
More specifically, when the battery voltage of the secondary battery cell exceeds the target charging voltage, the voltage control unit gently changes the battery voltage by changing the on / off duty ratio of the semiconductor switching element for charging. The target charging voltage is converged to the target charging voltage, and the target charging voltage is set lower as the detected temperature of the temperature sensor is higher, thereby preventing an internal short circuit of the secondary battery cell.
JP-A-11-111350

However, in the above-described conventional technology, since the target charging voltage is varied according to the temperature detected by the temperature sensor, the battery cannot be effectively prevented from being deteriorated. That is, a state in which the charging voltage of the secondary battery cell becomes so high that it exceeds the target charging voltage is a state in which the secondary battery cell has already deteriorated easily, and this target charging voltage is detected by the temperature sensor. Even if it is lowered according to the above, deterioration in the battery cannot be effectively prevented.
Further, in an electronic device that houses such a secondary battery in a casing, even if the target charging voltage is varied according to the temperature of the secondary battery cell or the temperature in the vicinity of the secondary battery cell, the secondary battery cell When the battery voltage is higher than the charging voltage, it is difficult to effectively suppress the temperature rise inside the housing, and the temperature rise inside the housing may affect the electronic components inside the housing It cannot be suppressed.

  The present invention has been made in view of the above-described circumstances, and an object of the present invention is to provide an electronic device and a charging method thereof that can effectively suppress a temperature rise inside the housing.

In order to achieve the above object, the following means are adopted.
Electronic device according to the present invention comprises a housing, wherein the includes a secondary battery to be distribution to the housing, and a power supply means for supplying electric power input from the external power source to the secondary battery, said power supply means Comprises a voltage detection means for detecting a battery voltage of the secondary battery and a power supply suppression means capable of suppressing power supply to the secondary battery, and the battery voltage detected by the voltage detection means. In the electronic device configured to suppress the power supply to the secondary battery by the power supply suppression unit when the battery voltage becomes equal to or higher than the full charge determination voltage value, the temperature detection unit detects the temperature inside the housing. , the power supply means, said housing said battery voltage detected by said voltage detecting means the next full charge judging voltage higher than a predetermined voltage value is set lower than the value, is detected and at said temperature detecting means The internal temperature is the specified temperature When it is above, characterized in that throttling power supply to the secondary battery by the power supply suppressing means.

The temperature detecting unit detects an ambient temperature of the secondary battery inside the casing .

When the battery voltage detected by the voltage detection means is equal to or higher than the predetermined voltage value and the temperature inside the casing detected by the temperature detection means is equal to or higher than a predetermined temperature, the power supply means The power supply suppression means alternately performs power supply and supply stop to intermittently supply power to the secondary battery, thereby suppressing power supply to the secondary battery and performing the intermittent supply. When starting, the power supply is performed first .

The full charge determination voltage value is lowered when the temperature inside the casing detected by the temperature detection means becomes equal to or higher than the predetermined temperature .

When the battery voltage detected by the voltage detection unit is equal to or higher than the full charge determination voltage value, the power supply unit reduces the charging current to the secondary battery by the power supply suppression unit and the charging current. that but stops power supply to the secondary battery to become equal to or less than the predetermined current value, the predetermined current value, the temperature of the housing portion detected by said temperature detecting means is increased to become equal to or higher than a predetermined temperature Features.

The method for charging an electronic device according to the present invention supplies power from an external power source to secondary batteries arranged and housed inside the casing, and when the battery voltage of the secondary battery becomes equal to or higher than a full charge determination voltage value. in charging method of suppressing an electronic equipment power supply to the secondary battery, to detect the temperature inside the enclosure, adjacent the battery voltage is the full charge determination voltage higher than a predetermined voltage value is set lower than the value, and detection temperature of the housing unit to be the line when more than a predetermined temperature, characterized in that throttling power supply to the secondary battery.

