JP2019022286A - Electronic device - Google Patents

Abstract

To suppress reduction in battery capacity due to repetition of charging.SOLUTION: An electronic apparatus 100 includes a battery 101, a measuring unit 102, and a control unit 103. The battery 101 is a power source of the electronic apparatus 100 and can be charged. The measuring unit 102 measures a value capable of deriving capacity deterioration of the battery 101. A control unit 103 performs control to raise a charging voltage of the battery 101 based on a value measured by the measuring unit 102 and correspondence information between the value and the charging voltage of the battery 101.SELECTED DRAWING: Figure 1

Description

  The present invention relates to an electronic device using a rechargeable battery.

  Conventionally, for example, a rechargeable secondary battery such as a lithium ion battery has been used for a portable device such as a smartphone. For example, in a lithium ion battery, it is known that capacity deterioration (cycle deterioration) occurs in which battery capacity is reduced by repeating charge and discharge cycles. Moreover, the technique regarding charge of a lithium ion battery is known (for example, refer the following patent documents 1 and 2).

JP 2006-311793 A Japanese Patent Laid-Open No. 2002-078222

  However, the above-described conventional technology has a problem that it is not possible to suppress a decrease in battery capacity due to repeated charging.

  In one aspect, an object of the present invention is to provide an electronic device that can suppress a decrease in battery capacity due to repeated charging.

  In order to solve the above-described problems and achieve the object, in one embodiment, a battery that is a power source of the device and that can be charged, a measurement unit that measures a value capable of deriving capacity deterioration of the battery, An electronic device is proposed that includes a control unit that performs control to increase the charging voltage of the battery based on the value measured by the measuring unit and correspondence information between the value and the charging voltage of the battery. .

  According to one aspect of the present invention, it is possible to suppress a decrease in battery capacity due to repeated charging.

FIG. 1 is a diagram illustrating an example of the electronic apparatus according to the first embodiment. FIG. 2 is a diagram of an example of the terminal device according to the first embodiment. FIG. 3 is a diagram illustrating an example of characteristics of the battery capacity for each charging voltage with respect to the number of cycles in the battery according to the first embodiment. FIG. 4 is a diagram illustrating an example of a battery capacity characteristic with respect to a charging voltage in the battery according to the first embodiment. FIG. 5 is a diagram illustrating an example of battery capacity characteristics with respect to AC impedance in the battery according to the first embodiment. FIG. 6 is a diagram illustrating an example of correspondence information between the AC impedance and the charging voltage according to the first embodiment. FIG. 7 is a flowchart (part 1) illustrating an example of processing by the control circuit of the terminal device according to the first embodiment. FIG. 8 is a flowchart (part 2) illustrating an example of a process performed by the control circuit of the terminal device according to the first embodiment. FIG. 9 is a diagram illustrating an example of charge voltage control and battery capacity according to the first embodiment. FIG. 10 is a diagram illustrating another example of charge voltage control and battery capacity according to the first embodiment. FIG. 11 is a diagram of an example of the terminal device according to the second embodiment. FIG. 12 is a diagram illustrating an example of correspondence information between the number of cycles and the charging voltage according to the second embodiment. FIG. 13: is a flowchart (the 1) which shows an example of the process by the control circuit of the terminal device concerning Embodiment 2. FIG. 14 is a flowchart (part 2) illustrating an example of a process performed by the control circuit of the terminal device according to the second embodiment.

  Embodiments of an electronic apparatus according to the present invention will be described below in detail with reference to the drawings.

(Embodiment 1)
(Electronic device according to the first embodiment)
FIG. 1 is a diagram illustrating an example of the electronic apparatus according to the first embodiment. As illustrated in FIG. 1, the electronic device 100 according to the first embodiment includes a battery 101, a measurement unit 102, and a control unit 103. The electronic device 100 may further include a storage unit 104.

  The battery 101 is a power source for the electronic device 100 (own device), and can supply power to devices inside the electronic device 100. The battery 101 is a secondary battery that can be charged by applying a charging voltage. The battery 101 can be various secondary batteries whose capacity is deteriorated by repeated charging and whose capacity increases as the charging voltage increases.

  The measuring unit 102 measures a value from which the capacity deterioration of the battery 101 can be derived. Then, the measurement unit 102 outputs the measured value to the control unit 103. The value from which the capacity deterioration of the battery 101 can be derived is a value having a correlation with the capacity deterioration of the battery 101, for example. As an example, the value that can derive the capacity deterioration of the battery 101 is a value indicating the AC impedance of the battery 101.

  The control unit 103 acquires correspondence information between the value measured by the measurement unit 102 and the charging voltage of the battery 101 from the storage unit 104. For example, when the storage unit 104 is provided in the electronic device 100, the control unit 103 reads correspondence information from the storage unit 104. When the storage unit 104 is provided in a device different from the electronic device 100, the control unit 103 receives correspondence information of the storage unit 104 by communicating with the device.

  Then, the control unit 103 performs control to increase the charging voltage of the battery 101 based on the value output from the measurement unit 102 and the acquired correspondence information. For example, the control unit 103 detects an increase in AC impedance of the battery 101 based on the AC impedance of the battery 101 indicated by the value output from the measurement unit 102. And the control part 103 performs control which raises the charging voltage of the battery 101 based on correspondence information, when the alternating current impedance of the battery 101 becomes more than predetermined amount.

  The storage unit 104 stores correspondence information between the value measured by the measurement unit 102 and the charging voltage of the battery 101. This correspondence information associates, for example, a value measured by the measurement unit 102 with a higher charging voltage as the capacity degradation of the battery 101 derived from the value measured by the measurement unit 102 increases. Further, the storage unit 104 may be provided in the electronic device 100 as described above, or may be provided in a device different from the electronic device 100 (for example, a server device).

  As described above, according to the electronic device 100 illustrated in FIG. 1, it is possible to perform control to increase the charging voltage of the battery 101 based on the measurement result of the value that can derive the capacity deterioration of the battery 101 and the correspondence information. Thereby, the charging voltage of the battery 101 can be increased according to the capacity deterioration of the battery 101, and the decrease in the battery capacity due to repeated charging of the battery 101 can be suppressed.

  For example, by performing control to increase the charging voltage of the battery 101 so that the capacity of the battery 101 falls within a predetermined range, the battery capacity of the battery 101 can be made almost constant regardless of the number of times the battery 101 is charged. become. Therefore, for example, the time during which the user of the electronic device 100 can use the electronic device 100 without being aware of the deterioration of the battery 101 can be made almost constant.

(Terminal device according to the first embodiment)
FIG. 2 is a diagram of an example of the terminal device according to the first embodiment. In FIG. 2, a solid line arrow indicates a power supply line, and a dotted line arrow indicates a control line. The electronic device 100 shown in FIG. 1 can be realized by, for example, the terminal device 200 shown in FIG. The terminal device 200 is a mobile terminal such as a mobile phone or a smartphone that performs cellular communication by performing wireless transmission with a base station device, for example.

  The terminal device 200 includes a power supply circuit 201, a charging circuit 202, a battery 203, a control circuit 204, a memory 205, and a device power supply 206. The battery 101 shown in FIG. 1 can be realized by the battery 203, for example. The measurement unit 102 shown in FIG. 1 can be realized by the control circuit 204, for example. The control unit 103 shown in FIG. 1 can be realized by the charging circuit 202 and the control circuit 204, for example. The storage unit 104 illustrated in FIG. 1 can be realized by the memory 205, for example.

  The AC adapter 21 illustrated in FIG. 2 can be connected to the terminal device 200. When the AC adapter 21 is connected to the terminal device 200, the AC adapter 21 converts an AC voltage (for example, commercial power supply) input from the outside into a DC voltage, and supplies the converted DC voltage to the terminal device 200. . AC is an abbreviation for “Alternating Current”.

