JPH1090377A - Method for detecting service life of battery - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent the occurrence of power cut-off caused by continuous load switching by discriminating the operable state at each load based on the voltage variation of the battery detected at the time of switching the loads. SOLUTION: A timer circuit A 102 periodically sends a battery voltage detection requesting signal 112 to a battery voltage detecting circuit 101 and a storage circuit 111. The circuit 101 detects the voltage of a battery and sends the detected voltage to an arithmetic circuit 109 in the period of the signal 112. The circuit 11 sends the terminating voltage level to the circuit 109 when a light load 104 is continuously executed. The circuit 109 compares the detected voltage of the battery with the terminating voltage level and, when the former is higher, continues the execution of the load 104. When the detected voltage is lower, the circuit 109 stops the execution. When the detected voltage is higher, the circuit A 102 generates the signal so as to repeat the same process after a fixed period of time and, when the detected voltage becomes lower than the terminating voltage level, the execution of the load 104 is stopped. Even for a normal load 105 and a heavy load 106, the residual capacity of the battery is completely consumed by performing similar processing at each terminating voltage level.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] 1. Field of the Invention [0002] The present invention relates to a battery life detecting method in a battery driving device for supplying power from a battery to a plurality of types of load circuits.

[0002]

2. Description of the Related Art In recent years, devices which are driven by a battery as a power source have been increasing due to miniaturization and power saving of devices. A typical example of such a device is a portable information terminal or a personal computer. Particularly, in a portable information terminal, a load that requires little power (a light load) such as an electronic organizer function, a load (normal load) in a standby state of a communication function, and a load (heavy load) that requires a large amount of power such as a communication function Load) are mixed.

A conventional battery life detecting method in such a battery driving device will be described with reference to FIG. FIG. 3A shows the discharge characteristics of the battery when three types of loads are used continuously. The vertical axis 40 indicates the battery voltage, and the horizontal axis 41 indicates the time. A characteristic curve 42 is a discharge curve when light loads are continuously executed, a characteristic curve 43 is a discharge curve when normal loads are continuously executed, and a characteristic curve 44 is a discharge curve when heavy loads are continuously executed. Is shown. The voltage level 50 is a cut-off voltage at which the battery life (life expires) with a light load 42, and the voltage level 51 is a normal load 4
The reference voltage 3 indicates the end voltage at which the battery life is reached, and the voltage level 52 indicates the end voltage at which the heavy load 44 reaches the end of battery life. The voltage level at which the battery lasts depends on the load. The reason is that the voltage drop due to the internal impedance of the battery differs depending on the load. Since a large current flows under a heavy load, a voltage drop due to the internal impedance of the battery increases. As a result, the voltage level at which the battery lasts is reduced.

In a battery driving device, a DC / DC converter (hereinafter referred to as a power supply circuit) generates a plurality of types of voltages based on a supply voltage from the same battery and supplies power to each load. In this power supply circuit, the minimum value of the input voltage differs depending on the type. This is because required characteristics (output voltage, output current, etc.) differ depending on the type of power supply circuit. For this reason, even if the load is light, the battery cannot always be used until the remaining capacity of the battery is smaller than that of the normal load. For example, the communication function standby function (light load) and the communication function (heavy load) of the portable information terminal
Operates only at 5 V of the power supply circuit, and the electronic organizer function (light load) requires 5 V of the power supply circuit and 30 V for the display function. This apparatus uses two dry batteries as a power source. As a result, a voltage between the initial voltage of 3.2 V of the dry battery and the voltage of 0.0 V when the remaining battery level is completely exhausted is input to each power supply circuit. The power supply of 5 V for the electronic organizer function and the communication function is 1.8 V because the boost amount is small.
It operates up to V battery voltage. However, 30V of display function
In the power supply, the amount of boosting increases because the output voltage of the power supply circuit is high, and the input voltage of the power supply circuit requires 2.0 V. For this reason, the communication function operates up to the battery voltage of 1.8 V, and the operation of the electronic organizer function is up to 2.0 V.

In a battery, a larger current flows as the load becomes heavier,
Since a battery has an internal impedance, the larger the current, the lower the battery voltage. Therefore, even if the batteries have the same remaining capacity, the battery voltage decreases as the load increases. In the standby function of the communication function, the load is lighter than that of the communication function. Therefore, the required remaining capacity is lost when the battery voltage is high. In this case, the remaining capacity is insufficient at 1.9 V. Therefore, the standby function of the communication function cannot operate the power supply circuit up to the minimum operating voltage of 1.8 V, and the minimum operating voltage is 1.9 V.

On the other hand, in the communication function, the battery voltage is 1.8 V
In the state of, sufficient remaining capacity remains. However, since the minimum input voltage of the power supply circuit is 1.8 V, the minimum operation voltage is 1.8 V. The electronic organizer function has a battery voltage of 2.
In the state of 0 V, the remaining capacity is sufficient. However, since the minimum input voltage of the power supply circuit is 2.0 V, the minimum operation voltage is 2.0 V.

When the remaining capacity of the battery at the end voltage of each function is compared, the load of the communication function is heavy, so the amount of drop of the battery voltage due to the internal impedance is large, and the communication voltage becomes the end voltage with the most remaining capacity. In the electronic organizer function, the final voltage of the power supply circuit is as high as 2.0 V, but the remaining capacity is smaller than that of the communication function because the load is light and the amount of battery voltage drop due to the internal impedance is small. In the standby function of the communication function, the remaining capacity is smaller than that of the electronic organizer function because all the capacity that can execute the load is used up (the standby function of the communication function uses up all the battery capacity. For example, when the electronic organizer function is operated with the ideal power supply, the cutoff voltage is 1.95 V. In this state, the cutoff voltage of the communication function standby function is 1.9 V.
The remaining capacity of the battery is smaller than that. This is because the heavier the load, the more the remaining capacity cannot be executed in a state where the remaining capacity is left. ).