  According to the present invention, power supply to the secondary battery in which the battery voltage of the secondary battery is equal to or higher than the full charge determination voltage value is suppressed, and the temperature inside the casing in which the secondary battery is stored is When the battery voltage is equal to or higher than the predetermined temperature, the power supply to the secondary battery is suppressed when the battery voltage is equal to or higher than the predetermined voltage value set to be smaller than the full charge determination voltage value. It can suppress and the effect accompanying the temperature rise inside this housing | casing can be reduced suitably.

  Hereinafter, an embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 is a block diagram showing a main configuration of a cellular phone as an electronic apparatus according to the present embodiment. In this figure, reference numeral 1 is a charging terminal (external power input unit), 2 is a resistor for detecting a charging current, 3 is a charging transistor, 4 is a system power supply IC (Integrated Circuit), 5 is a secondary battery, and 6 is a control. Reference numeral 7 denotes a temperature sensor (temperature detection means). The charging terminal 1 is a metal piece provided so as to be exposed at a part of the casing of the mobile phone, and charging current is supplied from an output terminal of an AC adapter connected to an external power source. One end of a resistor 2 is connected to such a charging terminal 1. The resistor 2 is provided between the charging terminal 1 and the charging transistor 3, and the other end is connected to the emitter terminal of the charging transistor 3.

  The charging transistor 3 is a PNP bipolar transistor as shown in the figure, and is provided between the resistor 2 and the secondary battery 5. The charging transistor 3 includes a secondary battery 5 whose collector terminal is a power source load for the secondary battery 5, a sound source IC (Integrated Circuit), an LED (Light Emitting Diode) controller, and a RF (Radio Frequency) power supply IC (Integrated Circuit). The base terminal is connected to the system power supply IC 4. In addition, the charging transistor 3 has an ON state in which the emitter terminal and the collector terminal are conductive according to the voltage (base voltage) of the base terminal set by the system power supply IC 4, and the emitter terminal and the collector terminal are non-conductive. The state transitions to an OFF state that is a conductive state. As described above, the secondary battery 5 is supplied with power from the external power supply by the power supply means configured to include the resistor 2, the charging transistor 3, and the system power supply IC4.

  The system power IC 4 controls power supply from the secondary battery 5 to a power load such as an LCD module or a camera module under the control of the control unit 6, and controls the charging transistor 3 to reduce the charging current 2. The supply to the secondary battery 5, that is, the charging of the secondary battery 5 is controlled. As shown in the figure, the positive terminal of the secondary battery 5 is connected to the system power supply IC 4, and the system power supply IC 4 detects the positive terminal voltage (battery voltage) and the charging current of the secondary battery 5 by this. It supplies to the control part 6 as charging information. The system power supply IC 4 also controls the supply of power from the secondary battery 5 to the LCD module and camera module. The secondary battery 5 is, for example, a lithium ion battery, and supplies power to the sound source IC, LED controller, RF power supply IC, and the like as a main power source of the mobile phone.

  The control unit 6 includes a memory, a CPU, and various interface circuits. The control unit 6 includes a predetermined charge control program stored in advance in the memory, temperature information input from the temperature sensor 7, and charge information input from the system power supply IC 4 ( The system power supply IC 4 is controlled by executing a predetermined charging process based on the battery voltage and the charging current. That is, the control unit 6 controls charging of the secondary battery 5 by indirectly controlling the charging transistor 3 via the system power supply IC 4.

  The temperature sensor 7 is provided at a position relatively distant from the high temperature portion in the casing of the mobile phone, detects the temperature inside the casing (internal casing temperature), and outputs the temperature information to the control unit 6 as the temperature information. To do.