  When the AC adapter 21 is connected to the terminal device 200, the power supply circuit 201 supplies an operating voltage based on the DC voltage supplied from the AC adapter 21 to the control circuit 204, the memory 205, and the device power supply 206.

  When the AC adapter 21 is connected to the terminal device 200, the charging circuit 202 charges the battery 203 by supplying a charging voltage based on the DC voltage supplied from the AC adapter 21 to the battery 203. In addition, the charging circuit 202 converts the charging voltage based on the DC voltage supplied from the AC adapter 21 so as to become the voltage indicated by the charging voltage instruction output from the control circuit 204, and converts the converted charging voltage to the battery 203. Supply.

  The battery 203 is a secondary battery that can be charged by a charging voltage supplied from the charging circuit 202. The battery 203 supplies an operating voltage due to discharge to the power supply circuit 201 when the AC adapter 21 is not connected to the terminal device 200, and the power supply circuit 201 supplies the control circuit 204, the memory 205, and the device power supply 206. Supply. As an example, the battery 203 is a lithium ion secondary battery. However, the battery 203 is not limited to a lithium ion secondary battery, and can be various secondary batteries whose capacity is deteriorated by repeated charging and whose capacity increases as the charging voltage increases.

  When the AC adapter 21 is connected to the terminal device 200, the control circuit 204, the memory 205, and the device power source 206 operate with the operating voltage supplied from the power supply circuit 201 supplied with power from the AC adapter 21. Further, when the AC adapter 21 is not connected to the terminal device 200, the control circuit 204, the memory 205, and the device power source 206 operate with the operating voltage supplied from the power supply circuit 201 supplied with power from the battery 203.

  The control circuit 204 is a control unit that controls charging of the battery 203 by the charging circuit 202. For example, the control circuit 204 measures the AC impedance of the battery 203 (the internal resistance of the battery 203). As an example, the control circuit 204 inputs an AC voltage to the battery 203. The control circuit 204 calculates the AC impedance of the battery 203 by calculating a difference between the amplitude of the AC voltage input to the battery 203 and the amplitude of the AC voltage output from the battery 203 according to the input AC voltage. taking measurement.

  However, the AC impedance measurement by the control circuit 204 is not limited to this, and various methods can be used. For example, the control circuit 204 may measure the AC impedance of the battery 203 by detecting the output voltage when the battery 203 is fully charged. Alternatively, the control circuit 204 may estimate the AC impedance based on the charging and discharging history of the battery 203, the operation history of the device that receives power supply from the battery 203, and the like.

  Further, the control circuit 204 reads a correspondence table (for example, see FIG. 6) between the AC impedance of the battery 203 and the charging voltage of the battery 203 from the memory 205. Then, the control circuit 204 identifies the charging voltage associated with the measured AC impedance of the battery 203 in the read correspondence table, and stores the charging voltage information indicating the identified charging voltage in the memory 205. When the battery 203 is charged, the control circuit 204 reads out the charging voltage information stored in the memory 205 and outputs a charging voltage instruction indicating the charging voltage indicated by the read charging voltage information to the charging circuit 202.

  The control circuit 204 can be realized by a digital circuit such as a CPU or SoC, for example. CPU is an abbreviation for Central Processing Unit. SoC is an abbreviation for System-on-a-Chip. The processing by the control circuit 204 will be described later (see, for example, FIGS. 7 and 8).

  The memory 205 includes a main memory and an auxiliary memory, for example. The main memory is, for example, a RAM (Random Access Memory). The main memory is used as a work area for the control circuit 204 (for example, CPU). The auxiliary memory is a non-volatile memory such as a magnetic disk or a flash memory. Various programs for operating the terminal device 200 are stored in the auxiliary memory. The program stored in the auxiliary memory is loaded into the main memory and executed by the control circuit 204.

  The above-described correspondence table between the AC impedance of the battery 203 and the charging voltage of the battery 203 is stored in an auxiliary memory of the memory 205, for example. The above-described charging voltage information is stored in, for example, the main memory or auxiliary memory of the memory 205.

  The device power source 206 is a device power source that supplies power to each device included in the terminal device 200. Examples of devices included in the terminal device 200 include devices such as a control circuit, a wireless communication device, a wired communication device, and a user interface. The user interface includes, for example, a microphone, a speaker, a touch panel, and the like. Note that the device power supply 206 may be included in the power supply circuit 201.

(Characteristics of battery capacity with respect to the number of cycles in the battery according to the first embodiment for each charging voltage)
FIG. 3 is a diagram illustrating an example of characteristics of the battery capacity for each charging voltage with respect to the number of cycles in the battery according to the first embodiment. In FIG. 3, the horizontal axis indicates the number of charge / discharge cycles of the battery 203, and the vertical axis indicates the capacity (battery capacity) for each charging voltage of the battery 203.

  The cycle number battery capacity characteristics 301 to 307 have a charge voltage of 4.3 [V], 4.25 [V], 4.2 [V], 4.15 [V], 4.1 [V], 4 respectively. This is a characteristic of the capacity of the battery 203 with respect to the number of charge / discharge cycles of the battery 203 in the case of .05 [V] and 4.0 [V]. Each of the cycle number battery capacity characteristics 301 to 307 indicates the cycle number battery capacity characteristics in a 45 ° C. environment.

  For example, the cycle number battery capacity characteristic 301 indicates the capacity of the battery 203 with respect to the number of charge / discharge cycles when the charge voltage of the battery 203 is set to 4.3 [V] and charge / discharge of the battery 203 is repeated. The capacity of the battery 203 in this case is the capacity of the battery 203 based on the capacity (100%) when the battery 203 is fully charged at 4.3 [V] when the battery 203 is not deteriorated.

  The cycle number battery capacity characteristic 302 indicates the capacity of the battery 203 with respect to the number of charge / discharge cycles when the charge voltage of the battery 203 is set to 4.25 [V] and charge / discharge of the battery 203 is repeated. The capacity of the battery 203 in this case is the capacity of the battery 203 based on the capacity (100%) when the battery 203 is fully charged at 4.25 [V] when the battery 203 is not deteriorated.

  As shown in cycle number battery capacity characteristics 301 to 307, the capacity of the battery 203 decreases as the number of charge / discharge cycles of the battery 203 increases. Further, the rate of decrease in the capacity of the battery 203 according to the number of charge / discharge cycles is higher as the charging voltage of the battery 203 is higher.

(Characteristics of battery capacity with respect to charging voltage in the battery according to the first embodiment)
FIG. 4 is a diagram illustrating an example of a battery capacity characteristic with respect to a charging voltage in the battery according to the first embodiment. In FIG. 4, the horizontal axis indicates the charging voltage of the battery 203, and the vertical axis indicates the 4.3 [V] charging capacity (battery capacity) of the battery 203.

  The charge voltage battery capacity characteristic 400 is a characteristic of the 4.3 [V] charge reference capacity (battery capacity) of the battery 203 with respect to the charge voltage of the battery 203. The charging voltage battery capacity characteristic 400 is a characteristic when there is no capacity deterioration of the battery 203. As shown in the charging voltage battery capacity characteristic 400, the higher the charging voltage of the battery 203, the larger the reference capacity of the battery 203 during 4.3 [V] charging.

(Characteristics of battery capacity with respect to AC impedance in the battery according to the first embodiment)
FIG. 5 is a diagram illustrating an example of battery capacity characteristics with respect to AC impedance in the battery according to the first embodiment. In FIG. 5, the horizontal axis indicates the AC impedance of the battery 203, and the vertical axis indicates the capacity (battery capacity) when the capacity without deterioration of the battery 203 is 100%.

