JPH05103429A - Power supply control system - Google Patents

Abstract

PURPOSE:To make it possible to use various kinds of batteries by conducting low battery detection or full-charging detection which is different from type to type of various kinds of batteries having different characteristics. CONSTITUTION:Using a low battery detection level and a full-charging detection level which are different between a nickel-cadmium (Ni-Cd) battery and a nickel- hydrogen (Ni-MH) battery, the capacity-declined state and the full-charged state of a battery 111 is detected. In this case, which detection level is used for detecting is decided by the type of a battery to be used as the battery 11 for driving a power supply, the nickel-cadmium (Ni-Cd) battery or the nickel- hydrogen (Ni-MH) battery. By this method, a power supply controller 12 can conduct a low-battery detection or a full-charging detection which is different from type to type of the batteries and thereby various kinds of batteries can be used in one and the same portable computer.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a power supply control system for a small electronic device, and more particularly to a power supply control system for a battery-operable portable computer.

[0002]

2. Description of the Related Art In recent years, various laptop type portable computers which are easy to carry and can be operated by a battery have been developed. This type of portable computer is usually provided with a low battery detection mechanism for detecting that the remaining capacity of the battery has dropped below a certain value.

This low battery detection mechanism is used for instructing an operator to stop using the battery by driving the battery, and detects the low battery state by utilizing the discharge characteristic of the battery used.

Nickel-cadmium (Ni-Cd) batteries are mainly used as batteries for portable computers. Therefore, the nickel cadmium (Ni
-Cd) The low battery detection mechanism of a portable computer using a battery is based on its nickel cadmium (Ni-
Cd) It was configured to detect a low battery condition at a detection level adapted to the discharge characteristics of the battery.

Recently, nickel cadmium (Ni-C
d) Nickel-hydrogen (Ni-MH) batteries are being used instead of batteries. This nickel-hydrogen (Ni-MH) battery has an advantage that it has a large capacity per unit volume and can be driven for a long time.

The low battery detection mechanism of a portable computer using a nickel metal hydride (Ni-MH) battery is
Unlike portable computers that use nickel-cadmium (Ni-Cd) batteries, nickel-hydrogen (Ni-Cd)
MH) is configured to detect a low battery condition at a detection level adapted to the discharge characteristics of the battery.

As described above, since the conventional low battery detection is always performed for one type of battery, the battery to be used is defined for each model of portable computer.
It was not possible to use other types of batteries. If another type of battery is used, the low battery state of the battery cannot be accurately detected.

Further, the portable computer is provided with not only a low battery detection mechanism but also a battery full charge detection mechanism. This full charge detection mechanism,
This is for controlling the charging of the battery using the AC commercial power supply, and automatically stops the charging of the battery when the battery is in the fully charged state.

With respect to this full charge detection mechanism as well, a portable computer using a nickel-cadmium (Ni-Cd) battery and a portable computer using a nickel-hydrogen (Ni-MH) battery have different detection levels. Detection control is being performed. Therefore,
If a battery of a type other than the predefined battery is used, the battery charge control may not be performed normally, and in some cases, overcharge may cause battery damage. As described above, conventionally, a battery to be used is specified for each model of a portable computer, and there is a drawback that a different type of battery other than that cannot be used.

[0010]

Conventionally, there is a drawback in that a battery to be used is specified for each model of a portable computer, and batteries of different types other than that cannot be used.

The present invention has been made in view of the above point, and enables different low battery detection or full charge detection to be performed for each of a plurality of types of batteries having different characteristics, and uses a plurality of types of batteries. It is an object of the present invention to provide a power supply control method capable of performing the above.

[0012]

A power supply control system according to the present invention comprises a judgment means for judging the kind of the battery mounted as a driving power supply in the apparatus among a plurality of kinds of batteries having different discharge characteristics. Low battery detection means for detecting a low capacity state of the battery using a plurality of low battery detection levels respectively adapted to the discharge characteristics of the plurality of types of batteries, and the plurality of low batteries according to the determination result by the determination means. A low battery detecting operation adapted to the discharge characteristic of the battery mounted as the driving power source, and a means for instructing the low battery detecting means which one of the detection levels is used to execute the detecting operation. It is characterized by performing.

