JP2008067523A - Portable terminal - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a portable terminal which can accurately determine the deterioration of a battery by itself in a short time, while charging the battery by connecting the portable terminal to an AC adapter, and can display or output the result with an arbitrary timing. <P>SOLUTION: While turning power supply to loads 12-14 off and charging a battery 6 with a constant current, battery voltage 6a is measured, while raising precision at a detecting section 16, when the battery voltage is in the vicinity of full charge voltage; and then the measured voltage is recorded in a measurement data storage memory 19 (voltage before the change). Subsequently, charging is stopped, and power supply to the loads is turned on and then the battery voltage 6a is measured and recorded (voltage after the change). Charging is sustained. The voltage difference before and after change is divided by previously a known current difference a before and after change, to obtain the internal resistance of the battery 6. Furthermore, the internal resistance is corrected by the temperature measured by a thermistor 7, and the corrected internal resistance is recorded in the measurement data storage memory 19. Deterioration of the battery is decided by this variational amount in the corrected internal resistance. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a portable terminal equipped with a secondary battery, which performs determination and display of characteristic deterioration of the secondary battery while the secondary battery is mounted.

(Background Technology 1)
Secondary batteries deteriorate over time due to stress such as repeated charge / discharge, high temperature, high voltage, etc., increasing internal resistance and decreasing battery capacity. As a method for determining the deterioration of the battery, there are a method for measuring the internal resistance and a method for measuring a charge amount from a discharge end state of the battery to a full charge. However, the internal resistance of the battery varies depending on the measurement conditions, and it is difficult to measure the change in internal resistance accompanying the original battery deterioration. The method of measuring the charge amount by charging / discharging requires time for measurement. The relationship between the internal resistance value and the battery capacity has a large individual variation, and there is a problem that even if the internal resistance value is measured, it does not always correspond to the battery capacity accurately.
In addition, in a mobile phone equipped with a secondary battery, the secondary battery is removed from the mobile phone, and the battery characteristics are measured with a dedicated battery measuring instrument. It was inconvenient for users. Also, the mobile phone needs to have a structure in which the secondary battery can be easily detached, and the structure is complicated.

(Background Technology 2)
There is a battery remaining capacity display device that displays the battery life by measuring the internal resistance of the battery (see, for example, Patent Document 1). In Patent Document 1, the internal resistance of the battery is measured by a voltage drop when the battery is discharged to the constant current load circuit 7. Furthermore, when the temperature is measured and it is determined that the temperature is other than room temperature, temperature correction is added to the internal resistance value. The battery life is determined based on the internal resistance value after the temperature correction, and the battery replacement is displayed (paragraphs 0024 to 0039).

(Background Technology 3)
There is a battery deterioration determination device that determines the battery deterioration by measuring the internal resistance of the battery (see, for example, Patent Document 2). In Patent Document 2, the internal resistance of the battery is measured based on a voltage drop when the battery is discharged to the resistor 12, and further corrected and stored by temperature. This process is performed in the initial state when the battery is shipped. In addition, the deterioration is determined by the amount of change from the initial internal resistance at regular or arbitrary times in actual use (paragraphs 0006 to 0016). In addition, the voltage in the fully charged state during trickle charging is measured in the initial state and actual use of the battery. When the battery deteriorates and the internal resistance increases, the voltage in the fully charged state also increases due to the charging current, so the deterioration is determined by comparing the voltage in the fully charged state between the initial state and actual use. (Paragraph 0017). By these methods, the problem of the internal resistance variation between battery solids is solved.
Japanese Unexamined Patent Publication No. 2000-12104 (paragraphs 0024 to 0039, FIGS. 1, 2, and 4) JP 2000-215923 A (paragraphs 0006 to 0019, FIGS. 1 to 5)

The internal resistance of the battery varies depending on the SOC of the battery (State of Charge; charged state indicating full charge, complete discharge, etc.), but Background Art 2 (Patent Document 1) and Background Technology 3 (Patent Document 2) Does not have that description. Moreover, in the mobile phone of Background Art 1, as is often referred to as “high frequency charging” or “low discharge depth charging”, the user often puts it on the charging stand immediately after using it a little. In this case, the battery is always in a fully charged state, that is, in a specific SOC state. In that case, a device is required for measuring the internal resistance.
Further, the internal resistance is measured only when the battery is discharged or charged. In this case, the voltage drop value is small and the measurement accuracy is deteriorated. Further, if the measurement is performed only when the battery is discharged, there is a problem that the battery current is consumed for the measurement.

  The present invention solves the conventional problems and accurately determines battery deterioration in a short time by placing the mobile terminal on an AC adapter while charging the mobile terminal itself. It is an object of the present invention to provide a portable terminal that can display or output the result without being affected by the individual variation of the relationship.

  In order to achieve the above object, the portable terminal of the present invention includes a rechargeable battery, a load unit supplied with current from the battery, and the load unit when the battery voltage is a voltage near a predetermined full charge. The first state in which the first load current is passed to the second state and the second state in which the second load current greater than the first load current is passed are switched, the battery voltages in the first state and the second state are measured, and the battery voltage The difference is calculated, or the battery voltage difference is divided by the battery current difference between the first state and the second state to calculate the internal resistance of the battery. Further, the change amount of the battery voltage difference or the internal resistance Control means for calculating a change amount and notifying information on the battery characteristics corresponding to the change amount of the battery voltage difference or the change amount of the internal resistance is provided.

  According to the present invention, it is possible to accurately determine battery deterioration in a short time with the mobile terminal itself while the battery is mounted on the mobile terminal, and display or output the result.