  The AC impedance battery capacity characteristic 500 is a capacity characteristic when the capacity without deterioration of the battery 203 is 100% with respect to the AC impedance of the battery 203. As shown in the AC impedance battery capacity characteristic 500, the AC impedance of the battery 203 increases as the capacity of the battery 203 decreases. Therefore, it is possible to estimate the deterioration of the capacity of the battery 203 by measuring the AC impedance of the battery 203.

(Correspondence information between AC impedance and charging voltage according to the first embodiment)
FIG. 6 is a diagram illustrating an example of correspondence information between the AC impedance and the charging voltage according to the first embodiment. In the memory 205 of the terminal device 200 shown in FIG. 2, for example, a correspondence table 600 shown in FIG. 6 is stored. The correspondence table 600 is correspondence information that associates the AC impedance of the battery 203 with the deterioration rate of the battery 203 and the charging voltage of the battery 203.

  The AC impedance of the battery 203 in the correspondence table 600 is, for example, the AC impedance of the battery 203 measured by the amplitude of the AC voltage output from the battery 203 when an AC voltage of 1 [kHz] is input to the battery 203.

  The deterioration rate of the battery 203 in the correspondence table 600 is determined based on the capacity of the battery 203 when the battery 203 without deterioration is charged at a predetermined voltage (for example, 4.3 [V]) as a reference (100%). It is the deterioration rate of the capacity of the battery 203 when charged with voltage. As an example, it is assumed that the battery 203 has a capacity of 3000 [mAh] when the battery 203 without deterioration is charged at 4.3 [V]. In this case, for example, when the deterioration rate of the battery 203 is 5%, the battery 203 is deteriorated and the capacity of the battery 203 when the battery 203 is charged at 4.3 [V] is 3000 * (1-0.05). ) = 2850 [mAh].

  The charging voltage of the battery 203 in the correspondence table 600 is a charging voltage that the charging circuit 202 should supply to the battery 203 in order to bring the capacity of the battery 203 within a predetermined range according to the deterioration rate of the battery 203. Next, a method for determining the charging voltage will be described.

  As an example, in the characteristics of the battery 203 shown in FIGS. 3 and 4, the charging voltage for maintaining the capacity of the battery 203 up to 500 cycles in the range of 80% to 85% on the basis of 4.3 [V] charging. A case of determination will be described. In this case, for example, the charging voltage (starting charging voltage) when the battery 203 is not deteriorated is set to 4.15 [V]. When the battery 203 is charged at 4.15 [V] with no deterioration of the battery 203, the capacity of the battery 203 is about 85% on the basis of 4.3 [V] charging (see FIG. 4).

  In addition, when the battery 203 is deteriorated in a state where the charging voltage is set to 4.15 [V], the capacity of the battery 203 is gradually decreased from 85% of the reference at the time of 4.3 [V] charging. Here, 5% of the capacity on the basis of 4.3 [V] charging corresponds to 5/85 * 100≈5.9% of the capacity on the basis of 4.15 [V] charging. For this reason, the decrease in capacity from 85% to 80% on the basis of 4.3 [V] charging is 100% to 100−5.9 = 94.1% on the basis of 4.15 [V] charging. This corresponds to a decline.

  When the charging voltage is 4.15 [V], the number of cycles until the capacity of the 4.15 [V] charging reference battery 203 is changed from 100% to 94.1% is about 160 cycles ( (See FIG. 3). That is, when the start charging voltage is 4.15 [V], the standard capacity of the battery 203 at the time of 4.3 [V] charging starts from 85% and is 80% in about 160 cycles (the deterioration rate is 5%). )become.

  For this reason, by raising the charging voltage at the time of 160 cycles from the start of use of the battery 203, it is possible to avoid the 4.3 [V] charging reference capacity of the battery 203 being less than 80%. Here, the charge voltage battery capacity characteristic 400 shown in FIG. 4 can be expressed, for example, by the following equation (1). In the equation (1), X is the 4.3 [V] charging reference capacity [%] of the battery 203, and Y is the charging voltage of the battery 203.

  Y = 0.01 * X + 3.3 (1)

  Therefore, assuming that the correlation of FIG. 4 is also present when the battery 203 is deteriorated, when the deterioration rate of the battery 203 is 5%, the capacity of the battery 203 is set to 85% of the standard at the time of 4.3 [V] charging. The charging voltage is Y = 0.01 * (85 * 100/95) + 3.3≈4.2 [V]. Therefore, by increasing the charging voltage of the battery 203 from 4.15 [V] to 4.2 [V], the 4.3 [V] charging reference capacity of the battery 203 can be returned to 85%.

  Similarly, when the battery 203 is deteriorated in a state where the charging voltage is set to 4.2 [V], the capacity of the battery 203 is gradually decreased from 85% of the reference at the time of 4.3 [V] charging. Here, 5% of the capacity on the basis of 4.3 [V] charging corresponds to 5/90 * 100≈5.6% of the capacity on the basis of 4.2 [V] charging. For this reason, the reduction in capacity from 85% to 80% on the basis of 4.3 [V] charging is from 95% to 95-5.6 = 89.4% on the basis of 4.2 [V] charging. This corresponds to a decline.

  When the charging voltage is 4.2 [V], the number of cycles until the capacity of the battery 203 at the time of 4.2 [V] charging is changed from 95% to 89.4% is about 150 cycles ( (See FIG. 3). Therefore, when the charging voltage is 4.2 [V], the capacity of the battery 203 at the time of 4.2 [V] charging becomes 89.4% at the time of about 160 + 150 = 310 cycles in total. That is, when the charging voltage of the battery 203 is set to 4.2 [V] at the time of 160 cycles, the standard capacity of the battery 203 at the time of 4.3 [V] charging starts from 85% and is 80% at about 310 cycles. (Deterioration rate is 10%).

  For this reason, by raising the charging voltage again at the time of 310 cycles from the start of use of the battery 203, it is possible to avoid the 4.3 [V] charging reference capacity of the battery 203 being less than 80%. For example, from the above equation (1), when the deterioration rate of the battery 203 is 10%, the charging voltage for setting the capacity of the battery 203 to 85% of the standard at the time of 4.3 [V] charging is Y = 0. 01 * (85 * 100/90) + 3.3≈4.25 [V]. Therefore, by increasing the charging voltage of the battery 203 from 4.2 [V] to 4.25 [V], the 4.3 [V] charging reference capacity of the battery 203 can be returned to 85%.

  Similarly, when the battery 203 is deteriorated in a state where the charging voltage is set to 4.25 [V], the capacity of the battery 203 is gradually decreased from 85% of the reference at the time of 4.3 [V] charging. Here, 5% of the capacity on the basis of 4.3 [V] charging corresponds to 5/95 * 100≈5.3% of the capacity on the basis of 4.25 [V] charging. For this reason, the reduction in capacity from 85% to 80% on the basis of 4.3 [V] charging is 90% to 90-5.3 = 84.7% on the basis of 4.25 [V] charging. This corresponds to a decline.

  When the charging voltage is 4.25 [V], the number of cycles until the capacity of the 4.203 [V] charging reference battery 203 is changed from 90% to 84.7% is about 150 cycles ( (See FIG. 3). Accordingly, when the charging voltage is 4.25 [V], the capacity of the battery 203 of the 4.25 [V] charging reference is 84.7% at a total of about 310 + 150 = 460 cycles. That is, when the charging voltage of the battery 203 is set to 4.25 [V] at the time of 310 cycles, the standard capacity of the battery 203 at the time of 4.3 [V] charging starts from 85% and is 80% at about 460 cycles. (Deterioration rate is 15%).

  For this reason, by raising the charging voltage again at the time of 460 cycles from the start of use of the battery 203, it is possible to prevent the 4.3 [V] charging reference capacity of the battery 203 from falling below 80%. For example, from the above equation (1), when the deterioration rate of the battery 203 is 15%, the charging voltage for setting the capacity of the battery 203 to 85% of the standard at the time of 4.3 [V] charging is Y = 0. 01 * (85 * 100/85) + 3.3 = 4.3 [V]. Therefore, by increasing the charging voltage of the battery 203 from 4.25 [V] to 4.3 [V], the 4.3 [V] charging reference capacity of the battery 203 can be returned to 85%.