In this power supply control system, low battery detection means for detecting a low battery state using a plurality of low battery detection levels is provided, and which detection level is used to execute the detection operation. , Is determined according to the type of battery mounted as a driving power source.
Therefore, different low battery detection can be performed for each of a plurality of types of batteries having different characteristics, and a plurality of types of batteries can be used.

[0014]

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

FIG. 1 shows a system configuration for realizing a power supply control system according to an embodiment of the present invention. This system is applied to a laptop type portable computer, and as shown in the figure, a battery pack 11, a power controller 12, a DC-DC.
Converter 13, AC adapter 14, switch circuit 1
5, a battery voltage detection circuit 16, a battery current detection circuit 17, an AC power supply voltage detection circuit 18, and backflow prevention diodes 19 and 20.

The battery pack 11 is detachably provided in the main body of the portable computer, in which a rechargeable battery 111 such as a nickel-cadmium (Ni-Cd) battery or a nickel-hydrogen (Ni-MH) battery is enclosed. There is. Further, the battery pack 11 is provided with a thermistor 112 and a battery identification terminal 113.

The thermistor 112 is provided in the vicinity of the battery 111 and is used to detect the temperature of the battery 111. That is, since the resistance value of the thermistor 112 changes depending on the ambient temperature, the temperature of the battery 111 is detected by the voltage value divided by the thermistor 112 and the resistor R.

The battery identification terminal 113 is used for the battery pack 1
For identifying the type of battery 111 in
For example, when the battery 111 is a nickel-hydrogen (Ni-MH) battery, the short state is set, and when the battery 111 is a nickel-cadmium (Ni-Cd) battery, the open state is set. The open / short setting of the battery identification terminal 113 is performed when the battery pack 11 is manufactured.

The DC-DC converter 13 sets the DC voltage from the battery 111 of the battery pack 11 or the DC voltage from the AC adapter 14 connected to the AC power source to a desired power source voltage value (+ 5V, + 12V, -9V). It converts and supplies it to each component of the portable computer as a power source. A backflow prevention diode 19 is connected between the DC-DC converter 13 and the AC adapter 14 to prevent backflow of current from the battery 111 to the AC adapter 14 even when an AC power source is not used. In addition, the batteries 111 and D of the battery pack 11
The backflow prevention diode 20 is also connected to the C-DC converter 13, so that the current from the AC adapter 14 to the battery 111 can be prevented even when the battery pack 11 is not attached or when the voltage of the battery 111 drops. Backflow is prevented.

The switch circuit 15 is a switch for controlling the supply of the charging current to the battery 111, and has an FET for connecting or disconnecting the charging current path between the AC adapter 14 and the battery 111. Switch circuit 15
Is set to the ON state when the battery 111 is in the chargeable state, and the charging current is supplied from the AC adapter 14 to the battery 111. Further, when the battery 111 is in the fully charged state, the switch circuit 15 is set to the off state, and the charging current from the AC adapter 14 to the battery 111 is shut off.

The battery voltage detection circuit 16 includes a battery 11
The voltage of 1 is detected. The battery current detection circuit 17 is
The charge current and the discharge current of the battery 111 are detected. The AC power supply voltage detection circuit 18 detects the voltage output from the AC adapter 14.

The power supply controller 12 is for controlling the power supply to the portable computer, including the on / off control of the system power supply of the portable computer, the control of the charging current to the battery 111, and the battery 1.
11, a process of detecting a fully charged state or a low battery state, a process of determining the type of the battery 111, and the like are executed. The power controller 12 includes a CPU 121, a RAM 122, and an R connected to each other via an internal bus, as shown in the figure.
It is composed of an OM 123, an analog input port 124, and a digital input / output port 125.

The CPU 121 executes a program in the ROM 12 to control the power supply controller 12 as a whole. R
The OM 123 stores programs necessary for the above-described various power supply control processes performed by the power supply controller 12. The RAM 123 is used as a work area for data processing performed by the CPU 121.