Embodiments of the present invention will be described below with reference to the drawings.
FIG. 1 is a block diagram of relevant portions of a mobile terminal according to each embodiment of the present invention. The portable terminal 100 includes a contact 1, a diode 2, a charging circuit 3, a battery 6, a thermistor 7, an operation unit 8, transistor switches 9 to 11, a transmission power amplifier 12, an LCD 13, a white LED 14, a control unit 15, and the like. Furthermore, the charging circuit 3 includes a transistor switch 4, a voltage control circuit 5, and the like. The control unit 15 includes a detection unit 16, a current storage memory 17, a battery temperature characteristic memory 18, a measurement data storage memory 19, a charge number counter 20, and the like. The AC adapter 200 (not shown) is a constant current source for charging the mobile terminal 100, and the mobile terminal 100 is placed on the AC adapter 200 during charging.

  The contact 1 of the mobile terminal 100 is a connection contact with the AC adapter 200. The diode 2 is for protecting the portable terminal 100 when a non-genuine AC adapter is mistakenly connected in reverse polarity. The diode 2 prevents power from being supplied from the battery 6 to the contact 1 through a specific path inside the charging circuit 3. This is because the contact 1 is exposed to the outside due to its structure, and prevents heat generation due to a metal short outside.

  The charging circuit 3 controls the constant current supplied from the AC adapter 200 to perform predetermined charging of the battery 6. The transistor switch 4 and the voltage control circuit 5 of the charging circuit 3 are controlled by the control unit 15 to perform on / off control of charging and control of the charging voltage. The battery 6 is a secondary battery. The thermistor 7 is for measuring the temperature of the battery 6. The operation unit 8 is an input means for user operation.

  The transistor switches 9 to 11 are on / off switches for supplying power to the transmission power amplifier 12, the LCD 13, and the white LED 14 that are loads inherent in the mobile terminal 100, and are controlled by the control unit 15. Note that these switches and loads are not limited to these three types, and, for example, a camera unit (not shown) and its intermittent switch may be further provided. The transmission power amplifier 12 is a power amplifier that wirelessly transmits to a base station (not shown) and consumes a large amount of current. The LCD 13 is a display means and still consumes a large amount of current. The white LED 14 is a backlight of the LCD 13 and still consumes a large amount of current.

  The control unit 15 includes a CPU, a ROM, a RAM, an I / O, and the like (not shown), and controls the entire mobile terminal 100. In particular, as a part related to the internal resistance measurement of the battery 6, the detection unit 16 detects the battery voltage 6a and the temperature 7a by an ADC (AD converter). The current storage memory 17 stores a constant current value of the AC adapter 200 in advance. In addition, load currents measured in advance by experiments or the like, that is, load currents of the transmission power amplifier 12, the LCD 13, the white LED 14, and the like are stored. When operating the transmission power amplifier 12 for internal resistance measurement, a frequency that avoids unnecessary high-frequency power emission may be generated by a signal source circuit such as a synthesizer and input to the transmission power amplifier. As a result, although there is a consumption current, there is no possibility that the radio wave is out of synchronization and an extra radio wave is emitted. The battery temperature characteristic memory 18 is a memory that stores in advance the relationship between the internal resistance of the battery and the temperature, and generally stores data obtained in advance from a battery manufacturer or the like.

  The measurement data storage memory 19 is a memory that measures and stores the internal resistance of the battery 6 and the like. The charge counter 20 counts the number of times that the mobile terminal 100 is placed on the AC adapter 200 and charged. The charge counter 20 may be initialized, for example, by a special key operation by a service person when replacing the battery. Further, when the battery has an individual ID number and can be read automatically, the number of times of charging may be initialized by detecting that the individual ID number has been changed by the processing of the control unit 15.

FIG. 2 is a diagram for explaining the internal resistance measurement of the battery of the portable terminal according to each embodiment of the present invention, and shows the voltage and current of the relevant part. In the case of a lithium ion battery, the internal resistance of the battery is, for example, 40 to 60 mΩ in a new state, and is about 100 mΩ when deteriorated. In order to measure the progress of this deterioration, a measurement accuracy of about 10 mΩ step is required.
(A) shows the voltage and current in the “charging and light load” state. If the constant current of the AC adapter 200 is 500 mA, a charging current of 500 mA is supplied. This value is stored in advance in the current storage memory 17 of the control unit 15. The charging current value switches 9 to 11 are all off, and the load current is only Idd supplied to the control unit 15. Therefore, the battery 6 is charged with 500-Idd [mA]. At this time, battery voltage 6a = battery cell voltage V + (500−Idd) × internal resistance 61, and the battery voltage 6a is measured by the control unit 15.

  (B) shows the voltage and current in the “charging and heavy load” state. If the constant current of the AC adapter 200 is 500 mA, a charging current of 500 mA is supplied. Switches 9-11 are all on. The load currents on the switches 9 to 11 side are measured in advance through experiments or the like and stored in the current storage memory 17 of the control unit 15. For example, this current is set to 600 mA. The total load current is 600 + Idd [mA]. Since the charging current is 500 mA, (600 + Idd−500) [mA], which is insufficient for the load current, is discharged from the battery 6. The battery voltage 6a at this time = battery cell voltage V− (600 + Idd−500) × internal resistance 61, and the battery voltage 6a is measured by the control unit 15.

  When comparing (a) (first state) and (b) (second state), the difference between the battery currents flowing through the internal resistance 61 is (500−Idd) + (600 + Idd−500) = 600 [mA]. It is. Moreover, the difference of the battery voltage 6a is also calculated. The internal resistance 61 is calculated by dividing the difference of the battery voltage 6a by the difference of battery current 600 [mA] according to Ohm's law.

  (C) shows the voltage and current in the “charge stopped and light load” state. A state in which charging is temporarily stopped by the control unit 13 while the mobile terminal 100 is being charged may be used, or a normal use state in which the mobile terminal 100 is removed from the AC adapter 200 may be used. The charging current is 0 mA. The switches 9 to 11 are all off, and the load current is only Idd supplied to the control unit 15. Therefore, Idd is discharged from the battery 6.

