JP4687329B2 - Information terminal and battery remaining charge calculation method - Google Patents

Description

  The present invention relates to an information terminal and a battery remaining amount calculation method.

  Examples of small information terminals using a battery include a digital camera, a portable video playback device, and a portable still image playback device. Recently, devices such as hard disk drives that have a large effect on load fluctuations have been installed in such small information terminals. For this reason, the load on the battery varies greatly depending on the driving state of such devices. It is supposed to be.

Accurate display of the remaining battery level is very important for the user as a means of estimating how much the information terminal can be used. As a method for detecting the remaining battery level, a method for measuring the charge / discharge current of the battery (for example, see JP-A-5-66251 and JP-A-7-260839), and a method for measuring the battery voltage (for example, JP-A-6-51876 and JP-A-11-55372).
Japanese Patent Laid-Open No. 5-66251 JP 7-260839 A JP-A-6-51876 Japanese Patent Laid-Open No. 11-55372

  However, the method for measuring the charge / discharge current requires a current measurement unit, a storage unit for storing the measured current data, and a CPU for calculating the remaining battery capacity from the data, which hinders downsizing and cost reduction. To do. For this reason, it is not suitable for a small information terminal.

  On the other hand, in the method of measuring the battery voltage, the external voltage changes due to the internal impedance when the load fluctuates as the characteristics of the battery. For this reason, an information terminal incorporating a device with a large load fluctuation cannot accurately detect the remaining battery level. For example, since the load becomes large when the information terminal is turned on, the remaining amount of battery is displayed low. After that, when the information terminal is stabilized, the load is reduced and the remaining amount of battery increases. Such a display change of the remaining battery level is confusing for the user and very inconvenient.

  As a method of correcting the influence of the load fluctuation, there is a method of measuring and correcting the current flowing through the load, as disclosed in Japanese Patent Laid-Open No. 5-66251. However, additional parts such as a current detection unit and a comparison voltage correction unit are required, resulting in an increase in cost. In addition, in an information terminal that must be downsized, it is desirable to avoid adding new components for the purpose of detecting the remaining battery level as much as possible. In addition, inserting a current detection resistor in the power supply line causes a voltage drop and wasteful power consumption, and is not suitable for information terminals that want to extend the battery driving time as much as possible. .

  Therefore, the present invention has been made in view of the above problems, and an object of the present invention is to reduce the size of an information terminal while enabling display of a remaining battery level corrected for the influence of load fluctuations.

In order to solve the above problems, an information terminal according to the present invention provides:
An information terminal driven by a battery,
Voltage detecting means for detecting a battery voltage which is a voltage of the battery;
An identification information acquiring means for acquiring identification information for identifying a model of a hard disk drive that is driven by power supplied from the battery;
Hard disk load holding means for holding parameters of the load on the battery for multiple types of hard disk drives;
Based on the identification information of the hard disk drive acquired by the identification information acquisition means, the hard disk load holding means is searched, and a load parameter acquisition means for acquiring a load parameter for the battery of the hard disk drive;
A load calculating means for calculating a load on the battery of the hard disk drive using a load parameter acquired by the load parameter acquiring means;
Battery remaining amount calculating means for calculating a battery remaining amount based on the battery voltage, and calculating a battery remaining amount corrected based on the load calculated by the load calculating means; ,
It is characterized by providing.

In this case, the hard disk drive has a plurality of states with different loads on the battery,
The hard disk load holding means may hold the load value for the battery as a parameter for each state of the hard disk drive.

Furthermore, for some states of the hard disk drive, the transition time for transitioning from that state to another state is predetermined,
The hard disk load holding means may hold the transition time as a parameter.

  The load calculating means may count the load based on the state transition of the hard disk drive during a predetermined period, and calculate the load of the hard disk drive based on the counted load.

In addition, it further includes a drive unit other than the hard disk drive, which is driven by power supplied from the battery,
The load calculating means may calculate a load on the battery including the hard disk drive and the drive unit.

Moreover, it further comprises a temperature detection means for detecting a battery temperature which is the temperature of the battery,
The battery remaining amount calculating unit may calculate a remaining battery level corrected based on the battery temperature detected by the temperature detecting unit.

  Moreover, you may make it further provide the display means which displays the said battery remaining charge calculated by the said battery remaining charge calculation means.

  The hard disk drive may be detachably connected to the information terminal.

The battery remaining amount calculation method according to the present invention is:
A battery remaining amount calculation method in an information terminal driven by a battery,
Detecting a battery voltage which is a voltage of the battery;
Obtaining identification information for identifying a model of a hard disk drive that is driven by receiving power from the battery; and
Based on the acquired identification information of the hard disk drive, searching for a hard disk load holding unit that holds a load parameter for the battery for a plurality of types of hard disk drives, and acquiring a load parameter for the battery of the hard disk drive;
Calculating the load on the battery of the hard disk drive using the acquired load parameter;
In calculating the battery remaining amount based on the battery voltage, calculating a battery remaining amount corrected based on the calculated load;
It is characterized by providing.