  Similarly, when the battery 203 is deteriorated in a state where the charging voltage is set to 4.3 [V], the capacity of the battery 203 is gradually decreased from 85% of the reference at the time of 4.3 [V] charging. When the charging voltage is 4.3 [V], the number of cycles until the capacity of the 4.3 [V] charging reference battery 203 is changed from 85% to 80% is about 200 cycles (FIG. 3). reference). Therefore, when the charging voltage is 4.3 [V], the capacity of the battery 203 of the 4.3 [V] charging reference is 80% at a total time of about 460 + 200 = 660 cycles. That is, the capacity of the battery 203 up to at least 500 cycles can be kept in the range of 80% to 85% on the basis of 4.3 [V] charging.

  From the above, in the correspondence table 600, when the deterioration rate of the battery 203 is in the range of 0% to less than 5%, the capacity of the battery 203 is in the range of 80% to 85% on the basis of 4.3 [V] charging. 4.15 [V] is associated as a charge voltage that can be maintained. Further, in the correspondence table 600, when the deterioration rate of the battery 203 is in the range of 5% or more and less than 10%, the capacity of the battery 203 can be maintained in the range of 80% to 85% on the basis of 4.3 [V] charging. 4.2 [V] is associated as a possible charging voltage.

  Further, in the correspondence table 600, in the range where the deterioration rate of the battery 203 is 10% or more and less than 15%, the capacity of the battery 203 can be kept in the range of 80% to 85% on the basis of 4.3 [V] charging. 4.25 [V] is associated as a charge voltage that can be generated. Further, in the correspondence table 600, when the deterioration rate of the battery 203 is in the range of 15% or more, the capacity of the battery 203 is kept in the range of 80% to 85% on the basis of 4.3 [V] charge until at least 500 cycles. 4.3 [V] is associated with the charging voltage that can be used.

  In addition, based on the AC impedance battery capacity characteristic 500 shown in FIG. 5, in the correspondence table 600, the range of 0% or more and less than 5% of the deterioration rate of the battery 203 is 120 [mΩ] or more of the AC impedance of the battery 203. A range less than 124 [mΩ] is associated. Further, in the correspondence table 600, the range of 5% or more and less than 10% of the deterioration rate of the battery 203 is associated with the range of 124 [mΩ] or more and less than 128 [mΩ] of the AC impedance of the battery 203.

  In the correspondence table 600, the range of 10 to 15% of the deterioration rate of the battery 203 is associated with a range of 128 [mΩ] to less than 132 [mΩ] of the AC impedance of the battery 203. Further, in the correspondence table 600, the range of 15% or more of the deterioration rate of the battery 203 is associated with the range of 132 [mΩ] or more of the AC impedance of the battery 203.

  The terminal device 200 uses the charging voltage associated with the AC impedance measured in the correspondence table 600 as the charging voltage of the battery 203. As a result, the capacity of the battery 203 can be kept in the range of 80% to 85% on the basis of 4.3 [V] charging up to at least 500 cycles (for example, up to 660 cycles).

  For example, if the battery 203 without deterioration is charged at 4.3 [V] and the capacity is 3000 [mAh], the start charging voltage is set to 4.15 [V] to start the battery 203. The capacity is 3000 [mAh] × 85% = 2550 [mAh]. When the capacity is reduced to 150 [mAh] (5% of 3000 [mAh]) to 2400 [mAh] due to deterioration of the battery 203, the charging voltage is increased by 0.05 [V] to increase the capacity of the battery 203 to 2550. Control to return to [mAh] is repeatedly executed. Thereby, the capacity | capacitance of the battery 203 can be maintained in the range of 2400-2550 [mAh]. In this case, the nominal battery capacity of the battery 203 can be set to 2550 [mAh], for example.

  Note that the terminal device 200 only needs to be able to derive the charging voltage from the AC impedance using the correspondence table 600, and therefore the deterioration rate in the correspondence table 600 may be omitted.

(Processing by the control circuit of the terminal device according to the first embodiment)
FIG. 7 and FIG. 8 are flowcharts illustrating an example of processing by the control circuit of the terminal device according to the first embodiment. The control circuit 204 of the terminal device 200 according to the first embodiment executes the steps shown in FIGS. 7 and 8, for example. For example, the control circuit 204 executes the steps shown in FIGS. 7 and 8 when the terminal device 200 is powered on. As an example, it is assumed that the battery 203 has a capacity of 3000 [mAh] when the battery 203 without deterioration is charged at 4.3 [V].

  First, the control circuit 204 measures the AC impedance of the battery 203 (step S701). For example, the control circuit 204 inputs an AC voltage of 1 [kHz] to the battery 203, and compares the amplitude of the AC voltage output from the battery 203 with the input AC voltage. It can be carried out.

  Next, the control circuit 204 determines whether or not the AC impedance measured in step S701 is 120 [mΩ] or more and less than 124 [mΩ] (step S702). When the AC impedance is 120 [mΩ] or more and less than 124 [mΩ] (step S702: Yes), the deterioration rate of the battery 203 (4.3 [V] and the deterioration rate from the capacity during charging) is less than 5%. (See FIG. 6). In this case, the control circuit 204 refers to the correspondence table 600 and determines the charging voltage to 4.15 [V] (step S703). For example, the control circuit 204 stores charging voltage information indicating the determined 4.15 [V] in the memory 205. At this stage, the charging voltage is set to 4.15 [V] and the battery 203 is charged, so that the capacity of the battery 203 can be set in the range of 2400 [mAh] to 2550 [mAh].

  Next, the control circuit 204 determines whether or not to charge the battery 203 (step S704). As an example, whether to charge the battery 203 can be determined according to the connection state of the AC adapter 21 with respect to the terminal device 200 and the charge state of the battery 203. For example, the control circuit 204 determines to charge the battery 203 when the AC adapter 21 is connected to the terminal device 200 and the battery 203 is not fully charged. Further, the control circuit 204 determines that the battery 203 is not charged when the AC adapter 21 is not connected to the terminal device 200 or when the battery 203 is fully charged.

  If it is determined in step S704 that the battery 203 is not charged (step S704: No), the control circuit 204 proceeds to step S706. When it is determined that the battery 203 is charged (step S704: Yes), the control circuit 204 charges the battery 203 with the charging voltage determined in step S703 (step S705). For example, the control circuit 204 reads the charging voltage information stored in the memory 205 and outputs a charging voltage instruction indicating the charging voltage indicated by the read charging voltage information to the charging circuit 202.

  Next, the control circuit 204 determines whether or not the AC impedance measurement timing has come (step S706). The AC impedance measurement timing is, for example, a periodic timing, for example, a fixed time every day. If the AC impedance measurement timing has not come (step S706: No), the control circuit 204 returns to step S704. When it is the measurement timing of the AC impedance (step S706: Yes), the control circuit 204 measures the AC impedance of the battery 203 (step S707). The method for measuring the AC impedance is the same as that in step S701.

  Next, the control circuit 204 determines whether or not the AC impedance measured in step S707 is 124 [mΩ] or more (step S708). If the AC impedance is not greater than 124 [mΩ] (step S708: No), it can be determined that the capacity of the battery 203 is still greater than 2400 [mAh]. In this case, the control circuit 204 returns to step S704.