  (D) shows the voltage and current in the “charge stopped and heavy load” state. The charging current is 0 mA. The switches 9 to 11 are all on, and the load current on the switches 9 to 11 side is 600 mA. The total load current is 600 + Idd [mA]. Accordingly, 600 + Idd [mA] is discharged from the battery 6.

  Comparing (c) (first state) and (d) (second state), the difference between the battery currents flowing through the internal resistor 61 is (600 + Idd) −Idd = 600 [mA]. Similarly, the internal resistance 61 is calculated by dividing the difference in the battery voltage 6a by the difference in battery current 600 [mA].

  Further, when (a) (first state) and (d) (second state) are compared, the difference in battery current flowing through the internal resistor 61 is as large as (500−Idd) + (600 + Idd) = 1100 [mA]. . Moreover, the difference of the battery voltage 6a is also calculated. The internal resistance 61 is calculated by dividing the difference in the battery voltage 6a by the difference in battery current 1100 [mA]. In this case, since the difference in the battery current is large, the difference in the battery voltage 6a is also large, and the accuracy of calculating the internal resistance can be increased.

  In (a), (b), (c), and (d), when Idd supplied to the control unit 15 is smaller than the load current on the switches 9 to 11 side, it may be ignored. Further, when the Idds of (a), (b), (c), and (d) are different from each other, the current values may be applied to the above calculation formula by measuring in advance through experiments or the like. Further, since the load current also changes depending on the value of the battery voltage 6a, it is measured in advance through experiments or the like and stored in the current storage memory 17 as the battery voltage VS load current data, and the battery voltage at the time of measuring the internal resistance. May be applied to the above formula. Further, if the internal resistance is measured when the battery voltage is a predetermined voltage value, the load current can be fixed, so that the accuracy of the resistance value calculation is improved.

  Further, in (a), (b), (c), and (d), there are two charging states: constant current charging or charging stop. For example, charging circuit 3 (FIG. 1) In addition, another charging circuit may be provided in parallel, and the charging state may be in two states: a large current constant current charging or a small current constant current charging. Further, the load state is two ways of turning on or off all of the switches 9 to 11, but the load current may be switched between two ways of large and small. In any case, the internal resistance of the battery can be calculated as long as the charging current and the load current are different.

  Moreover, although the transition between (a)-(b), the transition between (c)-(d), and the transition between (a)-(d) were demonstrated, the transition between (a)-(c), Even in the transition between (b) and (d), 500 mA is obtained as the battery current difference of the current flowing through the battery.

  Next, the required accuracy of the measurement voltage will be described. In the case of a lithium ion battery, the internal resistance of the battery is, for example, 40 to 60 mΩ in a new state, and is about 100 mΩ when deteriorated. In order to measure the progress of this deterioration, a measurement accuracy of about 10 mΩ step is required. Therefore, when the current difference is 600 mA, a voltage detection accuracy of about 600 mA × 10 mΩ = 6 mV step is required. When the current difference is 1100 mA, voltage detection accuracy of about 1100 mA × 10 mΩ = 11 mV step is required.

  FIG. 3 is a circuit diagram of a battery voltage detection unit of the mobile terminal according to each embodiment of the present invention. The detection unit 16 of the control unit 15 includes a resistor 31, a resistor 32, an amplifier 33, resistors 34 to 36, a transistor switch 37, a register 38, an ADC 39, and the like. These components may be distributed and arranged in the control unit 15 and the charging circuit 3.

  The ADC 39 performs battery voltage detection, battery temperature detection (thermistor 7) (not shown), and the like. Here, battery voltage detection will be described. The ADC 39 is an 8-bit (256 steps) AD converter, and 2.6 [V] is supplied to the reference voltage Vref terminal. Therefore, the voltage detection accuracy is 2.6 [V] /256=10.15 [mV] step with respect to the input of (0 to 2.6) [V] of the IN input of the ADC 39.

  The resistors 31 and 32 are for adjusting the detection range of the battery voltage 6 a to (0 to 2.6) [V] of the IN input of the ADC 39. The resistors 31 and 32 are high resistances, and their currents can be ignored. The amplifier 33 and the resistors 34 to 36 are feedback amplifiers. This feedback amplifier is to supply the IN input of the ADC 39 in accordance with the accuracy to be detected of the battery voltage 6a. The gain of the feedback amplifier is (resistor 34 + resistor 35 + resistor 36) / resistor 34 when the transistor switch 37 is off. The gain when the transistor switch 37 is turned on and the resistor 35 is short-circuited is (resistor 34 + resistor 36) / resistor 34.

  By the way, the detection range of the battery voltage 6a needs to detect a voltage range of 0 to 4.3 [V] when performing normal charging control, and 4.3 [V at the point of the battery voltage 6a. ] /256=16.79 [mV] step detection accuracy. Further, when measuring the internal resistance, the accuracy of 6 mV step or 11 mV step is required as described in FIG. Therefore, in order to use one ADC 39 in common, the gain of the feedback amplifier is controlled according to the application.

  If the AD converter has a resolution of 10 bits or 12 bits, gain control is not necessary. Although a 16-bit AD converter has been put into practical use, AD conversion takes time. In a mobile terminal, particularly a mobile phone, an AD converter is integrated in a control LSI together with a CPU and used for communication, so that high speed is also required. Therefore, a sequential conversion type or a fully parallel type (flash type) is used. In the case of the successive approximation type, if the resistance accuracy is low, monotonicity cannot be maintained. However, securing sufficient accuracy in the control LSI increases the cost, so the resolution is limited to about 8 bits to ensure monotonicity. There are many cases. If the all-parallel type (flash type) is multi-bit, the offset accuracy of the comparator is required, and the circuit scale and current consumption are large. Therefore, it is often set to about 8 bits, which is a realistic resolution according to the purpose of the LSI. Therefore, the gain control is an effective method because it can be realized simply by integrating a simple, inexpensive and small-scale circuit.