The program according to the present invention is:
A program for causing an information terminal driven by a battery to calculate the remaining battery charge,
Detecting a battery voltage which is a voltage of the battery;
Obtaining identification information for identifying a model of a hard disk drive that is driven by receiving power from the battery; and
Based on the acquired identification information of the hard disk drive, searching for a hard disk load holding unit that holds a load parameter for a battery for a plurality of types of hard disk drives, and acquiring a load parameter for the battery of the hard disk drive;
Calculating the load on the battery of the hard disk drive using the acquired load parameter;
In calculating the battery remaining amount based on the battery voltage, calculating a battery remaining amount corrected based on the calculated load;
Is executed by an information terminal.

The recording medium according to the present invention is
A recording medium recorded with a program for causing an information terminal driven by a battery to calculate the remaining battery charge,
Detecting a battery voltage which is a voltage of the battery;
Obtaining identification information for identifying a model of a hard disk drive that is driven by receiving power from the battery; and
Based on the acquired identification information of the hard disk drive, searching for a hard disk load holding unit that holds a load parameter for the battery for a plurality of types of hard disk drives, and acquiring a load parameter for the battery of the hard disk drive;
Calculating the load on the battery of the hard disk drive using the acquired load parameter;
In calculating the battery remaining amount based on the battery voltage, calculating a battery remaining amount corrected based on the calculated load;
Is recorded on the information terminal.

  In this embodiment, in a small information terminal having a detachable hard disk drive as a drive unit having a large load fluctuation, the load of the hard disk drive is calculated in calculating the remaining battery level, and the influence of the fluctuation of the hard disk drive load is calculated. In addition, when calculating the load of the hard disk drive, the remaining battery level can be calculated with high accuracy by calculating using a parameter depending on the model of the hard disk drive. More details will be described below.

  FIG. 1 is a block diagram illustrating an example of the internal configuration of the information terminal according to the present embodiment. As shown in FIG. 1, the information terminal includes a CPU 10, an LCD backlight 12, a display unit 18, and another load 16. In addition, an external hard disk drive EXHDD is detachably connected to the information terminal via a connection interface. Therefore, the user can prepare a plurality of different types of hard disk drives EXHDD and use them by arbitrarily replacing and connecting to this information terminal.

  In addition, the information terminal includes a battery 20, and the power supplied from the battery 20 is connected to the CPU 10, the LCD backlight 12, the display unit 18, and other loads 16 via the DC / DC converter 22. Has been supplied to. The power supplied from the battery 20 is also supplied to the hard disk drive EXHDD.

  That is, the voltage stabilized or transformed by the DC / DC converter 22 is supplied to the drive units as these loads. The other loads 16 comprehensively indicate various loads that are not individually illustrated.

  The CPU 10 includes an AD converter 30, a RAM (Random Access Memory) 32, and a ROM (Read Only Memory) 34 therein. The CPU 10 constitutes a central processing unit in the present embodiment.

  The information terminal also includes a voltage detection circuit 40. The voltage detection circuit 40 detects a voltage between the battery 20 and the DC / DC converter 22 and supplies the detected value as a battery voltage to the AD converter 30 of the CPU 10. The CPU 10 converts the detected value into digital data and imports it into the CPU 10.

  The battery 20 includes a temperature detection circuit 42. The temperature detection circuit 42 is composed of, for example, a thermistor, and an analog signal output from the temperature detection circuit 42 is input to the AD converter 30 and taken into the CPU 10 as digital data.

  Next, based on FIG. 2, the principle of the battery remaining amount calculation according to the present embodiment will be described. FIG. 2 is a graph showing the relationship between the battery voltage and the remaining battery level when the load is large (for example, 1200 mA) and when the load is small (for example, 400 mA). As can be seen from this graph, even if the measured battery voltage is the same value, the actual remaining battery level differs between when the load is large and when the load is small. Therefore, in this embodiment, the relationship between the battery voltage and the remaining battery level is prepared in advance in a table for some typical load values. And when calculating the remaining battery level, the load of the information terminal is calculated, and when determining the remaining battery level based on the measured battery voltage, a correction according to the load is performed to obtain a more accurate The battery level can be calculated.

  Further, it is assumed that the hard disk drive EXHDD attached to the information terminal according to the present embodiment has five operation states as shown in FIGS. That is, the hard disk drive EXHDD has an access state (hereinafter referred to as AC load) in which the hard disk drive EXHDD is actually accessed, a performance idle state (hereinafter referred to as PI load) for a predetermined period after the access is completed, and a performance idle state. An active idle state (hereinafter referred to as an AI load) for a predetermined period after the end, a low power idle state (hereinafter referred to as an LPI load) after the end of the active idle state, and a standby state (hereinafter referred to as the following) from the CPU 10 (Referred to as ST load).

  Here, the current consumption in the access state, the performance idle state, the active idle state, the low power idle state, and the standby state differs depending on the model of the hard disk drive EXHDD, and until the transition from the performance idle state to the active idle state. (Time during which the performance idle state is maintained) and time until the transition from the active idle state to the low power idle state (time during which the active idle state is maintained) are also different for each type of hard disk drive EXHDD.

  FIG. 5 is a diagram showing an example of the configuration of the hard disk load table TB20 stored in the ROM 34 of this information device. As shown in FIG. 5, the hard disk load table TB20 holds a parameter representing the load on the battery 20 for each hard disk drive model.

  The hard disk load table TB20 has a model name as identification information for identifying the model of the hard disk drive EXHDD. This model name is identification information that can be acquired from the hard disk drive EXHDD when the information terminal starts up the hard disk drive EXHDD.