The change in the battery voltage when the load is switched in the battery immediately before the end of the battery life will be described with reference to FIG. The same components as those in FIG. 3A are denoted by the same reference numerals. In FIG. 3B, the vertical axis 40 indicates the battery voltage, and the horizontal axis 41 indicates time. (B) of FIG. 3 shows that the remaining capacity of the battery capable of executing the load can be executed even if the (1) normal load has a smaller remaining capacity of the battery than a light load;
(2) The description will be made on the assumption that a light load can be executed even if the remaining capacity of the battery is smaller than a heavy load. The characteristic curve 60 shows the cut-off voltage level 50 during continuous light load operation.
The characteristic curve 61 is a change curve of the battery voltage when the load is switched to the normal load, and the characteristic curve 61 is a change curve of the battery voltage when the load is switched to the heavy load at the end voltage level 50. Change curve of battery voltage and characteristic curve 6 when switching to light load at end voltage level 51
Reference numeral 3 denotes a battery voltage change curve when the load is switched to a heavy load in the state of the end voltage level 51, and a characteristic curve 64 denotes a battery voltage when the load is switched to a light load at the end voltage level 52 while the heavy load is continuously executed. Change curve, characteristic curve 65
Is a change curve of the battery voltage when the normal load is switched in the state of the end voltage level 52. Voltage level 53
Is a battery voltage that is stable under a normal load in the battery voltage change curve 60, a voltage level 54 is a battery voltage that is stable under a heavy load in the battery voltage change curve 61, and a voltage level 55 is a battery voltage that is stable under a light load in the battery voltage change curve 62. The voltage level 56 is a stable battery voltage at a heavy load on the battery voltage change curve 63, the voltage level 57 is a stable battery voltage at a light load on the battery voltage change curve 64, and the voltage level 58 is a normal load on the battery voltage change curve 65. This shows a stable battery voltage. A characteristic curve 66 indicates a change in the battery voltage when the load is switched from a light load to a heavy load, and is a battery voltage change curve stabilized at the cut-off voltage level 52 of the heavy load particularly after switching to the heavy load. The characteristic curve 67 shows a change in the battery voltage when the load is switched from the normal load to the light load, and is a battery voltage change curve which is stabilized particularly at the end voltage level 50 of the light load. Characteristic curve 68
Shows a change in the battery voltage when switching from the normal load to the heavy load, and is a battery voltage change curve that is stabilized particularly at the end voltage level 52 of the heavy load.

Next, the change in battery voltage when the load is switched in the battery immediately before the battery life will be described.

As can be seen from the battery voltage change curve 61,
When the load is switched to a heavy load with a battery just before the battery life under a light load, the battery voltage drops to a value lower than the cut-off voltage level 52 of the heavy load, so that a power cutoff for device protection occurs. This is because a light load can be executed in a state where the remaining capacity of the battery is small, so that it cannot be executed with a heavy load, and the control circuit executes power cutoff control. For the same reason, as shown by the battery voltage change curves 62 and 63, when the battery is switched to a light load or a heavy load immediately before the battery life under the normal load, the battery voltage becomes lower than the end voltage level 50 and the end voltage level 52. And the power is cut off. The voltage of the light load before switching to the heavy load in the battery voltage change curve 66 is the voltage level 5 stable at the light load in the battery voltage change curve 64.
Same as 7. This is because the battery voltage change curve 64 and the battery voltage change curve 66 are stable just before the end voltage level 52 of the heavy load. In the battery voltage change curve 67, the voltage of the normal load before switching to a light load becomes the same as the voltage level 53 stabilized in the normal load in the battery voltage change curve 60. In the battery voltage change curve 68, the voltage of the normal load before switching to the heavy load becomes the same as the voltage level 58 stabilized in the normal load in the battery voltage change curve 65. The setting of the cut-off voltage level in the conventional battery drive device is performed so that the power supply is not interrupted when all combinations of loads are switched. This can be realized by switching the loads in all combinations in a state immediately before the power interruption occurs, and setting the highest voltage among the voltage before the switching and the voltage after the switching as the end voltage level. The end voltage level in the above example is a voltage level 57 that is stable at a light load in the battery voltage change curve 64 in a state where a heavy load is switched to a light load.

[0011]

By the way, according to the above-mentioned conventional technique, in order to prevent the power supply from being interrupted even if the loads are switched in all combinations, the battery voltage change curve 64 is stable at a light load. The voltage level 57 to be applied is set as the end voltage. However, the state in which the power is cut off at the voltage level 57 is only when the load is switched from a light load to a heavy load. In other states, the battery is usable but the life of the battery is exhausted. The batteries could not be used up. When the load is continuously executed, it is possible to determine whether or not a power failure occurs by checking the battery voltage before switching the load. For example, when switching from the normal load to the heavy load, it can be seen that if the voltage level 58 is stable at the normal load in the battery voltage change curve 65 or higher, no power interruption occurs, and the battery voltage change curve 65 stabilizes at the normal load. It can be seen that if the voltage level is lower than the voltage level 58, the power is cut off. In the battery voltage change curve 65, a voltage level 58 stabilized under a normal load is set as a threshold,
It is sufficient to determine whether to switch the load. Similarly,
When switching from the normal load to the light load, the voltage level 53 stable at the normal load in the battery voltage change curve 60 is shown.
It can be determined whether or not to switch the load using the threshold as a threshold. When switching from a light load to a normal load, the normal load can be executed even when the remaining battery level is small, so that the normal load can be switched unconditionally. Similarly, when switching from a heavy load to a light load and a normal load, the switching is performed unconditionally. As a result, the battery can be used up.

However, if the load is switched continuously before the battery voltage reaches a stable state, the battery life cannot be determined based on the threshold value, and a power failure occurs. Further, there is a case where the load cannot be switched even though the remaining battery power is sufficient. Further, the load being executed may be stopped immediately after switching the load, even though the remaining battery power is sufficient.

An object of the present invention is to provide a battery life detecting method adapted to the magnitude of the power of a load, and particularly to accurately detect the battery life even when a load switch occurs before the battery voltage is stabilized. Regardless of the load power,
It is an object of the present invention to provide a battery life detecting method that can effectively use battery capacity.

More specifically, it is possible to prevent a power-off from being caused by a request to switch to the next load during a period in which the battery voltage is falling due to the switching of the load.

Further, when a request for switching to the next load occurs while the battery voltage is rising due to the switching of the load, the load can be switched even though the remaining battery power is sufficient. Prevent loss.

Further, even though the remaining battery level is sufficient immediately after the switching of the load, the running load is stopped because the battery voltage has not risen to the final voltage level of the switched load. Prevent it from getting lost.

[0017]

In order to achieve the above object, there is provided a battery, a means for detecting a battery voltage, a plurality of loads, a means for switching between the plurality of loads, and a means for recognizing the load to be switched. In a battery driving device, in a battery life detecting method for determining whether or not operation at each load is possible by detecting a battery voltage, there is provided means for detecting a temporal fluctuation amount of a battery voltage when a load is switched, It is determined whether or not each load can operate based on the amount of voltage fluctuation. In addition, the end voltage level of the battery specified for each load is stored, and the end voltage level is compared with the battery voltage to determine whether or not operation is possible at each load, and the end voltage level is changed by each load.

Further, a means for switching a plurality of loads requiring different amounts of power, a means for recognizing a load currently being executed and a load requested to be switched, a means for detecting a battery voltage, and a switch to each load. Storage means for storing in advance the amount of fluctuation of the battery voltage and a calculation means, and the load executed before the load currently being executed, and the load being executed by the battery voltage detection means, the load recognition means and the calculation means. From the battery voltage when switching to the currently running load and the battery voltage when there is a load switching request and the amount of change in battery voltage per unit time from the elapsed time of the currently running load, the calculated battery The end voltage is changed for each load by comparing the amount of voltage fluctuation with a value stored in the storage means in advance and determining whether switching to the load requested to be switched is possible. To be able, it can to use up capacity that is stored in the battery, to be able to increase the time used by the battery driving.

[0019]

Embodiments of the present invention will be described with reference to the drawings.