  FIG. 4 is a diagram for explaining a change in internal resistance accompanying the deterioration of the battery of the mobile terminal according to each embodiment of the present invention. The battery 6 deteriorates due to aging such as repeated charge / discharge cycles, and the internal resistance increases. The battery 6 has individual variations, and the initial value of the internal resistance differs between the battery A and the battery B even when they are new. However, as both batteries are used, the internal resistance increases. This internal resistance is measured at a predetermined frequency at the start of new use and at every charge, and by calculating the amount of change from the initial value, the deterioration of the battery is judged, and the degree of deterioration is determined by the user and Notify service personnel. Since the resistance value is measured and stored without any particular attention to the user, there is no restriction on the use, and if the user wants to know the resistance value, information on the resistance value can be immediately notified. . The ratio between the battery capacity and the battery internal resistance has individual battery variations. Even if the internal resistance value of the battery is measured by the method described above, if the absolute value is notified, information including individual variations on the battery capacity is shown to the user. When manufacturing mobile devices and batteries, information on battery deterioration that is not affected by individual variations is given to users and service personnel by notifying the deterioration value from the initial point when the device manufacturer confirms and guarantees the battery capacity. It becomes possible to provide. The battery internal resistance measurement circuit also varies, and the connection resistance with the battery also varies. For portable devices that are difficult to replace, the deterioration value from the initial point may increase the correlation with the battery capacity. It is effective because it is easy.

  In addition, in order to measure and display the deterioration of the battery resistance value, starting from the time when the serviceman exchanges the battery or confirms the battery capacity value and the resistance value, the number of times of charging is reset as described in claim 6. It is convenient that the initial resistance value can be set.

  However, the internal resistance of the battery varies greatly depending on factors other than deterioration depending on the measurement conditions, and it is necessary to accurately detect the change in internal resistance accompanying the original deterioration shown in FIG. Next, a case where the internal resistance is different due to factors other than deterioration will be described.

FIG. 5 is a diagram for explaining the variation factors other than the deterioration of the internal resistance of the lithium ion battery of the portable terminal according to each embodiment of the present invention.
(A) shows the general relationship between internal resistance and SOC (charged state representing full charge, complete discharge, etc.) and the general relationship between battery voltage and SOC. The internal resistance also changes depending on the SOC state. Regarding the SOC on the horizontal axis, 0 [%] represents a fully discharged state and 100 [%] represents a fully charged state. The internal resistance [mΩ] indicated by a thick solid line is large when the SOC is small, decreases as the SOC increases, and becomes substantially flat at N or more near the center of the SOC. Therefore, in order to accurately measure the internal resistance, it is desirable to measure at a portion where the resistance value is flat. However, since it takes time to check the charge / discharge amount in order to detect this SOC, the SOC state is grasped by the battery voltage.

  Next, a general relationship between the battery voltage and the SOC will be described. The change in battery voltage is indicated by a dotted line. The battery voltage is small when the SOC is small, the voltage is substantially flat near the center of the SOC, and the voltage is steep when the SOC is near full charge. In order to recognize a portion having a flat resistance value by checking the voltage, it is difficult to recognize a portion having a flat resistance value due to voltage variation in the voltage check of the portion having a substantially flat voltage. Therefore, if you check whether the voltage value is in the voltage range near full charge and measure the resistance value at that voltage part, you can accurately measure the value near the full charge in the flat part of resistance. Can do.

  In addition, as a way of using a mobile terminal by a user, an AC adapter is often placed on the AC adapter instead of a stand for the mobile terminal. In that case, the battery is often almost fully charged, that is, the battery voltage is almost high. Therefore, if the voltage value is close to a full charge, for example, if the battery voltage is 4.10 [V] or the battery is fully charged, and the resistance value is measured at that voltage portion, the measurement is performed. Can increase the frequency.

  As described above, it is important to measure the resistance value at an appropriate battery voltage (SOC). A description will be given by taking as an example a lithium ion battery in which lithium cobaltate is a positive electrode material and graphite is a negative electrode material, with 20V being fully charged (SOC; 100%). For example, in a design in which the battery voltage (dotted line) is measured at 3.6 V or less, there is a high possibility that measurement is performed in a state where the battery resistance value indicated by a thick solid line changes sharply, and a resistance value having a strong correlation with the battery capacity is obtained. It is unsuitable for the purposes of this patent because it is concerned that it has not been measured. For example, in a design that measures at about 3.8V, if the user is in the habit of performing "high frequency charging" or "low discharge depth charging" that charges every call, the resistance value can be measured because it can always be 4.00V or higher. There are concerns that there are few opportunities to do so.

  For example, in the design that measures at 4.20V, the charging voltage that drops to about 4.10 to 4.17V at the same time that the battery voltage is released even when the charging voltage is 4.20V is often used. If the charging is stopped before, the battery voltage is less than 4.20 V, so that the method is limited to a method of measuring the internal resistance of the battery during charging as in Example 1 described later. If the measurement is carried out at about 4.00V to 4.10V, the battery voltage will elapse for each charge unless charging is stopped in the middle of the charging. is there. Hereinafter, in the case of a lithium ion battery in which 4.20V is fully charged (SOC; 100%), the predetermined battery voltage generally indicates a battery voltage close to full charge in this range.

  In general, the load current of the transmission power amplifier 12, the LCD 13, the white LED 14, etc., increases when the battery voltage is high. In general, the load current of a DCDC converter (not shown) decreases when the battery voltage is high. In many cases, these current consumptions do not change linearly with respect to the battery voltage and have a plurality of inflection points. Therefore, fixing the battery voltage when measuring the internal resistance is desirable in order to increase the measurement accuracy with simple measurement.