  In the present embodiment, the first alphabet represents the manufacturer name of the hard disk drive EXHDD, and the numerical value following this represents the model number. Here, it is assumed that the model name “AAA — 1111111” is attached to the information terminal.

  As can be seen from FIGS. 3 to 5, the hard disk drive EXHDD with the model name “AAA — 1111111” has a current consumption of 600 mA in the access state, a current consumption of 400 mA in the performance idle state, and a current consumption of 190 mA in the active idle state. In the low power idle state, the current consumption is 170 mA, and in the standby state, the current consumption is 40 mA. Also, the performance idle state time (hereinafter referred to as transition time T_PI) is 0.3 seconds after the end of the access state, and the active idle state time (hereinafter referred to as transition time T_AI) is after the performance idle state ends. 10 seconds. In the present embodiment, these parameters are read from the hard disk load table TB20, stored in the RAM 32 and held as the load parameter table TB10 shown in FIG.

  Furthermore, in this embodiment, the state of the hard disk drive EXHDD is sampled 32 times per second. In other words, the operating state of the hard disk drive EXHDD is specified with a sampling period of 31.25 ms.

  As shown in FIG. 4, the access signal in the present embodiment is at a low level when the hard disk drive EXHDD is in the access state, and is at a high level when the hard disk drive EXHDD is not in the access state.

  Therefore, in the present embodiment, even if the access signal indicates a state of not accessing, whether the hard disk drive EXHDD is in the performance idle state, the active idle state, the low power idle state, The current consumption varies greatly depending on whether it is in the standby state. For this reason, the load of the hard disk drive EXHDD cannot be accurately calculated simply by detecting and counting the high level and low level of the access signal.

  For example, as shown in FIG. 6, the access state, the performance idle state, the access state, the performance idle state, the access state, and the performance idle state change in order, and as shown in FIG. It is clear when the performance idle state, active idle state, and access state are sequentially compared.

  The number of times the low-level access signal (that is, the access state) is counted in 1 second shown in FIGS. 6 and 7 is the same as 6 times. However, the load on the hard disk drive EXHDD is 438 mA in the case of FIG. 6, 333 mA in the case of FIG. 7, and the difference is 105 mA. When the load of the hard disk drive EXHDD is calculated based only on the access signal indicating whether or not the hard disk drive EXHDD is being accessed, this exists as a potential error.

Therefore, in the present embodiment, the load of the hard disk drive EXHDD is calculated using the following equation (1).

Hard disk drive load = AC load x (N_ON / 32)
+ PI load x (N_OFF_PI / 32)
+ AI load x (N_OFF_AI / 32)
+ LPI load x (N_OFF_LPI / 32)
+ ST load x (N_OFF_ST / 32) (1)

  That is, since sampling is performed 32 times per second, the current consumption per second of the hard disk drive EXHDD is calculated based on the state obtained by sampling. Here, the counter N_ON is a count number when the hard disk drive EXHDD is in the access state in the immediately preceding 1 second, and the counter N_OFF_PI is a count when the hard disk drive EXHDD is in the performance idle state in the immediately preceding 1 second. The counter N_OFF_AI is a count when the hard disk drive EXHDD is in an active idle state in the immediately preceding 1 second, and the counter N_OFF_LPI is in a low power idle state in the immediately preceding 1 second. The counter N_OFF_ST is a count number when the hard disk drive EXHDD is in a standby state in the immediately preceding 1 second. That is, the counters N_ON, N_OFF_PI, N_OFF_AI, N_OFF_LPI, and N_OFF_ST are variables that are cleared to zero every second.

  Since the standby state (ST load) is shifted by issuing an instruction from the CPU 10 to the hard disk drive EXHDD, the standby state can be specified by the CPU 10 itself.

  Next, parameter setting processing executed by the information terminal will be described. FIG. 8 is a flowchart illustrating the contents of parameter setting processing executed by the information terminal according to the present embodiment. This parameter setting process is a process realized by the CPU 10 reading and executing a parameter setting program stored in the ROM 34. The parameter setting process is a process that is automatically started when the information terminal is powered on.

  As shown in FIG. 8, first, the information terminal acquires the model name of the external hard disk drive EXHDD connected to the information terminal (step S10). This is information automatically provided from the hard disk drive EXHDD to the CPU 10 of the information terminal when power is supplied to the hard disk drive EXHDD. Here, as described above, it is assumed that “AAA — 1111111” is acquired as the model name.

  Next, the information terminal searches the hard disk load table TB20 stored in the ROM 34, and acquires the load parameter of the model name acquired in step S10 (step S12). Here, since the model name “AAA — 1111111” is acquired in step S10, the hard disk load table TB10 is searched using this model name as a search key.

  If the model name acquired in step S10 is not registered in the hard disk load table TB10, the load parameter registered in “Other” is acquired.

  Next, the information terminal generates a load parameter table TB10 based on the load parameter acquired in step S12, and stores it in the RAM 32 (step S14). Thereby, the parameter setting process according to the present embodiment ends.