FIG. 4A explains the concept of the object of the present invention. 3 (a) and 3 (b) are denoted by the same reference numerals. This embodiment can be executed even when the remaining capacity of the battery capable of executing the load is smaller than the load in which the remaining capacity of the battery is lighter, as in the above-described conventional technology. The description will be made assuming that a light load can be executed even if the remaining capacity of the battery is smaller than a heavy load.

FIG. 4A shows a battery voltage change characteristic when the load is continuously switched from a light load to a normal load and further to a heavy load. A characteristic curve 60 is a battery voltage change curve when a light load is switched to a normal load immediately before the light load end voltage level 50, and a characteristic curve 71 is a switch to a heavy load before the battery voltage change curve 60 is stabilized. 3 shows a battery voltage change curve in the case where the battery voltage changes. In this embodiment, since it is assumed that the normal load can be executed with less remaining capacity than the light load, the load is unconditionally switched from the light load to the normal load. Further, in FIG. 4A, it is determined that the battery load can be switched to the heavy load with a battery voltage higher than the threshold voltage level 58 at which the normal load can be switched to the heavy load, and the normal load is switched to the heavy load. ing. This then
The limit voltage level 52 at which the battery voltage can execute a heavy load
Power is cut off. This is because the load was switched before the battery voltage dropped and stabilized on the battery voltage change curve 60. When the load is switched after the battery voltage is stabilized in the battery voltage change curve 60, the load cannot be switched because the battery voltage becomes lower than the threshold voltage level 58 at which the normal load can be switched to the heavy load. Judge. Thus, no power interruption occurs. However, even when it is determined whether or not the load can be switched based on the threshold value, if the load is switched and a next load switching request is issued during a period in which the battery voltage is falling, the power is cut off. (The first problem).

The concept for solving the first problem will be described with reference to FIG. Characteristic curve 7
Reference numeral 4 denotes a change characteristic of the battery voltage when the light load is switched to the normal load in the state of the threshold voltage level 57 at which the light load can be switched to the heavy load. In the battery voltage change curve 74, since the battery is of the limit that can be switched from a light load to a normal load and to a heavier load, even if the load is switched from a light load to a normal load and switched to a heavier load, the load is stabilized at a heavy load. The battery voltage is at the end voltage level 52 of the heavy load and does not cause a power failure.
As described above, the battery voltage change characteristic (curve) 60 when the light load is switched to the normal load immediately before the light load reaches the threshold voltage level 50, and the threshold voltage level at which the light load can be switched to the heavy load Focusing on the amount of battery voltage drop per unit time of the battery voltage change characteristic (curve) 74 when switching from a light load to a normal load at 57, the battery voltage change curve 60 has a lower voltage drop per unit time. large. The battery of the battery voltage change curve 60 has a lower remaining voltage than the battery of the battery voltage change curve 74, and thus has a lower voltage. On the other hand, since the power consumption of the battery voltage change curve 60 is the same as that of the battery voltage change curve 74, the battery of the battery voltage change curve 60 flows more current than the battery of the battery voltage change curve 74. The amount of voltage drop per unit time of the battery in the battery voltage change curve 60 is the battery voltage change curve 74.
The reason why the voltage drop is larger than the voltage drop per unit time of the battery is that the voltage drop due to the internal impedance of the battery is large because a large amount of current flows. From the above, it can be seen that when the load is switched with a battery having a reduced remaining capacity, the amount of voltage drop per unit time increases.

An example of means for solving the first problem by utilizing this voltage drop will be described below. In the case of continuously switching from a light load to a normal load and to a heavier load, if the voltage drop is larger than the voltage drop of the battery voltage change curve 74, the power is turned off. This is because when switching from a light load to a heavy load, the battery voltage can be switched from a light load to a heavy load.
It can also be seen from the fact that if it is lower than this, the power is cut off.

As an example of a case where the load is continuously switched, a state where the load is switched from a light load to a normal load (characteristic curve 60) and a state where the load is switched from a light load to the normal load (characteristic curve 60) to a heavy load (characteristic curve 60). This will be described with reference to a characteristic curve 71).

When switching from the light load to the normal load, the normal load can be executed even when the remaining capacity of the battery is smaller than that of the light load, so that the normal load is unconditionally switched to the normal load. The time width 75 is an elapsed time from when a light load is switched to a normal load to when a request to switch to a heavy load is generated. The voltage drop amount 77 is the elapsed time 7 until a request to switch to a heavy load occurs in a state where the load is switched from a light load to a normal load (characteristic curve 60).
5 shows the battery voltage dropped during 5; The voltage drop amount 76 is
Due to the limit of the battery that can be switched from a light load to a normal load and to a heavier load, during an elapsed time 75 until a request to switch to a heavy load is generated in a state where the load is switched from a light load to a normal load (characteristic curve 74). Shows the dropped battery voltage. The voltage drop amount 76 is a limit voltage drop amount that can be continuously switched from a light load to a normal load and to a heavier load during an elapsed time 75 until a request to switch to a heavy load is issued. When a request to switch to a heavy load occurs after the time 75 from when switching from a light load to a normal load to a request to switch to a heavy load occurs, the limit voltage drop amount 76 at which the load can be switched and the actual Are compared with each other. Since it is determined that the load cannot be switched because the actual voltage drop 77 is larger than the limit voltage drop 76, the load switching is stopped. If it is not possible to determine whether the remaining battery level is sufficient because the battery voltage is falling, determine the amount of battery voltage drop per hour and the amount of battery voltage drop at which the load can be switched. In comparison, when the battery voltage actually dropped is larger, it is determined that the remaining capacity is not left. Thereby, an example of the first problem can be solved.

Next, an example in which the second problem occurs will be described with reference to FIG. The same components as those shown in FIGS. 3A and 3B or FIG. 4A are denoted by the same reference numerals. Here, the case where the remaining capacity of the battery capable of executing the load has the following relationship will be described. The normal load can be executed even when the remaining capacity of the battery is smaller than the light load, and the light load can be executed even when the remaining capacity of the battery is smaller than the heavy load. FIG. 4B shows a battery voltage change characteristic when the load is continuously switched from the normal load to the light load and further to the heavy load. Characteristic curve 72
Is a characteristic curve of the battery voltage change when the load is switched from the normal load to the light load, and a characteristic curve 73 is a characteristic curve of the battery voltage when the load is switched from the state where the normal load is switched to the light load (characteristic curve 72) to the heavy load. Is shown. In the state of the characteristic curve 72, since the battery voltage is higher than the threshold voltage level 53 at which the normal load can be switched to the light load, it is determined that the light load can be switched, and the normal load is switched to the light load. Next, in a state in which the load is switched from a light load to a heavy load (characteristic curve 73), the load cannot be switched to a heavy load because the battery voltage is lower than the threshold voltage level 57 at which the load can be switched from the light load to the heavy load. Is determined. However, in practice, it can be seen that the battery voltage is equal to or higher than the voltage level 58 in the state where the load is switched from the normal load to the light load (characteristic curve 72), so that the remaining capacity enough to execute the heavy load remains. This is because the battery voltage is recovering in a state where the load is switched from the normal load to the light load (characteristic curve 72), and the threshold voltage level 57 at which the battery voltage can be switched from the light load to the heavy load. This is because the next load switching request has occurred before returning. According to the above description, even in the case of determining whether the load can be switched by the threshold value, when a request to switch to the next load occurs while the battery voltage is rising due to switching the load, In some cases, the load cannot be switched even though the remaining battery level is sufficient (second problem).