  When measuring the resistance value around 4.00V, if the battery voltage is already 4.17V at the start of charging, the internal resistance value at the battery voltage of 4.00V and the internal voltage at the battery voltage of 4.17V Since the difference in resistance value is slight, it is safe to substitute the measured value at 4.17V. In particularly rigorous measurement, the resistance value of a lithium ion battery close to a full charge such as 4.17 V is larger than 4.00 V. Therefore, when calculating an average value or a moving average value, it can be excluded or weighted. Treatment such as lightening may be performed.

(B) shows the relationship between the internal resistance and temperature of a lithium ion battery. The internal resistance also changes depending on the battery temperature. The internal resistance shows the minimum value above room temperature and the value is stable. It rises as it gets colder. Therefore, a resistance value measured at room temperature or higher, for example, 15 degrees Celsius or higher, may be used as a determined value. Alternatively, the relationship between the internal resistance and the temperature is stored in the battery temperature characteristic memory 18 (FIG. 1) as a correction coefficient, and for example, the internal resistance value of 25 degrees Celsius is set as a reference correction coefficient “1” and the other temperature. The resistance value measured in (5) may be corrected to an internal resistance value converted to 25 degrees Celsius and used as a determined value. For example, if the temperature when the resistance value is measured is 5 degrees Celsius, the resistance value at that time is divided by the correction coefficient 1.25 to obtain a resistance value converted to 25 degrees Celsius. This characteristic is general representative data of a lithium ion battery, and can be almost applied although there are individual differences of the battery.

  FIG. 6 is a flowchart of battery internal resistance measurement of the control unit of the mobile terminal according to the first embodiment of the present invention. In the first embodiment, during charging, charging is temporarily stopped and a large current load is turned on. During charging, when charging is temporarily stopped and large current load is turned on, a battery voltage difference and a current difference of 1100 mA Calculate the resistance. That is, the internal resistance is calculated by the transition from (a) to (d) in FIG.

  FIG. 7 is a diagram for explaining the measurement data storage memory of the mobile terminal according to each embodiment of the present invention. In the measurement data storage memory 19, the reference numeral 19a column indicates the number of times of charging, the reference numeral 19b column indicates the measurement temperature, the reference numeral 19c column indicates the battery voltage before the change, the reference numeral 19d column indicates the battery voltage after the change, the reference numeral 19e column indicates the calculated resistance value, The reference numeral 19f column stores the corrected resistance value, and the reference numeral 19g column stores the resistance value change amount.

  The operation will be described with reference to FIGS. The control unit 15 measures the battery internal resistance during the battery charging process. When entering the charging process (step S1), the control unit 15 first increments the charging number counter 20 by 1 (step S2). Then, the gain of the ADC input is lowered, that is, the gain of the amplifier 33 (FIG. 3) is lowered (step S3). This is because, as described with reference to FIG. 3, it is necessary to measure and manage the range of 0 to 4.3 [V] as the measurement range of the battery voltage in the charging process. Then, while performing the constant current charging process (step S4), it is checked whether the battery voltage 6a is at a voltage near full charge (step S5).

  If this is a voltage near full charge, it is checked whether an application other than the charging process, for example, a communication process or an LCD display process is being executed (step S6). This is to check whether charging is performed while executing the original function of the mobile terminal 100, that is, whether it is so-called “while charging”. If “while charging”, the voltage measurement for calculating the internal resistance (step S10) is passed and the charging process is continued (step S50). Even if “while charging”, depending on the type of application being executed, if the application may be stopped, it may be stopped and the measurement for calculating the internal resistance may be entered (step S10). Good.

  If it is not “while charging” in step S6, voltage measurement for calculating internal resistance (step S10) is started. First, the transistor switches 9 to 11 are turned off, and the power supply to the transmission power amplifier 12, the LCD 13, and the white LED 14 as loads is turned off (step S11). Next, the temperature is measured (step S12). This is performed by detecting the voltage at the temperature 7a (FIG. 1) by switching the input to the detection unit 16 to the thermistor 7 side with a changeover switch (not shown). Then, the measured temperature is recorded in the “measurement temperature” column (reference numeral 19 b) in the “charge count” column of the reference numeral 19 a of the measurement data storage memory 19 corresponding to the current value of the charge counter 20 (step S 12). ).

  Next, the input to the detection unit 16 is switched again to the battery voltage 6a side, and further, in order to increase the accuracy of voltage detection, the gain of the ADC input is increased, that is, the gain of the amplifier 33 is increased (step S13). This is because, as described with reference to FIG. 3, it is necessary to increase the detection accuracy at the time of measuring internal resistance rather than the detection accuracy at the time of normal charge control.

  Then, the battery voltage 6a during constant current charging is accurately measured (step S14). This state corresponds to (a) of FIG. Then, this battery voltage 6a is recorded in the “battery voltage before transition” column (reference numeral 19c) in the same “number of times of charging” column of the measurement data storage memory 19 (step S14). Next, the charging is temporarily stopped, and a predetermined time, for example, 0.01 seconds to 10 seconds is waited (step S15). This is because of waiting for stabilization of battery characteristics due to the stop of charging.

  Next, the transistor switches 9 to 11 are turned on to turn on the power supply to the transmission power amplifier 12, the LCD 13, and the white LED 14 that are loads, and the battery voltage 6a is measured (step S16). This state corresponds to (d) of FIG. Then, this battery voltage 6a is recorded in the “battery voltage after transition” column (reference numeral 19d) in the same “number of times of charging” column of the measurement data storage memory 19 (step S16).

Then, the transistor switches 9 to 11 are turned off, and the power supply to the load is turned off (step S17). Then, constant current charging is resumed (step S18).
Although the data for calculating the internal resistance are prepared as described above, steps S12 to S18 may be repeated a plurality of times to measure a plurality of times to obtain an average value. Even if it is repeated several times, the processing time is short. When the voltage measurement for calculating the internal resistance is completed, the ADC input gain is lowered to prepare for the normal charging process (step S19), and the charging process is continued (step S50).