  Next, hard disk drive load count processing in this embodiment will be described. FIG. 9 is a flowchart illustrating the contents of the hard disk drive load count process according to the present embodiment. The hard disk drive load count process shown in FIG. 9 is a process realized by the CPU 10 reading and executing a hard disk drive load count process program stored in the ROM 34. Further, the hard disk drive load count process is started and counted every 31.25 ms.

  As shown in FIG. 9, first, the information terminal determines whether or not the hard disk drive EXHDD is in an active state (step S20). Specifically, it is determined whether or not the access signal of the hard disk drive EXHDD indicates an accessing state. If the hard disk drive EXHDD is in the active state (step S20: YES), the counter N_ON is incremented by one (step S22).

  On the other hand, if the hard disk drive EXHDD is not in an active state (step S20: NO), it is determined whether or not the hard disk drive EXHDD is in a standby state (step S24). Specifically, since the CPU 10 outputs a command signal for shifting the hard disk drive EXHDD to the standby state, the CPU 10 can grasp whether or not the hard disk drive EXHDD is in the standby state. For this reason, the CPU 10 itself determines whether or not the hard disk drive has been put into a standby state. If the hard disk drive EXHDD is in the standby state (step S24: YES), the counter N_OFF_ST is incremented by one (step S26).

  On the other hand, when it is determined that the hard disk drive EXHDD is not in the standby state (step S24: NO), the information terminal acquires the transition time T_PI from the load parameter table TB10 (step S28).

  Next, the information terminal determines whether or not the access signal has continuously been in the non-access state for more than (T_PI / 0.03125) times of sampling (step S30). Specifically, the CPU 10 starts counting the number of consecutive non-accesses from zero immediately after shifting from a state where the access signal is accessed (low level) to a state where the access signal is not accessed (high level). At this time, when the state of not being accessed continues, a process of counting up the number of consecutive non-accesses by one is performed.

  Then, the information terminal determines whether or not the continuous non-access number has continued more than (T_PI / 0.03125) times. As described above, in the present embodiment, the performance idle transition time varies depending on the model of the hard disk drive EXHDD. Therefore, it is necessary for the performance idle period to elapse based on the transition time T_PI acquired in step S28. Calculate the number of consecutive non-accesses.

  In the example of FIG. 3, the performance idle state is a setting that continues for 300 ms when there is no access. For this reason, in the present embodiment in which sampling is performed every 31.25 ms, the performance idle state corresponds to a sampling time of 10 times, and therefore, the number of times the access signal that has been continuously in the non-access state is sampled 10 times or less. In this case, it can be determined that the system is in the performance idle state. When the number of consecutive non-accesses is equal to or less than (T_PI / 0.03125) times (step S30: NO), the counter N_OFF_PI is incremented by one (step S32).

  On the other hand, when the number of consecutive non-accesses is greater than (T_PI / 0.03125) times (step S30: YES), the information terminal acquires the transition time T_AI from the load parameter table TB10 (step S34).

  Next, the information terminal determines whether the number of consecutive non-accesses is greater than (T_PI + T_AI) /0.03125 times (step S36). As described above, in the example of FIG. 3, since the transition time of active idle is 10 seconds, the information terminal determines whether the number of consecutive non-accesses is greater than 330 times. That is, in the example of FIG. 3, the performance idle state is a setting that continues for 300 ms, and then the active idle state is a setting that continues for 10 seconds. Therefore, in the present embodiment in which sampling is performed every 31.25 ms, (0.3 + 10) /0.03125=329.6, and therefore 330 times is the number of determination criteria.

  That is, when the number of consecutive non-accesses indicating the number of times of consecutive non-access state sampling is greater than 10 and less than or equal to 330 times, it can be determined that the active idle state is present. When the number of consecutive non-accesses is equal to or less than (T_PI + T_AI) /0.03125 (step S36: NO), the counter N_OFF_AI is incremented by one (step S38).

  On the other hand, when the number of consecutive non-accesses is larger than (T_PI + T_AI) /0.03125 times (step S36: YES), the counter N_OFF_LPI is incremented by one (step S40).

  The hard disk drive load count processing according to the present embodiment is completed by the processing of step S22, step S26, step S32, step S38, and step S40.

  Next, the remaining battery level calculation process according to the present embodiment will be described. 10 and 11 are flowcharts for explaining the content of the remaining battery level calculation process according to the present embodiment. The remaining battery level calculation process shown in FIGS. 10 and 11 is a process realized by the CPU 10 reading and executing the remaining battery level calculation process program stored in the ROM 34. In the present embodiment, the remaining battery level calculation process is a process that is started at a rate of once per second.

  As illustrated in FIG. 10, the information terminal acquires a battery voltage that is a voltage of the battery 20 (step S50). That is, the voltage of the battery 20 detected by the voltage detection circuit 40 is acquired as digital data via the AD converter 30.

  Next, the information terminal acquires the battery temperature that is the temperature of the battery 20 (step S52). That is, the battery temperature of the analog data detected by the temperature detection circuit 42 provided inside the battery 20 is acquired as digital data via the AD converter 30.

  Next, the information terminal acquires a steady load (step S54). This steady load varies depending on the operation mode of the CPU 10. In the present embodiment, the CPU 10 is assumed to have three operation modes of low speed, medium speed, and high speed. Of these three operation modes, the CPU 10 knows which one is currently in operation. In this embodiment, the steady load is 400 mA at low speed, the steady load is 500 mA at medium speed, and the steady load is 600 mA at high speed.