An example of means for solving the second problem will be described with reference to FIG.
The characteristic curve 87 is a change characteristic curve of the battery voltage when switching from the normal load to the light load. Here, the battery voltage of the normal load before switching to the light load is the threshold voltage level 58 at which the normal load can be switched to the heavy load.

When switching from a normal load to a light load (characteristic curve 87) to a heavy load, the battery voltage stabilized under the heavy load is the final voltage level 5 of the heavy load.
2 and the power is not turned off. Here, a state where the load is switched from the normal load to the light load (characteristic curve 72) and a state where the load is switched from the normal load to the light load by the limit battery that can switch the load from the normal load to the light load and the heavy load (characteristic curve 87). Focusing on the amount of increase in battery voltage per unit time, it can be seen that the amount of increase in voltage per unit time is smaller in the state where the load is switched from the normal load to the light load (characteristic curve 72).

The battery in the state where the load is switched from the normal load to the light load (characteristic curve 72) is the state in which the battery is switched from the normal load to the light load by the limit battery that can switch the load from the normal load to the light load (the characteristic curve 72). 8
Since the remaining capacity is larger than that of the battery of 7), the voltage is high. On the other hand, a state in which the load is switched from the normal load to the light load (characteristic curve 72) and a state in which the load is switched from the normal load to the light load by the limit battery capable of switching from the normal load to the light load and further to the heavy load (characteristic curve 87). Since the power consumption is the same, the state where the normal load is switched to the light load (characteristic curve 72) is the normal load to the light load,
The state where the load is switched from the normal load to the light load by the limit battery that can be switched to the heavier load (characteristic curve 8
Less current than 7).

State 7 in which normal load is switched to light load
(2) Voltage rise per unit time in a state where the load is switched from a normal load to a light load by a battery of a limit that can switch from a normal load to a light load to a heavier load (characteristic curve 87). The reason for this is that the voltage rise based on the internal impedance of the battery is small because the current is small. As described above, when the load is switched using a battery with a large remaining capacity,
It can be seen that the voltage rise per unit time is small.

An example of means for solving the above-mentioned second problem by utilizing the amount of voltage rise will be described below. When switching from normal load to light load and then to heavy load continuously, the amount of voltage rise when switching from normal load to light load can be switched from normal load to light load and even heavy load. If it is larger than the amount of voltage rise in a state where the load is switched to a light load (characteristic curve 87), the power is cut off. This is because when switching from the normal load to the heavy load, the battery voltage can be switched from the normal load to the heavy load.
It can also be seen from the fact that if it is lower than this, the power is cut off.

As an example of a case where the load is continuously switched, a state where the normal load is switched to a light load (characteristic curve 72) and a state where the normal load is switched to a light load (characteristic curve 72) are switched to a heavy load (characteristic curve 72). This will be described with reference to a characteristic curve 73). When switching from a normal load to a light load, the load is switched to a light load because the battery voltage is equal to or higher than the threshold voltage level 53 at which the normal load can be switched to a light load. The time width 78 is the elapsed time from when the load is switched from the normal load to the light load until the request to switch to the heavy load is generated. The voltage rise amount 88 indicates the battery voltage that has risen during an elapsed time 78 until a request to switch to a heavy load occurs in a state where the load is switched from a normal load to a light load (characteristic curve 72). The amount of voltage rise 89 is determined by the limit battery that can be switched from a normal load to a light load and to a heavier load until a request to switch to a heavy load is generated in a state where the load is switched from a normal load to a light load (characteristic curve 87). The battery voltage increased during the elapsed time 78 is shown. The voltage rise amount 89 is a limit voltage rise amount that can be continuously switched from the normal load to the light load and to the heavier load during the elapsed time 78 until the request to switch to the heavy load occurs.

If a request to switch to a heavy load occurs after a lapse of time 78 from the switching from the normal load to the light load to the request to switch to the heavy load, the limit voltage increase amount at which the load can be switched 8
9 and the actual voltage rise 88. If the actual voltage increase 88 is smaller, the load is determined to be switchable and the load is switched. As described above, when it is not possible to determine whether or not the remaining battery level remains because the battery voltage is rising, the battery voltage rise amount per hour and the battery voltage rise amount at which the load can be switched to the limit When the battery voltage actually increased is small, it is determined that the remaining capacity remains. Thereby, an example of the second problem can be solved.

Next, an example in which the third problem occurs will be described with reference to FIG.

The same components as those shown in FIGS. 3A and 3B or FIGS. 4A and 4B are denoted by the same reference numerals. Here, the case where the remaining capacity of the battery capable of executing the load has the following relationship will be described. The normal load can be executed even when the remaining capacity of the battery is smaller than the light load, and the light load can be executed even when the remaining capacity of the battery is smaller than the heavy load. An example in which, when switching from a heavy load to a normal load, a situation in which the running load is stopped immediately after the switching even though the remaining battery level is sufficient will be described with reference to FIG. I do. As described above, in the limit state (characteristic curve 65) in which the load can be switched from the heavy load to the normal load, the remaining capacity for executing the normal load is left as described above.

When the load is switched from the heavy load to the normal load in the limit state (characteristic curve 65) at which the load can be switched from the heavy load to the normal load, the power supply does not occur because the remaining capacity is sufficient. However, the battery voltage immediately after the switching is the end voltage level 52 of the heavy load. Since the normal load cannot be continued because the voltage is lower than the normal load end voltage level 51, the execution of the normal load is stopped. The same applies to the case of switching from a heavy load to a light load and the case of switching from a normal load to a light load. This is because the battery voltage is rising due to switching the load,
This is because the battery voltage has not risen to the final voltage level of the switched load. In this way, even though the remaining battery level is sufficient immediately after switching the load, the running load may be stopped because the battery voltage has not risen to the cut-off voltage level of the switched load. Yes (third problem).

