JP2006260382A - Information terminal unit and battery residual power calculation method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an information terminal unit for eliminating necessity for measuring battery voltage repeatedly when displaying residual power of a battery. <P>SOLUTION: This information terminal unit having an LCD back-light 12 and an HDD 14 operating by receiving supply of power supply is provided. A voltage detection circuit 40 detects voltage of the battery 20 before supplying the battery 20 to the LCD back-light 12 and the HDD 14. A CPU 10 determines operation mode of the information terminal unit and obtains electric power consumption from load to the battery 20 and operation time in operation mode when operating in this operation mode. Residual power of the battery 20 is obtained from the battery voltage and electric power consumption. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an information terminal having a function of detecting a remaining battery level and a battery remaining amount calculating method.

  An increasing number of small information terminals using batteries handle still images and moving images. An increasing number of such small information terminals are equipped with devices such as hard disk drives that have a large effect on load fluctuations. Depending on the driving state of such a device, the load on the battery is greatly fluctuating.

  In order to estimate how much the information terminal can be used, an accurate display of the remaining battery level is very important. As a method for detecting the remaining battery level, a method for measuring the charge / discharge current of the battery is disclosed (for example, see Patent Documents 1 and 2). Further, a method for measuring battery voltage is disclosed (for example, see Patent Documents 3 and 4).

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. Therefore, it is not suitable for a small information terminal.

  On the other hand, in the method of measuring the battery voltage, the battery voltage obtained by the load changing varies. In particular, the value of the battery voltage that can be acquired varies between when there is a load and when there is no load. Since the remaining battery level is obtained from the acquired battery voltage, different remaining battery levels are displayed depending on whether the load is large or small even with the same remaining battery level.

  Therefore, in an information terminal incorporating a device with a large load fluctuation, the remaining battery level detected each time the battery voltage is measured changes, so the detected remaining battery level tends to be inaccurate. Since the display of the remaining battery level is inaccurate as described above, the remaining battery level cannot be properly confirmed, and the remaining battery level cannot be properly managed by charging or the like. Further, in order to detect the remaining battery level, it is necessary to measure the battery voltage many times while the information terminal is in operation, and there is a problem that the processing of the information terminal is burdened.

  An object of the present invention is to provide an information terminal that eliminates the need to repeatedly measure the battery voltage when displaying the remaining battery level, in order to eliminate the above-described problems caused by the prior art.

  In order to solve the above-described problem, an information terminal according to the present invention is an information terminal having a drive unit that operates in response to the supply of power from a rechargeable battery, and the battery before the supply of power to the drive unit is performed. Detection means for detecting the battery voltage of the information terminal, determination means for determining the operation mode of the information terminal, load on the battery when operating in the operation mode determined by the determination means, and operation time in the operation mode And calculating means for determining the remaining amount of the battery from the battery voltage and the power consumption determined by the calculating means.

  In addition, the operation mode of the information terminal is a type of information processing realized in the information terminal by operating the driving unit, and the calculation means includes a load according to the type of information processing and the information You may obtain | require the power consumption by this information processing from the time passed in execution of a process.

  The operation mode of the information terminal is the type of operation of the drive unit, and the calculation means calculates the drive unit based on the load according to the type of operation of the drive unit and the time when the drive unit is operated. You may ask for power consumption by.

  Further, the calculation means may obtain the power consumption by multiplying the load on the battery and the operation time in the operation mode.

  Further, the calculation means obtains an initial value of power consumption by subtracting the battery voltage detected by the detection means from the battery voltage in the case of full charge, and the load on the battery and the operation mode are obtained as the initial value. The power consumption may be obtained by adding a value obtained by multiplying the operation time at.

  In addition, a temperature detection unit that detects a temperature is further provided, and the calculation unit calculates a value based on the temperature detected by the temperature detection unit and the battery voltage detected by the detection unit as the remaining battery level when fully charged. The initial value of the battery remaining amount may be obtained by subtracting from the amount.

  Moreover, you may provide the display means which displays the battery remaining amount measured by the said measurement means on a display.

