JP2008139070A - Electronic device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To achieve an electronic device for obtaining a remaining usage time linearly reduced in response to an elapsed actual time. <P>SOLUTION: The electronic device comprises: a battery microcomputer 1 for storing information on a remaining capacity in a battery and information on a current in the battery; a remaining time linearizing table 6 for storing correction information for correcting the information on the remaining capacity in the battery; and a main microcomputer 2 for calculating the remaining usage time linearly reduced in response to the elapsed actual time based on the information on the remaining capacity in the battery corrected by the correction information and the information on the current in the battery, and can obtain the remaining usage time linearly changed in response to a change in the actual time. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

    The present invention relates to an electronic device.

    2. Description of the Related Art In recent years, some electronic devices that operate on a battery are provided with a function of displaying a remaining use time for displaying the remaining use time of a battery in minutes in addition to displaying three to four bars.

    Such an electronic device will be described below.

    Conventionally, when displaying the remaining battery capacity in minutes in an electronic device, Patent Document 1 uses a current integration technique, and corrects the remaining battery capacity value using various numerical tables for the integrated current value. A technique for obtaining the remaining usage time after obtaining a more accurate remaining battery capacity is known.

    FIG. 9 shows a configuration diagram of main parts of the electronic device. In FIG. 9, 1 is a battery microcomputer, 2 is a main body microcomputer, 3 is a display device, 4 is a battery remaining amount calculation register, and 5 is a current display register. The battery microcomputer 1 processes information in the battery. The main body microcomputer 2 acquires information in the battery from the battery microcomputer 1 and calculates the remaining usage time. The battery remaining amount calculation register 4 stores the calculation result of the remaining usage time. The current display register 5 holds the currently displayed value. The display device 3 displays the contents of the current display register 5 storing the result calculated by the main body microcomputer 2.

    The operation of the conventional electronic apparatus configured as described above will be described below with reference to FIGS.

    FIG. 2 shows a discharge voltage characteristic in which a change in terminal voltage of a lithium ion battery frequently used in portable devices is graphed. The vertical axis represents voltage (V), and the horizontal axis represents the remaining battery capacity ratio. The terminal voltage of a general lithium ion battery shows a change as shown in FIG. That is, in the high capacity portion near full charge (100% to 85%), the terminal voltage rapidly decreases in the initial portion, but gradually changes in the subsequent portion, and gradually decreases as the remaining battery capacity decreases. . In the intermediate capacity (75% to 15%) portion, the terminal voltage hardly decreases even if the remaining battery capacity decreases. In the low capacity (15% to 0%) portion, the terminal voltage rapidly decreases as the remaining battery capacity decreases, and reaches the end-of-discharge voltage.

    On the other hand, FIG. 3 is a graph showing changes in the average power consumption of the device. The vertical axis represents power (W), and the horizontal axis represents the remaining battery capacity ratio (%). When a switching regulator is used in the power supply circuit and the portable device is dominated by a load such as an LSI or motor, the change in average power consumption (W) is usually caused by changes in battery capacity and battery terminal voltage. It is constant regardless of.

    FIG. 4 shows changes in the discharge current (A) from the battery. The vertical axis represents current (A), and the horizontal axis represents the remaining battery capacity ratio (%). The change in current (A) increases from the power formula “power (W) = voltage (V) × current (A)” as the remaining battery capacity ratio (%) decreases as shown in FIG. It shows a change that is upside down with respect to the change in voltage (V).

    In other words, the current (A) changes in the high-capacity part (100% to 85%) close to full charge. The discharge current (A) value increases rapidly in the initial part, but the subsequent part Then, it changes slowly and gradually increases as the capacity decreases. In the intermediate capacity portion (75% to 15%), even if the capacity decreases, the value of the discharge current (A) hardly increases. In the low capacity portion (15% to 0%), the value of the discharge current (A) increases rapidly as the remaining battery capacity decreases.