  Next, the information terminal acquires the hard disk drive operating rate (step S56). In the present embodiment, the load on the hard disk drive EXHDD is calculated based on the above-described equation (1). That is, by the hard disk drive load count process, the load on the hard disk drive EXHDD is calculated based on the result of sampling the state of the hard disk drive EXHDD during the previous one second. Specifically, by substituting the N_ON count number, N_OFF_PI counter number, N_OFF_AI count number, N_OFF_LPI count number, and N_OFF_ST count number in the previous one second into the formula (1), the current hard disk The load on the drive EXHDD is calculated.

  Next, these counters N_ON, N_OFF_PI, N_OFF_AI, N_OFF_LPI, and N_OFF_ST are cleared and set to zero (step S58).

  Next, the information terminal acquires an LCD backlight luminance coefficient (step S60). In the present embodiment, the CPU 10 outputs a luminance signal for controlling the luminance of the LCD backlight 12 to the LCD backlight 12. Therefore, the CPU 10 can grasp the luminance coefficient of the LCD backlight 12 based on this luminance. In the present embodiment, the LCD backlight luminance coefficient is configured to be set in increments of 10% between 0% and 100%.

Next, the information terminal uses the following equation (2) to calculate the load of the entire information terminal (step S62).

Load = steady load + hard disk drive load
+ LCD load x LCD backlight luminance coefficient (2)

  Here, it is assumed that the hard disk drive access load is 500 mA, for example. In the present embodiment, the LCD load is, for example, 100 mA. Then, the current load of the information terminal is substituted by substituting the steady load acquired in step S54, the hard disk drive load acquired in step S56, and the LCD backlight luminance coefficient acquired in step S18 into equation (2). Can be calculated.

  Next, as shown in FIG. 11, the information terminal generates a voltage-residual amount conversion table corresponding to the battery temperature (step S70). In the present embodiment, four types of temperature-dependent voltage-remaining amount conversion tables are stored in the ROM 34 in the CPU 10. 12 to 15 are diagrams illustrating examples of these four types of temperature-dependent voltage-remaining amount conversion tables TB30 to TB60. 12 is a diagram showing a voltage-remaining amount conversion table TB30 when the battery temperature is 5 ° C., and FIG. 13 is a diagram showing a voltage-remaining amount conversion table TB40 when the battery temperature is 15 ° C. FIG. 14 is a diagram showing a voltage-remaining amount conversion table TB50 when the battery temperature is 25 ° C., and FIG. 15 is a diagram showing a voltage-remaining amount conversion table TB60 when the battery temperature is 45 ° C.

  As can be seen from these figures, in the present embodiment, the relationship between the remaining amount and the battery voltage is tabulated using three cases of loads of 400 mA, 800 mA, and 1200 mA as representative values. Then, using these voltage-remaining amount conversion tables, the voltage-remaining amount conversion table at the battery temperature acquired in step S52 is generated by the linear interpolation method.

これにより算出された電池温度が２０℃の場合の電圧−残量変換テーブルＴＢ７０は、図１６に示すようになる。この電圧−残量変換テーブルＴＢ７０は、ＣＰＵ１０のＲＡＭ３２に格納される。 For example, it is assumed that the battery temperature acquired in step S52 is 20 ° C. In this case, by linearly interpolating the voltage value of the 15 ° C. voltage-residual amount conversion table TB40 shown in FIG. 13 and the voltage value of the 25 ° C. voltage-residual amount conversion table TB50 shown in FIG. The voltage value of the voltage-residual amount conversion table TB50 is generated. Specifically, the temperature of the low voltage side voltage-residual conversion table is T1 (15 ° C.), the temperature of the high voltage side voltage-residual conversion table is T2 (25 ° C.), and the battery temperature is T (20 ° C.). ), And Y1 is a voltage value at T1, and Y2 is a voltage value at T2, the corrected voltage Y can be calculated by the following equation.

The voltage-remaining amount conversion table TB70 when the battery temperature calculated in this way is 20 ° C. is as shown in FIG. This voltage-remaining amount conversion table TB70 is stored in the RAM 32 of the CPU 10.

  In this embodiment, when the battery temperature is lower than 5 ° C., a voltage-remaining amount conversion table of 5 ° C. and 15 ° C. is used, and when the battery temperature is higher than 45 ° C., the voltage-remaining amount of 25 ° C. and 45 ° C. By using the conversion table and substituting it into Equation (3), a voltage-residual amount conversion table for those temperatures is obtained.

  Next, as shown in FIG. 11, the information terminal generates a voltage-residual amount conversion table corresponding to the load calculated in step S20 (step S72). That is, based on the voltage-residual amount conversion table generated in step S70, a voltage-residual amount conversion table corresponding to the load calculated in step S62 is generated and stored in the RAM 32.

これにより算出された負荷が１０００ｍＡの場合の電圧−残量変換テーブルＴＢ８０は、図１７に示すようになる。 For example, assume that the load calculated in step S62 is 1000 mA. In this case, the voltage value in the voltage-residual amount conversion table TB80 shown in FIG. 16 is linearly interpolated between the voltage value in the case of 800 mA and the voltage value in the case of 1200 mA. Is generated. Specifically, the current value on the low load side is L1 (800 mA), the current value on the high load side is L2 (1200 mA), the load calculated in step S62 is L, and Y1 is the voltage value at L1, When Y2 is a voltage value at the time of L2, the corrected voltage Y can be calculated by the following equation.