An example of means for solving the third problem will be described with reference to FIG. The characteristic curve 65 is
The change of the battery voltage in the limit state which can switch from a heavy load to a normal load is shown. The time width 84 corresponds to the cut-off voltage level 51 of the normal load in the limit state (characteristic curve 65) where the load can be switched from the heavy load to the normal load.
The time it takes for the voltage to rise. When switching from a heavy load to a normal load, the time required to increase to the end voltage level 51 of the normal load always depends on the limit state (characteristic curve 65) at which the heavy load can be switched to the normal load. The time required to rise to the cut-off voltage level 51 is 84 or less. This is because the battery voltage level 52 is the end voltage of the heavy load, so that the switching is not performed at a voltage lower than the end voltage level 52 of the heavy load. Further, when the load is switched from the heavy load to the normal load at a voltage between the end voltage level 52 of the heavy load and the end voltage level 51 of the normal load, the limit state where the remaining capacity can be switched from the heavy load to the normal load ( The time required for the battery voltage to rise to the cut-off voltage level 51 of the normal load because of more than the characteristic curve 65) is:
The time is always shorter than the time 84 required to increase to the end voltage level 51 of the normal load in the limit state (characteristic curve 65) where the load can be switched from the heavy load to the normal load. As described above, when the load is switched from the heavy load to the normal load, the load is terminated by the time 84 required to increase to the end voltage level 51 of the normal load in the limit state (characteristic curve 65) at which the heavy load can be switched to the normal load. If the battery life detection based on the voltage is stopped, it is possible to prevent the load being executed from being stopped.

As described above, in the limit state where the load can be switched from the heavy load to the normal load (characteristic curve 65), there is no power interruption during the time 84 required to increase to the cut-off voltage level 51 of the normal load. Recognize.
Since the state of the characteristic curve 65 is a limit state in which the load can be switched from the heavy load to the normal load, the state is not switched from the heavy load to the normal load when the remaining battery level is smaller than the characteristic curve 65. In other words, immediately after switching from the heavy load to the normal load, in the limit state (characteristic curve 65) in which the heavy load can be switched to the normal load, during the time 84 required for the voltage to rise to the end voltage level 51 of the normal load. There is no power interruption. As described above, in the limit state where the heavy load can be switched to the normal load immediately after switching from the heavy load to the normal load (characteristic curve 65), the operation is terminated by the time 84 required for the voltage to rise to the end voltage level 51 of the normal load. By stopping the detection of the battery life based on the voltage, the running load is not stopped immediately after switching to the normal load. The same applies when switching from a heavy load to a light load and from a normal load to a light load. As described above, when the battery voltage has not risen to the cut-off voltage level of the switched load, the detection of the battery life based on the cut-off voltage is stopped immediately after the switching until the battery voltage rises to the cut-off voltage level of the switched load. Thus, the load being executed is not interrupted immediately after switching the load. This allows
An example of the third problem can be solved.

Next, an embodiment for simultaneously achieving the first to third objects (objects) will be described. A battery driving device that can solve these problems includes a load recognition circuit, a battery, a battery voltage detection circuit, an arithmetic circuit, a storage circuit, a timer circuit A, a timer circuit B, and a load switching circuit. Selectively. Then, the timer circuit A periodically generates a battery voltage detection request, and notifies this to the battery voltage detection circuit and the storage circuit. The battery voltage detection circuit notifies a calculation result of the battery voltage detection result. The storage circuit notifies the operation circuit of the end voltage of the load being executed. The arithmetic circuit compares the notified end voltage with the detected battery voltage, and if the detected battery voltage is higher than the end voltage, continues the execution of the load, and if the detected battery voltage is lower than the end voltage, stops the execution of the load. Do it. Such processing is repeated at the cycle of the timer A.

If a load switching request is issued while such processing is being repeated, the load recognizing circuit recognizes the load currently being executed and the requested load, and communicates with the battery voltage detecting circuit. The arithmetic circuit notifies the timer circuit B of the notification. The timer circuit B notifies the execution time of the load currently being executed to the arithmetic circuit. The battery voltage detection circuit detects the battery voltage and notifies the arithmetic circuit. The arithmetic circuit determines whether the notified load can be executed based on the notified battery voltage. If the battery voltage is higher than the voltage at which the load can be executed unconditionally, it is determined whether the battery voltage increases when the load is switched.

If the battery voltage does not rise, the arithmetic circuit notifies this to the storage circuit, the timer circuit B and the load switching circuit. The storage circuit stores the detected battery voltage and the load being executed. The timer circuit B starts a timer for detecting the execution time of the load to be switched. The load switching circuit switches a load. This terminates the load switching process and returns to the periodic battery voltage monitoring process.

When the battery voltage rises, the arithmetic circuit notifies this to the storage circuit. The storage circuit notifies the arithmetic circuit of the time required for the battery voltage to rise to the cut-off voltage of the load to be switched in the battery having only the remaining capacity at which the load can be switched. The arithmetic circuit is
The execution time of the load notified from the timer circuit B is compared with the time required to increase to the cut-off voltage notified from the storage circuit. If the execution time of the load is longer than the time required to increase to the cut-off voltage, Then, the same processing as described above is performed, and the routine returns to the periodic battery voltage monitoring processing. If the execution time of the load is shorter than the time required for the load voltage to rise to the end voltage, a time period to wait after switching the load and returning to the periodic battery voltage monitoring process is calculated. The arithmetic circuit notifies this to the storage circuit, the timer circuit B, and the load switching circuit. The storage circuit stores the detected battery voltage and the load being executed. The timer circuit B starts a timer for detecting the execution time of the load to be switched. The load switching circuit switches a load. The arithmetic circuit waits for the calculated battery voltage to rise to the final voltage. This terminates the load switching process and returns to the regular battery voltage monitoring process.

When the battery voltage is lower than the voltage at which the load can be executed unconditionally, the storage circuit is notified to detect the remaining battery level. The storage circuit notifies the arithmetic circuit of the load being executed before the currently executed load and the battery voltage before switching the load. In addition, in the combination of loads to be notified, a time required from the time when the load is switched to the time when it becomes possible to determine whether the next load can be switched is notified. The notification time is a time required for the battery having only the remaining remaining capacity at which the load can be switched to reach a voltage at which it can be determined whether the next load can be switched. The arithmetic circuit compares the execution time of the load notified from the timer circuit B with the time notified from the storage circuit. If the time notified from the timer circuit B is longer, whether the combination may cause a power failure due to the combination of loads, or the combination that may not switch the load even though the capacity is sufficient. Judge. In the case of a combination in which the load may not be switched while the capacity remains, the load switching is stopped. In the case of a combination that may cause a power failure, the detected battery voltage is compared with a limit voltage at which the power failure does not occur when the load is switched from a state in which the load is continuously executed. If the detected battery voltage is lower, the switching of the load is stopped. If the detected battery voltage is higher, it is determined that the load can be executed, and the same processing as described above is performed, and the process returns to the periodic battery voltage monitoring processing.

If the time notified from the timer circuit B is shorter, this is notified to the storage circuit. The memory circuit is
A change in the battery voltage when the load is switched by a battery having only the remaining capacity at which the load can be switched is notified to the arithmetic circuit as a function using time as a variable.
The arithmetic circuit substitutes the execution time of the load into the notified function, and calculates the fluctuation amount of the battery voltage at which the load can be switched during the execution time. Further, the calculation is performed based on the detected battery voltage and the battery voltage before switching the load notified from the storage circuit, which is the actual amount of change in the battery voltage due to the switching of the load. Further, the change amount of the battery voltage at the limit at which the load can be switched is compared with the change amount of the actual battery voltage. If the actual change amount of the battery voltage is larger, the switching of the load is stopped. If the actual amount of change in the battery voltage is smaller, it is determined that there is enough remaining capacity to switch the load, the same processing as described above is performed, and the process returns to the periodic battery voltage monitoring processing. From the above,
The first to third objects can be simultaneously realized.