    FIG. 5 shows a change in average discharge current value (mA) per unit time from the battery. The horizontal axis represents the remaining usage time ratio. The discharge time required for fully discharging a fully charged battery is defined as 100%, and the whole is divided in increments of 5%. The reason for setting 5% increments is that in this embodiment, the complete discharge time is 20 minutes, so 5% increments correspond to 1 minute, and 5% increments represent unit time (1 minute).

    The vertical axis represents the average discharge current value (mA) per unit time. As described above, since each step of the horizontal axis corresponds to a unit time (1 minute), the area of the bar graph represents the average discharge current value (mA), and the following description will be made with one square in the figure as one unit. Therefore, it means that discharging is performed with an average current (mA) of 3.5 units in the first minute, and discharging is performed with an average current (mA) of 3.75 units in the next minute.

    FIG. 6 is a graph in which the remaining battery capacity (mAh: milliampere hour) actually discharged from the battery is integrated per unit time. In other words, as shown in the graph, the remaining battery capacity (mAh) of 6.0 units remains 1 minute before the end of discharge, and the current (mA) of 6.0 units is applied for 1 minute before the end of discharge. This means that the battery has been discharged and the capacity charged in the battery has become empty. Also, 2 minutes before the end of discharge, 11.0 units of remaining battery capacity (mAh) remained, and 5.0 units of current (1 minute before the end of discharge until 1 minute) mA) is discharged. As a result, a battery remaining capacity (mAh) of 6.0 units remained in the battery 1 minute before the end of discharge.

In the figure, this process is repeated, and the remaining battery capacity (mAh) per unit time (in this case, 1 minute) is integrated as an area of 1 square unit, going back to the fully charged state, and graphed. That is, in the fully charged state, there is a remaining battery capacity (mAh) of 83 units, and thereafter, discharging is performed at a current of 3.5 units (mA) in the first minute after full charging. The 3.5 unit current (mA) is an average discharge current (mA) in a unit time (1 minute) of 100% to 95% in FIG. As a result, the remaining battery capacity (mAh) after the first minute has elapsed is 79.5 units. If this is repeated and all the remaining battery capacity (mAh) is discharged, the remaining battery capacity becomes zero.
JP 2002-125321 A

    However, using the formula of “remaining usage time (minutes) = 60 minutes × (remaining battery capacity (mAh) / discharge current (mA))”, the remaining battery capacity (mAh) per unit time is calculated as the remaining battery capacity ratio. When the remaining usage time is calculated by dividing by the average current (mA) per unit time according to (%), it becomes the value of the remaining usage time calculation value (minute) shown below the bar graph of FIG. The result of the calculated remaining usage time (minutes) calculated for each unit time is different from the originally expected change, and decreases linearly with the passage of time of discharge, that is, continuously decreases at a constant value every minute. do not do.

    From the relationship between FIG. 6 and FIG. 5, for example, the remaining usage time calculated value (minute) calculated in the first one minute is “24 minutes = 83 (mAh) /3.5 (mA)”. The remaining usage time calculation value (minute) calculated in 1 minute is “21 minutes = 79.5 (mAh) /3.75 (mA)”, and the remaining usage time is calculated for the unit time (1 minute). Then it will decrease by 3 minutes to 21 (minutes).

    From this, it can be seen that if the calculation of the remaining usage time calculation value (minutes) is first calculated near full charge, it is too large. In addition, there is a problem that, in the initial stage, the actual usage time changes at a pace that is reduced by 2 minutes or more every minute, and the change in the remaining usage time calculation value is not a linear change with respect to the actual usage time.

  An object of the present invention is to solve such a problem and to realize an electronic apparatus capable of obtaining a remaining use time that linearly decreases with the passage of real time.

    In order to solve this problem, the present invention provides a storage unit that stores battery remaining capacity information and battery current information, a correction information holding unit that stores correction information for correcting the remaining battery capacity information, and the correction information. And a calculation unit that calculates a remaining use time that decreases linearly with the passage of real time from the remaining battery capacity information corrected in step 1 and the battery current information.