  The battery remaining amount calculating method according to the present invention is a battery remaining amount calculating method for an information terminal having a drive unit that operates in response to the supply of power from a rechargeable battery, before the power is supplied to the drive unit. A detection step of detecting a battery voltage of the battery, a determination step of determining an operation mode of the information terminal, a load on the battery when operating in the operation mode determined by the determination step, and the operation mode A calculation step for obtaining power consumption from the operating time of the battery, a measurement step for obtaining the remaining amount of the battery from the battery voltage and the power consumption obtained by the calculation step.

  Exemplary embodiments of an information terminal and a battery remaining amount calculation method according to the present invention will be described below in detail with reference to the accompanying drawings.

Example 1
FIG. 1 is a block diagram illustrating an example of the configuration of an information terminal. As shown in FIG. 1, the information terminal includes a CPU 10, an LCD backlight 12, an HDD (hard disk drive) 14, and a display unit 18.

  The information terminal includes a battery 20, and power supplied from the battery 20 is supplied to the drive unit via the DC / DC converter 22. That is, power is supplied to the CPU 10, the LCD backlight 12, the hard disk drive 14, and the display unit 18. That is, the power is supplied as a voltage stabilized by the DC / DC converter 22 or transformed. The CPU 10 includes an AD converter 30, a RAM 32, and a ROM 34 inside.

  The information terminal also includes a voltage detection circuit 40. This voltage detection circuit detects the voltage between the battery 20 and the DC / DC converter 22, and supplies the detected value to the AD converter 30 of the CPU 10 as the battery voltage. 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.

  When the main body is activated, power is supplied from a functional unit necessary for battery voltage measurement before power is supplied to the CPU 10, HDD 14, and LCD backlight 12. The voltage detection circuit 40 measures the battery voltage before starting a device with a large load, such as the HDD 14 or the LCD backlight 12. At the time of battery voltage measurement, since a device with a large load is not activated, the battery voltage can be measured with the same load every time the battery voltage is activated. The measured voltage is digitized by the A / D converter 30 of the processor.

  FIG. 2 is an explanatory diagram for explaining an average current consumption due to a steady load for each operation mode. This information terminal has operation modes of USB data transfer, still image reproduction (slide show), and moving image reproduction, and the average current consumption due to the steady load in each operation mode will be described. With this device, the power consumption is as follows when a moving image is played for 30 minutes and a slide show is performed for 30 minutes.

  In moving image reproduction, 450 (mA) × 0.5 (h) = 225 (mAh). In the slide show, 400 (mA) × 0.5 (h) = 200 (mAh). In total, 225 + 200 = 425 (mAh).

  FIG. 3 is a graph showing the discharge characteristics when the main body is started. The current value of the discharge current at the time of starting the main body is 0.46 A, and the discharge curve of the discharge characteristics with respect to this current value is shown in FIG. The discharge characteristics of the battery 20 can be known in advance by actual measurement or data from the manufacturer. After the battery 20 is fully charged, the power consumption is 425 (mAh) after use in the above mode. When the battery voltage corresponding to 425 (mAh) is confirmed with reference to this discharge curve, the battery voltage is about 3.9V.

  After turning on all the devices of the information terminal, the remaining capacity of the battery 20 is displayed by an icon. Further, the power consumption can be obtained by referring to the operation mode and the elapsed time, whereby the remaining battery level can be obtained. This remaining battery level can be divided into, for example, three states. The three states can be displayed with icons 1 to 3 from the one with the most remaining battery power to the one with the least amount of battery.

  The relationship between the remaining battery level and the icon is shown in the lower part of FIG. When the power consumption is 0 to 800 (mAh), it is indicated by an icon 1. When the power consumption is 800 to 2000 (mAh), it is indicated by an icon 2. When the power consumption is 2000 to 2400 (mAh), it is indicated by an icon 3.

  FIG. 4 is an explanatory diagram for explaining a display example of an icon indicating the remaining battery level. By displaying the remaining battery level with the icon, the user can clearly know the remaining battery level and can manage the remaining battery level appropriately. In addition, the display method of a battery remaining charge is not limited to the display by the icon shown in FIG. For example, instead of the three types of icons shown in FIG. 4, it is possible to display using more types of icons such as five types and ten types. Also, the remaining battery level can be displayed by the length of the bar graph using a bar graph instead of the icon. In addition, the actual number of remaining batteries can be displayed in the form of 100% or 70%, for example.