  In step S708, when the AC impedance is 124 [mΩ] or more (step S708: Yes), the deterioration rate of the battery 203 is about 5% (see FIG. 6), that is, the capacity of the battery 203 is about 2400 [mAh]. It can be judged that it became. In this case, the control circuit 204 refers to the correspondence table 600 and determines the charging voltage to 4.2 [V] (step S709). For example, the control circuit 204 stores charging voltage information indicating the determined 4.2 [V] in the memory 205. When the battery 203 is charged at the charging voltage of 4.2 [V] at this stage, the capacity of the battery 203 can be returned to 2550 [mAh].

  Next, the control circuit 204 determines whether or not to charge the battery 203 (step S710). The method for determining whether or not to charge the battery 203 is the same as in step S704. When it is determined that the battery 203 is not charged (step S710: No), the control circuit 204 proceeds to step S712. If it is determined that the battery 203 is to be charged (step S710: Yes), the control circuit 204 charges the battery 203 with the charging voltage determined in step S709 (step S711). For example, the control circuit 204 reads the charging voltage information stored in the memory 205 and outputs a charging voltage instruction indicating the charging voltage indicated by the read charging voltage information to the charging circuit 202.

  Next, the control circuit 204 determines whether or not the AC impedance measurement timing has come (step S712). The method for determining whether or not the AC impedance measurement timing has come is the same as in step S706. If the AC impedance measurement timing has not come (step S712: No), the control circuit 204 returns to step S710. When the timing for measuring the AC impedance is reached (step S712: Yes), the control circuit 204 measures the AC impedance of the battery 203 (step S713). The method for measuring the AC impedance is the same as that in step S701.

  Next, the control circuit 204 determines whether or not the AC impedance measured in step S713 is 128 [mΩ] or more (step S714). When the AC impedance is not 128 [mΩ] or more (step S714: No), it can be determined that the capacity of the battery 203 is still larger than 2400 [mAh]. In this case, the control circuit 204 returns to step S710.

  In step S714, when the AC impedance is 128 [mΩ] or more (step S714: Yes), the deterioration rate of the battery 203 is about 10% (see FIG. 6), that is, the capacity of the battery 203 is about 2400 [mAh]. It can be judged that it became. In this case, the control circuit 204 refers to the correspondence table 600 and determines the charging voltage to 4.25 [V] (step S715). For example, the control circuit 204 stores charging voltage information indicating the determined 4.25 [V] in the memory 205. If the battery 203 is charged by setting the charging voltage to 4.25 [V] at this stage, the capacity of the battery 203 can be returned to 2550 [mAh].

  Next, the control circuit 204 determines whether or not to charge the battery 203 (step S716). The method for determining whether or not to charge the battery 203 is the same as in step S704. If it is determined not to charge the battery 203 (step S716: No), the control circuit 204 proceeds to step S718. If it is determined that the battery 203 is to be charged (step S716: Yes), the control circuit 204 charges the battery 203 with the charging voltage determined in step S715 (step S717). For example, the control circuit 204 reads the charging voltage information stored in the memory 205 and outputs a charging voltage instruction indicating the charging voltage indicated by the read charging voltage information to the charging circuit 202.

  Next, the control circuit 204 determines whether or not the AC impedance measurement timing has come (step S718). The method for determining whether or not the AC impedance measurement timing has come is the same as in step S706. When the AC impedance measurement timing has not come (step S718: No), the control circuit 204 returns to step S716. When it is the measurement timing of the AC impedance (step S718: Yes), the control circuit 204 measures the AC impedance of the battery 203 (step S719). The method for measuring the AC impedance is the same as that in step S701.

  Next, the control circuit 204 determines whether or not the AC impedance measured in step S719 is 132 [mΩ] or more (step S720). When the AC impedance is not 132 [mΩ] or more (step S720: No), it can be determined that the capacity of the battery 203 is still larger than 2400 [mAh]. In this case, the control circuit 204 returns to step S716.

  In step S720, when the AC impedance is 132 [mΩ] or more (step S720: Yes), the deterioration rate of the battery 203 is about 15% (see FIG. 6), that is, the capacity of the battery 203 is about 2400 [mAh]. It can be judged that it became. In this case, the control circuit 204 refers to the correspondence table 600 and determines the charging voltage to 4.3 [V] (step S721). For example, the control circuit 204 stores charging voltage information indicating the determined 4.3 [V] in the memory 205.

  Next, the control circuit 204 determines whether or not to charge the battery 203 (step S722). The method for determining whether or not to charge the battery 203 is the same as in step S704. If it is determined that the battery 203 is not charged (step S722: No), the control circuit 204 returns to step S722. If it is determined that the battery 203 is to be charged (step S722: Yes), the control circuit 204 charges the battery 203 with the charging voltage determined in step S721 (step S723), and returns to step S722. In step S723, for example, the control circuit 204 reads the charging voltage information stored in the memory 205, and outputs a charging voltage instruction indicating the charging voltage indicated by the read charging voltage information to the charging circuit 202. Thereafter, the control circuit 204 does not have to measure the AC impedance of the battery 203.

  In step S702, when the AC impedance is not 120 [mΩ] or more and less than 124 [mΩ] (step S702: No), the control circuit 204 determines whether or not the AC impedance is 124 [mΩ] or more and less than 128 [mΩ]. Is determined (step S724). When the AC impedance is 124 [mΩ] or more and less than 128 [mΩ] (step S724: Yes), it can be determined that the deterioration rate of the battery 203 is 5% or more and less than 10% (see FIG. 6). In this case, the control circuit 204 proceeds to step S709.

  If the AC impedance is not 124 [mΩ] or more and less than 128 [mΩ] in Step S724 (Step S724: No), the control circuit 204 determines whether or not the AC impedance is 128 [mΩ] or more and less than 132 [mΩ]. Is determined (step S725). When the AC impedance is 128 [mΩ] or more and less than 132 [mΩ] (step S725: Yes), it can be determined that the deterioration rate of the battery 203 is 10% or more and less than 15% (see FIG. 6). In this case, the control circuit 204 proceeds to step S715.

  In step S725, when the AC impedance is 132 [mΩ] or more (step S725: No), it can be determined that the deterioration rate of the battery 203 is 15% or more (see FIG. 6). In this case, the control circuit 204 proceeds to step S721.

  Although the case where periodic timing is used as the AC impedance measurement timing has been described, the AC impedance measurement timing is not limited to this. For example, the control circuit 204 is based on the usage history (operation history or the like) of the terminal device 200 by the user of the terminal device 200, and the time period (midnight etc.) when the user of the terminal device 200 is not using the terminal device 200 is high. ) And the specified time zone may be used as the measurement timing. Further, the control circuit 204 may use a time zone that is the specified time zone and the user of the terminal device 200 is not actually using the terminal device 200 as the measurement timing.

(Control of charging voltage and battery capacity according to the first embodiment)
FIG. 9 is a diagram illustrating an example of charge voltage control and battery capacity according to the first embodiment. In FIG. 9, the horizontal axis indicates the number of charge / discharge cycles of the battery 203. A battery capacity 901 indicates a standard capacity of the battery 203 at the time of 4.3 [V] charging. A charging voltage 902 indicates a charging voltage of the battery 203.

  As described above, the terminal device 200 sets, for example, the charge voltage 902 at the start (when the number of cycles = 0) to 4.15 [V]. At this point, the battery capacity 901 is 85%. As the number of cycles increases, the battery capacity 901 decreases, but the terminal device 200 decreases the battery capacity 901 to 85% whenever the battery capacity 901 decreases to 80% (the deterioration rate increases by 5%). The charging voltage 902 is increased so as to return. Thereby, battery capacity 901 can be maintained in the range of 80% to 85% for at least 500 cycles (for example, up to 660 cycles).

  In addition, when the limit value (maximum value) of the charging voltage 902 is 4.3 [V], after the charging voltage 902 is set to 4.3 [V], the charging voltage 902 may be increased after that. Can not. For this reason, although the battery capacity 901 gradually deteriorates, the battery capacity 901 can be prevented from being deteriorated for a long period of time.