    With the electronic device of the present invention, the remaining usage time that decreases linearly with the passage of real time can be obtained.

  An electronic apparatus according to the present invention includes a storage unit that stores battery remaining capacity information and battery current information, a correction information holding unit that stores correction information for correcting the battery remaining capacity information, and a battery that is corrected with the correction information. A calculation unit that calculates a remaining usage time that linearly decreases with the passage of real time from the remaining capacity information and the battery current information; With this configuration, when displaying the remaining usage time, it is possible to prevent the initial display value from being too large, and every time one minute has elapsed from the portion near the full charge to the end of discharge. In addition, the remaining usage time display can continue to change linearly by 1 minute.

  Hereinafter, the best mode of the electronic apparatus according to the present invention will be described with reference to FIGS. 1, 6, 7, and 10.

(Embodiment 1)
FIG. 1 shows a main configuration of an embodiment of an electronic apparatus according to the present invention. 1 is a battery microcomputer (corresponding to a storage unit), 2 is a main body microcomputer (corresponding to a calculation unit), 3 is a display device, 4 is a battery remaining amount calculation register, and 5 is a current display register. , 6 is a remaining time linearization table (corresponding to a correction information holding unit).

    The main body microcomputer 2 has a remaining time linearization table 6. The main body microcomputer 2 determines the coefficient of the remaining time linearization table 6 to be applied according to the information acquired from the battery microcomputer 1 and adds the remaining capacity correction value calculated by integrating the remaining battery capacity to the remaining battery capacity calculation register. 4 is stored.

    The main body microcomputer 2 divides the value of the battery remaining amount calculation register 4 by the current information (corresponding to the battery current information) or the estimated current consumption at that time, thereby obtaining the calculated remaining battery usage time (minutes) of the electronic device. . Estimated current consumption refers to the estimated current consumption in the operation state based on the current information in the preparation stage at the preparation stage (corresponding to one of the modes) for the operation state (corresponding to one of the modes) of the device body. In the operating state of the device main body, it means current consumption information itself in the operation stage. That is, by dividing by the estimated current consumption, a sudden change in the remaining usage time can be suppressed. Note that the above-described mode means that when the electronic device is an electronic device having a camera function for shooting a subject, the subject is captured during shooting of the subject or before shooting is started (also referred to as a so-called through image). State. Note that the estimated current consumption as used in the present invention is not limited to before / beginning of shooting, and whether each part constituting the device main body or the device is activated before the active state, such as being displayed on the display unit or attached display. Any current consumption can be applied as long as the current consumption in the state is known in advance.

    Here, how to obtain the remaining time linearization table 6 will be described with reference to FIGS. FIG. 7 shows a change in the remaining capacity correction value (mAh) with respect to the remaining battery capacity ratio. Here, the dotted line in the figure represents the remaining battery capacity before correction, the solid line represents the remaining capacity correction value, and the bar graph in each section where the masses gathered (in the remaining capacity ratio in increments of 5%) represents the remaining capacity correction value. To express. The calculated remaining capacity correction value (mAh) is calculated by dividing the remaining capacity correction value (mAh) for each unit time by the average current (mA) in that section. The remaining battery capacity is corrected so as to increase linearly by 1 (minute) and change linearly up to the first full charge value. In other words, by correcting the remaining battery capacity (mAh) in advance according to the part where the current value changes near the full charge and near the end of discharge, the calculated remaining usage time during discharge changes linearly. To do.

    In other words, 20 minutes, 19 minutes ... 3 minutes, 2 minutes, 1 minute, 0 minutes, "remaining usage time (minutes) = 60 minutes x (remaining capacity correction value (mAh) / discharge current (mA)) The remaining capacity correction value (mAh) is also changed according to the discharge current (mAh) that changes in the middle so that the calculation results of " To be.