  FIG. 5 is a flowchart of battery remaining amount display processing at the time of power activation. First, power is turned on at a portion necessary for battery voltage measurement (step S501). Next, the voltage detection circuit 40 measures the battery voltage (step S502). Then, the battery discharge amount C is calculated (step S503). The battery discharge amount C can be calculated by taking the difference between the measured battery voltages from the fully charged voltage. Then, power is turned on as a whole (step S504).

  Next, it is determined whether C at the time of activation is within a range of 0 ≦ C <800 (step S505). When C is within the range (step S505: Yes), the display unit 18 displays the icon 1 (step S506), and ends the series of processes.

  When C is not within the range (step S505: No), it is determined whether C at the time of activation is within a range of 800 ≦ C <2000 (step S507). When C is within the range (step S507: Yes), the display unit 18 displays the icon 2 (step S508), and ends the series of processes.

  When C is not within the range (step S507: No), C at the time of activation is within the range of 2000 ≦ C, so the display unit 18 displays the icon 3 (step S509), and a series of processes Exit.

  For example, it is assumed that 4.2V is detected as a result of measuring the battery voltage at startup. By referring to the graph of FIG. 3, this voltage is displayed as a fully charged state. Since the battery is fully charged, the battery discharge amount C is zero. In addition, after this series of battery remaining amount display processing at the time of power activation is completed, the entire battery is turned on and the remaining amount of battery changes. Then, next, the process proceeds to a battery remaining amount display process when the main body is operating.

  FIG. 6 is a flowchart of the battery remaining amount display process corresponding to the operation mode of the device. First, the operation mode is determined (step S601). Next, it waits for 1 second (step S602), and calculates the consumed capacity L (step S603). That is, the consumed capacity L corresponding to the operation mode is added to the battery discharge amount C every second. As an operation mode of the information terminal, for example, when moving image playback is performed, a capacity of 450/3600 (mAh) per second is consumed. In addition, when the mode is changed by a user operation in the middle, the consumed capacity L is changed to a corresponding value in correspondence with the changed mode.

  Next, it is determined whether it is in the range of 0 ≦ C + L <800 (step S604). When C + L is within the range (step S604: Yes), the display unit 18 displays the icon 1 (step S605), and proceeds to step S609.

  If C + L is not within the range (step S604: No), it is determined whether it is within the range of 800 ≦ C + L <2000 (step S606). When C + L is within the range (step S606: Yes), the display unit 18 displays the icon 2 (step S607). That is, the transition from icon 1 to icon 2 occurs when the value of C + L exceeds 800 mAh. Then, the process proceeds to step S609.

  If C + L is not within the range (step S606: No), it is within the range of 2000 ≦ C + L, so the display unit 18 displays the icon 3 (step S608). That is, when the value of C + L exceeds 2000 mAh, the icon 2 changes to the icon 3. Next, it is determined whether or not the power is turned off (step S609), and when the power is turned off (step S609: Yes), a series of processing ends. When the power is not cut off (step S609: No), the process returns to step S602.

(Example 2)
In the first embodiment, the power consumption is obtained for each operation mode. However, the power consumption can be obtained by paying attention to the operation of the connected drive unit. That is, the battery remaining amount is calculated by obtaining the power consumption from the load applied to the driving unit such as the LCD backlight 12 and the HDD 14. The configuration of the information terminal of this embodiment is the same as that shown in FIG.

  The remaining battery level is displayed by the icon shown in FIG. 4 after all devices of the information terminal are turned on. The discharge characteristics are as described in FIG. 3, and the relationship between the remaining battery level and the icons is as shown in the lower part of FIG.

  FIG. 7 is an explanatory diagram for explaining the relationship between the LCD backlight luminance and the current value. Here, with respect to the luminance of the LCD backlight 12, the backlight current value flowing at this time is shown in mA.

  FIG. 8 is an explanatory diagram for explaining the relationship between the operation mode of the HDD and the current value. This indicates that the operating current value when idle (i.e., not accessed) is 600 mA, and the operating current value when accessed (i.e., accessed) is 190 mA.