The voltage-residual amount conversion table TB80 when the calculated load is 1000 mA is as shown in FIG.

  Next, as shown in FIG. 11, the information terminal calculates the remaining battery level based on the voltage-remaining amount conversion table TB80 after the load correction and the temperature correction (step S74). That is, the battery remaining amount corresponding to the battery voltage acquired in step S50 is calculated by linearly interpolating the values in the voltage-remaining amount conversion table TB80 stored in the RAM 32.

これにより、電圧残量を算出すると、約４２％になる。本実施形態では、この算出された電池残量は、一旦、ＲＡＭ３２に格納される。 For example, it is assumed that the battery voltage acquired in step S50 is 3.55V. In this case, the battery voltage is 3 by linearly interpolating 3.54V (battery remaining capacity 40%) and 3.60V (battery remaining capacity 50%) in the voltage-remaining capacity conversion table TB80 shown in FIG. Calculate the remaining battery level for .55V. Specifically, the voltage value on the low voltage side is Y1 (3.54V), the voltage value on the high voltage side is Y2 (3.60V), the voltage acquired in step S50 is Y, and X1 is Y1. When the remaining battery level is X2 and the remaining battery level at Y2 is X2, the corrected battery level X can be calculated by the following equation.

As a result, the remaining voltage is calculated to be about 42%. In the present embodiment, the calculated remaining battery level is temporarily stored in the RAM 32.

  Next, as shown in FIG. 11, the information terminal reads the remaining battery level calculated from the RAM 32 and displays it on the display unit 18 (step S76). Various methods for displaying the remaining battery level are conceivable. For example, the screen of the information terminal may be displayed as 42% as a numerical value, or the display unit 18 may be constituted by a bar-type liquid crystal display unit, and the bar length of the liquid crystal display unit may be The length may be equivalent to 42%.

  As described above, according to the present embodiment, a signal output from a device that outputs the load of a device (for example, the hard disk drive EXHDD, the LCD backlight 12, and the operation mode of the CPU 10) that contributes to the load fluctuation, Alternatively, the calculation is performed by measuring the received signal, and correction is performed based on the calculation result so that the remaining battery level is accurately displayed. In addition, since correction is performed using the CPU 10 that is originally incorporated in the information terminal, it is not necessary to add a new device, and the information terminal can be reduced in size and cost.

  Furthermore, since the battery temperature of the battery 42 is detected using the temperature detection circuit 42 and correction is also performed based on the battery temperature, the remaining battery level can be displayed with higher accuracy.

  In addition, since the model of the removable hard disk drive EXHDD is specified and the load parameters are set according to the model of the hard disk drive EXHDD actually connected to the information terminal, the load on the hard disk drive EXHDD is further increased. It is possible to calculate accurately, thereby improving the accuracy of the remaining battery level.

  In addition, this invention is not limited to the said embodiment, A various deformation | transformation is possible. For example, in the embodiment described above, the remaining battery level is displayed as it is, but this may be converted into the remaining usable time and displayed. In other words, what the user really wants to know is information on how much the information terminal can be used in the same way as it is now. In the embodiment described above, even an information terminal having a large load fluctuation can estimate the fluctuation of the load, and therefore the remaining usable time can be calculated based on the value of the load and the remaining battery level. Of course, this may be displayed in real time. As a result, for example, when a user is viewing a video, it is possible to accurately know how much can be viewed later, or how much data can be transferred later when backing up data. Can know with high accuracy.

  In the above-described embodiment, the LCD backlight 12, the hard disk drive EXHDD, and the CPU load are given as examples of the drive unit having a large load fluctuation. However, other drive unit elements may be added. Alternatively, some of the elements of the drive unit can be omitted. For example, since the influence of the load fluctuation is not so great, the LCD backlight 12 may not be considered when calculating the load. Alternatively, these driving elements may calculate the load as a constant constant. For example, the LCD backlight 12 may calculate the load with a constant value of 100 mA regardless of the luminance coefficient.

  Furthermore, in the above-described embodiment, the information terminal calculates a load other than the hard disk drive EXHDD as the load on the battery 20, but calculates the load of only the hard disk drive EXHDD and the remaining battery level based on this load. May be corrected.

  In addition, the current consumption and the transition time of the hard disk drive EXHDD used in the above-described embodiments are merely exemplary, and vary depending on the model of the hard disk drive EXHDD.

  In the above-described embodiment, the transition time is predetermined for the performance idle state and the active idle state of the hard disk drive EXHDD. However, all transitions are made for states other than the access state and the standby state. The time can be predetermined.

  Further, the state of the hard disk drive EXHDD is not limited to the five states described above, and may have different load states for the battery 20 in other sections.

  In the above-described embodiment, the load on the hard disk drive EXHDD is calculated at intervals of 1 second. However, the load on the hard disk drive EXHDD may be calculated every other predetermined period.

  In the above-described embodiment, the calculated remaining battery level is corrected based on the battery temperature acquired in step S52. However, the correction based on the battery temperature is not necessarily required.