  Further, the control for increasing the charging voltage 902 every time the deterioration rate of the battery capacity 901 increases by 5% has been described, but the present invention is not limited to such control. For example, by increasing the charging voltage 902 every time the deterioration rate of the battery capacity 901 increases by Z%, the capacity fluctuation of the battery capacity 901 can be made within Z%. In this case, for example, the above-described start charging voltage may be adjusted according to Z. For example, if Z <5, the fluctuation of the battery capacity 901 can be made smaller than the example shown in FIG. 9 (see, for example, FIG. 10). Alternatively, Z> 5 may be set.

  FIG. 10 is a diagram illustrating another example of charge voltage control and battery capacity according to the first embodiment. In FIG. 10, the same parts as those shown in FIG. FIG. 10 shows a change in the battery capacity 901 when the control is performed to increase the charging voltage 902 in fine units from the example shown in FIG. 9 (when Z <5).

  Thus, according to the terminal device 200 according to the first embodiment, it is possible to perform control for increasing the charging voltage of the battery 203 based on the measurement result of the AC impedance of the battery 203 and the correspondence table 600. Thereby, the charging voltage of the battery 203 can be increased in accordance with the capacity deterioration of the battery 203, and the decrease in the battery capacity due to repeated charging of the battery 203 can be suppressed.

  For example, by performing control to increase the charging voltage of the battery 203 so that the capacity of the battery 203 is within a predetermined range (80% to 85% in the above example), regardless of the number of times the battery 203 is charged. The battery capacity of the battery 203 can be made almost constant. Therefore, for example, the time during which the user of the terminal device 200 can use the terminal device 200 without charging the battery 203 can be made substantially constant.

(Embodiment 2)
In the second embodiment, parts different from the first embodiment will be described. In the second embodiment, a case will be described in which a value corresponding to the accumulated charging time of the battery 101 is used as a value from which the above-described capacity degradation of the battery 101 can be derived. The value corresponding to the accumulated charging time of the battery 101 may be information indicating the accumulated charging time of the battery 101, information indicating a quotient obtained by dividing the accumulated charging time of the battery 101 by a predetermined time, or the like. The cumulative charging time of the battery 101 is, for example, the total charging time of the battery 101 from a state where the battery 101 is not deteriorated (unused state).

(Terminal device according to the second embodiment)
FIG. 11 is a diagram of an example of the terminal device according to the second embodiment. In FIG. 11, the same parts as those shown in FIG. As shown in FIG. 11, the charging circuit 202 according to the second embodiment outputs charging history information indicating the charging history of the battery 203 to the control circuit 204. The charging history information is information for notifying the timing of starting and stopping charging of the battery 203, for example. Alternatively, the charging history information is information for notifying the charging time length after the charging of the battery 203 is stopped.

  The control circuit 204 calculates the accumulated charging time of the battery 203 based on the charging history information output from the charging circuit 202, and stores the accumulated charging time information indicating the calculated accumulated charging time in the memory 205. Then, the control circuit 204 reads the accumulated charging time information stored in the memory 205, and corresponds to charging / discharging by dividing the accumulated charging time indicated by the read accumulated charging time information by the charging time for a predetermined cycle. Deriving the number of cycles. The charging time for one cycle is a charging time required for charging the battery 203 from a state where the remaining battery level is 0% to a state where the remaining battery level is 100%.

  Further, the control circuit 204 reads a correspondence table (for example, see FIG. 12) between the number of cycles corresponding to charging / discharging of the battery 203 and the charging voltage of the battery 203 from the memory 205. Then, the control circuit 204 identifies the charging voltage associated with the calculated number of cycles corresponding to the charge / discharge in the read correspondence table, and stores the charging voltage information indicating the identified charging voltage in the memory 205. When the battery 203 is charged, the control circuit 204 reads out the charging voltage information stored in the memory 205 and outputs a charging voltage instruction indicating the charging voltage indicated by the read charging voltage information to the charging circuit 202.

  In addition, the control circuit 204 does not need to input an AC voltage to the battery 203 and measure the AC impedance of the battery 203.

(Correspondence information between cycle number and charging voltage according to the second embodiment)
FIG. 12 is a diagram illustrating an example of correspondence information between the number of cycles and the charging voltage according to the second embodiment. In the memory 205 of the terminal device 200 shown in FIG. 11, for example, a correspondence table 1200 shown in FIG. 12 is stored. The correspondence table 1200 is correspondence information that associates the number of cycles corresponding to charging / discharging of the battery 203, the accumulated charging time [h] of the battery 203, and the charging voltage of the battery 203.

  The accumulated charging time of the battery 203 in the correspondence table 1200 is, for example, the total time when the battery 203 is charged since the battery 203 is not used (uncharged). The number of cycles corresponding to charging / discharging of the battery 203 is a quotient obtained by dividing the cumulative charging time of the battery 203 by the charging time for one cycle described above. In the example shown in FIG. 12, the charging time for one cycle is 150 minutes (2.5 [h]).

  The charging voltage of the battery 203 in the correspondence table 1200 is determined by the charging circuit 202 in order to bring the capacity of the battery 203 within a predetermined range according to the number of cycles corresponding to charging / discharging of the battery 203 (that is, the deterioration rate of the battery 203). This is the charging voltage to be supplied to the battery 203. Next, a method for determining the charging voltage will be described.

  As an example, as in the first embodiment, in the characteristics of the battery 203 shown in FIGS. 3 and 4, the capacity of the battery 203 up to 500 cycles is 80% to 85% on the basis of 4.3 [V] charging. A case where the charging voltage for maintaining the range is determined will be described. In this case, for example, the charging voltage (starting charging voltage) when the battery 203 is not deteriorated is set to 4.15 [V].

  The deterioration rate of the battery 203 in the correspondence table 1200 can be estimated from the number of cycles of the battery 203 based on, for example, the characteristics of the battery 203 shown in FIG. For example, when the cycle number of the battery 203 is 0 cycle or more and less than 160 cycles, it can be estimated that the deterioration rate of the battery 203 is 0% or more and less than 5% (see FIG. 3). For this reason, in the correspondence table 1200, when the number of cycles corresponding to charging / discharging of the battery 203 is in a range of 0 cycle or more and less than 160 cycles, the deterioration rate of the battery 203 corresponds to a range of 0% or more and less than 5%. [V] (see FIG. 6) is associated.

  When the cycle number of the battery 203 is 160 cycles or more and less than 310 cycles, it can be estimated that the deterioration rate of the battery 203 is 5% or more and less than 10% (see FIG. 3). For this reason, in the correspondence table 1200, when the number of cycles corresponding to charging / discharging of the battery 203 is in a range of 160 cycles or more and less than 310 cycles, the deterioration rate of the battery 203 corresponds to a range of 5% or more and less than 10%. [V] (see FIG. 6) is associated.

  Further, when the cycle number of the battery 203 is 310 cycles or more and less than 460 cycles, it can be estimated that the deterioration rate of the battery 203 is 10% or more and less than 15% (see FIG. 3). Therefore, in the correspondence table 1200, when the number of cycles corresponding to charging / discharging of the battery 203 is in the range of 310 cycles or more and less than 460 cycles, the deterioration rate of the battery 203 corresponds to the range of 10% or more and less than 15%. [V] (see FIG. 6) is associated.

  Moreover, when the cycle number of the battery 203 is 460 cycles or more, it can be estimated that the deterioration rate of the battery 203 is 15% or more (see FIG. 3). For this reason, in the correspondence table 1200, when the number of cycles corresponding to charge / discharge of the battery 203 is in the range of 460 cycles or more, 4.3 [V] corresponding to the range in which the deterioration rate of the battery 203 is 15% or more (FIG. 6). Reference).