Hereinafter, a specific example of a battery driving device for switching a load will be described as an embodiment of the present invention with reference to FIGS. In the embodiment described below, a case in which a light load, a normal load, and a heavy load are switched will be described as an example. A description will be given of a case where the load relationship is the same as described above and has the following relationship. The normal load can be executed even when the remaining capacity of the battery is smaller than the light load, and the light load can be executed even when the remaining capacity of the battery is smaller than the heavy load. Also, to make the explanation easy to understand, FIG.
(A), (b) or reference numerals indicating specific battery voltage, time, and battery state shown in FIG. 5 are added to the description.

FIG. 1 is a functional block diagram showing one embodiment of a battery driving device for executing the battery life detecting method according to the present invention. FIG. 2 is a flowchart showing a specific example of the operation of the battery driving device shown in FIG. In FIG.
100 is a load switching request signal, 101 is a battery voltage detection circuit, 102 is a timer circuit A, 103 is a load switching circuit, 104 is a light load circuit (function), 105 is a normal load circuit (function), and 106 is a heavy load circuit ( Function), 10
7 is a battery, 108 is a load recognition circuit, 109 is an arithmetic circuit,
110 is a timer circuit B, 111 is a storage circuit, and 112 is a battery voltage detection request signal. Some of these measures are:
It is a functional means constituted by a CPU and a program.

In the embodiment described below, two processes shown in FIG. 2 are performed. In FIG. 2, a process 90 is a process for periodically monitoring the battery voltage, and a process 91 is a process for detecting the remaining capacity of the battery when a load switching request occurs.

The process 90 for periodically monitoring the battery voltage will be described. The timer circuit A 102 periodically generates a battery voltage detection request signal 112 to notify the battery voltage detection circuit 101 and the storage circuit 111. Battery voltage detection circuit 101
Detects the battery voltage in the cycle of the battery voltage detection request signal 112 and notifies the arithmetic circuit 109 of the detected battery voltage. This allows the battery voltage to be monitored periodically (step 12).
8). The storage circuit 111 notifies the arithmetic circuit 109 of the final voltage level 50 (shown in FIG. 5) when the light load 104 is continuously executed. The arithmetic circuit 109 compares the detected battery voltage with the cut-off voltage level 50 of the light load 104 (step 129). If the detected battery voltage is higher, the execution of the light load 104 is continued, and the detected battery voltage is continued. If the voltage is lower, the execution of the light load 104 is stopped (step 133). Load 10 with light detected battery voltage
If the end voltage level is higher than the end voltage level 50 of Step 4, the timer circuit A102 generates a battery voltage detection request signal 112 after a predetermined time (Step 132). As a result, the above processing is repeated, and when the remaining battery capacity decreases and the battery voltage becomes lower than the end voltage level 50 of the light load 104, the execution of the light load 104 is stopped (step 133). With such processing, when the light load 104 is continuously executed, the capacity of the battery can be used up. Step 1
At 29, the voltage to be compared in the normal load 105 is changed to the final voltage level 51 (shown in FIG. 5) of the normal load 105,
For the heavy load 106, the remaining voltage of the battery can be used up by changing the voltage to be compared to the final voltage level 52 of the heavy load 106 (shown in FIG. 5).

Here, the comparison result 130 in the step 129 indicates that the battery voltage V detected at the light load 104 is equal to or higher than the cut-off voltage level 50, and the battery voltage V detected at the normal load 105 is equal to or higher than the cut-off voltage level 51. , When the battery voltage V detected at the heavy load 106 ≧ the end voltage level 52. In addition, the comparison result 131
When the battery voltage V detected at the light load 104 <the cut-off voltage level 50, the battery voltage V detected at the normal load 105 <the cut-off voltage level 51, and the battery voltage V detected at the heavy load 106 <the cut-off voltage It is at the voltage level 52.

Next, a process 91 for detecting the remaining capacity of the battery when a load switching request has occurred will be described.

When the load switching request 100 is generated (step 134), the load currently being executed and the load requested to be switched are recognized (step 135). And
The load execution time T is detected (timer B is read), and it is determined whether the load can be switched by comparing the battery voltage V with the end voltage level (step 137).
Here, the comparison result 138 indicates that when the detected battery voltage V ≧ the threshold voltage level 57 in the switching of the light load 104 → the normal load 105 and the switching of the light load 104 → the heavy load 106, the normal load 105 → the light load In the switching of 104, the detected battery voltage V ≧ the threshold voltage level 5
3, when the detected battery voltage V ≧ the threshold voltage level 57 in the switching of the normal load 105 → heavy load 106, and in the switching of the heavy load 106 → light load 104, the heavy load 106 → the normal load 105 It is time for switching. The comparison result 139 indicates that when the detected battery voltage V <threshold voltage level 57 in the switching of the light load 104 → heavy load 106, the normal load 105 → the light load 10
In the switching of No. 4, the detected battery voltage V <the threshold voltage level 53, and in the switching of the normal load 105 → heavy load 106, the detected battery voltage V <the threshold voltage level 57.

In the case of the comparison result 139, the load executed before the currently executed load is recognized (step 1).
40), it is determined whether or not the time until the battery voltage recovers has elapsed based on the load execution time T (step 141). In this judgment processing 141, judgment result 1
Reference numeral 42 denotes a load execution time T> time width 82 when switching from (normal load 105) → light load 104 → heavy load 106, and load execution when switching from (heavy load 106) → light load 104 → heavy load 106. When time T> time width 83, (light load 104) → normal load 105
→ When switching to light load 106, (heavy load 10
6) When the load is switched to the normal load 105 → the light load 104, the load execution time T> the time width 84, and when the light load 104 is switched to the (light load 104) → the normal load 105 → the heavy load 106, the load execution time T> the time width 85. , When the battery voltage V <the threshold voltage level 58, (the heavy load 10
6) When switching from the normal load 105 to the heavy load 106, the load execution time T> the time width 84. When the determination result 142 is obtained, the load switching is stopped (step 143).

The judgment result 144 is (normal load 105) →
When the load is switched from the light load 104 to the heavy load 106, when the load execution time T ≦ the time width 82, (the heavy load 10
6) When the load is switched from the light load 104 to the heavy load 106, the load execution time T ≦ the time width 83, and when the (heavy load 106) → the normal load 105 → the light load 104 is switched, the load execution time T ≦ the time width 84. , When (light load 104) → normal load 105 → heavy load 106 is switched, when load execution time T ≦ time width 85,
(Heavy load 106) → normal load 105 → heavy load 106
At the time of load execution time T ≦ time width 84. Also, the judgment result 159 is (Light load 10
4) When switching from the normal load 105 to the heavy load 106, when the load execution time T> the time width 85, the battery voltage V
.Gtoreq.threshold voltage level 58.