  Here, the device is used for one hour in a certain use state, and the device usage integration time after that time is 45 minutes when the HDD 14 is idle, and the access time is 15 minutes. On the other hand, in the backlight luminance, 100% time is 30 minutes and 50% time is 30 minutes. In this way, the CPU 10 is notified. Although the case where the LCD backlight 12 and the HDD 14 are connected will be described here, more devices may be connected and the load of the connected devices may be obtained. In this case, the power consumption is as follows.

  From FIG. 7, the LCD backlight 12 is 100 (mA) × 0.5 (h) +50 (mA) × 0.5 (h) = 75 (mAh). From FIG. 8, with respect to the HDD 14, 600 (mA) × 0.25 (h) +190 (mA) × 0.75 (h) = 292.5 (mAh). In total, 75 + 292.5 = 367.5 (mAh).

  When the battery voltage initial value is measured to be 3.86 (V), the power consumption is about 800 (mAh) from the discharge curve shown by the discharge characteristics of the battery described in FIG. Here, after use in the above mode, 800 + 367.5 = 1167.5 (mAh). As a result, the battery voltage is required to be about 3.78V.

  FIG. 9 is a flowchart of the battery remaining amount display process corresponding to the operation mode of the component. This processing is started after the battery remaining amount display processing at the time of power activation explained in FIG. Therefore, the battery discharge amount C has already been measured, and power is supplied to the main body.

  First, the information terminal acquires the HDD operation rate (step S901). The HDD 14 outputs an access signal indicating whether access is being made to the CPU 10. For this reason, the CPU 10 can acquire the access signal and calculate the time during which the HDD 14 is accessing and the time other than the access.

  Next, the information terminal acquires a setting value of the LCD backlight 12 (step S902). The CPU 10 outputs a signal for controlling the luminance of the LCD backlight 12 to the LCD backlight 12. Therefore, based on this signal, the CPU 10 can grasp the set value of the LCD backlight 12. In the present embodiment, the setting value of the LCD backlight 12 can be set in increments of 10% between 0% and 100%.

  Next, it waits for 1 second (step S903), obtains power consumption L1 by the HDD 14 (step S904), and obtains power consumption L2 by the LCD backlight 12 (step S905). L1 and L2 are calculated every second.

  Next, it is determined whether or not the range is 0 ≦ C + L1 + L2 <800 (step S906). When C + L1 + L2 is within the range (step S906: Yes), the display unit 18 displays the icon 1 (step S907), and proceeds to step S911.

  If C + L1 + L2 is not within the range (step S906: No), it is determined whether it is within the range of 800 ≦ C + L1 + L2 <2000 (step S908). When C + L1 + L2 is within the range (step S908: Yes), the display unit 18 displays the icon 2 (step S909). That is, the transition from icon 1 to icon 2 occurs when the value of C + L1 + L2 exceeds 800 mAh. Then, the process proceeds to step S911.

  When C + L1 + L2 is not within the range (step S908: No), it is within the range of 2000 ≦ C + L1 + L2, so the display unit 18 displays the icon 3 (step S910). That is, when the value of C + L1 + L2 exceeds 2000 mAh, the icon 2 changes to the icon 3. Next, it is determined whether or not the power is turned off (step S911). When the power is turned off (step S911: Yes), a series of processing is terminated. If the power is not cut off (step S911: No), the process returns to step S903.

(Example 3)
Further, the battery voltage is affected by temperature. Therefore, the information terminal is configured to correct the temperature difference. Since the detection result of the temperature detection circuit 42 is taken into the CPU 10 as digital data, the CPU 10 knows the battery temperature. Here, measurement of the remaining battery level of the information terminal in consideration of the battery temperature will be described. The configuration of the information terminal of this embodiment is the same as that shown in FIG.

  FIG. 10 is a graph of discharge characteristics in which a temperature parameter is added to the voltage measurement result. When the temperature is 40 ° C., 20 ° C., 0 ° C., −10 ° C., and −20 ° C., the battery voltage is higher as the temperature is higher. When it is detected that the battery voltage at the start-up is 4.0 V, from this graph, when the temperature is 40 ° C., the already discharged capacity is 400 mAh. In the case of −10 ° C., the already discharged capacity is 50 mAh. Thus, the graph of the discharge characteristics used varies depending on the temperature. And the process after selecting a graph according to measurement temperature is the same as Example 1. FIG.