  The terminal device 200 derives the number of cycles corresponding to charging / discharging of the battery 203 from the accumulated charging time, and uses the charging voltage associated with the number of cycles derived in the correspondence table 1200 as the charging voltage of the battery 203. Thereby, as in the first embodiment, the capacity of the battery 203 can be kept in the range of 80% to 85% on the basis of 4.3 [V] charging for at least 500 cycles (for example, up to 660 cycles).

  As described above, when the terminal device 200 determines the charging voltage of the battery 203 from the number of cycles and the correspondence table 1200, the cumulative charging time of the battery 203 may be omitted from the correspondence table 1200.

  Further, the terminal device 200 may use the charging voltage associated with the accumulated charging time in the correspondence table 1200 as the charging voltage of the battery 203. In this case, the number of cycles corresponding to charging / discharging of the battery 203 in the correspondence table 1200 may be omitted. In this case, the terminal device 200 may not calculate the number of cycles corresponding to charging / discharging of the battery 203.

(Processing by the control circuit of the terminal device according to the second embodiment)
13 and 14 are flowcharts illustrating an example of processing performed by the control circuit of the terminal device according to the second embodiment. The control circuit 204 of the terminal device 200 according to the second embodiment executes the steps shown in FIGS. 13 and 14, for example. For example, the control circuit 204 executes the steps shown in FIGS. 13 and 14 when the terminal device 200 is powered on.

  As an example, it is assumed that the battery 203 has a capacity of 3000 [mAh] when the battery 203 without deterioration is charged at 4.3 [V]. Further, the control circuit 204 calculates the cumulative charging time of the battery 203 based on the charging history information output from the charging circuit 202, and repeats the process of storing the cumulative charging time information indicating the calculated cumulative charging time in the memory 205. Suppose that

  First, the control circuit 204 derives the number of cycles corresponding to charge / discharge (step S1301). For example, the control circuit 204 reads the accumulated charging time information stored in the memory 205, and divides the accumulated charging time indicated by the read accumulated charging time information by the charging time for the above-mentioned one cycle to thereby perform a cycle corresponding to charging / discharging. Deriving a number.

  Next, the control circuit 204 determines whether or not the number of cycles derived in step S1301 is 0 cycle or more and less than 160 cycles (step S1302). When the cycle is 0 cycle or more and less than 160 cycles (step S1302: Yes), the deterioration rate of the battery 203 (deterioration rate from the capacity at the time of charging at 4.3 [V]) may be determined to be less than 5%. it can. In this case, the control circuit 204 refers to the correspondence table 1200 and determines the charging voltage to be 4.15 [V] (step S1303). For example, the control circuit 204 stores charging voltage information indicating the determined 4.15 [V] in the memory 205. At this stage, the charging voltage is set to 4.15 [V] and the battery 203 is charged, so that the capacity of the battery 203 can be set in the range of 2400 [mAh] to 2550 [mAh].

  Next, the control circuit 204 determines whether or not to charge the battery 203 (step S1304). The method for determining whether or not to charge the battery 203 is the same as in step S704 shown in FIG. When it is determined that the battery 203 is not charged (step S1304: No), the control circuit 204 proceeds to step S1306. When it is determined that the battery 203 is to be charged (step S1304: Yes), the control circuit 204 charges the battery 203 with the charging voltage determined in step S1303 (step S1305). For example, the control circuit 204 reads the charging voltage information stored in the memory 205 and outputs a charging voltage instruction indicating the charging voltage indicated by the read charging voltage information to the charging circuit 202.

  Next, the control circuit 204 determines whether or not the cycle number determination timing has come (step S1306). The cycle number determination timing is the same as the AC impedance measurement timing described above, for example. When it is not the cycle number determination timing (step S1306: NO), the control circuit 204 returns to step S1304. When the cycle number determination timing comes (step S1306: Yes), the control circuit 204 derives the cycle number of the battery 203 (step S1307). The method for deriving the cycle number is the same as that in step S1301.

  Next, the control circuit 204 determines whether or not the number of cycles derived in step S1307 is 160 or more (step S1308). When the number of cycles is not 160 cycles or more (step S1308: No), it can be determined that the capacity of the battery 203 is still greater than 2400 [mAh]. In this case, the control circuit 204 returns to step S1304.

  In step S1308, when the number of cycles is 160 cycles or more (step S1308: Yes), it can be determined that the deterioration rate of the battery 203 is about 5%, that is, the capacity of the battery 203 is about 2400 [mAh]. . In this case, the control circuit 204 refers to the correspondence table 1200 and determines the charging voltage to 4.2 [V] (step S1309). For example, the control circuit 204 stores charging voltage information indicating the determined 4.2 [V] in the memory 205. When the battery 203 is charged at the charging voltage of 4.2 [V] at this stage, the capacity of the battery 203 can be returned to 2550 [mAh].

  Next, the control circuit 204 determines whether or not to charge the battery 203 (step S1310). The method for determining whether or not to charge the battery 203 is the same as in step S1304. When it is determined that the battery 203 is not charged (step S1310: No), the control circuit 204 proceeds to step S1312. If it is determined that the battery 203 is to be charged (step S1310: Yes), the control circuit 204 charges the battery 203 with the charging voltage determined in step S1309 (step S1311). For example, the control circuit 204 reads the charging voltage information stored in the memory 205 and outputs a charging voltage instruction indicating the charging voltage indicated by the read charging voltage information to the charging circuit 202.

  Next, the control circuit 204 determines whether or not the cycle number determination timing has come (step S1312). The method for determining whether or not the cycle number determination timing has come is the same as in step S1306. When it is not the determination timing of the number of cycles (step S1312: No), the control circuit 204 returns to step S1310. When the cycle number determination timing is reached (step S1312: YES), the control circuit 204 derives the cycle number of the battery 203 (step S1313). The method for deriving the cycle number is the same as that in step S1301.

  Next, the control circuit 204 determines whether or not the number of cycles derived in step S1313 is 310 or more (step S1314). When the number of cycles is not 310 or more (step S1314: No), it can be determined that the capacity of the battery 203 is still greater than 2400 [mAh]. In this case, the control circuit 204 returns to step S1310.

  In step S1314, when the number of cycles is 310 cycles or more (step S1314: Yes), it can be determined that the deterioration rate of the battery 203 is about 10%, that is, the capacity of the battery 203 is about 2400 [mAh]. . In this case, the control circuit 204 refers to the correspondence table 1200 and determines the charging voltage to 4.25 [V] (step S1315). For example, the control circuit 204 stores charging voltage information indicating the determined 4.25 [V] in the memory 205. If the battery 203 is charged by setting the charging voltage to 4.25 [V] at this stage, the capacity of the battery 203 can be returned to 2550 [mAh].

  Next, the control circuit 204 determines whether or not to charge the battery 203 (step S1316). The method for determining whether or not to charge the battery 203 is the same as in step S1304. When it is determined that the battery 203 is not charged (step S1316: No), the control circuit 204 proceeds to step S1318. When it is determined that the battery 203 is to be charged (step S1316: Yes), the control circuit 204 charges the battery 203 with the charging voltage determined in step S1315 (step S1317). For example, the control circuit 204 reads the charging voltage information stored in the memory 205 and outputs a charging voltage instruction indicating the charging voltage indicated by the read charging voltage information to the charging circuit 202.

  Next, the control circuit 204 determines whether or not the cycle number determination timing has come (step S1318). The method for determining whether or not the cycle number determination timing has come is the same as in step S1306. If the cycle number determination timing has not come (step S1318: NO), the control circuit 204 returns to step S1316. When the cycle number determination timing is reached (step S1318: YES), the control circuit 204 derives the cycle number of the battery 203 (step S1319). The method for deriving the cycle number is the same as that in step S1301.