When the judgment result 144 is obtained, the absolute value | △ V (T) | of the limit of the battery voltage change at which the load can be executed is calculated (step 145). Next, the battery voltage change amount ΔV (ΔV = Vold
-V) (step 146). Then, it is determined whether this load can be executed by comparing | ΔV (T) | with ΔV (step 147). The determination result 148 is as follows: when switching from (normal load 105) → light load 104 → heavy load 106, the absolute value of battery voltage change amount | △ V (T) | (battery voltage change amount of characteristic curve 87)>
When the battery voltage change amount △ V, (light load 104) → normal load 105 → heavy load 106 is switched, the absolute value of the battery voltage change amount | （V (T) | (the battery voltage change amount of the characteristic curve 74) When the battery voltage change amount △ V, and the determination result 148 is obtained, the switching of the load is stopped (step 149).

The judgment result 150 is (normal load 105) →
When the absolute value of the battery voltage change amount when switching from the light load 104 to the heavy load 106 | △ V (T) | (battery voltage change amount of the characteristic curve 87) ≦ battery voltage change amount △ V, (heavy load 106 ) → light load 104 → heavy load 106, (light load 104) → normal load 105 → light load 104, (heavy load 104) →
When switching from the normal load 105 to the light load 104,
(Light load 104) → normal load 105 → heavy load 106
When switching to the absolute value | △ V
(T) | (battery voltage change amount of characteristic curve 74) ≦ battery voltage change amount △ V, (heavy load 106) → normal load 10
This is when switching from 5 to heavy load 106 is performed.

Comparison result 138 and judgment results 159 and 15
When 0 is obtained, in step 151, when returning to the processing 90, the battery voltage is recovering, so that the battery life is not determined by the periodic battery voltage detection, so that the waiting after the load switching is performed. Is determined whether it is necessary. The determination result 152 indicates that when the load is switched from the light load 104 to the normal load 105, the light load 104 is changed to the heavy load 1
06, normal load 105 → heavy load 10
6 and the determination result 154 indicates that when the load is switched from the normal load 105 to the light load 104, when the load is switched from the heavy load 106 to the light load 104, the heavy load 1
06 → normal load 105 is switched.

When the determination result 152 is obtained, the wait time Twwait = 0 is set (step 15).
3). When the determination result 154 is obtained, the waiting time Twwait after the load is switched is calculated. When switching from the normal load 105 to the light load 104, the waiting time Twwait = time width 82-load execution time T, and when switching from the heavy load 106 to the light load 104, the waiting time Twit = time width 83-load execution time T, heavy load. When switching from 106 to the normal load 105, an operation of waiting time Twwait = time width 84-load execution time T is performed (step 155).

Then, the battery voltage Vold (Vold =
V) and the load being executed are stored (step 156),
The timer B is started and the load is switched (step 157), and the waiting time T until the battery voltage recovers is T
After waiting for wait, the process returns to the battery voltage monitoring process 90 (step 158).

In such a battery life detecting process, a case where a request to execute the heavy load 106 is generated by the load switching request 100 while the light load 104 is being executed will be described. When the load switching request 100 occurs, the load recognition circuit 108 issues a battery voltage detection request to the battery voltage detection circuit 101. At the same time, the arithmetic circuit 109 is notified of the currently executed light load 104 and the heavy load 106 that has been requested to be switched, and is made to recognize it. Battery voltage detection circuit 1
01 notifies the arithmetic circuit 109 of the battery voltage detection result. The arithmetic circuit 109 notifies the timer circuit B110. The timer circuit B110 notifies the execution time T of the light load 104 to the arithmetic circuit 109.

The arithmetic circuit 109 compares the battery voltage detection result with the threshold voltage level 57 (shown in FIG. 5) at which the light load 104 can be switched to the heavy load 106. If the battery voltage is higher than the threshold voltage 57 at which the load can be switched from the light load 104 to the heavy load 106, the arithmetic circuit 109 determines that the battery has sufficient capacity. The load circuit to be switched is a light load 104.
Since the load 106 is a heavy load, when the process moves to the process 90 for periodically monitoring the battery voltage, the voltage for determining whether the load can be executed is changed from the cutoff voltage level 50 at the light load to the heavy voltage. End voltage level 5 at load
Change to 2. In this case, the voltage for determining whether the load can be executed becomes low. In this state, the battery voltage does not become lower than the end voltage level 52 of the heavy load while the battery voltage is fluctuating due to the switching of the load. Judge that you can go back. Arithmetic circuit 1
09 is a load switching circuit 103 and a timer circuit B110.
Is notified to the storage circuit 111. The storage circuit 111 stores the battery voltage detection result and the light load 104 being executed.

The timer circuit B110 starts a timer to measure the execution time of the heavy load 106 to be switched. This is to predict the remaining battery level when the battery voltage is lower than the voltage at which the load can be executed unconditionally when the next load switching request occurs. The load switching circuit 103 switches to the heavy load 106 and immediately returns to the process 90 for periodically monitoring the battery voltage.

Next, the load 106 whose battery voltage detection result is heavy
The case where the load is lower than the threshold voltage 57 that can be switched to the light load 104 and the normal load 105 is executed before the light load 104 is executed will be described.

The arithmetic circuit 109 notifies the storage circuit 111 of the switching of the load circuit. The storage circuit 111 stores the normal load 10 executed before executing the light load 104.
5 is notified to the arithmetic circuit 109. This is because, as described in the case where the battery voltage detection result is higher than the threshold voltage 57 capable of switching from a heavy load to a light load, the load executed before executing the light load 104 is stored. It is stored in the circuit 111. The arithmetic circuit 109 is
When switching from the normal load 105 to the light load 104,
The time 82 until the battery voltage stabilizes (shown in FIG. 5) and the execution time T of the light load 104 are compared. Light load 104
Is longer than the time 82 required for the battery voltage to stabilize when the load is switched from the normal load 105 to the light load 104, the combination of loads may cause a power failure, It is determined whether or not there is a risk that the load will not be switched even though the load remains.
If there is a risk that the load will not be switched even though the capacity remains due to switching from a normal load to a light load, check whether the battery voltage is rising just after switching the load. Thus, the remaining battery level can be determined. In this case, since the execution time T of the light load is longer than the time 82 until the battery voltage is stabilized when switching from the normal load 105 to the light load 104, it is determined that the battery voltage is stable and that the battery voltage is dropping. I do. When switching from the light load 104 to the heavy load 106 in this state,
Since the power is cut off, it is determined that there is no remaining capacity in the battery, and the switching of the load is stopped. If the execution time T of the light load 104 is shorter than the time 82 until the battery voltage stabilizes when switching from the normal load 105 to the light load 104, the arithmetic circuit 109 notifies the storage circuit 111 of this. The storage circuit 111 stores the voltage of the normal load 105 before executing the light load 104 and the light load 1 from the normal load 105.
04, an approximation function using time as a variable in the limit battery voltage fluctuation that can be switched to the heavier load 106
V (T) is notified to the arithmetic circuit 109. Light load 104
The battery voltage of the normal load 105 before executing
The battery voltage detection result indicates that the load 104 is light to the heavy load 1
Threshold voltage level 57 switchable to 06
It is stored in the storage circuit 111 as described in the higher case.