The first port A of the analog input port 124
1, the detection output from the battery voltage detection circuit 16 is supplied. Further, the second port A2 of the analog input port 124 has a detection output from the battery current detection circuit 17, the third port A3 has a temperature detection output from the thermistor 112, and the fourth port A4 has an AC power supply voltage detection. The detection output from the circuit 18 is supplied. The values of these detection outputs are A / D converted and then read by the CPU 121.

The identification output from the battery identification terminal 113 is input to the first port D1 of the digital input / output port 125, and the switch signal for the switch circuit 15 is output from the second port D2. Next, referring to the flowchart of FIG. 2, the CPU 121 of the power supply controller 12
The power supply control operation executed by will be described.

First, the CPU 12 of the power supply controller 12
1 executes a process for determining the type of the battery 111 of the battery pack 11 mounted on the portable computer main body (step S11), and the battery 111 is a nickel hydrogen (Ni-MH) battery or a nickel cadmium ( It is determined whether the battery is a Ni-Cd battery (step S
12).

The battery 111 is nickel hydrogen (Ni-MH).
In the case of a battery, the CPU 121 uses the nickel hydrogen (Ni
-MH) Battery control processing (steps S13 to S16)
To execute.

That is, the CPU 121 first determines whether or not the battery 111, which is a nickel hydrogen (Ni-MH) battery, can be charged (step S13). If the battery can be charged, the switch circuit 15 is set to the ON state and the battery 11
Charged to 1 and nickel hydrogen (Ni-MH)
A full charge detection process for the battery is executed (step S1).
4). In this case, whether or not the battery 111 can be charged is determined depending on whether or not the nickel-hydrogen (Ni-MH) battery is in a fully charged state. Charging is done. And
When the battery 111 is fully charged, the switch circuit 15 is turned off to stop the charging of the battery 111.

The full charge detection process is performed by nickel hydrogen (Ni-
MH) The presence or absence of the fully charged state is detected at a detection level suitable for the charging characteristics of the battery. Details of this full charge detection processing will be described later with reference to FIG. 11.

Next, the CPU 121 judges whether or not the system is driven by only the battery 111 (step S15), and when the system is driven only by the battery 111 without using the AC power source. In step S16, a low battery detection process for a nickel hydrogen (Ni-MH) battery is executed.

Here, the CPU 121 determines whether or not the system is driven only by the battery 111.
It is determined by reading the voltage value input from the port A4 of 24. That is, AC to the AC adapter 14
When the commercial power supply is connected, the detection output of the AC power supply voltage detection circuit 18 exceeds a certain value, and when the AC commercial power supply is not connected, the AC power supply voltage detection circuit 18
The detection output of becomes zero. Therefore, the CPU 121 causes the battery 11 to operate when the voltage value input from the port A4 becomes zero.
Only 1 determines that the system is driven.

The low-battery detection process for a nickel-hydrogen (Ni-MH) battery detects the presence or absence of the low-battery state by using a detection level suitable for the discharge characteristics of the nickel-hydrogen (Ni-MH) battery. .. Details of this low battery detection processing will be described later with reference to FIG.

After that, the CPU 121 controls the switch circuit 1
5, the charge control of the battery 111, the discharge control of the battery 111, and the like are executed. In this discharge control, for example,
When the battery 111 is in a low battery state, the operator is notified by a buzzer sounding or LED lighting, and the supply amount of power supply current to each component of the portable computer is adjusted in order to reduce the consumption amount of the battery 111. Such processing is performed.

On the other hand, when it is determined in step S12 that the battery 111 is a nickel-cadmium (Ni-Cd) battery, the CPU 121 causes the nickel-cadmium (Ni-Cd) battery.
-Cd) Battery control processing (steps S17 to S20)
To execute.

That is, the CPU 121 first determines whether or not the battery 111 made of a nickel-cadmium (Ni-Cd) battery can be charged (step S17). If the battery can be charged, the switch circuit 15 is set to the ON state to charge the battery 111, and the full charge detection process for the nickel-cadmium (Ni-Cd) battery is executed (step S18). In this case, whether or not the battery 111 can be charged is determined by whether or not the nickel-cadmium (Ni-Cd) battery is in a fully charged state. If the battery is not in a fully charged state, the battery 111 is charged while performing the fully charged detection process. Charging is done. When the battery 111 is fully charged, the switch circuit 15 is turned off to stop the charging of the battery 111.