    Using the above results, the result of dividing the remaining capacity correction value (mAh) of each section by the remaining battery capacity (mAh) of each section before the correction is used, starting from 0 (mAh), one minute later. By performing all the steps, the coefficient of each section for correcting the remaining battery capacity (mAh) is obtained.

    By repeating this until full charge, a table of coefficients that can be corrected so that the remaining usage time calculation value (minute) changes linearly over the entire discharge period is obtained.

    In other words, once the curve of the discharge current of the battery is determined, the remaining time linearization table, which is a collection of coefficients for correction, is calculated by retroactively calculating the discharge process from 0 (mAh). You can ask. That is, the remaining time linearization table is a collection (table) of correction coefficients corresponding to various conditions obtained by simulation using the above method.

    Further, the remaining time linearization table is a value obtained by dividing the remaining capacity correction value (mAh) of the simulation result of each section by the remaining battery capacity (mAh) of each section, and is simply an anonymous number indicating the ratio.

    As a specific calculation order, first, the remaining capacity correction value (increase the value until the battery is fully charged while increasing the remaining time by 1 (minute) from 0 (mAh). Determine the value of mAh).

    Looking at FIG. 6, the remaining 15% to 0% sections are 3 minutes, 2 minutes, 1 minute, 0 minutes, “remaining usage time (minutes) = 60 minutes × (remaining capacity correction value (mAh) / Discharge current (mA)) "is calculated every minute. This is because the discharge current (mAh) changes in the middle, but the absolute value of the remaining capacity ability value (mAh) is small, and the current change has little effect on the calculation result of the remaining usage time (minutes). This is because the remaining usage time (minutes) is a continuous value on the surface because it is less than a minute unit. That is, in the region where the absolute value of the remaining battery capacity (mAh) is small and the influence of the current change on the calculation result of the remaining usage time (minutes) is less than one minute, no correction is necessary. In the previous 20% to 15% interval, the remaining usage time (minutes) is calculated as 5 minutes, and the values are not continuous. This is because the current change is large after this period, and at the same time, the influence of the current change on the calculation result of the remaining usage time (min) can be ignored in the part where the absolute value of the remaining battery capacity (mAh) is large to some extent. This is because an error exceeding 1 minute occurs. That is, the remaining battery capacity (mAh) needs to be corrected in a region where the remaining battery capacity (mAh) is large to some extent and the error exceeds 1 minute.

    From the above, in the interval from 20% to 15%, the remaining battery life (mAh) 20 (mAh) is corrected to the remaining capacity correction value 16 (mAh), thereby calculating the remaining usage time (minutes). Can be set to 4 minutes, and the value can be changed linearly and continuously. Back-calculating from this result, the correction coefficient in the section of 20% to 15% is 0.80 = 16 (mAh) / 20 (mAh).

    Similarly, by correcting the remaining battery capacity (mAh) of 24 (mAh) between 25% and 20% to the remaining capacity correction value of 20 (mAh), the remaining usage time (minutes) is calculated as 5 minutes. And the value can be changed continuously linearly. Back-calculating from this result, the correction coefficient in the section from 25% to 20% is 0.83 = 20 (mAh) / 24 (mAh).

    Similarly, by repeating the remaining battery capacity 79.5 (mAh) in the section from 95% to 90% to the remaining capacity correction value 71 (mAh), the calculation result of the remaining usage time (min) is 19 Minutes, and the value can be changed linearly and continuously. Back-calculating from this result, the correction coefficient in the section from 95% to 90% is 0.89 = 71 (mAh) /79.5 (mAh).

    Similarly, the remaining battery capacity 83 (mAh) in the first section in which discharge starts from 100% to 95% full charge is corrected to the remaining capacity correction value 70 (mAh), thereby remaining usage time (minutes). ) Can be calculated as 20 minutes, and the value can be changed linearly and continuously. The correction coefficient in the range from 100% to 95% is 0.84 = 70 (mAh) / 83 (mAh).