  For example, it is assumed that the battery voltage acquired when the information terminal is activated is 3.9 V, and the temperature at that time is 20 ° C. In this case, it can be seen from FIG. 10 that 600 mAh has been discharged. Then, after the information terminal is activated, the icon 1 is displayed.

  As described above, after the power is turned on, the load size can be calculated, and the power consumption can be calculated from the load size and the elapsed time. As a result, if the battery voltage is measured when the power is turned on, the remaining battery level at that time can be obtained by subtracting from the remaining battery level obtained at that time. Thereby, it is not necessary to measure the battery voltage again after the power is turned on, and the processing burden on the information terminal due to repeated measurement of the battery voltage can be suppressed. Further, since the measurement of the remaining battery level does not depend on the measurement accuracy of the battery voltage, the remaining battery level can be measured more accurately, and the remaining battery level can be managed more appropriately.

The block diagram explaining an example of a structure of an information terminal. Explanatory drawing explaining the average consumption current by the steady load according to operation mode. The graph which shows the discharge characteristic at the time of main body starting. Explanatory drawing explaining the example of a display of the icon which shows battery remaining charge. The flowchart of a battery remaining amount display process at the time of power activation. The flowchart of the battery remaining amount display process corresponding to the operation mode of an apparatus. Explanatory drawing explaining the relationship between LCD backlight brightness | luminance and an electric current value. Explanatory drawing explaining the relationship between the operation mode of HDD, and an electric current value. The flowchart of the battery remaining amount display process corresponding to the operation mode of components. A graph of discharge characteristics in which temperature parameters are added to voltage measurement results.

Explanation of symbols

10 CPU, 12 LCD backlight, 14 HDD, 18 display unit, 20 battery, 22 DC / DC converter, 30 AD converter, 32 RAM, 34 ROM, 40 voltage detection circuit, 42 temperature detection circuit

Claims (8)

An information terminal having a drive unit that operates in response to power supply from a rechargeable battery,
Detecting means for detecting a battery voltage of the battery before supplying power to the driving unit;
Determining means for determining an operation mode of the information terminal;
Calculation means for obtaining power consumption from the load on the battery when operating in the operation mode determined by the determination means and the operation time in the operation mode;
From the battery voltage and the power consumption obtained by the calculating means, measuring means for obtaining the remaining amount of the battery,
An information terminal comprising:   The operation mode of the information terminal is a type of information processing realized in the information terminal by operating the driving unit, and the calculation means calculates the load according to the type of information processing and the information processing The information terminal according to claim 1, wherein the power consumption by the information processing is obtained from a time elapsed in execution.   The operation mode of the information terminal is the type of operation of the drive unit, and the calculating means consumes the load according to the type of operation of the drive unit and the time that the drive unit has been operated. The information terminal according to claim 1, wherein power is obtained.   The information terminal according to any one of claims 1 to 3, wherein the calculation means obtains the power consumption by multiplying a load on the battery and an operation time in the operation mode.   The calculation means obtains an initial value of power consumption by subtracting the remaining battery level based on the battery voltage detected by the detection means from the remaining battery level in the case of full charge, and sets the initial value to the battery. The information terminal according to claim 4, wherein the power consumption is obtained by adding a value obtained by multiplying a load and an operation time in the operation mode.   Temperature detecting means for detecting temperature; and the calculating means calculates a value based on the temperature detected by the temperature detecting means and the battery voltage detected by the detecting means from the remaining battery level when fully charged. The information terminal according to claim 5, wherein an initial value of the remaining battery level is obtained by subtraction.   The information terminal according to claim 1, further comprising display means for displaying information indicating a remaining battery level measured by the measurement means on a display. A battery remaining amount calculation method for an information terminal having a drive unit that operates in response to power supply from a rechargeable battery,
A detection step of detecting a battery voltage of the battery before supplying power to the driving unit;
A determination step of determining an operation mode of the information terminal;
A calculation step for obtaining power consumption from the load on the battery when operating in the operation mode determined by the determination step and the operation time in the operation mode;
From the battery voltage and the power consumption determined by the calculation step, a measurement step for determining the remaining amount of the battery;
The battery remaining charge calculation method characterized by including.

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