The full charge detection process is to detect the presence or absence of the full charge state at a detection level suitable for the charging characteristics of the nickel-cadmium (Ni-Cd) battery. Details of this full charge detection processing will be described later with reference to FIG. 11.

Next, the CPU 121 judges whether or not the system is driven by only the battery 111 (step S19), and when the system is driven only by the battery 111 without using the AC power source. In step S20, a low battery detection process for a nickel-cadmium (Ni-Cd) battery is performed.

Here, the CPU 121 determines whether or not the system is driven only by the battery 111.
It is determined by reading the voltage value input from the port A4 of 24. That is, AC to the AC adapter 14
When the commercial power supply is connected, the detection output of the AC power supply voltage detection circuit 18 exceeds a certain value, and when the AC commercial power supply is not connected, the AC power supply voltage detection circuit 18
The detection output of becomes zero. Therefore, the CPU 121 causes the battery 11 to operate when the voltage value input from the port A4 becomes zero.
It is determined that the system is driven by only 1.

The low-battery detection process for nickel-cadmium (Ni-Cd) batteries is based on nickel-cadmium (Ni-Cd).
-Cd) The presence or absence of the low battery state is detected by using a detection level suitable for the discharge characteristics of the battery. Details of this low battery detection processing will be described later with reference to FIG.

After that, the CPU 121 controls the switch circuit 1
5, the charge control of the battery 111, the discharge control of the battery 111, and the like are executed. In this discharge control, for example,
When the battery 111 is in a low battery state, a buzzer sounds, an LED is lit to notify the operator, or a process of adjusting the supply amount of the power supply current to each component in order to reduce the consumption amount of the battery 111, etc. Is done.

As described above, depending on whether the battery 111 used is a nickel hydrogen (Ni-MH) battery or a nickel cadmium (Ni-Cd) battery, the full charge detection process and the low battery detection process for the battery 111 are performed. Each is different, but otherwise the same.

Next, referring to the flowchart of FIG.
An example of the battery determination process performed in step S11 of FIG. 2 will be described. This discrimination processing utilizes the battery identification terminal 113 provided in the battery pack 11.

First, the CPU 12 of the power supply controller 12
1 is a battery pack 1 in the body of the portable computer
It is determined whether or not No. 1 is attached (step S2
1). This is determined, for example, by whether or not the detection output from the battery voltage detection circuit 16 input to the port A1 of the analog input port 124 is zero. Also, the temperature detection output from the thermistor 112 can be used.

When the battery pack 11 is mounted, the CPU 121 reads the status of the port D1 of the digital input / output port 125 in order to determine the type of the battery 111 in the battery pack 11 (step S22). ). In this case, if the battery 111 is a nickel-hydrogen (Ni-MH) battery, the status of the port D1 is "L" because the battery identification terminal 113 is in a short state.
Level, and the battery 111 becomes nickel cadmium (Ni
-Cd) If it is a battery, the status of the port D1 is "H" level because the battery identification terminal 113 is in the open state.

Therefore, the CPU 121 determines that the port D1
When the status of is at "L" level, it is determined that the battery 111 is a nickel metal hydride (Ni-MH) battery (step S
23) When the status of the port D1 is "H" level, it is determined that the battery 111 is a nickel-cadmium (Ni-Cd) battery (step S24). in this way,
The type of the battery 111 can be easily determined by using the battery identification terminal 113.

To determine the type of the battery 111, the charge characteristic and the discharge characteristic of the battery 111 are checked by using the battery voltage detection circuit 16, the battery current detection circuit 17, and the thermistor 112, and the characteristic of the battery 111 is checked. However, nickel hydride (Ni-MH) batteries and nickel cadmium (Ni
-Cd) It can also be done by checking which characteristic of the battery matches.

Before explaining the battery discrimination processing using the charge characteristic and the discharge characteristic of the battery 111, first, a nickel hydrogen (Ni-MH) battery and a nickel cadmium (Ni-C) battery are used.
d) The charge characteristics and discharge characteristics of each battery will be described.