  In the above-described embodiment, the hard disk drive EXHDD is described as being detachably connected to the information terminal. However, for example, this specification is also applied to a specification in which the hard disk drive EXHDD is connected to the information terminal later. The invention can be applied. That is, the information terminal does not have a built-in hard disk drive, and the user can specify the hard disk drive EXHDD to be installed in advance even if the user arbitrarily attaches the hard disk drive EXHDD after purchasing the information terminal. Since this is not possible, the remaining battery level can be calculated more accurately by applying the present invention.

  For each process described in the above-described embodiment, a program for executing each process is recorded on a recording medium such as a flexible disk, a CD-ROM (Compact Disc-Read Only Memory), a ROM, or a memory card. Thus, it can be distributed in the form of a recording medium. In this case, the above-described embodiment can be realized by causing the information terminal to read and execute the recording medium on which the program is recorded.

  In addition, the information terminal may include another program such as an operating system or another application program. In this case, the other program provided in the information terminal is utilized, and the recording medium is recorded with an instruction for calling a program that realizes the same processing as the above-described embodiment from among the programs provided in the information terminal. May be.

  Furthermore, such a program can be distributed not as a recording medium but as a carrier wave through a network. The program transmitted in the form of a carrier wave on the network is taken into the information terminal, and the above-described embodiment can be realized by executing this program.

  Also, when a program is recorded on a recording medium or transmitted as a carrier wave on a network, the program may be encrypted or compressed. In this case, the information terminal that has read the program from the recording medium or the carrier wave needs to execute the program after decoding or decompressing the program.

  Furthermore, the above-described processing can be realized by hardware such as ASIC (Application Specific IC) as shown in FIG. In FIG. 18, the control unit composed of the hardware of the information terminal includes a hard disk load holding unit 100, an identification information acquisition unit 102, a load parameter acquisition unit 104, a load calculation unit 106, and a remaining battery level calculation unit 108. And is configured. Other parts are the same as those of the information terminal described above.

  Specifically, the voltage detection circuit 40 detects a battery voltage that is the voltage of the battery 20. The identification information acquisition unit 102 acquires, from the hard disk drive EXHDD, identification information that identifies the model of the hard disk drive EXHDD that is driven by power supplied from the battery 20. The hard disk drive EXHDD is detachably connected to the information terminal. The identification information for identifying the model of the hard disk drive EXHDD is, for example, the model name of the hard disk drive EXHDD.

  The hard disk load holding unit 100 holds a load parameter for a battery for a plurality of types of hard disk drives. Specifically, the hard disk load table TB20 shown in FIG. 5 described above is held.

  The load parameter acquisition unit 104 searches the hard disk load holding unit 100 based on the identification information of the hard disk drive EXHDD acquired by the identification information acquisition unit 102, and acquires the parameter of the load on the battery of the hard disk drive EXHDD.

  The load calculating unit 106 calculates the load on the battery 20 of the hard disk drive EXHDD using the load parameter acquired by the load parameter acquiring unit 104. The specific calculation method is as described above.

  When calculating the remaining battery level based on the battery voltage, the remaining battery level calculating unit 108 calculates a corrected remaining battery level based on the load calculated by the load calculating unit 106.

  Here, the hard disk drive EXHDD has a plurality of states with different loads on the battery 20, and the hard disk load holding unit 100 holds the load value on the battery as a parameter for each state of the hard disk drive EXHDD. .

  Of the states of the hard disk drive EXHDD, transition times T_PI and T_AI are predetermined for the performance idle state and the active idle state. The hard disk load table TB20 in the hard disk load holding unit 100 holds the transition times T_PI and T_AI as parameters.

  Further, the load calculation unit 106 counts the load based on the state transition of the hard disk drive EXHDD in a predetermined period (one second immediately before in the above-described embodiment), and based on the counted load, the hard disk drive EXHDD Calculate the load.

  In addition, the information terminal includes a CPU 10, an LCD backlight 12, and other loads 16 as drive units other than the hard disk drive that are driven by power supplied from the battery 20. Then, the load calculation unit 106 calculates a load on the battery 20 including the hard disk drive EXHDD and these drive units. Therefore, the remaining battery level calculation unit 108 calculates the corrected remaining battery level based on these overall loads.

  The temperature detection circuit 40 is an arbitrary component and detects a battery temperature that is the temperature of the battery 20. If the temperature detection circuit 40 is present, the battery remaining amount calculation unit 108 can also calculate the remaining battery amount corrected based on the battery temperature detected by the temperature detection circuit 40.

  The information terminal displays the remaining battery level calculated by the remaining battery level calculation unit 108 on, for example, the display unit 18.