The approximation function △ V (T) of the limit of the battery voltage fluctuation which can be switched from the normal load 105 to the light load 104 and the heavier load 106 is the normal load 10.
It is stored in the storage circuit 111 as a function for calculating the limit battery voltage variation that can be switched from 5 to the light load 104. The arithmetic circuit 109 includes a timer B110
The execution time T of the light load 104 read from the memory and the normal load 105 read from the storage circuit 111 to the light load 10
4. Approximate function △ V (T) of the limit battery voltage fluctuation that can be switched to the heavier load 106 (normal load 105
The approximate function △ V (T) when switching from the normal load to the light load 104 and from the normal load to the light load and the heavier load 106 is as follows: Based on the switched state (characteristic curve 87), the absolute value of the limit battery voltage change amount at which the normal load 105 can be switched to the light load 104 and the heavy load 106 is calculated. Also, the battery voltage detected by the battery voltage detection circuit 101 and the battery voltage of the normal load 105 read from the storage circuit 111 indicate the absolute value of the change amount of the battery voltage actually changed when switching from the normal load 105 to the light load 104. Is calculated by In addition, the absolute value of the limit battery voltage change amount that can be switched from the normal load 105 to the light load 104 and the heavier load 106 and the battery voltage change amount actually changed when the normal load 105 is switched to the light load 104 are calculated. The absolute values are compared, and when the absolute value of the actually changed battery voltage change amount is larger, it is determined that the battery does not have sufficient remaining capacity, and the switching of the load is stopped. If the absolute value of the actually changed battery voltage change amount is smaller, it is determined that the battery has sufficient remaining capacity. In addition, the load 1 to be switched is light.
From 04, it is determined that the load can be immediately returned to the process 90 for periodically monitoring the battery voltage because the load is a heavy load 106 and the final voltage is low. The arithmetic circuit 109 converts this into a load switching circuit 103, a timer circuit B110, and a storage circuit 111.
Notify. The storage circuit 111 stores the battery voltage detection result and the light load 104 being executed.

The timer circuit B 110 starts a timer to measure the execution time of the heavy load 106 to be switched. The load switching circuit 103 includes a heavy load 106
Process 9 for switching to and immediately monitoring the battery voltage immediately
Return to 0. The processing for switching from the light load 104 to the heavy load 106 has been described above, but the same processing is executed in accordance with the flowchart shown in FIG. 2 when switching to another load.

In the above-described embodiment, the case where three types of load circuits having different remaining battery capacities required for execution are switched is described. However, the present invention is not limited to this, and the present invention is not limited to this. Even if the remaining capacity is different or the number of loads is different, the present invention can be widely applied to any device that needs to be driven by a battery and switch the load.

[0067]

As described above, according to the present invention, in order to detect the battery life based on the load execution time and the battery voltage fluctuated during the load execution, the power interruption and the capacity by the continuous load switching are sufficient. The load switching can be prevented from being stopped in the state where the load remains, and after the load is switched, the load can be executed immediately after the load is switched by waiting until the battery voltage rises to the cutoff voltage of the switched load. Since the suspension can be prevented, the cut-off voltage can be changed by the load, and a battery driving device that can use up the capacity of the battery can be realized.

[Brief description of the drawings]

FIG. 1 is a functional block diagram showing an embodiment of a battery driving device that executes a battery life detecting method according to the present invention.

FIG. 2 is a flowchart showing a specific example of a battery life detecting method according to the present invention.

FIG. 3 is a timing chart showing a specific example of a discharge characteristic of a battery.

FIG. 4 is a timing chart showing a specific example of a change in battery voltage when a load is switched.

FIG. 5 is a timing chart showing a specific example of a change in battery voltage when a load is switched based on an end voltage or a threshold voltage.

[Explanation of symbols]

100: load switching request signal, 101: battery voltage detection circuit, 102: timer circuit A, 103: load switching circuit, 104: light load circuit, 105: normal load circuit
106: heavy load circuit, 107: battery, 108: load recognition circuit, 109: arithmetic circuit, 110: timer circuit B,
111: storage circuit, 112: battery voltage detection request signal.

 ──────────────────────────────────────────────────続 き Continued on the front page (72) Inventor Yasuo Sakai 292 Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa Prefecture Inside the Multimedia Systems Development Division of Hitachi, Ltd. (72) Inventor Tetsuya Suzuki Yoshida-cho, Totsuka-ku, Yokohama-shi, Kanagawa 292 Inside Hitachi Image Information System Co., Ltd.

Claims (6)

[Claims] 1. A battery driving apparatus comprising: a battery; a battery voltage detecting means; a plurality of loads; a means for switching between the plurality of loads; and a means for recognizing the load to be switched. In the battery life detection method for determining whether or not operation is possible at each load, a means for detecting a temporal variation of the battery voltage when the load is switched is provided, and based on the battery voltage variation, the operation at each load is determined. A battery life detection method characterized by making a judgment. 2. The battery according to claim 1, wherein a final voltage level of the battery specified for each load is stored, and the final voltage level is compared with the battery voltage to determine whether each load is operable or not. A battery life detecting method, wherein the cut-off voltage level is changed. 3. The battery life detecting process according to claim 1, wherein a change period of the battery voltage caused by switching the load is determined, and the battery life detecting process is stopped during the change period for the battery voltage to rise to the cut-off voltage level. Battery life detection method. 4. A battery driving apparatus comprising: a battery; a battery voltage detecting means; a plurality of loads; a means for switching between the plurality of loads; and a means for recognizing the load to be switched. In the battery life detection method for determining whether operation is possible at each load, the end voltage level of the battery specified for each load is stored, and the end voltage level is compared with the battery voltage to determine whether operation is possible at each load. And changing the end voltage level by each load. 5. The battery life detecting process according to claim 4, wherein a change period of the battery voltage caused by switching the load is determined, and the battery life detecting process is stopped during the change period for the battery voltage to rise to the cut-off voltage level. Battery life detection method. 6. A means for switching a plurality of loads requiring different amounts of power, a means for recognizing a load currently being executed and a load requested to be switched, a means for detecting a battery voltage, and a switchable to each load. A storage means and an operation means for storing the amount of fluctuation of the battery voltage in advance are provided, and the load executed before the load currently being executed, and the load The battery voltage at the time of switching to the currently executing load, the battery voltage at the time of the load switching request, and the amount of fluctuation of the battery voltage per unit time from the elapsed time of the currently executing load are calculated, and the calculated battery voltage is calculated. By comparing the amount of change with the value stored in the storage means in advance and determining whether switching to the load requested to be switched is possible, the cutoff voltage is changed for each load. Battery life detection method characterized by so can use up capacity that is stored in the battery Te.