FIG. 4 shows the change characteristics of the voltage (V) of the battery 111 with respect to the charging time (t) at the time of charging in a nickel hydrogen (Ni-MH) battery and a nickel cadmium (Ni-C) battery.
d) Shown for each battery. In the figure, VBAT is the battery voltage, and ΔVBAT / Δt is the amount of change in the battery voltage per unit time.

As shown, nickel cadmium (Ni
The battery voltage of the -Cd) battery rises faster than that of the nickel-hydrogen (Ni-MH) battery and is always nickel-hydrogen (Ni-).
The MH) battery is in a fully charged (FULL charge) state while holding a battery voltage higher than the battery voltage. In this case, the amount of change in battery voltage per unit time (ΔVBAT / Δt)
However, in the period between 0 and 30, the voltage of the nickel-cadmium (Ni-Cd) battery is higher than 15.6V,
Moreover, the voltage of the nickel hydrogen (Ni-MH) battery is 15.6.
It becomes V or less. In addition, in the period in which the amount of change (ΔVBAT / Δt) of the battery voltage per unit time is between 60 and 90, the voltage of the nickel-cadmium (Ni-Cd) battery is higher than 17.8V, and the nickel-hydrogen (Ni-Cd) battery is higher. -MH) The voltage of the battery becomes 17.8 V or less.

FIG. 5 shows the change characteristics of the temperature (T) of the battery 111 with respect to the charging time (t) at the time of charging, in a nickel-hydrogen (Ni-MH) battery and nickel-cadmium (Ni-C).
d) Shown for each battery. In the figure, ΔT / Δt is the amount of change in battery temperature per unit time.

As can be seen from the figure, in the vicinity of full charge, the ΔT / Δt of the nickel hydrogen (Ni-MH) battery is increased.
Is much higher than ΔT / Δt of nickel cadmium (Ni-Cd). Here, the value of ΔT / Δt when the nickel-hydrogen (Ni-MH) battery is fully charged is shown as A, and nickel-cadmium (Ni-
Cd) The value of ΔT / Δt when the battery is fully charged is shown as B.

FIG. 6 shows the change characteristics of the voltage (V) of the battery 111 with respect to the time (t) at the time of discharging, showing the nickel hydrogen (Ni-MH) battery and the nickel cadmium (Ni-C).
d) Shown for each battery. In the figure, the area of the hatched portion corresponds to the remaining capacity of the battery when it is determined that the battery is in the low-battery state.

As can be seen from the figure, the nickel-cadmium (Ni-Cd) battery maintains a higher battery voltage than the nickel-hydrogen (Ni-MH) battery until the battery capacity decreases, but the battery remaining capacity is constant. Battery voltage drops sharply. Compared with this, the battery voltage of a nickel-hydrogen (Ni-MH) battery is gradually lowered, and nickel-cadmium (Ni-Cd)
For a while after the battery is in the low battery state, a sufficient battery voltage is maintained as a power source. Therefore, nickel-hydrogen (Ni-MH) batteries are
i-Cd) It is slower to enter the low battery state than the battery.

In this case, for example, when the amount of change (ΔVBAT / Δt) of the battery voltage per unit time is between −60 and −90, nickel cadmium (Ni—Cd).
The voltage of the battery is higher than 14.2V, and the voltage of the nickel hydrogen (Ni-MH) battery is 114.2V or less.

In the figure, the battery voltage when the nickel-cadmium (Ni-Cd) battery reaches the low battery state is shown as LB1, and nickel-hydrogen (Ni-
The battery voltage when the MH) battery reaches the low battery condition is shown as LB2. Next, with reference to FIG. 7 and FIG. 8, a battery determination process performed using the discharge characteristic of the battery 111 will be described.

As described with reference to FIG. 6, nickel hydrogen (N
The i-MH) battery and the nickel-cadmium (Ni-Cd) battery have different discharge characteristics. Therefore, a table T1 as shown in FIG. 7 is provided on the ROM 123, the battery voltage is measured at regular intervals, and the amount of change in battery voltage (ΔVBAT / Δ
By comparing the measured voltage of the battery 111 with the reference value Vb for each constant range of t), nickel hydride (Ni
-MH) batteries and nickel cadmium (Ni-Cd) batteries can be distinguished.