The block diagram explaining an example of the composition of the information terminal concerning this embodiment. The figure which shows the graph of the relationship between a battery voltage and a battery remaining charge. The figure which shows an example of a structure of the load parameter table which the information terminal which concerns on this embodiment produces | generates. The figure which shows an example of the transition of the operating state of the hard disk drive in the information terminal which concerns on this embodiment, and current consumption. The figure which shows an example of a structure of the hard disk load table which the information terminal which concerns on this embodiment hold | maintains. The figure which shows an example of the transition of the operation state of the hard-disk drive in the information terminal which concerns on this embodiment. The figure which shows an example of the transition of the operation state of the hard-disk drive in the information terminal which concerns on this embodiment. The figure which shows the flowchart explaining the content of the parameter setting process which the information terminal which concerns on this embodiment performs. The figure which shows the flowchart explaining the content of the hard-disk drive load count process which the information terminal which concerns on this embodiment performs. The figure which shows the flowchart explaining the content of the battery remaining charge calculation process which the information terminal which concerns on this embodiment performs (the 1). The figure which shows the flowchart explaining the content of the battery remaining charge calculation process which the information terminal which concerns on this embodiment performs (the 2). The figure which shows an example of the 5 degreeC voltage-residual amount conversion table which the information terminal which concerns on this embodiment hold | maintains. The figure which shows an example of the 15 degreeC voltage-residual amount conversion table which the information terminal which concerns on this embodiment hold | maintains. The figure which shows an example of the 25 degreeC voltage-residual amount conversion table which the information terminal which concerns on this embodiment hold | maintains. The figure which shows an example of the 45 degreeC voltage-residual amount conversion table which the information terminal which concerns on this embodiment hold | maintains. The figure which shows an example of the 20 degreeC voltage-residual amount conversion table produced | generated from the 15 degreeC voltage-residual amount conversion table and the 25 degreeC voltage-residual amount conversion table. The figure which shows an example of the 1000 mA voltage-residual amount conversion table produced | generated from the 20 degreeC voltage-residual amount conversion table shown in FIG. The figure which shows an example of a structure at the time of implement | achieving battery remaining charge calculation processing with hardware.

Explanation of symbols

EXHDD Hard disk drive 10 CPU
12 LCD backlight 16 Other load 18 Display unit 20 Battery 22 DC / DC converter 30 AD converter 32 RAM
34 ROM
40 Voltage detection circuit

Claims (10)

An information terminal driven by a battery,
Voltage detecting means for detecting a battery voltage which is a voltage of the battery;
A hard disk drive driven by receiving power from the battery and having a plurality of states with different loads on the battery, based on a load parameter for the battery for each of the plurality of states, the load on the battery of the hard disk drive A load calculating means for calculating
Battery remaining amount calculating means for calculating a battery remaining amount based on the battery voltage and the load calculated by the load calculating means;
With
The load calculating means counts a load based on a state transition of the hard disk drive during a predetermined period, and calculates a load on the battery of the hard disk drive based on the counted load. Terminal. For some states of the hard disk drive, the transition time to transition from that state to another state is predetermined,
The information terminal according to claim 1 , wherein the load calculating unit further uses the transition time as a parameter.   An identification information acquisition means for acquiring identification information for identifying a model of the hard disk;
  The information terminal according to claim 1, wherein the load calculation unit uses a parameter of a load on the battery of the hard disk drive corresponding to the identification information acquired by the identification information acquisition unit. It further includes a drive unit other than the hard disk drive that is driven by receiving power from the battery,
It said load calculating means, information terminal according to any one of claims 1 to 3 wherein the calculating the load on the battery, including a hard disk drive and the drive unit, characterized in that. It further comprises temperature detecting means for detecting a battery temperature which is the temperature of the battery,
The battery residual quantity calculation means, information according to any one of claims 1 to 4 wherein calculating the battery remaining amount to the correction based on the battery temperature detected by the temperature detecting means, characterized in that Terminal. The information terminal according to any one of claims 1 to 5 , further comprising a display unit that displays the remaining battery level calculated by the remaining battery level calculating unit. The information terminal according to any one of claims 1 to 6 , wherein the hard disk drive is detachably connected to the information terminal. A battery remaining amount calculation method in an information terminal driven by a battery,
Detecting a battery voltage which is a voltage of the battery;
The load on the battery of the hard disk drive based on the plurality of parameters of the load on the battery for each state of the plurality of hard disk drives that are driven by receiving power supply from the battery and have different states on the battery Calculating steps,
Calculating a remaining battery level based on the battery voltage and the calculated load;
With
In the step of calculating the load, the load is counted based on a state transition of the hard disk drive in a predetermined period, and the load on the battery of the hard disk drive is calculated based on the counted load. Battery level calculation method. A program for causing an information terminal driven by a battery to calculate the remaining battery charge,
Detecting a battery voltage which is a voltage of the battery;
A hard disk drive driven by receiving power from the battery and having a plurality of states with different loads on the battery, based on load parameters for the battery for each of the plurality of states, the load on the battery of the hard disk drive Calculating steps,
Calculating a remaining battery level based on the battery voltage and the calculated load;
To the information terminal,
In the step of calculating the load, the load is counted based on a state transition of the hard disk drive in a predetermined period, and the load on the battery of the hard disk drive is calculated based on the counted load. Program to do. A recording medium recorded with a program for causing an information terminal driven by a battery to calculate the remaining battery charge,
Detecting a battery voltage which is a voltage of the battery;
A hard disk drive driven by receiving power from the battery and having a plurality of states with different loads on the battery, based on load parameters for the battery for each of the plurality of states, the load on the battery of the hard disk drive Calculating steps,
Calculating a remaining battery level based on the battery voltage and the calculated load;
To the information terminal,
In the step of calculating the load, the load is counted based on a state transition of the hard disk drive in a predetermined period, and the load on the battery of the hard disk drive is calculated based on the counted load. A recording medium on which a program to be recorded is recorded.

Images