  Next, the internal resistance calculation process (step S100) will be described. This process may be performed during the charging process, or may be performed at any timing other than the charging process, for example, in a standby state after the mobile terminal 100 is detached from the AC adapter. In the measurement data storage memory 19, voltage and temperature data measured in steps S12 to S18 of the charging process are recorded.

  The control unit 15 reads the measurement data storage memory 19. The voltage difference between the “battery voltage before transition” V1P [V] and the “battery voltage after transition” V1S [V] in the measurement data storage memory 19 is calculated for the first charge count data. The resistance value 60.5 mΩ obtained by dividing this voltage difference by the current difference 1100 mA preliminarily stored in the current storage memory 17 is stored in the “calculated resistance value” column of the symbol 19e column of the measurement data storage memory 19 (step S101). ).

  Next, 60.5 mΩ / 1 based on the “measurement temperature” 5 degrees Celsius of the measurement data storage memory 19 and the correction coefficient 1.25 (FIG. 5B) of 5 degrees Celsius of the battery temperature characteristic memory 18. The calculation of .25 = 48.4 mΩ is performed, and 48.4 mΩ is stored in the “corrected resistance value” column of reference numeral 19 f of the measurement data storage memory 19 (step S 102). If the number of times of charging is the first time, zero is recorded in the “resistance change” column of the reference numeral 19 g of the measurement data storage memory 19. This is the future standard as the initial value.

  The second and third charge times of the measurement data storage memory 19 are examples when the measurement temperature is 70 degrees Celsius and minus 9 degrees Celsius. In this case, the calculation of the resistance value is not performed because it is out of the normal use range of the battery, or the result is recorded and remains as a reference value. The same applies to the case where this temperature is not described in the battery temperature characteristic memory 18.

  For the fourth charge, the same process is performed, and “calculated resistance value” 53.4 mΩ and “corrected resistance value” 48.5 mΩ are recorded. Then, a difference of 0.1 mΩ between the “corrected resistance value” 48.4 mΩ of the first charge number of times as a reference and the current “corrected resistance value” 48.5 mΩ is calculated, and the “resistance value change” column is calculated. 0.1 mΩ is recorded (step S103).

  The reference initial value is not only the “corrected resistance value” of 48.4 mΩ for the first charge, but also the average of the “corrected resistance values” for a plurality of early charge times. The initial value of the “resistance value” may be used. If there is singular data, an average value may be taken and an initial value of “corrected resistance value” may be used.

  For each number of times of charging, calculation of “corrected resistance value” and calculation of the resistance value change amount, the resistance value change amount of 30.2 mΩ at the 100th charge time, the resistance value change amount of 50.7 mΩ at the 300th charge time, The resistance value change amount 110 mΩ is recorded at the 500th charge.

If the temperature correction is not performed, the internal resistance is almost constant if the temperature is not less than room temperature, for example, 15 degrees to 50 degrees Celsius. Therefore, it is determined whether the temperature is in the range above room temperature. You may make it validate only the internal resistance value calculated when it exists in the above range.
Further, although the measurement data storage memory 19 stores the voltage [V] and the resistance value [mΩ], the output binary data of the ADC 39 of the detection unit 16 may be recorded as it is. In many cases, since the user wants to know the amount of deterioration of the battery, the data notified to the user may be the output value of the ADC 39 in decimal, octal or hexadecimal instead of the resistance value. Displaying the criterion value for the degree of battery deterioration together with these deterioration display values is preferable because it increases convenience for the user.

FIG. 8 is a flowchart of battery deterioration notification of the control unit of the mobile terminal according to each embodiment of the present invention.
FIG. 9 is a diagram for explaining a display screen of battery deterioration notification of the control unit of the mobile terminal according to each embodiment of the present invention, where (a) is a resistance value change amount display, and (b) is a battery voltage difference ( It is an example of a change amount display of (ADC value).
The operation will be described with reference to FIGS. When the user of the portable terminal 100 performs a battery deterioration notification operation (YES in step S201), the control unit 15 reads the “resistance value change amount” of the latest charge count from the measurement data storage memory 19 (step S202). . For example, if the current number of times of charging is the 100th, the current “resistance value change amount” is 30.2 mΩ. Then, the current “resistance value change amount” of 30.2 mΩ is displayed in the “change amount of internal resistance value with respect to initial value” column on the display screen. In addition, a word indicating “resistance value change amount” VS battery deterioration is also displayed in the “battery deterioration guideline display” field of the display screen (step S203).

  This “resistance value change amount” VS battery deterioration is classified according to a resistance value change amount obtained from a battery manufacturer or the like and battery capacity data in advance. As a result, the “resistance change” of 0 to 40 mΩ is the same as a new battery, the “resistance change” of 40 to 60 mΩ starts to deteriorate the capacity of the battery, and the “resistance change” of 100 mΩ or more deteriorates the battery. It is recommended to replace the battery.

  The user sees this and knows that the battery is the same as a new battery if the “resistance change amount” is 30.2 mΩ. If the current number of times of charging is the latest 300th, “resistance value change amount” is displayed as 50.7 mΩ, and it is known that the battery capacity has started to deteriorate. If the current number of times of charging is the latest, the “resistance value change amount” 110 mΩ is displayed, and it is known that the battery needs to be replaced. In addition, not only this display form but the display of only the language showing battery deterioration may be sufficient.

  FIG. 9B shows a change in “battery voltage difference” in the expression “battery voltage difference / battery current difference (fixed value) = battery internal resistance value” that is not a resistance value display but a basis for calculating the resistance value. The quantity may be displayed with the ADC value as it is. For example, the initial value may be multiplied by a constant so as to be 100, for example, and processing may be added so that the user can easily understand. Since the battery current difference is a fixed value, the ADC value of “battery voltage difference” equivalently means internal resistance. Moreover, you may display the frequency | count of charge, the high temperature encounter frequency, etc. as other information.