  Next, the control circuit 204 determines whether or not the number of cycles derived in step S1319 is 460 or more (step S1320). When the number of cycles is not 460 cycles or more (step S1320: No), it can be determined that the capacity of the battery 203 is still larger than 2400 [mAh]. In this case, the control circuit 204 returns to step S1316.

  In step S1320, when the number of cycles is 460 cycles or more (step S1320: Yes), it can be determined that the deterioration rate of the battery 203 is about 15%, that is, the capacity of the battery 203 is about 2400 [mAh]. . In this case, the control circuit 204 refers to the correspondence table 1200 and determines the charge voltage to 4.3 [V] (step S1321). For example, the control circuit 204 stores charging voltage information indicating the determined 4.3 [V] in the memory 205.

  Next, the control circuit 204 determines whether or not to charge the battery 203 (step S1322). The method for determining whether or not to charge the battery 203 is the same as in step S1304. When it is determined that the battery 203 is not charged (step S1322: No), the control circuit 204 returns to step S1322. If it is determined that the battery 203 is to be charged (step S1322: Yes), the control circuit 204 charges the battery 203 with the charging voltage determined in step S1321 (step S1323), and the process returns to step S1322. In step S 1323, for example, the control circuit 204 reads the charging voltage information stored in the memory 205, and outputs a charging voltage instruction indicating the charging voltage indicated by the read charging voltage information to the charging circuit 202. Thereafter, the control circuit 204 does not have to derive the number of cycles of the battery 203.

  In step S1302, when the cycle number is not 0 cycle or more and less than 160 cycle (step S1302: No), the control circuit 204 determines whether or not the cycle number is 160 cycle or more and less than 310 cycle (step S1324). When the number of cycles is 160 cycles or more and less than 310 cycles (step S1324: Yes), it can be determined that the deterioration rate of the battery 203 is 5% or more and less than 10%. In this case, the control circuit 204 proceeds to step S1309.

  In step S1324, when the cycle number is not 160 cycles or more and less than 310 cycles (step S1324: No), the control circuit 204 determines whether the cycle number is 310 cycles or more and less than 460 cycles (step S1325). When the number of cycles is 310 cycles or more and less than 460 cycles (step S1325: Yes), it can be determined that the deterioration rate of the battery 203 is 10% or more and less than 15%. In this case, the control circuit 204 proceeds to step S1315.

  In step S1325, when the number of cycles is 460 cycles or more (step S1325: No), it can be determined that the deterioration rate of the battery 203 is 15% or more. In this case, the control circuit 204 proceeds to step S1321.

  As described above, according to the terminal device 200 according to the second embodiment, based on the measurement result of the value corresponding to the cumulative charging time of the battery 203 (for example, the number of cycles corresponding to charging / discharging of the battery 203) and the correspondence table 1200. Control for increasing the charging voltage of the battery 203 can be performed. Thereby, similarly to Embodiment 1, the charging voltage of the battery 203 is increased in accordance with the capacity deterioration of the battery 203, and a decrease in the battery capacity due to repeated charging of the battery 203 can be suppressed. In addition, since it is not necessary to provide a function of measuring the AC impedance of the battery 203, the device configuration of the terminal device 200 can be simplified.

  In each of the above-described embodiments, the case where the electronic device 100 illustrated in FIG. 1 is realized by the terminal device 200 has been described. However, the electronic device 100 is not limited to the terminal device 200, and various electronic devices that use secondary batteries. Can be applied to. Examples of electronic devices using secondary batteries include various electronic devices such as notebook personal computers, portable game machines, portable audio players, mobile batteries, and secondary battery electric vehicles.

  As described above, according to the electronic apparatus, it is possible to suppress a decrease in battery capacity due to repeated charging.

  For example, in a secondary battery such as a lithium ion battery, battery deterioration due to repeated charge and discharge is inevitable. For this reason, conventionally, since the battery was charged at a constant voltage, the battery was deteriorated and the battery capacity was reduced. Accordingly, there was a problem that the usable time of the mobile device such as a smartphone was shortened. As a result, users of mobile devices such as smartphones use the same every day, which leads to dissatisfaction that the remaining battery level after use has been reduced or the battery has run out It was. In addition, for example, in the technology that suppresses the deterioration of the battery by reducing the charging voltage, the battery capacity is not deteriorated from the viewpoint of the user.

  For example, even if a user of a mobile device such as a smartphone uses the same method every day, the user can see that the remaining battery level gradually decreases due to the remaining battery level display. For this reason, the user of the portable device has been dissatisfied or stressed by reducing the use so as not to run out of the battery, or has anxiety that the battery may run out.

  However, according to each of the above-described embodiments, for example, the battery itself deteriorates by lowering the charging voltage at the time of a new battery and gradually increasing the charging voltage according to the battery deterioration. The battery capacity is almost unchanged. That is, it is possible to prevent the battery capacity from deteriorating for a certain period by controlling the charging voltage according to the battery capacity deterioration. For this reason, for example, it becomes possible to eliminate the dissatisfaction that the usable time of a portable device such as a smartphone is shortened.

  The following additional notes are disclosed with respect to the above-described embodiments.

(Appendix 1) A battery that is a power source of the device and can be charged;
A measuring unit for measuring a value capable of deriving capacity deterioration of the battery;
A control unit that performs control to increase the charging voltage of the battery based on the value measured by the measuring unit, and correspondence information between the value and the charging voltage of the battery;
An electronic device comprising:

(Supplementary note 2) The electronic device according to supplementary note 1, wherein the correspondence information associates the value with the charging voltage that is higher as the capacity deterioration of the battery derived from the value increases.

(Additional remark 3) The said control part performs control which raises the charging voltage of the said battery so that the capacity | capacitance of the said battery may become in a predetermined range, The electronic device of Additional remark 1 or 2 characterized by the above-mentioned.

(Additional remark 4) The said value is a value which shows the alternating current impedance of the said battery,
The control unit performs control to increase a charging voltage of the battery when an increase in the AC impedance is detected based on the value.
The electronic device according to any one of appendices 1 to 3, wherein:

(Supplementary Note 5) The measurement unit inputs an AC voltage to the battery, and calculates a difference between the amplitude of the input AC voltage and the amplitude of the AC voltage output from the battery according to the input AC voltage. The electronic device according to appendix 4, wherein a value indicating an AC impedance of the battery is measured based on the electronic device.

(Additional remark 6) The said value is a value according to the accumulation charge time of the said battery, The electronic device as described in any one of additional marks 1-3 characterized by the above-mentioned.

(Supplementary note 7) The electronic device according to any one of supplementary notes 1 to 6, wherein the battery is a battery whose capacity increases as the charging voltage increases.

DESCRIPTION OF SYMBOLS 21 AC adapter 100 Electronic device 101,203 Battery 102 Measuring part 103 Control part 104 Memory | storage part 200 Terminal apparatus 201 Power supply circuit 202 Charging circuit 204 Control circuit 205 Memory 206 Device power supply 301-307 Cycle number battery capacity characteristic 400 Charge voltage Battery capacity characteristic 500 AC impedance battery capacity characteristics 600, 1200 Correspondence table 901 Battery capacity 902 Charging voltage

Claims (4)

A battery that can be charged as a power source for its own device,
A measuring unit for measuring a value capable of deriving capacity deterioration of the battery;
A control unit that performs control to increase the charging voltage of the battery based on the value measured by the measuring unit, and correspondence information between the value and the charging voltage of the battery;
An electronic device comprising:   The electronic device according to claim 1, wherein the control unit performs control to increase a charging voltage of the battery so that a capacity of the battery is within a predetermined range. The value is a value indicating the AC impedance of the battery,
The control unit performs control to increase a charging voltage of the battery when an increase in the AC impedance is detected based on the value.
The electronic device according to claim 1, wherein the electronic device is an electronic device.   The electronic device according to claim 1, wherein the value is a value corresponding to a cumulative charge time of the battery.

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