    Here, the value of the remaining capacity correction value (mAh) in the portion near 100% full charge will be considered. In this simulation, the remaining capacity correction value (mAh) is calculated over the entire area, and when the calculation results are arranged from 0% to 100%, the remaining capacity correction value (mAh) is From 100% to 0%, the remaining capacity will surely decrease if it is used. This is because, generally, as a characteristic of the battery, a change in the current value is abruptly changed near 100% full charge.

    That is, the current in the section from 95% to 90% changes abruptly to 3.5 (mA) while the current in the section from 100% to 95% changes to 3.75 (mA). For the remaining capacity correction value 71 (mAh) in the 90% section, a correction coefficient that reverses the magnitude of the remaining capacity correction value 70 (mAh) in the section from 100% to 95% is required.

    That is, the coefficient for correction in the section from 95% to 90% is 0.88, whereas the coefficient for correction in the section from 100% to 95% is 0.84, which is larger than the correction coefficient in the portion far from full charge. The correction coefficient in the portion near full charge performs stronger correction.

    As shown in FIG. 2, in general, the voltage of the battery does not change linearly with respect to the remaining capacity ratio, and thus has a characteristic of being bent with respect to the actual use time. When the changing voltage is combined with the constant power load characteristic of a device that uses a switching regulator, the current characteristic of the battery is the reverse of the voltage characteristic of the battery, so the battery current characteristic naturally does not change linearly. . As a result, the correction coefficient array does not change linearly, so correction using mathematical formulas is difficult. As a result, the values for each condition are obtained by simulation, and the remaining time linearization table is used. I have to take a correction method.

    Since the central portion of the discharge curve of the battery has relatively little change and the value tends to change linearly, the remaining time linearization table at the central portion of the discharge curve can be roughened.

    On the contrary, both ends of the discharge curve of the battery are relatively large, especially in the portion close to full charge, the correction coefficient tends to change greatly, so the correction coefficients at both ends of the discharge curve are high. The accuracy cannot be ensured unless it is finely divided.

    Further, it is necessary to create a remaining time linearization table according to the discharge voltage and discharge current curves of various batteries. In particular, a remaining time linearization table in which a sharp change in battery characteristics is finely divided is required.

    In the table for correcting the remaining battery capacity value according to the remaining capacity ratio described in this embodiment, the coefficient is determined by the characteristics of the discharge voltage. The curve representing the characteristics of the discharge voltage varies depending on the type of electrolyte used in the battery and its blending ratio. For example, nickel-metal hydride batteries generally have little voltage change, especially at the center remaining capacity ratio, whereas lithium ion batteries have a gentle voltage change at the center remaining capacity ratio. As the battery discharges, the voltage decreases.

    Further, the curve representing the characteristics of the discharge voltage varies depending on the environmental temperature in which the battery is placed and the internal temperature of the battery even if the battery has the same specification. In general, a high temperature curve does not change so much with respect to a normal temperature curve, but a curve representing a characteristic of a discharge voltage at a low temperature, particularly in a temperature range of 0 ° C. or less, changes greatly. At low temperatures, chemical changes are generally less likely to occur, so the discharge voltage curve of the battery becomes shorter and the voltage decreases more quickly.

    Moreover, even if the batteries have the same specifications, if charging / discharging is repeated, changes with time occur, the discharge voltage curve of the battery gradually decreases, and the voltage decreases more quickly.

    Furthermore, the discharge voltage curve of the battery when viewed at the same capacity ratio varies depending on the power consumption of the device. In general, if the power consumption of the device is large, the discharge voltage curve of the battery becomes short, and the voltage decreases more quickly when viewed at the same capacity ratio as a whole. Conversely, if the power consumption of the device is small, the discharge voltage curve of the battery will be long, and as a whole, the voltage drop will be slow when viewed at the same capacity ratio, and will end sharply at the end. It becomes a curve.