Here, the amount of change in the battery voltage (ΔVBAT /
The reference value Vb is set for each of four ranges in which Δt) is 0 to −30, −30 to −60, −60 to −90, and −90 or more.
The reference value Vb is, for example, the amount of change in the battery voltage (ΔVBA
T / Δt) is set to 14.2 V in the range of −60 to −90. As described with reference to FIG. 6, the value of this 14.2 V indicates that the amount of change in battery voltage (ΔVBAT / Δt) is −60.
Nickel hydrogen (Ni-MH) in the range of -90
It corresponds to approximately the intermediate value between the voltage of the battery and the voltage of the nickel-cadmium (Ni-Cd) battery.

Correspondence between the measured voltage of the battery 111 and the reference value Vb and the type of battery are as shown in FIG. That is, if the measured battery voltage VBAT is larger than the reference value Vb, nickel cadmium (Ni-C
d), and if the measured battery voltage VBAT is less than or equal to the reference value Vb, nickel hydrogen (Ni-M
H) It is determined to be a battery.

When the battery is discriminated by using the discharge characteristics as described above, the battery voltage detection circuit 16 is actually used.
It is preferable to add a current correction as shown in the following equation (1) to the battery voltage VBAT detected in step 1 and compare the correction value with a reference value. This is because a value that reduces the voltage fluctuation due to the load is used. Vc = VBAT + R · IBAT + K · T (1)

Here, Vc is the corrected battery voltage, VBAT
Is the battery voltage detected by the battery voltage detection circuit 16, R
Is the line through which the discharge current flows (battery 111 to DC-DC
Resistance of the line to the converter 13), IBAT is a battery current detected by the battery current detection circuit 17, K is a temperature constant, and T is a battery temperature detected using the thermistor 112. Next, referring to FIGS. 9 and 10, the battery 11
A battery determination process performed by using the charging characteristic of No. 1 will be described.

As described with reference to FIG. 4, nickel hydrogen (N
The charging characteristics are different between the i-MH) battery and the nickel-cadmium (Ni-Cd) battery. Therefore, a table T2 as shown in FIG. 9 is provided on the ROM 123, the battery voltage is measured at regular intervals, and the battery voltage change amount (ΔVBAT / Δ
By comparing the measured voltage of the battery 111 with the reference value Vb for each fixed range of t), the nickel-hydrogen (Ni-MH) battery and the nickel-cadmium (Ni-MH) battery can be used at the time of charging as well as at the time of discharging. -Cd) It can be distinguished from a battery.

Here, the amount of change in the battery voltage (ΔVBAT /
Δt) is in the range of 0 to 30, in the range of 30 to 60, and 60
The reference value Vb is set for each of the four ranges of 90 to 90 and 90 or more. This reference value V
b is set to 15.6 V, for example, when the amount of change in battery voltage (ΔVBAT / Δt) is in the range of 0 to 30. As described with reference to FIG. 4, the value of 15.6 V is obtained when the amount of change in battery voltage (ΔVBAT / Δt) is in the range of 0 to 30,
It corresponds to approximately the intermediate value between the voltage of a nickel-hydrogen (Ni-MH) battery and the voltage of a nickel-cadmium (Ni-Cd) battery.

Correspondence between the measured voltage of the battery 111 and the reference value Vb and the type of the battery are as shown in FIG. That is, if the measured battery voltage VBAT is larger than the reference value Vb, nickel cadmium (Ni-
Cd) The battery voltage V determined to be a battery and measured
If the value of BAT is below the reference value Vb, nickel hydrogen (Ni
-MH) Judge as a battery. In this way, the type of the battery 111 can be determined whether the battery 111 is being charged or discharged. Next, details of the full charge detection process will be described with reference to FIG. 11.

The processing routine for this full charge detection processing differs depending on whether the battery 111 is a nickel-hydrogen (Ni-MH) battery or a nickel-cadmium (Ni-Cd) battery, but it is actually used. Basically, the same processing procedure is applied to both of them, except that the detection levels are different.

Therefore, the full charge detection operation for both the nickel-hydrogen (Ni-MH) battery and the nickel-cadmium (Ni-Cd) battery will be described here by commonly using the flowchart of FIG.