  Here, in the case of the mobile phone, in addition to the secondary battery 5, an electronic board on which various electronic circuits such as the sound source IC, LED controller, RF power supply IC, receiving circuit and transmitting circuit are mounted, Although the LCD module, the camera module, and the like are housed, the temperature of the secondary battery 5 when the mobile phone is in use depends on the temperature of electronic components arranged around the secondary battery 5. That is, when the mobile phone is in use, electronic parts and the like become main heat sources, and the heat generated from these electronic parts and the like is absorbed by the secondary battery 5, thereby changing the temperature of the secondary battery 5. Is done. For this reason, the temperature sensor 7 in this mobile phone is located relatively far from the electronic component corresponding to the high temperature part when in use, and is around the secondary battery 5 (secondary battery 5 The temperature inside the housing can be suitably detected by the temperature sensor 7. The electronic component corresponding to the high temperature part is, for example, an RF receiver or a signal amplifier.

  Next, the charging operation of the mobile phone configured as described above will be described in detail with reference to the flowchart shown in FIG. 2 and the characteristic diagram shown in FIG. This flowchart shows the charging process of the control unit 6 when the secondary battery 5 is charged in a state where the mobile phone is being used.

  When the output terminal of the AC adapter is connected to the charging terminal 1, the control unit 6 detects the connection by monitoring the voltage of the charging terminal 1, for example, and starts the charging process. In this charging process, the control unit 6 first uses the full charge voltage Vm (see FIG. 3) that is the target battery voltage (full charge determination voltage value) at the end of charging and the charging current (predetermined current value) at the end of charging. A certain full charge current Im (see FIG. 3) is initially set as a control target value (step S1).

  FIG. 3 shows a state in which the full charge voltage Vm is set to about 4.3 and the full charge current Im is set to about 100 mA. When the control target value is initially set in this way, the charging transistor 3 is set to the ON state by the control unit 6 (step S2), and constant current control is performed by the AC adapter as shown in FIG. A constant charging current is sequentially supplied to the secondary battery 5 through the resistor 2 and the charging transistor 3. Then, the electric charges based on the charging current are sequentially stored (accumulated) in the secondary battery 5, whereby the battery voltage sequentially increases.

  The control unit 6 determines whether the battery voltage that sequentially increases in this way has reached the full charge voltage Vm and whether the charge current has decreased to the full charge current Im based on the charge information. (Step S3), if this determination is "Yes", the charging transistor 3 is set to the OFF state (step S4), the charging process is terminated, and if the determination is "No" Based on the temperature information, it is determined whether or not the temperature inside the casing has exceeded a predetermined temperature value of 45 ° C (step S5).

  Immediately after the start of charging, the determination in step S3 is “No”, so the determination process in step S5 is performed subsequent to step S3. However, if this determination is “No”, If the mobile phone has not been used for a long time and the temperature inside the housing has not risen to exceed 45 ° C., the process returns to step S2 to maintain the charging transistor 3 in the ON state. On the other hand, if the determination in step S5 is “Yes”, the controller 6 lowers the full charge voltage Vm set as the control target value in step S1 by 0.1 V (step S6), and also in step S1. The full charge current Im set as the control target value is increased by 50 mA (step S7).

  Then, the control unit 6 determines whether or not the battery voltage has exceeded the voltage threshold value (predetermined voltage value) of 3.9 V based on the charging information (step S8), and this determination is “No”. In this case, the process returns to step S2 to maintain the ON state of the charging transistor 3. If this determination is "Yes", the charging transistor 3 is turned OFF when 30 seconds have elapsed (step S9). The state is changed (step S10). FIG. 3 shows a state in which the battery voltage has risen to a value lower than about 4.3, which is the full charge voltage Vm, that is, about 4.15 V when 30 seconds have passed.

  When the charging transistor 3 is switched from the ON state to the OFF state, the supply of the charging current to the secondary battery 5 is stopped, and since the mobile phone is in use, the battery voltage is charged to the secondary battery 5. As the generated power is consumed by each load, it gradually decreases. When the battery voltage that decreases in this way exceeds 3.9 V (step S11), the control unit 6 returns the process to step S2 to switch the charging transistor 3 from the OFF state to the ON state, and the secondary of the charging current. While the supply to the battery 5 is resumed, at the stage where the battery voltage does not drop to 3.9 V, when the time of 30 seconds has elapsed since the charging transistor 3 was switched off in step S10 (step S12), the process Is returned to step S2 to switch the charging transistor 3 from the OFF state to the ON state.