  8 and 9 are notification examples for the user of the mobile terminal 100, but when the special key operation is performed for the service person, all the contents of the measurement data storage memory 19 (FIG. 7) are It may be displayed or output via an external interface (not shown). Thereby, the service person can know the details of the battery deterioration, the operating temperature environment of the user's portable terminal, the propensity of the charging operation, and the like that cause the battery deterioration. Further, the date and time of charging may be recorded in the measurement data storage memory 19 together with the number of times of charging.

According to the first embodiment, since the voltage measurement for calculating the internal resistance is performed when the battery voltage is in the vicinity of the full charge, the internal resistance is not affected by the SOC and is always fully charged in the usage in which the user frequently charges. Even when the battery voltage is always high, the predetermined battery voltage value for measuring the internal resistance of the battery is set to a voltage close to full charge, so that the timing of measuring the internal resistance is not lost. In addition, since the measurement for calculating the internal resistance is performed during charging, it does not affect the normal use of the mobile terminal. Also, the detection accuracy can be increased by a large current difference between the charging current and the discharging current. Further, since the ADC input gain is switched between normal charging and internal resistance measurement, the accuracy for measuring internal resistance can be sufficiently increased. In addition, since the discharge current uses a load or a transistor switch that is originally provided in the mobile terminal, it is not necessary to separately provide a discharge resistor or switch only for measuring the internal resistance.
In addition, the influence of SOC and temperature, which is a variation factor other than internal resistance deterioration, is removed, and accurate internal resistance measurement for determining internal resistance deterioration becomes possible.

  FIG. 10 is a flowchart of the battery internal resistance measurement of the control unit of the mobile terminal according to the second embodiment of the present invention. In the second embodiment, during charging, charging is temporarily stopped, a large current load is turned on / off, and the internal resistance is calculated based on the battery voltage difference and the current difference 600 mA when the large current load is turned on / off. That is, the charging current is not considered. That is, the internal resistance is calculated by the transition from (c) to (d) in FIG. 7, 8, and 9 are the same as those in the first embodiment, and detailed description thereof is omitted.

  In FIG. 10, the same parts as those in FIG. 6 of the first embodiment are denoted by the same step numbers, and the differences will be mainly described. The control unit 15 enters the charging process (step S1), and enters the voltage measurement for calculating the internal resistance (step S20) if the battery voltage 6a is near the full charge (YES in step S4). First, the power supply to the load is turned off (step S21), the temperature is measured (step S22), the ADC input gain is set high (step S23), charging is temporarily stopped and a predetermined time is waited (step S24).

  Next, the power supply to the load is turned off, and the battery voltage 6a is measured and recorded in the “battery voltage before transition” column (reference numeral 19c) of the measurement data storage memory 19 (step S25). This state corresponds to (c) of FIG. Next, the power supply to the load is turned on, the battery voltage 6a is measured, and recorded in the “battery voltage after transition” column (reference numeral 19d) of the measurement data storage memory 19 (step S26). This state corresponds to (d) of FIG.

  Although the data for calculating the internal resistance is prepared as described above, steps S25 and S26 may be repeated a plurality of times to obtain an average value for a plurality of times. Further, during this step, temperature measurement may be included and measurement may be performed a plurality of times. Even if it is repeated a plurality of times, the processing time is only several tens [mS]. When the voltage measurement for calculating the internal resistance is completed, the ADC input gain is lowered to prepare for the normal charging process (step S28), and the charging process is continued (step S50).

  The internal resistance calculation process (corresponding to step S100 in FIG. 6) is different in that the internal resistance is calculated not with the current difference of 1100 mA (Example 1) but with the current difference of 600 mA, but the rest is the same and the description is omitted. .

According to the second embodiment, since the voltage measurement for calculating the internal resistance is performed when the battery voltage is in the vicinity of the full charge, the internal resistance is not affected by the SOC and is always fully charged in the usage that the user frequently charges. Even when the battery voltage is constantly high, the timing for calculating the internal resistance is not missed. In addition, since the measurement for calculating the internal resistance is performed during charging, it does not affect the normal use of the mobile terminal. Further, since the ADC input gain is switched between normal charging and internal resistance measurement, the accuracy for measuring the internal resistance can be obtained. In addition, since the discharge current uses a load or transistor switch that is originally provided in the mobile terminal, it is not necessary to separately provide a discharge resistor or switch only for calculating the internal resistance.
In addition, the influence of SOC and temperature, which is a variation factor other than internal resistance deterioration, is removed, and accurate internal resistance measurement for determining internal resistance deterioration becomes possible.

  FIG. 11 is a flowchart of battery internal resistance measurement of the control unit of the mobile terminal according to the third embodiment of the present invention. In the third embodiment, a large current load is turned on / off without stopping charging during charging, and the internal resistance is calculated from the battery voltage difference and the current difference 600 mA when the large current load is turned on / off. That is, the internal resistance is calculated by the transition from (a) to (b) in FIG. 7, 8, and 9 are the same as those in the first embodiment, and detailed description thereof is omitted.

  In FIG. 11, the same parts as those in FIG. 6 of the first embodiment are denoted by the same step numbers, and the differences will be mainly described. The difference is that the charging temporary stop process (step S15) and the constant current charging restart (step S18) in FIG. 6 (Example 1) are deleted. This is not necessary because the third embodiment performs charging without stopping during charging. The other parts are the same, and the battery voltage and temperature when the load is turned on / off are measured and recorded in the measurement data storage memory 19.

  The internal resistance calculation process (corresponding to step S100 in FIG. 6) is different in that the internal resistance is calculated not with the current difference of 1100 mA (Example 1) but with the current difference of 600 mA, but the rest is the same and the description is omitted. .