First, the CPU 121 determines the thermistor 112.
The temperature detection output input from the port A3 to the port A3 is read at regular time intervals (for example, every 10 seconds) (step S31,
S32), the difference between the temperature read this time and the temperature read last time, that is, the temperature rise (ΔT) is calculated (step S3).
3). In this case, the value of the temperature rise (ΔT) is set to +1 when the temperature rises above a certain constant temperature (for example, 0.5 degrees), and remains zero when the temperature rises below that.

Next, the CPU 121 causes the temperature rise (Δ
It is checked whether or not T) has become larger than zero, and if the value of the temperature rise (ΔT) is zero, the counter value is incremented (step S35), and the processes of steps S31 to S34 are repeated. When the temperature rise (ΔT) becomes “1”, C
The PU 121 compares the counter value at that time with a detection level (ΔT / Δt) determined by the type of the battery 111.

This detection level (ΔT / Δt) is the temperature rise rate at full charge, and as described with reference to FIG. 5, in the case of a nickel hydrogen (Ni-MH) battery, the detection level (ΔT).
/ Δt) becomes the value "A", and nickel cadmium (Ni
In the case of the −Cd) battery, the value “B” lower than A is the detection level (ΔT / Δt).

In this way, the CPU 121 determines that the battery 111
Different detection levels are used depending on whether the battery is a nickel-hydrogen (Ni-MH) battery or a nickel-cadmium (Ni-Cd) battery.

When the counter value is smaller than the detection level (ΔT / Δt), that is, when the measured temperature increase rate is higher than the detection level (ΔT / Δt) temperature increase rate, the CPU 121 charges the battery 111. It is detected that the battery is in a charged state (step S38). On the other hand, when the counter value is larger than the detection level (ΔT / Δt), that is,
When the measured temperature rise rate is lower than the temperature rise rate of the detection level (ΔT / Δt), the counter value at that time is cleared (step S37), and the process returns from step S31. Next, the details of the low battery detection process will be described with reference to FIG.

The processing routine for this low battery detection processing differs depending on whether the battery 111 is a nickel-hydrogen (Ni-MH) battery or a nickel-cadmium (Ni-Cd) battery. Similarly, in practice, both are basically performed by the same processing procedure except that the detection level used is different.

Therefore, the low battery detection operation for both the nickel-hydrogen (Ni-MH) battery and the nickel-cadmium (Ni-Cd) battery will be described here by commonly using the flowchart of FIG.

First, the CPU 121 has the voltage detection circuit 16
The temperature detection output input from the port A1 to the port A1 is read (step S41), and the current detection output input from the current detection circuit 17 to the port A2 is read (step S42). Next, the CPU 121 uses the voltage detection circuit 1
Current correction is applied to the voltage V detected in 6 and V + i · R is taken as the corrected battery voltage E. Here, R is the resistance of the path at the time of discharging, and i is the current value detected by the current detection circuit 17. After that, the CPU 121 determines that the corrected battery voltage E
Is a detection level (LB) determined by the type of battery 111
Compare with.

This detection level (LB) is the battery voltage when the battery is low, and as described with reference to FIG. 6, in the case of a nickel-cadmium (Ni-Cd) battery, the detection level (LB) is the value "LB1". , NiMH (Ni-
In the case of the MH) battery, the value "LB2" lower than LB1 becomes the detection level (LB).

As described above, the CPU 121 controls the battery 111
Different detection levels are used depending on whether the battery is a nickel-hydrogen (Ni-MH) battery or a nickel-cadmium (Ni-Cd) battery.

When the corrected battery voltage E is lower than the detection level (LB1), the CPU 121 detects that the battery 111 is in the low battery state (step S4).
5). Further, the corrected battery voltage E is the detection level (LB
1) In the above cases, the processing from step S41 is repeated.

As described above, in this embodiment, the nickel cadmium (Ni-Cd) battery and the nickel-hydrogen (Ni-MH) battery have different low battery detection levels and full charge detection levels. The low-capacity state and the fully-charged state are detected, and which detection level is used to perform the detection operation depends on whether the battery used as the drive power supply is a nickel-cadmium (Ni-
Cd) battery or nickel metal hydride (Ni-MH) battery.