  That is, the control unit 6 switches the charging transistor 3 when the battery voltage drops below 3.9 V after switching the charging transistor 3 to OFF or when 30 seconds have elapsed after switching the charging transistor 3 to OFF. 3 is switched from the OFF state to the ON state again. Then, the ON / OFF duty ratio of the charging transistor 3 is adjusted according to the temperature in the casing and the battery voltage by such loop processing of steps S2 to S12. As a result, as shown in FIG. 3, the battery voltage reaches the full charge voltage Vm with a gradual increase from a state (about 4.15 V) lower than the full charge voltage Vm (about 4.3 V).

  That is, when the battery voltage of the secondary battery 5 does not reach the fully charged voltage Vm when the battery voltage of the secondary battery 5 exceeds the voltage threshold value and the internal temperature exceeds a predetermined temperature. Even so, the supply of power to the secondary battery 5 is intermittently performed and charging of the secondary battery 5 is suppressed. Therefore, compared with the case where the temperature inside the casing does not exceed the predetermined temperature, the battery voltage gradually increases, and the electronic components (such as the charging transistor 3) of the charging circuit accompanying the charging of the secondary battery 5 Heat generation can be suppressed, and the temperature rise of the secondary battery 5 itself can be suppressed, and the temperature rise of the mobile phone (housing) housing the secondary battery 5 can be suppressed.

  In addition, when the battery voltage of the secondary battery 5 exceeds the voltage threshold and the internal temperature exceeds the predetermined temperature value, power supply (charging transistor 3 ON) and power supply stop (charging transistor 3 OFF) are alternated. When the power is intermittently supplied (charged) to the secondary battery 5 as shown in steps S9 and S10, the power supply is stopped (charge transistor 3 OFF) after the power supply is performed for 30 seconds. That is, when the intermittent supply of power is started, the power supply is performed first. As a result, even after the battery voltage of the secondary battery 5 exceeds the voltage threshold, the power supply is performed first and the secondary battery 5 is continuously charged. Therefore, the power is supplied after the power supply for 30 seconds. Even if the supply is stopped for 30 seconds, the battery voltage of the secondary battery 5 is suppressed from dropping below the voltage threshold. Therefore, the battery voltage of the secondary battery 5 continues to rise gently.

  In addition, when supplying power to the secondary battery 5 intermittently, the interval between power supply and power supply stop may be changed according to the load state of the mobile phone. For example, when the load on the mobile phone is large, such as when watching TV or playing music, the power supply interval may be increased to shorten the power supply stop interval.

  In this way, when the battery voltage reaches the full charge voltage Vm with a gradual increase, the charging current is reduced so that the battery voltage converges to the full charge voltage Vm. Since this charging current is lowered every time it is determined that the battery voltage of the secondary battery 5 has reached the fully charged voltage Vm, the charging current is shown in FIG. 3 when the battery voltage reaches the fully charged voltage Vm. Thus, the power supply to the secondary battery 5 is suppressed. When it is determined that the charging current has decreased to the full charge current Im or less, that is, when it is determined that the battery voltage is greater than the full charge voltage Vm and the charge current is less than the full charge current Im, the fully charged state And the determination in step S3 is “Yes”.

  In the above-described embodiment, since the battery voltage is larger than the threshold voltage and the temperature in the housing exceeds 45 ° C. until the charging current is reduced to the full charging current Im or lower, intermittent charging is performed. Has been done. When the determination in step S3 is “Yes”, the control unit 6 sets the charging transistor 3 to the OFF state (step S4) and ends the charging process.