According to the third embodiment, since the voltage measurement for calculating the internal resistance is performed when the battery voltage is in the vicinity of the full charge, the internal resistance is not affected by the SOC and is always fully charged in the usage in which the user frequently charges. Even when the battery voltage is constantly high, the timing for calculating the internal resistance is not missed. In addition, since the measurement for calculating the internal resistance is performed during charging, it does not affect the normal use of the mobile terminal. In particular, since charging is not temporarily stopped, the influence on charging control can be completely eliminated. Further, since the ADC input gain is switched between normal charging and internal resistance measurement, the accuracy for measuring the internal resistance can be obtained. In addition, since the discharge current uses a load or transistor switch that is originally provided in the mobile terminal, it is not necessary to separately provide a discharge resistor or switch only for calculating the internal resistance.
In addition, the influence of SOC and temperature, which is a variation factor other than internal resistance deterioration, is removed, and accurate internal resistance measurement for determining internal resistance deterioration becomes possible.
Note that the mobile terminal of each embodiment can be applied to a mobile phone, a PDA, a camera, a notebook computer, and the like.

The block diagram of the relevant part of the portable terminal which concerns on each Example of this invention. The figure explaining the internal resistance measurement of the battery of the portable terminal which concerns on each Example of this invention. The circuit diagram of the detection part of the battery voltage of the portable terminal which concerns on each Example of this invention. The figure explaining the change of internal resistance accompanying deterioration of the battery of the portable terminal which concerns on each Example of this invention. The figure explaining the dispersion | variation factors other than deterioration of the internal resistance of the lithium ion battery of the portable terminal which concerns on each Example of this invention. The flowchart of the battery internal resistance measurement of the control part of the portable terminal which concerns on Example 1 of this invention. The figure explaining the measurement data storage memory of the portable terminal which concerns on each Example of this invention. The flowchart of the battery deterioration alerting | reporting of the control part of the portable terminal which concerns on each Example of this invention. The figure explaining the display screen of the battery degradation alerting | reporting of the control part of the portable terminal which concerns on each Example of this invention. The flowchart of the battery internal resistance measurement of the control part of the portable terminal which concerns on Example 2 of this invention. The flowchart of the battery internal resistance measurement of the control part of the portable terminal which concerns on Example 3 of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Contact 2 Diode 3 Charging circuit 4 Transistor switch 5 Voltage control circuit 6 Battery 61 Internal resistance 7 Thermistor 8 Operation part 9, 10, 11 Transistor switch 12 Transmission power amplifier 13 LCD
14 White LED
15 Control Unit 16 Detection Unit 17 Current Storage Memory 18 Battery Temperature Characteristic Memory 19 Measurement Data Storage Memory 20 Charge Count Counter 31, 32 Resistor 33 Amplifier 34, 35, 36 Resistor 37 Transistor Switch 38 Register 39 ADC
100 Mobile terminal 200 AC adapter

Claims (6)

Rechargeable batteries,
A load unit supplied with current from the battery;
When the battery voltage is a voltage in the vicinity of a predetermined full charge, switching between a first state in which a first load current is passed through the load section and a second state in which a second load current greater than the first load current is passed, The battery voltage difference between the first state and the second state is calculated by measuring the battery voltage between the first state and the second state, or the battery voltage difference is divided by the battery current difference between the first state and the second state to determine the internal resistance of the battery. And further calculating the amount of change in the battery voltage difference or the amount of change in the internal resistance, and reporting information on the battery characteristics corresponding to the amount of change in the battery voltage difference or the amount of change in the internal resistance. A portable terminal comprising a control means. A mobile terminal that receives charging power from outside,
Rechargeable batteries,
A load unit supplied with current from the battery;
A first state in which a first load current flows through the load unit during constant current charging of the first charging current; and the load during constant current charging of a second charging current less than the first charging current or during constant current charging stop. Switching a second state in which a second load current greater than the first load current is passed through the unit, measuring a battery voltage between the first state and the second state, and calculating a difference between the battery voltages, or the battery voltage Dividing the difference by the battery current difference between the first state and the second state to calculate the internal resistance of the battery, further calculating the change amount of the battery voltage difference or the change amount of the internal resistance, and the battery voltage A portable terminal comprising: control means for notifying information relating to the characteristics of the battery corresponding to a change amount of the difference or a change amount of the internal resistance. A mobile terminal that receives charging power from outside,
Rechargeable batteries,
A load unit supplied with current from the battery;
Switching between a first state in which a first load current flows through the load unit during constant current charging and a second state in which a second load current greater than the first load current flows through the load unit during constant current charging; The battery voltage difference between the first state and the second state is calculated by calculating the battery voltage between the first state and the second state, or the battery resistance difference is divided by the battery current difference between the first state and the second state. Further, the amount of change in the battery voltage difference or the amount of change in the internal resistance is calculated, and information on the battery characteristics corresponding to the amount of change in the battery voltage difference or the amount of change in the internal resistance is reported. And a control means. A mobile terminal that receives charging power from outside,
Rechargeable batteries,
A load unit supplied with current from the battery;
During the constant current charging, charging is temporarily stopped, and a first state in which a first load current flows through the load unit and a second state in which a second load current greater than the first load current flows through the load unit are switched, The battery voltage difference between the first state and the second state is calculated by calculating the battery voltage between the first state and the second state, or the battery resistance difference is divided by the battery current difference between the first state and the second state. Further, the amount of change in the battery voltage difference or the amount of change in the internal resistance is calculated, and information on the battery characteristics corresponding to the amount of change in the battery voltage difference or the amount of change in the internal resistance is reported. And a control means.   5. The control unit according to claim 1, wherein when the battery voltage in the first state and the second state is measured, the control means increases the measurement accuracy as compared with the battery voltage measurement in other cases. The mobile terminal according to item 1. Furthermore,
Charging number counting means for counting the number of times the battery is charged;
Resetting means for resetting the charging number counting means,
The control means includes
The change amount of the battery voltage difference or the change amount of the internal resistance is calculated based on the battery voltage difference or the internal resistance calculated when the number of times of charging is initial. The portable terminal according to any one of claims 1 to 4.

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