Therefore, low battery detection or full charge detection different for each type of battery can be executed,
It is possible to use multiple types of batteries in the same portable computer.

In this embodiment, only the case of using two types of batteries has been described, but even when three or more types of batteries are used, the detection level corresponding to the characteristics of the batteries used is similarly set. By using it, full charge detection and low battery detection can be performed normally.

Further, in this embodiment, nickel hydrogen (N
Although different detection levels were used for the i-MH) battery and the nickel-cadmium (Ni-Cd) battery, if the batteries have relatively similar characteristics, the intermediate value of the detection level that matches each is common. It is also possible to use it as a detection level.

It is needless to say that only the low battery detection level needs to be changed for batteries having different discharge characteristics, and only the full-charge detection level needs to be changed for batteries having only charge characteristics.

Further, although this power supply control method is particularly suitable for a battery-operable portable computer,
The present invention can be similarly applied to other various electronic devices as long as they can be driven by a battery.

[0083]

As described above, according to the present invention, it becomes possible to perform different low battery detection or full charge detection for a plurality of types of batteries having different characteristics, and it is possible to use a plurality of types of batteries. It will be possible.

[Brief description of drawings]

FIG. 1 is a block diagram showing a system configuration according to an embodiment of the present invention.

FIG. 2 is a flowchart illustrating a power supply control operation executed in the system of the embodiment.

FIG. 3 is a flowchart illustrating an example of a battery identification operation performed by the system of the same embodiment.

FIG. 4 is a diagram showing voltage-time charging characteristics of a battery used in the system of the example.

FIG. 5 is a diagram showing temperature-time charging characteristics of a battery used in the system of the example.

FIG. 6 is a diagram showing voltage-time discharge characteristics of a battery used in the system of the example.

FIG. 7 is a diagram showing an example of table contents referred to in a battery identification process using discharge characteristics executed in the system of the embodiment.

8 is a diagram showing the relationship between the type of battery and voltage when the table of FIG. 7 is used.

FIG. 9 is a diagram showing an example of table contents referred to in a battery identification process using charging characteristics executed in the system of the embodiment.

10 is a diagram showing the relationship between the type of battery and voltage when the table of FIG. 9 is used.

FIG. 11 is a flowchart showing an example of full charge detection processing executed by the system of the embodiment.

FIG. 12 is a flowchart showing an example of low battery detection processing executed in the system of the embodiment.

[Explanation of symbols]

11 battery pack, 12 ... power supply controller, 13 ...
DC-DC converter, 14 ... AC adapter, 15 ... Switch circuit, 16, 18 ... Voltage detection circuit, 17 ... Current detection circuit, 111 ... Battery, 112 ... Thermistor, 113 ...
Battery identification terminal, 121 ... CPU.

─────────────────────────────────────────────────── ─── Continuation of the front page (51) Int.Cl. ⁵ Identification code Office reference number FI technical display location H02J 7/10 B 9060-5G

Claims (2)

[Claims] 1. In a battery-powerable small electronic device, a determination means for determining the type of a battery mounted as a driving power source in the device among a plurality of types of batteries having different discharge characteristics, and the plurality of types of batteries. Of low battery detection levels that detect a low capacity state of the battery using a plurality of low battery detection levels that are respectively adapted to the discharge characteristics of And a means for instructing the low battery detection means which detection level is used to execute the detection operation, and performing a low battery detection operation adapted to the discharge characteristic of the battery mounted as the drive power source. Characteristic power control method. 2. In a battery-powerable small electronic device, a determination means for determining the type of a battery mounted as a drive power source in the device among a plurality of types of batteries having different charging characteristics, and the plurality of types of batteries. A full-charge detection unit that detects the full-charged state of the battery using a plurality of full-charge detection levels that are respectively adapted to the charging characteristics of the battery, and in accordance with the determination result by the determination unit, among the plurality of full-charge detection levels. And a means for instructing the full-charge detection means which detection level is to be used to perform the detection operation, and performing a full-charge detection operation suitable for the charging characteristics of the battery mounted as the driving power source. Characteristic power control method.