According to the present embodiment, when the battery voltage is lower than the full charge voltage Vm and the temperature inside the housing exceeds 45 ° C., the battery voltage reaches the full charge voltage Vm with a gentle slope. Since the secondary battery 5 is charged as described above, the deterioration of the secondary battery 5 can be prevented more effectively than in the past.
Further, when the temperature inside the case exceeds 45 ° C., the full charge voltage Vm is sequentially decreased in increments of 0.1 V, so that the deterioration of the secondary battery 5 can be further effectively prevented. .

  In the above-described embodiment, the full charge voltage Vm is sequentially decreased and the full charge current Im is sequentially increased every time the temperature in the casing exceeds 45 ° C. However, only one of them is changed. You may make it do. Further, instead of sequentially changing each time the temperature in the casing exceeds 45 ° C., it may be changed only once.

The present invention is not limited to the above embodiment. The charge control shown in the above flowchart is merely an example, and other procedures may be used as long as the charge control is performed so that the battery voltage reaches a full charge voltage Vm with a gentle slope from a state where the battery voltage is lower than the full charge voltage Vm. The charging control based on this may be used.
Further, the present invention is not limited to the charging control of the mobile phone, but can be applied to the charging control of various other devices.

It is a block diagram which shows the principal part structure of the mobile telephone concerning one Embodiment of this invention. It is a flowchart which shows the charging operation of the mobile telephone concerning one Embodiment of this invention. It is a characteristic view which shows the charge characteristic of the mobile telephone concerning one Embodiment of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Charging terminal, 2 ... Resistor, 3 ... Charging transistor, 4 ... System power supply IC, 5 ... Secondary battery, 6 ... Control part, 7 ... Temperature sensor

Claims (6)

A housing,
A secondary battery that is distribution to the housing,
Power supply means for supplying power input from an external power source to the secondary battery,
The power supply means includes voltage detection means for detecting a battery voltage of the secondary battery and power supply suppression means capable of suppressing power supply to the secondary battery, and is detected by the voltage detection means. In the electronic device configured to suppress power supply to the secondary battery by the power supply suppression unit when the battery voltage is equal to or higher than a full charge determination voltage value,
Temperature detecting means for detecting the temperature inside the housing;
It said power supply means becomes the voltage is the battery voltage detected by the detection means and the full-charge judging voltage higher than a predetermined voltage value is set lower than the value, the housing interior and is detected by said temperature detecting means electronic device temperature is when it is higher than a predetermined temperature, characterized in that to suppress power supply to the secondary battery by the power supply suppressing means.   The electronic device according to claim 1, wherein the temperature detecting unit detects an ambient temperature of the secondary battery inside the casing.   When the battery voltage detected by the voltage detection means is equal to or higher than the predetermined voltage value and the temperature inside the casing detected by the temperature detection means is equal to or higher than a predetermined temperature, the power supply means The power supply suppression means alternately performs power supply and supply stop to intermittently supply power to the secondary battery, thereby suppressing power supply to the secondary battery and performing the intermittent supply. 3. The electronic apparatus according to claim 1, wherein when starting, the power is supplied first.   The full charge determination voltage value is lowered when a temperature inside the casing detected by the temperature detection unit becomes equal to or higher than the predetermined temperature. Electronics. When the battery voltage detected by the voltage detection unit is equal to or higher than the full charge determination voltage value, the power supply unit reduces the charging current to the secondary battery by the power supply suppression unit and the charging current. When the current falls below a predetermined current value, the power supply to the secondary battery is stopped,
5. The electronic device according to claim 1, wherein the predetermined current value is increased when a temperature inside the casing detected by the temperature detecting unit is equal to or higher than a predetermined temperature. 6. An electronic device that supplies power from an external power source to secondary batteries arranged and housed inside the housing, and suppresses power supply to the secondary battery when the battery voltage of the secondary battery exceeds a full charge determination voltage value. In the device charging method,
Detect the temperature inside the housing,
The power supply to the secondary battery when the temperature of the housing unit in which the battery voltage becomes higher than a predetermined voltage value is set lower than the full charge judgment voltage value, and is detected is higher than a predetermined temperature A method for charging an electronic device, comprising suppressing the electronic device.

Images