    By creating a plurality of remaining time linearization tables according to the chemical prescription of the battery, temperature, changes over time, and discharge power of the device, switching the remaining time linearization tables to be used according to conditions makes it more detailed. Correction is performed, and the remaining capacity display time can be correctly changed.

    On the other hand, if too many remaining time linearization tables are created and used by switching according to conditions, the table data becomes enormous and the determination program becomes enormous. Therefore, it is important to accurately determine what is the most necessary condition, what is the most commonly occurring condition, and what is the most important condition for the user. Then, as a result of such examination and consideration, it is possible to create a remaining time linearization table by finely correcting important characteristics and dividing other less important corrections to some extent. It leads to restraining quantity.

    The remaining time linearization table is used by determining one coefficient to be obtained from each voltage, each current, each capacity ratio, and each temperature. That is, the coefficient that meets the condition is narrowed down from the remaining time linearization table.

    As a specific method of using the coefficient, as shown in FIG. 7, the coefficient selected from the remaining time linearization table is added to the remaining capacity capacity value (mAh) before correction, which is data from the actual battery, The remaining capacity correction value (mAh) which is the value after the capacity value correction is obtained, and the remaining time (minute) is calculated using the remaining capacity correction value and displayed on the display device.

    With the above configuration, a change in the remaining usage time calculation value (minute) can be made linear, and an excellent effect of providing a battery remaining capacity display (minute) that is trusted by the user can be obtained.

(Embodiment 2)
FIG. 10 shows the configuration of the second embodiment of the present invention. The difference from the first embodiment is that the battery microcomputer 1 has a remaining time linearization table 6. By having the remaining time linearization table 6 in the battery microcomputer 1, the coefficient is added to the remaining battery capacity to obtain a corrected capacity value, and the capacity value is supplied to the main body microcomputer 2 as the remaining capacity correction value. I can do it. As a result, the main body microcomputer 2 obtains only the remaining capacity information that has already been corrected in the battery remaining capacity calculation register 4, and can reduce the amount of data to be received. Then, the main body microcomputer 2 divides the value of the battery remaining capacity calculation register 4 by the current information or the estimated current consumption at that time to obtain the calculated value of the remaining battery usage time of the electronic device as in the first embodiment. .

    With the above configuration, the change in the remaining usage time calculation value (minute) can be made linear, and an excellent effect that the battery remaining capacity display (minute) that is reliable to the user can be provided can be obtained.

    Although the present invention has been described assuming a video camera in the embodiments, the present invention is widely applied to electronic devices having a battery remaining capacity display function, such as digital cameras and mobile phones, which are battery-driven electronic devices other than video cameras. Can be applied.

The principal part block diagram explaining the structure of one Embodiment in the electronic device of this invention Graph explaining changes in battery terminal voltage used in electronic equipment Graph explaining changes in average power consumption of electronic devices Graph explaining changes in discharge current of batteries used in electronic equipment Graph explaining average discharge current value change per unit time from batteries used in electronic equipment Graph explaining changes in remaining battery capacity of batteries used in electronic devices The graph explaining the change of the remaining capacity correction value of the battery used in the embodiment Configuration diagram illustrating an example of a remaining time linearization table Main block diagram for explaining the configuration of a conventional electronic device The block diagram explaining the principal part structure of other embodiment in the electronic device of this invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Battery microcomputer 2 Main body microcomputer 3 Display apparatus 4 Battery remaining capacity calculation register 5 Battery remaining capacity display register 6 Remaining time linearization table

Claims (2)

A storage unit for storing battery remaining capacity information and battery current information;
A correction information holding unit that stores correction information for correcting the remaining battery capacity information;
An electronic device comprising: a calculation unit that calculates a remaining use time that linearly decreases with the passage of real time from the remaining battery capacity information corrected with the correction information and the battery current information. The calculation unit calculates a remaining use time that linearly decreases with the passage of real time from the remaining battery capacity information corrected by the correction information, the battery current information, and the estimated current consumption estimated from the mode of the device body. The electronic device according to claim 1.